Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
DN280489887
Issue 02A
Approved on 2023-09-22
Single RAN Features Supported by Flexi Multiradio 10 BTS
Rel. 23R3-SR
Operating Documentation, Issue 01
© 2024 Nokia. Nokia Condential Information. Use subject to agreed restrictions on disclosure and use.
Nokia is committed to diversity and inclusion. We are continuously reviewing our customer
documentation and consulting with standards bodies to ensure that terminology is inclusive
and aligned with the industry. Our future customer documentation will be updated
accordingly.
This document includes Nokia proprietary and condential information, which may not be
distributed or disclosed to any third parties without the prior written consent of Nokia. This
document is intended for use by Nokia’s customers (“You”/”Your”) in connection with a
product purchased or licensed from any company within Nokia Group of Companies. Use this
document as agreed. You agree to notify Nokia of any errors you may nd in this document;
however, should you elect to use this document for any purpose(s) for which it is not
intended, You understand and warrant that any determinations You may make or actions
You may take will be based upon Your independent judgment and analysis of the content of
this document.
Nokia reserves the right to make changes to this document without notice. At all times, the
controlling version is the one available on Nokia’s site.
No part of this document may be modied.
NO WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
ANY WARRANTY OF AVAILABILITY, ACCURACY, RELIABILITY, TITLE, NON-INFRINGEMENT,
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, IS MADE IN RELATION TO THE
CONTENT OF THIS DOCUMENT. IN NO EVENT WILL NOKIA BE LIABLE FOR ANY DAMAGES,
INCLUDING BUT NOT LIMITED TO SPECIAL, DIRECT, INDIRECT, INCIDENTAL OR
CONSEQUENTIAL OR ANY LOSSES, SUCH AS BUT NOT LIMITED TO LOSS OF PROFIT,
REVENUE, BUSINESS INTERRUPTION, BUSINESS OPPORTUNITY OR DATA THAT MAY ARISE
FROM THE USE OF THIS DOCUMENT OR THE INFORMATION IN IT, EVEN IN THE CASE OF
ERRORS IN OR OMISSIONS FROM THIS DOCUMENT OR ITS CONTENT.
Copyright and trademark: Nokia is a registered trademark of Nokia Corporation. Other
product names mentioned in this document may be trademarks of their respective owners.
© 2024 Nokia.
2
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table of Contents
VoLTE summary of changes ........................................................................................................ 7
1 VoLTE overview and benefits ..................................................................................................... 8
2 VoLTE requirements .................................................................................................................. 11
3 VoLTE system impact ................................................................................................................ 13
VoLTE impact on other features ...................................................................................... 15
4 Introduction to VoLTE ............................................................................................................... 21
5 VoLTE UEs Power Consumption ............................................................................................... 26
6 Redirected VoLTE calls .............................................................................................................. 29
7 Specific frequency layers for VoLTE calls ............................................................................... 32
8 VoLTE protection timer trigger ................................................................................................ 36
9 Extension of RRC-connection time after handover ............................................................. 37
10 VoLTE actions triggered by a drop in voice quality ............................................................ 39
11 VoLTE improvements .............................................................................................................. 42
11.1 VoLTE UL coverage enhancement ............................................................................. 42
11.2 VoLTE robustness improvement ............................................................................... 45
11.3 Adaptive codec bit rate ............................................................................................... 48
11.4 VoLTE UL grant assignment ........................................................................................ 49
12 EN-DC setup during VoLTE services ..................................................................................... 52
13 VoLTE reference data .............................................................................................................. 53
13.1 VoLTE faults and alarms .............................................................................................. 53
13.2 VoLTE measurements, counters, and KPIs ............................................................... 53
13.3 VoLTE parameters ........................................................................................................ 59
14 Procedures related to the VoLTE functionality .................................................................. 71
14.1 Procedures for VoLTE UE power consumption ........................................................ 71
14.1.1 Activating the reduction of VoLTE UEs power consumption ..................... 71
14.1.2 Deactivating the reduction of VoLTE UEs power consumption ................ 73
14.2 Procedures for redirected VoLTE calls ...................................................................... 74
14.2.1 Activating the redirection of VoLTE calls during the E-RAB setup phase 74
14.2.2 Deactivating the redirection of VoLTE calls during the E-RAB setup phase
.................................................................................................................................... 76
14.2.3 Activating the redirection of VoLTE calls during the initial context setup
phase ........................................................................................................................ 77
14.2.4 Deactivating the redirection of VoLTE calls during the initial context setup
phase ........................................................................................................................ 80
14.3 Procedures for VoLTE actions triggered by voice drop ......................................... 81
14.3.1 Activating SRVCC to GSM ................................................................................. 81
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
3
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
14.3.2 Deactivating SRVCC to GSM ............................................................................ 82
14.3.3 Activating the inter-frequency mobility ........................................................ 83
14.3.4 Deactivating the inter-frequency mobility ................................................... 85
14.3.5 Verifying VoLTE inter-frequency handover based on VoLTE quality in
LTE3723 ................................................................................................................... 86
14.4 Procedures for VoLTE calls-specific frequency layers ........................................... 90
14.4.1 Activating the inter-frequency service-based handover ........................... 90
14.4.2 Deactivating the inter-frequency service-based handover ....................... 93
14.4.3 Activating the dedicated VoLTE inter-frequency handover ...................... 94
14.4.4 Deactivating the dedicated VoLTE inter-frequency handover .................. 96
14.4.5 Activating the service-based handover mode ............................................. 97
14.4.6 Deactivating the service-based handover mode ......................................... 99
14.5 Procedures for VoLTE protection timer trigger .................................................... 100
14.5.1 Activating the VoLTE protection timer trigger .......................................... 100
14.5.2 Deactivating the VoLTE protection timer trigger ...................................... 101
14.6 Procedures for the extension of RRC-connection time after handover .......... 102
14.6.1 Activating the extension of RRC-connection time after handover ........ 102
14.6.2 Deactivating the extension of RRC-connection time after handover ... 103
14.7 Procedures for VoLTE improvements ..................................................................... 104
14.7.1 Activating the VoLTE coverage boosting in UL scheduling ...................... 104
14.7.2 Deactivating the VoLTE UL coverage boosting .......................................... 107
14.7.3 Activating the adaptive codec bit rate ........................................................ 108
14.7.4 Deactivating the adaptive codec bit rate ................................................... 110
14.7.5 Verifying the recommended bit rate due to varying radio conditions .. 111
14.7.6 Activating VoLTE source rate-based UL assignment ................................ 116
14.7.7 Deactivating VoLTE source rate-based UL assignment ........................... 117
14.7.8 Verifying VoLTE source rate-based UL assignment .................................. 118
14.7.8.1 Making a VoLTE call in good RF conditions with LTE2774 disabled
.......................................................................................................................... 119
14.7.8.2 Making a VoLTE call in good RF conditions with LTE2774 enabled and
move to poor RF conditions ....................................................................... 120
14.8 Procedures for EN-DC setup during VoLTE services ............................................ 122
14.8.1 Activating the restrictions for EN-DC setup during VoLTE ...................... 122
14.8.2 Deactivating the restrictions for EN-DC setup during VoLTE ................. 124
14.8.3 Rollback to the LTE5542 feature solution .................................................. 125
VoLTE glossary .......................................................................................................................... 127
4
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
List of Figures
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Issue 02A.
VoLTE network architecture overview ..................................................................... 22
Target BLER and maximum number of HARQ configuration ............................... 28
Redirection of VoLTE call to other layers ................................................................ 29
QCI1 traffic steering to VoLTE preferred frequency layers ................................. 34
Normal operation mode ............................................................................................ 45
TTI bundling mode ...................................................................................................... 46
An overview of the LTE2774 feature functionality ............................................... 50
Inter-frequency handover triggered by high UL residual BLER ........................... 90
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
5
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
List of Tables
Table 1
Table 2
Table 3
Table 4
Table 5
VoLTE availability .......................................................................................................... 11
Service-based handover variants available due to LTE2503 ................................ 35
Counters introduced by the VoLTE features in LTE19 .......................................... 53
Counters introduced by the VoLTE features in LTE18 .......................................... 54
Counters introduced by the VoLTE features in RL70/RL55, LTE15A, and LTE16
........................................................................................................................................... 56
Table 6 Counters related to VoLTE features ......................................................................... 57
Table 7 Key performance indicators related to VoLTE features ........................................ 59
Table 8 Parameter introduced by the VoLTE features in 23R3 .......................................... 60
Table 9 Parameters introduced by the VoLTE features in SRAN20A ................................. 60
Table 10 Parameters introduced by the VoLTE features in LTE19 .................................... 61
Table 11 Parameters introduced by the VoLTE features in LTE18A ................................. 62
Table 12 Parameters introduced by the VoLTE features in LTE18 .................................... 63
Table 13 Parameters introduced by the VoLTE features in LTE16 .................................... 64
Table 14
Table 15
Table 16
Table 17
Table 18
Table 19
Parameters introduced by the VoLTE features in LTE15A ................................. 65
Parameters introduced by the VoLTE features in RL70/RL55 ........................... 66
Parameters related to the VoLTE features ........................................................... 68
Operation and maintenance parameters related to LTE3723 ........................... 87
Parameters configured during the test ............................................................... 113
Parameters related to the verification procedures of the LTE2774 feature
......................................................................................................................................... 119
Table 20 Parameters related to the verification procedures of the LTE2774 feature
......................................................................................................................................... 120
Table 21 The Activate the prevention of EN-DC setup during VoLTE (actVoLteNoEnDc)
parameter values and their description .................................................................. 124
6
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
VoLTE summary of changes
Find list of changes between document issues. You can navigate to respective changed topics.
Changes between issues 02 (2023-01-20) and 02A (2023-09-22)
Redirected VoLTE calls
A note informing that bearers included the E-RAB Setup Request message are present in
the E-RAB Failed Setup List information element (IE) has been added.
Changes between issues 01 (2021-11-11) and 02 (2023-01-20)
VoLTE UL coverage enhancement
The note about the configuration of the LNCELActivates VoLTE coverage
boosting improvements (actVoipCovBoostEnh) parameter has been added.
Activating the VoLTE coverage boosting in UL scheduling
The note about the configuration of the LNCELActivates VoLTE coverage
boosting improvements (actVoipCovBoostEnh) parameter has been added.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
7
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
1. VoLTE overview and benefits
VoLTE sets the framework to deliver voice calls over LTE networks using the IP Multimedia
Subsystem (IMS).
The VoLTE functionality brings the following benefits:
Improved capacity. Spectral efficiency is increased, resulting in an increase of up to twice the
number of voice calls per MHz, and three times more data throughput per MHz when
compared to non-VoLTE calls.
Voice service quality. High-definition (HD) voice service is provided, together with a guaranteed
bit rate and a shorter call setup time. HD voice uses audio frequencies that fall in the range of
50 hertz to 7 kHz and up.
Improved end user experience. Support for video calls and video chat services is introduced
The VoLTE functionality is based on the LTE10: EPS Bearers for Conversational Voice feature
which enables the use of the LTE architecture to perform voice calls. Other VoLTE features were
introduced to enhance the functionality.
LTE1406: Extended VoLTE Talk Time
This feature reduces the UE power consumption and extends the UE's battery life by using a
smaller number of the Hybrid Automatic Repeat Request (HARQ) and block error rate (BLER)
target transmissions.
LTE2108: Redirected VoLTE Call Setup and LTE2388: VoLTE Call Steering
Enhancement
These features introduce a mechanism to redirect VoLTE calls originating from LTE TDD networks
to either LTE FDD or WCDMA during the establishment phase. This solution bypasses the
limitation caused by spectrum license conditions in certain TDD networks that don't allow sending
VoLTE data packets.
8
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
LTE1127: Service Based Mobility Trigger, LTE1942: Dedicated VoLTE InterFrequency Target Frequency List, and LTE2503: Emergency Call-Based
Mobility Trigger
These features enhance the VoLTE functionality by introducing a mechanism for controlling which
target frequency layers are used for inter-frequency handovers during ongoing VoLTE calls. This
allows the control of the LTE frequency layers used by VoLTE.
LTE2430: QCI1 Establishment Triggered Protection Timer
This feature prevents the UE from going into the RRC idle mode caused by inactivity, for example,
near the start of the call setup procedure when there is no traffic on the QCI1 bearer until the call
is answered.. It saves signaling capacity and improves VoLTE setup success rate.
LTE3443: VoLTE Quality Triggered SRVCC to GSM and LTE3723: VoLTE
Quality-Triggered Inter-Frequency Mobility
These features introduce the possibility to trigger intra-LTE inter-frequency handover for voice
calls in case of a decrease in voice quality. This reduces the UE voice quality degradation by
handing over the UE (that has a QCI1 bearer activated) towards GSM or other LTE layers, for
example, in the expanded cell edge area.
LTE2098: VoLTE Uplink Coverage Boosting, LTE3692: VoLTE Robustness
Enhancements, LTE4244: VoLTE Coverage Extension by Codec Rate
Adaptation, and LTE2774: Source rate based UL grant assignment for VoLTE
These features optimize VoLTE voice quality at the cell edge and decrease the call drop rate. The
UL coverage for VoLTE UEs is also improved.
The LTE2098 feature provides better UL coverage for the UEs with QCI1 bearer established by
the introduction of:
Sensitivity-based UL resource allocation
Reduction of aperiodic Channel Quality Indicator (CQI) reporting
Increase UL receiver performance by improving noise power estimation and channel
estimation algorithms
The LTE3692 feature introduces three additional improvements to the VoLTE technology:
Audio gaps improvement, which occurs during VoLTE calls, using the proactive UL grants
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
9
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Reduce VoLTE dropped calls by reducing the transmission time interval (TTI) bundling mode
activation or deactivation handover events
Improved VoLTE retainability in TTI bundling mode using the fake discontinuous reception
(DRX) mechanism
The LTE4244 feature optimizes VoLTE call robustness for UEs in poor RF condition by
supporting adaptive codec bit rate.
The LTE2774 feature introduces the capability to adapt the UL transport block size (TBS) for a
VoLTE bearer according to the source bit rate (also called bearer measured bit rate). It
improves UL coverage and decreases resource waste by allocating the UL resources based on a
traffic measurements, when the buffer status report (BSR) isn't available. The mean opinion
score (MOS) for VoLTE calls is also improved.
LTE5388: VoLTE Without EN-DC
This feature introduces configurable restrictions for EN-DC setup during VoLTE services. This
allows for the avoidance of coverage deterioration.
CB009430: Prohibit Timer for RRC Connection Release with Mobility
This feature reduces the voice call setup time and improves the VoLTE end-user experience by
extending the time of an existing RRC connection with the UE after a handover. Therefore, the
data radio bearer creation for VoLTE is faster comparing to a situation in which the CB009430
feature is deactivated. The feature applies to TDD and FDD cells.
10
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
2. VoLTE requirements
Hardware, software, and license requirements
Equipment preconditions
Table 1: VoLTE availability
Feature
Available since
LTE1406: Extended VoLTE Talk Time
RL70/RL55
LTE2108: Redirected VoLTE Call Setup
RL70/RL55
LTE1127: Service Based Mobility Trigger
RL70/RL55
LTE2388: VoLTE Call Steering Enhancement
TL15A
LTE1942: Dedicated VoLTE Inter-frequency Target Frequency List
FL15A/TL15A
LTE2503: Emergency Call-based Mobility Trigger
FL16/TL16
LTE3443: VoLTE Quality Triggered SRVCC to GSM
FL18/TL18
LTE3723: VoLTE Quality-Triggered Inter-Frequency Mobility
SRAN20B/TL18A
LTE2430: QCI1 Establishment Triggered Protection Timer
FL15A/TL15A
LTE2098: VoLTE Uplink Coverage Boosting
FL16/TL16
LTE3692: VoLTE Robustness Enhancements
FL18/SRAN20C
LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation
FL19/SRAN20B
LTE2774: Source rate based UL grant assignment for VoLTE
FL18A/TL18A
LTE5388: VoLTE without EN-DC feature
CB009430: Prohibit Timer for RRC Connection Release with
Mobility
SRAN20A
23R3
For SRAN supported hardware and software, see Operating Documentation/Single RAN
Features/List of Features and Documents in Single RAN Operating Documentation.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
11
Sales information
For SRAN licenses information, see Operating Documentation/Single RAN System/Licenses.
12
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
3. VoLTE system impact
VoLTE impacts the following aspects of the system: interfaces, system performance, and
capacity.
Impact on interfaces
The LTE2503: Emergency Call-Based Mobility Trigger feature impacts the Uu interfaces. The
UE-EUTRA-Capability-v10c0-IEs information element (IE) is included by an UE in the
UeCapabilityInformation message to indicate that inter-frequency reference signal time
difference (RSTD) capability is supported. For more information about Uu interfaces, see 5G and
Single RAN System/Single RAN System Description/LTE-Uu interface.
Impact on network management tools
VoLTE has no impact on network management tools.
Impact on system performance and capacity
The LTE1406: Extended VoLTE Talk Time feature impacts system performance and capacity as
follows:
If QCI1 settings for the target block error rate (BLER) and the maximum number of Hybrid
Automatic Repeat Request (HARQ) transmissions aren't properly defined, there is a negative
impact on VoLTE service quality. These QCI1 settings are defined by the following parameters:
MRBTSMaximum number of HARQ transmission in UL for QCI1
(qci1HarqMaxTrUl)
MRBTSeVTT Maximum number of HARQ transmission in DL for QCI1
(qci1HarqMaxTrDl)
MRBTSUL AMC target BLER for QCI1 (qci1UlTargetBler)
MRBTSDL target BLER for QCI1 (qci1DlTargetBler)
Nokia recommends that the probability of packet loss (counted as target BLER to the power of
the maximum number of HARQ transmissions) doesn't exceed 1%.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
13
Note:
For example, if the target BLER is 9% and the maximum number of HARQ transmission
is set to 2, the probability of packet loss is 0.81% .
Higher BLER target for QCI1 bearers improves cell throughput because less robust modulation
and coding scheme (MCS) is in use. The less robust MCS, the more data can be transmitted per
physical resource block (PRB) and, thus, the packet scheduler allocates less PRBs to the voice
UEs.
The performance strongly depends on the parameter settings, defined by the SDRXDRX
short cycle (drxShortCycle) and SDRXDRX on duration timer (drxOnDuratT)
parameters.
For example, the best performing setting is when the drxShortCycle parameter is set to
40 ms and the drxOnDuratT parameter is set to 4. The LTE1406 feature brings 3.9%
performance gains in comparison to the same DRX configuration without LTE1406.
The LTE2108: Redirected VoLTE Call Setup and LTE2388: VoLTE Call Steering Enhancement
features impact system performance and capacity. The redirection of VoLTE calls to another LTE
frequency layer, or to the WCDMA layer, impacts the VoLTE quality of service. The VoLTE call setup
latencies are higher as the LTE-LTE handover or LTE-WCDMA redirection procedures cause
additional delays.
The LTE2098: VoLTE Uplink Coverage Boosting feature impacts VoLTE performance as follows:
The coverage of VoLTE UEs is improved by up to 2.5 dB when in TTI bundling mode, and by up
to 1.5 dB outside of TTI bundling mode.
Voice packet delay variation (PDV) is increased in the area of sensitivity-based resource
allocation because of the higher level of Radio Link Control (RLC) layer fragmentation.
PDV is defined as the variation in delay of uni-directional, consecutive packets which flow
between two hosts over an IP path. Low PDV is especially important for applications requiring
timely delivery of packets, such as multimedia applications, VoIP, video and so on.
VoLTE call drop and Real-Time Transport Protocol (RTP) packet loss rates are improved. See
the Table: Key performance indicators related to VoLTE features table.
Voice quality mean opinion score (MOS) is improved at the cell edge.
The LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation feature enables the
extension of VoLTE UL coverage by adapting the data rate to the recommended value, and the
reduction of voice packet loss rates in poor RF conditions. Depending on how the feature is
configured (if the LNCELConsider cell PRB usage in RBR (rbrCellPrbUsage)
parameter is set to enabled), any unused GBR capacity in the cell is affected by the data rate
14
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
recommendations. If a UE moves to better RF conditions, a higher bit rate recommendation is
sent to the UE to improve voice quality, which uses the unused GBR resources.
The LTE2774: Source Rate Based UL Grant Assignment for VoLTE feature impacts system
performance by increasing UL throughput due to optimized physical uplink shared channel
(PUSCH) PRB allocation for VoLTE users, which accommodates for non-VoLTE users.
The CB009430: Prohibit Timer for RRC Connection Release with Mobility feature improves the
system performance by reducing the voice call setup time after a handover. The eNB creates QCI1
bearers faster comparing to a situation in which the CB009430 feature is deactivated. It's
possible because the RRC connection lasts longer and the eNB doesn't need to perform the RRC
Connection Re-establishment procedure after the handover as quickly as before.
VoLTE impact on other features
List of correlations between VoLTE features and other features
The LTE10: EPS Bearers for Conversational Voice feature must be activated before activating
the following VoLTE features:
LTE1406: Extended VoLTE Talk Time
LTE1942: Dedicated VoLTE Inter-frequency Target Frequency List
LTE2503: Emergency Call-based Mobility Trigger
LTE1127: Service Based Mobility Trigger
LTE2430: QCI1 Establishment Triggered Protection Timer
LTE2098: VoLTE Uplink Coverage Boosting
LTE3692: VoLTE Robustness Enhancements
LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation
LTE2774: Source rate based UL grant assignment for VoLTE
The LTE10: EPS Bearers for Conversational Voice feature must be deactivated before activating
the following VoLTE features:
LTE2108: Redirected VoLTE Call Setup
LTE2388: VoLTE Call Steering Enhancement
The LTE1406 feature impact on other features
The LTE42: Support of DRX in RRC Connected Mode feature must be activated before
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
15
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
activating the LTE1406: Extended VoLTE Talk Time feature.
When the LTE907: TTI Bundling feature is enabled, the intra-cell handover is triggered to move
the UEs from non-transmission time interval (TTI) bundling mode to the TTI bundling mode. When
the UEs are in the TTI bundling mode, the discontinuous reception (DRX) is deactivated so the
modifications introduced with the LTE1406 feature have no effect in the network.
The LTE2108 and LTE2388 features impact on other features
The LTE1060: TDD-FDD Handover feature must be activated before activating the following
VoLTE features:
LTE2108: Redirected VoLTE Call Setup
LTE2388: VoLTE Call Steering Enhancement
The LTE7: Support of Multiple EPS Bearers feature must be activated before activating the
LTE2108 feature.
The LTE2108: Redirected VoLTE Call Setup feature is impacted by the LTE1442: Open Access
Home eNodeB Mobility feature. The home eNB targets are excluded as valid targets for the
LTE2108 feature.
The LTE1127 and LTE1942 features impact on other features
The LTE55: Inter-Frequency Handover feature must be activated before activating the following
VoLTE features:
LTE1127: Service Based Mobility Trigger
LTE1942: Dedicated VoLTE Inter-frequency Target Frequency List
The LTE1127, LTE1942, and LTE1060: TDD-FDD Handover features need to be enabled
together if an FDD-TDD handover is required for the service-based handover or for the interfrequency handover.
The LTE2503 feature impact on other features
The LTE572: IMS Emergency Sessions feature must be activated before activating the
LTE2503: Emergency Call-based Mobility Trigger feature.
The LTE2503: Emergency Call-Based Mobility Trigger feature is impacted by the LTE2351: S1Based Handover Towards CSG Cells feature. When LTE2503 is enabled, closed subscriber
16
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
group (CSG) cells are excluded as targets for a service-based handover with an emergency
Allocation and Retention Priority (ARP).
The LTE3443 feature impact on other features
The LTE873: SRVCC to GSM feature must be activated before activating the LTE3443: VoLTE
Quality Triggered SRVCC to GSM feature.
The LTE3443: VoLTE Quality-Triggered SRVCC to GSM feature impacts the following features:
LTE1170: Inter-eNB Inter-Frequency Load Balancing
The single radio voice call continuity (SRVCC) trigger introduced by the LTE3443 feature stops
the load balancing A4 measurements.
LTE1357: LTE-UTRAN Load Balancing
The SRVCC trigger introduced by the LTE3443 feature stops the load balancing B1
measurements.
LTE1841: Inter-Frequency Load Equalization
The SRVCC trigger introduced by the LTE3443 feature stops the load equalization A4
measurements.
LTE2051: Measurement-based Idle Mode Load Balancing
The SRVCC trigger introduced by the LTE3443 feature stops the idle mode load balancing A4
measurements.
The LTE3443: VoLTE Quality-Triggered SRVCC to GSM feature is impacted by the LTE3290:
SRVCC Trigger Enhancement feature. The LTE3443 SRVCC trigger is delayed if the LTE3290
delay timer (LNBTS SRVCC delay timer (srvccDelayTimer)) is running. The delay
depends on the srvccDelayTimer parameter setting.
The LTE3723 feature impact on other features
The LTE1060: TDD-FDD Handover feature must be activated before activating the LTE3723:
VoLTE Quality-Triggered Inter-Frequency Mobility feature.
The LTE3723: VoLTE Quality-Triggered Inter-Frequency Mobility feature impacts the following
features:
LTE1127: Service-Based Mobility Trigger
The VoLTE quality trigger introduced by the LTE3723 feature stops the service-based A4
measurements.
LTE1170: Inter-eNB Inter-Frequency Load Balancing
The VoLTE quality trigger introduced by the LTE3723 feature stops the load balancing A4
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
17
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
measurements.
LTE1357: LTE-UTRAN Load Balancing
The VoLTE quality trigger introduced by the LTE3723 feature stops the load balancing B1
measurements.
LTE1834: eMBMS Service Continuity
The VoLTE quality trigger introduced by the LTE3723 feature stops the Multimedia BroadcastMulticast Services (MBMS) A4 measurements.
LTE1841: Inter-Frequency Load Equalization
The VoLTE quality trigger introduced by the LTE3723 feature stops the load equalization A4
measurements.
LTE2051: Measurement-based Idle Mode Load Balancing
The VoLTE quality trigger introduced by the LTE3723 feature stops the idle mode load
balancing A4 measurements.
LTE4056: Cat-M1: VoLTE Support (Phase-I)
The LTE3723 functions aren't supported for Cat-M UEs.
LTE2612: ProSe Direct Communications for Public Safety
The voice quality triggered inter-frequency mobility isn't used for UEs with sidelink, which is the
process of communication between an in-coverage UE and other UEs that are in-coverage or
out-of-coverage using ProSe device-to-device (D2D) communication.
LTE4259: Increased Carrier Monitoring in Connected Mode
Event priority measurement for reference signal received power (RSRP) or reference signal
received quality (RSRQ) is defined in the LTE4259 feature. In this case, the priority is applicable
for voice quality triggered A3 and A5 events.
The LTE3723: VoLTE Quality-Triggered Inter-Frequency Mobility feature is impacted by the
following features:
LTE2551: RSRQ-Based A5
If the LTE2551 feature is enabled and the A5 event is triggered by the VoLTE quality trigger,
then the newly introduced A5 RSRQ measurements are used. If any A5 event is already
configured due to the DL trigger and the VoLTE quality trigger is started, the A5 event doesn't
change. If the DL trigger is turned off while VoLTE quality trigger is still on, then the A5 RSRQ is
used and configured with the maximum value of the LNHOIF RSRQ A5 interfrequency threshold1 (threshold3RsrqInterFreq) threshold.
LTE3127: SRVCC to GSM Measurement Optimization
If the LTE3127 feature is enabled, then the VoLTE quality triggered inter-frequency
measurements are stopped when the VoLTE quality or A2 event triggers the SRVCC to the
GSM measurement.
18
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
The LTE2098 feature impact on other features
The following features must be activated before activating the LTE2098: VoLTE Uplink
Coverage Boosting feature:
LTE11: Robust Header Compression
LTE1034: Extended Uplink Link Adaptation or LTE1495: Fast Uplink LinkAdaptation
The LTE2098: VoLTE Uplink Coverage Boosting feature impacts the following features:
LTE907: TTI Bundling
The number of physical resource blocks (PRBs) that can be allocated to a UE in the
transmission time interval (TTI) bundling mode can be lower than three with the introduction of
the LTE2098: VoLTE Uplink Coverage Boosting feature.
LTE571: Controlled Uplink Packet Segmentation
When the LTE2098: VoLTE Uplink Coverage Boosting feature is active, the UL packet
segmentation algorithm can't be controlled for UEs with limited VoLTE coverage.
The LTE3692 feature impact on other features
The LTE42: Support of DRX in RRC Connected Mode feature must be activated before
activating the LTE3692: VoLTE Robustness Enhancements feature.
The LTE4244 feature impact on other features
The LTE587 Multiple GBR EPS Bearers per UE feature must be activated before activating the
LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation feature.
The LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation feature impacts the
LTE907: TTI Bundling feature. For a UE in the TTI Bundling mode, an unsolicited message in UL
with recommended bit rate and UE access network bit rate recommendation queries are
supported. The usage of TTI bundling mode is reduced if the UE follows the bit rate
recommendations of the eNB by adapting the data rate of the audio codec.
The LTE2774 feature impact on other features
The LTE2774: Source rate based UL grant assignment for VoLTE feature impacts the following
features:
LTE1321: eRAB Modification - GBR
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
19
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
With the LTE2774 feature enabled, if the new S1 Application Protocol (S1AP) UL GBR is higher
than necessary for the VoLTE bearer, the value of the calculated voice packet doesn't change
when the UL GBR for a VoLTE bearer is modified on the S1AP interface.
LTE1929: UL Semi-Persistent Scheduling
If the LTE2774 feature is enabled, the size of the UL semi-persistent grant given to VoLTE
UEs is modified according to the calculated voice packet size that takes into account the VoLTE
bearers measured UL source bit rate.
The LTE5388 feature impact on other features
The LTE4088: LTE-NR Dual Connectivity Option 3X feature must be activated before activating
the LTE5388: VoLTE without EN-DC feature.
The LTE5388: VoLTE without EN-DC feature is impacted by the LTE4193: Dynamic Trigger for
LTE-NR DC Option 3x feature. When LTE4193 is enabled, if the UE works in non-EN-DC mode,
then the EN-DC restricted VoLTE bearer setup results in the deactivation of the B1-NR
measurements. If the UE works in the EN-DC mode, then the EN-DC restricted VoLTE bearer
setup results in secondary cell group (SCG) split bearer take back.
The CB009430 feature impact on other features
The CB009430: Prohibit Timer for RRC Connection Release with Mobility feature is impacted
by the LTE1617: RLF Triggered Handover and LTE-M Mobility features. The LTE1617 feature
enables handovers caused by a radio link failure and LTE-M Mobility features enable Cat-M UE
handovers. With the CB009430 feature activated, during any of these handovers, the eNB
doesn't send information to the target cell about how much time elapsed since the last QCI1
bearer for UE was released.
20
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
4. Introduction to VoLTE
VoLTE technology enables voice calls using an IP-based network architecture.
The VoLTE functionality is based on the LTE10: EPS Bearers for Conversational Voice feature. It
enables the use of LTE architecture to perform voice calls. For more information, see LTE10: EPS
Bearers for Conversational Voice.
When a VoLTE call is being set up, a dedicated bearer with QCI1 is set up for the voice call. Data
radio bearers (DRBs) are used for carrying user data. There are two types of DRBs: default bearers
(which are non-GBR) and dedicated bearers (which are GBR). A default bearer is assigned to an LTE
UE the first time it attaches to the network. For more information, see Radio Bearers Overview.
A VoLTE call requires an Evolved Packet System (EPS) and an IP Multimedia Subsystem (IMS). The
EPS connects the subscriber to the packet core that carries the voice traffic. The IMS provides the
voice capability. It contains all the core network elements necessary to provide multimedia
services.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
21
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Figure 1: VoLTE network architecture overview
The network elements and functions of the VoLTE network architecture are:
mobility management
entity (MME)
The MME is the main signaling node in the Evolved Packet Core (EPC).
It is responsible for initiating paging and authentication of the mobile
device. It retains location information at the tracking area level for
each user and then selects the appropriate gateway during the initial
registration process.
The MME provides the control plane function for mobility between
LTE and 2G/3G access networks.
Serving Gateway (SGW)
The SGW routes and forwards user data packets, and serves as the
mobility anchor for the user plane during the inter-eNodeB
handovers. It also acts as the anchor for mobility between LTE and
other 3GPP technologies
For idle state UEs, the SGW terminates the downlink (DL) data path
and triggers paging when the DL data arrives for the UE.
22
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Packet Data Network
Gateway (PGW)
The PGW provides connectivity between the UE and external packet
data networks. It provides the entry and exit point of traffic for the
UE. An UE can have simultaneous connectivity with more than one
PGW for accessing multiple Packet Data Networks (PDN).
The PGW performs policy enforcement, packet filtering for each user,
charging support, lawful interception, and packet screening.
policy and charging rules
function (PCRF)
The PCRF is responsible for implementing the charging policy and for
the Quality of Service (QoS) negotiation with external packet data
networks.
Call Session Control
Function (CSCF)
The CSCF is responsible for establishing, monitoring, supporting and
releasing multimedia sessions.
It can be divided into three distinct roles:
• Proxy CSCF (P-CSCF)
• Serving CSCF (S-CSCF)
• Interrogating CSCF (I-CSCF)
Media Gateway (MGW)
The MGW terminates bearer channels from a switched circuit network
and media streams from a packet network (for example, (real-time
transport protocol) RTP streams in an IP network). It can support
media conversion, bearer control and payload processing using
codecs, echo cancellers, and other on-board resources.
Media Gateway Control
Function (MGCF)
The MGCF controls media gateways, converts codecs where
necessary, and can serve as a breakout to a circuit-switched network.
In case MGCF works as a breakout to circuit switched (CS) network, it
is also responsible for managing the conversion of signaling
messages, converting session initiation protocol (SIP) messaging to
the Bearer Independent Call Control (BICC), and integrated services
digital network (ISDN) User Part (ISUP) protocols used in legacy
systems.
Media Resource Function
(MRF)
The MRF consists of the Media Resource Function Processor (MRFP)
and the Media Resource Function Controller (MRFC).
The MRF is used by the IMS application servers and I/S-CSCFs to
provide media plane processing independent of application types,
under the control of application server as well as basic media
processing functions to CSCFs.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
23
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
home subscriber server
(HSS)
The HSS is a network database that holds both static and dynamic
data elements related to subscribers. It provides user profile
information to the MME and IMS core during UE attach and IMS
registration.
Telephony Application
Server (TAS)
The TAS is an IMS Application Server built according to the IMS core
architecture, which provides a set of services for VoLTE. It provides
feature parity with mobile CS voice and VoLTE and supports an IMS
centralized service.
public land mobile network
(PLMN) / Public Switched
Telephone Network (PSTN)
A PLMN is any wireless communication system intended for use by
terrestrial subscribers. Such a system can stand alone, but often it is
interconnected with a fixed system such as the PSTN.
The PSTN provides infrastructure and services for public
telecommunication. The PSTN is the aggregate of the circuit-switched
telephone networks that are operated by national, regional, or local
telephony operators. These consist of telephone lines, fiber optic
cables, microwave transmission links, cellular networks,
communications satellites, and undersea telephone cables, all
interconnected by switching centers, which allow most telephones to
communicate with each other.
Mobility management events
Mobility management refers to a set of procedures that assure service continuity in case of a
moving UE. These procedures are used in VoLTE features to ensure connectivity and voice quality
while a UE is moving. These procedures are triggered by certain events:
A1
The A1 event is triggered when the serving cell becomes better than
the specified threshold. The threshold is configurable on the eNB.
This event is used to stop measurements for inter-frequency and
inter-RAT handovers in good radio conditions.
A2
The A2 event is triggered when the serving cell becomes worse than
the specified threshold. The threshold is configurable on the eNB.
This event is used to start measurements for inter-frequency and
inter-RAT handovers in poor radio conditions.
24
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
A3
The A3 event is triggered when the neighbor cell becomes better
than the serving cell. The threshold is configurable on the eNB. This
event is used for intra-frequency handovers, but may also be used
for inter-frequency handovers.
A4
The A4 event is triggered when the neighbor cell becomes better
than the threshold. The threshold is configurable on the eNB. This
event is used for inter-frequency handovers. An A4 event comes
after the A2 event occurs, and is then triggered if the A1 event does
not occur.
A5
The A5 event is triggered when two conditions are met - the serving
cell becomes worse than threshold 1, and the neighbor cell becomes
better than threshold 2. Two thresholds are used for this event - one
is for the serving cell, the second for the neighbor cell. The thresholds
are configurable on the eNB. This event is used for inter-frequency
handovers if the A3 and A4 are not configured.
B1
The B1 event is triggered when a neighboring inter-RAT cell becomes
better than the threshold. The thresholds are configurable on the
eNB. This event type is used for inter-RAT handovers (LTE to WCDMA
or GSM). A B1 event comes after the A2 event occurs, and is then
triggered if the A1 event does not occur. Note that inter-RAT A1 and
A2 thresholds are different from inter-frequency A1 and A2
thresholds.
B2
The B2 event is triggered when two conditions are met - the serving
cell becomes worse than threshold 1, and a neighboring inter-RAT cell
becomes better than threshold 2. Two thresholds are used - one for
the serving cell, and the second for the neighbor cell. These
thresholds are configurable on the eNB. This event is used for interRAT handovers if B1 is not configured. A B2 event comes after the A2
event occurs, and is then triggered if the A1 event does not occur.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
25
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
5. VoLTE UEs Power Consumption
The LTE1406: Extended VoLTE Talk Time feature is introduced to reduce the battery
consumption of the UEs with ongoing VoLTE call.
The LTE1406: Extended VoLTE Talk Time feature reduces the UE power consumption for VoLTE
calls. It allows to align the discontinuous reception (DRX) on duration time with the scheduling
request (SR) timing and limits the maximum number of Hybrid Automatic Repeat Request (HARQ)
retransmissions for QCI1 traffic. This results in less DRX active time for retransmissions.
When either the LTE42: Support of DRX in RRC Connected Mode or the LTE585: Smart DRX
features are activated, then the QCI1 is associated with DRX profile 2 (if the LTE42 feature is
activated) or DRX smart profile 2 (if the LTE585 feature is activated). This defines the default DRX
settings. For more information on how to optimally configure DRX, see the LTE42: Support of
DRX in RRC Connected Mode and LTE585: Smart DRX feature descriptions.
The LTE1406 feature is activated with the LNCEL Activate extended VoLTE talk
time (actQci1eVTT) parameter.
When the LTE1406 feature is activated and the measurement gaps for the UE are set, the
feature checks the DRX profile of the VoLTE call and configures the SR according to the periodicity
defined for the VoLTE DRX profile 2. The adjustment of the SR is done based on the long DRX
cycle, defined by the LNCEL DRX long cycle (drxLongCycle) parameter. With this feature,
the UE doesn't enter DRX active state in the middle of DRX cycle to send the SR. As a result, a
longer DRX sleeping time contributes to higher battery savings.
When the LTE1406 feature is activated, the eNB applies automatically the following changes with
the establishment of a QCI1 bearer:
In case of carrier aggregation cells, the eNB doesn't configure the secondary cell (SCell) for the
UE. If the UE is already connected to the primary cell (PCell) and has established an SCell, the
eNB checks the UL and DL throughputs.
The UL and DL throughput thresholds are calculated by the multiplication of the guaranteed
bit rate of the first QCI1 and the LNCEL Multiplication factor for the QCI1
traffic in uplink (qci1ThroughputFactorUl) and Multiplication factor
for the QCI1 traffic in downlink (qci1ThroughputFactorDl) parameters.
If the UL and DL throughputs don't exceed respective threshold, the SCell is deconfigured.
If the UL or DL throughput exceeds the respective threshold, the SCell is maintained.
If QCI1 UL and DL throughput thresholds are not exceeded, it means that the amount of
26
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
transmitted non-voice data is negligible and therefore there is no need of having an SCell
configured. Turning the SCell off extends the battery life of the UE.
In case of FDD, when the UL and DL throughputs don't exceed the respective QCI1 throughput
threshold and if the sounding reference signal (SRS) is active, the packet scheduler doesn't
allocate any SRS resources to the UE. If there are already some SRS resources allocated to the
UE, these resources are released and they are available for other UEs in the cell. This action
improved both efficient SRS use and brings battery saving.
If the UL and DL throughputs don't exceed the respective QCI1 throughput threshold, the
packet scheduler allocates scheduling request (SR) resources according to the QCI1-defined
periodicities based on the long DRX cycle. The SR is reconfigured only if the standard SR
periodicity, defined by the MPUCCH_FDD/MPUCCH_TDD Cell scheduling request
periodicity (cellSrPeriod) parameter, is shorter than the long DRX cycle.
The eNB reconfigures the target block error rate (BLER) and the maximum number of HARQ
according to the LNCEL Extended VoLTE Talk Time Configuration for QCI1
(qci1eVTTConfig) parameter if the UL and DL throughputs don't exceed the respective
QCI1 throughput threshold. If during the QCI1 bearer lifetime, the UE has high data throughput
(above throughput threshold), then the eNB changes back the maximum number of HARQ and
target BLER to the standard configuration used for non-QCI1 bearers. The UE stays in the
standard configuration at least for the duration of the LNCEL HARQ and BLER
reconfiguration timer for QCI1 (qci1ReconStopTimer) parameter.
Only three reconfigurations (transitions between dedicated QCI settings) are allowed during a
single call. If this limit is reached, the UE uses the standard target BLER and HARQ settings for
the duration of QCI1 bearer because this UE is considered to have unstable QCI1 traffic. In this
case, it's better to leave the standard configuration because it ensures that the cell isn't
blocked by the UEs that mostly send data with a low BLER rate (which costs to have high use of
physical resource block (PRBs) by a low modulation and coding scheme (MCS) index).
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
27
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Figure 2: Target BLER and maximum number of HARQ configuration
Once the UE releases the QCI1 bearer, the eNB:
reconfigures the target BLER and the maximum number of HARQ retransmissions back to
standard values defined for all non-QCI1 bearers.
tries to reconfigure the SCell to the UE.
tries to provide new SRS resources to the UE in case of FDD.
reconfigures the SR periodicity according to the defined standard periodicities used for all nonQCI1 bearers.
The LTE1406 feature can't work together with the LTE2388: VoLTE Call Steering Enhancement
feature.
28
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
6. Redirected VoLTE calls
The LTE2108: Redirected VoLTE Call Setup and LTE2388: VoLTE Call Steering Enhancement
features are introduced to redirect VoLTE calls from LTE TDD to LTE FDD or WCDMA.
There are networks in which the spectrum license conditions don't allow sending VoLTE data
packets on TDD frequencies. To make VoLTE calls possible in such networks, these data packets
are redirected during the establishment phase to other layers:
The eNB attempts to perform the handover to an FDD layer.
If the handover isn't successful or can't be performed, the VoLTE data packets are redirected
to a WCDMA layer.
Figure 3: Redirection of VoLTE call to other layers
The following features are used to redirect the VoLTE call:
LTE2108, when the QCI1 is requested during E-UTRAN Radio Access Bearer (E-RAB) setup
procedure
Note:
If there is at least one bearer with QCI1 in the E-RAB Setup Request message, all
bearers included in this request are present in the E-RAB Failed Setup List
information element (IE).
LTE2388, when the QCI1 is requested during initial context setup procedure
These features are implemented in case the LTE TDD network doesn't support the VoLTE
functionality, but is overlapped by the LTE FDD network, which supports VoLTE. Such a situation
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
29
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
can occur when the LTE10: EPS Bearers for Conversational Voice feature is enabled in the LTE
FDD network (the LNBTS_FDD Activate support of conversational voice
bearer (actConvVoice) parameter is set to true) but not in the LTE TDD network (the
LNBTS_TDD Activate support of conversational voice bearer
(actConvVoice) parameter is set to false). It means that when a UE requests the voice call in
the LTE TDD network with the LTE10 feature not activated, the voice call isn't established unless
the LTE2108 and LTE2388 features are activated.
The eNB starts the redirect timer, configurable in the LNCEL_TDD Redirected VoLTE call
setup supervision timer (voLteRedirTimer) parameter and begins a forced servicebased handover. Prior to the handover procedure, the A4 event-based measurements of the
potential target cells are performed. Upon receiving the A4 measurement report, the target cell
list is analyzed to choose the best target cell for the VoLTE call setup. A target cell for a handover
preparation is selected only if the UE measurements are above the reference signal received
power (RSRP) and reference signal received quality (RSRQ) thresholds, defined by the following
parameters:
LNHOIF Inter-freq. service based threshold RSRP target filter
(thresholdRsrpIFSBFilter)
LNHOIF Inter-freq. service based threshold RSRQ target filter
(thresholdRsrqIFSBFilter)
Another condition for selecting the target cell is that the target cell must not be blacklisted. A
target cell can be temporarily blacklisted for a handover, for example, when the handover
preparation supervision timer expires after several consecutive handover preparation attempts.
The preparation supervision timer is defined by the LNBTS Supervision timer
preparation intra LTE X2 HO (tX2RelocPrep) parameter.
If a handover to the FDD layer isn't successful, the eNB attempts a redirection to a WCDMA layer,
by reusing the target frequencies configured for circuit-switched fallback (CSFB) from the
LTE562: CSFB to UTRAN or GSM via Redirect feature.
The LTE2108 feature is activated with the LNBTS_TDD Activate redirect VoLTE
(actRedirVoLte) parameter.
The LTE2388 feature is activated with the LNBTS_TDD Activate VoLTE call steering
(actVoLteCallSteering) parameter.
The LTE2108 feature is a precondition to activate the LTE2388 feature.
The following VoLTE features must be deactivated before activating LTE2108:
LTE1127: Service Based Mobility Trigger
LTE1942: Dedicated VoLTE Inter-frequency Target Frequency List
30
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
The LTE1406: Extended VoLTE Talk Time feature must be deactivated before activating the
LTE2388 feature.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
31
7. Specific frequency layers for VoLTE calls
The LTE1127: Service Based Mobility Trigger, LTE1942: Dedicated VoLTE Inter-Frequency
Target Frequency List, and LTE2503: Emergency Call-Based Mobility Trigger features allow to
define dedicated frequencies as VoLTE preferred targets.
A high number of VoLTE UEs in the cell degrades total cell throughput and limits the throughput
for other services. Due to lower priority, resources for non-GBR traffic are limited. To overcome
such situations, you can configure the network with specific frequency layers for VoLTE calls.
With the LTE1127 feature enabled (the LNBTS Activate inter-frequency service
based handover (actInterFreqServiceBasedHo) parameter is set to true), the eNB
starts an A4-based inter-frequency measurement for service-based handover for all UEs with
established QCI bearers. The UEs enter a cell through handover or RRC connection reestablishment procedure, and don't have the A2/A3/A5 inter-frequency or B1/B2 inter-RAT
measurements activated. The eNB configures and activates a UE for A4 measurements with
specific service-based handover frequency layers selected according to an assigned mobility
profile, either MOPR or MODPR.
Note:
If the LTE490: Subscriber Profile Based Mobility feature is deactivated (LNBTS
Activate selective mobility profiles (actSelMobPrf) is set to false),
then the default mobility profile MODPR must be created for the configuration of VoLTE
target layers.
The A4 event supervision timer and the LNCEL Inter-freq. service based HO retry
timer (iFServiceBasedHoRetryTimer) timer are started (for service-based handover).
Upon receiving the A4 reports, the target cell list is processed to choose the best target cell for
service-based handover. The eNB periodically reactivates the service-based handover A4-based
measurements if the handover isn't executed after the A4 measurement report is received. When
the eNB doesn't receive the A4 measurement report, it deactivates A4-based inter-frequency
measurements after the A4 event supervision timer expires. The eNB also periodically reactivates
the service-based handover A4-based measurements after the
iFServiceBasedHoRetryTimer retry timer expires.
The specific VoLTE target frequency layers that are preferred for service-based handover are
configured using the MOPR Frequency layer list for VoLTE service based HO
32
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
(freqLayListServiceBasedHo) parameter.
When the LTE1942 feature is enabled (the LNBTS Activate dedicated VoLTE interfrequency handover (actDedVoLteInterFreqHo) parameter is set to true), VoLTE calls
can be moved to a particular frequency layer not only through service-based handover upon QCI1
bearer establishment as with the LTE1127 feature, but also during coverage-based handover and
load-based handover.
The specific VoLTE target frequency layers for inter-frequency mobility during VoLTE calls are
configured using the MOPR Frequency layer list for VoLTE service based HO
(freqLayListServiceBasedHo) parameter. When LTE1942 is activated, the list also
includes VoLTE target frequencies for service-based handover.
During the target cell selection, the eNB prevents the VoLTE UE from being handed over to a
target cell that isn't located on a dedicated VoLTE target frequency layer.
Note:
To make inter-frequency VoLTE handovers possible, at least the default mobility profile
(MODPR) must be created with the LTE1942 list.
The LTE2503: Emergency Call-based Mobility Trigger feature is an enhancement of the
LTE1127: Service Based Mobility Trigger feature. The LTE2503 feature introduces an additional
filter criterion for the service-based handover based on allocation and retention priority (ARP).
Without the LTE2503 feature, all the UEs with QCI1 bearer established (including those with
emergency call) are candidates for service-based handover. With the LTE2503 feature,
candidates for service-based handover can be limited to the UEs with VoLTE emergency calls, or
to the UEs with emergency calls that don't support inter-frequency reference signal time
difference (RSTD) measurements. The RSTD measurement is necessary to define the relative
timing between two cells, the reference cell and a measured cell. Also, it's necessary for Observed
Time Difference of Arrival (OTDOA) calculations.
The eNB tries to move, through inter-frequency handover, all the UEs with an established QCI1
bearer to the preferred frequency layers, if they provide sufficient coverage.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
33
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Figure 4: QCI1 traffic steering to VoLTE preferred frequency layers
UEs are selected as candidates for service-based handover using different modes. The LNCEL
Service based handover mode (sbHoMode) parameter is used to configure in which
mode the UEs are selected. There are three modes available:
all, when all the UEs with QCI1 are candidates for service-based handover.
ec, when all the UEs with QCI1 and emergency ARP are candidates for service-based handover.
ec_no_rstd, when all the UEs with QCI1 and emergency ARP that don't indicate support for
RSTD in their UE capabilities are candidates for service-based handover.
For the last two modes (ec and ec_no_rstd), the eNB starts the service-based handover similar
to the one from the LTE1127 feature with the following differences:
The HandoverRequest message is sent with the Time Critical Handover cause
message.
The source eNB accepts partial admission by the target eNB, but the service-based handover
with an emergency ARP is performed only if all bearers (not only QCI1 but other as well) with an
emergency ARP were accepted by the target eNB.
The UEs are moved using the available service-based handover variants:
34
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 2: Service-based handover variants available due to LTE2503
Service-based handover variants
Post-conditions
The service-based handover with the all mode (a
UE has established QCI1 bearer)
A UE is handed over to a target cell from a
frequency layer configured for a servicebased handover.
The service-based handover with the ec mode
(QCI1 with emergency ARP)
A UE is handed over to a target cell from a
frequency layer configured for a servicebased handover.
The service-based handover with the
ec_no_rstd mode (QCI1 with emergency ARP
and a UE not supporting RSTD capability)
A UE is handed over to a target cell from a
frequency layer configured for a servicebased handover.
The service-based handover with the ec mode
(QCI1 without emergency ARP)
A UE stays in a serving cell.
The service-based handover with the
ec_no_rstd mode (QCI1 without emergency
ARP or a UE supporting RSTD capability)
A UE stays in a serving cell.
The service-based handover with the ec mode
(QCI1 with emergency ARP, partial admission by
the target eNB, but all bearers with emergency
ARP are accepted)
A UE is handed over to a target cell from a
frequency layer configured for a servicebased handover.
The service-based handover with the
ec_no_rstd mode (QCI 1 with emergency ARP,
partial admission by the target eNB, and not all
bearers with emergency ARP are accepted)
If there are no more target cells on a target
cell list to be evaluated by the eNB, then a
UE stays in a serving cell. Otherwise, the
eNB tries to perform a service-based
handover with an emergency ARP to the
next target cell on the target cell list.
The LTE2503 feature is activated together with the LTE1127 feature (the LNBTS Activate
inter-frequency service based handover (actInterFreqServiceBasedHo)
parameter is set to true.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
35
8. VoLTE protection timer trigger
The LTE2430: QCI1 Establishment Triggered Protection Timer feature allows keeping the
VoLTE UE in the RRC-connected mode even if there is no activity, for example, near the start of
the call setup procedure when there is no traffic on the QCI1 bearer until the call is answered. This
prevents the UEs going to the RRC idle mode when there is potentially no traffic on any of the
bearers or on the S1 link.
The LTE2430 feature introduces a configurable QCI1 protection timer defined by the LNCEL
QCI1 protection timer (qci1ProtectionTimer) parameter. The timer is started or
restarted by the eNB every time the QCI1 is established.
The timer must be configured to a value higher than the LNCEL Inactivity timer
(inactivityTimer) timer, which defines the time period of the UE inactivity. The timer setting
is linked to the expected time period for the end user to answer the call when the phone is
ringing.
If the protection timer and all other inactivity timers expire before the ringtone is finished, the UE
is released to the RRC idle mode. In case the end user call is terminated, and no other QCI1
related to that UE is established, then the QCI1 protection timer stops.
The LTE2430 feature is activated with the LNBTS Activate RRC connected mode
while no activity (actRrcConnNoActivity) parameter.
36
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
9. Extension of RRC-connection time after handover
The CB009430: Prohibit Timer for RRC Connection Release with Mobility feature allows the
eNB to send to the target cell the information about how much time elapsed since the last QCI1
bearer for the UE was released. This information is used in the target cell to prolong the ongoing
RRC connection after a handover.
The CB009430 feature enables the eNB to transmit information to the target cell about how
much time elapsed since the last QCI1 bearer for UE was released. This information is used after
the handover to calculate the remaining time of RRC connection with the UE. The eNB of the
target cell maintains the ongoing RRC connection for at least the duration of the calculated time.
An ongoing RRC connection shortens the UE waiting time for the VoLTE call setup.
You activate the CB009430 feature per cell by using the LNCEL Activate forwarding of
elapsed time of prohibit timer for RRC Connection Release
(actRrcConnRelDelayForwarding) parameter. For more information, see Activating the
extension of RRC-connection time after handover.
During the activation of the CB009430 feature, you need to configure the LNCEL QCI1 RRC
Connection Release prohibit timer (qci1RrcRelDelayTimer) parameter. After
the last QCI1 bearer release, the eNB uses this parameter value to set and start the control plane
(C-plane) inactivity timer automatically. Before the C-plane inactivity timer expires, the eNB
performs an intra- or inter-eNB handover. During the handover, the eNB sends information about
how much time elapsed since the last QCI1 bearer for the UE was released to the target cell. The
elapsed time is then compared with the time set with the qci1RrcRelDelayTimer
parameter. The comparison leads to one of two results:
The time period is shorter than the one you set with the qci1RrcRelDelayTimer
parameter in the target cell.
The eNB sets the C-plane inactivity timer to a value equal to the difference between the value
of the qci1RrcRelDelayTimer parameter and the elapsed time since the last QCI1 bearer
was released. The eNB starts the C-plane inactivity timer after the RRC Connection
Reconfiguration procedure is complete. The RRC connection isn't released until the C-plane
inactivity timer expires. The RRC connection continues after the C-plane inactivity timer expires
if there are other eNB timers that are ongoing.
The time period is equal or longer than the one you set with the qci1RrcRelDelayTimer
parameter in the target cell.
The eNB doesn't start the C-plane inactivity timer for this UE.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
37
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
The eNB doesn't send information about the time that elapsed since the last QCI1 bearer release
from the source cell to the target cell during:
the handover caused by a radio link failure.
the RRC Connection Re-establishment procedure.
the forced service-based handover.
the Cat-M UE handover.
Both cells involved in the handover need to have the CB009430 feature activated. The feature
applies only to Nokia cells.
38
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
10. VoLTE actions triggered by a drop in voice quality
The LTE3443: VoLTE quality triggered SRVCC to GSM and LTE3723: VoLTE QualityTriggered Inter-Frequency Mobility features introduce the possibility to trigger a single radio
voice call connectivity (SRVCC) to GSM, and to trigger intra-LTE inter-frequency handover for
voice calls in case of a degradation in voice quality.
Voice quality is determined by checking voice gaps, in DL and UL, and final residual block error rate
(BLER).
The voice break period, also called a voice gap, refers to any of the following:
Any unexpected periods of voice transmission discontinuities, when the UE neither sends nor
receives any voice data.
A period of continued QCI1 UL PDCP packet losses or discards occurring in the eNB. This is
defined as a UL voice break.
A period of continued QCI1 DL PDCP packet losses or discards occurring in the eNB. This is
defined as a DL voice break.
All intended breaks (such as call forwarding, on-hold, or silence suppression) are not considered as
a voice break period.
The UL residual BLER criterion is used as an additional voice quality trigger. The residual BLER is a
BLER after maximum number of hybrid automatic repeat request (HARQ) transmissions. This
criterion is based on the definition of residual BLER after maximum number of HARQ
retransmissions introduced with the LTE2493: Enhanced VoLTE Performance Monitoring
feature.
To detect voice quality degradation, the voice breaks are measured and compared to the
following thresholds that are set by the operator:
VOLTEQUALPR Bad quality UL voice gap threshold
(badQualityULGapThres)
VOLTEQUALPR Bad quality DL voice gap threshold
(badQualityDLGapThres)
VOLTEQUALPR Bad quality residual BLER threshold
(badQualityRBlerThres)
VOLTEQUALPR Good quality UL DL voice gap threshold
(goodQualityGapThres)
VOLTEQUALPR Good quality residual BLER threshold
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
39
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
(goodQualityRBlerThres)
Counting the period of consecutive successful transmissions of QCI1 UL/DL PDCP packets and
comparing it against the thresholds above determine whether the UE is back in the good voice
quality state or not.
If the final residual BLER exceeds the thresholds above for a certain duration, the UE enters the
low voice quality state. If the final residual BLER drops again below the threshold for a certain
duration, the UE is restored to a good voice quality state.
VoLTE quality measurements
The LTE3443: VoLTE quality triggered SRVCC to GSM and LTE3723: VoLTE Quality-Triggered
Inter-Frequency Mobility features are used in case of voice quality degradation.
Single radio voice call continuity (SRVCC) is a mechanism to hand over UEs that have a QCI1 bearer
activated when changing from an LTE cell to a WCDMA or GSM cell. The voice bearer, that is
subject to a handover, is served through the circuit-switched (CS) domain on the WCDMA or the
GSM side. SRVCC is always executed without a packet-switched handover support (it means that
the established non-voice bearers aren't handed over to WCDMA or GSM).
Voice quality measurements are done by the eNB along with the DL radio interface quality and
power measurements delivered by the UE. If the voice quality doesn't meet the operator-defined
requirements, depending on the features available, one of the two actions occur:
In case of LTE3443, the GSM neighbor cell measurements are started. If the UE reports cells
with sufficient radio quality, an SRVCC is performed for the UE.
In case of LTE3273, the UE is configured to perform inter-frequency neighbour cell
measurements. If the UE reports suitable inter-frequency target cells, a handover is performed
for the UE.
For GSM neighbour cell measurements triggered by the voice quality criteria, the B1 event is used
based on the LTE3443 configuration.
Note:
As the eNB load or threshold parameter changes, a high number of the voice qualityrelated SRVCC trigger can occur simultaneously. To prevent overload, the lower layers have
to implement measures to control the trigger rate on the interface to the higher layers.
40
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
For intra-LTE inter-frequency measurements triggered by the voice quality criteria, the A3 and A5
events are used based on the LTE3723 configuration. If the A5 event is started due to a voice
quality trigger, the threshold for the serving cell is modified by the eNB in a way that the serving
cell condition is always true. This means that the LNHOIF Threshold Th3 For RSRP
Inter Frequency (threshold3InterFreq) or LNHOIF RSRQ A5 inter-frequency
threshold1 (threshold3RsrqInterFreq) parameters for the serving cell are set by the
eNB to the maximum value.
The A3 or A5 inter-frequency measurements and B1 SRVCC to GSM measurements are activated
for VoLTE UEs if either of the following conditions occurs:
The UL final residual BLER for the QCI1 bearer is higher than or equal to the configurable
threshold, defined by the badQualityRBlerThres parameter.
The UL voice break period gets higher than or equal to the configurable threshold, defined by
the badQualityULGapThres parameter.
The DL voice break period gets higher than or equal to the configurable threshold, defined by
the badQualityDLGapThres parameter.
The A3 or A5 inter-frequency measurements and B1 SRVCC to GSM measurements are stopped
for VoLTE UEs if all of the following conditions occur:
The UL final residual BLER for the QCI1 bearer is below the configurable threshold, defined by
the goodQualityRBlerThres parameter.
The period of consecutive successful receptions of QCI1 UL PDCP packets exceeds or equals
the configurable threshold, defined by the goodQualityGapThres parameter.
The period of consecutive successful transmissions of QCI1 DL PDCP packets exceeds or
equals the configurable threshold (the same threshold for the UL criterion is used), defined by
the goodQualityGapThres parameter.
The LTE3723: VoLTE Quality-Triggered Inter-Frequency Mobility feature is activated with the
LNBTS Activate VoLTE quality triggered inter frequency mobility
(actVoLTEQualInterFreqMobility) parameter.
The LTE3443: VoLTE quality triggered SRVCC to GSM feature is activated with the LNBTS
Activate VoLTE quality triggered SRVCC to GSM (actVoLTEQualSRVCCtoGsm)
parameter.
If the LTE3723 and LTE3443 features are enabled in the same cell, then the A3 or A5 interfrequency measurements and the B1 measurements for GSM are configured in parallel. The first
report received by the eNB determines what kind of mobility is used for the UE. For more
information about the events in the measurement reaport, see LTE handover events.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
41
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
11. VoLTE improvements
The LTE2098: VoLTE Uplink Coverage Boosting, LTE3692: VoLTE Robustness
Enhancements, LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation, and
LTE2774: Source Rate Based UL Grant Assignment for VoLTE features introduce several
mechanisms improving VoLTE functionality.
11.1 VoLTE UL coverage enhancement
The LTE2098: VoLTE Uplink Coverage Boosting feature improves the UL coverage for VoLTE
UEs by up to 2.5 dB when in transmission time interval (TTI) bundling mode, and by up to 1.5 dB
outside of TTI bundling mode. This improves the chances of establishing and maintaining a VoLTE
connection.
The LTE2098: VoLTE Uplink Coverage Boosting feature improves the UL coverage for VoLTE
UEs with QCI1 bearer established, and also UEs with QCI65 and QCI66 bearers established. QCI65
refers to mission-critical user plane push-to-talk voice, and QCI66 refers to non-mission-critical
user plane push-to-talk voice. QCI65 and QCI66 are introduced by the LTE2611: Introduction of
Public Safety Specific QCI Bearers feature.
The LTE2098 feature is activated with the LNCEL Activation of VoIP coverage
boosting in UL scheduling (actVoipCovBoost) parameter.
This feature provides the following UL coverage improvements:
Sensitivity-based UL resource allocation
Reduction of aperiodic channel quality indicator (CQI) reporting
Noise power and channel estimation improvements to the UL receiver
Sensitivity-based UL resource allocation is introduced for VoLTE UEs when:
a UE is power-limited, which means for the number of UL transmissions defined by the LNCEL
Number of carried VoIP samples before limitation
(ulsMinNumCoverageLimitationStateCheck) parameter, the power headroom report
(PHR) is lower than the configured threshold defined by the LNCEL Threshold of the
power headroom related to QCI1 bearer (ulsPhrQci1Low) parameter.
the modulation and coding scheme (MCS) is in the quadrature phase shift keying (QPSK) range.
42
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
With LTE2098, the aperiodic CQIs are requested only in the initial transmissions and are reported
no more than once per VoIP sample.
A VoLTE UE is switched back to normal scheduling when the PHR is higher than the configured
threshold defined by the LNCEL Threshold of the power headroom related to
QCI1 bearer (ulsPhrQci1Low) and LNCEL Threshold hysteresis related to
QCI1 bearer (ulsPhrQci1Hyst) parameters.
The improvement in the UL receiver is done through:
Improved noise power estimation algorithm. This algorithm is applied to all UL transmissions,
including non-VoLTE.
Improved channel estimation through slot averaging
Improved channel estimation through inter-TTI averaging
These UL receiver improvements aren't applicable to cells marked as high-speed cells (cells with
the LNCEL_FDD/LNCEL_TDD PRACH high speed flag (prachHsFlag) parameter set to
true).
The performance gain offered by LTE2098 (up to 1.5 dB gain without TTI bundling mode) can
only be achieved if the QCI1 GBR signaled over the S1 interface fits the data rate of speech codec
used for the call, as shown in some examples:
For Adaptive Multi-Rate Wideband (AMR-WB) 12.65 kbps, the S1 QCI1 GBR is 32 kbps.
For AMR-WB 23.85 kbps, the S1 QCI1 GBR is 44 kbps.
The AMR is a standard 3GPP audio compression format optimized for speech coding which uses
media adaptation. The AMR-WB is an audio compression format based on AMR encoding. It
provides improved speech quality due to a wider voice bandwidth (50-7000 Hz).
Higher GBR values waste radio resources and degrade the coverage gain.
LTE2098 allows you to choose the condition of entry into the TTI bundling mode with the LNCEL
Activates VoLTE coverage boosting improvements (actVoipCovBoostEnh)
parameter, which can be set to one of the three values:
off
on_ttib_entry_PHR_based
on_ttib_entry_BLER_SINR_based
If the parameter is set to on_ttib_entry_BLER_SINR_based, the UE enters the TTI
bundling mode based on the block error rate (BLER) and the signal-to-interference-plus-noise
ratio (SINR). This reduces the physical resource block (PRB) allocation to three PRBs and the level
of the TTI bundling usage.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
43
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
If the parameter is set to on_ttib_entry_PHR_based, then the UE enters the TTI bundling
mode based on the PHR criteria. LTE2098 offers the possibility of different configurations for the
entry and exit timers to and from the TTI bundling mode for the PHR-based method. The LNCEL
Number of carried VoIP samples before limitation
(ulsMinNumCoverageLimitationStateCheck) parameter is used to set this mechanism.
Note:
To enhance the coverage boosting functionality, set the actVoipCovBoostEnh
parameter to on_ttib_entry_BLER_SINR_based. If the actVoipCovBoostEnh
parameter is set to on_ttib_entry_PHR_based, UEs can be under the sensitivitybased scheduling for most of the time, depending also on the PHR threshold defined by
the ulsPhrQci1Low parameter. The on_ttib_entry_PHR_based option can
increase the UL latency of data bearers and, for example, decrease the TCP DL peak
throughput.
The LNCEL Minimum time to enter PHR based TTI bundling
(ttibPhrDwellTimeIn) and LNCEL Minimum time to exit PHR based TTI
bundling (ttibPhrDwellTimeOut) parameters allow for separate configurations for the
waiting timers before entering and exiting the TTI bundling mode. This improves control over the
retention time, avoiding fast re-entry into the TTI bundling mode.
The LTE2098 feature removes the QPSK threshold from the trigger conditions of PHR-based
entry into the TTI bundling mode.
To delay the BLER and SINR-based entry into the TTI bundling mode, configure the LNCEL
Minimum time to enter TTI bundling after Bearer Setup
(ttibMinDelayAfterBearerSetup) parameter. It determines the minimum time a UE in the
non-TTI bundling mode spends after VoLTE bearer setup before it can actually enter the TTI
bundling mode.
To restrict the initial number of PRBs that can be allocated to the UE in UL after the sensitivitybased scheduling mode is left, you can use the LNCEL Maximum number of PRBs after
coverage boosting (ulsMaxNumPrbAfterCovBoost) parameter. This restriction ensures
that the PHR of the UE isn't changed after the sensitivity-based scheduling mode is left.
When the LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation feature is activated,
the usage of sensitivity-based scheduling mode is reduced if the UE follows the bit rate
recommendations of the eNB by adapting the data rate of the audio codec to it.
When the LTE2774: Source rate based UL grant assignment for VoLTE feature is activated, the
44
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
MCS and PRB code point selection for coverage limited VoLTE UEs is modified to be based on the
VoLTE bearer measured UL source bit rate.
11.2 VoLTE robustness improvement
The LTE3692:VoLTE Robustness Enhancements feature introduces three improvements to
the VoLTE technology: proactive UL grants, improved transmission time interval (TTI) bundling
mode entry or exit, and fake discontinuous reception (DRX) in TTI bundling.
TTI bundling is designed to improve UL performance of UEs at cell edge. These UEs often hit the
maximum transmission power. Nevertheless, because of poor radio conditions, the quality of the
signal received by the BTS is decreased. In this case, the BTS triggers the TTI bundling activation.
UEs are switched into TTI bundling if the radio conditions deteriorate to the point where the block
error rate (BLER) or the signal-to-interference-plus-noise-ratio (SINR) threshold is exceeded and
the available power is insufficient for transmission on more than just a few physical resource
blocks (PRBs).
The TTI bundling has a fixed hybrid automatic repeat request (HARQ) round-trip timing of 16 TTIs.
When running in TTI bundling mode, a UE has four HARQ buffers that can be scheduled one after
the other, such that the UE is then transmitting without interruption. In normal mode, UEs have
eight HARQ processes.
Figure 5: Normal operation mode
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
45
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Figure 6: TTI bundling mode
QCI-1 proactive UL grants
The eNB gives UEs with an established QCI1 bearer an UL proactive grant based on the following
criteria:
Non-TTI bundling UEs are considered for a low priority UL grant if the UE didn't have an UL
transmission for the number of consecutive TTIs defined by the LNCEL RegTx VoLTE
proactive UL grant period (voLteProactUlGrantPeriodRegTx) parameter.
TTI bundling UEs are considered for a high priority UL grant if the UE didn't have a UL
transmission for the number of consecutive TTIs defined by the LNCEL TTIB VoLTE
proactive UL grant period (voLteProactUlGrantPeriodTtib) parameter.
The UE receives the UL grant only if it's UL-synchronized in the DRX active time and no
measurement gap is pending for the UE.
UL proactive grants are given to UEs based on the UL scheduler prioritization algorithm. When
there is higher priority traffic in the same TTI, it can pre-empt the UL proactive grants.
The maximum number of UEs (both TTI bundling and non-TTI bundling) which can have a
VoLTE proactive UL grant per TTI is defined by the LNCEL Maximum number of VoLTE
proactive UL grants per TTI (maxNumVoLteProactUlGrantsPerTti)
parameter.
If the maxNumVoLteProactUlGrantsPerTti parameter is set to 0, the QCI1 proactive
UL grant functionality is disabled.
The changes above help avoiding long audio gaps in the UL direction at the expense of more UL
transmissions, which can lead to an increase in both UE battery usage and UL noise level.
Improved TTI bundling mode entry/exit criteria
The eNB allows a UE with a VoLTE bearer to switch to TTI bundling mode only by fulfilling both
conditions below:
46
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
The UE UL signal-to-interference-plus-noise ratio (SINR) measurement is below the threshold
defined by the LNCEL SINR threshold for entering TTI bundling mode
(ttibSinrThresholdIn parameter for LNCEL Minimum time to enter SINR
based TTI bundling (ttibSinrDwellTimeIn) consecutive TTIs.
VoLTE bearer has been established for at least the period defined by the LNCEL Minimum
time to enter TTI bundling after Bearer Setup
(ttibMinDelayAfterBearerSetup) parameter.
The eNB allows a TTI bundling UE with a VoLTE bearer to transition out of TTI bundling mode only
if the UE UL SINR measurement is above the threshold defined by the LNCEL SINR threshold
for leaving TTI bundling mode (ttibSinrThresholdOut parameter for LNCEL
Minimum time to exit SINR based TTI bundling (ttibSinrDwellTimeOut)
consecutive TTIs.
This improvement reduces the ping-pong effect of the TTI bundling and non-bundling modes
transitions with the effect of decreasing related RRC signaling.
Fake discontinuous reception (DRX)
By default, the DRX is disabled when the UE enters in TTI bundling mode for VoLTE calls. In DRX
disabled state, a maximum of 10 ms is used as the DRX long cycle compared to DRX long cycle
(for example, 40 ms) in the DRX enabled case (see
3GPP TS 36.133, Chapter 7.6 Radio Link
Monitoring). The DRX long cycle is defined by the DRX DRX long cycle (drxLongCycle)
parameter.
Under poor RF conditions, the usage of DRX can increase the call drops. With this feature, this can
be avoided by keeping the UE in DRX active state.
The UE is configured for DRX while it's in TTI bundling mode, by setting the DRX on duration timer
to be equal to the DRX long cycle to keep the UE always in the DRX active state. The DRX on
duration timer is defined by the DRX DRX on duration timer (drxOnDuratT) parameter.
When the TTI bundling mode ends, the proper values from DRX profile are selected.
This functionality is activated with the LNCEL Activate DRX during TTI Bundling
(actDrxDuringTTIB) parameter.
Only if the LNCEL Activate DRX(actDrx) parameter is set to true, the
actDrxDuringTTIB parameter is allowed to be configured to true.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
47
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
11.3 Adaptive codec bit rate
The LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation feature supports the
dynamic bit rate adaptation according to varying RF conditions.
The LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation feature allows the eNB to
send the bit rate recommendations to the multimedia telephony (MMTel)-compatible UEs to
assist them in selecting or adapting to the suitable audio codec data rate. It also allows the UE to
send a query message to the local eNB to check if a previous bit rate recommendation can be
sustained by the eNB (the capabilities of MMTel UEs are specified in
3GPP TS 36.321, Chapter
6).
MMTel is a global standard based on the IP multimedia system, which defines an evolved
telephony service enabling real-time multimedia communication with the characteristics of a
telephony over mobile access. It uses media capabilities such as voice, real-time video, file
transfer, audio and video clips, text, and so on.
The recommended bit rate value is defined as an average link capacity in UL (that is available for
the UE), calculated over a configurable period of time. The link capacity depends on the actual
signal-to-interference-plus-noise ratio (SINR) and power headroom report (PHR) of the UE.
Whenever the link capacity in UL degrades below or improves above the last recommended bit
rate plus configured step size, the eNB sends a message with the newly calculated recommended
bit rate to the UE. This allows the UE to dynamically adapt the codec data rate according to the
current RF conditions.
The eNB also responds to the UE-initiated recommended bit rate queries for DL direction by
sending the available bit rate value in UL, or with a message with no bit rate recommendation
indicated by the value 0 of recommended bit rate index. The response for DL depends on the
configuration of the LNCEL RBR DL queries response mode (rbrDlQueryRespMode)
parameter.
The responses to UE-initiated recommended bit rate queries aren't sent until the configured time
period, defined by the LNCEL Ave. meas. time for avail. bit rate measurement
(rbrMeasTime) parameter, has expired after the establishment of the first VoLTE bearer. This
ensures that the recommended bit rate suits to the available link capacity of the UE.
Unused GBR capacity of the cell is considered in the data rate recommendations. If a UE moves to
better RF conditions, a higher bit rate recommendation is sent to the UE to improve voice quality,
which uses the unused GBR resources. This function is configured using the LNCEL Consider
cell PRB usage in RBR (rbrCellPrbUsage) parameter.
48
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
The recommended bit rate messages and UE recommended bit rate queries are MAC control
elements appended to an already scheduled UL or DL transmission. Since only audio codecs are
considered, the range of recommended bit rates is up to 140 kbit/s, covering all commercially
used Adaptive Multi-Rate (AMR), Adaptive Multi-Rate Wideband (AMR-WB), and Enhanced Voice
Services (EVS) codecs. For more information, see
3GPP TS 36.321, Chapter 6.1.3.13
Recommended bit rate MAC control element..
Note:
The recommended bit rate value is referenced by a recommended bit rate index, carried in
the MAC CE in the range of 0 to 18. Value 0 indicates that no bit rate is recommended. This
option is used in response to UE recommended bit rate queries only. Value 1 (see
3GPP
TS 26.114, Chapter 10.7.2) is never set by LTE4244 to avoid unwanted effects due to its
special meaning.
The LTE2774: Source rate based UL grant assignment for VoLTE feature must be activated
before activating the LTE4244 feature.
The LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation feature is activated with
the LNCEL Activate recommended bit rate (actRbr) parameter.
11.4 VoLTE UL grant assignment
The LTE2774: Source Rate Based UL Grant Assignment for VoLTE feature introduces
automatic adaptation of VoLTE uplink grants to the source rate.
The eNB allocates UL resources and selects transport block size (TBS) to VoLTE bearers according
to the buffer status report (BSR). When BSR isn't available, TBS is estimated based on the UL GBR
received over the S1 Application Protocol (S1AP) interface from mobility management entity
(MME). For more information about S1AP, see S1 Application Protocol document.
The physical uplink shared channel (PUSCH) resources are used in a manner which allows for more
users. The higher the cell load, the more beneficial it is since the resources can be allocated to the
users that need them the most).
Note:
In case of low-loaded cells, the scheduler continues to works based on the GBR assignment,
without affecting the other UEs.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
49
There are scenarios wherein the code rate communicated over the S1AP is higher than necessary
for the used codec. The eNB allocates too many physical resource blocks (PRBs) in UL for VoLTE
calls. Consequently, a higher amount of padding bits (bits with no real data, but are added to fill
the transport block) is used to reach the TBS.
When the LTE2774 feature is activated, the local cell group (LCG) UL bit rate of VoLTE bearers is
measured based on the received data volume of all the VoLTE bearers in the LCG. The data
volume is evaluated after MAC de-multiplexing and only the data volume received during talk
spurts is used for the evaluation of the bit rate. Talk spurts refer to a period when voice data
packets are exchanged, either in UL or DL.
When the VoLTE bearer is established, the UL bit rate is initialized to a value based on the bit rate
communicated over S1AP. When the S1AP data is received for the VoLTE bearer, the UL bit rate is
adapted based on the volume of received data. The measured bit rate is then used by the UL
scheduler for several VoLTE-specific bearer functions, such as the dedicated bearer with QCI1
used when a VoLTE call is set up.
Figure 7: An overview of the LTE2774 feature functionality
The LTE2774 feature optimizes the UL MAC padding for the VoLTE traffic when the UL GBR rate
communicated over S1AP is higher than what is necessary for the voice codec in use.
The LTE2774 feature is applied at LCG level, not at bearer level. If VoLTE LCG contains multiple
VoLTE bearers, the measured LCG level bit rate reflects the aggregate bit rate for all VoLTE
bearers in the LCG.
The LTE2774 feature is activated with the LNCEL Activate VoLTE source rate based
UL assignment (actVoLteSrcRate) parameter.
When both the LTE2098: VoLTE Uplink Coverage Boosting and the LTE2774: Source RateBased UL Grant Assignment for VoLTE features are enabled, the scheduler does a trade-off
assignment of lower radio resources while maintaining a satisfying Packet Data Convergence
Protocol (PDCP) loss rate. For the E-UTRAN PDCP SDU Loss Ratio in the UL, QCI1
50
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
KPI, a 2% value is estimated as a good level (this is also the value used by the scheduler as a
target value).
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
51
12. EN-DC setup during VoLTE services
The LTE5388: VoLTE without EN-DC feature replaces the LTE5524: Ongoing QCI1 Prevents
EN-DC Setup feature. LTE5388 allows to handle the EN-DC setup when VoLTE (emergency and
non-emergency QCI1, QCI65, and QCI66 bearers) is configured.
The LTE5388: VoLTE without EN-DC feature replaces the LTE5524: Ongoing QCI1 Prevents
EN-DC Setup feature. It extends VoLTE with EN-DC prevention rules by introducing support for
the QCI65 and QCI66 bearers, in addition to the QCI1 bearer. The LTE5388 feature allows to
resolve the issue when EN-DC is configured prior to VoLTE bearer establishment.
With the EN-DC configured, setting-up VoLTE connection (meaning QCI65, QCI66, emergency, and
non-emergency QCI1 bearers being established) results in EN-DC being disabled. Disabling EN-DC
doesn't initiate B1-NR measurements for the UE. These measurements are established when the
VoLTE bearer is removed.
The LTE5388: VoLTE without EN-DC feature is activated with the LNBTS Activate the
prevention of EN-DC setup during VoLTE (actVoLteNoEnDc) parameter with
separate values controlling the applicability for emergency QCI1 calls, non-emergency QCI1 calls,
and push-to-talk services with QCI65 and QCI66.
Setting the Activate the prevention of EN-DC setup during VoLTE
(actVoLteNoEnDc) parameter value allows to specify restrictions preventing VoLTE with EN-DC.
The restrictions are based on combinations of QCI1, QCI65, and QCI66 calls.
Note:
Setting the LNBTS Activate keep En-Dc during VoLte setup
(actVoLteNoEnDcDrop) parameter value to true allows to return to the LTE5524:
Ongoing QCI1 Prevents EN-DC Setup feature solution. In this solution, when the VoLTE
connection is ongoing (meaning, when there is either an emergency or non-emergency
QCI1 bearer established), B1-NR measurements aren't initiated and configuring EN-DC is
prevented.
52
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
13. VoLTE reference data
List of management data related to the VoLTE features: alarms, faults, measurements, counters,
KPIs, and parameters
For reference data descriptions, see Reference Documentation/Reference document.
13.1 VoLTE faults and alarms
There are no alarms and faults related to the VoLTE functionality.
13.2 VoLTE measurements, counters, and KPIs
List of management data related to the VoLTE features: measurements, counters, and KPIs
Measurements and counters
Table 3: Counters introduced by the VoLTE features in LTE19
Related
Counter ID
Counter name
Measurement
LTE4244
M8005C383
Unsolicited UL RBR
recommendation
LTE MAC PS
LTE4244
M8005C384
UL RBR recommendation
responses
LTE MAC PS
LTE4244
M8010C188
DL RBR recommendation
responses
LTE MAC PS
Feature
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
53
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 4: Counters introduced by the VoLTE features in LTE18
Related
Counter ID
Counter name
Measurement
LTE3443
M8016C61
Inter System Handover
VoLTE Quality triggered
SRVCC HO preparation
attempts
LTE Inter System Handover
LTE3443
M8016C62
Inter System Handover
attempts to GERAN with
VoLTE Quality triggered
SRVCC
LTE Inter System Handover
LTE3443
M8016C63
Successful Inter System
Handover completions to
GERAN with VoLTE
Quality triggered SRVCC
LTE Inter System Handover
LTE3443
M8016C64
Failed Inter-System
Handover preparations
to GERAN with VoLTE
Quality triggered SRVCC
due to timer
LTE Inter System Handover
LTE3443
M8016C65
Failed Inter-System
Handover preparations
to GERAN with VoLTE
Quality triggered SRVCC
due to target eNB
admission control
LTE Inter System Handover
LTE3443
M8016C66
Failed Inter-System
Handover preparations
to GERAN with VoLTE
Quality triggered SRVCC
caused by other reasons
LTE Inter System Handover
LTE3443
M8016C67
VoLTE Quality triggered
SRVCC HO execution
failures due to timer
expiry
LTE Inter System Handover
LTE3443
M8067C0
Downlink Voice Break
(VoLTE) Period BIN 1
LTE VoLTE Voice Break Period
Histogram
Feature
54
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Related
Counter ID
Counter name
Measurement
LTE3443
M8067C1
Downlink Voice Break
(VoLTE) Period BIN 2
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C2
Downlink Voice Break
(VoLTE) Period BIN 3
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C3
Downlink Voice Break
(VoLTE) Period BIN 4
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C4
Downlink Voice Break
(VoLTE) Period BIN 5
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C5
Downlink Voice Break
(VoLTE) Period BIN 6
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C6
Downlink Voice Break
(VoLTE) Period BIN 7
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C7
Downlink Voice Break
(VoLTE) Period BIN 8
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C8
Downlink Voice Break
(VoLTE) Period BIN 9
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C9
Downlink Voice Break
(VoLTE) Period BIN 10
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C10
Downlink Voice Break
(VoLTE) Period BIN 11
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C11
Uplink Voice Break
(VoLTE) Period BIN 1
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C12
Uplink Voice Break
(VoLTE) Period BIN 2
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C13
Uplink Voice Break
(VoLTE) Period BIN 3
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C14
Uplink Voice Break
(VoLTE) Period BIN 4
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C15
Uplink Voice Break
(VoLTE) Period BIN 5
LTE VoLTE Voice Break Period
Histogram
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Feature
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
55
Related
Counter ID
Counter name
Measurement
LTE3443
M8067C16
Uplink Voice Break
(VoLTE) Period BIN 6
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C17
Uplink Voice Break
(VoLTE) Period BIN 7
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C18
Uplink Voice Break
(VoLTE) Period BIN 8
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C19
Uplink Voice Break
(VoLTE) Period BIN 9
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C20
Uplink Voice Break
(VoLTE) Period BIN 10
LTE VoLTE Voice Break Period
Histogram
LTE3443
M8067C21
Uplink Voice Break
(VoLTE) Period BIN 11
LTE VoLTE Voice Break Period
Histogram
Feature
Table 5: Counters introduced by the VoLTE features in RL70/RL55, LTE15A, and LTE16
Related
Counter ID
Counter name
Measurement
LTE2108,
LTE2388,
LTE1127,
LTE2503
M8021C7
Number of service
based handover
attempts
LTE Handover
LTE2108,
LTE2388,
LTE1127,
LTE2503
M8021C8
Number of successful
service based
handover completions
LTE Handover
Feature
56
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 6: Counters related to VoLTE features
Related
Counter ID
Counter name
Measurement
LTE2108,
LTE2388
M8013C17
Signaling Connection
Establishment attempts due
to MO-Signaling
LTE UE State
LTE2108,
LTE2388
M8013C18
Signaling Connection
Establishment attempts due
to MT-Access
LTE UE State
LTE2108,
LTE2388
M8013C19
Signaling Connection
Establishment attempts due
to MO-Data
LTE UE State
LTE2108,
LTE2388
M8013C20
Signaling Connection
Establishment attempts due
to others
LTE UE State
LTE2108,
LTE2388
M8013C21
Number of Signaling
Connection Establishment
attempts for emergency
calls
LTE UE State
LTE2108,
LTE2388
M8013C5
Signaling Connection
Establishment completions
LTE UE State
LTE2108,
LTE2388
M8014C0
Inter eNB Handover
preparations
LTE Inter eNB
Handover
LTE2108,
LTE2388
M8014C7
Successful inter eNB HO
LTE Inter eNB
Handover
LTE2108,
LTE2388
M8014C14
Inter eNB S1-Handover
preparations
LTE Inter eNB
Handover
LTE2108,
LTE2388
M8014C19
Successful inter eNB S1-HO
LTE Inter eNB
Handover
LTE2108,
LTE2388
M8009C2
Intra eNB Handover
preparations
LTE Intra eNB
Handover
LTE2108,
LTE2388
M8009C7
Successful intra eNB HO
LTE Intra eNB
Handover
LTE2108,
LTE2388
M8016C14
Inter System Handover
preparations
LTE Inter System
Handover
Feature
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
57
Related
Counter ID
Counter name
Measurement
LTE2108,
LTE2388
M8016C23
Successful Inter System
Handover completions
LTE Inter System
Handover
LTE2108,
LTE2388
M8016C30
Successful Inter System
Handover completions to
UTRAN with SRVCC
LTE Inter System
Handover
LTE2108,
LTE2388
M8016C34
Successful Inter System
Handover completions to
GERAN with SRVCC
LTE Inter System
Handover
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Feature
58
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Key performance indicators
Table 7: Key performance indicators related to VoLTE features
Related
KPI ID
KPI name
LTE2108,
LTE2388
LTE_5043a
E-UTRAN Total HO Success Ratio, intra eNB
LTE2108,
LTE2388
LTE_5058b
E-UTRAN Total HO Success Ratio, inter eNB
X2 based
LTE2108,
LTE2388
LTE_5084a
E-UTRAN Total HO Success Ratio, inter eNB
S1 based
LTE2108,
LTE2388
LTE_5198b
E-UTRAN Inter RAT Total HO Success Ratio
LTE2108,
LTE2388
LTE_5204a
E-UTRAN E-RAB Setup Success Ratio, QCI1
LTE2108,
LTE2388
LTE_5218c
Total E-UTRAN RRC Connection Setup Success
Ratio
LTE2098
LTE_5311b
E-UTRAN PDCP SDU Loss Ratio in the UL, QCI1
LTE2098
LTE_5572g
E-UTRAN E-RAB QCI1 Drop Ratio, RAN View
feature
13.3 VoLTE parameters
List of management data related to VoLTE features: parameters
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
59
Parameters
Table 8: Parameter introduced by the VoLTE features in 23R3
Related
Full name
Abbreviated name
Path
Activate forwarding
of elapsed time of
prohibit timer for
RRC Connection
Release
actRrcConnRelDelayForw
arding
MRBTS/LNBTS/LNCEL
Feature
CB009430
Table 9: Parameters introduced by the VoLTE features in SRAN20A
Related
Full name
Abbreviated name
Path
LTE5388
Activate keep En-Dc
during VoLte setup
actVoLteNoEnDcDro
p
MRBTS/LNBTS
LTE5388
Activate the
prevention of EN-DC
setup during VoLTE
actVoLteNoEnDc
MRBTS/LNBTS
Feature
60
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 10: Parameters introduced by the VoLTE features in LTE19
Related
Full name
Abbreviated name
Path
LTE4244
Activate recommended
bit rate
actRbr
MRBTS/LNBTS/LNCEL
LTE4244
RBR configuration
rbrConfig
MRBTS/LNBTS/LNCEL
LTE4244
Ave. meas. time for
avail. bit rate
measurement
rbrMeasTime
MRBTS/LNBTS/LNCEL/
rbrConfig
LTE4244
Consider cell PRB
usage in RBR
rbrCellPrbUsage
MRBTS/LNBTS/LNCEL/
rbrConfig
LTE4244
Maximal RBR index
rbrIndexHighThresh
old
MRBTS/LNBTS/LNCEL/
rbrConfig
LTE4244
RBR additional power
headroom UL
rbrPhrDelta
MRBTS/LNBTS/LNCEL/
rbrConfig
LTE4244
RBR DL queries
response mode
rbrDlQueryRespMode
MRBTS/LNBTS/LNCEL/
rbrConfig
LTE4244
RBR operational mode
rbrOperMode
MRBTS/LNBTS/LNCEL/
rbrConfig
LTE4244
RBR query wait timer
rbrQueryWaitTimer
MRBTS/LNBTS/LNCEL/
rbrConfig
LTE4244
Step size for RBR
index down-switching
rbrStepSizeDown
MRBTS/LNBTS/LNCEL/
rbrConfig
LTE4244
Step size for RBR
index up-switching
rbrStepSizeUp
MRBTS/LNBTS/LNCEL/
rbrConfig
LTE4244
RBR wait timer for
next RBR message for
up-switching
rbrUpWaitTimer
MRBTS/LNBTS/LNCEL/
rbrConfig
Feature
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
61
Table 11: Parameters introduced by the VoLTE features in LTE18A
Related
Full name
Abbreviated name
Path
LTE3723
Activate VoLTE quality
triggered inter
frequency mobility
actVoLTEQualInterFreq
Mobility
MRBTS/ LNBTS
LTE2774
Activate VoLTE source
rate based UL assignment
actVoLteSrcRate
MRBTS/LNBTS/LNCEL
LTE3723
VoLTE quality target
threshold profile
identifier for interfrequency handover
interFreqVQTgtThreshP
rId
MRBTS/LNBTS/LNCEL/LNHOIF
LTE3723
Assigned VoLTE quality
profile
assignedVoLteQualProf
ile
MRBTS/LNBTS/TGTTHRESHPR
LTE3723
Offset of threshold3a
for RSRP VoLTE quality
inter frequency
threshold3aOffsetRsrp
VQ
MRBTS/LNBTS/TGTTHRESHPR
LTE3723
Offset of threshold3a
for RSRQ VoLTE quality
inter frequency
threshold3aOffsetRsrq
VQ
MRBTS/LNBTS/TGTTHRESHPR
LTE3723
Target threshold profile
identifier
tgtThreshPrId
MRBTS/LNBTS/TGTTHRESHPR
Feature
62
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 12: Parameters introduced by the VoLTE features in LTE18
Related
Full name
Abbreviated name
Path
LTE3443
Activate VoLTE quality
triggered SRVCC to GSM
actVoLTEQualSRVCCtoG
sm
MRBTS/LNBTS
LTE3443
Assigned VoLTE quality
profile
assignedVoLteQualPro
file
MRBTS/LNBTS/LNCEL
LTE3443
LTE VoLTE Voice Break
Period Histogram
mtVoLTEVoiceBPerioHi
st
MRBTS/LNBTS/PMRNL
LTE3443
Max voice break
distribution threshold
maxVBreakDistThresh
MRBTS/LNBTS/PMRNL/PMC
CP
LTE3443
Bad quality DL voice
gap threshold
badQualityDLGapThres
MRBTS/LNBTS/VOLTEQUAL
PR
LTE3443
Bad quality residual
BLER threshold
badQualityRBlerThres
MRBTS/LNBTS/VOLTEQUAL
PR
LTE3443
Bad quality UL voice
gap threshold
badQualityULGapThres
MRBTS/LNBTS/VOLTEQUAL
PR
LTE3443
Good quality residual
BLER threshold
goodQualityRBlerThre
s
MRBTS/LNBTS/VOLTEQUAL
PR
LTE3443
Good quality UL DL
voice gap threshold
goodQualityGapThres
MRBTS/LNBTS/VOLTEQUAL
PR
LTE3443
Residual BLER
condition time to
trigger
rBlerCondTimeToTrigg
er
MRBTS/LNBTS/VOLTEQUAL
PR
LTE3443
VoLTE quality profile
identifier
voLteQualPrId
MRBTS/LNBTS/VOLTEQUAL
PR
Feature
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
63
Table 13: Parameters introduced by the VoLTE features in LTE16
Related Feature
Full name
Abbreviated name
Path
LTE2098
Activation of VoIP coverage
boosting in UL scheduling
actVoipCovBoost
MRBTS/LNBTS/LNCEL
LTE2098
Activates VoLTE coverage
boosting improvements
actVoipCovBoostEnh
MRBTS/LNBTS/LNCEL
LTE2098
Minimum time to enter TTI
bundling after Bearer Setup
ttibMinDelayAfterBearerSetup
MRBTS/LNBTS/LNCEL
LTE2503
Service based handover mode
sbHoMode
MRBTS/LNBTS/LNCEL
LTE2098
VoIP coverage boosting
configuration
voipCovBoostConfig
MRBTS/LNBTS/LNCEL
LTE2098
Maximum number of PRBs after
coverage boosting
ulsMaxNumPrbAfterCovBoost
MRBTS/LNBTS/LNCEL/voipCovBoos
tConfig
LTE2098
Minimum time to enter PHR based
TTI bundling
ttibPhrDwellTimeIn
MRBTS/LNBTS/LNCEL/voipCovBoos
tConfig
LTE2098
Minimum time to exit PHR based
TTI bundling
ttibPhrDwellTimeOut
MRBTS/LNBTS/LNCEL/voipCovBoos
tConfig
LTE2098
Number of carried VoIP samples
before limitation
ulsMinNumCoverageLimitationS
tateCheck
MRBTS/LNBTS/LNCEL/voipCovBoos
tConfig
LTE2098
Threshold hysteresis related to
QCI1 bearer
ulsPhrQci1Hyst
MRBTS/LNBTS/LNCEL/voipCovBoos
tConfig
LTE2098
Threshold of the power headroom
related to QCI1 bearer
ulsPhrQci1Low
MRBTS/LNBTS/LNCEL/voipCovBoos
tConfig
64
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 14: Parameters introduced by the VoLTE features in LTE15A
Related
Full name
Abbreviated name
Path
LTE2430
Activate RRC
connected mode while
no activity
actRrcConnNoActivit
y
MRBTS/LNBTS
LTE1942
Activate dedicated
VoLTE inter-frequency
handover
actDedVoLteInterFre
qHo
MRBTS/LNBTS/LNBTS_FD
D
LTE1942
Activate dedicated
VoLTE inter-frequency
handover
actDedVoLteInterFre
qHo
MRBTS/LNBTS/LNBTS_TD
D
LTE2388
Activate VoLTE call
steering
actVoLteCallSteerin
g
MRBTS/LNBTS/LNBTS_TD
D
LTE2430
QCI1 protection timer
qci1ProtectionTimer
MRBTS/LNBTS/LNCEL
LTE1942
Frequency layer list
for ded. VoLTE interfrequency HO
freqLayListDedVoLte
Ho
MRBTS/LNBTS/MODPR
LTE1942
Frequency layer list
for ded. VoLTE interfrequency HO
freqLayListDedVoLte
Ho
MRBTS/LNBTS/MOPR
Feature
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
65
Table 15: Parameters introduced by the VoLTE features in RL70/RL55
Related
Full name
Abbreviated name
Path
LTE1127
Activate inter-frequency
service based handover
actInterFreqServiceBase
dHo
MRBTS/LNBTS/LNBTS_FDD
LTE1127
Activate inter-frequency
service based handover
actInterFreqServiceBase
dHo
MRBTS/LNBTS/LNBTS_TDD
LTE2108
Activate redirect VoLTE
actRedirVoLte
MRBTS/LNBTS/LNBTS_TDD
LTE1406
Activate extended VoLTE
talk time
actQci1eVTT
MRBTS/LNBTS/LNCEL
LTE1406
Extended VoLTE Talk Time
Configuration for QCI1
qci1eVTTConfig
MRBTS/LNBTS/LNCEL
LTE1406
DL target BLER for QCI1
qci1DlTargetBler
MRBTS/LNBTS/LNCEL/qci1eV
TTConfig
LTE1406
HARQ and BLER
reconfiguration timer for
QCI1
qci1ReconStopTimer
MRBTS/LNBTS/LNCEL/qci1eV
TTConfig
LTE1406
Maximum number of HARQ
transmission in DL for
QCI1
qci1HarqMaxTrDl
MRBTS/LNBTS/LNCEL/qci1eV
TTConfig
LTE1406
Maximum number of HARQ
transmission in UL for
QCI1
qci1HarqMaxTrUl
MRBTS/LNBTS/LNCEL/qci1eV
TTConfig
LTE1406
Multiplication factor for
the QCI1 traffic in
downlink
qci1ThroughputFactorDl
MRBTS/LNBTS/LNCEL/qci1eV
TTConfig
LTE1406
Multiplication factor for
the QCI1 traffic in
uplink
qci1ThroughputFactorUl
MRBTS/LNBTS/LNCEL/qci1eV
TTConfig
LTE1406
UL AMC target BLER for
QCI1
qci1UlTargetBler
MRBTS/LNBTS/LNCEL/qci1eV
TTConfig
LTE1127
Inter-freq service based
HO retry timer
iFServiceBasedHoRetryTi
mer
MRBTS/LNBTS/LNCEL
LTE2108
Redirected VoLTE call
setup supervision timer
voLteRedirTimer
MRBTS/LNBTS/LNCEL/LNCEL_T
DD
LTE2108
Inter-freq. service based
threshold RSRP target
filter
thresholdRsrpIFSBFilter
MRBTS/LNBTS/LNCEL/LNHOIF
LTE2108
Inter-freq. service based
threshold RSRQ target
thresholdRsrqIFSBFilter
MRBTS/LNBTS/LNCEL/LNHOIF
LTE1127
Inter-freq. service based
threshold RSRP target
filter
thresholdRsrpIFSBFilter
MRBTS/LNBTS/LNCEL/LNHOIF
Feature
66
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Related
Full name
Abbreviated name
Path
LTE1127
Inter-freq. service based
threshold RSRQ target
filter
thresholdRsrqIFSBFilter
MRBTS/LNBTS/LNCEL/LNHOIF
LTE1127
Frequency layer list for
VoLTE service based HO
freqLayListServiceBased
Ho
MRBTS/LNBTS/MOPR
LTE1127
Frequency layer list for
VoLTE service based HO
freqLayListServiceBased
Ho
MRBTS/LNBTS/MODPR
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Feature
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
67
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 16: Parameters related to the VoLTE features
Related Feature
Full name
Abbreviated name
Path
LTE4244
Activate enhanced AC and
GBR services
actEnhAcAndGbrServices
MRBTS/LNBTS
LTE2098
Activate PDCP robust header
compression
actPdcpRohc
MRBTS/LNBTS
CB009430
Activate prohibit timer for
RRC Connection Release
after last QCI1 bearer
release
actRrcConnRelDelay
MRBTS/LNBTS
LTE5388
Activation LTE-NR DualConnectivity
actLteNrDualConnectivity
MRBTS/LNBTS
LTE1127,
LTE1942,
LTE2503
Enable interFrequency
handover
actIfHo
MRBTS/LNBTS
LTE1942,
LTE2503,
LTE2098,
LTE2774
Activate support of
conversational voice bearer
actConvVoice
MRBTS/LNBTS/LNBTS_TDD
LTE1406,
LTE3692
Activate DRX
actDrx
MRBTS/LNBTS/LNCEL
LTE3692
Activate DRX during TTI
Bundling
actDrxDuringTTIB
MRBTS/LNBTS/LNCEL
LTE2098
Activate extended VoLTE
talk time
actQci1eVTT
MRBTS/LNBTS/LNCEL
CB009430
Activate inactive time
forwarding
actInactiveTimeForwarding
MRBTS/LNBTS/LNCEL
LTE1406
Activate smart DRX
actSmartDrx
MRBTS/LNBTS/LNCEL
LTE2098
Activate TTI bundling
actTtiBundling
MRBTS/LNBTS/LNCEL
LTE2098
Activate uplink link
adaptation
actUlLnkAdp
MRBTS/LNBTS/LNCEL
LTE1406
DL target BLER
dlTargetBler
MRBTS/LNBTS/LNCEL
LTE2098
Extended VoLTE Talk Time
Configuration for QCI1
qci1eVTTConfig
MRBTS/LNBTS/LNCEL
LTE2430
Inactivity timer
inactivityTimer
MRBTS/LNBTS/LNCEL
LTE1406
Maximum number of HARQ
transmission in DL
harqMaxTrDl
MRBTS/LNBTS/LNCEL
LTE1406
UL AMC target BLER
ulTargetBler
MRBTS/LNBTS/LNCEL
LTE2098
Maximum number of HARQ
transmission in UL
harqMaxTxUl
MRBTS/LNBTS/LNCEL
LTE3692
Maximum number of VoLTE
proactive UL grants per TTI
maxNumVoLteProactUlGrants
PerTti
MRBTS/LNBTS/LNCEL
LTE2098
Max number of UL HARQ
transmissions during TTI
bundling
harqMaxTrUlTtiBundling
MRBTS/LNBTS/LNCEL
68
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Related Feature
Full name
Abbreviated name
Path
LTE2098
Minimum PRB allocation for
UEs which are power limited
ulsMinRbPerUe
MRBTS/LNBTS/LNCEL
LTE3692
Minimum time to enter TTI
bundling after Bearer Setup
ttibMinDelayAfterBearerSe
tup
MRBTS/LNBTS/LNCEL
LTE2098
Minimum UL transport block
size
ulsMinTbs
MRBTS/LNBTS/LNCEL
LTE2098
Periodic PHR timer
tPeriodicPhr
MRBTS/LNBTS/LNCEL
CB009430
QCI1 RRC Connection Release
prohibit timer
qci1RrcRelDelayTimer
MRBTS/LNBTS/LNCEL
LTE3692
RegTx VoLTE proactive UL
grant period
voLteProactUlGrantPeriodR
egTx
MRBTS/LNBTS/LNCEL
LTE3692
TTI bundling operation mode
ttibOperMode
MRBTS/LNBTS/LNCEL
LTE3692
TTIB VoLTE proactive UL
grant period
voLteProactUlGrantPeriodT
tib
MRBTS/LNBTS/LNCEL
LTE3692
SINR based TTI bundling
dwell time
ttibSinrDwellTimeIn
MRBTS/LNBTS/LNCEL
LTE3692
SINR based TTI bundling
dwell time
ttibSinrDwellTimeOut
MRBTS/LNBTS/LNCEL
LTE1406
DRX profile 2
drxProfile2
MRBTS/LNBTS/LNCEL/DRX
LTE1406
DRX inactivity timer
drxInactivityT
MRBTS/LNBTS/LNCEL/DRX/drxPr
ofile2
LTE1406
DRX long cycle
drxLongCycle
MRBTS/LNBTS/LNCEL/DRX/drxPr
ofile2
LTE1406
DRX on duration timer
drxOnDuratT
MRBTS/LNBTS/LNCEL/DRX/drxPr
ofile2
LTE1406
DRX profile index
drxProfileIndex
MRBTS/LNBTS/LNCEL/DRX/drxPr
ofile2
LTE1406
DRX profile priority
drxProfilePriority
MRBTS/LNBTS/LNCEL/DRX/drxPr
ofile2
LTE1406
DRX retransmission timer
drxRetransT
MRBTS/LNBTS/LNCEL/DRX/drxPr
ofile2
LTE1406
DRX smart profile 2
drxSmartProfile2
MRBTS/LNBTS/LNCEL/SDRX
LTE1406
DRX inactivity timer
drxInactivityT
MRBTS/LNBTS/LNCEL/SDRX/drxP
rofile2
LTE1406
DRX long cycle
drxLongCycle
MRBTS/LNBTS/LNCEL/SDRX/drxP
rofile2
LTE1406
DRX on duration timer
drxOnDuratT
MRBTS/LNBTS/LNCEL/SDRX/drxP
rofile2
LTE1406
DRX profile index
drxProfileIndex
MRBTS/LNBTS/LNCEL/SDRX/drxP
rofile2
LTE1406
DRX profile priority
drxProfilePriority
MRBTS/LNBTS/LNCEL/SDRX/drxP
rofile2
LTE1406
DRX retransmission timer
drxRetransT
MRBTS/LNBTS/LNCEL/SDRX/drxP
rofile2
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
69
Related Feature
Full name
Abbreviated name
Path
LTE1406
DRX short cycle
drxShortCycle
MRBTS/LNBTS/LNCEL/SDRX/drxP
rofile2
LTE1406
DRX short cycle timer
drxShortCycleT
MRBTS/LNBTS/LNCEL/SDRX/drxP
rofile2
LTE1406
Short term inactivity
factor for smart DRX
smartStInactFactor
MRBTS/LNBTS/LNCEL/SDRX/drxP
rofile2
LTE1127,
LTE1942,
LTE2503
Auto adaption to freq.
layers of all neighbor
cells
autoAdapt
MRBTS/LNBTS/MODPR
LTE2108,
LTE2503
Frequency layer list for
VoLTE service based HO
freqLayListServiceBasedHo
MRBTS/LNBTS/MODPR
LTE1127,
LTE2503
Mobility default profile
identifier
moDPrId
MRBTS/LNBTS/MODPR
LTE1127
Mobility profile identifier
moPrId
MRBTS/LNBTS/MOPR
70
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
14. Procedures related to the VoLTE functionality
Instructions to activate, configure, deactivate, or verify the VoLTE functionality in the network
Before you start
See Configuring Features with BTS Site Manager or Configuring Features with Web Element
Manager for general management tool instructions.
14.1 Procedures for VoLTE UE power consumption
14.1.1 Activating the reduction of VoLTE UEs power
consumption
Instructions to optimize the battery life of VoLTE UEs, introduced with the LTE1406: Extended
VoLTE Talk Time feature.
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
The following features must be activated before activating the LTE1406: Extended VoLTE Talk
Time feature:
LTE10: EPS Bearers for Conversational Voice
Set the LNBTS_FDD/LNBTS_TDDActivate support of conversational voice
bearer (actConvVoice) parameter to true.
LTE42: Support of DRX in RRC Connected Mode
Set the LNCELActivate DRX (actDrx) parameter to true.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
71
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
4
If the Extended VoLTE Talk Time Configuration for QCI1
(qci1eVTTConfig) parameter structure doesn't exist, create it.
Configure the following parameters:
DL target BLER for QCI1 (qci1DlTargetBler)
Maximum number of HARQ transmission in DL for QCI1
(qci1HarqMaxTrDl)
Maximum number of HARQ transmission in UL for QCI1
(qci1HarqMaxTrUl)
HARQ and BLER reconfiguration timer for QCI1
(qci1ReconStopTimer)
Multiplication factor for the QCI1 traffic in downlink
(qci1ThroughputFactorDl)
Multiplication factor for the QCI1 traffic in uplink
(qci1ThroughputFactorUl)
UL AMC target BLER for QCI1 (qci1UlTargetBler)
5
Set the Activate extended VoLTE talk time (actQci1eVTT) parameter to
true.
Result
The LTE1406: Extended VoLTE Talk Time feature aligns the DRX on duration time with the
scheduling request (SR) timing.
72
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
14.1.2 Deactivating the reduction of VoLTE UEs power
consumption
Instructions to deactivate the LTE1406: Extended VoLTE Talk Time feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
4
Set the Activate extended VoLTE talk time (actQci1eVTT) parameter to
false.
Result
The BTS doesn't apply the LTE1406 feature-specific parameters. It applies the parameters of the
standard configuration: Maximum number of HARQ transmission in DL
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
73
(harqMaxTrDl), UL AMC target BLER (ulTargetBler), and DL target BLER
(dlTargetBler) to all the UEs.
14.2 Procedures for redirected VoLTE calls
14.2.1 Activating the redirection of VoLTE calls during the ERAB setup phase
Instructions to activate and configure the LTE2108: Redirected VoLTE Call Setup feature in the
network
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
The following features must be activated before activating the LTE2108: Redirected VoLTE Call
Setup:
LTE55: Inter-Frequency Handover
LTE1060: TDD-FDD Handover features
Set the LNBTS Enable InterFrequency Handover (actIfHo) parameter to
enabled. The LTE55 feature is a prerequisite for the LTE1060 feature. Both features are
activated using the actIfHo parameter.
The following features must be deactivated before activating the LTE2108: Redirected VoLTE
Call Setup:
LTE10: EPS Bearers for Conversational Voice
Set the LNBTS_FDD/LNBTS_TDD Activate support of conversational voice
bearer (actConvVoice) parameter value to false.
LTE1127: Service Base Mobility Trigger
74
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Set the LNBTS_FDD/LNBTS_TDD Activate inter-frequency service based
handover (actInterFreqServiceBasedHo) parameter to false.
LTE1942: Dedicated VoLTE Inter-Frequency Target Freguency List
For more information, see Deactivating the dedicated VoLTE inter-frequency handover.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Configuration›Configuration Management›Navigation
Panel›Steps›Radio Network Configuration›Parameter Editor
Configuration›Configuration Management›Parameter Editor
3
Go to the LNCEL_TDD object.
Object path: MRBTS›LNBTS›LNCEL›LNCEL_TDD
4
Configure the Redirected VoLTE call setup supervision timer
(voLteRedirTimer) parameter.
5
Create and configure the LNHOIF managed object.
Object path: MRBTS›LNBTS›LNCEL›LNHOIF
Configure the following parameters:
Eutra carrier info (eutraCarrierInfo)
Measurement bandwidth (measurementBandwidth)
Presence antenna port1 (interPresAntP)
Inter-freq. service based threshold RSRP target filter
(thresholdRsrpIFSBFilter)
Inter-freq. service based threshold RSRQ target filter
(thresholdRsrqIFSBFilter)
6
Go to the LNCEL_TDD object.
Object path: MRBTS›LNBTS›LNBTS_TDD
7
Set the Activate redirect VoLTE (actRedirVoLte) parameter to true.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
75
8
Create and configure the MODPR managed object.
Result
During the call setup phase, UEs are redirected or handed over from an LTE TDD network (without
VoLTE support) to either an LTE FDD network or other RATs that support voice services. The
request for QCI1 bearers is not rejected, and a voice call can be established.
14.2.2 Deactivating the redirection of VoLTE calls during the
E-RAB setup phase
Instructions to deactivate the LTE2108: Redirected VoLTE Call Setup feature in the network
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNCEL_TDD object.
Object path: MRBTS›LNBTS›LNBTS_TDD
76
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
4
Set the Activate redirect VoLTE (actRedirVoLte) parameter to false.
Result
Redirection or handover of a UE during the call setup phase from an LTE TDD network (without
VoLTE support) to an LTE FDD network or other RAT (with support for voice services) is no longer
supported.
14.2.3 Activating the redirection of VoLTE calls during the
initial context setup phase
Instructions to activate and configure the LTE2388: VoLTE Call Steering Enhancement feature
in the network
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
The following features must be activated before activating the LTE2388: VoLTE Call Steering
Enhancement feature:
LTE55: Inter-Frequency Handover
LTE1060: TDD-FDD Handover
Set the LNBTS Enable InterFrequency Handover (actIfHo) parameter to
enabled. The LTE55 feature is a prerequisite for the LTE1060 feature. Both features are
activated using the actIfHo parameter.
LTE2108: Redirected VoLTE Call Setup
Set the LNBTS_TDD Activate redirect VoLTE (actRedirVoLte) parameter to
true, and configure the LNCEL_TDD Redirected VoLTE call setup supervision
timer (voLteRedirTimer). For more information, see Activating the redirection of VoLTE
calls during the E-RAB setup phase
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
77
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
The following features must be deactivated before activating the LTE2388: VoLTE Call Steering
Enhancement feature:
LTE10: EPS Bearers for Conversational Voice
Set the LNBTS_FDD/LNBTS_TDD Activate support of conversational voice
bearer (actConvVoice) parameter to false.
LTE1406: Extended VoLTE Talk Time
Set the LNCEL Activate extended VoLTE talk time (actQci1eVTT) parameter to
false.
Before activating LTE2388, configure the redirection and handovers functionalities. To configure
the redirection functionality, do the following:
Set the LNBTS Activate CS fallback via redirection (actCSFBRedir) and
LNBTS Enable UE context release with redirect (actRedirect) parameters
to enabled.
Configure the Redirection priority for CS fallback with redirection
(csFallBPrio) and Redirection priority for UE context release
(redirectPrio) parameters in correct instance:
If the LTE490: Subscriber Profile Based Mobility feature is enabled (the LNBTS
Activate selective Mobility Profiles (actSelMobPrf) parameter is set to
true) and subscriber profile ID (SPID) mapping is enabled, configure the MOPR›MORED
instance.
If the LTE490 feature is enabled, there is no SPID mapping, and the MODPR Auto
adaptation to freq. layers of all neighbor cells (autoAdapt)
parameter is set to false, configure the MODPR›MODRED instance.
If the LTE490 feature is disabled (the LNBTS Activate selective Mobility
Profiles (actSelMobPrf) parameter is set to false), configure the LNCEL›REDRT
instance.
To configure handovers, set the Auto adaptation to freq. layers of all
neighbor cells (autoAdapt) parameter to false in the correct instance:
If the LTE490 feature and SPID mapping are enabled, configure the LNBTS›MOPR instance.
If the LTE490 feature is disabled, configure the LNBTS›MODPR instance.
Additionally:
Configure the LNCEL Mobility profiles mapping list (moPrMappingList)
parameters structure.
Configure at least one of the following parameters:
LNHOIF Inter-freq. service based threshold RSRP target filter
78
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
(thresholdRsrpIFSBFilter)
LNHOIF Inter-freq. service based threshold RSRQ target filter
(thresholdRsrqIFSBFilter)
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNBTS_TDD object.
Object path: MRBTS›LNBTS›LNBTS_TDD
4
Set the Activate VoLTE call steering (actVoLteCallSteering) parameter to
true.
5
Go to the MODPR object.
Object path: MRBTS›LNBTS›MODPR
6
Configure the Frequency layer list for VoLTE service based HO
(freqLayListServiceBasedHo) parameter.
Note:
For each element of the freqLayListServiceBasedHo parent parameter from
MRBTS›LNBTS›MOPR instance, create and configure an element for the
Frequency layer list for VoLTE service based HO
(freqLayListServiceBasedHo) parameter in MRBTS›LNBTS›MODPR.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
79
Note:
If the freqLayListServiceBasedHo parameter isn't configured or defined as an
empty list, all inter-frequency targets aren't allowed for a VoLTE handover to FDD
layer. In this case, the redirect is targeted to 3G directly if the frequency layers are
configured. Otherwise, a UE context release occurs.
Result
All LNCEL instances are operating with the configured and activated LTE2388: VoLTE Call
Steering Enhancement feature using the frequency layer list. VoLTE calls are possible in TDD
network.
14.2.4 Deactivating the redirection of VoLTE calls during the
initial context setup phase
Instructions to deactivate the LTE2388: VoLTE Call Steering Enhancement feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
80
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNBTS_TDD object.
Object path: MRBTS›LNBTS›LNBTS_TDD
4
Set the Activate VoLTE call steering (actVoLteCallSteering) parameter to
false.
Result
VoLTE calls are no longer possible in the TDD network.
14.3 Procedures for VoLTE actions triggered by voice drop
14.3.1 Activating SRVCC to GSM
Instructions to activate the LTE3443: VoLTE Quality-Triggered SRVCC to GSM feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
The LTE873: SRVCC to GSM feature is activated, and the LNBTS_FDD/LNBTS_TDD
Activate SRVCC to GSM (actSrvccToGsm) parameter is set to true.
Procedure
1
Start the WebEM application.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
81
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNBTS object.
Object path: MRBTS›LNBTS
4
Set the Activate VoLTE quality triggered SRVCC to GSM
(actVoLTEQualSRVCCtoGsm) parameter to true.
5
Create the VOLTEQUALPR object.
6
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
7
Configure the Assigned VoLTE quality profile
(assignedVoLteQualProfile) parameter.
Result
VoLTE quality criteria are applied to the UEs with QCI1 bearer, and the single radio voice call
continuity (SRVCC) measurements are activated if the voice quality is considered as bad.
14.3.2 Deactivating SRVCC to GSM
Instructions to deactivate the LTE3443: VoLTE Quality-Triggered SRVCC to GSM feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
82
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNBTS object.
Object path: MRBTS›LNBTS
4
Set the Activate VoLTE quality triggered SRVCC to GSM
(actVoLTEQualSRVCCtoGsm) parameter to false.
Result
The eNB no longer applies VoLTE quality criteria to UEs with the QCI1 bearer.
14.3.3 Activating the inter-frequency mobility
Instructions to activate the LTE3723: VoLTE Quality-Triggered Inter-Frequency Mobility
feature in the network
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
83
availability.
If either of the LTE55: Support of Inter-frequency Handover or LTE1060: TDD-FDD Handover
features is activated, the LNBTS Enable interFrequency handover (actIfHo)
parameter is set to enabled.
Procedure
1
Start the WebEM application.
2
Go to the LNBTS object.
Object path: MRBTS›LNBTS
3
Set the Activate VoLTE quality triggered inter frequency mobility
(actVoLTEQualInterFreqMobility) parameter to true.
4
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
5
Optionally, configure the Assigned VoLTE quality profile
(assignedVoLteQualProfile) parameter to the corresponding value.
Object path: MRBTS›LNBTS›LNCEL
6
Go to the TGTTHRESHPR object.
Object path: MRBTS›LNBTS›TGTTHRESHPR
7
Ensure that the following parameters are configured:
Offset of threshold3a for RSRP VoLTE quality inter frequency
(threshold3aOffsetRsrpVQ)
Offset of threshold3a for RSRQ VoLTE quality inter frequency
(threshold3aOffsetRsrqVQ)
8
Go to the LNHOIF object.
Object path: MRBTS›LNBTS›LNCEL›LNHOIF
9
Configure the VoLTE quality target threshold profile identifier for
inter-frequency handover (interFreqVQTgtThreshPrId) parameter that
84
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
references the naming attribute of the related TGTTHRESHPR Target threshold
profile identifier (tgtThreshPrId) parameter.
Result
Inter-frequency handovers are implemented for UEs with voice quality problems. These UEs are
redirected to other LTE layers by using the reported A3 and A5 measurements.
14.3.4 Deactivating the inter-frequency mobility
Instructions to deactivate the LTE3723: VoLTE Quality-Triggered Inter-Frequency Mobility
feature in the network
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the LNBTS object.
Object path: MRBTS›LNBTS
3
Set the Activate VoLTE quality triggered inter frequency mobility
(actVoLTEQualInterFreqMobility) parameter to false.
Result
Inter-frequency handovers based on reported A3 and A5 measurements are no longer available
for UEs with voice quality problems.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
85
14.3.5 Verifying VoLTE inter-frequency handover based on
VoLTE quality in LTE3723
The procedure verifies the VoLTE inter-frequency handover based on VoLTE quality.
Equipment preconditions
You need the following:
All of the LTE and System Architecture Evolution (SAE) network elements (eNBs, MME, SAEGW) are in service state without any alarms.
Two LTE cells with different frequencies are on-air, either on the same eNB or on different
ones. The LTE call setup is functional in both cells.
Set up the UE International Mobile Subscriber Identity (IMSI) in the home subscriber server
(HSS) or home location register (HLR) so that it has two bearers, one default bearer with QCI5
for IMS registration and one with QCI9 for non-GBR traffic.
Application server requirements:
It's connected directly to the SGi interface.
Optionally, the SIP server is installed on the application server.
The FTP server or Jperf is installed.
PC client application requirements:
Optionally, a VoIP client is installed.
A signaling tracer to monitor both LTE air interface and S1 interface is installed.
All related functionalities are enabled by the operation and maintenance tool.
Before you start
86
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 17: Operation and maintenance parameters related to LTE3723
Parameter name
Abbreviated name
Setting during test
Managed object
Activate VoLTE quality
triggered inter frequency
mobility
actVoLTEQualInterFreq
Mobility
true
MRBTS/LNBTS
VoLTE quality target
threshold profile
identifier for interfrequency handover
interFreqVQTgtThreshP
rId
1
MRBTS/LNBTS/LNCEL/LNH
OIF
Offset of threshold3a for
RSRP VoLTE quality inter
frequency
threshold3aOffsetRsrp
VQ
0.0
MRBTS/LNBTS/TGTTHRESH
PR
Offset of threshold3a for
RSRQ VoLTE quality inter
frequency
threshold3aOffsetRsrq
VQ
0.0
MRBTS/LNBTS/TGTTHRESH
PR
Target threshold profile
identifier
tgtThreshPrId
1
MRBTS/LNBTS/TGTTHRESH
PR
Assigned VoLTE quality
profile
assignedVoLteQualProf
ile
1
MRBTS/LNBTS/LNCEL
VoLTE quality profile
identifier
voLteQualPrId
1
MRBTS/LNBTS/VOLTEQUAL
PR
Bad quality residual BLER
threshold
badQualityRBlerThres
12
MRBTS/LNBTS/VOLTEQUAL
PR
Good quality residual BLER
threshold
goodQualityRBlerThres
11
MRBTS/LNBTS/VOLTEQUAL
PR
Residual BLER condition
time to trigger
rBlerCondTimeToTrigge
r
0.5
MRBTS/LNBTS/VOLTEQUAL
PR
Bad quality DL voice gap
threshold
badQualityDLGapThres
0.5
MRBTS/LNBTS/VOLTEQUAL
PR
Bad quality UL voice gap
threshold
badQualityULGapThres
0.5
MRBTS/LNBTS/VOLTEQUAL
PR
Good quality UL DL voice
gap threshold
goodQualityGapThres
2.5
MRBTS/LNBTS/VOLTEQUAL
PR
Activate support of
conversational voice bearer
actConvVoice
true
MRBTS/LNBTS/LNBTS
Activate multiple bearers
actMultBearers
true
MRBTS/LNBTS
Activate service based
mobility thresholds
actServBasedMobThr
false
MRBTS/LNBTS
Procedure
1
Attach the UE and make a VoLTE call on an LTE cell.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
87
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
1.1
Set up the UE IMSI in the HSS or HLR so that it has two bearers, one default bearer
with QCI5 for IMS registration and one with QCI9 for non-GBR traffic.
1.2
Attach one UE to the BTS.
1.3
Establish a circuit-switched call to the other UE by dialing its number (for example, a
+IMSI number).
The GBR bearer QCI1 must be established.
1.4
Establish packet-switched traffic.
It's sent through the QCI9 bearer.
Note:
The test setup assumes the use of a default bearer only to build up the VoIP bearer
on top (QCI5). In case of performing any GBR or non-GBR packet-switched traffic, a
second QCI9 bearer must be established over an access point name (APN) defined at
UE level.
This is the common approach for configuring voice services over LTE. The main reason
is to prevent the preemption of the default bearer for IMS signaling. Therefore, the UE
can attempt calls over the QCI5 default bearer, and to call any number anytime.
Step result
The attached procedure is successful for the default QCI5 bearer, with IMS signaling
configured at the eNB. To achieve this, the correct profile must be configured in the HSS.
The UE is successfully registered in the IMS and ready to call (right after the attach
procedure). As a result, the UE can perform or receive calls. The Session Initiation Protocol
(SIP) protocol REGISTER message is sent to the IMS. A confirmation is received with the
200 OK message.
When inviting some other party number, the policy and charging rules function (PCRF)
must trigger the QCI1 bearer establishment for VoIP. Then, the Real-Time Transport
Protocol (RTP) and RTP control protocol traffic moves over to this bearer. This is achieved
through the profile configured in the call session control function, which triggers the PCRF
with the correct QoS bearer combination, in this case only a QCI1 dedicated bearer.
88
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
2
Perform an inter-frequency handover triggered by Packet Data Convergence Protocol (PDCP)
protocol data unit (PDU) gaps.
The voice break period is a period of consecutive QCI1 DL/UL PDCP packet losses or discards
at eNB level. The triggered consecutive QCI1 DL/UL PDCP packet losses or discards increase
the DL/UL voice break period above the configurable threshold.
The following methods can trigger QCI1 DL/UL PDCP packet losses or discards:
Increase the number of VoLTE users by using a simulator in laboratory conditions.
Triger the DL GBR and DL non-GBR traffic to occupy as many physical resource blocks
(PRBs) as possible.
Bring the UE in worse radio conditions by increasing the attenuation value (because the
more UEs are moving towards the cell edge, the more physical radio resources are needed
to keep the requested GBR requirements for VoLTE traffic).
Step result
The inter-frequency measurements are activated for the VoLTE UE. The inter-frequency
handover is successful.
3
Perform an inter-frequency handover triggered by high UL residual block error rate (BLER).
The following methods can bring the test UE to high UL residual BLER conditions:
Increase the interference or noise in the UL spectrum by using a signaling generator in
laboratory.
Bring the UE in worse radio conditions by increasing the attenuation value.
Step result
The eNB reports the inter-frequency A3 or A5 event based on MAC UL residual BLER
conditions (based on LTE2493). The inter-frequency measurements are activated for the
VoLTE UE.
The inter-frequency handover is successful.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
89
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Figure 8: Inter-frequency handover triggered by high UL residual BLER
14.4 Procedures for VoLTE calls-specific frequency layers
14.4.1 Activating the inter-frequency service-based
handover
Instructions to activate and configure the LTE1127: Service Base Mobility Trigger feature in the
network
90
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
The following features must be activated before activating the LTE1127: Service Base Mobility
Trigger feature:
LTE10: EPS Bearers for Conversational Voice
Set the LNBTS_FDD/LNBTS_TDD Activate support of conversational voice
bearer (actConvVoice) parameter to true.
LTE55: Inter-Frequency Handover
Set the LNBTS Enable interFrequency handover (actIfHo) parameter to
enabled.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNBTS_FDD object.
Object path: MRBTS›LNBTS›LNBTS_FDD
4
Set the Activate inter-frequency service based handover
(actInterFreqServiceBasedHo) parameter to true.
5
Create one MODPR object on the selected LNBTS object, if it doesn't exist.
Object path: MRBTS›LNBTS›MODPR
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
91
6
Configure the Frequency layer list for VoLTE service based HO
(freqLayListServiceBasedHo) parameter.
7
Create one MOPR object on the selected LNBTS object, if the LTE490 feature is enabled.
Object path: MRBTS›LNBTS›MOPR
7.1
Configure the Mobility profile identifier (moPrId) parameter.
7.2
Configure the Frequency layer list for VoLTE service based HO
(freqLayListServiceBasedHo) parameter.
8
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
9
Configure the Inter-freq. service based HO retry timer
(iFServiceBasedHoRetryTimer) parameter.
10 Create at least one LNHOIF object on the selected LNCEL object.
You need an LNHOIF object for each frequency in the Frequency layer list for
VoLTE service based HO (freqLayListServiceBasedHo) parameter.
10.1 Configure the LNHOIF Neighbor interfrequency LTE cell handover
identifier (lnHoIfId) parameter.
10.2 Configure the LNHOIF Eutra carrier info (eutraCarrierInfo) parameter.
10.3 Configure the LNHOIF Measurement bandwidth (measurementBandwidth)
parameter.
10.4 Configure the LNHOIF Presence antenna port1 (interPresAntP)
parameter.
10.5 Configure the LNHOIF Inter-freq. service based threshold RSRP
target filter (thresholdRsrpIFSBFilter) parameter.
10.6 Configure the LNHOIF Inter-freq. service based threshold RSRQ
target filter (thresholdRsrqIFSBFilter) parameter.
92
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Result
Specific frequency layers for VoLTE calls can be configured. QCI1 traffic is offloaded to these
VoLTE preferred frequency layers.
14.4.2 Deactivating the inter-frequency service-based
handover
Instructions to deactivate the LTE1127: Service Base Mobility Trigger feature in the network
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Configuration›Configuration Management›Navigation
Panel›Steps›Radio Network Configuration›Parameter Editor
Configuration›Configuration Management›Parameter Editor
3
Go to the LNBTS_FDD object.
Object path: MRBTS›LNBTS›LNBTS_FDD
4
Set the Activate inter-frequency service based handover
(actInterFreqServiceBasedHo) parameter to false.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
93
Result
VoLTE preferred frequencies can't be configured. QCI1 traffic is served by all frequency layers
instead of VoLTE preferred frequency layers.
14.4.3 Activating the dedicated VoLTE inter-frequency
handover
Instructions to activate the LTE1942: Dedicated VoLTE Inter-frequency Target Frequency List
feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
The following features must be activated before activating the LTE1942: Dedicated VoLTE Interfrequency Target Frequency List feature:
LTE10: EPS Bearers for Conversational Voice
Set the LNBTS_FDD/LNBTS_TDD Activate support of conversational voice
bearer (actConvVoice) parameter to true. The LTE10 feature requires the LTE7:
Support of multiple EPS bearer feature to be activated (the LNBTS Activate Multiple
bearers (actMultBearers) parameter must be set to true).
LTE55: Inter-Frequency Handover
Set the LNBTS Enable InterFrequency Handover (actIfHo) parameter to
enabled.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
94
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Create one MODPR object on the selected LNBTS object.
Object path: MRBTS›LNBTS›MODPR
4
Set the Auto adaptation to freq. layers of all neighbour cells
(autoAdapt) parameter to false.
5
Go to the LNBTS_FDD or LNBTS_TDD object, depending on your needs.
Object path for FDD: MRBTS›LNBTS›LNBTS_FDD
Object path for TDD: MRBTS›LNBTS›LNBTS_TDD
6
Set the Activate dedicated VoLTE inter-frequency handover
(actDedVoLteInterFreqHo) parameter to true.
7
Optional:
Create one MOPR object on the selected LNBTS object.
Object path: MRBTS›LNBTS›MOPR
8
Go to the MOPR or MODPR object, depending on your needs.
Object path for FDD: MRBTS›LNBTS›MOPR
Object path for TDD: MRBTS›LNBTS›MODPR
9
Create and configure the Frequency layer list for ded. VoLTE interfrequency HO (freqLayListDedVoLteHo) list.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
95
Note:
If the LTE1127: Service Base Mobility Trigger feature is enabled, then the
MOPR/MODPR Frequency layer list for ded. VoLTE interfrequency HO (freqLayListDedVoLteHo) list must contain frequencies of
corresponding MOPR/MODPR Frequency layer list for VoLTE service
based HO (freqLayListServiceBasedHo).
Result
LTE neighbor cells can be defined as targets for VoLTE coverage and load-based handovers.
VoLTE calls can be moved to VoLTE preferred frequency layers, not only during service based
handover upon QCI1 bearer establishment, but also during load-based handovers.
14.4.4 Deactivating the dedicated VoLTE inter-frequency
handover
Instructions to deactivate the LTE1942: Dedicated VoLTE Inter-frequency Target Frequency
List feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
96
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNBTS_FDD or LNBTS_TDD object, depending on your needs.
Object path for FDD: MRBTS›LNBTS›LNBTS_FDD
Object path for TDD: MRBTS›LNBTS›LNBTS_TDD
4
Set the Activate dedicated VoLTE inter-frequency handover
(actDedVoLteInterFreqHo) parameter to false.
Result
The possibility to define specific LTE layers as targets for VoLTE coverage and load based
handovers is not available. All LTE neighbor cells are considered as potential targets for handovers.
14.4.5 Activating the service-based handover mode
Instructions to activate the LTE2503: Emergency Call-based Mobility Trigger feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure interrupts service availability,
either through a BTS restart or cell locking. Activating the configuration plan triggers these actions
on the BTS side.
The following features must be activated before activating the LTE2503: Emergency Call-Based
Mobility Trigger feature:
LTE10: EPS Bearers for Conversational Voice
Set the LNBTS_FDD/LNBTS_TDD Activate support of conversational voice
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
97
bearer (actConvVoice) parameter to true.
LTE1127: Service Based Mobility Trigger
Set the LNBTS_FDD/LNBTS_TDD Activate inter-frequency service based
handover (actInterFreqServiceBasedHo) parameter to true.
LTE572: IMS Emergency Sessions
Set the LNBTS_FDD/LNBTS_TDD Activate support of IMS emergency
sessions for Rel 9 UE (actIMSEmerSessR9) parameter to true.
The LNBTS Activate multiple bearers (actMultBearers) parameter must be set
to true.
The LNBTSAuto adaptation to freq. layers of all neighbour cells
(autoAdapt) parameter must be set to false.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
4
Configure the Service based handover mode (sbHoMode) parameter to a value
other than all.
Result
Candidates for service based handover can be specified. Either only UEs with ongoing Emergency
Calls, or all UEs with QCI1 bearer established can be specified as candidates for handover to VoLTE
preferred frequencies.
98
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
14.4.6 Deactivating the service-based handover mode
Instructions to deactivate the LTE2503: Emergency Call-based Mobility Trigger feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
4
Set the Service based handover mode (sbHoMode) parameter to all.
Result
Candidates for service based handover can't be specified. All UEs with QCI1 bearer established are
considered for service based handover.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
99
14.5 Procedures for VoLTE protection timer trigger
14.5.1 Activating the VoLTE protection timer trigger
Instructions to activate the LTE2430: QCI1 Establishment Triggered Protection Timer feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
The LTE10: EPS Bearers for Conversational Voice feature must be activated before activating
the LTE2430: QCI1 Establishment Triggered Protection Timer feature. Set the
LNBTS_FDD/LNBTS_TDD Activate support of conversational voice bearer
(actConvVoice) parameter to true.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNBTS object.
Object path: MRBTS›LNBTS
4
Set the Activate RRC connected mode while no activity
(actRrcConnNoActivity) parameter to true.
100
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
5
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
6
Set the QCI1 protection timer (qci1ProtectionTimer) parameter to a value
that is equal to or higher than the Inactivity timer (inactivityTimer) parameter.
Result
A QCI1 protection timer is introduced which prevents a VoLTE UE from going into RRC Idle mode
due to inactivity early in the call set up phase, when there is no traffic on the QCI1 bearer until the
call is answered.
14.5.2 Deactivating the VoLTE protection timer trigger
Instructions to deactivate the LTE2430: QCI1 Establishment Triggered Protection Timer
feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
101
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
3
Go to the LNBTS object.
Object path: MRBTS›LNBTS
4
Set the Activate RRC connected mode while no activity
(actRrcConnNoActivity) parameter to false.
Result
A VoLTE UE with QCI1 data radio bearer established is moved to RRC Idle mode after the RRC
inactivity timer expires. This occurs early in the call set up phase when there is no traffic on QCI1
bearer until the call is answered.
14.6 Procedures for the extension of RRC-connection time
after handover
14.6.1 Activating the extension of RRC-connection time after
handover
Instructions to activate the CB009430: Prohibit Timer for RRC Connection Release with
Mobility feature in the network
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Make sure that the BTS is commissioned and operational.
Make sure that BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Note:
Both cells involved in the handover need to have the CB009430 feature activated.
102
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Procedure
1
Go to Parameter Editor.
2
Set the LNBTSActivate prohibit timer for RRC Connection Release
after last QCI1 bearer release (actRrcConnRelDelay) parameter to true.
Object path: MRBTS›LNBTS
3
Configure the LNCELQCI1 RRC Connection Release prohibit timer
(qci1RrcRelDelayTimer) parameter.
Object path: MRBTS›LNBTS›LNCEL
4
Set the LNCELActivate forwarding of elapsed time of prohibit timer
for RRC Connection Release (actRrcConnRelDelayForwarding) parameter to
true.
Object path: MRBTS›LNBTS›LNCEL
The parameter needs to be configured for the same LNCEL managed object as in step 3.
Result
Information about the time elapsed since the last QCI1 bearer was released for the UE is
transmitted from the source cell to the target cell during the handover.
14.6.2 Deactivating the extension of RRC-connection time
after handover
Instructions to deactivate the CB009430: Prohibit Timer for RRC Connection Release with
Mobility feature in the network
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Make sure that the BTS is commissioned and operational.
Make sure that BTS elements are detected and configured.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
103
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Go to Parameter Editor.
2
Set the LNCEL Activate forwarding of elapsed time of prohibit timer
for RRC Connection Release (actRrcConnRelDelayForwarding) parameter to
false.
Object path: MRBTS›LNBTS›LNCEL
Result
When the CB009430 feature is disabled on at least one cell involved in the handover, the target
cell doesn't use information about the time elapsed since the last QCI1 bearer was released for
the UE.
14.7 Procedures for VoLTE improvements
14.7.1 Activating the VoLTE coverage boosting in UL
scheduling
Instructions to activate the LTE2098: VoLTE Uplink Coverage Boosting feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
104
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
The following features must be activated before activating the LTE2098: VoLTE Uplink
Coverage Boosting feature:
LTE10: EPS Bearers for Conversational Voice
Set the LNBTS_FDD Activate support of conversational voice bearer
(actConvVoice) parameter to true.
LTE11: Robust Header Compression
Set the LNBTS Activate PDCP robust header compression (actPdcpRohc)
parameter to true.
LTE1034: Extended Uplink Link Adaptation or LTE1543: SON LTE BTS Auto Connectivity
Set the LNCEL Activate uplink link adaptation (actUlLnkAdp) parameter to
eUlLa or fUlLa.
The following parameters must be configured:
The LNCEL Maximum number of HARQ transmission in DL for VoLTE
(harqMaxTrVoLteDl) parameter must be set to a numerical value indicating the maximum
number of HARQ transmissions.
The LNBTS Activate multiple bearers (actMultBearers) parameter must be set
to true.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
4
Create a new VoIP coverage boosting configuration (voipCovBoostConfig)
parameter structure.
4.1
Configure the following parameters:
Number of carried VoIP samples before limitation
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
105
(ulsMinNumCoverageLimitationStateCheck)
Threshold of the power headroom related to QCI1 bearer
(ulsPhrQci1Low)
Threshold hysteresis related to QCI bearer (ulsPhrQci1Hyst)
4.2
Set the Activation of VoIP coverage boosting in UL scheduling
(actVoipCovBoost) parameter to true.
5
Optional:
Configure the following parameters:
If the Periodic PHR timer (tPeriodicPhr) parameter is set higher than 20 sf
or infinity, set the Periodic PHR timer (tPeriodicPhr) parameter to 10 sf
or 20 sf.
Set the Maximum number of HARQ transmission (harqMaxTxUl) parameter to
a value greater than or equal to 5.
If the Activate extended VoLTE talk time (actQci1eVTT) parameter is set
to true, then the Maximum number of HARQ transmission in UL for
QCI1 (qci1HarqMaxTxUl) parameter must be equal to the Maximum number of
HARQ transmission in UL (harqMaxTxUl) parameter.
6
Configure the following parameters to improve VoLTE coverage boosting.
Activates VoLTE coverage boosting improvements
(actVoipCovBoostEnh)
Maximum number of PRBs after coverage boosting
(ulsMaxNumPrbAfterCovBoost)
Minimum time to enter PHR based TTI bundling
(ttibPhrDwellTimeIn)
Minimum time to exit PHR based TTI bundling
(ttibPhrDwellTimeOut)
Minimum time to enter TTI bundling after Bearer Setup
(ttibMinDelayAfterBearerSetup)
106
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Note:
The ttibMinDelayAfterBearerSetup parameter must not be configured
for TDD.
Note:
To enhance the coverage boosting functionality, set the actVoipCovBoostEnh
parameter to on_ttib_entry_BLER_SINR_based. If the
actVoipCovBoostEnh parameter is set to on_ttib_entry_PHR_based,
UEs can be under the sensitivity-based scheduling for most of the time, depending
also on the PHR threshold defined by the ulsPhrQci1Low parameter. The
on_ttib_entry_PHR_based option can increase the UL latency of data
bearers and, for example, decrease the TCP DL peak throughput.
Result
The UL coverage for VoLTE UEs is improved by up to 2.5 dB when in TTI bundling mode, and up to
1.5 dB outside of TTI bundling mode.
14.7.2 Deactivating the VoLTE UL coverage boosting
Instructions to deactivate the LTE2098: VoLTE Uplink Coverage Boosting feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if all BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
107
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
4
Set the Activation of VoIP coverage boosting in UL scheduling
(actVoipCovBoost) parameter to false.
5
Optional:
Delete the VoIP coverage boosting configuration (voipCovBoostConfig)
parameter structure.
Result
The improvement to UL coverage for VoLTE UEs (up to 2.5 dB when in TTI bundling mode, and up
to 1.5 dB outside of TTI bundling mode) is no longer available.
14.7.3 Activating the adaptive codec bit rate
Instructions to activate the LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation
feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
108
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Modifying the settings of the parameters used in this procedure interrupts service availability,
either through a BTS restart or cell locking. Activating the configuration plan triggers these actions
on the BTS side.
The following features must be activated before activating the LTE4244: VoLTE Coverage
Extension by Codec Rate Adaptation feature:
LTE10: EPS Bearers for Conversational Voice
Set the LNBTS_FDD /LNBTS_TDDActivate support of conversational voice
bearer (actConvVoice) parameter to true.
LTE587: Multiple GBR EPS Bearers per UE
Set the LNBTS Activate multiple GBR bearers (actMultGbrBearers) parameter
to true.
LTE2774: Source Rate Based UL Grant Assignment for VoLTE
Set the LNCEL Activate VoLTE source rate based UL assignment
(actVoLteSrcRate) parameter to true.
LTE497: Smart Admission Control
Set the LNBTS Activate enhanced AC and GBR services
(actEnhAcAndGbrServices) parameter to true.
Note:
The LTE497: Smart Admission Control feature activation is required if the LNCEL
Consider cell PRB usage in RBR (rbrCellPrbUsage) parameter is set to
true.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNCEL object.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
109
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Object path: MRBTS›LNBTS›LNCEL
4
Set the Activate recommended bit rate (actRbr) parameter to true.
5
Create and configure the RBR configuration (rbrConfig) parameter structure.
Result
The codec bit rate is adapted according to current radio conditions. The recommended bit rate
(RBR) value sent to the UE equals the available link capacity (bit rate) calculated by the eNB, and
the UE can use this RBR value for codec rate adaptation.
14.7.4 Deactivating the adaptive codec bit rate
Instructions to deactivate the LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation
feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if all BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
110
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Go to the LNCEL object.
3
Object path: MRBTS›LNBTS›LNCEL
4
Set the Activate recommended bit rate (actRbr) parameter to false.
5
Optional:
Delete the RBR configuration (rbrConfig) parameter structure.
Result
UEs choose the highest possible codec bit rate during VoLTE call establishment. The same codec
bit rate is maintained through the entire voice call and is not adjusted according to radio
conditions.
14.7.5 Verifying the recommended bit rate due to varying
radio conditions
Instructions to verify if the LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation
feature has been correctly activated and configured
Equipment preconditions
During the test preparation, make sure that:
the eNB and NetAct are in service, and a connection to the eNB is established through OMS
(for example, the WebEM).
the ANBR/ANBRQ-capable UEs are available.
the LTE UE tracing tool (for example, QXDM) is connected.
the LTE4244: VoLTE Coverage Extension by Codec Rate Adaptation is enabled.
Before you start
Check if the ANBR/ANBRQ-capable UE is available. You can do it by checking the
recommendedBitRate-r14 and recommendedBitRateQuery-r14 information elements
(IEs):
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
111
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Use subject to agreed restrictions on disclosure and use.
Issue 02A
© 2024 Nokia. Nokia Confidential Information
112
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 18: Parameters configured during the test
Parameter name
Abbreviation
Range and step
Setting during test
Managed object
Activate
recommended bit
rate
actRbr
true
false
true
MRBTS/LNBTS/LNCEL
Consider cell
PRB usage in
RBR
rbrCellPrbUsage
true
false
true
MRBTS/LNBTS/LNCEL
RBR DL queries
response mode
rbrDlQueryRespM
ode
UL_RBR
None
UL_RBR
MRBTS/LNBTS/LNCEL
Maximal RBR
index
rbrIndexHighThr
eshold
1-18
step: 1
18
MRBTS/LNBTS/LNCEL
Ave. meas. time
for avail. bit
rate
measurement
rbrMeasTime
0.2-5
step: 0.2
2
MRBTS/LNBTS/LNCEL
RBR operational
mode
rbrOperMode
UeQueryAllowed
eNbUnsolicitedAllowed
bothAllowed
bothAllowed
MRBTS/LNBTS/LNCEL
RBR additional
power headroom
UL
rbrPhrDelta
-10-10
step: 1
0
MRBTS/LNBTS/LNCEL
RBR query wait
timer
rbrQueryWaitTim
er
30s
12s
6s
3s
1.6s
0.8s
0.4s
0s
1.6s
MRBTS/LNBTS/LNCEL
Step size for
RBR index downswitching
rbrStepSizeDown
1-4
step: 1
1
MRBTS/LNBTS/LNCEL
Step size for
RBR index upswitching
rbrStepSizeUp
1-4
step: 1
1
MRBTS/LNBTS/LNCEL
RBR wait timer
for next RBR
message for upswitching
rbrUpWaitTimer
0-5
step: 0.2
2
MRBTS/LNBTS/LNCEL_TDD
Procedure
1
Configure the LTE cell with the required parameters.
2
Power on the UE and connect it to a tested cell in very good radio conditions.
3
Set up the VoLTE bearer GBR.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
113
Step result
The UE connection and GBR bearer setup were successful. An unsolicited message is sent to
the UE. The recommended bit rate index is upper limited by the Maximal RBR index
(rbrIndexHighThreshold) parameter.
4
Record previous index to the last recommended bit rate for further comparison.
5
Move the UE toward worse radio conditions.
Step result
The unsolicited recommended bit rate message is sent to the UE for UL with reduced
available bit rate or recommended bit rate index.
B022B-PS_Q_4379 VIP/macps.dl.sch.rbr.RbrCalculator|enb:109040
cell:1
crnti=7976|Unsolicited RBR: lcId=5 rrmCurrentRbrIndexUl=8 lastUeRbrIndex=9
The recommended bit rate index is upper limited by the LNCELMaximal RBR index
(rbrIndexHighThreshold) parameter.
6
Repeat step 5 until the lowest recommended bit rate index is reached.
Step result
The recommended bit rate index is degraded from recommended bit rate 18 to
recommended bit rate 2.
B022B-PS_Q_4379 VIP/macps.dl.sch.rbr.RbrIndexCalculator|Calculated RBR Indexes:
rrmRbrIndexUl = 18 rrmRbrGbrIndexUl = 10 rrmRbrEbrIndexUl = 0
B022B-PS_Q_4379 VIP/macps.dl.sch.rbr.RbrIndexCalculator|Calculated RBR Indexes:
rrmRbrIndexUl = 2 rrmRbrGbrIndexUl = 10 rrmRbrEbrIndexUl = 0
114
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
The index for the last recommended bit rate value is updated to the index for the measured
effective bit rate value. The RBR wait timer for next RBR message for upswitching (rbrUpWaitTimer) parameter is restarted. MAC layer control element for the
recommended bit rate is sent to the UE for UL.
7
Move UE back to the better radio conditions.
Step result
The unsolicited recommended bit rate message is sent to the UE for UL with reduced
available bit rate or recommended bit rate index.
B022B-PS_Q_4379 VIP/macps.dl.sch.rbr.RbrCalculator|enb:109040 cell:1
crnti=7976|Unsolicited RBR: lcId=5 rrmCurrentRbrIndexUl=5 lastUeRbrIndex=4
8
Repeat step 7 until the highest recommended bit rate index is reached.
Step result
The recommended bit rate index is upgraded from recommended bit rate 2 to
recommended bit rate 18.
B022B-PS_Q_4379 VIP/macps.dl.sch.rbr.RbrIndexCalculator|Calculated RBR Indexes:
rrmRbrIndexUl = 18 rrmRbrGbrIndexUl = 10 rrmRbrEbrIndexUl = 0
The index for the last recommended bit rate value is updated to the index for the measured
effective bit rate value. The RBR wait timer for next RBR message for upswitching (rbrUpWaitTimer) parameter is restarted. MAC layer control element for the
recommended bit rate is sent to the UE for UL.
Result
Depending on radio conditions, the eNB calculates/communicates recommended bit rates to
adapt the codec bit rates, by sending unsolicited messages to the UE.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
115
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
14.7.6 Activating VoLTE source rate-based UL assignment
Instructions to activate the LTE2774: Source Rate-Based UL Grant Assignment for VoLTE
feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if all BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
The LTE10: EPS Bearers for Conversational Voice feature must be activated before activating
the LTE2774: Source Rate Based UL Grant Assignment for VoLTE feature. The
LNBTS_FDD/LNBTS_TDD Activate support of conversational voice bearer
(actConvVoice) parameter must be set to true.
The following parameters must be configured:
The LNCEL Maximum number of HARQ transmission in DL for VoLTE
(harqMaxTrVoLteDl) parameter must be set to a numerical value indicating the maximum
number of HARQ transmissions.
The LNBTS Activate multiple bearers (actMultBearers) parameter must be set
to true.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
116
Go to the LNCEL object.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Object path: MRBTS›LNBTS›LNCEL
4
Set the Activate VoLTE source rate based UL assignment
(actVoLteSrcRate) parameter to true.
Result
When the buffer status report is not available, UL resources are allocated based on traffic
measurements. Only data received during periods where voice data packets are transmitted (talk
spurts) is used to evaluate the UL bit rate.
14.7.7 Deactivating VoLTE source rate-based UL assignment
Instructions to deactivate the LTE2774: Source Rate-Based UL Grant Assignment for VoLTE
feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application.
2
Go to the Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
117
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
3
Go to the LNCEL object.
Object path: MRBTS›LNBTS›LNCEL
4
Set the Activate VoLTE source rate based UL assignment
(actVoLteSrcRate) parameter to false.
Result
When the buffer status report is not available, the eNB allocates UL resources based on GBR
requirements from MME information.
14.7.8 Verifying VoLTE source rate-based UL assignment
Instructions to verify if the LTE2774: Source Rate-Based UL Grant Assignment for VoLTE
feature has been correctly activated and configured and if it works as expected
Equipment preconditions
You need the following:
An AirScale BTS or BTS that supports one of the following configurations: 5 MHz, 10 MHz, 15
MHz, or 20 MHz.
Note:
This check is of high priority for AirScale BTS.
A UE supporting VoLTE.
The VoLTE environment is working properly.
The S1-AP communicated GBR bit rate of the VoLTE bearer is higher than necessary for the
codec being used.
118
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
14.7.8.1 Making a VoLTE call in good RF conditions with
LTE2774 disabled
This procedure verifies if a VoLTE call works properly with the LTE2774 feature disabled.
Before you start
Table 19: Parameters related to the verification procedures of the LTE2774 feature
Full name
Abbreviated name
Parameter
Managed object
value
Activate VoLTE
source rate
based UL
assignment
actVoLteSrcRate
false
LNCEL
Max packet
aggregation UL
ulsMaxPacketAgg
1
LNCEL
Procedure
1
The UE is set up with a VoLTE bearer in good RF conditions such that a full voice packet can
be transmitted in UL without segmentation. Besides voice traffic, the VoLTE UE doesn't
generate any other traffic.
2
After some time, the VoLTE bearer is disconnected.
3
Collect the UE log.
4
Collect the transmission time interval (TTI) trace log.
Result
The VoLTE call works properly with the LTE2774 feature disabled.
The UE log and TTI trace log are collected.
With the LTE2774 feature disabled, the VoLTE calls padding bits level is 10 or 42.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
119
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
14.7.8.2 Making a VoLTE call in good RF conditions with
LTE2774 enabled and move to poor RF conditions
This procedure verifies if with the LTE2774 feature activated, the amount of padding bits in
VoLTE UE UL transmission during talk spurts period is reduced or eliminated when compared to
the case when the LTE2774 feature is deactivating.
Before you start
Table 20: Parameters related to the verification procedures of the LTE2774 feature
Full name
Abbreviated name
Parameter
Managed object
value
Activate VoLTE
source rate
based UL
assignment
actVoLteSrcRate
true
LNCEL
Max packet
aggregation UL
ulsMaxPacketAgg
1
LNCEL
120
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Procedure
1
The UE reestablishes the VoLTE bearer in the same RF conditions as in the Making a VoLTE
call in good RF conditions with LTE2774 disabled procedure.
2
A three-way call is established or a vocoder rate adaptation is performed.
Step result
The bitrate of the UL VoLTE bearer increases for the UE.
3
After some time, the three-way call or the vocoder rate adaptation ends.
Step result
The bitrate of the UL VoLTE bearer decreases for the UE.
4
After some time, the RF conditions for VoLTE UEs are deteriorated until packet segmentation
takes place.
5
Collect the UE log during the steps above.
6
Collect the transmission time interval (TTI) trace log during the steps above.
Result
From UE log and TTI trace log - the amount of padding bits in VoLTE UEs UL transmission
during talk spurts period is reduced or eliminated when compared with the situation when the
LTE2774 feature is disabled.
From UE log - the padding bits level of the VoLTE call is 6 (reduced compared to values when
the LTE2774 feature is deactivated).
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
121
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Regardless of the UL VoLTE bearers bitrate change (increasing or decreasing), the amount of
padding in VoLTE UEs UL transmissions during talk spurts period isn't impacted. The UL
transport block size (TBS) during talk spurts is adapted accordingly.
When VoLTE UEs' RF conditions deteriorate, the VoLTE packet segmentation takes place. The
overall amount of padding in VoLTE UEs' UL transmissions, delivered in multiple segments,
stays at the same level (reduced or eliminated when compared to the situation when the
LTE2774 feature is deactivated).
14.8 Procedures for EN-DC setup during VoLTE services
14.8.1 Activating the restrictions for EN-DC setup during
VoLTE
Instructions to configure restrictions allowing to prevent the EN-DC setup during VoLTE,
introduced by the LTE5388: VoLTE without EN-DC feature
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
122
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
The LTE4088: LTE-NR Dual Connectivity Option 3x feature must be activated, with the LNBTS
Activation LTE-NR Dual-Connectivity (actLteNrDualConnectivity) parameter
set to true, and configured following the Configuring LTE4088 procedure.
Procedure
1
Start the WebEM application.
2
Go to Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNBTS object.
Object path: MRBTS›LNBTS
4
Set the Activate the prevention of EN-DC setup during VoLTE
(actVoLteNoEnDc) parameter to a value other than disabled.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
123
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Table 21: The Activate the prevention of EN-DC setup during VoLTE
(actVoLteNoEnDc) parameter values and their description
Parameter values
Parameter value description
disabled
The EN-DC setup is allowed
non-emergency QCI1 calls
The EN-DC setup prevented during nonemergency QCI1 calls.
emergency QCI1 calls
The EN-DC setup prevented during emergency
QCI1 calls.
all QCI1 calls
The EN-DC setup prevented during all QCI1 calls.
QCI65 and QCI66 calls
The EN-DC setup prevented during QCI65 and
QCI66 calls.
QCI65/66 and non-emergency
QCI1
The EN-DC setup prevented during QCI65/66 and
normal non-emergency QCI1 calls.
QCI65/66 and emergency
QCI1
The EN-DC setup prevented during QCI65/66 and
emergency QCI1 calls.
QCI65/66 and all QCI1
calls
The EN-DC setup prevented during QCI65/66 and
all QCI1 calls.
Result
Setting the LNBTS Activate the prevention of EN-DC setup during VoLTE
(actVoLteNoEnDc) parameter to value other than disabled prevents the EN-DC setup
during VoLTE in configured circumstances.
14.8.2 Deactivating the restrictions for EN-DC setup during
VoLTE
Instructions to remove the restrictions for the EN-DC setup during VoLTE, introduced by the
LTE5388: VoLTE without EN-DC feature
124
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Before you start
See Configuring Features with Web Element Manager for general management tool
instructions.
Check if the BTS is commissioned and operational.
Check if BTS elements are detected and configured.
Modifying the settings of the parameters used in this procedure doesn't interrupt service
availability.
Procedure
1
Start the WebEM application
2
Go to Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
3
Go to the LNBTS object.
Object path: MRBTS›LNBTS
4
Set the Activate the prevention of EN-DC setup during VoLTE
(actVoLteNoEnDc) parameter to disabled.
Result
The EN-DC setup during VoLTE is allowed.
14.8.3 Rollback to the LTE5542 feature solution
Instructions to roll back to the LTE5524: Ongoing QCI1 Prevents EN-DC Setup feature solution,
introduced by the LTE5388: VoLTE without EN-DC feature
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
125
Procedure
1
Go to Parameter Editor.
Select from the available options
Go to Configuration›Configuration Management›Parameter Editor.
Use the PE keyboard shortcut.
Click the Parameter Editor icon in the top menu.
2
Go to the LNBTS object.
Object path: MRBTS›LNBTS
3
Set the Activate keep En-Dc during VoLte setup (actVoLteNoEnDcDrop)
parameter to true.
Result
With the LNBTS Activate keep En-Dc during VoLte setup
(actVoLteNoEnDcDrop) parameter enabled, the UE doesn't trigger the B1-NR measurements
while VoLTE connection is ongoing (meaning, when there is either an emergency or nonemergency QCI1 bearer established). Without B1-NR measurements, the secondary gNB (SgNB)
addition procedure isn't attempted (E-UTRA NR Dual Connectivity (EN-DC) is not established).
126
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
VoLTE glossary
A4 event
A part of a signaling procedure in which the UE sends measurement
reports. The A4 event occurs when a neighbor cell becomes better
than an absolute threshold. Different conditions cause different
events to the BTS.
Allocation and Retention Priority
(ARP)
A QoS parameter that's used to differentiate between bearers when
performing allocation and retention of a bearer. The ARP can be used
by the network to decide whether a certain bearer can be established
or must be rejected in case of resource limitations. Also, it can be
used to decide which bearers are dropped in case of exceptional
resource limitations, for instance, during a handover. This QoS
parameter, however, doesn't affect the packet forwarding in the
network.
B1 event
Part of a signaling procedure in which the UE sends measurement
reports. The B1 event takes place when a non-LTE neighbor cell
becomes better than an absolute threshold.
block error rate (BLER)
Ratio of the number of incorrectly received blocks to the total
number of blocks transferred. Multiple block error ratios may be used
to predict block error probability.
buffer status report (BSR)
Information sent to the BTS about the amount of data available for
transmission in UL buffers of the UE.
Carrier Aggregation (CA)
In radio resource management, a method of increasing the bit rate
by increasing the bandwidth. It's done by scheduling the data to more
than one cell (component carrier (CC)). In CA, one cell acts as a
primary cell (PCell), and is changed only during a handover, while the
other CCs are served by secondary cells (SCells) and can be added or
removed as required.
Channel Quality Indicator (CQI)
In high-speed DL packet access, an indicator of the channel quality
that's calculated using transmission time interval (TTI) and a channel
throughput reported by the UE to the BTS. It's crucial for determining
the right modulation and coding scheme (MCS).
Channel Quality Indicator (CQI)
periodicity
An interval with which the CQI is being transmitted to the BTS by a
higher layer message, for example, Radio Resource Control (RRC)
transmission.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
127
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Discontinuous Reception (DRX)
Means of saving battery power by periodically and automatically
switching the UE's receiver on and off. DRX can be thought of as a
kind of sleeping mode on the receiver side of a UE.
E-UTRAN NR Dual Connectivity
(EN-DC)
A functionality in which a UE is connected to one eNB, which acts as a
master node, and to one gNB, which acts as a secondary node.
Evolved Packet System (EPS)
bearer
A connection that is used to transport user data between the UE and
Packet Data Network (PDN) gateway or serving gateway (S-GW). It can
be a default bearer or a dedicated bearer. It can consist of a radio
bearer, an S1 bearer, and possibly also an S5 or S8 bearer.
GBR
A QoS parameter defining the resource type of the bearer (dedicated
Evolved Packet System (EPS) bearer). GBR services always have the
bandwidth of the bearer guaranteed.
hybrid automatic repeat request
(HARQ)
An error control technique used to improve the data throughput. It
combines the forward error coding (FEC) and automatic repeat
request (ARQ) methods.
IP Multimedia Subsystem (IMS)
emergency session
A type of session with a specific emergency bearer that's used for
emergency calls.
modulation and coding scheme
(MCS)
A set of values defined by the 3GPP, where each MCS value defines
which modulation and coding rate is used for a data transmission. An
MCS value is assigned by the BTS for every transmission to the UE,
based on the current radio conditions.
modulation
In LTE, a method by which the data is communicated through the air.
The more complex the modulation, the higher the data rate. More
complex modulations require better conditions, that is, less
interference and a good line of sight. In LTE, the supported
modulation types are QPSK and QAM.
mean opinion score (MOS)
A numerical measure of the human judged overall quality of an event
or experience. In audio and video communications, the overall quality
is scored by algorithms that attempt to approximate the human
experience. The most commonly used rating scale ranges from 1
(bad) to 5 (excellent).
non-GBR
A QoS parameter defining the resource type of the bearer (default
Evolved Packet System (EPS) bearer) in which the number of bits to
be delivered to a receiver isn't guaranteed.
128
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Observed Time Difference of
Arrival (OTDOA)
time interval that is observed by a UE between the reception of DL
signals from two different cells. If a signal from cell 1 is received at
the moment t1, and a signal from cell 2 is received at the moment t2,
the OTDOA is t2 – t1
padding
In LTE, a process of extending a block of information to a required
length.
padding bits
The number of bits used to complete a partially used block of
information to its full length.
physical resource block (PRB)
A set of allocated physical transport carriers and the time intervals
those carriers can use to transport data. It consists of 12 subcarriers
in the frequency domain and takes 14 orthogonal frequency division
multiplexing (OFDM) symbols in the time domain. The transmission
time interval is one millisecond.
primary cell (PCell)
In carrier aggregation (CA), a cell in which a UE has established its RRC
connection. It handles both GBR and non-GBR user data, as well as
DL and UL signaling. PCell for UE is only changed at handover.
proactive UL grant
A type of uplink grant that is assigned to the UE due to DL non-GBR
data transmission.
push-to-talk (PTT)
A one-way communication function in a mobile phone that enables a
user to talk to another user, or a selected user group, while the
recipient is only listening. Push-to-talk is activated by pressing the
push-to-talk key or its equivalent in the phone. In a user group, the
turns to speak are requested by pressing the talk key and is granted
on a first-come-first-served basis.
QCI
A mechanism used in LTE to ensure bearer traffic is allocated
appropriate QoS. Different bearer traffic requires different QoS and,
therefore, different QCI values. QCI value 9 is typically used for the
default bearer of a UE/PDN for non-privileged subscribers. The QoS
concept as used in LTE networks is class-based, where each bearer
type is assigned one QCI by the network. QCI is a scalar that is used
within the BTS as a reference to node specific parameters that
control packet forwarding treatment, for example scheduling weight,
admission thresholds, and link-layer protocol configuration.
QCI1
QCI defines the quality of the packet communication provided by
LTE. QCI1 is a GBR resource type, used for services such as
conversational voice.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
129
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
Reference Signal Received Power
(RSRP)
An average power value of the reference signals
(RSs) within the frequency bandwidth.
The interference and noise components aren't considered in the
computation of RSRP. It's used to
estimate the ability of a receiver to obtain and decode
information signal needed for cell selection, reselection, and
handover procedures.
Reference Signal Received
Quality (RSRQ)
The ratio of Reference Signal Received Power (RSRP) to Received
Signal Strength Indicator (RSSI). Due to the consideration of
interference and noise in RSRQ measurement, a UE may experience
different received signal qualities at different locations. The reference
point for the RSRQ is the antenna connector of the UE. For more
details, see 3GPP TS 36.214.
S1 Application Protocol (S1-AP)
A protocol that consists of a set of commands and processes used
to manage the communication between the BTS and mobility
management entity (MME).
secondary cell (SCell)
In carrier aggregation (CA), the additional cell operating on a
secondary frequency, which may be configured for a UE once a RRC
connection is established. It provides additional bandwidth to increase
the bit rate. The SCells for an UE can be added or removed when
required.
scheduling request (SR)
A special physical layer message for the UE to ask the BTS to send an
UL Grant so that the UE can start transmitting the data.
signal-to-interference-plus-noise
ratio (SINR)
A ratio that provides information on how strong the desired signal is
compared, to the interference and noise.
sounding reference signal (SRS)
Reference signal that the BTS receives from the UE and uses to
determine the channel state and the carrier frequencies it should
assign to the UE for transmission.
Talk spurts
In the VoLTE technology, one of the two states of the transmission.
During the talk spurts period the UE sends or receives the voice data
packets. The voice packets are transmitted every 20 ms. The size of
the voice data packet depends on the used speech coding rate.
transport block size (TBS)
Number of bits in a transport block.
130
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
Issue 02A
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE
transmission time interval (TTI)
A duration of the transmission on the radio link. It is equal to the
periodicity at which a transport block set is transferred by the physical
layer on the radio interface.
user equipment (UE)
A device used directly by an end-user to communicate, for example
mobile phone or laptop with LTE adapter.
UL grant
A specific physical control channel information sent from the BTS to
the UE, detailing resource allocation it has been granted; for example,
resource allocation size and grant duration.
Voice over LTE (VoLTE)
Technology that delivers voice communication over 4G LTE networks
using the IP Multimedia Subsystem (IMS).
VoLTE bearer
A bearer with a GBR QoS Class Identifier (QCI) which denotes voice.
Specifically QCI1, QCI65, QCI66.
Issue 02A.
© 2024 Nokia. Nokia Confidential Information
Use subject to agreed restrictions on disclosure and use.
131
Copyrighted material licensed to yamin.ofkir@citymesh.com on 11-04-2025.
No further reproduction or networking is permitted. Distributed by Nokia.
VoLTE