Security Level:
www.huawei.com
HUAWEI TECHNOLOGIES CO., LTD.
Contents
01
VoLTE Introduction
02
VoLTE Basic Feature Verification

VoLTE with intra-frequency HO

SRVCC to Utran
03
HUAWEI TECHNOLOGIES CO., LTD.
VoLTE Advanced Feature Verification

VoLTE with inter-frequency HO

ROHC

TTI Bundling

DRX

UL RLC Segmentation
Huawei proprietary. No spread without permission.
Page 2
VoLTE Introduction-Concept
4G Voice Evolution
Three Stage of 4G Voice Evolution：
CS is on 2G/3G, PS is On LTE
CS fall back to 2/3G, PS is on
LTE as first priority.
Both CS and PS are on LTE.
Advantage on VoLTE Solution
SVLTE
CSFB
VoLTE
Voice Quality
2/3G Voice Quality
2/3G Voice Quality
HD Voice Quality
Access Time
Short (5~6S)
Long (8S)
Shorter (0.5~2S)
UE Power
Consumption
High
High
Low
Spectrum Effieiency
Low
Low
High (4 Time)
What is VoLTE?
VoLTE is the voice communication between UE and IMS, and the
voice is carried on PS domain.
On the early stage of LTE network deployment, the operators
haven’t implemented IMS (IP Multimedia Subsystem), they usually
take CSFB as transitional voice solution. After the IMS
implementation, they will move to the final Voice Solution as
VoLTE.
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 3
VoLTE Introduction—Basic Structure
Signaling
Description
VoLTE is voice sessions set up over IP networks between the UE and the IMS.
That is, the calling and the called parties can use voice services within an LTE
network.
Terminal
Access
Bearer
CS
eMGW
(Called)
IMS
eMSC
BTS/NodeB BSC/RNC
HLR/HSS
SCP AS
CSCF
MME
• PS service handover to 2G/3G networks when DTM (Dual Transfer Mode)
is supported
MME
SMSC
SBC
ENUM
(Caller)
S-GW
Core Network Support
Sv interface between MME and MSC enhanced for
SRVCC.
PCRF
eNodeB
• PS service suspended when DTM is not supported.
Note: SRVCC is triggered if and only if the LTE UE is going out of the LTE coverage
VOLTE AS
IM-MGW MGCF
• SRVCC （ Single-Radio Voice Call Continuity） based on LTE coverage and
inter-RAT mobility
EMSC
AS
EPC
Voice & PS service continuity
Media
MME: Mobility Management Entity
SCP：Service Control Point
CRBT：Color Ring Back Tone
MGCF: Media Gateway Control Function
CSCF：Proxy Call Session Control Function
P-GW
CRBT Platform
HSS：Home Subscriber Server
SBC：Session Border Controller
PCRF：Policy and Charging Rule Function
HSS：Home Subscriber Server
SMSC：Short Message Service Centre
Benefits
Terminal Support
• 3GPP SRVCC UE is needed to perform SRVCC

VoLTE provides UEs in the E-UTRAN with voice services, without the need of falling back to GERAN or UTRAN.

VoLTE features the following characteristics: Higher spectral efficiency, Better user experience, such as lower access
delay and better voice quality
eSRVCC：ATCF(Access Transfer Control Function)/ATGW(Access Transfer Gateway)
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 4
IMS-based Voice Services
PCRF
MME
EPC
IMS Core
E-UTRAN
SBC
/P-CSCF
S-GW/P-GW
UE
I/S-CSCF
SIP signaling streams
Default bearer: IMS signaling streams
Dedicated bearer: Voice media streams
Voice media streams
 A default bearer(QCI5) is set up for IMS signaling streams when the UE attaches to the network.
 After the UE initiates a call, SIP signaling streams for call connection is transmitted over the default bearer through the PGW to the IMS Core.
 A dedicated bearer for IMS(QCI1) voice media streams is set up during call connection.
 Voice media streams of the calling and called parties are transmitted over the dedicated bearer.
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 5
VoLTE Bearing
Data Bearing
UE setup default bearing
QCI 9 for data service
Voice Bearing(QCI1&5)
Voice call Bearing(QCI1&5)
Dedicated Bearer(GBR)QCI=2
Video call Bearing(QCI1&2&5)
UE not
support
VoLTE
QCI9
UE Support VoLTE
No VoLTE session
QCI5+QCI9
VoLTE voice
session
QCI1 + QCI5 +
QCI9
VoLTE video session
QCI1
+QCI2+QCI5+QCI9
QCI
1
2
5
9
VOLTE use SIP protocol to create, update and terminate a VOTE call:
Resource
Type
GBR
No-GBR
Non-GBR
Priority
Packet
Delay
Budget
Packet Error
Loss Rate
2
100 ms
10-2
4
150 ms
10-3
1
9
100 ms
300ms
10-6
10-6
Example Services
Conversational Voice
Conversational Video
(Live Streaming)
IMS Signalling
Data
 IMS need to be deployed in LTE core network and 2/3G core network to be upgraded for SRVCC.
 The UE need registration in IMS APN for VOLTE service
VoLTE voice Code：
 The voice code is negotiated between UE and IMS(independent with eNodeB), and carrier with QCI1
AMR-NB：12.2K、10.2K、7.95K、7.4K、6.7K、5.9K、5.15K、4.75K
AMR-WB： 23.85K、23.05K、19.85K、18.25K、15.85K、14.25K、12.65K、8.85K、6.6K
bearing. QCI1 is transparent to the eNodeB
 The VOLTE session negotiation(Signaling) is carrying with QCI5 which is control plane of LTE network. It is
transparent to the eNodeB.
HUAWEI TECHNOLOGIES CO., LTD.
Silent Period one silent frame per 160ms
Active period one voice frame per 20ms or 40ms
Huawei proprietary. No spread without permission.
Page 6
Contents
01
VoLTE Introduction
02
VoLTE Basic Feature Verification

VoLTE with intra-frequency HO

SRVCC to Utran
03
HUAWEI TECHNOLOGIES CO., LTD.
VoLTE Advanced Feature Verification

VoLTE with inter-frequency HO

ROHC

TTI Bundling

DRX

UL RLC Segmentation
Huawei proprietary. No spread without permission.
Page 7
Enable VoLTE Basic Function
The system default setting has already open the
VoIP basic function. It generally only need to check
the configuration of the following parameters :
1.
Check the RLC PDCP parameter group ID of
QCI=1/2/5
2.
Check the QCI=1/2/5 RlcMode transmission
mode
LST RLCPDCPPARAGROUP check the QCI=5
bearing mode to AM mode, RLC mode to UM
mode carrying QCI=1/2; if a configuration error,
use the MOD RLCPDCPPARAGROUP command
to modify
3.
Check the eNodeB VoIP support switch
LST ENODEBALGOSWITCH to check if VoIP
support switch is open; otherwise, use the
MOD ENODEBALGOSWITCH command to open
the EtranVoipSupportSwith switch
HUAWEI TECHNOLOGIES CO., LTD.
Basic function
VoLTE with IntraFreq HO
SRVCC to Utran
Query QCI RLC PDCP parameter group ID:LST STANDARDQCI
Query QCI RlcMode mode: LST RLCPDCPPARAGROUP
Establishes the VoIP QCI=5 load bearing RLC mode is the AM mode, the QCI=1 load bearing RLC
mode is the UM mode:
MOD STANDARDQCI: Qci=QCI5, RlcPdcpParaGroupId=4;
MOD STANDARDQCI: Qci=QCI1, RlcPdcpParaGroupId=0;
MOD RLCPDCPPARAGROUP: RlcPdcpParaGroupId=4, RlcMode=RlcMode_AM;
MOD RLCPDCPPARAGROUP: RlcPdcpParaGroupId=0, RlcMode=RlcMode_UM;
Parameter name
Parameter ID
Suggestion
Keep the default configuration. Different QCI
corresponding to different RLC mode, according to the
RLC mode
QCI version has adaptive configuration of transmission
（RLC-UM or RLC-AM RlcMode
mode。
mode）
QCI1： RlcMode_UM(UM mode)
QCI2： RlcMode_UM(UM mode)
QCI5： RlcMode_AM(AM mode)
Keep the default configuration (support). If a eNodeB
EUTRAN supports the
not to support the VoIP service because of the
EutranVoipSupport
VoIP capability of the
transmission and other reasons , it is suggested that the
Switch
switch
operators after confirmation is set to OFF, otherwise the
configuration for the ON.
Huawei proprietary. No spread without permission.
Page 8
VoLTE Intra-frequency handover policy
X2 inerface handover process
S1
S1
MME
X2
6.Handover
confirm
2.Handover request
1.Ueuse MR
report RSRP
measurement
3.Handover request ACK
4.RRC Reconfiguration
service interruption duration3050ms
5.RRC
Reconfiguration
CMP
VoLTE with IntraFreq HO
Basic function
SRVCC to Utran
S1 inerface handover
process
8.Handover
confirm
2.Handover require
3.Handover
request
1.Ue use MR
report RSRP
measurement
5.Handover
command
4.Handover
request ACK
6.RRC Reconfiguration
service interruption duration50-80ms
7.RRC
Reconfiguration
CMP
• LTE X2 handover duration30~50ms， S1 handover duration50~80ms （GSM handover duration120ms-140ms），x2 handover reduce impact of MOS；
• intra-frequency handover hysteresis 2dB（trigger handover if neighboring cells higher than serving cell ），probability ping-pang handover，reduce
MOS value，suggestion：


The erratic fluctuation of radio environment （e.g：crossroads），increased intra-frequnecy handover hysteresis according to radio
environment ,reduce ping-pang handover
one-way moving of high speed railway ， intra-frequency handover policy would not lead to ping-pang handover, suggested use existing
parameters
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 9
VoLTE Intra-freq HO Verification
Basic function
VoLTE with IntraFreq HO
SRVCC to Utran
Scenario 1: UE1 & UE2 both VoLTE, keep the VoLTE call during intra-freq HO
VoLTE subscriber MS1 (MSISDN: 005521982137868) called VoLTE subscriber MS2
(MSISDN: 005521982137869)
At 11:22:50.080 MS1 started the call, and dedicated bearer QCI1 setup at 11:22:54.
the call connected at 11:22:54 and terminated at 11:46:06.
HUAWEI TECHNOLOGIES CO., LTD.
During the call, MS2 finished the intra-freq HO from serving cell to neighbor cell
PCI155 at 11:25:05. the handover succeeded.
the RTP sequence numbers were continuous during the handover, that’s, in scenario
of UE1 & UE2 both VoLTE, VoLTE call will keep continuous during intra-freq HO.
Huawei proprietary. No spread without permission.
Page 10
VoLTE Intra-freq HO Verification
Basic function
VoLTE with IntraFreq HO
SRVCC to Utran
Scenario 2: UE1 VoLTE, UE2 fallback 3G with intra-freq LTE HO
VoLTE subscriber MS2 (Huawei MATE7, MSISDN: 005521982137869) called CSFB
subscriber MS1 (Samsung Galaxy S4, MSISDN: 982135200).
MS1 (Samsung Galaxy S4) sent Extend Service Request message to eNodeB to start
CSFB at 15:55:47.631. The connected at 15:55:55, and terminated at 15:57:56.
HUAWEI TECHNOLOGIES CO., LTD.
During the call, MS2 finished the intra-freq HO from serving cell to neighbor cell
PCI315 at 15:56:52. the handover succeeded.
the RTP sequence numbers were continuous during the handover, that’s, in scenario of
UE1 VoLTE, UE2 fallback 3G , VoLTE call will keep continuous during intra-freq HO.
Huawei proprietary. No spread without permission.
Page 11
SRVCC to Utran
Basic function
VoLTE with IntraFreq HO
SRVCC to Utran
Open coverage-based eSRVCC need to adjust existing parameters.
Analysis for A2：
LTE RSRP
3G RSCP
high
high
Adjust parameter，active
3G measurement
A2
●
A2_blind
low
Time point①
LTE RSRP below A2，Ue report
A2 event -> eNB deliver B1
measurement--》UE measure
3G signal。
• On eSRVCC process, if UE not support
inter-RAT measurement, eNB pending
delivers the A4 measurement
configuration, will wait until time point
③ launch to 3G redirection
B1_UTRAN
●
low
●
Time
①
②
③
UE MR indicate 3G level above
B1_UTRAN，report B1 event--》
eNB launch to 3G eSRVCC
handover
HUAWEI TECHNOLOGIES CO., LTD.
user move to edge coverage of LTE
Time point ③
Time point ②
• eSRVCC need to launch neighboring
cell for 3G,handover to 3G
• When voice and data
concurrency ,support by terminal and
network(MME/RNC/IMS)，use
eSRVCC PS+CS handover to 3G
3G signal not coincidence requirement of
B1 or UE not support inter-frequency
measure，LTE RSRP below A2_blind，
trigger A2 blind event--》eNB lanuch to 3G
blind redrirection， voice interrupt。
Huawei proprietary. No spread without permission.
Page 12
SRVCC to Utran
VoLTE with IntraFreq HO
Basic function
SRVCC to Utran
To activate SRVCC to Utran, we need to configure the parameters as below.
parameter
UtranSrvccSwitch
UtranVoipCapSwitch
GeranVoipCapSwitch
QciPriorityForHo
InterRatPolicyCfgGroupId
Technology
LTE
LTE
LTE
LTE
LTE
UtranHoCfg
LTE
MOD INTERRATPOLICYCFGGROUP
CsPsHOInd
INTERRATHOA1A2HYST
INTERRATHOA1A2TIMETOTRIG
INTERRATHOA1THDRSRP
INTERRATHOA1THDRSRQ
INTERRATHOA2THDRSRP
INTERRATHOA2THDRSRQ
INTERRATHOUTRANB1THDECN0
INTERRATHOUTRANB1THDRSCP
INTERRATHOUTRANB1HYST
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
LTE
MOD UTRANEXTERNALCELL
MOD INTERRATHOCOMMGROUP
MOD INTERRATHOCOMMGROUP
MOD INTERRATHOCOMMGROUP
MOD INTERRATHOCOMMGROUP
MOD INTERRATHOCOMMGROUP
MOD INTERRATHOCOMMGROUP
ADD INTERRATHOUTRANGROUP
ADD INTERRATHOUTRANGROUP
ADD INTERRATHOUTRANGROUP
recommend value
1
0
0
QCI1: 1/QCI2: 3/QCI3: 2/QCI4: 4/QCI5: 9/QCI6: 5/QCI7: 6/QCI8: 7/QCI9: 8
QCI1: 0/QCI2: 2/QCI5: 1/QCI9: 3
GroupId0: PS_HO-0&SRVCC-1&REDIRECTION-0
GroupId1: PS_HO-0&SRVCC-1&REDIRECTION-1
GroupId2: PS_HO-0&SRVCC-0&REDIRECTION-1
GroupId3: PS_HO-0&SRVCC-0&REDIRECTION-1
BOOLEAN_FALSE
4（2db）
640ms
-109dbm
-20db
-113dBm
-24
-20
-109
4
INTERRATHOUTRANB1TIMETOTRIG
LTE
ADD INTERRATHOUTRANGROUP
320ms
HoSignalingOptSwitch
RsvdPara1
CmpSwitch=CMP_IU_IMS_PROC_AS_NOR
MAL_PS_SWITCH
LTE
UMTS
MOD ENODEBALGOSWITCH
SET URRCTRLSWITCH
AddA2MeasIfQciAdjSwitch-1
SYSHO_CSIN_PERMIT_SWITCH-1
UMTS
SET UCORRMALGOSWITCH
ON
HUAWEI TECHNOLOGIES CO., LTD.
MML
MOD ENODEBALGOSWITCH
MOD ENODEBALGOSWITCH
MOD ENODEBALGOSWITCH
MOD CELLSTANDARDQCI
MOD STANDARDQCI
Huawei proprietary. No spread without permission.
Page 13
SRVCC to Utran Verification
Basic function
VoLTE with IntraFreq HO
SRVCC to Utran
VoLTE call connected at 10:32:29.
Then eNodeB sent MobilityFromEUTRACommand message to UE at 10:33:19.661
to start the SRVCC handover.
At 10:33:19.307, UE reported the measurement result that serving 4G cell RSRP 122dBm, and 3G RSCP -106dBm.
UE replied HandoverToUtranComplete message to eNodeB at 10:33:19.837. SRVCC
handover succeeded.
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 14
Contents
01
VoLTE Introduction
02
VoLTE Basic Feature Verification

VoLTE with intra-frequency HO

SRVCC to Utran
03
HUAWEI TECHNOLOGIES CO., LTD.
VoLTE Advanced Feature Verification

VoLTE with inter-frequency HO

ROHC

TTI Bundling

DRX

UL RLC Segmentation
Huawei proprietary. No spread without permission.
Page 15
VoLTE with Inter-Freq HO policy
Inter-Freq HO
ROHC
TTI Bundling
DRX
RLC
Segmentation
VoLTE interference increased by more service provided. Multi-carrier scene need to balance traffic for each carrier, to ensure voice
quality, and to maximize resource usage.
1800 frequency
band



2600 frequency
band
2600 frequency
band
1800 frequency
band
1800 frequency
band
load-based handover
coverage-based handover
1800 frequency
band
UE move to edge coverage will trigger coverage-based inter-frequency handover, existing network setting accord with VoLTE need.
Open load-based inter-frequency function：when load of serving cell attained to threshold ，MLB algorithm will choose some
UEs to receive load-based inter-frequency measurement according to frequency of UE,APR and resource. When signal of interfrequency attained to threshold, handover to inter-frequency neighboring cell. It can balance load of carriers and increase usage.
Traffic-based handover fit for service hierarchical scene(1800 as coverage layer to bear high priority service,2600 as data layer to
bear Non GBR data service),used for 1800/2600 hierarchical and continuouscoverage scene.
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 16
VoLTE with Inter-Freq HO
Inter-Freq HO
ROHC
TTI Bundling
DRX
RLC
Segmentation
Scenario 1: Inter-frequency Handover from 1549 to 3100
volte call started at 17:35:50, and connected at 17:36:00. This call lasted about 20 min,
and terminated at 17:54:14.
During the volte call, the inter-frequency handover occurred at 17:44:51,
handover succeeded from 1549 to 3100.
During the volte call, UE reported the measurement report. It showed that the serving
cell RSRP result was 28, and there was a neighbor cell with PCI 441, RSRP result 45.
the RTP sequence numbers were continuous during the inter-frequency handover. The
VoLTE call is continuous during the S1-based inter-freq HO.
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 17
VoLTE with Inter-Freq HO
Inter-Freq HO
ROHC
TTI Bundling
DRX
RLC
Segmentation
Scenario 1: Inter-frequency Handover from 3100 to 1549
volte call started at 15:54:40, and connected at 15:54:57. This call lasted about 4 min,
and terminated at 15:58:38.
During the volte call, the inter-frequency handover occurred at 15:58:36,
handover succeeded from 3100 to 1549.
During the volte call, UE reported the measurement report. It showed that the serving
cell RSRP result was 26, and there was a neighbor cell with PCI 52, RSRP result 46.
the RTP sequence numbers were continuous during the inter-frequency handover. The
VoLTE call is continuous during the S1-based inter-freq HO.
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 18
RoHC-Enhance coverage & capacity
IP Header
60 Bytes
TTI Bundling
AMR frame
33 Bytes
3. Uplink, eNB
decompress and
restore IP header
1 ~ 6Bytes
2.Uplink, after IP header
compression, sended by
UE on air interface
RLC
Segmentation
VoIP User
IP Header
60 Bytes
1. raw data
RoHC key point：
• RoHC need support by eNB & UE, eNB negotiate with UE, if
negotiation fails, not use compressed mode
• RoHC only used for data block header compression and decompress
on user plane (QCI=1),
• VOIP DRB setup， RoHC parameter will be negotiated by eNB and UE;
inter-eNB handover，ROHC need negotiate again；
intra-eNB handover，ROHC need not negotiate again .
DRX
downlink, UE
decompress and restore
IP header
AMR frame
33 Bytes
RTP Header +
12 Bytes
HUAWEI TECHNOLOGIES CO., LTD.
ROHC
AMR-NB12.2K raw data block 93 bytes
AMR-WB23.85k raw data block 123 bytes
downlink, IP header
compression, sended by
eNB on air interface
eNB
CN
Inter-Freq HO
UDP Header
8 Bytes
AMR frame
33 Bytes
+
IPv6 Header
40 Bytes
FDD: RoHC can be deployment in
the existing network
TDD: Not Suggesting Deployment
RoHC gain：
• increase capacity: AMR-NB12.2K speech data compression rate about
58%((60-6)/93), AMR-WB23.85K speech data compression rate about
44%((60-6)/123), decreased used RB, increase system capacity.
• Enhance coverage: RoHC reduces edge rate of VoIP, reduces the power
requirement of UE, enhances the edge coverage area (increase 2dB)
Huawei proprietary. No spread without permission.
Page 19
RoHC-Enhance coverage & capacity
1. Check License
2. Activate header compression
feature: open the ROHC switch,
set the ROHC top model and
compression protocol type
Parameter name
Inter-Freq HO
feature ID
LOFD-001017
RObust Header Compression (ROHC)
DRX
RLC
Segmentation
License Description
Header
compression
Switch on ROHC, set ROHC highest mode, configure types of compression protocol :
MOD PDCPROHCPARA: RohcSwitch=ON, HighestMode=O_MODE, Profiles=Profile0x00011&Profile0x0002-1&Profile0x0003-1&Profile0x0004-1;
If deactivation of the ROHC feature, close the ROHC switch::
MOD PDCPROHCPARA: RohcSwitch=OFF;
ROHC switch
PdcpRohcPara.RohcSwitch
ROHC highest mode
PdcpRohcPara.HighestMode
HUAWEI TECHNOLOGIES CO., LTD.
TTI Bundling
Feature name
Parameter ID
Compression protocol type
ROHC
PdcpRohcPara.Profiles
Suggestion
When eNodeB cell RB utilization rate is high and the VoIP service
proportion is high, suggest to open ROHC.
According to the radio link quality to determine:
When radio link quality is GOOD, choose "U_MODE (one-way mode)“
When radio link quality is FAIR, choose "O_MODE (model)“
When radio link quality is BAD, choose "R_MODE (safe mode)"
This parameter is bit-map type, if one bit checked, it means eNodeB
support that corresponding compression profile.
Huawei proprietary. No spread without permission.
Page 20
RoHC-Enhance coverage & capacity
Huawei Mate7 can support ROHC. The UE capability information list relative information.
Volte call connected at 11:23:30.661. During the volte call, MS1 moved from PCI 54 to
PCI 141. It reported the measurement result at 11:25:15, and received the RRC
connection reconfiguration message.
HUAWEI TECHNOLOGIES CO., LTD.
Inter-Freq HO
ROHC
TTI Bundling
DRX
RLC
Segmentation
In the RRC connection reconfiguration message ,the mobility control information: target cell PCI 141. And
in the radio resource configure dedicated IE, we found that the RoHC feature was activated.
Check the KPIs after 1 hour test, we found that during the RoHC activated, the header compression radio
was almost below 20%, the packet compression ratio was below 60%, and uplink decompression failure
ratio usually was 0%.
Huawei proprietary. No spread without permission.
Page 21
TTI B-Enhance edge coverage
Inter-Freq HO
ROHC
TTI Bundling
DRX
RLC
Segmentation
3GPP TS 36.213 stipulate TTI Bundling can use at most 3 RB ,
QPSK, highest rank of MCS is 10
Implementation scheme
unbundled
bind4 TTIs
4 continuous subframes transfer 1 TB,
no need to wait
ACK/NACK of eNB
After transmits the data
block in a bundle of TTIs, among which the
last TTI is numbered N. The eNodeB sends an
ACK or NACK
Based on the feedback, the UE
determines whether a retransmission is
required. If it is required, the UE
retransmits the data block in the (N +
13)th through (N + 16)th TTIs.
bundled
•LTE stipulate TTI Bundling
retransmission also Bundling
Uplink Gain
• TTI Bundling only used to enhance Uplink coverage at cell edge of voice
• When edge user on bad channel quality, UE transmit the same data block on 4
continuous uplink sub frames, uplink combining gain is 3 dB
3dB
FDD: TTIB can be deployment in the existing network
TDD: Not Suggesting Deployment
HUAWEI TECHNOLOGIES CO., LTD.
• TTI Bundling transmit the same TB on 4 continuous sub-frames (TTI_BUNDLE_SIZE =4),
no need to wait ACK/NACK of eNB, the same TB will be transmitted 4 times, used
different redundancy algorithm
• UE must support TTI Bundling: TTI Bundling can be active according to radio link status
adaptively by network, the criterion for entering TTI Bundling is UE has VoLTE
bearer(QCI1) only and UE has move to cell edge require improve uplink.
Huawei proprietary. No spread without permission.
Page 22
TTI B-Enhance edge coverage
1. Check License
2. Activate TTI Bundling feature
switch
Feature ID
LOFD-001048
Inter-Freq HO
ROHC
TTI Bundling
Feature name
DRX
RLC
Segmentation
License discretion
TTI bunding
TTI Bundling
Open TTI Bundling
MOD CELLALGOSWITCH: LocalCellId=0, UlSchSwitch=TtiBundlingSwitch-1;
Close TTI Bundling
MOD CELLALGOSWITCH: LocalCellId=0, UlSchSwitch=TtiBundlingSwitch-0;
Parameter name
Uplink scheduling switch
Parameter ID
CellAlgoSwitch.UlSchSwitch
HUAWEI TECHNOLOGIES CO., LTD.
Suggestion
This parameter has a sub switch “TTI Bundling switch” to
switch on/off the TTI Bundling function. In the conventional
operational scenario, it is suggested to uncheck the TTI
Bundling switch. When the UE channel has poor quality and
output power is limited, it is suggested to switch on TTI
Bundling.
Huawei proprietary. No spread without permission.
Page 23
TTI B-Enhance edge coverage
Inter-Freq HO
ROHC
TTI Bundling
DRX
RLC
Segmentation
After QCI1 setup, when edge user’s radio environment became worse, TTI Bundling feature worked. The relative information was contained in RRC connection reconfiguration message.
Queried the counter about TTI Bundling, we found that during the verification test, TTI Bundling enter number reached 112.
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 24
DRX-UE Power saving

Inter-Freq HO
ROHC
TTI Bundling
DRX
RLC
Segmentation
DRX(Discontinuous Reception)，UE open receiver into activated state at necessary time,to receive downlink data and signaling, other time
close receiver into sleeping state, stop to receive downlink data and signaling in order to save power .
Close DRX
Monitor PDCCH information
Receive voice frame(1ms)
Open DRX
Receive voice frame(1ms)
20ms
DRX suggested parameter settings(Only for Reference)
QCI1
Long
Short
DRX
On
DRX
Retrans
DRX
period
Whether to
Duration Inactivity Timer
period
is
enable
Timer(psf) Timer(psf) (psf)
（ms）
enabled
suggested
40
10
80
8 close
open
close
-
QCI2、3、4
QCI5、6、7、8
open
、9
Sleep state
20ms
close DRX function,for LTE voice service,receive a 1ms frame in
20ms,UE has been monitoring the PDCCH information during the
call.
QCI Type
Monitor PDCCH information
80
2
HUAWEI TECHNOLOGIES CO., LTD.
80
8 open
Short
DRX
period
（ms）
20
in the open DRX function, UE transmission cycle of speech frames based on open receiving
antenna, PDCCH information monitoring, and receives downlink data; in sleep state closed
DRX receiving antenna, stop receiving downlink data and signaling
DRX features of key points: (refer to the specific VoLTE solutions engineering instructions)
• QCI=1 configuration for a set of DRX parameters
• According to the QCI=5 recommendations and QCI9 configuration use a same set of
parameters
• Keep other DRX parameters of QCI, DRX parameters of the VoLTE service and data
service does not conflict
• DRX needs to support the terminal chip. Some terminal chip supporting DRX properties,
but the RF module does not support. It is closed during the period of DRX. Therefore
opened DRX feature, power saving effect is not obvious.
The feature of DRX gain:
• The use of DRX, in the data connection state without service maximum save power
66% ；speech to be tested
Huawei proprietary. No spread without permission.
Page 25
DRX-UE Power saving
Inter-Freq HO
During the DT in 10th June, when UE entered cell 137277-1 (cell
name: 18NLRJBT20A), DRX was triggered. At 11:37:03.920, eNodeB
sent RRC connection reconfiguration message to UE to configure
DRX. The details show that DRX for QCI1 worked.
HUAWEI TECHNOLOGIES CO., LTD.
ROHC
TTI Bundling
DRX
RLC
Segmentation
After the volte call terminated, eNodeB sent RRC connection
reconfiguration message to UE. The details showed that DRX for QCI9
worked.
Huawei proprietary. No spread without permission.
Page 26
Uplink RLC Segment
20ms Voice Frame (AMR 12.2k)
Inter-Freq HO
MAC
RLC
PDCP
RoHC
Voice Payload
2
1
1
6
33 Bytes
Far end User (6PRB MCS4)
ROHC
TTI Bundling
←X
TBS = 18 Bytes
PDCP
Segment
Edge User (3PRB MCS2)
10 Bytes
MAC
RLC
Seg Payload
2
1
10
TBS = 18 Bytes
cannot hold one voice frame
RoHC
Voice Payload
+
←√
10 Bytes
+
10 Bytes
+
10 Bytes
 Segment one PDCP packet into several small packets and transmitted in
different subframe, this will reduce TBS size per subframe which result in
low MCS and improve the UL coverage
 TDD-LTE system, for the SA2(3:1), there are 4 UL frame in 20ms. The 4 UL
frame could be used to transmitted the same voice frame and response
with one HARQ, this will gain around 4dB for UL coverage and save the
PDCCH resource in downlink .
More UL segments for voice frame may cause increase of packet delay in the air, this may cause the increase
of packet loss (Schedule issue) or voice quality Issue.
 RLC segments will increase the bits number of RLC head and MAC head or signaling cost.
 HARQ channel issue may influence the decode the PDCP layer packet and result in bad voice quality.
HUAWEI TECHNOLOGIES CO., LTD.
RLC
Segmentation
←√
TBS = 51 Bytes
Edge User (3PRB MCS2)
DRX
Huawei proprietary. No spread without permission.
parameter
script
UlVoipRlcMaxSegNum MOD CELLULSCHALGO
Page 27
Recommend value
20
Uplink RLC Segment
Inter-Freq HO
ROHC
TTI Bundling
DRX
RLC
Segmentation
For RLC Segmentation feature, there is no special indicator in the signaling. We can only check the uplink packet loss rate.
On the U2000, the uplink packet loss rate counters for QCI of 1 are queried and the uplink packet loss rate is calculated. The
uplink packet loss rate decreases significantly after the RLC segmentation feature is enabled.
Test of and comparison between the uplink packet loss rates before and after the RLC segmentation feature is enabled.
•The uplink packet loss rate is about 3.77% when the RLC segmentation feature is disabled. And it decreases to about 3.44% when
the RLC segmentation feature is enabled.
•Conclusion
RLC segmentation worked well during the volte call. It will reduce the uplink packet loss rate and improve subscribers’ experience.
HUAWEI TECHNOLOGIES CO., LTD.
Huawei proprietary. No spread without permission.
Page 28
HUAWEI TECHNOLOGIES CO., LTD.
Thank You!
Huawei proprietary. No spread without permission.
Page 29