eRAN13.1 CCSS Function Introduction
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Contents
1. Function Roadmap
2. Background
3. Function Overview
4. Network Impacts
5. Engineering Guidelines
6. Activation Verification
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Function Roadmap
LAOFD-070201 Flexible CA from Multiple Carriers
eRAN7.0

Basic: The eNodeB can
configure different cell
combinations for different CA
UEs at the same time.
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eRAN11.1


Basic: Remains unchanged.
Enhancement: CA Combination
Smart Selection (CCSS) allows
the eNodeB to select a proper
cell combination for each CA
UE.
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eRAN13.1


Basic: Remains unchanged.
Enhancement: CCSS allows the
eNodeB to select a proper cell
combination for each CA UE.
 Optimizations in eRAN13.1
1. The PCell is selected
based on the Uu interface
capability of a cell.
2. A load factor is added to
calculate the Uu interface
capability of a cell.
3. A PCC anchor hysteresis is
added.
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Background
As LTE network frequencies keep increasing, there are more cell combinations for CA.
Multi-band multi-carrier LTE network
F8
F7
F6
F5
Which cell combination is the
most suitable for this CA UE?
F4
F3
F2
F1
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Function Overview
CCSS is the enhancement of LAOFD-070201 Flexible CA from Multiple Carriers. CCSS aims to provide
the most suitable cell combination for CA UEs that newly access a multi-band multi-carrier network,
improving user experience.
F5
F4
F3
F2
F1
Neighboring cell D
CCSS helps select the following
cell combination for the UE in the
serving cell: CA=B(PCell)+C+D
Neighboring cell C
Neighboring cell B
Serving cell
Neighboring cell A
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Function Overview
Prerequisite 2:
OverlapInd or
SCellBlindCfgFlag has
been correctly
configured.
Principle – Working Flow
Prerequisite 1:
Adaptive CA has been
deployed.
UEs access a network,
perform incoming handovers,
or reestablish RRC
connections.
The eNodeB checks whether its
selected candidate cell
combination for CA matches
UE capabilities.
Yes
Is
measureme
nt required?
Evaluation of the cell combination set for CA
The eNodeB selects
candidate CCs based on
coverage.
The eNodeB filters out
inappropriate CCs based
on load.
Multiple eNodeBs
exchange load information.
The eNodeB sequences all
cell combinations for CA.
No
The eNodeB selects a cell
combination for CA based
on measurement results
and then configures it.
The eNodeB
configures the
cell combination
for CA.
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Function Overview
Principle – Evaluation of the Cell Combination Set for CA
Coverage
Method for determining a
candidate CC:
Neighboring cell configuration:
 SCellBlindCfgFlag=TRUE
 OverlapInd=Yes
If a CC meets either of the above
conditions, the CC is regarded as
a candidate CC.
Sequencing of cell
combinations for CA
Load
 Cell combinations for CA are
sequenced based on
coverage, PCC selection,
load, and total Uu interface
capabilities of cells.*
High-load cells are filtered out.
Heavy load definition for the
PCell and SCells:
Number of users ≥ Value of
InterFreqMlbUeNumThd +
Value of
InterFrqUeNumOffloadOffset
*Uu interface capabilities of a
cell = Number of available RBs x
Spectral efficiency/Number of
UEs to be scheduled (newly
added in eRAN13.1)
If the HoAdmitSwitch option is
selected, heavy load is defined
for the PCell based on MLB.
Number of users ≥ Value of
InterFreqMlbUeNumThd +
Value of MlbUeNumOffset
Or
PRB usage efficiency ≥ Value of
InterFreqMlbThd + Value of
LoadOff
PCC selection
1. PCC anchoring policy
2. PCC selection for the cell combination
for CA (new switch)
 If this option is selected:
The eNodeB selects the PCC
based on the following information:
1) PCC priority
2) Uu interface capability of a cell
(newly added in eRAN13.1)
3) Serving cell
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Function Overview
Principle – PCC Anchoring Policy
CCSS starts working when UEs initially access a network, perform incoming handovers, or reestablish
RRC connections.
Collaboration with the PCC anchor
PCC Anchor Enabled During Initial
Access
Enhanced PCC Anchor Enabled During
Initial Access, Incoming Handovers, or
RRC Connection Reestablishment
PCC Anchor Disabled
The serving cell does not need to
function as the candidate PCC only
when initial access is being
performed.
The serving cell does not need to function
as the candidate PCC after event A1 is
reported.
Only the serving cell can function as
the candidate PCC.
PCC anchoring hysteresis (newly added in eRAN13.1)
Assume that there are two cell combinations for CA. One cell combination (A)
requires that PCC anchoring be triggered, and the other one (B) does not. If the
difference between the Uu interface capabilities of the two cell combinations exceeds
the specified threshold, PCC anchoring is triggered for cell combination A.
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Function Overview
Principle – Evaluation and Selection of a Cell Combination for CA
UE: CA capability reporting
Band A
Band B
Band A
Band C
Band D
Band E
eNodeB: evaluation of a cell
combination set for CA
Cell A
Cell B
Cell A
Cell C
Selected cell combination for CA
Cell D
Matching
. . .
Cell X
Cell A
(PCC)
Cell Y
Cell Z
Cell E
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Cell C
Cell D
Network Impacts


Gains

CA is easy to deploy. Policies for the PCC and SCC do not need to be differentiated.

The smart selection algorithm takes precedence over parameter settings, increasing the overall CA UE traffic volume
on a complex network. The following are key gain factors: number of carriers, CA deployment policy in use, and
proportion of each CA UE type.

Network load is optimized based on the selected PCell and the calculated Uu interface capabilities of cells, improving
downlink experience of CA UEs.

The PCC anchor hysteresis is optimized to reduce the number of handovers.
Impacts
SCC configuration has a maximum delay of 3 seconds from the time the eNodeB initiates measurement
to the time the specified timer expires while the eNodeB receives no measurement report.
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Network Impacts

Hardware requirements
None

Software requirements
Adaptive CA has been deployed.
OverlapInd or SCellBlindCfgFlag has been correctly configured.
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Engineering Guidelines

Cell-level license

LAOFD-070201 Flexible CA from Multiple Carriers
Smart CA enhances Flexible CA from Multiple Carriers, and it requires no additional license.

Activation

Example (Scripts in red are new in eRAN13.1.)
MOD ENodeBAlgoSwitch: CaAlgoSwitch=FreqCfgSwitch-1&AdpCaSwitch-1&CaSmartSelection-1;
MOD ENodeBAlgoSwitch: CaAlgoExtSwitch=SmartCaPccSelSwitch-1;
MOD EUTRANINTERFREQNCELL: LocalCellId=1, eNodeBId=123, CellId=2, OverlapInd=YES;
MOD CAGROUPSCELLCFG: LocalCellId=1, SCelleNodeBId=123, SCellLocalCellId=2, SCellBlindCfgFlag=TRUE;
MOD CAMGTCFG: LocalCellId=0, MinDlAvgToBeScheduledUeNum=2, SmartCaPccAnchoringHyst=20;

Deactivation

Example
MOD ENodeBAlgoSwitch: CaAlgoSwitch=CaSmartSelection-0;
MOD ENodeBAlgoSwitch: CaAlgoExtSwitch=SmartCaPccSelSwitch-0;
MOD CAMGTCFG: LocalCellId=0, MinDlAvgToBeScheduledUeNum=0, SmartCaPccAnchoringHyst=0;
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Engineering Guidelines

Counters
 If one cell combination for CA is selected and the PCell is not the serving cell, counters listed in the
following table will change.
Counter ID
Counter Name
Counter Description
1526739790
L.HHO.InterFreq.PCCAnchor.PrepAttOut
Number of PCC-anchoring-based inter-frequency handover preparation
attempts
1526739791
L.HHO.InterFreq.PCCAnchor.ExecAttOut
Number of PCC-anchoring-based inter-frequency handover execution attempts
1526739792
L.HHO.InterFreq.PCCAnchor.ExecSuccOut
Number of successful PCC-anchoring-based inter-frequency handover
executions
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Thank you
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