Inter-EnB Inter-Frequency Load Balancing

(1)

Network Engineering Information

John Torregoza

MBB CS NE LTE Radio & Performance

Wroclaw, April 2013

Please make sure that you are using the latest version of this NEI found in this link:

https://sharenet-ims.in

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1

1 Introduction

Introduction

Motivation and Feature OverviewMotivation and Feature Overview

3

3 Interdependencies

Interdependencies

InterdependeInterdependencies with ncies with Other Features and Other Features and FunctionsFunctions

2

2 Technical Details

Technical Details

Functionality and Implementation, Message FlowsFunctionality and Implementation, Message Flows

6

6 Benefits and Gains

Benefits and Gains

Simulation, Lab Simulation, Lab and Field and Field FindingsFindings

4

4 Configuration Management

Configuration Management

Parameters and parameterisation scenariosParameters and parameterisation scenarios

7

7 Performance Aspects

Performance Aspects

Counters and KPIs, Feature Impact Analysis andCounters and KPIs, Feature Impact Analysis and Verification

Verification

5

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1

1 Introduction

Introduction

3

3 Interdependencies

Interdependencies

2

2 Technical Details

Technical Details

6

6 Benefits and Gains

Benefits and Gains

4

4 Configuration Management

Configuration Management

7

7 Performance Aspects

Performance Aspects

Verification

5

(5)



LTE1170 extends RL40 functionality in providing means to move incoming load

from a high-loaded cell to low-loaded cells which use different frequency than

the high-loaded serving cell

• UEs entering Connected state can be offloaded if target cell is measured to be at good radio

condition

• Offloading of UEs can be done towards intra-eNB or inter-eNB neighbor cells

• Target cell for offloading must have available capacity to serve offloaded UEs

• Load information is exchanged only between cells of the same eNB

• Load information from cells belonging to other eNBs are implicitly determined from HO

preparation decision in Load blind HO

• The feature balances load only between inter-frequency cells

• DL GBR, DL non-GBR and PDCCH load are evaluated to trigger offloading of UEs



LTE55 Inter-frequency handover must be activated in order for LTE1170 to

work

(6)

0 10 20 30 40 50 60 70 80 90 100 t0 t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 C e l l L o a d ( % ) Time Freq1 Freq2



LTE1170 is aimed to improve the utilization of resources between inter-frequency cells

• Does not aim to equally distribute between cells but to have cell load below a configurable threshold

With LTE1170 0 10 20 30 40 50 60 70 80 90 100 t0 t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 C e l l L o a d ( % ) Time Freq1 Freq2

Imbalanced utilization of resources in an eNB resulting in some UEs

not scheduled in Freq1

Resources are better utilized, resulting in more scheduled UEs

Target Load Thresh High Load

(7)



LTE1170 extends the RL40 feature LTE1387 (Intra-eNB Inter-Frequency Load Balancing)

with the following functionalities:

LTE1387 (RL40)

LTE1170 (RL50)

Intra-eNB/Inter-eNB

Intra-eNB Intra-eNB, Inter-eNB

Load Measurement,

Evaluation and Exchange

GBR, non-GBR load (exchange only between same eNB cells)

GBR, non-GBR, PDCCH load (exchange only between same eNB cells)

Target Cell Selection

Suitable candidate cells are sorted according to load information exchanged between cells of same eNB

Similar sorting mechanism to LTE1387 for cells of the same eNB is supported.

Load-blind HO for cells with unknown load is supported. Target cells of rejected iFLB-based HO are temporarily blacklisted.

Cells with unknown load information are added at the bottom of the sorted list.

Radio Admission Control

(RAC)

RAC forwards load measurements from scheduler to higher layers

RAC forwards load measurements from scheduler to higher layers.

In case of iFLB-based HO, RAC in target cell checks for target cell’s available capacity and rejects the LB-based HO if the target cell has no available resource.

(8)



Dependency table:

FD-LTE RLrelease eNB NetAct

Release/version RL50 LBTS5.0 OSS5.5

TD-LTE TD LTE release eNB (TD LTE) NetAct (TD LTE)

Release/version RL35TD TD-LBTS3.0 OSS5.5

HW&IOT HWrequirements MME SAEGW UE

Release/version

FSMr2 (Flexi FDD) FSMr3 (Flexi 1Flexi10

TD-LTE0 FDD,) No dependency No dependency 3GPP R8 UEs

Flexi Zone Micro FZM release eNB (FZM) NetAct (FZM)

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1 Introduction

Motivation and Feature Overview

3 Interdependencies

Interdependencies with Other Features and Functions

2 Technical Details

Functionality and Implementation, Message Flows

6 Benefits and Gains

Simulation, Lab and Field Findings

4 Configuration Management

Parameters and parameterisation scenarios

7 Performance Aspects

Counters and KPIs, Feature Impact Analysis and Verification

(10)

Feature Overview



LTE1170 can be split into the four building blocks as follows:



Load Supervision and Exchange

• Each cell measures DL GBR, DL non-GBR and PDCCH load periodically and exchanges load information between cells of the same eNB

• eNB decides whether the cell enters or exits active inter-frequency load balancing (iF-LB) state



Candidate UE Selection for measurement solicitation

• UEs entering Connected state are considered candidates for measurement solicitation hence avoiding further increase in existing cell load

• Already connected UEs are NOT offloaded to neighbor cells via load-based HOs

• UEs with QCI1 bearers established may be excluded from offloaded UEs depending on parameterization



Measurement Solicitation

• A4 measurements is activated if candidate UE’s serving cell is in active iF-LB state



iF-LB Execution

• Target cell list (TCL) is created based on r eceived RSRP, RSRQ and load measurements

• TCL is then sorted and highest ranked neighbor cell is chosen as target cell for offloading

• Load-blind HO is supported if load information is not available (ex. Inter-eNB target

Load Supervision and

Exchange

Candidate UE Selection for

Measurement Solicitation

iF-LB Execution

Continuous load Measurement and Exchange

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Load Supervision and Exchange _Solicitation Measurement Solicitation iF-LB Execution

Cell Load Measurement(1/8)



When LTE1170 is activated, eNB periodically (every 500ms) calculates DL GBR, DL non-GBR and PDCCH load for

each of its own cells



Relevant information as highlighted below are provided to L3 from L2 in order to calculate DL GBR, DL non-GBR and

PDCCH load

• DL GBR load (%) is defined as the ratio of the average DL GBR PRB utilization to t he average available PRBs for dynamic scheduling

DL GBR Load

Measurements

• DL non-GBR load (%) is defined as the ratio of the estimated resource utilization for non-GBR bearers to the average available PRBs for non-GBR dynamic scheduling

• Average available PRBs for non-GBR dynamic scheduling is the average available PRBs for dynamic scheduling without the PRBs allocated to GBR bearers

• Estimated resource utilization for non-GBR bearers is related to the average sum of scheduling weights for established non-GBR bearers

DL non-GBR

Load

Measurements

• PDCCH load (%) is defined as the averaged ratio of utilized CCEs to total number of available CCEs • Total number of available CCEs is calculated based on configurable maximum number of PDCCH

symbols(maxNrSymPdcch ), independent of number of currently used PDCCH symbols (when LTE616/LTE939 Usage-based PDCCH Adaptation is activated)

PDCCH Load

Measurements

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Cell Load Measurement (2/8)



DL non-GBR load is estimated based on the average sum of scheduling weights for non-GBR bearers

with data available for initial transmission

• A single non-GBR UE in an empty cell can occupy most of the available bandwidth, limited only by

bandwidth-limiting features (ex. LTE13 - Rate Capping)

• It can be easily seen that parameterization of

iFLBNomNumPrb

defines how high/low non-GBR load is

interpreted

DL non-GBR

Load

Measurements

Average sum of scheduling weights for non-GBR bearers

i

FLBNomNumPrb Average available PRBs for non-GBR bearers

This product defines the estimated

resource utilization for non-GBR bearers

for a given average sum of weights for

non-GBR bearers

Configurable parameter that

defines the estimated number

of PRBs allocated to a

non-GBR bearer with scheduling

weight equal to 1

Scheduling weight pertains to the

non-GBR QCI-specific configurable

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Inputparameters Value

Average available PRBs for dynamic scheduling 50 PRBs

Average GBR allocation 20 PRBs 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 N o n - G B R L o a d ( % ) 0.001 0.002 0.005 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10 iFLBNomNumPrb Values



iFLBNomNumPrb Behavior

If iFLBNomNumPrb=0.5 with given input parameters, non-GBR load is 100% if there are >60 UEs with scheduling weight =1.

In high values of iFLBNomNumPrb, non-GBR changes significantly with slight changes in average sum of non-GBR weights

 A higher hysteresis between target and high load thresholds is needed or change iFLBNomNumPrb to a lower value

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

The load measurements are subjected to a filter with coefficient α= 0.5



Filtering prevents the algorithm from being overly sensitive to load measurement variations

DL GBR Load Measurements DL non-GBR Load Measurements PDCCH Load Measurements

Sliding Window

Filter

α = 0.5

DL GBR Filtered Load Measurements DL non-GBR Filtered Load Measurements PDCCH Filtered Load Measurements

Filter Coefficient α = 0.5 means that the resulting filtered load measurement

value consists of past filtered load measurement (50%) and current load

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

Relative load (Rel.Load) for each load type

(DL GBR/DL non-GBR/PDCCH) is the

actual load (DL GBR/non-GBR/PDCCH)

compared to the corresponding target load

thresholds



Available capacity (AC) for each load type

(DL GBR/DL non-GBR/PDCCH) defines the

available resource of the cell relative to

corresponding target load thresholds



Filtered load measurements as calculated

from load information received from L2

Cell Load Measurement (5/8) DL GBR Filtered Load Measurements PDCCH Filtered Load Measurements DL non-GBR Filtered Load Measurements DL GBR Relative Load DL non-GBR Relative Load PDCCH Relative Load DL GBR Available Capacity DL non-GBR Available Capacity PDCCH Available Capacity

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Load Supervision and Exchange _Solicitation Measurement Solicitation iF-LB Execution Cell LoadX(t) LoadX(t) 30% Rel. LoadX(t) 50% AC_X(t) 50% Rel. LoadX(t) 100% 100% 80% 60% 40% 20% Target load for X @ 60%

50% of the cell’s configured target load threshold for load type X(DL GBR/DL non-GBR/PDCCH) is

Available capacity in relation to configured target load threshold DL GBR Filtered Load Measurements PDCCH Filtered Load Measurements DL non-GBR Filtered Load Measurements DL GBR Relative Load DL non-GBR Relative Load PDCCH Relative Load DL GBR Available Capacity DL non-GBR Available Capacity PDCCH Available Capacity

Suppose that actual cell load for load type X (DL GBR/DL

non-GBR/PDCCH) is as shown

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Load Supervision and Exchange _Solicitation Measurement Solicitation iF-LB Execution Cell LoadX(t) Load_X(t) 70% _LoadRel._X_(t) 100% Rel. LoadX(t) 100% 100% 80% 60% 40% 20% Target load X @ 60% Available capacity=0%, no UEs are offloaded to

this cell Cell Load Measurement(7/8)

100% of target load threshold for load type X ((DL GBR/DL

non-GBR/PDCCH) is utilized DL GBR Filtered Load Measurements PDCCH Filtered Load Measurements DL non-GBR Filtered Load Measurements DL GBR Relative Load DL non-GBR Relative Load PDCCH Relative Load DL GBR Available Capacity DL non-GBR Available Capacity PDCCH Available Capacity

Actual cell load for load type X (DL GBR/DL non-GBR /PDCCH) exceeds corresponding target load threshold

(18)



Available capacity is used to quantify

the load between different cells



This information is exchanged between

cells of the SAME eNB



These load measurements are

evaluated to trigger and to stop

inter-frequency load balancing



Available capacities are exchanged between

cells of the same eNB periodically every 1

second



Load information is exchanged independent of

load balancing status, i.e. ACs are exchanged

whether LB was triggered or not as long as

feature is enabled

Cell Load Measurement (8/8) DL GBR Filtered Load Measurements PDCCH Filtered Load Measurements DL non-GBR Filtered Load Measurements DL GBR Relative Load DL non-GBR Relative Load PDCCH Relative Load DL GBR Available Capacity DL non-GBR Available Capacity PDCCH Available Capacity

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LeaveActive iF-LB State

Y N

EnterActive iF-LB State

N

Y

Receive and process Load Measurements N Y UE Selection for Measurement Solicitation Cell in Active iF-LB state ANY Cell Load

>

HighLoadxxx

ALL Cell Load < TargetLoadxxx Filtered load measurements are evaluated periodically each time measurements arrive from L2 (period= 500ms) iFLBTargetLoadGBRDL/ iFLBTargetLoadNonGBRDL/ iFLBTargetLoadPDCCH iFLBHighLoadGBRDL/ iFLBHighLoadNonGBRDL / iFLBHighLoadPDCCH

Enter Active iF-LB State

GBROR_nGBR

loadOR_PDCCH

load exceed the related high-load thresholds

Leave Active iF-LB State

GBRAND_nGBR

loadAND_PDCCH

load are below related the target load thresholds

Difference between target load and high load thresholds defines the level of hysteresis to prevent ping-pong between iF-LB states

Cell Load Evaluation (1/1)

DL GBR Filtered Load Measurements _{DL non-GBR} Filtered Load Measurements PDCCH Filtered Load Measurements Y _N

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Candidate UE selection for Measurement Solicitation(1/3)



For each UE that enter Connected state,

iFLBBearCheckTimer is started.



When iFLBBearCheckTimer expires, eNB checks if the

following UE selection conditions are met:

1. Serving cell is in Active iF-LB state.

2.

UE has no QCI 1 bearer*

3. Frequencies configured in LNHOIF are supported by the UE

4. A4 measurements and reporting supported by UE

5. No ongoing inter-frequency or inter-RAT measurements for the UE

6. If carrier aggregation is supported, UE has no SCC configured (FDD RL50 only as CA not supported in RL35TD)

*Note: depending on settings for iFLBBearCheckTimer ,

condition 2 is not checked



If all conditions are met, A4 configuration is activated

(Measurement Solicitation)

• Otherwise, UE under consideration is removed f rom possible candidates for offloading (UE stays in cell)

Parameters Description

MeasParameters > bandListEUTRA

>> interfreqBandlist >> interfreqNeedGaps

 Defines list of frequencies supported by UE

 For each of the defined frequencies, the list of other frequencies it can measure and necessity of setting gaps.

Feature Group Indicator  Defines which features are supported by UE.

 BIT13Inter-frequency Handover

 BIT14 A4 and A5 measurements/reporting

…

UEs in Idle State

eNB sends Initial Context Setup Response for UE entering Connected state iFLBBearCheckTimer Check UE selection conditions

If conditions are met, activate A4 and start timer reportTimerIFLBA4

 If conditions are not met, UE is not candidate for LB offloading

 UE stays in cell

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

Exemplary scenarios for iFLBBearCheckTimer

…

UEs in Idle State

eNB sends Initial Context Setup Response for UE going from Idle to Connected

30s

Check UE selection conditions

• UE did not establish QCI1

• Other conditions

UE can be offloaded if it

measures a suitable cell and

satisfies other conditions

…

UEs in Idle State

30s

UE establishes QCI1 bearer

UE is not a candidate for

offloading, UE stays in the

highly-loaded cell

Suppose

iFLBBearCheckTimer

=30s,

•Since QCI1 bearer was established, UE stays in the cell

Suppose

iFLBBearCheckTimer

=30s,

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

Exemplary scenarios for iFLBBearCheckTimer

,

…

UEs in Idle State

30s

Check UE selection conditions • UE did not establish QCI1 • Other conditions

If conditions are met, activate A4 and start timer

reportTimerIFLBA4

…

UEs in Idle State

eNB sends Initial Context Setup Response for UE going from Idle to Connected 1s UE established QCI1 bearer 40s after switching to connected state

Suppose iFLBBearCheckTimer=31s(special value),

• QCI1 Bearer condition not checked

• Other conditions

UE can be offloaded if it

measures a suitable cell and

satisfies other conditions

UE can be offloaded if it

measures a suitable cell and

satisfies other conditions

Suppose iFLBBearCheckTimer=30s,

Candidate UE selection for Measurement Solicitation(3/3)

UE establishes QCI1 bearer

(23)

Measurement Solicitation (1/ 2)

RSRP time A4-threshold = -140dBm TTT=40ms A4 Report Sent RSRP Neighbor

Parameter Name

Set values

> Trigger Type event >> eventId eventA4 >>> a4-Threshold >>>> threshold-RSRP 0 (-140dBm) >> hysteresis 0 >> Time To Trigger 40ms > Trigger Quantity RSRP

> Report Quantity Both(RSRP & RSRQ) > MaxReportCells 8

> Report Interval 60min > Report Amount 1

Lowest possible A4 RSRP threshold allows measurement of most neighbor cells

A4 Configuration hard-coded and NOT

configurable!

Reported cells are post-processed to remove cells with insufficient RSRP and/or RSRQ.

(24)

…

UE in Idle Mode

iFLBBearCheckTimer _{reportTimerIFLBA4=3000ms}

 If conditions are not met, UE is not candidate for LB offloading UE stays in  If iF/interRAT event is reported before reportTimerIFLBA4 expires, stop timer and deactivate A4.

UE stays in the cell but

 If reportTimerIFLBA4 expires without any reports coming, UE not considered for LB offloading

Deactivate A4

UE stays in the the cell

If A4 report from UE arrives before timer expires, Target Cell List (TCL) from A4 reports are

post-processed for iF-LB execution

If conditions are met, activate A4 and start timer

reportTimerIFLBA4

Measurement Solicitation (2 / 2)



If all conditions for Candidate UE selection for

Measurement Solicitations are met,

reportTimerIFLBA4 timer is started and A4 is activated



If IF/IRAT mobility HO event is reported or no A4

reports arrive before reportTimerIFLBA4=3000ms

expires, A4 is deactivated and UE stays in cell

• UE with IF/IRAT event is excluded from UE candidates for offloading as they may handover via normal means



Some UEs are removed from UE Candidate for

offloading (green boxes)

A4 event activation

 Set s-measure in measConfig to 0

 Add measIDs in MeasConfig

 Measurement gap handling

 SendRRC Connection Reconfiguration

A4 event deactivation

 Set s-measure in measConfig to threshold1

 Remove measIDs in MeasConfig

 Measurement gap handling

 SendRRC Connection Reconfiguration

(25)

iF-LB Execution (1/8)

 Upon receiving A4 reports, the target cell list (TCL) is post-processed to choose the best target cell for offloading

Elimination of Unsuitable Cells

Reordering of Target Cell List

Choosing the target cell for HO

Handover preparation

Handover Execution and Completion

 Elimination of Unsuitable LTE Handover Target Cells due to LB-HO conditions • Target cells with insufficient signal level or quality based on measurement reported.

Measured RSRP/RSRQ belowthresholdRsrpIFLBFilter/thresholdRsrqIFLBFilter,respectively

• Target cells whose load is too high (load above target, CAC= min(AC_GBR, AC_nGBR, AC_PDCCH) =0)

 Target cells whose AC are unknown would not be removed from TCL • Target cells which are temporarily blacklisted due to highload conditions • Target cells are from another RAT

• If target cell is considered as HeNB (HeNB mobility is done via redirection)

 Elimination of Unsuitable LTE Handover Target Cells due to Handover Restrictions

 Elimination of Unsuitable LTE Handover Target Cells due to Handover Restrictions for VoIP Emergency calls

UE entering

Connected

(26)

TCL

Load Supervision and Exchange _Solicitation Measurement Solicitation iF-LB Execution  eNB sorts cells in Target Cell List according to descending Composite Available

Capacity (CAC) = min (AC_GBR, AC_nGBR, AC_PDCCH)

 For cells with unknown CAC, eNodeB places them after cells with CAC>0

I n c r e a s i n g P r i o r i t y Cell 1 CAC=X Cell 2 CAC=Y Cell 3 CAC=Z Cell a CAC=?

….

Cell b CAC=? Cell c CAC=?

Ordered according to

descending CAC

Same order as

measurement report

(27)

TCL

Load Supervision and Exchange _Solicitation Measurement Solicitation iF-LB Execution  Topmost cell of sort ed TCL is chosen as the target cell for handover

• If no other cells exists in TCL, UE stays in cell

I n c r e a s i n g P r i o r i t y Cell 1 CAC=X Cell 2 CAC=Y Cell 3 CAC=Z Cell a CAC=?

….

Cell b CAC=? Cell c CAC=?

Ordered according to

descending CAC

Same order as

measurement report

Target Cell

for offloading

(28)

TCL

I n c r e a s i n g P r i o r i t y Cell a CAC=? (unknown cell) Cell b CAC=? (unknown cell) Cell c CAC=? (known cell)

If the highest ranked cell is “unknown” (no existing LNREL)

• Highest ranked cell is not considered as target cell for offloading

• The next highest ranked cell is check if known

Target Cell

for offloading

(29)

TCL

I n c r e a s i n g P r i o r i t y Cell a CAC=? (unknown cell) Cell b CAC=? (unknown cell) Cell c CAC=? (unknown cell)

• If a neighbour cell is selected as target

for handover preparation after an A4

event, then the eNB shall create the

related RNL-available NR (if it does not

exist yet)



eNB shall create a RNL-available NR if a neighbour cell is selected

as target for handover preparation (if the RNL-available NR is not yet

existing)

RNL- available NR is created

if not yet existing

(30)

Source Cell Target Cell

Handover Request

Cause: Reduce Load in Serving Cell

Admission Control HO Preparation Failure

Cause: No Radio Resources Available in Target Cell

 Intra-eNB, X2 or S1-based handover is prepared towards the chosen target cell with Handover Cause =“Reduce load in serving cell

 Radio Admission Control works in the same way as described for “HO due to radio reasons” in RRM_SFS.5090

 In addition, radio admission control in target cell checks its CAC and decides whether to admit/reject the load based HO

 If target cell’s load (any of the load type) is above corresponding target (i.e. CAC=0), target cell rejects HO with failure cause “No Radio Resources Available in Target Cell ”

 Radio admission control condition applies for Intra-eNB, X2 or S1 LB-based HO

(31)

 If source cell receives a X2AP/S1AP: HANDOVER PREPARATION FAILURE or HO was internally aborted (for Intra-eNB HOs) with cause"Radio Network Layer Cause (No Radio Resources Available in Target Cell)" or "Transport Layer Cause(Transport Resource Unavailable)", source eNB assumes that the target cell has no available capacity

Admission Control HO Preparation Failure

Cause: No Radio Resources Available in Target Cell

Transport Resource Unavailable

Source eNB starts timer with configurable duration

“prohibitLBHOTimer ”

While the timer is running, the target cell where HO was rejected will be temporarily blacklisted for all LB-based HO requests from the source cell

Blacklist evaluation only for LB-based handovers p r o h i b i t L B H O T i m e r Handover Request

Handover Request

Target Cell X

Handover Request

(32)

Load Supervision and Exchange _Solicitation Measurement Solicitation iF-LB Execution  If the Target cell sends accepts HO request with partial admission of bearers

due to load reasons, the source eNB applies temporary blacklisting towards the Target cell

 The source eNB starts HO CANCEL procedure with cause “Partial Handover”

Admission Control

X2AP: HO Request Acknowledge/ S1AP: HO COMMAND

ERAB Not Admitted List

p r o h i b i t L B H O T i m e r Handover Request

Handover Request

Different Target Cell

Handover Request

Handover Cancel

Cause: Partial Handover

IE/Group Name

ERAB Not Admitted List > ERAB List Items >>ERAB Id >> Cause

(33)

 UE follows normal HO execution and completion procedures for Intra-eNB, X2 or S1-based HO. Source Cell Target Cell

Admission Control

Intra-eNB/X2AP: HO Request Acknowledge/ S1AP: HO COMMAND/

Handover Request

Continue Normal HO Procedures Continue Normal HO Procedures

(34)



Feature activation

•

• Feature activated via parameter

Feature activated via parameter actInterFreqLB

actInterFreqLB



Activation flag is common between RL40 LTE1387 and RL50 LTE1170



Upgrade from RL40 to RL50

Upgrade from RL40 to RL50 means that PDCCH load and load-blind HO is considered

means that PDCCH load and load-blind HO is considered with regards to impact

with regards to impact

on perfomance

•

• When activated, load measurements are taken and

When activated, load measurements are taken and exchange between cells of same eNB.

exchange between cells of same eNB.

•

• In addition,

In addition,

iFLBBearCheckTimer

is started for each UE that transitions from

is started for each UE that transitions from idle to connected.

idle to connected.



Feature deactivation

•

• Load measurements are not taken nor exchanged.

Load measurements are not taken nor exchanged.

iFLBBearCheckTimer

is not started

•

• If, iF-LB triggered actions are ongoing, continue actions but do

If, iF-LB triggered actions are ongoing, continue actions but do not trigger new actions

not trigger new actions



Running timers are not stopped but no new actions triggered when timers expire



Incoming A4 reports are ignored



(35)

1

1 Introduction

Introduction

3

3 Interdependencies

Interdependencies

2

2 Technical Details

Technical Details

6

6 Benefits and Gains

Benefits and Gains

4

4 Configuration Management

Configuration Management

7

7 Performance Aspects

Performance Aspects

Verification

5

(36)



LTE1170 Inter-eNB

LTE1170

Inter-eNB Inter-Frequency

Inter-Frequency Load

Load Balancing-

Balancing- Mandatory

Mandatory feature

feature



LTE55

LTE55 –

– Inter-frequency Handover (RL20/RL05TD)

Inter-frequency Handover (RL20/RL05TD)

•

• The feature provides means for a UE tThe feature provides means for a UE t o be handed over to neighbor cells of o be handed over to neighbor cells of different frequencydifferent frequency

•

• In order to off load UEs to neighbor cells using different frequency carrier, LTE55 must be activatedIn order to offload UEs to neighbor cells using different frequency carrier, LTE55 must be activated

•

• LTE1170 will not work if LTE55 is not LTE1170 will not work if LTE55 is not activatedactivated

LTE1170

Inter-e

Inter-eNBNBInter-

Inter-frequency Load frequency Load Balancing Balancing LTE55 LTE55 Inter-frequency Inter-frequency Handover Handover

(37)

LTE1170

Inter-e

Inter-eNBNBInter-

Inter-frequency Load

frequency Load

Balancing



LTE1170 Inter-eNB

LTE1170

Inter-eNB Inter-Frequency

Inter-Frequency Load

Load Balancing-

Balancing- Affected/A

Affected/Affecting

ffecting Features

Features



LTE1089 Downlink Carrier Aggregation

LTE1089 Downlink Carrier Aggregation –

– 20Mhz (RL50)

20Mhz (RL50)

•

• UEs with Secondary Component Carrier(SCC) configured will not UEs with Secondary Component Carrier(SCC) configured will not be considered as candidates for be considered as candidates for offloading to another layer offloading to another layer

•

• If a large percentage of If a large percentage of UEs have SCC configured for carrier aggregation, gain from load balancing is limitedUEs have SCC configured for carrier aggregation, gain from load balancing is limited



LTE1442 Open Access

LTE1442 Open Access Home eNodeB

Home eNodeB Mobility (

Mobility (RL50)

RL50)

•

• Home eNodeBsHome eNodeBs are not considered as are not considered as target for LB-based HOstarget for LB-based HOs

•

• IfIf actHeNBMobility actHeNBMobility = TRUE = TRUE and if the PCI is within the Pand if the PCI is within the PCI range (defined byCI range (defined by pciFirst pciFirst andand pciLast pciLast ) ) for for the the HeNBHeNB for for thethe EARFCN (

EARFCN ( freqEutrafreqEutra), the cell is removed from the ), the cell is removed from the target cell listtarget cell list

•

• Mobility towards Mobility towards HenBHenB is only viis only via redirecta redirect

LTE1089 LTE1089 Downlink Carrier Downlink Carrier Aggregation-20Mhz Aggregation-20Mhz LTE1442 LTE1442

Open Access Home

eNod

(38)



 LTE1170 Inter-eNBLTE1170 Inter-eNB Inter-FreqInter-Frequency Load Balancing-uency Load Balancing- AffectedAffected/Affecting features/Affecting features 

 LTE497 Smart Admission LTE497 Smart Admission Control (RL40/RL35TD)Control (RL40/RL35TD)

•

• LTE497 introduced a thresholdLTE497 introduced a threshold maxGbrTrafficLimit maxGbrTrafficLimit to determine whether to initiate congestion control or to determine whether to initiate congestion control or preemption of preemption of GBR bearersGBR bearers

•

• No cross-check between theNo cross-check between the maxGbrTrafficLimit maxGbrTrafficLimit and the LTE1170 GBR high load thresholdsand the LTE1170 GBR high load thresholds iFLBHighLoadGBRDLiFLBHighLoadGBRDL

•

• Relationship betweenRelationship between maxGbrTrafficLimit maxGbrTrafficLimit andand iFLBHighLoadGBRDLiFLBHighLoadGBRDLdeterdeterminesmines whetwhetherher congecongestion constion control or trol or load baload balancinlancing is theg is the first mechanism to take effect

first mechanism to take effect 

 LTE533+CRL0923 MRO (RL30/RL35TD)LTE533+CRL0923 MRO (RL30/RL35TD) •

• CRL0923 allows MRO algorithms to be applied as CRL0923 allows MRO algorithms to be applied as well to interwell to inter -frequency neighbor relations-frequency neighbor relations •

• Cell individual offsets adjusted by LTE533 would take into account HO events from LB-based HOsCell individual offsets adjusted by LTE533 would take into account HO events from LB-based HOs 

 LTE490 Subscriber profile based mobility LTE490 Subscriber profile based mobility (RL30/RL35TD)(RL30/RL35TD)

•

• Subscriber profiles are applied on the load balancing target frequency carriers as already supported for the normal Inter-Frequency HOSubscriber profiles are applied on the load balancing target frequency carriers as already supported for the normal Inter-Frequency HO targets

targets

•

• When LTE490 is activated, the SPID assigned to the UE is evaluated and the LB HO target for offloading is selected according to theWhen LTE490 is activated, the SPID assigned to the UE is evaluated and the LB HO target for offloading is selected according to the mobility profile defined by SPID (

mobility profile defined by SPID (MODPRMODPRandand MOPRMOPRMOCs)MOCs)

LTE1170

Inter-e

Inter-eNBNBInter-

Inter-frequency Load frequency Load Balancing Balancing LTE497 LTE497 Smart Admission Smart Admission Control Control LTE490 LTE490 Subscriber Profile Subscriber Profile based Mobility based Mobility LTE533 LTE533 Mobility Mobility Robustness Robustness

(39)

LTE1170 eNB Inter-frequency Load

Balancing



LTE1170 Inter-eNB Inter-Frequency Load Balancing- Supporting features



LTE1383-A Cell Specific neighbor relation / PCI hand ling (RL50/RL35TD)

• LNREL object, is created by eNB for a neighbor cell selected as target cell for handover preparation, assuming LNREL object for this neighbor cell does not exist and no other cells in t he TCL are known

LTE1383

Cell Specific Neighbor Relation/PCI Handling

(40)

1 Introduction

Motivation and Feature Overview

3 Interdependencies

Interdependencies with Other Features and Functions

2 Technical Details

Functionality and Implementation, Message Flows

6 Benefits and Gains

Simulation, Lab and Field Findings

4 Configuration Management

Parameters and parameterisation scenarios

7 Performance Aspects

Counters and KPIs, Feature Impact Analysis and Verification

(41)

• Definition of terms and rules for parameter classification:

- The ‘Basic Parameters’ category contains primary parameters which should be considered during cell deployment and must be adjusted to a particular scenario. These are:

- Network Element (NE) identifiers

- Planning parameters, e.g. neighbour definitions, frequency, scrambling codes, PCI, RA preambles - Parameters that are the outcome from dimensioning, i.e. basic parameters defining amount of resources - Basic parameters activating basic functionalities, e.g. power control, admission control, handovers

- Parameters defining operators’ strategy, e.g. traffic steering, thresholds for power control, handovers, cell reselections, b asic parameters defining feature behaviour

- The ‘Advanced Parameters’ category contains the parameters for network optimisation and fine tuning:

- Decent network performance should be achieved without tuning these parameters

- Universal defaults ensuring decent network performance need to be defined for all parameters of this category. If this is not possible for a given parameter it must be put to the ‘Basic Parameters’ category

- Parameters requiring detailed system knowledge and broad experience unless rules for the ‘Basic Parameters’ category are viol ated - All parameters (even without defaults) related to advanced and very complex features

Purpose:

 Categories of parameters have been defined to simplify network parameterization. Parameterization effort shall be focused mainly on parameters included in basic category.

 Categorization will be reflected in a ‘view’ definition in NetAct CM Editor (planned in RL60) i.e. parameters will be displayed according to the category: either in the ‘Basic parameters’ view or t he ‘Advanced parameters’ view.

(42)

actInterFreqLB

Activation of inter frequency load balancing (iFLB)

Object: LNBTS Range: 0 (false), 1 (true) Default: 0 (false) Multiplicity: 1 Modification: Online Modifiable Category: Basic Link to PKDB Parameter Behavior:

 Feature is activated on eNB level.

• All cells in eNB are considered in LB procedures

• However, cell-level exclusion from LB procedures can be done via specific configuration of load thresholds

 When actInterFreqLB =“TRUE”, load measurements are taken and exchange bet ween cells of same eNB. In addition, iFLBBearCheckTimer is started for each UE that transitions from idle to connected.

 The parameter serves as a common activation switch for LTE1387 (Intra-eNB Inter-frequency LB) and LTE1170 (Inter-frequency LB)

Parameterization Rules:

1. actifHO must be enabled to activate actInterFreqLB

• Offloading to other frequencies is not possible without activating inter- frequency handovers

2. The object “Inter freq load bal load thresholds” must be created per cell belonging to an eNB for which actInterFreqLB is set to “TRUE”.

• This object contains mandatory parameters (high load and target load thresholds, QCI1 bearer check timer and nominal number of PRBs) which are needed for LB operations 3. At least one of thresholdRsrpIFLBFilter or thresholdRsrqIFLBFilter must be configured when

actInterFreqLB is “TRUE”

• In order to assure a level of signal power and quality in t arget cells where UEs are offloaded

(43)

thresholdRsrpIFLBFilter

_{Inter-Freq LB Threshold for RSRP Target Filter}

Object: LNHOIF Range: -140, -139, ..., -44dBm Step: step 1dBm Default:

-100dBm

Multiplicity: 1 Unit: dBm Modification: Online Modifiable Category: Basic Link to PKDB

Parameter Behavior:



The parameter thresholdRsrpIFLBFilter defines the minimum RSRP level at

which UE reported measurements (via A4 event) are filtered in order to

remove cells with insufficient signal power from the Target Cell List(TCL)

• Cells with measured RSRP below

thresholdRsrpIFLBFilter

are removed from TCL



High Value of thresholdRsrpIFLBFilter

• Low chance for UE to get offloaded as a suitable target cell needs to be measured with higher RSRP than configured thresholds

• Less UEs are offloaded, less risk of HO failures and HO pingpongs



Low Value of thresholdRsrpIFLBFilter

• High chance for UE to get offloaded as a suitable target cell needs to be measured with higher RSRP than configured thresholds

• More UEs are offloaded, increase in risk of HO f ailures and HO pingpongs



The parameter incorporates frequency layer prioritization in offloading UEs

as the parameter can be configured per neighbor carrier frequency under

LNHOIF object

(44)

thresholdRsrpIFLBFilter

Inter-Freq LB Threshold for RSRP Target Filter

Parameterization Rules:

1. Configured values for thresholdRsrpIFLBFilter is recommended to be

above threshold2InterFreq of target cell to prevent inter-frequency mobility

ping-pongs.

2. If actInterFreqLB is “TRUE”, at least one of the threshold parameters for

RSRP (thresholdRsrpIFLBFilter ) and RSRQ (thresholdRsrqIFLBFilter)

must be configured per LNHOIF object

(45)

threshold2InterFreq Serving Cell RSRP (F1) Target Cell RSRP (F2) thresholdRsrpIFLBFilter Serving cells enter Active LB state UE switches from idle to connected state UE is offloaded to target cell After a short delay

Inter-frequency measurements are triggered UE may be handed over back to previous serving

cells via normal inter-frequency HO

Scenario: thresholdRsrpIFLBFilter < threshold2InterFreq



Figures show the possible scenarios violations of rule#1 and rule#2 in parameterization of

thresholdRsrpIFLBFilter

•Scenario below shows a possible ping-pong scenario if thresholdRsrpIFLBFilter

<

threshold2InterFreq

(46)

thresholdRsrqIFLBFilter

Inter-Freq LB Threshold for RSRQ Target Filter

Object: LNHOIF Range: -19.5, -19, , ..., -3.5, -3 dB Step: step 0.5dB Default:

-10dB

Multiplicity: 1 Unit: dB

Modification: Online Modifiable Category: Basic

Link to PKDB

Parameter Behavior:



The parameter thresholdRsrqIFLBFilter defines the minimum RSRQ level

at which UE reported measurements (via A4 event) are filtered in o rder to

remove cells with insufficient signal quality from the Target Cell List(TCL)

• Cells with measured RSRQ below thresholdRsrqIFLBFilter are

removed from TCL



The parameter incorporates frequency layer prioritization in offloading

UEs as the parameter can be configured per neighbor carrier frequency

under LNHOIF object



High Value of thresholdRsrqIFLBFilter

• Low chance for UE to get offloaded as a suitable target cell needs to

be measured with higher RSRQ than conf igured thresholds

• Less UEs are offloaded



Low Value of thresholdRsrqIFLBFilter

• High chance for UE to get offloaded as a suitable target cell needs to

be measured with higher RSRQ than conf igured thresholds

• More UEs are offloaded, increase in risk of HO failures and HO

pingpongs

(47)

thresholdRsrqIFLBFilter

Inter-Freq LB Threshold for RSRQ Target Filter

Parameterization Rules:

1.If

actInterFreqLB

is “TRUE”, at least one of the threshold

parameters for RSRP

(thresholdRsrpIFLBFilter )

and RSRQ

(thresholdRsrqIFLBFilter)

must be configured per LNHOIF object

(48)

iFLBTargetLoadGBRDL

Inter-Freq Load Balancing GBR Target Load DL

Object: LNCEL Range: 0%..100% Step: 1% Default:

50%

Multiplicity: 1 Unit: % Modification: Online Modifiable Category: Advanced Link to PKDB

Parameter Behavior:



The parameter iFLBTargetLoadGBRDL defines the level of GBR load that triggers

the exit from iF-LB Active state of a cell, i.e. stop UE offloading to neighbor cells

• Exit from iF-LB Active state occurs if ALL GBR, non-GBR and PDCCH load are below their corresponding target thresholds

• Together with iFLBHighLoadGBRDL, iFLBTargetLoadGBRDL provides hysteresis between iF-LB state transitions in terms of GBR load



In addition, iFLBTargetLoadGBRDL serves as GBR load reference in the

calculation of a cell’s GBR available capacity



Setting the target load thresholds to 0% and high load thresholds to 100% allows a

cell to be excluded from LB procedures



Setting the target threshold to a value XX% and high load thresholds to 100%

allows a cell to accept offloaded UEs but does not allow to offload UEs to

neighbors



Thresholds can be set per load type (DL GBR/DL non-GBR/PDCCH) to

differentiate load levels per load type at which cell enters or exits active iF-LB

states

(49)

iFLBTargetLoadGBRDL

Inter-Freq Load Balancing GBR Target Load DL

50%

Parameter Behavior:



High Value of

iFLBTargetLoadGBRDL

• More offloaded UEs can can be accepted by the cell from neighbor cells

• Easier to exit from active iF-LB in terms of GBR load



Low Value of

iFLBTargetLoadGBRDL

• Low number of UEs can be offloaded to this cell due to CAC=0 level can

easily be reached

• Once cell enters active iF-LB state, it is difficult to exit active iF-LB state

Parameterization Rules:

1. Verify that

iFLBTargetLoadGBRDL

≤

iFLBHighLoadGBRDL

2. iFLBTargetLoadGBRDL

is mandatory when

actInterFreqLB

=“TRUE”

(50)

iFLBTargetLoadNonGBRDL

Inter-Freq Load Balancing non-GBR Target Load DL

75%

Parameter Behavior:



The parameters iFLBTargetLoadNonGBRDL defines the level of non-GBR

load that triggers the exit from iF-LB Active state of a cell, i.e. stop UE

offloading to neighbor cells

• Together with iFLBHighLoadNonGBRDL, iFLBTargetLoadNonGBRDL provides hysteresis between iF-LB state transitions in terms of non-GBR load



In addition, iFLBTargetLoadNonGBRDL serves as non-GBR load reference in

the calculation of a cell’s non-GBR available capacity



Setting the target load thresholds to 0% and high load thresholds to 100%

allows a cell to be excluded from LB procedures



Setting the target threshold to a value XX% and high load thresholds to 100%

allows a cell to accept offloaded UEs but does not allow to offload UEs to

neighbors



Thresholds can be set per load type (DL GBR/DL non-GBR/PDCCH) to

differentiate load levels per load type at which cell enters or exits active iF-LB

states

(51)

iFLBTargetLoadNonGBRDL

_{Inter-Freq Load Balancing non-GBR Target Load DL}

75%

Parameter Behavior:



High Value of

iFLBTargetLoadNonGBRDL

• More offloaded UEs can can be accepted by the cell from neighbor

cells

• Easier to exit from active iF-LB in terms of non-GBR load



Low Value of

iFLBTargetLoadNonGBRDL

• Low number of UEs can be offloaded due to CAC=0 can easily be

reached

• Once cell enters active iF-LB state, it is difficult to exit active iF-LB state

Parameterization Rules:

1. Verify that

iFLBTargetLoadNonGBRDL

≤

iFLBHighLoadNonGBRDL

2. iFLBTargetLoadNonGBRDL

is mandatory when

actInterFreqLB

=“TRUE”

(52)

iFLBTargetLoadPdcch

Inter-Freq Load Balancing PDCCH Target Load DL

50%

Multiplicity: 1 Unit: % Modification: Online Modifiable Category Advanced Link to PKDB

Parameter Behavior:



The parameters iFLBTargetLoadPdcch defines the level of PDCCH load that

triggers the exit from iF-LB Active state of a cell, i.e. stop UE offloading to

neighbor cells

• Together with iFLBHighLoadPdcch, iFLBTargetLoadPdcch provides hysteresis between iF-LB state transitions in terms of PDCCH load



In addition, iFLBTargetLoadPdcch serves as PDCCH load reference in the

calculation of a cell’s PDCCH available capacity



Setting the target load thresholds to 0% and high load thresholds to 100%

allows a cell to be excluded from LB procedures



Setting the target threshold to a value XX% and high load thresholds to 100%

allows a cell to accept offloaded UEs but does not allow to offload UEs to

neighbors



Thresholds can be set per load type to differentiate load levels per load type at

which cell enters or exits active iF-LB states

(53)

LTE1170 - Inter-eNB Inter-Frequency Load Balancing

iFLBTargetLoadPdcch

Inter-Freq Load Balancing PDCCH Target Load DL

50%

Multiplicity: 1 Unit: % Modification: Online Modifiable Category Advanced Link to PKDB

Parameter Behavior:



High Value of iFLBTargetLoadPdcch

• More offloaded UEs can can be accepted by the cell from neighbor

cells

• Easier to exit from active iF-LB in terms of PDCCH load



Low Value of

iFLBTargetLoadPdcch

• Low number of UEs can be offloaded due to CAC=0 can easily be

reached

• Once cell enters active iF-LB state, it is difficult to exit active iF-LB state

Parameterization Rules:

1. Verify that

iFLBTargetLoadPdcch

≤

iFLBHighLoadPdcch

2. iFLBTargetLoadPdcch is mandatory when actInterFreqLB =“TRUE”

(54)

iFLBHighLoadGBRDL

Inter-Freq Load Balancing GBR High Load DL

60%

Multiplicity: 1 Unit: % Modification: Online Modifiable Category: Advanced Link to PKDB 

iFLBHighLoadGBRDL(1/2)

Parameter Behavior:



The parameters iFLBHighLoadGBRDL defines the level of GBR load that

triggers the entry to iF-LB Active state of a cell, i.e. start UE offloading to

neighbor cells

• Together with iFLBTargetLoadGBRDL, iFLBHighLoadGBRDL provides

hysteresis between iF-LB state transitions



Setting the target load thresholds to 0% and high load thresholds to 100%

allows a cell to be excluded from LB procedures



Setting the target threshold to a value XX% and high load thresholds to 100%

allows a cell to accept offloaded UEs but does not allow to zoffload UEs to

neighbors



Thresholds can be set per load type to differentiate load levels per load type at

which cell enters or exits active iF-LB states



High Value of iFLBHighLoadGBRDL

• More GBR cell traffic handled by cell before triggering LB, i.e. delays offloading of UEs to neighbor cells



Low Value of iFLBHighLoadGBRDL

(55)

iFLBHighLoadGBRDL

Inter-Freq Load Balancing GBR High Load DL

60%

Parameterization Rules:

1. iFLBTargetLoadGBRDL

≤

iFLBHighLoadGBRDL

2. iFLBHighLoadGBRDL

is mandatory when

actInterFreqLB

=“TRUE”

3. When LTE497 (Smart Admission Control) is activated

(

actEnhAcAndGbrServices

=true), care must be taken in setting

iFLBHighLoadGBRDL

• If maxGBRTrafficLimit < iFLBHighLoadGBRDL, admission control and

congestion handling reduce/limit the load before iF-LB can act

• Similarly

,

if maxGBRTrafficLimit

>

iFLBHighLoadGBRDL, offloading of

Ues occurs first before load becomes high enough to trigger smart

admission control actions

(56)

iFLBHighLoadNonGBRDL

Inter-Freq Load Balancing Non-GBR High Load DL

85%

Parameter Behavior:



The parameters iFLBHighLoadNonGBRDL defines the level of non-GBR load that

triggers the entry to iF-LB Active state of a cell, i.e. start UE offloading to neighbor

cells

• Together with iFLBTargetLoadNonGBRDL, iFLBHighLoadNonGBRDL

provides hysteresis between iF-LB state transitions



Setting the target load thresholds to 0% and high load thresholds to 100% allows a

cell to be excluded from LB procedures



Setting the target threshold to a value XX% and high load thresholds to 100%

allows a cell to accept offloaded UEs but does not allow to offload UEs to neighbors



Thresholds can be set per load type to differentiate load levels per load type at

which cell enters or exits active iF-LB states



High Value of iFLBHighLoadNonGBRDL

• More non-GBR cell load handled by cell before triggering LB, i.e. delays

offloading of UEs to neighbor cells



Low Value of iFLBHighLoadNonGBRDL

• UEs are offloaded to neighbor cells earlier, cell enters active iF-LB earlier

Parameterization Rules:

(57)

iFLBHighLoadPdcch

Inter-Freq Load Balancing PDCCH High Load DL

80%

Multiplicity: 1 Unit: % Modification: Online Modifiable Link to PKDB

Parameter Behavior:



The parameters iFLBHighLoadPdcch defines the level of PDCCH load that

triggers the entry to iF-LB Active state of a cell, i.e. start UE offloading to

neighbor cells

• Together with iFLBTargetLoadPdcch, iFLBHighLoadPdcch provides hysteresis between iF-LB state transitions



Setting the target load thresholds to 0% and high load thresholds to 100%

allows a cell to be excluded from LB procedures



Setting the target threshold to a value XX% and high load thresholds to 100%

allows a cell to accept offloaded UEs but does not allow to offload UEs to

neighbors



Thresholds can be set per load type to differentiate load levels per load type at

which cell enters or exits active iF-LB states



High Value of iFLBHighLoadPdcch

• More PDCCH cell load handled by cell before triggering LB, i.e. delays offloading of UEs to neighbor cells



Low Value of iFLBHighLoadPdcch

• UEs are offloaded to neighbor cells earlier, cell enters active iF-LB earlier 

iFLBHighLoadPdcch (1/2)

(58)

iFLBHighLoadPdcch

_{Inter-Freq Load Balancing PDCCH High Load DL}

80%

Multiplicity: 1 Unit: % Modification: Online Modifiable Link to PKDB

Parameterization Rules:

1. iFLBTargetLoadPdcch

≤

iFLBHighLoadPdcch

2. iFLBHighLoadPdcch is mandatory when actInterFreqLB =“TRUE”

(59)

GBR/nGBR/PDCCH Cell Load GBR/nGBR/PDCCH Target load = 0% GBR/nGBR/PDCCH High load = 100% GBR Load 0% Non-GBR Load 0% PDCCH Load 0%

Load for any load type will never be below target=0%, will

not exit active iF-LB state

GBR AC 0% Non-GBR AC 0% PDCCH AC 0%

AC is always 0%, cell will not accept any offloaded UEs from

neighbor cells GBR Load 100% PDCCH Load 100% nGBR Load 100%

Load for any load type will never exceed 100%, i.e. cell will never

enter active iF-LB state

Special Case 1: Cell Exclusion from Load Balancing

• Setting the target load thresholds to 0% and high load thresholds to 100% allows a cell to be excluded from LB

procedures

(60)

• Setting the target threshold to a value XX% and high load thresholds to 100% allows a cell to accept offloaded

UEs but does not allow to offload UEs to neighbors

GBR/nGBR/PDCCH Cell Load GBR/nGBR/PDCCH Target load = XX% GBR/nGBR/PDCCH High load = 100%

Up to a certain level of cell load defined by target cell load, cell may

be target for offloaded UEs

GBR Load 100% PDCCH Load 100% nGBR Load 100%

Special Case 2: Cell accepts offloaded UEs but never enter active iF-LB state

Load for any load type will never exceed 100%, i.e. cell will never enter

active iF-LB state

GBR Load A% nGBR Load B% PDCCH Load C%

(61)

• Thresholds can be set per load type to differentiate load levels per load type at which cell enters or exits active

iF-LB states

GBR/nGBR/PDCCH Cell Load GBR Target load = ZZ% GBR High load = XX% GBR Load A% nGBRAC 0%

Special Case 3: Load Type Differentiation

nGBR/PDCCH High load = 100% nGBR/PDCCH

Target load = YY%

nGBR Load

B% PDCCH

Load C%

Different threshold levels allows differentiation between load types

In this example, nGBR and PDCCH load never trigger cell’s entry to active iF-LB state; UEs will not be

offloaded to this cell as GBR load has exceeded target GBR load

(62)

• Setting the target threshold to 0% and high load thresholds to some value XX% makes the cell reject offloaded

UEs and allows the cell to be in always active iF-LB state



Not recommended

GBR/nGBR/PDCCH Cell Load GBR/nGBR/PDCCH Target load = 0% GBR/nGBR/PDCCH High load = XX% GBR Load A% GBR AC 0% nGBR AC 0% PDCCH AC 0%

AC is always 0%, cell will not accept any offloaded UEs from neighbor cells

nGBR Load B% PDCCH Load C%

GBR Load nGBR Load PDCCH Load GBR AC 0% nGBR AC 0% PDCCH AC 0%

Cell enters active iF-LB state

When cell enters active iF-LB state, cell will never exit due to load never going below target load.

Special Case 4: Cell always in Active iF-LB mode

(63)

iFLBNomNumPrb

_{Inter-Freq LB Nominal Number of PRBs}

Object: LNCEL Range: 1 (0.001), 2 (0.002), 5 (0.005), 10 (0.01), 20 (0.02), 50 (0.05), 100 (0.1), 200 (0.2), 500 (0.5), 1000 (1), 2000 (2), 5000 (5), 10000 (10) Default:

1000 (1)

Multiplicity: 1

Modification: Online Modifiable Category: Advanced Link to PKDB



iFLBNomNumPrb (1/2)

Parameter Behavior:



The parameter iFLBNomNumPrb defines the estimated load contributed to the

overall non-GBR cell load by a non-GBR bearer with scheduling weight=1

• Non-GBR load can not be measured in similar manner as GBR loada single UE with non-GBR bearer may completely use all PRBs if there are no other UEs in the cell • Multiplying the parameter with the average sum of bearer weights results in the

estimated non-GBR cell loaded for the cell



Higher Value: faster rate of change in measured non-GBR load with respect to

change in sum of bearer scheduling weights

• Faster to trigger entry and exit to active iF-LB

• iF-LB state changes can be become more frequentdifference between HighLoad and TargetLoad must be higher to have decent hysteresis between entering and leaving active iF-LB state

• Faster to reach non-GBR target loadless offloaded UEs accepted



Lower Value: slower rate of change in measured non-GBR load with respect to

change in sum of bearer scheduling weights

• Slower to trigger entry and exit t o active iF-LB