ilide.info-load-balancing-pr_5ad3040f899f862c4622631185082de8.pdf

loadbalance 4G parameter nokia

1. RA41220-V-22R3 © Nokia 2021
Load balancing features

2. 2 RA41220-V-22R3 © Nokia 2021
•Load Balancing Features Overview
Idle Mode Mobility Load Balancing
Intra-Frequency
Inter-Frequency
Intra-LTE Inter-RAT
LTE1387 – Intra-eNB Inter-Frequency Load Balancing (RL40)
LTE1170 – Inter-eNB Inter-frequency Load Balancing (RL50)
Connected Mode Load Balancing Features
LTE1531 – Inter-frequency Load Balancing Extensions (RL60/RL45TD)
LTE487 – Idle Mode Load Balancing (RL50/RL35TD/RL50FZ)
CRL0632 – Basic Idle mode Load Balancing (RL40)
LTE1677 – Idle Mode Load Balancing Extensions (RL60/RL45TD)
LTE1140 – Intra-Frequency Load
Balancing (RL70/RL55TD)
LTE1841 – Inter Frequency Load Equalization (RL70/RL55TD)
LTE2050 – Load Triggered Idle Mode Load Balancing (RL70/RL55TD)
Idle Mode Load Balancing Features
LTE2051 – Measurement Based Idle Mode Load Balancing (L15A)
LTE2166 – Support of dedicated idle mode mobility priorities– (L16)
LTE2106 - CA-aware IMMLB (L16A)
LTE4945 - TM9 aware Idle Mode Load Balancing (L19B)
LTE5501 - EN-DC aware idle mode load balancing (L20A)
LTE5104 - 5G Option 2 Aware Idle Mode Load Balancing (L20B)
LTE1357 LTE-UTRAN load
balancing (FL15A)

3. 3 RA41220-V-22R3 © Nokia 2021
Module Contents
•Idle mode load balancing
•Connected mode load balancing

4. 4 RA41220-V-22R3 © Nokia 2021
A percentage of UEs switching from connected to idle state are provided dedicated cell reselection priorities for different
frequency layers and RATs via RRC Release message
LTE 487/LTE1677 Idle Mode Mobility Load Balancing
Freq1
Freq2
Broadcasted Cell Reselection
Priorities
Freq 1 High
Freq 2 Low
Dedicated Cell Reselection
Priorities
Freq 1 Low
Freq 2 High
Percentage of UEs33%
1. UEs connected to Freq1
3. UEs are released by the
cell
2. Selected UEs are sent
IMMLB priorities
4. UEs uses the IMMLB
priorities for reselection
RRC Connection
Idle: Cell Reselection
(the selected UE)

5. 5 RA41220-V-22R3 © Nokia 2021
Key functionality
LTE487 Idle Mode Load Balancing
•A UE is selected for IMMLB if the condition below is true:
•Where:
•NrOfRrcReleaseForIMMC: Internal counter RRC connection release with IMMLB information
•NrOfRrcRelease: Total number of RRC connection release
•idleLBPercentageOfUes: Percentage of UE’s set via parameter for IMMLB offloading. This is based on object level (LNCEL, MOPR,
MODPR)
•Additionally it is also checked the UE capabilities support at least one of the configured target
Interfrequency/RAT layers
•eNB has at least one frequency valid for load balancing , taking into account UE Capabilities with supported bands and
configured frequencies in SIB related instances for intra-LTE and inter-RAT target frequencies or Mobility Profiles
•UE was not selected for any kind of redirection
Check assumes that UE to be
released is sent
idleModeMobilityControlInfo

6. 6 RA41220-V-22R3 © Nokia 2021
In case we have more than 2 layers and we need to
have more control on load balancing , WRR
algorithm can be used on top of lagacy one.

7. 7 RA41220-V-22R3 © Nokia 2021
LTE1677 Idle Mode Mobility Load Balancing/Extensions
- Weighted Round Robin (WRR)
IMMLB weights that are configured for each of n frequencies in Frequency List 1 are summed
∑w1(fx)…wn(fx) and then there is a randomized WRR probability calculated, e.g. when n=3)
Frequency layer
[ (f
x) ]
Weight configured
[ w
j(f
x) ]
Sum of weights
[ ∑w
1(f
x)…w
n(f
x) ]
WRR probability
[ pWRR
j(f
x) ]
f
1
w
1
(f
1
) 100
200
= 100/200 = 0.5
f
3 w
2(f
3) 50 = 50/200 = 0.25
f
4 w
3(f
4) 50 = 50/200 = 0.25
(STEP 1)
Frequency List
FREQ WEIGHT
f
1
100
f
3
50
f
4
50
0
0.5
0.5
0.75
0.75
1
p
1
WRR(f
1
) = 0.5 p
2
WRR(f
3
) = 0.25 p
3
WRR(f
4
) = 0.25
f
1 = [0;0.5] f
3 = (0.5;0.75]
f
4 = (0.75;1]
Generated value 0.76 means that f
4
will get priority 7 in IMMCI Example: Value 0.76 was randomly generated

8. 8 RA41220-V-22R3 © Nokia 2021
LTE2050 Load Triggered Idle Mode Load Balancing
Introduction of inter-RAT
capability
RL40 RL50 – LTE487
Load balancing across LTE
carriers
•Idle Mode Mobility Load Balancing (IMMLB) refers to the inclusion of Dedicated Priorities within the RRC
Connection Release message
•Load balancing is achieved by allowing:
•some UE’s use the Priorities broadcast within the SIB
•some UE’s use Dedicated Priorities included within their RRC Connection Release
•IMMLB has evolved with each software release
•RL70 introduces the capability to trigger IMMLB only when the serving load becomes high
•rather than always triggering the feature
Introduction of Absolute
Priority Weights
RL60 – LTE1677

9. 9 RA41220-V-22R3 © Nokia 2021
Proposed configuration
Technolo
gy
Abbreviated Name MO Class Paramet
er
Category
Parent
Structure
Full Name Data
Type
Range and step Default ValuePROPOSED Required
on
Creation
4G idleLBPercentageOfUesMRBTS/LNBTS/LNCEL Basic
parameter
s
  Percentage of UE for idle mode load balancing Number0...100, step 10 0 50 Mandator
y
4G t320 MRBTS/LNBTS/LNCEL Advanced
parameter
s
  Timer T320 Enumerati
on
5:5min;
10:10min;
20:20min;
30:30min;
60:60min;
120:120min;
180:180min
180 10 Mandator
y
4G actIdleLB MRBTS/LNBTS Basic
parameter
s
  Activation of idle mode load balancing (IdleLB) Boolean  0 1 Mandator
y
4G idleLBCellReSelPrioMRBTS/LNBTS/LNCEL Basic
parameter
s
  Serving cell carrier freq prio for idle mode load balancingNumber0...6.8, step 0.2  7 Optional
4G idleLBCelResWeight MRBTS/LNBTS/LNCEL Basic
parameter
s
  Cell reselection weight factor idle mode load balancingNumber1...100, step 1  50 Optional
4G eutCelResPrio MRBTS/LNBTS/LNCEL/
IRFIM
Basic
parameter
s
  EUTRA carrier frequency absolute priority Number0...7, step 1  7 Optional
4G idleLBEutCelResPrioMRBTS/LNBTS/LNCEL/
IRFIM
Basic
parameter
s
  EUTRAN carrier freq prio for idle mode load balancingNumber0...6.8, step 0.2  6 Optional
4G idleLBEutCelResWeightMRBTS/LNBTS/LNCEL/
IRFIM
Basic
parameter
s
  EUTRA carrier weight factor idle mode load balancingNumber1...100, step 1  50 Optional

10. 10 RA41220-V-22R3 © Nokia 2021
Module Contents
•Idle mode load balancing
•Connected mode load balancing

11. 11 RA41220-V-22R3 © Nokia 2021
Inter-frequency Load Balancing
LTE55 Inter-frequency handover must be activated in order for LTE1170 to work
DL
UL
DL
UL 2
1
0
0
M
H
z
8
5
0
M
H
z
LTE1170 (Inter-frequency Load Balancing) extends LTE1387 (Intra-eNodeB inter-frequency LB ) 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
•No load information sent over X2 interface
•The feature balances load only between inter-frequency cells
•DL GBR, DL non-GBR and PDCCH load are evaluated to trigger offloading of UEs

12. 12 RA41220-V-22R3 © Nokia 2021
Load Supervision and
Exchange
Candidate UE Selection for
Measurement Solicitation
Measurement Solicitation
iF-LB Execution
Continuous load
Measurement and
Exchange
Intra-eNB Inter-frequency Load balancing
Step 1
Step 2
Step 3
Step 4

13. 13 RA41220-V-22R3 © Nokia 2021
•Step 1 Load supervision and exchange
Inter-frequency Load Balancing
Cell Load Measurements
•Each measured DL Load (ML) is reflected as Relative Load (RL)
- Relative Load defines measured load in relation to configured Target Load Threshold (TL)
- Target Load Threshold is configured via parameters: LNCEL:LoadSettings:targetLoadGbrDl, targetLoadNonGbrDl,
targetLoadPdcch
- Relative load is a subcomponent in calculation of DL Available Capacity (AC)
Available Capacity = [100% - RL]
DL GBR Measured
Load
DL non-GBR
Measured Load
PDCCH Measured
Load
DL GBR Relative
Load
PDCCH Relative
Load
DL non-GBR
Relative Load
DL GBR Available
Capacity
PDCCH Available
Capacity
DL non-GBR
Available Capacity
0%
100%
Cell Load
X
[%]
50%
50%
AC
X
RL
X
50%
ML
X
X = GBR, nonGBR, PDCCH
25%
TL
X

14. 14 RA41220-V-22R3 © Nokia 2021
Inter-frequency Load Balancing
Step 1 Load Supervision and Exchange
Leave Active iF-LB
State
Y
N
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
TargetLoadGBRDL/
TargetLoadNonGBRDL/
TargetLoadPDCCH
iFLBHighLoadGBRDL/
iFLBHighLoadNonGBR
DL/
iFLBHighLoadPDCCH
DL GBR
Filtered Load
Measurements
DL non-GBR
Filtered Load
Measurements
PDCCH Filtered
Load
Measurements
Y N
Enter Active iF-LB
State Note : Filtered load measurements are evaluated
periodically each time measurements arrive from
L2 (period= 500ms).

15. 15 RA41220-V-22R3 © Nokia 2021
Inter-frequency Load Balancing
Step 4 iF-LB Execution
Upon receiving A4 reports, the target cell list (TCL) is processed to choose the best target cell for offloading
•eNodeB shall reorder Target Cell List according to
descending Composite Available Capacity (CAC)
•CAC= min (AC_GBR, AC_nGBR, AC_PDCCH)
•Topmost cell of re-ordered TCL is chosen as the target cell
for HO
•Intra-eNB X2, or S1 HO is prepared towards the chosen
target cell
•HO Cause “Reduce load in serving cell”
•Admission Control shall be applied as for “HO due to radio
reasons”
Elimination of Unsuitable Cells
Reordering of Target Cell List
Choosing the target cell for HO
Handover preparation
Handover Execution
•Target cell should have RSRP & RSRQ better than
•thresholdRsrpIFLBFilter
•thresholdRsrqIFLBFilter

16. 16 RA41220-V-22R3 © Nokia 2021
actInterFreqLB - activates Inter- frequency load balancing (iF-LB) feature
thresholdRsrpIFLBFilter - Threshold for Filtering Target Cells out of reported A4 event based on RSRP values due to IFLB
thresholdRsrqIFLBFilter - Threshold for Filtering Target Cells out of reported A4 event based on RSRQ values due to IFLB
TargetLoadGBRDL – Target Load for usage of GBR
TargetLoadNonGBRDL - Target Load for usage of nonGBR
TargetLoadPDCCH - Target Load for usage of PDCCH
iFLBHighLoadGBRDL - High Load for usage of GBR
iFLBHighLoadNonGBRDL - High Load for usage of nonGBR
iFLBHighLoadPDCCH - High Load for usage of PDCCH
iFLBBearCheckTimer - Inter-Freq Load Balancing QCI1 Bearer Check Timer
iFLBRetryTimer Inter Freq Load Bal Retry Timer
Inter-frequency Load Balancing
Parameters
Dependencies;
iFLBHighLoadGBRDL >= TargetLoadGBRDL
iFLBHighLoadNonGBRDL >= TargetLoadNonGBRDL
iFLBHighLoadPDCCH >= TargetLoadPDCCH

17. 17 RA41220-V-22R3 © Nokia 2021
Cell C
(Partner cell)
Cell B
(Neighbour cell)
•Goal of the feature: load equalization (LE) between source
cell and partner neighbor cells
-Partner cell – neighbour cell of the same or different eNB that uses
partner frequency layer and is AMLE allowed
(LNREL:amleAllowed = true)
•The same set of parameters from AMLEPR is used for all partner
cells of partner frequency layer
-Partner frequency layer – frequency layer that is configured in
partnership for serving cell
-Partnership is created when frequency layer is configured in any of
Active Mode Load Equalization Profile (AMLEPR):
LNCEL:AMLEPR
•Intra frequency partnership is not supported
•Configuration of partnership is always done per frequency layer
LTE1841 Inter frequency load equalization
Cell A
(Source cell)
overview
Load is being equalized between
Source cell and Partner cells only
Cell D
(Partner cell)

18. 18 RA41220-V-22R3 © Nokia 2021
When feature is activated (LNCEL:actAmle = true) its behaviour can be
reflected as 5 functional blocks
1)Load supervision and exchange:
•Measurements of CAC
S
and exchange with neighbours
2)Check of active AMLE state conditions
•AMLE state of source cell is determined
3)Candidate UE selection
•When Inter Frequency Load Balancing QCI1 Bearer Check Timer or Inter Frequency Load
Balancing Retry Timer is expired UE is checked if it can be Candidate for offloading
4)Measurement solicitation
•A4 measurements of partner neighbour frequencies are triggered
5)Load Equalization execution
•Target Cell List is post-processed, unsuitable cells are removed
•Inter frequency Handover preparation phase is started
LTE1841 Inter frequency load equalization
Check of active AMLE
state conditions
Candidate UE selection
Measurement
solicitation
Load Equalization
execution
Load supervision and
CAC exchange
AMLE feature
overview
Partner Cell
Source Cell

19. 19 RA41220-V-22R3 © Nokia 2021
LTE1841 Inter frequency load equalization
•Load types measured: GBR, PDCCH and
nonGBR
•From RL70 onwards user has impact on which type
of load is taken into account for CAC
DL
determination
•Parameter LNCEL:loadSettings:mlbEicicOperMode
is used to control CAC calculation
˗allUes – DL GBR, DL nonGBR, PDCCH loads are
considered
˗nonGbrPdcch – DL nonGBR and PDCCH loads are
considered
˗nonGbrOnly – only nonGBR load is considered
1) Load supervision and CAC exchange:
LNCEL:loadSettings:mlbEicicOperMode
allUes nonGbrPdcch nonGbrOnly

20. 20 RA41220-V-22R3 © Nokia 2021
LTE1841 Inter frequency load equalization
DL GBR Measured
Load
DL non-GBR
Measured Load
PDCCH Measured
Load
DL GBR Relative
Load
PDCCH Relative
Load
DL non-GBR
Relative Load
DL GBR Available
Capacity
PDCCH Available
Capacity
DL non-GBR
Available Capacity
0%
100%
Cell Load
X
[%]
50%
50%
AC
X
RL
X
50%
ML
X
X = GBR, nonGBR, PDCCH
•Each measured DL Load (ML) is reflected as Relative
Load (RL)
˗Relative Load defines measured load in relation to
configured Target Load Threshold (TL)
˗Target Load Threshold is configured via parameters:
LNCEL:LoadSettings:targetLoadGbrDl,
targetLoadNonGbrDl, targetLoadPdcch
˗Relative load is a subcomponent in calculation of DL
Available Capacity (AC)
•Available Capacity = [100% - RL]
•DL Composite Available Capacity is the minimum of
all AC:
CAC
DL
= min(AC
GBR
, AC
nonGBR
, AC
PDCCH
)
1) Load supervision and CAC exchange:
25%
TL
X

21. 21 RA41220-V-22R3 © Nokia 2021
LTE1841 Inter frequency load equalization
Resource Status Update (RSU) message
•Resource Status Update message contains LM
information coming from different eNB
•The first RSU is sent by responding eNB as soon as
first Load Measurements are available
•Subsequent reporting is handled according to
Requested Periodicity
˗If more than one feature activated on Requesting eNB
(like LTE1140 or LTE1113 among others) requires Load
Measurements from Responding eNB, the lowest
periodicity requested by all features is used
•Requested periodicity for LTE1841 is defined by
parameter LNCEL:amlePeriodLoadExchange
Cell1
…
Requesting eNB
X2AP: RSU
CellX
Cell1
…
Responding eNB
CellY
Note:
Successful RSR Initiation of Cell1.
First Load Measurements are available on Responding eNB
After each Requested periodicity RSU is sent again
X2AP:RSU (Cell1)
time
A B
Responding eNB
C C C C
A
B
C
Requested Periodicity
More details about RSR Procedure one can find here.
1) Load supervision and CAC exchange:

22. 22 RA41220-V-22R3 © Nokia 2021
LTE1841 Inter frequency load equalization
2) Check of active AMLE state conditions
LNCE
L
AMLEPR-0
amlePrId
cacHeadroom
deltaCac
maxCacThreshol
d
targetCarrierFreq
Active mode load equalization profile identifier
Headroom in CAC
Target carrier frequency
Difference in CAC of source and target cells
Threshold for maximum CAC
Note:
When LTE1841 is activated (LNBTS:actAmle = true), at least
default AMLEPR-0 has to be configured

Source Cell
Partner Cell
Check of active AMLE
state conditions
AMLE feature
When LTE1841 is enabled, source cell can be in
active or inactive AMLE state with partner cell
•Source Cell is in active AMLE state only when:
1.It is not in Active Inter Frequency Load Balancing
(iFLB) State (applicable when LTE1170/LTE1531 is
activated)
2.There is at least one partner cell configured
for source cell (LNREL:amleAllowed=true)

23. 23 RA41220-V-22R3 © Nokia 2021
LTE1841 Inter frequency load equalization
When LTE1841 is enabled, source cell can be in
active or inactive AMLE state with partner cell
•Source Cell is in active AMLE state only when:
3.Following criteria are met for configured partner cell:
CRITERIUM 1: CAC
S < AMLEPR:maxCacThreshold
CRITERIUM 2: CAC
T
≥ AMLEPR:cacHeadroom
CRITERIUM 3: CAC
T
- CAC
S
> AMLEPR:deltaCac
2) Check of active AMLE state conditions
Source cel is
loosing capacity
Target cel has
enough capacity
The difference between S
and T is enough to make
offload
MRBTS.LNBTS.LNCEL.AMLEPR.
maxCacThreshold
Threshold for maximum CAC AMLEPR;
0..100%;
Default :100%
MRBTS.LNBTS.LNCEL.AMLEPR.
cacHeadroom
Headroom in CAC
0..100%;
Default :0
MRBTS.LNBTS.LNCEL.AMLEPR.deltaCac
Difference in CAC of source and target cells
0..100%;
Default :20%

24. 24 RA41220-V-22R3 © Nokia 2021
LTE1841 Inter frequency load equalization
Example:
•3 partner cells
•2 partner frequency layers
AMLE State verification:
PC1
f1
PC2
f2
PC3
f2
CAC
PC1 CAC
PC2
CAC
PC3
Partner Cell (PC) of Source Cell (S)
CAC
S < maxCacThreshold
f1
CAC
S
< maxCacThreshold
f2
CAC
S
< maxCacThreshold
f2
CAC
PC2
≥ cacHeadroom
f2
STOP
CAC
PC2
– CAC
S
>∆CAC
f2 STOP
AMLE INACTIVE AMLE INACTIVE AMLE ACTIVE
2) Check of active AMLE state conditions
N
N
YYY
Y
CAC
PC3
≥ cacHeadroom
f2

25. 25 RA41220-V-22R3 © Nokia 2021
Candidate UE Selection procedure is reused from
LTE1170/LTE1531
•Inter Frequency Load Balancing QCI1 Bearer Check Timer is
started every time when:
˗UE either enters RRC Connection state or
˗UE enters cell that is already in unbalanced state (active iFLB state) via
Handover
•Inter Frequency Load Balancing Retry Timer is started every
time when:
˗Inter Frequency Load Balancing QCI1 Bearer Check Timer is expired
˗Inter Frequency Load Balancing Retry Timer is expired
˗UE enters cell that is balanced state (inactive iFLB state) via Handover,
regardless of AMLE state in cell.
LTE1841 Inter frequency load equalization
3) Candidate UE Selection
time
B B
Note:
Inter Frequency LB Bearer Check Timer is started
UE selection criteria are verified. Inter Frequency Load
Balancing Retry Timer (T
dyn
) is (re)started
A
B
A
UE enters RRC Connected State
or UE was handed over to the cell that is in
active iFLB state

26. 26 RA41220-V-22R3 © Nokia 2021
UE is a candidate for offloading only if it fulfills UE selection criteria
1)Source Cell is in active AMLE state
2)UE supports at least one partner frequency layer that is used by partner cell with which
source cell is in active AMLE state
3)UE has no QCI1 bearer established (depending on LNCEL:iFLBBearCheckTimer)
•UE with QCI1 established, analogously to iFLB feature, is considered to be candidate
for offloading only when LNCEL:iFLBBearCheckTimer = 31
4)UE has no GBR bearer established (depending on the
LNCEL:loadSettings:mlbEicicOperMode setting)
•UE with GBR bearer established can only be offloaded if GBR load is taken into
account during CAC calculation (LNCEL:loadSettings:mlbEicicOperMode = allUEs)
5) UE has no Secondary Cell (SCell) configured
6) There are no ongoing inter-frequency or inter-RAT measurements for the UE
7)Required functionalities, i.e. Inter frequency Handover and A4 measurements are
supported by the UE  UE reports FGI bit 13 = 1, 14 = 1 and 25 = 1
LTE1841 Inter frequency load equalization
3) Candidate UE Selection
Source
Cell
?
Partner
Cell

27. 27 RA41220-V-22R3 © Nokia 2021
For UE that is a candidate for offloading A4 measurements
are started, provided that maximum number of concurrent
A4 measurements (LNCEL:iFLBA4ActLim) is not reached
•s-measure in measConfig is set to 0
˗s-measure=0 causes instant start of UE measurements (regardless of RSRP
level of serving cell)
•ReportConfigEUTRA is added in reportConfigToAddModList
˗A4 configuration is hardcoded and not modifiable
•Activation of A4 is done by adding selected measObjectIds and reportConfigIds
to measIdToAddModList
˗Partner frequency layers (measObjectIds) that are supported by the UE and
for which at least one partner cell is in active AMLE state with source cell
are added
•UE is informed about changes in measConfig via RRC Connection
Reconfiguration message
˗Measurement gap handling (if needed) is included
LTE1841 Inter frequency load equalization Source Cell
Partner Cell
Measurement
Solicitation
AMLE feature
ReportConfigEUTRA (A4)
Parameter Name Set values
> Trigger Type event
>> eventId eventA4
>>> a4-Threshold
>>>> threshold-RSRP 0 (-140dBm)
>> hysteresis 0
>> Time To Trigger (TTT) 40ms
> Trigger Quantity RSRP
> Report Quantity Both(RSRP & RSRQ)
> MaxReportCells 8
> Report Interval 60min
> Report Amount 1
4) Measurement Solicitation

28. 28 RA41220-V-22R3 © Nokia 2021
Target Cell List (TCL) postprocessing
STEP 1: Removing unsuitable cells from TCL
•Cells with unsufficient level of RSRP/RSRQ according to filtering parameters setting:
LNHOIF:thresholdRsrpIFLBFilter and LNHOIF:thresholdRsrqIFLBFilter
•Cells from different RAT (including cells of Home eNB when LNBTS:actHeNBMobility is activated)
•Cells with unknown CAC and with too low CAC
•When AMLEPR:cacHeadroom > 0 then cells with CAC
T
< AMLEPR:cacHeadroom are removed, otherwise cells with CAC
T
=0% are
removed [no available capacity]
•Cells for which CAC of Source cell is too high [CAC
S
> AMLEPR:maxCacThreshold] *
•Cells that do not fulfill: CAC
T
- CAC
S
> AMLEPR:deltaCac *
•Number of AMLE HOs towards given cell, between two CAC updates from this cell,
is higher than LNCEL:amleMaxNumHo
•Cells that are blacklisted for Load Based HO (LB HO)
STEP 2: TCL sorting
•If there is at least one cell on TCL after STEP1, list is sorted according to descending ∆CAC
•First candidate that is at the top of TCL is a partner target cell with the biggest CAC deviation with source cell
LTE1841 Inter frequency load equalization Source Cell
Partner Cell
Load Equalization
execution
AMLE feature
All unsuitable cells are
removed from TCL
5) Load Equalization execution

29. 29 RA41220-V-22R3 © Nokia 2021
HO preparation phase
•First cell from the top of TCL is considered to be the first
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 (RAC) is responsible for
verification if given handover can be admitted
˗Case 1) Successful HO preparation phase
•If target cell provides sufficient number of resources to serve
the UE, HANDOVER REQUEST ACKNOWLEDGE
message is sent to source eNB  Handover Execution phase
is performed
LTE1841 Inter frequency load equalization
Target CellSource Cell
Handover Request Ack.

Handover Request
Radio Admission
Control
Cause: Reduce Load in Serving Cell
End of HO preparation phase
X2 based Handover message flow
NOTE: For simplicity, only X2 Load Based Handover is
described. In case of different types of HO (intra-eNB, S1
based HO) proper HO messages are used
5) Load Equalization execution

30. 30 RA41220-V-22R3 © Nokia 2021
HO preparation phase
˗Case 2) Unsuccessful HO preparation
phase
•If RAC of target cell rejects the HO Request,
HO Preparation failure with proper cause is
sent
-If RAC admits only some of UE`s bearers,
LBHO is cancelled by source cell (cause:
Partial HO)
•Target cell in which RAC rejects (or partially
admits) LBHO is blocked by source cell to
avoid next LBHOs during time defined by
LNBTS:prohibitLBHOTimer
•In such case, HO towards the second cell in
TCL (if any) will be triggered
LTE1841 Inter frequency load equalization
NOTE: For simplicity, only X2 Load Based Handover is
described. In case of different types of HO (intra-eNB, S1
based HO) proper HO messages are used
Target CellSource Cell
HO Preparation Failure
Cause: No Radio Resources Available in
Target Cell/Transport Resources
Unavailable

p
r
o
h
i
b
i
t
L
B
H
o
T
i
m
e
r
Handover Request
Cause: Reduce Load in Serving Cell
Handover Request
Handover Request
Cause: Reduce Load in
Serving Cell
Admission
Control
Cause: Reduce Load in Serving Cell
Cause: Reduce Load in Serving Cell
Handover Request
5) Load Equalization execution
Other
Target Cell

31. 31 RA41220-V-22R3 © Nokia 2021
Configuration Management
Abbrev Description MO
actAmle Activate active mode load equalization LNCEL
amlePrId Active mode load equalization profile identifier LNCEL:AMLEPR
targetCarrierFreq Target carrier frequency LNCEL:AMLEPR
amleAllowed Active mode load equalization allowed LNREL
cacHeadroom Headroom in CAC LNCEL:AMLEPR
deltaCac Difference in CAC of source and target cells LNCEL:AMLEPR
amlePeriodLoadExchange X2 resource status update periodicity LNCEL
maxCacThreshold Threshold for maximum CAC LNCEL:AMLEPR
LTE1841 Inter frequency load equalization

32. 32 RA41220-V-22R3 © Nokia 2021
Proposed Configuration
Only cosited LNREL will be created , only intrasector HO will be allowed
TechnologyAbbreviated Name MO Class Full Name Range and step Default ValuePROPOSED VAL UE Required
on Creation
4G amlePrId MRBTS/LNBTS/LNCEL/AMLEPRActive mode load equalization profile identifier0...15, step 1 0 0 Not modifiableMandatory
4G cacHeadroom MRBTS/LNBTS/LNCEL/AMLEPRHeadroom in CAC 0...100, step 1 0 100 On-line Mandatory
4G deltaCac MRBTS/LNBTS/LNCEL/AMLEPRDifference in CAC of source and target cells 0...100, step 1 20 8 On-line Mandatory
4G maxCacThreshold MRBTS/LNBTS/LNCEL/AMLEPRThreshold for maximum CAC 0...100, step 1 100 100 On-line Mandatory
4G targetCarrierFreq MRBTS/LNBTS/LNCEL/AMLEPRTarget carrier frequency 0...262143, step 1  F1,F2 On-line Mandatory
4G actAmle MRBTS/LNBTS/LNCEL Activate active mode load equalization  0 1 On-line Mandatory
4G actAmleServCellFilterMRBTS/LNBTS/LNCEL Activate AMLE serving cell threshold filtering  0  On-line Optional
4G amleMaxNumHo MRBTS/LNBTS/LNCEL Max number of AMLE-based HOs between two CAC updates1...100, step 1 10 10 On-line Mandatory
4G amlePeriodLoadExchangeMRBTS/LNBTS/LNCEL X2 resource status update periodicity for AMLE1000:1000ms;
2000:2000ms;
5000:5000ms;
10000:10000ms
1000 1000 On-line Mandatory
4G amleServCellThreshRsrpMRBTS/LNBTS/LNCEL AMLE serving cell RSRP threshold filter -140...-43, step 1-140  On-line Optional
4G amleServCellThreshRsrqMRBTS/LNBTS/LNCEL AMLE serving cell RSRQ threshold filter -20...-3, step 0.5-20  On-line Optional
4G maxNumAmleNeigh MRBTS/LNBTS/LNCEL Maximum number of AMLE neighbors 0...64, step 1 16 1 On-line Mandatory
4G amlePrId MRBTS/LNBTS/LNCEL/AMLEPRActive mode load equalization profile identifier0...15, step 1 0 0 Not modifiableMandatory
4G amleAllowed MRBTS/LNBTS/LNCEL/LNRELActive mode load equalization allowed  0 1 On-line Mandatory
4G targetLoadGbrDl MRBTS/LNBTS/LNCEL DL GBR resource target load 0...100, step 1 0...100, step 160 On-line Mandatory
4G targetLoadNonGbrDlMRBTS/LNBTS/LNCEL DL non-GBR resource target load 0...100, step 1 0...100, step 160 On-line Mandatory
4G targetLoadPdcch MRBTS/LNBTS/LNCEL PDCCH target load 0...100, step 1 0...100, step 160 On-line Mandatory
4G mlbEicicOperMode MRBTS/LNBTS/LNCEL Mode for calculating the CAC in load bal. and eICIC0:nonGbrOnly;
1:nonGbrPdcch;
2:allUes
2 0 On-line Mandatory

33. RA41220-V-22R3 © Nokia 2021