HSIFLS trial on Tripoli The document summarizes a trial of HSDPA Inter-Frequency Load Sharing (HSIFLS) on the city of Tripoli. It describes the HSIFLS feature, parameters that can be configured like threshold levels, and monitoring counters. The trial tested different threshold scenarios to prioritize load sharing between two carriers and equally distribute HS users and load for better spectrum efficiency and lower rejections. The recommended scenario was found to be using a threshold around 35% to balance traffic.

1. HSIFLS TRIAL on TRIPOLI
Site

2. outline
› Introduction
› HS Inter-Frequency Load Sharing (HSIFLS)
› Conclusion

3. Introduction
› In P7 inter-frequency load sharing feature has the following
properties:
– Feature : FAJ 121 435
– Triggered at RRC connection setup
– Applies to all calls (R99 and HS)
– Does not take into account UE and cell capabilities
– Triggered only by “non-HSDPA and the HSDPA required power”
– Triggered only when downlink transmitted power is above 50%
(fixed) of the pwradm (configurable).
– Activation at RNC level by setting loadSharingRrcEnabled=1

4. Introduction
› In W10 two new load sharing features are introduced (in
addition to the existing ones) to balance more efficiently
the traffic between cells:
– HSDPA Inter-frequency loadsharing
– Non-HSPA Inter-frequency loadsharing
› Without loss of generality, These features have three
degrees of freedom:
– Trigger type (HS users, Power, Dlcode)
– Trigger thresholds (configurable)
– UE type and cell capabilities (considered)

5. HSIFLS
› HSDPA Inter-frequency loadsharing
– Feature : FAJ 121 1467
– Triggered at RAB setup or upswitch from FACH/DCH to HS
(Controlled by cell param iflsmode)
– Applies to HS connection (Including EUL, MIMO, MC)
– Triggered by the number of HS users
– Activated on RNC level (HspaLoadSharing should be Enabled and
Activated)
– Cell parameter Coveragerelation.hsLoadSharing should be ON
– HSIFLS is working if cell parameter hsIflsThreshUsers>0
– Up to 5 coveragerelations (colocated and non-colocated, SRNC)
can be defined for each cell and the best cell among them is chosen
for load sharing
– UE and cell capability are considered (capability examined first)
– Old cell selection procedure is disabled when HSIFLS is operational

6. HSIFLS-Algorithm
› Feature is Enabled and activated on RNC level
› On cell level CoverageRelation is defined, Attribute hsLoadSharing=ON and hsIflsThreshUsers>0
› If any of previous conditions are not met, HS cell selection procedure is followed
› Target cells should have at least same coverage as the source because Blind IFHO will be attempted
Trigger
(iflsmode)
Path Loss check
(pathlossThreshold )
iflsmode=0 (New RAB)
iflsmode=1 (Upswith)
iflsmode=2 (New RAB OR Upswith)Cpich_Pwr – Cpich_RSCP >
pathlossThreshold
This check is not performed in Cell_FACH
Evaluation : Capability
If the UE is more capable than the source
cell, trigger in the source cell does not apply
and also the hysteresisEvaluation : Load
Continue in the same cell
Blind IFHO, FACH to HS
HS-Reconfig; Fail?
Non-Congested cell found
UE has
same
capability
Suitable cell found
Continue in Src cell
Continue in target cell

7. HSIFLS-Evaluation-load
Please
refer to
next slides
for param
definition

8. HSIFLS-Parameter
› coverageRelation Used to define a coverage related candidate cell, that
can be used as a target for load sharing. Applies to both HSDPA and Non-
HSPA load sharing, and is also used by HS cell selection. The following
attributes can be configured:
– hsLoadsharing. If this attribute is set to ON, this coverage relation applies for
HSDPA Inter-frequency load sharing.
– dchLoadsharing. If this attribute is set to ON, this coverage relation applies for Non-
HSPA Inter-frequency load sharing.
– hsCellSelection. Can be set to ON in only one coverage relation out from the same
cell. Defines that this coverage relation applies for HS cell selection.
› hsIflsThreshUsers An Operator cell parameter. Defined as percent of
the admission limit hsdpaUsersAdm. More than this number of HS serving cell
users are required to trigger HS load sharing out from the cell. If set to 0 the
feature is OFF in the cell.

9. HSIFLS-Parameter
› hsIflsMarginUsers An Operator cell parameter. Defines a number of serving
cell HS users that shall be subtracted when computing the remaining resources
in a cell. Defined as percent of the admission limit hsdpaUsersAdm.
› pathlossThreshold An Operator cell parameter. Defines the maximum
allowed pathloss before triggering a blind IFHO attempt from a dedicated
channel. Also applies to Non-HSPA load sharing.
› iflsHyst An Operator RNC parameter. Defines a required load hysteresis
between source and target cell, as a percent of current load. Also applies to
Non-HSPA load sharing.
› iflsMode An Operator cell parameter. Configures which RAB switches that
can trigger load sharing. Also applies to non-HSPA load sharing.
– RAB_EST: Trigger at RAB establishment only.
– UPSWITCH_ATT: Trigger at upswitch attempts caused by channel switching. Note
that this value will disable non-HSPA load sharing since this feature is only triggered
by RAB establishment.
– RAB_EST_OR_UPSWITCH_ATT: Trigger both a RAB establishment and at upswitch
attempts.

10. HSIFLS-Monitoring
pmOutHsIflsHhoAtt
Number of attempted outgoing Hard Handovers due to HS Inter-Frequency load sharing. This counter is incremented
by one when an RRC Physical Channel Reconfiguration, Radio Bearer Setup or Radio Bearer Reconfiguration is sent
to the UE, for an attempt to do a Hard HO or reconfiguration to a load sharing candidate cell, and triggered by HS
Inter-Frequency load sharing. The counter is stepped in the best cell in the source active set.
pmOutHsIflsHhoSucc
Number of successful outgoing Hard Handovers due to HS Inter-Frequency load sharing.This counter is incremented
by one when an RRC Physical Channel Reconfiguration Complete, Radio Bearer Setup Complete or Radio Bearer
Reconfiguration Complete is received from the UE, during an attempt to do a Hard HO or reconfiguration to a load
sharing candidate cell, triggered by HS Inter-Frequency load sharing. The counter is stepped in the best cell in the
source active set.
pmInHsIflsHhoAtt
Number of attempted incoming Hard Handovers due to HS Inter-Frequency load sharing. This counter is incremented
by one when an RRC Physical Channel Reconfiguration, Radio Bearer Setup or Radio Bearer Reconfiguration is sent
to the UE, for an attempt to do a Hard HO or reconfiguration to a load sharing candidate cell, and triggered by HS
Inter-Frequency load sharing. The counter is stepped in the target cell.
pmInHsIflsHhoSucc
Number of successful incoming Hard Handovers due to HS Inter-Frequency load sharing. This counter is incremented
by one when an RRC Physical Channel Reconfiguration Complete, Radio Bearer Setup Complete or Radio Bearer
Reconfiguration Complete is received from the UE, during an attempt to do a Hard HO or reconfiguration to a load
sharing candidate cell, triggered by HS Inter-Frequency load sharing. The counter is stepped in the target cell.

11. HSIFLS-Case Study
› HS-HIFLS can be used to control user distribution between carriers.
› It can be used to efficiently utilize all resources on both carriers.
› Feature activated on a Tripoli cell sector 2.
› 4 different scenarios and thresholds are done:
RNC Feature/Param
hsLoadSharing ON
iflsHyst 5
Parameter Carrier Scenario 1 Scenario 2 Scenario 3 Scenario 4
hsIflsThreshUsers 1 50 35 10 20
pathlossThreshold 1 140 140 140 140
hsIflsMarginUsers 2 0 0 0 0
iflsmode 1 0 0 0 0

12. HSIFLS-Case Study
› Prioritize sharing from 1st
carrier to 2nd
carrier
› IFLS intensity increases at more aggressive settings with good success
rate.
IFLS at 50%
IFLS at 35%
IFLS at 10%
IFLS at 20%

13. HSIFLS-Case Study
IFLS at 50%
IFLS at 35%
IFLS at 10%
IFLS at 20%
› At HSIFLS activation (at 50% threshold), the gap between F1 and F2 in
terms or HS users and HS RAB attempts is reduced. At 35% it is even
reduced more. At aggressive settings(10% and 20%), F2 is favorized more.

14. HSIFLS-Case Study
IFLS at 50%
IFLS at 35%
IFLS at 10%
IFLS at 20%
› HS RAB SR is stable except at aggressive settings where F2 HS rejections
increased.

15. HSIFLS-Case Study-Conclusion
› Using different thresholds we can distribute the HS users
and the HS load between the 2 carriers.
› The recommended scenario is to equally distribute the
users on both carriers
– For higher spectrum efficiency
– Lower HS rejections
– To achieve the maximum possible user throughput especially a very
high load.