4.2 Load balancing optimization function
28.6283GPPInformation Service (IS)Release 17Self-Organizing Networks (SON) Policy Network Resource Model (NRM) Integration Reference Point (IRP)Telecommunication managementTS
4.2.1 Objective and targets
The objective of LB Optimization is to cope with undesired traffic load distribution and to minimize the number of handovers and redirections needed to achieve the load balancing. One of the following targets or the combination of the following targets shall be used. The specific target value or values shall be configured by operators. Operators should assign weights for targets being used.
Targets drawn from the following table can be configured for LBO:
|
Target Name |
Definition |
Legal Values |
|---|---|---|
|
RRC connection establishments failure rate related to load |
The number of Failed RRC connection establishments related to load/ The total number of Attempted RRC connection establishments. The target is met if the actual rate is smaller than the target value. |
Integer [0..100] in unit percentage |
|
E-RAB setup failure rate related to load |
The number of E-RAB setup failure related to load/ The total number of attempted E-RAB setup For E-RAB setup failure related to load, the causes “Reduce load in serving cell” and “Radio resources not available” defined in TS 36.413 [12] could be used. The target is met if the actual rate is smaller than the target value. |
Integer [0..100] in unit percentage |
|
RRC Connection Abnormal Release Rate Related to Load |
The number of abnormal RRC connection release related to load/ The total number of RRC connection release. The target is met if the actual rate is smaller than the target value. |
Integer [0..100] in unit percentage |
|
E-RAB Abnormal Release Rate Related to Load |
The number of E-RAB abnormal release related to load/ The total number of E-RAB release For E-RAB setup failure related to load, the causes “Reduce load in serving cell” and “Radio resources not available” defined in TS 36.413 [12] could be used. The target is met if the actual rate is smaller than the target value. |
Integer [0..100] in unit percentage |
|
Rate of failures related to handover |
(the number of failure events related to handover) / (the total number of handover events) The target is met if the actual rate is smaller than the target value. |
Integer [0..100] in unit percentage |
For the following targets out of the above table, the target values depend on the composite available capacity range in the cell and are defined separately for uplink and downlink. For these tuples can be configured, indicating the capacity ranges together with the target value valid in that range.
RRC connection establishments failure rate related to load,
E-RAB setup failure rate related to load,
RRC Connection Abnormal Release Rate Related to Load,
E-RAB Abnormal Release Rate Related to Load
For the following targets shall be identical with the corresponding targets defined in Handover Optimization.
Rate of failures related to handover
4.2.2 Parameters To Be Optimized
To reach load optimization target, LBO may optimize some mobility settings (HO and/or idle mobility configuration) defined in TS 36.331 [6].
4.2.3 Optimization method
4.2.3.1 Problem detection
The problem detection is out of scope of this specification.
4.2.3.2 Problem solution
The problem solution is out of scope of this specification.
4.2.4 Architecture
4.2.4.1 Definition of logical functions
LB Monitor Function: This function is used for monitoring the load balance optimization (e.g. Monitoring related performance counters or alarms).
LB Policy control function: This function is used for configuring the load balance optimization policies.
4.2.4.2 Location of logical functions
NM (IRPManager)
DM
eNB
Itf-N
eNB
EM
LB Monitor Function
LB Policy Control Function
X2
eNB
LB Monitor Function
LB Policy Control Function
X2
EM
For Load Balancing, the SON LB decision algorithm is located in eNB. The detailed SON functionalities in eNB are out of scope of this specification.
4.2.5 PM
IRPManager may collect Load balancing related performance measurements. Performance Measurements related with Load balancing are captured in the table below:
|
Performance measurement name |
Description |
Related targets |
|
The number of Failed RRC connection establishments related to load |
Refer to 3GPP TS 32.425 [8] Failed RRC connection establishments |
RRC connection establishments failure rate related to load |
|
The total number of Attempted RRC connection establishments |
Refer to 3GPP TS 32.425 [8] Attempted RRC connection establishments |
RRC connection establishments failure rate related to load |
|
The number of E-RAB setup failure related to load |
Refer to 3GPP TS 32.425 [8] Number of initial SAE Bearers failed to setup |
E-RAB setup failure rate related to load |
|
The total number of attempted E-RAB setup |
Refer to 3GPP TS 32.425 [8] Number of initial SAE Bearers attempted to setup |
E-RAB setup failure rate related to load |
|
The number of abnormal RRC connection release related to load |
Number of UE CONTEXT Release Request initiated by eNodeB |
RRC Connection Abnormal Release Rate Related to Load |
|
The total number of RRC connection release |
Number of Successful UE Context Release |
RRC Connection Abnormal Release Rate Related to Load |
|
The number of E-RAB abnormal release related to load |
Refer to 3GPP TS 32.425 [8] Number of SAE Bearers requested to release initiated by eNodeB per cause |
E-RAB Abnormal Release Rate Related to Load |
|
The total number of E-RAB release |
Refer to 3GPP TS 32.425 [8] Number of SAE Bearers successfully released |
E-RAB Abnormal Release Rate Related to Load |
|
the number of failure events related to handover |
Refer to 4.3.5 |
Rate of failures related to handover |
|
the total number of handover events |
Refer to 4.3.5 |
Rate of failures related to handover |
NOTE: The monitoring of performance measurements will make use of existing PM IRP.