Release 11)
9 3GPP TS 28.628 V11.3.0 (2013-09)
LB LBO MRO NM NRM OAM RO SON UE Load Balancing
Load Balancing Optimization Mobility Robustness Optimisation Network Manager
Network Resource Model
Operation Administration Maintenance RACH Optimization
Self Organizing Networks User Equipment
4
4.1
4.1.1
4.1.1.1
SON Policy and Optimization Function Definitions
Monitoring and Management Operations for Self-Optimization
Monitoring and Management Function
Usage of Itf-N
For specifically defined Itf-N NRM Interface see clause 5.
4.2
4.2.1
Load Balancing Optimization Function
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:
3GPP
Release 11)
Target Name RRC connection establishments failure rate related to load E-RAB setup failure rate related to load 10 3GPP TS 28.628 V11.3.0 (2013-09)
Legal Values Integer [0..100] in unit percentage RRC Connection Abnormal Release Rate Related to Load E-RAB Abnormal Release Rate Related to Load Rate of failures related to handover Definition 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. 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. 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. 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. (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 Integer [0..100] in unit percentage Integer [0..100] in unit percentage 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
4.2.3.1
Optimization Method
Problem Detection
The problem detection is out of scope of this specification.
3GPP
Release 11)
11 3GPP TS 28.628 V11.3.0 (2013-09)
4.2.3.2 Problem Solution
The problem solution is out of scope of this specification.
4.2.4
4.2.4.1
Architecture
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) LB Policy Control Function LB Monitor Function Itf-N DM LB Policy Control Function EM LB Monitor Function eNB LB decision algorithm X2 eNB LB decision algorithm X2 eNB EM LB decision algorithm
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:
3GPP
Release 11)
Performance measurement name The number of Failed RRC connection establishments related to load The total number of Attempted RRC connection establishments The number of E-RAB setup failure related to load The total number of attempted E-RAB setup The number of abnormal RRC connection release related to load The total number connection release of RRC 12 Description Refer to 3GPP TS 32.425 [8] Failed RRC connection establishments Refer to 3GPP TS 32.425 [8] Attempted RRC connection establishments Refer to 3GPP TS 32.425 [8] Number of initial SAE Bearers failed to setup Refer to 3GPP TS 32.425 [8] Number of initial SAE Bearers attempted to setup Number of UE CONTEXT Release Request initiated by eNodeB Number of Successful UE Context Release Refer to 3GPP TS 32.425 [8] Number of SAE Bearers requested to release initiated by eNodeB per cause Refer to 3GPP TS 32.425 [8] Number of SAE Bearers successfully released Refer to 4.3.5 3GPP TS 28.628 V11.3.0 (2013-09)
Related targets RRC connection establishments failure rate related to load RRC connection establishments failure rate related to load E-RAB setup failure rate related to load E-RAB setup failure rate related to load RRC Connection Abnormal Release Rate Related to Load RRC Connection Abnormal Release Rate Related to Load E-RAB Abnormal Release Rate Related to Load E-RAB Abnormal Release Rate Related to Load Rate of failures related to handover Rate of failures related to handover The number of E-RAB abnormal release related to load The total number of E-RAB release the number of failure events related to handover the total number of handover Refer to 4.3.5 events
NOTE:
The monitoring of performance measurements will make use of existing PM IRP.
4.3
4.3.1
Handover (HO) Parameter Optimization Function
Objective and Targets
For intra-LTE, one of the following targets or the combination of the following targets shall be used. The specific target value shall be configured by operators. Operators should assign weights for targets being used.
Target Name Definition Rate of failures related to (the number of failure events related to handover) / (the total handover number of handover events) The target is met if the actual rate is smaller than the target value. Legal Values Integer [0..100] in unit percentage The objective of minimizing the number of unnecessary handovers shall always be pursued in case the other target/s configured by the operator is/are achieved. This objective may not need configuration of a target value.
4.3.2 Parameters To Be Optimized
The tables below summarise the handover parameters in TS 36.331 [6].
3GPP
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