8 SON procedures

28.3133GPPManagement and orchestrationRelease 17Self-Organizing Networks (SON) for 5G networksTS

8.1 Introduction

The procedures listed in clause 8 are some of all the possibilities, and are not exhaustive.

8.2 Distributed SON

8.2.1 RACH Optimization (Random Access Optimisation)

Figure 8.2.1-1 depicts a procedure that describes how D-SON management function can manage the RACH optimization (D-SON) function. It is assumed that the D-SON management function has consumed the performance assurance management service to collect RACH optimisation related measurements.

Figure 8.2.1-1: RACH Optimization procedure

1. The D-SON management function consumes the provisioning MnS with modifyMOIAttributes operation (see clause 5.1.3 in TS 28.532 [3]) to configure the targets for RACH optimization function.

1.a The provisioning MnS sets the targets for RACH optimization (D-SON) function (NOTE).

2. The D-SON management function consumes the provisioning MnS with modifyMOIAttributes operation to enable the RACH optimization function for a given NR cell if it is not enabled.

3.a The provisioning MnS enables the RACH optimization (D-SON) function (NOTE).

3. The RACH optimization (D-SON) function receives the RACH information report from UE(s), and analyses them to determine the actions to optimize the RACH performance if the performance does not meet the targets by updating the RACH parameters.

4. The D-SON management function collects the RACH related performance measurements.

5. The D-SON management function analyses the measurements to evaluate the RACH performance,

6. The D-SON management function consumes the provisioning MnS with modifyMOIAttributes operation to update the targets of the RACH optimization function, when the RACH optimization performance does not meet the targets:

6.a The provisioning MnS updates the targets for RACH optimization function (NOTE).

NOTE: The interface between provisioning MnS and RACH optimization is not subject to standardization.

8.2.2 MRO (Mobility Robustness Optimisation)

Figure 8.2.2-1 depicts a procedure that describes how D-SON management function can manage the MRO function. It is assumed that the D-SON management function has consumed the performance assurance MnS to create PM jobs to collect handover related measurements.

Figure 8.2.2-1: MRO procedure

1. The D-SON management function consumes the provisioning MnS with modifyMOIAttributes operation (see clause 5.1.3 in TS 28.532 [3]) to configure targets for the MRO function.

1.a The provisioning MnS sets the targets for MRO function (NOTE).

2. The D-SON management function consumes the management service for NF provisioning with modifyMOIAttributes operation to configure the ranges of handover parameters.

2.a The MnS of provisioning sets the ranges for MRO function (NOTE).

3. The D-SON management function consumes the management service for NF provisioning with modifyMOIAttributes operation to configure the MRO control parameters (e.g. Maximum deviation of Handover Trigger, Minimum time between Handover Trigger changes).

3.a The MnS of provisioning sets the MRO control parameters for MRO function (NOTE).

4. The D-SON management function consumes the NF provisioning MnS with modifyMOIAttributes operation to enable the MRO function for a given NR cell if it is not enabled.

4.a The provisioning MnS enables the MRO function (NOTE).

5. The MRO function receives MRO information reports from UE(s), and analyses them to determine the actions to optimize the MRO performance. If the performance does not meet the targets, it updates the handover parameters.

6. The D-SON management function collects MRO related performance measurements.

7. The D-SON management function analyses the measurements to evaluate the MRO performance,

8. The D-SON management function performs one of the following actions, when the MRO performance does not meet the targets:

8.1. Consume the MnS of provisioning with modifyMOIAttributes operation to update the targets of the MRO function;

8.1.a The MnS of provisioning updates the targets for MRO function (NOTE).

8.2. Consume the MnS of provisioning with modifyMOIAttributes operation to update the ranges of the handover parameters;

8.2.a The MnS of provisioning updates the ranges of the handover parameters (NOTE).

8.3. Consume the MnS of provisioning with modifyMOIAttributes operation to update the control parameters;

8.3.a The MnS of provisioning updates the control parameters (NOTE).

NOTE: The interface between provisioning MnS and MRO function is not subject to standardization.

8.2.3 PCI configuration

8.2.3.1 Initial PCI configuration

Figure 8.2.3.1-1 depicts a procedure that describes how D-SON management function can manage the PCI configuration (D-SON) function to assign the initial PCI values to an NR cell.

Figure 8.2.3.1-1: Initial PCI configuration procedure

1. The D-SON management function consumes the MnS of NF provisioning with modifyMOIAttributes operation to configure the PCI list for an NR cell.

1.a The producer of provisioning MnS sets the PCI list at the PCI configuration (D-SON) function. (NOTE)

2. The D-SON management function consumes the MnS of NF provisioning with modifyMOIAttributes operation to enable the PCI configuration function for NR cell(s) if it is not enabled.

2.a The MnS of provisioning enables the PCI configuration (D-SON) function (NOTE).

3. The PCI configuration (D-SON) function selects PCI value(s) from the PCI list.

4. The PCI configuration (D-SON) function reports the PCI value(s) being assigned to the MnS of NF provisioning.

5. The MnS of NF provisioning sends a notification notifyMOIAttributeValueChange to D-SON management function with sourceIndicator = SON_operation, attributeValueChange = < nRPCI, new PCI value> (see clause 11.1.1.9.2 in TS 28.532 [3]) to indicate the PCI value(s) being assigned to NR cell(s).

NOTE: The interface between MnS of NF provisioning and PCI configuration (D-SON) function is not subject to standardization.

8.2.3.2 PCI re-configuration failure mitigation

Figure 8.2.3.2-1 depicts a procedure that describes how D-SON management function can re-configure the PCI lis for the NR cell, when the PCI configuration function is not able to mitigate a PCI collision or PCI confusion problemt.

Figure 8.2.3.2-1: PCI re-configuration failure mitigation procedure

1. The PCI configuration (D-SON) function reports to the producer of fault supervision MnS that PCI configuration function failed to mitigate the PCI collision or PCI confusion problems (NOTE).

2. The producer of fault supervision MnS sends a notification notifyNewAlarm to D-SON management function to report the PCI configuration function failure.

3. The D-SON management function consumes the MnS of NF provisioning with modifyMOIAttributes operation to re-configure the PCI list for NR cell(s).

3.a The MnS of NF provisioning re-configures the PCI list for NR cell(s) (see NOTE).

4. The PCI configuration (D-SON) function selects PCI value(s) from the updated PCI list.

5. The PCI configuration (D-SON) function reports the PCI value(s) being assigned to the MnS of NF provisioning.

6. The Producer of provisioning MnS sends a notification notifyMOIAttributeValueChange to the D-SON management function with sourceIndicator = SON_operation, attributeValueChange = < nRPCI, new PCI value, old PCI value> (see clause 11.1.1.9.2 in TS 28.532 [3]) to indicate the new PCI value being assigned to NR cell.

7. The PCI configuration (D-SON) function notifies MnS of fault supervision that the PCI configuration function has been restored (see NOTE).

8. The producer of fault supervision MnS sends a notification notifyClearedAlarm to D-SON management function to report that the PCI configuration function has been restored.

NOTE: The interface betweenProducer of provisioning MnS and PCI configuration (D-SON) function is not subject to standardization.

8.2.3.3 PCI re-configuration

Figure 8.2.3.3-1 depicts a procedure that describes how the PCI configuration function, when detecting a PCI collision or confusion, re-configures the PCI of the cell based on the PCI list and notifies the D-SON management consumer.

Figure 8.2.3.3-1: PCI re-configuration procedure

1. The PCI configuration (D-SON) function detects and corrects the PCI collision or PCI confusion problem for a NR cell.

2. The PCI configuration (D-SON) function indicates the attribute change to the Producer of provisioning MnS. (NOTE)

3. The Producer of provisioning MnS sends a notification notifyMOIAttributeValueChange to the D-SON management function with sourceIndicator = SON_operation, attributeValueChange = < nRPCI, new PCI value, old PCI value> (see clause 11.1.1.9.2 in TS 28.532 [3]) to indicate the new PCI value having been assigned to NR cell.

NOTE: The interface between Producer of provisioning MnS and PCI configuration (D-SON) function is not subject to standardization.

8.2.4 LBO (Load Balancing Optimisation)

Figure 8.2.4-1 depicts a procedure that describes how D-SON management function can manage the LBO function. It is assumed that the D-SON management function has consumed the performance assurance MnS to create PM jobs to collect handover related measurements.

Figure 8.2.4-1: D-LBO procedure

1. The D-SON management function consumes the management service for NF provisioning with modifyMOIAttributes operation (see clause 5.1.3 in TS 28.532 [3]) to configure the ranges of HO and/or reselection parameters for the LBO function.

1.a The MnS of provisioning sets the ranges for MRO function (NOTE).

2. The D-SON management function consumes the NF provisioning MnS with modifyMOIAttributes operation to enable the LBO function for a given NR cell if it is not enabled.

2.a The provisioning MnS enables the LBO function (NOTE).

3. The LBO function collects real-time load information to determine and perform actions to balance the traffic loads among NR cells.

4. D-SON management function collects LBO related performance measurements.

5. The D-SON management function analyses the measurements to evaluate the LBO performance,

6. The D-SON management function consume the MnS of provisioning with modifyMOIAttributes operation to update the ranges of handover parameters if the LBO failed to meet expection,

6.a. The MnS of provisioning updates the ranges of HO and/or reselection parameters (NOTE).

NOTE: The interface between provisioning MnS and D-LBO function is not subject to standardization.

8.3 Centralized SON

8.3.1 PCI configuration

8.3.1.1 Initial PCI configuration

Figure 8.3.1.1-1 depicts a procedure that describes how C-SON can assign the PCI values to NR cells the first time.

Figure 8.3.1.1-1: Initial PCI configuration procedure

1. The C-SON determines the PCI value(s) for NR cell(s).

2. The C-SON consumes the MnS of NF provisioning with modifyMOIAttributes operation to configure the PCI value(s) for NR cell(s).

2.a The MnS of provisioning sets the PCI value(s) for NR cell(s) (NOTE)

3. The producer of provisioning MnS sends a notification notifyMOIAttributeValueChange to C-SON function with sourceIndicator = SON_operation, attributeValueChange = < nRPCI, new PCI value> (see clause 11.1.1.9.2 in TS 28.532 [3]) to indicate the PCI value(s) being assigned to NR cell(s).

NOTE: The interface between MnS of provisioning and PCI configuration (D-SON) function is not subject to standardization.

8.3.1.2 PCI re-configuration

Figure 8.3.1.2-1 depicts a procedure that describes how C-SON function can re-configure the PCI list for NR cell(s) when PCI collision or PCI confusion issues were detected. It is assumed that the C-SON function has consumed the MnS of performance assurance to create PM jobs to collect PCI related measurements.

Figure 8.3.1.2-1: PCI re-configuration procedure

1. The C-SON function collects PCI related performance measurements that are derived from MeasResultListNR (see clause 6.3.2 in TS 38.331 [9]) from producer of performance assurance MnS.

2. The C-SON function analyses the NRM data and PCI related measurements to detect the PCI collision or PCI confusion problems for NR cell(s).

3. The C-SON function determines the new PCI value(s) for NR cell(s).

4. The C-SON function consumes the MnS of NF provisioning with modifyMOIAttributes operation to re-configure the PCI values for NR cell(s).

4.a The MnS of NF provisioning set the PCI value(s) for NR cell(s).

5. The producer of provisioning MnS sends a notification notifyMOIAttributeValueChange to C-SON function with sourceIndicator = SON_operation, attributeValueChange = < nRPCI, new PCI value, old PCI value> (see clause 11.1.1.9.2 in TS 28.532 [3]) to indicate the PCI value(s) being assigned to NR cell(s).

8.3.2 Procedures for establishment of a new RAN NE in network

8.3.2.1 Procedures for RAN NE plug and connect to management system

The NE described in this procedure can be gNB in non-split scenario and gNB-DU in split scenario.

Note 1: The NE within virtualization is not addressed.

The details of procedure flow and descriptions are covered in TS 28.315 [21].

Note 2: Void

Note 3: Void

Note 4: Void.

Note 5: Void.

8.3.2.2 Procedures for self-configuration management

The Figure 8.3.2.2-1 illustrates the procedure for start self-configuration management.

Figure 8.3.2.2-1: Procedures for self-configuration management

1. MnS consumer of self-configuration management sends createScManagementProfile request for NE(s) of a certain type to MnS producer of self-configuration management. NE information, stop point information and step information may be included in the request.

2. MnS producer of self-configuration management creates ScManagementProfile instance for NE(s) specified in the received request.

3. MnS producer of self-configuration management sends the create ScManagementProfile response to MnS producer of self-configuration management.

4. For each NE (specified in the created ScManagementProfile) starting its self-configuration process, MnS producer of self-configuration management sends NotifyScProcessCreation notification to MnS consumer of self-configuration management.

5. When arrival at a stop point (e.g. stop point waiting for the network configuration data) or step described in corresponding ScManagementProfile, MnS producer of self-configuration management sends NotifyProcessStage notification to MnS consumer of self-configuration management.

6. If arrival at a stop point in step 5), MnS consumer of self-configuration management sends ResumeScProcess request to MnS producer of self-configuration management. If the self-configuration process is suspended at a stop point and is waiting for the network configuration data, the request include network configuration data or information indicating location of network configuration data.

7. When the self-configuration process is terminated, the MnS producer of self-configuration management sends NotifyScProcessDeletion notification to MnS consumer of self-configuration management.

8.3.3 RRM resources optimization for network slice instance(s)

Figure 8.3.3-1 depicts an example of network slice instances that are created to support various services, such as URLLC, eMBB, or mMTC with different RRM resources requirements, where network slice instances sNSSAI #2-1 and sNSSAI #2-2 support a kind of RRM requirements, while network slice instances sNSSAI #1 supports different RRM requirements. It shows that the RRM resources provided by network functions of DU, CUUP, and CUCP are characterized by RRMPolicyRatio IOC with rRMPolicyMaxRatio, rRMPolicyMinRatio, and rRMPolicyDedicatedRatio attributes to define the shared resources, prioritized resources, and dedicated resources for network slice instance(s) (see clause 4.3.36.1 in TS 28.541 [13]).

The RRMPolicyRatio IOC has a base class RRMPolicy IOC that contains resourceType (i.e. PRB for DU, DRB for CUUP, and RRC connected user for CUCP) and rRMPolicyMemberList that contains the network slice instance(s) subject to this policy (see clause 4.3.43 in TS 28.541 [13]). A network function may have one or more RRMPolicyRatio MOI(s) where each RRMPolicyRatio MOI is associated with network slice instance(s) that share the same RRM resource requirements.

Figure 8.3.3-1: RRM policies for multiple network slice instances

It is assumed that the C-SON function has consumed the MnS of performance assurance to create PM jobs to collect RRM related measurements from RAN nodes, such as DU, CUCP, and CUUP where the network slice instances are created, and an AI/ML model has been created based on the use plane and control plane information (e.g. traffic loads and patterns) that are collected from the RRM related performance measurements received previously.

Figure 8.3.3-2: RRM resources optimization procedure

1. The C-SON function consumes the performance assurance MnS to receive the measurements (e.g. mean and peak numbers of PRB usage on DL / UL, average DL / UL UE throughput in gNB, distribution of DL / UL UE throughput in gNB) from NF DU to monitor the performance of network slice instances identified by sNSSAI #1 and sNSSAI #2.

2. The C-SON function consumes the performance assurance MnS to receive the measurements (e.g. such as mean and peak numbers of DRBs successfully setup) from NF CUUP to monitor the performance of network slice instances identified by sNSSAI #1 and sNSSAI #2.

3. The C-SON function consumes the performance assurance MnS to receive the measurements (e.g. mean numbers of PDU Sessions requested to setup, mean numbers of PDU Sessions successfully setup) from NF CUCP to monitor the performance of network slice instances identified by sNSSAI #1 and sNSSAI #2.

4. The C-SON function analyzes the measurements to train the AI/ML model and determines the actions if needed to optimize the RRM resources for network slice instance(s) that include consuming the MnS of provisioning to update the RRMPolicyRatio corresponding to the specific network slice instance(s).

If the RRM resources for network slice instances at DU need update, then the following steps are executed:

5. The C-SON function consumes the MnS of NF provisioning with modifyMOIAttributes operation to re-configure the RRMPolicyRatio for the NF DU.

5.a The MnS of NF provisioning updates RRMPolicyRatio at the NF DU.

6. The producer of provisioning MnS sends a notification notifyMOIAttributeValueChange to C-SON function with sourceIndicator = SON_operation, attributeValueChange = < RRMPolicyRatio, new value, old value> to indicate the successful RRMPolicyRatio update.

If the RRM resources for network slice instances at CUUP need update, then the following steps are executed:

7. The C-SON function consumes the MnS of NF provisioning with modifyMOIAttributes operation to re-configure the RRMPolicyRatio for the NF CUUP.

7.a The MnS of NF provisioning updates RRMPolicyRatio at the NF CUUP.

8. The producer of provisioning MnS sends a notification notifyMOIAttributeValueChange to C-SON function with sourceIndicator = SON_operation, attributeValueChange = < RRMPolicyRatio, new value, old value> to indicate the successful RRMPolicyRatio update.

If the RRM resources for network slice instances at CUCP need update, then the following steps are executed:

9. The C-SON function consumes the MnS of NF provisioning with modifyMOIAttributes operation to re-configure the RRMPolicyRatio for the NF CUCP.

9.a The MnS of NF provisioning updates RRMPolicyRatio at the NF CUCP.

10. The producer of provisioning MnS sends a notification notifyMOIAttributeValueChange to C-SON function to indicate the successful RRMPolicyRatio update.

NOTE: The interface between producer of provisioning MnS and NFs is not subject to standardization.

8.3.4 Centralized Capacity and Coverage Optimization (CCO)

Figure 8.3.4-1 depicts the procedure of centralized capacity and coverage optimization. It is assumed that PM job control and provisioning have been executed to allow C-SON function to receive performance measurements, MDT, RLF, and RCEF reports.

Figure 8.3.4-1: Capacity and coverage optimization procedure

1. The C-SON function receives the measurements, as listed in clause 7.2.3.3.1, which are used to detect the capacity and coverage issues in NR cells.

2. The C-SON function receives MDT, RLF, and RCEF reports, as listed in clause 7.2.3.3.2, which are used to detect the capacity and coverage issues in NR cells.

3. The C-SON function analyzes the measurements, MDT, RLF, and RCEF reports to determine whether the capacity and coverage of given cells or beams need to be optimized.

If the capacity and coverage of given cells or beams need to be optimized, then the following steps are executed:

4. The C-SON function determine the actions to mitigate the CCO issues.

5. The C-SON function consumes the MnS of NF provisioning with modifyMOIAttributes operation to re-configure the CCO control parameters, as listed in clause 7.2.3.2.1.

5.a The MnS of NF provisioning updates the CCO control parameters at the NF for NR cells (NOTE).

6. The producer of provisioning MnS sends a notification notifyMOIAttributeValueChange to C-SON function with sourceIndicator = SON_operation, attributeValueChange = < attributes being changed> to indicate the CCO control parameters have been updated successfully.

7. The C-SON function collects the measurements.

8. The C-SON function analyzes the measurements to evaluate if the COO issues have been mitigated.

If the the CCO issues have not been mitigated, then the following steps are executed:

9. The C-SON function consumes the MnS of NF provisioning with modifyMOIAttributes operation to re-configure the CCO control parameters, as listed in clause 7.2.3.2.1.

9.a The MnS of NF provisioning updates the CCO control parameters at the NF for NR cells (NOTE).

10. The producer of provisioning MnS sends a notification notifyMOIAttributeValueChange to C-SON function with sourceIndicator = SON_operation, attributeValueChange = < attributes being changed> to indicate the CCO control parameters have been updated successfully.

NOTE: The interface between producer of provisioning MnS and NFs is not subject to standardization.

Annex A (informative):
PlantUML source code