Content for  TS 38.473  Word version:  18.2.0

The BAP Mapping Configuration Procedure is initiated by the gNB-CU to configure the DL/UL routing information and/or traffic mapping information needed for the gNB-DU. The procedure uses non-UE associated signalling.

The gNB-CU initiates the procedure by sending BAP MAPPING CONFIGURATION message to the gNB-DU. The gNB-DU replies to the gNB-CU with BAP MAPPING CONFIGURATION ACKNOWLEDGE. If BH Routing Information Added List IE is included in the BAP MAPPING CONFIGURATION message, the gNB-DU shall, if supported, store the BH routing information from this IE and use it for DL/UL traffic forwarding as specified in TS 38.340. If BH Routing Information Added List IE contains information for an existing BAP Routing ID, the gNB-DU shall, if supported, replace the previously stored routing information for this BAP Routing ID with the corresponding information in the BH Routing Information Added List IE. If BH Routing Information Removed List IE is included in the BAP MAPPING CONFIGURATION message, the gNB-DU shall, if supported, remove the BH routing information according to such IE. If the Traffic Mapping Information IE is included in the BAP MAPPING CONFIGURATION message, the gNB-DU shall, if supported, process the Traffic Mapping Information IE as follows:

• if the IP to layer2 Traffic Mapping Info IE is included, the gNB-DU shall store the mapping information contained in the IP to layer2 Traffic Mapping Info To Add IE, if present, and remove the previously stored mapping information as indicated by the IP to layer2 Traffic Mapping Info To Remove IE, if present. The gNB-DU shall use the mapping information stored for the mapping of IP traffic to layer 2, as specified in TS 38.340.
• if the BAP layer BH RLC channel Mapping Info IE is included, the gNB-DU shall store the mapping information contained in the BAP layer BH RLC channel Mapping Info To Add IE, if present, and remove the previously stored mapping information as indicated by the BAP layer BH RLC channel Mapping Info To Remove IE, if present. The gNB-DU shall use the mapping information stored when forwarding traffic on BAP sublayer, as specified in TS 38.340.

If the Buffer Size Threshold IE is included in the BAP MAPPING CONFIGURATION message, the gNB-DU shall, if supported, use it to determine the DL congestion based on the flow control feedback from child IAB-nodes as specified in TS 38.340. If BAP Header Rewriting Added List IE is included in the BAP MAPPING CONFIGURATION message, the gNB-DU shall, if supported, store the BAP header rewriting configuration from this IE, and use it as specified in TS 38.340. If BAP Header Rewriting Added List IE contains information for an existing ingress BAP Routing ID, the gNB-DU shall, if supported, replace the previously stored BAP header rewriting configuration for this ingress BAP Routing ID with the corresponding information in the BAP Header Rewriting Added List IE. If BAP Header Rewriting Removed List IE is included in the BAP MAPPING CONFIGURATION message, the gNB-DU shall, if supported, remove the BAP header rewriting configuration according to such IE. If the Re-routing Enable Indicator IE is included in the BAP MAPPING CONFIGURATION message, and the value is set as "false", the gNB-DU shall, if supported, disable the inter-donor-DU re-routing, as specified in TS 38.340. If the Re-routing Enable Indicator IE is included in the BAP MAPPING CONFIGURATION message, and the value is set as "true", the gNB-DU shall, if supported, enable the inter-donor-DU re-routing.

If the gNB-DU cannot accept the configuration, it shall respond with a BAP MAPPING CONFIGURATION FAILURE and appropriate cause value. If the BAP MAPPING CONFIGURATION FAILURE message includes the Time To Wait IE, the gNB-CU shall wait at least for the indicated time before reinitiating the BAP MAPPING CONFIGURATION message towards the same gNB-DU.

Not applicable.

The gNB-DU Resource Configuration procedure is initiated by the gNB-CU in order to configure the resource usage for a gNB-DU. The procedure uses non-UE associated signalling. In this version of the specification, this procedure is used to configure IAB resources.

The gNB-CU initiates the procedure by sending the GNB-DU RESOURCE CONFIGURATION message to gNB-DU. The gNB-DU replies to the gNB-CU with the GNB-DU RESOURCE CONFIGURATION ACKNOWLEDGE message. For each cell in the Activated Cells to Be Updated List IE of the GNB-DU RESOURCE CONFIGURATION message, the gNB-DU shall store the resource configuration contained in the IAB-DU Cell Resource Configuration-Mode-Info IE and use it when performing scheduling in compliance with TS 38.213. If the Child-Node List IE is included in the GNB-DU RESOURCE CONFIGURATION message, for each child-node indicated by the gNB-CU UE F1AP ID IE and gNB-DU UE F1AP ID IE, and for each cell served by this child node indicated by the NR CGI IE in the Child-Node Cells List IE, the gNB-DU shall store the received information and use this information for scheduling, in compliance with TS 38.213, clause 14. If the Neighbour-Node Cells List IE is included in the GNB-DU RESOURCE CONFIGURATION message, for each neighbour-node cell indicated by the NR CGI IE in the Neighbour-Node Cells List IE, the gNB-DU shall store the received information and use this information for cross-link interference management and/or semi-static resource coordination. If the Peer Parent-Node Indicator IE is included in the GNB-DU RESOURCE CONFIGURATION message and the value is set as "true", the gNB-DU shall, consider the cell indicated by the NR CGI IE is served by the peer parent node of the IAB-node indicated by the gNB-CU UE F1AP ID IE and the gNB-DU UE F1AP ID IE. If the Serving Cells List IE is included in the GNB-DU RESOURCE CONFIGURATION message, the gNB-DU shall store the received information and use this information for scheduling, in compliance with TS 38.213, clause 14.

If the gNB-DU cannot accept the configuration, it shall respond with a GNB-DU RESOURCE CONFIGURATION FAILURE and appropriate cause value. If the GNB-DU RESOURCE CONFIGURATION FAILURE message includes the Time To Wait IE, the gNB-CU shall wait at least for the indicated time before reinitiating the GNB-DU RESOURCE CONFIGURATION message towards the same gNB-DU.

Not applicable.

The purpose of the IAB TNL Address Allocation procedure is to allocate TNL addresses to be used by the IAB-node(s). This procedure uses non-UE associated signalling.

The gNB-CU initiates the procedure by sending the IAB TNL ADDRESS REQUEST message to the gNB-DU. If the IAB TNL ADDRESS REQUEST message contains the IAB IPv4 Addresses Requested IE, the gNB-DU shall allocate the individual TNL address(es) accordingly and include these IPv4 address(es) in the IAB TNL ADDRESS RESPONSE message. If the IAB TNL ADDRESS REQUEST message contains the IAB IPv6 Request Type IE, the gNB-DU shall allocate the individual IPv6 address(es) or IPv6 address prefix(es) accordingly and include these IPv6 address(es) or IPv6 address prefix(es) in the IAB TNL ADDRESS RESPONSE message. If the IAB TNL ADDRESS REQUEST message contains the IAB TNL Addresses To Remove List IE, the gNB-DU shall consider that the TNL address(es) and/or TNL address prefix(es) therein are no longer used by the IAB-node(s). In addition, if the IAB TNL ADDRESS REQUEST message only contains the IAB TNL Addresses to Remove List IE, the gNB-CU shall ignore the IAB Allocated TNL Address List IE in the IAB TNL ADDRESS RESPONSE message. If the IAB TNL ADDRESS RESPONSE message contains the IAB TNL Address Usage IE in the IAB Allocated TNL Address Item IE, the gNB-CU shall consider the indicated TNL address usage when allocating a TNL address to an IAB-node. Otherwise, the gNB-CU shall consider that the TNL address can be used for all traffic when allocating the TNL address to an IAB-node. If the IAB TNL Address Exception IE is included in the IAB TNL ADDRESS REQUEST message and the gNB-DU is an IAB-donor-DU, the gNB-DU shall, if supported, consider the IP address(es) therein as exempt from TNL address filtering, and forward the packets with the address(es) indicated by this IE, as specified in TS 38.401.

If the gNB-DU cannot accept the request, it shall respond with an IAB TNL ADDRESS FAILURE and appropriate cause value. If the IAB TNL ADDRESS FAILURE message includes the Time To Wait IE, the gNB-CU shall wait at least for the indicated time before reinitiating the IAB TNL ADDRESS REQUEST message towards the same gNB-DU.

Not applicable.

The purpose of the IAB UP Configuration Update procedure is to update the UP parameters including UL mapping configuration and the UL/DL UP TNL information between IAB-donor-CU and IAB-node. This procedure uses non-UE associated signalling.

The gNB-CU initiates the procedure by sending the IAB UP CONFIGURATION UPDATE REQUEST message to the gNB-DU. The gNB-DU replies to the gNB-CU with the IAB UP CONFIGURATION UPDATE RESPONSE message. If the UL UP TNL Information to Update List IE is included in the IAB UP CONFIGURATION UPDATE REQUEST message, the gNB-DU shall perform the mapping according to the new received BH Information IE for each F1-U GTP tunnel indicated by the UL UP TNL Information IE. If the New UL UP TNL Information IE is included in UL UP TNL Information to Update List IE, the gNB-DU shall use it to replace the information of UL F1-U GTP tunnel indicated by the UL UP TNL Information IE. If the UL UP TNL Address to Update List IE is included in the IAB UP CONFIGURATION UPDATE REQUEST message, the gNB-DU shall replace the old TNL address with the new TNL address for all the maintained UL F1-U GTP tunnels corresponding to the old TNL address. If the DL UP TNL Address to Update List IE is included in the IAB UP CONFIGURATION UPDATE RESPONSE message, the gNB-CU shall replace the old TNL address with the new TNL address for all the maintained DL F1-U GTP tunnels corresponding to the old TNL address.

If the gNB-DU receives an IAB UP CONFIGURATION UPDATE REQUEST message and cannot perform any update accordingly, it shall consider the update procedure as failed and respond with an IAB UP CONFIGURATION UPDATE FAILURE message and an appropriate cause value. If the IAB UP CONFIGURATION UPDATE FAILURE message includes the Time To Wait IE, the gNB-CU shall wait at least for the indicated time before reinitiating the IAB UP CONFIGURATION UPDATE REQUEST message towards the same gNB-DU.

Not applicable.

This procedure is initiated by gNB-CU to send the Access and Mobility related Information to gNB-DU. The procedure uses non-UE-associated signalling.

The Access and Mobility Indication procedure is initiated by ACCESS AND MOBILITY INDICATION message sent from gNB-CU to gNB-DU. If the ACCESS AND MOBILITY INDICATION message contains the RACH Report Information List IE the gNB-DU shall take it into account for optimisation of RACH access procedures. If the ACCESS AND MOBILITY INDICATION message contains the RLF Report Information List IE the gNB-DU shall take it into account for optimisation of mobility parameters. If the ACCESS AND MOBILITY INDICATION message contains the Successful HO Report Information List IE the gNB-DU may take it into account for optimisation of mobility parameters.

Not applicable.

The purpose of the Reference Time Information Reporting Control procedure is to command the gNB-DU to send the requested accurate reference time information to the gNB-CU. The procedure uses non-UE associated signalling.

The gNB-CU initiates the procedure by sending REFERENCE TIME INFORMATION REPORTING CONTROL message to the gNB-DU. Upon reception of the REFERENCE TIME INFORMATION REPORTING CONTROL message, the gNB-DU shall, if supported, perform the requested reference time information reporting action. The Report Type IE indicates to the gNB-DU whether:

• to report on demand;
• to report periodic, with a frequency as specified by the Report Periodicity IE;
• to stop periodic reporting.

Not applicable.

The purpose of the Reference Time Information Report procedure is to report the accurate reference time information from the gNB-DU to the gNB-CU. The procedure uses non-UE associated signalling.

The gNB-DU initiates the procedure by sending a REFERENCE TIME INFORMATION REPORT message to the gNB-CU. The REFERENCE TIME INFORMATION REPORT message may be used as a response to the REFERENCE TIME INFORMATION REPORTING CONTROL message.

Not applicable.