The following subclauses specify the procedures for unicast resource management for vertical application layer. The NRM server sets up bearers and may need to modify the bearers for an already established VAL service communication.
Characteristics that may need to be modified include:
activation and deactivation of the bearer;
modification of the QoS characteristics of the bearer (e.g. bearer priority adjustment); and
modification of GBR due to application requirement
Vertical application layer specific pre-requisites and resultant behaviour by functional entities in performing these procedures are specified in the respective vertical application layer TS (e.g. for V2X application layer, see TS 23.286).
Unicast resource management is supported with PCC interactions with SIP core and PCC interactions with NRM server. The PCC procedures for EPS are specified in TS 23.203 and the PCC procedures for 5GS are specified in TS 23.503.
The procedure defined in this subclause specifies how network resources are requested at VAL service communication establishment. If concurrent sessions are used the NRM server may utilize the capability of resource sharing specified for underlying network policy and charging functions. The request for resources includes application type, bandwidth, priority, application identifier and resource sharing information.
The procedure is generic to any type of session establishment that requires requests for network resources.
Procedures in Figure 14.3.3.2.1.2-1 are the signalling procedures for the requesting resource at session establishment.
Pre-condition:
The VAL client has requested VAL service communication with the VAL server.
To modify unicast bearers, the NRM server shall send a resource modification request containing the parameters to be modified for the UE.
Possible scenarios when this procedure may be used are:
Modify the allocation and retention priority for unicast resources;
Release and resume resources in-between VAL service communications; or
Release and resume resources when a UE is able to receive the VAL service communications over multicast transmission