9 Policy and charging control

26.2373GPPIP Multimedia Subsystem (IMS) based Packet Switch Streaming (PSS) and Multimedia Broadcast/Multicast Service (MBMS) User ServiceProtocolsRelease 17TS

9.1 General

For the purpose of the present specification, the policy and charging control (PCC) is according to 3GPP TS 23.203 [12]. This clause is relevant when PCC is present. However, IMS based PSS and MBMS User Services can be realized without PCC. When PCC is not present, the UE is responsible for allocation of the resources based on Session Description information.

Service subscription control is performed by the SCF at registration and at PSS and MBMS session initiation.

QoS control is different for PSS and MBMS User Services.

9.2 QoS control

The P-CSCF is used as the Application Function in the PCC architecture. The PCRF decides how policy control of the QoS is performed for IMS initiated and controlled PSS and MBMS User Service.

In case of PSS, the PCRF shall use the SDP received from the P-CSCF during session establishment to calculate the proper QoS authorization. The way the QoS is enforced in this architecture is defined in 3GPP TS 23.203 [12].

In case of MBMS, the PCRF shall not initiate the establishment of a specific bearer.

Figure 20: PSS QoS Policy Control

NOTE: The sequence shown is simplified and does not e.g. show session progress messages and the ACK message from the UE in response to the reception of 200 OK.

The PSS case of QoS control is shown on figure 20. The appropriate existing bearers are used or new required bearers are allocated. Network initiated bearer control and UE initiated bearer control are possible. When receiving the final SDP, the UE shall initiate the establishment of the required bearers unless a network initiated bearer allocation procedure is already ongoing, or the UE has been configured to use network initiated resource control.