Content for  TS 23.280  Word version:  19.3.1

The MC service server is an instantiation of a GCS AS. For the MC service server to know the status of the MBMS bearer, and thus know the networks ability to deliver the service, it is required that the network provides MBMS bearer event notifications to the MC service server. The different events notified to the MC service server include the MBMS bearer start result (e.g. when the first cell successfully allocated MBMS resources), including information if any cells fail to allocate MBMS resources to a specific MBMS bearer, the current status of the MBMS bearer, MBMS bearer suspension/resume or overload scenarios.

The procedure in Figure 10.7.3.10.2-1 shows notification information flows from MC service server to BM-SC.

Application layer FEC can be used to recover the packet losses when delivering a MC service over MBMS, to reach its required level of QoS. Support of FEC is optional for the MC service servers and MC service clients Adding FEC introduces an extra latency in the end to end media transport. This extra latency is bounded to fulfil the low latency requirements for mission critical services. FEC can be applied by the BM-SC if required by the MC service server (subclause 10.7.3.11.2), or directly by the MC service server (subclause 10.7.3.11.3). FEC is decoded by the MC service client. Either method is independent of the other. The MC service server may consider the listening status reports from previous MBMS bearer quality detection procedures (subclause 10.7.3.6) to adjust the FEC parameters when delivering over a new MBMS bearer.

In this procedure, depicted in Figure 10.7.3.11.2-1, the MC service server asks the BM-SC to apply FEC to a set of medias, transported by a MBMS bearer, using the Setup FEC request. This procedure can be applied when using pre-established MBMS bearers (10.7.3.1) or dynamic MBMS bearers (10.7.3.2). Pre-condition:

1. The MC service server has already activated a MBMS Bearer, with the MBMS Bearer request specified in TS 23.468.

In this procedure, depicted in Figure 10.7.3.11.3-1, FEC encoding is performed by the MC service server. The MC service server includes the FEC information within the MBMS bearer announcement. The FEC decoding is performed by the MC service client.

Support of ROHC over MBMS is optional for the MC service servers and MC service clients. If header compression and FEC are both applied to a communication over MBMS, the header compression shall be performed after the FEC encoding. These procedures can be applied when using pre-established MBMS bearers (see clause 10.7.3.1) or dynamic MBMS bearers (see clause 10.7.3.2).

In this procedure, depicted in Figure 10.7.3.12.2-1, header compression is performed by the MC service server. The MC service server includes the ROHC information within the MBMS bearer announcement. The header decompression is performed by the MC service client.

In this procedure, depicted in Figure 10.7.3.12.3-1, the MC service server asks the BM-SC to compress headers for a set of medias, transported by a MBMS bearer, using the Setup ROHC request. Pre-condition:

1. The MC service server has already activated a MBMS Bearer, with the MBMS Bearer request specified in TS 23.468.