6.14 MBMS model (Rel-6 or later)

34.123-33GPPPart 3: Abstract test suite (ATS)TSUser Equipment (UE) conformance specification

The MBMS test model illustrates the relationship between various channels, from logical channel to physical channels applied to the MBMS test. The MBMS-dedicated stand-alone SCCPCH, MICH, MAC-m, MCCH, MSCH and MTCH are configured by the TTCN.

During softcombining, MTCHs which have the same logical channel identity but in different cells are connected to the same UM RLC.

Figure 6.14: The model of MBMS testing

6.14.1 MBMS RLC test model

6.14.1.1 RLC test model for MTCH test

For RLC tests on MTCH a TR radio bearer is configured (tsc_RB_MTCH_RLC_TR). Similar to the UM mode, data scheduling is applied at the test.

When reconfiguring back from TR to UM mode, MAC is reconfigured and RLC is released/reconfigured again. It implies that UM will restart with sequence number 0; the corresponding RLC state variables are set to 0. Sequence numbers between the one used in the last PDU sent in TR mode and the sequence number 0 are considered by the UE as lost sequence numbers and shall have no impact on the test in the UM mode.

6.14.1.2 RLC test model for MCCH test

For RLC tests the MCCH critical messages can be sent as a DL sequence of PER encoded UM RLC PDUs in RLC TR mode. To achieve this, the normal UM radio bearer on MCCH is replaced with a TR radio bearer configured with a negative RB Id (tsc_RB_MCCH_RLC_TR). This is achieved by reconfiguring MAC and releasing the existing RLC UM entity /configuring a new TR RLC entity. It results in only one RLC entity being able to map on MCCH at the test.

It is assumed that the necessary MCCH data are completely sent out before the reconfiguration procedure mentioned above takes place.

When changing from UM to TR the care should be taken on the sequence numbers used in the RLC PDUs. That can be achieved by querying the SN from SS with CRLC_SequenceNumber_REQ. When changing back to UM the RLC may continue with the sequence number following the last sequence number used before changing to TR mode. That implies, the UM part of the RLC in SS does not need to take care of the UM PDUs sent in TR mode. The UE will regard it as PDU lost.

To support re-synchronization the ‘specialLI’ of the RLC_UM_CriticalMCCHMsg_REQ following TR mode can be set to TRUE.