Section: 5.3.14 UE Radio Capability Match Request
Content: If the MME, e.g. based on SRVCC capability in NAS, UE Usage Type or local policy, requires more information on the UE radio capabilities support to be able to set the IMS voice over PS Session Supported Indication (see clause 4.3.5.8), then the MME may send a UE Radio Capability Match Request message to the eNodeB. This procedure is typically used during the Initial Attach procedure, during Tracking Area Update procedure for the "first TAU following GERAN/UTRAN Attach" or for "UE radio capability update" or when MME has not received the Voice Support Match Indicator (as part of the MM Context). Figure 5.3.14-1: UE Radio Capability Match Request 1 The MME indicates whether the MME wants to receive Voice support match indicator. The MME may include the UE Radio Capability information that it has previously received from the eNodeB via a S1-AP UE CAPABILITY INFO INDICATION as described in clause 5.11.2. 2. Upon receiving a UE Radio Capability Match Request from the MME, if the eNodeB has not already received the UE radio capabilities from the UE or from MME in step 1, the eNodeB requests the UE to upload the UE radio capability information by sending the RRC UE Capability Enquiry. 3. The UE provides the eNodeB with its UE radio capabilities sending the RRC UE Capability Information. 4. The eNodeB checks whether the UE radio capabilities are compatible with the network configuration for ensuring voice service continuity of voice calls initiated in IMS. For determining the appropriate UE Radio Capability Match Response, the eNodeB is configured by the operator to check whether the UE supports certain capabilities required for Voice continuity of voice calls using IMS PS. In a shared network, the eNodeB keeps a configuration separately per PLMN. NOTE 1: What checks to perform depends on network configuration, i.e. following are some examples of UE capabilities to be taken into account: - the SRVCC, and UTRAN/E-UTRAN Voice over PS capabilities; - the Radio capabilities for UTRAN/E-UTRAN FDD and/or TDD; and/or - the support of UTRAN/E-UTRAN frequency bands. NOTE 2: The network configuration considered in the decision for the Voice Support Match Indicator is homogenous within a certain area (e.g. MME Pool Area) in order to guarantee that the Voice Support Match Indicator from the eNodeB is valid within such area. The eNodeB provides a Voice Support Match Indicator to the MME to indicate whether the UE capabilities and networks configuration are compatible for ensuring voice service continuity of voice calls initiated in IMS. The MME stores the received Voice support match indicator in the MM Context and uses it as an input for setting the IMS voice over PS Session Supported Indication. 5. If eNodeB requested radio capabilities from UE in step 2 and 3, eNodeB also sends the UE radio capabilities to the MME using the S1-AP UE CAPABILITY INFO INDICATION. The MME stores the UE radio capabilities without interpreting them for further provision to the eNodeB in cases described in clause 5.11.2. NOTE 3: Steps 4 and 5 may be received by the MME in any order.