Section: 5.11.5 UE Radio Capability for Category M Differentiation
Content: This functionality is used by the Core Network to be able to identify traffic to/from Category M UEs for charging differentiation. The eNodeB determines whether a UE is of Category M from the UE's radio capability if UE signals one or more of the specific Category M. The eNodeB then indicates to the MME whether the UE is Category M using the "LTE-M Indication" information in S1-AP message(s) used to upload the UE Radio Capabilities to the MME. Typically this is at the same time as the eNodeB uploads the UE Radio Capability information. When the UE is of Category M, the MME receives one "LTE-M Indication" from eNB irrespective of whether the UE supports terrestrial WB-E-UTRAN or satellite WB-E-UTRAN or both and irrespective of whether the UE Radio Capability information of the UE is retrieved from terrestrial or satellite access eNB. The MME stores the "LTE-M Indication" in the MME context. If the UE context in MME contains the "LTE-M Indication" the MME indicates to the S-GW that the RAT type of the UE is one of the LTE-M RAT types in every Create Session Request message and every Modify Bearer Request message, so this is handled for charging and PCC purposes. The MME additionally takes into account whether the UE is accessing over terrestrial WB-E-UTRAN or satellite WB-E-UTRAN when determine the LTE-M RAT type. If the MME requests the SGW to pass LTE-M RAT type to the PDN GW, based on operator policy (e.g. based on roaming agreements or based on the need to pass the LTE-M RAT type information to PGW also), the MME informs the Serving GW that it is requested to relay the LTE-M RAT type to the PGW also. Otherwise, the Serving GW indicates WB-E-UTRAN RAT type to the PDN GW. In order to handle the situations of inter-MME change, the "LTE-M Indication" is sent from the source MME to the target MME as part of the MM Context information. The UE Radio Capability for Category M Differentiation is only applicable for MMEs, i.e. it is not applicable for SGSNs. Therefore, it will not be included during context transfers from and towards SGSNs.