Section: 4.3.28 Restriction of use of Enhanced Coverage
Content: Support of UEs in Enhanced Coverage is specified in TS 36.300[ Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 ]  [5]. The usage of Enhanced Coverage may require use of extensive resources (e.g. radio and signalling resources) from the network. This feature enables the operator to prevent specific subscribers from using Enhanced Coverage. The UE indicates its capability of support for restriction of use of Enhanced Coverage in Attach and TAU procedure for the RAT it is camping on to the MME. MME receives Enhanced Coverage Restricted parameter from the HSS. This parameter is kept as part of subscription data in the HSS and specifies per PLMN whether the enhanced coverage functionality is restricted or not for the UE. For roaming UEs, if HSS doesn't provide any Enhanced Coverage Restricted parameter or the provided Enhanced Coverage Restricted parameter is in conflict with the roaming agreement, the MME uses default Enhanced Coverage Restricted parameter locally configured in the VPLMN based on the roaming agreement with the subscriber's HPLMN. The UE shall assume that restriction for use of Enhanced Coverage is same in the equivalent PLMNs. If the UE includes the support for restriction of use of Enhanced Coverage, MME sends Enhanced Coverage Restricted parameter to the UE in the Attach/TAU Accept message. The UE shall use the value of Enhanced Coverage Restricted parameter to determine if enhanced coverage feature is restricted or not. NOTE: How this parameter is used by UE at AS layer is defined in the RAN specification. The UE assumes Enhanced Coverage is allowed unless explicitly restricted by the network for a PLMN. NB-IoT cells also broadcast the support of restriction of use of Enhanced Coverage as defined in TS 36.331[ Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification ]  [37]). If the MME has sent the Enhanced Coverage Restricted parameter to the UE, the MME provides an Enhanced Coverage Restricted parameter to the eNodeB via S1 signalling during paging, and whenever the UE context is established in RAN, e.g. during service request procedure, attach procedure, and TAU procedure.