E-MBMS Gateway and the eNodeBs is introduced to ensure that the same content is sent over the air from all the eNodeBs. As shown in Figure 3.34, eBM-SC (Broadcast Multicast Service Center) is the source of the MBMS traffic, and the E-MBMS gateway is responsible for distributing the traffic to the different eNodeBs of the MBSFN area. IP multicast may be used for distributing the traffic Next Generation Mobile Communications Ecosystem BM-SC Gateway packet packet Figure 3.34 The overall u-plane architecture of the MBMS content synchronization. Reproduced with permission from C 2009 3GPP [14] Note: SYNC = Protocol to synchronize data used to generate a certain radio frame; TNL = Transport Network Layer; M1 Interface = MBMS-GW and eNodeB from the E-MBMS gateway to the different eNBs. 3GPP has defined a control plane entity, known as the MBMS Coordination Entity (MCE) that ensures that the same resource block is allocated for a given service across all the eNodeBs of a given MBSFN area. It is the task of the MCE to ensure that the RLC/MAC layers at the eNodeBs are appropriately configured for MBSFN operation. 3GPP has currently assumed that header compression for MBMS services will be performed by the E-MBMS gateway [28]. 3.9.8 One Voice The 'One Voice' initiative of the leading service providers and manufacturers defines the use of IMS to support VoIP over LTE. The specification V1.0.0 [29] defines a 3GPP compliant voice over IMS profile by listing a number of E-UTRAN, EPC, IMS core, and UE features which are considered essential to launch interoperable IMS based voice. The profile is recommended only for LTE standalone network without relying on legacy circuit and packet switched infrastructure. It has been designed to support roaming as well. Voice over LTE will use guaranteed bit rate (GBR) as non GBR are not suitable for IMS based voice services. The UE and network will support both IPv4 and IPv6. The UE and network will also support SMS-over-IP as specified in 3GPP TS 24.341. The V1.0.0 specification lists a numb