tence; Data Forwarding; Interference Management; Inter-BS Coordination. The data-plane portion of the MAC sub-layer is responsible for the following functions: MAC SDU Fragmentation/Packing; MAC PDU Formation. To draw an analogy between the IEEE 802.16m and 3GPP LTE Layer 2 protocols, one must note that the Layer 2 functions of the latter include MAC and RLC sub-layers and the RRC sub-layer is considered Layer 3. The IEEE 802.16m RRCM functional group corresponds to RRC sub-layer in 3GPP LTE, and the IEEE 802.16n MAC sub-layer is analogous to a combination of 3GPP LTE MAC and RLC sub-layers. The 3GPP LTE MAC and RLC sub-layers will be described in this chapter to enable the reader to understand the similarities and differences of IEEE 802.16m and 3GPP LTE/LTE- Advanced demonstrating correspondences between the two protocol sets [3,9]. The IEEE 802.16m MAC is connection-oriented. For the purpose of mapping services to varying levels of QoS at mobile stations, all data communications are manifested in the form of transport connections. Service flows may be provisioned when an MS performs network entry. Following MS registration with the serving BS, transport connections are established and associated with the service flows (one connection per service flow) to provide a reference for requesting bandwidth. Furthermore, new transport connections may be established when a user's service needs to change. A transport connection defines the mapping between peer convergence sub-layers that utilize the MAC and a service flow. The service flow defines the QoS parameters for the PDUs that are exchanged on the connection. The concept of service flow mapping to a transport connection is essential to the operation of the MAC CPS protocols. Service flows provide a mechanism for UL and DL QoS management. In particular, they are an integral part of the bandwidth allocation process. An MS requests UL bandwidth on a per connection basis by implicitly identifying the service flow. The bandwidth is granted by the serving BS to an MS as