rgence Sublayer Service-Specific Convergence Sublayers MAC SAP MAC Common Part Sublayer (MAC CPS) Management Entity MAC Common Part Sublayer Security Sublayer Security Sublayer PHY SAP Physical Layer (PHY) Management Entity Management Plane Data/Control Plane Figure 4.2 IEEE 802.16-2004 reference model. Reproduced with permission from C 2004 IEEE [2] a data point to the operators in their vendor selection for WiMAX. The MAC consists of three sublayers namely service-specific convergence sublayer, MAC common part sublayer and MAC security sublayer. The specifications also define three key network configurations for WiMAX systems, namely point- to-point (PTP), point-to multipoint (PMP) and mesh topologies [1]. Point-to-Point (PTP): The PTP topology consists of one transmitting and one receiving entity (radio). Since a PTP connection is not shared with multiple users, it delivers more bandwidth to the end-user. It provides an alternative to T1/E1 backhauling solutions. Point to Multipoint (PMP): The PMP networks allow a single source to serve multiple end users. PTP systems are used more by residential customers than business users because of less stringent bandwidth requirements. Mesh Topology: In mesh topology each node has redundant connections to other nodes in the network. The mesh topology could be partial or full; in a partial mesh, each node is connected to at least two other nodes while in full mesh each node is connected to every other node. A partial mesh in comparison to a full mesh offers less redundancy and greater economics. One of the key aspects of a mesh network is the routing functionality of its nodes which allows them to take the best route in communication with other nodes or networks. The failure of a node results in automatic re-routing to bypass the node failure. The MAC as defined in the standard consists of three sublayers: service-specific convergence sublayer (CS), MAC common part sublayer (MAC CPS) and security sublayer [2,3,5]. 4.2.1.1 Service-specific Convergence Sublayer The service 