Praise for Fundamentals of WiMAX

308 Chapter 9 • MAC Layer of WiMAXHigher LayerMAC Convergence Sublayer(header suppression and SFID and DIC identification)MAC Common Part Sublayer(assembly of MAC PDUs, ARQ scheduling, MAC management)DataSignaling(MAC management)MAC Security Sublayer(encryption)Figure 9.1 The WiMAX MAC layerPHYThe MAC layer of WiMAX, as shown in Figure 9.1, is divided into three distinct components:the service-specific convergence sublayer (CS), the common-part sublayer, and the securitysublayer. The CS, which is the interface between the MAC layer and layer 3 of the network,receives data packets from the higher layer. These higher-layer packets are also known as MACservice data units (SDU). The CS is responsible for performing all operations that are dependenton the nature of the higher-layer protocol, such as header compression and address mapping.The CS can be viewed as an adaptation layer that masks the higher-layer protocol and itsrequirements from the rest of the MAC and PHY layers of a WiMAX network.The common-part sublayer of the MAC layer performs all the packet operations that are independentof the higher layers, such as fragmentation and concatenation of SDUs into MAC PDUs,transmission of MAC PDUs, QoS control, and ARQ. The security sublayer is responsible forencryption, authorization, and proper exchange of encryption keys between the BS and the MS.In this chapter, we first describe the CS and its various functions. Next, we describe theMAC common-part sublayer, the construction of MAC PDUs, bandwidth allocation process,QoS control, and network-entry procedures. We then turn to the mobility-management andpower-saving features of the WiMAX MAC layer.