ganized to be consistent with the protocol layers, starting from the network layer and moving down to the physical layer. The overall operation of the mobile station, relay station, and base station and their corresponding state machines are described in Chapter 4. Perhaps this chapter is the most important part of the book, as far as understanding the general operation of the system is con- cerned. Chapter 5 describes the interface with the packet data network. Chapters 6 and 7 describe the medium access control layer protocols. Due to the size of content, the medium access control and physical layer chapters (Chapters 6, 7, 9 and 10) have been divided into two parts. The security aspects of the systems under consideration are described in Chapter 8. The additional functional components, algorithms, and protocols which have been introduced by the 3GPP LTE-Advanced are emphasized SO that they are not confused with the legacy components. The multi-carrier operation of the IEEE 802.16m and 3GPP LTE-Advanced are described in Chapter 11. The performance evaluation of the IEEE 802.16m and 3GPP LTE-Advanced against the IMT-Advanced requirements has been described in Chapter 12, where all the performance metrics are defined and link-level and system-level simu- lation methodologies and parameters are elaborated. The existing mobile broadband radio access systems will continue to evolve and new systems will emerge. The vision, service and system requirements for systems beyond IMT-Advanced will be defined as soon as the IMT-Advanced standardization process winds down. While it is not exactly clear what technologies will be incorporated into the design of such systems and whether the existing radio access technologies will converge into a single universal radio interface, it is envisioned that the future radio interfaces will rely on distributed antenna systems, low-power emission, distributed computing, seamless connectivity, software defined radio, cognitive radio systems, multi-resolution wireless multimedia, and coope