mto base station, and relay station) through use of state diagrams and call flows. An attempt has been made to characterize the behavior of IEEE 802. 16m systems in various operating conditions such as system entry/re-entry, cell selection/reselection, intra/inter-radio access network handover, power management, and inactivity intervals. This chapter describes how the IEEE 802.16m system entities operate and what procedures or protocols are involved, without going through the implementation details of each function or protocol. The detailed algorithmic description of each function and protocol will be provided in following chapters. Several scattered call flows and state diagrams were used in reference [1] to demonstrate the behavior of the legacy mobile and base stations, making it difficult to coherently understand the system behavior. The IEEE 802.16 standards have not generally been developed with a system-minded view; rather, they specify components and building blocks that can be integrated to build a working and performing system. An example is the mobile WiMAX profiles where a specific set of IEEE 802.16-2009 standard features (one out of many possible configurations) were selected to form a mobile broadband wireless access system. Detailed IEEE 802.16m entities' state transition diagrams comprising states, constituent functions, and protocols within each state, and inter-state transition paths conditioned to certain events would help the understanding and implementation of the standards specification [2-5]. It further helps to understand the behavior of the system without struggling with the distracting details of each constituent function. State diagrams are used to describe the behavior of a system. They can describe possible states of a system and transitions between them as certain events occur. The system described by a state diagram must be composed of a finite number of states. However, in some cases, the state diagram may represent a reasonable abstraction of the system. There are many forms of s