e MS. The MS may transit from Active Mode to Sleep Mode during sleep intervals (with The access is not designated as an independent state in the legacy standard, rather it is considered as a set of messages that are exchanged between the mobile station and the base station [1]. However, we categorize those messages and procedures as Access State in this book. The Access State can be considered as a transient state. 4.1 IEEE 802.16m mobile station state diagrams Paging Available Mode Access State Connected State Initialization State Paging Unavailable Power Down Power On/Off Normal Network Re-Entry/Fast Network Re-Entry Initialization State Access State* Connected State Idle State From Access State, Connected State, or Idle State Scanning and DL Synchronization From Initialization (Preamble Detection) Sleep mode State or Idle State Ranging and UL Sleep Listening synchronization Interval Interval To Initialization Broadcast Channel To Access State State Basic Capability Acquisition Negotiation Active Mode Cell Selection From Access Decision To Idle State State MS Authentication, Authorization & Key Exchange To Initialization State Scanning Mode Registration with Serving BS To Connected Initial Service Flow State Establishment FIGURE 4-1 IEEE 802. 16m mobile station state transition diagram [3] CHAPTER 4 IEEE 802. 16m System Operation and State Diagrams intermittent DL/UL traffic) or to Idle State (when it has no DL/UL traffic and following deregistration with the BS) in order to conserve power. Sleep Mode: this mode is intended to minimize MS power usage and decrease usage of serving BS radio resources by pre-negotiated periods of absence from the serving BS air interface while connected to the BS. The MS in Active Mode transitions to Sleep Mode through Sleep Mode MAC management messages. The MS does not transmit and receive any information to/from its serving BS during the sleep interval. A traffic indication message from the serving BS can trigger an MS in the Sleep Mode to transit to Active Mode. Scanning Mode: 