protocols have been simplified to reduce the network entry/re-entry latency, and to enable fast cell selection or reselection. As an example, the location of the system configuration information has been fixed in IEEE 2.16m standard SO that on successful downlink synchronization, the superframe headers containing the system configuration information can be located and acquired. This would enable the MS to make decisions for attachment to the BS without acquiring and decoding the legacy downlink control channel and the downlink and uplink channel descriptors that were transmitted as MAC management messages in the legacy system. This modification would further result in power saving in the MS, due to shortening and simplification of the initialization procedure. In the next sections, the detailed procedures corresponding to each state are described. Although both normal and fast network re-entry processes are shown as transition from the Idle State to the Access State in Figure 4-1, there are differences that distinguish the two processes which 4.1 IEEE 802. 16m mobile station state diagrams Sleep Request/Sleep. Network Re-entry Process Response Messages Active Mode/Scanning Connected Idle State Sleep Mode State (Normal Operation) Deregistration Request/ Traffic Indication/Bandwidth Deregistration Command Request Messages FIGURE 4-2 Steady-state behavior of IEEE 802.16 mobile stations [1] will be discussed in the next sections. The steady-state behavior of IEEE 802.16 mobile stations is shown in Figure 4-2. The latter figure applies to both IEEE 802.16m [2] and IEEE 802.16-2009 standard [1] compliant mobile stations, although the details of procedures might be different in the two systems. Once the MS completes the initial network entry, it starts normal operation in the Active Mode while periodically scanning the neighboring base stations for handover. It may transition to the Idle State through deregistration messages or exit the Idle State and enter the Active Mode by per- forming network re-entry procedures. Th