work maintains the track of the MS by updating the MS location profile in a central database. If there is pending traffic for an idle MS, the MS is paged within the paging group that was last reported. It must be noted that the greater the number of base stations within a paging group, the higher the paging resources required in the network. Network operators should make tradeoffs between using resources for location update signaling versus paging over a large geographical area. As shown in Figure 4-10, the Idle State consists of two separate modes, Paging Available Mode and Paging Unavailable Mode. During Idle State, the MS may attempt power saving by switching between Paging Available and Paging Unavailable modes. The MS monitors the paging message during listening intervals. The start of the mobile station's paging listening interval is derived based on paging cycle and paging offset. Paging offset and paging cycle are defined in terms of number of superframes [2]. The BS transmits the list of PGIDs at the predetermined location within the radio frame. The PGID information should be received during mobile stations' paging listening interval. Listening Interval Paging Offset 3 Paging Offset 2 Paging Offset 3 Paging Offset 2 Paging Cycle Paging Cycle Paging Cycle Paging Offset 1.. Paging Offset 1 Paging Offset 1 M Superframes (M<N) K Superframes (M<K<N) N Superframes N Superframes N Superframes Superframe Superframe Superframe Boundary Boundary Boundary FIGURE 4-7 An illustration of paging cycle, paging offset, and listening interval concepts (example) 4.1 IEEE 802. 16m mobile station state diagrams P-PLI S-PLI P-PLI S-PLI Primary Paging Group Monitoring P-PLI S-PLI P-PLI S-PLI Secondary Paging Group Monitoring To: PAGING CYCLE PUI: Paging Unavailable Interval T1: Primary PAGING OFFSET P-PLI: Primary Paging Listening Interval T2: Secondary PAGING_OFFSET S-PLI: Secondary Paging Listening Interval FIGURE 4-8 Multiple paging group idle state operation (example) [27] Paging message is an MS notification which either