Wimax standards and Security The Wimax

Location Update

An MS in idle mode updates its location in the following circumstances:

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  Paging group update: The MS updates its location when it detects a change in paging group. If the paging group identifier contained in an MOB_PAG-ADV broadcast message during the MS paging listening interval does not match the paging group to which the MS belongs, the MS determines that the paging group has changed.
  
• 
  Timer update: The MS periodically updates its location prior to the expiration of an idle mode timer.
  
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  Power down update: The MS attempts to update its location once as a part of its orderly power-down procedure. This mechanism enables a paging controller to update the MS’s exact status and to delete all information about the MS and discontinue idle mode paging control for the MS at the time of power down.
  
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  MAC hash skip threshold update: The MS updates its location when the MS MAC hash skip counter exceeds the MAC hash skip thresh- old successively. After successful location update, the BS and MS reinitialize their respective MAC hash skip counters.
  

Figure 6.12 illustrates location update. If an MS in idle mode decides to update its location, it attempts to update with a target BS. Location is updated by the exchange of RNG-REQ and REG-RSP messages. The MS sends an RNG- REQ message, which includes the ranging purpose indication of location update request and the paging controller ID. The target BS replies with an RNG-RSP message, which includes the location update response and paging group ID. If the location update is successful, the target BS notifies the paging controller of the location of the MS via the backbone, and the MS records the

Paging controller


RNG-REQ
(Location update request, paging controller ID)