9-GSM信令流程介绍.ppt

* SETUP : to indicate a mobile Originating Call establishment (contains the call number) Progress : from the Network to the MS to indicate the progress of a call Call Proceeding : send by the network to the calling MS to indicate that the requested call establishment information has been receivedand no more call establishment will be accepted Alerting : to indicate the called user alerting has been initiated Connect : indicate the call acceptance by the called user Connect Acknowledge : to acknowledge the offered connection * * * Three Location Updating tye : Normal Location updating : used to update the regeistration of the actual LA of a MS in the Network Periodic Location Updating : to notifiy periodically the availability of the mobile in the network. This procedure is controlled by a timer (T3212) in the MS. The timer is stopped and reset to 0 when : LU accept or Reject message is received, MS has respond to a paging, MS is deactivated. IMSI Attach : to activate a MS in the Network If T3210 expires, then T3211 starts. When T3211 reaches 0, the location update procedure is restarted. * * The MS receives a Channel Release : the MS instruct the LAPDm function to perform a dsiconnection of the LAPDm and start T3110. The radio link failure algorithm in the MS is trigerred by the BSS when it stops the sending of SACCH frames to the MS. SACHH frames should be stopped for a period of T3109 for the algorithm in the MS to detect a radio link failure condition. The BSC initiate by sending the DEACTIVATE SACCH to the BTS. BTS intiated release : when LAPD failure or OM intervention. In both case, the BTS ensure that the TRX and MS are released and send an ERROR REPORT to the BSC. * C′hannel Release : cause is included (Normal Release, Abnormal Release (Unspecified, Channel Unacceptable, Timer Expiry, No activity on the Radio Path)). Disconnect : when the MS doesnt receive any SACCH message, the MS steal some TCH for Signalling (FACCH). T3111 : this timer allows