第7章移动主叫流程.doc

第7章移动主叫流程... 7-1
概述.. 7-1
正常流程.. 7-1
Mobile originating call establishment without OACSU (early assignment)7-2
Mobile originating call establishment with OACSU (late assignment)7-5
Mobile originating call establishment with OACSU (Very early assignment)7-7
异常流程.. 7-8
随即接入、立即指配异常流程.. 7-8
MSC未下发Assignment request 而是直接下发Disconnect拆除呼叫.. 7-9
指配异常流程.. 7-9
掉话造成的异常流程.. 7-10
用户挂机造成的异常流程.. 7-10
MSC清除造成的异常流程.. 7-11
第7章  移动主叫流程
  概述
移动主叫(始呼)包括MS拨打MS、MS拨打固定电话,不包括短消息始发。
  正常流程
移动主叫正常流程,根据指配流程类别(Early Assignment、Late Assignment、Very Early Assignment)分成三类。其中Early Assignment、Late Assignment流程的选择是MSC决定的;Very Early Assignment流程是由BSS根据无线资源等情况决定的。
  Mobile originating call establishment without OACSU (early assignment)
1. 信令流程
                                                                                                       图7-1 Mobile originating call establishment without OACSU (early assignment)
(1)      MS在空中接口的接入信道上(RACH上)向BTS发送Channel Request(该消息内含接入原因值为MOC。但是该消息中的原因值并不完全准确,因为MS在做移动主叫和IMSI分离时都填的是该原因值。);
(2)      BTS向BSC发送Channel Required消息;
(3)      BSC收到Channel Required后,分配信令信道,向BTS发送Channel Activation;
(4)      BTS收到Channel Activation后,如果信道类型正确,则在指定信道上开功率放大器,上行开始接收信息,并向BSC发送Channel Activation Acknowledge;
(5)      BSC通过BTS向MS发送Immediate mand,Um接口中该消息在AGCH上发送;
(6)      H上发SABM帧接入;
(7)      H上回UA帧进行确认;
(8)      BTS向BSC发Establishment Indication(该消息中准确的反映了MS的接入原因,例如此时对移动主叫和IMSI分离填的是不同的原因值。),内含CM Service Request消息内容;
(9)      P链接,向MSC发送CM Service Request;
(10)  MSC向BSC回链接确认消息;
(11)  MSC发CM Service Accepted,H上发送;
(12)  H上发Setup;
(13)  MSC向主叫MS发Call Proceeding,H上发送;
(14)  MSC向BSC发Assignment Request,在该消息中,分配了A接口CIC;
(15)  BSC分配话音信道,向BTS发送Channel Activation;
(16)  BTS收到Channel Activation后,如果信道类型正确,则在指定信道上开功率放大器,上行开始接收信息,并向BSC发送Channel Activation Acknowledge;
(17)  mand,H上发送;
(18)  H上发SABM帧来接入;
(19)  H上回UA帧进行确认;
(20)  BTS向BSC发Establishment Indication;
(21)  MS在接入话音信道后