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1、呼叫处理流程及网络优化,内容,第一部分 呼叫流程 第二部分 常规掉话、接入失败及掉话分析。,cdma呼叫过程,第一部分,CDMA 呼叫处理,Acquisition of the CDMA System Idle Mode Handoff Registration Termination Origination End of a Call Handoff,手机是怎么工作的?,Acquisition of the CDMA System,CDMA 呼叫过程,手机找到一个频率,手机发现最强的导频信号, 读取同步信道信息,配置信息,读完同步信息后，手机开始读寻呼信道消息，并开始不停监测该信道。 在通话
2、前，手机必须收集到完整的配置信息。 配置信息每 1.28 seconds会重复。 有新的消息手机会更新，如没有600S手机也会更新一次,手机到寻呼信道获得配置信息,2个重要的配置信息,4个另外的配置信息,Idle 模式下的切换,CDMA 呼叫流程,Idle 模式下的切换,Idle模式下总是解调最强信号。 手机不停搜索临区的导频。 如果手机发现更好的信号，就切换上去，基站并不知道。,Idle 模式下的手机行为,手机在接入信道的操作,1个寻呼信道对应32个接入信道. 接入信道在开环模式下工作! 手机探针工作如下： If “probe” not acknowledged by BTS within
3、ACC_TMO (400 mS.), phone will wait a random time (200 mS) then probe again, stronger by PI db. There can be 15 max. (typ. 5) probes in a sequence and 15 max. (typ. 2) sequences in an access attempt most attempts succeed on first probe!,登记,CDMA 呼叫处理过程,登记,登记就是空闲模式下的手机让系统知道它在等待呼入电话。 this allows the sys
4、tem to inform the mobiles home switch of the mobiles current location, so that incoming calls can be delivered registration also allows the system to intelligently page the mobile only in the area where the mobile is currently located, thereby eliminating useless congestion on the paging channels in
5、 other areas of the system There are many different conditions that could trigger an obligation for the mobile to register there are flags in the System Parameters Message which tell the mobile when it must register on the current system,一个登记实例,The System Parameters Message tells all mobiles when th
6、ey should register. This mobile notices that it is obligated to register, so it transmits a Registration Message.,The base station confirms that the mobiles registration message was received. Were officially registered!,起呼,CDMA 呼叫处理流程,手机起呼,手机用户按 SEND键. 手机发射 Origination Message 在接入信道上. 系统在寻呼信道上确认接受到该
7、消息. 系统为呼叫准备资源. 基站在寻呼信道上发Channel Assignment Message. 手机和基站在业务信道关注相互确认消息。. 呼叫建立完成.,手机起呼,The mobile sends an origination message on the access channel.,The base station confirms that the origination message was received.,The base station sends a Channel Assignment Message and the mobile goes to the tra
8、ffic channel.,业务信道确认,连接完成,Now the switch completes the audio circuit and the two callers can talk!,被叫,CDMA 呼叫处理过程,一个实际的来电呼叫,The system pages the mobile, 615-330-0644.,The base station confirms that the mobiles page response was received. Now the mobile is waiting for channel assignment, expecting a
9、response within 12 seconds.,The mobile responds to the page.,信道分配和业务信道确认,Only about 400 ms. after the base station acknowledgment order, the mobile receives the channel assignment message.,The base station is already sending blank frames on the forward channel,using the assigned Walsh code.,The mobi
10、le sees at least two good blank frames in a row on the forward channel, and concludes this is the right traffic channel. It sends a preamble of two blank frames of its own on the reverse traffic channel.,The base station acknowledges receiving the mobiles preamble.,The mobile station acknowledges th
11、e base stations acknowledgment. Everybody is ready!,呼叫建立完成,Now that both sides have arrived on the traffic channel, the base station proposes that the requested call actually begin.,The mobile agrees and says its ready to play.,The base station orders the mobile to ring, and gives it the calling par
12、tys number to display.,18:14:48.018 Reverse Traffic Channel: Order ACK_SEQ: 1 MSG_SEQ: 4 ACK_REQ: 0 ENCRYPTION: 0 Mobile Station Acknowledgement Order,The mobile says its ringing.,SERVICE CONNECT COMPLETE is a major milestone in call processing. Up until now, this was an access attempt. Now it is of
13、ficially a call.,正式通话,The mobile has been ringing for several seconds. The human user finally comes over and presses the send button to answer the call.,Now the switch completes the audio circuit and the two callers can talk!,结束一个通话,CDMA 呼叫处理过程,正常通话结束,At the end of a normal call, this mobile user pr
14、essed end.,The mobile left the traffic channel, scanned to find the best pilot, and read the Sync Channel Message.,The base station acknowledged receiving the message, then sent a release message of its own.,切换,CDMA 呼叫处理过程,呼叫已经建立了，手机还在搜索信号,Ec/Io,All PN Offsets,0 0,32728 512,Chips PN,0,-20,Neighbor S
15、et,The call is already in progress. PN 168 is the only active signal, and also is our timing reference. Continue checking the neighbors.,If we ever notice a neighbor with Ec/Io above T_ADD, ask to use it! Send a Pilot Strength Measurement Message!,T_ADD,10752 168,32000 500,14080 220,!,!,手机切换!,Just p
16、rior to this message, this particular mobile already was in handoff with PN 168 and 220. This pilot strength measurement message reports PN 500 has increased above T_Add, and the mobile wants to use it too.,The base station acknowledges receiving the Pilot Strength Measurement Message.,基站发切换消息,The base station sends a Handof Direction Message authorizing the mobile to begin soft handoff with all three requested PNs. The pre-existing link on PN 168 will continue to use Walsh code 61, the new link on PN220 will use Walsh Code 20, and the new link on PN500 will use Walsh code 50.,
