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<TD borderColor=#6699ff><FONT
size=2>您的位置：技术园地>技术讲座-GSM蜂窝移动通信系统 </FONT></TD></TR>
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<DIV align=center><FONT color=#000080 size=5><B><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">第八讲</SPAN><SPAN
lang=EN-US style="mso-spacerun: yes"> </SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">呼叫处理</SPAN></B><SPAN
lang=EN-US><SPAN
style="mso-spacerun: yes"> (3-4) </SPAN></SPAN></FONT><FONT
size=4></FONT></DIV></TD></TR>
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<P class=MsoNormal style="LINE-HEIGHT: 150%"><B><SPAN lang=EN-US
style="FONT-SIZE: 12pt; mso-spacerun: yes"><A
name="8.3 初始化"></A></SPAN><A name="8.3 初始化"><SPAN lang=EN-US
style="FONT-SIZE: 12pt">8.3<SPAN style="mso-spacerun: yes">
</SPAN></SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">初始化</SPAN></A><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></B></P>
<P class=MsoNormal style="LINE-HEIGHT: 150%"><SPAN lang=EN-US
style="FONT-SIZE: 12pt; mso-spacerun: yes">
</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"><FONT
color=#000066>初始化过程是一个随机接入过程。从广义上说，这个过程始于</FONT></SPAN><FONT
color=#000066><SPAN lang=EN-US
style="FONT-SIZE: 12pt">MS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">MS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在<BR></SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">RACH(</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">随机接入信道</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">)</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">上发送一条“信道请求”消息，</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BTS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">收到此消息后通知</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BSC</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，并附上</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BTS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">对该</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">MS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">到</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BTS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">传输时延的估算及本次接入原因，</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BSC</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">根据接入原因及当前资料情况，选择一条空闲的专用信道</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">SDCCH</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">通知</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BTS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">激活它。</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BTS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">完成指定信道的激活后，</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BSC</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">在</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">AGCH(</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">允许接入</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">)</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">上发送“立即分配”消息或称</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">为初始化分配消息，其中包含</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BSC</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">分配给</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">MS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">SDCCH</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">信道描述，初始化时间提前量、初始化最大传输功率以及有关参考值。每个在</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">AGCH</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">信道上等待分配的</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">MS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可以通过比较参考值来判断这个分配信息的归属，以避免争抢引起混乱。</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></FONT></P>
<P class=MsoNormal
style="TEXT-INDENT: 24pt; LINE-HEIGHT: 150%; mso-char-indent-count: 2.0; mso-char-indent-size: 12.0pt"><FONT
color=#000066><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">当</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">MS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">正确地收到自己的初始分配后，根据信道的描述，把自己调整到该信道上，建立一条传输信令的链路，发送第一个专用信道上的初始消息，其中含有客户的识别码</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">(</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">来自</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">SIM</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">卡上的信息</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">)</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">、本次接入的原因、登记和鉴权等内容。</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt"><O:P> </O:P></SPAN></FONT></P>
<P class=MsoNormal style="LINE-HEIGHT: 150%"><FONT
color=#000066><SPAN lang=EN-US
style="FONT-SIZE: 12pt; mso-spacerun: yes">
</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">当</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BSC</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">没有空闲信道可供分配时，</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">BSC</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">要向</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">MS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">发出“立即分配拒绝”消息，其中可以含有一个限制</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">MS</SPAN><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">继续呼出的时间指示。这是—种减少</SPAN><SPAN
lang=EN-US style="FONT-SIZE: 12pt">RACH</SPAN><SPAN
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