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style="mso-hansi-font-family: Times New Roman">51帧的复帧---它包括51个TDMA帧，持续时长3060／13ms。26个这样的复帧组成一个超帧。这种复帧用于携带BCH和CCCH。 </SPAN></FONT><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><O:P>
</O:P></SPAN></P>
<P class=MsoNormal><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN><FONT
color=#0000cc>（3）突发脉冲序列（Burst）<O:P>
</O:P></FONT><O:P></O:P></SPAN></P>
<P class=MsoNormal><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN><FONT face=楷体_GB2312
color=#000066>TDMA信道上一个时隙中的信息格式称为突发脉冲序列。共有五种类型。<O:P>
</O:P></FONT></SPAN></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN>①
普通突发脉冲序列（NB）：用于携带TCH及除RACHA，SCH和FCCH以外的控制信道上的信息，图3-9所示，</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">“</SPAN><SPAN
lang=EN-US
style="mso-hansi-font-family: Times New Roman">57个加密比特</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">是客户数据或话音，再加</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">“</SPAN><SPAN
lang=EN-US
style="mso-hansi-font-family: Times New Roman">1</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">个比特用作借用标志。借用标志是表示此突发脉冲序列是否被<SPAN
lang=EN-US>FACCH信令借用。</SPAN></SPAN><SPAN lang=EN-US
style="mso-ascii-font-family: 宋体">“</SPAN><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman">26个训练比特</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">是一串已知比特，用于供均衡器产生信道模型（一种消除时间色散的方法）。<SPAN
lang=EN-US><O:P> </O:P></SPAN></SPAN></FONT></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US
style="mso-hansi-font-family: Times New Roman; mso-spacerun: yes">
</SPAN><SPAN lang=EN-US
style="mso-ascii-font-family: 宋体">“</SPAN><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman">TB</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">尾比特总是<SPAN
lang=EN-US>000帮助均衡器判断起始位和中止位。</SPAN></SPAN><SPAN lang=EN-US
style="mso-ascii-font-family: 宋体">“</SPAN><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman">GP</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">保护间隔，<SPAN
lang=EN-US>8.25个比特（相当于大约30</SPAN></SPAN><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman; mso-ascii-font-family: 宋体; mso-char-type: symbol; mso-symbol-font-family: Symbol">m</SPAN><SPAN
lang=EN-US
style="mso-hansi-font-family: Times New Roman">s），是一个空白空间。由于每载频最多8个客户，因此必须保证各自时隙发射时不相互重迭。尽管使用了时间调整方案，但来自不同移动台的突发脉冲序列彼此间仍会有小的滑动，因此8.25个比特的保护可使发射机在GSM建议许可范围内上下波动。<O:P>
</O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes">
</SPAN>
<IMG height=69 src="g3-3.files/g3-3.H8.gif" width=338
v:shapes="_x0000_i1027"><O:P> </O:P></SPAN></FONT></P>
<P class=MsoNormal style="TEXT-ALIGN: center" align=center><FONT
face=楷体_GB2312 color=#000066><SPAN
style="mso-hansi-font-family: Times New Roman">图<SPAN lang=EN-US>3－9
普通突发脉冲序列<O:P> </O:P><O:P></O:P></SPAN></SPAN></FONT></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US
style="mso-hansi-font-family: Times New Roman">
</SPAN><SPAN style="mso-hansi-font-family: Times New Roman">②
频率校正突发脉冲序列（<SPAN
lang=EN-US>FB）：用于移动台的频率同步，它相当于一个带频移的未调载波。此突发脉冲序列的重复称FCCH，见图
3-10。图中</SPAN></SPAN><SPAN lang=EN-US
style="mso-ascii-font-family: 宋体">“</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">固定比特</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">全部是<SPAN
lang=EN-US>0，使调制器发送一个未调载波。</SPAN></SPAN><SPAN lang=EN-US
style="mso-ascii-font-family: 宋体">“</SPAN><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman">TB</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">和</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">“</SPAN><SPAN
lang=EN-US
style="mso-hansi-font-family: Times New Roman">GP</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">同普通突发脉冲序列中的</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">“</SPAN><SPAN
lang=EN-US
style="mso-hansi-font-family: Times New Roman">TB</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">和</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">“</SPAN><SPAN
lang=EN-US
style="mso-hansi-font-family: Times New Roman">GP</SPAN><SPAN
lang=EN-US style="mso-ascii-font-family: 宋体">”</SPAN><SPAN
style="mso-hansi-font-family: Times New Roman">。<SPAN
lang=EN-US><O:P> </O:P></SPAN></SPAN></FONT></P>
<P class=MsoNormal
style="TEXT-INDENT: 31.5pt; mso-char-indent-count: 3.0; mso-char-indent-size: 10.5pt"><FONT
face=楷体_GB2312 color=#000066><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN>
<IMG height=79 src="g3-3.files/g3-3.H9.gif" width=401
v:shapes="_x0000_i1028"><O:P> </O:P></SPAN></FONT></P>
<P class=MsoNormal style="TEXT-INDENT: 21pt; TEXT-ALIGN: center"
align=center><FONT face=楷体_GB2312 color=#000066><SPAN
style="mso-hansi-font-family: Times New Roman">图<SPAN
lang=EN-US>3－10 频率校正突发脉冲序列<O:P>
</O:P><O:P></O:P></SPAN></SPAN></FONT></P>
<P class=MsoNormal style="TEXT-INDENT: 21pt"><FONT face=楷体_GB2312
color=#000066><SPAN style="mso-hansi-font-family: Times New Roman">③
同步突发脉冲序列（<SPAN
lang=EN-US>SB）：用于移动台的时间同步，它包括一个易被检测的长同步序列并携带有TDMA帧号和基站识别码（BSIC）信息。这种突发脉冲序列的重复称为SCH，见图3－11所示。<O:P>
</O:P></SPAN></SPAN></FONT></P>
<P class=MsoNormal
style="TEXT-INDENT: 63pt; mso-char-indent-count: 6.0; mso-char-indent-size: 10.5pt"><FONT
face=楷体_GB2312 color=#000066><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman">
<IMG height=68 src="g3-3.files/g3-3.H10.gif" width=362
v:shapes="_x0000_i1029"><O:P> </O:P></SPAN></FONT></P>
<P class=MsoNormal style="TEXT-INDENT: 21pt; TEXT-ALIGN: center"
align=center><FONT face=楷体_GB2312 color=#000066><SPAN
style="mso-hansi-font-family: Times New Roman">图<SPAN
lang=EN-US>3－11 同步突发脉冲序列<O:P>
</O:P><O:P></O:P></SPAN></SPAN></FONT></P>
<P class=MsoNormal style="TEXT-INDENT: 21pt"><FONT face=楷体_GB2312
color=#000066><SPAN style="mso-hansi-font-family: Times New Roman">④
接入突发脉冲序列（<SPAN
lang=EN-US>AB）：用于随机接入，它有一个较长的保护间隔，这是为了适应移动台首次接入（或切换到另一个BTS）后不知道时间提前量而设置的。移动台可能远离BTS，这意味着初始突发脉冲序列会迟一些到达BTS，由于第一个突发脉冲序列中没有时间调整，为了不与下一时隙中的突发脉冲序列重叠，此突发脉冲序列必须短一些，见图3－12所示。<O:P>
</O:P></SPAN></SPAN></FONT></P>
<P class=MsoNormal
style="TEXT-INDENT: 52.5pt; mso-char-indent-count: 5.0; mso-char-indent-size: 10.5pt"><FONT
face=楷体_GB2312 color=#000066><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman">
<IMG height=84 src="g3-3.files/g3-3.H11.gif" width=372
v:shapes="_x0000_i1030"><O:P> </O:P></SPAN></FONT></P>
<P class=MsoNormal style="TEXT-INDENT: 21pt; TEXT-ALIGN: center"
align=center><FONT face=楷体_GB2312 color=#000066><SPAN
style="mso-hansi-font-family: Times New Roman">图<SPAN
lang=EN-US>3－12 接入突发脉冲序列<O:P>
</O:P><O:P></O:P></SPAN></SPAN></FONT></P>
<P class=MsoNormal style="TEXT-INDENT: 21pt"><FONT face=楷体_GB2312
color=#000066><SPAN style="mso-hansi-font-family: Times New Roman">⑤
空闲突发脉冲序列（<SPAN
lang=EN-US>DB）：此突发脉冲序列在某些情况下由BTS发出，不携带任何信息。它的格式与普通突发脉冲序列相同，其中加密比特改为具有一定比恃模型的混合比特。</SPAN></SPAN><SPAN
lang=EN-US
style="mso-hansi-font-family: Times New Roman"> </SPAN></FONT><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><O:P>
</O:P></SPAN></P>
<P class=MsoNormal><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN><FONT
color=#0000cc>（4）逻辑信道到物理信道的映射<O:P>
</O:P></FONT><O:P></O:P></SPAN></P>
<P class=MsoNormal><SPAN lang=EN-US
style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN><FONT
face=楷体_GB2312
color=#000066>谈过TDMA信道、TDMA帧和突发脉冲序列之后，我们就可以谈谈逻辑信道映射到物理信道的方法。我们知道每小区有若干个载频，每个载频都有8个时隙，我们定义载频数为C0，C1，…，Cn，时隙数为T30，T51，···，T87。<O:P>
</O:P></FONT></SPAN></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN>① 控制信道的映射<O:P>
</O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes">
</SPAN>对某小区超过1个载频时，该小区C0上的TS0就映射广播和公共控制信道，具体映射方法见图3－13。图中所示：<O:P>
</O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes">
</SPAN>F（FCCH）--- 移动台依此同步频率，它的突发脉冲序列为FB。<O:P>
</O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes">
</SPAN>S（SCH）--- 移动台依此读TDMA帧号和BSIC码，突发脉冲序列为SB。<O:P>
</O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes">
</SPAN>B（BCCH）--- 移动台依此读有关此小区的通用信息。突发脉冲序列为NB。<O:P>
</O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes">
</SPAN>I（IDEL）--- 空闲帧，不包括任何信息。突发脉冲序列为DB。<O:P>
</O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=楷体_GB2312 color=#000066><SPAN
lang=EN-US style="mso-hansi-font-family: Times New Roman"><SPAN
style="mso-spacerun: yes">
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