1　无线传输环境无线信道 (特别是陆地移动信道 ) ,由于地面情况的复杂性 ,发射的信号往往是经过多条路径到达接收端 ,即产生多径效应 ,从而造成接收信号相互重叠 ,产生信号符号间相互干扰 ,致使接收端判断错误 ,严重影响信号传输质量 ,这种特征为信道的时间弥散性。特别是当信 A wireless transmission environment Wireless channel (especially land mobile channel), due to the complexity of the ground situation, the transmitted signal is often through the path to reach the receiving end, that multipath effect, resulting in the received signals overlap each other, resulting in signal symbols Mutual interference, resulting in the receiver to determine the error, seriously affecting the quality of signal transmission, this feature is the time dispersion of the channel. Especially when the letter