1、 摘 要 本课题研究卷积编码在扩频通信系统中的性能分析。CDMA( CodeD ivisionM ultipleA ccess)通信是利用相互正交(或尽可能正交)的不同编码分配给不同用户调 制信号，实现多用户同时使用同一频率接入系统和和网络的通信，即码分多址通 信.由于利用相互正交(或尽可能正交)的编码去调制信号， 会将原信号的信号频谱带 宽扩展。因此，对这种调制方式的通信，又称为扩展频谱通信。信号在传输中往 往由于各种原因，使得在传送的数据流中产生误码，从而使接收端产生图象跳跃、 不连续、出现马赛克等现象。所以通过信道编码这一环节，对数码流进行相应的 处理，使系统具有一定的纠错能力和抗干扰能
2、力，可极大地避免码流传送中误码 的发生。误码的处理技术有纠错、交织、线性内插等。信道类型主要又高斯，瑞 利，莱斯分布，它们对信号得影响也有所不同。为了提高信号传输的可靠性和纠 错能力，我们使用卷积编码方式，但是对不同的信道类型，卷积编码对系统性能 的作用也不同。本设计课题就是利用软件方法搭建通信模型研究在 CDMA 扩频通 信系统中，不同卷积速率在高斯，瑞利，莱斯分布下的不同效果 。 先用 simulink 搭建扩频通信一般模型，再加入卷积编码和维特比译码，然后 观察信号的在高斯，瑞利，莱斯信道下的误码率，画出误码率曲线，分析并总结 出不同无线信道下的性能。 关键词：扩频通信；码分多址；信道；
3、卷积编码 ABSTRACT This thesis attempt to research the performance of convolusional coding in Spread-spectrum communication system. CDMA communication distribution different uers different Code which are Mutually orthogonal ,implementation, Multi-user access at the same time using the same frequency and
4、network systems ,called Code Division Multiple Access Communication.The use of orthogonal code modulation signal will expansion signal spectrum bandwidth of the original signal.Therefore, the modulation mode of communication, also known as spread spectrum communication.Signal transmission often for
5、a variety of reasons, makes the transmission of data flow generated in error, so that the receiver generated images jumping, not continuous, and phenomena such as a mosaic。Therefore, through this link of channel coding, digital flow corresponding handling, allowing the system to have a certain error
6、 correction capability and anti-jamming capabilities, Code can greatly spread avoid the occurrence of error in the delivery.Error handling technology FEC, interleaving, such as linear interpolation. the main channel type of Gaussian, Rayleigh, Rice distribution, and they signal a very different impact.In order to improve the reliability of signal transmission and error correction capability, we use convolution encoder, However, the different types of channel, convolution coding properties of t
