基于Matlab的直扩通信系统仿真

摘要

人们的生活充满了各类信息的交互需求，从贝尔实验室电话接通的时刻起，有线通信进入人们的视野，而到了现在无线通信方式成了我们当今生活的必需品。出于无线通信环境的复杂性和恶劣性以及对通信质量的要求，通信系统的抗干扰性能的优化提升成了一个热点课题，扩频通信技术也逐渐发展成为众多通信系统中不可或缺的部分。主要有跳频扩频技术和直接序列扩频技术。

直接序列扩频的本质就是用高码率的扩频码序列在发送端与信号序列相乘扩展信号频谱，接收端用相同的扩频码序列进行解扩，得到原始信息。本文用Matlab软件中Simulink通信仿真模块进行直扩通信系统的仿真和分析。Simulink 仿真模型采用二进制发生器做数字信源，利用PN码产生器产生扩频序列调制信源，经过BPSK调制后发射至高斯白噪声信道进行传输。在接收端，通过乘法器进行解扩调制，再经BPSK解调得到恢复出的信息，与信源信息对比，计算误码率并进行相关分析。仿真中，将设计重点放在了扩频调制和BPSK调制，故系统同步和信道部分做了理想处理，在假设系统已准确同步的情况下进行了仿真。在给定的条件下，对Simulink仿真模型进行了运行测试，得到了预期的仿真结果。

【关键词】直接序列扩频BPSK调制Simulink 系统仿真抗干扰

ABSTRACT

Since the moment of Bell Labs’ call connected, the wired communications comes into our vision, and however wireless communication has become a necessity nowadays. Requirements for wireless communication complexity of the environment and poor communication quality, anti-jamming performance of the communication system optimization and upgrading has become a hot topic in the spread spectrum communication technology .It has gradually developed into an integral part of many communications systems . The main frequency hopping spread spectrum and direct sequence spread spectrum technology.

The nature of the direct-sequence spread-spectrum technology is the spreading code sequence with a high bit rate expanded in the transmitter and the signal sequence multiplying the signal spectrum, the receiver dispread using the same spreading code sequence to get the original information. The DSSS communication system with Matlab analysis software is used to simulink and build simulation communication model. We use the binary generator to generate a digital source, the PN code generator produce the order spread spectrum sequence, multiply them and send the result to the white Gaussian noise channel after BPSK modulation for transmission. At the receiving end, message is dispread and modulated through the multiplier, and t hen demodulated by the BPSK demodulation. Compared with the source of informati on, the bit error rate is calculated and analysized. In this Simulation, the design focus on the spread spectrum modulation and BPSK modulation, so the system synchronization and channel part of the ideal treatment, were simulated under the assumption that the system has accurate synchronization. Run the test under the given conditions, the Simulink model and got the simulation results which we want.

【Keywords】Direct sequence spread spectrum BPSK modulation Simulink system simulation anti-jamming

目录

前言 (1)

第一章扩频通信概述 (2)

第一节扩频通信的发展和应用 (2)

第二节扩频通信理论基础及分类 (3)

一、扩频通信理论基础 (3)

二、扩频通信系统分类 (4)

第三节扩频通信基本性能参数 (4)

一、处理增益 (4)

二、干扰容限 (5)

三、干扰门限 (5)

四、射频带宽 (6)

第四节扩频通信技术现状 (6)

第五节本章小结 (7)

第二章直接序列扩频通信 (8)

第一节直接序列扩频原理及调制过程 (8)

一、直接序列扩频基本原理 (8)

二、直扩系统的调制方式 (9)

三、直扩系统的解扩调制 (10)

第二节伪随机编码 (11)

一、伪随机编码概述 (11)

二、m序列 (12)

第三节直接序列扩频通信主要特点 (13)

第四节直扩系统同步原理 (15)

第四节直扩系统抗干扰能力分析 (17)

一、直扩系统抗宽带干扰性能 (17)

二、直扩系统抗窄带干扰性能 (17)

三、直扩系统抗多径干扰性能 (18)