一种优化扩频通信系统帧同步性能的算法  

An Algorithm for Optimizing Frame Synchronization Performance of Spread Spectrum Communication System

作　　者：陈纪平 蔡刚 黄志洪 CHEN Jiping;CAI Gang;HUANG Zhihong(Aerospace Information Research Institute,Chinese Academy of Sciences,Beijing,100086 China)

机构地区：[1]中国科学院空天信息创新研究院,北京100086

出　　处：《科技创新导报》2021年第13期165-172,共8页Science and Technology Innovation Herald

摘　　要：本文针对扩频通信系统在低信噪比条件下帧同步成功率低的问题,提出了一种基于相关运算极值的软相关判决算法。利用帧头的固定随机序列的特性,与接收信息进行相关累加,选取累加结果最大的位置为帧头,该方法可以提升低信噪比条件下的同步成功率。利用MATLA B软件搭建了面向直接序列扩展频谱系统的仿真验证平台,在发射端模拟了信号的扩频与调制功能,在接收端实现了捕获、跟踪以及帧同步过程,模拟了不同信噪比对同步成功率的影响。仿真结果表明,对比判决成功率为85%的两种不同判决方式,传统硬判决所需的信噪比为-33dB以上,软判决方式所需信噪比为-39dB以上,性能优化了6dB,当利用连续的软相关算法进行判决时,所需信噪比为-41dB以上,性能优化再次提升2dB。同时在低信噪比-35dB到-40dB时,判决成功率能够提升70%。Aiming at the problem of low frame synchronization success rate in spread spectrum communication system under the condition of low signal-to-noise ratio,this paper proposes a soft correlation decision algorithm based on the extreme value of correlation operation.Utilizing the characteristics of the fixed random sequence of the frame header,the relevant accumulation is carried out with the received information,and the position with the largest accumulation result is selected as the frame header.This method can improve the synchronization success rate under the condition of low signal-to-noise ratio.A simulation verification platform for direct sequence spread spectrum system was built using MATLAB software.The signal's spread spectrum and modulation functions are simulated at the transmitting end,and the acquisition,tracking and frame synchronization processes are realized at the receiving end,and the synchronization success rate under different signal-to-noise ratios is simulated.The simulation results show that comparing two different decision methods with a decision success rate of 85%,the traditional hard decision requires a signal-to-noise ratio of-33dB or more,and the soft decision method requires a signal-to-noise ratio of-39dB or more.The performance is optimized by 6dB.When making decisions using continuous soft correlation algorithms,the required signal-to-noise ratio is above-41dB,and the performance optimization is increased by 2dB again.At the same time,when the signal-to-noise ratio is-35dB to-40dB,the decision success rate can be increased by 70%.

关 键 词：无线通信 直接扩频 帧同步 MATLAB仿真 

分 类 号：TN914.41[电子电信—通信与信息系统]