DSSS 卫星通信中基于小波包变换的干扰抑制方法

摘要

卫星通信中利用直接序列扩频技术具有一定的抗干扰能力，但由于扩频增益无法做到无限大，当强干扰超过系统的干扰容限时，系统传输性能将会大幅降低。通过变换域信号处理技术对直接序列扩频中的干扰进行检测与抑制，能够增强其抗干扰能力。小波包变换具有优异的时频域局部分析能力，非常适合用于直接序列扩频系统中干扰检测与抑制。分别对规则小波包分解和最佳小波包分解进行了研究，提出了一种基于最佳小波包分解的干扰抑制新方法，通过将子带功率比与最小功率阈值相结合，实现对干扰进行定位和抑制。仿真结果表明，所提出的算法与基于规则小波包分解的干扰抑制和传统的快速傅里叶变换算法干扰抑制相比较，性能得到显著改善，且在计算复杂度上上升极少，是提高直接序列扩频信号抗干扰能力的更有效的选择。%Direct sequence spread spectrum (DSSS)can suppress interference to a certain extend in satellite communication.However,because the spreading gain is limited,when strong interference is more than the sys-tem interference tolerance margin,the system transmission performance would be reduced sharply.The tech-nology of transform domain signal processing could detect and suppress interference in the DSSS,so it could im-prove the anti-interference ability of the system.Wavelet packet transform which has the excellent time-fre-quency local analysis ability,is very suitable for interference detection and suppression in the DSSS system.The regular wavelet packet decomposition and the best wavelet packet decomposition are studied,and a new method for interference suppression based on the best wavelet packet decomposition is proposed,which combines subba-nd power ratio and the minimum power threshold to location and suppress interference.The simulation results show that the proposed algorithm enhances the performance and anti-interference ability of the system greatly, increases the computational complexity slightly,compared to that based on regular wavelet packet decomposi-tion and the traditional fast Fourier transformation (FFT)algorithm.It is a more effective method to suppress interference in the satellite DSSS communication system.