Abstract: For that the traditional frequency domain block LMS algorithm which is used for the narrowband interference suppression in Direct Sequence Spread Spectrum（DSSS） communication anti-jamming system leads to a conflict of convergence speed and steady stage error, a new variable step size FBLMS algorithm is proposed, it is the ratio of the remaining interference of the output signal and the overall noise signal to control the variable step size factor update, as interference is filtered, the step size factor is also reduced, making the DSSS communications jamming system to obtain better suppression interference effect. Firstly, DSSS communications jamming system based on the frequency domain block LMS algorithm is introduced. Then the proposed variable step size FBLMS is analyzed. Finally, simulation comparison of this algorithm and traditional algorithm are carried out. Theory analysis and simulation results show that the VSS-FBLMS algorithm can effectively filter out the narrowband interference. The anti-jamming performance of VSS-FBLMS algorithm can exceed the traditional FBLMS algorithm, convergence rate and steady-state error is also superior to the traditional FBLMS algorithm.

Key words: direct sequence spread spectrum, frequency domain block LMS algorithm, variable step size, narrowband interference

摘要： 针对现有直接序列扩频（DSSS）通信抗干扰系统中的传统频域块最小均方误差（FBLMS）算法在收敛速度和稳态误差之间存在矛盾的问题，提出了一种新的变步长算法——VSS-FBLMS算法，该算法通过输出信号中剩余干扰所占整体噪声信号的比例来调节变步长因子，步长因子随着干扰的被滤除而逐渐减小，使得DSSS通信抗干扰系统获得更好的抑制干扰效果。首先对传统FBLMS算法的DSSS抗干扰系统进行了介绍，然后对提出的VSS-FBLMS算法进行分析，最后将新算法和传统算法加入DSSS通信抗干扰系统中进行仿真对比。理论分析和仿真结果表明，VSS-FBLMS算法不仅可以有效滤除窄带干扰，而且抗干扰性能优于传统FBLMS算法，收敛速率和稳态误差也都优于传统FBLMS算法。

关键词: 直接序列扩频, 频域块LMS算法, 变步长, 窄带干扰