频域块LMS算法在直扩系统抗干扰中的应用研究

Application Research of Frequency Domain Block LMS Algorithm for Anti-jamming in DSSS System

针对直接序列扩频(DSSS)通信系统中窄带干扰抑制问题,研究频域块最小均方误差(LMS)算法。首先对传统LMS算法、符号LMS算法、归一化LMS算法和频域块LMS算法进行理论分析和性能对比,然后建立基于频域块LMS算法的DSSS抗干扰系统仿真模型。先通过信噪比改善因子仿真来验证算法有效性,再仿真比较不同信噪比和信干比条件下窄带干扰抑制效果。理论分析和仿真结果表明,频域块LMS算法不仅比前三种LMS算法有更精确的梯度向量估计和更低的计算复杂度,而且可以有效滤除窄带干扰,抗干扰性能能够达到或优于前三种LMS算法,滤除干扰后的误码率曲线接近无干扰系统。

For the narrowband interference suppression in direct sequence spread spectrum（DSSS） communication system, the frequency domain block LMS algorithm is studied. Firstly, the theory analysis and performance comparison of traditional LMS algo- rithm, symbol LMS algorithm, normalized LMS algorithm and frequency domain block LMS algorithm are carried out. Then the DSSS anti-jamming system simulation model based on the frequency domain block LMS algorithm is established. The validity of the frequency domain block LMS algorithm is verified by the SNR improvement factor simulation, and the narrowband interference sup- pression performances under different SNR and SIR conditions are simulated. Theory analysis and simulation results show that the frequency domain block LMS algorithm has more precise gradient vector estimation than the other three LMS algorithms, its compu- tation complexity is lower, and it can effectively filter out the narrowband interference. The anti-jamming performance of frequency domain block LMS algorithm can reach or exceed the other three LMS algorithms and the BER（ bit error rate） curve after filtering the interference is close to that of non-interference system.