一种新变步长LMS算法在二阶自适应陷波器中的应用

A New Variable Step-Size LMS-Like Algorithm for a Second-Order Adaptive IIR Notch Filter

LMS自适应算法运算简单,但收敛速度较慢,且在低信干比条件下,滤波器系数的均方差(MSE)很大.为此,提出了一种新的变步长自适应算法(VS-LMS-L).该算法用瞬时输出信号的自相关估计值来控制步长的更新,能够在低信干比条件下,减小无关噪声的影响.该算法有着很快的收敛速度和较小的MSE,将它应用于DQPSK调制的卫星通信抗窄带干扰中.仿真表明,在输入信干比为-32.77 dB的条件下,得到了-6.93 dB的输出信干比,信干比改善达到了25.84 dB,显示出了这种算法的鲁棒性和优越性.

The traditional adaptive algorithm(PG algorithm) has a low computational complexity and is suitable for realtime implementation. However, its convergence of adaptation is not fast and the MSE of the filter coefficient is high, especially in the low input SNR. This paper presented a new variable stepsize adaptive algorithm for a second order adaptive IIR notch filter. It uses the estimate of the instantaneous output signal autocorrelation to control the step size update. This technique can reduce the effect of the uncorrelated noise in a low input SNR situation. It provides fast convergence and reduces the MSE of the filter coefficient. In the satellite communication system, the VSLMSL algorithm is applied to NarrowBand interference cancellation. The simulation result shows that under the condition of input SNR=-32.77dB, the output SNR=-6.93dB is got, which demonstrates the robustness and advance of our algorithm.