A variable step size LMS equalization algorithm in the satellite communication system

摘要

Equalization algorithm has a great significance to overcome the inter-symbol interference (ISI) existing in the satellite communication system. But fixed step size (FSS) LMS equalization algorithms and traditional variable step size LMS (VSSLMS) equalization algorithms do not perform well in some aspects such as convergence speed. Therefore, a VSSLMS equalization algorithm based on logarithmic function is proposed. It establishes a nonlinear function relationship between step size and autocorrelation value of the error signal. It also introduces the smoothing factor and the previous step size to control the steady-state error with small fluctuations. Compared with the similar algorithms, the proposed algorithm performs better than those algorithms in aspects of anti-noise performance, convergence speed and tracking speed. The model of the satellite communication system is presented, and the proposed algorithm is applied to the adaptive equalizer in the model. The simulation result shows that the bit error rate (BER) performance of the system is effectively improved.