A Dual-mode Blind Equalization Algorithm for Improving the Channel Equalized Performance

Abstract

In this paper, we propose a new dual-mode blind equalization algorithm to improve the channel equalization performance. First, a kind of new error function is proposed and a nonlinear function between the step-size factor and the new error function is built to realize the variable step-size constant modulus algorithm (CMA). Then, in order to optimize the channel equalization performance, the variable step-size CMA is combined with decision directed least mean square (DDLMS) algorithm to form the new dual-mode algorithm. The new dual- mode algorithm uses either switching-dual mode or weighted dual-mode to update the coefficient of blind decision feedback equalizer. The simulation results show that in the situation of Gaussian white noise with 30dB signal-to-noise ratio, the proposed algorithm reduces the steady-state error to 12dB and drops inter symbol interference to 31dB in the condition of satellite channel. The new dual-mode algorithm not only increases the rate of convergence but also reduces the steady- state error. The proposed algorithm can be widely used in different communication channels such as the satellite channel.  Index Terms—Blind equalization; constant modulus algorithm; variable step-size; decision directed least mean square.