A soft fast estimation method of PN sequence based on weighting Walsh Hadamard Transform

Poor error-tolerance and polynomial taps restriction are the main issues of Walsh Hadamard Transform estimation method. This article is devoted to these issues and a novel soft fast PN sequence estimation algorithm based on weighting Walsh Hadamard Transform is proposed. Firstly, the theoretical analysis about error-tolerance likelihood bound of sequence hard-decision and restrictive factor of estimation polynomial taps is performed. Based on the analysis, the sequence soft information is introduced into sequence frequency-coefficient to improve estimation performance, and the Walsh Hadamard matrix is column-weighted to change its binary property, which can decrease the influence of polynomial taps to estimation performance. Meanwhile, the sequence control state is chosen to decrease the estimation polynomial taps in essence. Simulation results illustrate that our proposed method is irrelevant with the order and tap of generation polynomial and can yield a performance gain of more than 1.5dB compared to WHT.