Research on Blind Equalization Technique of Hydroacoustic Channel Based on Adaptive Spiral Search Sparrow Algorithm

In the process of hydroacoustic communication, the receiver has the problems of serious signal distortion and high bit error rate (BER) due to the multipath effect and Doppler effect of hydroacoustic channel. Therefore, a new sparrow optimization algorithm (WA-SSA) based on adaptive spiral search is proposed and used for the blind equalization technique to solve the above problems. In this algorithm, the population is initialized by Tent chaotic mapping to ensure the diversity of initial positions, and the positions are updated by using the spiral search strategy in the whale algorithm. In addition, the algorithm improves the optimization search process by using the adaptive step size factor, and also perturbs the population by using the Gauss-Cauchy variation to improve the ability of jumping out of the local optimal solution. Finally, the WA-SSA algorithm is used to optimize the tapped power vector of the constant modulus algorithm (CMA) which is applied to the hydroacoustic communication system. Compared with other optimization algorithms, the WA-SSA algorithm converges faster and has higher convergence accuracy. The results of the sea trial experiments show that the CMA technique based on the WA-SSA algorithm improves the convergence accuracy of the constellation map, reduces the mean square error and the BER, and achieves a better equalization effect under three modulation methods, namely 8PSK, 16QAM and 64QAM.