Proposed affine projection algorithm for adaptive equalization over shallow water acoustic channel

Underwater acoustic communications especially over shallow water channels suffer from multipath spread that causes inter-symbol interference (ISI). One of the best ways for overcoming ISI is to use adaptive equalizers. In addition to convergence rate and steady-state error, computational complexity influences adaptive equalizers performance. In this paper, we apply least mean fourth-power of two quantizer (LMFPTQ) also we suggest proposed affine projection algorithm (Proposed APA) and proposed normalized least mean fourth (Proposed NLMF) as new algorithms with lower steady-state error and faster convergence rate in comparison with LMF-PTQ, for equalizing underwater acoustic communications. We apply experimental data from Persian Gulf for examining and showing that the proposed method provides a good trade-off between convergence rate and computational complexity over shallow water channels.