Series Equalizer Based on Constant Modulus Algorithm and Decision-Directed Algorithm

A new series equalizer based on constant modulus algorithm (CMA) and decision-directed (DD) algorithm is proposed to overcome inter-symbol interference (ISI) much better in the communication system without the aid of training sequences. The proposed equalizer uses the CMA as the forward filter and DD algorithm as the back filter. These two filters are series and operate concurrently. It makes full use of the advantages of the CMApsilas "eye-opened" ability and DDpsilas superior convergence performance. Therefore the proposed equalizer obtains not only the faster convergence and lower residual error but also the ability of phase rotation-compensated. Computer simulations with underwater acoustic channels are presented and the simulation results are shown to prove the efficiency of the proposed equalizer.