Combination Blind Equalization Suitable for 4-PAM and 16- QAM Signals

In digital communication system, De Castro et al. proposed a combination blind equalization based on a constant modulus algorithm (CMA) and a decision directed (DD) operating concurrently (CMA+DD) which is known to outperform the CMA considerably, however it still only achieves moderate steady-state mean square error (MSE). Then a new CMA based on modified function is discussed in such combination blind equalization scheme. For the 4- PAM and 16-QAM signals, by adjusting the coordinates of received signals the cost function will become exactly zero when the channel is perfectly equalized. So the proposed algorithm can obtain lower steady-state MSE than CMA+DD. Simulation results show that the proposed method achieves satisfactory performance.