The CMA equalizer operates in a blind fashion without training data and attempts to "calm" the system by bringing the signal constellation to a circle. This technique works best with PSK modulations but will work for a 4-ary QAM modulation.
The problem of using the CMA equalizer in this set up is that it cannot resolve phase ambiguities introduced by the channel. It needs to be used in conjunction with differential modulation or another form of trained equalizer.
Therefore, adding either one of the above suggestions should solve the issue when designing a communications link utilizing the CMA equalizer.
Best Answer