Blind Equalization Schemes with Different Error Equations

A general problem with blind adaptation techniques is that they have poor convergence properties compared to the traditional techniques using training sequences. Having a multi-modal cost surface, blind adaptation techniques may force the equalizer to converge to a false minimum, depending on the initialization. The most commonly used blind adaptation algorithm is the Constant Modulus Algorithm (CMA). In our simulations a logarithmic error equation causes CMA to converge to a global minimum when a differential encoding scheme is used. The convergence rates of CMA with different error equations were also investigated for a symmetric channel.