A comparative study of two blind FIR equalizers

The paper investigates blind finite-impulse-response (FIR) equalization schemes for quadrature amplitude modulation (QAM) signalling. We compare a bootstrap maximum a posteriori probability (MAP) equalizer with a recently introduced concurrent constant modulus algorithm (CMA) and decision directed (DD) equalizer (CMA+DD). Both equalizers are known to outperform the CMA considerably. The concurrent CMA+DD equalizer has a complexity that is slightly more than twice of the CMA, and the bootstrap MAP equalizer has computational requirements that are only slightly more complex than the CMA. Simulation results indicate that the bootstrap MAP blind FIR equalizer has a faster convergence rate than the concurrent CMA+DD blind FIR equalizer, but tuning of the former is more complicated than the latter