Blind FIR equalisation for high-order QAM signalling

Abstract

We compare some blind finite-impulse-response (FIR) equalisation schemes for high-order quadrature amplitude modulation (QAM) signalling. The popular constant modulus algorithm (CMA) is used as a benchmark in an investigation of two blind FIR equalisers, namely, a bootstrap maximum a posteriori probability (MAP) equaliser and a recently introduced concurrent CMA and decision directed (DD) equaliser (CMA+DD). Both equalisers are known to outperform the CMA considerably at costs of a small increase in computational complexity. Our study indicates that the bootstrap MAP equaliser has a faster convergence rate than the concurrent CMA+DD equaliser.