Adaptive equalization with RLS-MLSE for frequency-selective fast fading mobile radio channels

Abstract

The authors propose a novel adaptive equalization scheme which is a combination of the recursive least squares adaptive algorithm and maximum likelihood sequence estimation (RLS-MLSE). The performance of the scheme is demonstrated in frequency-selective fast fading mobile radio channels. RLS-MLSE employs a parallel estimation scheme in which the state of the channel is estimated by the Viterbi algorithm and the parameters of the channel impulse response are estimated by RLS. A simplified RLS algorithm and an extension to the diversity reception scheme are discussed. Computer simulations show that RLS-MLSE is suitable for 40-kb/s QPSK (quadrature phase shift keying) transmission in 900-MHz-band mobile radio systems, and that equalization with two-branch diversity operates up to a maximum Doppler frequency of 160 Hz.<>