MATCHED-FILTER BOUND FOR TRELLIS-CODED TRANSMISSION OVER FREQUENCY-SELECTIVE FADING CHANNELS WITH DIVERSITY

Transmission of trellis-coded digital information over time-variant fr equency-selective multipath radio channels leads to receiver design co nsiderations and bit error characteristics fundamentally different fro m those of links using static channels. Making use of diversity is of prime importance in a fading environment. Explicit antenna diversity, implicit time diversity from inter-leaved trellis-coded modulation, an d implicit multipath diversity via energy detection/equalization are t hree methods of transmission quality enhancement that can be jointly e mployed without loss of power and bandwidth. The matched filter bound (MFB) is a lower bound on the average bit error rate under ideal condi tions, i.e. perfect channel estimation, interleaving, and equalization . In this paper, a new method of evaluating the MFB based on an eigenv alue approach is presented and the analysis extended to include transm ission of trellis-coded linearly modulated signals over selective dive rsity channels having arbitrary fading multipath profiles. MFB results are generated for a number of illuminating examples (trellis codes wi th effective code lengths up to 5, selective two-ray and GSM Rayleigh as well as flat Rician channels) that demonstrate the potential benefi ts of implicit time and multipath diversity. Some simulation results a re presented giving rise to concluding remarks on the tightness of the bound.