Modulation diversity for fading ISI channels: performance analysis and code design

In this paper, modulation diversity (MD) for Rayleigh fading intersymbol interference (ISI) channels is proposed. In particular, the achievable performance with MD is analyzed and a design criterion for MD codes is deduced from an upper bound on the pairwise error probability. This design rule is similar to the well-known design rule for MD codes for flat fading and does not depend on the power delay profile of the fading channel. Several examples for MD codes with prescribed properties are given and compared. Simulation results confirm that considerable performance gains can be achieved with MD even if suboptimum equalization schemes are adopted at the receiver.