Embedded Rank Distance Codes for ISI Channels

Designs for transmit alphabet constrained space-time codes naturally lead to questions about the design of rank distance codes. Recently, diversity embedded multilevel space-time codes for flat-fading channels have been designed from sets of binary matrices with rank distance guarantees over the binary field by mapping them onto quadrature amplitude modulation (QAM) and phase-shift keying (PSK) constellations. In this paper, we demonstrate that diversity embedded space-time codes for fading intersymbol interference (ISI) channels can be designed with provable rank distance guarantees. As a corollary, we obtain an asymptotic characterization of the fixed transmit alphabet rate-diversity tradeoff for multiple antenna fading ISI channels. The key idea is to construct and analyze properties of binary matrices with a particular structure (Toeplitz structure) induced by ISI channels.