Detection techniques for V-BLAST in frequency selective fading channels

V-BLAST (Vertically-layered Bell Laboratories Layered Space-Time) is a multiple transmit and receive antenna system that provides very high capacity compared to single antenna systems. However, most research in this area had assumed a flat-fading channel environment. This paper considers a frequency selective Rayleigh fading channel environment for multi-input and multi-output (MIMO) systems. Three different detection techniques with ordered successive interference cancellation are proposed: (1) zero-forcing maximal ratio combining (ZF-MRC); (2) layered maximum likelihood detection (L-MLD); and (3) group maximum likelihood detection (G-MLD). All these schemes consider the delayed elements in each transmit-receive antenna pair as imaginary antennas transmitting delayed versions of the substreams. Constraints on the number of receive antennas are also discussed, with G-MLD requiring the least elements. Simulation results show that G-MLD provides the best performance with ZF-MRC performing the worst.