||The next generation wireless communication systems are expected to support a wide range of high-quality services which require high data rate transmission as well as high system capacities. One of the most recent and promising techniques for realizing extraordinary spectral efficiencies over wireless links is V-BLAST (Vertical-Bell Laboratories Layered Space-Time). This is a new system proposed by Bell Laboratories as an extremely efficient scheme for high capacity communications in wireless environments. The V-BLAST technique employs a multi-element antenna array technology at both the transmitter and receiver to increase system capacity, data rate as well as spectral efficiency. In this thesis, we consider the performance of V-BLAST in a frequency selective fading channel. In particular, we investigate the effect of time delay spread on V-BLAST. In order to make V-BLAST more robust against the detrimental effects of frequency selective and time varying channels, we combine V-BLAST with Orthogonal Frequency Division Multiplexing (OFDM) transmission and Reed-Solomon coding. Owing to the required intensive computation involved, we propose a low complexity multicarrier V-BLAST based on the use of a subcarrier grouping, an innovative sub-optimal decoding ordering procedure, and the Gram-Schmitt Orthogonalization (GSO) procedure instead of the pseudoinverse operation used in V-BLAST. It is shown that the proposed system can greatly reduce the computational complexity required with a minimal penalty in performance compared with a standard multicarrier V-BLAST.