In the past few years, theoretical investigations have revealed that the multipath wireless channel is capable of enormous capacities, provided that the multipath scattering is sufficiently rich and is properly exploited through the use of an appropriate processing architecture. V-BLAST is a well-known architecture, which has demonstrated spectral efficiencies of 20 - 40 bps/Hz in an indoor propagation environment. However, owing to the intensive computation involved, it may be difficult to implement this architecture for high data rate communication system. In this research, a method is proposed to reduce its complexity by using a sub-optimal decoding order and utilizing Gram-Schmitt Orthogonalization (GSO) to substitute the computation of a series of pseudo-inverse in finding the weig...[ Read more ]

In the past few years, theoretical investigations have revealed that the multipath wireless channel is capable of enormous capacities, provided that the multipath scattering is sufficiently rich and is properly exploited through the use of an appropriate processing architecture. V-BLAST is a well-known architecture, which has demonstrated spectral efficiencies of 20 - 40 bps/Hz in an indoor propagation environment. However, owing to the intensive computation involved, it may be difficult to implement this architecture for high data rate communication system. In this research, a method is proposed to reduce its complexity by using a sub-optimal decoding order and utilizing Gram-Schmitt Orthogonalization (GSO) to substitute the computation of a series of pseudo-inverse in finding the weight vectors.

Recently, a lattice decoding algorithm is proposed to obtain the optimum performance in MIMO channel and its complexity is a thousand times smaller than that of the standard exhaustive search. In this research, the lattice decoder has been analyzed as a depth-first tree search and approaches have been proposed to further reduce the complexity by several times using a child node ordering and checking the optimality of the initial estimate.

The lattice decoding algorithm has the disadvantage of non-fixed throughput since the amount of calculation required is highly varying. A K-Best algorithm of which the amount of calculation is tightly bounded is proposed. The algorithm can be easily implemented in a pipelined architecture, which is impossible for the conventional lattice decoder. The K-Best algorithm is not optimal, but its performance is very closed to the optimum performance, if the value of K is sufficiently large. The pipeline architecture of K-best algorithm has been developed. It is shown that using 0.35 μm technology, a bit rate of 10Mbps can be easily achieved with perfomance close to the conventional lattice decoder.