A reduced-complexity maximum-likelihood
detector that provides a high degree of
signal detection accuracy while maintaining high
processing speeds. A communication
system implementing the present invention comprises a plurality of transmit sources operable to transmit a plurality of symbols over a plurality of channels, wherein the
detector is operable to receive symbols corresponding to the transmitted symbols. The
detector processes the received symbols to obtain initial estimates of the transmitted symbols and then uses the initial estimates to generate a plurality of reduced search sets. The reduced search sets are then used to generate decisions for detecting the transmitted symbols. In various embodiments of the invention, the decisions for detecting the symbols can be hard decisions or soft decisions. Furthermore, in various embodiments of the invention, the initial estimates can be obtained using a plurality of linear
equalization techniques, including zero-forcing
equalization, minimum-mean-squared-error
equalization. The initial estimate can also be obtained by nulling and canceling techniques. In various embodiments of the invention, the data output corresponding to the transmitted symbols can be obtained using a log-likelihood probability ratio. The method and apparatus of the present invention can be applied to any communication
system with multiple transmit streams.