Patent ID: 7809075

Claim:
A system for detecting a plurality of symbols communicated from multiple transmitting antennas to multiple receiving antennas, comprising: a first detector that determines the symbols from a plurality of respective partial distances of a first plurality of potential choices for at least one of the symbols from a constellation, the first detector determining the respective partial distances from a plurality of signals received at the receiving antennas; wherein the first detector comprises a K-best sphere detector; a second detector that determines the symbols from a plurality of respective partial distances of a second plurality of potential choices for at least one of the symbols from the constellation, the second detector determining the respective partial distances from the signals, and in response to a signal-to-noise ratio (SNR) of the signals being higher than a threshold the second plurality is fewer in number than the first plurality; wherein the second detector comprises a depth-first-search maximum-likelihood detector that prunes each second potential choice having the respective partial distance that is not less than the respective partial distance of one of the second potential choices; wherein the one of the second potential choices includes respective symbols for all of the symbols communicated from the transmitting antennas to the receiving antennas; wherein the respective partial distance of the one of the second potential choices is a distance between the respective symbols and the signals received at the receiving antennas; and an evaluator coupled to the first and second detectors, the evaluator estimating the SNR of the signals received at the receiving antennas, wherein the evaluator enables the first detector to determine the symbols in response to the SNR being lower than the threshold, and the evaluator enables the second detector to determine the symbols in response to the SNR being higher than the threshold.