New sphere decoding for block space-time codes

Multiple antenna systems that operate at high data rates require simple yet effective space-time transmission schemes to handle the large traffic volume in real time. Recently, different block space-time codes, such as: Orthogonal Designs, VBLAST, LD (Linear Dispersion) codes, have been introduced. Due to the high complexity of the optimum ML (Maximum Likelihood) detection, sub-optimal detection methods like sequentially nulling and canceling for the VBLAST, have been proposed for non orthogonal block space-time codes. A new lattice decoder has been proposed using sphere decoding, but this method yet suffers from complexity and sensitivity to choose the radius of the sphere. We present a new sphere decoding algorithm that has lower complexity than other schemes and performs very close to ML decoding.