A low complexity closed-loop BLAST architecture

Original form of BLAST can provide very high data rate but is susceptible to fading correlations between transmit antennas. In this paper, we propose an improved form of BLAST architecture that employs a low rate feedback channel to adjust the transmission mode at the transmitter adaptively. An optimal criterion to select transmit antennas and modulation modes is derived based on zero-forcing technique. Simulation results in different scenarios show that the proposed closed-loop BLAST (or C-BLAST) outperforms the open-loop V-BLAST significantly, especially when the channel is ill-conditioned, since it judiciously selects a set of antennas to avoid disastrous fading correlations. Even in rich scattering environments, it still achieves some performance gain due to more efficient power allocations.