Log-likelihood-ratio-based detection ordering in V-BLAST

We propose a new detection ordering based on the log-likelihood ratio (LLR) in the iterative nulling and cancellation process of vertical Bell Laboratories layered space-time (V-BLAST) decoding. The motivation for using the LLR is that it provides the reliability information on the maximum a posteriori probability decision. As a result, the error propagation associated with a wrong cancellation can be minimized. Simplified ordering schemes that require a much less computation, but provide a performance virtually identical to the LLR-based ordering, are also provided. The performance of the LLR ordering in the V-BLAST combined with space-time block codes is evaluated.