Log-likelihood ratio based detection ordering for the V-BLAST

We propose a new detection ordering for the V-BLAST. The main idea is to detect and cancel sub-streams in order of the magnitude of log-likelihood ratio (LLR), i.e. the symbol with the largest magnitude of LLR is detected first. The motivation is that the reliability of data decision increases with increasing magnitude of LLR. As a result, the error propagation associated with a wrong decision and the resulting error probability for the remaining sub-streams can be minimized. It is shown that the proposed LLR-based ordering significantly outperforms the conventional SNR-based ordering. Simplified LLR-based ordering and envelope-based ordering that require a much less computation, but provide a performance virtually identical to the LLR-based ordering, are also proposed.