Enhanced MIMO detection with parallel V-BLAST

Foschini quantified the large capacity of the multiple-input multiple-output (MIMO) wireless channel and showed how this capacity could be achieved using a layered and coded space-time architecture. Unfortunately, his proposed diagonal Bell Laboratories Space-Time (D-BLAST) detection algorithm has proved awkward to implement. Attention has instead focused on the simpler vertically-layered architecture. The well-known vertical MIMO detectors, such as zero forcing (ZF), minimum mean squared error (MMSE), maximum likelihood (ML), vertical BLAST (V-BLAST), and several versions of sphere decoding (SD), offer different trade-offs between computational complexity and performance. V-BLAST offers intermediate, but clearly suboptimal performance that has a computational complexity that grows linearly in the number of transmitted layers and in the size M of the symbol constellation. Fouladi Fard, Alimohammad and Cockburn recently proposed a parallel V-BLAST algorithm, which we call F-BLAST, that offers performance that approaches that of optimal ML at the cost of performing V-BLAST in parallel for all M possible values of the symbol in the layer with the weakest expected signal-to-noise ratio. Here we revisit the performance of F-BLAST and show how the degree of parallelism can be reduced while maintaining performance that greatly exceeds that of V-BLAST. The data parallel structure of the new detection algorithms, and their simpler control structure compared to SD, should offer implementation advantages.