A sequential detection approach for approximate MAP detection in MIMO systems

Soft-decisions from a multiple input multiple output (MIMO) detector are desirable if iterative detection and decoding (IDD) is employed at receivers in MIMO systems. The minimum mean square error (MMSE)-soft cancellation (SC) detector has an excellent trade-off between performance and complexity. By noting that the MMSE-SC detector is an approximate maximum a posteriori probability (MAP) detector, another approximate MAP detector that uses sequential processing is proposed in this paper. The proposed sequential detector can provide a better performance than the MMSE-SC detector, while its complexity is comparable with that of the MMSE-SC detector. An interesting feature of the proposed sequential detector is that the trade-off between complexity and performance can be exploited by a single parameter, which could be an important control parameter in practical implementations.