Abstract
In non-coherently coded space-time modulated transmission schemes, the conventional noncoherent MAP (maximum a posteriori) detector, which performs an exhaustive search among all possibly transmitted space-time matrices, is too complex to be performed, if the conveyed data bits within the coherence block is high. In this paper, we propose a noncoherent MAP detector with a very low detection complexity for the orthogonally designed USTM (unitary space-time modulation) signals. In addition, we prove that the detected soft LLR (loglikelihood ratio) values are independent of the a priori soft LLR values sent from the outer decoder. Hence, iterative detection and decoding between the detector and the decoder can be avoided to reduce the receiving complexity without performance degradation. Compared to the scheme using the conventional noncoherent MAP detector, the proposed scheme are able to provide the same error-rate performance, and a much lower detection complexity.