Temporal Permutations in Distinct Accumulated Blocks of Space-Time Block-Coded Spatial Modulation

Spatial modulation (SM) is a multi-antenna technique that transmits additional data bits by selecting indexes of transmit antennas. Space-time block coded SM (STBC-SM) increases diversity order compared to the original SM by activating two transmit antennas each time. This paper proposes a novel STBC-SM technique that temporally permutates signals of STBC blocks, allowing for increased data rate by selecting different permutation patterns. The proposed technique, temporal permutations in distinct accumulated blocks (TP-DAB), can be applied to existing STBC-SM schemes to enhance spectral efficiency. We first propose a systematic method to generate permutation patterns of TP-DAB for various numbers of different blocks. Subsequently, we design examples using the obtained permutation patterns. Besides, we propose a low-complexity maximum-likelihood (ML) detector with significantly lower complexity than the original ML receiver. In addition to the benefit of bandwidth efficiency, analytical bounds and computer simulations demonstrate that STBC-SM systems using TP-DAB provide better error performance than the original system.