High-Diversity Bandwidth-Efficient Space-Time Block Coded Differential Spatial Modulation

By choosing indexes of antennas, differential spatial modulation (DSM) transmits additional data bits without increasing power consumption, radio-frequency circuits, and pilot overhead. Space-time block coded DSM (STBC-DSM) is a DSM scheme combined with STBC to enhance diversity. In our earlier work, we propose a bandwidth-efficient STBC-DSM (BE-STBC-DSM) scheme, which interleaves the transmitted symbols. However, the transmit diversity order of existing STBC-DSM schemes is only two. In this paper, we propose an STBC-DSM scheme whose transmit diversity order is four, called high-diversity BE-STBC-DSM (HD-BE-STBC-DSM), by replacing the
$2\times 2$
STBC with a full-diversity
$4\times 4$
STBC in BE-STBC-DSM. Because the interleaving patterns in the original BE-STBC-DSM cannot be utilized in HD-BE-STBC-DSM, we need to find new interleaving patterns for HD-BE-STBC-DSM. We propose a novel interleaving type, intra-block interleaving, and propose a new design method that differs from the BE-STBC-DSM method. In addition, we propose inter-block interleaving and search patterns of inter-block interleaving. Compared with other DSM schemes with the same diversity order, HD-BE-STBC-DSM is much more spectrally efficient. In addition, HD-BE-STBC-DSM offers the best error performance at high signal-to-noise ratios among all STBC-DSM schemes.