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Spatial modulation (SM) can transmit additional data bits by selecting antennas and avoids synchronization and interferences among antennas. Differential SM (DSM) is a noncoherent technique of SM, but it is less bandwidth efficient than SM. This paper proposes a novel DSM scheme called long-block DSM (LB-DSM), whose block is longer than the original DSM’s. Each block of LB-DSM consists of two parts. One part is the block of the original DSM, and the other is similar to SM. With the aid of the latter part, the data rate of LB-DSM is higher than that of DSM. Besides, we propose bit mapping and low-complexity noncoherent maximum-likelihood detection for LB-DSM, by which LB-DSM is less complicated than DSM. In addition to higher bandwidth efficiency and lower decoding complexity, distance analysis and computer simulation results indicate that LB-DSM provides better error performance than DSM for 8PSK (eight-ary phase shift keying). Furthermore, the idea of LB-DSM is applied to generalized DSM (GDSM), which activates more than one transmit antenna each time. The resulting scheme, called long-block GDSM, offers better bandwidth efficiency and error performance than GDSM. |
