wo kinds of improved SD algorithms for generalised spatial modulation (GSM), termed as the tree search SD (T-SD) and the path search SD (P-SD), are proposed to provide greater complexity reduction compared with the conventional SD algorithms by merging the repeating elements of the vectors. Simulation results show that the proposed T-SD and P-SD can reduce the complexity dramatically while maintaining the optimum bit-error-ratio(BER) performance, especially for high spectral efficiency GSM. Furthermore, P-SD breaks the limitation on the number of transmit antennas and receive antennas.