A Grouped Pre-Coding Aided Spatial Modulation for MIMO Systems

Pre-coding aided spatial modulation (PSM) is a recently introduced concept that achieves low complexity and low cost at the receiver. However, it is only suitable for the symmetric or under-determined system due to the utilization of the linear pre-coding. In this paper, a novel PSM-based transmission strategy termed as grouped pre-coding aided spatial modulation (group PSM) is proposed for the over-determined MIMO system where the number of receive antennas is larger than the number of transmit antennas. In our group PSM scheme, the receive antennas are equally divided into several groups. A single receive antenna group is selected during each time slot and the index of the receive antenna group is used for conveying extra information bits. We design a low complexity detection method for the proposed scheme and derive the bit error rate expression. To further improve the performance of group PSM, we propose a power allocation method, where the power allocated for each receive antenna group is optimized based on maximizing the minimum Euclidean distance between received group PSM signal constellations. We also generalize our group PSM scheme in order to improve the multiplexing gain and flexibility, where a particular subset of receive antenna groups is activated so as to convey more information bits. Our simulation results validate the accuracy of the theoretical analysis and demonstrate that both the proposed group PSM and generalized group PSM schemes achieve good performance and significantly increase the scalability of PSM in practice.