Multi-User Linear Precoding for Downlink Generalized Spatial Modulation Systems

In this letter, a linear precoding scheme is proposed for downlink (DL) multi-user (MU) generalized spatial modulation (GSM) systems. The proposed precoding scheme achieves, not only inter-user interference (IUI) free, but also maximum signal-to-noise ratio (SNR). The former achievement leads to higher multiplexing gain, while the later results in higher diversity gain. By formulating the precoder design as a constrained optimization problem, the optimal precoding vectors are derived by using singular value decomposition (SVD). Outage and ergodic capacities of the proposed scheme are then analyzed, and compared to that of the conventional GSM scheme and the MU zero-forcing (ZF) transmit beamforming scheme by simulations. Simulation results indicate that the proposed scheme can effectively eliminate the IUI, and achieve significant diversity gain.