Energy-Efficient Spatial Modulation Over MIMO Frequency-Selective Fading Channels

In this paper, an energy-efficient spatial modulation (SM), which is called joint space and time dispersion modulation (STdM), is proposed for the multiple-input multiple-output (MIMO) frequency-selective fading channel. The proposed scheme extends the recent concept of SM to both space and time dispersion dimensions. Specifically, in the STdM scheme, only 1 out of N_t transmit antennas (TAs) is active in 1 out of L-1 channel time slots, where N_t and L are the number of TAs and the channel time dispersion length, respectively. Moreover, the information is carried by three units: active-channel time-slot index, active-antenna index, and modulation symbol. Compared with SM, the proposed STdM employs a new dimension, i.e., the passive-channel time slot, to convey information. Therefore, the proposed STdM is expected to have energy efficiency superiority over SM, similar to the superiority of SM over the conventional MIMO scheme, which is then validated by simulations.