Spatially-Averaging Channel Estimation for Spatial Modulation

Spatial modulation (SM) is a unique single-stream, multiple-input multiple-output (MIMO) transmission technique. Unlike multi-steam MIMO schemes, a single transmit antenna is activated in SM at any given time. Therefore, inter-channel interference is completely avoided. In addition, SM requires only one radio-frequency (RF) chain, regardless of the number of transmit antennas used. This key property results in a significant saving in quiescent power of power amplifiers. However, a challenge occurs when channel estimation (CE) is implemented for SM: the transmit antennas have to send pilots sequentially. Thus, in order not to compromise the throughput, the pilot number of each transmit antenna is restricted. This means we focus on improving the CE performance without increasing the number of pilots. In this paper, we propose a novel CE method for SM, in which the channel is jointly estimated across receive antennas. Simulation results show that the proposed approach outperforms the conventional method for various channel correlations between the receive antennas.