A novel multiple access scheme based on spatial modulation MIMO

Spatial modulation (SM) is a unique single-stream Multiple-Input Multiple-Output (MIMO) transmission technique. Unlike conventional MIMO schemes, SM activates a single transmit antenna at any time instance, and therefore completely avoids inter-channel interference in single user scenarios. When considering multiple users, precoding techniques can be applied to realise multi-user SM (MU-SM) and coordinate multi-user interference. The transmit antennas in MU-SM are divided into groups, and each group is dedicated to one user. This means that the management and selection of antennas are crucial with respect to capacity in MU-SM. Therefore, we propose a novel multiple access method in this paper, named spatial modulation multiple access (SMMA). Unlike in MU-SM where a fixed antenna arrangement is used, the concept of SMMA is to adaptively allocate the transmit antennas to multiple users. Results show that SMMA obtains a signal-to-noise ratio (SNR) gain of up to 6 dB over MU-SM. More importantly, the performance of SMMA degrades insignificantly as the number of users increases.