Space Modulation Techniques

Chapter 5Information Theoretic Treatment for SMTs

Previously discussed space modulation techniques (SMTs) are novel wireless communication systems that deploy multiple transmit antennas at the transmitter and uses spatial symbols to convey additional information bits. They propose a new way to convey information between a source and destination nodes that is not trivial. One of the major elements to fully understand the capabilities of SMTs is the derivation of the capacity for such techniques. Several attempts were made in literature to derive the capacity of SMTs, and different assumptions were made to facilitate such analysis [202–206]. Most existing studies derive SMTs capacity by following conventional multiple–input multiple–output (MIMO) capacity derivation. A common assumption in literature is that SMTs have two information symbols: spatial and signal symbols. Spatial information symbols are represented by the indexes of the different transmit antennas, while signal symbols are drawn from arbitrary signal constellation diagram. However, representing the spatial symbols by the indexes of transmit antennas is not accurate. Assuming for instance that there exist multiple transmit antennas and are located at the same spatial location in space, the size of the spatial constellation diagram is one and no data can be conveyed through spatial symbols. Hence, the indexes of the transmit antennas are not the source of spatial information, and the spatial bits are encoded in the Euclidean ...