Structure optimisation of spatial modulation over correlated fading channels

A unique characteristic of spatial modulation (SM) is the three dimensional constellation diagram. This enables to trade-off traditional signal constellation diagrams with spatial constellation diagrams where the latter is defined by the physical antenna array. In this paper we investigate the optimum pairs of signal and spatial constellation sizes with respect to average bit error probability (ABEP) and energy efficiency. The analysis is performed for varying antenna correlations and channel conditions. Both numerical and closed-form results are presented which show that a significant performance gain can be obtained when the optimal constellation pairs are used.