Space Shift Keying (SSK) Modulation with Partial Channel State Information: Optimal Detector and Performance Analysis over Fading Channels

Space Shift Keying (SSK) modulation is a new and recently proposed transmission technology for Multiple-Input-Multiple-Output (MIMO) wireless systems, which has been shown to be a promising low-complexity alternative to several state-of-the-art MIMO schemes. So far, only optimal or heuristic transceivers with Full Channel State Information (F-CSI) at the receiver have been investigated, and their performance analyzed over fading channels. In this paper, we develop and study the performance of the optimal Maximum-Likelihood (ML) detector with unknown phase reference at the receiver (i.e., Partial-CSI, P-CSI, knowledge). A very accurate analytical framework for the analysis and optimization of this novel detector over generically correlated and non-identically distributed Nakagami-{m} fading channels is proposed, and its performance compared to the optimal receiver design with F-CSI. Numerical results will point out that: i) the performance of SSK modulation is significantly affected by the characteristics of fading channels, e.g., channel correlation, fading severity, and, particularly, power imbalance among the transmit-receive wireless links, and ii) unlike ordinary modulation schemes, there is a substantial performance loss when the receiver cannot exploit the phase information for optimal receiver design. This latter result highlights the importance of accurate and reliable channel estimation mechanisms for the efficient operation of SSK modulation over fading channels. Analytical frameworks and theoretical findings will also be substantiated via Monte Carlo simulations.