On the achievable performance-complexity tradeoffs of relay-aided space shift keying

Future cellular networks require transmission technologies and protocols that are energy-efficient, and that can meet the growing demands of mobile data traffic with the best performance versus complexity tradeoff. The recently proposed single-RF space shift keying (SSK-) multiple-input-multiple-output (MIMO) transmission scheme is one of such physical layer technology that satisfies these criteria. In general, SSK requires a large number of antenna elements (with only one of them active) at the transmitter for high data rate transmission. This makes SSK particularly useful for the downlink of cellular systems. In this paper, we exploit the virtual MIMO concept to design SSK transmission schemes for the uplink of cellular networks. The idea is to take advantage of nearby nodes to the mobile terminal as a 'virtual spatial-constellation diagram,' where the information can be encoded and transmitted to the final destination. By taking into account the virtual nature of the spatial-constellation diagram, we develop advanced demodulation techniques, perform a comprehensive mathematical analysis, as well as analyze the system complexity and energy consumption. It is also shown that the proposed scheme is capable of outperforming certain state-of-the-art protocols.