Distributed space shift keying for the uplink of relay-aided cellular networks

Space Shift Keying (SSK) is a novel low-complexity digital modulation technique for multiple antenna wireless systems. In SSK, blocks of data are encoded in the index of a specific transmit antenna of the antenna array, which is switched on for data transmission while all the other antennas radiate no power. Recent results have shown that SSK can outperform, with low computational complexity, conventional modulation schemes when many antennas at the transmitter are available. Unfortunately, this makes SSK a useful candidate for transmission technology only in the downlink of cellular networks. In this paper, by exploiting the concept of virtual antenna arrays, we propose a novel relay-aided scheme to make SSK useful in the uplink of cellular networks. The specific contributions of this paper are as follows: i) the optimal decoder which takes into account decoding errors at the relays is developed; and ii) the performance in terms of Average-Bit-Error-Probability (ABEP), and the energy gain in terms of Relative-Average-Energy-Reduction (RAER) per bit is studied. Via Monte-Carlo simulations, it is shown that the proposed optimal decoder outperforms the conventional decoder for SSK, which does not account for decoding errors at the relays.