Energy-Based Maximum Likelihood Detector for GSSK in MIMO-ABC Systems

We propose a novel, low complexity energy-based maximum likelihood (EML) detector for a generalized space shift keying (GSSK)-enabled multiple-input multiple-output (MIMO) ambient backscatter communication (ABC) system. The proposed scheme exploits the multiple antenna structure of the system to achieve a lower error rate performance than the conventional single-antenna ABC systems. The proposed EML GSSK detector does not require the perfect knowledge of the ambient source signal. To gain insights into the performance of the proposed scheme, we derive the exact pairwise error probability (PEP) of the EML detector, and further obtain an upper bound on the probability of error. We also derive a simple asymptotic PEP expression, as the number of antennas of the reader becomes large. We validate our analysis through Monte Carlo simulations, and show that the performance loss due to the approximations employed in our analysis is small. The performance of EML detector is also compared with the conventional ML detector and the loss in performance is studied.