Performance analysis of symbol swapped spatial modulation

Abstract

In this work we propose and analyze the performance of an N t × N r multiple-input multiple-output (MIMO) system model that uses spatial modulation (SM) over two time slots. A tuple of information symbols [p, q] is transmitted using SM in first time slot by selecting pth transmitter antenna and illuminating that antenna with qth symbol from either M-ary phase shift keying (MPSK) or M-ary quadrature amplitude modulation (MQAM) constellation. Whereas in the second time slot, the tuple [q, p] is transmitted using SM, thereby q is transmitted using spatial constellation and p is transmitted using either MPSK or MQAM constellation. We call this system model symbol swapped SM (SS-SM). We analyze the performance of SS-SM using an upper bound on the bit error rate (BER) based on pairwise error probability (PEP). We show using simulation results that SS-SM performs better than conventional SM. Further, simulation results also substantiate the upper bound on the BER of SS-SM. Moreover, the improvement in the performance of SS-SM over conventional SM is deduced from the derived PEP.