On the impact of imperfect channel knowledge on the performance of quadrature spatial modulation

Quadrature spatial modulation (QSM) is a new multiple-input multiple-output (MIMO) transmission technique that enhances the overall spectral efficiency of conventional spatial modulation (SM). QSM extends the single dimension spatial constellation to another dimension by considering the inphase and the quadrature components of the data symbol. It has been shown that spectral efficiency can be significantly increased while most inherent advantages of SM are retained. In this paper, the impact of Gaussian imperfect channel estimation on the performance of QSM system is studied. A closed-form expression for the pair-wise error probability (PEP) of generic QSM system is derived and used to calculate a tight upper bound of the Average Bit Error Probability (ABEP) over Rayleigh fading. Also, simple asymptotic expression is derived and analyzed. Obtained Monte Carlo simulation results highlight the accuracy of the conducted analysis.