Physical Layer Security and Spectral Efficiency Augmentation of Quadrature Spatial Modulation Using Layered Architecture

The recent emergence of quadrature spatial modulation (QSM) as a new modulation concept introduces the idea of transmitting the real part and the imaginary part of the signal constellation symbols on cosine and sine carriers respectively. In this paper, we enhance the spectral efficiency by adding a single layer to the QSM scheme. The proposed scheme known as layered quadrature spatial modulation (LQSM) not only improves the spectral efficiency of QSM scheme, but also ensures the secrecy of confidential information. The confidential information is passed through XOR Logic Unit, which generates fake bits to confuse the passive eavesdropper. Simulation results show that the BER performance at eavesdropper is significantly degraded, whereas BER performance remains unaffected at the desired receiver. It is also observed that LQSM has greater spectral efficiency with slightly degraded BER performance than QSM.