Virtual Spatial Modulation with Diversity Improvement

This paper proposes a novel generalised pre-coding aided spatial modulation (GPSM) scheme, called generalised virtual spatial modulation (GVSM), which performs index modulation on the virtual parallel channels obtained by the singular value decomposition (SVD) of multiple-input multiple-output (MIMO) channels. To improve the diversity performance, the coordinate interleaving technique is further introduced into GVSM, resulting in so-called coordinate interleaved GVSM (CI-GVSM), in which the real and imaginary parts of two complex symbols are interleaved and transmitted over strong and weak eigen-modes. A closed-form upper bound on the average bit error probability (ABEP) applicable to both GVSM and CI-GVSM is derived, followed by the asymptotic performance analysis that reveals the error floor and diversity order under imperfect and perfect channel estimation, respectively. Numerical and simulation results corroborate our analysis and show that the proposed GVSM and CI-GVSM outperform the existing GPSM schemes at the same spectral efficiency.