Precoded Optical Spatial Modulation for Indoor Visible Light Communications

This paper proposes a precoded optical space-domain index modulation scheme for indoor visible light communications, which is based on the optimization of minimum Euclidean distance spatial (OSM) with real-valued constellations. We find that precoding matrix design can be formulated as non-convex quadratically constrained quadratic program (QCQP), whose solution generally intractable. To tackle this problem, we first consider case two transmit antennas ( N t = 2) in OSM and derive closed-form arbitrary M-order pulse amplitude (PAM). Based derived solutions error vector reduction method, then propose low-complexity iterative (LCI) algorithm to identify setup > 2. strike flexible complexity-BER (bit rate) tradeoff, successive convex approximation (SCA)-assisted matrix-based method transform QCQP problem into series linear subproblems, solved by solvers. Simulation results show these proposed algorithms are capable substantially improving system performance compared conventional systems. Besides, symbol-based SCA introduced it shown outperform suboptimal LCI terms BER.