Achieving Minimum Error in MISO Optical Spatial Modulation

In this paper, a novel light emitting diode (LED) power control algorithm is proposed for an optical spatial modulation (OSM) based communications system. The proposed algorithm constantly controls the power of the LEDs employed at the transmitter side to provide the minimum overall symbol error ratio (SER) for a mobile user. An exact analytical SER expression is obtained for the general multiple-input-single-output (MISO) OSM system. It is shown that the proposed algorithm solves a convex optimization problem where linear constraints are used to minimize the SER. Finally, a 2 x 1 MISO-OSM example is presented to prove the effectiveness of the proposed algorithm. The computer simulations show that the power adaptive MISO-OSM system with the proposed algorithm achieves the average SER of 3.87 x 10(-6) for 30 dB signal-to-noise-ratio (SNR).