Optimal Power Allocation in SM-OFDM System Based on Visible Light Communications

Spatial Modulation is a kind of spatial multiplexing schemes conveying information by the location of transmit antennas and spatial modulation (SM) along with OFDM can be applied to visible light communications for higher data rates. The closed form of symbol error rate (SER) in optical SM-OFDM communication system is derived in this paper. SER is a convex function of power allocation coefficients, therefore there exist optimal allocation coefficients minimizing SER. The optimal allocation coefficients are derived for different channels and numbers of transmit antennas. Analytical results are validated by Monte Carlo simulation results and these results show that a significant SER improvement is obtained by using the power allocation. In addition, the optimal allocation coefficients are affected by the channel and number of transmitters.