Optimal Power Allocation in Spatial Modulation OFDM for Visible Light Communications

This paper constructs a model for Optical Spatial Modulation Orthogonal Frequency Division Multiplexing (O-SM-OFDM). It investigates the effects of different power allocation schemes on bit error ratio (BER) performance. Optical features such as the DCO technique, the LED non-linearity and the indoor optical channel are considered. Under power constraint, when making power difference between transmitters, we discussed trade-off between the accuracy of the spatial domain bits detection and that of signal domain bits detection. We investigated the relationship between transmitter power surplus, spatial BER, signal BER, system total BER and signal to noise ratio (SNR). The optimal point of transmission power difference is found to be around 11.5 dB.