Power Allocation for Visible Light Communications Multi-LED Parallel Superimposed High Speed Transmission

Multiple LED wicks are used in a single lamp to send disparate data under different driving voltages at the same time. At the receiver, a single photodiode(PD) is used to detect the convergence light intensity signals after superposition transmission in visible light channel. Finally, data can be detected and separated by the divergence of driving voltages. Thus the data rate that is multiple times of a single LED wick can be realized. Due to the nonnegative characteristics of LED driving voltage, the detecting algorithm of the receiver based on on-off keying(OOK) modulation is proposed. Meanwhile, joint power allocation scheme of the Signal to noise ratio(SNR) evolution and programing for the electro-optical conversion nonlinearity of LED are proposed. The simulation shows that sacrifice in SNR could make LED work within the linear range of superposition high-speed communication. And the system could achieve the same bit error rate(BER) performance as the un-programming scheme. Comparing with the low-rate scheme under the constant driving voltage of multiple LED wicks, the proposed scheme is more efficient.