A compensation approach of LED nonlinearity based on efficiency evaluation in a visible light communication system

In this work, a practical efficiency evaluation method for InGaN-based LEDs is deduced, in which the internal quantum efficiency and output light power-injection current (L-I) curves can be reconstructed by the injected current I-0 corresponding to the peak quantum efficiency, a given injected current I-1 and the corresponding light output power ratio r. There is good agreement between the calculated result using the proposed method and measured L-I result using the integral sphere system. On this basis, the pre-distortion and post-mitigation is realized for the DC-biased orthogonal frequency division multiplexing (DCO-OFDM) system. It is demonstrated that the bit error rate (BER) performance of the visible light communication (VLC) system with pre-distortion is much better than the original system even if the estimated I-0 and r values are not very accurate. Furthermore, using adaptive post-mitigation based on the proposed LED evaluation method, the performance of VLC system can also be improved obviously. (C) 2019 The Japan Society of Applied Physics