Abstract
Non-orthogonal multiple access (NOMA) can increase the overall spectral efficiency of visible light communication (VLC) system. In this paper, we proposed a novel scheme to improve the bit error rate (BER) performance of a two-user NOMA VLC system by adjusting superposition constellation. The corresponding closed-form BER expressions are derived. Convex optimization is used to find the optimal parameters of the adjusted superposition constellation, where the overall BER is minimized. The BER performances are evaluated by theoretical analysis, Monte-Carlo (MC) simulation and experiment. The results illustrate that 8.9-dB and 8.1-dB signal-to-noise ratios (SNRs) are reduced to achieve BER of 10-3 for the two users, whose power allocation coefficients are 0.6 and 0.4, respectively.
Highlights
In the last decade, visible light communication (VLC) has aroused many researchers’ interests [1,2,3]
In [11], Shi et al investigated the performance of offset quadrature amplitude modulation (OQAM) orthogonal frequency division multiplexing (OFDM) based multiple input multiple output (MIMO) non-orthogonal multiple access (NOMA) VLC system, and studied its advantages over conventional MIMO system
The results show that the signal-to-noise ratios (SNRs) to achieve the bit error rate (BER) of 10−3 decrease 8.9 dB and 8.1 dB for the two users, when their corresponding power allocation coefficients are 0.6 and 0.4, respectively
Summary
Visible light communication (VLC) has aroused many researchers’ interests [1,2,3]. NOMA is an attractive access means to let multiple terminals use the same time and frequency resources. It provides high spectral efficiency, high flexibility, and improved fairness [8, 9]. Optimization of superposition constellation is another approach to improve the performance of NOMA VLC system. We propose a novel superposition constellation adjustment scheme to improve the bit error rate (BER) performance of a two-user NOMA VLC system. In order to obtain the minimized overall BER performance, the parameters in adjusting the constellation are obtained according to convex optimization In such a case, the two users’ BER performances are both improved.
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