We previously proposed inverse source coding (ISC) to maximize the transmission rate in visible light communications with dimming capability using ON–OFF keying. First, this paper extends the proposed ISC approach to <i>M</i>-ary pulse amplitude modulation and obtains the optimal probability distributions. Then, dimming capacity is used to compare the existing analog dimming approach, the extended ISC approach, and the hybrid of these approaches. We conclude that ISC is the best approach, and threshold values for adaptive modulation are derived depending on signal quality and dimming target.
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