Channel Capacity of Differential Amplitude Pulse-Position Modulation (DAPPM) over Indoor Optical Wireless Communications

Differential amplitude pulse-position modulation (AtimesL-DAPPM) over an indoor optical wireless link can be represented as a Markov source transmitted over a finite-state machine channel. The state-transition probabilities that maximize the information rate are determined by using expectation-maximization. Then, the channel capacity of DAPPM is obtained and compared to that of pulse-position modulation (L-PPM) and differential pulse-position modulation (L-DPPM). It is shown that DAPPM achieves a higher capacity and is less sensitive to multipath dispersion than PPM and DPPM