Capacity of Differential Pulse-Position Modulation (DPPM) over Nakagami-m Fading Channels

The capacity of differential pulse-position modulation (DPPM) is considered in this paper. Since the formula of Shannon Capacity is effective only in the AWGN channel with continuous-valued inputs and outputs, while the channel employing M-ary DPPM modulation has discrete-valued inputs and continuous-valued outputs, we derive the modified formula which applies to calculate the capacity of a UWB system with DPPM over an AWGN channel. Then the result is extended to Nakagmi-m fading channels. Monte Carlo simulation is employed to analyze the relationship between the capacity and the signal to noise ratio (SNR), and the relationship between reliable communication distance and channel capacity subject to FCC Part 15 rules is also given. The results show that DPPM is superior to PPM in terms of data transfer rate and capacity performance.