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Numerical analysis of MPPM performance in Free Space Laser Communications

In this paper, we study on the fundamental principle of MPPM (m-ary pulse position modulation) in free space laser communications. Firstly we discuss the definition of performance parameters, such as signalling ability, transmission efficiency, and bandwidth utilization rate. Then we compare the performance of MPPM with that of PPM (pulse position modulation), such as bandwidth and power efficiency. Finally we discuss the channel capacity, Information transmission rate and the energy efficiency for MPPM and PPM channel, and give the expression of channel capacity in optical MPPM channel with guard interval.