Pulse-position-width modulation scheme in wireless optical communication system

In order to improve the bandwidth efficiency of the L-level pulse-position modulation (PPM) scheme used in wireless optical communication, a new modulation scheme, L-level pulse-position-width modulation (PPWM) scheme was proposed based on L-level PPM scheme and L-level pulse-width modulation (PWM) scheme. It increases the bandwidth efficiency through reducing the power efficiency properly. The PPWM signal's power efficiency and bandwidth efficiency are analyzed and the packet error rate in the weak turbulence channel model is also derived and compared with that in other modulation schemes. The result shows that the L-level PPMPWM scheme has low bit error rate, high power efficiency, better bandwidth efficiency, and low packet error rate.