Pulse Position Based Modulation Techniques for Optical Communication
Intensity Modulation with Direct Modulation (IM/DM) favors low duty cycle modulation schemes such as Pulse Position Modulation (PPM) and Multiple PPM (MPPM). In this paper, the channel model over IM/DD is introduced. Then, a brief summary is given about some of the modulation techniques used in this area. Finally, some of the pulse position based coded modulation techniques are reviewed. The most practical modulation technique in a wireless optical system is Intensity Modulation and Direct Detection (IM/DD). In this modulation technique, the information is modulated using the instantaneous power of the carrier and special detection devices such as photocurrent diode are used to convert the instantaneous power of the signal to an electrical current.