A synopsis of modulation techniques for wireless infrared communication

A number of modulation techniques have been proposed and thoroughly analysed in literature for optical wireless communication systems. Each modulation technique has its unique attractive features as well as its challenges. Some are very simple to implement and bandwidth efficient like the on-off keying (OOK). Pulse interval modulation (PIM) techniques are reputed for their inherent synchronisation pulse, subcarrier modulation offers increased throughput, resilience to the inter-symbol interference (ISI) and immunity against the fluorescent-light noise near DC, while pulse position modulation (PPM) provides the unparalleled power efficiency in line of sight (LOS) links but the performance degrades severely in dispersed communication channel. There has been an enormous work on the analysis of these and many more modulation techniques under different channel and environmental conditions; we however present here a concise synopsis of the mostly reported wireless infrared modulation techniques.