Multiple pulse amplitude and position modulation for the optical wireless channel

The increasing demand for high speed optical wireless applications has strongly motivated recent research work towards improvement in the throughput of the optical channels. Numerous modulation schemes have been studied in this area. Multiple pulse position modulation (MPPM) has proved to be more power efficient than other modulation schemes such as on off keying (OOK), pulse amplitude modulation (PAM), and pulse position modulation (PPM). However, MPPM is not a strong candidate when the bandwidth efficiency is taken into account. To achieve optimum power and bandwidth efficiency, a new modulation scheme, multiple pulse amplitude and position modulation (MPAPM), is proposed. This paper analyses the proposed modulation scheme in terms of bandwidth requirements and power efficiency. The new scheme delivers an improvement in energy per unit bandwidth of 10 dB.