Proposal of Optical Wireless Turbo Coded System with Hybrid PPM-OOK Signalling

As typical binary modulation schemes for the intensity modulation / direct detection (IM/DD) optical wireless communication, on-off keying (OOK) and binary pulse position modulation (BPPM) are well known. Although OOK has higher transmission efficiency than BPPM, BPPM is superior to OOK in terms of communication reliability. It is expected to create a better modulation scheme by fusing OOK and PPM. In this paper, an optical wireless turbo coded system using a new signalling scheme called hybrid PPM-OOK signalling (HPOS) is proposed. The information bit stream of the turbo coded system is represented by PPM signalling and the parity bit streams are indicated by OOK signalling. The decision for OOK is optimized via the PPM signal. The proposed system is evaluated through computer simulation in optical wireless channel. The effective information rate performances (i.e. channel capacity) of the proposed system are compared with those of the conventional OOK turbo coded system and BPPM turbo coded system. As results, the proposed system outperforms the conventional OOK system and BPPM system.