Trellis-Coded Multiple-Pulse Position Modulation for Wireless Infrared Communications

Abstract

We present new trellis codes based on multiple-pulse position modulation (MPPM) for wireless infrared communication. We assume that the receiver uses maximuml-ikelihood sequence detection to mitigate the effects of channel dispersion, which we model using a first-order low-pass filter. Compared to trellis codes based on PPM, the new codes are less sensitive to multipath dispersion and offer better power efficiency when the desired bit rate is large compared to the channel bandwidth. For example, when the bit rate equals the bandwidth, trelliscoded (y)-MPPM requires 1.4 dB less optical power than trellis-coded 16-PPM having the same constraint length.