Performance of PPM with maximum-likelihood sequence detection on measured non-directed indoor infrared channels

Examines the performance of pulse-position modulation (PPM) on indoor infrared channels with multipath-induced intersymbol interference (ISI). The authors review maximum-likelihood sequence detection (MLSD) for PPM over ISI channels in additive white Gaussian noise. They evaluate the performance of PPM links other 46 actual measured indoor infrared channels. Detailed performance results are presented for 2-, 4-, 8-, and 16-PPM at bit rates of 10 Mb/s and 30 Mb/s, and these techniques are compared to on-off keying. They results show that when MLSD is employed, 16-PPM provides the best average-power efficiency among the modulation techniques considered.