Decision-feedback equalization of pulse-position modulation on measured nondirected indoor infrared channels

We examine the performance of two decision-feedback equalizers (DFE's) for pulse-position modulation (PPM) on measured nondirected indoor infrared cha nnels with intersymbol interference. PPM offers high average-power efficien cy, but on ISI channels, unequalized PPM suffers severe performance penalti es. We have previously examined the performance of the maximum-likelihood s equence detector (MLSD), and found that it yields significant improvements, However, the MLSD often requires such large complexity and delay that it m ay be impractical, We investigate suboptimal, reduced-complexity equalizati on techniques for PPM, providing a performance analysis of zero-forcing chi p-rate and symbol rate DFE's, Our results show that a symbol-rate DFE provi des performance that closely approaches that of the optimal MLSD.