Digital pulse interval modulation for optical communications

This article presents a study of digital pulse interval modulation for opti cal wireless communications using intensity modulation with direct detectio n. DPIM code properties are discussed, and expressions for the transmission capacity, power spectrum, and error probability are presented. We show tha t for a given number of bits per symbol, DPIM has higher transmission capac ity, a similar spectral profile, and only a marginally inferior error proba bility performance compared with pulse position modulation, and is rather l ess complex to implement. Finally, problems associated with the nonuniform symbol length characteristics of DPIM together with possible solutions are discussed.