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  • Research Article
  • Open Access

Differential Amplitude Pulse-Position Modulation for Indoor Wireless Optical Communications

EURASIP Journal on Wireless Communications and Networking20052005:542578

  • Received: 31 March 2004
  • Published:


We propose a novel differential amplitude pulse-position modulation (DAPPM) for indoor optical wireless communications. DAPPM yields advantages over PPM, DPPM, and DH-PIM in terms of bandwidth requirements, capacity, and peak-to-average power ratio (PAPR). The performance of a DAPPM system with an unequalized receiver is examined over nondispersive and dispersive channels. DAPPM can provide better bandwidth and/or power efficiency than PAM, PPM, DPPM, and DH-PIM depending on the number of amplitude levels and the maximum length of a symbol. We also show that, given the same maximum length, DAPPM has better bandwidth efficiency but requires about and more power than PPM and DPPM, respectively, at high bit rates over a dispersive channel. Conversely, DAPPM requires less power than DH-PIM . When the number of bits per symbol is the same, PAM requires more power, and DH-PIM less power, than DAPPM. Finally, it is shown that the performance of DAPPM can be improved with MLSD, chip-rate DFE, and multichip-rate DFE.


  • differential amplitude pulse-position modulation
  • optical wireless communications
  • intensity modulation and direct detection
  • decision-feedback equalization

Authors’ Affiliations

Department of Electrical and Computer Engineering, University of Victoria, P.O. Box 3055, STN CSC, V8W 3P6, BC, Victoria, Canada


© Sethakaset and Gulliver 2005

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.