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Proceedings Paper

Power-efficient multiple-subcarrier modulation scheme for optical wireless communications
Author(s): Byron Yu; Joseph M. Kahn; Roy You
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Paper Abstract

Multiple-subcarrier modulation (MSM) offers several potential advantages for optical wireless systems. MSM makes it possible to perform frequency-division multiplexing, while maintaining the simplicity of intensity modulation and direct detection. Indoor optical wireless systems may be subject to multipath distortion; in such systems, MSM enables transmission at high bit rates with minimal intersymbol interference. The average-power efficiency of MSM is lower than that of baseband modulation techniques, such as on-off-keying or pulse-position modulation, however. We present a technique for improving the average-power efficiency of multiple-subcarrier systems using binary or quadrature phase-shift keying (BPSK, QPSK) with bandlimited pulses, which are, necessarily, not time-limited. In order to insure the non-negativity of the transmitted intensity signal, we use a time-varying bias signal, which is a baseband pulse-amplitude modulation signal also using these pulses. We focus on the problem of designing this time-varying bias signal, which is complicated by the fact that the pulses are not time-limited. We show that the proposed scheme can significantly enhance power efficiency, with only a minimal increase in implementation complexity.

Paper Details

Date Published: 6 December 2002
PDF: 13 pages
Proc. SPIE 4873, Optical Wireless Communications V, (6 December 2002); doi: 10.1117/12.455506
Show Author Affiliations
Byron Yu, Univ. of California/Berkeley (United States)
Stanford Univ. (United States)
Joseph M. Kahn, Univ. of California/Berkeley (United States)
Roy You, Univ. of California/Berkeley (United States)

Published in SPIE Proceedings Vol. 4873:
Optical Wireless Communications V
Eric J. Korevaar, Editor(s)

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