Capacity Bounds for the Gaussian IM-DD Optical Multiple-Access Channel

Anas Chaaban, Omer M. S. Al-Ebraheemy, Tareq Y. Al-Naffouri, Mohamed-Slim Alouini

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Optical wireless communications (OWC) is a promising technology for closing the mismatch between the growing number of connected devices and the limited wireless network capabilities. Similar to downlink, uplink can also benefit from OWC for establishing connectivity between such devices and an optical access point. In this context, the incoherent intensitymodulation and direct-detection (IM-DD) scheme is desirable in practice. Hence, it is important to understand the fundamental limits of communication rates over an OWC uplink employing IM-DD, i.e., the channel capacity. This uplink, modeled as a Gaussian multiple-access channel (MAC) for indoors OWC, is studied in this paper, under the IM-DD constraints which form the main difference with the standard Gaussian MAC commonly studied in the radio-frequency context. Capacity region outer and inner bounds for this channel are derived. The bounds are fairly close at high signal-to-noise ratio (SNR), where a truncated- Gaussian input distribution achieves the capacity region within a constant gap. Furthermore, the bounds coincide at low SNR showing the optimality of on-off keying combined with successive cancellation decoding in this regime. At moderate SNR, an optimized uniformly-spaced discrete input distribution achieves fairly good performance.
Original languageEnglish (US)
Pages (from-to)3328-3340
Number of pages13
JournalIEEE Transactions on Wireless Communications
Volume16
Issue number5
DOIs
StatePublished - Mar 18 2017

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