Capacity Bounds and High-SNR Capacity of MIMO Intensity-Modulation Optical Channels

Anas Chaaban, Zouheir Rezki, Mohamed-Slim Alouini

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


The capacity of the intensity modulation direct detection multiple-input multiple-output channel is studied. Therein, the nonnegativity constraint of the transmit signal limits the applicability of classical schemes, including precoding. Thus, new ways are required for deriving capacity bounds for this channel. To this end, capacity lower bounds are developed in this paper by deriving the achievable rates of two precodingfree schemes: Channel inversion and QR decomposition. The achievable rate of a DC-offset SVD-based scheme is also derived as a benchmark. Then, capacity upper bounds are derived and compared against the lower bounds. As a result, the capacity at high signal-to-noise ratio (SNR) is characterized for the case where the number of transmit apertures is not larger than the number of receive apertures, and is shown to be achievable by the QR decomposition scheme. This is shown for a channel with average intensity or peak intensity constraints. Under both constraints, the high-SNR capacity is approximated within a small gap. Extensions to a channel with more transmit apertures than receive apertures are discussed, and capacity bounds for this case are derived.
Original languageEnglish (US)
Pages (from-to)3003-3017
Number of pages15
JournalIEEE Transactions on Wireless Communications
Issue number5
StatePublished - Feb 19 2018

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The work of Z. Rezki is supported in part by the Qatar National Research Fund (a member of Qatar Foundation) under Grant NPRP 9-077-2-036. The statements made herein are solely the responsibility of the authors.


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