Free-Space Optical Communications: Capacity Bounds, Approximations, and a New Sphere-Packing Perspective

Handle URI:
http://hdl.handle.net/10754/552096
Title:
Free-Space Optical Communications: Capacity Bounds, Approximations, and a New Sphere-Packing Perspective
Authors:
Chaaban, Anas; Morvan, Jean-Marie; Alouini, Mohamed-Slim ( 0000-0003-4827-1793 )
Abstract:
The capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel is studied. It is shown that for an IM-DD channel with generally input-dependent noise, the worst noise at high SNR is input-independent Gaussian with variance dependent on the input cost. Based on this result, a Gaussian IM-DD channel model is proposed where the noise variance depends on the optical intensity constraints only. A new recursive approach for bounding the capacity of the channel based on sphere-packing is proposed, which leads to a tighter bound than an existing sphere-packing bound for the channel with only an average intensity constraint. Under both average and peak constraints, it yields bounds that characterize the high SNR capacity within a negligible gap, where the achievability is proved by using a truncated Gaussian input distribution. This completes the high SNR capacity characterization of the channel, by closing the gap in the existing characterization for a small average-to-peak ratio. Simple fitting functions that capture the best known achievable rate for the channel are provided. These functions can be of significant practical importance especially for the study of systems operating under atmospheric turbulence and misalignment conditions. Finally, the capacity/SNR loss between heterodyne detection (HD) systems and IM-DD systems is bounded at high SNR, where it is shown that the loss grows as SNR increases for a complex-valued HD system, while it is bounded by 1.245 bits or 3.76 dB at most for a real-valued one.
KAUST Department:
Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
Issue Date:
Apr-2015
Type:
Technical Report
Sponsors:
This work is supported in part by King Abdulaziz City of Science and Technology (KACST) under grant AT-34-145.
Appears in Collections:
Technical Reports; Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorChaaban, Anasen
dc.contributor.authorMorvan, Jean-Marieen
dc.contributor.authorAlouini, Mohamed-Slimen
dc.date.accessioned2015-05-03T06:07:22Zen
dc.date.available2015-05-03T06:07:22Zen
dc.date.issued2015-04en
dc.identifier.urihttp://hdl.handle.net/10754/552096en
dc.description.abstractThe capacity of the intensity-modulation direct-detection (IM-DD) free-space optical channel is studied. It is shown that for an IM-DD channel with generally input-dependent noise, the worst noise at high SNR is input-independent Gaussian with variance dependent on the input cost. Based on this result, a Gaussian IM-DD channel model is proposed where the noise variance depends on the optical intensity constraints only. A new recursive approach for bounding the capacity of the channel based on sphere-packing is proposed, which leads to a tighter bound than an existing sphere-packing bound for the channel with only an average intensity constraint. Under both average and peak constraints, it yields bounds that characterize the high SNR capacity within a negligible gap, where the achievability is proved by using a truncated Gaussian input distribution. This completes the high SNR capacity characterization of the channel, by closing the gap in the existing characterization for a small average-to-peak ratio. Simple fitting functions that capture the best known achievable rate for the channel are provided. These functions can be of significant practical importance especially for the study of systems operating under atmospheric turbulence and misalignment conditions. Finally, the capacity/SNR loss between heterodyne detection (HD) systems and IM-DD systems is bounded at high SNR, where it is shown that the loss grows as SNR increases for a complex-valued HD system, while it is bounded by 1.245 bits or 3.76 dB at most for a real-valued one.en
dc.description.sponsorshipThis work is supported in part by King Abdulaziz City of Science and Technology (KACST) under grant AT-34-145.en
dc.titleFree-Space Optical Communications: Capacity Bounds, Approximations, and a New Sphere-Packing Perspectiveen
dc.typeTechnical Reporten
dc.contributor.departmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Divisionen
All Items in KAUST are protected by copyright, with all rights reserved, unless otherwise indicated.