Tripling the capacity of wireless communications using electromagnetic polarization

Wireless communications are a fundamental part of modern information infrastructure. But wireless bandwidth is costly, prompting a close examination of the data channels available using electromagnetic waves. Classically, radio communications have relied on one channel per frequency, although it is...

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Bibliographic Details
Published in:Nature (London) 2001-01, Vol.409 (6818), p.316-318
Main Authors: deCarvalho, Robert, Andrews, Michael R, Mitra, Partha P
Format: Article
Language:English
Subjects:
Applied sciences
Capacity
Channel capacity
Channels
Communications
Electromagnetic radiation
Electromagnetic waves
Electromagnetism
Exact sciences and technology
Frequencies
Humanities and Social Sciences
Indoor
Infrastructure
letter
multidisciplinary
Polarization
Propagation through the atmosphere
Radio communications
Radiocommunications
Radiowave propagation
Scattering
Science
Science (multidisciplinary)
Telecommunications
Telecommunications and information theory
Urban areas
Wireless communication
Wireless communications
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Summary:Wireless communications are a fundamental part of modern information infrastructure. But wireless bandwidth is costly, prompting a close examination of the data channels available using electromagnetic waves. Classically, radio communications have relied on one channel per frequency, although it is well understood that the two polarization states of planar waves allow two distinct information channels; techniques such as 'polarization diversity' already take advantage of this. Recent work has shown that environments with scattering, such as urban areas or indoors, also possess independent spatial channels that can be used to enhance capacity greatly. In either case, the relevant signal processing techniques come under the heading of 'multiple-input/multiple-output' communications, because multiple antennae are required to access the polarization or spatial channels. Here we show that, in a scattering environment, an extra factor of three in channel capacity can be obtained, relative to the conventional limit using dual-polarized radio signals. The extra capacity arises because there are six distinguishable electric and magnetic states of polarization at a given point, rather than two as is usually assumed.
ISSN:0028-0836
1476-4687
DOI:10.1038/35053015