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Proceedings Paper

Collaborative Beamfocusing Radio (COBRA)
Author(s): Jeremy P. Rode; Mark J. Hsu; David Smith; Anis Husain
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Paper Abstract

A Ziva team has recently demonstrated a novel technique called Collaborative Beamfocusing Radios (COBRA) which enables an ad-hoc collection of distributed commercial off-the-shelf software defined radios to coherently align and beamform to a remote radio. COBRA promises to operate even in high multipath and non-line-of-sight environments as well as mobile applications without resorting to computationally expensive closed loop techniques that are currently unable to operate with significant movement. COBRA exploits two key technologies to achieve coherent beamforming. The first is Time Reversal (TR) which compensates for multipath and automatically discovers the optimal spatio-temporal matched filter to enable peak signal gains (up to 20 dB) and diffraction-limited focusing at the intended receiver in NLOS and severe multipath environments. The second is time-aligned buffering which enables TR to synchronize distributed transmitters into a collaborative array. This time alignment algorithm avoids causality violations through the use of reciprocal buffering. Preserving spatio-temporal reciprocity through the TR capture and retransmission process achieves coherent alignment across multiple radios at ~GHz carriers using only standard quartz-oscillators. COBRA has been demonstrated in the lab, aligning two off-the-shelf software defined radios over-the-air to an accuracy of better than 2 degrees of carrier alignment at 450 MHz. The COBRA algorithms are lightweight, with computation in 5 ms on a smartphone class microprocessor. COBRA also has low start-up latency, achieving high accuracy from a cold-start in 30 ms. The COBRA technique opens up a large number of new capabilities in communications, and electronic warfare including selective spatial jamming, geolocation and anti-geolocation.

Paper Details

Date Published: 28 May 2013
PDF: 11 pages
Proc. SPIE 8753, Wireless Sensing, Localization, and Processing VIII, 87530J (28 May 2013); doi: 10.1117/12.2018142
Show Author Affiliations
Jeremy P. Rode, Ziva Corp. (United States)
Mark J. Hsu, Ziva Corp. (United States)
David Smith, Ziva Corp. (United States)
Anis Husain, Ziva Corp. (United States)

Published in SPIE Proceedings Vol. 8753:
Wireless Sensing, Localization, and Processing VIII
Sohail A. Dianat; Michael David Zoltowski, Editor(s)

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