An Improved Outer Bound on the Storage-Repair-Bandwidth Tradeoff of Exact-Repair Regenerating Codes

Sasidharan, Birenjith and Senthoor, Kaushik and Kumar, Vijay P (2014) An Improved Outer Bound on the Storage-Repair-Bandwidth Tradeoff of Exact-Repair Regenerating Codes. In: IEEE International Symposium on Information Theory (ISIT), JUN 29-JUL 04, 2014, 2014 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY (ISIT), pp. 2430-2434.

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Abstract

While the tradeoff between the amount of data stored and the repair bandwidth of an (n, k, d) regenerating code has been characterized under functional repair (FR), the case of exact repair (ER) remains unresolved. It is known that there do not exist ER codes which lie on the FR tradeoff at most of the points. The question as to whether one can asymptotically approach the FR tradeoff was settled recently by Tian who showed that in the (4, 3, 3) case, the ER region is bounded away from the FR region. The FR tradeoff serves as a trivial outer bound on the ER tradeoff. In this paper, we extend Tian's results by establishing an improved outer bound on the ER tradeoff which shows that the ER region is bounded away from the FR region, for any (n; k; d). Our approach is analytical and builds upon the framework introduced earlier by Shah et. al. Interestingly, a recently-constructed, layered regenerating code is shown to achieve a point on this outer bound for the (5, 4, 4) case. This represents the first-known instance of an optimal ER code that does not correspond to a point on the FR tradeoff.

Item Type:	Conference Proceedings
Series.:	IEEE International Symposium on Information Theory
Publisher:	IEEE
Additional Information:	Copy right for this article belongs to the IEEE International Symposium on Information Theory (ISIT), Honolulu, HI, JUN 29-JUL 04, 2014
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	05 Mar 2015 12:54
Last Modified:	05 Mar 2015 12:54
URI:	http://eprints.iisc.ac.in/id/eprint/51012

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