Ditto: A System for Opportunistic Caching in Multi-Hop Wireless Mesh Networks

Fahad Dogar, Amar Phanishayee, Himabindu Pucha, Olatunji Ruwase, and David Andersen

Abstract

This paper presents the design, implementation, and evaluation of Ditto, a system that opportunistically caches overheard data to improve subsequent transfer throughput in

wireless mesh networks. While mesh networks have been proposed as a way to provide cheap, easily deployable Internet access, they must maintain high transfer throughput to

be able to compete with other last-mile technologies. Unfortunately, doing so is difficult because multi-hop wireless transmissions interfere with each other, reducing the available

capacity on the network. This problem is particularly severe in common gateway-based scenarios in which nearly all transmissions go through one or a few gateways from the

mesh network to the Internet. Ditto exploits on-path as well as opportunistic caching

based on overhearing to improve the throughput of data transfers and to reduce load on the gateways. It uses contentbased naming to provide application independent caching

at the granularity of small chunks, a feature that is key to being able to cache partially overheard data transfers. Our evaluation of Ditto shows that it can achieve significant

performance gains for cached data, increasing throughput by up to 7x over simpler on-path caching schemes, and by up to an order of magnitude over no caching.

Details

Publication typeProceedings
PublisherACM MOBICOM
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