A Cross-layer Decentralized BitTorrent for Mobile Ad hoc Networks

S. Rajagopalan and C. Shen (University of Delaware)
MOBIQUITOUS 2006
Abstract
In recent years, a number of P2P systems, for instance, Gnutella, KaZaA, Napster, and BitTorrent, have been proposed for the wired Internet. However, these protocols are not immediately applicable to the mobile ad hoc networks (MANETs) owing to the extreme conditions MANETs operate
under. Of the above protocols, although BitTorrent has several features which make it an ideal candidate for adapting to MANETs, the current specification of BitTorrent has several drawbacks which make a straightforward implementation of BitTorrent for MANETs an undesirable solution.
In this paper, we investigate a straightforward implementation of BitTorrent [6, 3] in MANETs, termed BTI, and compare its performance with a cross-layer adaptation of BitTorrent for MANETs, termed BTM. We resolve the issues of centralized control and single point of failure in BTI by
proposing mechanisms to decentralize the BitTorrent model for MANETs and provide resource/data redundancy to improve the protocol performance. In addition, the cross-layer model of BTM is more suited for use in a MANET. Our performance comparison studies show that BTM is able to outperform
BTI in terms of goodput, and the number of pieces delivered, in the context of amortizing the client download expenses over more connections (that is, BTM has a higher average peer degree).

Mobile Ad hoc Network

A Mobile Ad hoc wireless Network (MANET) is a network established for a special, often extemporaneous service customized to applications.
The ad hoc network is typically set up for a limited period of time, in an environment that may change from application to application.
As a difference from the Internet where the TCP/IP protocol suite supports a vast range of applications, in the MANET the protocols are tuned to a specific customer and application.
The customers move and the environment may change dynamically and unpredictably.
For the MANET to retain its efficiency, the ad hoc protocols at various layers may need to self-tune to adjust to environment, traffic and mission changes.
From these properties emerges the vision of the MANET as an extremely flexible, malleable and yet robust and formidable network architecture.

Mario Gerla et al. (Dealing with Node Mobility in Ad Hoc Wireless Network)