Study of BitTorrent for file sharing in ad hoc networks

A mobile ad-hoc network(MANET) is a collection of mobile nodes dynamically forming a temporary network without any fixed infrastructure. The topology of MANETs changes dynamically causing frequent node failures and network partitions. Sharing of information in such networks is a challenging task. MANETs and peer-to-peer networks share several common characteristics such as self-configuration, decentralized architecture and dynamic topology. These similarities are appealing for implementing peer-to-peer systems in MANETs. The peer-to-peer protocols proposed for the Internet are not directly applicable for mobile ad-hoc networks due to the dynamic characteristics of MANETs. This paper implements BitTorrent for MANETs(BTM) which uses random piece download to clients. We have also implemented other download mechanisms - rarest piece and random first piece with rarest piece and strict priority. We compare the performance of these three versions in terms of average goodput, average energy consumption, control overhead and average latency. Our performance study shows that the last performs better than pure rarest piece and is much better than random download. We also compared the performance of File Transfer Protocol(FTP) with the three versions of BTM. The results indicate that FTP is better than the three versions of BTM for small file sizes, in terms of latency of download whereas in all other parameters, BTM performs better. As the file size increases, BTM shows better performance than FTP even for latency.