Optimizing the BitTorrent performance using an adaptive peer selection strategy

BitTorrent employs a static quota-based peer selection strategy to fixedly allocate upload quotas for the Tit-For-Tat (TFT) choke algorithm and Optimistic Unchoke (OU) algorithm. This static quota allocation scheme would incur a paradox of supply and demand between upload peers and request peers. The paradox of supply and demand means that many request peers stay in the starvation state while many upload quotas stay in the idleness state. We propose a dynamic quota-based peer selection strategy, where request peers are classified by the principle of investment return and each upload peer adaptively allocates upload quotas for the TFT and OU algorithms according to dynamically changed numbers of different request peers. Simulation experiments show that our dynamic quota allocation scheme can eliminate the paradox of supply and demand, increase the resource utility ratio of upload peers, and decrease the file download time, at the cost of uploading more a few file blocks for each upload peer.