How Can Network Coding Help P2P Content Distribution?

It is well known that network coding can enhance the performance of peer-to-peer (P2P) content distribution systems since it benefits block scheduling. In this paper, we introduce our P2P content distribution system "SmartCode" with sparse network coding on PlanetLab. SmartCode uses pre-checking to avoid linearly dependent blocks being transmitted. Under the same system architecture, we also implement two systems "Ecode" and "LRF". Ecode is also based on sparse network coding, but without pre-checking. LRF is BitTorrent- like, using local-rarest-first for block scheduling. We conduct extensive experiments to compare the performances among the three systems. Experimental results show that the distributing time of SmartCode is reduced by 11% on average and up to 19% compared with LRF, and by 7% on average and up to 16% compared with Ecode. We also conduct experiments to analyze robustness among the three systems under the assumption that peers join in and leave a content distribution session dynamically and the seed leave the session after it has transmitted a fixed percentage of blocks over the total blocks of the content. In dynamical cases, SmartCode outperforms evidently than Ecode and LRF in downloading time and the times of peers completing the downloading.