Network Coding And Its Applied Research In The P2p Content Distribution

Peer dynamics (departure or failure) in peer-to-peer (P2P) networks disrupts the downloading process to the peers. Previous works on fault resilience include peer selection and overlay topology organization. Random network coding based on the generation concept is a practical approach to implement network coding for data networks in general. If we model the generations as blocks distributed by a seed in a P2P network and the disruptions caused by peer dynamics as packet losses, random network coding can be applied in P2P networks.In this thesis, we propose a network coding scheme using a concept we call generation crossing that allows some overlap in packets transmitted between successive generations. We group the native packets into generations where any two successive generations share some packets, referred to as crossing. The extinct generation (lost packets) may be revived with the assistance of the crossing packets from other generations. This can be regarded as a form of cooperative decoding. In order to enhance the contribution of the crossing packets to cooperative decoding, we also introduce a full cardinality precode, which enables a peer to reconstruct the original data file when only a subset of data blocks is received. We show that the success rate for the whole file to be delivered to peers increases remarkably with a small number of overlapped packets between successive generations.