Application Level QoS in Multimedia Peer-to-Peer (P2P) Networks

In peer-to-peer (P2P) overlay networks, each peer process (peer) can play a role of not only client but also server. Here, multimedia contents are in nature distributed in peers by downloading and caching. A peer may have a full replica and another peer may have only apart, even less qualified version of a multimedia content like monochromatic version of a fully colored movie. Here, a peer which transmits multimedia contents and a peer which receives the contents are referred to source and receiver peers, respectively. In addition, a peer on a mobile computer is moving in the network. This means, not only receiver peers bot also source peers are moving. In this paper, we would like to discuss how source peers efficiently deliver multimedia contents to receiver peers in a streaming model, where quality of service (QoS) supported by the peers and communication channels are dynamically changing, possibly according to the movements of the peers. It is critical to support a receiver peer with enough QoS to satisfy the receiver's requirements, e.g. play a fully colored video movie in the streaming service in change of QoS of networks and peers. In this paper, we discuss a multi-source streaming protocol where a receiver peer can receive packets of a multimedia content from a source peer which can support enough QoS out of multiple source peers. If a current source peer which supports the receiver peer is expected to support less QoS, another source peer takes over the source peer and starts sending packets of the multimedia content.