Content distribution support in modern wireless and wired networks

Abstract. This thesis focuses on the distribution of live video streams over Peer-to-Peer (P2P) networks. Our approach to the problem is to preserve the inherent advantage offered by the P2P architecture and ex-ploit it to enhance the quality experienced by the end user, by revealing those subtle processes that may affect the overall system performance and require a different design perspective that suits the new distribution environment. In the first part of this thesis we examine the impact of the adopted playout policy on the performance of P2P live streaming sys-tems. We argue and demonstrate that (popular) playout policies which permit the divergence of the playout points of different nodes can dete-riorate drastically the performance of P2P live streaming. Consequently, we argue in favor of keeping different playout points ”near-in-time”, even if this requires sacrificing (dropping) some late frames. In the second part of this thesis we deal with the natural instability of the distribution en-vironment which poses a major problem in the case of a video streaming service. Taking into account the proven correlation between the experi-enced quality at each node and node churn we manage to improve the stability (lower node churn) and the offered quality of the system.