Multiple Sub-stream Transmission Mechnism In P2P Live Streaming Systems And Its Performance Analysis

P2P (Peer-to-Peer) streaming technology has become one of the most popularsolutions for Internet multimedia applications, as it can offer better bandwidth scalability,transmission path redundancy and self-organization. Based on the multiple sub-streamtransmission mechanism of Coolstreaming called FD-PA (Fixed Decomposition, PeerAdaptation), considering the peer dynamics on the Internet, an improved multiplesub-stream transmission mechanism called NFD-SPA (Non-Fixed Decomposition, SlowPeer Adaptation) is proposed. Mathematical models and performance analysis arebrought out for these two mechanisms.Firstly, based on the FD-PA mechanism, considering the synchronous transmissiondemand of the multiple sub-streams, regarding the data block arrivals as multiple queueswith homogeneous Poisson arrival processes, the data block forwarding procedure as apure limited polling service, a pure limited symmetric polling model is constructed.Employing an M/G/1queueing with multiple vacations, the system measures in terms ofthe peer buffering length and video continuity level are obtained accordingly.Secondly, taking into account the transmission dynamics of the multiple sub-streamsin the P2P environment, through buffer monitoring and different processing, a novelmultiple sub-stream transmission mechanism called NFD-SPA is proposed. In theNFD-SPA mechanism, by calculating the peer buffering speed periodically, thetransmission speed of multiple sub-streams are divided into four levels, namely, poor,lower, medium and higher, respectively. For the poor speed sub-stream, its parent peerwill be dismissed immediately. For the lower speed sub-stream, the current parents willbe checked firstly to share the transmission task of the low speed sub-stream. Thetransmission task of sub-stream with medium transmission speed keeps fixed.Thirdly, based on the NFD-SPA mechanism, considering the assignment flexibilityof the data transmission task, regarding the data block arrivals of different sub-streams asmultiple queues with non-homogeneous Poisson arrival processes, and the data blockforwarding procedure as a K-limited polling service, a K-limited asymmetric polling model is constructed. By using the method of a stochastic decomposition, the systemperformance is analyzed approximately in steady-state, and some performance measures,such as the peer buffering length and the data processing continuity level, are presented.Finally, the numerical experiments for the pure limited symmetric polling model andthe K-limited asymmetric polling model are provided, and the impacts of the systemparameters to the performance measures are represented for both the FD-PA mechanismand NFD-SPA mechanism. Combing with the system simulations, system performancefor the two multiple sub-stream transmission mechanisms are investigated and compared.