Analysis of optimal piece flow in tit-for-tat-based P2P streaming
Analysis of optimal piece flow in tit-for-tat-based P2P streaming
复制标题
DOI：
10.1016/j.comnet.2018.04.004
复制
发表时间：
2018-07
期刊：
影响因子：
--
通讯作者：
Masahiro Sasabe
中科院分区：
文献类型：
--
作者：
Masahiro Sasabe
BitTorrent是一种成功的P2P文件分发系统，它采用博弈论中的针锋相对策略来鼓励节点之间的合作，即，每个对等体必须向其他对等体提供原始文件的片段（称为片段），以便从其他对等体检索其需要的片段。由于TFT策略可以限制节点的搭便车行为，因此也有一些基于TFT的P2P流媒体系统，并对这些现有系统的性能进行了分析。然而，基于TFT的P2P流媒体中的最佳片段流尚未被揭示。在本文中，基于TFT的P2P流媒体的离散时间模型的第一次开发和整数线性规划（ILP）制定，以确定最佳的片流的平均播放延迟最小化。通过使用现有求解器求解ILP，即，CPLEX，我们可以得到最佳件流的数值例子。对所获得的最优片流的分析表明：（1）最优片选择是基于有序片检索和最稀有的第一片检索之间的平衡;（2）最优节点选择取决于节点的上传能力和流播阶段;（3）片数不影响系统性能，（4）最大播放延迟可以由对等体的数量与服务器的上传容量的比率来限制，以及（5）TFT约束的放松如何能够改善系统性能。
BitTorrent, which is one of the successful Peer-to-Peer (P2P) file distribution systems, adopts the tit-for-tat (TFT) strategy in game theory to encourage cooperation among peers, i.e., each peer has to provide fragments of the original file, called pieces, to others so as to retrieve its demanding pieces from them. Because the TFT strategy can restrict free riding behavior of peers, there are also several TFT-based P2P streaming systems and the performance of such existing systems has been analyzed. However, optimal piece flow in TFT-based P2P streaming has not been revealed yet. In this paper, a discrete-time model of TFT-based P2P streaming is first developed and integer linear programming (ILP) is formulated to determine the optimal piece flow where the average play-out delay is minimized. By solving the ILP using existing solver, i.e., CPLEX, we can obtain numerical examples of optimal piece flow. The analysis of obtained optimal piece flow reveals that (1) optimal piece selection is based on the balance between in-order piece retrieving and the rarest-first piece retrieving, (2) optimal peer selection depends on the upload capacities of peers and the stage of streaming, (3) the number of pieces does not affect the system performance, (4) the maximum play-out delay can be bounded by the ratio of the number of peers to the server’s upload capacity, and (5) how the relaxation of TFT constraint can improve the system performance.