P2P流媒体中的数据分配算法

最近兴起的P2P技术在充分利用客户资源、提高系统的可伸缩性方面具有巨大的潜力,基于P2P提供视频服务已成为Internet的一项重要应用.在多对单P2P模式下,对多个发送端最优地分配发送速率和数据是一个难题.为此,提出了一种新的分配算法.首先,应用排队论把最优速率分配问题模型化为非线性最优化问题,推导出求解最优化问题的速率分配公式;然后,基于该公式提出最优速率分配算法(ORAA),并对ORAA输出解的最优性给出证明;最后,提出动态速率分配算法(DRAA).DRAA对动态的网络环境具有自适应性,能根据网络条件的变化最优地为多个发送端进行速率和数据分配.仿真实验结果表明,在不同的参数条件下,DRAA算法减少了计算和通信开销,比同类算法有更好的性能.

Data Allocation Algorithms in P2P Streaming

The recently emerging P2P technologies have huge potential on resource usage and system scalability. Providing P2P-based media streaming service, which is an important application over the Internet, has attracted a lot of research interests. In P2P media streaming with the pattern of multiple senders and single receiver, it is still a challenge to optimally allocate streaming rate and media data among multiple senders. To cope with the problem, a new solution is proposed. Firstly, the authors model the optimal rate allocation problem as a non-linear optimization problem by applying queueing theory, and derive the optimal rate allocation formula that computes the optimal solution. Then, a new optimal rate allocation algorithm (ORAA) based on the formula is proposed. The ORAA algorithm can produce the optimal solution and the optimality of its solution is proved. Finally, based on the ORAA algorithm, a dynamic rate allocation algorithm (DRAA) is proposed, which can dynamically adapt to network fluctuation and optimally allocate streaming rate and media data among multiple senders. Because of its short running time, the DRAA algorithm can be used in real time. Extensive simulation results using NS2 show that the proposed DRAA algorithm effectively reduces calculation and communication overheads, and achieves a better performance than the related works with different parameters.