Chinese Journal of Computers   Full Text
Title	A Dynamic Scheduling Algorithm for Mobile Streaming Media Based on Proxy Caching
Authors	LIAO Jian-Xin1) YANG Ge1),2) ZHU Xiao-Min1) HUANG Hai1)
Address	1)(State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing 100876) 2)(College of Information Science and Technology, Liaoning University, Shenyang 110036)
Year	2008
Issue	No.7(1216—1223)
Abstract &   Background	Abstract A novel dynamic scheduling algorithm DS2AM2PC(Dynamic Scheduling Algorithm for Mobile Streaming Media based on Proxy Caching)for mobile streaming media based on proxy caching is proposed. It employs the scheme that the cache window size can be increased or decreased adaptively according to the popularity of the requested object and the patch bytes that are segmented and cached. Every time the segment patch with different or same number of bytes is cached at the proxy cache according to the different circumstances. The cache window size is updated periodically according to the popularity of mobile streaming media object. The maximum cache size is decided dynamically. The principle is obeyed that the data cached for each mobile streaming media object are in proportion to their popularity at the proxy server. Simulation results show that this strategy is more adaptive than P3S2A(Proxy-assisted Patch Pre-fetching and Service Scheduling Algorithm) algorithm and OBP(Optimized Batch Patching)+prefix&patch caching algorithm for the variety of the request arrival rates. It can significantly reduce patching data through patching channel under the circumstance of the same maximum cache space. This can effectively reduce the server load and network bandwidth usage on backbone link. It can faster cache the media object than P3S2A algorithm. It reduces the average occupied cache space at the proxy. Keywords 3G； mobile streaming media； scheduling algorithm； proxy caching； segment patch pre-fetching Background This work is supported by the National Science Fund for Distinguished Young Scholars(No.60525110); National 973 Program (Nos.2007CB307100, 2007CB307103); Program for New Century Excellent Talents in University (No.NCET-04-0111); NSFC(No.90604012)；Development Fund Project for Electronic and Information Industry (Mobile Service and Application System Based on 3G); 2007 Year’s Science Fund Project for Young Scholars of Liaoning University (2007LDQN08). An important objective of these projects is to design scheduling algorithms, which can improve the transmission performance of a streaming media system. Delivering efficiently streaming media to asynchronous clients is a challenging task due to the high bandwidth requirements. A lot of existing solutions have focused on developing IP multicast-based scheduling algorithm to reduce server load and network bandwidth. However, even today IP multicast deployment in the Internet remains severely limited. This paper solves the problem of streaming media in the Internet-like environment through the dynamic scheduling algorithm based on proxy caching. Simulation results shows that the algorithm effectively reduces the server load and network bandwidth usage on backbone link and the average occupied cache space at the proxy. Their previous work on this area include a proxy caching algorithm based on segment popularity for mobile streaming media, an active prefetching algorithm for streaming media based on natural number segmentation, peer-to-peer oriented admission control for streaming media and a data assignment algorithm based on peer to peer for streaming media and so on.