Optimization Research On Key Problems Of Video-on-demand Service Based On Correlation Characteristics

VoD (Video-on-Demand) supports interactive operations, is better than thetraditional passive video service and is becoming one of the most popular services inthe internet. The characteristics of VoD, such as the interactive operations, user'sdemand for the real-time view, the explosive increase of service scale, as well as theinstability of users' demand, bring some challenges to implement a high-quality andcost-effective VoD system. This paper, basing on the relevance characteristic ofdifferent video segments and videos, implements an optimizing research on the keyproblems of VoD service which are as following:1) Fast locate the destination segment. To solve this problem, based on thecharacter that the segments of on-demand streaming have some relevance with eachother, a new VoD model is proposed. The proposed model makes peers with similarinterests organized together to realize most users' requests can be satisfied by theirneighbors. And then it improves the searching efficiency of locating the destinationsegment. The optimization problem about how to optimize peer's neighborlist isinduced by the proposed strategy, and the problem can be formulated as a set coverproblem. An approximate optimization algorithm is presented to solve the problem.The simulation results show that the proposed strategy can effectively reduce theseeking delay and enhance the scalability of the system.2) The deployment of VoD service on cloud platform. Through the crawled dataof videos in YouTube, we find that with larger than90%probability, the YouTubeuser's all requested videos are within three hops of related videos. Base on thisconclusion, a cluster-based P2P VoD model with cloud assistance is proposed. Therequested bandwidth prediction for a cluster is needed for the start delay of cloudservers. Given the diverse capacities, cost, limited lease size of cloud servers, weformulate an optimization problem about how to lease cloud servers to minimize theleasing cost. And then a heuristic solution is presented. The evaluation shows theefficiency of the proposed schemes. 3) The research on the optimal content placement scheme on distributed cloudservers. Considering the regional differences in the videos' popularity, ageographic-aware content placement scheme is proposed. The proposed scheme aimsat reducing the cross-boundary traffic and realizing the load-balance on cloud serversas well as preserving the social relationship. The problem can be formulated as aconstrained k-medoids clustering problem which under the constraint of minimizingthe cross-boundary traffic and the imbalanced weight on cloud servers. Comparedwith the previous scheme which overlooked the geographic popularity of interest, theproposed one effectively reduce the cross-boundary traffic and realize theload-balance on cloud servers as well as preserve social relationship.4) The research on an efficient cache replacement strategy to promote thecontent utilization and reduce the delay of content request with the limited cache size.This paper proposes a cache replacement scheme based on video semantic similarity.When a peer's cache space is full, it will replace the videos which have a lagersemantic similarity with the already replaced videos and the replaced content shouldhave the smaller popularity and larger replications. The replacement problem can bedescribed as a multi-goal optimizing problem, we transform it into a single-goaloptimizing problem and then describe it as a knapsack problem. A heuristic algorithmis proposed to solve it. The simulation analyses the impact of different parametersettings on the performance of the proposed scheme and verifies the effectiveness ofthe scheme in promoting the hit ratio.This paper is funded by National “863” Project (2008AA01A315),2011Specialized Research Fund for the Doctoral Program of Higher Education, undergrant of “Research of Key Technology of P2P VoD Based on Cloud”(20114101110007) and2011Innovative Talent Project of Department of Henaneducation, under grant of “Research on key Technology of P2P VoD”(2011HASTIT003), Key Projects in Henan Province Department of Education, undergrant of “Research on Key Problems of Cloud-assisted P2P VoD”(13A520562).