Video distribution and routing for video-on-demand networks

Abstract

Broadband Integrated Service Digital Network (B-ISDN) provides a digital packetswitching network which supports the -4synchronous Transfer Mode (ATM) technology. ATWI is ready for the transmission of not only voice and data, but also video. The AThl Quality-of-Service (QoS) guarantee is important for real time video services because the bandwidth, the loss of video data and the time delay between the source and the destination are guaranteed when the call is established. Video-On-Demand (VOD) is the video service that allows subscribers to view video programs any time in their places. Video is delivered from the video server in the VOD network to the subscriber's setop box when a video service is requested. The number of concurrent video streams provided by a video server is fixed. As a result, - the video server cannot serve any additional request if it has already provided the maximum number of concurrent streams. Copies of the video programs are distributed in different video servers in VOD network such that the overall blocking probability of video servers is reduced. The number of copies of a video program placed in the VOD network is proportional to the storage cost in the video server. The operation cost of VOD service is composed of the storage and transmission cost. To obtain a maximum revenue, the VOD service provider needs to obtain an optimal video placement in the network. The placement problem has the NPcomplete property in which an optimal solution is not guaranteed to be obtained. Once the video programs are placed in the network, it is important to decide in which path the video program is transported to the subscriber. The routing path is based on the availability of bandwidth of various paths in the network. The dynamic routing configuration allows each video transmission using a minimum cost path which has enough bandwidth allocated for the whole transmission. After a certain period of operation, new video programs are placed and old video programs are removed from the network. The video refreshment mechanism is based on the popularity of video programs. A number of old video programs copies with low popularity are removed from the network. On the other hand, a number of new video programs copies are distributed to the existing placement configuration. In the first part of the thesis, the formulated models for the video initial placement and the dynamic routing are presented. An algorithm is proposed to obtain near-optimal solutions for the formulated models in the second part of the thesis. The proposed algorithm is based on the decomposition procedures and Genetic Algorithms (GA). From the simulation result, it shows that the proposed algorithm gives a near-optimal solutions for the video placement and the dynamic routing in an efficient way. Moreover, a formulated video refreshment model is presented. The numerical analysis shows that the refreshment mechanism manages the storage resource in the VOD network efficiently.

Date of Award	16 Oct 2000
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Chi Hung Sammy CHAN (Supervisor)