Studies on Design and Evaluation of a Video Multicast Method for Heterogeneous Mobile Terminals

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In this research, we have considered a cost-efficient multicast method for video streaming to heterogeneous mobile terminals via a content delivery network (CDN). Based on the requirements such that each mobile terminal can specify the quality of receiving video under the constraints of display size, computation power, available battery power, and bandwidth and that each terminal can receive the video mostly satisfying the user's demand, we have the following results.(1) The original video is converted in various qualities by letting proxies execute transcoding services based on the users' requirements. We have developed an algorithm for deciding connecting paths among a server, proxies, and mobile terminals so as to minimize the resource of CDN. Furthermore, we have designed a protocol for reconstructing the paths periodically according to users' requirements.(2) We consider a method for constructing a multicast tree in a mobile ad hoc network. In general, it is NP-hard to construct the cost-minimum multicast tree under multiple constraints such as latency time and bandwidth, and thus we have developed an efficient algorithm for obtaining a semi-optimal solution using a genetic algorithm. In order to apply to a large scale network, we have designed an distributed algorithm with two stages, as follows: The set of mobile nodes is divided into clusters by gathering the nodes located near. After that, a semi-optimal multicast tree is constructed for each cluster, and then a semi-optimal multicast tree is constructed for the set of representative nodes of clusters.We have confirmed the usefulness of the results above through simulations.