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Research On The Key Technologies Of Video Delivery In Opportunistic Networks

Posted on:2016-02-28Degree:DoctorType:Dissertation
Country:ChinaCandidate:H H WuFull Text:PDF
GTID:1108330482457830Subject:Computer Science and Technology
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With the popularity of smart mobile devices, the way for people to access and share information becomes more convenient, and the contents, from the text, images, sound to the video, has become more and more abundant. At the same time, all kinds of applications supported by mobile phones are emerging, and especially the ones based on video streaming have attracted much attention from the academic and industry communities. However, the transmission of massive video data will bring tremendous cost pressures to the mobile users and service providers, and on the other hand, the rapid growth of video traffic in the foreseeable future years will also go far beyond the capacity limits of the cellular networks and Wi-Fi hotspots with limited coverage. Therefore, data exchange among mobile users through their conscious or unconscious contacts has become an new paradigm for video data transmission, while the develop-ment of short-range wireless communication technologies also provides sup-ports for the implementation of such model.For general data exchange through opportunistic contacts, related issues have been extensively studied; however, due to the features of video data and the special requirements on delivery quality of video-based applications, the existing methods for general data transmission cannot be applied to video trans-mission very well. Thus, we fully consider the characteristics of opportunistic networks, focus on the issue of video data delivery, and conduct our research from three aspects including package scheduling policy, routing algorithm and cooperation incentive among mobile users. As a result, some model, strategy and scheme have been proposed accordingly. Specifically, the main contribu-tions are as follows:(1) Quality-gain-based video packet scheduling policy. When video data. is transmitted in opportunistic network, any replica of a video packet which has not been delivered yet, will has a gain on the quality of reconstructed video, if it is received successfully by the destination node. The gain of a video packet is determined by two factors:its importance on the video reconstruction and the number of its replicas in the network. We establish the quantitative model between the quality gain and the two factors, and based on this, propose a video packet scheduling policy which can optimize the video delivery quality.(2) Transmission-mode adaptive opportunistic routing algorithm for video delivery. In an urban environment, on the one hand, due to the fading wire-less channel and interference, large amounts of packets will be damaged and discarded when they are transmitted though wireless link, and as a result, the quality of recovered video clip will be decreased greatly; on the other hand, if the video delivery relies solely on the movement of vehicles, large amounts of packets will be dropped due to the excessive delay, which can also result in significant distortion. To deal with this conflict, we propose a quality-oriented opportunistic routing algorithm, which can adaptively change the data trans-mission mode to minimize the utilization of wireless links. By finding a balance between the transmission delay and packet loss, the quality of video recovered is maximized.(3) Static-node-assisted relay-caching opportunistic routing algorithm for video delivery. In the urban environment, how to deliver video streaming to a mobile target vehicle with minimum delay under the requirements of play-back quality is a very practical problem with many application requirements. To deal with this issue, we utilize the existing wireless enabled traffic cameras as static caching nodes and propose the static-node-assisted relay-caching rout-ing algorithm. This algorithm can adaptively select proper camera as Optimal Buffering Point (OBP) for each segment of live video streaming, and through the cooperation of these OBPs, the live video streaming could be delivered to a mobile target vehicle with minimal startup delay while satisfying the required visual quality and playback performance.(4) User Cooperation incentive scheme for opportunistic video delivery, video delivery in opportunistic networks needs close collaboration among mo-bile users to ensure the delivery quality, but the selfishness of mobile users will impair the cooperation seriously. To solve this problem, we regard each video packet as commodity, and propose the quality-driven incentive scheme. In this scheme, each video packet is dynamically priced according to their expected marginal gains on the quality of the reconstructed video, and the process of video delivery is considered as a sequence of packet transactions which are modeled as two-person cooperative games; driven by the market behaviors of participatory users, video clips can be delivered with optimal quality.In summary, this thesis studies the video delivery in opportunistic net-works from the aspects of scheduling policy, routing algorithm and incentive mechanism, and proposes a series of models and methods. The research results are evaluated by theoretic analysis and extensive simulations, which can pro-vide theoretical basis and technical support for all kinds of video applications running over opportunistic networks.
Keywords/Search Tags:Opportunistic networks, video delivery, scheduling policy, routing algorithm, incentive scheme
PDF Full Text Request
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