| Benefiting from the fast evolution of wireless communications and the widespread of mobile smart devices,we have witnessed a rapid development of mobile Internet.Within such a trend,mobile multimedia applications,including mobile video streaming,is undergoing explosive growth.The current mobile Internet,however,still applies the traditional TCP/IP architecture,which design for host communication and is no longer suitable for the current Internet with the function of content distribution.Conventional solutions such as content delivery network and peer-to-peer technologies provide large scale multimedia services via constructing an overlay upon the TCP/IP network.This overlay structure not only causes extra communication costs but also difficult to provide near-end,smooth data access for users due to the high dynamic of mobile nodes.These drawbacks severely impair the performance of multimedia services.To overcome the drawbacks of TCP/IP network,numerous researchers focus on the study of future Internet architecture.Information-centric networking(ICN)as a pioneer network architecture has gained significant attention recently.Instead of naming the host as in TCP/IP,ICN introduces the idea of naming the content and provide name-based routing and in-networking caching.The major advantage of naming the content is that the data transmission will be not affected by the movement of network units over the delivery path.Also,the in-network caching shortages the distance between the popular content and users and thereby reducing the data access delay.Although ICN has been treated as a promising solution for the future Internet,how to provide high-quality multimedia services via ICN remain problematics:(1)Current ICN mainly concerns the caching on static units such as routers,yet neglecting the massive resource holding by a large number of mobile devices,which limits the caching utilization;(2)current ICN forwarding suffers from the conflicts between forwarding delay and forwarding maintenance costs,resulting in the low efficiency on request/data forwarding and difficulty on supporting large scale,low delay mobile multimedia services;(3)The existing ICN transmission control strategies focus on the static network scenarios,which is unsuitable for the mobile network with high dynamic network topology and user behaviors.Consequently,the network resource is not fully utilized while the multimedia transmission performance is low;(4)with the popularity of dynamic adaptive streaming(DAS),enabling the ICN DAS becomes a popular research trend.However,current studies still follow the conventional IP-based end-to-end bitrate adaptions,neglecting the multicast and multi-rate features of ICN DAS.To deal with the above challenges,this Ph.D.thesis studies the key technologies of ICN for mobile multimedia services,and mainly focuses on ICN content caching,forwarding,transmission control,and rate adaptation.Contributions are multi-folded:(1)A time threshold-based ICN cooperative caching for multimedia is proposed.First,the thesis introduces the evolutionary model of caching distribution-user demand in mobile scenarios.Based on this model,the cooperative caching optimization problem is formulated whose objective is to jointly minimize the caching cost and data access delay.Moreover,by the comparison between theoretical and numerical results,it is found that the performance of time threshold caching policy is better than that of the probabilistic caching policy.Therefore,a time threshold cooperative caching algorithm has been proposed which leverages the mobile devices’storage and D2D communications to enhance the caching performance in mobile networks.Extensive simulations tests have also been conducted and proofs that the proposed algorithm outperforms several state-of-art solutions.(2)Based on the cooperative caching,a preference and mobility aware ICN video forwarding mechanism are then proposed.In this mechanism,the mobile nodes with similar video access and movement behaviors are clustered as associate nodes.Each mobile node forms the high preferencedd content table to maintain the caching status of its associate nodes,which is used for fast and reliable request forwarding.Additionally,a mobility adaptive data delivery solution it also given which ensures the smoothness of data delivery when the delivery path changes.(3)A distributed stochastic optimization framework for ICN transmission control has been proposed.To accommodate the network dynamic and bandwidth limitations in mobile scenarios and consider the multipath feature of ICN,the transmission control problem in ICN is formulated as a stochastic optimization whose objective is to maximize the overall long term network utility.By introducing the virtual queues,the formulated problem is rephrased as Min-Drift-Minus-Penalty forms.The optimization problem is then decoupled to two subproblems:request scheduling and rate control problem.A distributed alternating optimization algorithm is given to solve the problems iteratively.Theoretical and numerical results show the convergences of the proposed algorithm.Simulation tests have also been conducted and show how our proposed algorithm outperforms state-of-the-art solutions.(4)For providing high-quality Dynamic Adaptive Streaming(DAS),a decentralized asynchronous optimization(DAOA)for ICN DAS tranmisssion has been given.The problem has been formulated as a two-stage optimization problem where the first stage is to optimize the flow control in ICN and the second stage is for playback bitrate selection.Then,the distributed asynchronous optimization algorithm(DAOA)is proposed.DAOA applies a distributed switching mirror descent algorithm to solve the first stage problem and the second stage problem is solved by the Lyapunov optimization theorem.Theoretical results show the convergence of the proposed algorithm.Simulation has also been conducted to show the performance of the proposed DAOA.This study focuses on the mobile multimedia services over the ICN.In particular,solutions for content caching,forwarding,transmission control,and rate adaptation have been proposed.For the research methods,mathematical modeling,problem formulation,optimization algorithm design,theoretical and numerical proof the algorithm’s main results and simulation tests have been applied.The research achievement of this study can benefit our nation’s designate of future network architecture,mobile multimedia service to some degree. |
