Algorithms For The Multi-channel Program Download Problem In Vod Applications Based On Vanet

With the development of the Internet and the popularity of mobile terminals,video-on-demand(VOD)has become one of the most popular network applications.It has brought great convenience to us in all aspects of life,such as learning,work and enter-tainment.People want to watch videos anytime,anywhere,especially on board.How-ever,watching videos in the journey is mostly limited to using local storage or mobile data traffic at present,but cache lacks flexibility while mobile data traffic is too expen-sive.The appearance of internet of vehicles makes it possible to solve these problems.Though users can use VOD system by accessing the internet of vehicles,there still exist some other issues,such as poor video playback,low video clarity etc,which are caused by the high mobility and limited resources of the internet of vehicles.Therefore,how to design a VOD system which can meet all kinds of needs and bring better user experience has become an urgent problem to be solved.To address above challenges,this paper presents a set of video download schemes for several scenarios based on C/S architec-ture in the internet of vehicles,which can effectively improve user experience.There are three major contributions in this paper:· On the client side,we propose a set of video download framework.This frame-work is composed of three different scenarios.Firstly,we study the Multi-Channel Program Download Problem(McPDP).We prove it is NP-complete by reduction from 3-SAT(3)problem.For another version with neatly placed programs of equal length,the Aligned Multi-Channel Program Download Problem(AMcPDP),we present two algorithms by transforming it into a max-flow problem.We also study the version with buffer limitation,the Multi-Channel Discrete Download Problem with Finite Storage(McDDPS),and designed two collaborative algorithms based on greedy algorithm to find the fastest schedule to download all necessary pro-grams.· On the server side,we propose a set of channel broadcasting protocol framework.The framework consists of two kinds of broadcasting protocols based on multi-channel broadcasting model-Simple Segment Broadcasting Protocol(SSB)and Block Cycle Broadcasting Protocol(BCB).For both the limited storage version and the unlimited storage version,we present download algorithms to solve them.This framework can effectively reduce client delay.· We extend these two frameworks to the multi-server environment,and put for-ward general steps to solve multi-server problems.For multi-server scenarios,we have proposed solutions for both small video download case and large video download case.It is found that our proposed schemes can effectively improve the download efficiency of mobile vehicles.Finally,we also analyze the performance of those proposed algorithms by simula-tion using MATLAB.Also,the case study of multi-server problem is carried out.The experimental results show that two frameworks that we have proposed can effectively shorten the client delay,reduce the storage requirements and bring better user experi-ence.