Video Streaming Caching In Wireless D2D Networks

Due to the rapid development of the Internet of things and intelligent terminals,the number of terminal devices has shown an explosive growth and the mobile data traffic has shown an exponential growth trend,among which the traffic generated by video streaming accounts for more than 60%of the mobile data traffic.When using mobile devices to assist cellular network in content distribution,devices should be able to realize direct data transmission between each other without passing through the base station,which is the device-to-device(D2D)communication technology.To make full use of D2 D caching,it is necessary to design the video streaming caching strategy in the D2 D networks reasonably.A unique feature of streaming is that a viewer can play the video as soon as he/she caches some initial video segments,i.e.,prefix,rather than waiting until the entire video file is downloaded.Exploiting this feature of video streaming for prefix caching is able to further boost user-perceived actual experience.In this paper,the caching strategies build the mathematical models basing on the feature of video streaming.We have proposed a video streaming caching strategy of prefix caching and a video streaming caching strategy of unrestricted prefix caching.Taking D2 D network playback delay as the performance evaluation index,the two kinds of video streaming caching strategy design problems are constructed into mathematical models to minimize D2 D network playback delay with caching space limitation.Both the mathematical models can be reconstructed to the problems of monotone submodular maximization based on matroids.Then we design the greedy algorithms to solve the two models.In the two strategies,the caching strategies obtained by the greedy algorithms achieve better performances with lower time complexity,which are very close to the corresponding optimal solutions.In addition,the performance index of the video streaming caching strategy of prefix caching is not much different from that of the video streaming caching strategy that does not restrict prefix caching,but the algorithm time complexity of prefix caching strategy is lower.The user can get more communication gains by moving and connecting more base stations or terminal devices.We propose a video streaming caching strategy for mobile users.In this paper,an alternating renewal process is used to describe the user's mobile mode.Taking the D2 D network play delay as the performance evaluation index,the video streaming caching strategy design problem when the user is moving is constructed into a mathematical model with cache space limitation to minimize D2 D network play delay,which is solved by the greedy algorithm.Through simulations,it can be seen that the movement of users makes users have more opportunities to share files,brings greater gains to communication,and gets less playback delay.