Research On Video Cache And Distribution Strategy In Wireless Edge Networks

With the rapid development of network technology and the popularity of smart devices,as an integral part of people's living,learning and entertainment,the number of video services shows an explosive growth trend.And the repeated transmission of video on the backhaul link brings a great challenge to the wireless edge network.Edge caching places the caching resources in the nearest place to the user,which can reduce the video transmission delay and system energy consumption.It can not only meet the requirements of high speed and low delay of emerging video services,but also deal with the change of quality of experience(QoE)caused by user's mobility.Therefore,it is necessary to study the video caching and video distribution in the wireless edge networks.Firstly,this thesis introduces the research background and related research hotspots of mobile edge caching technology,mainly summarizes the newest research status about video caching and video distribution in mobile edge caching technology,and summarizes the shortcomings of existing research works.Secondly,in the scenario where the small base station(SBS)follows the homogeneous poisson point process(HPPP),the cache placement problem of video content with different quality levels is studied.Video is encoded into same video layers with scalable video coding(SVC)technology.The probability of successful video transmission is derived,and the system energy efficiency and average delay of wireless edge networks are further derived.An optimization model is established to balance system energy efficiency and average delay,and then a video caching strategy based on genetic algorithm is proposed.Simulation results show that the proposed algorithm can achieve great results in system energy efficiency,average delay and cache hit rate.Then,the idea of software defined network(SDN)was added to the wireless edge network.In order to realize the centralized control of wireless edge network and simplify the management and scheduling of communication resources,an edge caching architecture based on SDN is designed.Aiming at the decline of user's QoE caused by user mobility,an adaptive video distribution algorithm is proposed.The SDN controller monitors the whole wireless edge network to obtain real-time network state and selects the optimal video quality level and power allocation for users.The simulation results show that the proposed algorithm can reduce the video playback and improve the user's QoE effectively.