Video Transmission Scheme Design In A Cache-Enabled Cloud Wireless Access Network

With the continuous growth of emerging data services based on video content,the traffic load of mobile networks is increasing,which poses a serious challenge to the capacity of existing networks and the uplink and downlink data rates.In order to meet the growing data traffic service,on the one hand,the cloud radio access network(C-RAN)is adopted in the next generation network system;on the other hand,the edge cache is deployed under the C-RAN architecture,so that the data content such as the video requested by the user can be obtained locally,which effectively reduces the pressure on the backhaul link.This paper mainly studies the video transmission in the cache-enabled C-RAN scenario,and optimizes the network from two aspects:cache placement strategy and beamforming design.The main contributions and innovations of this paper are as follows:1.This paper describes the research background and related research of the topic.The characteristics and main research directions of C-RAN architecture are introduced in detail.The research and application of cache classification and placement strategy are summarized,and the related research in cache-enabled C-RAN is introduced.2.In this paper,we propose a video transmission scheme based on popularity-based cache placement strategy and multicast beamforming design.Firstly,the impact of buffer on backhaul consumption is considered.The multicast beamforming scheme of video transmission is studied by establishing the downlink and rate maximization problem.The backhaul consumption is included in the constraint condition,and the successive convex approximation iterative algorithm is proposed to solve the optimization problem.Simulation results show that the proposed scheme can effectively improve the system gain.3.In this paper,we propose a joint optimization scheme for base station clustering and sparse beamforming in a multi-cell C-RAN scenario based on layered cache of scalable video.In view of the variability of video requested by users,this paper proposes a layered cache scheme based on scalable coding.The downlink weighted and rate maximization problem is established to achieve joint optimization of base station clustering and sparse beamforming.Different from the previous chapter,the backhaul constraint uses the fixed transmission rate to model the backhaul link consumption.In this paper,the downlink and rate will appear in the backhaul constraint and in the objective function.In this paper,the target optimization problem is transformed into a weighted minimum mean square error problem,and a local optimal solution is obtained by the block coordinate descent method.Simulation results demonstrate that the proposed layered cache scheme can improve the cache hit probability and the advantage of the proposed joint optimization scheme in performance gain.