Content Delivery Technology Of Dual-structural CDN Based On LTE

Content Delivery Network(CDN)is deployed on the traditional TCP/IP network as an overlay network.Although CDN can improve the response speed of terminal requests and the performance of content service,it lacks the semantic information and fails to push content to the terminal.Fortunately,the broadcast-storage structure,embracing the UCL semantic information,can directly use the broadcast channels and push the content to the terminal in the "one to many" delivery pattern.Therefore,this thesis introduces the broadcast-storage structure as a secondary structure to the edge of CDN to form a dual-structural CDN.Because the eMBMS technology is an enhanced multimedia broadcast multicast technology applied in the LTE network,which has good characteristics such as high data rate,low delay and so on,this thesis uses eMBMS technology to implement the broadcast-storage structure.The dual-structural CDN increases the delivery of broadcast content on the basis of original content delivery mechanism.Therefore,how to design an efficient content delivery mechanism is the main problem to be solved of this thesis.Aiming at the problems of content delivery in the dual-structural CDN,this thesis proposed,in terms of the content pushing,a content broadcast pushing algorithm(CBPA)according to the needs of utilizing the UCL semantic information,and multiple users' interests and attention to the timeliness.And in terms of the content forwarding,this thesis proposed a content forwarding algorithm(CFA)according to the fact that the broadcast contents lie in the edge nodes.The main work of this thesis is as follows:(1)For the demands of content pushing in the dual-structural CDN,this thesis presents a content broadcast pushing algorithm(CBPA).CBPA mainly contains the base station and the terminal.The base station calculates the content of the user's interest according to the user's history access record and the UCL information,and pushes the content to the terminal by using the idle time slot of the virtual push time axis.The terminal selectively accesses the content pushed by the base station based upon the demand of each content.Compared with the traditional content pushing algorithm,CBPA utilizes the semantic characteristics of UCL,and can effectively improve the hit rate of terminal.(2)Focusing on the problems of content forwarding in the dual-structural CDN,this thesis proposes an efficient content forwarding algorithm(CFA).Firstly,the forwarding strategy of broadcast content is realized through the mutual cooperation of neighbor nodes.Then the content obtained from the neighbor node or the primary structure is decided whether to cache based on the UCL semantic information.Finally,the cache replacement of the edge node is realized on the basis of the idea of greedy-alogrithm.Compared with the traditional content forwarding algorithm,CFA takes account of the characteristics and demands of the broadcast content,and efficiently utilizes the broadcast content of the edge nodes,which can improve the response delay of the end requests and the hit rate of the edge nodes.(3)Based on the prototype system environment of the broadcast-storage structure,this thesis designs and implements a LTE technology based dual-structural CDN prototype system.In the prototype system,the CBPA and CFA are analyzed and tested via real data set in the dual-structural CDN.The experimental results show the feasibility and effectiveness of the CBPA and CFA.