| With the vigorous development of Internet,network traffic has increased explosively.More and more problems such as increased transmission delays,low utilization of network resources,and insufficient network support for mobility and security.come to light in traditional TCP/IP network.The proposal of Content Centric Network(CCN)can effectively solve these problems.As the cornerstone and key technology of CCN,cache strategies have been widely studied.However,the existing cache strategies still have problems of high content redundancy and low cache content utilization.Therefore,this thesis mainly studies the cache decision strategies and replacement strategies to improve the network performance of CCN from cache strategy aspect.The main contents of this thesis are as follows:(1)First of all,to slove problems of large content redundancy and slow push of popular content to terminal nodes near users,this thesis proposes a probability cache strategy based on data sources.The scheme performs probability cache on the return link according to different data sources,and can dynamically adjust the probability according to the length of the link;At the same time,the popular data can be quickly pushed to node near users.The simulation results show that,compared with the traditional cache scheme,the proposed strategy improves the hit rate and reduces the average hop count for getting the content..(2)Secondly,The greater the probability of request is and the closer the expected access time to current time is,the greater its retention value is.So a replacement strategy based on expected value is proposed.This strategy considers popularity and time distance from expected access time to current time to construct the expected value function and replace the least valuable content accordingly.Simulation experiments show that,compared with the traditional cache replacement strategies,this strategy can effectively improve the cache hit rate,reduce the count of request hops,and improve network performance. |
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