Explicit Content Caching At Cellular Base Stations For Opportunistic Wireless CDN

It is widely recognized that caching is an indispensable technology for the next generation mobile content delivery networks(CDNs).In particular,caching at mobile base stations(BS)can help to reduce the backhaul traffic and improve users'content access experience.The recently proposed Opportunistic wireless Content Delivery Network(OwCDN)is a promising new paradigm of mobile CDN.It aims to exploit the redundant capacity in cellular access networks for secondary content delivery service,such that the utilization efficiency of the cellular network can be improved.This paper studies novel BS caching schemes tailored for OwCDN.This thesis first presents a brief review of traditional caching policies and discusses new challenges for BS caching in OwCDN.An explicit BS caching scheme is then proposed.Unlike traditional "transparent" caching schemes,our caching scheme is "explicit" in a way that users' content request is constrained to the already cached content at the local BS.Second,we study the problem of pro-active and explicit BS caching with user mobility awareness.The problem is formulated as a combinatorial optimization problem.Four heuristic algorithms are proposed to solve the problem.The performance of these algorithms is compared and discussed.Third,the problem of explicit BS caching is further refined by considering the fairness constraint among users.A heuristic algorithm is proposed to solve the problem.In the above two problems,the impacts of storage size and redundant capacity on the effectiveness of BS caching are thoroughly studied via simulations.Our studies find that significant performance gains can be obtained when caching policies can adapt to the size of caching storage,the amount of redundant capacity,and the user mobility patterns.We conclude that explicit BS caching is a promising new paradigm of BS caching in next generation mobile communication networks.