Cooperative Caching Management In Wireless Communication Networks

With the huge popularization of smart devices and the explosion of mobile traffic,the capacity of current wireless networ-ks is challenged and this is foreseen to be worsen in the fifth-generation(5G)mobile networks.A recent promising approach to alleviate this problem is to offload data traffic through opportunistic communications,which allows coordination and sharing of storage resources among diverse nodes such as mobiledevices(e.g.,smartphones,laptops),base stations(BSs).Cooperative caching management in mobile communication networks becomes a hot research topic recently due to its benefits of improving the network throughput and reducing of communication cost.Inspired with the cooperative caching policy as a major role in wireless communication networks,this dissertation mainly deals with the cooperative caching management in content-centric mobile ad hoc network and wireless device-to-device(D2D)caching network.Existing literature either exploits the joint design of caching and content discovery strategies through cellular link or deals with quality of service(QoS),which ignores the availability of D2D transmitter for communication.To address such challenges,this dissertation proposes potential solutions based cooperative caching management,which prevents redundancy inuser demands and shows high performance improvement for the increase in content popularity distribution.Detailed contributions are summarized as follows.1)To optimize the cache placement in a content-centric wireless ad hoc network,a cooperative group caching strategy is proposed,in which the caching fit probability is considered as the objective in optimizing the cache placement.To execute placement,the neighboring node with the lowest caching fit probability is chosen as the best candidate.With theconsidered strategy,the cache hit probability and the average number of successful served requests are analytically derived.Numerical results and simulations are provided and revealed that the proposed strategy outperforms the existing strategies by reducing content redundancy.2)To improve the performance of in-network caching in D2D communications,a joint optimization problem of caching decision and content discovery subject to the maximization of the in-network caching gain is formulated.The evaluation of the proposed results for different value of the Zipf parameter shows that the in-network caching gain is significantly improved with the joint optimization.Meanwhile,the proposed joint caching decision and content discovery algorithm provides a distributed solution that can achieve performance comparable to that of the exhaustive search method.Further,the proposed scheme has a notable in-network caching gain and an improvement in traffic offloading as compared to most popular content(MPC)scheme and greedy caching scheme.3)Finally,to reduce the traffic of backhaul link and enhance network capacity in cache-enabled D2D-aided cellular networks,a cooperative crossing cache placement is studied to maximize the offloading probability,which establishes device availability.The availability of a device indicates whether a cache-enabled device can handle the transmission of the desired content within the required sending time,called the delay.Based on the caching strategy and the availability of transmission devices,the content offloading cooperation strategy is derived in which content delivery traffic can be offloaded via the local cache,a D2D link,or else via a cellular link.The proposed scheme improves the total offloading probability by 13.5%and 23%compared to MPC scheme and cooperative content caching in BS mode or D2D mode separately(Coop.BS/D2D caching)scheme.