Offloading Content with Self-organizing Mobile Fogs

Mobile users in an urban environment access content on the internet from different locations. It is challenging for the current service providers to cope with the increasing content demand from a large number of collocated mobile users. In-network caching to offload content at nodes closer to users alleviate the issue, though efficient cache management is required to find out who should cache what, when and where in an urban environment, given nodes limited computing, communication and caching resources. To address this, we first define a novel relation between content popularity and availability in the network and investigate a node's eligibility to cache content based on its urban reachability. We then allow nodes to self-organize into mobile fogs to increase the distributed cache and maximize content availability in a cost-effective manner. However, to cater rational nodes, we propose a coalition game for the nodes to offer a maximum "virtual cache" assuming a monetary reward is paid to them by the service/content provider. Nodes are allowed to merge into different spatio-temporal coalitions in order to increase the distributed cache size at the network edge. Results obtained through simulations using realistic urban mobility trace validate the performance of our caching system showing a ratio of 60-85% of cache hits compared to the 30-40% obtained by the existing schemes and 10% in case of no coalition

Standalone Green Cache Points for Vehicular Content Distribution Networks

With the rapid growth of interest in media-rich user experience, content distribution networks (CDNs) gained considerable attention. Since, most of the energy is consumed by cache points (CPs) and the associated equipment, it is imperative to deploy fewer number of CPs or switch off as many as possible to save energy. This results in degraded quality of service (QoS). It is an usual dimensioning technique to optimise the number and locations of caching points (CPs) of a content distribution network (CDN), where the objective is to reduce operational energy. In this paper, we reduce non-renewable energy consumption (carbon footprint) by introducing renewable grid energy (in the form of wind energy) and adaptive CPs. Further, we propose algorithms for provisioning high number of simultaneous downloads, which reduce overall waiting time and number of dropped request of city vehicular users. The end result is substantial improvement in quality of service (QoS). The proposed CPs save 100% grid energy during the whole day while fulfilling content demand in a city vehicular environment