Purging-Aware Content Placement in Fog-Based Content Delivery Networks

Fog-based Content Delivery Network can cache contents in fog-enabled devices like set-top boxes. This enhanced proximity helps to reduce latency. Efficient content placement is required for the efficient usage of cache resources, both in the cloud and in the fog. The content purging that may occur due to storage scarcity at the edge sides must be considered in an efficient content placement strategy. In this paper, we model the content placement problem in a hierarchical fog-based CDN as an optimization problem that minimizes the overall content access latency. Factors such as content purging, content popularity, and end-user priority have been taken into account. We propose a genetic-based algorithm to solve this problem. Simulation results show the proposed algorithm has a lower latency in comparison with the greedy approach.