piFogBed: A Fog Computing Testbed Based on Raspberry Pi The fog computing testbed can accelerate the development of fog computing. But so far, there is no real dedicated fog computing testbed to help researchers to test their prototypes, designs, and distributed algorithms in real fog computing scenarios. Researchers often verify their fog computing solutions by adapting some existing testbeds or using simulators under specific conditions, which may make their experimental results unable to withstand the examination of real production environments. This paper proposes piFogBed, the first fog computing testbed for rapid prototyping fog computing components in real environments by using Raspberry Pies and the Docker container. It can be integrated into the existing production network quickly and flexibly. To evaluate piFogBed, we demonstrate its experimental process with a medical monitoring use case, and also verify its feasibility, effectiveness and fidelity. The cost of each fog node of the proposed testbed is only 400 RMB, which is very low compared with the special fog computing equipment, so it is worth promoting and applying.

CostEfficient Resource Provision for Multiple Mobile Users in Fog Computing Fog computing is an emerging paradigm that brings the computing capabilities close to distributed IoT devices, which provides networking services between end devices and traditional cloud data centers. One important mission is to further reduce the monetary cost of fog resources while meeting the evergrowing demand of multiple users. In this paper, we focus on minimizing the total cost for multiple mobile users to provide an efficient resource provisioning scheme in fog computing. The total cost includes two aspects: the replication cost and the transmission cost. We consider two cases for the resource provision problem by focusing on different cost models. First, one simple case where users can only upload one replication is discussed, and an optimal solution is proposed by converting the original problem into one of bipartite graph matching. Then we consider a more complicated case that each user can upload multiple replications on fog nodes in the resource provisioning. For different transmission cost models, the transmission cost is related to the distance of each pair of fog nodes. This problem is proven to be NPhard. We first propose a nonadaptive algorithm which is proved to be bounded by 23W13OPT. Another 3eapproximation algorithm is proposed based on local search, which has better performance with higher complexity. Extensive simulations also prove the efficiency of our schemes.