Energy-Efficient and delay-guaranteed computation offloading for fog-based IoT networks

Cooperation between the cloud and the fog in the Internet of Things (IoT) system can enhance the efficiency of limited-power and computationally-constrained IoT devices in terms of delay and energy consumption by offloading delay-sensitive and computation-intensive tasks to nearby fog nodes. The purpose of computation offloading is to minimize the energy consumption of IoT devices, meanwhile assuring maximum tolerable delay of tasks. In this paper, we propose a computation offloading scheme in an IoT-fog-cloud architecture considering a multiuser multi-fog nodes scenario. The proposed scheme considers multiple offloading through collaboration between fog nodes, which aims to optimize the offloading probability and the transmit power allocation jointly. Since the formulated optimization problem is non-convex and NP-hard, exploiting successive convex approximation (SCA) and Dinkelbach method, an iterative two-steps algorithm is proposed to solve the problem efficiently. The simulation results expose the tradeoff between energy consumption and task completion time in IoT devices. Further, the convergence of the proposed algorithm is verified.