Utility Maximization for Splittable Task Offloading in IoT Edge Network

This paper comprehensively investigates spatio-temporal dynamics for task offloading in the Internet of Things (IoT) Edge Network (iTEN) in order to maximize utility. Different from the previous works in the literature that only consider partially dynamic factors, this paper takes into account the time-varying wireless link quality, communication power, wireless interference on task offloading, and the spatiotemporal dynamics of energy harvested by terminals and their charging efficiency. Our goal is to maximize utility during the task offloading by considering the above-mentioned factors, which are relatively complex but closer to reality. This paper designs the Time-Expanded Graph (TEG) to transfer network dynamics and wireless interference into some static weight in the graph so as to devise the algorithm easily. This paper firstly devises the Single Terminal (ST) utility maximization algorithm on the basis of TEG when there is only one terminal. In the case of multiple terminals, it is very complicated to directly solve the utility maximization of the task offloading. This paper adopts the framework of Garg and Könemann and devises a multi-terminal algorithm (MT) to maximize the total utility of all terminals. MT is a fast approximate algorithm and its approximate ratio is 1-3ς, where 0<ς<1/3 is a positive small constant. The comprehensive experiments are conducted to illustrate that our algorithm significantly improves the overall utility compared to the three basic algorithms.