Joint Link Scheduling and Routing in Two-Tier RF-Energy-Harvesting IoT Networks

This article considers routing and link scheduling in a two-tier wireless backhaul network. The first tier consists of routers and the second tier consists of radio frequency (RF)-energy-harvesting Internet-of-Things (IoT) devices that rely on routers for energy. Our aim is to derive the shortest time division multiple access (TDMA) link schedule that satisfies the traffic demand of routers and energy demand of IoT devices. We formulate a linear program (LP) to jointly derive a routing and link schedule solution. We also propose a heuristic link scheduler called transmission set generation (TSG) to generate transmission sets and to derive the transmit power allocation of routers. In addition, we present a novel routing metric that considers RF-energy-harvesting devices on a given path. TSG on average achieves 31.25% shorter schedules as compared to competing schemes. Finally, our novel routing metric results in link schedules that are at most 24.75% longer than those computed by LP.