A battery aware scheme for energy efficient coverage and routing in wireless MIMO mesh networks

Wireless MIMO (Multiple Input Multiple Output) mesh networks recently emerge as a flexible, low-cost and multi-functional networking platform with wired infrastructure connected to the Internet. Mesh routers are equipped with multiple radio transceivers that can work simultaneously. This MIMO feature greatly improves data throughput of mesh routers. A critical issue in MIMO mesh networks is to maintain network coverage and routing for a long lifetime with high energy efficiency. As more and more outdoor applications require long-lasting, high energy efficient and continuously-working mesh networks with battery-powered mesh routers, it is important to maximize the performance of mesh networks from a battery aware point of view. Recent study in battery technology reveals that discharging of a battery is nonlinear. Batteries tend to discharge more power than needed, and reimburse the over-discharged power later if they have sufficiently long recovery time. To take advantage of the battery recovery property, in this paper we first study the relationships between various MIMO transceiver parameters and their battery parameters to give an energy model for MIMO transceivers. We then present a multiple current battery model that can accurately describe battery behaviors with multiple current inputs. Based on these two models, we propose a battery aware MIMO mesh network power scheduling scheme. The scheme consists of two algorithms: the coverage algorithm and the backhaul routing algorithm. The key idea of the coverage algorithm is to let neighboring mesh routers collaboratively adjust their transceiver radii to dynamically recover their over-discharged battery power. The backhaul routing algorithm adopts the multiple current battery model to calculate battery discharging loss at routers for scheduling mesh backhaul routing. We conducted simulations to evaluate the performance of the proposed scheme. The results show that network lifetime can be improved by up to 10.3% and 16.1% for homogeneous and heterogeneous mesh networks, respectively.