On wireless network infrastructure optimisation for cyber-physical systems in future smart buildings

Today, most cyber-physical systems (CPS) in smart buildings require a wireless-based network infrastructure for sensing, communication, and actuation. In such CPSs, the energy expenditure and hence battery lifetime of the wireless network infrastructure depend heavily upon the placement of the base stations (BS). However, in indoor environments, BS placement is particularly challenging due to the impact of building structures and floors/walls separations. In this paper, we study the problem of jointly optimizing BS placement and power control in buildings to prolong the battery lifetime of sensors in the CPS network infrastructure. We first show that the joint BS placement and power control problem can be formulated as a mixed-integer non-convex program (MINCP), which is NP-hard and difficult to solve especially when the network size is large. To address this difficulty, we propose a novel efficient algorithm called ECPC that targets at large-sized network infrastructures in buildings. Our theoretical analysis and numerical results show that ECPC achieves competitive solutions compared to the true optimal solutions obtained by the branch-and-bound method.