Integrating Low-Power Wide-Area Networks in White Spaces

Low-Power Wide-Area Networks (LPWANs) are evolving as an enabling technology for Internet-of-Things (IoT) that offer long communication range at low power. Despite their promise, existing LPWANs still face limitations in meeting scalability and covering much wider area which make their adoption challenging for future IoT applications, specially in infrastructure-limited rural areas. To address this, we consider achieving scalability by integrating multiple LPWANs that need to coordinate for extended coverage. Recently proposed SNOW (Sensor Network Over White Spaces) has demonstrated advantages over existing LPWANs in its performance. In this paper, we propose to scale up LPWANs through a seamless integration of multiple SNOWs that enables concurrent inter-SNOW and intra-SNOW communications. We then formulate the tradeoff between scalability and inter-SNOW interference as a constrained optimization problem whose objective is to maximize scalability by managing white space spectrum sharing across multiple SNOWs. We also prove the NP-hardness of this problem. We then propose an intuitive polynomial time heuristic algorithm for solving the scalability optimization problem. Hardware experiments through deployment in an area of (15x10)sq. km demonstrate the effectiveness of our algorithm and feasibility of achieving scalability through seamless integration of SNOWs with high reliability, low latency, and energy efficiency.