Duty-Cycle-Aware Real-Time Scheduling of Wireless Links in Low Power WANs

Low Power Wide Area Networks (LPWANs) are an excellent fit to city-scale IoT applications becuase of their long range and a battery life of several years, and a data rate of 25-50kbps, which is sufficient to carry IoT traffic. However, a practical limitation of a LPWAN-based real-time wireless network is the duty-cycle limit imposed on the sub-1GHz band by the FCC. In this paper, we overcome this challenge by proposing the first duty-cycle-aware wireless link scheduling algorithm for real-time LPWANs that considers the urgency of the packets as well as the availability of the wireless channels. The proposed algorithm is implemented in a five-node, wide-area outdoor test-bed in multiple realworld scenarios. Simulation results are provided to quantify its performance under different settings (e.g. larger networks, variety of workloads, and multiple baselines). In both realworld deployments and simulations, the proposed algorithm outperforms standard scheduling algorithms in terms of link schedulability, deadline misses, and buffer size.