📝 SummarXiv

Abstract

Precise and energy-efficient localization is a critical requirement in many Internet of Things (IoT) applications, particularly in large-scale deployments such as asset tagging, agriculture, and smart cities, where long battery life and cost-effectiveness are crucial. The Semtech SX1280 LoRa transceiver presents a promising solution for IoT localization. It combines low cost, low power, and precise ranging capability over distances of up to 1 km. However, the ranging process requires two devices to be simultaneously active, one initiating the ranging request and the other responding to it, which can lead to significant energy expenditure if not properly managed. Despite the transceiver's excellent performance, no existing system-level framework effectively manages sleep-wake coordination and role assignment needed for energy-efficient operation. This paper presents a coordination framework that significantly reduces power consumption while maintaining the inherent precise ranging capability of the chip. The framework schedules short, synchronized wake-up windows between the initiator and the responder, allowing devices to remain in deep sleep for most of their duty cycle. This scheduling strategy minimizes reliance on precise continuous timing and mitigates drift in low-cost oscillators. To validate the framework, we designed and developed custom nodes that are compliant with the framework's protocol. Experimental results show that the proposed approach allows a node to stay in ultra-low power mode and wake periodically to check for instructions. The node can remain in standby mode for up to nine months on a single coin cell battery and can perform ranging operations on demand in near real-time, all while maintaining a localization accuracy within five meters.