A Microsecond Energy-Efficient LoRa Time Synchronization Based on Low-Layer Timestamping and Asymmetric Time Translation

High-precision time synchronization is chased by thriving Long Range (LoRa) research due to its significance for accurate monitoring, detection, and network collaboration. Only a few LoRa time synchronization methods could achieve microsecond-level accuracy, however, at the expense of extensive synchronization message exchanges. In this paper, we propose a microsecond time synchronization for the LoRa network based on low-layer timestamping and asymmetric time translation. Note that, the proposed time synchronization does not induce synchronization message transmissions at the LoRa end nodes, therefore, achieves high energy efficiency. Experimental results on a real LoRa testbed demonstrate that the proposed method achieves microsecond-level synchronization accuracy with significantly fewer synchronization message transmissions compared to the state-of-the-art.