Per-Hop Delay Compensation in Time Synchronization for Multi-Hop Wireless Sensor Networks Based on Packet-Relaying Gateways

Multi-hop time synchronization is essential to large-scale deployment of IoT and wireless sensor networks. Its performance, however, is affected by the processing delays at intermediate gateway nodes, which cause cumulative synchronization error. To address this, we propose a per-hop delay compensation scheme as a simple and effective multi-hop extension option based on packet-relaying gateway nodes for energy-efficient time synchronization in wireless sensor networks. Experimental results on a real testbed demonstrate that the per-hop delay compensation scheme significantly improves the multi-hop time synchronization performance when applied to the state-of-the-art beaconless asymmetric energy-efficient time synchronization scheme and the conventional flooding time synchronization protocol.