*Article* **LPSRS: Low-Power Multi-Hop Synchronization Based on Reference Node Scheduling for Internet of Things**

**Mahmoud Elsharief 1,2, Mohamed A. Abd El-Gawad 3, Haneul Ko <sup>4</sup> and Sangheon Pack 5,\***


**Abstract:** Time synchronization is one of the most fundamental problems on the internet of things (IoT). The IoT requires low power and an efficient synchronization protocol to minimize power consumption and conserve battery power. This paper introduces an efficient method for time synchronization in the IoT called low-power multi-hop synchronization (LPSRS). It employs a reference node scheduling mechanism to avoid packet collisions and minimize the communication overhead, which has a big impact on power consumption. The performance of LPSRS has been evaluated and compared to previous synchronization methods, HRTS and R-Sync, via real hardware networks and simulations. The results show that LPSRS achieves a better performance in terms of power consumption (transmitted messages). In particular, for a large network of 450 nodes, LPSRS reduced the total number of transmitted messages by 53% and 49% compared to HRTS and R-Sync, respectively.

**Keywords:** HRTS; IoT; LPSRS; low power; R-sync; scheduling; time synchronization
