High-Precision Low-Power Wireless Nodes’ Synchronization via Decentralized Control

Abstract

Time synchronization is crucial for wireless sensor networks (WSNs), where operations often rely on time ordering of events. WSNs are deployed in different scenarios, and therefore their timing requirements are often related to the peculiar characteristics of the specific environment they have to act in. Synchronization is anyway always an issue: transactional applications need monotonicity of the nodes' clocks to avoid time reversal, ultralow power applications call for minimal overhead to allow for low-duty-cycle operation, applications facing extreme environments have to maintain the needed precision in the presence of unforeseen thermal drift, and so on. Specially, control applications on battery-powered devices, where timing is an issue and low-power operation is highly desired, benefit from synchronization. However, to date, the problem of synchronization has been differently faced depending on the application domain. This paper proposes a general solution to the problem of synchronization in WSNs, which seamlessly integrates with the radio stack. In addition, it guarantees monotonic and continuous node clocks with low overhead for the infrastructure. The solution is based on a decentralized control scheme that is stable and robust to thermal stress, without the need for temperature measurements. The control scheme is simulated and implemented on real WSN nodes. The efficiency of the scheme is evaluated with simulations and experiments, providing insights on the maximum synchronization error between nodes, on the communication overhead, and on the limited nodes' power consumption. The solution is also compared with state-of-the-art alternatives.

FLOPSYNC-QACS: Quantization-aware clock synchronization for wireless sensor networks

“…Time synchronization in a distributed system is a well known and studied problem in computer science [25]- [28], and has recently gained attention in the control community as well [8], [29]. We here limit the scope to the master-slave case in which the master floods the WSN with synchronization packets at a fixed period T , constant and known networkwide.…”

“…For the correct operation of WSNs, a major challenge is accurate time synchronization [4], [5]. This is required to ensure reliable communication links, but also for location/proximity estimation [6], energy efficiency [7], [8], mobility [9], and wherever WSN nodes coordination -possibly with realtime tasks -is required. Moreover, since most WSN nodes operate on battery and synchronization must be guaranteed continuously, energy-efficient solutions are in order [10].…”

Clock synchronization algorithms for networked systems

“…(3) 基于能量、资源优化的有限时间内高效时钟同步算法实现. 无线传感器网络节点由电池供电 或依赖太阳能供电, 能量利用限制较大, 所设计的时钟同步算法的能耗大小将直接影响算法在实际网 络中的可持续应用 [101] . 已有的研究主要关注于能量对同步算法性能的影响, 并设计相应的算法来减 少能量分布不均所带来的影响, 缺乏在能量受限时的时间同步算法的研究 [102] .…”

Performance Analysis of Time Synchronization Protocols in Wireless Sensor Networks

“…A significant number of studies regarding this problem have been conducted in recent years. Many protocols and algorithms have been proposed to achieve sub-microsecond accuracy in experimental test-beds [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]. However, unlike time synchronization in wired networks, wireless networks present additional challenges such as the uncertainty of wireless transmission, energy consumption, and mobility [24].…”