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In both wired and wireless networks, time synchronization is an important service for a wide range of applications in distributed systems. This includes radio interferometry. However, literature researches show that many distributed protocols cannot satisfy sub-ns time synchronization accuracy due to asymmetric delay errors, accumulated jitters and because of the strategy used to compute and adjust...
Distributed cyber-physical systems (CPS) are increasingly provided with an accurate and precise common sense of time using a variety of well established time distribution methods such as GNSS, IEEE 1588 and others. Less attention has been paid to the effective use of time in CPS and techniques and components to support such use. This paper reviews these topics and discusses critical components that...
Computer and telecommunications advances in the last years allowed new distributed applications developments. In this context, time synchronization is a very important issue. Many industrial sectors, such as financial and power, need to achieve high time accuracy. The IEEE 1588–2008 standard [1] defines the second version of PTP, designed to archive clock accuracy in the sub-microsecond range. Previous...
Various applications require or can benefit from high accuracy of synchronization between networked elements. The White Rabbit (WR) project includes enhancements to the now widespread IEEE1588 Precision Time Protocol (PTP) to support supplying synchronization in the sub-nanosecond level.
Tight synchronization timing is expected to play a crucial role for the realization of emerging Internet of Things (IoT) high value real-time applications such as smart transportation and smart grid. Most packet-based synchronization protocols require two-way communications delay symmetry for precise accuracy. The Precision Time Protocol (PTP) provides mechanisms to measure and take into account the...
We investigated the performance of the IEEE 802.1AS time synchronization protocol and its usage in in-vehicle networks by assessing the precise time synchronization mechanisms, such as offset correction, rate correction and the automatic optimal sync message period. In particular, this paper presents a method for adjusting the optimal synchronization message period to achieve high-precision time synchronization...
Wireless sensor networks (WSNs) powered by energy harvesting is a promising technology for monitoring and diagnostic systems in smart grid. However, the limitation and instability of harvesting energy leads to the requirement of high energy-efficient time synchronization algorithms for WSNs. In this paper, in order to minimize the energy consumption, we propose an improved hybrid time synchronization...
Time synchronization provides an essential service for wireless sensor networks. In this paper, we present a new synchronization algorithm which is based on average time synchronization in two-way message exchanges. Firstly, the proposed algorithm does not rely on any reference (or root) nodes, therefore, is totally distributed, asynchronous, robust to node failure or changes of network topology....
According to such problems as acquisition terminal and smart meter's real-time deviation is large which has lead to TOU power price and ladder power price policy difficult to successfully implement in electricity information acquisition system, this paper has applied GPS clock synchronization technology and PTP clock synchronization technology in electricity information acquisition system's simulation...
We present an evaluation of the accuracy of an adherence monitoring add-on device (SmartTurbo v2.0, Nexus6 Limited, Auckland, New Zealand) designed to fit a commercial inhalation device (Turbuhaler®, dry powder inhaler, AstraZeneca). The evaluation has been based on simulated reallife placebo usage by 11 patients and carried out during a 12 day period. The simulated usage covered low and high inhalation...
This session presents a new technique to verify synchronization protocols on RTL designs that automatically extract synchronizers from a flat design, and helkps to formally verify the correctness of the implemented synchronization protocol. It also present an approach to dynamically tune the time quantum in temporally decoupled simulations in order to improve the accuracy/performance tradeoff in virtual...
In recent years, issues of Wireless Sensor Networks (WSNs) have been widely studied. The energy is limited in WSNs. However, it always takes much energy to achieve highly accurate time synchronization. In this paper, a Spanning Tree-based Energy-efficient Time Synchronization (STETS) strategy for WSNs is proposed. In STETS, only a small number of sensor nodes in the WSN have the privilege to send...
In this work, we consider a space network time synchronization protocol which is based on time information exchanges similar to Network Time Protocol. Further, we analyze the performance of this time protocol due to relative motion with two spacecraft through using STK and Mat lab software jointly simulation. Regard the influencing factors such as relative distance between the two spacecraft, the...
With the continuous development of the space technology, increasing communication between spacecrafts. To ensure the spacecrafts keep a uniform time standard, time synchronization protocol plays an crucial role. Taking account the characteristics of deep-space: poor link quality, limited node computing power, and the GNSS service is unstable, through the improving of IEEE1588 protocol, a autonomous...
Delay is one of the main parameters in determining quality of service and topology of network. One way delay provides us with more information than that a round trip time does and it also involves more intricate calculations. In this paper, two measuring devices are designed and implemented that can measure the one way delay present between two distant points in web environment using GPS clock and...
In order to reduce the cost and acquire the microsecond-level time synchronization, this paper has proposed the DF-NTP (Double filter NTP) and analyzed the algorithm of NTP (network time protocol) and the causes of synchronization error. The precision of time synchronization can be raised through filtrating the delay in the forward-backward path and reducing the influence of uncertain delay. The experimental...
The emergence of Wireless Sensor Networks (WSNs) applications such as localizing, tracking, surveillance, speedometers, and so on, synchronizing sensor motes' clocks is essential in WSNs. Thus, many time synchronization protocols are proposed in recent decade to get network wide synchronization. Each of those protocols strives to get a good precision in different ways. This paper aims to review some...
We consider the clock synchronization problem in wireless mobile ad hoc networks in the presence of Byzantine nodes. The communication topology is dynamic: nodes move randomly within a geographical area. We propose a clock synchronization protocol which is based on the linear approximate consensus method. Periodically each correct node broadcasts its current timestamp and gathers the timestamps provided...
This paper proposes a Delay Asymmetry Correction (DAC) Model to enhance clock synchronization protocols based on a Master-Slave arrangement such as the IEEE 1588 PTP protocol. The purpose of this work is to mitigate the effects of unpredictable packet delay variations (PDV), which may aggravate asymmetric link delays on timing packets, in order to improve the synchronization accuracy of the slave...
Traditionally, the architecture of control system in large physics experiment is based on PLC and DCS like EPICS. For the control information in controls system, its timestamp is marked in control computer after transferred from PLC to computer. This mode will introduce more time deviation in time stamp. In CSNS, we will use a new PLC from BECKHOFF which can provide real-time timestamp, and we can...
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