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We present Timestamp Order Preserving (TOP), a replicated state machine (RSM) protocol that exploits the synchrony of networks to provide high performance. TOP uses physical timestamp of synchronized clock as a consistent total order to achieve consensus. It keeps estimating the bounds of network latency and offset of synchronized clock to deduce the commit time for each operation. It adopts speculative...
Over the last few years, packet based networks have become the common transport for applications requiring clock synchronization. Classical time distribution protocols are run between a master clock and a slave clock using a single network path between the two clocks. A recently introduced approach called Slave Diversity uses multiple paths between a master-slave pair to reduce the effect of temporal...
This paper reports a study and practical evaluation of two different clock synchronization methods for distributed measurement and control nodes based on Linux Single Board Computers (SBCs) with ARM processors and communicating through a TCP/IP wide area network. First the Network Time Protocol (NTP) is configured and evaluated in different network scenarios. The second solution is a specific development...
This paper presents a method for time base synchronization between independent nodes which communicate over a wireless medium. It is shown that the malicious effects of multipath propagation are minimized and precise time base synchronization is achieved.
This paper presents a method for time base synchronization between independent nodes which communicate over a wireless medium. It is shown that the malicious effects of multipath propagation are minimized and precise time base synchronization is achieved.
The synchronization is a key point in measurement and control systems, which use technologies such as network communication, local computing and distributed objects. Modern industrial application is demanding the synchronization for higher precision, this paper analyzes a variety of synchronous time synchronization protocols used in the current industrial Ethernet applications, mean-while explains...
We present a new software-based clock synchronization scheme that provides high precision time agreement among distributed memory nodes. The technique is designed to minimize variance from a reference chimer during runtime and with minimal time-request latency. Our scheme permits initial unbounded variations in time and corrects both slow and fast chimers (clock skew). An implementation developed...
Clock inaccuracies cause serious problems and troublesome in distributed systems. The clocks of different processors need to be synchronized to limit errors. This is to have an efficient communication or resource sharing. Hence the clocks need to be monitored and adjusted continuously. Otherwise, the clocks drift apart. Similarly clock skew also introduces mismatch in time value of two clocks. Both...
Shrinking process tolerances due to decreasing device sizes and increasing chip complexity in semiconductor manufacturing are motivating efforts to improve methods of equipment data acquisition (EDA). Prior work shows that the lack of precise time-stamping and clock synchronization is a critical hindrance to reliable data acquisition and real-time process control systems. The ultimate goal in the...
Expressway toll system is a complex distribution network, the synchronization of individual clock in the system is the basis of toll system and expressway management. This paper analyses the hierarchical architecture of time synchronization in the computer network of expressway toll system, and explores the characteristics and applicable conditions of several useful methods of time synchronization...
IP networks allow constructing versatile device configurations for multimedia streaming. However, the stochastic nature of the packet-switched data transmission may complicate IP-based implementations of some conventional applications such as analog wired transmission of synchronized multi-channel audio. This paper introduces a multimedia streaming system based on the synchronization of multiple playback...
3D teleimmersive (TI) environments have gained significant attention as they show promising results for a wide number of applications. These environments are usually distributed and multi platform which makes performance analysis and monitoring difficult. We present a unified time service (UTS) and its measurement framework for evaluating components in terms of their reflected QoS (e.g. delay). Then...
This paper presents a toolset formed by a timing library and a clock synchronization library for a cluster. These are tools developed to measure both execution and communication times in distributed environments for performance evaluation. The toolset scalability is shown by experimentation as well as the instrumentation of a parallel matrix multiplication algorithm, based on broadcast communications...
We present an improved algorithm to get high precision clock synchronization. In this algorithm, the initial synchronous deviation and the uncertainty of synchronization network are eliminated. Based on the underlying hardware clock, we achieve high resolution logic clock, so it supplies the practice base for this algorithm. This solution can get higher precision than the previous algorithm under...
Tokens are popular in two factor authentication, where the first authentication credential is a fixed secret key s1 associated with the user and the second authentication credential is a dynamic secret key s2 generated by the token assigned to the user. Popular hardware tokens use a synchronized clock T along with a static secret key encoded into the token to generate a one time secret s2. The contribution...
We explore the robustness of synchronization performed in the presence of variable latencies using two software clocks: the TSCclock, designed to replace ntpd for Internet synchronisation, and ptpd, a software implementation of IEEE-1588. Using a precise comparison methodology the TSCclock is shown to be more accurate and far more robust. We discuss the reasons why and the implications for IEEE-1588...
The ability to acquire quality equipment and process data is important for future real-time process control systems to maximize opportunities for semiconductor manufacturing yield enhancement and equipment efficiency. Clock synchronization for accurate time-stamping and maintaining a consistent frequency in trace data collection are essential for accurate merging of data from heterogeneous sources...
To study and gain a better understanding of the power system dynamics, the concept of building a frequency monitoring network (FNET) was proposed in 2000 [1] and has been realized in 2003. The FNET system consists of many high dynamic precision frequency and phasor estimation devices, also known as frequency disturbance recorders (FDR). These FDRs can be used at any 110 V or 220 V wall outlet and...
In distributed real-time systems, most of the end-to-end delay fluctuations, especially the delay fluctuations in the network, are bounded provided that the global network traffic loads are manually controlled to be light-weighted. This paper introduces a simple clock synchronization method in distributed real-time systems by using the traffic smoothing technique which is implemented at each end node...
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