Topic
Cristian's algorithm
About: Cristian's algorithm is a research topic. Over the lifetime, 33 publications have been published within this topic receiving 745 citations.
Papers
27 Aug 1984
TL;DR: A new fault-tolerant algorithm for solving a variant of Lamport's clock synchronization problem for a system of distributed processes that communicate by sending messages, which solves the problem of maintaining closely synchronized local times, assuming that processes' local times are closely synchronized initially.
Abstract: We describe a new fault-tolerant algorithm for solving a variant of Lamport's clock synchronization problem. The algorithm is designed for a system of distributed processes that communicate by sending messages. Each process has its own read-only physical clock whose drift rate from real time is very small. By adding a value to its physical clock time, the process obtains its local time. The algorithm solves the problem of maintaining closely synchronized local times, assuming that processes' local times are closely synchronized initially. The algorithm is able to tolerate the failure of just under a third of the participating processes. It maintains synchronization to within a small constant, whose magnitude depends upon the rate of clock drift, the message delivery time, and the inital closeness of synchronization. We also give a characterization of how far the clocks drift from real time. Reintegration of a repaired process can be accomplished using a slight modification of the basic algorithm. A similar style algorithm can also be used to achieve synchronization initially.
361 citations
26 Apr 2004
TL;DR: This work describes a probabilistic method for clock synchronization that uses the higher precision of receiver-to-receiver synchronization, as described in reference broadcast synchronization (RBS) protocol, and extends this protocol for maintaining clock synchronization in a multihop network.
Abstract: Recent advances in technology have made low cost, low power wireless sensors a reality. Clock synchronization is an important service in any distributed system, including sensor network systems. Applications of clock synchronization in sensor networks include data integration in sensors, sensor reading fusion, TDMA medium access scheduling, and power mode energy saving. However, for a number of reasons, standard clock synchronization protocols are unsuitable for direct application in sensor networks. In this paper, we introduce the concept of adaptive clock synchronization based on the need of the application and the resource constraint in the sensor networks. We describe a probabilistic method for clock synchronization that uses the higher precision of receiver-to-receiver synchronization, as described in Reference Broadcast Synchronization (RBS) protocol. This deterministic protocol is extended to provide a probabilistic bound on the accuracy of the clock synchronization, allowing for a tradeo between accuracy and resource requirement. Expressions to convert service specifications (maximum clock synchronization error and confidence probability) to actual protocol parameters (minimum number of messages and synchronization overhead) are derived. Further, we extend this protocol for maintaining clock synchronization in a multihop network.
184 citations
TL;DR: The principle that a bounded monotonic sequence must possess a limit and the concept of maximum consensus are exploited to design a novel clock synchronization algorithm for the network to achieve accurate and fast synchronization.
54 citations
22 Apr 2013
TL;DR: Parts of the network which influence the accuracy of packed based time synchronization in Wireless Sensor Networks are investigated and clock stability, clock resolution, time-stamping moment, physical layer property, communication aspects, synchronization time, number of synchronization messages, synchronization interval and synchronization algorithm are identified.
Abstract: Accurate time synchronization is crucial for many applications of Wireless Sensor Networks. Extensive research is performed on this topic, however, there are some aspects of time synchronization which still require attention. In this thesis we investigate aspects of the network which influence the accuracy of packed based time synchronization in Wireless Sensor Networks. The network of four nodes that are capable of wireless communication is constructed. Each node consists of Arduino Mega board with ATMEGA2560 micro-controller and RZ502 Accessory Kit with AT86RF230 radio chip. Three time-stamp exchange models are implemented on this network to synchronize the clocks and and compared with each other. The estimation of the synchronization parameters is done using Least Square estimators. Phase offset, frequency offset and communication delay are required to be estimated during the synchronization. From basic time-stamp exchange scheme, only sender-receiver model enables the estimation of the communication delay. The global synchronization leads to more accurate synchronization compared to the pair-wise synchronization. Based on the constructed setup, the aspects which influence the accuracy of time synchronization are identified: clock stability, clock resolution, time-stamping moment, physical layer property, communication aspects, synchronization time, number of synchronization messages, synchronization interval, time-stamp exchange model and synchronization algorithm. The requirements on these aspects are derived from the demand on the accuracy of the synchronization.
31 citations
25 Oct 2010
TL;DR: The results of test show that the improved method can effectively increased the clock synchronization accuracy under asymmetric communication paths.
Abstract: In order to satisfy the request for precise clock synchronization in industry Ethernet, this paper has conducted the research to the IEEE1588 high-precision time synchronization algorithm, carried on the elaboration to the principle of algorithm, proposed the corresponding improvement algorithm for asymmetric communication paths and got it verified. The results of test show that the improved method can effectively increased the clock synchronization accuracy under asymmetric communication paths.
16 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2017 | 1 |
| 2014 | 3 |
| 2013 | 4 |
| 2012 | 3 |
| 2011 | 4 |
| 2010 | 3 |