A step forward the on-line minimization of the synchronization events in TPSN
13 May 2012-pp 2780-2784
TL;DR: An experimental approach to the optimization of synchronization protocols for wireless sensor networks by proposing that the sensor node be synchronized with the master node on the basis of two suitable figures of merit: the former takes into account the past synchronizations, whilst the latter depends on the residual error after the last synchronization.
Abstract: The paper proposes an experimental approach to the optimization of synchronization protocols for wireless sensor networks. The authors' research is aimed in both minimizing the synchronization residual error and the wireless sensor node energy consumption. The approach has been thought to be applied to different synchronization protocols and to give the best results for small scale wireless sensor network. In particular, results concerning the well know Timing Synchronization Protocol for Sensor Networks (TPSN) are presented in the paper. The main idea is that the sensor node be synchronized with the master node on the basis of two suitable figures of merit: the former takes into account the past synchronizations, whilst the latter depends on the residual error after the last synchronization. On the basis of the on board and real time evaluation of these two indexes the number of synchronization events and the node energy consumption can be both reduced.
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06 May 2013
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12 citations
Cites methods from "A step forward the on-line minimiza..."
...In this scenario, stemming from previous experiences in fields of the SG [17], [18], sensor networks performance characterization [19]-[21], measurement uncertainties in communication networks [22]-[25], the authors propose a study...
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14 Nov 2013
TL;DR: This work analyzes the performance considering real sensor nodes equipped with specific features for the access to time information at media access control (MAC) layer forocol based time synchronization in wireless sensor networks.
Abstract: Protocol based time synchronization in wireless sensor networks is a relevant issue for many researchers. In literature many papers dealing with the design and characterization of several techniques for synchronization can be found. Some of them consider only performance analysis in simulation environment, others analyze the performance considering real sensor nodes equipped with specific features for the access to time information (i.e. timestamps) at media access control (MAC) layer.
5 citations
Cites methods from "A step forward the on-line minimiza..."
...In particular, they have designed new wireless sensor nodes [12] and wireless interface architectures [7], as well as implemented and experimentally characterized the performance of synchronization schemes based on both two-ways messaging and regression-based protocols [13], [14]....
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01 Jan 2015
TL;DR: A semi-active RFID module for remote monitoring of storage conditions during the transportation is proposed that integrates one SmartTag and some sensors, and allows also to locate the object to the one which is related.
Abstract: In this paper a semi-active RFID module for remote monitoring of storage conditions during the transportation is proposed. It integrates one SmartTag and some sensors, and allows also to locate the object to the one which is related. In order to obtain the real time observing on the transportation vehicle an On Board Unit (OBU) is installed that works as a concentrator and communicates with a central control room.
2 citations
References
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TL;DR: The concept of sensor networks which has been made viable by the convergence of micro-electro-mechanical systems technology, wireless communications and digital electronics is described.
17,936 citations
09 Dec 2002
TL;DR: Reference Broadcast Synchronization (RBS) as discussed by the authors is a scheme in which nodes send reference beacons to their neighbors using physical-layer broadcasts, and receivers use their arrival time as a point of reference for comparing their clocks.
Abstract: Recent advances in miniaturization and low-cost, low-power design have led to active research in large-scale networks of small, wireless, low-power sensors and actuators. Time synchronization is critical in sensor networks for diverse purposes including sensor data fusion, coordinated actuation, and power-efficient duty cycling. Though the clock accuracy and precision requirements are often stricter than in traditional distributed systems, strict energy constraints limit the resources available to meet these goals.We present Reference-Broadcast Synchronization, a scheme in which nodes send reference beacons to their neighbors using physical-layer broadcasts. A reference broadcast does not contain an explicit timestamp; instead, receivers use its arrival time as a point of reference for comparing their clocks. In this paper, we use measurements from two wireless implementations to show that removing the sender's nondeterminism from the critical path in this way produces high-precision clock agreement (1.85 ± 1.28μsec, using off-the-shelf 802.11 wireless Ethernet), while using minimal energy. We also describe a novel algorithm that uses this same broadcast property to federate clocks across broadcast domains with a slow decay in precision (3.68 ± 2.57μsec after 4 hops). RBS can be used without external references, forming a precise relative timescale, or can maintain microsecond-level synchronization to an external timescale such as UTC. We show a significant improvement over the Network Time Protocol (NTP) under similar conditions.
2,537 citations
03 Nov 2004
TL;DR: The FTSP achieves its robustness by utilizing periodic flooding of synchronization messages, and implicit dynamic topology update and comprehensive error compensation including clock skew estimation, which is markedly better than that of the existing RBS and TPSN algorithms.
Abstract: Wireless sensor network applications, similarly to other distributed systems, often require a scalable time synchronization service enabling data consistency and coordination. This paper describes the Flooding Time Synchronization Protocol (FTSP), especially tailored for applications requiring stringent precision on resource limited wireless platforms. The proposed time synchronization protocol uses low communication bandwidth and it is robust against node and link failures. The FTSP achieves its robustness by utilizing periodic flooding of synchronization messages, and implicit dynamic topology update. The unique high precision performance is reached by utilizing MAC-layer time-stamping and comprehensive error compensation including clock skew estimation. The sources of delays and uncertainties in message transmission are analyzed in detail and techniques are presented to mitigate their effects. The FTSP was implemented on the Berkeley Mica2 platform and evaluated in a 60-node, multi-hop setup. The average per-hop synchronization error was in the one microsecond range, which is markedly better than that of the existing RBS and TPSN algorithms.
2,267 citations
"A step forward the on-line minimiza..." refers background in this paper
...Among the others, Timing Synch Protocol for Sensor Networks (TPSN) [5], Reference Broadcast Synchronization (RBS) [6] and Flooding Time Synch Protocol (FTSP) [7] have been intentionally designed for low power WSNs and are the most widespread thanks to their simple implementation and low memory requirements....
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05 Nov 2003
TL;DR: It is argued that TPSN roughly gives a 2x better performance as compared to Reference Broadcast Synchronization (RBS) and verify this by implementing RBS on motes and use simulations to verify its accuracy over large-scale networks.
Abstract: Wireless ad-hoc sensor networks have emerged as an interesting and important research area in the last few years. The applications envisioned for such networks require collaborative execution of a distributed task amongst a large set of sensor nodes. This is realized by exchanging messages that are time-stamped using the local clocks on the nodes. Therefore, time synchronization becomes an indispensable piece of infrastructure in such systems. For years, protocols such as NTP have kept the clocks of networked systems in perfect synchrony. However, this new class of networks has a large density of nodes and very limited energy resource at every node; this leads to scalability requirements while limiting the resources that can be used to achieve them. A new approach to time synchronization is needed for sensor networks.In this paper, we present Timing-sync Protocol for Sensor Networks (TPSN) that aims at providing network-wide time synchronization in a sensor network. The algorithm works in two steps. In the first step, a hierarchical structure is established in the network and then a pair wise synchronization is performed along the edges of this structure to establish a global timescale throughout the network. Eventually all nodes in the network synchronize their clocks to a reference node. We implement our algorithm on Berkeley motes and show that it can synchronize a pair of neighboring motes to an average accuracy of less than 20ms. We argue that TPSN roughly gives a 2x better performance as compared to Reference Broadcast Synchronization (RBS) and verify this by implementing RBS on motes. We also show the performance of TPSN over small multihop networks of motes and use simulations to verify its accuracy over large-scale networks. We show that the synchronization accuracy does not degrade significantly with the increase in number of nodes being deployed, making TPSN completely scalable.
2,215 citations
"A step forward the on-line minimiza..." refers background in this paper
...Recent literature is proposing many efficient algorithms for WSNs synchronization [5]-[10]....
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...For the sake of brevity, only the TPSN synchronization protocol is considered in this paper....
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...In particular, to allow executing a number of virtual synchronizations rather than real ones the reliable knowledge of the ∆ and d indexes provided by the TPSN synchronization protocol and defined in equation (1) is required....
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...Among the others, Timing Synch Protocol for Sensor Networks (TPSN) [5], Reference Broadcast Synchronization (RBS) [6] and Flooding Time Synch Protocol (FTSP) [7] have been intentionally designed for low power WSNs and are the most widespread thanks to their simple implementation and low memory requirements....
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...Keywords: wireless sensor network, synchronization, measurement, TPSN; I. INTRODUCTION In recent years a growing number of people has been interested in the world of sensor networks, both for scientific and industrial purposes....
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01 May 2005
TL;DR: In this paper, a survey and evaluation of clock synchronization protocols based on a palette of factors such as precision, accuracy, cost, and complexity is presented, which can help developers either in choosing an existing synchronization protocol or in defining a new protocol that is best suited to the specific needs of a sensor network application.
Abstract: Recent advances in micro-electromechanical (MEMS) technology have led to the development of small, low-cost, and low-power sensors Wireless sensor networks (WSNs) are large-scale networks of such sensors, dedicated to observing and monitoring various aspects of the physical world In such networks, data from each sensor is agglomerated using data fusion to form a single meaningful result, which makes time synchronization between sensors highly desirable This paper surveys and evaluates existing clock synchronization protocols based on a palette of factors like precision, accuracy, cost, and complexity The design considerations presented here can help developers either in choosing an existing synchronization protocol or in defining a new protocol that is best suited to the specific needs of a sensor-network application Finally, the survey provides a valuable framework by which designers can compare new and existing synchronization protocols
1,018 citations