Temperature-Compensated Clock Skew Adjustment

Castillo-Secilla, José María; Muñoz, José Manuel Palomares; Olivares, Joaquín

doi:10.3390/s130810981

Cited by 22 publications

(39 citation statements)

References 15 publications

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“…Therefore, we conjecture that if the experiment duration gets long, clock drift may become significant and the accuracy of the delay analysis could be impacted. However, for relatively short experiments (e.g., 30 minutes to an hour) and the same type of sensor nodes, clock drift does not introduce considerable errors compared with packet delays (around 2 ms for a duration of 30 mins [24,25]). To mitigate the issues with clock drift, lightweight clock calibration methods could be implemented [29].…”

Section: Discussionmentioning

confidence: 99%

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TeaCP: A Toolkit for evaluation and analysis of collection protocols in Wireless Sensor Networks

Hashemi

Warsawski

et al. 2013

2013 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems (COMCAS 2013)

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Abstract-We present TeaCP, a prototype toolkit for the evaluation and analysis of collection protocols in both simulation and experimental environments running on TinyOS. Our toolkit consists of a testing system, which runs a collection protocol of choice, and an optional SD card-based logging system, which stores the logs generated by the testing system. The SD card datalogger allows a wireless sensor network (WSN) to be deployed flexibly in various environments, especially where wired transfer of data is difficult. Using the saved logs, TeaCP evaluates a wide range of performance metrics, such as reliability, throughput, and delay. TeaCP further allows visualization of packet routes and the topology evolution of the network, under both static and dynamic conditions, even in the face of transient disconnections. Through simulation of an intra-car WSN and real lab experiments, we demonstrate the functionality of TeaCP for comparing the performance of two prominent collection protocols, the Collection Tree Protocol (CTP) and the Backpressure Collection Protocol (BCP). We also present the usage of TeaCP as a high level diagnosis tool, through which an inconsistency of the BCP implementation for the CC2420 radio chips is identified and resolved.Index Terms-Network and systems monitoring, wireless sensor networks, collection protocol, performance evaluation and visualization, opensource toolkit.

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Section: Discussionmentioning

confidence: 99%

“…However, for relatively short experiments (e.g., 30 minutes to an hour) and the same type of sensor nodes, the amount of clock drift is negligible compared to packet delays (around 2 ms for a duration of 30 mins [24,25]). The issue of time synchronization is further discussed in Section V.…”

Section: ) Delay Performancementioning

confidence: 99%

TeaCP: A Toolkit for evaluation and analysis of collection protocols in Wireless Sensor Networks

Hashemi

Warsawski

et al. 2013

2013 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems (COMCAS 2013)

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“…The values of

s k e w_{temp}

shown are computed assuming that the reference oscillator remains stabilized at

25^{\circ}

(thus, it does not suffer from any temperature influence). The expected

s k e w_{temp}

is obtained using Equation (14), which can be derived from the quadratic relationship formula of the tuning-fork [15].

E x p e c t e d S k e w_{temp} = 1 + β \cdot {(T - 25^{\circ})}^{2}

…”

Section: Hypothesis Demonstrationmentioning

confidence: 99%

Homomorphic Filtering for Improving Time Synchronization in Wireless Networks

Castillo-Secilla

Muñoz

León

et al. 2017

Sensors

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Wireless sensor networks are used to sample the environment in a distributed way. Therefore, it is mandatory for all of the measurements to be tightly synchronized in order to guarantee that every sensor is sampling the environment at the exact same instant of time. The synchronization drift gets bigger in environments suffering from temperature variations. Thus, this work is focused on improving time synchronization under deployments with temperature variations. The working hypothesis demonstrated in this work is that the clock skew of two nodes (the ratio of the real frequencies of the oscillators) is composed of a multiplicative combination of two main components: the clock skew due to the variations between the cut of the crystal of each oscillator and the clock skew due to the different temperatures affecting the nodes. By applying a nonlinear filtering, the homomorphic filtering, both components are separated in an effective way. A correction factor based on temperature, which can be applied to any synchronization protocol, is proposed. For testing it, an improvement of the FTSP synchronization protocol has been developed and physically tested under temperature variation scenarios using TelosB motes flashed with the IEEE 802.15.4 implementation supplied by TinyOS.

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“…With the embedded thermometer in the processor, it is possible to make a software correction for the temperature based frequency drift. Similar methods have been used by [21] and [22]. Experiments were performed in order to test accuracy of the theoretical model for low cost oscillators.…”

Section: Frequency and Frequency Vs Temperature Calibrationmentioning

confidence: 99%

Simultaneity Analysis In A Wireless Sensor Network

Malović¹,

Brajović²,

Mišković³

et al. 2015

Metrology and Measurement Systems

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An original wireless sensor network for vibration measurements was designed. Its primary purpose is modal analysis of vibrations of large structures. A number of experiments have been performed to evaluate the system, with special emphasis on the influence of different effects on simultaneity of data acquired from remote nodes, which is essential for modal analysis. One of the issues is that quartz crystal oscillators, which provide time reading on the devices, are optimized for use in the room temperature and exhibit significant frequency variations if operated outside the 20-30°C range. Although much research was performed to optimize algorithms of synchronization in wireless networks, the subject of temperature fluctuations was not investigated and discussed in proportion to its significance. This paper describes methods used to evaluate data simultaneity and some algorithms suitable for its improvement in small to intermediate size ad-hoc wireless sensor networks exposed to varying temperatures often present in on-site civil engineering measurements.

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Temperature-Compensated Clock Skew Adjustment

Cited by 22 publications

References 15 publications

TeaCP: A Toolkit for evaluation and analysis of collection protocols in Wireless Sensor Networks

TeaCP: A Toolkit for evaluation and analysis of collection protocols in Wireless Sensor Networks

Homomorphic Filtering for Improving Time Synchronization in Wireless Networks

Simultaneity Analysis In A Wireless Sensor Network

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