Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070147
J. Mackay, Ron Murdock, Gregory Hall
There are several applications for position location that require a solution that minimizes size and power. In the case of planetary navigation, these constraints are critical due to the cost of deployment. This paper describes the analysis, design, and prototyping of a system that takes advantage of a common time-base provided by IEEE 1588 Precision Time Protocol (PTP) to use minimal processing algorithms and processing resources.
{"title":"Applying IEEE 1588 to packet radio trilateration","authors":"J. Mackay, Ron Murdock, Gregory Hall","doi":"10.1109/ISPCS.2011.6070147","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070147","url":null,"abstract":"There are several applications for position location that require a solution that minimizes size and power. In the case of planetary navigation, these constraints are critical due to the cost of deployment. This paper describes the analysis, design, and prototyping of a system that takes advantage of a common time-base provided by IEEE 1588 Precision Time Protocol (PTP) to use minimal processing algorithms and processing resources.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114383599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070142
D. Fontanelli, D. Macii, P. Wolfrum, D. Obradovic, Guenter Steindl
In industrial automation networks based on the Precision Time Protocol (PTP) large temperature changes as well as mechanical shocks and vibrations may severely affect the performance of the local oscillators clocking the network nodes, thus making accurate time synchronization challenging. This problem is particularly critical in large industrial networks with long linear paths, as multiple uncertainty sources tend to accumulate while PTP event messages are forwarded towards the slave clocks. In this paper, the performance of a clock state estimator based on a special Kalman filter as well as on a detailed model of the PTP communication mechanism is described. The reported simulation results when the network nodes are subject to changeable environmental conditions provide interesting guidelines to keep synchronization accuracy in industrial networks within given boundaries.
{"title":"A clock state estimator for PTP time synchronization in harsh environmental conditions","authors":"D. Fontanelli, D. Macii, P. Wolfrum, D. Obradovic, Guenter Steindl","doi":"10.1109/ISPCS.2011.6070142","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070142","url":null,"abstract":"In industrial automation networks based on the Precision Time Protocol (PTP) large temperature changes as well as mechanical shocks and vibrations may severely affect the performance of the local oscillators clocking the network nodes, thus making accurate time synchronization challenging. This problem is particularly critical in large industrial networks with long linear paths, as multiple uncertainty sources tend to accumulate while PTP event messages are forwarded towards the slave clocks. In this paper, the performance of a clock state estimator based on a special Kalman filter as well as on a detailed model of the PTP communication mechanism is described. The reported simulation results when the network nodes are subject to changeable environmental conditions provide interesting guidelines to keep synchronization accuracy in industrial networks within given boundaries.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120899033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070150
C. M. D. Dominicis, A. Flammini, S. Rinaldi, E. Sisinni, A. Cazzorla, A. Moschitta, P. Carbone
The work presented in this paper is related with time synchronization for wireless networks. In particular, it is focused on the proposal and experimental evaluation of a low-cost and high precision timestamping technique based on Ultra Wide Band (UWB) signalling. In recent years, the use of such systems has gained an increasing success thanks to their robustness to interferers and multipath. In this paper a new hybrid wireless node is proposed; a traditional IEEE802.15.4 radio, the reference physical layer for wireless sensor networks, is supported by an UWB transceiver. The former is used for communication purposes and allows to preserve compatibility with already installed infrastructures/networks; the latter is used for time of arrival estimation. Hardware prototypes have been realized and experimental tests have shown a sub-nanosecond accuracy. A comparison with commercial solutions has shown a performance improvement with respect to conventional approaches.
{"title":"High-precision UWB-based timestamping","authors":"C. M. D. Dominicis, A. Flammini, S. Rinaldi, E. Sisinni, A. Cazzorla, A. Moschitta, P. Carbone","doi":"10.1109/ISPCS.2011.6070150","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070150","url":null,"abstract":"The work presented in this paper is related with time synchronization for wireless networks. In particular, it is focused on the proposal and experimental evaluation of a low-cost and high precision timestamping technique based on Ultra Wide Band (UWB) signalling. In recent years, the use of such systems has gained an increasing success thanks to their robustness to interferers and multipath. In this paper a new hybrid wireless node is proposed; a traditional IEEE802.15.4 radio, the reference physical layer for wireless sensor networks, is supported by an UWB transceiver. The former is used for communication purposes and allows to preserve compatibility with already installed infrastructures/networks; the latter is used for time of arrival estimation. Hardware prototypes have been realized and experimental tests have shown a sub-nanosecond accuracy. A comparison with commercial solutions has shown a performance improvement with respect to conventional approaches.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121876353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070158
Richard T. Cochran, C. Marinescu, C. Riesch
As computer and embedded systems are becoming more complex and distributed, keeping accurate time throughout the whole system becomes a challenging task. The IEEE 1588 Precision Time Protocol was designed to achieve very accurate synchronization in distributed environments. Linux is becoming the leading operating system for embedded devices, but little attention has been paid to the issue of how to internally synchronize the Linux system clock with the PTP hardware clock. Our paper presents the current status in this area, highlights possible solutions for this problem, and describes our efforts to address this key issue.
{"title":"Synchronizing the Linux system time to a PTP hardware clock","authors":"Richard T. Cochran, C. Marinescu, C. Riesch","doi":"10.1109/ISPCS.2011.6070158","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070158","url":null,"abstract":"As computer and embedded systems are becoming more complex and distributed, keeping accurate time throughout the whole system becomes a challenging task. The IEEE 1588 Precision Time Protocol was designed to achieve very accurate synchronization in distributed environments. Linux is becoming the leading operating system for embedded devices, but little attention has been paid to the issue of how to internally synchronize the Linux system clock with the PTP hardware clock. Our paper presents the current status in this area, highlights possible solutions for this problem, and describes our efforts to address this key issue.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117146229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070153
Tal Mizrahi
The wide deployment of the IEEE 1588 Precision Time Protocol (PTP) raises significant security concerns; its quick assimilation has outrun security standardization efforts. In the absence of a standard security solution for PTP, several different alternatives have been suggested as a means to fill this vacuum using existing off-the-shelf security protocols. In this paper, we analyze PTP security solutions using two such protocols; IPsec and MACsec. We characterize the common deployment scenarios for PTP using these protocols, and then present a security threat analysis under these scenarios.
{"title":"Time synchronization security using IPsec and MACsec","authors":"Tal Mizrahi","doi":"10.1109/ISPCS.2011.6070153","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070153","url":null,"abstract":"The wide deployment of the IEEE 1588 Precision Time Protocol (PTP) raises significant security concerns; its quick assimilation has outrun security standardization efforts. In the absence of a standard security solution for PTP, several different alternatives have been suggested as a means to fill this vacuum using existing off-the-shelf security protocols. In this paper, we analyze PTP security solutions using two such protocols; IPsec and MACsec. We characterize the common deployment scenarios for PTP using these protocols, and then present a security threat analysis under these scenarios.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126795502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070152
A. Mahmood, G. Gaderer, H. Trsek, Stefan Schwalowsky, N. Kero
The introduction of the precision time protocol has brought forth the possibility to have a standardised synchronization mechanism in networks, independent from the actual communication technology. However, it can be observed, for example in the annexes of the standard, that many implementations focus only on Ethernet based communication. The logical next step is to investigate how this protocol will fare when used for synchronizing clocks in a distributed manner over IEEE 802.11 based devices. The availability of features like roaming, the broadcast nature of the wireless medium and different hardware platform architectures require an investigation on how clock synchronization can be realized in wireless environments. This paper proposes an approach to import the precision time protocol to IEEE 802.11. Furthermore, standard nodes are enhanced with software timestamping, leading to a synchronization accuracy of a few microseconds.
{"title":"Towards high accuracy in IEEE 802.11 based clock synchronization using PTP","authors":"A. Mahmood, G. Gaderer, H. Trsek, Stefan Schwalowsky, N. Kero","doi":"10.1109/ISPCS.2011.6070152","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070152","url":null,"abstract":"The introduction of the precision time protocol has brought forth the possibility to have a standardised synchronization mechanism in networks, independent from the actual communication technology. However, it can be observed, for example in the annexes of the standard, that many implementations focus only on Ethernet based communication. The logical next step is to investigate how this protocol will fare when used for synchronizing clocks in a distributed manner over IEEE 802.11 based devices. The availability of features like roaming, the broadcast nature of the wireless medium and different hardware platform architectures require an investigation on how clock synchronization can be realized in wireless environments. This paper proposes an approach to import the precision time protocol to IEEE 802.11. Furthermore, standard nodes are enhanced with software timestamping, leading to a synchronization accuracy of a few microseconds.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125065941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070141
Dinh Thai Bui, M. le Pallec
the IEEE 1588-2008 standard [1] introduces and specifies Boundary Clock (BC) and Transparent Clock (TC) concepts in order to address stringent time distribution requirements (e.g. 1 µs accuracy for the end application) across a communication network. Both concepts present different strengths and weaknesses which are generally used as arguments to oppose one against the other. This paper, on the contrary, is advocating for the implementation of both functionalities on the same network node with regards to the great commonalities and complementarities between them. Going further on this complementary approach, this contribution proposes a hybrid module aiming at combining different advantages offered respectively by BC and TC concepts.
{"title":"Dual and hybrid PTP modules","authors":"Dinh Thai Bui, M. le Pallec","doi":"10.1109/ISPCS.2011.6070141","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070141","url":null,"abstract":"the IEEE 1588-2008 standard [1] introduces and specifies Boundary Clock (BC) and Transparent Clock (TC) concepts in order to address stringent time distribution requirements (e.g. 1 µs accuracy for the end application) across a communication network. Both concepts present different strengths and weaknesses which are generally used as arguments to oppose one against the other. This paper, on the contrary, is advocating for the implementation of both functionalities on the same network node with regards to the great commonalities and complementarities between them. Going further on this complementary approach, this contribution proposes a hybrid module aiming at combining different advantages offered respectively by BC and TC concepts.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124113468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070148
M. Lipinski, T. Wlostowski, J. Serrano, P. Alvarez
This article describes time distribution in a White Rabbit Network. We start by presenting a short overview of the White Rabbit project explaining its requirements to highlight the importance of the timing aspects of the system. We then introduce the technologies used to achieve high clock accuracy, stability and resilience in all the components of the network. In particular, the choice of the IEEE 1588-2008 (PTP) and Synchronous Ethernet standards are explained. In order to accommodate hardware-supported mechanisms to increase PTP synchronization accuracy, we introduce the White Rabbit extension to PTP (WRPTP). The hardware used to supportWRPTP is presented.Measured results of WRPTP performance demonstrate sub-nanosecond accuracy over a 5km fiber optic link with a precision below 10ps and a reduced PTP-message exchange rate. Tests of the implementation show full compatibility with existing PTP gear.
{"title":"White rabbit: a PTP application for robust sub-nanosecond synchronization","authors":"M. Lipinski, T. Wlostowski, J. Serrano, P. Alvarez","doi":"10.1109/ISPCS.2011.6070148","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070148","url":null,"abstract":"This article describes time distribution in a White Rabbit Network. We start by presenting a short overview of the White Rabbit project explaining its requirements to highlight the importance of the timing aspects of the system. We then introduce the technologies used to achieve high clock accuracy, stability and resilience in all the components of the network. In particular, the choice of the IEEE 1588-2008 (PTP) and Synchronous Ethernet standards are explained. In order to accommodate hardware-supported mechanisms to increase PTP synchronization accuracy, we introduce the White Rabbit extension to PTP (WRPTP). The hardware used to supportWRPTP is presented.Measured results of WRPTP performance demonstrate sub-nanosecond accuracy over a 5km fiber optic link with a precision below 10ps and a reduced PTP-message exchange rate. Tests of the implementation show full compatibility with existing PTP gear.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"457 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116502284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070151
Natasa Simanic, R. Exel, P. Loschmidt, Thomas Bigler, N. Kero
Clock synchronization has become an indispensable service in most distributed systems as it allows to sort events on a common time scale and coordinate collaborative actions.With the demand for even higher synchronization accuracy, new challenges and barriers have to be tackled to fulfill these requirements. One of them, the inevitable signal propagation time between the devices, is compensated in many state-of-the-art synchronization protocols by round-trip measurements, neglecting any form of delay asymmetry of the communication link. In this paper, we analyze the impact of asymmetry in networks based on the physical layer of copper-based Ethernet and compare different approaches on how to mitigate the impact of asymmetry. We propose a non-invasive system performing asymmetry measurements on a link basis and show that such a system can integrate into existing synchronization solutions.
{"title":"Compensation of asymmetrical latency for ethernet clock synchronization","authors":"Natasa Simanic, R. Exel, P. Loschmidt, Thomas Bigler, N. Kero","doi":"10.1109/ISPCS.2011.6070151","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070151","url":null,"abstract":"Clock synchronization has become an indispensable service in most distributed systems as it allows to sort events on a common time scale and coordinate collaborative actions.With the demand for even higher synchronization accuracy, new challenges and barriers have to be tackled to fulfill these requirements. One of them, the inevitable signal propagation time between the devices, is compensated in many state-of-the-art synchronization protocols by round-trip measurements, neglecting any form of delay asymmetry of the communication link. In this paper, we analyze the impact of asymmetry in networks based on the physical layer of copper-based Ethernet and compare different approaches on how to mitigate the impact of asymmetry. We propose a non-invasive system performing asymmetry measurements on a link basis and show that such a system can integrate into existing synchronization solutions.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127042129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-11-07DOI: 10.1109/ISPCS.2011.6070154
M. Laner, S. Caban, P. Svoboda, M. Rupp
Time synchronization is a vital requirement for various applications. Especially the synchronization of desktop computers to the Coordinated Universal Time (UTC) yields numerous use cases, such as distributed measurements. Several solutions address this need, at different levels of price and accuracy. In this work we evaluate on the achievable precision in time synchronization of a desktop PC, for example, assisted by a low-budget GPS receiver. This is achieved by a novel measurement setup, which is comparing the software synchronized internal clock of the PC to a rubidium frequency standard. Our results show, that the synchronization offsets of the software clocks of all tested PCs have positive mean (time lag) in the order of 10 µs. The respective standard deviation is typically an order of magnitude lower. Thereby the unknown interrupt latency is the limiting factor for the accuracy. With this work we show that today (2011) 10 µs of precision can be achieve at very low cost.
{"title":"Time synchronization performance of desktop computers","authors":"M. Laner, S. Caban, P. Svoboda, M. Rupp","doi":"10.1109/ISPCS.2011.6070154","DOIUrl":"https://doi.org/10.1109/ISPCS.2011.6070154","url":null,"abstract":"Time synchronization is a vital requirement for various applications. Especially the synchronization of desktop computers to the Coordinated Universal Time (UTC) yields numerous use cases, such as distributed measurements. Several solutions address this need, at different levels of price and accuracy. In this work we evaluate on the achievable precision in time synchronization of a desktop PC, for example, assisted by a low-budget GPS receiver. This is achieved by a novel measurement setup, which is comparing the software synchronized internal clock of the PC to a rubidium frequency standard. Our results show, that the synchronization offsets of the software clocks of all tested PCs have positive mean (time lag) in the order of 10 µs. The respective standard deviation is typically an order of magnitude lower. Thereby the unknown interrupt latency is the limiting factor for the accuracy. With this work we show that today (2011) 10 µs of precision can be achieve at very low cost.","PeriodicalId":416451,"journal":{"name":"2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123883980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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