Pub Date : 2019-09-01DOI: 10.1109/ISPCS.2019.8886632
P. Jansweijer, H. Peek
High accuracy two-way time transfer systems that use single fiber as a medium, operated bidirectional at dual wavelength, suffer propagation delay asymmetry due to chromatic dispersion. Calibration is necessary for reaching sub-ns accuracies. We present a method to determine and monitor the optical wavelength dependent fiber delay coefficient (α) insitu using the high accuracy time-stamping capabilities of the time dissemination network itself, without the need for an additional fiber link.
{"title":"Insitu determination of the fiber delay coefficient in time-dissemination networks","authors":"P. Jansweijer, H. Peek","doi":"10.1109/ISPCS.2019.8886632","DOIUrl":"https://doi.org/10.1109/ISPCS.2019.8886632","url":null,"abstract":"High accuracy two-way time transfer systems that use single fiber as a medium, operated bidirectional at dual wavelength, suffer propagation delay asymmetry due to chromatic dispersion. Calibration is necessary for reaching sub-ns accuracies. We present a method to determine and monitor the optical wavelength dependent fiber delay coefficient (α) insitu using the high accuracy time-stamping capabilities of the time dissemination network itself, without the need for an additional fiber link.","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125461298","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 : 2019-09-01DOI: 10.1109/ispcs.2019.8886629
{"title":"[Copyright notice]","authors":"","doi":"10.1109/ispcs.2019.8886629","DOIUrl":"https://doi.org/10.1109/ispcs.2019.8886629","url":null,"abstract":"","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132203855","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 : 2019-09-01DOI: 10.1109/ISPCS.2019.8886645
Martin Langer, Thomas Behn, R. Bermbach
This paper presents a method to secure the time synchronization messages of various Network Time Protocol (NTP) services. It uses the Network Time Security protocol (NTS), which is now in a final, pre-RFC state, without the necessity of changes of their underlying implementations. A dedicated NTS service – the so-called NTS daemon (NTSd) – captures the standard NTP messages of the client and passes them on to an NTS server (tunneling). Supplied with the respective timestamps the secured message travels back via the NTS daemon to the NTP client, a procedure completely transparent to the NTP services. The presented research and the implementation of the method show advantages and limitations of the approach. Furthermore, it offers limited correction of NTS related time message asymmetries. Measurements provide an insight into the achievable accuracy and show the differences to NTP services with integrated NTS capability.
{"title":"Securing Unprotected NTP Implementations Using an NTS Daemon","authors":"Martin Langer, Thomas Behn, R. Bermbach","doi":"10.1109/ISPCS.2019.8886645","DOIUrl":"https://doi.org/10.1109/ISPCS.2019.8886645","url":null,"abstract":"This paper presents a method to secure the time synchronization messages of various Network Time Protocol (NTP) services. It uses the Network Time Security protocol (NTS), which is now in a final, pre-RFC state, without the necessity of changes of their underlying implementations. A dedicated NTS service – the so-called NTS daemon (NTSd) – captures the standard NTP messages of the client and passes them on to an NTS server (tunneling). Supplied with the respective timestamps the secured message travels back via the NTS daemon to the NTP client, a procedure completely transparent to the NTP services. The presented research and the implementation of the method show advantages and limitations of the approach. Furthermore, it offers limited correction of NTS related time message asymmetries. Measurements provide an insight into the achievable accuracy and show the differences to NTP services with integrated NTS capability.","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130016765","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 : 2019-09-01DOI: 10.1109/ispcs.2019.8886630
{"title":"ISPCS 2019 Author Index","authors":"","doi":"10.1109/ispcs.2019.8886630","DOIUrl":"https://doi.org/10.1109/ispcs.2019.8886630","url":null,"abstract":"","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133862471","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 : 2019-09-01DOI: 10.1109/ISPCS.2019.8886633
Martin Langer, K. Teichel, Kai Heine, D. Sibold, R. Bermbach
In this paper, we consider ways of using secondary “Watchdog” mechanisms to protect primary time synchronization protocols from single-source or single-channel errors. This approach is particularly interesting when the Watchdog mechanism has stronger cryptographic protection than the primary synchronization mechanism. We specifically discuss the case where the primary mechanism employs one-way communication and is secured with an authentication scheme based on delayed disclosure of cryptographic information. Further, we present results from experiments with an implementation combining such a primary mechanism with a secured two-way control mechanism, which lead us to overall recommend the approach.
{"title":"Guards and Watchdogs in One-Way Synchronization with Delay-Related Authentication Mechanisms","authors":"Martin Langer, K. Teichel, Kai Heine, D. Sibold, R. Bermbach","doi":"10.1109/ISPCS.2019.8886633","DOIUrl":"https://doi.org/10.1109/ISPCS.2019.8886633","url":null,"abstract":"In this paper, we consider ways of using secondary “Watchdog” mechanisms to protect primary time synchronization protocols from single-source or single-channel errors. This approach is particularly interesting when the Watchdog mechanism has stronger cryptographic protection than the primary synchronization mechanism. We specifically discuss the case where the primary mechanism employs one-way communication and is secured with an authentication scheme based on delayed disclosure of cryptographic information. Further, we present results from experiments with an implementation combining such a primary mechanism with a secured two-way control mechanism, which lead us to overall recommend the approach.","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133196737","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 : 2019-09-01DOI: 10.1109/ISPCS.2019.8886634
R. M. Kaminsky
This paper explores holdover in an IEEE 1588v2 application. Lab measurements were taken on a reference design configured as a telecom boundary clock (T-BC) comparing the short- and long-term holdover performance of the node when using a TCXO, OCXO, and age-compensated DOCXO, as its reference oscillator. Measurements were taken both with, and without the assistance of a physical layer clock. The results show that when a physical layer clock (e.g. SyncE) is provided, the node meets the ITU-T Recommendation (G.8273.2) [1] for short-term holdover. For this paper, long-term holdover (24-hour) performance is based on the end-to-end LTE-TDD small cell mobile network requirements. When a physical layer clock is provided, the long-term holdover performance is highly dependent on the average drift rate of the PTP clock at the time when this clock is lost and much less dependent on the stability of the local reference oscillator. However, for long-term holdover, when a physical layer clock is not provided, the type of reference oscillator used becomes extremely important and only by employing an age-compensated oscillator was the 24-hour phase error requirement successfully achieved.
{"title":"Test Results of IEEE 1588v2 Network Synchronization Holdover Performance using Various Types of Reference Oscillators","authors":"R. M. Kaminsky","doi":"10.1109/ISPCS.2019.8886634","DOIUrl":"https://doi.org/10.1109/ISPCS.2019.8886634","url":null,"abstract":"This paper explores holdover in an IEEE 1588v2 application. Lab measurements were taken on a reference design configured as a telecom boundary clock (T-BC) comparing the short- and long-term holdover performance of the node when using a TCXO, OCXO, and age-compensated DOCXO, as its reference oscillator. Measurements were taken both with, and without the assistance of a physical layer clock. The results show that when a physical layer clock (e.g. SyncE) is provided, the node meets the ITU-T Recommendation (G.8273.2) [1] for short-term holdover. For this paper, long-term holdover (24-hour) performance is based on the end-to-end LTE-TDD small cell mobile network requirements. When a physical layer clock is provided, the long-term holdover performance is highly dependent on the average drift rate of the PTP clock at the time when this clock is lost and much less dependent on the stability of the local reference oscillator. However, for long-term holdover, when a physical layer clock is not provided, the type of reference oscillator used becomes extremely important and only by employing an age-compensated oscillator was the 24-hour phase error requirement successfully achieved.","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122196484","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 : 2019-09-01DOI: 10.1109/ISPCS.2019.8886639
S. Sandha, Joseph Noor, F. Anwar, M. Srivastava
Achieving precise time synchronization across a collection of smartphones poses unique challenges due to their limited hardware support, exclusively wireless networking interface, and restricted timing stack control. Given the ubiquity and popularity of smartphones in modern distributed applications, clock discrepancies often lead to degraded application performance. In this paper, we present and evaluate alternative approaches to attain precise time synchronization by leveraging the various peripherals available on modern smartphone devices. Our evaluation across Android smartphones typically attains synchronization accuracy within (i) 200μs using audio, (ii) 3000μs using Bluetooth Low Energy, and (iii) 1000μs using Wi-Fi. Under certain conditions, we show that smartphones synchronized using one peripheral can accurately timestamp and generate synchronous events over other peripherals. The provided guide and accompanying open-source implementations offer developers a means to select the appropriate time synchronization technique when building distributed applications.
{"title":"Exploiting Smartphone Peripherals for Precise Time Synchronization","authors":"S. Sandha, Joseph Noor, F. Anwar, M. Srivastava","doi":"10.1109/ISPCS.2019.8886639","DOIUrl":"https://doi.org/10.1109/ISPCS.2019.8886639","url":null,"abstract":"Achieving precise time synchronization across a collection of smartphones poses unique challenges due to their limited hardware support, exclusively wireless networking interface, and restricted timing stack control. Given the ubiquity and popularity of smartphones in modern distributed applications, clock discrepancies often lead to degraded application performance. In this paper, we present and evaluate alternative approaches to attain precise time synchronization by leveraging the various peripherals available on modern smartphone devices. Our evaluation across Android smartphones typically attains synchronization accuracy within (i) 200μs using audio, (ii) 3000μs using Bluetooth Low Energy, and (iii) 1000μs using Wi-Fi. Under certain conditions, we show that smartphones synchronized using one peripheral can accurately timestamp and generate synchronous events over other peripherals. The provided guide and accompanying open-source implementations offer developers a means to select the appropriate time synchronization technique when building distributed applications.","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115616267","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 : 2019-09-01DOI: 10.1109/ISPCS.2019.8886638
D. Anand, C. Freiheit, M. Weiss, K. Shenoi, H. Ossareh
Accurate time is frequently cited as an enabling requirement for precisely coordinated control systems used in the electrical power system. Methods and technologies to evaluate the impact of impaired time accuracy on these control systems are frequently expensive to build and confined to a laboratory setting. Our focus in this paper is to develop a system to apply timing impairments to electrical sensors in the field. We expect that the value of such a system would be in elucidating potentially negative interactions between interconnected and interdependent measurement and control components as deployed. As such, this paper outlines the design of a new hardware-in-the-loop tool for applying timing impairments to sensors that require accurate time. In addition to the design of the tool, we discuss the challenges and one approach for implementing realistic impairment scenarios that may be comprised of stochastic variations, systematic offsets and accumulating errors.
{"title":"A timing impairment module for electrical synchrometrology","authors":"D. Anand, C. Freiheit, M. Weiss, K. Shenoi, H. Ossareh","doi":"10.1109/ISPCS.2019.8886638","DOIUrl":"https://doi.org/10.1109/ISPCS.2019.8886638","url":null,"abstract":"Accurate time is frequently cited as an enabling requirement for precisely coordinated control systems used in the electrical power system. Methods and technologies to evaluate the impact of impaired time accuracy on these control systems are frequently expensive to build and confined to a laboratory setting. Our focus in this paper is to develop a system to apply timing impairments to electrical sensors in the field. We expect that the value of such a system would be in elucidating potentially negative interactions between interconnected and interdependent measurement and control components as deployed. As such, this paper outlines the design of a new hardware-in-the-loop tool for applying timing impairments to sensors that require accurate time. In addition to the design of the tool, we discuss the challenges and one approach for implementing realistic impairment scenarios that may be comprised of stochastic variations, systematic offsets and accumulating errors.","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122683922","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 : 2019-09-01DOI: 10.1109/ISPCS.2019.8886643
Prasanth Kemparaj, S. S. Kumar
IEEE 1588-2008 protocol is used to provide time and frequency synchronization in network. As time and frequency distribution protocols are becoming increasingly common and widely deployed across the networks, concern about their exposure to security threats and vulnerabilities are increasing. One can use external security mechanisms like IPSEC or MACSEC to safe-guard network from various attacks and not specific to timing protocols. To address security related threats IEEE 1588-2019 draft standard D1.5 defines a “PTP integrated security(PTPIS)” mechanism which is complex and not completely integrated because key management mechanism is left open. A simple and “ Fully PTP Integrated Security(FPTPIS)” mechanism which includes key management is proposed by introducing a new general message and TLV. This paper describes how new general message and TLV enables “fully PTPIS” and thus solving the security requirements of the RFC7384.
{"title":"Secure precision time protocol in packet switched networks","authors":"Prasanth Kemparaj, S. S. Kumar","doi":"10.1109/ISPCS.2019.8886643","DOIUrl":"https://doi.org/10.1109/ISPCS.2019.8886643","url":null,"abstract":"IEEE 1588-2008 protocol is used to provide time and frequency synchronization in network. As time and frequency distribution protocols are becoming increasingly common and widely deployed across the networks, concern about their exposure to security threats and vulnerabilities are increasing. One can use external security mechanisms like IPSEC or MACSEC to safe-guard network from various attacks and not specific to timing protocols. To address security related threats IEEE 1588-2019 draft standard D1.5 defines a “PTP integrated security(PTPIS)” mechanism which is complex and not completely integrated because key management mechanism is left open. A simple and “ Fully PTP Integrated Security(FPTPIS)” mechanism which includes key management is proposed by introducing a new general message and TLV. This paper describes how new general message and TLV enables “fully PTPIS” and thus solving the security requirements of the RFC7384.","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"6 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133019808","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 : 2019-09-01DOI: 10.1109/ISPCS.2019.8886640
Brandon Smith, Bob Noseworthy, R. Bartos
Monitoring mechanisms are an essential component of timing security. Existing mechanisms allow for a comprehensive view of the distribution of time throughout a network, but they do not scale to large networks. We propose a new method called aggregated reverse time transfer (ARTT), which builds upon the reverse time transfer mechanism and the IEEE 1588 monitoring TLV to limit message complexity and redundant information. We demonstrate that these two mechanisms can be used in concert to report the timing error of a network more efficiently without a significant loss in accuracy.
{"title":"ARTT: A Scalable Approach for Monitoring the Quality of Time in Distributed Systems","authors":"Brandon Smith, Bob Noseworthy, R. Bartos","doi":"10.1109/ISPCS.2019.8886640","DOIUrl":"https://doi.org/10.1109/ISPCS.2019.8886640","url":null,"abstract":"Monitoring mechanisms are an essential component of timing security. Existing mechanisms allow for a comprehensive view of the distribution of time throughout a network, but they do not scale to large networks. We propose a new method called aggregated reverse time transfer (ARTT), which builds upon the reverse time transfer mechanism and the IEEE 1588 monitoring TLV to limit message complexity and redundant information. We demonstrate that these two mechanisms can be used in concert to report the timing error of a network more efficiently without a significant loss in accuracy.","PeriodicalId":193584,"journal":{"name":"2019 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control, and Communication (ISPCS)","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133157771","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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