Heterogeneous multicore platforms have become an attractive choice to deploy mixed criticality systems demanding diverse computational requirements. One of the major challenges is to efficiently harness the computational power of these multicore platforms while deploying mixed criticality applications. The problem is acerbated with an additional demand of energy efficiency. It is particularly relevant for the battery powered embedded systems. We propose a partitioning algorithm for unrelated heterogeneous multicore platforms to map mixed criticality applications that ensures the timeliness property and reduces the energy consumption.
{"title":"Energy-Aware Task Allocation onto Unrelated Heterogeneous Multicore Platform for Mixed Criticality Systems","authors":"Muhammad Ali Awan, D. Masson, E. Tovar","doi":"10.1109/RTSS.2015.46","DOIUrl":"https://doi.org/10.1109/RTSS.2015.46","url":null,"abstract":"Heterogeneous multicore platforms have become an attractive choice to deploy mixed criticality systems demanding diverse computational requirements. One of the major challenges is to efficiently harness the computational power of these multicore platforms while deploying mixed criticality applications. The problem is acerbated with an additional demand of energy efficiency. It is particularly relevant for the battery powered embedded systems. We propose a partitioning algorithm for unrelated heterogeneous multicore platforms to map mixed criticality applications that ensures the timeliness property and reduces the energy consumption.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129469061","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}
Multi-level inclusive caches are often used in multi-core processors to simplify the design of cache coherence protocol. However, the use of such cache hierarchies poses great challenges to tight worst-case execution time (WCET) estimation due to the possible invalidation behavior. Traditionally, multi-level inclusive caches are analyzed in a level-by-level manner, and at each level three analyses (i.e. must, may, and persistence) are performed separately. At a particular level, conservative decisions need to be made when the behaviors of other levels are not available, which hurts analysis precision. In this paper, we propose an approach which analyzes a multi-level inclusive cache by integrating the three analyses for all levels together. The approach is based on the abstract interpretation of a concrete operational semantics defined for multi-level inclusive caches. We evaluate the proposed approach and also compare it with two state-of-the-art approaches. From the experimental results, we can observe the proposed approach can significantly improve the analysis precision under relatively small cache size configurations.
{"title":"Precise Multi-level Inclusive Cache Analysis for WCET Estimation","authors":"Zhenkai Zhang, X. Koutsoukos","doi":"10.1109/RTSS.2015.40","DOIUrl":"https://doi.org/10.1109/RTSS.2015.40","url":null,"abstract":"Multi-level inclusive caches are often used in multi-core processors to simplify the design of cache coherence protocol. However, the use of such cache hierarchies poses great challenges to tight worst-case execution time (WCET) estimation due to the possible invalidation behavior. Traditionally, multi-level inclusive caches are analyzed in a level-by-level manner, and at each level three analyses (i.e. must, may, and persistence) are performed separately. At a particular level, conservative decisions need to be made when the behaviors of other levels are not available, which hurts analysis precision. In this paper, we propose an approach which analyzes a multi-level inclusive cache by integrating the three analyses for all levels together. The approach is based on the abstract interpretation of a concrete operational semantics defined for multi-level inclusive caches. We evaluate the proposed approach and also compare it with two state-of-the-art approaches. From the experimental results, we can observe the proposed approach can significantly improve the analysis precision under relatively small cache size configurations.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124054342","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}
A method to bound the Failures In Time (FIT) rate of a CAN-based real-time system, i.e., the expected number of failures in one billion operating hours, is proposed. The method leverages an analysis, derived in the paper, of the probability of a correct and timely message transmission despite host and network failures due to electromagnetic interference (EMI). For a given workload, the derived FIT rate can be used to find an optimal replication factor, which is demonstrated with a case study based on a message set taken from a simple mobile robot.
提出了一种约束基于can的实时系统的FIT (failure In Time)率的方法，即十亿运行小时内的预期故障数。该方法利用了文中导出的一种分析方法，即在主机和网络由于电磁干扰(EMI)而发生故障的情况下，正确及时地传输消息的概率。对于给定的工作负载，可以使用导出的FIT率来查找最佳复制因子，通过基于从简单移动机器人获取的消息集的案例研究来演示这一点。
{"title":"When Is CAN the Weakest Link? A Bound on Failures-in-Time in CAN-Based Real-Time Systems","authors":"A. Gujarati, Björn B. Brandenburg","doi":"10.1109/RTSS.2015.31","DOIUrl":"https://doi.org/10.1109/RTSS.2015.31","url":null,"abstract":"A method to bound the Failures In Time (FIT) rate of a CAN-based real-time system, i.e., the expected number of failures in one billion operating hours, is proposed. The method leverages an analysis, derived in the paper, of the probability of a correct and timely message transmission despite host and network failures due to electromagnetic interference (EMI). For a given workload, the derived FIT rate can be used to find an optimal replication factor, which is demonstrated with a case study based on a message set taken from a simple mobile robot.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":"146 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116909164","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}
Y. Pant, Houssam Abbas, K. Mohta, Truong X. Nghiem, Joseph Devietti, R. Mangharam
Control software of autonomous robots has stringent real-time requirements that must be met to achieve the control objectives. One source of variability in the performance of a control system is the execution time and accuracy of the state estimator that provides the controller with state information. This estimator is typically perception-based (e.g., Computer Vision-based) and is computationally expensive. When the computational resources of the hardware platform become overloaded, the estimation delay can compromise control performance and even stability. In this paper, we define a framework for co-designing anytime estimation and control algorithms, in a manner that accounts for implementation issues like delays and inaccuracies. We construct an anytime perception-based estimator from standard off-the-shelf Computer Vision algorithms, and show how to obtain a trade-off curve for its delay vs estimate error behaviour. We use this anytime estimator in a controller that can use this trade-off curve at runtime to achieve its control objectives at a reduced energy cost. When the estimation delay is too large for correct operation, we provide an optimal manner in which the controller can use this curve to reduce estimation delay at the cost of higher inaccuracy, all the while guaranteeing basic objectives are met. We illustrate our approach on an autonomous hexrotor and demonstrate its advantage over a system that does not exploit co-design.
{"title":"Co-design of Anytime Computation and Robust Control","authors":"Y. Pant, Houssam Abbas, K. Mohta, Truong X. Nghiem, Joseph Devietti, R. Mangharam","doi":"10.1109/RTSS.2015.12","DOIUrl":"https://doi.org/10.1109/RTSS.2015.12","url":null,"abstract":"Control software of autonomous robots has stringent real-time requirements that must be met to achieve the control objectives. One source of variability in the performance of a control system is the execution time and accuracy of the state estimator that provides the controller with state information. This estimator is typically perception-based (e.g., Computer Vision-based) and is computationally expensive. When the computational resources of the hardware platform become overloaded, the estimation delay can compromise control performance and even stability. In this paper, we define a framework for co-designing anytime estimation and control algorithms, in a manner that accounts for implementation issues like delays and inaccuracies. We construct an anytime perception-based estimator from standard off-the-shelf Computer Vision algorithms, and show how to obtain a trade-off curve for its delay vs estimate error behaviour. We use this anytime estimator in a controller that can use this trade-off curve at runtime to achieve its control objectives at a reduced energy cost. When the estimation delay is too large for correct operation, we provide an optimal manner in which the controller can use this curve to reduce estimation delay at the cost of higher inaccuracy, all the while guaranteeing basic objectives are met. We illustrate our approach on an autonomous hexrotor and demonstrate its advantage over a system that does not exploit co-design.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129821995","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}
Nan Guan, Mengying Zhao, C. Xue, Yongpan Liu, W. Yi
This paper studies the performance analysis problem of energy-harvesting real-time network systems in the Real-Time Calculus (RTC) framework. The behavior of an energy-harvesting node turns out to be a generalization of two known components in RTC: it behaves like an AND connector if the capacitor used to temporally store surplus energy has unlimited capacity and there is no energy loss, while it behaves like a greedy processing component (GPC) if the size of the capacitor is zero and thus surplus energy is lost or passed to other nodes immediately. In this paper, methods are developed to analyze the worst-case performance, in terms of delay and backlog, of energy-harvesting nodes as well as compute upper/lower bounds of their data and energy outputs. Moreover, with the proposed analysis methods, we disclose some interesting properties of the worst-case behaviors of energy-harvesting systems, which provide useful information to guide system design. Experiments are conducted to evaluate our theoretical contributions and also confirm that the disclosed properties are not just the result of our analysis, but indeed hold in realistic system behaviors.
{"title":"Modular Performance Analysis of Energy-Harvesting Real-Time Networked Systems","authors":"Nan Guan, Mengying Zhao, C. Xue, Yongpan Liu, W. Yi","doi":"10.1109/RTSS.2015.14","DOIUrl":"https://doi.org/10.1109/RTSS.2015.14","url":null,"abstract":"This paper studies the performance analysis problem of energy-harvesting real-time network systems in the Real-Time Calculus (RTC) framework. The behavior of an energy-harvesting node turns out to be a generalization of two known components in RTC: it behaves like an AND connector if the capacitor used to temporally store surplus energy has unlimited capacity and there is no energy loss, while it behaves like a greedy processing component (GPC) if the size of the capacitor is zero and thus surplus energy is lost or passed to other nodes immediately. In this paper, methods are developed to analyze the worst-case performance, in terms of delay and backlog, of energy-harvesting nodes as well as compute upper/lower bounds of their data and energy outputs. Moreover, with the proposed analysis methods, we disclose some interesting properties of the worst-case behaviors of energy-harvesting systems, which provide useful information to guide system design. Experiments are conducted to evaluate our theoretical contributions and also confirm that the disclosed properties are not just the result of our analysis, but indeed hold in realistic system behaviors.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130606660","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}
Semi-partitioned scheduling is a resource efficient scheduling approach compared to the conventional multiprocessor scheduling approaches in terms of system utilization and migration overhead. Semi-partitioned scheduling can better utilize processor bandwidth compared to the partitioned scheduling while introducing less overhead compared to the global scheduling. Various techniques have been proposed to schedule tasks in a semi-partitioned environment, however, they have used blocking-agnostic allocation mechanisms in presence of resource sharing protocols. Since, the allocation mechanism can highly affect the system schedulability, in this paper we provide a blocking-aware allocation mechanism for semi-partitioned scheduling framework under a suspension-based resource sharing protocol. We have applied new heuristics for sorting the tasks in the algorithm that shows improvements upon system schedulability. Finally, we present our preliminary results.
{"title":"Semi-partitioning under a Blocking-Aware Task Allocation","authors":"Sara Afshar, M. Behnam, T. Nolte","doi":"10.1109/RTSS.2015.48","DOIUrl":"https://doi.org/10.1109/RTSS.2015.48","url":null,"abstract":"Semi-partitioned scheduling is a resource efficient scheduling approach compared to the conventional multiprocessor scheduling approaches in terms of system utilization and migration overhead. Semi-partitioned scheduling can better utilize processor bandwidth compared to the partitioned scheduling while introducing less overhead compared to the global scheduling. Various techniques have been proposed to schedule tasks in a semi-partitioned environment, however, they have used blocking-agnostic allocation mechanisms in presence of resource sharing protocols. Since, the allocation mechanism can highly affect the system schedulability, in this paper we provide a blocking-aware allocation mechanism for semi-partitioned scheduling framework under a suspension-based resource sharing protocol. We have applied new heuristics for sorting the tasks in the algorithm that shows improvements upon system schedulability. Finally, we present our preliminary results.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125024131","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}
Hyosu Kim, Sang Jeong Lee, Wookhyun Han, Daehyeok Kim, I. Shin
A variety of advantages from sounds such as measurement and accessibility introduces a new opportunity for mobile applications to offer broad types of interesting, valuable functionalities, supporting a richer user experience. However, in spite of the growing interests on mobile sound applications, few or no works have been done in focusing on managing an audio device effectively. More specifically, their low level of real-time capability for audio resources makes it challenging to satisfy tight timing requirements of mobile sound applications, e.g., a high sensing rate of acoustic sensing applications. To address this problem, this work presents the SounDroid framework, an audio device management framework for real-time audio requests from mobile sound applications. The design of SounDroid is based on the requirement analysis of audio requests as well as an understanding of the audio playback procedure including the audio request scheduling and dispatching on Android. It then incorporates both real-time audio request scheduling algorithms, called EDF-V and AFDS, and dispatching optimization techniques into mobile platforms, and thus improves the quality-of-service of mobile sound applications. Our experimental results with the prototype implementation of SounDroid demonstrate that it is able to enhance scheduling performance for audio requests, compared to traditional mechanisms (by up to 40% of improvement), while allowing deterministic dispatching latency.
{"title":"SounDroid: Supporting Real-Time Sound Applications on Commodity Mobile Devices","authors":"Hyosu Kim, Sang Jeong Lee, Wookhyun Han, Daehyeok Kim, I. Shin","doi":"10.1109/RTSS.2015.34","DOIUrl":"https://doi.org/10.1109/RTSS.2015.34","url":null,"abstract":"A variety of advantages from sounds such as measurement and accessibility introduces a new opportunity for mobile applications to offer broad types of interesting, valuable functionalities, supporting a richer user experience. However, in spite of the growing interests on mobile sound applications, few or no works have been done in focusing on managing an audio device effectively. More specifically, their low level of real-time capability for audio resources makes it challenging to satisfy tight timing requirements of mobile sound applications, e.g., a high sensing rate of acoustic sensing applications. To address this problem, this work presents the SounDroid framework, an audio device management framework for real-time audio requests from mobile sound applications. The design of SounDroid is based on the requirement analysis of audio requests as well as an understanding of the audio playback procedure including the audio request scheduling and dispatching on Android. It then incorporates both real-time audio request scheduling algorithms, called EDF-V and AFDS, and dispatching optimization techniques into mobile platforms, and thus improves the quality-of-service of mobile sound applications. Our experimental results with the prototype implementation of SounDroid demonstrate that it is able to enhance scheduling performance for audio requests, compared to traditional mechanisms (by up to 40% of improvement), while allowing deterministic dispatching latency.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127798713","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}
On uniprocessors, a failure of the single core means unavoidable system failure. However, on multicores, when a core fails, it is conceivable that the computation could continue on remaining cores in a degraded system mode indefinitely, until orderly shutdown and servicing can take place. This would be very desirable for critical applications but, apart from hardware and software support, it would require (i) a scheduling approach designed for providing such resilience and (ii) accompanying schedulability analysis, that derives offline the guarantees about the system meeting its deadlines at run-time, even if one core fails.
{"title":"Towards Realistic Core-Failure-Resilient Scheduling and Analysis","authors":"Borislav Nikolic, K. Bletsas","doi":"10.1109/RTSS.2015.47","DOIUrl":"https://doi.org/10.1109/RTSS.2015.47","url":null,"abstract":"On uniprocessors, a failure of the single core means unavoidable system failure. However, on multicores, when a core fails, it is conceivable that the computation could continue on remaining cores in a degraded system mode indefinitely, until orderly shutdown and servicing can take place. This would be very desirable for critical applications but, apart from hardware and software support, it would require (i) a scheduling approach designed for providing such resilience and (ii) accompanying schedulability analysis, that derives offline the guarantees about the system meeting its deadlines at run-time, even if one core fails.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124461960","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}
Marco Ziccardi, E. Mezzetti, T. Vardanega, J. Abella, F. Cazorla
Measurement-based probabilistic timing analysis (MBPTA) computes trustworthy upper bounds to the execution time of software programs. MBPTA has the connotation, typical of measurement-based techniques, that the bounds computed with it only relate to what is observed in actual program traversals, which may not include the effective worst-case phenomena. To overcome this limitation, we propose Extended Path Coverage (EPC), a novel technique that allows extending the representativeness of the bounds computed by MBPTA. We make the observation data probabilistically path-independent by modifying the probability distribution of the observed timing behaviour so as to negatively compensate for any benefits that a basic block may draw from a path leading to it. This enables the derivation of trustworthy upper bounds to the probabilistic execution time of all paths in the program, even when the user-provided input vectors do not exercise the worst-case path. Our results confirm that using MBPTA with EPC produces fully trustworthy upper bounds with competitively small overestimation in comparison to state-of-the-art MBPTA techniques.
{"title":"EPC: Extended Path Coverage for Measurement-Based Probabilistic Timing Analysis","authors":"Marco Ziccardi, E. Mezzetti, T. Vardanega, J. Abella, F. Cazorla","doi":"10.1109/RTSS.2015.39","DOIUrl":"https://doi.org/10.1109/RTSS.2015.39","url":null,"abstract":"Measurement-based probabilistic timing analysis (MBPTA) computes trustworthy upper bounds to the execution time of software programs. MBPTA has the connotation, typical of measurement-based techniques, that the bounds computed with it only relate to what is observed in actual program traversals, which may not include the effective worst-case phenomena. To overcome this limitation, we propose Extended Path Coverage (EPC), a novel technique that allows extending the representativeness of the bounds computed by MBPTA. We make the observation data probabilistically path-independent by modifying the probability distribution of the observed timing behaviour so as to negatively compensate for any benefits that a basic block may draw from a path leading to it. This enables the derivation of trustworthy upper bounds to the probabilistic execution time of all paths in the program, even when the user-provided input vectors do not exercise the worst-case path. Our results confirm that using MBPTA with EPC produces fully trustworthy upper bounds with competitively small overestimation in comparison to state-of-the-art MBPTA techniques.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122171479","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}
F. Terraneo, A. Leva, Silvano Seva, M. Maggio, A. Papadopoulos
Clock synchronization is a necessary component in modern distributed systems, especially Wireless Sensor Networks (WSNs). Despite the great effort and the numerous improvements, the existing synchronization schemes do not yet address the cancellation of propagation delays. Up to a few years ago, this was not perceived as a problem, because the time-stamping precision was a more limiting factor for the accuracy achievable with a synchronization scheme. However, the recent introduction of efficient flooding schemes based on constructive interference has greatly improved the achievable accuracy, to the point where propagation delays can effectively become the main source of error. In this paper, we propose a method to estimate and compensate for the network propagation delays. Our proposal does not require to maintain a spanning tree of the network, and exploits constructive interference even to transmit packets whose content are slightly different. To show the validity of the approach, we implemented the propagation delay estimator on top of the FLOPSYNC-2 synchronization scheme. Experimental results prove the feasibility of measuring propagation delays using off-the-shelf microcontrollers and radio transceivers, and show how the proposed solution allows to achieve sub-microsecond clock synchronization even for networks where propagation delays are significant.
{"title":"Reverse Flooding: Exploiting Radio Interference for Efficient Propagation Delay Compensation in WSN Clock Synchronization","authors":"F. Terraneo, A. Leva, Silvano Seva, M. Maggio, A. Papadopoulos","doi":"10.1109/RTSS.2015.24","DOIUrl":"https://doi.org/10.1109/RTSS.2015.24","url":null,"abstract":"Clock synchronization is a necessary component in modern distributed systems, especially Wireless Sensor Networks (WSNs). Despite the great effort and the numerous improvements, the existing synchronization schemes do not yet address the cancellation of propagation delays. Up to a few years ago, this was not perceived as a problem, because the time-stamping precision was a more limiting factor for the accuracy achievable with a synchronization scheme. However, the recent introduction of efficient flooding schemes based on constructive interference has greatly improved the achievable accuracy, to the point where propagation delays can effectively become the main source of error. In this paper, we propose a method to estimate and compensate for the network propagation delays. Our proposal does not require to maintain a spanning tree of the network, and exploits constructive interference even to transmit packets whose content are slightly different. To show the validity of the approach, we implemented the propagation delay estimator on top of the FLOPSYNC-2 synchronization scheme. Experimental results prove the feasibility of measuring propagation delays using off-the-shelf microcontrollers and radio transceivers, and show how the proposed solution allows to achieve sub-microsecond clock synchronization even for networks where propagation delays are significant.","PeriodicalId":239882,"journal":{"name":"2015 IEEE Real-Time Systems Symposium","volume":" 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113947224","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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