| 61. |
- Ashjaei, Mohammad, et al.
(author)
-
Response time analysis of multi-hop HaRTES Ethernet Switch networks
- 2014
-
In: IEEE Int. Workshop Factory Commun. Syst. Proc. WFCS. - 9781479932351
-
Conference paper (peer-reviewed)abstract
- In this paper we focus on micro-segmented switched-Ethernet networks with HaRTES switches. HaRTES switches provide synchronous and asynchronous real-time traffic scheduling, dynamic Quality-of-Service adaptation and transparent integration of real-time and non-real-time nodes. Herein we investigate the challenges of connecting multiple HaRTES switches in order to build multi-hop communication and we propose a method, named Distributed Global Scheduling, to handle the traffic forwarding in such an architecture while preserving the unique properties of the single HaRTES switch case. Moreover, we develop a response time analysis for the method. We also evaluate the level of pessimism embodied in the anal-ysis. Finally, we show the applicability of the proposed method in an industrial setting by applying it in an automotive case study.
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| 62. |
- Ashjaei, Mohammad, 1980-, et al.
(author)
-
Schedulability Analysis of Ethernet Audio Video Bridging Networks with Scheduled Traffic Support
- 2017
-
In: Real-time systems. - : Springer Science and Business Media LLC. - 0922-6443 .- 1573-1383. ; 53:4, s. 526-577
-
Journal article (peer-reviewed)abstract
- The IEEE Audio Video Bridging (AVB) technology is nowadays under consideration in several automation domains, such as, automotive, avionics, and industrial communications. AVB offers several benefits, such as open specifications, the existence of multiple providers of electronic components, and the real-time support, as AVB provides bounded latency to real-time traffic classes. In addition to the above mentioned properties, in the automotive domain, comparing with the existing in-vehicle networks, AVB offers significant advantages in terms of high bandwidth, significant reduction of cabling costs, thickness and weight, while meeting the challenging EMC/EMI requirements. Recently, an improvement of the AVB protocol, called the AVB ST, was proposed in the literature, which allows for supporting scheduled traffic, i.e., a class of time-sensitive traffic that requires time-driven transmission and low latency. In this paper, we present a schedulability analysis for the real-time traffic crossing through the AVB ST network. In addition, we formally prove that, if the bandwidth in the network is allocated according to the AVB standard, the schedulability test based on response time analysis will fail for most cases even if, in reality, these cases are schedulable. In order to provide guarantees based on analysis test a bandwidth over-reservation is required. In this paper, we propose a solution to obtain a minimized bandwidth over-reservation. To the best of our knowledge, this is the first attempt to formally spot the limitation and to propose a solution for overcoming it. The proposed analysis is applied to both the AVB standard and the AVB ST. The analysis results are compared with the results of several simulative assessments, obtained using OMNeT++, on both automotive and industrial case studies. The comparison between the results of the analysis and the simulation ones shows the effectiveness of the analysis proposed in this work.
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| 63. |
- Ashjaei, Mohammad, et al.
(author)
-
SEtSim : A modular simulation tool for switched Ethernet networks
- 2016
-
In: Journal of systems architecture. - : Elsevier BV. - 1383-7621 .- 1873-6165. ; 65, s. 1-14
-
Journal article (peer-reviewed)abstract
- Using high bandwidth network technologies in real-time applications, for example in automotive systems, is rapidly increasing. In this context, switched Ethernet-based protocols are becoming more popular due to their features such as providing a collision-free domain for transmission of messages. Moreover, switched Ethernet is a mature technology. Several protocols based on switched Ethernet have been proposed over the years, tuned for time critical applications. However, research for improving the features and performance of these protocols is still on-going. In order to evaluate the performance of early stage proposed protocols, the mathematical analysis and/or experiments are required. However, performing an experiment for complex network topologies with a large set of messages is not effortless. Therefore, using a simulation based approach for evaluating a protocol's performance and/or properties is highly useful. As a response to this we have developed a simulator, called SEtSim, for switched Ethernet networks. SEtSim is developed based on Simulink, and it currently supports different network topologies of the FIT-SE protocol as well as Ethernet AVB protocol. However, the kernel of SEtSim is designed such that it is possible to add and integrate other switched Ethernet-based protocols. In this paper, we describe the design of SEtSim and we show its scalability.
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| 64. |
- Ashjaei, Mohammad, et al.
(author)
-
SEtSim: A Modular Simulation Tool for Switched Ethernet Networks
- 2014
-
Reports (other academic/artistic)abstract
- Using high bandwidth network technologies in real-time applications, for example in automotive systems, is rapidly increasing. In this context, switched Ethernet-based protocols are becoming more popular due to their features such as providing a collision-free domain for transmission of messages. Moreover, switched Ethernet is a mature technology. Several protocols based on switched Ethernet have been proposed over the years, tuned for time critical applications. However, research for improving the features and performance of these protocols is still on-going. In order to evaluate the performance of early stage proposed protocols, the mathematical analysis and/or experiments are required. However, performing an experiment for complex network topologies with a large set of messages is not effortless. Therefore, using a simulation based approach for evaluating a protocol's performance and/or properties is highly useful. As a response to this we have, based on Simulink, developed a simulator, called SEtSim, for switched Ethernet networks. SEtSim currently supports different network topologies of the FTT-SE protocol, a master-slave protocol designed for standard Ethernet switches, as well as Ethernet AVB protocol. However, the kernel of SEtSim is designed such that it is possible to add and integrate other switched Ethernet-based protocols. In this paper, we describe the design of SEtSim and we show its scalability.
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| 65. |
- Ashjaei, Mohammad, et al.
(author)
-
Supporting Multi-Hop Communications with HaRTES Ethernet Switches
- 2013
-
Conference paper (peer-reviewed)abstract
- In this paper we identify the challenges of multi-hop communication when using a micro-segmented switched-Ethernet protocol with enhanced HaRTES switches. The HaRTES architecture has been explored in the scope of single-switch topology, and provides dynamic virtual channels that can be composed hierarchically and provide bounded latency together with temporal isolation. Herein we propose two different solutions regarding the traffic forwarding in multi-switch architectures, while maintaining the unique properties of the single HaRTES switch case. In the first approach, the traffic is buffered and scheduled sequentially in each hop. In the second solution the traffic is scheduled once and forwarded immediately through multiple switches without buffering. In this paper we present a brief comparison of both approaches and we report on the on-going work towards effective support to real-time communications in dynamic and complex Cyber-Physical Systems.
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| 66. |
- Ashjaei, Mohammad, et al.
(author)
-
The Design and Implementation of a Simulator for Switched Ethernet Networks
- 2012
-
In: 3rd International Workshop on Analysis Tools andMethodologies for Embeddedand Real-time Systems. ; , s. 57-62
-
Conference paper (peer-reviewed)abstract
- In the context of Switched Ethernet, the Flexible Time-Triggered Switched Ethernet protocol (FTT-SE) was proposed to overcome the limitations and related problems of using COTS switches in real-time networks, such as overflow of switch queues due to uncontrolled arrival of packets. Although the FTT-SE protocol has been validated by several experiments on real applications, evaluation of different architectures as well as evaluation of large scale networks is not straightforward. Therefore, a simulator to evaluate different network architectures based on the FTT-SE protocol is useful. In this paper we present such a simulator. We address the extended FTT-SE protocol using multiple switches and we present a modular simulator based on Simulink/Matlab to visualize message transmissions and to evaluate end-to-end delay bounds of messages.
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| 67. |
- Ashjaei, Mohammad, et al.
(author)
-
Worst-case delay analysis of master-slave switched ethernet networks
- 2012
-
In: Proceeings of the 2nd International Workshop on Worst-Case Traversal Time. - New York, NY, USA : ACM. - 9781450316866 ; , s. 15-21
-
Conference paper (peer-reviewed)abstract
- Switched Ethernet is increasingly used in real-time communication due to its intrinsic features such as micro segmentation and high throughput. However, COTS switches may impose long blocking times due to their FIFO queues and can also experience buffer overflow in outgoing queues due to uncontrolled packets arrival. The FTT-SE protocol uses a Master-Slave technique to overcome the COTS switch limitations in real-time applications. Recently, we extended the protocol for large scale networks and in this paper we present the worst-case delay analysis using the Network Calculus formalism for such a network. Moreover, we assess the end-to-end delay of traffic with simulation concluding that the obtained analytical results present a good match with the observed delays, providing uppers bounds that vary between 0% and 50% above the maximum measured values. © 2012 ACM.
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| 68. |
- Ashjaei, Seyed Mohammad Hossein, 1980-, et al.
(author)
-
Modeling and Timing Analysis of Vehicle Functions Distributed over Switched Ethernet
- 2017
-
In: IECON 2017 - 43RD ANNUAL CONFERENCE OF THE IEEE INDUSTRIAL ELECTRONICS SOCIETY. - 9781538611272 ; , s. 8419-8424
-
Conference paper (peer-reviewed)abstract
- This paper proposes an approach to model switched Ethernet communication within a model- and component-based software development framework for vehicular distributed embedded systems. The paper also presents a method to extract the network timing model from the systems that use switched Ethernet networks. In order to provide a proof of concept, an existing industrial component model and its tool suite, namely RCM and Rubus-ICE respectively, are extended by implementing the modeling technique, the timing model extraction method and response-time analysis of the Ethernet AVB protocol. The extensions to RCM are backward compatible with the modeling and end-to-end timing analysis of traditional in-vehicle networks and legacy (previously developed) vehicular distributed embedded systems. Furthermore, the paper discusses the implementation and test strategy used in this work. Finally, the usability of the modeling approach and implemented timing analysis is demonstrated by modeling and time analyzing a vehicular application case study with the extended component model and tool suite.
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| 69. |
- Bassi, Ezio, et al.
(author)
-
Powerline Communication in Electric Vehicles
- 2009
-
In: IEEE International Electric Machines and Drives Conference (IEMDC'09). - 9781424442522 ; , s. 1749-1753
-
Conference paper (peer-reviewed)abstract
- In full electric (EV) or hybrid electric (HEV) vehicles the onboard communication is a crucial issue, that can take advantage from a reliable and robust interaction among the embedded units (ECUs) providing among others the power and batteries management, services, accessories and supervision; an updated global view of the system under control (the car) can improve the quality of control, reliability, safety and comfort. Power Line Communication technology (PLC), that take advantage of the DC power line as a physical medium to exchange messages, according to standard protocols, is a candidate at substituting the actual wired solutions, by substantially reducing the cabling burden. The present paper aims at i) reviewing PLC technology for DC bus in the automotive sector; ii) defining the requirements of a reliable communication systems within a car environment, with special attention given to the data exchange needed by the more critical systems in EV and HEV, and namely the control of electrical actuators for traction; iii) describing a benchmark for testing the data transfer characteristics and performance, including details on proposed protocols and architectures and presenting experimental results on data channel characterization and transmission.
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| 70. |
- Becker, Matthias, 1986-, et al.
(author)
-
A Generic Framework Facilitating Early Analysis of Data Propagation Delays in Multi-Rate Systems
- 2017
-
In: The 23th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications RTCSA'17.
-
Conference paper (peer-reviewed)abstract
- A majority of multi-rate real-time systems are constrained by a multitude of timing requirements, in addition to the traditional deadlines on well-studied response times. This means, the timing predictability of these systems not only depends on the schedulability of certain task sets but also on the timely propagation of data through the chains of tasks from sensors to actuators. In the automotive industry, four different timing constraints corresponding to various data propagation delays are commonly specified on the systems. This paper identifies and addresses the source of pessimism as well as optimism in the calculations for one such delay, namely the reaction delay, in the state-of-the-art analysis that is already implemented in several industrial tools. Furthermore, a generic framework is proposed to compute all the four end-to-end data propagation delays, complying with the established delay semantics, in a scheduler and hardware-agnostic manner. This allows analysis of the system models already at early development phases, where limited system information is present. The paper further introduces mechanisms to generate job-level dependencies, a partial ordering of jobs, which need to be satisfied by any execution platform in order to meet the data propagation timing requirements. The job-level dependencies are first added to all task chains of the system and then reduced to its minimum required set such that the job order is not affected. Moreover, a necessary schedulability test is provided, allowing for varying the number of CPUs. The experimental evaluations demonstrate the tightness in the reaction delay with the proposed framework as compared to the existing state-of-the-art and practice solutions.
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