| 1. |
- Aglianò, Simone, et al.
(författare)
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Resource Management and Control in Virtualized SDN Networks
- 2018
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Ingår i: CSI International Symposium on Real-Time and Embedded Systems and Technologies REST'18. - 9781538614754 ; , s. 47-53
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Konferensbidrag (refereegranskat)abstract
- Software defined networking and network virtual-ization are widely considered promising techniques for reducing the complexity of network management in many contexts that require high Quality of Service (QoS) and the support for heterogeneous architectures. In this paper we address a network architecture, here called a virtualized SDN network, that combines the benefits of SDN and virtualization. To cope with the demand for efficiently sharing a platform among several services, here a resource management mechanism to reserve and control network resources among various services in the virtualized SDN networks is proposed. The mechanism is implemented on an SDN controller and a set of experiments show the effectiveness of the proposed approach.
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| 2. |
- Alderisi, Giuliana, et al.
(författare)
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Probabilistic Scheduling and Adaptive Relaying for WirelessHART Networks
- 2015
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Ingår i: 20th IEEE International Conference on Emerging Technologies and Factory Automation ETFA'15. - 9781467379304
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Konferensbidrag (refereegranskat)abstract
- This paper deals with a way to probabilistically guarantee reliable packet delivery in WirelessHART based networks suitable for industrial control systems. We propose a new scheduling scheme, called Iterative Probabilistic Scheduling with Adaptive Relaying (IPS-AR), which consists of a static part (IPS) and a dynamic part (AR). IPS takes into account the channel characteristics and exploits relaying to achieve a minimum reliability threshold as requested by the supported industrial application. In the AR part, each relay node decides the packet to be sent based on online assessment of both the number of consecutive errors experienced by previous packets belonging to the same flow, as well as the number of copies of the packet currently available at the other relay nodes. This enables IPS-AR to achieve the desired reliability level while using the available re-sources in terms of time and bandwidth more efficiently.
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| 3. |
- Ashjaei, Mohammad, 1980-, et al.
(författare)
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Schedulability Analysis of Ethernet Audio Video Bridging Networks with Scheduled Traffic Support
- 2017
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Ingår i: Real-time systems. - : Springer Science and Business Media LLC. - 0922-6443 .- 1573-1383. ; 53:4, s. 526-577
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Girs, Svetlana
(författare)
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Cooperative Communication for Increased Reliability in Industrial Wireless Networks
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introducing wireless networks into distributed industrial systems may enable new or improved application areas and also great cost reductions due to lower complexity of installation and maintenance, compared to existing wired solutions. However, signals travelling through wireless channels are affected by pathloss, fading and shadowing, and, as a result, packet errors are both time-varying and more frequent than in e.g., existing wired fieldbuses. Packet errors or delays occurring in industrial systems can, in critical situations, lead to damage of expensive equipment or even danger to human life. Thus, wireless networks can be accepted for use in industrial networks only when sufficient levels of reliability and timeliness can be guaranteed.Relaying is a technique that has the potential to increase reliability with maintained delay. Having different geographical locations, and thus different wireless channel qualities, some nodes may overhear transmitted packets even in cases when the intended receiver did not, and then cooperate by relaying these packets to their final destination.This thesis deals with design of relaying strategies aiming to increase reliability in deadline-constrained industrial applications using wireless networks. The influence of several different parameters, such as positions of relay nodes, number of erroneous packets at the relay node and at the destination respectively, as well as the number of available time slots before the deadline, are evaluated to determine the best acting strategy for each relay node. Moreover, it is shown that when a specific relay node has the opportunity to aid more than one source node, performance can be improved even further if the relay node combines several packets, using Luby coding or packet aggregation, and instead relays such combined packets. Given the methods proposed in this thesis, the reliability in industrial wireless networks can be enhanced considerably, without increasing the delay, such that message deadlines still are kept.
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| 5. |
- Kaczynski, Giordano A., et al.
(författare)
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Deriving Exact Stochastic Response Times of Periodic Tasks in Hybrid Priority-driven Soft Real-time Systems
- 2007
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Ingår i: Proceedings of 12th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA'07), Patras, Greece. - 9781424408269 ; , s. 101-110
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Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to allow for hybrid task sets in the context of stochastic real-time analysis. The paper goes beyond previous work by allowing for the presence of aperiodic tasks in the system. Instead of representing a task with a fixed activation period and a Worst-Case Execution Time (WCET), here a task is characterized by an Arrival Profile (AP) and an Execution Time Profile (ETP), both given by random variables with known distributions. Any number of aperiodic tasks, with arbitrary arrival and execution time profiles, can be dealt with. To cope with the unbounded interference introduced by aperiodic tasks in the system, sporadic and aperiodic tasks are encapsulated within servers. The paper presents the calculus for obtaining the exact ETP of servers, which allows us to derive exact response time distributions of periodic tasks. Also, an example is used to show the potential and validity of the proposed approach.
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| 6. |
- Kaczynski, Giordano A., et al.
(författare)
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Towards stochastic response-time of hierarchically scheduled real-time tasks
- 2006
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Ingår i: IEEE Symposium on Emerging Technologies and Factory Automation, ETFA. - 1424406811 ; , s. 453-456
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Konferensbidrag (refereegranskat)abstract
- The growing need for providing real-time system designers with less pessimistic results than the ones given by traditional worst-case analysis motivates several recent works on stochastic analysis methods. This paper deals with the calculation of stochastic Response Time Profiles of tasks that are hierarchically scheduled using server-based techniques in a stochastic analysis framework. Depending on how tasks are scheduled within the server, differences in temporal performance are expected. In the paper, initial results on calculating the Response Time Profiles for these server-scheduled tasks are outlined.
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