| 1. |
- Almeida, Luis, et al.
(författare)
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Managing end-to-end resource reservations
- 2014
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Ingår i: 7th International Workshop on Compositional Theory and Technology for Real-Time Embedded Systems CRTS'14.
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Konferensbidrag (refereegranskat)
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| 2. |
- Ashjaei, Mohammad, et al.
(författare)
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A Compact Approach to Clustered Master-Slave Ethernet Networks
- 2012
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Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS. - 9781467315739 ; , s. 157-160
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Konferensbidrag (refereegranskat)abstract
- Ethernet switches are increasingly used in real-time distributed systems as a technical solution to guarantee the timeliness in communications. However, there are still limitations related to real-time behavior caused by the limited number of priority levels and the possibility of memory overruns with consequent message losses. These limitations can be eliminated using a master/slave technique such as proposed by the FTT paradigm. This led to the FTT-SE protocol that schedules transmissions centrally in a master node. While this protocol has already been well studied and investigated for small networks with a single switch, its extension to larger networks is still an open issue. In this paper we propose a compact clustered solution to scale the FTT-SE protocol to networks of multiple switches by organizing the network in sub-networks composed of one master and one switch each and which can be connected directly, without bridges. This paper also shows how the timeliness of the traffic can still be enforced. The validation is currently on-going.
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| 3. |
- Ashjaei, Mohammad, et al.
(författare)
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Dynamic Reconfiguration in Multi-Hop Switched Ethernet Networks
- 2014
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Ingår i: ACM SIGBED Review. Special Issue on 6th Workshop on Adaptive and Reconfigurable Embedded Systems (APRES 2014). - : Association for Computing Machinery (ACM). - 1551-3688. ; 11:3, s. 62-65
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Tidskriftsartikel (refereegranskat)abstract
- The FTT-SE protocol provides adaptive real-time communication on Ethernet networks. To assure a continued real-time behavior, FTT-SE integrates admission control with a quality-of-service mechanism, which screen all adaptation and reconfiguration requests, accepting only those that do not compromise the system timeliness. The adaptability and reconfigurability have been deeply studied in the case of single switch FTT-SE architectures, whereas the extension of that for the multi-hop FTT-SE architecture was not yet investigated. Therefore, in this paper we study the challenges of enabling dynamic reconfiguration in multi-hop FTT-SE networks, we propose two methods (one centralized and one distributed) and we present a qualitative comparison between them.
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| 4. |
- Ashjaei, Mohammad, et al.
(författare)
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MTU Assignment in a Master-Slave Switched Ethernet Network
- 2013
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Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate the problem of selecting the Maximal Transmission Unit (MTU) size that maximizes the schedulability of real-time messages. We focus on a bandwidth-efficient master-slave switched Ethernet protocol, namely the FTT-SE protocol. We propose an algorithm to find the MTU for each message in order to maximize the schedulability of the messages. Moreover, we evaluate our proposed algorithm and we show that setting the MTU for messages using the algorithm increases the schedulability of messages compared with assigning the MTU to the maximum value that the protocol can support.
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| 5. |
- Ashjaei, Mohammad, et al.
(författare)
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Performance Analysis of Master-Slave Multi-Hop Switched Ethernet Networks
- 2013
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Ingår i: Proceedings of the 8th IEEE International Symposium on Industrial Embedded Systems, SIES 2013. - 9781479906581 ; , s. 280-289
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Konferensbidrag (refereegranskat)abstract
- There is an increasing trend towards using switched Ethernet in real-time distributed systems due to features like absence of collisions and high throughput. Nevertheless, a few problems persist, in particular related to priority inversion and limited length in queues. In this paper we focus on a protocol which uses a master-slave technique over standard switched Ethernet in order to overcome such problems, namely FTT-SE protocol. We present an improved response time analysis for such a network and we compare, analytically and with simulations, the results achieved with Network Calculus on a worst-case scenario. We show that our proposed response time analysis gives tighter bounds compared to Network Calculus. Moreover, we compare the performance of different solutions to scale the FTT-SE protocol with respect to the bandwidth utilization. Finally, we propose a new architecture to improve the average performance of master-slave switched Ethernet networks.
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| 6. |
- Ashjaei, Mohammad, et al.
(författare)
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Reduced Buffering Solution for Multi-Hop HaRTES Switched Ethernet Networks
- 2014
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Ingår i: The 20th IEEE International Conference on embedded and Real-Time Computing Systems and Applications RTCSA'14. - 9781479939534 ; , s. Article number 6910504-
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Konferensbidrag (refereegranskat)abstract
- In the context of switched Ethernet networks, multi-hop communication is essential as the networks in industrial applications comprise a high amount of nodes, that is far beyond the capability of a single switch. In this paper, we focus on multi-hop communication using HaRTES switches. The HaRTES switch is a modified Ethernet switch that provides real-time traffic scheduling, dynamic Quality-of-Service and temporal isolation between real-time and non-real-time traffic. Herein, we propose a method, called Reduced Buffering Scheme, to conduct the traffic through multiple HaRTES switches in a multi-hop HaRTES architecture. In order to enable the new scheduling method we propose to modify the HaRTES switch structure. Moreover, we develop a response time analysis for the new method. We also compare the proposed method with a method previously proposed, called Distributed Global Scheduling, based on their traffic response times. We show that, the new method forwards all types of traffic including the highest, the medium and the lowest priority, faster than the previous method in most of the cases. Furthermore, we show that the new method performs even better for larger networks compared with the previous one.
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| 7. |
- Ashjaei, Mohammad, et al.
(författare)
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Supporting Multi-Hop Communications with HaRTES Ethernet Switches
- 2013
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Konferensbidrag (refereegranskat)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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| 8. |
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| 9. |
- Hufnagel, Andreas, et al.
(författare)
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Long-term safety and efficacy of eslicarbazepine acetate as adjunctive therapy in the treatment of partial-onset seizures in adults with epilepsy: Results of a 1-year open-label extension study
- 2013
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Ingår i: Epilepsy Research. - : Elsevier BV. - 0920-1211 .- 1872-6844. ; 103, s. 262-269
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To evaluate the long-term safety, tolerability and efficacy of once-daily eslicarbazepine acetate (ESL) as adjunctive therapy in adults with partial-onset seizures. Methods: One-year open-label extension (OLE) study with ESL in patients who completed a randomised, double-blind placebo-controlled trial (study BIA-2093-302; Epilepsy Res. 89 (2010) 278-285). Starting dose was 800. mg once-daily, for 4 weeks; thereafter, dose could be individualised within the 400-1200. mg range. Doses of concomitant antiepileptic drugs were to be kept stable. Results: Overall, 325 patients were enrolled (intent-to-treat population); 223 (68.6%) patients completed 1-year of treatment. ESL median dose was 800. mg once-daily. Compared to the baseline period of the double-blind study completed prior to this OLE study, median seizure frequency decreased by 32% in weeks 1-4, and between 37% and 39% thereafter. The responder rate (seizure reduction ≥50%) was 37% during weeks 1-4 and thereafter ranged between 38% and 42% per 12-week interval. Proportion of seizure-free patients per 12-week interval ranged between 5% and 11%. Improvements from baseline in several Quality of Life in Epilepsy Inventory-31 (QOLIE-31) and Montgomery Asberg Depression Rating Scale (MADRS) scores were observed. Adverse events (AEs) were reported by 83% of patients. AEs occurring in ≥10% of patients were dizziness, headache and somnolence. AEs were usually of mild to moderate intensity. Conclusion: In this study, ESL demonstrated a sustained therapeutic effect and was well tolerated during 1-year add-on treatment of adults with partial-onset seizures. Additionally, significant improvements in quality of life domains and depressive symptoms were observed under long-term treatment with once-daily ESL. © 2012 Elsevier B.V.
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| 10. |
- Iqbal, Zahid, et al.
(författare)
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Implementing Hierarchical Scheduling on COTS Ethernet Switches Using a Master/Slave Approach
- 2012
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Ingår i: 7th IEEE International Symposium on Industrial Embedded Systems (SIES'12), Conference proceedings. - 9781467326834 - 9781467326858 ; , s. 76-84
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Konferensbidrag (refereegranskat)abstract
- Hierarchical scheduling is instrumental to efficiently deploy component-based designs and achieve composability. It allows partitioning resources into multiple levels, hiding the complexity within each partition behind its respective interface. In this paper we focus on the network resource, particularly on Ethernet using ordinary COTS switches, and we show how hierarchical scheduling can be efficiently deployed using a master/slave approach that enforces the temporal properties of the partitions. We use the FTT-SE protocol for being open source and a bandwidth efficient master/slave alternative currently available for real-time communication over Ethernet. We present a response-time analysis for the traffic submitted within each partition and we validate it using experimental results obtained from a prototype implementation. In particular, the results highlight the strong partitioning capabilities of our approach, with full temporal isolation across partitions in different branches of the hierarchy.
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