| 1. |
- Agelis, Sacki, et al.
(författare)
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Reconfigurable optical interconnection system supporting concurrent application-specific parallel computing
- 2005
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Ingår i: 17th Symposium on Computer Architecture and High Performance Computing. - Washington, DC, USA : IEEE Computer Society. - 076952446X ; , s. 44-51
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Konferensbidrag (refereegranskat)abstract
- Application specific architectures are highly desirable in embedded parallel computing systems at the same time as designers strive for using one embedded parallel computing platform for several applications. If this can be achieved, the cost can be decreased in comparison to using several different embedded parallel computing systems. This paper presents a novel approach of running several high-performance applications concurrently on one single parallel computing system. By using a reconfigurable backplane interconnection system, the applications can be run efficiently with high network flexibility since the interconnect network can be adapted to fit the application that is being processed for the moment. More precisely, this paper investigates how the space time adaptive processing (STAP) radar algorithm and the stripmap synthetic aperture radar (SAR) algorithm can be mapped on a multi-cluster processing system with a reconfigurable optical interconnection system realized by a micro-optical-electrical mechanical system (MOEMS) crossbars. The paper describes the reconfigurable platform, the two algorithms and how they individually can be mapped on the targeted multiprocessor system. It is also described how these two applications can be mapped simultaneously on the optical reconfigurable platform. Implications and requirements on communication bandwidth and processor performance in different critical points of the two applications are presented. The results of the analysis show that an implementation is feasible with today's MOEMS technology, and that the two applications can be successfully run in a time-sharing scheme, both at the processing side and at the access for interconnection bandwidth.
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| 2. |
- Bilstrup, Katrin, et al.
(författare)
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Report on the Collaboration between CVIS and CERES in the Project Vehicle Alert System (VAS)
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In March 2007, an agreement was made for interchange of experiences between CVIS and the Centre for Research on Embedded Systems (CERES) at Halmstad University in Sweden. The majority of the work relating to this collaboration has been conducted within the CERES project Vehicle Alert System (VAS), aiming to use vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications to provide different types of warning messages. The main focus of the VAS project is on communication and in particular the lower layers of the communication stack are investigated. VAS involves academic researchers from Halmstad University as well as researchers from Volvo Technology, SP Technical Research Institute of Sweden and the company Free2move. This report presents the results of the VAS project, its publications, and other issues of interest both to the CVIS consortium as well as a broader scope.
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| 3. |
- Bilstrup, Katrin, et al.
(författare)
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Vehicle Alert System
- 2007
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Ingår i: Proceedings of 14th world congress on intelligent transport system (ITS). ; , s. 2-9
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Konferensbidrag (refereegranskat)abstract
- The Vehicle Alert System (VAS) project focuses on cooperative alert services based on timely and reliable communication under the challenging circumstances pertaining to a highly mobile vehicular network. Through a cross-layer design, we gain the flexibility needed to adapt the system to the individual requirements of three chosen application scenarios that represent different situations where cooperation between vehicles can make a significant impact. The VAS project is a collaboration involving academic as well as industrial partners and the final stage of the project is a demonstrator that implements results from the research.
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| 4. |
- Böhm, Annette, 1975-, et al.
(författare)
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A Fibre-Optic AWG-Based Real-Time Network and Its Applicability to High-Performance Embedded Computing
- 2005
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Ingår i: 19th International Parallel and Distributed Processing Symposium. - Piscataway, N.J. : IEEE Press. - 0769523129 ; , s. 133b-133b
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Konferensbidrag (refereegranskat)abstract
- In this paper, an architecture and a Medium Access Control (MAC) protocol for a multi-wavelength optical communication network, applicable in short range communication systems like System Area Networks (SANs), are proposed. The main focus lies on guaranteed support for hard and soft real-time traffic. The network is based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) at its center. Traffic scheduling is centralized in one node (residing together with the AWG in a hub), which communicates through a physical control channel. The AWG's property of spatial wavelength reuse and the combination of fixed-tuned and tunable transceivers in the nodes enable simultaneous control and data transmission. A case study with defined real-time communication requirements in the field of Radar Signal Processing (RSP) was carried out and indicates that the proposed system is very suitable for this kind of application.
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| 5. |
- Böhm, Annette, et al.
(författare)
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Handover in IEEE 802.11p-based delay-sensitive vehicle-to-infrastructure communication
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Based on communication and cooperation between vehicles and roadside infrastructure, Intelligent Transport Systems (ITS) safety applications offer great potential to avoid traffic accidents or at least reduce their impact. As these applications usually are delay-sensitive, the delay introduced by waiting for access to the wireless communication channel should both be reduced and provided with an upper bound. The proposed IEEE 802.11p standard for short to medium range vehicular communication does not offer these guarantees. In previous work, we presented a MAC (Medium Access Control) enhancement supporting delay-sensitive, safety-critical V2I (Vehicle-to-Infrastructure) applications. Since the proposed enhancement requires a deterministic and fast mechanism to associate a vehicle to a roadside unit (RSU) so that it can be integrated into the centralized polling schedule, we now target the handover and connection setup between a vehicle and an RSU. Although the first connection setup with an RSU still underlies the randomness of the original 802.11p MAC method, we provide a deterministic solution to further enhance the handover procedures by introducing a fast, proactive handover mechanism. We show that the overhead of our solution is limited and still allows our MAC protocol to support safety-critical V2I applications in a densely trafficked highway scenario.
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| 6. |
- Böhm, Annette, et al.
(författare)
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Position-based data traffic prioritization in safety-critical, real-time vehicle-to-infrastructure communication
- 2009
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Ingår i: IEEE International Conference on Communications Workshops, 2009. ICC Workshops 2009. - Piscataway, N.J. : IEEE Press. - 9781424434374 ; , s. 205-210
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Konferensbidrag (refereegranskat)abstract
- Future active-safety applications in vehicular networks rely heavily on the support for real-time inter-vehicle communication. The Medium Access Control (MAC) mechanism proposed for the upcoming IEEE 802.11p standard intended for Intelligent Transport Systems (ITS) applications does not offer deterministic real-time support, i.e., the channel access delay is not upper bounded. We therefore propose a vehicle-to-infrastructure (V2I) communication solution extending IEEE 802.11p, by introducing a collision-free MAC phase with an enhanced prioritization mechanism based on vehicle positions and the overall road traffic density. A road side unit using a polling mechanism is then able to provide real-time support such that it can guarantee collision-free channel access within its transmission range. Part of the bandwidth remains unchanged such that best-effort services like ongoing vehicle-to-vehicle (V2V) applications may continue. Our solution guarantees that all communication deadlines of the V2I applications are met, while minimizing the required length of the collision-free phase. This in turn maximizes the amount of bandwidth available for best-effort services and ongoing V2V applications. The position-based prioritization mechanism further improves the throughput of both real-time and best-effort data traffic by focusing the communication resources to the most hazardous areas. The concept is evaluated analytically based on a realistic task set from a V2I merge assistance scenario.
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| 7. |
- Böhm, Annette, et al.
(författare)
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Supporting real-time data traffic in safety-critical vehicle-to-infrastructure communication
- 2008
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Ingår i: 33rd IEEE Conference on Local Computer Networks, 2008. LCN 2008. - Los Alamitos : IEEE Computer Society. - 9781424424122 ; , s. 614-621
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Konferensbidrag (refereegranskat)abstract
- Support for real-time traffic is crucial to many ITS (Intelligent Transport Systems) safety applications. At the same time it is desirable to provide a number of non-safety services. In this paper, we propose a communication system for safety-critical V2I (Vehicle-to-Infrastructure) communication based on an extension to the upcoming IEEE 802.11p MAC standard. Real-time analysis provides the tool to adapt the resources set aside for collision-free, safety-critical data traffic to the communication needs of the current number of supported vehicles. The remaining bandwidth is available to other services according to the contention-based random access method defined in the standard. The performance of the proposed concept is evaluated through a simulation analysis based on a merge assistance scenario supported by roadside infrastructure.
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| 8. |
- Fan, Xing, 1975-, et al.
(författare)
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Admission control for switched real-time Ethernet : scheduling analysis versus network calculus
- 2005
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Ingår i: Proc. of the Swedish National Computer Networking Workshop (SNCNW’05), Halmstad, Sweden, Nov. 23-24, 2005. ; , s. 4 s.-
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Konferensbidrag (refereegranskat)abstract
- Many approaches have been developed to give an estimation of the upper bound of the end-to-end delay or the response-time for real-time application, e.g., the Network Calculus (NC) model and the scheduling analysis. In this paper, we present an approach based on scheduling analysis to support guaranteed real-time services over standard switched Ethernet. Furthermore, we conduct a comparative study between these two admission control schemes, our novel algorithm and an NC-based algorithm. The simulation analysis shows that our feasibility analysis gives up to 50% higher utilization than the popular NC. Another advantage of our solution is that no additional hardware or software modification of the switch and the underlying standard. In our proposal, the traffic differentiation mechanism introduced by the IEEE 802.1D/Q standard and the standard hardware-implemented First Come First Served (FCFS) priority queuing are used in the switch and the source nodes. We have derived a feasibility analysis algorithm to ensure that the real-time requirements can be met. The algorithm also gives, as a sub-result, the needed buffer space in the end nodes and the switch. Moreover, our feasibility analysis supports variable-sized frames and switches with different bit-rates ports.
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| 9. |
- Fan, Xing, 1975-, et al.
(författare)
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Guaranteed real-time communication in packet-switched networks with FCFS queuing
- 2009
-
Ingår i: Computer Networks. - Amsterdam : North Holland. - 1389-1286 .- 1872-7069. ; 53:3, s. 400-417
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a feasibility analysis of periodic hard real-time traffic in packet-switched networks using first come first served (FCFS) queuing but no traffic shapers. Our work constitutes a framework that can be adopted for real-time analysis of switched low-cost networks like Ethernet without modification of the standard network components. Our analysis is based on a flexible network and traffic model, e.g., variable-sized frames, arbitrary deadlines and multiple switches. The correctness of our real-time analysis and the tightness of it for network components in single-switch networks are given by theoretical proofs. The performance of the end-to-end real-time analysis is evaluated by simulations. Moreover, our conceptual and experimental comparison studies between our analysis and the commonly used Network Calculus (NC) shows that our analysis can achieve better performance than NC in many cases.
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| 10. |
- Fan, Xing, 1975-, et al.
(författare)
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Guaranteed Real-Time Communication in Packet-Switched Networks with FCFS queuing : Analysis and Simulations
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this report, we present a real-time analytical framework and the performance evaluation on our analysis. We propose a feasibility analysis of periodic hard real-time traffic in packet-switched networks using First Come First Served (FCFS) queuing but no traffic shapers. We choose switched Ethernet as an example to present the idea of our analysis and our experimental evaluations in this report.The remainder of the report is organized as follows. In Chapter 2, we define the network models, important concepts and terminology for real-time analysis. Chapter 3 presents our real-time analysis for isolated network elements. Chapter 4 gives end-to-end real-time analysis. Chapter 5 presents the performance evaluation of our results by simulation and comparison study and summarizes this report.
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