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THE IEEE Design Automation Standards Committee and the IEEE Corporate Advisory Group are cosponsoring an interesting new standards project. IEEE P1685 (www.eda-stds.org/spirit-p1685) aims to develop an XML-based standard for descr...
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THE IEEE Design Automation Standards Committee and the IEEE Corporate Advisory Group are cosponsoring an interesting new standards project. IEEE P1685 (www.eda-stds.org/spirit-p1685) aims to develop an XML-based standard for describing electronic intellectual property (IP).
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Nach 2,5 Jahren intensiver Arbeit wurden die wichtigsten IEEE 5.9 WAVE-Standards IEEE802.11p, IEEE1609.4 und IEEE1609.3 von der Version „Trial Use" in „Füll Use" übergeleitet und publiziert.Das U.S. Department of Transportatio...
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Nach 2,5 Jahren intensiver Arbeit wurden die wichtigsten IEEE 5.9 WAVE-Standards IEEE802.11p, IEEE1609.4 und IEEE1609.3 von der Version „Trial Use" in „Füll Use" übergeleitet und publiziert.Das U.S. Department of Transportation (US DOT) ist dabei, die aktualisierten Standards durch mehrere Hersteller implementieren zu lassen und diese im Rahmen von Pilotprojekten in einem End-to-end-System zu validieren. Im Fokus dieser Pilotprojekte sind dabei verschiedene Anwendungen im Bereich Straßenverkehrssicherheit.Dieser Beitrag gibt einen Überblick über die IEEE 5.9 WAVE-Standards, die Basis-Architektur der Straßen- (Roadside Unit, RSU) und der fahrzeugseitigen (Onboard Unit, OBU) Ausrüstung sowie über die Applikationen, die dafür eingesetzt werden, um die Standards und deren Anwendungen zu validieren. Nicht zuletzt werden die Aktivitäten der Kapsch TrafficCom in diesem Umfeld beschrieben.
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Wifeless access in the vehicular environment (WAVE) architecture of intelligent transportation system (ITS) has been standardized in the IEEE 802.11p specification and it is going to be widely deployed in many roadway environments...
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Wifeless access in the vehicular environment (WAVE) architecture of intelligent transportation system (ITS) has been standardized in the IEEE 802.11p specification and it is going to be widely deployed in many roadway environments in order to provide prompt emergency information and internet services. A typical WAVE network consists of a number of WAVE devices, in which one is the road-side-unit (RSU) and the others are on-board-units (OBUs), and supports one control channel (CCH) and one or more service channels (SCH) for OBU access. The CCH is used to transport the emergency messages and service information of SCHs and the SCHs could be used to carry internet traffic and non-critical safety traffic of OBUs. However, the IEEE 802.11p contention-based medium access control protocol would suffer degraded transmission efficiency if the number of OBUs contending on an SCH is large. Moreover, synchronizing all WAVE devices to periodically and equally access the CCH and an SCH will waste as much as 50% of the channel resources of the SCH [1]. As a solution, we propose an efficiency-improvement scheme, namely the agent-based coordination (ABC) scheme, which improves the SCH throughput by means of electing one OBU to be the agent to schedule the other OBUs so that they obtain the access opportunities on one SCH and access the other SCH served by RSU in a contention-free manner. Based on the ABC scheme, three different scheduling and/or relaying strategies are further proposed and compared. Numerical results and simulation results confirm that the proposed ABC scheme significantly promotes the standard transmission efficiency.
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Wireless Access in the Vehicular Environment (WAVE) specification defines the WAVE Short Message Protocol (WSMP) for delivering WAVE Short Messages (WSMs). In the multihop transmission, WSMs are first received and stored in queues...
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Wireless Access in the Vehicular Environment (WAVE) specification defines the WAVE Short Message Protocol (WSMP) for delivering WAVE Short Messages (WSMs). In the multihop transmission, WSMs are first received and stored in queues and then forwarded to the next hop. Unfortunately, WSMP does not specify any mechanism to avoid the messages loss resulted from queueing overflow. In this paper, a dual threshold-based queueing management which adjusts the message accepting rate upon the current queue length is proposed. The multihop transmission can be modeled as a tandem queueing network, and a discrete time Markov chain (DTMC) can be applied to evaluate the proposed queueing management. Since the computational complexity increases with the number of hops, an approximation approach to resolve DTMC model is also presented. Simulation results demonstrate the accuracy of approximation and the effectiveness of the proposed queueing management.
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An intelligent transportation system is proposed to integrate information and communication technologies into vehicles and transport infrastructure to improve vehicular safety. To accelerate the commercialization of intelligent tr...
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An intelligent transportation system is proposed to integrate information and communication technologies into vehicles and transport infrastructure to improve vehicular safety. To accelerate the commercialization of intelligent transportation system, a series of wireless access schemes for vehicular environments are proposed. These schemes, however, still suffer from multiple collisions of emergent messages in control channels (CCH), resulting in a driver may not receiving emergent messages in time. This work develops group reservation medium access control (GRMAC) to minimize the collisions of emergent messages in vehicular environments and thereby increase the availability of emergent messages. GRMAC also allows vehicles to reserve CCH bandwidth when they stay in service channels (SCH) in order to reduce collisions of emergent messages in CCH. GRMAC also migrates the CCH bandwidth scheduling mechanism from CCH to SCHs to reduce the burden on CCH. The theoretical analysis and simulation results under heavy loads shows that GRMAC achieves two time the goodput of conventional IEEE 802.11p/1609 mechanism and six time that of dedicated multi-channel MAC.
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Transmission control protocol (TCP) is one of the popular protocol in many applications which requires reliable end-to-end protocol. Improvement or replacement of TCP in wireless environments, unfortunately, studies have shown tha...
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Transmission control protocol (TCP) is one of the popular protocol in many applications which requires reliable end-to-end protocol. Improvement or replacement of TCP in wireless environments, unfortunately, studies have shown that TCP performance in Vehicular Ad-hoc Networks (VANETs) is very poor. TCP treats packet loss as a sign of network congestion. In wireless network however, losses can occur for reasons besides congestions, poor channel condition or collision. So TCP will reduce congestion window size, effectively decreasing throughput. In VANET, the path symmetry is not guaranteed due to high mobility. This can decrease TCP performance due to incorrect estimation of RTT times, resulting in unnecessary retransmission which produce excess of congestion in the network. The existing TCP variants cannot yield good performance in highly mobile environment due to the fact that TCP cannot able to differentiate packet drop occur from link failure with that of congestion in network. To overcome the problem of frequent retransmission, a Significant RTT timer modification to be made at the TCP sender side. The ultimate intend of the project is to design a new RTT, SRTT and RTO timers for high mobility environment (VANET). In this regard, an exclusive examination is being done with the existing RTT, SRTT and RTO timers under different TCP variants for vehicular network. The analysis was done with Bonn Motion mobility model that is built over NS-2 simulator. The TCP variants were evaluated with the metrics such as end-to-end delay, packet delivery factor, good put and throughput.
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In recent years, lot of research activities undergone on vehicular communication. An intelligent transportation system (ITS) is a technology particularly used for transportation that uses moving cars as nodes in a network to crea...
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In recent years, lot of research activities undergone on vehicular communication. An intelligent transportation system (ITS) is a technology particularly used for transportation that uses moving cars as nodes in a network to create a mobile network. This technology offers an extensive range of applications including safety and non safety applications such as traffic management, road safety and infotainments. Vehicles are dynamically clustered according to different metrics such as direction of vehicles' movement, WiMAX Received Signal Strength, and inter-vehicular distance, respectively. In this work, Authors focus on the design of hybrid communication system for vehicular communication. The Dedicated Short Range Communication (DSRC) and WiMAX can be converged for the same. Authors have designed the physical layer to bridge between DSRC and WiMAX which involves all the processing performed on peak data rates of more than the vehicular communication standards. Authors successfully simulated data transmission of this system in MATLAB. By using OFDM physical layer parameters we can combine IEEE 802.11p standards and WiMAX to achieve such a performance in ITS.
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