1,414 research outputs found

    WEIRD Testbeds with Fixed and Mobile WiMAX Technology for User Applications, Telemedicine and Monitoring of Impervious Areas

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    Wireless Metropolitan Area Networks based on IEEE 802.16d/e standards are soon to be deployed in several countries. However, there is lack of published literature with results from actual test¬beds. This paper introduces the work done in the EU Sixth Framework Programme Project WEIRD to design and set up WiMAX testbeds in four EU countries. We describe the method¬ology followed, detail our implementation and present results from the testbeds, as deployed in the first phase of WEIRD. The testbeds are used to demonstrate how WiMAX technology can be used to extend the connectivity of the pan-European data com¬munications network (GEANT2) to isolated and impervious ar¬eas and, furthermore, to assure end-to-end quality of service to novel applications

    WEIRD Testbeds with Fixed and Mobile WiMAX Technology for User Applications, Telemedicine and Monitoring of Impervious Areas

    Get PDF
    Wireless Metropolitan Area Networks based on IEEE 802.16d/e standards are soon to be deployed in several countries. However, there is lack of published literature with results from actual test¬beds. This paper introduces the work done in the EU Sixth Framework Programme Project WEIRD to design and set up WiMAX testbeds in four EU countries. We describe the method¬ology followed, detail our implementation and present results from the testbeds, as deployed in the first phase of WEIRD. The testbeds are used to demonstrate how WiMAX technology can be used to extend the connectivity of the pan-European data com¬munications network (GEANT2) to isolated and impervious ar¬eas and, furthermore, to assure end-to-end quality of service to novel applications.SIGARCH, Create-NetPublishedInnsbruck, Austria1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attiveope

    Spectrum Sharing Methods in Coexisting Wireless Networks

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    Radio spectrum, the fundamental basis for wireless communication, is a finite resource. The development of the expanding range of radio based devices and services in recent years makes the spectrum scarce and hence more costly under the paradigm of extensive regulation for licensing. However, with mature technologies and with their continuous improvements it becomes apparent that tight licensing might no longer be required for all wireless services. This is from where the concept of utilizing the unlicensed bands for wireless communication originates. As a promising step to reduce the substantial cost for radio spectrum, different wireless technology based networks are being deployed to operate in the same spectrum bands, particularly in the unlicensed bands, resulting in coexistence. However, uncoordinated coexistence often leads to cases where collocated wireless systems experience heavy mutual interference. Hence, the development of spectrum sharing rules to mitigate the interference among wireless systems is a significant challenge considering the uncoordinated, heterogeneous systems. The requirement of spectrum sharing rules is tremendously increasing on the one hand to fulfill the current and future demand for wireless communication by the users, and on the other hand, to utilize the spectrum efficiently. In this thesis, contributions are provided towards dynamic and cognitive spectrum sharing with focus on the medium access control (MAC) layer, for uncoordinated scenarios of homogeneous and heterogeneous wireless networks, in a micro scale level, highlighting the QoS support for the applications. This thesis proposes a generic and novel spectrum sharing method based on a hypothesis: The regular channel occupation by one system can support other systems to predict the spectrum opportunities reliably. These opportunities then can be utilized efficiently, resulting in a fair spectrum sharing as well as an improving aggregated performance compared to the case without having special treatment. The developed method, denoted as Regular Channel Access (RCA), is modeled for systems specified by the wireless local resp. metropolitan area network standards IEEE 802.11 resp. 802.16. In the modeling, both systems are explored according to their respective centrally controlled channel access mechanisms and the adapted models are evaluated through simulation and results analysis. The conceptual model of spectrum sharing based on the distributed channel access mechanism of the IEEE 802.11 system is provided as well. To make the RCA method adaptive, the following enabling techniques are developed and integrated in the design: a RSS-based (Received Signal Strength based) detection method for measuring the channel occupation, a pattern recognition based algorithm for system identification, statistical knowledge based estimation for traffic demand estimation and an inference engine for reconfiguration of resource allocation as a response to traffic dynamics. The advantage of the RCA method is demonstrated, in which each competing collocated system is configured to have a resource allocation based on the estimated traffic demand of the systems. The simulation and the analysis of the results show a significant improvement in aggregated throughput, mean delay and packet loss ratio, compared to the case where legacy wireless systems coexists. The results from adaptive RCA show its resilience characteristics in case of dynamic traffic. The maximum achievable throughput between collocated IEEE 802.11 systems applying RCA is provided by means of mathematical calculation. The results of this thesis provide the basis for the development of resource allocation methods for future wireless networks particularly emphasized to operate in current unlicensed bands and in future models of the Open Spectrum Alliance

    Solutions for IPv6-based mobility in the EU project MobyDick

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    Proceedings of the WTC 2002, 18th World Telecommunications Congress, Paris, France, 22 -27 September, 2002.Mobile Internet technology is moving towards a packet-based or, more precisely, IPv6-based network. Current solutions on Mobile IPv6 and other related QoS and AAA matters do not offer the security and quality users have come to take for granted. The EU IST project Moby Dick has taken on the challenge of providing a solution that integrates QoS, mobility and AAA in a heterogeneous access environment. This paper focuses on the mobility part of the project, describes and justifies the handover approach taken, shows how QoS-aware and secure handover is achieved, and introduces the project's paging concept. It shows that a transition to a fully integrated IP-RAN and IP-Backbone has become a distinct option for the future.Publicad

    Final report on the evaluation of RRM/CRRM algorithms

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    Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin

    Voice performance analysis using voice codec by packet fragmentation and contention free periods in wireless networks

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    The admission control is required to maintain the established route between the source and the destination in the wireless network. To maintain the stability of the route, the wireless channel parameters has to be adopted appropriately. Thus, this study analyzes the wireless access medium parameter through direct coordination (DCF) and point-to-point coordination method. The packets are fragmented in DCF and contention free period interval are adjusted to study the QoS parameters for various VOIP codec using OPNET simulation tool. The result shows that packet fragmentation to 256 bytes and contention free period for 20 ms improves QoS for G.729 for Voice traffic

    An improved medium access control protocol for real-time applications in WLANs and its firmware development

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    The IEEE 802.11 Wireless Local Area Network (WLAN), commonly known as Wi-Fi, has emerged as a popular internet access technology and researchers are continuously working on improvement of the quality of service (QoS) in WLAN by proposing new and efficient schemes. Voice and video over Internet Protocol (VVoIP) applications are becoming very popular in Wi-Fi enabled portable/handheld devices because of recent technological advancements and lower service costs. Different from normal voice and video streaming, these applications demand symmetric throughput for the upstream and downstream. Existing Wi-Fi standards are optimised for generic internet applications and fail to provide symmetric throughput due to traffic bottleneck at access points. Performance analysis and benchmarking is an integral part of WLAN research, and in the majority of the cases, this is done through computer simulation using popular network simulators such as Network Simulator ff 2 (NS-2) or OPNET. While computer simulation is an excellent approach for saving time and money, results generated from computer simulations do not always match practical observations. This is why, for proper assessment of the merits of a proposed system in WLAN, a trial on a practical hardware platform is highly recommended and is often a requirement. In this thesis work, with a view to address the abovementioned challenges for facilitating VoIP and VVoIP services over Wi-Fi, two key contributions are made: i) formulating a suitable medium access control (MAC) protocol to address symmetric traffic scenario and ii) firmware development of this newly devised MAC protocol for real WLAN hardware. The proposed solution shows signifocant improvements over existing standards by supporting higher number of stations with strict QoS criteria. The proposed hardware platform is available off-the-shelf in the market and is a cost effective way of generating and evaluating performance results on a hardware system
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