3,217 research outputs found

    Design of Media Access Control Schemes for Performance Enhancement of Future Generation Wireless Systems

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    Wireless Local Area Networks (WLANs) now provide connectivity to many businesses, homes and educational institutions. The wireless channel itself is plagued with numerous problems, such as it does not natively allow sharing of the wireless resource. WLAN devices utilize a complex medium access control (MAC) mechanism to allow multiple users to share the wireless resource. The distributed coordination function (DCF) is the most commonly used multiple access scheme in WLANs and a member of the 802.11 standard [1]. In this thesis, two major roles of MAC protocols are examined: maximizing network throughput and service differentiation. Firstly, a novel MAC scheme is proposed that makes use of Multiple-Input, Multiple-Output (MIMO) antenna technology to improve overall network throughput. The proposed MIMO-Aware MAC (MA-MAC) scheme utilizes the beamforming feature available in MIMO systems to allow two simultaneous transmissions of the wireless channel overlapped in time. This results in increased aggregate network throughput. This proposed scheme is shown to offer better throughput and delay performance versus existing MAC schemes proposed for simultaneous transmission. In addition, this MAC scheme is able to achieve this performance in a manner compatible with the existing standard. The latter part of this thesis proposes a new Time Division Multiple Access (TDMA) based scheme for providing video, voice and data services (also known as the Triple-Play services) in a point-to-multipoint network. By dynamically allocating transmission slots, the proposed Television TDMA (TV-TDMA) scheme is shown to better meet delay requirements for video and voice traffic, and is able to achieve higher overall saturation throughput for best-effort traffic than existing Quality of Service enabled protocols

    Design of Media Access Control Schemes for Performance Enhancement of Future Generation Wireless Systems

    Get PDF
    Wireless Local Area Networks (WLANs) now provide connectivity to many businesses, homes and educational institutions. The wireless channel itself is plagued with numerous problems, such as it does not natively allow sharing of the wireless resource. WLAN devices utilize a complex medium access control (MAC) mechanism to allow multiple users to share the wireless resource. The distributed coordination function (DCF) is the most commonly used multiple access scheme in WLANs and a member of the 802.11 standard [1]. In this thesis, two major roles of MAC protocols are examined: maximizing network throughput and service differentiation. Firstly, a novel MAC scheme is proposed that makes use of Multiple-Input, Multiple-Output (MIMO) antenna technology to improve overall network throughput. The proposed MIMO-A ware MAC (MA-MAC) scheme utilizes the beamforming feature available in MIMO systems to allow two simultaneous transmissions of the wireless channel overlapped in time. This results in increased aggregate network throughput. This proposed scheme is shown to offer better throughput and delay performance versus existing MAC schemes proposed for simultaneous transmission. In addition, this MAC scheme is able to achieve this performance in a manner compatible with the existing standard. The latter part of this thesis proposes a new Time Division Multiple Access (TDMA) based scheme for providing video, voice and data services (also known as the Triple-Play services) in a point-to-multipoint network. By dynamically allocating transmission slots, the proposed Television TDMA (TV-TDMA) scheme is shown to better meet delay requirements for video and voice traffic, and is able to achieve higher overall saturation throughput for best-effort traffic than existing Quality of Service enabled protocols

    Wireless industrial monitoring and control networks: the journey so far and the road ahead

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    While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks

    Design of Media Access Control Schemes for Performance Enhancement of Future Generation Wireless Systems

    Get PDF
    Wireless Local Area Networks (WLANs) now provide connectivity to many businesses, homes and educational institutions. The wireless channel itself is plagued with numerous problems, such as it does not natively allow sharing of the wireless resource. WLAN devices utilize a complex medium access control (MAC) mechanism to allow multiple users to share the wireless resource. The distributed coordination function (DCF) is the most commonly used multiple access scheme in WLANs and a member of the 802.11 standard [1]. In this thesis, two major roles of MAC protocols are examined: maximizing network throughput and service differentiation. Firstly, a novel MAC scheme is proposed that makes use of Multiple-Input, Multiple-Output (MIMO) antenna technology to improve overall network throughput. The proposed MIMO-Aware MAC (MA-MAC) scheme utilizes the beamforming feature available in MIMO systems to allow two simultaneous transmissions of the wireless channel overlapped in time. This results in increased aggregate network throughput. This proposed scheme is shown to offer better throughput and delay performance versus existing MAC schemes proposed for simultaneous transmission. In addition, this MAC scheme is able to achieve this performance in a manner compatible with the existing standard. The latter part of this thesis proposes a new Time Division Multiple Access (TDMA) based scheme for providing video, voice and data services (also known as the Triple-Play services) in a point-to-multipoint network. By dynamically allocating transmission slots, the proposed Television TDMA (TV-TDMA) scheme is shown to better meet delay requirements for video and voice traffic, and is able to achieve higher overall saturation throughput for best-effort traffic than existing Quality of Service enabled protocols
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