Stefan Mangold

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In this paper, a comprehensive overview of the new features of an upcoming new standard IEEE 802.11e to support Quality of Service (QoS) in Wireless Local Area Networks (WLANs) is presented. We address Medium Access Control (MAC) enhancements found in the current 802.11e draft specification by emphasizing the differences from the legacy 802.11 standard. New(More)
and Introduction Legacy 802.11 • Distributed Coordination Function • Point Coordination Function QoS Support Mechanisms Of 802.11e • Basic Improvements of the Legacy 802.11 Mac • HCF Contention-based Medium Access • Hybrid Coordination Function, Controlled Medium Access • Improved Efficiency Evaluation Summary and Conclusions
IEEE 802.11e Medium Access Control (MAC) is an emerging supplement to the IEEE 802.11 Wireless Local Area Network (WLAN) standard to support Quality-of-Service (QoS). The 802.11e MAC is based on both centrally-controlled and contention-based channel accesses. In this paper, we evaluate the contention-based channel access mechanism, called enhanced(More)
One of the reasons for the limitation of bandwidth in current generation wireless networks is the spectrum policy of the Federal Communications Commission (FCC). But, with the spectrum policy reform, open spectrum wireless networks, and spectrum agile radios are set to drive next general wireless networks. In this paper, we investigate continuous-time(More)
Visible Light Communication (VLC) with Light Emitting Diodes (LEDs) as transmitters and receivers enables low bitrate wireless adhoc networking. LED-to-LED VLC adhoc networks with VLC devices communicating with each other over free-space optical links typically achieve a throughput of less than a megabit per second at distances of no more than a few meters.(More)
The opening up of the unlicensed bands for commercial use has been a tremendous success. Wireless communications in computing, mobile, medical and consumer electronics market segments have grown rapidly in the past few years. Due to this success, radio resources in the unlicensed bands are progressively becoming scarce. Recently, the Spectrum Policy Task(More)
Wireless local area networks have been designed for wireless communication. Frames are acknowledged (ACKed) after a short and predefined MAC idle time. The MAC idle time varies with i) the physical distance between stations, caused by the delay of wireless signal propagation, and ii) the time to detect the ACK at the local station, which varies with the(More)
Radio spectrum allocation is undergoing radical rethinking. Regulators, government agencies, industry and the research community recently established many initiatives for new spectrum policies and seek approaches to more efficiently manage the radio spectrum. In this paper, we are examining new approaches, namely, spectrum agile radios, for opportunistic(More)