5,742 research outputs found
QoS evaluation of the WLAN IEEE 802.11e
Wireless networks have a variety of advantages making them very popular in various applications. As the use of wireless networks increases, so does the demand for better service in terms of less delay for voice and video traffic. In 1990 the IEEE 802.11 was defined as a wireless network standard, yet this standard lacks traffic differentiation techniques to provide time-efficient service. The Work Group "e" has been working on enhancing the service since end of 2002; currently it defined a draft that will be the future standard to enhance the service. This new standard will enhance the use of wireless networks in time sensitive applications such as videoconferencing and voice over the internet protocol (VoIP). This study evaluated and suggested enhancements for the service performance of the defined IEEE 802.11 e draft. It is essential to assess the performance of the draft, as it will be the baseline standard for all the IEEE 802.11 wireless network vendors. The results of this work show that legacy networks (networks without the IEEE 802.11e implementation) perform better than the IEEE 802.11e networks under single kind of traffic (either data, voice or video traffic). Considering such conclusions is critical for businesses-when making decisions to upgrade or forgo purchasing costly equipment. Improvement suggestions to the upcoming IEEE 802.11e were made based on simulation results to change the default value of some parameters to achieve better performance under mixed traffic. The simulation results also show that the IEEE 802.11e provides priority to voice and video over data traffic
A Dynamic Multimedia User-Weight Classification Scheme for IEEE_802.11 WLANs
In this paper we expose a dynamic traffic-classification scheme to support
multimedia applications such as voice and broadband video transmissions over
IEEE 802.11 Wireless Local Area Networks (WLANs). Obviously, over a Wi-Fi link
and to better serve these applications - which normally have strict bounded
transmission delay or minimum link rate requirement - a service differentiation
technique can be applied to the media traffic transmitted by the same mobile
node using the well-known 802.11e Enhanced Distributed Channel Access (EDCA)
protocol. However, the given EDCA mode does not offer user differentiation,
which can be viewed as a deficiency in multi-access wireless networks.
Accordingly, we propose a new inter-node priority access scheme for IEEE
802.11e networks which is compatible with the EDCA scheme. The proposed scheme
joins a dynamic user-weight to each mobile station depending on its outgoing
data, and therefore deploys inter-node priority for the channel access to
complement the existing EDCA inter-frame priority. This provides efficient
quality of service control across multiple users within the same coverage area
of an access point. We provide performance evaluations to compare the proposed
access model with the basic EDCA 802.11 MAC protocol mode to elucidate the
quality improvement achieved for multimedia communication over 802.11 WLANs.Comment: 15 pages, 8 figures, 3 tables, International Journal of Computer
Networks & Communications (IJCNC
Comparative Analysis of QoS Guarantee on IEEE 802.11e and IEEE 802.11g Wireless Local Area Networks
For this project, we propose to compare the 802.11g and the 802.11e Wireless Local Area Networks (WLANs). The 802.11g WLAN standards are good for data applications. However, the 802.11g standard is not well-equipped to deal with the intended delay and bandwidth requirements of multimedia applications, such as video and voice over wireless IP. For this reason, an approved amendment (802.11e) was added to the IEEE 802.11 standard. The 802.11e implements Quality of Service (QoS), which enables features through changes in the Medium Access Control (MAC) layer. The performance of 802.11e will be evaluated using OPNET simulation and compared with the 802.11g WLAN standard. Â Keyword: QoS, IEEE 802.11, WLAN, MAC, OPNET, WiFi, CSMA/CA
A network resource availability model for IEEE802.11a/b-based WLAN carrying different service types
The electronic version of this article is the complete one and can be found online at: http://jwcn.eurasipjournals.com/content/2011/1/103.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Operators of integrated wireless systems need to have knowledge of the resource availability in their different access networks to perform efficient admission control and maintain good quality of experience to users. Network availability depends on the access technology and the service types. Resource availability in a WLAN is complex to gather when UDP and TCP services co-exist. Previous study on IEEE802.11a/b derived the achievable throughput under the assumption of inelastic and uniformly distributed traffic. Further study investigated TCP connections and derived a model to calculate the effective transmission rate of packets under the assumption of saturated traffic flows. The assumptions are too stringent; therefore, we developed a model for evaluating WLAN resource availability that tries to narrow the gap to more realistic scenarios. It provides an indication of WLAN resource availability for admitting UDP/TCP requests. This article presents the assumptions, the mathematical formulations, and the effectiveness of our model
Analysis and Performance Evaluation of IEEE 802.11 WLAN
With fast deployment of wireless local area networks VoIP over IEEE 802.11 wireless local area network (WLAN) is growing very fast and is providing a cost effective alternative for voice communications. WLANs were initially set up to handle bursty nonreal time type of data traffic. Therefore, the wireless access protocols initially defined are not suitable for voice traffic. Subsequently, updates in the standard have been made to provision for QoS requirements of data, especially the real time traffic of the type voice and video. Despite these updates, however, transmitting voice traffic over WLAN does not utilize the available bandwidth (BW) efficiently, and the number of simultaneous calls supported in practice is significantly lower than what the BW figures would suggest. Several modifications have been proposed to improve the call capacity, and recently isochronous coordination function (ICF) was introduced to mitigate the problem of low call capacity. The proposed modified ICF which further improves the performance in terms of the call capacity. The proposed scheme uses multiplexing and multicasting in the downlink to substantially increase the call capacity
A control theoretic approach to achieve proportional fairness in 802.11e EDCA WLANs
This paper considers proportional fairness amongst ACs in an EDCA WLAN for
provision of distinct QoS requirements and priority parameters. A detailed
theoretical analysis is provided to derive the optimal station attempt
probability which leads to a proportional fair allocation of station
throughputs. The desirable fairness can be achieved using a centralised
adaptive control approach. This approach is based on multivariable statespace
control theory and uses the Linear Quadratic Integral (LQI) controller to
periodically update CWmin till the optimal fair point of operation. Performance
evaluation demonstrates that the control approach has high accuracy performance
and fast convergence speed for general network scenarios. To our knowledge this
might be the first time that a closed-loop control system is designed for EDCA
WLANs to achieve proportional fairness
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