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In this paper, a novel non-saturation analytical model for enhanced distributed channel access (EDCA) in IEEE 802.11e wireless local area network (WLAN) is proposed. Unlike previous work focused on saturation conditions, this model uses Markov and M/M/1/K theories to predict MAC delay, service time, throughput and loss. Moreover, the EDCA technique resets the default contention window (CW) of stations...
In order to guarantee the QoS requirements in IEEE 802.11 WLANs, the IEEE 802.11e standard for MAC enhancement has been proposed to support delay-sensitive applications. The IEEE 802.11e enhanced distributed coordination function (EDCF) provides traffic differentiation based on a set of static Access Category (AC) MAC parameters which guarantee prioritization of real-time flows with strict bandwidth...
One of the most challenge applications in VANET is a safety application. The important characteristic of this application is stringent time constraints. To satisfy these constraints, seamless handoffs must be provided. The mechanism making successful seamless handoffs is a network selection technique. Several techniques such as AHP, SAW, GRA and TOPSIS were proposed to select a network satisfying...
With the development of railway transit wireless communication technology, the existing test platforms about comprehensive test are facing new challenge of real-time problems. Aiming at the demand for Doppler Effect testing of domestic railway transit WLAN equipment and in consideration of the flaw of small bandwidth and relatively large delay of the channel emulator, this paper proposes a novel approach...
In order to implement the heterogeneous wireless network using multiple wireless systems, it is important to comprehend the transmission quality characteristics such as the transmission throughput and delay, because the network control managements are performed based on these qualities. In this paper, we address the study results regarding the transmission quality characteristics of the Wireless LAN...
Vertical handoff plays an important role in guaranteeing users to be always connected in an overlapped multi-network environment. During the vertical handoff procedure, handoff decision is the most important step that affects the normal working of communication. An incorrect handoff decision or selection of a non-optimal network may result in undesirable effects such as higher costs, poor quality...
This article makes a taxonomic study of wireless traffic using a model of self-similarity based on traffic components at the link, network and transport layer. We evaluate applications performance using two different simulation scenarios in which the traffic is defined according to the statistical parameters observed in real traffic. The simulations evaluate network performance using different compositions...
There are obvious differences between video and data frame transmission in WLAN, for the video streams need to provide people with consequent and distinct scene. Thus we should concern with the transmission delay and throughput for the video frame. In transmission, the long video frame would be segmented, and then fill into the SDU. Different frame rate and size lead to different MAC layer transmission...
Wireless local area network (WLAN) has become more popular in recent years. With increase in demand users are expecting quality of service (QoS) for multimedia services in WLAN. The legacy protocol IEEE 802.11 and IEEE 802.11e does not provide QoS and fairness for converging traffic in WLAN, so efficient management of protocols are required to provide acceptable QoS for real time traffic and fairness...
Voice over IP “VoIP” is a form of voice speech that uses data networks, for transmission of voice traffic over IP-based networks to transmit voice signals. The signal is correctly encoded at one end of the communication channel, sent as packets through the data network, then decoded at the receiving end and transformed back into a voice signal. It has a potential and offering a choice to the traditional...
In this paper, we propose a consistent random backoff (CRB) scheme to reduce the channel access delay jitter in voice over wireless local area networks (VoWLANs). In the CRB scheme, a contention window (CW) size at each backoff stage is determined by hashing the session identifier and the talk spurt index. Therefore, all packets in the same talk spurt of a session have the same CW sizes if they are...
In wireless local area networks (WLANs), there could be several available access points (APs) around a Station (STA). How to select the most appropriate AP among those available APs has become a hot research topic. The conventional selection policy, which selects one AP with the best RSSI, makes the loads among APs be distributed unevenly and degrades resource utilization rate. Recently, several AP...
Reduction of power consumption is one of an important issue in wireless communications because most mobile devices are battery-driven. There are many power saving techniques for use in a wireless LAN (WLAN) environment at the hardware level and at the MAC protocol level. Their common strategy for power saving is to stay in sleep mode, which consumes very little energy, for as long as possible when...
Today's laptops and mobile terminals are equipped with several network interfaces belonging to different access technologies. Users can benefit from multi-homing to access network services anywhere, at any time and from any network. Multipath TCP (MPTCP) is a modified version of Transmission Control Protocol (TCP) which allows a TCP connection to simultaneously send data over multiple paths. One of...
To support delay-sensitive applications on IP over wireless LAN (WLAN), both layer-2 handoff (L2H) and layer-3 handoff (L3H) must be conducted efficiently. Prior studies toward a fast L2H/L3H assume simple networking environments where Extended Service Set (ESS) exactly matches subnets. This paper identifies performance issues associated with inter-ESS L2Hs and L3Hs under mismatching ESS-subnet configurations,...
With the extensive deployment of 802.11 wireless local area networks (WLANs) and the need for better quality of service (QoS), the 802.11e MAC with service differentiation was developed. Analysing the effect of fading, shadowing and near-far effect on the performance of 802.11 is a fundamental consideration in practical situations since the wireless channels are errorprone.This paper develops a p-persistent...
Cellular networks coupled with wireless local area networks would be very common in the next- generation wireless environments. This integration would be made possible by employing techniques of vertical handover across different radio access networks. Finding precise timing to carry out vertical handover is an important problem and is the topic of this research work. We propose a hybrid vertical...
A 2–2 cascade multirate sigma delta modulator targeting for GSM/ Bluetooth/ GPS/ WCDMA/ WLAN/ WiMAX application is designed in this paper. According to the needs of the customers and desired Quality of Service, the proposed modulator should be a power and area efficient reconfigurable sigma delta modulator with variable bandwidth and dynamic range. The multirate technique is introduced in the modulator...
The next generation technology of Voice over Internet Protocol (VoIP) allows voice to be delivered over the Internet Protocol based networks. The integration of VoIP and Wireless Local Area Network (WLAN) has become popular. However, WLAN architecture was primarily designed to carry data and not for real-time applications, such as VoIP. Hence, there is a need to enhance the quality of VoIP transmission...
Various application services including multimedia applications need efficient multicast technologies, but the IEEE 802.11 protocol, which is currently the most widely used, does not specify the standard on multicast, which is, instead, substituted by broadcast or a combination of unicast. Using broadcast is, however, difficult to judge on the transmission success or fail, because it does not receive...
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