This paper proposes analytical expressions of end-to-end throughput for IEEE 802.11e Enhanced Distributed Channel Access (EDCA) wireless string-topology multi-hop networks. For obtaining the IEEE 802.11e EDCA performance, internal collisions between Access Categories (ACs) in a node, frame collisions with external nodes, and frame-existence probabilities of buffers at each AC are expressed as f...

Although the EDCA access mechanism of the 802.11e standard supports legacy DCF stations, the presence of DCF stations in the WLAN jeopardizes the provisioning of the service guarantees committed to the EDCA stations. The reason is that DCF stations compete with Contention Windows (CW ’s) that are predefined and cannot be modified, and as a result the impact of the DCF stations on the service re...

IEEE 802.11e network standard supports the quality of service through EDCA technique. This technique does not fulfill the requirements of QoS. So in this paper, we have proposed modified EDCA technique to improve the QoS in same IEEE 802.11e networks. In this approach, we have changed Contention Window size. The proposed method is implemented in NS2 and also this should compare with conventiona...

The ability to perform traffic differentiation is a promising feature of the current Medium Access Control (MAC) in Wireless Local Area Networks (WLANs). The Enhaced Distributed Channel Access (EDCA) MAC protocol for WLANs proposes up to four Access Categories (AC) that can be mapped to different traffic priorities. High priority ACs are allowed to transmit more often than low priority ACs, pro...

IEEE 802.11e specifies the Enhanced Distributed Channel Access (EDCA) for distributed access with traffic differentiation to a Wireless Local Area Network (WLAN). Traffic differentiation led to introducing several traffic queues within each station, thus introducing virtual collision. In this paper, we present a pattern based Markov chain model of EDCA including the virtual collision phenomenon...

In this paper we describe how the contentionbased medium access mechanism of 802.11e, EDCA, can be enhanced in order to allow stations to reserve medium access for their real-time applications with QoS requirements. We present our proposed scheme, which is called EDCA with resource reservation (EDCA/RR), and describe how it can be extended in order to be used in wireless multi-hop networks. EDC...

The popular IEEE 802.11 WLAN today does not provide any quality-of-service (QoS) because of its contention-based channel access nature of the medium access control (MAC). Therefore, we proposed a simple software upgradebased solution, called a dual queue scheme, to provide QoS to real-time services such as Voiceover-IP (VoIP) in our previous work. The dual queue scheme operates on top of the le...

This paper investigates rate configuration of the Expedited Forwarding (EF) class of Differentiated Services (DiffServ) when used with 802.11e EDCA. The rate configuration problem is presented, and several approaches are tested and evaluated in order to solve the problem. Results reveal that the contention window makes rate configuration very hard for the highest priority class (AC_VO) in 802.1...

IEEE 802.11e Enhanced Distributed Channel Access (EDCA) is the most popular standard used in WLAN to support QoS for various real-time service flows. Based on DCF, EDCA introduces some new QoS parameters, which are defined by IEEE 802.11e standard. But how to adjust these parameters is still worth investigating. In the paper, we present a novel saturated throughput analysis of the IEEE 802.11e ...