The IEEE 802.11e standard revises the Medium Access Control (MAC) layer of the former IEEE 802.11 standard for Quality-of-Service (QoS) provision in the Wireless Local Area Networks (WLANs). The Enhanced Distributed Channel Access (EDCA) function of 802.11e defines multiple Access Categories (AC) with AC-specific Contention Window (CW) sizes, Arbitration Interframe Space (AIFS) values, and Tran...

In this paper, the timing behavior of the EDCA mechanism defined in the IEEE 802.11e standard is analyzed. More specifically, the target of this paper is to understand the limitations of the highest priority level of the EDCA mechanism (voice category) when supporting real-time (RT) communication. We show that for most part of the evaluated scenarios, when using the default parameters of the ED...

This paper proposes a very simple reduced abstract model of the behavior of the EDCA (Enhanced Distributed Channel Access) access mode with respect to an access category under saturation. This model is derived from a Markov chain model of EDCA using reduction techniques. Closed-form expressions of common performance metrics (i.e. mean throughput, mean access delay and packet drop probability of...

In this study, throughput and delay performance of IEEE 802.11b and 802.11e is presented under non-saturation conditions. In order to improve the performance of IEEE 802.11b, the IEEE 802.11e has been proposed to improve the Quality of Services (QoS) for multimedia application. The standard 802.11b CSMA/CA contention mechanism does not support QoS but the standard 802.11e provides QoS by adjust...

IEEE approved the 802.11 standard amendment for QoS support in 2005 after having issued 13 draft versions. Over this period, several technical changes, e.g., regarding the backoff procedure evolved. The original TKN EDCF model, published in 2003 for ns-2.26 is based on 802.11e Draft 2 respective 4 and had to be adjusted accord to the final standard amendment. The resulting novel TKN EDCA model ...

Problem statement: The IEEE 802.11e EDCA protocol with different access Categories (ACs) supporting for Quality-of-Service (QoS). Due to internal or external packet collision, the Contention Window (CW) of the station increases the channel idle time under high Bit Error Rate (BER). Approach: In this study, we propose an analytical model for performance evaluation of IEEE 802.11e EDCA scheme und...

802.11b The legacy IEEE 801.11 doesn’t support QoS streams with priorities. It since causes some QoS demanding applications such as VoIP, Video streaming to be limited in its usefulness. Enhancements have been made to the MAC layer by the new 802.11e standard to support prioritized and parameterized QoS. The work of this paper is to simulate the new scheme and modify the existing OPNET WLAN MAC...

One of the main challenges with 802.11e EDCA is the configuration of the open parameters of this mechanism, namely AIFS, CWmin, CWmax and TXOP_limit. In this paper, we address the issue of finding the optimal configuration of these parameters in order to maximize the throughput performance of the WLAN. We first present a model to analyze the throughput performance of an EDCAWLAN as a function o...

window, collision, IEEE 802.11e, EDCF. Abstract—The Enhanced Distributed Channel Access (EDCA) is introduced to provide QoS on the basis of Distributed Coordination Function (DCF) in IEEE802.11. The access mechanism of IEEE802.11e, referred to as EDCA, assigns different access categories (AC) with different types of data traffic based on priorities. Each priority uses a different set of medium ...

Multimedia communications over WLAN is widely acknowledged as one of the key, emerging applications for wireless LANs. As with any multiservice network, there is the need to provision the WLANs with the QoS mechanisms capable of guaranteeing the requirements of various services. The IEEE 802.11e (EDCA) standard defines the required QoS mechanisms into the protocol architecture of IEEE 802.11 WL...