IEEE 802.11e-EDCF Evaluation through MAC-Layer Metrics over QoS-aware Mobility Constraints Khaled Dridi Laboratory of Images, Signals and Intelligent Systems, University of Paris East, France. Nadeem Javaid Laboratory of Images, Signals and Intelligent Systems, University of Paris East, France. Boubaker Daachi Laboratory of Images, Signals and Intelligent Systems, University of Paris East, France. Karim Djouani LISSI, University of Paris East, France. djouani@univ-paris12.fr F’SATI, Pretoria, S. Africa. ABSTRACT This paper presents how enhanced Quality of Service (QoS) in IEEE802.11e is achieved by providing traffics with different priorities performing the access to the wireless medium. Particularly, the EDCF set of parameters defines the priorities of the admission control mechanism during the Contention-based Period (CP). This can subsequently be declined to a variation of network dynamicity. Reliability analysis of different traffic classes (video, voice and data), without considering both network topology and node’s mobility constraints, is not well appropriate. Being based upon scenarios, our proposed approach reveals how the behaviour of the service differentiation scheme is greatly affected according to the nodes’ mobility (position and velocity). Thus, three levels (Low, Medium, and High) of node’s speed are discerned. Depending on the Access Aategories (AC’s) in QoS Stations (QSAT’s), the Wireless LAN has been implemented on various static and dynamic scenarios using NS-2. Performance of EDCF based on the main MAC-layer metrics, such as throughput, End-2-End delay and jitter, is deeply investigated. Keywords IEEE 802.11e, EDCF, Mobility, QoS, Throughput, End-2-end delay, Jitter. 1. INTRODUCTION Though wireless networks suffer from lower bandwidth (rather shared bandwidth), higher Bit Error Rate (BER), important amount of delays, and lower security than wired networks, still they have been emerged as a prevailing technology for the broadband wireless access, like IEEE 802.11 WLAN. ‘Shared Medium’ is the basic cause for the problem which must: provide service differentiation between different types of traffic, risk of collisions, low medium utilization, etc. Moreover wireless networks are much better than the wired networks because of: more flexibility, easy installation, increased bandwidth and very less prices [6]. If the recent standards of IEEE 802.11x provide the guarantee for connectivity, sufficient coverage, least price, required security and more compatibility among the existing technologies then it is likely that the demands to support real-time applications such as streaming of voice, video and data supported over these networks will increase day-by-day. Particularly, the EDCF set of parameters defines the priorities of the admission control mechanism during the contention-based period (CP). This can subsequently be declined to a variation of network dynamicity. Reliability analysis of different traffic classes (video, voice and data), without considering both network topology and node’s mobility constraints, is not well appropriate. The organization of the paper is as follows: Section II first describes the background of IEEE 802.11 standard with service differentiation. Then there is a discussion that how IEEE802.11e (EDCF) is evolved from DCF. The section also elaborates the needs of mobility in recent era. Section III is comprised of a detailed discussion of three MAC-layer metrics on which this work has been done. Sections IV gives the description of the topology and scenarios which, we think, are the best suitable for our proposed work. Conclusion is given in section V and references are provided in section VI. In our last work [1], we proposed a scheduling algorithm aiming to improve QoS in the wireless networks. 2. BACKGROUND The service differentiation is one of the most wanted demands for the recent applications (with voice, video and data). So, IEEE 802.11 provided a mode of operation for the said demand. But it shows very poor performance regarding link utilization [2]. Several new mechanisms for service differentiation have been and being proposed [3], [4], [5]. The quality of traffics including video streaming is getting better performance because of being considered according to the characteristics of wireless networks and different sorts of service differentiation. 2.1 Legacy IEEE 802.11 MAC The standard WLAN IEEE 802.11 used Best-effort service model built on FIFO queuing mechanism. The access mode is based Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. MoMM2009, December 14–16, 2009, Kuala Lumpur, Malaysia. Copyright 2009 ACM 978-1-60558-659-5/09/0012...$10.00. khaled.dridi@etu.univ-paris12.fr nadeemjavaid@ieee.org daachi@univ-paris12.fr djouanik@tut.ac.za MoMM 2009 Full Papers Proceedings of MoMM2009 211