Experimental evaluation of TCP performance and fairness in an 802.11e test-bed

In this paper we present measurements made using an 802.11e wireless testbed. We demonstrate experimentally how the new 802.11e [1] QoS parameters behave in our testbed. We describe the testing methodology used to validate the operation of the 802.11e TXOP, AIFS and CWmin parameters and compare the experimental results to existing analytical models. We also discuss a number of practical issues encountered during our measurements. We then use the testbed to demonstrate some known problems with TCP's performance caused by cross-layer interaction between the TCP congestion control algorithm and the MAC layer CSMA/CA contention mechanism. Finally, we study how these problems can be mitigated using the flexibility provided by the 802.11e parameters via the scheme suggested in [2].

[1]  Roberto Battiti,et al.  Supporting service differentiation with enhancements of the IEEE 802.11 MAC protocol: Models and analysis , 2007, Science in China Series F: Information Sciences.

[2]  Marco Mellia,et al.  Measuring TCP over WiFi: A Real Case , 2005 .

[3]  Stefano Salsano,et al.  TCP Fairness Issues in IEEE 802 . 11 Based Access Networks , 2003 .

[4]  A. Girotra,et al.  Performance Analysis of the IEEE 802 . 11 Distributed Coordination Function , 2005 .

[5]  H. Balakrishnan,et al.  How network asymmetry affects TCP , 2001, IEEE Communications Magazine.

[6]  Héctor L. Velayos Munoz,et al.  Performance measurements of the saturation throughput in IEEE 802.11 access points , 2005, Third International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt'05).

[7]  Haitao Wu,et al.  Performance of reliable transport protocol over IEEE 802.11 wireless LAN: analysis and enhancement , 2002, Proceedings.Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies.

[8]  Prasun Sinha,et al.  Understanding TCP fairness over wireless LAN , 2003, IEEE INFOCOM 2003. Twenty-second Annual Joint Conference of the IEEE Computer and Communications Societies (IEEE Cat. No.03CH37428).

[9]  Douglas J. Leith,et al.  Using the 802.11e EDCF to achieve TCP upload fairness over WLAN links , 2005, Third International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt'05).