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Performance Enhancement of Multirate IEEE 802.11 WLANs with Geographically Scattered Stations
July 2006 (vol. 5 no. 7)
pp. 906-919
In today's IEEE 802.11 Wireless LANs (WLANs), e.g., the popular IEEE 802.11b, stations support multiple transmission rates, and use them adaptively depending on the underlying channel condition via link adaptation. It has been known that when some stations use low transmission rates due to bad channel conditions, the performance of the stations using high rates is heavily degraded, and this phenomenon is often referred to as performance anomaly. In this paper, we model the WLAN incorporating stations with multiple transmission rates in order to demonstrate the performance anomaly analytically. Note that all the previously proposed models of the IEEE 802.11 assume a single transmission rate. We also develop possible remedies to improve the performance. Our solution is basically to control the access parameters such as the initial backoff window, the frame size, and the maximum backoff stage, depending on the employed transmission rate. Throughout simulations, we demonstrate that our analytical model is accurate, and the proposed mechanism can indeed provide the remedies to the performance anomaly by increasing the aggregate throughput up to six times.

[1] IEEE 802.11, Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Aug. 1999.
[2] P.S. Henry and H. Luo, “WiFi: What's Next?” IEEE Comm. Magazine, vol. 40, no. 12, pp. 66-72, Dec. 2002.
[3] IEEE 802.11b, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications: High-Speed Physical Layer Extension in the 2.4GHz Band, Supplement to IEEE 802.11 Standard, Sept. 1999.
[4] IEEE 802.11a, Part 11: Wireless LAN, Medium Access Control (MAC) and Physical Layer (PHY) Specifications: High-Speed Physical Layer in the 5GHz Band, Supplement to IEEE 802.11 Standard, Sept. 1999.
[5] D. Qiao and S. Choi, “Goodput Enhancement of IEEE 802.11a Wireless LAN via Link Adaptation,” Proc. IEEE Int'l Conf. Comm., pp. 1995-2000, June 2001.
[6] D. Qiao, S. Choi, and K.G. Shin, “Goodput Analysis and Link Adaptation for IEEE 802.11a Wireless LANs,” IEEE Trans. Mobile Computing, vol. 1, no. 4, pp. 278-292, 2002.
[7] J. del P. Pavon and S. Choi, “Link Adaptation Strategy for IEEE 802.11 WLAN via Received Signal Strength Measurement,” Proc. IEEE Int'l Conf. Comm., vol. 2, pp. 1108-1113, May 2003.
[8] M. Portoles, Z. Zhong, and S. Choi, “IEEE 802.11 Downlink Traffic Shaping Scheme for Multi-User Service Enhancement,” Proc. IEEE Ann. IEEE Int'l Symp. Personal Indoor and Mobile Radio Comm., Sept. 2003.
[9] J.-L.C. Wu, H.-H. Liu, and Y.-J. Lung, “An Adaptive Multirate IEEE 802.11 Wireless LAN,” Proc. Int'l Conf. Information Networking, pp. 411-418, 2001.
[10] G. Holland, N. Vaidya, and P. Bahl, “A Rate-Adaptive MAC Protocol for Multi-Hop Wireless Networks,” Proc. ACM SIGMOBILE Conf., pp. 236-251, July 2001.
[11] A. Kamerman and L. Monteban, “WaveLAN-II: A High-Performance Wireless LAN for the Unlicensed Band,” Bell Labs Technical J., pp. 118-133, Summer 1997.
[12] M. Heusse, F. Rousseu, G. Berger-Sabbatel, and A. Duda, “Performance Anomaly of 802.11b,” Proc. IEEE INFOCOM Conf., vol. 2, pp. 836-843, Mar. 2003.
[13] G. Bianchi, “IEEE 802.11— Saturation Throughput Analysis,” IEEE Comm. Letters, vol. 2, no. 12, pp. 318-320, Dec. 1998.
[14] G. Bianchi, “Performance Analysis of the IEEE 802.11 Distributed Coordinated Function,” IEEE J. Selected Areas Comm. (JSAC), vol. 18, no. 3, pp. 535-547, Mar. 2000.
[15] Y. Xiao and J. Rosdahl, “Throughput and Delay Limits of IEEE 802.11,” IEEE Comm. Letters, vol. 6, no. 8, pp. 355-357, Aug. 2002.
[16] F. Cali, M. Conti, and E. Gregori, “IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement,” Proc. IEEE INFOCOM Conf., vol. 1, pp. 142-149, Apr. 1998.
[17] S. Garg, M. Kappes, and A.S. Krishnakumar, “On the Effect of Contention-Window Sizes in IEEE 802.11b Networks,” technical report, Avaya Labs Research, June 2002.
[18] S. Khurana, A. Kahol, S.K. S. Gupta, and P.K. Srimani, “Performance Evaluation of Distributed Co-Ordination Function for IEEE 802.11 Wireless LAN Protocol in Presence of Mobile and Hidden Terminals,” Proc. IEEE Int'l Symp. Modeling, Analysis, and Simulation of Computer and Telecomm. Systems, pp. 40-47, 1999.
[19] M. Youssef, A. Vasan, and R. Miller, “Specification and Analysis of the DCF and PCF Protocols in the 802.11 Standard Using Systems of Communicating Machines,” Proc. IEEE Workshop Secure Network Protocols, pp. 132-141, Nov. 2002.
[20] H. Wu, Y. Peng, K. Long, and S. Cheng, “A Simple Model of IEEE 802.11 Wireless LAN,” Proc. Conf. Information Cultures and Information Interests, vol. 2, pp. 514-519, Nov. 2001.
[21] Y. Xiao, “Backoff-Based Priority Schemes for IEEE 802.11,” Proc. IEEE Int'l Conf. Comm., 2003, vol. 3, pp. 1568-1572, May 2003.
[22] Y. Xiao, “A Simple and Effective Priority Scheme for IEEE 802.11,” IEEE Comm. Letters, vol. 7, no. 2, pp. 70-72, Feb. 2003.
[23] E. Ziouva and T. Antonakopoulos, “CSMA/CA Performance under High Traffic Conditions: Throughput and Delay Analysis,” Computer Comm., vol. 25, pp. 313-321, 2002.
[24] M.S. Gast, 802.11 Wireless Networks: the Definitive Guide. O'Reilly, 2002.
[25] OPNET, Inc., http:/, 2005.
[26] Y. Xiao, “An Analysis for Differentiated Services in IEEE 802.11 and IEEE 802.11e Wireless LANs,” Proc. IEEE Int'l Conf. Distributed Computing Systems, Mar. 2004.
[27] J. del P. Pavon and S. Shankar, “Impact of Frame Size, Number of Stations and Mobility on the Throughput Performance of IEEE 802. 11e,” Proc. IEEE Wireless Comm. and Networking Conf., Mar. 2004.
[28] IEEE 802.11e, Part 11: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications: Medium Access Control (MAC) Enhancements for Quality of Service (QoS), Supplement to IEEE 802.11 Standard, Nov. 2005.
[29] I. Tinnirello and S. Choi, “Temporal Fairness Provisioning in Multi-Rate Contention-Based 802.11e WLANs,” Proc. IEEE Int'l Symp. a World of Wireless, Mobile and Multimedia Networks, June 2005.

Index Terms:
Backoff algorithm, CSMA/CA, DCF, IEEE 802.11a/b/g, link adaptation, performance anomaly, throughput.
Duck-Yong Yang, Tae-Jin Lee, Kyunghun Jang, Jin-Bong Chang, Sunghyun Choi, "Performance Enhancement of Multirate IEEE 802.11 WLANs with Geographically Scattered Stations," IEEE Transactions on Mobile Computing, vol. 5, no. 7, pp. 906-919, July 2006, doi:10.1109/TMC.2006.101
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