This Article 
   
 Share 
   
 Bibliographic References 
   
 Add to: 
 
Digg
Furl
Spurl
Blink
Simpy
Google
Del.icio.us
Y!MyWeb
 
 Search 
   
Performance Impact of Interlayer Dependence in Infrastructure WLANs
July 2006 (vol. 5 no. 7)
pp. 829-845
Widespread deployment of infrastructure WLANs has made Wi-Fi an integral part of today's Internet access technology. Despite its crucial role in affecting end-to-end performance, past research has focused on MAC protocol enhancement, analysis, and simulation-based performance evaluation without sufficient consideration for modeling inaccuracies stemming from interlayer dependencies, including physical layer diversity, that significantly impact performance. We take a fresh look at IEEE 802.11 WLANs and using experiment, simulation, and analysis demonstrate its surprisingly agile performance traits. Our findings are two-fold. First, contention-based MAC throughput degrades gracefully under congested conditions, enabled by physical layer channel diversity that reduces the effective level of MAC contention. In contrast, fairness degrades and jitter increases significantly at a critical offered load. This duality obviates the need for link layer flow control for throughput improvement. Second, TCP-over-WLAN achieves high throughput commensurate with that of wireline TCP under saturated conditions, challenging the widely held perception that TCP throughput fares poorly over WLANs when subject to heavy contention. We show that TCP-over-WLAN prowess is facilitated by the self-regulating actions of DCF and TCP feedback control that jointly drive the shared channel at an effective load of two to three wireless stations, even when the number of active stations is large. We show that the mitigating influence of TCP extends to unfairness and adverse impact of dynamic rate shifting under multiple access contention. We use experimentation and simulation in a complementary fashion, pointing out performance characteristics where they agree and differ.

[1] AiroPeek NX, WildPackets, Inc., http:/www.wildpackets.com/, 2004.
[2] http://www.enterasys.comwireless/, 2004.
[3] The Network Simulator— ns-2, http://www.isi.edu/nsnamns/, 2004.
[4] IEEE 802.11 Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Aug. 1999.
[5] N. Abramson, “The Aloha System— Another Alternative for Computer Communications,” Proc. Fall Joint Computer AFIPS Conf., pp. 281-285, 1970.
[6] D. Aguayo, J. Bicket, S. Biswas, G. Judd, and R. Morris, “Link-Level Measurements from an 802.11b Mesh Network,” Proc. ACM SIGCOMM '04 Conf., 2004.
[7] A. Balachandran, G. Voelker, P. Bahl, and P. Rangan, “Characterizing User Behavior and Network Performance in a Public Wireless LAN,” Proc. ACM SIGMETRICS '02 Conf., pp. 195-205, 2002.
[8] H. Balakrishnan, V. Padmanabhan, S. Seshan, and R. Katz, “A Comparison of Mechanisms for Improving TCP Performance over Wireless Links,” IEEE/ACM Trans. Networking, vol. 5, no. 6, pp. 756-769, 1997.
[9] G. Bianchi, “Performance Analysis of The IEEE 802.11 Distributed Coordination Function,” IEEE J. Selected Areas in Comm., vol. 18, no. 3, pp. 535-547, 2000.
[10] D. Boggs, J. Mogul, and C. Kent, “Measured Capacity of an Ethernet: Myths and Reality,” Proc. ACM SIGCOMM '88 Conf., pp. 222-234, 1988.
[11] F. Cali, M. Conti, and E. Gregori, “IEEE 802.11 Wireless LAN: Capacity Analysis and Protocol Enhancement,” Proc. IEEE INFOCOM '98 Conf., pp. 142-149, 1998.
[12] F. Cali, M. Conti, and E. Gregori, “IEEE 802.11 Protocol: Design and Performance Evaluation of an Adaptive Backoff Mechanism,” IEEE J. Selected Areas in Comm., vol. 18, no. 9, pp. 1774-1786, 2000.
[13] P. Chatzimisios, A.C. Boucouvalas, and V. Vitsas, “Performance Analysis of IEEE 802.11 DCF in Presence of Transmission Errors,” Proc. IEEE Int'l Conf. Comm., pp. 3854-3858, 2004.
[14] I. Cuinas and M. Sanchez, “Measuring, Modeling, and Characterizing of Indoor Radio Channel at 5.8 GHz,” IEEE Trans. Vehicular Technology, vol. 50, no. 2, pp. 526-535, 2001.
[15] M. Grossglauser and D. Tse, “Mobility Increases the Capacity of Ad-Hoc Wireless Networks,” Proc. IEEE INFOCOM '01 Conf., pp. 1360-1369, 2001.
[16] P. Gupta and P. Kumar, “The Capacity of Wireless Networks,” IEEE Trans. Information Theory, vol. 46, no. 2, pp. 388-404, 2000.
[17] W. Haitao, P. Yong, L. Keping, C. Shiduan, and M. Jian, “Performance of Reliable Transport Protocol over IEEE 802.11 Wireless LAN: Analysis and Enhancement,” Proc. IEEE INFOCOM '02 Conf., pp. 599-607, 2002.
[18] G. Holland, N. Vaidya, and P. Bahl, “A Rate-Adaptive MAC Protocol for Multihop Wireless Networks,” Proc. ACM MobiCom '01 Conf., 2001.
[19] V. Joel, “Exploding the Myth of WLAN Performance,” Telephony Online, Oct. 2004.
[20] H. Kim and J. Hou, “Improving Protocol Capacity with Model-Based Frame Scheduling in IEEE 802.11-Operated WLANs,” Proc. ACM MobiCom '03 Conf., pp. 190-204, 2003.
[21] S. Kjesbu and T. Brunsvik, “Radiowave Propagation in Industrial Environments,” Proc. 26th Ann. Conf. IEEE Industrial Electronics Soc., vol. 4, pp. 2425-2430, 2000.
[22] L. Kleinrock and F. Tobagi, “Packet Switching in Radio Channels: Part I— Carrier Sense Multiple-Access Modes and Their Throughput-Delay Characteristics,” IEEE Trans. Comm., vol. 23, no. 12, pp. 1400-1416, 1975.
[23] R. Knopp and P. Humblet, “Information Capacity and Power Control in Single-Cell Multiuser Communications,” Proc. Int'l Conf. Comm., 1995.
[24] A. Kochut, A. Vasan, A.U. Shankar, and A. Agrawala, “Sniffing Out the Correct Physical Layer Capture Model in 802.11b,” Proc. IEEE Int'l Conf. Network Protocols, 2004.
[25] D. Kotz and K. Essien, “Analysis of a Campus-Wide Wireless Network,” Proc. ACM MobiCom '02 Conf., pp. 107-118, 2002.
[26] U. Kozat and L. Tassiulas, “Throughput Capacity of Random Ad Hoc Networks with Infrastructure Support,” Proc. ACM MobiCom '03 Conf., pp. 55-65, 2003.
[27] B. Liu, Z. Liu, and D. Towsley, “On the Capacity of Hybrid Wireless Networks,” Proc. IEEE INFOCOM '03 Conf., pp. 1543-1552, 2003.
[28] S. Lu, T. Nandagopal, and V. Bharghavan, “A Wireless Fair Service Algorithm for Packet Cellular Networks,” Proc. ACM MobiCom '98 Conf., pp. 10-20, 1998.
[29] P. Mehra, A. Zakhor, and C. Vleeschouwer, “Receiver-Driven Bandwidth Sharing for TCP,” Proc. IEEE INFOCOM '03, 2003.
[30] R. Metcalfe and D. Boggs, “Ethernet: Distributed Packet Switching for Local Computer Networks,” Comm. ACM, vol. 19, no. 7, pp. 395-404, 1976.
[31] J. Padhye, V. Firoiu, D. Towsley, and J. Kurose, “Modeling TCP Throughput: A Simple Model and Its Empirical Validation,” Proc. ACM SIGCOMM '98 Conf., pp. 303-314, 1998.
[32] K. Park and W. Willinger, “Self-Similar Network Traffic: An Overview,” Self-Similar Network Traffic and Performance Evaluation, Wiley-Interscience, 2000.
[33] K. Pentikousis, “TCP in Wired-Cum-Wireless Environments,” IEEE Comm. Surveys, fourth quarter, no. 7, pp. 2-14, 2000.
[34] R. Rom and M. Sidi, Multiple Access Protocols: Performance and Analysis. Springer-Verlag, 1990.
[35] N. Spring, M. Chesire, M. Berryman, V. Sahasranaman, T. Anderson, and B. Bershad, “Receiver Based Management of Low Bandwidth Access Links,” Proc. IEEE INFOCOM '00 Conf., pp. 245-254, 2000.
[36] S. Sridhar, D. Hogenboom, and B. Willemsen, “Microwave Experiments on Chaotic Billiards,” J. Statistical Physics, vol. 68, no. 239, 1992.
[37] D. Tang and M. Baker, “Analysis of a Local-Area Wireless Network,” Proc. ACM MobiCom '00 Conf., pp. 1-10, 2000.
[38] R. Tingley and K. Pahlavan, “Space-Time Measurement of Indoor Radio Propagation,” IEEE Trans. Instrument Measurements, vol. 50, no. 1, pp. 22-31, 2001.
[39] D. Tse, “Optimal Power Allocation over Parallel Gaussian Channels,” Proc. Int'l Symp. Information Theory, 1997.
[40] N. Vaidya, P. Bahl, and S. Gupta, “Distributed Fair Scheduling in a Wireless LAN,” Proc. ACM MobiCom '00 Conf., pp. 167-178, 2000.
[41] A. Vasan and U. Shankar, “An Empirical Characterization of Instantaneous Throughput in 802.11b WLANs,” Technical Report CS-TR-4389, UMIACS-TR-2002-69, Dept. of Computer Science and UMIACS, Univ. of Maryland, College Park, 2002.
[42] G. Xylomenos and G. Polyzos, “TCP and UDP Performance over a Wireless LAN,” Proc. IEEE INFOCOM '99 Conf., pp. 439-446, 1999.
[43] G. Xylomenos, G. Polyzos, P. Mähönen, and M. Saaranen, “TCP Performance Issues over Wireless Links,” IEEE Comm. Magazine, vol. 39, no. 4, pp. 52-58, 2001.
[44] C. Yuen and P. Marbach, “Service Differentiation in Random Access Networks,” Technical Report CSRG-472, Computer System Research Group, Univ. of Toronto, July 2003.

Index Terms:
Wireless communication, access schemes, physical layer diversity, TCP-over-WLAN performance, experimentation versus simulation.
Citation:
Sunwoong Choi, Kihong Park, Chong-kwon Kim, "Performance Impact of Interlayer Dependence in Infrastructure WLANs," IEEE Transactions on Mobile Computing, vol. 5, no. 7, pp. 829-845, July 2006, doi:10.1109/TMC.2006.102
Usage of this product signifies your acceptance of the Terms of Use.