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Journal of the Brazilian Computer Society

Print version ISSN 0104-6500On-line version ISSN 1678-4804

J. Braz. Comp. Soc. vol.9 no.1 Campinas Nov. 2003 

Full text available only in PDF format


Quality of service in Ad Hoc 802.11 networks



Marcelo G. RubinsteinI; José Ferreira de RezendeII

IDepto. de Eng. Eletronica e Telecomunicacões, Universidade do Estado do Rio de Janeiro, FEN - Rua São Francisco Xavier, 524 - 20550-013, Rio de Janeiro - RJ - Brazil,
IIGrupo de Teleinformática e Automação, Universidade Federal do Rio de Janeiro, PEE-COPPE - CP 68504 - 21945-970, Rio de Janeiro - RJ - Brazil,




This paper presents major quality of service problems in IEEE 802.11 networks. It analyzes unfairness in bandwidth sharing and TCP instability in MAC 802.11. Moreover, differentiation techniques for providing medium access priority are evaluated. Simulation results show that the ad hoc routing protocol has a great influence on unfairness and on the TCP throughput instability due to succeeding routing failures originated by the MAC sublayer. Differentiation mechanism results show that DIFS-based schemes can provide a fine-grained throughput differentiation compared to backoff-based ones. Nevertheless, backoff-based schemes are more effective in providing latency differentiation, which is important for real-time traffic.

Keywords: Ad hoc networks, IEEE 802.11. Quality of Service




[1] I. Aad and C. Castelluccia. Differentiation mechanisms for IEEE 802.11. In Infocom'2001, Anchorage, Alaska, April 2001.        [ Links ]

[2] I. Aad and C. Castelluccia. Remarks on per-flow differentiation in IEEE 802.11. In Proceedings of the European Wireless, Florence, Italy, February 2002.        [ Links ]

[3] Brahim Bensaou, Yu Wang, and Chi Chung Ko. Fair medium access in 802.11 based wireless ad-hoc networks. In IEEE/ACM The First Annual Workshop on Mobile Ad Hoc Networking & Computing (MobiHoc), Boston, USA, August 2000.        [ Links ]

[4] Josh Broch, David A. Maltz, David B. Johnson, Yih-Chun Hu, and Jorjeta Jetcheva. A performance comparison of multi-hop wireless ad hoc network routing protocols. In ACM The Forth Annual Conference on Mobile Computing and Networking (MobiCom), Dallas, USA, October 1998.        [ Links ]

[5] Carlos de M. Cordeiro, Samir R. Das, and Dharma P. Agrawal. COPAS: Dynamic contention-balancing to enhance the performance of TCP over multi-hop wireless networks. In The 11th International Conference on Computer Communications and Networks (IC3N), Miami, USA, October 2002.        [ Links ]

[6] Kevin Fall and Kannan Varadhan. The NS Manual. Technical report, The VINT Project, January 2002.        [ Links ]

[7] Tom Goff, Nael Abu-Ghazaleh, Dhananjay Phatak, and Ridvan Kahvecioglui. Preemptive routing in ad hoc networks. Journal of Parallel and Distributed Computing, 63(2):123-140, February 2003.        [ Links ]

[8] Daqing Gu and Jinyun Zhang. QoS enhancement in IEEE 802.11 wireless local area networks. IEEE Communications Magazine, 41(6):120-124, June 2003.        [ Links ]

[9] V. Kanodia, C. Li, A. Sabharwal, B. Sadeghi, and E. Knightly. Distributed multi-hop scheduling and medium access with delay and throughput constraints. In ACM The Seventh Annual Conference on Mobile Computing and Networking (MobiCom), Rome, Italy, July 2001.        [ Links ]

[10] Vikram Kanodia, Chengzhi Li, Ashutosh Sabharwal, Bahareh Sadeghi, and Edward Knightly. Distributed priority scheduling and medium access in ad hoc networks. Wireless Networks, 8(5):455-466, September 2002.        [ Links ]

[11] Institute of Electrical and Eletronics Engineers. Wireless LAN medium access control (MAC) and physical layer (PHY) specifications. IEEE Standard 802.11, 1999.        [ Links ]

[12] Institute of Electrical and Eletronics Engineers. Wireless LAN medium access control (MAC) and physical layer (PHY) specifications: High-speed physical layer in the 5 GHz band. IEEE Standard 802.11a, 1999.        [ Links ]

[13] Institute of Electrical and Eletronics Engineers. Wireless LAN medium access control (MAC) and physical layer (PHY) specifications: Higher-speed physical layer extension in the 2.4 GHz band. IEEE Standard 802.11b, 1999.        [ Links ]

[14] Institute of Electrical and Eletronics Engineers. Medium access control (MAC) enhancements for quality of service (QoS). IEEE Draft for Standard 802.11e/D3.2, March 2002.        [ Links ]

[15] Charles Perkins and Pravin Bhagwat. Highly dynamic destination-sequenced distance-vector routing (DSDV) for mobile computers. In ACM SIGCOMM'94 Conference on Communications Architectures, Protocols and Applications, pages 234-244, 1994.        [ Links ]

[16] J. Schiller. Mobile Communications. Addison-Wesley, 1st edition, 2000. ISBN 0201398362.        [ Links ]

[17] Ken Tang and Mario Gerla. Fair sharing of MAC under TCP in wireless ad hoc networks. In IEEE Multiaccess, Mobility and Teletraffic for Personal Communications (MMT'99), Venice, Italy, October 1999.        [ Links ]

[18] Nitin H. Vaidya, Paramvir Bahl, and Seema Gupta. Distributed fair scheduling in a wireless LAN. In ACM The Sixth Annual Conference on Mobile Computing and Networking (MobiCom), Boston, EUA, August 2000.        [ Links ]

[19] Yu Wang and Brahim Bensaou. Achieving fairness in IEEE 802.11 DFWMAC with variable packet lengths. In IEEE Global Telecommunications Conference (Globecom), Texas, USA, November 2001.        [ Links ]

[20] Kaixin Xu, Sang Bae, Sungwook Lee, and Mario Gerla. TCP behavior across multihop wireless networks and the wired internet. In Proceedings of the 5th ACM International Workshop on Wireless Mobile Multimedia, pages 41-48, Georgia, USA, September 2002.        [ Links ]

[21] Shugong Xu and Tarek Saadawi. Does the IEEE 802.11 MAC protocol work well in multihop wireless ad hoc networks? IEEE Communications Magazine, 39(6):130-137, June 2001.        [ Links ]

[22] Shugong Xu and Tarek Saadawi. Revealing the problems with 802.11 medium access control protocol in muilti-hop wireless ad hoc networks. Computer Networks, 38(4):531-548, March 2002.        [ Links ]

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