한국정보과학회논문지:정보통신 (Journal of KIISE:Information Networking)

한국정보과학회 (Korean Institute of Information Scientists and Engineers)
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무선 링크에서의 TCP 성능 평가

Performance Evaluation of TCP over Wireless Links

  • 박진영 (LG정보통신 차세대통신연구소) ;
  • 채기준 (이화여자대학교 컴퓨터학과)
  • 발행 : 2000.06.30
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⟨ 이전 논문 다음 논문 ⟩

초록

현재 가장 널리 쓰이는 수송계층 프로토콜인 TCP는 패킷 손실이 망의 혼잡 때문에 발생하는 기존의 망들에 적합하도록 되어 있다. TCP는 망의 패킷 에러율이 낮다는 가정 하에 종단간 신뢰성 있는 패킷 전송을 수행한다. 그러나 무선 링크가 있는 망에서는 높은 에러율과 핸드오프에 의한 패킷 손실이 발생하게 된다. TCP는 이런 경우에 발생되는 모든 패킷 유실에 대해서 혼잡 제어와 회피 알고리즘을 작동시키게 된다. 따라서 무선 링크에서의 높은 에러율에 의해 TCP의 불필요한 혼잡제어 알고리즘이 작동되고 망의 대역폭을 비효율적으로 사용하게 하여 무선 환경과 연결된 망에서의 종단간 성능을 저하시키게 된다. 이러한 무선 링크에서의 TCP 성능 향상을 위한 많은 방안들이 연구되고 있다. 본 논문에서는 무선 링크에서의 TCP 성능 향상을 위한 기존의 기법들을 비교 분석하고 각 방법의 성능을 평가하여 유무선 링크가 연결된 망에서 TCP의 성능 향상에 적합한 모델을 제시하고자 한다. 이는 기지국에서의 캐쉬 기법과 함께 TCP 종단간 SACK 옵션에 의한 수신자 정보를 사용하는 방법으로 시뮬레이션을 통하여 제시한 모델의 유효 처리율이 타 방식에 비해 향상되었고 무선 링크로의 중복된 재전송의 비율이 줄었음을 알 수 있었다.

Nowadays, most widely used transport protocol, TCP is tuned to perform well in traditional networks where packet losses occur mostly because of congestion. TCP performs reliable end-to-end packet transmission under the assumption of low packet error rate. However, networks with wireless links suffer from significant losses due to high error rate and handoffs. TCP responds to all losses by invoking congestion control and avoidance algorithms, resulting in inefficient use of network bandwidth and degraded end-to-end performance in that system. To solve this problem, several methods have been proposed. In this paper, we analyse and compare these methods and propose appropriate model for improving TCP performance in the network with wireless links. This model uses TCP selective acknowledgement (SACK) option between TCP ends, and also uses caching method at the base station. Our simulation results show that using TCP SACK option with base station caching significantly reduces unnecessary duplicate retransmissions and recover packet losses effectively.

키워드

참고문헌

  1. V. Jacobson, 'Congestion Avoidance and Control,' in Proc. SIGCOMM '88, ACM, USA, pp. 314-329, 1988 https://doi.org/10.1145/52324.52356
  2. W. R. Stevens, 'TCP Slow Start, Congestion A voidance, Fast Retransmission, and Fast Recovery Algorithms,' IETF, RFC 2001, Jan. 1997
  3. E.Arnir et al. 'Efficient TCP over networks with wireless links,' in Proc. HotOS- V, May 1995 https://doi.org/10.1109/HOTOS.1995.513451
  4. A. Bakre and B. R Badrinath, 'I-TCP: Indirect TCP for Mobile Hosts,' In Proc. 15th International Conf on Distributed Computing Systems (ICDCS), May 1995 https://doi.org/10.1109/ICDCS.1995.500012
  5. H. Balakrishnan, S. Seshan, and R.H. Katz, 'Improving Reliable Transport and Handoff Performance in Cellular Wireless Networks,' ACM Wireless Networks, 1(4), Dec. 1995 https://doi.org/10.1007/BF01985757
  6. H. Balakrishnan, V. N. Padrnanabhan, S. Seshan, R H. Katz, 'A Comparison of Mechanisms for Improving TCP performance over Wireless Links,' IEEE/ACM Transactions on Networking, Dec. 1997 https://doi.org/10.1109/90.650137
  7. R. Goyal, R Jain, S. Kalyanaraman, 'TCP Selective Acknowledgments and UBR Drop Policies to Improve ATM - UBR Performance over Terrestrial and Satellite Networks,' in Proc. ICCCN97, Sep. 1997 https://doi.org/10.1109/ICCCN.1997.623286
  8. V. Jacobson, R. Braden, D. Broman, 'TCP Extensions for High Performance,' RFC 1323, May 1992
  9. Luigi Rizzo, 'Issues in the implementation of selective acknowledgements for TCP,' Draft, Jan. 1996
  10. 'Experimental TCP Selective Acknowledgment Implementations,' Pittsburgh Supercomputing Center (PSC), http://www.psc.edu/networking/aIL sack.html
  11. A DeSimone et al., 'Throughput perfonnance of transport-layer protocols over wireless LANs,' in Proc. IEEE GLOBECOM '93, pp. 542-549, 1993 https://doi.org/10.1109/GLOCOM.1993.318140
  12. W. C. Jakes, Jr., 'Microwave mobile communications,' John Wiley & Sons, 1974
  13. M. Zorzi et al., 'On the accuracy of a first-order markov model for data transmission on fading channels,' in Proc. ICUPC '95, 1995 https://doi.org/10.1109/ICUPC.1995.496890
  14. H. S. Wang, 'On verifying the first-order markovian assumption for a rayleigh fading channel model,' in Proc. ICUPC '94, pp. 160-164, 1994 https://doi.org/10.1109/ICUPC.1994.383065
  15. 전병곤, 이병기, 'PCN 환경에서의 TCP 성능 분석', 한국통신학회 논문지, 제 23권 2호, 1998. 2
  16. John G. Proakis, 'Digital Communications,' Third Edition, McGRAW-HILL, 1995
  17. Young Yong Kim, San-qi Li, 'Modeling Fast Fading Channel Dynamics for Packet Data Perfonnance Analysis,' in Proc. IEEE INFO COM '98, pp. 1292-1300, 1998 https://doi.org/10.1109/INFCOM.1998.662944
  18. K Y. Wang, S. K Tripathi, 'Mobile-End Transport Protocol: An Alternative to TCP/IP Over Wireless Links,' in Proc. IEEE INFOCOM '98, pp. 1046-1053, 1998 https://doi.org/10.1109/INFCOM.1998.662914
  19. A. Romanow and S. Floyd, 'Dynamics of TCP Traffic over ATM Networks,' IEEE Journal on Selected Areas in Communications, Vol. 13, no.4, May 1995 https://doi.org/10.1109/49.382154
  20. S. Keshav, S. Morgan, 'SMART Retransimssion: Performnance with Overload and Random Losses,' in Proc. INFOCOM '97, 1997 https://doi.org/10.1109/INFCOM.1997.631134
  21. William Stallings, 'High-Speed Networks: TCP/IP and ATM design principles,' 1998
  22. P. Johansson, E. Wedlund, J. M. Karlsson, 'Interaction Between TCP Flow Control and ABR Rate Control,' Proceedings of IEEE ATM '97, 1997 https://doi.org/10.1109/ATM.1997.624714
  23. M. Mathis, J. Madhavi, S. Floyd, A. Romanow, 'TCP Selective Acknowledgment Options,' IETF, RFC 2018, Oct. 1996
  24. W. Richard Stevens, 'TCP/IP Illustrated, Volume 1 : The Protocols,' Addison-Wesley, Dec. 1993
  25. Gary R. Wright, W. Richard Stevens, 'TCP/IP Illustrated Volume 2 The Implementation,' Addison-Wesley, Jan. 1995
  26. Fall K, Floyd S., 'Comparisons of Tahoe, Reno, and Sack TCP,' ftp://ftp.ee.lbl.gov/papers/sacks.ps.Z, Dec. 1995
  27. Floyd S., 'Issues of TCP with SACK,' ftp// ftp.ee.lbl.gov/papers/issues_sa.ps.Z, Jan. 1996.
  28. Jacobson, V. , R. Braden, 'TCP Extensions for Long-Delay Paths,' IETF, RFC 1072, Oct. 1988
  29. Postel, J., 'Transmission Control Protocol - DARPA Internet Program Protocol Specification,' IETF, RFC 793, DARPA, Sep.1981
  30. Ramon Caceres, Liviu Iftode,'Improving the Performance of Reliable Transport Protocols in Mobile Computing Environments,' IEEE Journal on Selected Areas in Communications, June. 1996 https://doi.org/10.1109/49.391749
  31. DCB/LBNL Network Simulator: ns-v.2.0, http://www-mash.cs.berkeley.edu/ns