Performance Issues with General Packet Radio Service

  • 발행 : 2002.12.01

초록

The General Packet Radio Service (GPRS) is being deployed by GSM network operators world-wide, and promises to provide users with “always-on” data access at bandwidths comparable to that of conventional fixed-wire telephone modems. However, many users have found the reality to be rather different, experiencing very disappointing performance when, for example, browsing the web over GPRS. In this paper, we examine the causes, and show how unfortunate interactions between the GPRS link characteristics and TCP/IP protocols lead to poor performance. A performance characterization of the GPRS link-layer is presented, determined through extensive measurements taken over production networks. We present measurements of packet loss rates, bandwidth availability, link stability, and round-trip time. The effect these characteristics have on TCP behavior are examined, demonstrating how they can result in poor link utilization, excessive packet queueing, and slow recovery from packet losses. Further, we show that the HTTP protocol can compound these issues, leading to dire WWW performance. We go on to show how the use of a transparent proxy interposed near the wired-wireless border can be used to alleviate many of these performance issues without requiring changes to either client or server end systems.

키워드

참고문헌

  1. G. Brasche and B. Walke, 'Concepts, services and protocols of the new GSM phase 2+ general packet radio service,' IEEE Commun. Mag., Aug. 1997
  2. M. Meyer, 'TCP performance over GPRS,' in Proc. IEEE WCNC, pp.1248-1252, 1999
  3. H. Balakrishnan et al.'A comparison of mechanisms for improving TCP performance over wireless links,' IEEE/ACM Trans. Networking, vol. 5, no.6, Dec. 1997
  4. E. Amir and H. Balakrishnan, 'An evaluation of the Metricom Ricochet wireless network,' CS 294-7 Class Project, UC Berkeley, available at http://www.lariat.org/Berkeley/paper.html
  5. P. Sinha et al.,'WTCP: A reliable transport protocol for wireless wide-area networks,' in Proc. ACM M0BIC0M'99, 1999
  6. J-H. Park, 'Wireless internet access for mobile subscribers based on the GPRS/UMTS network,' IEEE Commun. Mag., Apr. 2002
  7. R. Ludwig et al., 'Multi-layer tracing of TCP over a reliable wireless link,' in Proc. ACM SIGMETRICS, 1999
  8. J. C. Mogul et al. 'Potential benefits of delta encoding and data compres-sion for HTTP,' in Proc. ACM SIGCOMM, Cannes, France, Sept. 1997. pp. 181-194
  9. An Introduction to the Vodafone GPRS Environment and Supported Ser-vices, Issue 1.1/1200, Dec. 2000, Vodafone Ltd., 2000
  10. B. Walke, Mobile Radio Networks, Networking, and Protocols (2. Ed.). John Wiley & Sons, Chichester 2001
  11. C. Bettssetter, H. Vogel, and J. Eberspacher, 'GSM phase 2+ general packet radio service GPRS: Architecture, Protocols, and air interface,' IEEE Commun. surveys Third Quater 1999, vol. 2 no. 3
  12. P. Stuckmann, 'Quality of service management in GPRS-based radio ac-cess networks,' Telecommun. Systems, Kluwer Academic Publishers, 19:3,4, pp.515-546, 2002 https://doi.org/10.1023/A:1013811026373
  13. P. Stuckmann, N. Ehlers, and B. Wouters, 'GPRS traffic performance mea-surements,' in Proc. IEEE Veh. TechnoI. Conf. (Fall VTC 2002), Vancou-ver, Canada, Sept. 2002
  14. A. Gurtov et al.,'Multi-layer protocol tracing in a GPRS network,' in Proc. IEEE Veh. Technol. Conf. (Fall VTC2002), Vancouver, Canada, Sept 2002
  15. tcpdump(Available at http://www.tcpdump.org),tcptrace(Available at http://www.tcptrace.org),ttcp+(Available at http://www.cl.cam.ac.uk/Research/SRG/netos/netx/)
  16. R. Chakravorty, J. Cartwright, and I. Pratt, 'Practical experience With TCP over GPRS,' in Proc. IEEE GL0BEC0M'2002, Taipei, Taiwan, Nov. 2002, available at http://www.cl.cam.ac.uk/users/rc277/gprs.html
  17. R. Chakravorty and I. Pratt, "WWW performance over GPRS,' in Proc. IEEE Int. Conf. Mobile and Wireless Commun. Networks (IEEE MWCN 2002), Stockholm, Sweden, Sept. 2002, available at hap://www.cl.cam.ac.uk/users/rc277/gprs.html
  18. J. Cartwright, GPRS Link Characterization, available at http://www.cl.cam.ac.uk/users/rc277/linkchar.html
  19. M. Mathis et al., 'TCP selective acknowledgement options,' Request for Comments (RFC) - 2018, Apr. 1996
  20. L. Zhang, S. Shenker, and D. Clark, 'Observations on the dynamics of a congestion control algorithm: The effects of two-way traffic,' in Proc ACM SIGC0MM'91, 1991
  21. D. Dutta and Y. Zhang, 'An active proxy based architecture for TCP in heterogeneous variable bandwidth networks,' in Proc. IEEE GLOBE-C0M'2001,Nov.2001
  22. Z. Wang and P. Cao, 'Persistent connection behaviour of popu-lar browsers,' available at http://www.cs.wisc.edu/cao/papers/persistent-connection.html
  23. J. C. Mogul, 'Support for out-of-order responses in HTTP,' internet Draft, Network Working Group, 6 Apr. 2001
  24. F. Donelson Smith et al., 'What TCP/IP protocol headers can tell us about the web,' in Proc. ACM SIGMETRICS, 1999
  25. V. N. Padmanabhan and J. C. Mogul, 'Improving HTTP latency,' Com-outer Networks and ISDN Systems, vol. 28, pp. 25-35, 1995 https://doi.org/10.1016/0169-7552(95)00106-1
  26. H. Nielsen et al., 'Network performance effects of HTTP/l.l CSSl, and PNG,' in Proc. ACM SIGCOMM, Cannes, France, Sept. 1997
  27. Opera web browser, available at http://www.opera.com
  28. Mozilla web browser, available at http://www.mozilla.org
  29. B. Knutsson and L. Peterson, 'Transparent TCP proxy signalling,' J. Com-mun. and Networks (JCN). Mar. 2001
  30. R. Chakravorty, S. Katti, J. Crowcroft and I. Pratt, 'Flow aggregation for enhanced TCP over wide-area wireless,' in Proc. IEEE INFOCOM'2003, available at http://www.cl.cam.ac.uk/users/rc277/gprs.html
  31. George Xylomenos et al., 'TCP performance issues over wireless links,' IEEE Commun. Mag., Apr. 2001
  32. T. Alanko et al., 'Measured performance of data transmission over cellular telephone networks,' in ACM Computer Commun. Review, 24:5, 1995
  33. J. Korhonen et al., 'Measured Performance of GSM HSCSD and GPRS,' in Proc IEEE ICC'2001 2001
  34. H. Balakrishnan, R. Katz, and S. Seshan, 'Improving TCP/IP performance over wireless networks,' in Proc.ACM M0BIC0M'95, Nov. 1995
  35. V. Bakshi et al.,'Improving performance of TCP over wireless networks,' Texas A&M Univ. Tech. Report TR-96-014, May 1996
  36. A. Bakre and B. R. Badrinath, 'I-TCP: Indirect TCP for mobile hosts,' in Proc. 15th IEEEICDCS, pp. 136-143, Vancouver, BC, May 1995
  37. K. Ratnam and I. Matta, 'W-TCP: An efficient transmission control pro-tocol for networks with wireless links,' in Proc. IEEE ISCC'98, 1998
  38. T. Go et al.,'Freeze-TCP: A true end-to-end enhancement mechanism for mobile environments,' in Proc. JEEE INFOCOM'2000, Israel, 2000
  39. J. Hu and K. L. Yeung, 'FDA: A novel base station flow control scheme for TCP over heterogeneous networks,' in Proc. IEEE INF0C0M'2001, 2001
  40. K. Brown and S. Singh, 'M-TCP: TCP for mobile cellular networks,' Computer Commun. Review, 1997
  41. T. B. Fleming, S. F. Midkiff, and N. J. Davis, 'Improving the performance of the world wide web over wireless networks,' in Proc. IEEE GLOBE-COM'97, 1997
  42. H. Balakrishnan and R. H. Katz, 'Explicit loss notification and wireless web performance' in Proc.IEEE GLOBECOM Internet Mini-Conf., Sydney, Australia, Nov. 1998
  43. M. Liljeberg et al.,'M0WGLI WWW software: Improved usability of WWW in mobile WAN environments,' IEEE Global Internet, Nov. 1996
  44. Firsthop GPRS accelerator, available at http://www.firsthop.com/
  45. The squid proxy cache homepage, available at http://www.squid-cache.org