无线局域网中基于DCF的QoS改善方法
摘要
在有线网络中，许多业务，如语音、视频业务等，有严格的端到端服务质量要求，包括时延、带宽、丢包率等等。随着光纤技术日新月异的发展，主干网上的带宽变得越来越大，而作为接入部分的无线网络带宽资源相对较小。这样，无线接入部分就成为整个网络中端到端连接服务质量的瓶颈。因此，如何在无线通信系统上向用户业务提供服务质量保证成为关键的问题。目前，个人移动通信系统的发展为终端移动性提供了很好的支持，无线局域网也为终端提供了带宽更宽的无线接入手段，但是在向用户业务提供服务质量保证方面，现有工作仍显不足。此外，移动IP作为无线网络体系结构中的核心网络业务承载协议将各种无线通信系统结合起来，也是无线网络体系结构一个有前景的发展方向。
服务质量作为人们对网络提供服务的满意程度，自从被提出至今，经历了综合业务模型，差分业务模型和多协议标记交换等阶段。在此基础上，我们研究了无线局域网中的服务质量策略，在对基于IEEE 802.11的无线局域网进行了充分了解的基础上，提出了在无线局域网DCF方式下发送较大MSDU[2]（MAC层服务数据单元）时会遇到的问题，指出当把MSDU分片[2]成为一组MPDU（MAC层协议数据单元）进行发送时，随着MPDUs的不断发送，排序靠后的MPDU将对整个MSDU的发送时间产生决定性影响。因此有必要不断提高MPDU的发送优先级，从而确保MSDU的发送可靠性和延时。提高优先级的方法采用减小DCF中的和DIFS，分别采用阶跃的、线性的和指数的不同方法实现。通过仿真分析，证实了此方法的可行性，并且能够有效减小数据单元的发送时间。
随着IP技术的不断发展，在移动IP中有关服务质量的问题也成为热点。本文还比较了在移动IP中几种不同的移动检测方法，指出网络层和底层协议相结合的方法有较好的性能，也是无线网络技术发展趋势之一。
In communication networks many kinds of traffic have stringent end-to-end Quality of Service (QoS) requirements，including delay, bandwidth, packet loss rate etc. With the development of the personal mobile communication system and wide utilization of wireless local area network(WLAN), more and more people began to concern on the problems of providing QoS on the wireless networks. Furthermore, the seamless combination of various wireless communication system using Mobile IP is another promising of future framework of wireless network. In this thesis we study the following aspects.
We study the QoS strategy in wireless networks. After understanding the wireless local network based on IEEE 802.11, we point out the problem that occur when a large MSDU(MAC Service Data Unit) is to be sent in the DCF mode in Wireless LAN. When a MSDU is divided into several MPDUs (MAC Protocol Date Unit), the later MPDU will service as a important role. It is necessary to improve the priority of the later MPDU. We use the leap, linear and exponential methods to reduce the minimum contention window () and the distributed inter frame space (DIFS) , so . The result of simulation approve that our approaches can reduce the delay of the transmission of MSDU, improve the performance of the network. In different situation we can choose appropriate parameters to satisfy the user's QoS requirement.
With the development of Mobile IP, the QoS according to Mobile has been an important issue. In this paper, we compared with several mobile-detection methods, point out that the schedule that combined with network layer and lower layer will have better performance.
服务质量作为人们对网络提供服务的满意程度，自从被提出至今，经历了综合业务模型，差分业务模型和多协议标记交换等阶段。在此基础上，我们研究了无线局域网中的服务质量策略，在对基于IEEE 802.11的无线局域网进行了充分了解的基础上，提出了在无线局域网DCF方式下发送较大MSDU[2]（MAC层服务数据单元）时会遇到的问题，指出当把MSDU分片[2]成为一组MPDU（MAC层协议数据单元）进行发送时，随着MPDUs的不断发送，排序靠后的MPDU将对整个MSDU的发送时间产生决定性影响。因此有必要不断提高MPDU的发送优先级，从而确保MSDU的发送可靠性和延时。提高优先级的方法采用减小DCF中的和DIFS，分别采用阶跃的、线性的和指数的不同方法实现。通过仿真分析，证实了此方法的可行性，并且能够有效减小数据单元的发送时间。
随着IP技术的不断发展，在移动IP中有关服务质量的问题也成为热点。本文还比较了在移动IP中几种不同的移动检测方法，指出网络层和底层协议相结合的方法有较好的性能，也是无线网络技术发展趋势之一。
In communication networks many kinds of traffic have stringent end-to-end Quality of Service (QoS) requirements，including delay, bandwidth, packet loss rate etc. With the development of the personal mobile communication system and wide utilization of wireless local area network(WLAN), more and more people began to concern on the problems of providing QoS on the wireless networks. Furthermore, the seamless combination of various wireless communication system using Mobile IP is another promising of future framework of wireless network. In this thesis we study the following aspects.
We study the QoS strategy in wireless networks. After understanding the wireless local network based on IEEE 802.11, we point out the problem that occur when a large MSDU(MAC Service Data Unit) is to be sent in the DCF mode in Wireless LAN. When a MSDU is divided into several MPDUs (MAC Protocol Date Unit), the later MPDU will service as a important role. It is necessary to improve the priority of the later MPDU. We use the leap, linear and exponential methods to reduce the minimum contention window () and the distributed inter frame space (DIFS) , so . The result of simulation approve that our approaches can reduce the delay of the transmission of MSDU, improve the performance of the network. In different situation we can choose appropriate parameters to satisfy the user's QoS requirement.
With the development of Mobile IP, the QoS according to Mobile has been an important issue. In this paper, we compared with several mobile-detection methods, point out that the schedule that combined with network layer and lower layer will have better performance.
引文
[1] ]朱京，“无线网络中TCP/IP性能改进策略的研究”，[硕士学位论文]，清华大学电子工程系，2001.
[2] IEEE, "IEEE std 802.11-wireless LAN medium access control(MAC) and physical layer(PHY) specifications", 1999.
[3] L. Zhang, S, Deering, D. Estrin, "RSVP: A New Resource Reservation Protocol," IEEE Network, Sep 1993.
[4] K. Fall and K. Varadhan, "ns notes and documentation", tech. rep., VINT Project, UC-Berkeley and LBNL, 2001.
[5] R. Braden, et al., "Resource Reservation Protocol(RSVP)-Version 1 Function Specification", RFC2205, September 1997.
[6] N. H. Vaidya, P. Bahl and S. Gupta, "Distributed Fair Scheduling in a Wireless LAN", ACM Mobicom'2000, Aug. 2000.
[7] C. L. Lee, Y. C. Chen and J. R. Chen, "Providing Service Differentiation in Wireless Networks", IEICE Trans. Commun., vol. E84-B, No.4,April 2001.
[8]W. R. Steven, " TCP Slow Start, congestion, fast retransmit, snd fast recovery Algorithm". IETF 2001， Jan 1997.
[9] S. Floyd , " The NewReno modification to TCP's fast recovery Algorithm". IETF 2582，Apr 1999.
[10] M. Mathis, " TCP Selective Acknowledgement Option". IETF 2081， Oct 1996..
[11]Jim Geier . “无线局域网”，人民邮电出版社，Apr. 2001.
[12]郭峰，曾兴雯，刘乃安等，“无线局域网”，电子工业出版社，May. 1997.
[13]James D.Solomon, “Mobile IP the Internet Unplugged”, 清华大学出版社，Prentice Hill PTR, Jan. 2001.
[14]Dongxu Shen, Chuanyi Ji,"Admission Control of Mutimedia Traffic for Third Generation CDMA Network", INFOCOM 2000: 1077-1086.
[15] Y. X. Cao and O. K. Li, "Scheduling Algorithms in Broad-Band Wireless
Networks", IEEE Proceedings, Vol. 89, pp. 76-87, 2001..
[16]张平，王卫东，崔春风等，“第三代蜂窝移动通信系统-WCDMA”，北京邮电大学出版社，Nov. 2001.
[17]段祥，“无线网络中资源管理和服务质量的研究”，[硕士学位论文]，清华大学电子工程系，2001.
[18]George Xylomenos, George C.Ployzos, “Internet Protocol Performance over Networks with Wireless Links”, IEEE Network, July/August 1999. 55-63.
[19]W. T. Chen, L. C. Huang, “RSVP Mobility Support: A Signaling Protocol for Integrated Services Internet with Mobile Hosts”, IEEE infocom 2000.
[20] A. Terzis, M. Srivastava, L. Zhang, "A Simple QoS Signaling Protocol for Mobile Hosts in the Integrated Services Internet". Appeared in INFOCOM99, NY, NY.
[21] George Xylomenos and George C. Polyzos, "Internet Protocol Performance over Networks with Wireless Links", IEEE Network, Volume 13, Number 4, 1999, pp. 55-63.
[22] George Xylomenos and George C. Polyzos, "Link Layer Support for Quality of Service on Wireless Internet Links", IEEE Personal Communications, Volume 6, Number 5, 1999, pp. 52-60.
[23] N. A. Fikouras, K. El Malki, and S. R. Cvetkovic. "Performance of TCP and UDP during Mobile IP handoffs in single-agent subnetworks". In Proceedings of the Wireless Communications and Networking Conference 1999 (WCNC), New Orleans, USA, September 1999. IEEE.
[24] R. Braden, D. Clark, S. Shenker," Integrated Service in the Internet Architecture: an Overview", Internet RFC 1633, June 19954.
[25]S. Blake et al., "An Architecture for Differentiated Service.", RFC 2475, Dec 1998.
[26] E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol Label Switching Architecture", Internet draft , draft-ietf-mpls-arch-01.txt, Mar 1998.
[27]Xipeng Xiao, Lionel M. Ni,“Internet QoS: A Big Picture”, IEEE Network, March/April 1999, pp8-18.
[28]D. Awduche, et al., “Requirements for Traffic Engineering over MPLS”，Internet draft, draft-ietf-mpls-traffic-eng.00.txt, Oct 1998.
[29]Hari Balakrishnan, Randy H. Katz,"Explicit Loss Notification and Wireless Web Performance", IEEE Globecom Internet Mini-Conference,November 1998.
[30]王重钢，隆克平，龚向阳等，“分组交换网络中队列调度算法的研究及其展望”，电子学报，vol.29，No.4，April 2001，553-559.
[31]Laurent Mathy, Christopher Edwards, David Hutchison, "The Internet: AGlobal Telecommunications Solution", IEEE Network, July/August 2000, 46-57.
[32] Michael Stangel, Vaduvur Bharghavan," Improving TCP Performance in Mobile Computing Environments", International Conference on Communications 1998, Atlanta, GA。
[33] Ashish Ahuja, Sulabh Agarwal, Jatinder Pal Singh, "Performance of TCP over Different Routing Protocols in Mobile Ad-Hoc Networks.", IEEE VTC'2000, Tokyo.
[34]N. A. Fikouras, C. Gorg, "Performance comparison of hinted and advertisement based movement detection methods for mobile IP hand-offs",Computer Networks 37（2001） 55-62。
[35] N. A. Fikouras, K. EI Malki, S. R. Cvetkovic, "Performance analysis of mobile IP handoffs", Asia Pacific Microwave Conference 1999 (APMC), Singapore, December 1999
[2] IEEE, "IEEE std 802.11-wireless LAN medium access control(MAC) and physical layer(PHY) specifications", 1999.
[3] L. Zhang, S, Deering, D. Estrin, "RSVP: A New Resource Reservation Protocol," IEEE Network, Sep 1993.
[4] K. Fall and K. Varadhan, "ns notes and documentation", tech. rep., VINT Project, UC-Berkeley and LBNL, 2001.
[5] R. Braden, et al., "Resource Reservation Protocol(RSVP)-Version 1 Function Specification", RFC2205, September 1997.
[6] N. H. Vaidya, P. Bahl and S. Gupta, "Distributed Fair Scheduling in a Wireless LAN", ACM Mobicom'2000, Aug. 2000.
[7] C. L. Lee, Y. C. Chen and J. R. Chen, "Providing Service Differentiation in Wireless Networks", IEICE Trans. Commun., vol. E84-B, No.4,April 2001.
[8]W. R. Steven, " TCP Slow Start, congestion, fast retransmit, snd fast recovery Algorithm". IETF 2001， Jan 1997.
[9] S. Floyd , " The NewReno modification to TCP's fast recovery Algorithm". IETF 2582，Apr 1999.
[10] M. Mathis, " TCP Selective Acknowledgement Option". IETF 2081， Oct 1996..
[11]Jim Geier . “无线局域网”，人民邮电出版社，Apr. 2001.
[12]郭峰，曾兴雯，刘乃安等，“无线局域网”，电子工业出版社，May. 1997.
[13]James D.Solomon, “Mobile IP the Internet Unplugged”, 清华大学出版社，Prentice Hill PTR, Jan. 2001.
[14]Dongxu Shen, Chuanyi Ji,"Admission Control of Mutimedia Traffic for Third Generation CDMA Network", INFOCOM 2000: 1077-1086.
[15] Y. X. Cao and O. K. Li, "Scheduling Algorithms in Broad-Band Wireless
Networks", IEEE Proceedings, Vol. 89, pp. 76-87, 2001..
[16]张平，王卫东，崔春风等，“第三代蜂窝移动通信系统-WCDMA”，北京邮电大学出版社，Nov. 2001.
[17]段祥，“无线网络中资源管理和服务质量的研究”，[硕士学位论文]，清华大学电子工程系，2001.
[18]George Xylomenos, George C.Ployzos, “Internet Protocol Performance over Networks with Wireless Links”, IEEE Network, July/August 1999. 55-63.
[19]W. T. Chen, L. C. Huang, “RSVP Mobility Support: A Signaling Protocol for Integrated Services Internet with Mobile Hosts”, IEEE infocom 2000.
[20] A. Terzis, M. Srivastava, L. Zhang, "A Simple QoS Signaling Protocol for Mobile Hosts in the Integrated Services Internet". Appeared in INFOCOM99, NY, NY.
[21] George Xylomenos and George C. Polyzos, "Internet Protocol Performance over Networks with Wireless Links", IEEE Network, Volume 13, Number 4, 1999, pp. 55-63.
[22] George Xylomenos and George C. Polyzos, "Link Layer Support for Quality of Service on Wireless Internet Links", IEEE Personal Communications, Volume 6, Number 5, 1999, pp. 52-60.
[23] N. A. Fikouras, K. El Malki, and S. R. Cvetkovic. "Performance of TCP and UDP during Mobile IP handoffs in single-agent subnetworks". In Proceedings of the Wireless Communications and Networking Conference 1999 (WCNC), New Orleans, USA, September 1999. IEEE.
[24] R. Braden, D. Clark, S. Shenker," Integrated Service in the Internet Architecture: an Overview", Internet RFC 1633, June 19954.
[25]S. Blake et al., "An Architecture for Differentiated Service.", RFC 2475, Dec 1998.
[26] E. Rosen, A. Viswanathan, R. Callon, "Multiprotocol Label Switching Architecture", Internet draft , draft-ietf-mpls-arch-01.txt, Mar 1998.
[27]Xipeng Xiao, Lionel M. Ni,“Internet QoS: A Big Picture”, IEEE Network, March/April 1999, pp8-18.
[28]D. Awduche, et al., “Requirements for Traffic Engineering over MPLS”，Internet draft, draft-ietf-mpls-traffic-eng.00.txt, Oct 1998.
[29]Hari Balakrishnan, Randy H. Katz,"Explicit Loss Notification and Wireless Web Performance", IEEE Globecom Internet Mini-Conference,November 1998.
[30]王重钢，隆克平，龚向阳等，“分组交换网络中队列调度算法的研究及其展望”，电子学报，vol.29，No.4，April 2001，553-559.
[31]Laurent Mathy, Christopher Edwards, David Hutchison, "The Internet: AGlobal Telecommunications Solution", IEEE Network, July/August 2000, 46-57.
[32] Michael Stangel, Vaduvur Bharghavan," Improving TCP Performance in Mobile Computing Environments", International Conference on Communications 1998, Atlanta, GA。
[33] Ashish Ahuja, Sulabh Agarwal, Jatinder Pal Singh, "Performance of TCP over Different Routing Protocols in Mobile Ad-Hoc Networks.", IEEE VTC'2000, Tokyo.
[34]N. A. Fikouras, C. Gorg, "Performance comparison of hinted and advertisement based movement detection methods for mobile IP hand-offs",Computer Networks 37（2001） 55-62。
[35] N. A. Fikouras, K. EI Malki, S. R. Cvetkovic, "Performance analysis of mobile IP handoffs", Asia Pacific Microwave Conference 1999 (APMC), Singapore, December 1999