Abstract
IEEE 802.11 based wireless networks have seen rapid growth and deployment in the recent years. Critical to the 802.11 MAC operation, is the handoff function which occurs when a mobile node moves its association from one access point to another. In this paper, we present an empirical study of this handoff process at the link layer, with a detailed breakup of the latency into various components. In particular, we show that a MAC layer function - probe is the primary contributor to the overall handoff latency. In our study, we observe that the latency is significant enough to affect the quality of service for many applications (or network connections). Further we find variations in the latency from one hand-off to another as well as with APs and STAs used from different vendors. Finally, we discuss optimizations on the probe phase which can potentially reduce the probe latency by as much as 98% (and a minimum of 12% in our experiments). Based on the study, we draw some guidelines for future handoff schemes.
- Host AP driver for Intersil Prism Cards. URL:http://hostap.epitest.fi.Google Scholar
- Linux driver for Prism based wireless cards. URL:http://www.linux-wlan.com/linux-wlan/.Google Scholar
- OpenBSD based access points using the Soekris Boards. URL: http://www.missl.cs.umd.edu/wireless/testbed/.Google Scholar
- A. Balachandran, G. Voelker, P. Bahl, and P. Rangan. Characterizing User Behavior and Network Performance in a Public Wireless LAN. In Proceedings of ACM SIGMETRICS'02, June 2002. Google ScholarDigital Library
- R. Caceres and V. N. Padmanabhan. Fast and Scalable Wireless Handoffs in Support of Mobile Internet Audio. Mobile Networks and Applications, 3(4):180--188, December 1998. Google ScholarDigital Library
- C. Chien. Digital Radio Systems on a Chip. Kluwer Academic Publishers, 2001. Google ScholarDigital Library
- IEEE. Part 11:Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. IEEE Standard 802.11, 1999.Google Scholar
- IEEE. Recommended Practice for Multi-Vendor Access Point Interoperability via an Inter-Access Point Protocol Across Distribution Systems Supporting IEEE 802.11 Operation. IEEE Draft 802.1f/D3, January 2002.Google Scholar
- International Telecommunication Union. General Characteristics of International Telephone Connections and International Telephone Circuits. ITU-TG.114, 1988.Google Scholar
- R. Koodli and C. Perkins. Fast Handover and Context Relocation in Mobile Networks. ACM SIGCOMM Computer Communication Review, 31(5), October 2001. Google ScholarDigital Library
- U. R. Krieger and M. Savoric. Performance Evaluation Of Handover Protocols For Data Communication In A Wireless ATM Network. In Proceedings of ITC 16, June 1999.Google Scholar
- A. Mishra, M. Shin, and W. Arbaugh. Context Caching using Neighbor Graphs for Fast Handoffs in a Wireless Network. Computer Science Technical Report CS-TR-4477, University of Maryland, 2003.Google Scholar
- S. Pack and Y. Choi. Fast Inter-AP Handoff using Predictive-Authentication Scheme in a Public Wireless LAN. IEEE Networks 2002 (To Appear), August 2002.Google ScholarCross Ref
- S. Pack and Y. Choi. Pre-Authenticated Fast Handoff in a Public Wireless LAN based on IEEE 802.1x Model. IFIP TC6 Personal Wireless Communications 2002 (To Appear), October 2002. Google ScholarDigital Library
- R. Ramjee, T. F. L. Porta, J. Kurose, and D. Towsley. Performance evaluation of connection rerouting schemes for ATM-based wireless networks. IEEE/ACM Transactions on Networking, 6(3):249--261, 1998. Google ScholarDigital Library
- H. B. Srinivasan Seshan and R. H. Katz. Handoffs in Cellular Wireless Networks: The Daedalus Implementation and Experience. 4:141--162, 1997. Google ScholarDigital Library
- C. L. Tan, K. M. Lye, and S. Pink. A Fast Handoff Scheme for Wireless Networks. In WOWMOM, pages 83--90, 1999. Google ScholarDigital Library
- C.-K. Toh. Implementation and Evaluation of a Mobile Handover Protocol in Fairisle. 1995. http://www.cl.cam.ac.uk/Research/SRG/greenbook.html.Google Scholar
Index Terms
- An empirical analysis of the IEEE 802.11 MAC layer handoff process
Recommendations
Reducing MAC layer handoff latency in IEEE 802.11 wireless LANs
MobiWac '04: Proceedings of the second international workshop on Mobility management & wireless access protocolsWith the growth of IEEE 802.11-based wireless LANs, VoIP and similar applications are now commonly used over wireless networks. Mobile station performs a handoff whenever it moves out of the range of one access point (AP) and tries to connect to a ...
Design and evaluation of a novel MAC layer handoff protocol for IEEE 802.11 wireless networks
In recent years, the IEEE 802.11 wireless network family has become one of the most important set of standards in the wireless communications industry. IEEE 802.11 compliant devices are inexpensive and easier to configure and deploy than other wireless ...
A cross-layer partner-based fast handoff mechanism for IEEE 802.11 wireless networks
In wireless-mobile networks, users freely and frequently change their access points (APs) while they are communicating with other users. To support the mobility of mobile nodes (MNs), Mobile IPv6 (MIPv6) is used to inform the information of MN's home ...
Comments