Using Neighbor Graphs in Support of Fast and Secure WLAN Mobility

William A. Arbaugh
University of Maryland

Monday, October 20, 1:30PM
*** Note unusual time. ***
Lieb 3rd floor Conference Room
 

Abstract


IEEE 802.11 based wireless networks have seen rapid growth and deployment in recent years. Critical to the 802.11 MAC operation is the hand-off function that occurs when a mobile node moves its association from one access point (or base station) to another. In this talk I will present an empirical study of the 802.11 handoff process at the link layer which will include a detailed breakup of the contributing factors of the latency. In particular, I will show that a MAC layer function, probe, is the primary contributor to the overall handoff latency in current deployments, and that a proposed standard inter-access point protocol (IAPP) contributes an additional unwarranted delay. I will then describe a novel method for dynamically learning the mobility topology of the network, i.e. the neighbor graph. Neighbor graphs are then used to cache context ahead of a mobile station ensuring that the station's context is always one hop ahead. I will conclude the talk by providing implementation and performance details. Specifically, we find that the use of neighbor graphs with IAPP reduces the hand-off latency by an order of magnitude.

This is joint work with Arunesh Mishra and Min-ho Shin of the University of Maryland, as well as Insun Lee and Kyunghun Jang of Samsung Electronics.