Improving the Latency of 802.11 hand-offs using Neighbor Graphs
Improving the Latency of 802.11 hand-offs using Neighbor Graphs
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Date
2004-01-29
Authors
Shin, Minho
Mishra, Arunesh
Arbaugh, William
Advisor
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Abstract
The 802.11 IEEE Standard has enabled low cost and effective wireless
LAN services (WLAN). With the sales and deployment of WLAN based
networks exploding, many people believe that they will become the
fourth generation cellular system (4G) or a major portion of
it. However, the small cell size of WLAN networks creates frequent
hand-offs for mobile users. If the latency of these hand-offs is high,
as previous studies have shown, then the users of synchronous
multimedia applications such as voice over IP (VoIP) will experience
excessive jitter. The dominating factor in WLAN hand-offs has been
shown to be the discovery of the candidate set of next access
points. In this paper, we describe the use of a novel and efficient
discovery method using neighbor graphs and overlap
graphs. Our method reduces the total number probed channels as well
as the total time spent waiting on each channel. Our implementation
results show that this approach reduces the overall probe time
significantly when compared to other approaches. Furthermore,
simulation results show that the effectiveness of our method improves
as the number of non-overlapping channels increases, such as in the 5
GHz band used by the IEEE 802.11a standard.
(UMIACS-TR-2003-118)