IMC '05, 2005 Internet Measurement Conference Abstract
Pp. 293298 of the Proceedings
Facilitating Access Point Selection in IEEE 802.11 Wireless Networks
S. Vasudevan, University of Massachusetts, Amherst; K. Papagiannaki and C. Diot, Intel Research Cambridge; J. Kurose and D. Towsley, University of Massachusetts, Amherst
The performance experienced by wireless clients in IEEE 802.11 wireless
networks heavily depends on the clients' ability to identify the Access
Point (AP) that will offer the best service. The current AP
affiliation mechanism implemented in most wireless clients is based on
signal strength measurements received by the client from all the APs
neighborhood. The client then affiliates with the AP from which it
receives the strongest signal. It is well-known that such an algorithm
can lead to sub-optimal performance, due to its ignorance of the
load at different APs.
In this work, we consider the problem
of AP selection. We identify potential bandwidth as the
metric based on which hosts should make affiliation decisions, and define it as the (MAC-layer) bandwidth that
client is likely to receive after affiliating with a particular AP. We
limit ourselves to the use of passive measurements that do not
require an end-host to affiliate with the AP, thus allowing the end-host to simultaneously evaluate the potential bandwidth to multiple APs in range.
This can also facilitate more
informed roaming decisions. We propose a methodology for the estimation
of potential upstream and downstream bandwidth between a client and an AP based on
measurements of delay incurred by 802.11 Beacon frames from the AP.
Preliminary experiments conducted in a controlled environment demonstrate that
the proposed methodology looks promising, yielding fairly accurate
under varying conditions.
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