| Conference |
| Type of Publication |
| Overhearing the Wireless Interface for 802.11-based
Positioning Systems |
| Title |
|
|
| Authors |
| Proc. of the Fifth Annual IEEE International
Conference on Pervasive Computing and Communications (PerCom
2007), pp.
145-150, New York, NY, USA, 23. March 2007 |
| Published in |
| Not only the proliferation of 802.11, but
also the capability to determine the position of mobile devices
make 802.11 highly appealing for many application areas.
Typically, a mobile device that wants to know its position
regularly performs active or passive scans to obtain the signal
strength measurements of neighboring access points. Active and
passive scanning are survey techniques originally intended to be
performed once in a while to learn about the presence and signal
reception quality of access points within communication range.
Based on this survey the best suitable access point is selected
as the gateway to the wired network. However, so far, no
investigations are known to have been launched into how regular
scanning affects concurrent data transmissions from an end-user
point of view. In this paper, we explore how common data
communication is affected while actively or passively scanning at
the same time. We found that with an active scanning interval of
less than 2 seconds the network conditions such as throughput and
round trip delay are insufficient for interactive applications.
The same is true for passive scanning if a scanning interval of
less than 7 seconds is chosen. Furthermore, we present a novel
scan scheme called Monitor Sniffing to reduce client service
disruptions. Monitor Sniffing exploits the fact that 802.11
operates on overlapping channels by overhearing the wireless
interface. We have implemented our Monitor Sniffing algorithm
using commodity 802.11g hardware, and we demonstrate that it is
faster than active and passive scanning and does not disturb
concurrent data communication. Finally, our approach only
requires software modifications on the client side, making the
adoption process quite easy. |
| Abstract |
|
| Projects |
|
Monitor Sniffing
positioning systems
location systems
802.11
ubiquious computing
Mobile Business
context-aware applications
location-based services
|
| Keywords |
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