| Conference |
| Type of Publication |
| ComPoScan: Adaptive Scanning for Efficient Concurrent
Communications and Positioning with 802.11 |
| Title |
|
Mikkel Baun Kjærgaard
|
| Authors |
| Proc. of the 6th ACM International Conference on
Mobile Systems, Applications, and Services (MobiSys
2008), Breckenridge, CO, USA, June 2008 |
| Published in |
| Using 802.11 concurrently for communications
and positioning is problematic, especially if location-based
services (e.g., indoor navigation) are concurrently executed with
real-time applications (e.g., VoIP, video conferencing).
Periodical scanning for measuring the signal strength interrupts
the data flow. Reducing the scan frequency is no option because
it hurts the position accuracy. For this reason, we need an
adaptive technique to mitigate this problem. This work proposes
ComPoScan which, based on movement detection, adaptively switches
between light-weight monitor sniffing and invasive active
scanning to allow positioning and to minimize the impact on the
data flow. The system is configurable to realize different
trade-offs between position accuracy and the level of
communication interruption. We provide extensive experimental
results by emulation on data collected at several sites and by
validation in several real-world deployments. Results from the
emulation show that the system can realize different trade-offs
by changing parameters. Furthermore, the emulation shows that the
system works independently of the environment, the network card,
the signal strength measurement technology, and number and
placement of access points. We also show that ComPoScan does not
harm the positioning accuracy of a positioning system. By
validation in several real-world deployments, we provided
evidence for that the real system works as predicted by the
emulation. In addition, we provide results for ComPoScan's impact
on communication where it increases throughput by a factor of
122, decreases the delay by a factor of ten, and the percentage
of dropped packages by 73 percent. |
| Abstract |
| [PDF]
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