US 7,551,579 B2Granted

Calculation of quality of wlan access point characterization for use in a wlan positioning system

AssigneeSkyhook Wireless, Inc.

InventorsFarshid Alizadeh-Shabdiz, Kaveh Pahlavan, Nicolas Brachet

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Abstract

Methods and systems for classifying WLAN access points according to the quality of estimation of characteristics of the WLAN access points are provided. The classifications may be used to scale a reference database and quantify an expected error of estimation of the characteristics of the access points. WLAN access points may be classified based on their impact on a user's position, speed of travel, and direction of travel estimation accuracy in a WLAN positioning system. A method for determining a quality of estimation of characteristics of a Wi-Fi access point comprises a Wi-Fi enabled scanning device measuring a number of received signal strength (RSS) samples of the Wi-Fi signal transmitted by the Wi-Fi access point. A total distance traveled by the Wi-Fi enabled scanning device while measuring the number of RSS samples is estimated and used to estimate the quality of estimation of characteristics of the Wi-Fi access point.

Claims4

Dependent claims

In a positioning system having a plurality of Wi-Fi access points in a target area, a method for determining a quality of estimation of characteristics of a Wi-Fi access point, the method comprising:

a Wi-Fi enabled scanning device receiving and measuring a number of received signal strength (RSS) samples of a Wi-Fi signal transmitted by the Wi-Fi access point;
estimating a total distance traveled by the Wi-Fi enabled scanning device while measuring the number of RSS samples;
using the estimated total distance traveled to calculate the quality of estimation of characteristics of the Wi-Fi access point;
associating a corresponding speed of travel of the Wi-Fi enabled scanning device with each RSS sample;
associating a corresponding period of time of scanning with each RSS sample;
determining a confidence factor, CFn, using the sum of each of the speeds of travel of the Wi-Fi enabled scanning device weighted by the corresponding period of time of scanning for each RSS sample;
and
determining the quality of estimation, R, according to the equation:
R
=
(
R
max
-
R
min
)
⁢
[
log
⁢
(
CF
n
)
-
log
⁡
(
CF
min
)
]
[
log
⁡
(
CF
max
)
-
log
⁡
(
CF
min
)
]
+
R
min
wherein:
Rmax is a maximum quality of estimation;
Rmin is a minimum quality of estimation;
CFmax is a maximum confidence factor;
and
CFmin is a minimum confidence factor.

54 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/430,224Filed 8 May 2006
Published: US 2007/0258409 A18 Nov 2007
Granted: 23 Jun 2009
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

H04W 16/18
Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures: network planning tools
H04W 24/10
Supervisory, monitoring or testing arrangements: scheduling measurement reports ; Arrangements for measurement reports
H04W 48/16
Access restriction ; Network selection; Access point selection: discovering, processing access restriction or access information
H04W 48/20
Access restriction ; Network selection; Access point selection: selecting an access point