SYSTEM AND METHOD OF PASSIVE AND ACTIVE SCANNING OF WLAN-ENABLED ACCESS POINTS TO ESTIMATE POSITION OF A WLAN POSITIONING DEVICE

• US 20080008121A1
• Filed: 07/06/2007
• Published: 01/10/2008
• Est. Priority Date: 07/07/2006
• Status: Active Grant

• Current Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Original Assignee: Skyhook Wireless Incorporated (Liberty Broadband Corp.)
• Inventors: ALIZADEH-SHABDIZ, Farshid
• Granted Patent: US 8,185,129 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: G01S 5/019 Energy consumption
• CPC Class Codes: G01S 5/0242 Determining the position of transmitters to be subsequently used in positioning G01S5/0289 takes precedence
• CPC Class Codes: H04B 7/26 at least one of which is mobile
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

Systems and methods of passive and active scanning of WLAN-enabled access points to estimate position of a WLAN positioning device. A device estimates the position of itself. The device includes a WLAN radio module for receiving WLAN signals, extraction logic for extracting information from said received WLAN signals to identify the WLAN APs, and logic to cooperate with a WLAN-based positioning system. The WLAN radio module includes a phase for active scanning of WLAN APs in range of said device and a phase of passive scanning of WLAN APs in range of said device, and the passive scanning phase scans only a pre-determined and selected subset of WLAN channels. Under certain embodiments, the WLAN radio module includes a passive scanning phase that simultaneously scans multiple WLAN channels.

Claims

1. A device for estimating the position of itself in response to gathering wireless signal information from WLAN access points (APs), said device comprising:

a WLAN radio module for receiving WLAN signals transmitted by WLAN APs in range of said device;

extraction logic for extracting information from said received WLAN signals to identify the WLAN APs; and

logic to cooperate with a WLAN-based positioning system to estimate the position of the device based at least in part on the extracted information identifying the WLAN APs in the range of said device;

wherein said WLAN radio module includes a phase for active scanning of WLAN APs in range of said device and a phase of passive scanning of WLAN APs in range of said device; and

wherein said passive scanning phase scans only a pre-determined and selected subset of WLAN channels.

2. The device of claim 1 wherein the pre-determined and selected subset is the most used WLAN channels.

3. The device of claim 1 wherein said WLAN radio module includes a passive scanning phase that simultaneously scans multiple WLAN channels.

4. The device of claim 1 wherein said scanning is divided into a plurality of phases, and wherein said WLAN radio module stops scanning after detecting sufficient number of APs to locate the WLAN enabled device.

5. The device of claim 1 wherein the scanning is selected based on a status of the device to minimize power consumption.