Techniques for estimating a position of a user device using optimized scanning
In various embodiments, position of a user device is estimated by scanning for WLAN packets transmitted within range of the user device, the scanning to include a plurality of phases which are progressed through until WLAN information sufficient to identify at least a threshold number of WLAN APs is obtained, the plurality of phases including an active scanning phase in which the RF module transmits probe request packets and receives one or more probe response packets, and one or more passive scanning phases in which the RF module listens for one or more packets without first transmitting request packets, extracting WLAN information indicating an identity of one or more WLAN APs from the one or more probe response packets or the one or more listened for packets, and providing the WLAN information to a WPS to obtain an estimate of the position of the user device.
1. A method for estimating a position of a user device, comprising:
scanning, by a radio frequency (RF) module of the user device, for wireless local area network (WLAN) packets transmitted within range of the user device, the scanning to include a plurality of phases which are progressed through until WLAN information that identifies at least a threshold number of WLAN access points (APs) is obtained and then scanning is ceased, the plurality of phases including an active scanning phase in which the RF module transmits probe request packets and receives one or more probe response packets, and one or more passive scanning phases in which the RF module listens for one or more packets without first transmitting request packets;
extracting WLAN information indicating an identity of one or more WLAN APs from the one or more probe response packets or the one or more listened for packets; and
providing the WLAN information indicating the identity of the one or more WLAN APs to a WLAN positioning system (WPS) to obtain an estimate of the position of the user device.
2. The method of claim 1 , wherein the one or more passive scanning phases include a passive scanning phase of a subset of all WLAN channels provided by a WLAN protocol and a passive scanning phase of all WLAN channels provided by the WLAN protocol.
3. The method of claim 1 , wherein the threshold number of WLAN APs is greater than a minimum number of WLAN APs required by the WPS to estimate the position of the user device.
4. The method of claim 1 , wherein the user device is a limited-transmission device that is only capable of transmitting a predefined subset of WLAN packets supported by a WLAN protocol.
5. The method of claim 4 , wherein the predefined subset of WLAN packets includes probe request packets.
6. The method of claim 4 , wherein the limited-transmission device is only capable of receiving a second predefined subset of WLAN packets supported by the WLAN protocol.
7. The method of claim 6 , wherein the second predefined subset of WLAN packets includes probe response packets.
8. The method of claim 1 , wherein the probe request packets are pre-generated and stored on the user device, and transmission of probe request packets comprises providing the pre-generated probe-response packets to the RF module.
9. A method for estimating a position of a user device, comprising:
scanning, by a radio frequency (RF) module of the user device, for wireless local area network (WLAN) packets transmitted within range of the user device, the RF module having a RF filter bandwidth that allows WLAN packets on multiple WLAN channels of a WLAN protocol to simultaneously pass;
extracting WLAN information indicating an identity of one or more WLAN APs from the WLAN packets simultaneously passed by the RF filter; and
providing the WLAN information indicating the identity of the one or more WLAN APs to a WPS to obtain an estimate of the position of the user device.
10. The method of claim 9 , wherein the scanning using the RF module having the RF filter bandwidth that allows WLAN packets on multiple WLAN channels to simultaneously pass includes passive scanning.
11. A method for estimating a position of a user device, comprising:
determining a power-consumption mode and a wireless local area network access point (AP) association status of the user device;
based on the power-consumption mode and the association status, performing at least one of active scanning in which the RF module transmits probe request packets and receives one or more probe response packets or passive scanning in which the RF module listens for one or more packets without first transmitting request packets;
extracting WLAN information indicating an identity of one or more WLAN APs from the one or more probe response packets or the one or more listened for packets; and
providing the WLAN information indicating the identity of the one or more WLAN APs to a WLAN positioning system (WPS) to obtain an estimate of the position of the user device.
12. The method of claim 11 , wherein the active scanning is performed in response to determining the user device is in a low-power consumption mode and not associated with any WLAN AP.
13. The method of claim 11 , wherein the active scanning and the passive scanning are both performed in response to determining the user device is in an active mode and not associated a WLAN AP, wherein the active scanning is performed first and followed by the passive scanning.
14. A system configured to estimate a position of a user device, comprising:
a user device including
one or more radio frequency (RF) modules configured to scan for wireless local area network (WLAN) packets transmitted within range of the user device, the scanning to include a plurality of phases which are utilized until a condition is met, the plurality of phases including an active scanning phase in which the RF module transmits probe request packets and receives one or more probe response packets, and one or more passive scanning phases in which the RF module listens for one or more packets without first transmitting request packets, and
a packet processing module configured to extract WLAN information indicating an identity of one or more WLAN APs from the one or more probe response packets or the one or more listened for packets; and
a WPS executing at least in part on the user device or a server that is accessible to the user device, the WPS configured to take the identity of the one or more WLAN APs, compare the identity of the one or more WLAN APs to a reference database, and based on the comparison estimate a position of the user device.
15. The system of claim 14 , wherein the condition is that WLAN information that identifies at least a threshold number of WLAN access points (APs) has been obtained.
16. The system of claim 15 , wherein the threshold number of WLAN APs is greater than a minimum number of WLAN APs required by the WPS to estimate the position of the user device.
17. The system of claim 14 , wherein the one or more passive scanning phases include a passive scanning phase of a subset of all WLAN channels provided by a WLAN protocol and a passive scanning phase of all WLAN channels provided by the WLAN protocol.
18. The system of claim 14 , wherein the user device is a limited-transmission device that is only capable of transmitting a predefined subset of WLAN packets supported by a WLAN protocol.
19. The system of claim 14 , wherein the limited-transmission device is only capable of receiving a second predefined subset of WLAN packets supported by the WLAN protocol.
20. The system of claim 14 , wherein a phase to utilize of the plurality of phases is selected in response to a power-consumption mode and the association status of the user device.