AUTONOMOUS WI-FI BASED RANGING DEVICE

• US 20130044612A1
• Filed: 08/16/2011
• Published: 02/21/2013
• Est. Priority Date: 08/16/2011
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Olaf J. Hirsch
• Inventors: HIRSCH, Olaf J.
• Application Number:
  US13/211,192
• Publication Number:
  US 20130044612A1
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A method for autonomous ranging between Wi-Fi enabled mobile devices. A mobile device transmits a probe request to a target mobile device via a wireless channel, and receives a probe response from the target device. The probe response includes identification information associated with the target device. The mobile device uses the identification information to transmit a data packet to the target device via the wireless channel, and without communicating with any wireless access points. The mobile device then receives a reply packet from the target device and determines a distance to the target device based on a round trip time between the transmission of the data packet and the reception of the reply packet.

Claims

1. A method of operating a mobile device, the method comprising:

transmitting a first probe request to a target mobile device via a wireless channel;

receiving a first probe response from the target mobile device, wherein the probe response includes identification information associated with the target mobile device;

transmitting a first data packet to the target mobile device, via the wireless channel and using the identification information;

receiving a first reply packet from the target mobile device; and

determining a first distance to the target mobile device based, at least in part, on a round trip time (RTT) between the transmission of the first data packet and the reception of the first reply packet.

2. The method of claim 1, wherein the mobile device transmits the first data packet to the target mobile device without communicating with any wireless access points.

3. The method of claim 1, wherein the first data packet is a NULL frame and the first reply packet is an acknowledgement frame.

4. The method of claim 1, further comprising:

selectively triggering an alarm based on the first distance to the target mobile device.

5. The method of claim 4, wherein the selectively triggering comprises triggering the alarm if the first distance is less than or equal to a threshold distance.

6. The method of claim 4, wherein the alarm includes at least one of a visual, audible, or physical notification.

7. The method of claim 4, wherein the alarm intensifies as the first distance decreases.

8. The method of claim 1, wherein the mobile device does not pair or handshake with the target mobile device.

9. The method of claim 1, further comprising:

recording a transmit time when the mobile device transmits the first data packet;

recording a receive time when the mobile device receives the first reply packet; and

determining the RTT based on the transmit time and the receive time.

10. The method of claim 1, wherein the identification information includes at least a media access control (MAC) address of the target mobile device.

11. The method of claim 1, further comprising:

transmitting a second data packet to the target mobile device;

receiving a second reply packet from the target mobile device; and

determining a second distance to the target mobile device based, at least in part, on a RTT between the transmission of the second data packet and the reception of the second reply packet.

12. The method of claim 11, further comprising:

determining a velocity of the target mobile device based, at least in part, on a difference between the first distance and the second distance.

13. A mobile communication device, comprising:

means for transmitting a first probe request to a target mobile device via a wireless channel;

means for receiving a first probe response from the target mobile device, wherein the probe response includes identification information associated with the target mobile device;

means for transmitting a first data packet to the target mobile device, via the wireless channel and using the identification information;

means for receiving a first reply packet from the target mobile device; and

means for determining a first distance to the target mobile device based, at least in part, on a round trip time (RTT) between the transmission of the first data packet and the reception of the first reply packet.

14. The device of claim 13, wherein the mobile device transmits the first data packet to the target mobile device without communicating with any wireless access points.

15. The device of claim 13, wherein the first data packet is a NULL frame and the first reply packet is an acknowledgement frame.

16. The device of claim 13, further comprising:

means for selectively triggering an alarm based on the first distance to the target mobile device.

17. The device of claim 16, wherein the means for selectively triggering is configured to trigger the alarm if the first distance is less than or equal to a threshold distance.

18. The device of claim 13, wherein the alarm includes at least one of a visual, audible, or physical notification.

19. The device of claim 13, wherein the mobile device does not pair or handshake with the target mobile device.

20. The device of claim 13, further comprising:

means for recording a transmit time when the mobile device transmits the first data packet;

means for recording a receive time when the mobile device receives the first reply packet; and

means for determining the RTT based on the transmit time and the receive time.

21. The device of claim 13, wherein the identification information includes at least a media access control (MAC) address of the target mobile device.

22. The device of claim 13, further comprising:

means for transmitting a second data packet to the target mobile device;

means for receiving a second reply packet from the target mobile device; and

means for determining a second distance to the target mobile device based, at least in part, on a RTT between the transmission of the second data packet and the reception of the second reply packet.

23. The device of claim 22, further comprising:

means for determining a velocity of the target mobile device based, at least in part, on a difference between the first distance and the second distance.

24. The device of claim 13, further comprising:

a GPS component configured to determine an absolute position of the mobile communication device.

25. The device of claim 24, further comprising:

means for communicating the absolute position of the mobile communication device to the target device.

26. The device of claim 25, wherein the absolute position of the mobile communication device is communicated to the target device by embedding the absolute position within the first data packet.