PACKET BASED LOCATION PROVISIONING IN WIRELESS NETWORKS

• US 20110149756A1
• Filed: 12/23/2009
• Published: 06/23/2011
• Est. Priority Date: 12/23/2009
• Status: Active Grant

• Current Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Original Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Inventors: Yang, Jin, Kamdar, Kamlesh S., Chan, Yee Sin, Lee, Jay J.
• Granted Patent: US 8,467,309 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A system may include a plurality of wireless devices, each wireless device including a time source and configured to selectively communicate with at least one other of the plurality of wireless devices by way of a packet-based time precision protocol. The plurality of wireless devices may include a first wireless device and a second wireless device, the first wireless device being configured to determine whether the first wireless device and the second wireless device are in selective communication over a single-hop wireless link; determine a one-way delay over the single-hop wireless link by way of at least one packed-based time precision protocol message; and calculate a distance measurement between the first wireless device and the second wireless device based at least in part on the one-way delay.

Claims

1. A system, comprising:

a plurality of wireless devices, each wireless device including a time source and configured to selectively communicate with at least one other of the plurality of wireless devices by way of a packet-based time precision protocol;

wherein the plurality of wireless devices includes a first wireless device and a second wireless device, the first wireless device being configured to;

determine whether the first wireless device and the second wireless device are in selective communication over a single-hop wireless link;

determine a one-way delay over the single-hop wireless link by way of at least one packed-based time precision protocol message; and

calculate a distance measurement between the first wireless device and the second wireless device based at least in part on the one-way delay.

2. The system of claim 1, wherein the first wireless device is further configured to adjust the distance measurement according to a non-line-of-sight portion of the one-way delay.

3. The system of claim 1, wherein the first wireless device is further configured to:

send a first message to the second wireless device;

determine a first timestamp indicative of the time the first message is sent using the time source included in the first wireless device;

receive a second message from the second wireless device, the second message including a second timestamp indicative of the time the first message was received and a third timestamp indicative of the time the second message was sent, the second and third timestamps being determined by a time source included in the second wireless device;

determine a fourth timestamp indicative of the time the second message is received using the time source included in the first wireless device;

determine an offset time between the time source in the first wireless device and the time source in the second wireless device; and

determine the one-way delay between the first wireless device and the second wireless device according to the four timestamps and the offset time.

4. The system of claim 3, wherein the second wireless device is configured to:

receive the first message from the first wireless device;

determine the second timestamp indicative of the time the first message is received using the time source included in the second wireless device;

determine the third timestamp indicative of the time the second message is to be sent using the time source included in the second wireless device; and

send the second message to the first wireless device responsive to receipt of the first message.

5. The system of claim 1, wherein the first wireless device is further configured to:

determine whether the first wireless device and a third wireless device of the plurality of devices are in selective communication over a second single-hop wireless link;

determine a second one-way delay over the second single-hop wireless link by way of at least one packed-based time precision protocol message; and

calculate an additional distance measurement between the first wireless device and the third wireless device based at least in part on the second one-way delay.

6. The system of claim 5, wherein the first wireless device is further configured to:

optimize a set of weighting factors, each of the distance measurements being associated with a corresponding weighting in the set of weightings;

perform a weighted trilateration of the distance measurements weighted according to the weighting factors; and

provision a location of the first wireless device according to the result of the weighted trilateration.

7. The system of claim 6, wherein the weighted trilateration includes a least squares optimization weighted according to the set of weighting factors.

8. The system of claim 6, wherein the distance measurement is assigned a weighting according to the distance measurement from the second wireless device.

9. The system of claim 8, wherein the weighting is at least one of inversely proportional to the distance measurement, linearly decreasing with respect to the distance measurement, and reduced to zero according to a distance threshold.

10. The system of claim 6, wherein the distance measurement is assigned a weighting according to an underlying wireless technology over which the first message is sent.

11. The system of claim 10, wherein a distance measurement performed over a cellular communications link is assigned a greater weighting factor than a distance measurement performed over a wireless local area network link.

12. The system of claim 6, wherein the distance measurement is assigned a weighting according to a precision of the time source of the second wireless device.

13. A method, comprising:

determining whether a first wireless device and a second wireless device are in selective communication over a single-hop wireless link;

each wireless device being one of a plurality of wireless devices including a time source and selectively communicating with at least one other of the plurality of wireless devices by way of a packed-based time precision protocol;

determining a one-way delay over the single-hop wireless link by way of at least one packed-based time precision protocol message; and

calculating distance measurement between the first wireless device and the second wireless device based at least in part on the one-way delay.

14. The method of claim 13, further comprising:

sending a first message to the second wireless device;

determining a first timestamp indicative of the time the first message is sent using the time source included in the first wireless device;

receiving a second message from the second wireless device, the second message including a second timestamp indicative of the time the first message was received and a third timestamp indicative of the time the second message was sent, and determining the second and third timestamps by way of a time source included in the second wireless device;

determining a fourth timestamp indicative of the time the second message is received using the time source included in the first wireless device;

determining an offset time between the time source in the first wireless device and the time source in the second wireless device; and

determining the one-way delay between the first wireless device and the second wireless device according to the four timestamps and the offset time.

15. The method of claim 13, further comprising:

determining whether the first wireless device and a third wireless device of the plurality of devices are in selective communication over a second single-hop wireless link;

determining a second one-way delay over the second single-hop wireless link by way of at least one packed-based time precision protocol message; and

calculating an additional distance measurement between the first wireless device and the third wireless device based at least in part on the second one-way delay.

16. The method of claim 15, further comprising:

optimizing a set of weighting factors, each of the distance measurements being associated with a corresponding weighting in the set of weightings;

performing a weighted trilateration of the distance measurements weighted according to the weighting factors; and

provisioning a location of the first wireless device according to the result of the weighted trilateration.

17. The method of claim 16, wherein the weighted trilateration includes a least squares optimization weighted according to the set of weighting factors.

18. A computer-readable medium tangibly embodying computer-executable instructions comprising:

calculating a first distance measurement between a first wireless device and a second wireless device according to a line-of-sight delay between the first wireless device and the second wireless device;

calculating a second distance measurement between the first wireless device and a third wireless device according to a line-of-sight delay between the first wireless device and the third wireless device;

determining a first weighting factor configured to weight the first distance measurement;

determining a second weighting factor configured to weight the second distance measurement;

performing a weighted trilateration including the measured distances weighted according to the weighting factors; and

provisioning a location of the first wireless device according to the result of the weighted trilateration.

19. The computer-readable medium of claim 18, wherein the weightings are determined according to at least one of a distance measurement between wireless devices, an underlying wireless technology over which a distance measurement was determined, and a precision of a time source used in part to determine a distance measurement.

20. The computer-readable medium of claim 18, further comprising:

calculating a third distance measurement between a first wireless device and a third wireless device according to a line-of-sight delay between the first wireless device and the third wireless device; and

calculating a fourth distance measurement between a first wireless device and a fourth wireless device according to a line-of-sight delay between the first wireless device and the fourth wireless device.