Method and apparatus for determining the location of a node in a wireless system

• US 20070021124A1
• Filed: 07/25/2005
• Published: 01/25/2007
• Est. Priority Date: 07/25/2005
• Status: Active Grant

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Huang, Jian, Kyperountas, Spyros, Niu, Feng
• Granted Patent: US 7,317,925 B2
• Time in Patent Office: Days
• US Class Current: 455/456.100
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A location technique is utilized within a wireless communication system where power measurements from various nodes are weighted to determine a node'"'"'s location. An iterative location process is executed where as more and more nodes are heard from, a node will re-locate itself in order to improve location accuracy.

Claims

1. A method for determining a location of a node in a wireless communication system, the method comprising the steps of:

receiving a first plurality of over-the-air signals from a first plurality of nodes, the first plurality of over-the-air signals each containing a location;

calculating a first plurality of weighting factors based on transmit and receive powers of the first plurality of over-the-air signals;

calculating a location based on the first plurality of weighting factors and the locations.

2. The method of claim 1 wherein the first plurality of over-the-air signals additionally comprises transmit power information.

3. The method of claim 1 wherein the step of calculating the first plurality of weighting factors comprises the step of calculating a first plurality of weighting factors that are based on a ratio of received power to transmit power.

4. The method of claim 1 wherein the first plurality of nodes comprises a first plurality of reference nodes, the locations of which are known.

5. The method of claim 4 wherein the step of calculating the first plurality of weighting factors comprises the step of calculating a plurality of values for

6. The method of claim 5 wherein n1 is a parameter adjustable to optimize location estimation, preferably in the range of n/2 and 3n/2, where n is the path loss exponent assuming the following path loss model,

PL(in dB)=PL₀(in dB)+10n log (r)+ε

,

PL (in dB)=−

10 log₁₀(β

), where r is a distance between the two nodes.

7. The method of claim 5 wherein the step of calculating the location comprises the step of calculating

8. The method of claim 1 further comprising the steps of:

receiving a second plurality of over-the-air signals from a second plurality of nodes, the second plurality of over-the-air signals each containing a location;

calculating a second plurality of weighting factors based on transmit and receive powers of the second plurality of over-the-air signals;

calculating an updated location based on the second plurality of weighting factors and the locations within the second plurality of over-the -air signals.

9. The method of claim 8 wherein the second plurality of over-the-air signals additionally comprises transmit power information.

10. The method of claim 8 wherein the step of calculating the second plurality of weighting factors comprises the step of calculating a second plurality of weighting factors that are based on a ratio of received power to transmit power.

11. The method of claim 8 wherein the second plurality of nodes comprises reference nodes, the locations of which are known, and blind nodes, the locations of which are estimated.

12. The method of claim 11 wherein the step of calculating the second plurality of weighting factors comprises the step of calculating a plurality of values for

13. The method of claim 12 wherein n1 is a parameter adjustable to optimize location estimation, preferably in the range of n/2 and 3n/2, where n is the path loss exponent assuming the following path loss model,

PL(in dB)=PL₀(in dB)+10n log (r)+ε

,

PL(in dB)=−

10 log₁₀(β

), where r is a distance between the two nodes.

14. The method of claim 12 wherein the step of calculating the updated location comprises the step of calculating

15. An apparatus comprising:

a receiver receiving a first plurality of over-the-air signals from a first plurality of nodes, the first plurality of over-the-air signals each containing a location; and

logic circuitry calculating a first plurality of weighting factors based on transmit and receive powers of the first plurality of over-the-air signals and calculating a location based on the first plurality of weighting factors and the locations.

16. The apparatus of claim 15 wherein the first plurality of over-the-air signals additionally comprises transmit power information.

17. The apparatus of claim 15 wherein the weighting factors are based on a ratio of received power to transmit power.

18. The method of claim 15 wherein the first plurality of nodes comprises a first plurality of reference nodes, the locations of which are known.

19. The method of claim 18 wherein the weighting factors are calculated by finding values for

20. The method of claim 19 wherein n1 is a parameter adjustable to optimize location estimation, preferably in the range of n/2 and 3n/2, where n is the path loss exponent assuming the following path loss model,

PL(in dB)=PL₀(in dB)+10n log (r)+ε

,

PL (in dB)=−

10 log₁₀(β

), where r is a distance between the two nodes.