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

• US 7,317,925 B2
• Filed: 07/25/2005
• Issued: 01/08/2008
• 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: Niu, Feng, Kyperountas, Spyros, Huang, Jian
• Primary Examiner(s): Eng, George
• Assistant Examiner(s): Kim, Wesley
• Application Number:
  US11/188,908
• Publication Number:
  US 20070021124A1
• Time in Patent Office: 897 Days
• Field of Search: 455/422.1, 455/418, 455/419, 455/456.1
• US Class Current: 455/456.1
• 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 a ratio of received power to transmit power;

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

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;

wherein the first plurality of nodes comprises a first plurality of reference nodes, the locations of which are known; and

wherein the second plurality of nodes comprises reference nodes, the locations of which are known, and blind nodes, the locations of which are estimate;

wherein the step of calculating the first plurality of weighting factors comprises the step of calculating a plurality of values for

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 n1 is a parameter adjustable to optimize location estimation, preferably in the range of n/1 and 3n/1, 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)=−

10log₁₀ (β

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

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

5. The method of claim 1 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.

6. The method of claim 1 wherein the step of calculating the second plurality of weighting factors comprises the step of calculating a plurality of values for

7. The method of claim 6 wherein n1 is a parameter adjustable to optimize location estimation, preferably in the range of n/1 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)=−

10log₁₀ (β

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

8. The method of claim 6 wherein the step of calculating the updated location comprises the step of calculating