Method and apparatus for positioning a set of terminals in an indoor wireless environment

• US 20060205417A1
• Filed: 03/10/2005
• Published: 09/14/2006
• Est. Priority Date: 03/10/2005
• Status: Active Grant

• Current Assignee: Avaya Incorporated
• Original Assignee: Avaya Incorporated
• Inventors: Krishnakumar, Anjur S., Krishnan, P., Ju, Wen-Hua, Madigan, David
• Granted Patent: US 7,403,784 B2
• Time in Patent Office: Days
• US Class Current: 455/456.500
• CPC Class Codes: G01S 2205/02 Indoor
• CPC Class Codes: G01S 5/0252 Radio frequency fingerprinting
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Methods and apparatus are provided for estimating a location of a plurality of wireless terminals. Signal strength measurements are obtained for at least one packet transmitted by each of the wireless terminals; and a Bayesian algorithm is applied to the signal strength measurements to estimate the location of each wireless terminal. In an infrastructure-based deployment, signal strength measurements are obtained from one or more signal monitors. In a client-based model, signal strength measurements are obtained from a client associated with a respective wireless terminal.

Claims

1. A method for estimating a location of a plurality of wireless terminals, comprising:

obtaining signal strength measurements associated with a plurality of wireless terminals; and

applying a Bayesian algorithm to said signal strength measurements to estimate said location of said plurality of wireless terminals.

2. The method of claim 1, wherein said signal strength measurements are obtained from one or more signal monitors that use measurements from at least one packet transmitted by each of said plurality of wireless terminals.

3. The method of claim 1, wherein said signal strength measurements are obtained from a client associated with a respective wireless terminal, said client using measurements from at least one packet transmitted by an access point.

4. The method of claim 1, further comprising the step of forming one or more vectors of signal strength measurements that are applied to said Bayesian algorithm.

5. The method of claim 1, wherein said Bayesian algorithm implements a non-hierarchical Bayesian model.

6. The method of claim 1, wherein said Bayesian algorithm implements a hierarchical Bayesian model.

7. The method of claim 1, wherein said Bayesian algorithm implements a Bayesian model that decays said signal strength measurements approximately linearly with log distance.

8. The method of claim 1, wherein said Bayesian algorithm implements a Bayesian model that employs similar coefficients of linear regression models corresponding to a plurality of access points.

9. The method of claim 1, wherein said Bayesian algorithm implements a Bayesian model that employs prior knowledge that a plurality of access points behave in a similar manner.

10. The method of claim 1, wherein said Bayesian algorithm implements a Bayesian model that employs a corridor main effect that indicates whether one or more of said wireless terminals are likely in a same corridor as an access point.

11. The method of claim 1, wherein said Bayesian algorithm implements a Markov chain Monte Carlo algorithm.

12. An apparatus for estimating a location of a plurality of wireless terminals, comprising:

a memory; and

at least one processor, coupled to the memory, operative to;

obtain signal strength measurements associated with a plurality of wireless terminals; and

apply a Bayesian algorithm to said signal strength measurements to estimate said location of said plurality of wireless terminals.

13. The apparatus of claim 12, wherein said signal strength measurements are obtained from one or more signal monitors that use measurements from at least one packet transmitted by each of said plurality of wireless terminals.

14. The apparatus of claim 12, wherein said signal strength measurements are obtained from a client associated with a respective wireless terminal, said client using measurements from at least one packet transmitted by an access point.

15. The apparatus of claim 12, wherein said Bayesian algorithm implements a Bayesian model that decays said signal strength measurements approximately linearly with log distance.

16. The apparatus of claim 12, wherein said Bayesian algorithm implements a Bayesian model that employs similar coefficients of linear regression models corresponding to a plurality of access points.

17. The apparatus of claim 12, wherein said Bayesian algorithm implements a Bayesian model that employs prior knowledge that a plurality of access points behave in a similar manner.

18. The apparatus of claim 12, wherein said Bayesian algorithm implements a Bayesian model that employs a corridor main effect that indicates whether one or more of said wireless terminals are likely in a same corridor as an access point.

19. The apparatus of claim 12, wherein said Bayesian algorithm implements a Markov chain Monte Carlo algorithm.

20. An article of manufacture for estimating a location of a plurality of wireless terminals, comprising a machine readable medium containing one or more programs which when executed implement the steps of:

obtaining signal strength measurements associated with a plurality of wireless terminals; and

applying a Bayesian algorithm to said signal strength measurements to estimate said location of said plurality of wireless terminals.