Location estimation of wireless terminals in a multi-story environment

• US 20050176406A1
• Filed: 02/11/2004
• Published: 08/11/2005
• Est. Priority Date: 02/11/2004
• Status: Active Grant

• Current Assignee: Avaya Incorporated
• Original Assignee: Avaya Technology LLC (Avaya Incorporated)
• Inventors: Krishnakumar, Anjur Sundaresan, Krishnan, P.
• Granted Patent: US 7,272,394 B2
• Time in Patent Office: Days
• US Class Current: 455/410
• CPC Class Codes: G01S 5/0295 Proximity-based methods, e.g. position inferred from reception of particular signals
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method and apparatus are disclosed for estimating the location of a wireless terminal across multiple building floors. The illustrative embodiment determines the floor where the wireless terminal is presently located by using a majority logic-based heuristic. A plurality of signal monitors measure signals from the wireless terminal and provide those signal strength measurements to a location estimation server. Alternatively, the wireless terminal measures signals that are transmitted by a plurality of transmitting signal devices and provides those signal strength measurements to a location estimation server. The location estimation server determines the floor of the wireless terminal in accordance with the illustrative embodiment of the present invention.

Claims

1. A method comprising:

acquiring signal strength measurements for a signal that is received at a plurality of receivers, wherein said plurality of receivers is distributed across a plurality of zones; and

estimating which zone of said plurality of zones said signal was transmitted from based on;

(i) which zone of said plurality of zones contains a majority of the receivers that correspond to the m strongest of said signal-strength measurements; and

(ii) whether or not said zone determined in (i) contains a majority of the receivers that correspond to the m strongest of said signal-strength measurements after increasing the value of the m+1st strongest of said signal strength measurements;

wherein m is a positive integer.

2. The method of claim 1 further comprising selecting the smallest possible value for m.

3. The method of claim 1 wherein said plurality of zones corresponds to the floors of a building and said candidate zone corresponds to a particular floor of said building.

4. The method of claim 1 wherein the value of the m+1st strongest of said signal strength measurements is increased by an amount between 4 and 6 dB, inclusive.

5. The method of claim 1 wherein the value of the m+1st strongest of said signal strength measurements is increased by an amount that is dependent on the value of m.

6. An apparatus comprising:

a network interface for acquiring signal strength measurements for a signal that is received at a plurality of receivers, wherein said plurality of receivers is distributed across a plurality of zones; and

a processor for estimating which zone of said plurality of zones said signal was transmitted from based on;

(i) which zone of said plurality of zones contains a majority of the receivers that correspond to the m strongest of said signal-strength measurements; and

(ii) whether or not said zone determined in (i) contains a majority of the receivers that correspond to the m strongest of said signal-strength measurements after increasing the value of the m+1st strongest of said signal strength measurements;

wherein m is a positive integer.

7. The apparatus of claim 6 further comprising said plurality of receivers for making said signal strength measurements.

8. The apparatus of claim 6 wherein said processor is also for selecting the smallest possible value for m.

9. The apparatus of claim 6 wherein said plurality of zones corresponds to the floors of a building and said candidate zone corresponds to a particular floor of said building.

10. The apparatus of claim 6 wherein the value of the m+1st strongest of said signal strength measurements is increased by an amount between 4 and 6 dB, inclusive.

11. The apparatus of claim 6 wherein the value of the m+1st strongest of said signal strength measurements is increased by an amount that is dependent on the value of m.

12. A method comprising:

making signal strength measurements at a plurality of receivers across a plurality of zones, wherein said signal strength measurements correspond to a signal transmitted from a wireless terminal;

finding a minimum value for m, wherein m is a positive integer, such that;

(i) the majority of receivers that correspond to the m strongest-ranked signals of said signal strength measurements are located in a candidate zone within said plurality of zones; and

(ii) the majority of receivers that correspond to the m strongest-ranked signals after adding a value K to the m+1st strongest of said signal strength measurements are located in said candidate zone; and

identifying said wireless terminal as being in said candidate zone.

13. The method of claim 12 wherein said plurality of zones corresponds to the floors of a building and said candidate zone corresponds to a particular floor of said building.

14. The method of claim 12 wherein said value K is between 4 and 6 dB, inclusive.

15. The method of claim 12 wherein said value K is dependent on the value of m.

16. An apparatus comprising:

a plurality of receivers for making signal strength measurements across a plurality of zones, wherein said signal strength measurements correspond to a signal transmitted from a wireless terminal; and

a processor for;

(i) finding a minimum value for m, wherein m is a positive integer, such that;

(a) the majority of receivers that correspond to the m strongest-ranked signals of said signal strength measurements are located in a candidate zone within said plurality of zones; and

(b) the majority of receivers that correspond to the m strongest-ranked signals after adding a value K to the m+1st strongest of said signal strength measurements are located in said candidate zone; and

(ii) identifying said wireless terminal as being in said candidate zone.

17. The apparatus of claim 16 wherein said processor is also for determining the location within said candidate zone of said wireless terminal.

18. The apparatus of claim 16 wherein said plurality of zones corresponds to the floors of a building and said candidate zone corresponds to a particular floor of said building.

19. The apparatus of claim 16 wherein said value K is between 4 and 6 dB, inclusive.

20. The apparatus of claim 16 wherein said value K is dependent on the value of m.

21. A method comprising:

acquiring signal strength measurements for at least one signal, wherein the signal paths that correspond to said at least one signal traverse a plurality of zones; and

estimating at which zone of said plurality of zones a wireless terminal is present based on;

(i) which zone of said plurality of zones contains a majority of signal devices that correspond to the m strongest of said signal-strength measurements; and

(ii) whether or not said zone determined in (i) contains a majority of signal devices that correspond to the m strongest of said signal-strength measurements after increasing the value of the m+1st strongest of said signal strength measurements;

wherein m is a positive integer; and

wherein said signal devices are distributed across said plurality of zones.

22. The method of claim 21 further comprising selecting the smallest possible value for m.

23. The method of claim 21 wherein said plurality of zones corresponds to the floors of a building and said candidate zone corresponds to a particular floor of said building.