Location applications for wireless networks

• US 20040176108A1
• Filed: 02/13/2003
• Published: 09/09/2004
• Est. Priority Date: 02/13/2003
• Status: Active Grant

• Current Assignee: AiRISTA Flow, Inc. (AiRISTA, LLC), AiRISTA International Oy (AiRISTA, LLC)
• Original Assignee: Ekahau Oy
• Inventors: Misikangas, Pauli
• Granted Patent: US 7,149,531 B2
• Time in Patent Office: Days
• US Class Current: 455/456.5
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method for locating terminals (T) in a wireless network (RN) comprising several base stations. A probabilistic model (PM) of the wireless network indicates a probability distribution (413₁-413_n) for signal values of several base stations at several locations in the wireless network. Each terminal makes a set of observations (423) of signal values of a subset of the several base stations. The terminal'"'"'s location (425) is estimated based on the probabilistic model (PM) and the set of observations. The terminal recurrently measures at least one additional item (424), which is not used for locating the terminal. Each information tuple (42) indicates the additional items (424) and the time (422) and the location (425) at which the additional items were measured. The information tuples (42) are used to determine the additional item (424) as a function (45) of time and location in the wireless network.

Claims

1. A method for locating several terminals in a wireless network comprising several base stations;

the method comprising;

maintaining a probabilistic model of the wireless network, the probabilistic model indicating a probability distribution for signal values of several base stations at several locations in the wireless network;

for each of the several terminals;

the terminal making a set of observations of signal values of a subset of said several base stations;

determining an estimate of the terminal'"'"'s location based on the probabilistic model and the set of observations;

the terminal recurrently measuring at least one additional item, wherein the at least one additional item is not used for determining the estimate of the terminal'"'"'s location;

the method further comprising;

collecting information tuples, wherein each information tuple indicates the at least one additional item and the time and the estimate of the terminal'"'"'s location at which the at least one additional item was measured;

storing and organizing the information tuples;

using the stored information tuples to determine the at least one additional item as a function of time and location in the wireless network.

2. A method according to claim 1, wherein the at least one additional item comprises a signal value of a base station that is not part of said subset.

3. A method according to claim 1, wherein the at least one additional item comprises a physical quantity unrelated to the radio network.

4. A method according to claim 1, wherein the at least one additional item comprises a quantity that cannot be measured without affecting the radio network'"'"'s operation, and said measuring comprises controlling several terminals with a common controller.

5. A method according to claim 1, wherein the at least one additional item comprises throughput in the radio network.

6. A method according to claim 4, wherein the at least one additional item is measured in response to detecting a simultaneous need and opportunity to measure the at least one additional item.

7. A method according to claim 5, wherein the step of measuring throughput comprises, in the following order:

the terminal discontinuing making the set of observations;

the terminal making a throughput measurement;

the terminal continuing making the set of observations;

inversely weighting the throughput measurement by an estimated change of the terminal'"'"'s location between the discontinuing and continuing steps.

8. A method according to claim 1, wherein the at least one additional item comprises identifiers of base stations.

9. A method according to claim 8, further comprising using the identifiers of base stations and the estimate of the terminal'"'"'s location to detect an illegitimate base station.

10. A method according to claim 1, wherein the step of maintaining the probabilistic model of the wireless network comprises physically measuring signal values of several base stations at several locations in the wireless network.

11. A method according to claim 1, wherein the step of maintaining the probabilistic model of the wireless network comprises calculating signal values of several base stations at several locations based on a propagation model of the wireless network.

12. A method according to claim 1, further comprising:

determining multiple device models that compensate for the differences between different terminals'"'"' observations of the at least one signal quality value; and

for each terminal, selecting a device model among the multiple device models, and processing the observations made by the terminal with the selected device model.

19. A computer program product embodying computer instructions, wherein executing the computer instructions in a computer arrangement functionally connected to a wireless network serving terminals causes the computer arrangement, the wireless network and the terminals to perform the steps of claim 1.

13. An arrangement for locating several terminals in a wireless network comprising several base stations;

the arrangement comprising;

a probabilistic model of the wireless network, the probabilistic model indicating a probability distribution for signal values of several base stations at several locations in the wireless network;

a location calculation module for determining an estimate of each terminal'"'"'s location based on the probabilistic model and a set of observations made by the terminal in question, wherein the set of observations indicates signal values of a subset of said several base stations;

control means for;

receiving from each of the several terminals at least one additional measured item, wherein the at least one additional item is not used for determining the estimate of the terminal'"'"'s location;

storing information tuples, wherein each information tuple indicates the at least one additional item and the time and the estimate of the terminal'"'"'s location at which the at least one additional item was measured; and

for

using the stored information tuples to determine the at least one additional item as a function of time and location in the wireless network.

14. An arrangement according to claim 13, wherein the control means comprises a controller for coordinating measurements of several terminals.

15. An arrangement according to claim 14, wherein the at least one additional item comprises throughput in the radio network.

16. An arrangement according to claim 15, wherein the controller is operable to order a terminal to perform the following acts:

discontinue of making the set of observations;

perform a throughput measurement;

continue making the set of observations;

and the arrangement is operable to inversely weigh the throughput measurement by an estimated change of the terminal'"'"'s location between the discontinuing and continuing acts.

17. An arrangement according to claim 14, wherein the at least one additional item comprises identifiers of base stations.

18. An arrangement according to claim 13, wherein the arrangement further comprises multiple device models that compensate for the differences between different terminals'"'"' observations of the at least one signal quality value;

and

the arrangement is operable to select, for each terminal, a device model among the multiple device models, and to process the observations made by the terminal with the selected device model.