Wireless communication system and method and system for detection of position of radio mobile station

• US 6,140,964 A
• Filed: 03/18/1997
• Issued: 10/31/2000
• Est. Priority Date: 03/22/1996
• Status: Expired due to Term

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kubo, Toru, Yamaguchi, Kazuaki, Oka, Natsuki, Sugiura, Masataka, Ishibashi, Hiroyoshi, Kanaya, Etsumi
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/819,985
• Time in Patent Office: 1,323 Days
• Field of Search: 342/450, 342/451, 342/457, 342/463, 342/464, 342/465, 342/360, 455/456
• US Class Current: 342/464
• CPC Class Codes: G01S 1/026 of associated receivers
• CPC Class Codes: G01S 5/02521 using a radio-map
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method of detecting a position of a radio mobile station in radiocommunications, which is capable of accurately and simply finding the position of the mobile station. At a measuring point the mobile station measures the reception radio strength levels from a plurality of base stations and conveys the measurement results through the base station to a control station. The control station learns, through a neural network, the correlation between the reception radio strength levels and the position of the mobile station on the basis of the measurement results at a plurality of measuring points and the positions of the measuring points. Subsequently, when the mobile station communicates to the control station the reception radio strength levels measured at an arbitrary point, the control station estimates the position of the mobile station, causing those measurement results, on the basis of the correlation obtained through the learning.

Claims

1. A method of detecting a position of a particular mobile station in a radio communication system including at least the mobile station, a plurality of base stations and a control station, said method comprising the steps of:

measuring only reception strength levels of radio signals from said plurality of base stations at a plurality of measuring points using at least one mobile station of said radio communication system;

transmitting a result of the measurement from said at least one mobile station to said control station through one of said base stations;

performing a learning operation in said control station through a neural network, to learn a correlation between said strength levels of said radio signals and the position of said at least one mobile station on the basis of said measurement results at said plurality of measuring points and on the basis of position data of said measuring points,

said neural network having a plurality of input layer nodes corresponding in number to the number of said base stations so that each of said input layer nodes corresponds to one of said base stations,

said neural network having output layer nodes whose number is sufficient for indicating positional information whereby said neural network learns such that said neural network outputs positional information of said respective measuring points when receiving said reception strength levels at each of said base stations corresponding to each of said respective nodes of said input layer with respect to all of said measuring points;

conveying measurement results of strength levels of said radio signals from each of said plurality of base stations, measured by said particular mobile station at an arbitrary point, to said control station through one of said base stations; and

estimating by said control station a position of said particular mobile station which has provided said measurement results, on the basis of said correlation between said strength levels of said radio signal and a position of said at least one mobile station attained through the learning operation.

2. A position detection method as defined in claim 1, wherein said measuring points are determined in advance and each of said mobile stations measures reception radio strength levels from said plurality of base stations at its own corresponding measuring point.

3. A position detection method as defined in claim 1, wherein said measuring points are spots at which chargers are located to charge said mobile station, comprising the further steps of:

storing an ID in each of said chargers;

reading said ID by said particular mobile station or by said another mobile station when such a mobile station is connected to said charger,

reporting said ID by said mobile station to said control station through one of said base stations,

obtaining a position of said charger as a measuring point by said control station using said ID reported by said mobile station,

and using said position of said charger as said position data of said mobile station.

4. A position detection method as defined in claim 1, wherein said mobile station conveys positional data of said measuring point and said reception radio strength levels from said plurality of base stations, measured at said measuring point, through said base station to said control station.

5. A position detection method as defined in claim 1, wherein said mobile station measures reception radio strength levels from said plurality of base stations plural times at one of the same measuring point and an arbitrary point and statistically processes a plurality of resultant measurement values to obtain a single value and outputs it as a final measurement result.

6. A position detection method as defined in claim 1, further comprising the step of transmitting the position estimated by said control station from said control station to said particular mobile station, when said mobile station transmits a result of measurement obtained at said arbitrary point to said control station.

7. A position detection method as defined in claim 1, wherein, when said mobile station inquires to said control station for a position of a different mobile station, said control station gives instructions to said different mobile station to measure and report reception radio strength levels due to said plurality of base stations and estimates a position of said different mobile station on the basis of the reported measurement results to convey the estimation result to said mobile station.

8. A position detection method as defined in claim 1, wherein said control station successively stores the estimation results on the position of said mobile station and estimates a position of said mobile station on the basis of new measurement results, and further decides, on the basis of the past positions of said mobile station, whether the estimated position of said mobile station is appropriate or not, and, if not appropriate, gives instructions to said mobile station to again perform the measurement.

9. A position detection method as defined in claim 8, wherein said mobile station measures reception radio strength levels from said plurality of base stations at a constant time interval and conveys the measurement results through said base station to said control station.

10. A position detection method as defined in claim 1, comprising the further step of using a region with an expansion including a room or district where said mobile station exists as said position of said particular mobile station.

11. A mobile station radio communication system comprising:

a mobile station, a plurality of base stations and a control station,

said control station detecting a position of said mobile station, wherein;

said mobile station includes radio signal strength measuring means for measuring strength levels of said radio signal from each of said plurality of base stations, and

said control station includes;

position input means for inputting positions of a plurality of measuring points;

position learning processing means for learning, through a neural network, a correlation between said strength levels of said radio signals measured by said mobile station at each of said plurality of measuring points and the positions of said plurality of measuring points inputted through said position input means,

said neural network having a plurality of input layer nodes corresponding in number to the number of said base stations so that each node corresponds to one of said base stations,

said neural network having output layer nodes whose number is sufficient for indicating positional information whereby said neural network learns such that said neural network outputs positional information of said respective measuring points when receiving reception strength levels at each of said base stations corresponding to each of said respective nodes of said input layer with respect to all of said measuring points; and

position estimation processing means for estimating a position of said mobile station at the measuring time, on the basis of strength levels of said radio strength from each of said plurality of base stations measured by said mobile station at an arbitrary point, by using correlation learned by said position learning processing means.

12. A mobile station radio communication system as defined in claim 11, further comprising a charger for charging said mobile station placed at the position of each of said measuring points,

wherein each of said chargers stores an ID so that said ID is read by said mobile station when said mobile station is connected to said charger,

said mobile station is arranged to report said ID to said control station through one of said base stations, and

said control station is arranged to obtain position of said charger as a measuring point using said ID reported from said mobile station,

said position of said charger being used as position data of said mobile station.

13. A mobile station radio communication system as defined in claim 11, further comprising a learning data collector located at the position of said measuring point,

said learning data collector including:

radio signal strength measuring means for measuring strength levels of radio signals from each of said plurality of base stations and transmission and reception means for reporting said strength levels through said base station to said control station and further for receiving a control signal from said control station.

14. A mobile station radio communication system as defined in claim 11, wherein said control station further includes radio strength report requesting means for transmitting a radio strength report requesting message to said mobile station so that said mobile station measures radio strength levels from said plurality of base stations and reports the measurement results.

15. A mobile station radio communication system as defined in claim 11, wherein said mobile station comprises a self mobile station position inquiring means for issuing a radio signal strength measurement request to said radio signal strength measuring means, and when said control station receives strength levels measured by said radio signal strength measuring means, said control station estimates a position of said mobile station and reports the estimation result to said mobile station.

16. A mobile station radio communication system as defined in claim 14, wherein said mobile station is equipped with a different mobile station position inquiring means for transmitting a request for inquiry for a position of a different mobile station to said control station, and when said control station receives said request therefrom, said radio strength report requesting means transmits said radio strength report requesting message to said different mobile station undergoing the position inquiry, and in response to a report of measurement results on radio strength levels from said different mobile station, said control station estimates a position of said different mobile station on the basis of the reported measurement results and reports the estimation result to said mobile station that makes said inquiry.

17. A mobile station radio communication system as defined in claim 14, wherein said control station includes position accumulation means for accumulating information on positions of said mobile station estimated by said position estimating processing means, in time series, and history decision means for deciding, on the basis of a change of the position of said mobile station accumulated in said position accumulation means with time, whether the position of said mobile station estimated by said position estimation processing means is or is not appropriate, and when said history decision means decides that the estimated position is not appropriate, said radio signal strength report requesting means issues a radio signal strength report requesting message to said mobile station for renewing radio signal strength information.

18. A wireless radiocommunication system as defined in claim 11, wherein said mobile station is equipped with at least two frequency synthesizers so that, even if one frequency synthesizer is in a synchronized condition with a communication carrier at a call, said radio strength measuring means uses the other frequency synthesizer to measure radio strength levels from said plurality of base stations.

19. A mobile station radio communication system as defined in claim 11, wherein the number of said output layer nodes corresponds to a number of areas defining a range of positions being detected and said control station uses said neural network to learn a correlation between said reception radio strength levels and said areas in which said mobile station is situated.

25. A mobile station radio communication system as defined in claim 11, wherein said mobile station comprises learning result sotrage means for storing parameters of a neural network conveyed from said control station and a position calculation means for constructing a neural network using said parameters stored in said learning result storage means to detect, through the constructed neural network, its own position on the basis of reception radio signal strength levels from said plurality of base stations measured at an arbitrary point.

20. A mobile station radio communication system comprising:

a mobile station, a plurality of base stations and a control station, and a control station,

said control station detecting a position of said mobile station, wherein;

said mobile station includes radio signal strength measuring means for measuring strength levels of said radio signal from each of said plurality of base stations, and

said control station includes;

position storage means for storing data indicative of a position of each of a plurality of measuring points and an ID of said mobile station, said position storage means storing said data in correspondence with each of said measuring points;

position learning processing means for learning, through a neural network, a correlation between said strength levels of said radio signals corresponding to each of said measuring points and the positions of said plurality of measuring points inputted through said position input means,

said neural network having a plurality of input layer nodes corresponding in number to the number of said base stations so that each node corresponds to one of said base stations,

said neural network having output layer nodes whose number is sufficient for indicating positional information whereby said neural network learns such that said neural network outputs positional information of said respective measuring points when receiving reception strength levels at each of said base stations corresponding to each of said respective nodes of said input layer with respect to all of said measuring points; and

position estimation processing means for estimating a position of said mobile station at the measuring time, on the basis of strength levels of said radio strength from each of said plurality of base stations measured by said mobile station at an arbitrary point, by using correlation learned by said position learning processing means.

21. A method of detecting the position of a mobile station in a radio communication system including at least the mobile station, a plurality of base stations and a control station, said method comprising the steps of:

determining a plurality of measuring points in advance, said measuring points being distributed as evenly as practicable over an area in which said plurality of base stations are located;

measuring at each measuring point only a strength of a radio signal from one or more of said base stations where reception is available, and recording the measurement result in combination with positional information of the measuring points;

forming a neural network for learning correlations between measurement results at respective measuring points and the positional information thereof so that said neural network outputs positional information of said measuring points in receipt of said result of measurement,

providing said neural network a number of input layer nodes corresponding in number to the number of said base stations so that each node corresponds to one of said base stations,

providing said neural network a plurality of output layer nodes whose number is sufficient for indicating positional information whereby said neural network learns such that said neural network outputs positional information of said respective measuring points when receiving reception strength levels at each of said base stations corresponding to each of said respective nodes of said input layer with respect to all of said measuring points;

measuring at one or more unknown points a strength of a radio signal from one or more base stations when said mobile station is within said area; and

inputting said radio signal strength obtained in said step of measuring at one or more unknown points to said neural network so as to determine a position of said mobile station.

22. A radio communication system comprising at least one mobile station, a plurality of base stations and a control station adapted to determine a position of a mobile station, a plurality of measuring points being determined in advance, said measuring points being distributed as evenly as practicable over an area in which said plurality of base stations are located, said system comprising:

first measuring means for measuring at each of said measuring points only a strength level of a radio signal from one or more of said base stations where reception is available;

means for recording the measurement result in combination with positional information of the measuring points, said positional information being inputted in advance;

means for forming a neural network to learn a correlation between said strength levels of said radio signals and the position of said mobile station on the basis of said measurement results at said plurality of measuring points and on the basis of position data of said measuring points,

said neural network having a plurality of input layer nodes corresponding in number to the number of said base stations so that each of said input layer nodes corresponds to one of said base stations,

said neural network having output layer nodes whose number is sufficient for indicating positional information whereby said neural network learns such that said neural network outputs positional information of said respective measuring points when receiving reception strength levels at each of said base stations corresponding to each of said respective nodes of said input layer with respect to all of said measuring points;

second measuring means for measuring at one or more unknown points a strength of a radio signal from one or more base stations when said mobile station is within said area; and

means for inputting to said neural network said strength of said radio signal obtained by said second measuring means so as to o determine a position of said mobile station.

23. A method of detecting a position of a particular mobile station in a radio communication system including at least the mobile station, a plurality of base stations and a control station, said method comprising the steps of:

measuring only reception strength levels of radio signals from said plurality of base stations at a plurality of measuring points using at least one mobile station of said radio communication system;

transmitting a result of the measurement from said at least one mobile station to said control station through one of said base stations;

converting said reception strength levels of said radio signals transmitted from said at least one mobile station into theoretical distances between said base stations and said at least one mobile station;

performing a learning operation in said control station through a neural network, to learn a correlation between said theoretical distances and the position of said at least one mobile station on the basis of said measurement results at said plurality of measuring points and on the basis of position data of said measuring points,

said neural network having a plurality of input layer nodes corresponding in number to the number of said base stations so that each node corresponds to one of said base stations,

said neural network having output layer nodes whose number is sufficient for indicating positional information whereby said neural network learns such that it will output positional information of said respective measuring points when receiving said theoretical distance at each of said base stations corresponding to each of said respective nodes of said input layer with respect to all of said measuring points;

conveying measurement results of strength levels of said radio signals, from each of said plurality of base stations, as measured by said particular mobile station at an arbitrary point, to said control station through one of said base stations; and

estimating by said control station a position of said particular mobile station which has provided said measurement results, on the basis of said correlation between said strength levels of said radio signal and a position of said at least one mobile station attained through the learning operation.

24. A mobile station radio communication system comprising:

at least one mobile station, a plurality of base stations and a control station,

said control station detecting a position of a mobile station, wherein;

said mobile station includes radio signal strength measuring means for measuring reception strength levels of said radio signal from each of said plurality of base stations, and

said control station includes;

position input means for inputting positions of a plurality of measuring points;

means for converting said reception strength levels of said radio signals transmitted from said mobile station into theoretical distances between said base stations and said mobile station;

position learning processing means for learning, through a neural network, a correlation between said strength levels of said radio signals measured by said mobile station at each of said plurality of measuring points and the positions of said plurality of measuring points inputted through said position input means,

said neural network having a plurality of input layer nodes corresponding in number to the number of said base stations so that each node corresponds to one of said base stations,

said neural network having output layer nodes whose number is sufficient for indicating positional information whereby said neural network learns such that said neural network outputs positional information of said respective measuring points when receiving said theoretical distance at each of said base stations corresponding to each of said respective nodes of said input layer with respect to all of said measuring points; and

position estimation processing means for estimating a position of said mobile station at the measuring time, on the basis of strength levels of said radio strength from each of said plurality of base stations measured by said mobile station at an arbitrary point, by using correlation learned by said position learning processing means.