Mobile station position tracking system for public safety

• US 6,421,009 B2
• Filed: 05/08/1998
• Issued: 07/16/2002
• Est. Priority Date: 05/08/1998
• Status: Expired due to Term

• Current Assignee: Suprunov, Peter
• Original Assignee: Suprunov, Peter
• Inventors: Suprunov, Peter
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US09/074,610
• Publication Number:
  US 20020005804A1
• Time in Patent Office: 1,530 Days
• Field of Search: 342/457, 342/450, 342/463, 342/465, 455/456, 455/521, 455/404, 455/434, 455/461, 455/426, 375/34, 375/35, 375/45, 379/38
• US Class Current: 342/465
• CPC Class Codes: H01Q 1/3233 particular used as part of a sensor or in a security system, e.g. for automotive radar, navigation systems
• CPC Class Codes: H01Q 21/06 Arrays of individually energised antenna units similarly polarised and spaced apart

Abstract

A system for determining the location of a mobile station in a cellular communications network, comprising a plurality of locator units fixedly positioned for tracking and measuring communications between a base station and a mobile station initiating an emergency communication, each locator unit comprising a receiving means for monitoring a control channel of the base station for detecting and receiving identifying information including an assigned voice channel associated with the particular mobile station initiating said emergency communication, a storage means for storing the identifying information associated with the to emergency communication, a controller means for tuning the receiving means to the assigned voice channel associated with the emergency communication for receiving voice and control channel data between the base station and the mobile station, a transmission means operable in a first mode responsive to the receiving means and the controller means for initiating a second communication to a monitor unit based on the stored identifying information, the second communication occurring further including data indicative of the signal strength as a function of distance of the mobile station relative to the particular locator unit, wherein the monitor unit is responsive to the plurality of locator units for receiving the second communication from each locator unit and determining and tracking the position of the mobile station based on the received signal strengths and the known positions of the fixed locator units.

Claims

1. A local area direct law enforcement emergency notification system for determining the position of a mobile station in a cellular communications network, comprising:

at least three independent locator units installed in each cell and fixedly positioned for tracking and measuring communications between a base station and said mobile station initiating an emergency communication, each said locator unit comprising;

omni directional receiving means for monitoring control channels of said base station for detecting and receiving mobile station identifying information including an assigned voice channel associated with said particular mobile station initiating said emergency communication;

storage means for storing said identifying information associated with said emergency communication;

controller means for tuning said omni directional receiving means to the assigned voice channel associated with said emergency communication for receiving voice and control channels data between said base station and said mobile station;

omni directional transmission means operable in a first mode responsive to said omni directional receiving means and said controller means for initiating a second, direct communication to at least one independent portable monitor unit based on said stored identifying information, said second communication further including data indicative of the signal strength of said mobile station relative to said particular locator unit;

wherein at least one said independent portable monitor unit is responsive to said plurality of independent locator units for receiving said second communication from each said locator unit and determining and tracking the position of said mobile station based on said received signal strengths and the known position of said fixed independent locator units.

2. The local area emergency service system according to claim 1, wherein said omni directional transmission means is operable in a second mode for initiating a third communication to at least one said independent portable monitor unit voice information and signal strength data received via said omni directional receiving means tuned to said assigned voice channel of said emergency communication from said mobile station.

3. The local area emergency service system according to claim 2, wherein at least one said independent portable monitor unit includes detection means responsive to the second communication from each said locator unit for determining the locator unit transmission having the strongest signal strength, said detection means also operable for determining the position of the mobile station by association of the relative position of each of the independent locator units within the cell and the corresponding signal strength as a function of distance of the signal detected by said omni directional receiving means.

4. The local area emergency service system according to claim 3, wherein at least one said independent portable monitor unit further includes display means including a map of the cell areas for displaying the position of said mobile station on the map and identifying information of a user associated with said mobile station onto a display.

5. The local area emergency service system according to claim 4, at least one said independent portable monitor unit further including speaker means for providing audible voice information received from said locator unit omni directional transmission means.

6. The local area emergency service system according to claim 5, at least one said independent portable monitor unit further including means for determining changes in signal strength from said locator unit having the highest transmitted signal strength and operable in response to a change in said highest signal strength exceeding a predetermined variation threshold for initiating a fourth communication to said plurality of independent locator units for obtaining new signal strength data in order to calculate a new position associated with said mobile station.

7. The local area emergency service system according to claim 6, wherein said fourth communication initiated over a Reverse Control Channel.

8. The local area emergency service system according to claim 1, wherein each said locator unit is fixedly positioned an equal distance between the center of the cell and the perimeter of the cell.

9. The local area emergency service system according to claim 1, wherein said identifying information further includes a MIN number associated with said mobile station, signal strength of said mobile station, and wherein second communication further includes said particular locator unit'"'"'s identification number.

10. A method for determining the location of mobile station in a cellular communication network with direct delivery of emergency information to an appropriate law enforcement agency, said method comprising the steps of:

monitoring within a cellular cell via a plurality of omnidirectional fixed positioned independent locator units LDPs with omnidirectional transmitting and receiving, a control channel of a particular cell in said cellular network for an emergency communication between a mobile station and a base station;

upon detection of said emergency communication, recording set-up call information associated with emergency call between said mobile station and said base station;

measuring signal strength of the emergency communication;

broadcasting a second communication from said plurality of fixed positioned independent locator units to the appropriate law enforcement agency in response to said detection, said second communication including the set-up call information associated with said first emergency communication, and the measured signal strength of said mobile station as a function of distance from each of said plurality of fixed positioned independent locator units;

directly receiving said second communication at said law enforcement agency; and

determining the position of said mobile station based on a comparison of the signal strengths associated with said second communication from each of said plurality of fixed positioned independent locator units.

11. The method according claim 10, further comprising providing a data base of pre-stored user identification data associated with a portion of said setup call information included in said emergency communication;

and

retrieving said user identification data indicative of a particular user associated with said mobile station in response to said second communication for displaying said retrieved user identification data and said mobile station position onto a display terminal.

12. The method according claim 11, further comprising the step of:

determining from said plurality of fixed position sources the source having the highest signal strength associated with said second communication indicative of the strength of said mobile station as a function of distance from said fixed source; and

terminating communication with and releasing all other said fixed position sources.

13. The method according claim 12, further comprising the steps of:

originating a third communication from monitor units to said LDP-source having said highest signal strength and receiving voice and signal strength data from that LDP-source associated with the emergency communication from said mobile station.

14. The method according claim 13, further comprising the steps of:

periodically sampling the signal strength associated with said fixed position source having the highest signal strength and comparing with a predetermined threshold; and

calculating a new position of said mobile station by originating a third communication to each of said plurality of fixed position LDP'"'"'s-sources to provide a new measurement of the signal strength of said mobile station as a function of distance from said respective fixed position LDP'"'"'s.

15. The method of claim 14, wherein said plurality of fixed position LDP'"'"'s are equally spaced between a center of the particular cell and the perimeter of said cell.

16. The method according claim 15, wherein said setup call information includes MIN number, assigned voice channel, and signal strength of said mobile station.

17. The method according claim 16, wherein said second communication further includes an identification number associated with said particular fixed position LDP'"'"'s.

18. The method according claim 17, further comprising the step of controlling the switching between the monitoring, receiving and transmission of said emergency and said second and third communication for each of said plurality of said fixed position LDP'"'"'s.

19. An independent local area emergency service system for determining the position of a mobile station in a cellular network comprising at least three independent locator units with omni directional antennas installed in each cell, each said locator unit is fixedly positioned in said same particular cell of said network, and said locator units are positioned (at) an equal distance between said base station and the periphery of said cell border for tracking and measuring emergency communication between said base station and said mobile station initiating an emergency cellular telephone call, each said locator unit comprising:

a first receiver for monitoring a Reverse Control Channel for emergency call detecting and receiving identifying information including an assigned voice channel and MIN number associated with said emergency telephone call from the particular mobile station;

memory for storing the identifying information associated with said emergency telephone call;

a second receiver for monitoring a Forward Control Channel for tuning said first receiver to a mobile station assigned voice channel;

a transmitter responsive to both the first and second receivers and operable in a first mode for broadcasting a second communication signal to at least one independent portable monitor unit based on the identifying information, and including data indicative of the signal strength of the mobile station relative to said particular locator unit, and in a second mode responsive to at least one said portable monitor unit for broadcasting a third communication including voice and signal strength data via said assigned voice channel, and wherein the monitor unit is responsive to the three independent locator units in said first mode for receiving the second communication including signal strength and identifying information and determining the position of said mobile station based on the received signal strengths and known positions of the fixed independent locator units, and in said second mode, the monitor unit selecting the said locator unit having the highest signal strength of said plurality of independent locator units for receiving said third communication of voice and data; and

wherein said at least one said independent portable monitor unit includes a computer console and data base containing information associated with said mobile station such that upon receipt of said identifying information, additional information retrieved from said data base is displayed on said console in addition to said position of said mobile station and said voice communication.