Method and system for determining position of mobile radio terminals

• US 6,064,888 A
• Filed: 11/26/1997
• Issued: 05/16/2000
• Est. Priority Date: 11/26/1997
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Grubeck, Hans, Fischer, Sven, Lundqvist, Patrik, Bergkvist, Bengt
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): Gantt, Alan T.
• Application Number:
  US08/978,912
• Time in Patent Office: 902 Days
• Field of Search: 455/456, 455/440, 455/441, 455/457
• US Class Current: 455/456.4
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• 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 and system are disclosed for determining the distance between a radio receiver (RX) and a radio transmitter (TX) by uplink time measurements, whereby uplink messages are transmitted by the transmitter (TX) and used primarily for position determination. In one embodiment, the uplink messages are intra-cell handover messages if the transmitter (TX) is a component of a mobile radio terminal which is operating in accordance with an existing TDMA standard. In a second embodiment, the uplink messages are a new type of message transmitted in time slots not used by the mobile radio terminal and preferably, also not used by other mobile radio terminals in the system, if the transmitter (TX) is a component of a mobile radio terminal which is operating in accordance with a new or emerging TDMA standard. The evolving GSM radio air-interface standard is an example of such a TDMA standard.

Claims

1. A method for use in determining a geographical position of a mobile terminal in at least a TDMA or FDMA mobile radio system, comprising the steps of:

receiving in said mobile radio system a request to determine said geographical position;

determining whether said mobile terminal is operating in a conversational mode, and if not, establishing a call with said mobile terminal;

attempting to ascertain an uplink time slot that is unused by said mobile terminal and a serving base station, and if successful, assigning said uplink time slot that is unused as a geographical position determining time slot, and if not successful, determining to interrupt unlink communication by assigning a time slot that is currently used by said mobile terminal as said geographical position determining time slot;

ordering at least one base station to listen for a transmission from said mobile terminal and to perform a measurement associated with said determining said geographical position;

sending an order from said serving base station to said mobile terminal to transmit at least one uplink signal at said geographical position determining time slot, said at least one uplink signal primarily for use in said measurement associated with said determining said geographical position;

said mobile terminal transmitting said at least one uplink signal on a frequency assigned to said serving base station and at said geographical position determining time slot; and

said at least one base station performing said measurement associated with said determining said geographical position.

2. The method of claim 1, wherein said ordering step comprises ordering at least three base stations to listen for said transmission from said mobile terminal and to each perform a measurement associated with said determining said geographical position.

3. The method of claim 1, wherein said measurement comprises a time measurement.

4. The method of claim 1, wherein said at least one uplink signal is solely for use in said measurement associated with said determining said geographical position.

10. The method of claim 1, wherein said mobile radio system comprises a TDMA system, and said at least one uplink signal is transmitted at said geographical position determining time slot, wherein said geographical position determining time slot is a time slot not used for traffic by said mobile terminal.

11. The method of claim 1, wherein the interrupted uplink communication is for mobile assisted handover (MAHO) measurements.

12. The method of claim 10, wherein said at least one uplink signal is transmitted on any frequency assigned to said serving base station.

13. The method of claim 1, wherein a start time and a stop time for said at least one uplink signal and a corresponding measurement are predetermined in order to minimize a system load.

14. The method of claim 13, wherein said start time and said stop time are defined by associated frame numbers.

5. A method for use in determining a geographical position of a mobile terminal in at least a TDMA or FDMA mobile radio system, comprising the steps of:

receiving in said mobile radio system a request to determine said geographical position;

ordering at least one base station to listen for a transmission from said mobile terminal and perform a measurement associated with said determining said geographical position;

sending an order from a serving base station to said mobile terminal to transmit at least one unlink signal, said at least one unlink signal primarily for use in said measurement associated with said determining said geographical position;

said mobile terminal transmitting said at least one uplink signal on a frequency assigned to said serving base station;

said at least one base station performing said measurement associated with said determining said geographical position; and

wherein said at least one uplink signal comprises an intra-cell handover access message.

6. The method of claim 5, wherein said intra-cell handover access message specifies a handover to an already utilized channel.

7. The method of claim 5 or 6, wherein said uplink signal comprises at least two intra-cell handover access messages responsive to a purposefully delayed acknowledgment to said uplink signal from said serving base station to said mobile terminal, said acknowledgment purposefully delayed in order for said at least one base station to receive additional uplink signals for use in performing measurements associated with said determining said geographical position.

8. The method of claim 7, wherein a purposeful delay is long enough for said mobile terminal to transmit a specified number of uplink signals, and after a time-out period, said mobile terminal reverts to a traffic channel utilized prior to said handover.

9. The method of claim 8, wherein said specified number of uplink signals is specified as a maximum number of uplink signals by a GSM radio air-interface specification.

15. A system for use in determining a geographical position of a mobile terminal in a mobile radio system, comprising:

means for receiving a request to determine said geographical position;

means for determining whether said mobile terminal is operating in a conversational mode and means for establishing a call with said mobile terminal responsive to a determination that said mobile terminal is not operating in a conversational mode by said means for determining;

means for attempting to ascertain an uplink time slot that is unused by said mobile terminal and a serving base station, and means for assigning said uplink time slot that is unused as a geographical position determining time slot responsive to ascertainment of an uplink time slot that is unused by said means for attempting to ascertain, said means for assigning determining to interrupt uplink communication and assigning a time slot that is currently used by said mobile terminal as said geographical position determining time slot responsive to a failure to ascertain an uplink time slot that is unused by said means for attempting to ascertain;

means for ordering at least one base station to listen for a transmission from said mobile terminal;

a modified receiver, coupled to said at least one base station, for performing a measurement associated with said determining said geographical position;

said serving base station operable to send an order to said mobile terminal to transmit at least one uplink signal at said geographical position determining time slot, said at least one uplink signal primarily for use in said measurement associated with said determining said geographical position; and

said mobile terminal operable to transmit said at least one uplink signal on a frequency assigned to said serving base station at said geographical position determining time slot.

16. The system of claim 15, wherein said at least one base station comprises at least three base stations.

17. The system of claim 15, wherein said measurement comprises a time measurement.

18. The system of claim 15, wherein said at least one uplink signal is solely for use in said measurement associated with said determining said geographical position.

24. The system of claim 15, wherein said mobile radio system comprises a TDMA system, and said at least one uplink signal is transmitted at said geographical position determining time slot, wherein said geographical position determining time slot is a time slot not used for traffic by said mobile terminal.

25. The system of claim 15, wherein the interrupted uplink communication is for mobile assisted handover (MAHO) measurements.

26. The system of claim 24, wherein said at least one uplink signal is transmitted on any frequency assigned to said serving base station.

27. The system of claim 15, wherein a start time and a stop time for said at least one uplink signal and a corresponding measurement are predetermined in order to minimize a system load.

28. The system of claim 27, wherein said start time and said stop time are defined by associated frame numbers.

19. A system for use in determining a geographical position of a mobile terminal in a mobile radio system, comprising:

means for receiving a request to determine said geographical position and ordering at least one base station to listen for a transmission from said mobile terminal;

a modified receiver, coupled to said at least one base station, for performing a measurement associated with said determining said geographical position;

a serving base station operable to send an order to said mobile terminal to transmit at least one unlink signal, said at least one unlink signal primarily for use in said measurement associated with said determining said geographical position;

said mobile terminal operable to transmit said at least one uplink signal on a frequency assigned to said serving base station; and

wherein said at least one uplink signal comprises an intra-cell handover access message.

20. The system of claim 19, wherein said intra-cell handover access message specifies a handover to an already utilized channel.

21. The system of claim 19 or 20, wherein said uplink signal comprises at least two intra-cell handover access messages responsive to a purposefully delayed acknowledgment to said uplink signal from said serving base station to said mobile terminal, said acknowledgment purposefully delayed in order for said at least one base station to receive additional uplink signals for use in performing measurements associated with said determining said geographical position.

22. The system of claim 21, wherein a purposeful delay is long enough for said mobile terminal to transmit a specified number of uplink signals, and after a time-out period, said mobile terminal operable to revert to a traffic channel utilized prior to said handover.

23. The system of claim 22, wherein said specified number of uplink signals is specified as a maximum number of uplink signals by a GSM radio air-interface specification.

29. A method for use in determining a geographical position of a mobile terminal in at least a TDMA or FDMA mobile radio system, comprising the steps of:

receiving in said mobile radio system a request to determine said geographical position;

ordering at least one base station to listen for a transmission from said mobile terminal and perform a measurement associated with said determining said geographical position;

sending an order from a serving base station to said mobile terminal to transmit at least one uplink signal, said at least one uplink signal primarily for use in said measurement associated with said determining said geographical position;

said mobile terminal transmitting said at least one uplink signal on a frequency assigned to said serving base station;

said at least one base station performing said measurement associated with said determining said geographical position; and

wherein said at least one uplink signal comprises a handover access message.

30. The method of claim 29, wherein said handover access message specifies a handover to an already utilized channel.

31. The method of claim 29 or 30, wherein said uplink signal comprises at least two handover access messages responsive to a purposefully delayed acknowledgment to said uplink signal from said serving base station to said mobile terminal, said acknowledgment purposefully delayed in order for said at least one base station to receive additional uplink signals for use in performing measurements associated with said determining said geographical position.

32. The method of claim 31, wherein a purposeful delay is long enough for said mobile terminal to transmit a specified number of uplink signals, and after a time-out period, said mobile terminal reverts to a traffic channel utilized prior to said handover.

33. The method of claim 32, wherein said specified number of uplink signals is specified as a maximum number of uplink signals by a GSM radio air-interface specification.

34. A system for use in determining a geographical position of a mobile terminal in a mobile radio system, comprising:

means for receiving a request to determine said geographical position and ordering at least one base station to listen for a transmission from said mobile terminal;

a modified receiver, coupled to said at least one base station, for performing a measurement associated with said determining said geographical position;

a serving base station operable to send an order to said mobile terminal to transmit at least one uplink signal, said at least one uplink signal primarily for use in said measurement associated with said determining said geographical position;

said mobile terminal operable to transmit said at least one uplink signal on a frequency assigned to said serving base station; and

wherein said at least one uplink signal comprises a handover access message.

35. The system of claim 34, wherein said handover access message specifies a handover to an already utilized channel.

36. The system of claim 34 or 35, wherein said uplink signal comprises at least two handover access messages responsive to a purposefully delayed acknowledgment to said uplink signal from said serving base station to said mobile terminal, said acknowledgment purposefully delayed in order for said at least one base station to receive additional uplink signals for use in performing measurements associated with said determining said geographical position.

37. The system of claim 36, wherein a purposeful delay is long enough for said mobile terminal to transmit a specified number of uplink signals, and after a time-out period, said mobile terminal operable to revert to a traffic channel utilized prior to said handover.

38. The system of claim 37, wherein said specified number of uplink signals is specified as a maximum number of uplink signals by a GSM radio air-interface specification.