Method and an arrangement relating to telecommunication systems

• US 5,960,355 A
• Filed: 02/10/1997
• Issued: 09/28/1999
• Est. Priority Date: 02/16/1996
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hedlund, Anders, Ekman, Kenneth, Ghisler, Walter, Lundqvist, Rikard
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Bhattacharya, Sam
• Application Number:
  US08/799,039
• Time in Patent Office: 960 Days
• Field of Search: 455/422, 455/456, 455/457, 455/435, 455/502, 455/503, 455/517, 455/524, 342/450, 342/452, 342/457, 701/207
• US Class Current: 455/456.1
• CPC Class Codes: G01S 1/022 Means for monitoring or calibrating
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

The present invention teaches a method, system, terminals and service node for geographically positioning a first mobile radio terminal (MS1) within a radio network (100) comprising unsynchronised radio base stations by using a plurality of second fixed radio terminals (MS2) whereby the positions of the radio base stations and the second fixed radio terminals are known. First and second radio terminals (MS1,MS2) measure the relative receive times between the timing signals downlink (113-118) received from at least three radio base stations (BS1,BS2,BS3) and the second fixed radio terminals (MS2)send them to a service node (107) in the network (100) using them for calculating the transmission time offsets of the timing signals downlink. Calculating the position of the first mobile radio terminal (MS1) is performed either in the service node (107) in the network (100) or in the terminal (MS1) itself, after respectively sending relative receive time measurements from the first mobile radio terminal (MS1) to the service node (107), or broadcasting transmission time offset values and known positions from the service node (107) to the first radio terminal (MS1) to be positioned.

Claims

1. A method for determining a geographical position of a first mobile radio terminal in a mobile radio system comprising at least three radio base stations at least a second radio terminal at a fixed position and a service node in which are stored the known positions of said at least three radio base stations and said at least one second radio terminal comprising the following steps:

synchronising said second radio terminal to timing signals downlink received from a first one of said at least three radio base stations;

measuring at said second radio terminal relative receive times of said timing signals downlink received from remaining radio base stations while also reading identities of said at least three radio base stations;

sending the relative receive times measured at said second radio terminal and associated radio base station identities to said service node;

calculating at said service node transmission time offsets of said timing signals downlink from said relative receive times and said known positions;

synchronising said first mobile radio terminal to timing signals downlink received from an arbitrary one among said at least three radio base stations;

measuring at said first mobile radio terminal relative receive times of said timing signals downlink received from remaining radio base stations while also reading said at least three radio base station'"'"'s identity;

sending the relative receive times measured at said first radio terminal and associated radio base station identities to said service node;

calculating at said service node the position of said first mobile radio terminal from said stored positions and from measurements and identities sent from said first and second radio terminals to said service node.

2. A method according to claim 1, including the following additional steps:

repeating at intervals the step of measuring the relative receive times at said second radio terminal;

time stamping said measurements at said second mobile radio terminal;

sending said time-stamping of said measurements to said service node;

extrapolating transmission time offsets to the actual time of the calculation by making use of said time stamping said measurements and of the time elapsed since said measurements were made.

3. A method according to claim 1, whereby said second radio terminal is located at one of said at least three radio base stations.

4. A method according to claim 1, whereby said service node is a service node in the wire-bound part of the network and handles the calculation for a plurality of mobile radio terminals.

5. A method according to claim 4, whereby said service node sends results of the calculations to the first mobile radio terminal.

6. A method according to claim 1, comprising the step of synchronising a mobile radio terminal to a serving radio base station, comprising the sub-steps of:

resetting a counter in said mobile radio terminal thereby synchronising to said serving radio base station;

storing the reset value of said counter in said mobile radio terminal;

reading in said mobile radio terminal on the synchronisation channel SCH of said serving radio base station the radio base station identity and the current frame number.

7. A method according to claim 1, comprising the step of measuring at said radio terminal relative receive times of the timing signals downlink of other radio base stations than said serving radio base station comprising the sub-steps of:

storing the value of a counter in said mobile radio terminal at the instant the frame of said other radio base station begins;

reading in said mobile radio terminal on the synchronisation channel SCH of said other radio base station the radio base station identity and the current frame number;

deciding if more other radio base stations are to be measured and if so loop back to the sub-step of storing.

8. A method according to claim 1, improving the accuracy of positioning by the steps of:

checking after a first execution of the positioning method whether there are any radio base stations in the network which may yield a more accurate positioning than the at least three radio base stations used in said first execution of the positioning and whether more accurate positioning is desirable;

performing, if indicated by the previous step of checking, a further execution of the positioning method using at least one radio base station identified in the previous step of checking.

9. A method according to claim 1, in the case the land system has no information about the identity of the serving radio base station associated with a terminal to be positioned, providing the steps of:

sending a message to the mobile radio terminal to be positioned;

receiving from said mobile radio terminal to be positioned an answer via its serving radio base station the answer identifying said serving radio base station.

10. A method for determining a geographical position of a first mobile radio terminal in a mobile radio system comprising at least three radio base stations at least a second radio terminal at a fixed position, a service node in which are stored the known positions of said at least three radio base stations and said at least one second radio terminal and an accessory associated with said first mobile radio terminal comprising the following steps:

synchronising said second radio terminal to timing signals downlink received from a first one of said at least three radio base stations;

measuring at said second radio terminal relative receive times of said timing signals downlink received from remaining radio base stations while also reading said at least three radio base station'"'"'s identity;

sending the relative receive times measured at said second radio terminal and associated radio base station identities to said service node;

calculating at said service node transmission time offsets of said timing signals downlink from said relative receive times and said known positions;

broadcasting the known positions of said at least three radio base stations and said respective transmission time offsets provided in the previous step of calculating;

receiving said known positions and respective transmission time offsets of the previous step of broadcasting in said accessory of said first mobile radio terminal;

synchronising said first radio terminal to timing signals downlink received from an arbitrary one among said at least three radio base stations;

measuring at said first mobile radio terminal relative receive times of said timing signals downlink received from remaining radio base stations while also reading said at least three radio base station'"'"'s identity;

transferring the relative receive times measured at said first radio terminal and associated radio base station identities to said accessory of said first radio terminal;

calculating in said accessory the position of said first mobile radio terminal from the information provided in the steps of receiving and transferring.

11. A method according to claim 10, including the following additional steps:

repeating at intervals the step of measuring the relative receive times at said second radio terminal;

time stamping said measurements at said second mobile radio terminal;

sending said time-stamping of said measurements to said service node;

extrapolating transmission time offsets to the actual time of the calculation by making use of said time stamping said measurements and of the time elapsed since said measurements were made.

12. A method according to claim 10, whereby said second radio terminal is located at one of said at least three radio base stations.

13. A method according to claim 10, hereby said service node is a service node in the wire-bound part of the network and handles the calculation for a plurality of mobile radio terminals.

14. A method according to claim 10, comprising the step of synchronising a mobile radio terminal to a serving radio base station, comprising the sub-steps of:

resetting a counter in said mobile radio terminal thereby synchronising to said serving radio base station;

storing the reset value of said counter in said mobile radio terminal;

reading in said mobile radio terminal on the synchronisation channel SCH of said serving radio base station the radio base station identity and the current frame number.

15. A method according to claim 10, comprising the step of measuring at said radio terminal relative receive times of the timing signals downlink of other radio base stations than said serving radio base station comprising the sub-steps of:

storing the value of a counter in said mobile radio terminal at the instant the frame of said other radio base station begins;

reading in said mobile radio terminal on the synchronisation channel SCH of said other radio base station the radio base station identity and the current frame number;

deciding if more other radio base stations are to be measured and if so loop back to the sub-step of storing.

16. A mobile radio system comprising at least three radio base stations sending timing signals downlink and at least a first mobile radio terminal the geographical position of which is to be determined, comprising:

at least a second radio terminal at a fixed position receiving said timing signals downlink;

a service node having stored in it known positions of said at least three radio base stations and of said at least second radio terminal;

measuring means in said at least first and at least second radio terminals for measuring relative receive times of said timing signals downlink and reporting them to said service node;

first calculating means in said service node for calculating transmission time offsets, from said known positions and said relative receive times reported by said at least second radio terminal;

second calculating means in said service node for calculating the position of said first mobile radio terminal from said known positions of said at least three radio base stations, from said transmission time offsets and from relative receive times sent by said first mobile radio terminal.

17. A system according to claim 16, wherein said second mobile radio terminal being located at a base station site.

18. A system according to claim 16, wherein radio base stations send downlink a Frequency Correction Channel FCCH and a Synchronisation Channel SCH which may be read during idle and dedicated modes and wherein the mobile radio terminals synchronise to the serving radio base station and can read said Synchronisation Channel of other radio base stations than said serving radio base station, comprising:

measuring means for reading in said radio terminals on the Synchronisation Channel SCH of said other radio base stations than said serving radio base station the base station identity and the current frame number and reading on a counter in said second and first mobile radio terminals the relative receive time of said other radio base stations relative to the beginning of a frame of said serving radio base station;

wherein if the radio terminal is in dedicated mode reading on said counter is performed during an idle time slot in the radio terminal.

19. A system according to claim 16, with at least one radio base station in the system further comprising:

means for sending on a beacon channel periodic timing signals downlink to facilitate positioning of mobile radio terminals;

means for receiving from a service node in the network orders relating to at least the setting of the frequency of said beacon channel.

20. A system according to claim 16, with simplified calculations of the position of radio terminals the simplification being obtained by synchronising some but not all radio base stations of the positioning system.

21. A mobile radio system comprising at least three radio base stations sending timing signals downlink and at least a first mobile radio terminal the geographical position of which is to be determined, comprising:

at least a second radio terminal at a fixed position receiving said timing signals downlink;

a service node having stored in it known positions of said at least three radio base stations and of said at least second radio terminal;

measuring means in said at least first and at least second radio terminals for measuring relative receive times of said timing signals downlink and reporting them to said service node;

first calculation means in said service node for calculating transmission time offsets, from said known positions and said relative receive times reported by said at least second radio terminal;

sending means for sending from said service node to said first mobile radio terminal said known positions of said at least three radio base stations and associated transmission time offsets;

second calculating means in said at least first mobile radio terminal for calculating its own position from said known positions of said at least three radio base stations and associated transmission time offsets and from relative receive times transferred by said first mobile radio terminal.

22. A system according to claim 21, wherein said second mobile radio terminal being located at a base station site.

23. A system according to claim 21, wherein radio base stations send downlink a Frequency Correction Channel FCCH and a Synchronisation Channel SCH which may be read during idle and dedicated modes and wherein the mobile radio terminals synchronise to the serving radio base station and can read said Synchronisation Channel of other radio base stations than said serving radio base station, comprising:

measuring means for reading in said radio terminals on the Synchronisation Channel SCH of said other radio base stations than said serving radio base station the base station identity and the current frame number and reading on a counter in said second and first mobile radio terminals the relative receive time of said other radio base stations relative to the beginning of a frame of said serving radio base station;

wherein if the radio terminal is in dedicated mode reading on said counter is performed during an idle time slot in the radio terminal.

24. A system according to claim 21, with at least one radio base station in the system further comprising:

means for sending on a beacon channel periodic timing signals downlink to facilitate positioning of mobile radio terminals;

means for receiving from a service node in the network orders relating to at least the setting of the frequency of said beacon channel.

25. A system according to claim 21, with simplified calculations of the position of radio terminals the simplification being obtained by synchronising some but not all radio base stations of the positioning system.

26. A radio terminal comprising:

measuring means for measuring during idle mode and conversation mode the relative receive times between periodic timing signals downlink received from a considered radio base station and periodic timing signals downlink received from a serving radio base station when said mobile radio terminal is synchronised to said serving radio base station;

reading means for reading during idle mode and conversation mode the Frequency Correction Channel FCCH and Synchronisation Channel SCH including reading the identity and frame number transmitted by said considered radio base station;

messaging means for messaging during idle mode and conversation mode measured relative receive times and read identities and frame numbers to a service node.

27. A radio terminal according to claim 26, further comprising:

messaging means for receiving in said radio terminal position information, transmission time offset information and identity information regarding radio base stations;

wherein said information regarding radio base stations is provided as broadcast downlink information from at least some among the radio base stations.

28. A mobile radio terminal according to claim 27, further comprising:

second calculating means for calculating its own position;

wherein the mobile calculating its own position makes use of downlink information streams only.

29. A radio terminal according to claim 26, further comprising:

messaging means for receiving in said radio terminal position information, transmission time offset information and identity information regarding radio base stations;

wherein said information regrading radio base stations is provided as individual messages, preferably of Short Message Service SMS type, addressed to said radio terminal.

30. A mobile radio terminal according to claim 29, further comprising:

second calculating means for calculating its own position;

wherein the mobile calculating its own position makes use of downlink information streams only.

31. A mobile radio terminal according to claim 29, wherein said measuring means, said reading means, said messaging means for messaging and said messaging means for receiving are implemented as a processor with programs located in a first mobile radio terminal to be positioned and in a second mobile radio terminal the position of which is known.

32. A mobile radio terminal according to claim 29, wherein said measuring means comprises a Quarter Bit Counter and wherein a resolution of the Quarter Bit Counter is increased by using a higher frequency as an input to the counter and by using correspondingly more bits in said counter thereby counting to more than 4999.

33. A mobile radio terminal according to claim 26, further comprising:

second calculating means for calculating its own position;

wherein the mobile calculating its own position makes use of downlink information streams only.

34. A mobile radio terminal according to claim 33, wherein said measuring means comprises a Quarter Bit Counter and wherein a resolution of the Quarter Bit Counter is increased by using a higher frequency as an input to the counter and by using correspondingly more bits in said counter thereby counting to more than 4999.

35. A mobile radio terminal according to claim 27, wherein said measuring means, said reading means, said messaging means for messaging and said messaging means for receiving are implemented as a processor with programs located in a first mobile radio terminal to be positioned and in a second mobile radio terminal the position of which is known.

36. A mobile radio terminal according to claim 27, wherein said measuring means comprises a Quarter Bit Counter and wherein a resolution of the Quarter Bit Counter is increased by using a higher frequency as an input to the counter and by using correspondingly more bits in said counter thereby counting to more than 4999.

37. A mobile radio terminal according to claim 26, wherein said measuring means, said reading means and said messaging means are implemented as a processor with programs located in a first mobile radio terminal to be positioned and in a second mobile radio terminal the position of which is known.

38. A mobile radio terminal according to claim 26, wherein said measuring means comprises a Quarter Bit Counter and wherein a resolution of the Quarter Bit Counter is increased by using a higher frequency as an input to the counter and by using correspondingly more bits in said counter thereby counting to more than 4999.

39. A mobile radio terminal according to claim 37, wherein said measuring means comprises a Quarter Bit Counter and wherein a resolution of the Quarter Bit Counter is increased by using a higher frequency as an input to the counter and by using correspondingly more bits in said counter thereby counting to more than 4999.

40. A service node in a mobile radio network this network comprising at least three radio base stations sending timing signals downlink at least one first mobile radio terminal the geographical position of which is to be determined, at least one second fixed radio terminal said service node comprising:

receiving means for receiving measurement reports from said at least one fixed radio terminal of relative receive times of timing signals downlink transmitted by said at least three radio base stations;

storing means for storing known geographical positions of said at least three radio base stations and of said at least one second fixed radio terminal;

first calculating means for calculating from measurement reports from said at least one fixed radio terminal and from said known geographical positions transmission time offsets of the timing signals downlink transmitted by said at least three radio base stations.

41. A service node according to claim 40, further comprising:

receiving means for receiving measurement reports from said first mobile radio terminal of relative receive times of timing signals downlink transmitted by said at least three radio base stations;

second calculating means for calculating the geographical position of said first mobile radio terminal from said transmission time offsets, said known geographical positions and said received measurement reports from said first mobile radio terminal.

42. A service node according to claim 40, further comprising:

sending means for sending said known geographical positions and said transmission time offsets to radio base stations for broadcasting to said first mobile radio terminal.