Method and system for determining the position of mobile radio terminals

• US 6,031,490 A
• Filed: 12/23/1997
• Issued: 02/29/2000
• Est. Priority Date: 08/18/1997
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Forssen, Ulf Goran, Ghisler, Walter, Berg, Jan-Erik
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/996,937
• Time in Patent Office: 798 Days
• Field of Search: 342/387, 342/457, 342/458, 342/465, 455/456
• US Class Current: 342/457
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• 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

The disclosure describes a novel Time Difference of Arrival (TDOA) method and system for determining the position of a first mobile radio terminal within an associated mobile radio system, which is based on Time of Arrival (TOA) measurements, including a plurality of radio base stations, measuring devices, network controller, and service node. The measuring devices are synchronized in otherwise unsynchronized radio base stations. The measuring devices measure TOA on demand and (optionally) Direction of Arrival (DOA), on a digital uplink time slot or on digital information on an analog uplink traffic channel in one or more radio base stations. The TOA and DOA information and the traffic channel number are reported to a Mobile Services Switching Center, which obtains the first mobile terminal'"'"'s identity from the traffic channel number and sends the terminal identity and TOA and DOA measurement information to a Service Node. The Service Node calculates the position of the first mobile radio terminal using the TOA information (supplemented by the DOA information when available). A second mobile radio terminal is colocated on a mobile platform (auto, emergency vehicle, etc.) with one of the radio base stations, which can be moved into relatively close proximity with the first mobile radio terminal. Consequently, by moving one of the radio base stations close to the region of interest (near the first mobile radio terminal), the position determination accuracy is significantly improved.

Claims

1. A method for determining the geographical position of a first mobile radio terminal in a mobile radio system, said mobile radio system including a network controller and at least three radio base stations, each of said at least three radio base stations including an uplink TOA measuring unit operable to communicate with said network controller, a control unit, and a time reference unit operable to provide timing reference signals to said uplink TOA measuring unit, at least one of said at least three radio base stations colocated with and connected to a second mobile radio terminal, said second mobile radio terminal coupled to said network controller via a radio interface, and a service node operable to store known positions of at least two of said at least three radio base stations, the method comprising the steps of:

receiving a request in said mobile radio system to determine the geographical position of said first mobile radio terminal;

determining and reporting the position of said second mobile radio terminal to said service node;

directing said first mobile radio terminal to transmit digital signals uplink on a traffic channel when said first mobile terminal is not transmitting or transmitting only analog signals;

measuring in each uplink TOA measuring unit an uplink TOA of the digital signals transmitted by the first mobile radio terminal;

receiving in said network controller said uplink TOA measurements from said at least three radio base stations and a traffic channel number to said traffic channel;

translating said traffic channel number to an identity of said first mobile radio terminal;

conveying said uplink TOA measurements and said first mobile radio terminal identity to said service node; and

calculating in said service node the position of said first mobile radio terminal using said known positions of said at least three radio base stations and said uplink TOA measurements.

2. The method according to claim 1, further comprising the step of said network controller directing said first mobile radio terminal to increase transmission power during said uplink TOA measurements.

3. The method according to claim 1, further comprising the step of inter-base station handing off said first mobile radio terminal to a more distant serving base station.

4. The method according to claim 1, further comprising the step of intra-base station handing off said first mobile radio terminal to a second traffic channel if, in a distant base station performing a TOA measurement, a signal-to-noise ratio of said traffic channel is less than a predetermined value, said second traffic channel having a signal-to-noise ratio greater than said predetermined value.

5. The method according to claim 1, wherein said uplink TOA measuring unit comprises a modified receiver.

6. The method according to claim 1, wherein said directing step comprises setting up a call to said first mobile radio terminal.

7. The method according to claim 1, further comprising the step of performing a handover before measuring said uplink TOA measurements of the first mobile radio terminal. digital information.

8. The method according to claim 1, wherein said directing step comprises conveying information to a first analog mobile radio terminal, said information directing said first analog mobile radio terminal to respond uplink with digital information.

9. The method according to claim 1, wherein said directing step comprises conveying information to a first packet terminal, said information directing said first packet terminal to respond uplink.

10. The method according to claim 1, wherein said determining and reporting step comprises determining the position of said second mobile radio terminal using GPS position information, and reporting said position of said second mobile radio terminal to said service node.

11. The method according to claim 1, wherein said determining and reporting step comprises determining the position of said second mobile radio terminal using predetermined position information, and reporting said position of said second mobile radio terminal to said service node.

12. A mobile radio system capable of determining the geographical position of a first mobile radio terminal located in said mobile radio system, comprising:

a network controller;

at least four radio base stations, each of said at least four radio base stations including uplink TOA measuring equipment operable to communicate with said network controller, and a time reference unit operable to provide timing signals to said uplink TOA measuring equipment, at least one of said at least four radio base stations colocated with and connected to a second mobile radio terminal, said second mobile radio terminal coupled to said network controller via a radio interface and one of said at least four radio base stations; and

a service node operable to store known position information about at least three of said at least four radio base stations, said mobile radio system operable to determine said geographical position of said first mobile radio terminal, by receiving a request to determine said geographical position of said first mobile radio terminal, directing said first and second mobile radio terminals to transmit digital signals uplink on traffic channels when said first mobile radio terminal or second mobile radio terminals is not transmitting or transmitting only analog signals, measuring TOA of the transmitted digital signals in the uplink TOA measuring equipment in at least four radio base stations, receiving from said at least four radio base stations said TOA measurement information in said network controller and traffic channel numbers to said traffic channels, translating said traffic channel numbers to identities of said first and second mobile radio terminals, conveying said uplink TOA measurement information and identities to said service node, and calculating in said service node the geographical position of said first and second mobile radio terminals using said known position information of said at least three radio base stations and said uplink TOA measurement information.

13. The mobile radio system according to claim 12, wherein said directing operation comprises setting up a call to said first and second mobile radio terminals.

14. The mobile radio system according to claim 12, wherein said directing operation comprises activating said first mobile radio terminal to transmit if said first mobile radio terminal is inactive and a discontinuous transmission type.

15. The mobile radio system according to claim 12, wherein said directing operation comprises conveying information to a first analog mobile radio terminal that directs said first mobile radio terminal to respond on said uplink with digital information.

16. The mobile radio system according to claim 12, wherein said directing operation comprises conveying information to a first packet terminal that directs said first packet terminal to respond on said uplink.

17. The mobile radio system according to claim 12, wherein said uplink TOA measuring equipment includes a DOA meter.

18. The mobile radio system according to claim 12, further comprising means for performing a handover before measuring said uplink TOA measurements of the first mobile radio terminal.

19. A method for determining the geographical position of a first mobile radio terminal in a mobile radio system, said mobile radio system including a network controller and at least two radio base stations each including at least one uplink TOA measuring unit each located at a different location with respect to one another and each operable to communicate with said network controller, a control unit, and a time reference unit operable to provide timing reference signals to said uplink TOA measuring units, at least one of said at least two radio base stations colocated with and connected to a second mobile radio terminal, said second mobile radio terminal coupled to said network controller via a radio air interface, and a service node operable to store known positions of at least two of said uplink TOA measuring units, the method comprising the steps of:

receiving a request in said mobile radio system to determine the geographical position of said first mobile radio terminal;

determining and reporting the position of said second mobile radio terminal to said service mode;

directing said first mobile radio terminal to transmit digital signals uplink on the traffic channel when said first mobile terminal is not transmitting or transmitting only analog signals;

measuring in each uplink TOA measuring unit an uplink TOA measurement of the digital signals transmitted by the first mobile radio terminal;

receiving in said network controller said uplink TOA measurement from each uplink TOA measuring unit and a traffic channel number to said traffic channel;

translating said traffic channel number to an identity of said first mobile radio terminal;

conveying said uplink TOA measurements and said first mobile radio terminal identity to said service node; and

calculating in said service node the position of said first mobile radio terminal using said known positions of said plurality of uplink TOA measuring units and said uplink TOA measurements.

20. A mobile radio system capable of determining the geographical position of a first mobile radio terminal, comprising:

a network controller;

at least two radio base stations each including at least one uplink TOA measuring unit each located at a different location with respect to one another and each operable to communicate with said network controller, and a time reference unit operable to provide timing signals to each uplink TOA measuring unit, at least one of said at least two radio base stations colocated with and connected to a second mobile radio terminal, said second mobile radio terminal coupled to said network controller via a radio air interface; and

a service node operable to store known positions of at least two of said uplink TOA measuring units, said mobile radio system operable to determine said geographical position of said first mobile radio terminal, by receiving a request to determine the geographical position of said first mobile radio terminal, determining and reporting the position of said second mobile radio terminal to said service mode, directing said first mobile radio terminal to transmit digital signals uplink on a traffic channel when said first mobile radio terminal is not transmitting or transmitting only analog signals, measuring TOA information of the digital signals transmitted by the first mobile radio terminal on said traffic channel in each uplink TOA measuring unit, receiving from each uplink TOA measuring unit said TOA measurement information in said network controller and a traffic channel number to said traffic channel, translating the traffic channel number to an identity of said first mobile radio terminal, conveying said uplink TOA measurement information and identity to said service node, and calculating in said service node the geographical position of said first mobile radio terminal using said known position information of said plurality of uplink TOA measuring units and said uplink TOA measurement information.

21. A method for determining the geographical position of a first mobile radio terminal in a mobile radio system, said mobile radio system including a network controller and a radio base station including an uplink measuring unit operable to communicate with said network controller, a control unit, and a time reference unit operable to provide timing reference signals to said uplink measuring unit, said radio base station colocated with and connected to a second mobile radio terminal, said second mobile radio terminal coupled to said network controller via a radio air interface, and a service node operable to store a known position of said radio base station, the method comprising the steps of:

receiving a request in said mobile radio system to determine the geographical position of said first mobile radio terminal;

determining and reporting the position of said second mobile radio terminal to said service node;

directing said first mobile radio terminal to transmit digital signals uplink on the traffic channel when said first mobile terminal radio is not transmitting or transmitting only analog signals;

measuring in said uplink measuring unit an uplink TOA measurement and a DOA measurement of the digital signals transmitted by the first mobile radio terminal;

receiving in said network controller said uplink TOA measurement and said DOA measurement from said radio base station and a traffic channel number to said traffic channel;

translating the traffic channel number to an identity of said first mobile radio terminal;

conveying said uplink TOA measurement, said DOA measurement and said first mobile radio terminal identity to said service node; and

calculating in said service node the position of said first mobile radio terminal using said known position of said radio base station, said uplink TOA measurement and said DOA measurement.

22. A mobile radio system capable of determining a geographical position of a first mobile radio terminal, comprising:

a network controller;

a radio base station including an uplink measuring equipment operable to communicate with said network controller, a control unit, and a time reference unit operable to provide timing signals to said uplink measuring equipment, said radio base station colocated with and connected to a second mobile radio terminal, said second mobile radio terminal coupled to said network controller via a radio air interface; and

a service node operable to store known position information about said radio base station, said mobile radio system operable to determine said geographical position of said first mobile radio terminal, by receiving a request at said mobile radio system to determine the geographical position of said first mobile radio terminal, directing said first mobile radio terminal to transmit digital signals uplink on a traffic channel when said mobile radio terminal is not transmitting or transmitting only analog signals, measuring in the uplink measuring equipment a TOA measurement and a DOA measurement of the digital signals transmitted by the first mobile radio terminal, receiving from said radio base station said TOA measurement and said DOA measurement in said network controller and a traffic channel number to said traffic channel, translating the traffic channel number to an identity of said first mobile radio terminal, conveying said TOA measurement, said DOA measurement and said first mobile radio terminal identity to said service node, and calculating in said service node the geographical position of said first mobile radio terminal using said known position information of said radio base station, said TOA measurement, and said DOA measurement.