Calculation method in a radio system for calculating the geometrical time difference between transmitters

• US 20020177452A1
• Filed: 07/15/2002
• Published: 11/28/2002
• Est. Priority Date: 04/08/1998
• Status: Active Grant

• Current Assignee: Nokia Networks (Nokia Corporation)
• Original Assignee: Nokia Networks (Nokia Corporation)
• Inventors: Rantalainen, Timo M., Ruutu, Ville
• Granted Patent: US 7,194,272 B2
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• 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 invention relates to a calculating method and a radio system comprising a set of emitters and a set of receivers and a measuring means, which measure the time difference between the reception moments of signals transmitted by the transmitters while the receiver is receiving signals, and which calculate the geometrical time difference of the signals transmitted by the transmitters. The radio system comprises a calculating means, which form the real time difference between the transmission moments of the signals transmitted by the transmitters as a function of time by means of measuring the time difference of the signals received by the receiver and by means of the geometrical time difference, in such a way that the calculating means and the geometrical time difference to the time difference based on the reception moments. Moreover, the calculating means sum up directly measured real time differences and thereby calculate the real time differences between the other transmitters in the coverage area of the receiver. Further, the calculating means calculate the real time differences between the transmitters in the coverage areas of different receivers by using the already calculated time differences between the transmitters.

Claims

1. A calculation method to be used in a radio system comprising a set of transmitters (101-110) and a set of receivers (201-204), in which radio system the time difference between the reception moments of signals transmitted by the transmitters (101-110) is measured, and the geometrical time difference of the transmitted signals is calculated, characterized by forming the real time difference between the transmission moments of signals transmitted by a transmitter serving a respective receiver (201-204) and by the neighbour transmitter of said transmitter as a function of time by means of measuring the time difference between the reception moments of the signals and by means of the geometrical time difference, in such a way that the geometrical time difference is added to the time difference based on the reception moments,

summing up directly measured real time differences in order to calculate the real time differences between the other transmitters in the coverage area of the receiver,

calculating the real time differences between transmitters in coverage areas of various receivers (201-204) by using the time differences that have already been calculated between the transmitters.

2. A method according to claim 1, characterized by forming the real time difference between the transmission moments by means of measuring the time difference between the reception moments of signals transmitted by two neighbour transmitters, and by means of the geometrical time difference.

3. A method according to claim 1, characterized by forming the real time difference between the transmission moments by means of measuring the time difference between the reception moments of signals transmitted by two serving transmitters, and by means of the geometrical time difference.

4. A method according to claim 1, characterized by using the difference of the reception moments of the signals transmitted by the transmitter serving the receiver (201-204) and by the neighbour transmitter of said transmitter to determine the synchronisation of the transmitters with each other.

5. A method according to claim 1, characterized by using the difference of the reception moments of the signals transmitted by two neighbour transmitters and/or two serving transmitters to determine the synchronisation of the transmitters with each other.

6. A method according to claim 1, characterized by measuring a signal which has arrived at different receivers and which was transmitted by the same transmitter, if the transmitter is located in the coverage area of several receivers.

7. A method according to claim 1, characterized by measuring the signals transmitted by the transmitters located in each of the coverage areas of the receivers (201-204), and by using the real time differences calculated on the basis of the signals received from each coverage area in calculating the time differences between the transmitters in various coverage areas.

8. A method according to claim 1, characterized by forming graphs on the basis of the transmitters (101-110) and the real time differences between them, in which graphs the transmitters are displayed as nodal points and the directly measured real time differences are displayed as lines, by seeking paths from a transmitter to the other transmitters, and by summing up the real time differences between the transmitters in order to determine real time differences which have not been discovered before.

9. A method according to claim 8, characterized by selecting the time difference values of the shortest path for the summing up, if several paths exist between the transmitters.

10. A method according to claim 1, characterized by using the real time difference in order to locate a subscriber terminal in a radio system when measuring the observed time differences between the arrival times of the signals coming from the transmitters.

11. A radio system comprising a set of transmitters (101-110), a set of receivers (201-204) and a measuring means (10) which measure the time difference between the reception moments of signals transmitted by the transmitters while the receiver is receiving signals, and which calculate the geometrical time difference of the signals transmitted by the transmitters, characterized in that

the radio system comprises a calculating means (11), which form the real time difference between the transmission moments of signals transmitted by transmitters as a function of time by means of measuring the time difference of signals received by a receiver, and by means of the geometrical time difference, in such a way that the calculating means (11) add the geometrical time difference to the time difference based on the reception moments,

the calculating means (11) sum up directly measured real time differences and thereby calculate the real time differences between the other transmitters in the coverage area of the receiver, and

the calculating means (11) calculate the real time differences of the transmitters in coverage areas of various receivers by using the time differences that have already been calculated between the transmitters.

12. A radio system according to claim 11, characterized in that the calculating means (11) form the real time difference between the transmission moments by means of measuring the time difference between the reception moments of signals transmitted by two neighbour transmitters, and by means of the geometrical time difference.

13. A radio system according to claim 11, characterized in that the calculating means (11) form the real time difference between the transmission moments by means of measuring the time difference between the reception moments of signals transmitted by two serving transmitters, and by means of the geometrical time difference.

14. A radio system according to claim 11, characterized in that the calculating means (11) use the difference of the reception moments of signals transmitted by two neighbour transmitters and/or two serving transmitters to determine the synchronisation of the transmitters with each other.

15. A radio system according to claim 11, characterized in that the calculating means (11) use the difference of the reception moments of the signals transmitted by the transmitter serving the receiver and by the neighbour transmitter of said transmitter to determine the synchronisation of the transmitters (101-110) with each other.

16. A radio system according to claim 11, characterized in that various measuring means (10) measure a signal of the same transmitter, if the transmitter is located in the coverage area of several receivers.

17. A radio system according to claim 11, characterized in that the calculating means (11) determine the real time difference of the transmitter serving the receiver (201-204) compared to the other transmitters in the coverage area of the receiver.

18. A radio system according to claim 11, characterized in that the calculating means (11) form a matrix, where the rows correspond to the transmitter serving the receiver and the columns correspond to the neighbour transmitter of the serving transmitter, and the calculating means use the matrix in order to calculate the real time differences between the transmission moments of the transmitters.

19. A radio system according to claim 11, characterized in that the calculating means (11) place the calculated real time differences between the transmission moments of the transmitters into a matrix, after which the calculating means (11) determine the real time difference for the transmitter on the basis of the calculated time differences without the measuring means (10) directly measuring the signal transmitted by the transmitter.

20. A radio system according to claim 11, characterized in that the calculating means (11) form graphs on the basis of the transmitters (101-110) and the real time differences between them, in which graphs the transmitters are displayed as nodal points and the directly measured real time differences are displayed as lines, after which the calculating means (11) seek paths from transmitters to the other transmitters and the calculating means (11) sum up real time differences between the transmitters in order to determine real time differences which have not been discovered before.

21. A radio system according to claim 20, characterized in that if several alternative paths exist between the transmitters, the calculating means (11) select the shortest path, on the basis of which the time difference is determined.

22. A radio system according to claim 11, characterized in that in order to locate a receiver the real time difference is used, in such a way that the corresponding real time difference is subtracted from the time difference between the reception moments of the signals measured by the receiver to be located, e.g. a subscriber terminal.

23. A radio system according to claim 11, characterized in that the calculating means (11) form a matrix, where the rows correspond to the transmitter, to which the time difference of another transmitter is compared, and where the columns represent the other transmitter, and where the calculating means (11) use the matrix in calculating the real time differences between the transmission moments of the transmitters.

24. A radio system according to claim 11, characterized in that the receiver is a subscriber terminal, such as a mobile phone.