Mobile station position estimation scheme for cellular mobile communication system

• US 6,181,944 B1
• Filed: 03/13/1998
• Issued: 01/30/2001
• Est. Priority Date: 03/14/1997
• Status: Expired due to Term

• Current Assignee: NTT Mobile Communications Network Inc. (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Mobile Communications Network Inc. (Nippon Telegraph and Telephone Corporation)
• Inventors: Ohno, Kouji, Onoe, Seizo, Uebayashi, Shinji
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): Woldetatios, Yemane
• Application Number:
  US09/041,764
• Time in Patent Office: 1,054 Days
• Field of Search: 455/422, 455/456, 455/457, 701/207, 342/442, 342/457
• US Class Current: 455/456.2
• 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 mobile station position estimation scheme for a cellular mobile communication system which is capable of estimating a position of a mobile station in a simple manner even in the general cellular mobile communication systems in which base stations are not synchronized. According to this mobile station position estimation scheme, a first signal sequence and a second signal sequence which are uniquely predetermined for the mobile station are exchanged between the mobile station and the base station, and then a position of the mobile station is estimated at one station among the base station and the mobile station, by obtaining a phase difference between the first signal sequence and the second signal sequence and calculating an estimated distance between the base station and the mobile station according to the phase difference.

Claims

1. A mobile station position estimation method in a cellular mobile communication for carrying out communications between mobile stations and base stations, comprising the steps of:

(a) exchanging between a base station and a mobile station a first signal sequence and a second signal sequence which are uniquely predetermined for the mobile station; and

(b) estimating a position of the mobile station at one station among the base station and the mobile station, by obtaining a phase difference between the first signal sequence and the second signal sequence and calculating an estimated distance between the base station and the mobile station according to the phase difference;

wherein at the step (a), said one station transmits the first signal sequence to another station among the base station and the mobile station, and said another station transmits the second signal sequence to said one station in synchronization with the first signal sequence as received by said one station; and

at the step (b), said one station obtains the phase difference by comparing phases of the first signal sequence as transmitted by said one station and the second signal sequence as received by said one station.

2. The method of claim 1, wherein when multipath signal is received at the step (a), said another station transmits the second signal sequence in synchronization with the first signal sequence received from a path having a shortest delay time.

3. The method of claim 1, wherein when multipath signal is received at the step (a), said one station obtains the phase difference by using the second signal sequence received from a path having a shortest delay time at the step (b).

4. The method of claim 1, wherein the cellular mobile communication is a mobile communication in CDMA scheme, and the first signal sequence and the second signal sequence are spread codes of CDMA scheme.

5. The method of claim 1, wherein the cellular mobile communication uses base stations each of which has a broadcast channel for transmitting information to be broadcast to all mobile stations, and said one station is the base station;

and

at the step (a), the base station transmits the first signal sequence through the broadcast channel.

6. The method of claim 1, wherein the mobile station exchanges the first signal sequence and the second signal sequence with respect to each one of a plurality of base stations at the step (a), and the step (b) calculates estimated distances of the mobile station with respect to said plurality of base stations separately and estimates the position of the mobile station by combining the estimated distances of the mobile station with respect to said plurality of base stations.

7. The method of claim 6, wherein at the step (a), the mobile station carries out simultaneous multi-code transmission by code division multiplexing signals to be transmitted with respect to said plurality of base stations.

8. The method of claim 6, wherein at the step (a), the mobile station carries out transmission by time division multiplexing signals to be transmitted to said plurality of base stations into a channel of a frame structure.

9. The method of claim 1, wherein said one station is the mobile station, and at the step (a), the base station transmits through a broadcast channel a third signal sequence which is uniquely predetermined for the mobile station, before the mobile station transmits the first signal sequence to the base station, and the mobile station transmits the first signal sequence to the base station in synchronization with the third signal sequence as received by the mobile station.

10. The method of claim 1, wherein said one station is the mobile station, and at the step (a), the base station transmits through a broadcast channel a third signal sequence which is uniquely predetermined for the mobile station, before the mobile station transmits the first signal sequence to the base station, the mobile station obtains a first phase difference by comparing phases of the third signal sequence as received by the mobile station and the first signal sequence to be transmitted by the mobile station and transmits information on the first phase difference and the second signal sequence, and the base station obtains a second phase difference by comparing phases of the first signal sequence as received by the base station and the third signal sequence as transmitted by the base station, calculates a first estimated distance between the base station and the mobile station from the first phase difference and the second phase difference, obtains a third phase difference by comparing phases of the first signal sequence as received by the base station and the second signal sequence to be transmitted by the base station, and transmits information on the third phase difference, information on the first estimated distance and the second signal sequence to the mobile station;

and

at the step (b), the mobile station obtains a fourth phase difference by comparing phases of the first signal sequence as transmitted by the mobile station and the second signal sequence as received by the mobile station, calculates a second estimated distance between the base station and the mobile station from the third phase difference and the fourth phase difference, and calculates the estimated distance from the first estimated distance and the second estimated distance.

11. The method of claim 1, wherein the step (b) estimates the position of the mobile station to be within an estimated position area obtained by accounting for a prescribed error in positions distanced by the estimated distance from the base station in a service area of the base station;

and

when the mobile station exchanges the first signal sequence and the second signal sequence with respect to each one of a plurality of base stations at the step (a), the step (b) calculates estimated distances of the mobile station with respect to said plurality of base stations separately, and estimates the position of the mobile station to be within an area in which a plurality of estimated position areas obtained from the estimated distances of the mobile station with respect to said plurality of base stations are overlapping.

12. The method of claim 1, wherein the step (b) estimates the position of the mobile station to be within an estimated position area obtained by accounting for a prescribed error in positions distanced by the estimated distance from the base station in a sector of the base station which is currently in communication with the mobile station;

and

when the mobile station exchanges the first signal sequence and the second signal sequence with respect to each one of a plurality of base stations at the step (a), the step (b) calculates estimated distances of the mobile station with respect to said plurality of base stations separately, and estimates the position of the mobile station to be within an area in which a plurality of estimated position areas obtained from the estimated distances of the mobile station with respect to said plurality of base stations are overlapping.

13. A mobile station position estimation method in a cellular mobile communication for carrying out communications between mobile stations and base stations, comprising the steps of:

(a) exchanging between a base station and a mobile station a first signal sequence and a second signal sequence which are uniquely predetermined for the mobile station; and

(b) estimating a position of the mobile station at one station among the base station and the mobile station, by obtaining a phase difference between the first signal sequence and the second signal sequence and calculating an estimated distance between the base station and the mobile station according to the phase difference;

wherein at the step (a), said one station transmits the first signal sequence to another station among the base station and the mobile station, and said another station obtains a first phase difference by comparing phases of the first signal sequence as received by said another station and the second signal sequence to be transmitted by said another station, and transmits information on the first phase difference and the second signal sequence to said one station; and

at the step (b), said one station obtains a second phase difference by comparing phases of the first signal sequence as transmitted by said one station and the second signal sequence as received by said one station, and calculates the estimated distance by using the first phase difference and the second phase difference.

14. The method of claim 13, wherein when multipath signal is received at the step (a), said another station obtains the first phase difference by using the first signal sequence received from a path having a shortest delay time.

15. The method of claim 13, wherein when multipath signal is received at the step (a), said one station obtains the second phase difference by using the second signal sequence received from a path having a shortest delay time at the step (b).

16. The method of claim 13, wherein the cellular mobile communication is a mobile communication in CDMA scheme, and the first signal sequence and the second signal sequence are spread codes of CDMA scheme.

17. The method of claim 13, wherein the cellular mobile communication uses base stations each of which has a broadcast channel for transmitting information to be broadcast to all mobile stations, and said one station is the base station;

and

at the step (a), the base station transmits the first signal sequence through the broadcast channel.

18. The method of claim 13, wherein the mobile station exchanges the first signal sequence and the second signal sequence with respect to each one of a plurality of base stations at the step (a), and the step (b) calculates estimated distances of the mobile station with respect to said plurality of base stations separately and estimates the position of the mobile station by combining the estimated distances of the mobile station with respect to said plurality of base stations.

19. The method of claim 18, wherein at the step (a), the mobile station carries out simultaneous multi-code transmission by code division multiplexing signals to be transmitted with respect to said plurality of base stations.

20. The method of claim 18, wherein at the step (a), the mobile station carries out transmission by time division multiplexing signals to be transmitted to said plurality of base stations into a channel of a frame structure.

21. The method of claim 13, wherein said one station is the mobile station, and at the step (a), the base station transmits through a broadcast channel a third signal sequence which is uniquely predetermined for the mobile station, before the mobile station transmits the first signal sequence to the base station, and the mobile station transmits the first signal sequence to the base station in synchronization with the third signal sequence as received by the mobile station.

22. The method of claim 13, wherein said one station is the mobile station, and at the step (a), the base station transmits through a broadcast channel a third signal sequence which is uniquely predetermined for the mobile station, before the mobile station transmits the first signal sequence to the base station, the mobile station obtains a first phase difference by comparing phases of the third signal sequence as received by the mobile station and the first signal sequence to be transmitted by the mobile station and transmits information on the first phase difference and the second signal sequence, and the base station obtains a second phase difference by comparing phases of the first signal sequence as received by the base station and the third signal sequence as transmitted by the base station, calculates a first estimated distance between the base station and the mobile station from the first phase difference and the second phase difference, obtains a third phase difference by comparing phases of the first signal sequence as received by the base station and the second signal sequence to be transmitted by the base station, and transmits information on the third phase difference, information on the first estimated distance and the second signal sequence to the mobile station;

and

at the step (b), the mobile station obtains a fourth phase difference by comparing phases of the first signal sequence as transmitted by the mobile station and the second signal sequence as received by the mobile station, calculates a second estimated distance between the base station and the mobile station from the third phase difference and the fourth phase difference, and calculates the estimated distance from the first estimated distance and the second estimated distance.

23. The method of claim 13, wherein the step (b) estimates the position of the mobile station to be within an estimated position area obtained by accounting for a prescribed error in positions distanced by the estimated distance from the base station in a service area of the base station;

and

when the mobile station exchanges the first signal sequence and the second signal sequence with respect to each one of a plurality of base stations at the step (a), the step (b) calculates estimated distances of the mobile station with respect to said plurality of base stations separately, and estimates the position of the mobile station to be within an area in which a plurality of estimated position areas obtained from the estimated distances of the mobile station with respect to said plurality of base stations are overlapping.

24. The method of claim 13, wherein the step (b) estimates the position of the mobile station to be within an estimated position area obtained by accounting for a prescribed error in positions distanced by the estimated distance from the base station in a sector of the base station which is currently in communication with the mobile station;

and

when the mobile station exchanges the first signal sequence and the second signal sequence with respect to each one of a plurality of base stations at the step (a), the step (b) calculates estimated distances of the mobile station with respect to said plurality of base stations separately, and estimates the position of the mobile station to be within an area in which a plurality of estimated position areas obtained from the estimated distances of the mobile station with respect to said plurality of base stations are overlapping.

25. A base station device at a base station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising:

a reception unit for receiving a first signal sequence transmitted by a mobile station, which is uniquely predetermined for the mobile station; and

a transmission unit for transmitting a second signal sequence which is uniquely predetermined for the mobile station, to the mobile station in synchronization with the first signal sequence received by the reception unit, so as to enable the mobile station to estimate a position of the mobile station by calculating an estimated distance between the base station and the mobile station according to a phase difference between the first signal sequence and the second signal sequence.

26. The base station device of claim 25, wherein when the reception unit receives multipath signal, the transmission unit transmits the second signal sequence in synchronization with the first signal sequence received from a path having a shortest delay time.

27. A mobile station device at a mobile station in a cellular mobile communication system for carrying out communications between base stations and mobile stations, comprising:

a reception unit for receiving a first signal sequence transmitted by a base station, which is uniquely predetermined for the mobile station; and

a transmission unit for transmitting a second signal sequence which is uniquely predetermined for the mobile station, to the base station in synchronization with the first signal sequence received by the reception unit, so as to enable the base station to estimate a position of the mobile station by calculating an estimated distance between the base station and the mobile station according to a phase difference between the first signal sequence and the second signal sequence.

28. The mobile station device of claim 27, wherein when the reception unit receives multipath signal, the transmission unit transmits the second signal sequence in synchronization with the first signal sequence received from a path having a shortest delay time.

29. A base station device at a base station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising:

a transmission unit for transmitting to a mobile station a first signal sequence which is uniquely predetermined for the mobile station;

a reception unit for receiving a second signal sequence transmitted by the mobile station, which is uniquely predetermined for the mobile station; and

a position estimation unit for estimating a position of the mobile station by obtaining a phase difference by comparing phases of the first signal sequence transmitted by the transmission unit and the second signal sequence received by the reception unit, and calculating an estimated distance between the base station and the mobile station according to the phase difference.

30. The base station device of claim 29, wherein when the reception unit receives multipath signal, the position estimation unit obtains the phase difference by using the second signal sequence received from a path having a shortest delay time.

31. A mobile station device at a mobile station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising:

a transmission unit for transmitting to a base station a first signal sequence which is uniquely predetermined for the mobile station;

a reception unit for receiving a second signal sequence transmitted by the base station, which is uniquely predetermined for the mobile station; and

a position estimation unit for estimating a position of the mobile station by obtaining a phase difference by comparing phases of the first signal sequence transmitted by the transmission unit and the second signal sequence received by the reception unit, and calculating an estimated distance between the base station and the mobile station according to the phase difference.

32. The mobile station device of claim 31, wherein when the reception unit receives multipath signal, the position estimation unit obtains the phase difference by using the second signal sequence received from a path having a shortest delay time.

33. A base station device at a base station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising:

a transmission unit for transmitting to a mobile station a first signal sequence which is uniquely predetermined for the mobile station;

a reception unit for receiving a second signal sequence which is uniquely predetermined for the mobile station and information on a first phase difference indicating a phase difference between the first signal sequence and the second signal sequence as obtained by the mobile station, which are transmitted by the mobile station; and

a position estimation unit for estimating a position of the mobile station by obtaining a second phase difference by comparing phases of the first signal sequence transmitted by the transmission unit and the second signal sequence received by the reception unit, and calculating an estimated distance between the base station and the mobile station according to the first phase difference received by the reception unit and the second phase difference.

34. The base station device of claim 33, wherein when the reception unit receives multipath signal, the position estimation unit obtains the second phase difference by using the second signal sequence received from a path having a shortest delay time.

35. A mobile station device at a mobile station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising:

a transmission unit for transmitting to a base station a first signal sequence which is uniquely predetermined for the mobile station;

a reception unit for receiving a second signal sequence which is uniquely predetermined for the mobile station and information on a first phase difference indicating a phase difference between the first signal sequence and the second signal sequence as obtained by the base station, which are transmitted by the base station; and

a position estimation unit for estimating a position of the mobile station by obtaining a second phase difference by comparing phases of the first signal sequence transmitted by the transmission unit and the second signal sequence received by the reception unit, and calculating an estimated distance between the base station and the mobile station according to the first phase difference received by the reception unit and the second phase difference.

36. The mobile station device of claim 35, wherein when the reception unit receives multipath signal, the position estimation unit obtains the second phase difference by using the second signal sequence received from a path having a shortest delay time.

37. A base station device at a base station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising:

a reception unit for receiving a first signal sequence transmitted by a mobile station, which is uniquely predetermined for the mobile station; and

a transmission unit for obtaining a first phase difference by comparing phases of the first signal sequence received by the reception unit and a second signal sequence which is uniquely predetermined for the mobile station, and transmitting the second signal sequence and information on the first phase difference to the mobile station, so as to enable the mobile station to obtain a second phase difference by comparing phases of the first signal sequence and the second signal sequence and estimate a position of the mobile station by calculating an estimated distance between the base station and the mobile station according to the first phase difference and the second phase difference.

38. The base station device of claim 37, wherein when the reception unit receives multipath signal, the transmission unit obtains the first phase difference by using the first signal sequence received from a path having a shortest delay time.

39. A mobile station device at a mobile station in a cellular mobile communication system for carrying out communications between mobile stations and base stations, comprising:

a reception unit for receiving a first signal sequence transmitted by a base station, which is uniquely predetermined for the mobile station; and

a transmission unit for obtaining a first phase difference by comparing phases of the first signal sequence received by the reception unit and a second signal sequence which is uniquely predetermined for the mobile station, and transmitting the second signal sequence and information on the first phase difference to the base station, so as to enable the base station to obtain a second phase difference by comparing phases of the first signal sequence and the second signal sequence and estimate a position of the mobile station by calculating an estimated distance between the base station and the mobile station according to the first phase difference and the second phase difference.

40. The mobile station device of claim 39, wherein when the reception unit receives multipath signal, the transmission unit obtains the first phase difference by using the first signal sequence received from a path having a shortest delay time.