Device and method for locating a mobile station in a mobile communication system

• US 6,275,186 B1
• Filed: 12/10/1999
• Issued: 08/14/2001
• Est. Priority Date: 12/10/1998
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kong, Seung-Hyun
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H
• Application Number:
  US09/459,052
• Time in Patent Office: 613 Days
• Field of Search: 342/463, 342/464, 342/450, 342/457, 455/456, 455/404
• US Class Current: 342/463
• 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: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A device and method for locating a mobile station (MS) in a mobile communication system. In the MS locating device for an MS which receives signals synchronized to a predetermined time from at least one adjacent base station (BS) and is located within a serving BS of the at least one BS, an analog to digital converter (ADC) converts the received BS signals to digital chip sample data, a memory stores the chip sample data, a dedicated searcher detects at least two signals by correlating the chip sample data received from the memory by off-line processing and calculates the signal-to-interference ratios (SIRs) and time difference of arrival (TDOA) of the two signals, and a controller estimates the MS location based on the SIRs and TDOA received from the dedicated searcher.

Claims

1. A device for locating a mobile station (MS) having signals received from a plurality of adjacent base stations (BSs) in a mobile communication system, comprising:

an analog-to-digital converter (ADC) for converting the received signals to digital chip sample data;

a memory for storing the chip sample data provided from the ADC for a required measure time;

a dedicated searcher for detecting at least two signals satisfying a threshold from the chip sample data based on a correlation length and a PN (Pseudo Noise) offset, and calculating a signal-to-interference ratio (SIR) and a time difference of arrival (TDOA) of the detected signals; and

a controller for outputting the correlation length and the PN offset to the dedicated searcher based on the SIR and TDOA provided from the dedicated searcher.

2. The device as claimed in claim 1, wherein the controller provides the dedicated searcher with at least one correlation length for PN offsets of said adjacent BSs.

3. The device as claimed in claim 2, wherein the threshold is based on the correlation length.

4. The device as claimed in claim 2, wherein the controller increases the correlation length by a predetermined length when the dedicated searcher fails to detect the signals.

5. The device as claimed in claim 1, wherein the dedicated searcher performs correlation on the chip sample data newly stored in the memory with the correlation length used for the previous chip sample data, and, when a specific signal detected by performing correlation exceeds a threshold of the received signal according to said correlation length, performs correlation while decreasing said correlation length until said threshold is satisfied.

6. The device as claimed in claim 1, wherein the controller controls a quantization unit of the ADC according to an SIR from a serving BS out of the adjacent BSs.

7. The device as claimed in claim 1, wherein the dedicated searcher comprises:

a searcher for outputting an SIR and an offset index of a signal satisfying a threshold from the chip sample data based on the correlation length and the PN offset provided from the controller;

a path selector for selecting an offset index corresponding to the earliest path from the offset indexes provided from the searcher and an SIR corresponding to said offset index;

a PN generator for generating a PN code of the corresponding signal based on the PN offset from the controller and the offset index from the path selector;

a decimator for extracting an early sample and a late sample being apart from said early sample by a predetermined chip period on the basis of a specific sample of the chip sample data;

a correlator for outputting an early signal correlation value and a late signal correlation value by performing correlation on the PN code from the PN generator and the early sample and the late sample from the decimator based on the correlation length;

a time tracker for outputting a time offset correction value according to the early signal correlation value and the late signal correlation value;

an accumulator for accumulating the time offset correction value from the time tracker according to the correlation length;

a summation device for correcting the time offset index from the path selector with the time offset correction value accumulated by the accumulator, to output a TDOA; and

a reference time compensator for compensating for a reference time error for the TDOA.

8. A device for locating a mobile station (MS) having signals received from a plurality of adjacent base stations (BSs) in a mobile communication system, comprising:

an analog-to-digital converter (ADC) for converting the received signals to digital chip sample data;

a dedicated searcher for detecting at least two signals satisfying a threshold from the chip sample data based on a correlation length and a pseudo noise (PN) offset, and calculating a signal-to-interference ratio (SIR) and a time difference of arrival (TDOA) of the detected signals; and

a controller for outputting the correlation length and the PN offset to the dedicated searcher based on the SIR and TDOA provided from the dedicated searcher.

9. The device as claimed in claim 8, wherein the controller provides the dedicated searcher with at least one correlation length for PN offsets of said adjacent BSs.

10. The device as claimed in claim 9, wherein the threshold is based on the correlation length.

11. The device as claimed in claim 8, wherein the controller increases the correlation length by a predetermined length when the dedicated searcher fails to detect the signals.

12. The device as claimed in claim 8, wherein the controller controls a quantization unit of the ADC according to an SIR from a serving BS out of the adjacent BSs.

13. The device as claimed in claim 8, wherein the dedicated searcher comprises:

a searcher for outputting an SIR and an offset index of a signal satisfying a threshold from the chip sample data based on the correlation length and the PN offset provided from the controller;

a path selector for selecting an offset index corresponding to an earliest path from the offset indexes provided from the searcher and an SIR corresponding to said offset index;

a PN generator for generating a PN code of the corresponding signal based on the PN offset from the controller and the offset index from the path selector;

a decimator for extracting an early sample and a late sample being apart from said early sample by a predetermined chip period on the basis of a specific sample of the chip sample data;

a correlator for outputting an early signal correlation value and a late signal correlation value by performing correlation on the PN code from the PN generator and the early sample and the late sample from the decimator depending on the correlation length;

a time tracker for outputting a time offset correction value according to the early signal correlation value and the late signal correlation value;

an accumulator for accumulating the time offset correction value from the time tracker according to the correlation length;

a summation device for correcting the time offset index from the path selector with the time offset correction value accumulated by the accumulator, to output a TDOA; and

a reference time compensator for compensating for a reference time error for the TDOA.

14. A method for locating a mobile station (MS) having signals received from a plurality of adjacent base stations (BSs) in a mobile communication system, comprising the steps of:

converting the received signals to digital chip sample data;

detecting at least two signals satisfying a threshold from the chip sample data based on a correlation length and a pseudo noise (PN) offset, and calculating a signal-to-interference ratio (SIR) and a time difference of arrival (TDOA) of the detected signals; and

outputting the correlation length and the PN offset based on the SIR and TDOA.

15. The method as claimed in claim 14, wherein in the correlation length output step, at least one correlation length is output for PN offsets of said adjacent BSs.

16. The method as claimed in claim 15, wherein the threshold is based on the correlation length.

17. The method as claimed in claim 14, wherein the correlation length increases by a predetermined length upon failure to detect the signals.

18. The method as claimed in claim 14, wherein a quantization unit for digital conversion is controlled according to an SIR from a serving BS out of the adjacent BSs.

19. The method as claimed in claim 14, wherein the calculating step comprises the steps of:

outputting an SIR and an offset index of a signal satisfying a threshold from the chip sample data based on the correlation length and the PN offset;

selecting an offset index corresponding to an earliest path from the offset indexes provided from the searcher and an SIR corresponding to said offset index;

generating a PN code of the corresponding signal based on the PN offset and the offset index;

extracting an early sample and a late sample being apart from said early sample by a predetermined chip period on the basis of a specific sample of the chip sample data;

outputting an early signal correlation value and a late signal correlation value by performing correlation on the early sample and the late sample depending on the correlation length;

outputting a time offset correction value according to the early signal correlation value and the late signal correlation value;

accumulating the time offset correction value according to the correlation length;

correcting the time offset index with the accumulated time offset correction value, to output a TDOA; and

compensating for a reference time error for the TDOA.

20. A method for locating a mobile station (MS) having signals received from a plurality of adjacent base stations (BSs) in a mobile communication system, comprising the steps of:

converting the received signals to digital chip sample data;

storing the chip sample data for a required measure time;

detecting at least two signals satisfying a threshold from the chip sample data based on a correlation length and a pseudo noise (PN) offset, and calculating a signal-to-interference ratio (SIR) and a time difference of arrival (TDOA) of the detected signals; and

outputting the correlation length and the PN offset based on the SIR and TDOA.

21. The method as claimed in claim 20, wherein in the correlation length output step, at least one correlation length is output for PN offsets of said adjacent BSs.

22. The method as claimed in claim 21, wherein the threshold is based on the correlation length.

23. The method as claimed in claim 21, wherein the correlation length increases by a predetermined length upon failure to detect the signals.

24. The method as claimed in claim 20, wherein a quantization unit for digital conversion is controlled according to an SIR from a serving BS out of the adjacent BSs.

25. The method as claimed in claim 20, wherein the calculating step comprises the steps of:

outputting an SIR and an offset index of a signal satisfying a threshold from the chip sample data based on the correlation length and the PN offset;

selecting an offset index corresponding to an earliest path from the offset indexes provided from the searcher and an SIR corresponding to said offset index;

generating a PN code of the corresponding signal based on the PN offset and the offset index;

extracting an early sample and a late sample being apart from said early sample by a predetermined chip period on the basis of a specific sample of the chip sample data;

outputting an early signal correlation value and a late signal correlation value by performing correlation on the early sample and the late sample depending on the correlation length;

outputting a time offset correction value according to the early signal correlation value and the late signal correlation value;

accumulating the time offset correction value according to the correlation length;

correcting the time offset index with the accumulated time offset correction value, to output a TDOA; and

compensating for a reference time error for the TDOA.

26. A method for locating a mobile station (MS) depending on at least two signals having different PN offsets acquired from digital chip sample data obtained by converting signals received from at least one adjacent base station (BS), the method comprising the steps of:

(a) calculating signal-to-interference ratios (SIRs) and at least one time difference of arrival (TDOA) of the acquired at least two signals;

(b) determining whether the acquired at least two signals are received from the same BS;

(c) locating, when the at least two signals are received from the same BS, the MS based on a direction of the MS and a distance from the base station; and

(d) locating, when the at least two signals are received from different BSs, the MS based on the calculated SIRs and at least one TDOA.

27. The method as claimed in claim 26, wherein the step (c) comprises the steps of:

estimating the direction of the MS on the basis of the base station using the SIRs and a SIR map;

calculating the distance between the MS and the BS using a round trip delay (RTD); and

locating the MS based on the estimated direction of the MS and the calculated distance.

28. The method as claimed in claim 26, wherein the step (d) comprises the steps of:

determining a parabola representing a probable position of the MS using the calculated at least one TDOA and a TDOA map between the different BSs;

determining a probable position line representing a probable position of the MS using the calculated SIRs and a SIR map between the different BSs; and

locating the MS based on an intersecting point of the parabola and the probable position line.

29. The method as claimed in claim 26, further comprising the step of locating, when at least three SIRs and at least three TDOAs are calculated for at least three BS signals, the MS using the calculated at least three SIRs and at least three TDOAs.

30. The method as claimed in claim 28, wherein the position of the MS is estimated by an average of the probable positions constituting the parabola duration between the intersecting points.