Method of locating a mobile phone by measuring the distance between the phone and a base station in a cellular mobile telephone system

• US 6,408,186 B1
• Filed: 01/21/2000
• Issued: 06/18/2002
• Est. Priority Date: 01/23/1999
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Jee-Yeon, Wee, Pyeong-Hwan
• Primary Examiner(s): Hunter, Daniel
• Assistant Examiner(s): TRAN, TUAN A
• Application Number:
  US09/488,808
• Time in Patent Office: 879 Days
• Field of Search: 455/423, 455/424, 455/67.1, 455/67.6, 455/456, 342/357.02, 342/357.08, 701/214
• US Class Current: 455/456.1
• CPC Class Codes: G01S 13/76 wherein pulse-type signals are transmitted
• CPC Class Codes: G01S 7/40 Means for monitoring or calibrating
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method of measuring the distance between a mobile phone and a base station based on the round-trip delay (RTD) of a prescribed message transmitted from the base station to the mobile phone in a cellular mobile telephone system (CMTS), comprising the steps of calculating a mean error distance to adjust the distance between the base station and the mobile phone within the cell boundary of the base station, measuring the RTD between the base station and the mobile phone positioned at an arbitrary point within the cell, calculating the RTD distance between the base station and the mobile phone based on the RTD measurement by subtracting the mean error distance from the RTD distance.

Claims

1. A method for measuring a mean error distance to adjust the distance between a mobile phone and a base station in a cell obtained by a round-trip delay (RTD) of a prescribed message transmitted from said base station to said mobile phone in a cellular mobile telephone system (CMTS), said method comprising the steps of:

determining a plurality of measuring points within the cell of said base station to be used for obtaining said mean error distance;

measuring respective RTDs between said measuring points and said base station by sequentially positioning said mobile phone at each of said measuring points;

calculating respective RTD distances between said measuring points and said base station based on said RTD measurements;

obtaining respective Global Positioning System(GPS) data for said measuring points and said base station;

calculating respective GPS distances between said measuring points and said base station based on said GPS data;

calculating respective error distances by taking the difference between said respective RTD distances and said GPS distances; and

,

obtaining said mean error distance from said respective error distances.

2. The method as defined in claim 1, wherein said step of measuring the respective RTDs between said measuring points and said base station further includes the steps of providing said mobile phone to establish a call connection with said base station and providing said base station to trace an electronic serial number of said mobile phone.

3. The method as defined in claim 1, wherein each of said respective RTDs is represented by a sum of a forward propagation delay by said prescribed message when transmitted from said base station to said mobile phone, a reverse propagation delay by said message returning from said mobile phone to said base station, and a system delay for said base station to demodulate and analyze said returned message.

4. The method as defined in claim 3, wherein said step of calculating said respective RTD distances between said measuring points and said base station further includes the steps of calculating one-way propagation delay from said measured RTD and calculating one-way wave distance from said measured RTD.

5. The method as defined in claim 4, wherein said one-way propagation delay is obtained by subtracting said system delay from said respective RTD and dividing the remainder by two.

6. The method as defined in claim 4, wherein said one-way wave distance is obtained by multiplying said one way propagation delay by the speed of light and the transmission speed of chip unit for said CMTS.

7. A method for measuring the distance between a mobile phone and a base station based on the round-trip delay (RTD) of a prescribed message transmitted from said base station to said mobile phone in a cellular mobile telephone system (CMTS), said method comprising the steps of:

calculating a mean error distance to adjust said distance between said base station and said mobile phone within the cell boundary of said base station;

measuring the RTD between said base station and said mobile phone positioned at an arbitrary point within the boundary of said cell;

calculating the RTD distance between said base station and said mobile phone based on said measured RTD; and

,

subtracting said mean error distance from said calculated RTD distance.

8. The method as defined in claim 7, wherein the step of calculating said mean error distance further includes the steps of:

determining a plurality of measuring points within the cell of said base station to be used for obtaining said mean error distance;

measuring respective RTDs between said measuring points and said base station by sequentially positioning said mobile phone at each of said measuring points;

calculating respective RTD distances between said measuring points and said base station based on said RTD measurements;

obtaining respective Global Positioning System(GPS) data for said measuring points and said base station;

calculating respective GPS distances between said measuring points and said base station based on said GPS data;

calculating respective error distances by taking the difference between said respective RTD distances and said GPS distances; and

,

obtaining said mean error distance from said respective error distances.

9. The method as defined in claim 8, wherein said step of measuring the respective RTDs between said measuring points and said base station further includes the steps of providing said mobile phone to establish a call connection with said base station and providing said base station to trace an electronic serial number of said mobile phone.

10. The method as defined in claim 8, wherein each of said respective RTDs is represented by a sum of a forward propagation delay by said prescribed message when transmitted from said base station to said mobile phone, a reverse propagation delay by said message returning from said mobile phone to said base station, and a system taken for said base station to demodulate and analyze said returned message.

11. The method as defined in claim 10, wherein said step of calculating said respective RTD distances between said measuring points and said base station further includes the steps of calculating one-way propagation delay from said measured RTD and calculating one-way wave distance from said measured RTD.

12. The method as defined in claim 11, wherein said one-way propagation delay is obtained by subtracting said system delay from said respective RTD and dividing the remainder by two.

13. The method as defined in claim 11, wherein said one-way wave distance is obtained by multiplying said one way propagation delay by the speed of light and the transmission speed of chip unit for said CMTS.