Base station with slave antenna for determining the position of a mobile subscriber in a CDMA cellular telephone system

• US 6,195,046 B1
• Filed: 06/06/1996
• Issued: 02/27/2001
• Est. Priority Date: 06/06/1996
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gilhousen, Klein S.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/659,406
• Time in Patent Office: 1,727 Days
• Field of Search: 342/387, 342/457, 342/463, 342/464, 342/465, 379/63, 379/59, 455/456, 455/562
• US Class Current: 342/457
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0254 detecting a user operation or a tactile contact or a motion of the device
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method for determining the position of a mobile station using a base station having three antennas. The first antenna is used to transmit a first signal modulated with a first preassigned Walsh code. The second antenna is used to transmit a second signal modulated with a second preassigned Walsh code. A third antenna is used to transmit a third signal modulated with a third preassigned Walsh code. Each of the three signals is also modulated with a common spreading code in addition to the first, second and third Walsh codes. Each of the three signals are received by the mobile station. The mobile station determines the time of arrival of each such signal. Based upon these relative times of arrival, the mobile station determines its location.

Claims

1. A method for determining the position of a mobile station within a cellular telephone system, said cellular telephone system having a base station with first, second and third antennas, comprising the steps of:

(A) transmitting a first signal having a first preassigned Walsh code from said first antenna of said base station to said mobile station, transmitting a second signal having a second preassigned Walsh code from said second antenna of said base station to said mobile station, and transmitting a third signal having a third preassigned Walsh code from said third antenna of said base station to said mobile station, each of said first, second and third signals being modulated with a common spreading code, in addition to the first, second and third Walsh codes;

(B) receiving said first, second and third signals at said mobile station at first, second and third relative receptions times, respectively;

(C) determining first and second positional measurements in accordance with said first, second and third relative reception times; and

(D) determining said position of said mobile station in accordance with said first and second positional measurements.

2. The method of claim 1, wherein said second and third antennas are each within 300 feet of said first antenna.

3. The method of claim 1, wherein said first, second and third signals are all transmitted in step (A) on a common RF channel.

4. The method of claim 1 further comprising the step of:

(E) sending said first and second positional measurements to a switching center of said cellular system;

wherein said step (D) is performed within said switching center of said cellular system.

5. The method of claim 1 further comprising the step of:

(F) sending said first and second positional measurements to said base station;

wherein said step (D) is performed within said base station.

6. The method of claim 1, wherein said first, second and third relative reception times respectively represent a first clock synchronization setting associated with said receiving of said first signal at said mobile station, a second clock synchronization setting associated with said receiving of said second signal at said mobile station, and a third clock synchronization setting associated with said receiving of said third signal at said mobile station.

7. The method of claim 6, wherein said first positional measurement represents a first difference between said first clock synchronization setting and said second clock synchronization setting, and wherein said second positional measurement represents a second difference between said first clock synchronization setting and said third clock synchronization setting.

8. The method of claim 1, wherein said cellular telephone system is a time division multiple access cellular telephone system.