System and method of dynamically calibrating based station timing using location information

• US 6,687,501 B2
• Filed: 07/20/2001
• Issued: 02/03/2004
• Est. Priority Date: 10/10/2000
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Soliman, Samir S.
• Primary Examiner(s): Maung, Nay
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US09/910,517
• Publication Number:
  US 20020065089A1
• Time in Patent Office: 928 Days
• Field of Search: 455/423, 455/424, 455/67.1, 455/561, 455/67.11, 455/67.14, 455/67.16, 370/335
• US Class Current: 455/424
• CPC Class Codes: H04W 56/006 using known positions of transmitter and receiver
• CPC Class Codes: H04W 56/009 Closed loop measurements

Abstract

A system and method for dynamically calibrating a base station in a wireless communication system, is presented herein. In accordance with an embodiment of the invention, the system includes a base station for transmitting, receiving, and processing communication signals and a wireless communication device for communicating with the base station. The wireless communication device is configured to determine its location (e.g., using GPS information), to detect the arrival time of a first signal transmitted from the base station, and to calculate a line-of-sight (LOS) delay corresponding to the LOS distance between the wireless communication device and the base station. The LOS distance calculation is based on the base station location information and the wireless communication device location information. The base station measures a round trip delay (RTD) corresponding to the delay incurred by the first signal and a delay incurred by a second signal transmitted from the wireless communication device back to the base station in response to the first signal. The base station then determines a base station timing calibration error based on the LOS delay, the first signal arrival time, and the RTD, and dynamically calibrates the base station timing to compensate for the base station timing calibration error.

Claims

1. A method for calibrating timing of base station in a wireless communication system, comprising:

determining location information of a wireless communication device;

calculating a line-of-sight delay corresponding to a line-of-sight distance between said wireless communication device and said base station, said line-of-sight distance based on base station location information and said wireless communication device location information;

detecting an arrival time of a first signal transmitted from said base station to said wireless communication device;

measuring a round trip delay corresponding to a delay incurred by said first signal and a delay incurred by a second signal transmitted from said wireless communication device back to said base station in response to said first signal;

determining a base station timing calibration error based on said line-of-sight delay, said first signal arrival time, and said round trip delay; and

calibrating said base station timing to compensate for said base station timing calibration error;

wherein said line-of-sight delay is determined by the following relationship;

${\mathrm{\Delta <br><br>}}_{\mathrm{los}}=\frac{\sqrt{{\left(x_b-x_w\right)}^2+{\left(y_b-y_w\right)}^2+{\left(z_b-z_w\right)}^2}}{c}$

where;

Δ

_los represents the line-of-sight delay,

x_b, y_b, and Z_b represent coordinate information identifying the base station location information,

x_w, y_w, z_w represent coordinate information identifying the wireless communication device location information, and

c represents the speed of light.

2. The method of claim 1, wherein said determining base station timing calibration error includes determining a forward link base station calibration timing error based on said first signal arrival time, said line-of-sight delay, and a wireless communication device processing delay.

3. The method of claim 2, wherein said determining base station timing calibration error further includes determining a reverse link base station calibration timing error based on said round trip delay, said first signal arrival time, said line-of-sight delay, and said wireless communication device processing delay.

4. The method of claim 3, wherein said forward link base station calibration timing error is determined by the following relationship:

Δ

_bf=τ

_arr−

Δ

_wf−

Δ

_LOS,

where;

Δ

_bf represents the forward link base station calibration timing error,

 

Δ

_wf represents the wireless communication device processing delay,

 

τ

_arr represents the first signal arrival time, and

 

Δ

_LOS represents the line-of-sight delay.

5. The method of claim 4, wherein said reverse link base station calibration timing error is determined by the following relationship:

Δ

_br==RTD+Δ

_wf −

τ

_arr−

Δ

_LOS,

 

where;

Δ

_br represents the reverse link base station calibration timing error,

 

RTD represents the round trip delay,

 

Δ

_wf represents the wireless communication device processing delay,

 

Δ

_arr represents the first signal arrival time, and

 

Δ

_LOS represents the line-of-sight delay.

6. The method of claim 5, wherein said measuring round-trip delay further includes,

measuring a plurality of delays corresponding to a plurality of first signals transmitted from said base station to said wireless communication device and a plurality of second signals transmitted from said wireless communication device to said base station, in response to said first signals, and

averaging said plurality of delays to determine said round trip delay.

7. The method of claim 6, wherein said calibrating base station timing to compensate for said base station timing calibration error includes adjusting a transmission time for signals transmitted from said base station to said wireless communication device by an amount equivalent to said forward link base station calibration timing error.

8. The method of claim 7, wherein said calibrating base station timing to compensate for said base station timing calibration error further includes adjusting a reception time for signals transmitted from said wireless communication device to said base station by an amount equivalent to said reverse link base station calibration timing error.

9. The method of claim 8, wherein said determining location information of said wireless communication device includes employing a global positioning satellite mechanism in said wireless communication device, said global positioning satellite mechanism configured to receive timing and frequency information from a plurality of participating satellites and to determine its location based on said timing and frequency information.

10. A system for calibrating base station timing in a wireless communication system, comprising:

a base station for transmitting, receiving, and processing communication signals; and

a wireless communication device for communicating with said base station, said wireless communication device configured to determine its location, to detect an arrival time of a first signal transmitted from said base station, and to calculate a line-of-sight delay corresponding to a line-of-sight distance between said wireless communication device and said base station, said line-of-sight distance based on base station location information and said wireless communication device location information,

wherein said base station measures a round trip delay corresponding to a delay incurred by said first signal and a delay incurred by a second signal transmitted from said wireless communication device back to said base station in response to said first signal, and

wherein said base station determines a base station timing calibration error based on said line-of-sight delay, said first signal arrival time, and said round trip delay, and calibrates said base station timing to compensate for said base station timing calibration error;

wherein said line-of-sight delay is determined by the following relationship;

${\mathrm{\Delta <br><br>}}_{\mathrm{los}}=\frac{\sqrt{{\left(x_b-x_w\right)}^2+{\left(y_b-y_w\right)}^2+{\left(z_b-z_w\right)}^2}}{c}$

where;

Δ

_los represents the line-of-sight delay,

 

x_b, y_b, and z_b represent coordinate information identifying the base station location information,

 

x_w, y_w, z_q represent coordinate information identifying the wireless communication device location information, and

 

c represents the speed of light.

11. The system of claim 10, said base station timing calibration error includes g a forward link base station calibration timing error based on said first signal arrival time, said line-of-sight delay, and a wireless communication device processing delay.

12. The system of claim 11, wherein said base station timing calibration error further includes a reverse link base station calibration timing error based on said round trip delay, said first signal arrival time, said line-of-sight delay, and said wireless communication device processing delay.

13. The system of claim 12, wherein said forward link base station calibration timing error is determined by the following relationship:

Δ

_bf=τ

_arr−

Δ

_wf−

Δ

_LOS,

where;

Δ

_bf represents the forward link base station calibration timing error,

 

Δ

_wf represents the wireless communication device processing delay,

 

ρ

arr represents the first signal arrival time, and

 

Δ

_LOS represents the line-of-sight delay.

14. The system of claim 13, wherein said reverse link base station calibration timing error is determined by the following relationship:

Δ

_br==RTD+A_wf−

τ

_arr−

Δ

_LOS,

where;

Δ

_br represents the reverse link base station calibration timing error,

 

RTD represents the round trip delay,

 

Δ

_wf represents the wireless communication device processing delay, Ε

_arr represents the first signal arrival time, and

Δ

_LOS represents the line-of-sight delay.

15. The system of claim 14, wherein said round-trip delay includes an average of a plurality of delays corresponding to a plurality of first signals transmitted from said base station to said wireless communication device and a plurality of second signals, responsive to said first signals, transmitted from said wireless communication device to said base station.

16. The system of claim 15, wherein said base station calibrates said base station timing by adjusting a transmission time for signals transmitted from said base station to said wireless communication device by an amount equivalent to said forward link base station calibration timing error.

17. The system of claim 16, wherein said when in said base station calibrates said base station timing by adjusting a reception time for signals transmitted from said wireless communication device to said base station by an amount equivalent to said reverse link base station calibration timing error.

18. The system of claim 17, wherein said wireless communication device determines said wireless communication device location information by employing a global positioning satellite mechanism, said global positioning satellite mechanism configured to receive timing and frequency information from a plurality of participating satellites and to determine its location based on said timing and frequency information.

19. A machine-readable medium encoded with a plurality of processor-executable instruction sequences for calibrating timing of a base station in a wireless communication system, said instruction sequences comprising:

determining location information of a wireless communication device;

calculating a line-of-sight delay corresponding to a line-of-sight distance between said wireless communication device and said base station, said line-of-sight distance based on base station location information and said wireless communication device location information;

detecting an arrival time of a first signal transmitted from aid base station to said wireless communication device;

measuring a round trip delay corresponding to a delay incurred by said first signal and a delay incurred by a second signal transmitted from said wireless communication device back to said base station in response to said first signal;

determining a base station timing calibration error based on said line-of-sight delay, said first signal arrival time, and said round trip delay; and

calibrating said base station timing to compensate for said base station timing calibration error;

wherein said line-of-sight delay is determined by the following relationship;

${\mathrm{\Delta <br><br>}}_{\mathrm{los}}=\frac{\sqrt{{\left(x_b-x_w\right)}^2+{\left(y_b-y_w\right)}^2+{\left(z_b-z_w\right)}^2}}{c}$

where;

Δ

_los represents the line-of-sight delay,

 

x_b, y_b and z_b represent coordinate information identifying the base station location information,

 

x_w, x_w, z_q represent coordinate information identifying th wireless communication device location information, and

 

c represents the speed of light.

20. The machine-readable medium of claim 19, wherein said determining base station timing calibration error includes determining a forward link base station calibration timing error based on said first signal arrival time, said line-of-sight delay, and a wireless communication device processing delay.

21. The machine-readable medium of claim 20, wherein said determining base station timing calibration error further includes determining a reverse link base station calibration timing error based on said round trip delay, said first signal arrival time, said line-of-sight delay, and said wireless communication device processing delay.

22. The machine-readable medium of claim 21, wherein said forward link base station calibration timing error is determined by the following relationship:

Δ

_bf=τ

_arr−

Δ

_wf−

Δ

_LOS,

where;

Δ

_bf represents the forward link base station calibration timing error,

 

Δ

_wf represents the wireless communication device processing delay,

 

τ

_arr represents the first signal arrival time, and

Δ

_LOS represents the line-of-sight delay.

23. The machine-readable medium of claim 22, herein said reverse link base station calibration timing error is determined by the following relationship:

 

Δ

br =RTD+Δ

_wf−

Σ

_arr−

Δ

_LOS,

where;

Δ

_br represents the reverse link base station calibration timing error,

 

RTD represents the round trip delay,

 

Δ

_wf represents the wireless communication device processing delay,

 

τ

_arr represents the first signal arrival time, and

Δ

_LOS represents the line-of-sight delay.

24. The machine-readable medium of claim 23, wherein said measuring round-trip delay further includes,

measuring a plurality of delays corresponding to a plurality of first signals transmitted from said base station to said wireless communication device and a plurality of second signals transmitted from said wireless communication device to said base station, in response to said first signals, and averaging said plurality of delays to determine said round trip lay.

25. The machine-readable medium of claim wherein said calibrating base station timing to compensate for said base station timing calibration error includes adjusting a transmission time for signals transmitted from said base station to said wireless communication device by an amount equivalent to said forward link base station calibration timing error.

26. The machine-readable medium of claim 25, wherein said calibrating base station timing to compensate for said base station timing calibration error further includes adjusting a reception time for signals transmitted from said wireless communication device to said base station by an amount equivalent to said reverse link base station calibration timing error.

27. The machine-readable medium of claim 26, wherein said determining location information of said wireless communication device includes employing a global positioning satellite mechanism in said wireless communication device, said global positioning satellite mechanism configured to receive timing and frequency information from a plurality of participating satellites and to determine its location based o said timing and frequency information.