Methods and apparatus for improving accuracy of radio timing measurements

• US 7,359,711 B2
• Filed: 06/13/2003
• Issued: 04/15/2008
• Est. Priority Date: 10/31/2002
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens Communications Incorporated (Siemens AG)
• Inventors: Edge, Stephen William, Manohar, Bollapragada V. J.
• Primary Examiner(s): Anderson, Matthew
• Assistant Examiner(s): HUANG, WEN WU
• Application Number:
  US10/460,982
• Publication Number:
  US 20040087269A1
• Time in Patent Office: 1,768 Days
• Field of Search: 455/456, 455/457, 455/404.2, 455/208, 455/265, 455/13.2, 375/144, 375/147, 375/148, 342/457, 342/387
• US Class Current: 455/456.1
• CPC Class Codes: H04B 7/2678 Time synchronisation
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 56/001 Synchronization between nodes

Abstract

A system, method, apparatus, means, and computer program code for improving accuracy of radio timing measurements. According to some embodiments, a wireless terminal or other wireless device can make adjustments to a measurement made from a radio transmission source by adjusting timing measurements using a weighted average and/or synchronizing its timing to the timing of this or some other radio transmission source. The adjusted measurements can be obtained for times other than when the original measurements are made. Measurements for multiple radio transmission sources can then be adjusted to a common time wherein adjustment errors due to unknown timing drift in the radio sources and wireless terminal and Doppler errors due to unknown relative velocities can be reduced or eliminated.

Claims

1. A method for improving the accuracy of a radio timing measurement made by a terminal, comprising:

making a first radio timing measurement for a radio transmission source at a time T*_x according to a timing reference in said terminal;

making a second radio timing measurement for said radio transmission source at a time T*_y according to a timing reference in said terminal;

determining a third radio timing measurement for said radio transmission source at a time T* according to a timing reference in said terminal based, at least in part, on said first radio timing measurement;

determining a fourth radio timing measurement for said radio transmission source at said time T* based, at least in part, on said second radio timing measurement;

determining a fifth radio timing measurement for said radio transmission source at said time T* based, at least in part, on said third radio timing measurement and said fourth radio timing measurement;

making radio timing measurements for said radio transmission source at 2M (M≧

1) sequential times T*₁, T*₂, . . . , T*_2M according to a timing source in said terminal, wherein said making said first and second radio timing measurements for said radio transmission source at said respective times T*_x and T*_y is part of said making timing measurements for said radio transmission source at said 2M sequential times T*₁, T*₂, . . . , T*_2M;

determining a radio timing measurement for said radio transmission source at said time T* for each of said 2M timing measurements for said radio transmission source at said 2M sequential times; and

determining a sixth radio timing measurement for said radio transmission source at said time T* based, at least in part, on said 2M radio timing measurements for said radio transmission source at said time T* determined from each of said 2M sequential radio timing measurements at times T*₁, T*₂, . . . , T*_2M, wherein said determining a sixth radio timing measurement employs a weighted average of said 2M radio timing measurements for said radio transmission source at said time T* where the weight for any radio timing measurement at said time T* determined from a radio timing measurement at time T*_i, (1≦

i≦

2M) is δ

_i/|T*−

T*_i| where δ

_i=−

1 or δ

_i=+1, wherein T* exceeds each of the time values T*_i, T*₂, . . . , T*_m and is less than each of the time values T*_m+1, T*_m+2, . . . , T*_2M where 0≦

m≦

2M and δ

_i(1≦

i≦

2M) is chosen so that;

δ

_i =+1 except as follows;

if m<

M;

δ

_i=−

1 for any (M−

m) indices i in the range (m+1, m+2, . . . 2M) that give Σ

(i=1 to i=2M) δ

_i/|T*_i−

T*|≠

0;

if m>

M;

δ

_i=−

1 for any (m−

M) indices i in the range (1, 2, . . . m) that give Σ

(i =1 to i=2M) δ

_i/|T*_i−

T*|≠

0;

if m=M;

all the values δ

_i are +1.

2. The method of claim 1, wherein said time T*_x and said time T*_y occur after said time T*.

3. The method of claim 1, wherein said time T*_x and said time T*_y occur before said time T*.

4. The method of claim 1, wherein said time T* occurs after said time T*_x and before said time T*_y.

5. The method of claim 1, wherein said determining a fifth radio timing measurement for said radio transmission source at said time T* includes determining a weighted average radio timing measurement.

6. The method of claim 1, further comprising:

determining a timing drift difference between said terminal and a second radio transmission source based, at least in part, on a radio timing measurement for said second radio transmission source at a time T1 and a radio timing measurement for said second radio transmission source at a time T2; and

determining an adjustment to said timing reference in said terminal based, at least in part, on said timing drift difference.

7. An apparatus for improving the accuracy of radio timing measurement information for a terminal, comprising:

a memory;

a communication port; and

a processor connected to said memory and said communication port, said processor being operative to;

making a first radio timing measurement for a radio transmission source at a time T*_x according to a timing reference in said terminal;

making a second radio timing measurement for said radio transmission source at a time T*_y according to a timing reference in said terminal;

determining a third radio timing measurement for said radio transmission source at a time T* according to a timing reference in said terminal based, at least in part, on said first radio timing measurement;

determining a fourth radio timing measurement for said radio transmission source at said time T* based, at least in part, on said second radio timing measurement;

determining a fifth radio timing measurement for said radio transmission source at said time T* based, at least in part, on said third radio timing measurement and said fourth radio timing measurement;

making radio timing measurements for said radio transmission source at 2M (M≧

1) sequential times T*₁, T*₂, . . . , T*_2M according to a timing source in said terminal, wherein said making said first and second radio timing measurements for said radio transmission source at said respective times T*_X and T*_y is part of said making timing measurements for said radio transmission source at said 2M sequential times T*₁, T*₂, . . . , T*_2M;

determining a radio timing measurement for said radio transmission source at said time T* for each of said 2M timing measurements for said radio transmission source at said 2M sequential times; and

determining a sixth radio timing measurement for said radio transmission source at said time T* based, at least in part, on said 2M radio timing measurements for said radio transmission source at said time T* determined from each of said 2M sequential radio timing measurements at times T*_i, T*₂, . . . , T*_2M, wherein said determining a sixth radio timing measurement employs a weighted average of said 2M radio timing measurements for said radio transmission source at said time T* where the weight for any radio timing measurement at said time T* determined from a radio timing measurement at time T*₁, (1≦

i≦

2M) is δ

_i|/T*−

T*_i| where δ

_i=+1 or δ

_i=−

1, and wherein T* exceeds each of the time values T*₁, T*₂, . . . , T*_m and is less than each of the time values T*_m+1, T*_m+2, . . . , T*_2M where 0≦

m≦

2M and δ

_i(1≦

i≦

2M) is chosen so that;

δ

_i=+1 except as follows;

if m<

M;

δ

_i=−

1 for any (M−

m) indices i in the range (m+1, m+2, . . . , 2M) that give Σ

(i=1 to i =2M) δ

_i/|T*₁−

T*|≠

0;

if m>

M;

δ

_i =−

1 for any (m−

M) indices i in the range (1, 2, . . . m) that give Σ

(i=1 to i=2M) δ

_i/|T*_i −

T*|≠

0;

if m=M;

all the values δ

_i are +1.

8. A computer program product in a computer readable medium for improving the accuracy of a radio timing measurement for a terminal, comprising:

instructions for making a first radio timing measurement for a radio transmission source at a time T*_x according to a timing reference in said terminal;

instructions for making a second radio timing measurement for said radio transmission source at a time T*_y according to a timing reference in said terminal;

instructions for determining a Third radio timing measurement for said radio transmission source at a time T* according to a timing reference in said terminal based, at least in part, on said first radio timing measurement;

instructions for determining a fourth radio timing measurement for said radio transmission source at said time T* based, at least in part, on said second radio timing measurement;

instructions for determining a fifth radio timing measurement for said radio transmission source at said time T* based, at least in part, on said third radio timing measurement and said fourth radio timing measurement;

instructions for making radio timing measurements for said radio transmission source at 2M (M≧

1) sequential times T*₁, T*₂, . . . , T*_2M according to a timing source in said terminal, wherein said making said first and second radio timing measurements for said radio transmission source at said respective times T*_x and T*_y is part of said making timing measurements for said radio transmission Source at said 2M sequential times T*₁, T*₂, . . . , T*_2M;

instructions for determining a radio timing measurement for said radio transmission source at said time T* for each of said 2M timing measurements for said radio transmission source at said 2M sequential times; and

instructions for determining a sixth radio timing measurement for said radio transmission source at said time T* based, at least in part, on said 2M radio timing measurements for said radio transmission source at said time T* determined from each of said 2M sequential radio timing measurements at times T*₁, T*₂, . . . , T*_2M, wherein said determining a sixth radio timing measurement employs a weighted average of said 2M radio timing measurements for said radio transmission source at said time T* where the weight for any radio timing measurement at said time T* determined from a radio timing measurement at time T*₁, (1≦

i≦

2M) is δ

_i/|T*−

T*_i| where δ

_i=+1 or δ

_i=−

1, and wherein T* exceeds each of the time values T*₁, T*₂, . . . , T*_m, and is less than each of the time values T*_m+1, T*_m+2, . . . , T*_2M where 0≦

m≦

2M and δ

_i (1≦

i≦

2M) is chosen so that;

δ

_i=+1 except as follows;

if m<

M;

δ

_i=−

1 for any (M−

m) indices i in the range (m+1, m+2, . . . 2M) that give Σ

(i=1 to i=2M) δ

_i/|T*_i−

T*|≠

0;

if m>

M;

δ

_i=−

1 for any (m−

M) indices i in the range (1, 2, . . . m) that give Σ

(i=1 to i=2M) δ

_i/|T*<sub>1−

T*|≠</sub>

0;

if m=M;

all the values δ

_i are +1.