Threshold Determination in TDOA-Based Positioning System

• US 20110205914A1
• Filed: 02/24/2010
• Published: 08/25/2011
• Est. Priority Date: 02/24/2010
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Frank, Colin D., Krishnamurthy, Sandeep H.
• Granted Patent: US 8,509,102 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: G01S 5/0221 Receivers
• 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: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method in a wireless communication terminal including receiving a signal comprising at least a Positioning Reference Signal (PRS) transmission from a serving cell and a PRS transmission from a neighbor cell, estimating a signal quality metric (SQM) based on the PRS transmission from the neighbor cell, estimating a time difference of arrival (TDOA) measurement for the neighbor cell based on the PRS transmissions, determining if the estimated SQM satisfies a criterion, and sending a report to the serving cell that includes at least the estimated TDOA if the criterion is satisfied.

Claims

1. A method in a wireless communication terminal, the method comprising:

receiving a signal comprising at least a Positioning Reference Signal (PRS) transmission from a serving cell and a PRS transmission from a neighbor cell;

estimating a signal quality metric (SQM) based on the PRS transmission from the neighbor cell and the received signal;

estimating a time difference of arrival (TDOA) measurement for the neighbor cell based on the PRS transmissions received from the neighbor cell and the received signal;

determining if the estimated SQM satisfies a criterion;

threshold T_X1<

=SQM<

=threshold T_X2, wherein at least one of the thresholds T_X1 or T_X2 is based on a physical channel identifier (PCID) of the serving cell and a PCID of the neighbor cell;

sending a report to the serving cell that includes the estimated TDOA if the criterion is satisfied.

2. The method of claim 1 further comprising determining a PRS frequency offset as MOD (PCID serving cell-PCID neighbor cell, 6).

3. The method of claim 1, wherein the signal quality metric corresponds to an estimation of power of the PRS transmission from the neighbor cell received at the wireless communication terminal.

4. The method of claim 1 further comprising

determining a noise measurement based on a signal from which an estimation of power of the PRS transmission from the neighbor cell received at the wireless communication terminal was obtained;

and

where the signal quality metric is based on an estimation of power of the PRS transmission from the neighbor cell and the noise measurement.

5. The method of claim 1 further comprising:

determining whether PRS from the serving cell transmission is muted during an occasion where the PRS transmission from the neighbor cell is received;

estimating the TDOA based on the PRS signal received during the occasion where the PRS transmission from the serving cell is muted wherein at least one of the thresholds T_X1 or T_X2 is based on whether the serving cell PRS transmission was muted.

6. The method of claim 1, sending the report to the serving cell that includes the PCID of the neighbor cell and the estimated TDOA if the criterion is satisfied.

7. A method in a wireless communication terminal, the method comprising:

receiving a signal comprising at least a Positioning Reference Signal (PRS) transmission from a serving cell and a PRS transmission from a neighbor cell;

estimating a signal quality metric (SQM) based on the PRS transmission from the neighbor cell;

estimating a time difference of arrival (TDOA) measurement for the neighbor cell based on the PRS transmissions received from the neighbor cell;

determining if the estimated SQM satisfies a first criterion threshold T_X1<

=SQM<

=threshold T_X2, wherein at least one of the thresholds T_X1 or T_X2 is based at least in part on a signal received from the serving cell;

sending a report to the serving cell that includes the estimated TDOA if the first criterion is satisfied.

8. The method of claim 7 further comprising determining at least one of T_X1 and T_X2 based on a serving cell signal power received at the wireless communication terminal.

9. The method of claim 14 further comprising,

determining whether a strength of a signal received from the serving cell satisfies a second criterion:

threshold T_Y1<

=SCSS<

=threshold T_Y2; and

sending the report to the serving cell only if the first and second criteria are satisfied.

10. The method of claim 9 wherein at least one of the thresholds T_Y1 and T_Y2 is based on whether autonomous muting is enabled.

11. The method of claim 9 wherein the signal received from the serving cell corresponds to the PRS transmission received from the serving cell.

12. The method of claim 9 wherein the signal received from the serving cell corresponds to a cell specific reference signal received from the serving cell.

13. The method claim 7 wherein the signal received from the serving cell is a system information message, a LTE Positioning Protocol message or a Radio Resource Control (RRC) message.

14. The method claim 7 wherein at least one of the thresholds T_X1 or T_X2 is based on whether autonomous muting is enabled.

15. The method of claim 7 where the signal quality metric corresponds to an estimation of power of the PRS transmission from the neighbor cell.

16. The method of claim 7 further comprising

determining a noise measurement based on a signal from which an estimation of power of the PRS transmission from the neighbor cell received at the wireless communication terminal was obtained;

and

where the signal quality metric is based on an estimation of power of the PRS transmission from the neighbor cell and the noise measurement.

17. The method of claim 7, sending the report to the serving cell that includes the PCID of the neighbor cell and the estimated TDOA if the criterion is satisfied.

18. A method in a wireless communication terminal, the method comprising:

receiving a signal comprising at least a Positioning Reference Signal (PRS) transmission from a serving cell and a PRS transmission from a neighbor cell;

estimating a signal quality metric (SQM) based on the PRS transmission from the neighbor cell;

estimating a time difference of arrival (TDOA) measurement for the neighbor cell based on the PRS transmissions received from the neighbor cell;

determining if the estimated SQM satisfies a criterion threshold T_X1<

=SQM<

=threshold T_X2, wherein at least one of the thresholds T_X1 or T_X2 is based on a frame timing offset between the serving cell and the neighbor cell;

sending a report to the serving cell that includes the estimated TDOA if the criterion is satisfied.

19. The method of claim 18, wherein at least one of the thresholds T_X1 or T_X2 is based on a power of the PRS transmission from the serving cell received at the wireless communication terminal and a power of the PRS transmission from the neighbor cell received at the wireless communication terminal.

20. The method of claim 18 further comprising

determining whether serving cell PRS transmission is muted during an occasion in which the PRS transmission from the neighbor cell is received;

estimating the TDOA based on the PRS signal received during the occasion in which the serving cell PRS transmission is muted, wherein at least one of the thresholds T_X1 or T_X2 is based on whether the serving cell PRS transmission was muted.

21. The method of claim 18 where the signal quality metric corresponds to an estimation of power of the PRS transmission from the neighbor cell received at the wireless communication terminal.

22. The method of claim 18 further comprising:

determining a noise measurement based on a signal from which an estimation of power of the PRS transmission from the neighbor cell received at the wireless communication terminal was obtained; and

where the signal quality metric is based on the estimation of power of the PRS transmission from the neighbor cell and the noise measurement.