Threshold determination in TDOA-based positioning system

• US 9,049,680 B2
• Filed: 06/10/2013
• Issued: 06/02/2015
• Est. Priority Date: 02/24/2010
• Status: Expired due to Fees

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Inventors: Krishnamurthy, Sandeep H., Frank, Colin D.
• Primary Examiner(s): MATTIS, JASON E
• Application Number:
  US13/913,684
• Publication Number:
  US 20130273905A1
• Time in Patent Office: 722 Days
• US Class Current: 1/1
• 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 Positioning Reference Signal (PRS) from a serving cell and a PRS from a neighbor cell;

estimating a signal quality metric (SQM) based on the PRS of the neighbor cell and a noise measurement based on the PRS of the serving cell;

estimating a time difference of arrival (TDOA) measurement for the neighbor cell based on the PRS of the neighbor cell and the PRS of the serving cell;

determining at least one of a first threshold T_X1 and a second threshold T_X2 based on determining whether a PRS pattern of the service cell overlaps a PRS pattern of the neighbor cell based on a physical channel identifier (PCID) of the serving cell and a PCID of the neighbor cell;

determining if the estimated SQM satisfies a criterion;

threshold T_X1<

=SQM<

=threshold T_X2; and

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

2. The method of claim 1 wherein determining at least one of the first and second thresholds comprises 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 of 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 of the neighbor cell received at the wireless communication terminal was obtained;

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

5. The method of claim 1 further comprising:

determining whether the PRS of the serving cell is muted during an occasion where the PRS of the neighbor cell is received; and

estimating the TDOA based on the PRS received during the occasion where the PRS of 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 was muted.