Support of downlink positioning using coherent and non-coherent signal acquisition

Patent metadata

Field	Value
Publication number	US-9733337-B2
Application number	US-201615131838-A
Country	US
Kind code	B2
Filing date	Apr 18, 2016
Priority date	Aug 28, 2015
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

Techniques are discussed for conveying frequency error characteristics for a plurality of cell transceivers from a server to a mobile device to enable the mobile device to determine an optimum or near optimum period of coherent integration of a downlink signal from one or more of the plurality of cell transceivers based on the frequency error characteristics. The coherent integration of the downlink signal may be to support a downlink terrestrial positioning method such as the Observed Time Difference of Arrival (OTDOA) method for Long Term Evolution (LTE) and the downlink signal may be a Positioning Reference Signal (PRS). A mobile device may perform downlink signal integration for longer periods than the optimum period for coherent integration by combining coherent integration results using non-coherent integration. The optimum period may achieve maximum or near maximum signal to noise ratio.

First claim

What is claimed is:

1. A method at a mobile device comprising:
obtaining one or more messages from a server comprising positioning assistance data for a downlink terrestrial positioning method, the positioning assistance data identifying a plurality of cell transceivers, the positioning assistance data further comprising one or more frequency error characteristics for at least one of the plurality of cell transceivers; and
determining a usage of coherent integration, based on at least one of the frequency error characteristics to measure a characteristic of a downlink signal for at least one of the plurality of cell transceivers according to the downlink terrestrial positioning method.

2. The method of claim 1 , and further comprising
measuring the characteristic of the downlink signal based, at least in part, on the usage of coherent integration.

3. The method of claim 2 , wherein measuring the characteristic of the downlink signal for the at least one of the plurality of cell transceivers comprises:
obtaining one or more coherent integration results, wherein each coherent integration result is obtained by coherently integrating consecutive samples of the downlink signal for the at least one of the plurality of cell transceivers according to the usage of coherent integration;
measuring one coherent integration result if the number of coherent integration results is one; and
measuring a combination of the one or more coherent integration results if a number of the one or more coherent integration results exceeds one, wherein the combination of the one or more coherent integration results is determined using non-coherent integration.

4. The method of claim 3 , and further comprising:
determining a frequency source for the coherently integrating consecutive samples of the downlink signal for the at least one of the plurality of cell transceivers according to the usage of coherent integration, wherein the frequency source comprises one of the plurality of cell transceivers, and the frequency source is determined based, at least in part, on a frequency error characteristic for the frequency source.

5. The method of claim 4 , further comprising:
obtaining an estimated location of the mobile device based at least in part on the measured characteristic of the downlink signal for the at least one of the plurality of cell transceivers.

6. The method of claim 4 , wherein the downlink terrestrial positioning method comprises an Observed Time Difference Of Arrival (OTDOA) method for Long Term Evolution (LTE), and wherein the downlink signal comprises a Positioning Reference Signal (PRS).

7. The method of claim 6 , wherein the PRS for the least one of the plurality of cell transceivers comprises a plurality of two or more consecutive subframes in each PRS positioning occasion.

8. The method of claim 6 , wherein determining the usage of coherent integration comprises determining a maximum number of consecutive subframes for coherent integration for a PRS positioning occasion.

9. The method of claim 6 , wherein the assistance data further comprises an identifier for a first reference cell transceiver and further comprising:
determining a second reference cell transceiver, wherein the second reference cell transceiver is either the first reference cell transceiver or another cell transceiver within the plurality of cell transceivers, wherein the determination of the second reference cell transceiver is based at least in part on a frequency error characteristic for the second reference cell transceiver if the second reference cell transceiver is different from the first reference cell transceiver, wherein the assistance data comprises the frequency error characteristic for the second reference cell transceiver.

10. The method of claim 9 , wherein the frequency source comprises the second reference cell transceiver.

11. The method of claim 1 , wherein at least one of the one or more frequency error characteristics for the at least one of the plurality of cell transceivers comprises an expected carrier frequency error.

12. The method of claim 1 , wherein at least one of the one or more frequency error characteristics for the at least one of the plurality of cell transceivers comprises a class of carrier frequency error.

13. A mobile device comprising:
a wireless transceiver to transmit messages to and receive messages from a wireless communication network; and
a processor coupled to the wireless transceiver configured to:
obtain one or more messages received at the wireless transceiver from a server comprising positioning assistance data for a downlink terrestrial positioning method, the positioning assistance data identifying a plurality of cell transceivers, the positioning assistance data further comprising one or more frequency error characteristics for at least one of the plurality of cell transceivers; and
determine a usage of coherent integration, based on at least one of the frequency error characteristics to measure a characteristic of a downlink signal for at least one of the plurality of cell transceivers according to the downlink terrestrial positioning method.

14. The mobile device of claim 13 , wherein the processor is further configured to measure the characteristic of the downlink signal based on the determined usage of coherent integration.

15. The mobile device of claim 14 , wherein the processor is further configured to:
obtain one or more coherent integration results, wherein each coherent integration result is obtained by coherently integrating consecutive samples of the downlink signal for the at least one of the plurality of cell transceivers according to the usage of coherent integration;
measure one coherent integration result if the number of coherent integration results is one; and
measure a combination of the one or more coherent integration results if a number of the one or more coherent integration results exceeds one, wherein the combination of the one or more coherent integration results is determined using non-coherent integration.

16. The mobile device of claim 14 , wherein the processor is further configured to:
initiate transmission of one or more messages through the wireless transceiver to the server comprising a measurement based, at least in part, on the measured characteristic of the downlink signal for the at least one of the plurality of cell transceivers, wherein the server is capable of determining a location estimate for the mobile device based at least in part on the measurement.

17. The mobile device of claim 16 , wherein the measurement comprises a reference signal time difference (RSTD) measurement.

18. The mobile device of claim 13 , wherein the downlink terrestrial positioning method comprises an Observed Time Difference Of Arrival (OTDOA) method for Long Term Evolution (LTE), and wherein the downlink signal comprises a Positioning Reference Signal (PRS).

19. The mobile device of claim 18 , wherein the PRS for the least one of the plurality of cell transceivers comprises a plurality of two or more consecutive subframes in each PRS positioning occasion.

20. The mobile device of claim 19 , wherein the processor is further configured to determine the usage of coherent integration based on a determination of a maximum number of consecutive subframes for coherent integration for a PRS positioning occasion.

21. The mobile device of claim 18 , wherein the assistance data further comprises an identifier for a first reference cell transceiver, and wherein t

Assignees

• Qualcomm Inc

Inventors

• Edge Stephen William
• Opshaug Guttorm
• Fischer Sven

Classifications

• H04W64/003

  locating network equipment · CPC title

• G01S5/0236

  Assistance data, e.g. base station almanac · CPC title

• H04L5/0048

  Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091) · CPC title

• G01S5/0289 Primary

  of multiple transceivers, e.g. in ad hoc networks · CPC title

• G01S5/0242

  Determining the position of transmitters to be subsequently used in positioning (G01S5/0289 takes precedence) · CPC title