Interference mitigation for positioning reference signals

Patent metadata

Field	Value
Publication number	US-9686715-B2
Application number	US-201615174669-A
Country	US
Kind code	B2
Filing date	Jun 6, 2016
Priority date	Nov 28, 2014
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

Techniques are provided, which may be used for determining a position of a user equipment (mobile device). In certain example implementations, tones in positioning signals from one or more sources that may interfere with certain positioning signals be estimated and some form of interference mitigation may be applied, which may better enable the user equipment to acquire certain other positioning signals that may be useful in determining a position of the user equipment.

First claim

The invention claimed is:

1. A method for use in determining a position of a user equipment, the method comprising:
measuring, by a wireless transceiver in the user equipment, a plurality of positioning signals that are synchronized relative to one another, to obtain first measurements;
storing, in a storage device in the user equipment, the first measurements;
estimating, by a processor in the user equipment, a first plurality of tones of one or more first station(s), based on the first measurements measured in a current cyclical period during which positioning signals are transmitted per a transmission schedule, and based on identification of the one or more first station(s);
mitigating, by the processor in the user equipment, the first plurality of tones of one or more first station(s), from the first measurements measured in the current cyclical period, to obtain second measurements of the current cyclical period; and
storing, in the storage device in the user equipment, the second measurements.

2. The method of claim 1 wherein:
the first measurements comprise measurements of positioning signals from one or more first station(s) that use a common frequency shift.

3. The method of claim 1 further comprising:
computing, by the processor in the user equipment, a position of the user equipment based, at least in part, on the first measurements and the second measurements.

4. The method of claim 1 wherein:
the second measurements improve detection rate of second station(s) overpowered by the one or more first stations detected in the first measurements.

5. The method of claim 1 wherein:
the current cyclical period has a duration of a predetermined number of subframes N PRS which are grouped into a positioning occasion, in a transmission schedule.

6. The method of claim 1 further comprising:
applying, by the processor in the user equipment, a test of interference to additional measurements measured in one or more earlier cyclical periods, to identify the one or more first station(s) prior to the current cyclical period.

7. The method of claim 1 wherein:
the second measurements obtained in a first subframe within the current cyclical period are integrated with the second measurements obtained in a second subframe within the current cyclical period.

8. The method of claim 1 wherein estimation of the first plurality of tones of one or more first station(s) comprises:
searching for a peak in a vector of channel impulse response (CIR) of positioning signals;
aligning the peak to origin, by performing a circular shift using frequency domain channel response of positioning signals, to obtain an origin-centered CIR vector;
eliminating aliasing in the origin-centered CIR vector by frequency interpolation, to obtain an interpolated OR vector;
scaling the interpolated OR vector to overcome energy diminishment caused by zero tones, to obtain a scaled OR vector; and
performing on the scaled OR vector, reverse of the circular shift, to obtain and store in memory the first plurality of tones of the one or more first station(s).

9. A non-transitory computer-readable storage media comprising a plurality of instructions that are executable by a processor in a user equipment to direct the user equipment to:
measure, by a wireless transceiver in the user equipment, a plurality of positioning signals that are synchronized relative to one another, to obtain first measurements;
store, in a storage device in the user equipment, the first measurements;
estimate, by a processor in the user equipment, a first plurality of tones of one or more first station(s), based on the first measurements measured in a current cyclical period during which positioning signals are transmitted per a transmission schedule, and based on identification of the one or more first station(s);
mitigate, by the processor in the user equipment, the first plurality of tones of one or more first station(s), from the first measurements measured in the current cyclical period, to obtain second measurements of the current cyclical period; and
store, in the storage device in the user equipment, the second measurements.

10. The non-transitory computer-readable storage media of claim 9 wherein:
the first measurements comprise measurements of positioning signals from one or more first station(s) that use a common frequency shift.

11. The non-transitory computer-readable storage media of claim 9 wherein the instructions are further executable by the processor to:
compute a position of the user equipment based, at least in part, on the first measurements and the second measurements.

12. The non-transitory computer-readable storage media of claim 9 wherein:
the second measurements improve detection rate of second station(s) overpowered by the one or more first stations detected in the first measurements.

13. The non-transitory computer-readable storage media of claim 9 wherein the current cyclical period has a duration of a predetermined number of subframes N PRS which are grouped into a positioning occasion, in the transmission schedule.

14. The non-transitory computer-readable storage media of claim 9 , wherein the instructions are further executable by the processor to direct the user equipment to:
apply a test of interference to additional measurements measured in one or more earlier cyclical periods, to identify the one or more first station(s) prior to the current cyclical period.

15. The non-transitory computer-readable storage media of claim 9 , wherein:
the second measurements obtained in a first subframe within the current cyclical period are integrated with the second measurements obtained in a second subframe within the current cyclical period.

16. The non-transitory computer-readable storage media of claim 9 , wherein the instructions are further executable by the processor to direct the user equipment to:
search for a peak in a vector of channel impulse response (CIR) of positioning signals;
align the peak to origin by performing a circular shift using frequency domain channel response of positioning signals, to obtain an origin-centered CIR vector;
eliminate aliasing in the origin-centered CIR vector by frequency interpolation, to obtain an interpolated CIR vector;
scale the interpolated CIR vector to overcome energy diminishment caused by zero tones, to obtain a scaled CIR vector; and
perform on the scaled CIR vector, reverse of the circular shift, to obtain and store in memory the first plurality of tones of the one or more first station(s).

17. A device comprising:
a wireless transceiver;
a memory;
a processor operatively coupled to the wireless transceiver and the memory, and wherein the processor and the memory are configured to:
measure, by a wireless transceiver in the device, a plurality of positioning signals that are synchronized relative to one another, to obtain first measurements;
store, in a memory in the device, the first measurements;
estimate, by the processor in the device, a first plurality of tones of one or more first station(s), based on the first measurements measured in a current cyclical period during which positioning signals are transmitted per a transmission schedule, and based on identification of the one or more first station(s);
mitigate, by the processor in the device, the first plurality of tones of one or more first station(s), from the first measurements measured in the current cyclical period, to obtain second measurements of the current cyclical period; and
store, in the memory in the device, the second measurements.

Assignees

• Qualcomm Inc

Inventors

• Mirbagheri Arash
• Zhang Shenqiu

Classifications

• H04W64/006 Primary

  with additional information processing, e.g. for direction or speed determination · CPC title

• H04L27/2647

  Arrangements specific to the receiver only (equalisation H04L27/01) · CPC title

• H04J11/004

  using regenerative subtractive interference cancellation · CPC title

• H04B17/345

  Interference values ({signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]} H04B17/336) · CPC title

• H04B17/336

  Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] · CPC title