RANDOMIZATION OF PRS FREQUENCY OFFSETS AND MUTING PATTERNS IN LTE FOR EOTDOA

• US 20160065342A1
• Filed: 09/01/2015
• Published: 03/03/2016
• Est. Priority Date: 09/02/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: MIRBAGHERI, Arash, BANISTER, Brian Clarke
• Granted Patent: US 10,439,775 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/30 Resource management for broadcast services

Abstract

Certain aspects of the present disclosure generally relate to randomization of positioning reference signal (PRS) frequency offsets and muting patterns in long term evolution (LTE) for enhanced observed time difference of arrival (eOTDOA). According to certain aspects, a method is provided for wireless communications which may be performed, for example, by a base station (BS). The method generally includes randomly selecting at least one parameter used to determine a set of time-frequency resources for transmitting positioning reference signals (PRS) and transmitting PRS on the determined set of time-frequency resources. The user equipment (UE) may randomly select the at least one parameter used to determine the set of time-frequency resources to measure for the PRS from the BS and measure PRS on the determined set of time-frequency resources.

Claims

1. A method for wireless communications by a base station (BS), comprising:

randomly selecting at least one parameter used to determine a set of time-frequency resources for transmitting positioning reference signals (PRS);

determining the set of time-frequency resources based at least on the at least one parameter; and

transmitting PRS on the determined set of time-frequency resources.

2. The method of claim 1, wherein the at least one parameter is randomly selected using a value generated by a random number generator initialized with a seed value.

3. The method of claim 2, further comprising providing the seed value to a user equipment (UE) prior to transmitting the PRS.

4. The method of claim 3, wherein the seed value is provided to the UE with assistance data, the assistance data comprising a list of one or more neighboring base stations and observed time difference of arrival (OTDOA) assistance data.

5. The method of claim 2, wherein the seed value is based on at least one of:

a physical cell ID (PCID) of the BS, a system frame number, or a time of day.

6. The method of claim 1, wherein the set of time-frequency resources comprises one or more frequency tones in at least one orthogonal frequency division multiplexing (OFDM) symbol period of one or more PRS subframes.

7. The method of claim 1, wherein:

the at least one parameter comprises a PRS offset; and

frequency tones are determined based on a stride pattern of a fixed number of frequency tones in each OFDM symbol period and the PRS offset.

8. The method of claim 7, wherein the value of the PRS offset is randomly selected from a set of values corresponding to a size of the stride pattern.

9. The method of claim 1, wherein:

the at least one parameter comprises a muting pattern having a sequence of bits with each bit indicating whether PRS is sent in a corresponding PRS occasion.

10. The method of claim 9, wherein a length of the muting pattern is selected such that, over a series of PRS subframes, the BS transmits PRS with a duty cycle of a target value.

11. The method of claim 1, wherein the set of time-frequency resources for transmitting PRS comprises different time-frequency resources per subframe or per PRS occasion.

12. A method for wireless communications by a user equipment (UE), comprising:

randomly selecting at least one parameter used to determine a set of time-frequency resources to measure for positioning reference signals (PRS) from a base station (BS); and

measuring the PRS on the set of time-frequency resources.

13. The method of claim 12, wherein the at least one parameter is randomly selected using a value generated by a random number generator initialized with a seed value.

14. The method of claim 13, further comprising receiving the seed value from the BS prior to receiving the PRS.

15. The method of claim 13, wherein the seed value is received with assistance data, the assistance data comprising a list of one or more neighboring base stations and observed time difference of arrival (OTDOA) assistance data.

16. The method of claim 13, wherein the seed value is based on at least one of:

a physical cell ID (PCID) of the BS, a system frame number, or a time of day.

17. The method of claim 12, wherein the set of time-frequency resources comprises one or more frequency tones in at least one orthogonal frequency division multiplexing (OFDM) symbol period of one or more PRS subframes.

18. The method of claim 12, wherein:

the at least one parameter comprises a PRS offset; and

frequency tones are determined based on a stride pattern of a fixed number of frequency tones in each OFDM symbol period and the PRS offset.

19. The method of claim 18, wherein the value of the PRS offset is randomly selected from a set of values corresponding to a size of the stride pattern.

20. The method of claim 12, wherein:

the at least one parameter comprises a muting pattern having a sequence of bits with each bit indicating whether PRS is sent in a corresponding PRS occasion.

21. The method of claim 12, further comprising:

estimating time of arrival (TOA) differences of the measured PRS from PRS from one or more other BSs.

22. The method of claim 12, wherein the set of time-frequency resources to measure for PRS comprises different time-frequency resources per subframe or per PRS occasion.

23. An apparatus for wireless communications, comprising:

means for randomly selecting at least one parameter used to determine a set of time-frequency resources for transmitting positioning reference signals (PRS);

means for determining the set of time-frequency resources based at least on the at least one parameter; and

means for transmitting PRS on the determined set of time-frequency resources.

24. The apparatus of claim 23, wherein the at least one parameter is randomly selected using a value generated by a random number generator initialized with a seed value.

25. The apparatus of claim 23, wherein:

the at least one parameter comprises a PRS offset; and

frequency tones are determined based on a stride pattern of a fixed number of frequency tones in each OFDM symbol period and the PRS offset.

26. The apparatus of claim 23, wherein:

the at least one parameter comprises a muting pattern having a sequence of bits with each bit indicating whether PRS is sent in a corresponding PRS occasion.

27. An apparatus for wireless communications, comprising:

means for randomly selecting at least one parameter used to determine a set of time-frequency resources to measure for positioning reference signals (PRS) from a base station (BS); and

means for measuring PRS on the set of time-frequency resources.

28. The apparatus of claim 27, wherein the at least one parameter is randomly selected using a value generated by a random number generator initialized with a seed value.

29. The apparatus of claim 27, wherein:

the at least one parameter comprises a PRS offset; and

frequency tones are determined based on a stride pattern of a fixed number of frequency tones in each OFDM symbol period and the PRS offset.

30. The apparatus of claim 27, wherein:

the at least one parameter comprises a muting pattern having a sequence of bits with each bit indicating whether PRS is sent in a corresponding PRS occasion.