Hearability improvements for reference signals

• US 8,982,851 B2
• Filed: 01/04/2010
• Issued: 03/17/2015
• Est. Priority Date: 01/06/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Agrawal, Avneesh, Sampath, Ashwin, Palanki, Ravi, Bhushan, Naga, Bachu, Raja Sekhar, Khandekar, Aamod D.
• Primary Examiner(s): HOANG, THAI D
• Application Number:
  US12/651,838
• Publication Number:
  US 20100172311A1
• Time in Patent Office: 1,898 Days
• Field of Search: 375260-262, 370329-330, 370335-338, 370342-348
• US Class Current: 370/335
• CPC Class Codes: H04L 1/1893 Physical mapping arrangements physical resource mapping in general H04L5/00
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0082 at predetermined intervals
• CPC Class Codes: H04W 72/30 Resource management for broadcast services
• CPC Class Codes: H04W 72/566 of the information or information source or recipient

Abstract

Systems and methodologies are described that facilitate providing high reuse for transmitting reference signals, such as positioning reference signals (PRS) and cell-specific reference signals (CRS), to improve hearability thereof for applications such as trilateration and/or the like. In particular, PRSs can be transmitted in designated or selected positioning subframes. Resource elements within the positioning subframe can be selected for transmitting the PRSs and can avoid conflict with designated control regions, resource elements used for transmitting cell-specific reference signals, and/or the like. Resource elements for transmitting PRSs can be selected according to a planned or pseudo-random reuse scheme. In addition, a transmit diversity scheme can be applied to the PRSs to minimize impact of introducing the PRSs to legacy devices. Moreover, portions of a subframe not designated for PRS transmission can be utilized for user plane data transmission.

Claims

1. A method, comprising:

determining a positioning subframe configured for transmitting positioning reference signals (PRS);

selecting one or more resource elements in the positioning subframe for transmitting a PRS avoiding resource elements in the positioning subframe configured for transmitting cell-specific reference signals (CRS); and

transmitting a PRS in the one or more resource elements.

2. The method of claim 1, wherein the selecting one or more resource elements includes selecting the one or more resource elements in a portion of the positioning subframe.

3. The method of claim 2, wherein the selecting one or more resource elements in the portion of the positioning subframe includes selecting the one or more resource elements in a slot of the positioning subframe.

4. The method of claim 3, wherein the slot of the positioning subframe is adjacent to a disparate slot of the positioning subframe that includes a set of resource elements reserved for transmitting control data.

5. The method of claim 3, wherein the selecting one or more resource elements includes selecting the one or more resource elements in consecutive orthogonal frequency division multiplexing (OFDM) symbols in the slot of the positioning subframe.

6. The method of claim 5, wherein the selecting one or more resource elements in consecutive OFDM symbols includes shifting between subcarriers of the consecutive OFDM symbols.

7. The method of claim 6, wherein the shifting between subcarriers of the consecutive OFDM symbols includes shifting between subcarriers of the consecutive OFDM symbols according to a diagonal pattern.

8. The method of claim 3, wherein the selecting one or more resource elements includes selecting the one or more resource elements to have a similar periodicity and a similar structure as CRSs.

9. The method of claim 1, wherein the selecting one or more resource elements includes selecting the one or more resource elements according to a planned selection function or a pseudo-random selection function.

10. The method of claim 1, wherein the selecting one or more resource elements in the positioning subframe for transmitting the PRS further includes avoiding a portion of the positioning subframe allocated for control data transmissions.

11. The method of claim 1, further comprising applying a transmit diversity scheme to the PRS.

12. The method of claim 11, wherein the transmitting the PRS is performed over a single antenna port utilized to transmit remaining PRSs in the positioning subframe.

13. The method of claim 1, wherein the selecting one or more resource elements in the positioning subframe includes selecting the one or more resource elements from a subband, comprising a plurality of consecutive resource blocks, related to transmitting the PRS according to a network specification or a configuration.

14. The method of claim 1, further comprising indicating that the positioning subframe is a multicast/broadcast single frequency network subframe.

15. The method of claim 1, wherein the transmitting the PRS in the one or more resource elements includes transmitting the PRS according to a Zadoff-Chu sequence, a Walsh sequence, or a quadrature phase-shift keying sequence to ease detection of the PRS.

16. A wireless communications apparatus, comprising:

at least one processor configured to;

select a portion of a positioning subframe for transmitting positioning reference signals (PRS);

determine one or more resource elements in the positioning subframe, excluding a plurality of disparate resource elements allocated for transmitting cell-specific reference signals (CRS), for transmitting a PRS; and

transmit the PRS in the one or more resource elements; and

a memory coupled to the at least one processor.

17. The wireless communications apparatus of claim 16, wherein the portion of the positioning subframe is a slot of the positioning subframe.

18. The wireless communications apparatus of claim 17, wherein the slot of the positioning subframe is adjacent to a disparate slot of the positioning subframe that includes a set of resource elements reserved for transmitting control data.

19. The wireless communications apparatus of claim 17, wherein the one or more resource elements are in consecutive orthogonal frequency division multiplexing (OFDM) symbols in the slot of the positioning subframe.

20. The wireless communications apparatus of claim 19, wherein the one or more resource elements include shifted subcarriers of the consecutive OFDM symbols.

21. The wireless communications apparatus of claim 20, wherein the shifted subcarriers correspond to a diagonal pattern.

22. The wireless communications apparatus of claim 16, wherein the at least one processor determines the one or more resource elements according to a planned selection function or a pseudo-random selection function.

23. The wireless communications apparatus of claim 16, wherein the at least one processor is further configured to apply a transmit diversity scheme to the PRS.

24. An apparatus, comprising:

means for determining a positioning subframe configured for transmitting positioning reference signals (PRS);

means for selecting one or more resource elements in the positioning subframe, excluding a set of resource elements allocated for transmitting cell-specific reference signals (CRS), for transmitting a PRS; and

means for transmitting the PRS in the one or more resource elements.

25. The apparatus of claim 24, wherein the means for determining the positioning subframe determines at least a portion of a slot of the positioning subframe configured for transmitting PRSs.

26. The apparatus of claim 25, wherein the at least the portion of the slot is adjacent to a disparate slot of the positioning subframe that includes a disparate portion allocated for transmitting control data.

27. The apparatus of claim 25, wherein the means for selecting one or more resource elements in the positioning subframe selects the one or more resource elements from consecutive orthogonal frequency division multiplexing (OFDM) symbols in the slot of the positioning subframe.

28. The apparatus of claim 27, wherein the means for selecting one or more resource elements in the positioning subframe selects the one or more resource elements as shifted subcarriers in each of the consecutive OFDM symbols.

29. The apparatus of claim 28, wherein the one or more resource elements form a diagonal pattern.

30. The apparatus of claim 24, further comprising means for applying a transmit diversity scheme to the PRS.

31. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to select a portion of a positioning subframe for transmitting positioning reference signals (PRS);

code for causing the at least one computer to determine one or more resource elements in the positioning subframe, excluding a plurality of disparate resource elements allocated for transmitting cell-specific reference signals (CRS), for transmitting a PRS; and

code for causing the at least one computer to transmit the PRS in the one or more resource elements.

32. The computer program product of claim 31, wherein the portion of the positioning subframe is a slot of the positioning subframe.

33. The computer program product of claim 32, wherein the slot of the positioning subframe is adjacent to a disparate slot of the positioning subframe that includes a set of resource elements reserved for transmitting control data.

34. The computer program product of claim 32, wherein the one or more resource elements are comprise within consecutive orthogonal frequency division multiplexing (OFDM) symbols in the slot of the positioning subframe.

35. The computer program product of claim 34, wherein the one or more resource elements are comprised within subcarriers shifted among the consecutive OFDM symbols according to a pattern.

36. The computer program product of claim 35, wherein the pattern is a diagonal pattern.

37. An apparatus, comprising:

a special slot selecting component that determines a positioning subframe configured for transmitting positioning reference signals (PRS);

a PRS resource element selecting component that selects one or more resource elements in the positioning subframe, excluding a set of resource elements allocated for transmitting cell-specific reference signals (CRS), for transmitting a PRS; and

a PRS transmitting component that transmits the PRS in the one or more resource elements.

38. The apparatus of claim 37, wherein the special slot selecting component determines at least a portion of a slot of the positioning subframe configured for transmitting PRSs.

39. The apparatus of claim 38, wherein the at least the portion of the slot is adjacent to a disparate slot of the positioning subframe that includes a disparate portion allocated for transmitting control data.

40. The apparatus of claim 39, wherein the PRS resource element selecting component selects the one or more resource elements from consecutive orthogonal frequency division multiplexing (OFDM) symbols in the slot of the positioning subframe.

41. The apparatus of claim 40, wherein the PRS resource element selecting component selects the one or more resource elements as shifted subcarriers in each of the consecutive OFDM symbols.

42. The apparatus of claim 41, wherein the one or more resource elements form a diagonal pattern.