Reference signal for time and/or frequency tracking in a wireless network

• US 9,107,213 B2
• Filed: 11/06/2012
• Issued: 08/11/2015
• Est. Priority Date: 11/09/2011
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ng, Boon Loong, Nam, Young-Han, Lee, Juho, Zhang, Jianzhong
• Primary Examiner(s): Mered, Habte
• Assistant Examiner(s): Islam, Rownak
• Application Number:
  US13/670,044
• Publication Number:
  US 20130114535A1
• Time in Patent Office: 1,008 Days
• Field of Search: 370/329, 370/330, 370/310, 370/328, 370/503, 370/350, 455/450, 455/464
• US Class Current: 1/1
• CPC Class Codes: H04L 5/0005 Time-frequency
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

A method and an apparatus in a base station are capable of including a tracking reference signal (TRS) in a downlink subframe. The method includes generating a TRS subframe by including the TRS in the downlink subframe at a frequency density of at least one resource element per six resource elements in the TRS subframe. Additionally, the method includes transmitting the TRS subframe at a periodicity among other subframes not including the TRS.

Claims

1. A method for including a tracking reference signal (TRS) in a downlink subframe, the method comprising:

determining whether at least one of a time density or a frequency density of a channel-state-information reference signal (CSI-RS), included in the downlink subframe for at least one of time or frequency tracking by an user equipment, exceeds a threshold;

generating, in response to determining that the at least one of the time density or the frequency density of the CSI-RS does not exceed the threshold, a TRS subframe by including the TRS in the downlink subframe at a frequency density of at least one resource element per six resource elements in the TRS subframe, the frequency density of the TRS in the downlink subframe configured for timing or frequency tracking by a user equipment, wherein generating the TRS subframe comprises configuring the TRS in the downlink subframe independently of the CSI-RS included in the downlink subframe; and

transmitting the TRS subframe at a periodicity among other subframes not including the TRS.

2. The method of claim 1, wherein generating the TRS subframe comprises generating the TRS subframe by including the TRS in the downlink subframe on a port for a cell-specific reference signal (CRS).

3. The method of claim 2 further comprising:

determining whether the CRS is absent in one or more downlink subframes,

wherein generating the TRS subframe comprises generating the TRS subframe to include the TRS in response to determining that the CRS is absent in the one or more downlink subframes.

4. The method of claim 1, wherein a pattern of the TRS in the TRS subframe is that of a CSI-RS port with increased frequency density and regular spacing between resource elements of the TRS in the TRS subframe.

5. The method of claim 1, wherein a pattern of the TRS in the TRS subframe is a collection of multiple CSI-RS port patterns.

6. The method of claim 1, wherein a density of the TRS in the TRS subframe is expressly indicated in a one-bit field in configuration information.

7. The method of claim 1, wherein a density of the TRS in the TRS subframe is implicitly indicated by a type of carrier used to transmit the TRS subframe.

8. The method of claim 1, wherein the periodicity of the TRS subframe among the other subframes is at least one of one TRS subframe every five milliseconds or one TRS subframe in every five subframes.

9. An apparatus in a base station configured to include a tracking reference signal (TRS) in a downlink subframe, the apparatus comprising:

a controller configured to determine whether at least one of a time density or a frequency density of a channel-state-information reference signal (CSI-RS), included in the downlink subframe for at least one of time or frequency tracking by an user equipment, exceeds a threshold;

transmitter processing circuitry configured to generate, in response to a determination that the at least one of the time density or the frequency density of the CSI-RS does not exceed the threshold, a TRS subframe by including the TRS at a frequency density of at least one resource element per six resource elements in the TRS subframe, the frequency density of the TRS in the downlink subframe configured for timing or frequency synchronization by a user equipment, and to configure the TRS in the downlink subframe independently of the CSI-RS included in the downlink subframe; and

one or more antennas configured to transmit the TRS subframe at a periodicity among other subframes not including the TRS.

10. The apparatus of claim 9, wherein the transmitter processing circuitry is configured to generate TRS subframe by including the TRS in the downlink subframe on a port for a cell-specific reference signal (CRS).

11. The apparatus of claim 10 further comprising:

a controller configured to determine whether the CRS is absent in one or more downlink subframes,

wherein the transmitter processing circuitry is configured to generate the TRS subframe to include the TRS in response to a determination that the CRS is absent in the one or more downlink subframes.

12. The apparatus of claim 9, wherein a pattern of the TRS in the TRS subframe is that of a CSI-RS port with increased frequency density and regular spacing between resource elements of the TRS in the TRS subframe.

13. The apparatus of claim 9, wherein a pattern of the TRS in the TRS subframe is a collection of multiple CSI-RS port patterns.

14. The apparatus of claim 9, wherein a density of the TRS in the TRS subframe is expressly indicated in a one-bit field in configuration information.

15. The apparatus of claim 9, wherein a density of the TRS in the TRS subframe is implicitly indicated by a type of carrier used by the base station to transmit the TRS subframe.

16. The apparatus of claim 9, wherein the periodicity of the TRS subframe among the other subframes is at least one of one TRS subframe every five milliseconds or one TRS subframe in every five subframes.

17. An apparatus in a user equipment configured to identify a tracking reference signal (TRS) in a downlink subframe, the apparatus comprising:

one or more antennas configured to receive a TRS subframe at a periodicity among other subframes not including the TRS;

receiver processing circuitry configured to identify the TRS in the TRS subframe; and

a controller configured to perform at least one of frequency or timing tracking using the TRS,

wherein a frequency density of the TRS in the TRS subframe is at least one resource element per six resource elements,

wherein at least one of a time density or a frequency density of a channel-state-information reference signal (CSI-RS) is determined not to exceed a threshold,

wherein the TRS is configured in the downlink subframe independently of the CSI-RS included in the downlink subframe, and

wherein the TRS subframe is generated to include the TRS in response to the at least one of the time density or the frequency density of the CSI-RS included in the downlink subframe not exceeding the threshold.

18. The apparatus of claim 17, wherein the TRS is included on a port for a cell-specific reference signal (CRS) in the downlink subframe.

19. The apparatus of claim 17, wherein the periodicity of the TRS subframe among the other subframes is at least one of one TRS subframe every five milliseconds or one TRS subframe in every five subframes.

20. The apparatus of claim 17, wherein the controller is configured to process the TRS to achieve or maintain timing or frequency synchronization for wireless communication by the UE.