Method of feedback for beamforming in a wireless communication system and apparatus therefor

Patent metadata

Field	Value
Publication number	US-9800304-B2
Application number	US-201515125946-A
Country	US
Kind code	B2
Filing date	Feb 17, 2015
Priority date	Mar 13, 2014
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A method of transmitting channel state information (CSI) for a hybrid beamforming from a user equipment in a wireless communication system according to one embodiment of the present invention may include measuring a gain of a directional beam formed with reference to a first direction and a gain of an omni-directional beam formed equivalently in all directions respectively and transmitting the CSI including a gain difference between the directional beam and the omni-directional beam to a base station, wherein a direction of a digital beamforming in the hybrid beamforming is determined in accordance with the gain difference between the directional beam and the omni-directional beam and wherein a direction of an analog beamforming in the hybrid beamforming is determined in accordance with the first direction.

First claim

The invention claimed is:

1. A method of transmitting channel state information (CSI) for hybrid beamforming from a user equipment (UE) in a wireless communication system, the method comprising:
measuring a gain of a directional analog beam formed with reference to a first direction and a gain of an omni-directional beam formed equivalently in all directions; and
transmitting the CSI including a gain difference between the directional analog beam and the omni-directional beam to a base station,
wherein a direction of a digital beamforming in the hybrid beamforming is determined in accordance with a UE direction with respect to the base station, and the UE direction is estimated without using a precoding matrix by utilizing the gain difference between the directional analog beam and the omni-directional beam,
wherein the precoding matrix for the digital beamforming is determined from the determined direction of the digital beamforming, and
wherein a direction of an analog beamforming in the hybrid beamforming is determined in accordance with the first direction.

2. The method of claim 1 , wherein the directional analog beam indicates an angle range where a hybrid beam is formable.

3. The method of claim 1 ,
wherein the directional analog beam is formed using prescribed radio frequency (RF) chains selected from a plurality of RF chains performing the analog beamforming, and
wherein the prescribed RF chains are selected based on a plurality of antenna patterns forming directional analog beams equivalent to each other.

4. The method of claim 1 , wherein the CSI further comprises an indicator indicating whether the user equipment is located in a clockwise direction or a counterclockwise direction from the first direction.

5. The method of claim 1 ,
wherein the directional analog beam is rotated by a prescribed unit angle, and
wherein the CSI further comprises information on a direction having a maximum gain of the directional analog beam and a direction having a second highest gain of the directional analog beam according to the rotation of the directional analog beam.

6. A method of receiving channel state information (CSI) for hybrid beamforming by a base station in a wireless communication system, the method comprising:
transmitting a first signal through a directional analog beam formed with reference to a first direction;
transmitting a second signal through an omni-directional beam formed equivalently in all directions; and
receiving the CSI including a gain difference between the directional analog beam and the omni-directional beam from a user equipment (UE),
wherein a direction of digital beamforming in the hybrid beamforming is determined in accordance with a UE direction with respect to the base station, and the UE direction is estimated without using a precoding matrix by utilizing the gain difference between the directional analog beam and the omni-directional beam,
wherein the precoding matrix for the digital beamforming is determined from the determined direction of the digital beamforming, and
wherein a direction of an analog beamforming in the hybrid beamforming is determined in accordance with the first direction.

7. The method of claim 6 , wherein the directional analog beam indicates an angle range where a hybrid beam is formable.

8. The method of claim 6 ,
wherein the directional analog beam is formed using prescribed radio frequency (RF) chains selected from a plurality of RF chains performing the analog beamforming, and
wherein the prescribed RF chains are selected based on a plurality of antenna patterns forming directional analog beams equivalent to each other.

9. The method of claim 6 , wherein the CSI further comprises an indicator indicating whether the user equipment is located in a clockwise direction or a counterclockwise direction from the first direction.

10. The method of claim 6 ,
wherein the directional analog beam is rotated by a prescribed unit angle, and
wherein the CSI further comprises information on a direction having a maximum gain of the directional analog beam and a direction having a second highest gain of the directional analog beam according to the rotation of the directional analog beam.

11. The method of claim 6 , further comprising:
determining a direction where the user equipment is located from the base station is based on the CSI.

12. A user equipment (UE) of transmitting channel state information (CSI) for hybrid beamforming in a wireless communication system, the user equipment comprising:
a processor for measuring a gain of a directional analog beam formed with reference to a first direction and a gain of an omni-directional beam formed equivalently in all directions; and
a transmitter for transmitting the CSI including a gain difference between the directional analog beam and the omni-directional beam to a base station,
wherein a direction of digital beamforming in the hybrid beamforming is determined in accordance with a UE direction with respect to the base station, and the UE direction is estimated without using a precoding matrix by utilizing the gain difference between the directional analog beam and the omni-directional beam,
wherein the precoding matrix for the digital beamforming is determined from the determined direction of the digital beamforming, and
wherein a direction of an analog beamforming in the hybrid beamforming is determined in accordance with the first direction.

13. A base station of receiving channel state information (CSI) for hybrid beamforming in a wireless communication system, the base station comprising:
a transmitter for transmitting a first signal through a directional analog beam formed with reference to a first direction, and for transmitting a second signal through an omni-directional beam formed equivalently in all directions;
a receiver for receiving the CSI including a gain difference between the directional analog beam and the omni-directional beam from a user equipment (UE); and
a processor for determining a direction of digital beamforming in the hybrid beamforming in accordance with a UE direction with respect to the base station, for estimating the UE direction without using a precoding matrix by utilizing the gain difference between the directional analog beam and the omni-directional beam, for determining the precoding matrix for the digital beamforming from the determined direction of the digital beamforming, and for determining a direction of an analog beamforming in the hybrid beamforming in accordance with the first direction.

Assignees

• Lg Electronics Inc

Inventors

• Kim Kitae
• Kang Jiwon
• Lee Kilbom

Classifications

• H04B7/046

  taking physical layer constraints into account · CPC title

• H04B7/0689

  using different transmission schemes, at least one of them being a diversity transmission scheme · CPC title

• H04B7/0626 Primary

  Channel coefficients, e.g. channel state information [CSI] · CPC title

• H04B7/0417 Primary

  Feedback systems · CPC title

• H04B7/0871

  using different reception schemes, at least one of them being a diversity reception scheme · CPC title