# US 10,771,213 B2 · Method for transmitting feedback information for DM-RS based downlink transmission in wireless communication system and apparatus therefor

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,771,213 B2
- Document ID: US10771213B2
- Status: Granted
- Kind: B2
- Application number: 16/090,150
- Filed: 2017-03-31
- Published: 2019-10-10
- Granted: 2020-09-08
- Earliest claimed: 2016-03-31
- Assignees: LG Electronics Inc.
- Applicants: LG Electronics Inc.
- Inventors: Hyungtae Kim; Kijun Kim; Jonghyun Park; Haewook Park
- Web page: https://patentgrep.com/patent/US10771213B2

## CPC

- H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)}
- H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B 7/0486: {taking channel rank into account}
- H04B 7/06: at the transmitting station
- H04B 7/0626: {Channel coefficients, e.g. channel state information [CSI]}
- H04B 7/0632: {Channel quality parameters, e.g. channel quality indicator [CQI]}
- H04W 72/12: Wireless traffic scheduling
- H04W 76/27: Transitions between radio resource control [RRC] states
- H04L 5/14: Two-way operation using the same type of signal, i.e. duplex
- H04W 72/542: using measured or perceived quality
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04B: TRANSMISSION
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

Disclosed is a method by which a terminal reports channel status information (CSI) to a base station in a wireless communication system, so as to perform a demodulation reference signal (DM-RS)-based downlink transmission through a multi-layer. Particularly, the method comprises the steps of: receiving a channel status information-reference signal (CSI-RS) from the base station; calculating the CSI on the basis of the CSI-RS, on the assumption that a dual pre-coder composed of a first pre-coder and a second pre-coder is applied; and reporting the calculated CSI to the base station, wherein column vectors of the second pre-coder are composed of a single discrete Fourier transform (DFT) vector.

## Claims

### Claim 1

A method of reporting Channel Status Information (C SI) for a Demodulation-Reference Signal (DM-RS) based downlink transmission through dual layers to a base station by a user equipment in a wireless access system, the method comprising:
receiving a Channel Status Information-Reference Signal (CSI-RS) from the base station;
calculating the CSI based on the CSI-RS on an assumption that a dual precoder including a first precoder and a second precoder is applied; and
reporting the CSI to the base station, the CSI including at least one of a rank indicator, channel quality information or information on the first precoder,
wherein the second precoder is configured from one of precoders defined by two column vectors, and
wherein the two column vectors are identical.

### Claim 2 (depends on 1)

The method of claim 1, wherein the dual layers correspond to different antenna ports of the DM-RS.

### Claim 3 (depends on 1)

The method of claim 1, wherein the second precoder applies a same beam to each of the dual layers.

### Claim 4 (depends on 1)

The method of claim 1, wherein the received CSI-RS is defined as 4 or 8 antenna ports.

### Claim 5

A method of receiving Channel Status Information (CSI) for a Demodulation-Reference Signal (DM-RS) based downlink transmission through dual layers by a base station from a user equipment in a wireless access system, the method comprising:
transmitting a Channel Status Information-Reference Signal (CSI-RS) to the user equipment; and
receiving the CSI including at least one of a rank indicator, channel quality information or information on a first precoder of a dual precoder,
wherein the CSI is calculated by the user equipment based on the CSI-RS on an assumption that the dual precoder including the first precoder and a second precoder is applied,
wherein the second precoder is configured from one of precoders defined by two column vectors, and
wherein the two column vectors are identical.

### Claim 6 (depends on 5)

The method of claim 5, wherein the dual layers correspond to different antenna ports of the DM-RS.

### Claim 7 (depends on 5)

The method of claim 5, wherein the second precoder applies a same beam to each of the dual layers.

### Claim 8 (depends on 5)

The method of claim 5, wherein the received CSI-RS is defined as 4 or 8 antenna ports.