# US 11,445,543 B2 · Method and apparatus for performing listen before talk (LBT) for wireless communication in unlicensed band

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- Number: US 11,445,543 B2
- Document ID: US11445543B2
- Status: Granted
- Kind: B2
- Application number: 17/055,118
- Filed: 2019-05-14
- Published: 2021-09-02
- Granted: 2022-09-13
- Earliest claimed: 2018-05-16
- Assignees: Kt Corporation
- Applicants: Kt Corporation
- Inventors: Kyujin Park
- Web page: https://patentgrep.com/patent/US11445543B2

## CPC

- H04W 74/0808: using carrier sensing, e.g. carrier sense multiple access [CSMA]
- H04W 74/002: {Transmission of channel access control information}
- H04W 74/006: {in the downlink, i.e. towards the terminal}
- H04W 74/0833: Random access procedures, e.g. with 4-step access
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

Provided are a method and apparatus for performing listen before talk (LBT) by a terminal for wireless communication in an unlicensed band. The method may include: determining an LBT scheme for transmitting an uplink signal in an unlicensed band, among a plurality of LBT schemes distinguished by at least one of whether to perform LBT, whether to perform random back off, and a random back-off time; and transmitting an uplink signal in an unlicensed band according to the determined LBT scheme.

## Claims

### Claim 1

A method of a user equipment (UE) for performing Listen Before Talk (LBT) for wireless communications over an unlicensed band, the method comprising:
determining an LBT scheme from a plurality of LBT schemes for transmitting an uplink (UL) signal over the unlicensed band;
performing the LBT according to the determined LBT scheme; and
transmitting the UL signal over the unlicensed band after performing the LBT,
wherein the LBT scheme is determined in association with timing gap information from a plurality of timing gap information between a transmission of a downlink (DL) signal of a base station and a transmission of the UL signal of the UE, and
wherein each of the plurality of timing gap information corresponds to each of the plurality of LBT schemes to perform the LBT.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the UL signal is transmitted over the unlicensed band in a channel occupancy time being shared for the transmission of the DL signal of the base station and the transmission of the UL signal of the UE.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the LBT scheme is determined based on LBT indication information received from the base station.

### Claim 4

A user equipment (UE) performing Listen Before Talk (LBT) for wireless communications over an unlicensed band, the UE comprising:
a controller configured to determine an LBT scheme from a plurality of LBT schemes for transmitting an uplink (UL) signal over the unlicensed band, and perform the LBT according to the determined LBT scheme; and
a transmitter configured to transmit the UL signal over the unlicensed band after performing the LBT,
wherein the LBT scheme is determined in association with timing gap information from a plurality of timing gap information between a transmission of a downlink (DL) signal of a base station and a transmission of the UL signal of the UE, and
wherein each of the plurality of timing gap information corresponds to each of the plurality of LBT schemes to perform the LBT.

### Claim 5 (depends on 4)

The UE according to claim 4, wherein the UL signal is transmitted over the unlicensed band in a channel occupancy time being shared for the transmission of the DL signal of the base station and the transmission of the UL signal of the UE.

### Claim 6 (depends on 4)

The UE according to claim 4, wherein the LBT scheme is determined based on LBT indication information received from the base station.