US 12,273,923 B2
Methods, apparatus and systems for system access in unlicensed spectrum
Faris Alfarhan, Montreal (CA); J. Patrick Tooher, Montreal (CA); Ghyslain Pelletier, Montreal (CA); Paul Marinier, Brossard (CA); and Aata El Hamss, Laval (CA)
Assigned to InterDigital Patent Holdings, Inc., Wilmington, DE (US)
Appl. No. 17/252,418
Filed by InterDigital Patent Holdings, Inc., Wilmington, DE (US)
PCT Filed Jun. 10, 2019, PCT No. PCT/US2019/036313
§ 371(c)(1), (2) Date Dec. 15, 2020,
PCT Pub. No. WO2019/245779, PCT Pub. Date Dec. 26, 2019.
Claims priority of provisional application 62/735,446, filed on Sep. 24, 2018.
Claims priority of provisional application 62/715,315, filed on Aug. 7, 2018.
Claims priority of provisional application 62/686,943, filed on Jun. 19, 2018.
Prior Publication US 2021/0274555 A1, Sep. 2, 2021
Int. Cl. H04W 74/0833 (2024.01); H04W 72/23 (2023.01); H04W 74/0808 (2024.01)
CPC H04W 74/0833 (2013.01) [H04W 72/23 (2023.01); H04W 74/0808 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A method implemented by a Wireless Transmit/Receive Unit (WTRU) using an unlicensed frequency channel, the method comprising:
determining that a first preamble is to be transmitted;
determining one or more first physical random access channel (PRACH) resources to transmit the first preamble;
monitoring for a first downlink (DL) signal within a first Channel Occupancy Time (COT), wherein the monitoring for the first DL signal is based on a configured pattern, and wherein reception of the first DL signal is an indication that the WTRU can transmit the first preamble; and
on condition that the first DL signal within the first COT is received:
determining, based on a duration of a time gap after reception of the first DL signal within the first COT, that a listen before talk (LBT) operation is not required, and
transmitting the first preamble in the one or more first PRACH resources;
determining that a second preamble is to be transmitted;
determining one or more second PRACH resources to transmit the second preamble;
monitoring for a second downlink (DL) signal within a second Channel Occupancy Time (COT), wherein the monitoring for the second DL signal is based on the configured pattern, and wherein reception of the second DL signal is an indication that the WTRU can transmit the second preamble; and
on condition that the second DL signal within the second COT is received:
determining, based on a duration of a time gap after reception of the second DL signal within the second COT, to perform a listen before talk (LBT) operation, and
on condition that a channel associated with the one or more second PRACH resources is determined to be idle in accordance with the LBT operation, transmitting the second preamble in the one or more second PRACH resources.