US Patent No. 10,470,209

METHOD, APPARATUS, AND SYSTEM FOR CHANNEL ACCESS IN UNLICENSED BAND


Patent No. 10,470,209
Issue Date November 05, 2019
Title Method, Apparatus, And System For Channel Access In Unlicensed Band
Inventorship Minseok Noh, Seoul (KR)
Jinsam Kwak, Uiwang-si (KR)
Juhyung Son, Uiwang-si (KR)
Assignee WILUS INSTITUTE OF STANDARDS AND TECHNOLOGY INC., Seoul (KR)

Claim of US Patent No. 10,470,209

1. A method for performing downlink transmission in a specific cell by an apparatus in a cellular wireless communication system, the method comprising:receiving hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback for downlink channel transmission(s) of the specific cell, wherein the downlink channel transmission(s) are included in one or more adjacent subframes on the specific cell which are most recently transmitted before the downlink transmission;
determining a contention window based on HARQ-ACK value(s) of HARQ-ACK feedback corresponding to downlink channel transmission(s) in specific subframe(s) among the one or more adjacent subframes, wherein when a ratio of negative acknowledgement (NACK) of the HARQ-ACK value(s) is equal to or more than a reference value, the contention window is increased to a next higher allowed value, and when the ratio of the NACK of the HARQ-ACK value(s) is less than the reference value, the contention window is reset to a minimum value,
generating a random number N (N?0) in the determined contention window; and
performing the downlink transmission in the specific cell after sensing a channel on the specific cell at least for N slots while the channel on the specific cell is idle,
wherein the specific subframe is a first one subframe for which HARQ-ACK feedback is available among the one or more adjacent subframes in response to the first one subframe being a full subframe, and
wherein the specific subframes are first two subframes for which HARQ-ACK feedback is available among the one or more adjacent subframes in response the first one subframe being a partial subframe.