US Patent No. 10,470,212

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


Patent No. 10,470,212
Issue Date November 05, 2019
Title Method, Apparatus, And System For Channel Access In Unlicensed Band
Inventorship Minseok Noh, Seoul (KR)
Jinsam Kwak, Gyeonggi-do (KR)
Juhyung Son, Gyeonggi-do (KR)
Assignee WILUS INSTITUTE OF STANDARDS AND TECHNOLOGY INC., Gyeonggi-Do (KR)

Claim of US Patent No. 10,470,212

1. A method for performing downlink transmission in a specific cell by a base station in a cellular wireless communication system, the method comprising:receiving a plurality of hybrid automatic repeat request acknowledgment (HARQ-ACK) responses for downlink transmission(s) in a reference subframe of the specific cell;
setting contention window sizes of a plurality of priority classes for a transmission in the specific cell;
selecting a random number N within a contention window size of a particular priority class among the plurality of priority classes; and
performing, after sensing a channel on which a downlink transmission of the particular priority class is to be performed being idle for at least N slot periods, the downlink transmission of the particular priority class on the channel,
wherein the setting contention window sizes comprises:
increasing contention window size of every priority class of the plurality of priority classes to a next higher allowed value in response to a ratio of negative acknowledgement (NACK) among the plurality of HARQ-ACK responses being equal to or more than a reference value, wherein the increased contention window size of every priority class is maintained, and
setting the contention window size of every priority class of the plurality of priority classes to a minimum value in response to the ratio of the NACK among the plurality of HARQ-ACK responses being less than the reference value.