Channel access in unlicensed spectrum
Channel access in unlicensed spectrum may be a function of the type of physical channel and/or a procedure that initiated a transmission. An LBT procedure may be performed as a function of beam management. A WTRU may access a channel using multiple channel access methods associated with multiple uplink transmissions based on a determination of persistent interference associated with the channel. Channel access methods may be performed with different parameters or characteristics based on the resource type/timing of the transmission/measurements of DL/UL RS. Channel access methods may be characterized by a sensing duration, an ED threshold, a beam width, and/or a beam direction. Different ED thresholds may be applied as a function of one or more characteristics of an applicable beam. Multiple sensing methods and/or related parameters may be applied as a function of the type of physical channel and/or the type of procedure associated with a transmission.
1. A wireless transmit/receive unit (WTRU) comprising:
a processor configured to:
receive configuration information that indicates a first channel access method and a second channel access method, wherein the first access method is associated with using a first beam width, and wherein the second access method is associated with using a second beam width;
select the first channel access method for a first uplink transmission on a channel;
access the channel via the first channel access method and transmit the first uplink transmission on the channel;
determine that a condition associated with the channel is satisfied, wherein the condition is determined to be satisfied based on one or more of: a determination of a number of retransmissions of an uplink transport block exceeding a first threshold, or a determination of a failure to receive feedback associated with a number of transmissions that exceed a second threshold;
based on the determination the condition associated with the channel is satisfied, select the second channel access method for a second uplink transmission; and
access the channel via the second channel access method and transmit the second uplink transmission on the channel.
2. The WTRU of claim 1 , wherein the first channel access method comprises the channel being sensed for a first duration using a first beam.
3. The WTRU of claim 2 , wherein the second channel access method comprises at least the channel being sensed for a second duration using a second beam.
4. The WTRU of claim 3 , wherein the second beam is an omni-directional beam.
5. The WTRU of claim 4 , wherein the first beam is a first directional beam.
6. The WTRU of claim 3 , wherein the second channel access method further comprises the channel being sensed for a third duration using a third beam.
7. The WTRU of claim 6 , wherein the third beam is a second directional beam.
8. The WTRU of claim 5 , wherein the processor is further configured to determine one or more parameters of a directional beam based on one or more parameters of a beam of an associated transmission.
9. The WTRU of claim 6 , wherein the one or more parameters of the beam of the associated transmission comprise at least a beam direction.
10. A method comprising:
receiving configuration information that indicates a first channel access method and a second channel access method, wherein the first access method is associated with using a first beam width, and wherein the second access method is associated with using a second beam width;
selecting the first channel access method for a first uplink transmission on a channel;
accessing the channel via the first channel access method and transmit the first uplink transmission on the channel;
determining that a condition associated with the channel is satisfied, wherein the condition is determined to be satisfied based on one or more of: a determination of a number of retransmissions of an uplink transport block exceeding a first threshold, or a determination of a failure to receive feedback associated with a number of transmissions that exceed a second threshold;
based on the determination the condition associated with the channel is satisfied, selecting the second channel access method for a second uplink transmission; and
accessing the channel via the second channel access method and transmit the second uplink transmission on the channel.
11. The method of claim 10 , wherein the first channel access method comprises the channel being sensed for a first duration using a first beam.
12. The method of claim 11 , wherein the second channel access method comprises the channel being sensed for a second duration using a second beam and the channel being sensed for a third duration using a third beam.
13. The method of claim 12 , wherein the second beam is an omni-directional beam, and wherein the first beam is a first directional beam and the third beam is a second directional beam.
14. The method of claim 13 , further comprising determining one or more parameters of a directional beam based on one or more parameters of a beam of an associated transmission.
15. The method of claim 14 , wherein the one or more parameters of the beam of the associated transmission comprise at least a beam direction.