Transmission adaptation and grant-free access
A wireless transmit receive unit (WTRU) may receive a set of candidate resources, which may be used for transmission. The WTRU may periodically perform CCA on a channel (e.g., before transmitting on the channel). When the channel is determined to be free, the WTRU may determine a resource for transmission from the candidate resources. The resource may be determined based on the time remaining in the time period. For example, when the time remaining in the time period is shorter, the WTRU may determine to transmit on a resource that comprises more frequency resources. The WTRU may determine a Multiple Input Multiple Output (MIMO) scheme based on the number of frequency resources. The WTRU may send a transmission on the resource, which may include a demodulation reference signal (DM-RS). The DM-RS may indicate the resource used from transmission to a receiver of the transmission.
1. A wireless transmit/receive (WTRU) comprising:
a processor configured to:
receive downlink control information (DCI) that indicates a set of frequency resources, wherein the DCI indicates a first start time associated with a first transmission occasion and a second start time associated with a second transmission occasion;
determine that a channel access attempt for the first transmission occasion associated with the first start time has failed;
determine that a channel access attempt for the second transmission occasion associated with the second start time was successful; and
send, based on the channel access attempt for the second transmission occasion associated with the second start time being successful, an uplink transmission during the second transmission occasion associated with the second start time using the set of frequency resources.
2. The WTRU of claim 1 , wherein the first transmission occasion is associated with a first transmission time period and the second transmission occasion is associated with a second transmission time period.
3. The WTRU of claim 1 , wherein the processor is further configured to:
receive second DCI that indicates a second set of frequency resources, wherein the second DCI indicates a third start time associated with a third transmission occasion and a fourth start time associated with a fourth transmission occasion;
determine that a channel access attempt for the third transmission occasion associated with the third start time was successful; and
send, based on the channel access attempt for the third transmission occasion associated with the third start time being successful, a second uplink transmission during the third transmission occasion associated with the third start time using the second set of frequency resources.
4. The WTRU of claim 3 , wherein the processor is further configured to send, based on the channel access attempt for the third transmission occasion associated with the third start time being successful, a third uplink transmission during the fourth transmission occasion associated with the fourth start time using the second set of frequency resources.
5. The WTRU of claim 4 , wherein the third transmission occasion and the fourth transmission occasion are contiguous transmission occasions.
6. The WTRU of claim 1 , wherein a demodulation reference signal (DM-RS) is included in a last orthogonal frequency division multiplexing (OFDM) symbol of the uplink transmission.
7. The WTRU of claim 1 , wherein a demodulation reference signal (DM-RS) is included at a first orthogonal frequency division multiplexing (OFDM) symbol of the uplink transmission.
8. The WTRU of claim 1 , wherein the DCI indicates a third start time associated with a third transmission occasion, and the second and third transmission occasions are continuous in time.
9. The WTRU of claim 8 , wherein the processor is further configured to send, based on the channel access attempt for the second transmission occasion associated with the second start time being successful, a second uplink transmission at the third transmission occasion associated with the third start time using the set of frequency resources.
10. The WTRU of claim 1 , wherein the processor is further configured to determine a number of transport blocks to transmit based on the channel access attempt for the second transmission occasion associated with the second start time being successful.
11. A method implemented by a wireless transmit/receive (WTRU), the method comprising:
receiving downlink control information (DCI) that indicates a set of frequency resources, wherein the DCI indicates a first start time associated with a first transmission occasion and a second start time associated with a second transmission occasion;
determining that a channel access attempt for the first transmission occasion associated with the first start time has failed;
determining that a channel access attempt for the second transmission occasion associated with the second start time was successful; and
sending, based on the channel access attempt for the second transmission occasion associated with the second start time being successful, an uplink transmission during the second transmission occasion associated with the second start time using the set of frequency resources.
12. The method of claim 11 , wherein the first transmission occasion is associated with a first transmission time period and the second transmission occasion is associated with a second transmission time period.
13. The method of claim 11 , further comprising:
receiving second DCI that indicates a second set of frequency resources, wherein the second DCI indicates a third start time associated with a third transmission occasion and a fourth start time associated with a fourth transmission occasion;
determining that a channel access attempt for the third transmission occasion associated with the third start time was successful; and
sending, based on the channel access attempt for the third transmission occasion associated with the third start time being successful, a second uplink transmission during the third transmission occasion associated with the third start time using the second set of frequency resources.
14. The method of claim 13 , further comprising sending, based on the channel access attempt for the third transmission occasion associated with the third start time being successful, a third uplink transmission during the fourth transmission occasion associated with the fourth start time using the second set of frequency resources.
15. The method of claim 14 , wherein the third transmission occasion and the fourth transmission occasion are contiguous transmission occasions.
16. The method of claim 11 , wherein a demodulation reference signal (DM-RS) is included in a last orthogonal frequency division multiplexing (OFDM) symbol of the uplink transmission.
17. The method of claim 11 , wherein a demodulation reference signal (DM-RS) is included at a first orthogonal frequency division multiplexing (OFDM) symbol of the uplink transmission.
18. The method of claim 11 , wherein the DCI indicates a third start time associated with a third transmission occasion, and the second and third transmission occasions are continuous in time.
19. The method of claim 18 , further comprising sending, based on the channel access attempt for the second transmission occasion associated with the second start time being successful, a second uplink transmission during the third transmission occasion associated with the third start time using the set of frequency resources.
20. The method of claim 11 , further comprising determining a number of transport blocks to transmit based on the channel access attempt for the second transmission occasion associated with the second start time being successful.
21. A wireless transmit/receive (WTRU) comprising:
a processor configured to:
receive downlink control information (DCI) that indicates a set of frequency resources, wherein the DCI indicates a first start time associated with a first transmission occasion and a second start time associated with a second transmission occasion;
determine that a channel access attempt for the first transmission occasion associated with the first start time was successful;
send, based on the channel access attempt for the first transmission occasion associated with the first start time being successful, an uplink transmission during the first transmission occasion associated with the first start time using the set of frequency resources; and
send, based on the channel access attempt for the first transmission occasion associated with the first start time being successful, a second uplink transmission during the second transmission occasion associated with the second start time using the set of frequency resources.
22. The WTRU of claim 21 , wherein the first transmission occasion and the second transmission occasion are contiguous transmission occasions.