Grant-based uplink transmission in unlicensed band
Methods and devices for grant-based uplink transmission in an unlicensed band are provided. Uplink grant messages are transmitted to electronic devices (EDs) in order to indicate time-frequency resources that are allocated to the EDs for uplink transmission in an unlicensed spectrum band. For a given ED, in the event that a first listen-before-talk (LBT) operation for the time-frequency resource allocated to the ED fails, the ED performs a second LBT operation within the allocated time-frequency resource at a start time based on a start point configuration within the allocated time-frequency resource. If the second LBT operation succeeds, the ED transmits an uplink transmission within a remaining portion of the allocated time-frequency resource that includes an activation signal to indicate a start of the uplink transmission, and uplink payload data.
1. A method for an Electronic Device (ED) in a wireless network, the method comprising:
receiving an uplink grant message from a base station, the uplink grant message indicating time-frequency resources allocated to the ED for uplink transmission in an unlicensed spectrum band, the allocated time-frequency resources located within a first set of subcarriers in a first channel and a second set of subcarriers in a second channel; and
performing a first listen-before-talk (LBT) operation on the first set of subcarriers in the first channel and a second LBT operation on the second set of subcarriers in the second channel, both the first LBT operation and the second LBT operation being performed at a first start point within a subframe.
2. The method of claim 1 , further comprising:
performing a third LBT operation on the first set of subcarriers in the first channel and a fourth LBT operation on the second set of subcarriers in the second channel at a second start point within the subframe upon determining that both the first LBT operation and the second LBT operation have failed.
3. The method of claim 2 , further comprising:
upon determining that the third LBT operation has succeeded, transmitting an uplink transmission within a remaining portion of the allocated time-frequency resources, the uplink transmission comprising:
an activation signal to indicate a start of the uplink transmission; and uplink payload data.
4. The method of claim 3 , wherein the uplink payload data includes a sequence of code blocks mapped to the first start point and the second start point in accordance with a predefined mapping relationship.
5. The method of claim 4 , wherein the sequence of code blocks starts with a code block mapped to the first start point in the allocated time-frequency resources.
6. The method of claim 4 , wherein the sequence of code blocks starts with a code block mapped to the second start point in the remaining portion of the allocated time-frequency resources.
7. The method of claim 4 , wherein a code block size is determined in accordance with a size of the allocated time-frequency resources.
8. The method of claim 3 , further comprising:
upon determining that the third LBT operation has succeeded, transmitting a reservation signal between the second start point and the closest orthogonal frequency division multiplexing (OFDM) symbol boundary after the second start point.
9. The method of claim 2 , wherein each start point is either at an orthogonal frequency division multiplexing (OFDM) symbol boundary or midway between adjacent OFDM symbol boundaries within the allocated time-frequency resources.
10. The method of claim 2 , wherein the first LBT operation and the third LBT operation are based on energy measured on the first set of subcarriers in the first channel and wherein the second LBT operation and the fourth LBT operation are based on energy measured on the second set of subcarriers in the second channel.
11. An Electronic Device (ED) comprising:
one or more processors; and
a non-transitory computer readable storage medium storing programming for execution by the one or more processors, the programming including instructions to:
receive an uplink grant message from a base station, the uplink grant message indicating time-frequency resources allocated to the ED for uplink transmission in an unlicensed spectrum band, the allocated time-frequency resources located within a first set of subcarriers in a first channel and a second set of subcarriers in a second channel; and
perform a first listen-before-talk (LBT) operation on the first set of subcarriers in the first channel and a second LBT operation on the second set of subcarriers in the second channel, both the first LBT operation and the second LBT operation being performed at a first start point within a subframe.
12. The ED of claim 11 , wherein the programming further includes instructions to:
perform a third LBT operation on the first set of subcarriers in the first channel and a fourth LBT operation on the second set of subcarriers in the second channel at a second start point within the subframe upon determining that both the first LBT operation and the second LBT operation have failed.
13. The ED of claim 12 , wherein the programming further includes instructions to:
upon determining that the third LBT operation has succeeded, transmit an uplink transmission within a remaining portion of the allocated time-frequency resources, the uplink transmission comprising:
an activation signal to indicate a start of the uplink transmission; and
uplink payload data.
14. The ED of claim 13 , wherein the uplink payload data includes a sequence of code blocks mapped to the first start point and the second start point in accordance with a predefined mapping relationship.
15. The ED of claim 14 , wherein the sequence of code blocks starts with a code block mapped to the first start point in the allocated time-frequency resources.
16. The ED of claim 14 , wherein the sequence of code blocks starts with a code block mapped to the second start point in the remaining portion of the allocated time-frequency resources.
17. The ED of claim 14 , wherein a code block size is determined in accordance with a size of the allocated time-frequency resources.
18. The ED of claim 13 , further comprising:
upon determining that the third LBT operation has succeeded, transmitting a reservation signal between the second start point and the closest orthogonal frequency division multiplexing (OFDM) symbol boundary after the second start point.
19. The ED of claim 12 , wherein each start point is either at an orthogonal frequency division multiplexing (OFDM) symbol boundary or midway between adjacent OFDM symbol boundaries within the allocated time-frequency resources.
20. The ED of claim 12 , wherein the first LBT operation and the third LBT operation are based on energy measured on the first set of subcarriers in the first channel and wherein the second LBT operation and the fourth LBT operation are based on energy measured on the second set of subcarriers in the second channel.