Listen before talk procedure in a wireless device and wireless network
A wireless device receives an uplink grant for a licensed assisted access (LAA) cell. The uplink grant comprises a physical uplink shared channel (PUSCH) starting position field and a listen-before-talk (LBT) type field. The PUSCH starting position field indicates a PUSCH starting position in a subframe of the LAA cell. The LBT type field indicates at least one of a first LBT type or a second LBT type for the subframe. A determination is made based, at least, on uplink transmissions by the wireless device in a preceding adjacent subframe of the LAA cell, to: perform an LBT procedure for transmission of uplink signals in the subframe, or transmit the uplink signals without performing the LBT procedure for the subframe, regardless of the LBT type field indicating the first LBT type or the second LBT type. The uplink signals in the subframe may be transmitted via the LAA cell.
1. A method comprising:
receiving by a wireless device, an uplink multi-subframe grant for a licensed assisted access (LAA) cell, the uplink multi-subframe grant comprising:
radio resources of an uplink burst comprising a plurality of consecutive subframes;
a physical uplink shared channel (PUSCH) starting position field indicating a PUSCH starting position in a subframe of the plurality of consecutive subframes; and
a listen-before-talk (LBT) type field indicating at least one of a first LBT type or a second LBT type for the subframe of the plurality of consecutive subframes;
determining, at least based on uplink transmissions by the wireless device in a preceding adjacent subframe to the subframe of the plurality of consecutive subframes and a maximum channel occupancy time (MCOT) not expiring in the subframe of the plurality of consecutive subframes, to:
ignore the LBT type field in the uplink grant by not performing an LBT procedure for the subframe of the plurality of consecutive subframes; and
transmit uplink signals in the subframe of the plurality of consecutive subframes without performing the LBT procedure for the subframe of the plurality of consecutive subframes, regardless of the LBT type field indicating the first LBT type or the second LBT type; and
transmitting, via the LAA cell, the uplink signals in the subframe of the plurality of consecutive subframes.
2. The method of claim 1 , wherein:
the first LBT type is a Category 4 LBT; and
the second LBT type is a Category 2 LBT.
3. The method of claim 1 , wherein the PUSCH starting position field indicates that PUSCH transmissions in the subframe start from a beginning of symbol zero.
4. The method of claim 1 , wherein the wireless device transmits without a transmission gap between the preceding adjacent subframe and the subframe.
5. The method of claim 1 , wherein the determining to transmit the uplink signals in the subframe without performing the LBT procedure for the subframe is further based on the wireless device transmitting without a transmission gap between the preceding adjacent subframe and the subframe.
6. The method of claim 1 , wherein the determining to transmit the uplink signals in the subframe without performing the LBT procedure for the subframe is further based on the PUSCH starting position field indicating that PUSCH transmissions in the subframe start from a beginning of symbol zero.
7. The method of claim 1 , wherein the wireless device transmits in a last symbol of the preceding adjacent subframe.
8. The method of claim 1 , wherein the determining to transmit the uplink signals without performing the LBT procedure for the subframe is further based on the wireless device transmitting in a last symbol of the preceding adjacent subframe.
9. The method of claim 1 , further comprising receiving a second uplink grant for the preceding adjacent subframe.
10. The method of claim 9 , wherein the second uplink grant is one of:
a single-subframe uplink grant; or
a multi-subframe uplink grant.
11. A wireless device comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the wireless device to:
receive an uplink multi-subframe grant for a licensed assisted access (LAA) cell, the uplink multi-subframe grant comprising:
radio resources of an uplink burst comprising a plurality of consecutive subframes;
a physical uplink shared channel (PUSCH) starting position field indicating a PUSCH starting position in a subframe of the plurality of consecutive subframes; and
a listen-before-talk (LBT) type field indicating at least one of a first LBT type or a second LBT type for the subframe of the plurality of consecutive subframes;
determine, at least based on uplink transmissions in a preceding adjacent subframe to the subframe of the plurality of consecutive subframes and a maximum channel occupancy time (MCOT) not expiring in the subframe of the plurality of consecutive subframes, to:
ignore the LBT type field in the uplink grant by not performing an LBT procedure for the subframe of the plurality of consecutive subframes; and
transmit uplink signals in the subframe of the plurality of consecutive subframes without performing the LBT procedure for the subframe of the plurality of consecutive subframes, regardless of the LBT type field indicating the first LBT type or the second LBT type; and
transmit, via the LAA cell, the uplink signals in the subframe of the plurality of consecutive subframes.
12. The wireless device of claim 11 , wherein the wireless device transmits without a transmission gap between the preceding adjacent subframe and the subframe.
13. The wireless device of claim 11 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to determine to transmit the uplink signals in the subframe without performing the LBT procedure for the subframe based on the wireless device transmitting without a transmission gap between the preceding adjacent subframe and the subframe.
14. The wireless device of claim 11 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to determine to transmit the uplink signals in the subframe without performing the LBT procedure for the subframe based on the PUSCH starting position field indicating that PUSCH transmissions in the subframe start from a beginning of symbol zero.
15. The wireless device of claim 11 , wherein the wireless device transmits in a last symbol of the preceding adjacent subframe.
16. The wireless device of claim 11 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to determine to transmit the uplink signals without performing the LBT procedure for the subframe based on the wireless device transmitting in a last symbol of the preceding adjacent subframe.
17. The wireless device of claim 11 , further comprising receiving at least one message comprising configuration parameters of the LAA cell.
18. The wireless device of claim 11 , wherein the instructions, when executed by the one or more processors, further cause the wireless device to receive a second uplink grant for the preceding adjacent subframe.
19. The wireless device of claim 11 , wherein the uplink grant further comprises a PUSCH ending symbol field indicating whether the PUSCH is transmitted in a last symbol of the subframe.
20. The wireless device of claim 18 , wherein the second uplink grant is one of:
a single-subframe uplink grant; or
multi-subframe uplink grant.