Method and apparatus for LBT failure detection
A method for LBT failure detection performed by a UE is provided. The method includes: receiving, by a MAC entity of the UE, an LBT failure indication from a lower layer for all UL transmissions; increasing an LBT failure counter when the MAC entity receives the LBT failure indication; determining an LBT failure event occurs when the LBT failure counter is greater than or equal to a threshold; and resetting the LBT failure counter after the MAC entity has not received the LBT failure indication for a time period.
1. A user equipment (UE) comprising:
one or more non-transitory computer-readable media having computer-executable instructions embodied thereon; and
at least one processor coupled to the one or more non-transitory computer-readable media, the computer-executable instructions causing the UE to:
receive, by a Medium Access Control (MAC) entity of the UE, a Listen-Before-Talk (LBT) failure indication from a lower layer in response to an unsuccessful uplink (UL) transmission attempt;
identify the unsuccessful UL transmission attempt associated with the received LBT failure indication based on a timing of resources used by the unsuccessful UL transmission attempt
increase an LBT failure counter by one when the MAC entity receives the LBT failure indication;
determine an LBT failure event has occurred when the LBT failure counter is greater than or equal to a threshold;
indicate an LBT failure problem to an upper layer in response to determining an LBT failure event has occurred; and
reset the LBT failure counter in response to indicating the LBT failure problem to the upper layer.
2. The UE of claim 1 , wherein the computer-executable instructions further cause the UE to:
reset the LBT failure counter after-the MAC entity has not received the LBT failure indication for a time period.
3. The UE of claim 1 , wherein the computer-executable instructions further cause the UE to:
perform a Radio Link Failure (RLF) recovery procedure.
4. The UE of claim 1 , wherein the computer-executable instructions further cause the UE to:
perform a re-establishment procedure by transmitting a Radio Resource Control (RRC) re-establishment request message indicating a re-establishment cause as LBT failure, when the LBT failure event occurs in a Primary Cell (PCell).
5. The UE of claim 1 , further comprising a transceiver communicatively coupled to the at least one processor, wherein the computer-executable instructions further cause the UE to:
transmit, to a master node via the transceiver, a Secondary Cell Group (SCG) failure report indicating the LBT failure problem when the LBT failure event occurs in a Primary Secondary Cell (PSCell).
6. The UE of claim 1 , further comprising a transceiver communicatively coupled to the at least one processor, wherein the computer-executable instructions further cause the UE to:
receive, via the transceiver, a configuration that indicates at least one of a time period and the threshold.
7. The UE of claim 6 , wherein the computer-executable instructions further cause the UE to:
reset the LBT failure counter when at least one of the time period and the threshold is reconfigured.
8. The UE of claim 1 , wherein the computer-executable instructions further cause the UE to:
reset the LBT failure counter when the MAC entity considers LBT for a UL transmission attempt as successful.
9. The UE of claim 1 , wherein the computer-executable instructions further cause the UE to:
reset the LBT failure counter when a reset of the MAC entity is requested.
10. A method for Listen-Before-Talk (LBT) failure detection performed by a User Equipment (UE), the method comprising:
receiving, by a Medium Access Control (MAC) entity of the UE, a Listen-Before-Talk (LBT) failure indication from a lower layer in response to an unsuccessful uplink (UL) transmission attempt;
identifying the unsuccessful UL transmission attempt associated with the received LBT failure indication based on a timing of resources used by the unsuccessful UL transmission attempt;
increasing an LBT failure counter by one when the MAC entity receives the LBT failure indication;
determining an LBT failure event has occurred when the LBT failure counter is greater than or equal to a threshold;
indicating an LBT failure problem to an upper layer in response to determining an LBT failure event has occurred; and
resetting the LBT failure counter in response to indicating the LBT failure problem to an upper layer.
11. The method of claim 10 , further comprising resetting the LBT failure counter after-the MAC entity has not received the LBT failure indication for a time period.
12. The method of claim 10 , further comprising performing a Radio Link Failure (RLF) recovery procedure.
13. The method of claim 10 , further comprising performing a re-establishment procedure by transmitting a Radio Resource Control (RRC) re-establishment request message indicating a re-establishment cause as LBT failure, when the LBT failure event occurs in a Primary Cell (PCell).
14. The method of claim 10 , further comprising transmitting, to a master node, a Secondary Cell Group (SCG) failure report indicating the LBT failure problem when the LBT failure event occurs in a Primary Secondary Cell (PSCell).
15. The method of claim 10 , further comprising receiving a configuration that indicates at least one of a time period and the threshold.
16. The method of claim 15 , further comprising resetting the LBT failure counter when at least one of the time period and the threshold is reconfigured.
17. The method of claim 10 , further comprising resetting the LBT failure counter when the MAC entity considers LBT for a UL transmission attempt as successful.
18. The method of claim 10 , further comprising resetting the LBT failure counter when a reset of the MAC entity is requested.