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 at least one processor is configured to execute the computer-executable instructions to:
receive, by a Medium Access Control (MAC) entity of the UE, a Listen-Before-Talk (LBT) failure indication from a lower layer of the UE for all uplink (UL) transmissions;
increase an LBT failure counter when the MAC entity receives the LBT failure indication;
determine that an LBT failure event has occurred when the LBT failure counter is greater than or equal to a threshold;
indicate, by the MAC entity of the UE, to an upper layer of the UE an LBT failure problem after determining that the LBT failure event has occurred; and
transmit, to a secondary node, a Master Cell Group (MCG) failure report including information of the LBT failure problem when the LBT failure event occurs in a Primary Cell (PCell) or MCG.
2. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
perform a Radio Link Failure (RLF) recovery procedure.
3. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions 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).
4. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
transmit the Master Cell Group (MCG) failure report to the secondary node operating on a licensed spectrum.
5. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
transmit the Master Cell Group (MCG) failure report to the secondary node operating on an unlicensed spectrum.
6. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
reset the LBT failure counter when the threshold is reconfigured.
7. The UE of claim 1 , wherein the at least one processor is further configured to execute the computer-executable instructions to:
reset the LBT failure counter when the UE switches from an active Bandwidth Part (BWP) of the UE to another BWP.
8. A method comprising:
receiving, by a Medium Access Control (MAC) entity of the user equipment (UE), a Listen-Before-Talk (LBT) failure indication from a lower layer of the UE for all uplink (UL) transmissions;
increasing an LBT failure counter when the MAC entity receives the LBT failure indication;
determining that an LBT failure event has occurred when the LBT failure counter is greater than or equal to a threshold;
indicating, by the MAC entity of the UE, to an upper layer of the UE an LBT failure problem after determining that the LBT failure event has occurred; and
transmitting, to a secondary node, a Master Cell Group (MCG) failure report including information of the LBT failure problem when the LBT failure event occurs in a Primary Cell (PCell) or MCG.
9. The method of claim 8 , further comprising performing a Radio Link Failure (RLF) recovery procedure.
10. The method of claim 8 , 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).
11. The method of claim 8 , further comprising transmitting the Master Cell Group (MCG) failure report to the secondary node operating on a licensed spectrum.
12. The method of claim 8 , further comprising transmitting the Master Cell Group (MCG) failure report to the secondary node operating on an unlicensed spectrum.
13. The method of claim 8 , further comprising resetting the LBT failure counter when the threshold is reconfigured.
14. The method of claim 8 , further comprising resetting the LBT failure counter when the UE switches from an active Bandwidth Part (BWP) of the UE to another BWP.