Method for reporting channel failure
Methods and apparatuses are described herein for reporting channel failure, and may be used, among others, for New Radio (NR) operation in unlicensed spectrum (NR-U). Upon detecting a consistent uplink (UL) listen-before-talk (LBT) failure or upon detecting a beam failure on a cell, a Scheduling Request (SR) may be triggered to have a UL resource granted for transmission of the failure to another cell, or to a subset of other cells, using, for example, a failure recovery Medium Access Control-Control Element (MAC-CE). If no grant of an available UL resource can be obtained for transmission of the MAC-CE, or the grant is not suitable for the failure reporting, a failure recovery SR may be transmitted repeatedly to obtain an UL grant suitable for transmitting the failure report. In some cases, a WTRU may initiate a random-access procedure for transmitting the MAC-CE, for example when resources for failure reporting are not configured.
1. A wireless transmit/receive unit (WTRU) comprising a processor, the processor configured to:
detect consistent listen before talk (LBT) failure for a first cell;
determine that uplink (UL) resources that can be used for transmitting an indication of the consistent LBT failure are available in a second cell; and
transmit a medium access control element (MAC-CE) that indicates that consistent LBT failure has occurred for the first cell, wherein the MAC-CE is transmitted using the UL resources in the second cell, and wherein the MAC-CE comprises a bitmap, the bitmap comprising a plurality of bits, wherein each bit of the plurality bits corresponds to a cell index of a respective cell, wherein a bit of the bitmap corresponding to the cell index of the first cell indicates the consistent LBT failure associated with the first cell.
2. The WTRU of claim 1 , wherein the processor is further configured to:
receive a radio resource control (RRC) message, wherein the RRC message comprises scheduling request (SR) configuration information associated with consistent LBT failure reporting, and wherein the SR configuration information indicates resources to be used by the WTRU for sending an SR associated with consistent LBT failure reporting.
3. The WTRU of claim 2 , wherein the processor being configured to determine the UL resources that can be used for transmitting the indication of the consistent LBT failure are available in the second cell comprises the processor being configured to:
transmit an SR using the resources indicated by the SR configuration information associated with consistent LBT failure reporting; and
receive an UL grant after transmitting the SR on the resources indicated by the SR configuration information associated with consistent LBT failure reporting, the UL grant indicating the UL resources in the second cell.
4. The WTRU of claim 3 , wherein the processor is further configured to:
cancel further SR transmissions using the resources indicated by the SR configuration information associated with consistent LBT failure reporting based on transmitting MAC-CE that indicates that consistent LBT failure has occurred for the first cell.
5. The WTRU of claim 3 , wherein the processor is further configured to:
cancel further SR transmissions using the resources indicated by the SR configuration information associated with consistent LBT failure reporting based on receiving reconfiguration information associated with consistent LBT failure recovery for the first cell.
6. The WTRU of claim 1 , wherein the processor being configured to detect consistent LBT failure comprises the processor being configured to: determine that a number of LBT attempts failures for the first cell during a period of time is greater than a threshold.
7. The WTRU of claim 1 , wherein the bitmap comprised in the MAC-CE is used to indicate cell indices of a plurality of cells for which the WTRU has detected consistent LBT failure.
8. The WTRU of claim 1 , wherein the MAC-CE comprises an indication of a logical channel index, the indication of the logical channel index being an indication that the MAC-CE is for reporting consistent LBT failure.
9. A method implemented by a wireless transmit/receive unit (WTRU) comprising, the method comprising:
detecting consistent listen before talk (LBT) failure for a first cell;
determining that uplink (UL) resources that can be used for transmitting an indication of the consistent LBT failure are available in a second cell; and
transmitting a medium access control element (MAC-CE) that indicates that consistent LBT failure has occurred for the first cell, wherein the MAC-CE is transmitted using the UL resources associated with the second cell, and wherein the MAC-CE comprises a bitmap, the bitmap comprising a plurality of bits, wherein each bit of the plurality bits corresponds to a cell index of a respective cell, wherein a bit of the bitmap corresponding to the cell index of the first cell indicates the consistent LBT failure associated with the first cell.
10. The method of claim 9 , further comprising:
receiving a radio resource control (RRC) message, the RRC message comprising scheduling request (SR) configuration information associated with consistent LBT failure reporting, the SR configuration information indicating resources to be used by the WTRU for sending an SR associated with consistent LBT failure reporting, wherein the WTRU determining the UL resources that can be used for transmitting an indication of the consistent LBT failure are available in the second cell comprises:
transmitting an SR using the resources indicated by the SR configuration information associated with consistent LBT failure reporting; and
receiving an UL grant after transmitting the SR on the resources indicated by the SR configuration information associated with consistent LBT failure reporting, the UL grant indicating the UL resources that can be used for transmitting an indication of the consistent LBT failure are available in the second cell.
11. The method of claim 10 , further comprising cancelling further SR transmissions using the resources indicated by the SR configuration information associated with consistent LBT failure reporting based on:
transmitting MAC-CE that indicates that consistent LBT failure has occurred for the first cell; or
receiving reconfiguration information associated with consistent LBT failure recovery for the first cell.
12. The method of claim 9 , wherein the bitmap comprised in the MAC-CE is used to indicate cell indices of a plurality of cells for which the WTRU has detected consistent LBT failure.
13. The method of claim 9 , wherein the MAC-CE comprises an indication of a logical channel index, the indication of the logical channel index being an indication that the MAC-CE is for reporting consistent LBT failure.
14. A wireless transmit/receive unit (WTRU) comprising a processor, the processor configured to:
receive a radio resource control (RRC) message, wherein the RRC message comprises scheduling request (SR) configuration information associated with consistent listen before talk (LBT) failure reporting, and wherein the SR configuration information indicates resources to be used by the WTRU for sending an SR associated with consistent LBT failure reporting;
detect consistent LBT failure for a first cell, wherein consistent LBT failure is detected based on a number of LBT attempts failures for the first cell during a period of time being greater than a threshold;
transmit an SR using the resources indicated by the SR configuration information associated with consistent LBT failure reporting; and
receive an UL grant after transmitting the SR on the resources indicated by the SR configuration information associated with consistent LBT failure reporting, the UL grant indicating the UL resources in a second cell; and
transmit a medium access control element (MAC-CE) that indicates that consistent LBT failure has occurred for the first cell, wherein the MAC-CE is transmitted using the UL resources in the second cell, and wherein the MAC-CE comprises a bitmap, the bitmap comprising a plurality of bits, wherein each bit of the plurality of bits corresponds to a cell index of a respective cell, wherein a bit of the bitmap corresponding to the cell index of the first cell indicates the consistent LBT failure associated with the first cell.