Techniques for communicating on an uplink in a shared radio frequency spectrum band

An apparatus for wireless communication at a network access device, comprising:

• a processor;
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• detect a first reference signal received from a user equipment (UE) in a reference scheduled transmission burst including a plurality of contiguous transmission time intervals (TTIs) received over a shared radio frequency spectrum band;
• identify a reference TTI in which the first reference signal is received;
• determine a contention window size usable by the UE to contend for access to the shared radio frequency spectrum band, the determined contention window size based at least in part on:
• a triggering of aperiodic channel state information (CSI) without a physical uplink shared channel (PUSCH) on the reference TTI, a decoding of a physical uplink control channel (PUCCH) with cyclic redundancy check (CRC) scheduled in the reference TTI, a decoding of a random access preamble scheduled on a physical random access channel (PRACH) in the reference TTI, a decoding of a first scheduled uplink transmission associated with a random access procedure and received in the reference TTI, or a combination thereof;
• and
• transmit an indication of the determined contention window size to the UE.

A method for wireless communication at a user equipment (UE), comprising:

• receiving at least one uplink grant of a plurality of uplink grants for a reference scheduled transmission burst including a plurality of contiguous transmission time intervals (TTIs) transmitted over a shared radio frequency spectrum band, wherein at least a first uplink grant in the plurality of uplink grants includes:
• a first indication that the first uplink grant is associated with a first scheduled TTI of the reference scheduled transmission burst, a second indication of a position of the first scheduled TTI within the reference scheduled transmission burst, or a combination thereof;
• transmitting during at least one TTI of the reference scheduled transmission burst, in accordance with the at least one uplink grant, the transmitting beginning during a first transmission TTI;
• receiving an indication of a reference TTI, the reference TTI being used for transmission by the UE during the reference scheduled transmission burst;
• and
• determining a contention window size usable by the UE to contend for access to the shared radio frequency spectrum band, the determining based at least in part on a relationship between the first scheduled TTI, the reference TTI, and the first transmission TTI.

An apparatus for wireless communication at a user equipment (UE), comprising:

• a processor;
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• receive at least one uplink grant of a plurality of uplink grants for a reference scheduled transmission burst including a plurality of contiguous transmission time intervals (TTIs) transmitted over a shared radio frequency spectrum band, wherein at least a first uplink grant in the plurality of uplink grants includes:
• a first indication that the first uplink grant is associated with a first scheduled TTI of the reference scheduled transmission burst, a second indication of a position of the first scheduled TTI within the reference scheduled transmission burst, or a combination thereof;
• transmit during at least one TTI of the reference scheduled transmission burst, in accordance with the at least one uplink grant, the transmitting beginning during a first transmission TTI;
• receive an indication of a reference TTI, the reference TTI being used for transmission by the UE during the reference scheduled transmission burst;
• and
• determine a contention window size usable by the UE to contend for access to the shared radio frequency spectrum band, the determining based at least in part on a relationship between the first scheduled TTI, the reference TTI, and the first transmission TTI.

A method for wireless communication at a user equipment (UE), comprising:

• transmitting a reference scheduled transmission burst including a plurality of contiguous transmission time intervals (TTIs) over a shared radio frequency spectrum band;
• identifying a hybrid automatic repeat request (HARQ) process corresponding to a reference TTI, wherein the reference TTI is a first TTI of the plurality of contiguous TTIs for which a HARQ acknowledgement is received;
• identifying an instance of the HARQ process associated with a TTI subsequent to the reference TTI, wherein the instance of the HARQ process is identified based at least in part on:
• whether the TTI is included within the reference scheduled transmission burst or a subsequent transmission burst, whether the TTI includes aperiodic channel state information (CSI) without a physical uplink shared channel (PUSCH), or a combination thereof;
• and
• determining a contention window size used to contend for access to the shared radio frequency spectrum band, the determining based at least in part on a state of a new data indicator (NDI) associated with the identified instance of the HARQ process.

An apparatus for wireless communication at a user equipment (UE), comprising:

• a processor;
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• transmit a reference scheduled transmission burst including a plurality of contiguous transmission time intervals (TTIs) over a shared radio frequency spectrum band;
• identify a hybrid automatic repeat request (HARQ) process corresponding to a reference TTI, wherein the reference TTI is a first TTI of the plurality of contiguous TTIs for which a HARQ acknowledgement is received;
• identify an instance of the HARQ process associated with a TTI subsequent to the reference TTI, wherein the instance of the HARQ process is identified based at least in part on:
• whether the TTI is included within the reference scheduled transmission burst or a subsequent transmission burst, whether the TTI includes aperiodic channel state information (CSI) without a physical uplink shared channel (PUSCH), or a combination thereof;
• and
• determine a contention window size used to contend for access to the shared radio frequency spectrum band, the determining based at least in part on a state of a new data indicator (NDI) associated with the identified instance of the HARQ process.

An apparatus for wireless communication at a user equipment (UE), comprising:

• a processor;
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• transmit a first type of buffer status report (B SR) including an indication of an amount of data to be transmitted for each of a plurality of listen before talk (LBT) priority classes;
• and
• receive from a network access device, in response to transmitting the first type of BSR, an indication of a LBT priority class to be used by the UE when contending for access to a shared radio frequency spectrum band.

A method for wireless communication at a user equipment (UE), comprising:

• receiving a first uplink grant for transmitting over a shared radio frequency spectrum band, the first uplink grant associated with a first listen before talk (LBT) priority class;
• performing a first LBT procedure based at least in part on the first LBT priority class to contend for access to the shared radio frequency spectrum band, the first LBT procedure concluding at a LBT state;
• determining, based at least in part on the LBT state, to not transmit over the shared radio frequency spectrum band in accordance with the first uplink grant;
• receiving a second uplink grant for transmitting over the shared radio frequency spectrum band, the second uplink grant associated with a second LBT priority class;
• and
• performing a second LBT procedure based at least in part on the second LBT priority class, the first LBT priority class, and the LBT state to contend for access to the shared radio frequency spectrum band.

An apparatus for wireless communication at a user equipment (UE), comprising:

• a processor;
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• receive a first uplink grant for transmitting over a shared radio frequency spectrum band, the first uplink grant associated with a first listen before talk (LBT) priority class;
• perform a first LBT procedure based at least in part on the first LBT priority class to contend for access to the shared radio frequency spectrum band, the first LBT procedure concluding at a LBT state;
• determine, based at least in part on the LBT state, to not transmit over the shared radio frequency spectrum band in accordance with the first uplink grant;
• receive a second uplink grant for transmitting over the shared radio frequency spectrum band, the second uplink grant associated with a second LBT priority class;
• and
• perform a second LBT procedure based at least in part on the second LBT priority class, the first LBT priority class, and the LBT state to contend for access to the shared radio frequency spectrum band.

A method for wireless communication at a network access device, comprising:

• identifying feedback received from a user equipment (UE) for a downlink reference transmission time interval (TTI) of a transmission opportunity (TxOP) over a shared radio frequency spectrum band, the TxOP comprising at least one downlink TTI and at least one uplink TTI;
• identifying an uplink TTI, of the TxOP, for which scheduling information is transmitted in the downlink reference TTI;
• and
• determining a contention window size usable by the network access device to contend for access to the shared radio frequency spectrum band, for a next TxOP, based at least in part on the identified feedback and a scheduled uplink transmission in the identified uplink TTI.

An apparatus for wireless communication at a network access device, comprising:

• a processor;
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• identify feedback received from a user equipment (UE) for a downlink reference transmission time interval (TTI) of a transmission opportunity (TxOP) over a shared radio frequency spectrum band, the TxOP comprising at least one downlink TTI and at least one uplink TTI;
• identify an uplink TTI, of the TxOP, for which scheduling information is transmitted in the downlink reference TTI;
• and
• determine a contention window size usable by the network access device to contend for access to the shared radio frequency spectrum band, for a next TxOP, based at least in part on the identified feedback and a scheduled uplink transmission in the identified uplink TTI.

A method for wireless communication at a user equipment (UE), comprising:

• receiving scheduling information for an uplink transmission to be made over a plurality of carriers of a shared radio frequency spectrum band;
• identifying a carrier of the plurality of carriers for which to perform a first type of listen before talk (LBT) procedure;
• performing the first type of LBT procedure for the identified carrier;
• performing a second type of LBT procedure for each carrier of the plurality of carriers other than the identified carrier, the second type of LBT procedure having a shorter contention window than the first type of LBT procedure;
• and
• transmitting the uplink transmission over the plurality of carriers based at least in part on the performance of the first type of LBT procedure for the identified carrier and the performance of the second type of LBT procedure for each carrier other than the identified carrier.

An apparatus for wireless communication at a user equipment (UE), comprising:

• a processor;
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• receive scheduling information for an uplink transmission to be made over a plurality of carriers of a shared radio frequency spectrum band;
• identify a carrier of the plurality of carriers for which to perform a first type of listen before talk (LBT) procedure;
• perform the first type of LBT procedure for the identified carrier;
• perform a second type of LBT procedure for each carrier of the plurality of carriers other than the identified carrier, the second type of LBT procedure having a shorter contention window than the first type of LBT procedure;
• and
• transmit the uplink transmission over the plurality of carriers based at least in part on the performance of the first type of LBT procedure for the identified carrier and the performance of the second type of LBT procedure for each carrier other than the identified carrier.

An apparatus for wireless communication at a network access device, comprising:

• a processor;
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• schedule an uplink transmission to be made by a user equipment (UE) over a plurality of carriers of a shared radio frequency spectrum band;
• and
• transmit, to the UE, an indication of a single carrier of the plurality of carriers for which to perform a first type of listen before talk (LBT) procedure.

A method for wireless communication at a user equipment (UE), comprising:

• identifying a type of listen before talk (LBT) procedure to be performed for contending for access to a shared radio frequency spectrum band, the identified type of LBT procedure including a first type of LBT procedure or a second type of LBT procedure;
• identifying an energy detection threshold associated with the identified type of LBT procedure, the identified energy detection threshold including a first energy detection threshold for the first type of LBT procedure or a second energy detection threshold for the second type of LBT procedure, wherein the first energy detection threshold is lower than the second energy detection threshold;
• and
• performing the identified type of LBT procedure based at least in part on the identified energy detection threshold to contend for access to the shared radio frequency spectrum band.

An apparatus for wireless communication at a user equipment (UE), comprising:

• a processor;
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• identify a type of listen before talk (LBT) procedure to be performed for contending for access to a shared radio frequency spectrum band, the identified type of LBT procedure including a first type of LBT procedure or a second type of LBT procedure;
• identify an energy detection threshold associated with the identified type of LBT procedure, the identified energy detection threshold including a first energy detection threshold for the first type of LBT procedure or a second energy detection threshold for the second type of LBT procedure, wherein the first energy detection threshold is lower than the second energy detection threshold;
• and
• perform the identified type of LBT procedure based at least in part on the identified energy detection threshold to contend for access to the shared radio frequency spectrum band.