Patent Description:
Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for feedback message control.

Relatedly, document 3GPP R1-<NUM> describes PUCCH transmission on an eLAA carrier, document 3GPP R1-<NUM> describes HARQ-ACK feedback for URLLC, document 3GPP R1-<NUM> describes HARQ-ACK transmission due to bandwidth part (BWP) switching, and document 3GPP R1-<NUM> describes DL/UL scheduling and HARQ management.

In some aspects, a method of wireless communication, performed by a user equipment (UE), is provided according to independent claim <NUM>.

In some aspects, an apparatus for wireless communication is provided according to independent claim <NUM>.

In some aspects, a non-transitory computer-readable medium according to independent claim <NUM> is provided.

Preferred embodiments are described in the dependent claims.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, and/or processing system as substantially described herein with reference to and as illustrated by the accompanying drawings and/or specification.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with feedback message control, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG> and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. In some aspects, memory <NUM> and/or memory <NUM> may comprise a non-transitory computer-readable medium storing one or more instructions for wireless communication. For example, the one or more instructions, when executed by one or more processors of the base station <NUM> and/or the UE <NUM>, may perform or direct operations of, for example, process <NUM> of <FIG> and/or other processes as described herein.

UE <NUM> includes means for determining that a current transmission cycle does not satisfy a feedback message transmission criterion for a feedback message to acknowledge whether a transmission was successfully received, means for performing a feedback response action on the feedback message based at least in part on determining that the current transmission cycle does not satisfy the feedback message transmission criterion, and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>, such as controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, and/or the like.

In some communications systems, such as NR, a UE may transmit feedback messages to a BS to indicate whether a transmission is successfully received. For example, a BS may transmit a physical downlink shared channel (PDSCH) transmission to a UE, and the UE may transmit an acknowledgement (ACK) message via a physical uplink shared channel (PUSCH) to indicate successful receipt of the PDSCH transmission. Similarly, for a PDSCH and other periodic transmissions, when the UE does not receive the PDSCH transmission during a period of time for which the PDSCH transmission is scheduled, the UE may transmit a negative acknowledgement (NACK) message. The BS may retransmit the PDSCH based at least in part on receiving the NACK message. The UE may, for a retransmission of the PDSCH, transmit an ACK message to indicate successful receipt or a NACK message to trigger another retransmission. In this way, use of feedback messages reduces a likelihood that a UE is not able to communicate with a BS, by providing a mechanism for triggering retransmission.

However, in some cases, a time at which a feedback message is scheduled may be within a threshold of an end of a current transmission cycle. For example, when the UE sends a NACK message for a PDSCH and the BS retransmits the PDSCH, the retransmission of the PDSCH may be scheduled relatively close to an end of the current transmission cycle. As a result, an amount of time remaining in the current transmission cycle may not be enough for the UE to receive the retransmission of the PDSCH, process the retransmission of the PDSCH to confirm receipt, and transmit a feedback message (e.g., an ACK or NACK). The UE may be unable to transmit the feedback message in a subsequent transmission cycle, as resources of the subsequent transmission cycle may be reserved for feedback messages triggered by transmissions in the subsequent transmission cycle. In another example, the UE may not have resources scheduled in the current transmission cycle for transmitting a feedback message, even when the feedback message is triggered more than a threshold amount of time before an end of the current transmission cycle.

Some aspects described herein provide for feedback message control. A UE is configured to transmit a feedback message using resources of a subsequent transmission cycle, such as when the feedback message is triggered within a threshold period of time of a current transmission cycle, when the feedback message is triggered without a resource for transmitting the feedback message being scheduled, and/or the like. In this case, the BS may be configured to expect to receive a feedback message in a resource of a subsequent transmission cycle and may schedule resources in the subsequent transmission cycle to enable the UE to transmit the feedback message in the subsequent transmission cycle. In an example not falling within the scope of the claims, the UE may be configured to selectively drop the feedback message rather than attempting to transmit the feedback message in a subsequent transmission cycle. For example, when the UE determines that resources are not available for use in transmitting a feedback message, the UE may drop the feedback message rather than storing the feedback message for a threshold period of time until resources become available. In this way, the UE may enable greater flexibility for feedback messaging for periodic transmissions, thereby improving network utilization.

<FIG> is a diagram illustrating an example <NUM> of feedback message delay, in accordance with various aspects of the present disclosure. As shown in <FIG>, example <NUM> includes a BS <NUM> and a UE <NUM>.

As further shown in <FIG>, and by reference number <NUM>, during a first transmission cycle, BS <NUM> may attempt to transmit a PDSCH to UE <NUM>. For example, BS <NUM> may transmit PDSCH transmissions for a group of UEs <NUM> through N including UE <NUM>. As shown by reference number <NUM>, UE <NUM> may fail to receive a PDSCH transmission from BS <NUM> during a time period for which the PDSCH transmission is scheduled. For example, a beam direction of BS <NUM> may not be configured for a location of UE <NUM>, which may result in UE <NUM> not receiving the PDSCH transmission.

In some aspects, UE <NUM> may determine that a feedback message transmission criterion is satisfied for transmitting a feedback message triggered by not receiving the PDSCH. For example, UE <NUM> may determine that the feedback message is triggered more than a threshold period of time before an end of the first transmission cycle and that an uplink resource is available for transmitting the feedback message in the first transmission cycle. In this case, UE <NUM> may transmit a NACK message using a PUSCH resource for UE <NUM> (e.g., of a group of PUSCH resources for a group of UEs <NUM> through N that includes UE <NUM>), as shown by reference number <NUM>.

In some aspects, UE <NUM> may receive signaling indicating use of the feedback message transmission criterion and/or a feedback response action associated therewith, as described in more detail herein. For example, BS <NUM> may transmit a downlink control information (DCI) message indicating that UE <NUM> is to delay a feedback message when the feedback message is triggered within a threshold amount of time of the end of a transmission cycle. Additionally, or alternatively, UE <NUM> may access a stored configuration indicating that UE <NUM> is to delay the feedback message when the feedback message is triggered within a threshold amount of time of the end of a transmission cycle. Additionally, or alternatively, UE <NUM> may receive a DCI or access a stored configuration indicating that UE <NUM> is to drop a feedback message if the feedback message transmission criterion is satisfied, as described in more detail herein.

As further shown in <FIG>, and by reference number <NUM>, based at least in part on receiving the NACK message, BS <NUM> may retransmit the PDSCH transmission to UE <NUM>. For example, during a portion of the first transmission cycle allocated for PDSCH retransmission, BS <NUM> may attempt to retransmit the PDSCH to UEs that indicated a failure to receive the PDSCH. In this case, UE <NUM> may, again, fail to receive the PDSCH, as shown by reference number <NUM>. For example, UE <NUM> may determine that a PDSCH transmission is not received during a time period for retransmission of the PDSCH, and may determine to transmit another feedback message to BS <NUM> to indicate a failure of the PDSCH retransmission. In this case, UE <NUM> may, again, determine that the feedback message transmission criterion is satisfied, and may transmit a NACK message using a physical uplink control channel (PUCCH) resource, as shown by reference number <NUM>.

As further shown in <FIG>, and by reference number <NUM>, based at least in part on receiving another NACK message, BS <NUM> may, again, attempt to retransmit the PDSCH transmission to UE <NUM>. For example, during the portion of the first cycle allocated for PDSCH retransmission, BS <NUM> may attempt to retransmit the PDSCH to each UE that, again, indicated a failure to receive the PDSCH. In this case, UE <NUM> may successfully receive the PDSCH, as shown by reference number <NUM>. Based at least in part on successfully receiving the PDSCH, UE <NUM> may determine to transmit a feedback message (e.g., an ACK message) to BS <NUM> to indicate successful receipt of the PDSCH.

In this case, UE <NUM> may determine that the feedback message transmission criterion is not satisfied. For example, UE <NUM> may determine that the ACK message is triggered within a threshold amount of time of an end of the first cycle, which may result in the ACK message extending into the second cycle (e.g., as a result of processing and/or transmission delays). Additionally, or alternatively, UE <NUM> may determine that resources for transmitting the ACK message (e.g., PUSCH resources or PUCCH resources) are not allocated in a remainder of the first cycle.

UE <NUM> determines to perform a feedback response action based at least in part on determining that the feedback message transmission criterion is not satisfied for the first transmission cycle. For example, as shown by reference number <NUM>, UE <NUM> may delay the ACK message until an available uplink resource in a second transmission cycle after the first transmission cycle. In this case, UE <NUM> may store an indicator of the ACK message in a data structure to enable UE <NUM> to transmit the ACK message at a later time (e.g., using the available uplink resource of the second transmission cycle). In some aspects, UE <NUM> may use the feedback message for outer-loop link adaptation based at least in part on delaying the feedback message. For example, UE <NUM> may adapt a modulation, coding, and/or other parameter in connection with the feedback message based at least in part on delaying the feedback message. In some aspects, UE <NUM> may delay a feedback message for more than a single transmission cycle. For example, UE <NUM> may delay the ACK message until an available uplink resource, which may occur in a third transmission cycle, a fourth transmission cycle, and/or the like after the first transmission cycle.

In some examples not falling within the scope of the claims, UE <NUM> may perform a different feedback response action. For example, UE <NUM> may determine to drop the feedback message rather than storing and delaying the feedback message. In some aspects, UE <NUM> may determine to drop the feedback message based at least in part on a deadline criterion. For example, UE <NUM> may determine that an available uplink resource is not scheduled for a threshold amount of time, and may determine to drop the feedback message rather than store the feedback message for greater than the threshold amount of time. Additionally, or alternatively, UE <NUM> may determine to use a different frequency resource to transmit the feedback message. For example, UE <NUM> may receive an initial transmission on a first frequency FR1, and may frequency hop to a second frequency FR2 to transmit the feedback message, thereby increasing a likelihood of identifying an available uplink resource relative to remaining on a single frequency band.

UE <NUM> determines to include the feedback message in another transmission that is to be transmitted using a subsequent uplink resource. For example, as shown by reference numbers <NUM>, <NUM>, and <NUM>, UE <NUM> may receive a PDSCH transmission from BS <NUM> in the second transmission cycle and may have a PUSCH resource reserved for transmitting a feedback message for the PDSCH of the second transmission cycle. In this case, UE <NUM> may include the feedback message triggered by the second PDSCH retransmission in the first transmission cycle with the feedback message for the PDSCH of the second transmission cycle in a single PUSCH transmission using a PUSCH resource, as shown. In this way, UE <NUM> enables delayed transmission of a feedback message.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a UE (e.g., UE <NUM> and/or the like) performs operations associated with feedback message control.

As shown in <FIG>, in some aspects, process <NUM> includes determining that a current transmission cycle does not satisfy a feedback message transmission criterion for a feedback message to acknowledge whether a transmission was successfully received (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may determine that a current transmission cycle does not satisfy a feedback message transmission criterion for a feedback message to acknowledge whether a transmission was successfully received, as described above.

As further shown in <FIG>, in some aspects, process <NUM> includes performing a feedback response action on the feedback message based at least in part on determining that the current transmission cycle does not satisfy the feedback message transmission criterion (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may perform a feedback response action on the feedback message based at least in part on determining that the current transmission cycle does not satisfy the feedback message transmission criterion, as described above.

In a first aspect, process <NUM> includes delaying transmission of the feedback message from the current transmission cycle to a subsequent transmission cycle based at least in part on determining that the current transmission cycle does not satisfy the feedback message transmission criterion, and transmitting the feedback message in the subsequent transmission cycle based at least in part on delaying the transmission of the feedback message from the current transmission cycle to the subsequent transmission cycle.

In a second aspect, not falling within the scope of the claims, alone or in combination with the first aspect, process <NUM> includes dropping the feedback message.

In a third aspect, alone or in combination with one or more of the first and second aspects, process <NUM> includes determining that an amount of remaining time in the current transmission cycle does not satisfy a threshold amount of time.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the threshold amount of time is based at least in part on a UE processing capability.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, process <NUM> includes determining that an uplink resource for transmitting the feedback message is not available in the current transmission cycle.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, the feedback message is an acknowledgement message or a negative acknowledgement message.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, process <NUM> includes receiving an indicator from a base station instructing the UE to perform the feedback response action.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, process <NUM> includes determining that an uplink resource is not available for the feedback message within a threshold amount of time.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, process <NUM> includes transmitting the feedback message on a different frequency band than a frequency band for which the feedback message was scheduled, based at least in part on determining that the current transmission cycle does not satisfy the feedback message transmission criterion.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, process <NUM> includes transmitting the feedback message on a channel determined based at least in part on a base station indication or a preconfigured rule.

In an eleventh aspect, alone or in combination with one or more of the first through tenth aspects, process <NUM> includes transmitting the feedback message to enable outer-loop link adaptation, and performing outer-loop link adaptation using a measurement related to the transmitting of the feedback message.

In a twelfth aspect, alone or in combination with one or more of the first through eleventh aspects, process <NUM> includes transmitting an inquiry message to request information identifying a data pattern.

In a thirteenth aspect, alone or in combination with one or more of the first through twelfth aspects, the data pattern includes at least one of a packet arrival period or a packet expiration period.

In a fourteenth aspect, alone or in combination with one or more of the first through thirteenth aspects, process <NUM> includes storing one or more packets for which the feedback message is delayed or dropped.

Claim 1:
A method of wireless communication performed by a user equipment, UE (<NUM>), comprising:
determining (<NUM>) that a current transmission cycle does not satisfy a feedback message transmission criterion for a feedback message (<NUM>) to acknowledge whether a transmission (<NUM>) was successfully received,
wherein the determining (<NUM>) comprises at least one of:
determining that an amount of remaining time in the current transmission cycle does not satisfy a threshold amount of time, or determining that an uplink resource for transmitting the feedback message is not available in the current transmission cycle; and
performing (<NUM>) a feedback response action on the feedback message (<NUM>) based at least in part on determining that the current transmission cycle does not satisfy the feedback message transmission criterion, wherein the performing (<NUM>) comprises:
delaying (<NUM>) transmission of the feedback message (<NUM>) from the current transmission cycle to a subsequent transmission cycle based at least in part on the determining (<NUM>) that the current transmission cycle does not satisfy the feedback message transmission criterion; and
transmitting the feedback message (<NUM>) in the subsequent transmission cycle based at least in part on the delaying (<NUM>) the transmission of the feedback message (<NUM>) from the current transmission cycle to the subsequent transmission cycle, wherein the feedback message (<NUM>) from the current transmission cycle is included with another feedback message of the subsequent transmission cycle in a single transmission.