Patent Description:
A wireless communication network may include a number of base stations (BSs) that can support communication for a number of user equipment (DEs).

NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL), using CP-OFDM and/or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (LTL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. Relatedly, document 3GPP R1-<NUM> describes code block group (CBG) based (re)transmission, and document 3GPP R1-<NUM> describes uplink control information (UCI) multiplexing.

More specifically, the invention is directed to a method of wireless communication performed by a base station, as defined in claim <NUM>, to a method of wireless communication performed by a user equipment, as defined in claim <NUM>, to a corresponding computer program, as defined in claim <NUM>, to a base station, as defined in claim <NUM>, and to a user equipment, as defined in claim <NUM>.

Some UEs may be considered Internet-of Things (IoT) devices, and/or may be implemented as may be implemented as NB-IoT (narrowband internet of things) devices.

Each radio frame may include <NUM> subframes with a length of <NUM>. Consequently, each subframe may have a length of <NUM>. Each subframe may indicate a link direction (e.g., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include DL/UL data as well as DL/UL control data.

<FIG> shows a block diagram of a design of base station <NUM> and UE <NUM>, which may be one of the base stations and one of the UEs in <FIG>.

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 using a downlink assignment index (DAI) in New Radio, 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>, process <NUM> of <FIG>, process <NUM> of <FIG>, process <NUM> of <FIG>, process <NUM> of <FIG>, process <NUM> of <FIG>, process <NUM> of <FIG>, 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, the UE <NUM> may include means for monitoring a slot for a total DAI in DCI other than a downlink grant, wherein the total DAI indicates a number of downlink grants transmitted to the UE <NUM> in a bundling window; means for determining whether the total DAI has been received by the UE <NUM>; means for selectively transmitting ACK/NACK feedback for the bundling window based at least in part on whether the total DAI has been received; and/or the like. Additionally, or alternatively, the UE <NUM> may include means for monitoring a final slot of a bundling window for a total DAI, wherein the total DAI indicates a number of downlink grants transmitted to the UE <NUM> in the bundling window; means for determining whether the total DAI has been received by the UE <NUM> in the final slot of the bundling window; means for selectively transmitting ACK/NACK feedback for the bundling window based at least in part on whether the total DAI has been received in the final slot of the bundling window; and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>.

Additionally, or alternatively, the UE <NUM> may include means for receiving a common downlink control communication, associated with multiple UEs, that includes multiple total DAIs that indicate a number of downlink grants transmitted to each of the multiple UEs in a bundling window; means for identifying, from the common downlink control communication, a total DAI, of the multiple total DAIs, that corresponds to the UE <NUM>; means for transmitting ACK/NACK feedback for the bundling window based at least in part on the total DAI; and/or the like. Additionally, or alternatively, the UE <NUM> may include means for receiving an uplink grant that includes multiple total DAIs corresponding to multiple DAI groups associated with the UE <NUM>, wherein each of the multiple DAI groups is associated with a different set of component carriers used by the UE <NUM> for carrier aggregation; means for transmitting ACK/NACK feedback for the multiple DAI groups based at least in part on the multiple total DAIs included in the uplink grant; and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>.

In some aspects, the base station <NUM> may include means for determining a total DAI for a bundling window, wherein the total DAI indicates a number of downlink grants transmitted to a UE in the bundling window; means for transmitting the total DAI to the UE in DCI other than a downlink grant; and/or the like. Additionally, or alternatively, the base station <NUM> may include means for determining whether a downlink assignment is to be scheduled for a UE in a final slot of a bundling window; means for determining a total DAI for the bundling window based at least in part on whether the downlink assignment is to be scheduled, wherein the total DAI indicates a number of downlink grants transmitted to the UE in the bundling window; means for transmitting the total DAI in the final slot of the bundling window regardless of whether the downlink assignment is to be scheduled in the final slot of the bundling window; and/or the like. In some aspects, such means may include one or more components of base station <NUM> described in connection with <FIG>.

Additionally, or alternatively, the base station <NUM> may include means for determining multiple total DAIs for a bundling window based at least in part on a number of downlink grants transmitted to each of multiple UEs in the bundling window; means for transmitting the multiple total DAIs in a common downlink control communication associated with the multiple UEs; and/or the like. Additionally, or alternatively, the base station <NUM> may include means for determining multiple total DAIs corresponding to multiple DAI groups associated with a UE, wherein each of the multiple DAI groups is associated with a different set of component carriers used by the UE for carrier aggregation; means for transmitting the multiple total DAIs to the UE in an uplink grant; and/or the like. In some aspects, such means may include one or more components of base station <NUM> described in connection with <FIG>.

<FIG> is a diagram illustrating an example <NUM> of using downlink assignment indexes for HARQ ACK/NACK feedback, in accordance with various aspects of the present disclosure.

In LTE, a downlink assignment index (DAI) was introduced to solve the many-to-one mapping problem of HARQ ACK/NACK feedback. DAI is designed to alleviate the ambiguity between the base station <NUM> and the UE <NUM> regarding the total size and index of scheduled transport blocks (TBs) to be acknowledged or negatively acknowledged in a single PUCCH transmission (e.g., in multiplexed or bundled HARQ ACK/NACK feedback). Two DCI fields were introduced: a DAI counter (sometimes referred to as cumulative DAI) and a total DAI value, each with two bits. As illustrated in <FIG>, the DAI counter accumulates in a frequency first (e.g., across slots) and time second (e.g., across component carriers (CCs)) fashion, taking a value of <NUM>, <NUM>, <NUM>, or <NUM>, corresponding to the two bits of the DAI counter. When the UE <NUM> misses a value in an observed DAI sequence, then the UE <NUM> determines that a downlink grant was missed and reports a NACK in the HARQ ACK/NACK feedback transmitted via the physical uplink control channel (PUCCH). With a <NUM>-bit modulo-<NUM> DAI counter, this DAI mechanism is robust to any consecutive three missing grants, and with a <NUM>-bit total DAI field, the issue of PUCCH payload size ambiguity caused by missing the last few grants may be alleviated.

However, this DAI mechanism may result in ambiguities between the base station <NUM> and the UE <NUM> regarding a size of the HARQ ACK/NACK feedback when the UE <NUM> misses the last downlink grant in a bundling window that includes multiple downlink grants for which HARQ ACK/NACK feedback is reported together, as described in more detail below in connection with <FIG>. In this case, the UE <NUM> may transmit a different number of HARQ ACK/NACK bits than are expected by the base station <NUM>, resulting in an error. Furthermore, NR presents other challenges in the design of a robust HARQ ACK/NACK feedback mechanism, one of them being that the number of code block groups (CBGs) per TB for different downlink assignments could be different, leading to potentially different ACK/NACK payload sizes across slots and/or CCs. In this case, multiple DAI counters may be used for different DAI groups, adding further complexity to the HARQ ACK/NACK process and an increased likelihood of ambiguities between the base station <NUM> and the UE <NUM> regarding a size of HARQ ACK/NACK feedback for different DAI groups. Some techniques and apparatuses described herein reduce or eliminate ambiguities between the base station <NUM> and the UE <NUM> regarding HARQ ACK/NACK feedback when the UE <NUM> misses the last downlink grant in a bundling window, when the UE <NUM> is associated with multiple DAI groups, and/or the like.

<FIG> is a diagram illustrating another example <NUM> of using downlink assignment indexes for HARQ ACK/NACK feedback, in accordance with various aspects of the present disclosure.

In NR, a TB may be divided into one or more code block groups (CBGs), where each CBG is separately acknowledged or negatively acknowledged to prevent retransmission of large TBs. In some aspects, the number of CBGs per TB may be configured dynamically or semi-statically, such as using a radio resource control (RRC) configuration. The number of HARQ ACK/NACK bits transmitted for a TB may equal the number of CBGs for that TB. Using the DAI mechanism described above in connection with <FIG>, even if the UE <NUM> can detect missing grants, the UE <NUM> may not be capable of inferring the expected HARQ ACK/NACK payload size (e.g., the number of bits) for the missing grants. To solve this issue, multiple DAI groups may be used, where each DAI group uses a different DAI for different HARQ ACK/NACK payload sizes.

For example, as shown in <FIG>, a multiple DAI group mechanism may include CC1 and CC4 configured with TB-based retransmission (e.g., the number of CBGs per TB is one), and CC2 and CC3 configured with CBG-based retransmission with the number of CBGs per TB equal to <NUM>. In this case, the HARQ ACK/NACK feedback will include one bit for each TB granted on CC1 and CC4, and the HARQ ACK/NACK feedback will include four bits for each TB granted on CC2 and CC3. In this case, a first DAI counter is used for CC1 and CC4 (shown in light gray), and a second DAI counter is used for CC2 and CC3 (shown in dark gray). Note that slot <NUM> in CC3 is labeled as TB-based because the base station <NUM> may use fallback DCI for a particular slot to indicate TB-based transmission even though the component carrier has CBGs enabled by default (e.g., in some cases, a CBG configuration may be dynamically overridden). Using multiple DAI counters for different DAI groups adds further complexity to the HARQ ACK/NACK process, and increases a likelihood of ambiguities between the base station <NUM> and the UE <NUM> regarding a size of HARQ ACK/NACK feedback for different DAI groups. Some techniques and apparatuses described herein reduce or eliminate ambiguities between the base station <NUM> and the UE <NUM> regarding HARQ ACK/NACK feedback when the UE <NUM> misses the last downlink grant in a bundling window, when the UE <NUM> is associated with multiple DAI groups, and/or the like.

<FIG> is a diagram illustrating an example <NUM> of using a bundling window for HARQ ACK/NACK feedback, in accordance with various aspects of the present disclosure.

In NR, a downlink grant may indicate a timing between downlink assignment (e.g., a slot in which the downlink grant is received) and a corresponding downlink communication (e.g., on the physical downlink shared channel (PDSCH)). For example, this timing may be indicated by a field in DCI, and may be referred to as a K0 value. Similarly, an uplink grant may indicate a timing between uplink assignment and a corresponding uplink communication. Additionally, or alternatively, a downlink grant may indicate a timing between reception of a downlink communication (e.g., on the PDSCH) and a corresponding ACK/NACK indication (e.g., HARQ ACK/NACK feedback for the downlink communication). For example, this timing may be indicated by a field in DCI, and may be referred to as a K1 value.

As shown by reference number <NUM>, a downlink communication (e.g., a PDSCH communication), received by a UE <NUM> in slot <NUM>, may be associated with a K1 value of <NUM>. This K1 value may indicate a subsequent slot in which HARQ ACK/NACK feedback, corresponding to the downlink communication, is to be transmitted by the UE <NUM>. For example, the K1 value of <NUM> indicates that the HARQ ACK/NACK feedback for the downlink communication is to occur <NUM> slots after the slot in which the downlink communication is received (e.g., <NUM> slots after slot <NUM>). In this case, the downlink communication is received in slot <NUM>, and the K1 value of <NUM> indicates that the HARQ ACK/NACK feedback for downlink communication is to occur in slot <NUM>.

Similarly, as shown by reference number <NUM>, a downlink communication, received by the UE <NUM> in slot <NUM>, may be associated with a K1 value of <NUM>. This K1 value of <NUM> indicates that the HARQ ACK/NACK feedback for the downlink communication is to occur <NUM> slots after the slot in which the downlink communication is received (e.g., <NUM> slots after slot <NUM>). In other words, a K1 value of <NUM> indicates that the HARQ ACK/NACK feedback for the downlink communication is to occur in the same slot as the downlink communication. In this case, the HARQ ACK/NACK feedback may be referred to as an immediate HARQ ACK/NACK because the HARQ ACK/NACK feedback occurs in the same slot as the corresponding downlink communication.

As shown by reference number <NUM>, the UE <NUM> may transmit HARQ ACK/NACK feedback, corresponding to the downlink communications received in both slot <NUM> and slot <NUM>, in an uplink portion of slot <NUM>. In some aspects, the HARQ ACK/NACK feedback may include multiplexed or bundled HARQ ACK/NACK indications (e.g., ACK/NACK bits) for a bundling window, which includes all HARQ ACK/NACK feedback for downlink communications to be acknowledged or negatively acknowledged in the same slot.

As used herein, a bundling window may include a set of slots with a set of scheduled downlink communications (e.g., PDSCH communications), including received downlink communications (e.g., scheduled PDSCH communications received by a UE <NUM>) and unreceived downlink communications (e.g., scheduled PDSCH communications not received by the UE <NUM>). A bundling window may be associated with HARQ ACK/NACK multiplexing and/or HARQ ACK/NACK bundling. For example, a bundling window may include a number of slots, where downlink communications received in those slots are to be acknowledged or negatively acknowledged together using HARQ ACK/NACK multiplexing and/or HARQ ACK/NACK bundling (e.g., in a same uplink transmission time interval, such as a slot or a portion of a slot). In some aspects, a bundling window may include multiple slots with downlink grants that point to the same slot for HARQ ACK/NACK feedback. For example, the bundling window for HARQ ACK/NACK feedback reported in slot <NUM> may include slot <NUM> and slot <NUM>. Thus, a size of the bundling window may be dynamically configured in NR, and may include consecutive or non-consecutive slots.

In example <NUM>, if the UE <NUM> were to miss the downlink grant in slot <NUM>, then the UE <NUM> would transmit HARQ ACK/NACK feedback only for the downlink grant in slot <NUM>, and not for the downlink grant in slot <NUM>. In this case, the UE <NUM> would be unable to use DAI from slot <NUM> to determine that a downlink grant was missed in slot <NUM> because the UE <NUM> missed the downlink grant in slot <NUM> (e.g., including the DAI in the downlink grant), and would be unable to use DAI from any subsequent slots to determine that the downlink grant was missed in slot <NUM> because slot <NUM> is the last slot in the bundling window in which a downlink grant is transmitted. This leads to an ambiguity between the base station <NUM> and the UE <NUM> regarding HARQ ACK/NACK feedback because the base station <NUM> is expecting to receive HARQ ACK/NACK feedback for both the downlink grant in slot <NUM> and the downlink grant in slot <NUM>, whereas the UE <NUM> would only transmit HARQ ACK/NACK feedback for the downlink grant in slot <NUM> (e.g., because the UE <NUM> missed the downlink grant in slot <NUM> and was unable to determine that this downlink grant was missed).

Some techniques and apparatuses described herein reduce or eliminate ambiguities between the base station <NUM> and the UE <NUM> regarding HARQ ACK/NACK feedback when the UE <NUM> misses the last downlink grant in a bundling window, when the UE <NUM> is associated with multiple DAI groups, and/or the like.

In some aspects, to reduce or eliminate ambiguities between the base station <NUM> and the UE <NUM> regarding HARQ ACK/NACK feedback when the UE <NUM> misses the last downlink grant in a bundling window, the base station <NUM> may signal a total DAI using DCI other than a downlink grant. In some aspects, the UE <NUM> may transmit ACK/ACK feedback only when the DCI is received, thereby reducing or eliminating ambiguities regarding ACK/NACK feedback when the UE <NUM> misses the last downlink grant in a bundling window. In some aspects, this DCI may be transmitted in a final slot of a bundling window to provide an accurate count of the number of downlink grants transmitted to the UE <NUM> in the bundling window. The UE <NUM> may monitor the final slot of the bundling window for the total DAI included in the separate DCI that is not a downlink grant, and may transmit ACK/NACK feedback only when the total DAI is received in the final slot, thereby reducing or eliminating ambiguities regarding ACK/NACK feedback when the UE <NUM> misses the last downlink grant in a bundling window.

Additional details are provided below in connection with process <NUM> of <FIG> and process <NUM> of <FIG>. In some aspects, process <NUM> and/or process <NUM> may be used when the UE <NUM> transmits ACK/NACK feedback via a physical uplink control channel (PUCCH).

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a base station, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where a base station (e.g., base station <NUM> and/or the like) uses DAI in New Radio.

As shown in <FIG>, in some aspects, process <NUM> may include determining a total downlink assignment index (DAI) for a bundling window, wherein the total DAI indicates a number of downlink grants transmitted to a user equipment (UE) in the bundling window (block <NUM>). For example, the base station may determine (e.g., using controller/processor <NUM> and/or the like) a total DAI for a bundling window. The total DAI may indicate a number of downlink grants transmitted to a UE in the bundling window. The bundling window may be a dynamic bundling window determined based at least in part on one or more timing indications received in one or more downlink grants, as described above in connection with <FIG>.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting the total DAI to the UE in downlink control information (DCI) other than a downlink grant (block <NUM>). For example, the base station may transmit (e.g., using transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) the total DAI to the UE. The total DAI may be transmitted in DCI other than a downlink grant. In this way, the UE may receive an accurate count of the number of downlink grants transmitted in the bundling window even if the UE misses the last downlink grant in the bundling window (e.g., which would normally include the DAI used by the UE), thereby reducing or eliminating HARQ ACK/NACK ambiguities between the UE and the base station.

For example, if the UE misses the total DAI in the DCI other than a downlink grant, the UE may prevent HARQ ACK/NACK feedback from being reported in an initial opportunity (e.g., in the slot indicated by the downlink grants in the bundling window for HARQ ACK/NACK feedback). When the base station fails to receive the HARQ ACK/NACK feedback as expected, the base station and/or the UE may coordinate retransmissions (e.g., the base station may retransmit one or more downlink grants for the UE).

Process <NUM> may include additional aspects, such as any single aspect or any combination of aspects described below and/or in connection with one or more other processes described herein.

In some aspects, the total DAI is transmitted in a final slot of the bundling window. This may ensure an accurate indication of the number of downlink grants transmitted in the bundling window. In some aspects, the total DAI is transmitted in a slot other than a final slot of the bundling window. In this case, the total DAI may include an estimate of the number of downlink grants to be transmitted to the UE in the bundling window.

In some aspects, the total DAI is one of multiple total DAIs transmitted to the UE in the DCI. The multiple total DAIs may correspond to multiple DAI groups associated with the UE. Each of the multiple DAI groups may be associated with a different set of component carriers used for carrier aggregation, as described above in connection with <FIG>. In this way, ambiguities between the UE and the base station regarding HARQ ACK/NACK feedback for different DAI groups may be reduced or eliminated.

In some aspects, the total DAI is indicated in the DCI using more than two bits. For example, as described above in connection with <FIG>, in some aspects, DAI values included in downlink grants may be limited to <NUM> bits to ensure that enough bits remain to indicate other information needed in a downlink grant (e.g., a K0 value, a K1 value, and/or the like). When the total DAI is indicated in DCI other than a downlink grant, such limitations need not apply. Thus, more than <NUM> bits may be used for the total DAI, resulting in a more robust HARQ ACK/NACK mechanism. For example, the total DAI in the DCI other than a downlink grant may include <NUM> bits, <NUM> bits, and/or the like.

<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) uses DAI in New Radio.

As shown in <FIG>, in some aspects, process <NUM> may include monitoring a slot for a total downlink assignment index (DAI) in downlink control information (DCI) other than a downlink grant, wherein the total DAI indicates a number of downlink grants transmitted to the UE in a bundling window (block <NUM>). For example, the UE may monitor (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, and/or the like) a slot for a total DAI in downlink control information (DCI) other than a downlink grant. The total DAI may indicate a number of downlink grants transmitted to the UE in a bundling window. In this way, the UE may receive an accurate count of the number of downlink grants transmitted in the bundling window even if the UE misses the last downlink grant in the bundling window, as described above in connection with <FIG>.

As further shown in <FIG>, in some aspects, process <NUM> may include determining whether the total DAI has been received by the UE (block <NUM>). For example, the UE may determine (e.g., using controller/processor <NUM> and/or the like) whether the total DAI has been received by the UE. For example, the UE may determine whether the UE has received the DCI, other than a downlink grant, that includes the total DAI.

As further shown in <FIG>, in some aspects, process <NUM> may include selectively transmitting acknowledgement (ACK) or negative acknowledgement (NACK) (ACK/NACK) feedback for the bundling window based at least in part on whether the total DAI has been received (block <NUM>). For example, the UE may selectively transmit (e.g., using controller/processor <NUM> and/or the like to determine whether to transmit, using transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like to transmit) ACK/NACK feedback for the bundling window based at least in part on determining whether the total DAI has been received.

For example, if the total DAI has been received in the DCI other than a downlink grant, then the UE (e.g., controller processor <NUM> and/or the like) may instruct one or more components of UE (e.g., transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) to transmit the ACK/NACK feedback for the bundling window. Alternatively, if the total DAI has not been received in the DCI other than a downlink grant, then the UE (e.g., controller processor <NUM> and/or the like) may not provide ACK/NACK feedback to one or more components of the UE for transmission (e.g., transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like). In this way, the UE may prevent transmission of potentially ambiguous ACK/NACK feedback.

In some aspects, transmission of the ACK/NACK feedback in an initial uplink opportunity is prevented based at least in part on a determination that the total DAI has not been received. In some aspects, the ACK/NACK feedback is transmitted in an initial uplink opportunity based at least in part on a determination that the total DAI has been received. For example, if the UE misses the total DAI in the DCI other than a downlink grant, the UE may prevent HARQ ACK/NACK feedback from being reported in an initial opportunity (e.g., in the slot indicated by the downlink grants in the bundling window for HARQ ACK/NACK feedback). When the base station fails to receive the HARQ ACK/NACK feedback as expected, the base station and/or the UE may coordinate retransmissions (e.g., the base station may retransmit one or more downlink grants for the UE).

In some aspects, the slot is a final slot of the bundling window. This may ensure an accurate indication of the number of downlink grants transmitted in the bundling window. In some aspects, the slot is not a final slot of the bundling window. In some aspects, the total DAI includes an estimate of the number of downlink grants to be transmitted to the UE in the bundling window.

In some aspects, the total DAI is one of multiple total DAIs indicated in the DCI, wherein the multiple total DAIs correspond to multiple DAI groups associated with the UE, wherein each of the multiple DAI groups is associated with a different set of component carriers used for carrier aggregation. In this way, ambiguities between the UE and the base station regarding HARQ ACK/NACK feedback for different DAI groups may be reduced or eliminated, as described above in connection with <FIG>.

In some aspects, the total DAI is indicated in the DCI using more than two bits. In this way, the HARQ ACK/NACK mechanism may be more robust, as described above in connection with <FIG>.

In some aspects, to reduce or eliminate ambiguities between the base station <NUM> and the UE <NUM> regarding HARQ ACK/NACK feedback when the UE <NUM> misses the last downlink grant in a bundling window, the base station <NUM> may signal a total DAI using a downlink grant that is transmitted in a final slot of a bundling window, thereby providing an accurate count of the number of downlink grants transmitted to the UE <NUM> in the bundling window. The UE <NUM> may monitor the final slot of the bundling window for the total DAI, and may transmit ACK/NACK feedback only when the downlink grant is received in the final slot, thereby reducing or eliminating ambiguities regarding ACK/NACK feedback. In some aspects, the downlink grant may include a downlink assignment for the UE <NUM> in addition to the total DAI. In some aspects, the downlink grant may not include any downlink assignments for the UE <NUM> (e.g., may be a dummy downlink grant), and may only include the total DAI.

As shown in <FIG>, in some aspects, process <NUM> may include determining whether a downlink assignment is to be scheduled for a user equipment (UE) in a final slot of a bundling window (block <NUM>). For example, the base station may determine (e.g., using controller/processor <NUM> and/or the like) whether a downlink assignment is to be scheduled for a UE in a final slot of a bundling window.

As further shown in <FIG>, in some aspects, process <NUM> may include determining a total downlink assignment index (DAI) for the bundling window based at least in part on whether the downlink assignment is to be scheduled, wherein the total DAI indicates a number of downlink grants transmitted to the UE in the bundling window (block <NUM>). For example, the base station may determine (e.g., using controller/processor <NUM> and/or the like) a total DAI for the bundling window based at least in part on whether the downlink assignment is to be scheduled. The total DAI may indicate a number of downlink grants transmitted to the UE in the bundling window. Thus, the total DAI may be incremented (e.g., from a previously transmitted total DAI) if a downlink assignment is to be scheduled for the UE in the final slot of the bundling window, and may not be incremented if a downlink assignment is not to be scheduled for the UE in the final slot of the bundling window.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting the total DAI in the final slot of the bundling window regardless of whether the downlink assignment is to be scheduled in the final slot of the bundling window (block <NUM>). For example, the base station may transmit (e.g., using transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) the total DAI in the final slot of the bundling window regardless of whether the downlink assignment is to be scheduled in the final slot of the bundling window. In this way, the base station may guarantee that the UE has an accurate indication of the number of downlink grants transmitted to the UE in the bundling window because no downlink grants will be transmitted to the UE for the bundling window after the final slot of the bundling window.

In some aspects, the total DAI is transmitted in a downlink grant that schedules a downlink assignment for the UE in the final slot of the bundling window based at least in part on a determination that a downlink assignment is to be scheduled for the UE in the final slot of the bundling window. For example, the total DAI may be transmitted in a downlink grant that includes downlink assignment information (e.g., a K0 value, a K1 value, and/or the like). In this case (e.g., when a downlink assignment is to be scheduled for the UE in the final slot of the bundling window), the total DAI may be different from a most recently transmitted total DAI for the UE. For example, the total DAI transmitted in the downlink grant in the final slot may be incremented from the most recently transmitted total DAI for the UE (e.g., transmitted in a previous slot of the bundling window).

In some aspects, the total DAI is transmitted in a dummy downlink grant that does not schedule any downlink assignments for the UE based at least in part on a determination that a downlink assignment is not to be scheduled for the UE in the final slot of the bundling window. For example, the total DAI may be transmitted in a dummy downlink grant that does not include downlink assignment information (e.g., that does not include a K0 value, a K1 value, and/or the like). Additionally, or alternatively, the total DAI may be transmitted in DCI other than a downlink grant, as described above in connection with <FIG> and <FIG>. In this case (e.g., when a downlink assignment is not to be scheduled for the UE in the final slot of the bundling window), the total DAI may be the same as a most recently transmitted total DAI for the UE. For example, the total DAI transmitted in the dummy downlink grant in the final slot may not be incremented from the most recently transmitted total DAI for the UE (e.g., transmitted in a previous slot of the bundling window).

In some aspects, the total DAI is one of multiple total DAIs transmitted to the UE in the final slot of the bundling window. The multiple total DAIs may correspond to multiple DAI groups associated with the UE, and each of the multiple DAI groups may be associated with a different set of component carriers used for carrier aggregation, as described above in connection with <FIG>. In this way, ambiguities between the UE and the base station regarding HARQ ACK/NACK feedback for different DAI groups may be reduced or eliminated.

As shown in <FIG>, in some aspects, process <NUM> may include monitoring a final slot of a bundling window for a total downlink assignment index (DAI), wherein the total DAI indicates a number of downlink grants transmitted to the UE in the bundling window (block <NUM>). For example, the UE may monitor (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, and/or the like) a final slot of a bundling window for a total DAI. The total DAI may indicate a number of downlink grants transmitted to the UE in the bundling window.

As further shown in <FIG>, in some aspects, process <NUM> may include determining whether the total DAI has been received by the UE in the final slot of the bundling window (block <NUM>). For example, the UE may determine (e.g., using controller/processor <NUM> and/or the like), whether the total DAI has been received by the UE in the final slot of the bundling window.

As further shown in <FIG>, in some aspects, process <NUM> may include selectively transmitting acknowledgement (ACK) or negative acknowledgement (NACK) (ACK/NACK) feedback for the bundling window based at least in part on whether the total DAI has been received in the final slot of the bundling window (block <NUM>). For example, the UE may selectively transmit (e.g., using controller/processor <NUM> and/or the like to determine whether to transmit, using transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like to transmit) ACK/NACK feedback for the bundling window based at least in part on determining whether the total DAI has been received in the final slot of the bundling window.

For example, if the total DAI has been received in the final slot of the bundling window, then the UE (e.g., controller processor <NUM> and/or the like) may instruct one or more components of UE (e.g., transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) to transmit the ACK/NACK feedback for the bundling window. Alternatively, if the total DAI has not been received in the final slot of the bundling window, then the UE (e.g., controller processor <NUM> and/or the like) may not provide ACK/NACK feedback to one or more components of the UE for transmission (e.g., transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like). In this way, the UE may prevent transmission of potentially ambiguous ACK/NACK feedback.

In some aspects, transmission of the ACK/NACK feedback in an initial uplink opportunity is prevented based at least in part on a determination that the total DAI has not been received in the final slot of the bundling window. In some aspects, the ACK/NACK feedback is transmitted in an initial uplink opportunity based at least in part on a determination that the total DAI has been received in the final slot of the bundling window. For example, if the UE misses the total DAI in the final slot of the bundling window, the UE may prevent HARQ ACK/NACK feedback from being reported in an initial opportunity (e.g., in the slot indicated by the downlink grants in the bundling window for HARQ ACK/NACK feedback). When the base station fails to receive the HARQ ACK/NACK feedback as expected, the base station and/or the UE may coordinate retransmissions (e.g., the base station may retransmit one or more downlink grants for the UE).

In some aspects, the total DAI is received in a downlink grant that schedules a downlink assignment for the UE in the final slot of the bundling window. In some aspects, the total DAI is received in a dummy downlink grant that does not schedule any downlink assignments for the UE.

In some aspects, the total DAI is one of multiple total DAIs indicated in the final slot of the bundling window, wherein the multiple total DAIs correspond to multiple DAI groups associated with the UE, wherein each of the multiple DAI groups is associated with a different set of component carriers used for carrier aggregation. In this way, ambiguities between the UE and the base station regarding HARQ ACK/NACK feedback for different DAI groups may be reduced or eliminated.

In some aspects, to reduce or eliminate ambiguities between the base station <NUM> and the UE <NUM> regarding HARQ ACK/NACK feedback when the UE <NUM> misses the last downlink grant in a bundling window, the base station <NUM> may signal a total DAI using a common downlink control communication (e.g., a group common PDCCH communication) associated with multiple UEs <NUM>. In this way, network resources may be conserved by using a common downlink control communication to indicate different total DAIs corresponding to different UEs <NUM>.

As shown in <FIG>, in some aspects, process <NUM> may include determining multiple total downlink assignment indexes (DAIs) for a bundling window based at least in part on a number of downlink grants transmitted to each of multiple user equipment (UEs) in the bundling window (block <NUM>). For example, the base station may determine (e.g., using controller/processor <NUM> and/or the like) multiple total DAIs for a bundling window based at least in part on a number of downlink grants transmitted to each of multiple user equipment (UEs) in the bundling window. For example, the base station may determine a first total DAI for a first UE, may determine a second total DAI for a second UE, and/or the like. The base station may transmit control information (e.g., a power control command, a total DAI, and/or the like) to the multiple UEs using the same common downlink control communication, as described below.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting the multiple total DAIs in a common downlink control communication associated with the multiple UEs (block <NUM>). For example, the base station may transmit (e.g., using transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) the multiple total DAIs in a common downlink control communication associated with the multiple UEs. In some aspects, the common downlink control communication is a group common physical downlink control channel (PDCCH) communication.

In some aspects, the common downlink control communication includes multiple fields for indicating the multiple total DAIs. In this way, a UE may uniquely identify a total DAI that corresponds to the UE.

In some aspects, a field of the common downlink control communication in which a total DAI, of the multiple total DAIs, is to be indicated is determined based at least in part on a hash value associated with a UE corresponding to the total DAI. For example, a UE may use a hash value (e.g., a UE identifier, an index assigned to the UE, and/or the like) to identify which DAI field of the common downlink control communication includes the total DAI for the UE. The base station may store the hash value that will be used by the UE, and may insert the total DAI into the DAI field that the UE will identify using the hash value.

In some aspects, the multiple total DAIs include a set of total DAIs associated with a single UE, wherein each total DAI, in the set of total DAIs, is associated with a different set of component carriers used by the single UE for carrier aggregation. For example, a DAI field of the common downlink control communication may include a total DAI corresponding to a particular DAI group for a UE. In this case, the common downlink control communication may include multiple total DAIs for a single UE, where the multiple total DAIs correspond to different DAI groups of the UE. Thus, in some aspects, the number of DAI fields included in the common downlink control communication may be greater than the number of UEs associated with the common downlink control communication. In some aspects, a DAI field may be reused for multiple UEs, such as when two UEs share a total DAI, when two UEs share a total DAI for at least one DAI group, and/or the like.

In some aspects, a set of fields of the common downlink control communication in which the set of total DAIs is to be indicated is determined based at least in part on a set of hash values associated with the single UE. For example, a UE may use a set of hash values (e.g., determined based at least in part on a UE identifier, based at least in part on an index assigned to the UE, and/or the like) to identify which DAI fields of the common downlink control communication include the total DAI for the DAI groups of the UE. The base station may determine the set of hash values that will be used by the UE, and may insert the total DAIs into the DAI fields that the UE will identify using the set of hash values.

In some aspects, a field of the common downlink control communication is configured to indicate a maximum total DAI of at least two UEs based at least in part on a determination that the at least two UEs hash to the field. For example, in some cases, multiple UEs may hash to a same DAI field of the common downlink control communication. The base station may identify this scenario, may determine a maximum total DAI associated with the multiple UEs (e.g., by comparing total DAIs associated with the multiple UEs), and may insert the maximum total DAI into the DAI field to which the multiple UEs will hash. In this case, a UE that has received a smaller number of grants than indicated by the maximum total DAI may indicate a NACK for the additional bits, and the base station may ignore these ACK bits (e.g., may not retransmit a downlink grant for the UE because an initial downlink grant was never transmitted for the UE).

As shown in <FIG>, in some aspects, process <NUM> may include receiving a common downlink control communication, associated with multiple user equipment (UEs), that includes multiple total downlink assignment indexes (DAIs) that indicate a number of downlink grants transmitted to each of the multiple UEs in a bundling window (block <NUM>). For example, the UE may receive (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) a common downlink control communication associated with multiple UEs. The common downlink control communication may include multiple total DAIs that indicate a number of downlink grants transmitted to each of the multiple UEs in a bundling window, as described above in connection with <FIG>. In some aspects, the common downlink control communication is a group common physical downlink control channel (PDCCH) communication.

As further shown in <FIG>, in some aspects, process <NUM> may include identifying, from the common downlink control communication, a total DAI, of the multiple total DAIs, that corresponds to the UE (block <NUM>). For example, the UE may identify (e.g., using controller/processor <NUM> and/or the like), from the common downlink control communication, a total DAI, of the multiple total DAIs, that corresponds to the UE.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting acknowledgement (ACK) or negative acknowledgement (NACK) (ACK/NACK) feedback for the bundling window based at least in part on the total DAI (block <NUM>). For example, the UE may selectively transmit (e.g., using controller/processor <NUM> and/or the like to determine whether to transmit, using transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like to transmit) ACK/NACK feedback for the bundling window based at least in part on the total DAI, in the common downlink control communication, that corresponds to the UE. For example, the UE may transmit ACK/NACK feedback for the bundling window using a number of bits indicated by the total DAI.

In some aspects, the common downlink control communication includes multiple fields for indicating the multiple total DAIs. In some aspects, the total DAI is identified using a hash value, associated with the UE, that hashes to a field of the common downlink control communication in which the total DAI is indicated, as described above in connection with <FIG>.

In some aspects, the multiple total DAIs include a set of total DAIs associated with the UE, wherein each total DAI, in the set of total DAIs, is associated with a different set of component carriers used by the UE for carrier aggregation, as described above in connection with <FIG>. In some aspects, the set of total DAIs is identified by the UE using a set of hash values, associated with the UE, that hash to a set of fields of the common downlink control communication in which the set of total DAIs are indicated, as described above in connection with <FIG>.

In some aspects, a first slot in which the common downlink control communication is received is determined based at least in part on a timing relationship between the first slot and a second slot in which the UE is to transmit an uplink control communication. For example, the UE may determine a slot (e.g., X) in which the UE is to transmit an uplink control communication to report HARQ ACK/NACK feedback for the bundling window, and may determine another slot (e.g., X-<NUM>) to be monitored by the UE for the common downlink control communication. In some aspects, the timing relationship may be configured using an RRC configuration. In this way, the UE may conserve resources by monitoring for the common downlink control communication only in an appropriate slot.

In some aspects, to permit signaling of HARQ ACK/NACK feedback for multiple DAI groups, the base station <NUM> may signal multiple total DAIs, corresponding to the multiple groups, in an uplink grant. In this way, network resources may be conserved by using a single uplink grant to indicate different total DAIs corresponding to different DAI groups of the UE <NUM>, and ACK/NACK ambiguities associated with using multiple DAI groups may be reduced or eliminated.

Additional details are provided below in connection with process <NUM> of <FIG> and process <NUM> of <FIG>. In some aspects, process <NUM> and/or process <NUM> may be used when the UE <NUM> transmits ACK/NACK feedback via a physical uplink shared channel (PUSCH), such as when uplink control information is piggybacked on the PUSCH.

As shown in <FIG>, in some aspects, process <NUM> includes determining multiple total downlink assignment indexes (DAIs) corresponding to multiple DAI groups associated with a user equipment (UE), wherein each of the multiple DAI groups is associated with a different set of component carriers used by the UE for carrier aggregation (block <NUM>). According to the invention, the base station determines (e.g., using controller/processor <NUM> and/or the like) multiple total DAIs corresponding to multiple DAI groups associated with a UE. According to the invention, each DAI group is associated with a different set of component carriers used by the UE for carrier aggregation, as described above in connection with <FIG>. According to the invention, the base station determines a first total DAI for a first DAI group of the UE, and determines a second total DAI for a second DAI group of the UE.

As further shown in <FIG>, in some aspects, process <NUM> includes transmitting the multiple total DAIs to the UE in an uplink grant (block <NUM>). According to the invention, the base station transmits (e.g., using transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) the multiple total DAIs to the UE in an uplink grant.

According to the invention, the multiple total DAIs are indicated in different fields of the uplink grant. In some aspects, the uplink grant may be for an uplink data channel via which uplink control information is piggybacked. For example, the uplink grant may be for the PUSCH. In this way, when the UE is to transmit HARQ ACK/NACK feedback for different DAI groups via the PUSCH, the uplink grant may indicate the total DAIs for the different DAI groups, thereby reducing or eliminating ambiguities between the UE and the base station regarding HARQ ACK/NACK feedback for different DAI groups.

As shown in <FIG>, in some aspects, process <NUM> may include receiving an uplink grant that includes multiple total downlink assignment indexes (DAIs) corresponding to multiple DAI groups associated with the UE, wherein each of the multiple DAI groups is associated with a different set of component carriers used by the UE for carrier aggregation (block <NUM>). According to the invention, the UE receives (e.g., using antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, and/or the like) an uplink grant that includes multiple total DAIs corresponding to multiple DAI groups associated with the UE. According to the invention, each of the multiple DAI groups is associated with a different set of component carriers used by the UE for carrier aggregation, as described above in connection with <FIG>.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting acknowledgement (ACK) or negative acknowledgement (NACK) (ACK/NACK) feedback for the multiple DAI groups based at least in part on the multiple total DAIs included in the uplink grant (block <NUM>). According to the invention, the UE transmits (e.g., using controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like) ACK/NACK feedback for the multiple DAI groups based at least in part on the multiple total DAIs included in the uplink grant.

According to the invention, the multiple total DAIs are indicated in different fields of the uplink grant. In some aspects, the uplink grant may be for an uplink data channel via which uplink control information is piggybacked. For example, the uplink grant may be for the PUSCH. In some aspects, the ACK/NACK feedback is transmitted via the uplink data channel (e.g., the PUSCH and/or the like). In this way, when the UE is to transmit HARQ ACK/NACK feedback for different DAI groups via the PUSCH, the uplink grant may indicate the total DAIs for the different DAI groups, thereby reducing or eliminating ambiguities between the UE and the base station regarding HARQ ACK/NACK feedback for different DAI groups.

Claim 1:
A method of wireless communication performed by a base station, BS (no), comprising:
determining (<NUM>) multiple total downlink assignment indexes, DAIs, corresponding to multiple DAI groups associated with a user equipment, UE (<NUM>), wherein each of the multiple DAI groups is associated with a different set of component carriers, CCs, used by the UE (<NUM>) for carrier aggregation;
wherein the multiple total DAIs include a first total DAI for a first set of component carriers used by the UE (<NUM>) and a second total DAI for a second set of component carriers used by the UE (<NUM>), and
wherein a different number of code block groups, CBGs, per transport block, TB, are used for the first set of component carriers and the second set of component carriers; and
transmitting (<NUM>) the multiple total DAIs to the UE (<NUM>) in an uplink grant, wherein the multiple total DAIs are indicated in different fields of the uplink grant.