Techniques for Enhanced Sidelink Feedback Transmission

Abstract

Methods, systems, and devices for wireless communication are described. A first wireless device may monitor a set of physical sidelink shared channel (PSSCH) resources for sidelink messages from a second wireless device. The first wireless device may generate one or more codebooks including acknowledgement (ACK) or negative acknowledgement (NACK) bits corresponding to the sidelink messages. The first wireless device may transmit one or more feedback messages to the second wireless device on one or more physical sidelink feedback channel (PSFCH) resources according to a sidelink feedback configuration of the first wireless device. The one or more feedback messages may include an indication of the one or more codebooks. The techniques described herein may enable the first wireless device to transmit one or more feedback messages to the second wireless device with higher throughput and greater signaling efficiency, among other benefits.

Description

[Technical Field]

[0001] The following relates to wireless communications, including techniques for enhanced sidelink feedback transmission. [Background technology]

[0002] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcasts, etc. These systems may be capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth-generation (4G) systems, such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth-generation (5G) systems, sometimes referred to as New Radio (NR) systems. These systems may employ techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM), etc. A wireless multiple-access communication system may include one or more base stations or one or more network access nodes, each simultaneously supporting communication for multiple communication devices, which can sometimes be known as user equipment (UE).

[0003] In some wireless communication systems, a first wireless device may transmit sidelink feedback information to a second wireless device on physical sidelink feedback channel (PSFCH) resources. For example, the first wireless device may transmit one or more acknowledgement (ACK) or negative acknowledgement (NACK) bits corresponding to one or more sidelink messages from the second wireless device. However, in some cases, the first wireless device may not be able to transmit more than one ACK or NACK bit per PSFCH resource, which may result in lower throughput and reduced signaling efficiency at the first wireless device. Summary of the Invention

[0004] The described techniques relate to improved methods, systems, devices, and apparatuses that support techniques for enhanced sidelink feedback transmission. Generally, the described techniques provide for improving throughput and signaling efficiency of sidelink feedback transmission from a wireless device. In some examples, a first wireless device may monitor a set of physical sidelink shared channel (PSSCH) resources for sidelink messages from a second wireless device. The first wireless device may generate one or more codebooks including acknowledgement (ACK) or negative acknowledgement (NACK) bits corresponding to the sidelink messages. The first wireless device may transmit one or more feedback messages to a second wireless device on one or more physical sidelink feedback channel (PSFCH) resources according to the sidelink feedback configuration of the first wireless device. The one or more feedback messages may include an indication of the one or more codebooks. The techniques described herein may enable the first wireless device to transmit one or more feedback messages to a second wireless device with higher throughput and greater signaling efficiency, among other benefits.

[0005] A method for wireless communication in a first wireless device is described that may include monitoring a plurality of sidelink resources for a plurality of sidelink messages from a second wireless device, generating one or more codebooks comprising a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages, and transmitting a set of feedback messages to the second wireless device over the set of feedback resources in accordance with a sidelink feedback configuration of the first wireless device, the set of feedback messages comprising an indication of the one or more codebooks.

[0006] An apparatus for wireless communication in a first wireless device is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to monitor a plurality of sidelink resources for a plurality of sidelink messages from a second wireless device, generate one or more codebooks that include a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages, and transmit a set of feedback messages to the second wireless device over the set of feedback resources in accordance with a sidelink feedback configuration of the first wireless device, the set including an indication of the one or more codebooks.

[0007] Another apparatus for wireless communication in a first wireless device is described, which may include: means for monitoring a plurality of sidelink resources for a plurality of sidelink messages from a second wireless device; means for generating one or more codebooks comprising a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages; and means for transmitting, via the set of feedback resources, a set of feedback messages to the second wireless device in accordance with a sidelink feedback configuration of the first wireless device, the set of feedback messages comprising an indication of the one or more codebooks.

[0008] A non-transitory computer-readable medium storing code for wireless communication at a first wireless device is described, wherein the code may include instructions executable by a processor to: monitor a plurality of sidelink resources for a plurality of sidelink messages from a second wireless device; generate one or more codebooks comprising a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages; and transmit a set of feedback messages to the second wireless device over the set of feedback resources in accordance with a sidelink feedback configuration of the first wireless device, the set of feedback messages comprising an indication of the one or more codebooks.

[0009] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating one or more codebooks may include acts, functions, means, or instructions for generating a joint codebook including multiple ACK or NACK bits corresponding to multiple sidelink messages that may be associated with different priority levels, different group indices, or both.

[0010] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating the joint codebook may include operations, functions, means, or instructions for generating a first subset of the joint codebook including ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages associated with a first priority level, and for generating a second subset of the joint codebook including ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages associated with a second priority level, which may be different from the first priority level.

[0011] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating the joint codebook may include operations, functions, means, or instructions for generating a first subset of the joint codebook including ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages associated with a first group index, and for generating a second subset of the joint codebook including ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages associated with a second group index.

[0012] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first group index corresponds to a set of priority levels that may be below a sidelink priority threshold and the second group index corresponds to a set of priority levels that may be above the sidelink priority threshold.

[0013] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an act, function, means, or instruction to concatenate different subsets of the joint codebook in ascending or descending order with respect to priority level or group index.

[0014] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting the set of feedback messages may include an act, function, means, or instruction of transmitting, over a PSFCH resource, an indication of a joint codebook in accordance with a sidelink feedback configuration.

[0015] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the sidelink messages may be associated with respective priority levels, respective group indices, or both, and the sidelink feedback configuration indicates a sidelink priority threshold, a first mapping between the respective priority levels and one or more codebooks, a second mapping between the respective group indices and one or more codebooks, or a combination thereof.

[0016] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, multiple sidelink messages may be multiplexed with respective instances of sidelink control information (SCI).

[0017] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, each respective instance of the SCI includes an indication of a counter sidelink allocation index and an aggregate sidelink allocation index associated with a sidelink message from the plurality of sidelink messages.

[0018] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the counter sidelink allocation index and the total sidelink allocation index may be specific to a priority level, a group index, or both.

[0019] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the counter sidelink allocation index and the total sidelink allocation index may be applicable to different priority levels, different group indices, or both.

[0020] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, generating the one or more codebooks may include operations, functions, means, or instructions for generating a first codebook that includes ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages associated with a first priority level, and for generating a second codebook that includes ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages associated with a second priority level, which may be different from the first priority level.

[0021] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, generating the one or more codebooks may comprise operations, functions, means, or instructions for generating a first codebook including ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages associated with a first group index, and for generating a second codebook including ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages associated with a second group index, which may be different from the first group index.

[0022] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, transmitting the set of feedback messages may comprise: transmitting, via a first PSFCH resource, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages associated with a first priority level, a first group index, or both; and transmitting, via a second PSFCH resource, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages associated with a second priority level, a second group index, or both.

[0023] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include an operation, function, means, or instruction for receiving control signaling indicating one or more of: a quantity of one or more codebooks; a quantity of PSSCH groups; a quantity of PSSCH priority levels; a sidelink priority threshold; or an indication of whether ACK or NACK bits for sidelink messages associated with different priority levels, different group indices, or both should be included in a joint codebook or in separate codebooks, and generating the one or more codebooks may be based on the control signaling.

[0024] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the sidelink messages include unicast PSSCH transmissions.

[0025] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the sidelink messages include unicast PSSCH transmissions, groupcast PSSCH transmissions, or both.

[0026] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, unicast PSSCH transmissions and groupcast PSSCH transmissions may be associated with separate counter sidelink allocation indices and separate total sidelink allocation indices.

[0027] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating one or more codebooks may include an act, function, means, or instruction to generate a joint codebook that includes ACK or NACK bits corresponding to unicast PSSCH transmissions and groupcast PSSCH transmissions.

[0028] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating the joint codebook may include operations, functions, means, or instructions for generating a first subset of the joint codebook that includes ACK or NACK bits corresponding to unicast PSSCH channel transmissions, and for generating a second subset of the joint codebook that includes ACK or NACK bits corresponding to groupcast PSSCH transmissions, wherein the first subset of the joint codebook precedes the second subset of the joint codebook.

[0029] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting the set of feedback messages may include an act, function, means, or instruction of transmitting, on PSFCH resources, an indication of a joint codebook in accordance with a sidelink feedback configuration.

[0030] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting the set of feedback messages may include operations, functions, means, or instructions for transmitting, over a first PSFCH resource, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including an ACK or NACK bit corresponding to a unicast PSSCH transmission, and transmitting, over a second PSFCH resource, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including an ACK or NACK bit corresponding to a groupcast PSSCH transmission.

[0031] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an act, function, means, or instruction of receiving radio resource control (RRC) signaling indicating whether ACK or NACK bits for unicast PSSCH transmissions and ACK or NACK bits for groupcast PSSCH transmissions should be included in a single codebook or in different codebooks, and generating the one or more codebooks may be based on the RRC signaling.

[0032] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, function, means, or instruction for receiving RRC signaling indicating a sidelink feedback configuration, and transmitting the set of feedback messages to the second wireless device may be based on the RRC signaling.

[0033] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the plurality of sidelink messages includes a first set of groupcast PSSCH transmissions associated with a first group identifier and a second set of groupcast PSSCH transmissions associated with a second group identifier.

[0034] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating the one or more codebooks may include an act, function, means, or instruction for generating a joint codebook that includes acknowledgment or NACK bits corresponding to a first set of groupcast PSSCH transmissions and a second set of groupcast PSSCH transmissions.

[0035] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating the joint codebook may include operations, functions, means, or instructions for generating a first subset of the joint codebook that includes acknowledgment or NACK bits corresponding to a first set of groupcast PSSCH transmissions, and for generating a second subset of the joint codebook that includes acknowledgment or NACK bits corresponding to a second set of groupcast PSSCH transmissions.

[0036] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an act, function, means, or instruction for concatenating different subsets of the joint codebook in ascending order with respect to the group identifier.

[0037] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating one or more codebooks may include acts, functions, means, or instructions for generating a first codebook that includes ACK or NACK bits corresponding to a first set of groupcast PSSCH transmissions, and for generating a second codebook that includes ACK or NACK bits corresponding to a second set of groupcast PSSCH transmissions.

[0038] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting the set of feedback messages may include an act, function, means, or instruction of transmitting an indication of the first codebook and the second codebook on different PSFCH resources in accordance with the sidelink feedback configuration.

[0039] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an act, function, means, or instruction of receiving RRC signaling indicating whether the acknowledgment or negative acknowledgment bits for the first set of groupcast PSSCH transmissions and the acknowledgment or negative acknowledgment bits for the second set of groupcast PSSCH transmissions should be included in a single codebook or in different codebooks, and generating the one or more codebooks may be based on the RRC signaling.

[0040] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an act, function, means, or instruction to retransmit a set of feedback messages based on the outcome of a listen before talk (LBT) procedure, an unsuccessful initial transmission, or both.

[0041] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, functions, means, or instructions for receiving an SCI indicative of an ACK feedback indicator associated with a plurality of sidelink messages and for determining, based on the value of the ACK feedback indicator, whether one or both of a counter sidelink allocation index or a total sidelink allocation index for a subsequent sidelink message can be reset.

[0042] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating one or more codebooks may include acts, functions, means, or instructions for generating a codebook that includes ACK or NACK bits corresponding to multiple sidelink messages that may be associated with the same value of the ACK feedback indicator.

[0043] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, function, means, or instruction for receiving an SCI indicating a PSSCH group index, a hybrid automatic repeat request (HARQ)-ACK trigger field, or both, and determining, based on the SCI, whether to report HARQ-ACK feedback for the first PSSCH group, the second PSSCH group, or both.

[0044] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, generating one or more codebooks may include operations, functions, means, or instructions for generating one or more codebooks including HARQ-ACK feedback for the first PSSCH group and the second PSSCH group based on values ​​of the HARQ-ACK trigger field, where the one or more codebooks may be concatenated in ascending order with respect to the PSSCH group index.

[0045] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, functions, means, or instructions for receiving an SCI indicative of a counter sidelink allocation index, a first total sidelink allocation index associated with the first PSSCH group, a first ACK feedback indicator associated with the first PSSCH group, or a combination thereof, and determining whether one or both of the first total sidelink allocation index or the counter sidelink allocation index for the first PSSCH group can be reset based on the value of the first ACK feedback indicator.

[0046] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include an operation, function, means, or instruction for receiving an SCI indicating a second ACK feedback indicator and a second total sidelink allocation index associated with a second PSSCH group, and generating the one or more codebooks may be based on receiving the SCI.

[0047] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include an operation, function, means, or instruction for receiving RRC signaling indicating an SCI format comprising a group index field, a HARQ-ACK trigger field, a first acknowledgment feedback indicator field associated with the first PSSCH group, a second ACK feedback indicator field associated with the second PSSCH group, a counter sidelink allocation index field, a first total sidelink allocation index field associated with the first PSSCH group, a second total sidelink allocation index field associated with the second PSSCH group, or a combination thereof.

[0048] SUMMARY A method for wireless communication in a first wireless device is described. The method may include: transmitting, to a second wireless device, control signaling indicating a sidelink feedback configuration for the second wireless device; transmitting, via a plurality of sidelink resources, a plurality of sidelink messages to the second wireless device; and monitoring, according to the sidelink feedback configuration, a set of feedback resources for a set of feedback messages from the second wireless device, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages.

[0049] An apparatus for wireless communication in a first wireless device is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: transmit, to a second wireless device, control signaling indicating a sidelink feedback configuration for the second wireless device; transmit a plurality of sidelink messages to the second wireless device over a plurality of sidelink resources; and monitor a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages.

[0050] Another apparatus for wireless communication in a first wireless device is described. The apparatus may include: means for transmitting control signaling to a second wireless device indicating a sidelink feedback configuration for the second wireless device; means for transmitting a plurality of sidelink messages to the second wireless device over a plurality of sidelink resources; and means for monitoring a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages.

[0051] A non-transitory computer-readable medium storing code for wireless communication in a first wireless device is described, wherein the code may include instructions executable by a processor to: send control signaling to a second wireless device indicating a sidelink feedback configuration for the second wireless device; send a plurality of sidelink messages to the second wireless device over a plurality of sidelink resources; and monitor a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages.

[0052] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an operation, function, means, or instruction for receiving, via the PSFCH resource, from the second wireless device, an indication of a joint codebook including multiple ACK or NACK bits corresponding to multiple sidelink messages that may be associated with different priority levels, different group indices, or both.

[0053] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the sidelink messages may be associated with respective priority levels, respective group indices, or both, and the sidelink feedback configuration indicates a sidelink priority threshold, a first mapping between the respective priority levels and one or more codebooks, a second mapping between the respective group indices and one or more codebooks, or a combination thereof.

[0054] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, multiple sidelink messages may be multiplexed with respective instances of an SCI.

[0055] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, each respective instance of the SCI includes an indication of a counter sidelink allocation index and an aggregate sidelink allocation index associated with a sidelink message from the plurality of sidelink messages.

[0056] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the counter sidelink allocation index and the total sidelink allocation index may be specific to a priority level, a group index, or both.

[0057] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the counter sidelink allocation index and the total sidelink allocation index may be applicable to different priority levels, different group indices, or both.

[0058] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, functions, means, or instructions for receiving, via a first PSFCH resource, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, associated with a first priority level, a first group index, or both, and for receiving, via a second PSFCH resource, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, associated with a second priority level, a second group index, or both.

[0059] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting control signaling may include an act, function, means, or instruction of transmitting RRC signaling indicating a quantity of one or more codebooks, a quantity of PSSCH groups, a quantity of PSSCH priority levels, a sidelink priority threshold, or a combination thereof.

[0060] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the sidelink messages include unicast PSSCH transmissions.

[0061] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the sidelink messages include unicast PSSCH transmissions, groupcast PSSCH transmissions, or both.

[0062] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, unicast PSSCH transmissions and groupcast PSSCH transmissions may be associated with separate counter sidelink allocation indices and separate total sidelink allocation indices.

[0063] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an act, function, means, or instruction for receiving, over the PSFCH resource, a feedback message indicating a joint codebook including ACK or negative acknowledgement bits corresponding to unicast PSSCH transmissions and ACK or negative acknowledgement bits corresponding to groupcast PSSCH transmissions.

[0064] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, functions, means, or instructions for receiving, via a first PSFCH resource, a first feedback message indicating a first codebook that includes an ACK or NACK bit corresponding to a unicast PSSCH transmission, and receiving, via a second PSFCH resource, a second feedback message indicating a second codebook that includes an ACK or NACK bit corresponding to a groupcast PSSCH transmission.

[0065] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting control signaling may include an act, function, means, or instruction to transmit RRC signaling indicating whether ACK or NACK bits for unicast PSSCH transmissions and ACK or NACK bits for groupcast PSSCH transmissions should be included in a single codebook or in different codebooks.

[0066] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the plurality of sidelink messages includes a first set of groupcast PSSCH transmissions associated with a first group identifier and a second set of groupcast PSSCH transmissions associated with a second group identifier.

[0067] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting control signaling may include an act, function, means, or instruction of transmitting RRC signaling indicating whether acknowledgment or negative acknowledgment bits for a first set of groupcast PSSCH transmissions and acknowledgment or negative acknowledgment bits for a second set of groupcast PSSCH transmissions should be included in a single codebook or in different codebooks.

[0068] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include operations, functions, means, or instructions for receiving, via a first PSFCH resource, a first feedback message indicating a first codebook that includes ACK or NACK bits corresponding to a first set of groupcast PSSCH transmissions, and receiving, via a second PSFCH resource, a second feedback message indicating a second codebook that includes ACK or NACK bits corresponding to a second set of groupcast PSSCH transmissions.

[0069] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include an act, function, means, or instruction for receiving a feedback message indicating a codebook including ACK or NACK bits corresponding to multiple sidelink messages that may be associated with the same acknowledgement feedback indicator value.

[0070] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may further include an operation, function, means, or instruction for transmitting an SCI indicating a PSSCH group index, a HARQ-ACK trigger field, a first ACK feedback indicator associated with the first PSSCH group, a second ACK feedback indicator associated with the second PSSCH group, a counter sidelink allocation index, a first total sidelink allocation index associated with the first PSSCH group, a second total sidelink allocation index associated with the second PSSCH group, or a combination thereof.

[0071] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting the control signaling may further include an operation, function, means, or instruction for transmitting RRC signaling indicating an SCI format including a group index field, a HARQ-ACK trigger field, a first acknowledgment feedback indicator field associated with the first PSSCH group, a second ACK feedback indicator field associated with the second PSSCH group, a counter sidelink allocation index field, a first total sidelink allocation index field associated with the first PSSCH group, a second total sidelink allocation index field associated with the second PSSCH group, or a combination thereof.

[0072] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, transmitting control signaling may comprise an act, function, means, or instruction of transmitting an SCI indicating a counter sidelink allocation index, a total sidelink allocation index, an ACK feedback indicator, or a combination thereof, wherein a value of the ACK feedback indicator indicates whether one or both of the total sidelink allocation index or the counter sidelink allocation index may be reset for the PSSCH group. [Brief explanation of the drawings]

[0073] [Figure 1] 1 illustrates an example wireless communication system that supports techniques for enhanced sidelink feedback transmission, according to aspects of the present disclosure. [Figure 2] 1 illustrates an example wireless communication system that supports techniques for enhanced sidelink feedback transmission, according to aspects of the present disclosure. [Figure 3A] 10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 3B] 10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 4A] 10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 4B] 10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 5A] 10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 5B] 10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 6A] 10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 6B] 10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 7] 10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 8]10 illustrates an example of resource mapping supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 9] 1 illustrates an example of a process flow supporting techniques for enhanced sidelink feedback transmission, according to aspects of the present disclosure. [Figure 10] FIG. 1 illustrates a block diagram of a device supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 11] FIG. 1 illustrates a block diagram of a device supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 12] FIG. 1 illustrates a block diagram of a communications manager supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 13] FIG. 1 illustrates a diagram of a system including devices that support techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 14] 1 shows a flowchart illustrating a method for supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 15] 1 shows a flowchart illustrating a method for supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 16] 1 shows a flowchart illustrating a method for supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. [Figure 17] 1 shows a flowchart illustrating a method for supporting techniques for enhanced sidelink feedback transmission, according to an aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0074] In some wireless communication systems supporting sidelink communication between wireless devices, a first wireless device (e.g., user equipment (UE), sidelink device) may transmit a sidelink message to a second wireless device on physical sidelink shared channel (PSSCH) resources. The second wireless device (e.g., destination device) may transmit hybrid automatic repeat request (HARQ) acknowledgement (ACK) feedback for the sidelink message to the first wireless device (e.g., source device) on physical sidelink feedback channel (PSFCH) resources. The HARQ-ACK feedback may include an ACK bit or a negative acknowledgement (NACK) bit corresponding to the sidelink message. The second wireless device may determine which PSFCH resource to use for transmitting the HARQ-ACK feedback based on an identifier of the first wireless device, an identifier of the second wireless device, a mapping between PSSCH resources and PSFCH resources, or a combination thereof.

[0075] However, in some cases, the second wireless device may not be able to transmit more than one bit (e.g., an ACK or NACK bit) per PSFCH resource. Thus, when the second wireless device receives multiple sidelink messages from the first wireless device, the second wireless device may transmit HARQ-ACK feedback for the first sidelink message on the first PSFCH resource and may transmit HARQ-ACK feedback for the second sidelink message on the second PSFCH resource. Transmitting one bit per PSFCH resource may result in lower signaling overhead and higher power consumption at the second wireless device. Moreover, transmitting one bit per PSFCH resource may result in higher sidelink feedback reporting latency and lower achievable throughput (e.g., when there is a delay between the first and second PSFCH resources).

[0076] Aspects of the present disclosure provide for transmitting multiple ACK or NACK bits on a single PSFCH resource. Techniques described herein may improve latency and signaling efficiency of sidelink feedback reporting. As an example, the second wireless device may record ACK or NACK bits for multiple sidelink messages in a Type 2 HARQ-ACK codebook and may transmit an indication of the codebook on a single PSFCH resource. Each sidelink message received by the second wireless device (e.g., from the first wireless device) may be associated with a priority level, a group index, or both.

[0077] If the second wireless device receives sidelink messages with different priority levels, the second wireless device may generate a codebook such that ACK or NACK bits corresponding to sidelink messages of higher priority precede ACK or NACK bits corresponding to sidelink messages of lower priority (or vice versa). Alternatively, the second wireless device may generate different Type 2 HARQ-ACK codebooks for different priority levels or groups. For example, the second wireless device may record ACK or NACK bits for sidelink messages associated with a first group index in a first codebook and record ACK or NACK bits for sidelink messages associated with a second group index in a second codebook. The second wireless device may then transmit the first codebook on the first PSFCH resource and the second codebook on the second PSFCH resource.

[0078] The second wireless device may determine whether to include ACK or NACK bits for sidelink messages with different group indices or priority levels in separate or joint codebooks based on receiving control signaling, such as sidelink control information (SCI) or radio resource control (RRC) signaling, from the first wireless device or another network entity (e.g., a base station). This control signaling may indicate one or more total sidelink allocation indices, one or more counter sidelink allocation indices, one or more ACK feedback indicators, one or more HARQ-ACK trigger fields, or a combination thereof. The techniques described herein may enable the second wireless device to transmit sidelink feedback information with higher throughput, greater signaling efficiency, and reduced latency, among other benefits.

[0079] Aspects of the present disclosure are first described in the context of a wireless communication system, resource mapping, and process flows. Aspects of the present disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts relating to techniques for enhanced sidelink feedback transmission.

[0080] 1 illustrates an example of a wireless communication system 100 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an LTE Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable communications, low-latency communications, communications with low-cost and low-complexity devices, or any combination thereof.

[0081] The base stations 105 may be dispersed throughout a geographic area to form the wireless communication system 100 and may be devices of different types or with different capabilities. The base stations 105 and the UEs 115 may communicate wirelessly via one or more communication links 125. Each base station 105 may provide a coverage area 110 over which the UEs 115 and the base stations 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which the base stations 105 and the UEs 115 may support communication of signals according to one or more radio access technologies.

[0082] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary or mobile or both at different times. The UEs 115 may be devices of different forms or with different capabilities. Some example UEs 115 are shown in FIG. 1. The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115, base stations 105, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment), as shown in FIG. 1.

[0083] In some examples, one or more components of the wireless communication system 100 may operate as or be referred to as a network node. As used herein, a network node may refer to any UE 115, base station 105, core network 130 entity, apparatus, device, or computing system configured to implement any of the techniques described herein. For example, a network node may be a UE 115. As another example, a network node may be a base station 105. As another example, a first network node may be configured to communicate with a second network node or a third network node. In one aspect of this example, the first network node may be a UE 115, the second network node may be a base station 105, and the third network node may be a UE 115. In another aspect of this example, the first network node may be a UE 115, the second network node may be a base station 105, and the third network node may be a base station 105. In yet other aspects of this example, the first, second, and third network nodes may be different. Similarly, reference to a UE 115, a base station 105, an apparatus, a device, or a computing system may include disclosure of the UE 115, the base station 105, the apparatus, the device, or the computing system being a network node. For example, disclosure that a UE 115 is configured to receive information from a base station 105 also discloses that a first network node is configured to receive information from a second network node. In this example, consistent with the present disclosure, a first network node may refer to a first UE 115, a first base station 105, a first apparatus, a first device, or a first computing system configured to receive information, and a second network node may refer to a second UE 115, a second base station 105, a second apparatus, a second device, or a second computing system.

[0084] The base stations 105 may communicate with the core network 130, or with each other, or both. For example, the base stations 105 may interface with the core network 130 through one or more backhaul links 120 (e.g., via an S1, N2, N3, or other interface). The base stations 105 may communicate with each other via the backhaul links 120 (e.g., via an X2, Xn, or other interface), either directly (e.g., directly between the base stations 105) or indirectly (e.g., via the core network 130), or both. In some examples, the backhaul links 120 may be or include one or more wireless links.

[0085] One or more of the base stations 105 described herein may include or be referred to as a base transceiver station, radio base station, access point, radio transceiver, NodeB, eNodeB (eNB), next generation NodeB or giga-NodeB (any of which may be referred to as a gNB), Home NodeB, Home eNodeB, or other suitable terminology by those skilled in the art.

[0086] The UE 115 may include or be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, and a “device” may also be referred to as a unit, a station, a terminal, or a client, among other examples. The UE 115 may also include or be referred to as a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, the UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among other examples, which may be implemented in various items, such as an appliance, a vehicle, a meter, or the like.

[0087] The UEs 115 described herein may be capable of communicating with various types of devices, such as other UEs 115, which may act as relays, as shown in FIG. 1, as well as base stations 105 and network equipment, including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples.

[0088] The UE 115 and the base station 105 may communicate wirelessly with each other via one or more communication links 125 on one or more carriers. The term “carrier” may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication link 125. For example, a carrier used for the communication link 125 may include a portion (e.g., a bandwidth part (BWP)) of a radio frequency spectrum band operating according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling coordinating operation on the carrier, user data, or other signaling. The wireless communication system 100 may support communication with the UE 115 using carrier aggregation or multi-carrier operation. The UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation can be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers.

[0089] The communication links 125 shown in the wireless communication system 100 may include uplink transmissions from the UE 115 to the base station 105 or downlink transmissions from the base station 105 to the UE 115. A carrier may carry downlink or uplink communications (e.g., in FDD mode) or may be configured to carry downlink and uplink communications (e.g., in TDD mode).

[0090] A signal waveform transmitted on a carrier may be composed of multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Thus, the more resource elements the UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. Wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers may further increase data rates or data integrity for communications with UE 115.

[0091] One or more numerologies for a carrier may be supported, and a numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs with the same or different numerologies. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time, and communication for the UE 115 may be limited to one or more active BWPs.

[0092] The time interval for the base station 105 or the UE 115 is, for example, T s =1 / (Δf max N f) seconds, where Δf max may represent the maximum supported subcarrier spacing, and N f may represent the maximum supported discrete Fourier transform (DFT) size. The communication resource time intervals may be organized according to radio frames, each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0093] Each frame may include multiple consecutively numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into several slots. Alternatively, each frame may include a variable number of slots, and the number of slots may depend on the subcarrier spacing. Each slot may include several symbol periods (e.g., depending on the length of a cyclic prefix prepended to each symbol period). In some wireless communication systems, a slot may be further divided into multiple minislots, each containing one or more symbols. Excluding the cyclic prefix, each symbol period may include one or more (e.g., N f The duration of a symbol period may depend on the subcarrier spacing or the frequency band of operation.

[0094] A subframe, slot, minislot, or symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., among bursts of shortened TTIs (sTTIs)).

[0095] Physical channels may be multiplexed on carriers according to various techniques. Physical control channels and physical data channels may be multiplexed on downlink carriers using, for example, one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. A control region (e.g., a control resource set (CORESET)) for a physical control channel may be defined by several symbol periods and may extend across the system bandwidth of the carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESETs) may be configured for a set of UEs 115. For example, one or more of the UEs 115 may monitor or search the control region for control information according to one or more search space sets, and each search space set may include one or more control channel candidates at one or more aggregation levels arranged in a cascaded manner. The aggregation level for control channel candidates may refer to several control channel resources (e.g., control channel elements (CCEs)) associated with coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for sending control information to multiple UEs 115 and a UE-specific search space set for sending control information to a specific UE 115.

[0096] In some examples, the base stations 105 may be mobile and therefore may provide communication coverage to moving geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communication system 100 may include a heterogeneous network, for example, where different types of base stations 105 provide coverage to various geographic coverage areas 110 using the same or different radio access technologies.

[0097] Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception, but not simultaneous transmission and reception). In some examples, half-duplex communication may be implemented at a reduced peak rate. Other power conservation techniques for UEs 115 include entering a power-saving deep sleep mode when not engaged in active communication, operating over a limited bandwidth (e.g., pursuant to narrowband communication), or a combination of these techniques. For example, some UEs 115 may be configured for operation using a narrowband protocol type associated with a defined portion or range (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a guard band of a carrier, or outside a carrier.

[0098] The wireless communication system 100 may be configured to support ultra-reliable or low-latency communications, or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low-latency communications (URLLC). The UE 115 may be designed to support ultra-reliable, low-latency, or critical functionality. Ultra-reliable communications may include private or group communications and may be supported by one or more services such as push-to-talk, video, data, etc. Support for ultra-reliable, low-latency functionality may include service prioritization, and such services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, and ultra-reliable low-latency may be used interchangeably herein.

[0099] In some examples, the UE 115 may also be able to communicate directly with other UEs 115 via a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) protocol or a D2D protocol). One or more UEs 115 utilizing D2D communication may be within the geographic coverage area 110 of the base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of the base station 105 or may not be able to receive transmissions from the base station 105. In some examples, a group of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system in which each UE 115 transmits to every other UE 115 in the group. In some examples, the base station 105 facilitates scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without the involvement of the base station 105.

[0100] In some systems, the D2D communication link 135 may be an example of a communication channel between vehicles (e.g., UEs 115), such as a sidelink communication channel. In some examples, the vehicles may communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination thereof. The vehicles may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information relevant to the V2X system. In some examples, vehicles in a V2X system may communicate with roadside infrastructure, such as roadside units, or with a network via one or more network nodes (e.g., base stations 105) using vehicle-to-network (V2N) communication, or both.

[0101] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5G core, 5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) that manages access and mobility, and at least one user plane entity (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (PDN gateway (P-GW), or a user plane function (UPF)) that routes packets or interconnects to external networks. The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the core network 130. User IP packets may be forwarded through a user plane entity, which may provide IP address allocation and other functions. The user plane entity may connect to IP services 150 for one or more network operators. The IP services 150 may include access to the Internet, intranet(s), IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0102] Some of the network devices, such as the base stations 105, may include subcomponents, such as an access network entity 140, which may be an example of an access node controller (ANC). Each access network entity 140 may communicate with the UE 115 through one or more other access network transmitting entities 145, which may be referred to as radio heads, smart radio heads, or transmission / reception points (TRPs). Each access network transmitting entity 145 may include one or more antenna panels. In some configurations, various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or integrated into a single network device (e.g., the base station 105).

[0103] The wireless communication system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). The 300 MHz to 3 GHz region is commonly known as the ultra-high frequency (UHF) region or decimeter band because wavelengths range in length from approximately 1 decimeter to 1 meter. Although UHF waves may be blocked or redirected by buildings and environmental features, the waves can penetrate structures sufficiently for a macrocell to provide service to UEs 115 located indoors. Transmission of UHF waves may be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers) compared to transmissions using lower frequencies and longer waves in the shortwave (high frequency (HF)) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0104] The wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may utilize License Assisted Access (LAA), LTE-Unlicensed (LTE-U), or NR technology in an unlicensed band, such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in an unlicensed radio frequency spectrum band, devices such as the base station 105 and the UE 115 may utilize carrier sensing for collision detection and avoidance. In some examples, operation in an unlicensed band may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA). Operation in the unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

[0105] The base station 105 or the UE 115 may be equipped with multiple antennas that can be used to utilize techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of the base station 105 or the UE 115 may be located in one or more antenna arrays or antenna panels that can support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be collocated in an antenna assembly such as an antenna tower. In some examples, the antennas or antenna arrays associated with the base station 105 may be located in various geographic locations. The base station 105 may have an antenna array with several rows and columns of antenna ports that the base station 105 can use to support beamforming of communications with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals transmitted through the antenna ports.

[0106] Beamforming, sometimes referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting or receiving device (e.g., base station 105, UE 115) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming may be achieved by combining signals communicated through antenna elements of an antenna array such that some signals propagating in a particular orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjusting signals communicated through antenna elements may include the transmitting or receiving device applying an amplitude offset, a phase offset, or both to signals carried through the antenna element associated with the device. The adjustment associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., relative to the antenna array of the transmitting or receiving device, or to some other orientation).

[0107] The wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. The Radio Link Control (RLC) layer may perform packet segmentation and reassembly for communications on logical channels. The Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels onto transport channels. The MAC layer may also use error detection techniques, error correction techniques, or both to support retransmissions at the MAC layer and improve link efficiency. In the control plane, the RRC protocol layer may establish, configure, and maintain an RRC connection between the UE 115 and the base station 105 or core network 130, which supports radio bearers for user plane data. In the physical layer, transport channels may be mapped to physical channels.

[0108] The UE 115 and the base station 105 may support retransmission of data to increase the chance of successful reception of the data. HARQ feedback is one technique for increasing the likelihood that data will be accurately received over the communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions). In some examples, a device may support same-slot HARQ feedback, in which the device may provide HARQ feedback in a particular slot for data received in a previous symbol in that slot. In other cases, the device may provide HARQ feedback in a subsequent slot or according to some other time interval.

[0109] In some wireless communication systems, ACK or NACK feedback may be required in a PSFCH for a physical sidelink control channel (PSCCH) or PSSCH transmission. The PSFCH resources may be from a resource pool that may or may not be part of a dedicated PSFCH resource pool. A wireless device may be configured with a PSFCH resource periodicity (e.g., periodPSFCHresource) that refers to the period (in slots) for PSFCH transmission in the resource pool. Supported periods may include 0 slots (e.g., no PSFCH transmission), 1 slot, 2 slots, or 4 slots, among other examples. A PSFCH transmission may be performed in the first slot using available PSFCH resources after a PSSCH transmission and after a minimum gap time after the PSSCH (e.g., MinTimeGapPSFCH). The wireless device may also configure a set of resources (e.g., indicated by rbSetPSFCH) defined as a set of physical RBs (PRBs) for the PSFCH in a slot.

[0110]

number

[0111]

number

[0112]

number

[0113] The PSFCH resource pool is calculated using the formula:

[0114]

number

[0115]

number

[0116]

number

[0117]

number

[0118] The wireless device may be configured to:

[0119]

number

[0120] Some wireless devices may not support transmission of multiple ACK or NACK bits per PSFCH resource. A PSFCH resource may refer to one RB in one symbol having a format similar to physical uplink control channel (PUCCH) format 0. A PSFCH resource may carry one bit. If a wireless device is scheduled to send multiple ACK or NACK bits, the wireless device may FDM these bits over multiple PSFCH resources. This transmission technique may be applicable, for example, when a wireless device receives multiple PSFCHs from the same source device. In such a case, the PSFCH may be mapped to PSFCH resources hashed to the same PSFCH location (e.g., when the PSFCH period is 2 or 4 slots). This transmission technique may also be applicable when a wireless device receives multiple PSFCHs from different source devices and is scheduled to send a PSFCH to each source device. In such a case, there may be a limit on how many PSFCH resources a wireless device can multiplex in the same symbol.

[0121] Introducing multi-bit PSFCH transmission may be desirable for many scenarios, such as sidelink eMBB, where consecutive PSFCH streams may be more likely to be transmitted to the same destination node. Multi-bit PSFCH transmission may also be applied to sidelink carrier aggregation, which may increase the number of ACK or NACK bits that can be transmitted at a given time. Additionally, for sidelink applications in unlicensed radio frequency spectrum bands, wireless devices may not be able to configure frequent PSFCH opportunities (e.g., possible PSFCH transmissions may have a periodicity greater than four slots). Using conventional techniques to transmit multiple ACK or NACK bits may involve multiplexing many PSFCH resources. By introducing a multi-bit PSFCH, wireless devices can reduce the number of PSFCH resources multiplexed at a given time. In the case of multiple ACK or NACK bits to the same source UE, the techniques described herein may utilize a Uu uplink design in which the ACK or NACK bits are collected in a codebook and transmitted on a single channel.

[0122] For sidelink applications other than V2X, supporting the transmission of multiple ACK or NACK bits from one destination UE to the same source UE may result in higher throughput and greater signaling efficiency. The multiple ACK or NACK bits may correspond to multiple PSSCHs from the same node. The multiple ACK or NACK bits may also correspond to previously failed ACK or NACK transmissions (e.g., due to Listen-Before-Talk (LBT) failures in unlicensed bands) scheduled for retransmission from the destination node. To support the techniques described herein, a sidelink HARQ-ACK codebook may be used to convey multiple ACK or NACK bits from the destination device to the source. The techniques described herein provide for extending Type 2 HARQ-ACK codebook usage to sidelink applications. The described techniques also support an extended Type 2 HARQ-ACK codebook for sidelink operation in unlicensed bands.

[0123] The wireless communication system 100 may support techniques for improved sidelink feedback transmission at a wireless device. For example, the techniques and operations described with reference to FIG. 1 may enable a wireless device (e.g., a destination UE) to transmit multiple ACK or NACK bits on a single PSFCH resource (e.g., corresponding to multiple PSSCH transmissions from a source UE), as opposed to transmitting a single ACK or NACK bit per PSFCH resource. As a result, the wireless device may experience higher throughput and greater signaling efficiency, among other benefits.

[0124] 2 illustrates an example wireless communication system 200 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The wireless communication system 200 may implement or be implemented by aspects of the wireless communication system 100. For example, the wireless communication system 200 may include a UE 115-a, a UE 115-b, and a base station 105-a, which may be examples of corresponding devices described with reference to FIG. 1. The UE 115 and the base station 105-a may communicate within a geographical coverage area 110-a, which may be an example of the geographical coverage area 110 described with reference to FIG. 1. In the wireless communication system 200, the UE 115-a may generate one or more sidelink type 2 HARQ-ACK codebooks that include ACK or NACK bits corresponding to the sidelink message 210.

[0125] The wireless communication system 200 may support sidelink communication between the UE 115-a (e.g., a destination UE) and the UE 115-b (e.g., a source UE). For example, the UE 115-b may transmit a sidelink message 210 to the UE 115-a via PSSCH resources, and the UE 115-a may transmit a feedback message 215 to the UE 115-a via PSFCH resources. The feedback message 215 may include HARQ-ACK feedback (e.g., an ACK or NACK bit) corresponding to the sidelink message 210. To support transmission of the feedback message 215 on the PSFCH resources, the base station 105-a may transmit control signaling 205-a to the UE 115-a. Similarly, the base station 105-a may transmit control signaling 205-b to the UE 115-b. In some examples, the UE 115-a may relay the control signaling 205-a to the UE 115-b in accordance with a sidelink communication scheme. Similarly, the UE 115-b may relay the control signaling 205-b to the UE 115-a in accordance with a sidelink communication scheme.

[0126] In some examples, the control signaling 205 may include RRC signaling indicating a minimum PSFCH gap time (e.g., a minimum duration between PSSCH and PSFCH transmissions), a PSFCH periodicity (e.g., a number of slots between PSFCH resources), a mapping between PSSCH resources and PSFCH resources, a PSFCH resource pool configuration, an algorithm for identifying PSFCH resources based on an identifier of the UE 115, or a combination thereof. The control signaling 205 may also indicate a sidelink feedback configuration that the UE 115-a may use for sidelink type-2 HARQ-ACK codebook generation. For example, the control signaling 205 may indicate whether ACK or NACK bits for sidelink messages associated with different priority levels (e.g., PSSCH priority levels) or different groups (e.g., unicast PSSCH group, groupcast PSSCH group) should be included in a joint type-2 HARQ-ACK codebook or separate type-2 HARQ-ACK codebooks. Additionally or alternatively, the control signaling 205 may indicate whether the counter sidelink allocation index and the total allocation index are counted together or separately for different priority levels or groups.

[0127] The UE 115-b may transmit a sidelink message 210-a to the UE 115-a on a first PSSCH resource and may transmit a sidelink message 210-b to the UE 115-a on a second PSSCH resource. In some examples, the sidelink message 210 may be multiplexed with a respective PSCCH transmission containing an SCI related to the sidelink message 210. For example, the SCI (e.g., a piggybacked SCI) may indicate one or more of a total sidelink allocation index, a counter sidelink allocation index, an ACK feedback indicator, a group index, a priority level, or a HARQ-ACK feedback trigger for the sidelink message 210. In some examples, the UE 115-a may determine whether to reset the total sidelink allocation index and the counter sidelink allocation index for the sidelink message based on the value of the ACK feedback indicator. Similarly, the UE 115-a may determine whether to transmit a HARQ-ACK feedback for the sidelink message 210 based on the value of the HARQ-ACK feedback trigger.

[0128] The UE 115-a may generate HARQ-ACK feedback for the sidelink message 210 based on the control signaling 205 and the SCI from the PSCCH transmission multiplexed with the sidelink message 210. For example, the UE 115-a may determine (e.g., based on the SCI) that the sidelink message 210-a is associated with a first priority level, a first group (e.g., a unicast PSSCH group or a groupcast PSSCH group), or both. Similarly, the UE 115-a may determine that the sidelink message 210-b is associated with a second priority level, a second group index, or both. Accordingly, the UE 115-a may determine (e.g., based on the control signaling 205) whether ACK or NACK bits for the sidelink message 210 should be included in the same codebook or in different codebooks.

[0129] For example, if the UE 115-a generates separate type-2 HARQ-ACK codebooks for the sidelink messages 210, the UE 115-a may transmit an indication of the type-2 HARQ-ACK codebooks on separate PSFCH resources. For example, the UE 115-a may transmit a feedback message 215-a to the UE 115-b on a first PSFCH resource and a feedback message 215-b to the UE 115-b on a second PSFCH resource. The feedback message 215-a may include an indication of a first codebook containing ACK or NACK bits corresponding to the sidelink message 210-a, and the feedback message 215-b may include an indication of a second codebook containing ACK or NACK bits corresponding to the sidelink message 210-b. Alternatively, the UE 115-a may generate a joint codebook containing ACK or NACK bits for both sidelink messages 210. In such an example, the UE 115-a may transmit a joint codebook indication on a single PSFCH resource.

[0130] The wireless communication system 200 may support techniques for improved sidelink feedback transmission at the UE 115-a. For example, the techniques and operations described with reference to FIG. 2 may enable the UE 115-a (e.g., a destination UE) to transmit multiple ACK or NACK bits (e.g., corresponding to a sidelink message 210 from the UE 115-b) on a single PSFCH resource, as opposed to transmitting a single ACK or NACK bit per PSFCH resource. As a result, the UE 115-a may experience higher throughput and greater signaling efficiency, among other benefits.

[0131] 3A and 3B illustrate examples of resource mapping 300 and resource mapping 301 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The resource mapping 300 and resource mapping 301 may implement or be implemented by aspects of the wireless communication system 100 or the wireless communication system 200. For example, the resource mapping 300 and resource mapping 301 may implement or be implemented by a wireless device, which may be an example of the UE 115 described with reference to FIGS. 1 and 2. In accordance with the resource mapping 300 and resource mapping 301, the wireless device (e.g., the destination UE) may transmit an indication of a sidelink type 2 HARQ-ACK codebook, including ACK or NACK bits corresponding to sidelink messages with different priority levels or different group indices.

[0132] In the example of FIG. 3A, a first wireless device (e.g., a source UE) may transmit multiple PSSCH transmissions 310 (e.g., sidelink messages) to a second wireless device (e.g., a destination UE). For example, the first wireless device may transmit a PSSCH transmission 310-a to the second wireless device during slot 305-a and a PSSCH transmission 310-b to the second wireless device during slot 305-b. The first wireless device may also transmit a PSSCH transmission 310-c to the second wireless device during slot 305-d. Each PSSCH transmission 310 may be multiplexed with a corresponding PSCCH transmission, which may include an SCI related to the PSSCH transmission 310. Each instance of the SCI may indicate a total sidelink allocation index and a counter sidelink allocation index for a respective sidelink message.

[0133] After monitoring the PSSCH transmission 310 from the first wireless device, the second wireless device may generate a codebook 335-a (e.g., a type 2 HARQ-ACK codebook for sidelink messages) that includes an ACK or NACK bit corresponding to the PSSCH transmission 310. For example, the codebook 335-a may include an ACK or NACK bit 330-a corresponding to the PSSCH transmission 310-a, an ACK or NACK bit 330-b corresponding to the PSSCH transmission 310-b, and an ACK or NACK bit 330-c corresponding to the PSSCH transmission 310-c. As shown in FIG. 3A, the PSSCH transmission 310-a may be associated with a counter sidelink allocation index of 1, the PSSCH transmission 310-b may be associated with a counter sidelink allocation index of 2, and the PSSCH transmission 310-c may be associated with a counter sidelink allocation index of 3.

[0134] The second wireless device may transmit an indication of the codebook 335-a according to a sidelink feedback configuration, which may include a PSFCH periodicity 325-a and a minimum PSFCH gap time 320-a. The PSFCH periodicity 325-a may refer to the number of slots 305 between PSFCH resources 315, and the minimum PSFCH gap time 320-a may refer to the minimum number of slots between when the second wireless device receives a sidelink message and when the second wireless device can transmit feedback (e.g., HARQ-ACK feedback) for the sidelink message. For example, if the second wireless device successfully receives a PSSCH transmission 310-b in slot 305-b and the minimum PSFCH gap time 320-a is two slots, the second wireless device may not be able to transmit HARQ-ACK feedback (e.g., an ACK bit) for the PSSCH transmission 310-b until the minimum PSFCH gap time 320-a has elapsed (e.g., from slot 305-d). In other words, the second wireless device may transmit HARQ-ACK feedback for the PSSCH transmission 310-b in the first slot that includes a PSFCH resource and that is at least two slots after the last slot in which the second wireless device receives the PSSCH transmission 310-b. In accordance with this sidelink feedback configuration, the second wireless device may transmit an indication of the codebook 335-a to the first wireless device on the PSFCH resource 315-a located in slot 305-f.

[0135] In the example of FIG. 3B , a first wireless device (e.g., a source UE) may transmit multiple PSSCH transmissions 310 (e.g., sidelink messages) to a second wireless device (e.g., a destination UE). For example, the first wireless device may transmit a PSSCH transmission 310-d to the second wireless device during slot 305-g and a PSSCH transmission 310-e to the second wireless device during slot 305-h. The first wireless device may also transmit a PSSCH transmission 310-f to the second wireless device during slot 305-j. Each PSSCH transmission 310 may be multiplexed with a corresponding PSCCH transmission, which may include an SCI related to the PSSCH transmission 310. Each instance of the SCI may indicate a total sidelink allocation index and a counter sidelink allocation index for a respective sidelink message.

[0136] The PSSCH transmissions 310 may be associated with different PSSCH priority levels or different PSSCH groups (e.g., unicast or groupcast). For example, PSSCH transmissions 310-d and 310-f may be associated with a first PSSCH priority level or group, and PSSCH transmission 310-e may be associated with a second PSSCH priority level or group. In some examples, the total sidelink allocation index and the counter sidelink allocation index may be counted separately for different PSSCH priority levels or different PSSCH groups. Alternatively (e.g., as shown in the example of Figure 3B), the total sidelink allocation index and the counter sidelink allocation index may be counted together for different PSSCH priority levels or different PSSCH groups.

[0137] After monitoring the PSSCH transmission 310 from the first wireless device, the second wireless device may generate a codebook 335-b (e.g., a type-2 HARQ-ACK codebook for sidelink communications) that includes an ACK or NACK bit corresponding to the PSSCH transmission 310. For example, the codebook 335-b may include an ACK or NACK bit 330-d corresponding to the PSSCH transmission 310-d, an ACK or NACK bit 330-e corresponding to the PSSCH transmission 310-e, and an ACK or NACK bit 330-f corresponding to the PSSCH transmission 310-f. As shown in FIG. 3B, the PSSCH transmission 310-d may be associated with a counter sidelink allocation index of 1, the PSSCH transmission 310-e may be associated with a counter sidelink allocation index of 2, and the PSSCH transmission 310-f may be associated with a counter sidelink allocation index of 3.

[0138] The second wireless device may transmit an indication of the codebook 335-b according to a sidelink feedback configuration, which may include a PSFCH periodicity 325-b and a minimum PSFCH gap time 320-b. The PSFCH periodicity 325-b may refer to the number of slots 305 between PSFCH resources 315, and the minimum PSFCH gap time 320-b may refer to the minimum number of slots between when the second wireless device receives a sidelink message and when the second wireless device can transmit feedback (e.g., HARQ-ACK feedback) for the sidelink message. For example, if the second wireless device unsuccessfully receives a PSSCH transmission 310-e in slot 305-h and the minimum PSFCH gap time 320-b is two slots, the second wireless device may not be able to transmit HARQ-ACK feedback (e.g., a NACK bit) for the PSSCH transmission 310-e until the minimum PSFCH gap time 320-b has elapsed (e.g., from slot 305-j). In other words, the second wireless device may transmit HARQ-ACK feedback for the PSSCH transmission 310-e in the first slot that includes a PSFCH resource and that is at least two slots after the last slot in which the second wireless device receives the PSSCH transmission 310-e. In accordance with this sidelink feedback configuration, the second wireless device may transmit an indication of the codebook 335-b to the first wireless device on a PSFCH resource 315-b located in slot 305-l.

[0139] Resource mapping 300 and resource mapping 301 may support techniques for improved sidelink feedback transmission at a wireless device. For example, the techniques and operations described with reference to Figures 3A and 3B may enable a wireless device (e.g., a destination UE) to transmit multiple ACK or NACK bits on a single PSFCH resource (e.g., corresponding to multiple PSSCH transmissions from a source UE), as opposed to transmitting a single ACK or NACK bit per PSFCH resource. As a result, the wireless device may experience higher throughput and greater signaling efficiency, among other benefits.

[0140] 4A and 4B illustrate example resource mappings 400 and 401 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The resource mappings 400 and 401 may implement or be implemented by aspects of the wireless communication system 100 or the wireless communication system 200. For example, the resource mappings 400 and 401 may implement or be implemented by a wireless device, which may be an example of the UE 115 described with reference to FIGS. 1 and 2. According to the resource mappings 400, a wireless device (e.g., a destination UE) may generate a joint Type-2 HARQ-ACK codebook that includes ACK or NACK bits corresponding to sidelink messages (e.g., PSSCH transmissions) associated with different priority levels or groups (e.g., unicast PSSCH group, groupcast PSSCH group). According to the resource mappings 401, the wireless device may generate separate Type-2 HARQ-ACK codebooks that include ACK or NACK bits corresponding to sidelink messages associated with specific priority levels or group indices.

[0141] The resource mapping 400 and the resource mapping 401 may support Type-2 HARQ-ACK codebooks for unicast PSSCH transmissions. For example, the described techniques may support transmission of joint or mixed Type-2 HARQ-ACK codebooks for PSSCHs with different priorities. In some examples, the counter sidelink allocation index and the total sidelink allocation index in an SCI (e.g., SCI1 or SCI2A) may be counted together for PSSCHs with different priorities. In other examples, the counter sidelink allocation index and the total sidelink allocation index in an SCI (e.g., SCI1 or SCI2A) may be counted separately for different priorities. The Type-2 sub-codebooks for each PSSCH priority may be concatenated in ascending or descending order with respect to the PSSCH priority. In other examples, PSSCHs with different priorities may be separated into multiple groups. The counter sidelink allocation index and the total sidelink allocation index in an SCI (e.g., SCI1 or SCI2) may be counted separately for PSSCHs associated with different groups. The Type 2 sub-codebooks for each group may be concatenated in ascending or descending order with respect to the group index.

[0142] In some examples, these PSSCH groups may be hard-coded or configured via RRC signaling. Additionally or alternatively, the PSSCH group index may be determined based on the PSSCH priority level. For example, if M groups are defined or configured, Priority 0 to Priority (8 / M-1) belong to the first group, Priority (8 / M) to Priority (8 / M) belong to the second group, and so on. *2 / M-1) may belong to the second group. If M is 8 and there are two separate PSSCH groups, group index 0 may correspond to priority levels 0 through 3, and group index 1 may correspond to priority levels 4 through 7. In another example, the wireless device may use a sidelink priority threshold (e.g., sl-PriorityThreshold or sl-PriorityThreshold-UL-URLLC) to determine a suitable group for PSSCH transmission. If the priority level of the PSSCH transmission is below these thresholds, the PSSCH may be associated with the first group. Otherwise, the priority level may be associated with the second group. For example, group index 0 may correspond to a PSSCH priority level below sl-PriorityThreshold or sl-PriorityThreshold-UL-URLLC, and group index 1 may correspond to a PSSCH priority level above sl-PriorityThreshold or sl-PriorityThreshold-UL-URLLC.

[0143] The resource mapping 400 and the resource mapping 401 may also support separate Type-2 HARQ-ACK codebooks for PSSCH transmissions with different priorities. For example, the counter sidelink allocation index and the total sidelink allocation index in an SCI (e.g., SCI1 or SCI2A) may be counted together for PSSCH transmissions with corresponding HARQ-ACK bits transmitted in a common HARQ-ACK codebook. Alternatively, the counter sidelink allocation index and the total sidelink allocation index in an SCI (e.g., SCI1 or SCI2A) may be counted separately for PSSCH transmissions with corresponding HARQ-ACK bits transmitted in different HARQ-ACK codebooks.

[0144] In some examples, the number of separate HARQ-ACK codebooks for PSSCH transmissions with different priorities may be hard-coded or configurable via RRC signaling. For example, a HARQ-ACK codebook index of 0 may correspond to priority levels 0 through 3, and a HARQ-ACK codebook index of 1 may correspond to priority levels 4 through 7 (e.g., assuming two separate codebooks and eight different priority levels). Additionally or alternatively, the wireless device may use various sidelink priority thresholds (e.g., sl-PriorityThreshold or sl-PriorityThreshold-UL-URLLC) to determine the number of HARQ-ACK codebooks for reporting ACK or NACK bits for a PSSCH transmission. For PSSCH transmissions associated with priority levels below these thresholds, one HARQ-ACK codebook may be generated and transmitted on a single PSFCH resource. For PSSCH transmissions associated with priority levels above these thresholds, another HARQ-ACK codebook may be generated and transmitted on a different PSFCH resource. For example, a HARQ-ACK codebook index of 0 may correspond to a priority level below sl-PriorityThreshold or sl-PriorityThreshold-UL-URLLC, and a HARQ-ACK codebook index of 1 may correspond to a priority level above sl-PriorityThreshold or sl-PriorityThreshold-UL-URLLC. An indication of whether to use a joint or separate Type 2 HARQ-ACK codebook for PSSCH transmissions with different priorities can be configured via RRC signaling.

[0145] In the example of FIG. 4A , a first wireless device (e.g., a destination UE) may generate a joint codebook 435-a (e.g., a type 2 HARQ-ACK codebook for sidelink communications) that includes ACK or NACK bits 430 corresponding to PSSCH transmissions 410 associated with different PSSCH priority levels or groups. As an example, a second wireless device (e.g., a source UE) may transmit a PSSCH transmission 410-a to the first wireless device during slot 405-a and a PSSCH transmission 410-b to the first wireless device during slot 405-b. The second wireless device may also transmit a PSSCH transmission 410-c to the first wireless device during slot 405-d. The PSSCH transmission 410-a and the PSSCH transmission 410-c may be associated with a first PSSCH priority level or group, and the PSSCH transmission 410-b may be associated with a second PSSCH priority level or group. Each of the PSSCH transmissions 410 may be multiplexed with a corresponding PSCCH transmission that includes an SCI related to one of the PSSCH transmissions 410. Each instance of the SCI may indicate a counter sidelink allocation index and an aggregate sidelink allocation index for a respective PSSCH transmission (e.g., a sidelink message).

[0146] As shown in the example of Figure 4A, the total sidelink allocation index and the counter sidelink allocation index may be counted separately for different PSSCH priority levels or groups. For example, both PSSCH transmission 410-a and PSSCH transmission 410-b may be associated with a total sidelink allocation index of 1 and a counter sidelink allocation index of 1 (e.g., because these PSSCH transmissions belong to different PSSCH priority levels or groups). PSSCH transmission 410-c may be associated with a total sidelink allocation index of 2 and a counter sidelink allocation index of 2 (e.g., because PSSCH transmission 410-c follows PSSCH transmission 410-a).

[0147] After monitoring the PSSCH transmission 410, the first wireless device may generate a joint codebook 435-a that includes ACK or NACK bits 430 corresponding to the PSSCH transmission 410. The joint codebook 435-a may include a subset 440-a (e.g., a first sub-codebook) that corresponds to a first PSSCH priority level or group and a subset 440-b (e.g., a second sub-codebook) that corresponds to a second PSSCH priority level or group. The subset 440-a may include the ACK or NACK bits 430-a that correspond to the PSSCH transmission 410-a and the ACK or NACK bits 430-b that correspond to the PSSCH transmission 410-c, and the subset 440-b may include the ACK or NACK bits 430-c that correspond to the PSSCH transmission 410-b.

[0148] The first wireless device may transmit the joint codebook 435-a on the PSFCH resources 415-a in accordance with a sidelink feedback configuration of the first wireless device. As described herein, this sidelink feedback configuration may include a PSFCH periodicity 425-a and a minimum PSFCH gap time 420-a. The PSFCH periodicity 425-a may refer to the number of slots 405 between the PSFCH resources 415, and the minimum PSFCH gap time 420-a may refer to the minimum number of slots between when the first wireless device receives a sidelink message (e.g., a PSSCH transmission) and when the first wireless device can transmit feedback for the sidelink message (e.g., HARQ-ACK feedback). For example, if a first wireless device successfully receives a PSSCH transmission 410-b in slot 405-b and the minimum PSFCH gap time 420-a is two slots, the first wireless device may not be able to transmit HARQ-ACK feedback (e.g., an ACK bit) for the PSSCH transmission 410-b until the minimum PSFCH gap time 420-a has elapsed (e.g., from slot 405-d). In other words, the first wireless device may transmit HARQ-ACK feedback for the PSSCH transmission 410-b in the first slot that includes a PSFCH resource and that is at least two slots after the last slot in which the first wireless device receives the PSSCH transmission 410-b. In accordance with this sidelink feedback configuration, the first wireless device may transmit an indication of the joint codebook 435-a to the second wireless device on a PSFCH resource 415-a located in slot 405-f.

[0149] 4B , a first wireless device (e.g., a destination UE) may generate codebook 435-b and codebook 435-c (e.g., separate Type 2 HARQ-ACK codebooks) that include ACK or NACK bits 430 corresponding to PSSCH transmissions 410. Specifically, codebook 435-b may include HARQ-ACK feedback for PSSCH transmissions 410 associated with a first PSSCH priority level or group, and codebook 435-c may include HARQ-ACK feedback for PSSCH transmissions 410 associated with a second PSSCH priority level or group. As an example, a second wireless device (e.g., a source UE) may transmit PSSCH transmission 410-d to the first wireless device during slot 405-g and may transmit PSSCH transmission 410-e to the first wireless device during slot 405-h. The second wireless device may also transmit a PSSCH transmission 410-f to the first wireless device during slot 405-j. PSSCH transmission 410-d and PSSCH transmission 410-f may be associated with a first PSSCH priority level or group, and PSSCH transmission 410-e may be associated with a second PSSCH priority level or group. Each of the PSSCH transmissions 410 may be multiplexed with a corresponding PSCCH transmission that includes an SCI related to one of the PSSCH transmissions 410. The SCI may indicate a counter sidelink allocation index and an aggregate sidelink allocation index for the respective PSSCH transmission (e.g., a sidelink message).

[0150] As shown in the example of Figure 4B, the total sidelink allocation index and the counter sidelink allocation index may be counted separately for different PSSCH priority levels or groups. For example, both PSSCH transmission 410-d and PSSCH transmission 410-e may be associated with a total sidelink allocation index of 1 and a counter sidelink allocation index of 1 (e.g., because these PSSCH transmissions belong to different PSSCH priority levels or groups). PSSCH transmission 410-f may be associated with a total sidelink allocation index of 2 and a counter sidelink allocation index of 2 (e.g., because PSSCH transmission 410-f belongs to the first PSSCH priority level or group and follows PSSCH transmission 410-d).

[0151] After monitoring the PSSCH transmission 410, the first wireless device may generate codebook 435-b and codebook 435-c. Codebook 435-b may include ACK or NACK bits 430-d corresponding to PSSCH transmission 410-d and ACK or NACK bits 430-e corresponding to PSSCH transmission 410-f, and codebook 435-c may include ACK or NACK bits 430-f corresponding to PSSCH transmission 410-e. As described herein, the first wireless device may receive an indication via RRC signaling from the second wireless device or another network entity of whether to generate a joint codebook (as shown in FIG. 4A) or separate codebooks (as shown in FIG. 4B).

[0152] The first wireless device may transmit an indication of codebook 435-b on PSFCH resource 415-b and an indication of codebook 435-c on PSFCH resource 415-c. That is, the first wireless device may transmit the indication of codebook 435 on separate PSFCH resources 415 within slot 405-l. The first wireless device may transmit these indications in accordance with a sidelink feedback configuration, which may include a PSFCH periodicity 425-b and a minimum PSFCH gap time 420-b. The PSFCH periodicity 425-b may refer to the number of slots 405 between PSFCH resources 415, and the minimum PSFCH gap time 420-b may refer to the minimum number of slots between when the first wireless device receives a sidelink message (e.g., a PSSCH transmission) and when the first wireless device can transmit feedback for the sidelink message (e.g., HARQ-ACK feedback). For example, if a first wireless device unsuccessfully monitors for PSSCH transmission 410-e in slot 405-h and the minimum PSFCH gap time 420-b is two slots, the first wireless device may not be able to transmit HARQ-ACK feedback (e.g., a NACK bit) for PSSCH transmission 410-e until the minimum PSFCH gap time 420-b has elapsed (e.g., from slot 405-j). In other words, the first wireless device may transmit HARQ-ACK feedback for PSSCH transmission 410-e in the first slot that includes a PSFCH resource and that is at least two slots after the last slot in which the first wireless device receives PSSCH transmission 410-e.

[0153] Resource mapping 400 and resource mapping 401 may support techniques for improved sidelink feedback transmission at a wireless device. For example, the techniques and operations described with reference to Figures 4A and 4B may enable a wireless device (e.g., a destination UE) to transmit multiple ACK or NACK bits on a single PSFCH resource (e.g., corresponding to multiple PSSCH transmissions from a source UE), as opposed to transmitting a single ACK or NACK bit per PSFCH resource. As a result, the wireless device may experience higher throughput and greater signaling efficiency, among other benefits.

[0154] 5A and 5B illustrate example resource mappings 500 and 501 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The resource mappings 500 and 501 may implement or be implemented by aspects of the wireless communication system 100 or the wireless communication system 200. For example, the resource mappings 500 and 501 may implement or be implemented by a wireless device, which may be an example of the UE 115 described with reference to FIGS. 1 and 2. According to the resource mappings 500, the wireless device (e.g., the destination UE) may generate a joint Type-2 HARQ-ACK codebook that includes ACK or NACK bits corresponding to sidelink messages (e.g., PSSCH transmissions) associated with different priority levels or groups (e.g., unicast PSSCH group, groupcast PSSCH group). According to the resource mapping 501, the wireless device may generate a separate Type 2 HARQ-ACK codebook that includes ACK or NACK bits corresponding to sidelink messages associated with a particular priority level or group index (e.g., unicast PSSCH group, groupcast PSSCH group).

[0155] Resource mapping 500 and resource mapping 501 may support a Type 2 HARQ-ACK codebook for both unicast PSSCH transmissions and groupcast PSSCH transmissions using HARQ operation when the HARQ-ACK information includes an ACK or NACK bit. In some examples, the counter sidelink allocation index and total sidelink allocation index may be counted separately for unicast PSSCH transmissions and groupcast PSSCH transmissions. The Type 2 HARQ-ACK codebooks for unicast PSSCH transmissions and groupcast PSSCH transmissions may also be concatenated and multiplexed on the same PSFCH resource. In some examples, the Type 2 HARQ-ACK codebook for unicast PSSCH transmissions may precede the Type 2 HARQ-ACK codebook for groupcast PSSCH transmissions.

[0156] The Type 2 HARQ-ACK codebooks for unicast PSSCH transmissions and groupcast PSSCH transmissions may also be transmitted separately (e.g., on corresponding PSFCH resources). An indication of whether the Type 2 HARQ-ACK codebooks for unicast PSSCH transmissions and groupcast PSSCH transmissions should be transmitted together or separately may be configured via RRC signaling. The described techniques may be applicable when the groupcast UE is fixed (e.g., for PLC, sensors, actuators).

[0157] Resource mapping 500 and resource mapping 501 may also support Type-2 HARQ-ACK codebooks for multiple PSSCH groupcast groups. In such an example, the counter sidelink allocation index and total sidelink allocation index may be counted separately for each groupcast PSSCH group. As an example, a wireless device may generate a joint Type-2 codebook by concatenating Type-2 sub-codebooks for each PSSCH groupcast group in ascending order with respect to the group index. Alternatively, a wireless device may generate a separate Type-2 codebook for each groupcast PSSCH group and transmit these separate codebooks on separate PSFCH resources. A wireless device may receive RRC signaling from a network entity or another wireless device indicating whether to generate a joint or separate Type-2 codebook for different groupcast PSSCH groups. The techniques described herein may be applicable when one transmitting device has multiple groups of groupcast PSSCH transmissions to the same receiving device.

[0158] In the example of FIG. 5A , a first wireless device (e.g., a destination UE) may generate a joint codebook 535-a (e.g., a type 2 HARQ-ACK codebook for sidelink communications) that includes ACK or NACK bits 530 corresponding to unicast and groupcast PSSCH transmissions. As an example, a second wireless device (e.g., a source UE) may transmit a PSSCH transmission 510-a to the first wireless device during slot 505-a and a PSSCH transmission 510-b to the first wireless device during slot 505-b. The second wireless device may also transmit a PSSCH transmission 510-c to the first wireless device during slot 505-d. PSSCH transmission 510-a and PSSCH transmission 510-c may be examples of unicast PSSCH transmissions, and PSSCH transmission 510-b may be an example of a groupcast PSSCH transmission. Each of the PSSCH transmissions 510 may be multiplexed with a corresponding PSCCH transmission that includes an SCI related to one of the PSSCH transmissions 510. Each instance of the SCI may indicate a total sidelink allocation index and a counter sidelink allocation index for a respective PSSCH transmission (e.g., a sidelink message).

[0159] As shown in the example of Figure 5A, the total sidelink allocation index and counter sidelink allocation index may be counted separately for unicast and groupcast PSSCH transmissions. For example, both PSSCH transmissions 510-a and 510-b may be associated with a total sidelink allocation index of 1 and a counter sidelink allocation index of 1 (e.g., because PSSCH transmission 510-a is unicast and PSSCH transmission 510-b is groupcast). PSSCH transmission 510-c may be associated with a total sidelink allocation index of 2 and a counter sidelink allocation index of 2 (e.g., because PSSCH transmission 510-c is also groupcast).

[0160] After monitoring the PSSCH transmission 510, the first wireless device may generate a joint codebook 535-a that includes ACK or NACK bits 530 corresponding to the PSSCH transmission 510. The joint codebook 535-a may include a subset 540-a (e.g., a first sub-codebook) that corresponds to unicast PSSCH transmissions and a subset 540-b (e.g., a second sub-codebook) that corresponds to groupcast PSSCH transmissions. The subset 540-a may include the ACK or NACK bits 530-a that correspond to the PSSCH transmission 510-a and the ACK or NACK bits 530-b that correspond to the PSSCH transmission 510-c, and the subset 540-b may include the ACK or NACK bits 530-c that correspond to the PSSCH transmission 510-b.

[0161] The first wireless device may transmit the joint codebook 535-a on the PSFCH resources 515-a in accordance with a sidelink feedback configuration of the first wireless device. As described herein, this sidelink feedback configuration may include a PSFCH periodicity 525-a and a minimum PSFCH gap time 520-a. The PSFCH periodicity 525-a may refer to the number of slots 505 between the PSFCH resources 515, and the minimum PSFCH gap time 520-a may refer to the minimum number of slots between when the first wireless device receives a sidelink message (e.g., a PSSCH transmission) and when the first wireless device can transmit feedback for the sidelink message (e.g., HARQ-ACK feedback). For example, if a first wireless device successfully receives a PSSCH transmission 510-b in slot 505-b and the minimum PSFCH gap time 520-a is two slots, the first wireless device may not be able to transmit HARQ-ACK feedback (e.g., an ACK bit) for the PSSCH transmission 510-b until the minimum PSFCH gap time 520-a has elapsed (e.g., from slot 505-d). In other words, the first wireless device may transmit HARQ-ACK feedback for the PSSCH transmission 510-b in the first slot that includes a PSFCH resource and that is at least two slots after the last slot in which the first wireless device receives the PSSCH transmission 510-b. In accordance with this sidelink feedback configuration, the first wireless device may transmit an indication of the joint codebook 535-a to the second wireless device on a PSFCH resource 515-a located in slot 505-f.

[0162] 5B , a first wireless device (e.g., a destination UE) may generate codebook 535-b and codebook 535-c (e.g., separate Type 2 HARQ-ACK codebooks) that include ACK or NACK bits 530 corresponding to PSSCH transmission 510. Specifically, codebook 535-b may include HARQ-ACK feedback for unicast PSSCH transmissions, and codebook 535-c may include HARQ-ACK feedback for groupcast PSSCH transmissions. As an example, a second wireless device (e.g., a source UE) may transmit PSSCH transmission 510-d to the first wireless device during slot 505-g and may transmit PSSCH transmission 510-e to the first wireless device during slot 505-h. The second wireless device may also transmit PSSCH transmission 510-f to the first wireless device during slot 505-j. PSSCH transmissions 510-d and 510-f may be examples of unicast PSSCH transmissions, and PSSCH transmission 510-e may be an example of a groupcast transmission. Each of the PSSCH transmissions 510 may be multiplexed with a corresponding PSCCH transmission that includes an SCI related to one of the PSSCH transmissions 510. This SCI may indicate a counter sidelink allocation index and an aggregate sidelink allocation index for the respective PSSCH transmission (e.g., sidelink message).

[0163] As shown in the example of Figure 5B, the total sidelink allocation index and counter sidelink allocation index may be counted separately for unicast and groupcast. For example, both PSSCH transmission 510-d and PSSCH transmission 510-e may be associated with a total sidelink allocation index of 1 and a counter sidelink allocation index of 1 (e.g., because PSSCH transmission 510-d is unicast and PSSCH transmission 510-e is groupcast). PSSCH transmission 510-f may be associated with a total sidelink allocation index of 2 and a counter sidelink allocation index of 2 (e.g., because PSSCH transmission 510-f is also a groupcast PSSCH transmission).

[0164] After monitoring the PSSCH transmission 510, the first wireless device may generate codebook 535-b and codebook 535-c. Codebook 535-b may include ACK or NACK bits 530-d corresponding to PSSCH transmission 510-d and ACK or NACK bits 530-e corresponding to PSSCH transmission 510-f, and codebook 535-c may include ACK or NACK bits 530-f corresponding to PSSCH transmission 510-e. As described herein, the first wireless device may receive an indication via RRC signaling from the second wireless device or another network entity of whether to generate a joint codebook (as shown in FIG. 5A) or separate codebooks (as shown in FIG. 5B).

[0165] The first wireless device may transmit an indication of codebook 535-b on PSFCH resource 515-b and an indication of codebook 535-c on PSFCH resource 515-c. That is, the first wireless device may transmit the indication of codebook 535 on separate PSFCH resources 515 within slot 505-l. The first wireless device may transmit these indications in accordance with a sidelink feedback configuration that may include a PSFCH periodicity 525-b and a minimum PSFCH gap time 520-b. The PSFCH periodicity 525-b may refer to the number of slots 505 between PSFCH resources 515, and the minimum PSFCH gap time 520-b may refer to the minimum number of slots between when the first wireless device receives a sidelink message (e.g., a PSSCH transmission) and when the first wireless device can transmit feedback for the sidelink message (e.g., HARQ-ACK feedback). For example, if a first wireless device unsuccessfully monitors for PSSCH transmission 510-e in slot 505-h and the minimum PSFCH gap time 520-b is two slots, the first wireless device may not be able to transmit HARQ-ACK feedback (e.g., a NACK bit) for PSSCH transmission 510-e until the minimum PSFCH gap time 520-b has elapsed (e.g., after slot 505-j). In other words, the first wireless device may transmit HARQ-ACK feedback for PSSCH transmission 510-e in the first slot that includes a PSFCH resource and that is at least two slots after the last slot in which the first wireless device receives PSSCH transmission 510-e.

[0166] Resource mapping 500 and resource mapping 501 may support techniques for improved sidelink feedback transmission at a wireless device. For example, the techniques and operations described with reference to Figures 5A and 5B may enable a wireless device (e.g., a destination UE) to transmit multiple ACK or NACK bits on a single PSFCH resource (e.g., corresponding to multiple PSSCH transmissions from a source UE), as opposed to transmitting a single ACK or NACK bit per PSFCH resource. As a result, the wireless device may experience higher throughput and greater signaling efficiency, among other benefits.

[0167] 6A and 6B illustrate examples of resource mapping 600 and resource mapping 601 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. Resource mapping 600 and resource mapping 601 may implement or be implemented by aspects of wireless communication system 100 or wireless communication system 200. For example, resource mapping 600 and resource mapping 601 may implement or be implemented by a wireless device, which may be an example of UE 115 described with reference to FIGS. 1 and 2. According to resource mapping 600, a wireless device (e.g., a destination UE) may generate a joint Type-2 HARQ-ACK codebook that includes ACK or NACK bits corresponding to sidelink messages (e.g., PSSCH transmissions) associated with different groupcast PSSCH groups. According to resource mapping 601, the wireless device may generate separate Type-2 HARQ-ACK codebooks that include ACK or NACK bits corresponding to sidelink messages associated with specific groupcast PSSCH groups.

[0168] In the example of FIG. 6A , a first wireless device (e.g., a destination UE) may generate a joint codebook 635-a (e.g., a type-2 HARQ-ACK codebook for sidelink communications) that includes ACK or NACK bits 630 corresponding to different groupcast PSSCH groups. As an example, a second wireless device (e.g., a source UE) may transmit a PSSCH transmission 610-a to the first wireless device during slot 605-a and a PSSCH transmission 610-b to the first wireless device during slot 605-b. The second wireless device may also transmit a PSSCH transmission 610-c to the first wireless device during slot 605-d. The PSSCH transmission 610-a and the PSSCH transmission 610-c may be associated with the first groupcast PSSCH group, and the PSSCH transmission 610-b may be associated with the second groupcast PSSCH group. Each of the PSSCH transmissions 610 may be multiplexed with a corresponding PSCCH transmission that includes an SCI related to one of the PSSCH transmissions 610. Each instance of the SCI may indicate a counter sidelink allocation index and an aggregate sidelink allocation index for a respective PSSCH transmission (e.g., a sidelink message).

[0169] As shown in the example of Figure 6A, the total sidelink allocation index and counter sidelink allocation index may be counted separately for different groupcast PSSCH groups. For example, both PSSCH transmission 610-a and PSSCH transmission 610-b may be associated with a total sidelink allocation index of 1 and a counter sidelink allocation index of 1 (e.g., because these PSSCH transmissions 610-a and 610-b are associated with different groupcast PSSCH groups). PSSCH transmission 610-c may be associated with a total sidelink allocation index of 2 and a counter sidelink allocation index of 2 (e.g., because PSSCH transmission 610-c and PSSCH transmission 610-a are associated with the same groupcast PSSCH group).

[0170] After monitoring the PSSCH transmission 610, the first wireless device may generate a joint codebook 635-a that includes ACK or NACK bits 630 corresponding to the PSSCH transmission 610. The joint codebook 635-a may include a subset 640-a (e.g., a first sub-codebook) that corresponds to the first groupcast PSSCH group and a subset 640-b (e.g., a second sub-codebook) that corresponds to the second groupcast PSSCH group. The subset 640-a may include the ACK or NACK bits 630-a that correspond to the PSSCH transmission 610-a and the ACK or NACK bits 630-b that correspond to the PSSCH transmission 610-c, and the subset 640-b may include the ACK or NACK bits 630-c that correspond to the PSSCH transmission 610-b.

[0171] The first wireless device may transmit the joint codebook 635-a on the PSFCH resources 615-a in accordance with a sidelink feedback configuration of the first wireless device. As described herein, this sidelink feedback configuration may include a PSFCH periodicity 625-a and a minimum PSFCH gap time 620-a. The PSFCH periodicity 625-a may refer to the number of slots 605 between the PSFCH resources 615, and the minimum PSFCH gap time 620-a may refer to the minimum number of slots between when the first wireless device receives a sidelink message (e.g., a PSSCH transmission) and when the first wireless device can transmit feedback for the sidelink message (e.g., HARQ-ACK feedback). For example, if a first wireless device successfully receives a PSSCH transmission 610-b in slot 605-b and the minimum PSFCH gap time 620-a is two slots, the first wireless device may not be able to transmit HARQ-ACK feedback (e.g., an ACK bit) for the PSSCH transmission 610-b until the minimum PSFCH gap time 620-a has elapsed (e.g., from slot 605-d). In other words, the first wireless device may transmit HARQ-ACK feedback for the PSSCH transmission 610-b in the first slot that includes a PSFCH resource and that is at least two slots after the last slot in which the first wireless device receives the PSSCH transmission 610-b. In accordance with this sidelink feedback configuration, the first wireless device may transmit an indication of the joint codebook 635-a to the second wireless device on a PSFCH resource 615-a located in slot 605-f.

[0172] In the example of FIG. 6B , a first wireless device (e.g., a destination UE) may generate codebook 635-b and codebook 635-c (e.g., separate Type 2 HARQ-ACK codebooks) that include ACK or NACK bits 630 corresponding to PSSCH transmission 610. Specifically, codebook 635-b may include HARQ-ACK feedback for PSSCH transmission 610 in the first groupcast PSSCH group, and codebook 635-c may include HARQ-ACK feedback for PSSCH transmission 610 in the second groupcast PSSCH group. As an example, a second wireless device (e.g., a source UE) may transmit PSSCH transmission 610-d to the first wireless device during slot 605-g and may transmit PSSCH transmission 610-e to the first wireless device during slot 605-h. The second wireless device may also transmit PSSCH transmission 610-f to the first wireless device during slot 605-j. PSSCH transmission 610-d and PSSCH transmission 610-f may be examples of unicast PSSCH transmissions, and PSSCH transmission 610-e may be an example of a groupcast transmission. Each of the PSSCH transmissions 610 may be multiplexed with a corresponding PSCCH transmission that includes an SCI related to one of the PSSCH transmissions 610. Each instance of the SCI may indicate a counter sidelink allocation index and an aggregate sidelink allocation index for a respective PSSCH transmission (e.g., a sidelink message).

[0173] As shown in the example of Figure 6B, the total sidelink allocation index and counter sidelink allocation index may be counted separately for different groupcast PSSCH groups. For example, both PSSCH transmission 610-d and PSSCH transmission 610-e may be associated with a total sidelink allocation index of 1 and a counter sidelink allocation index of 1 (e.g., because these PSSCH transmissions belong to different groupcast PSSCH groups). PSSCH transmission 610-f may be associated with a total sidelink allocation index of 2 and a counter sidelink allocation index of 2 (e.g., because PSSCH transmission 610-f and PSSCH transmission 610-d belong to the same groupcast PSSCH group).

[0174] After monitoring the PSSCH transmission 610, the first wireless device may generate a codebook 635-b and a codebook 635-c. The codebook 635-b may include an ACK or NACK bit 630-d corresponding to the PSSCH transmission 610-d and an ACK or NACK bit 630-e corresponding to the PSSCH transmission 610-f, and the codebook 635-c may include an ACK or NACK bit 630-f corresponding to the PSSCH transmission 610-e. As described herein, the first wireless device may receive an indication via RRC signaling from the second wireless device or another network entity of whether to generate a joint codebook (as shown in FIG. 6A) or separate codebooks (as shown in FIG. 6B).

[0175] The first wireless device may transmit an indication of codebook 635-b on PSFCH resource 615-b and an indication of codebook 635-c on PSFCH resource 615-c. That is, the first wireless device may transmit the indication of codebook 635 on separate PSFCH resources 615 within slot 605-l. The first wireless device may transmit these indications in accordance with a sidelink feedback configuration, which may include a PSFCH periodicity 625-b and a minimum PSFCH gap time 620-b. The PSFCH periodicity 625-b may refer to the number of slots 605 between PSFCH resources 615, and the minimum PSFCH gap time 620-b may refer to the minimum number of slots between when the first wireless device receives a sidelink message (e.g., a PSSCH transmission) and when the first wireless device can transmit feedback for the sidelink message (e.g., HARQ-ACK feedback). For example, if a first wireless device unsuccessfully monitors for a PSSCH transmission 610-e in slot 605-h and the minimum PSFCH gap time 620-b is two slots, the first wireless device may not be able to transmit HARQ-ACK feedback (e.g., a NACK bit) for the PSSCH transmission 610-e until the minimum PSFCH gap time 620-b has elapsed (e.g., after slot 605-j). In other words, the first wireless device may transmit HARQ-ACK feedback for the PSSCH transmission 610-e in the first slot that includes a PSFCH resource and that is at least two slots after the last slot in which the first wireless device receives the PSSCH transmission 610-e.

[0176] Resource mapping 600 and resource mapping 601 may support techniques for improved sidelink feedback transmission at a wireless device. For example, the techniques and operations described with reference to Figures 6A and 6B may enable a wireless device (e.g., a destination UE) to transmit multiple ACK or NACK bits on a single PSFCH resource (e.g., corresponding to multiple PSSCH transmissions from a source UE), as opposed to transmitting a single ACK or NACK bit per PSFCH resource. As a result, the wireless device may experience higher throughput and greater signaling efficiency, among other benefits.

[0177] 7 illustrates an example of a resource mapping 700 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The resource mapping 700 may implement or be implemented by aspects of the wireless communication system 100 or the wireless communication system 200. For example, the resource mapping 700 may implement or be implemented by a wireless device that may be an example of the UE 115 described with reference to FIG. 1 and FIG. 2. According to the resource mapping 700, the wireless device (e.g., the destination UE) may retransmit an indication of the codebook 735-a on the PSFCH resource 715-c after unsuccessfully transmitting an indication of the codebook 735-a on the PSFCH resource 715-b.

[0178] The resource mapping 700 may support an extended sidelink type 2 HARQ-ACK codebook to enable retransmission of previously transmitted or unsuccessfully transmitted HARQ-ACK feedback (e.g., due to an LBT failure). The number of PSSCH groups can be hard-coded or configurable via RRC signaling. In the case of a single PSSCH group, an ACK feedback indicator in an SCI (e.g., SCI1 or SCI2A) may be used to support the extended sidelink type 2 HARQ-ACK codebook. For example, when the ACK feedback indicator is toggled, the counter sidelink allocation index and the total sidelink allocation index may be reset. Therefore, the counter sidelink allocation index and the total sidelink allocation index may or may not be reset with the PSFCH opportunity.

[0179] 7, a first wireless device (e.g., a destination UE) may monitor a PSSCH transmission 710 from a second wireless device (e.g., a source UE) in multiple slots. For example, the first wireless device may monitor PSSCH transmission 710-a, PSSCH transmission 710-b, PSSCH transmission 710-c, PSSCH transmission 710-d, PSSCH transmission 710-e, and PSSCH transmission 710-f in the first slot (e.g., slot n), second slot (e.g., slot n+1), fourth slot (e.g., slot n+3), seventh slot (e.g., slot n+6), eighth slot (e.g., slot n+7), and tenth slot (e.g., slot n+9), respectively.

[0180] Each of the PSSCH transmissions 710 may be multiplexed with a respective PSCCH transmission that includes an SCI related to one of the PSSCH transmissions 710. This SCI may indicate a total sidelink allocation index, a counter sidelink allocation index, an ACK feedback indicator, or a combination thereof. In the example of Figure 7, PSSCH transmission 710-a may be associated with a total sidelink allocation index of 1, a counter sidelink allocation index of 1, and an ACK feedback indicator of 0. Similarly, PSSCH transmission 710-b may be associated with a total sidelink allocation index of 2, a counter sidelink allocation index of 2, and an ACK feedback indicator of 0. PSSCH transmission 710-c may be associated with a total sidelink allocation index of 3, a counter sidelink allocation index of 3, and an ACK feedback indicator of 0. PSSCH transmission 710-d may be associated with a total sidelink allocation index of 4, a counter sidelink allocation index of 4, and an ACK feedback indicator of 0. The PSSCH transmission 710-e may be associated with a total sidelink allocation index of 1, a counter sidelink allocation index of 1, and an ACK feedback indicator of 0. The PSSCH transmission 710-f may be associated with a total sidelink allocation index of 1, a counter sidelink allocation index of 1, and an ACK feedback indicator of 1.

[0181] In some examples, the first wireless device may reset the counter sidelink allocation index and the total sidelink allocation of a PSSCH transmission 710-f based on the value of an ACK feedback indicator associated with the PSSCH transmission, as opposed to resetting the counter sidelink allocation index and the total sidelink allocation of the PSSCH transmission 710-f after each PSFCH opportunity. For example, the first wireless device may reset the counter sidelink allocation and the total sidelink allocation index of a PSSCH transmission 710-f based on the value (e.g., 1) of an ACK feedback indicator associated with the PSSCH transmission 710-f, which may toggle between different values.

[0182] The first wireless device may generate a codebook 735-a (e.g., a first type-2 HARQ-ACK codebook) that includes ACK or NACK bits 730 corresponding to the PSSCH transmission 710. For example, the codebook 735-a may include an ACK or NACK bit 730-a corresponding to the PSSCH transmission 710-a, an ACK or NACK bit 730-b corresponding to the PSSCH transmission 710-b, and an ACK or NACK bit 730-c corresponding to the PSSCH transmission 710-c. After generating the codebook 735-a, the first wireless device may attempt to transmit an indication of the codebook 735-a on a PSFCH resource 715-b in accordance with a sidelink feedback configuration of the first wireless device. Specifically, the first wireless device may identify a PSFCH resource 715 suitable to use for transmission of the codebook 735-a based on a PSFCH periodicity and a minimum PSFCH gap time configured for the first wireless device. For example, if the first wireless device is configured with a minimum PSFCH gap time of two slots, the first wireless device may not be able to transmit the indication of codebook 735-a on PSFCH resource 715-a because PSFCH resource 715-a is within two slots of when the first wireless device received the PSSCH transmission 710 associated with codebook 735-a. Thus, the first wireless device may determine to transmit the indication of codebook 735-a on PSFCH resource 715-b.

[0183] However, in some examples, the transmission of the codebook 735-a may be unsuccessful. Specifically, the first wireless device may be unable to transmit the indication of the codebook 735-a on the PSFCH resource 715-b, for example, if the first wireless device experiences an LBT failure (e.g., if the first wireless device is communicating with the second wireless device in an unlicensed radio frequency spectrum band, such as an NR unlicensed (NR-U) frequency band). In other examples, the transmission of the codebook 735-a may be unsuccessful due to poor channel conditions or interference at the second wireless device.

[0184] According to the techniques described herein, the first wireless device may be configured to retransmit ACK or NACK bits 730 from codebook 735-a if an initial transmission of codebook 735-a is unsuccessful. For example, the first wireless device may append ACK or NACK bits 730 from codebook 735-a to codebook 735-b (e.g., a second type-2 HARQ-ACK codebook) and transmit an indication of codebook 735-b on PSFCH resource 715-c. Thus, codebook 735-b may include ACK or NACK bits 730-a corresponding to PSSCH transmission 710-a, ACK or NACK bits 730-b corresponding to PSSCH transmission 710-b, ACK or NACK bits 730-c corresponding to PSSCH transmission 710-c, ACK or NACK bits 730-d corresponding to PSSCH transmission 710-d, and ACK or NACK bits 730-e corresponding to PSSCH transmission 710-e.

[0185] The resource mapping 700 may support techniques for improved sidelink feedback transmission at a wireless device. For example, the techniques and operations described with reference to FIG. 7 may enable a wireless device (e.g., a destination UE) to transmit multiple ACK or NACK bits on a single PSFCH resource (e.g., corresponding to multiple PSSCH transmissions from a source UE), as opposed to transmitting a single ACK or NACK bit per PSFCH resource. As a result, the wireless device may experience higher throughput and greater signaling efficiency, among other benefits.

[0186] 8 illustrates an example of a resource mapping 800 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The resource mapping 800 may implement or be implemented by aspects of wireless communication system 100 or wireless communication system 200. For example, the resource mapping 800 may implement or be implemented by a wireless device that may be an example of a UE 115 described with reference to FIG. 1 and FIG. 2. According to the resource mapping 800, the wireless device (e.g., the destination UE) may retransmit an indication of codebook 835-a on PSFCH resource 815-c after unsuccessfully transmitting an indication of codebook 835-a on PSFCH resource 815-b.

[0187] The resource mapping 800 may support a Type 2 HARQ-ACK codebook for two different PSSCH groups. To support this feature, a group index field may be added to the SCI (e.g., SCI1 or SCI2A). A 1-bit HARQ-ACK trigger field may be added to the SCI, with "0" indicating that HARQ-ACK feedback is configured for the scheduled PSSCH group and "1" indicating that HARQ-ACK feedback is configured for both the scheduled and non-scheduled PSSCH groups. When both PSSCH groups are triggered by the HARQ-ACK trigger field, the placement of the HARQ-ACK feedback for the two PSSCH groups may be ordered in ascending order with respect to the group index. The SCI may also be modified to include an ACK feedback indicator for the non-scheduled PSSCH group and a total sidelink allocation index field.

[0188] For some devices (e.g., Mode 1 UEs), an indication of whether the SCI format includes the ACK feedback indicator and total sidelink allocation index fields for non-scheduled groups may be configured via RRC signaling. For other devices (e.g., Mode 2 UEs), an indication of whether the SCI format includes the ACK feedback indicator and total sidelink allocation index fields for non-scheduled groups may be pre-configured. In such an example, the counter sidelink allocation index and total sidelink allocation index for scheduled PSSCH groups may be accumulated within the corresponding PSSCH group until the ACK feedback indicator value for the PSSCH group is toggled.

[0189] An example SCI format for an extended Type 2 HARQ-ACK codebook transmission on PSFCH resources may include a group index field, a trigger field, an ACK indicator field for scheduled PSSCH groups, an ACK indicator field for non-scheduled PSSCH groups, a counter sidelink allocation index field, a total sidelink allocation index field for scheduled PSSCH groups, and a total sidelink allocation index field for non-scheduled PSSCH groups. The group index field may include one bit, with "0" indicating that PSSCH group 0 (e.g., the first PSSCH group) is the scheduled PSSCH group and "1" indicating that PSSCH group 1 (e.g., the second PSSCH group) is the scheduled PSSCH group. The trigger field may also include one bit, with "0" indicating that only HARQ-ACK feedback for scheduled groups is reported and "1" indicating that HARQ-ACK feedback for non-scheduled groups is also reported. The ACK indicator field may include one bit for scheduled groups and one bit for non-scheduled groups. The field for non-scheduled groups may be configurable (e.g., via RRC signaling) or pre-configured. The total sidelink allocation index field may contain 2 bits for scheduled groups and 2 bits for non-scheduled groups. The field for non-scheduled groups may be configurable (e.g., via RRC signaling) or pre-configured.

[0190] 8, a first wireless device (e.g., a destination UE) may monitor a PSSCH transmission 810 from a second wireless device (e.g., a source UE) in multiple slots. For example, the first wireless device may monitor PSSCH transmission 810-a, PSSCH transmission 810-b, PSSCH transmission 810-c, PSSCH transmission 810-d, PSSCH transmission 810-e, PSSCH transmission 810-f, and PSSCH transmission 810-g in the first slot (e.g., slot n), second slot (e.g., slot n+1), fourth slot (e.g., slot n+3), fifth slot (e.g., slot n+4), seventh slot (e.g., slot n+6), eighth slot (e.g., slot n+7), and tenth slot (e.g., slot n+9), respectively.

[0191] Each of the PSSCH transmissions 810 may be multiplexed with a respective PSCCH transmission that includes an SCI related to one of the PSSCH transmissions 810. This SCI may indicate a total sidelink allocation index for a scheduled PSSCH group, a total sidelink allocation index for a non-scheduled PSSCH group, a counter sidelink allocation index, an ACK feedback indicator (e.g., "NFI") for a scheduled PSSCH group, an ACK feedback indicator for a non-scheduled PSSCH group, a HARQ-ACK feedback trigger (e.g., "R"), a PSSCH group index, or any combination thereof. In the example of Figure 8, PSSCH transmission 810-a may be associated with a group index of 0, a total sidelink allocation index of 1, a counter sidelink allocation index of 1, an ACK feedback indicator of 0, and a HARQ-ACK feedback trigger value of 0. Similarly, PSSCH transmission 810-b may be associated with a group index of 0, a total sidelink allocation index of 2, a counter sidelink allocation index of 2, an ACK feedback indicator of 0, and a HARQ-ACK feedback trigger value of 0. The PSSCH transmission 810-c may be associated with a group index of 0, a total sidelink allocation index of 3, a counter sidelink allocation index of 3, an ACK feedback indicator of 0, and a HARQ-ACK feedback trigger value of 0.

[0192] PSSCH transmission 810-d may be associated with a group index of 1, a total sidelink allocation index of 1, a counter sidelink allocation index of 1, an ACK feedback indicator of 0, and a HARQ-ACK feedback trigger value of 0. PSSCH transmission 810-e may be associated with a group index of 1, a total sidelink allocation index of 2, a counter sidelink allocation index of 2, an ACK feedback indicator of 0, and a HARQ-ACK feedback trigger value of 0. PSSCH transmission 810-f may be associated with a group index of 1, a first total sidelink allocation index of 3 (e.g., corresponding to a scheduled PSSCH group), a second total sidelink allocation index of 3 (e.g., corresponding to a non-scheduled PSSCH group), a counter sidelink allocation index of 3, a first ACK feedback indicator of 0 (e.g., corresponding to a scheduled PSSCH group), a second ACK feedback indicator of 0 (e.g., corresponding to a non-scheduled PSSCH group), and a HARQ-ACK feedback trigger value of 1. The PSSCH transmission 810-g may be associated with a group index of 0, a total sidelink allocation index of 1, a counter sidelink allocation index of 1, an ACK feedback indicator of 1, and a HARQ-ACK feedback trigger value of 0.

[0193] As described herein, the first wireless device may reset the counter sidelink allocation index and the total sidelink allocation of a PSSCH transmission based on the value of an ACK feedback indicator associated with the PSSCH transmissions in the corresponding PSSCH group, as opposed to resetting the counter sidelink allocation index and the total sidelink allocation of a PSSCH transmission after each PSFCH opportunity. The first wireless device may determine whether to include HARQ-ACK feedback for the scheduled PSSCH group or for both the scheduled and non-scheduled PSSCH groups based on the corresponding HARQ-ACK feedback trigger value and the respective ACK feedback indicator value.

[0194] The first wireless device may generate a codebook 835-a (e.g., a first type-2 HARQ-ACK codebook) that includes ACK or NACK bits 830 corresponding to some of the PSSCH transmissions 810. For example, the codebook 835-a may include an ACK or NACK bit 830-a corresponding to the PSSCH transmission 810-a, an ACK or NACK bit 830-b corresponding to the PSSCH transmission 810-b, and an ACK or NACK bit 830-c corresponding to the PSSCH transmission 810-c. After generating the codebook 835-a, the first wireless device may attempt to transmit an indication of the codebook 835-a on a PSFCH resource 815-b in accordance with a sidelink feedback configuration of the first wireless device. Specifically, the first wireless device may identify suitable PSFCH resources 815 to use for transmissions of the codebook 835-a based on a PSFCH periodicity and a minimum PSFCH gap time configured for the first wireless device. For example, if the first wireless device is configured with a minimum PSFCH gap time of two slots, the first wireless device may not be able to transmit the indication of codebook 835-a on PSFCH resource 815-a because PSFCH resource 815-a is within two slots of when the first wireless device received the PSSCH transmission 810 associated with codebook 835-a. Thus, the first wireless device may determine to transmit the indication of codebook 835-a on PSFCH resource 815-b.

[0195] However, in some examples, the transmission of codebook 835-a may be unsuccessful. Specifically, the first wireless device may be unable to transmit the indication of codebook 835-a on PSFCH resource 815-b, for example, if the first wireless device experiences an LBT failure (e.g., if the first wireless device is communicating with the second wireless device in an unlicensed radio frequency spectrum band, such as an NR unlicensed (NR-U) frequency band). In other examples, the transmission of codebook 835-a may be unsuccessful due to poor channel conditions or interference levels at the second wireless device.

[0196] According to the techniques described herein, the first wireless device may be configured to retransmit ACK or NACK bits 830 from codebook 835-a if an initial transmission of codebook 835-a is unsuccessful. For example, the first wireless device may receive (e.g., via an instance of an SCI associated with PSSCH transmission 810-f) a HARQ-ACK trigger value of 1, which may indicate to report HARQ-ACK feedback for both a scheduled PSSCH group (e.g., group 1) and an unscheduled PSSCH group (e.g., group 0). Based on this indication, the first wireless device may append the ACK or NACK bits 830 from codebook 835-a to codebook 835-b (e.g., a second type-2 HARQ-ACK codebook) and may transmit an indication of codebook 835-b on PSFCH resource 815-c. Codebook 835-b may include a subset 840-a (e.g., a first sub-codebook) corresponding to group index 0 (e.g., an unscheduled PSSCH group) and a subset 840-b (e.g., a second sub-codebook) corresponding to group index 1 (e.g., a scheduled PSSCH group). Subset 840-a may include an ACK or NACK bit 830-a corresponding to PSSCH transmission 810-a, an ACK or NACK bit 830-b corresponding to PSSCH transmission 810-b, and an ACK or NACK bit 830-c corresponding to PSSCH transmission 810-c, and subset 840-b may include an ACK or NACK bit 830-d corresponding to PSSCH transmission 810-d, an ACK or NACK bit 830-e corresponding to PSSCH transmission 810-e, and an ACK or NACK bit 830-f corresponding to PSSCH transmission 810-f.

[0197] Resource mapping 800 may support techniques for improved sidelink feedback transmission at a wireless device. For example, the techniques and operations described with reference to FIG. 8 may enable a wireless device (e.g., a destination UE) to transmit multiple ACK or NACK bits on a single PSFCH resource (e.g., corresponding to multiple PSSCH transmissions from a source UE), as opposed to transmitting a single ACK or NACK bit per PSFCH resource. As a result, the wireless device may experience higher throughput and greater signaling efficiency, among other benefits.

[0198] 9 illustrates an example process flow 900 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. Process flow 900 may implement or be implemented by aspects of wireless communication system 100 or wireless communication system 200. For example, process flow 900 may include UE 115-c (e.g., a first wireless device), UE 115-d (e.g., a second wireless device), and base station 105-b (e.g., a network entity). In the following description of process flow 900, operations between UE 115 and base station 105 may be performed in a different order or at different times than shown. Additionally or alternatively, some operations may also be omitted from process flow 900, and other operations may be added to process flow 900.

[0199] At 905, the base station 105-b may send control signaling (e.g., RRC signaling) to one or both of the UEs 115-c and 115-d. The control signaling may indicate an amount of type-2 HARQ-ACK codebooks to use for sidelink feedback transmission, an amount of PSSCH groups, an amount of PSSCH priority levels, a sidelink priority threshold, or an indication of whether ACK and NACK bits for sidelink messages associated with different priority levels, different group indices, or both should be included in a joint type-2 HARQ-ACK codebook, separate type-2 HARQ-ACK codebooks, or both. The control signaling may also indicate other information, such as a mapping between PSSCH resources and PSFCH resources, a PSFCH resource pool configuration, a minimum PSFCH gap time, a PSFCH resource periodicity, or a combination thereof.

[0200] At 910, the UE 115-d may transmit multiple sidelink messages to the UE 115-c on PSSCH resources. The sidelink messages may include unicast PSSCH transmissions, groupcast PSSCH transmissions, or a combination thereof. The sidelink messages may also include a first set of PSSCH groupcast transmissions and a second set of PSSCH groupcast transmissions. In some examples, the sidelink messages may be multiplexed with the SCI. For example, the UE 115-c may multiplex one or more PSSCH transmissions with one or more corresponding PSCCH transmissions that include the SCI. This SCI (e.g., piggybacked SCI) may indicate one or more of the following: a first total sidelink allocation index for scheduled PSSCH groups, a second total sidelink allocation index for non-scheduled PSSCH groups, a counter sidelink allocation index, a first ACK feedback indicator for scheduled PSSCH groups, a second ACK feedback indicator for non-scheduled PSSCH groups, a PSSCH group index, or a HARQ-ACK trigger field for the respective PSSCH transmission (e.g., sidelink message).

[0201] At 915, the UE 115-c may generate one or more Type-2 HARQ-ACK codebooks to report ACK or NACK bits for sidelink messages from the UE 115-d. The UE 115-c may generate the one or more codebooks according to the sidelink feedback configuration of the UE 115-c. In some examples, the UE 115-c may generate a joint (e.g., mixed) codebook that includes ACK or NACK bits for all of the sidelink messages, even if the sidelink messages are associated with different priority levels or group indices. Alternatively, the UE 115-c may generate separate codebooks that include ACK or NACK bits for sidelink messages associated with specific priority levels or group indices. For example, if a sidelink message includes both unicast and groupcast PSSCH transmissions, the UE 115-c may include ACK or NACK bits for the unicast and groupcast PSSCH transmissions in the same codebook or in different codebooks.

[0202] In some examples, the UE 115-c may concatenate one or more codebooks at 920. For example, if the UE 115-c is configured to include ACK or NACK bits for all sidelink messages in a single Type 2 HARQ-ACK codebook, the UE 115-c may generate sub-codebooks for sidelink messages having different priority levels or group indices and may concatenate the sub-codebooks in ascending or descending order with respect to priority level or group index. The UE 115-c may concatenate the sub-codebooks according to a sidelink feedback configuration of the UE 115-c, which may be pre-configured or specified via RRC signaling.

[0203] At 925, the UE 115-c may send one or more feedback messages to the UE 115-d on one or more PSFCH resources. The one or more feedback messages may indicate ACK or NACK bits corresponding to sidelink messages from the UE 115-d. Specifically, each feedback message may include an indication of a type-2 HARQ codebook. For example, if the UE 115-c is configured to generate a joint type-2 HARQ-ACK codebook that includes ACK or NACK feedback for sidelink messages with different priority levels or group indices, the UE 115-c may send a single feedback message indicating the joint codebook. Alternatively, if UE 115-c is configured to generate separate Type-2 HARQ-ACK codebooks for different priority levels or groups (e.g., unicast PSSCH groups, groupcast PSSCH groups, or both), UE 115-c may send an indication of each Type-2 HARQ-ACK codebook on separate PSFCH resources in accordance with the sidelink feedback configuration of UE 115-c.

[0204] Process flow 900 may support techniques for improved sidelink feedback transmission at UE 115-c. For example, the techniques and operations described with reference to FIG. 9 may enable UE 115-c (e.g., a destination UE) to transmit multiple ACK or NACK bits on a single PSFCH resource (e.g., corresponding to multiple PSSCH transmissions from UE 115-d), as opposed to transmitting a single ACK or NACK bit per PSFCH resource. As a result, UE 115-c may experience higher throughput and greater signaling efficiency, among other benefits.

[0205] 10 shows a block diagram 1000 of a device 1005 supporting techniques for enhanced sidelink feedback transmission according to an aspect of the present disclosure. The device 1005 may be an example of an aspect of a wireless device (e.g., a UE 115) as described herein. The device 1005 may include a receiver 1010, a transmitter 1015, and a communications manager 1020. The device 1005 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0206] The receiver 1010 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various traffic channels (e.g., control channels, data channels, traffic channels related to techniques for enhanced sidelink feedback transmission). The information may be passed to other components of the device 1005. The receiver 1010 may utilize a single antenna or multiple antennas.

[0207] The transmitter 1015 may provide a means for transmitting signals generated by other components of the device 1005. For example, the transmitter 1015 may transmit information such as packets associated with various traffic channels (e.g., control channels, data channels, traffic channels related to techniques for enhanced sidelink feedback transmission), user data, control information, or any combination thereof. In some examples, the transmitter 1015 may be collocated with the receiver 1010 within a transceiver module. The transmitter 1015 may utilize a single antenna or multiple antennas.

[0208] The communications manager 1020, the receiver 1010, the transmitter 1015, or various combinations or components thereof may be examples of means for implementing various aspects of the techniques for enhanced sidelink feedback transmission described herein. For example, the communications manager 1020, the receiver 1010, the transmitter 1015, or various combinations or components thereof may support a method for implementing one or more of the functions described herein.

[0209] In some examples, the communications manager 1020, the receiver 1010, the transmitter 1015, or various combinations or components thereof may be implemented in hardware (e.g., in communications management circuitry). The hardware may include a processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting means for performing the functions described in this disclosure. In some examples, the processor and memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by the processor executing instructions stored in the memory).

[0210] Additionally or alternatively, in some examples, the communications manager 1020, the receiver 1010, the transmitter 1015, or various combinations or components thereof may be implemented in code executed by a processor (e.g., as communications management software or firmware). If implemented in code executed by a processor, the functionality of the communications manager 1020, the receiver 1010, the transmitter 1015, or various combinations or components thereof may be performed by a general-purpose processor, a DSP, a CPU, an ASIC, an FPGA, or any combination of these or other programmable logic devices (e.g., configured as or otherwise supporting a means for performing the functions described in this disclosure).

[0211] In some examples, the communications manager 1020 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the receiver 1010, the transmitter 1015, or both. For example, the communications manager 1020 may receive information from the receiver 1010 and transmit information to the transmitter 1015, or may be integrated in combination with the receiver 1010, the transmitter 1015, or both to receive information, transmit information, or perform various other operations described herein.

[0212] The communications manager 1020 may support wireless communications at a first wireless device (e.g., UE 115) according to examples disclosed herein. For example, the communications manager 1020 may be configured or otherwise support monitoring sidelink resources for sidelink messages from a second wireless device. The communications manager 1020 may be configured or otherwise support generating one or more codebooks including ACK or NACK bits corresponding to the sidelink messages. The communications manager 1020 may be configured or otherwise support transmitting a set of feedback messages including an indication of the one or more codebooks to the second wireless device via a set of feedback resources according to a sidelink feedback configuration of the first wireless device.

[0213] Additionally or alternatively, the communications manager 1020 may support wireless communications at a first wireless device (e.g., UE 115) according to examples disclosed herein. For example, the communications manager 1020 may be configured as or otherwise support transmitting control signaling to a second wireless device indicating a sidelink feedback configuration for the second wireless device. The communications manager 1020 may be configured as or otherwise support transmitting a plurality of sidelink messages to the second wireless device via a plurality of sidelink resources. The communications manager 1020 may be configured as or otherwise support monitoring a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages.

[0214] By including or configuring a communications manager 1020 according to examples described herein, the device 1005 (e.g., a processor controlling or otherwise coupled to the receiver 1010, the transmitter 1015, the communications manager 1020, or a combination thereof) may support techniques for reduced power consumption by performing fewer sidelink feedback transmissions. For example, the techniques described herein may enable the device 1005 to transmit multiple ACK or NACK bits (e.g., for multiple PSSCH transmissions) on a single PSFCH resource, as opposed to transmitting one ACK or NACK bit per PSFCH resource. As a result, the device 1005 may perform fewer transmissions, which may result in greater power savings in the device 1005.

[0215] 11 shows a block diagram 1100 of a device 1105 supporting techniques for enhanced sidelink feedback transmission according to an aspect of the present disclosure. The device 1105 may be an example of an aspect of the device 1005 or a wireless device (e.g., a UE 115) as described herein. The device 1105 may include a receiver 1110, a transmitter 1115, and a communications manager 1120. The device 1105 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0216] The receiver 1110 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various traffic channels (e.g., control channels, data channels, traffic channels related to techniques for enhanced sidelink feedback transmission). The information may be passed to other components of the device 1105. The receiver 1110 may utilize a single antenna or multiple antennas.

[0217] The transmitter 1115 may provide a means for transmitting signals generated by other components of the device 1105. For example, the transmitter 1115 may transmit information such as packets associated with various traffic channels (e.g., control channels, data channels, traffic channels related to techniques for enhanced sidelink feedback transmission), user data, control information, or any combination thereof. In some examples, the transmitter 1115 may be collocated with the receiver 1110 within a transceiver module. The transmitter 1115 may utilize a single antenna or multiple antennas.

[0218] The device 1105, or various components thereof, may be an example of a means for implementing various aspects of the techniques for enhanced sidelink feedback transmission described herein. For example, the communications manager 1120 may include a sidelink monitoring component 1125, a codebook generation component 1130, a feedback transmission component 1135, a control signaling transmitter 1140, a sidelink message transmitter 1145, a feedback monitoring component 1150, or any combination thereof. The communications manager 1120 may be an example of an aspect of the communications manager 1020 as described herein. In some examples, the communications manager 1120 or various components thereof may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the receiver 1110, the transmitter 1115, or both. For example, the communications manager 1120 may receive information from the receiver 1110 and transmit information to the transmitter 1115, or may be integrated in combination with the receiver 1110, the transmitter 1115, or both, to receive information, transmit information, or perform various other operations described herein.

[0219] The communications manager 1120 may support wireless communications at a first wireless device (e.g., UE 115) according to examples disclosed herein. The sidelink monitoring component 1125 may be configured as or otherwise support monitoring sidelink resources for sidelink messages from a second wireless device. The codebook generation component 1130 may be configured as or otherwise support generating one or more codebooks including ACK or NACK bits corresponding to the sidelink messages. The feedback transmission component 1135 may be configured as or otherwise support transmitting a set of feedback messages including an indication of one or more codebooks to the second wireless device via a set of feedback resources according to a sidelink feedback configuration of the first wireless device.

[0220] Additionally or alternatively, the communications manager 1120 may support wireless communications at a first wireless device (e.g., a UE 115) according to examples disclosed herein. The control signaling transmitter 1140 may be configured as or otherwise support a means for transmitting control signaling to a second wireless device indicating a sidelink feedback configuration for the second wireless device. The sidelink message transmitter 1145 may be configured as or otherwise support a means for transmitting a plurality of sidelink messages to the second wireless device via a plurality of sidelink resources. The feedback monitoring component 1150 may be configured as or otherwise support a means for monitoring a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages.

[0221] FIG. 12 shows a block diagram 1200 of a communications manager 1220 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The communications manager 1220 may be an example of aspects of the communications manager 1020, the communications manager 1120, or both described herein. The communications manager 1220, or various components thereof, may be an example of a means for implementing various aspects of the techniques for enhanced sidelink feedback transmission described herein. For example, the communications manager 1220 may include a sidelink monitoring component 1225, a codebook generation component 1230, a feedback transmission component 1235, a control signaling transmitter 1240, a sidelink message transmitter 1245, a feedback monitoring component 1250, a control signaling receiver 1255, an index determination component 1260, a feedback reception component 1265, a concatenation component 1270, or any combination thereof. Each of these components may communicate directly or indirectly with each other (e.g., via one or more buses).

[0222] The communications manager 1220 may support wireless communications at a first wireless device (e.g., UE 115) according to examples disclosed herein. The sidelink monitoring component 1225 may be configured as or otherwise support monitoring sidelink resources for sidelink messages from a second wireless device. The codebook generation component 1230 may be configured as or otherwise support generating one or more codebooks including ACK or NACK bits corresponding to the sidelink messages. The feedback transmission component 1235 may be configured as or otherwise support transmitting a set of feedback messages including an indication of one or more codebooks to the second wireless device via a set of feedback resources according to a sidelink feedback configuration of the first wireless device.

[0223] In some examples, to support generating one or more codebooks, the codebook generation component 1230 may be configured as or otherwise support generating a joint codebook including multiple ACK or NACK bits corresponding to multiple sidelink messages associated with different priority levels, different group indices, or both.

[0224] In some examples, to support generating a joint codebook, the codebook generation component 1230 may be configured or otherwise support generating a first subset of the joint codebook that includes ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, the first subset of sidelink messages being associated with a first priority level. In some examples, to support generating a joint codebook, the codebook generation component 1230 may be configured or otherwise support generating a second subset of the joint codebook that includes ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, the second subset of sidelink messages being associated with a second priority level different from the first priority level.

[0225] In some examples, to support generating a joint codebook, the codebook generation component 1230 may be configured as or otherwise support generating a first subset of the joint codebook that includes ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, the first subset of sidelink messages being associated with a first group index. In some examples, to support generating a joint codebook, the codebook generation component 1230 may be configured as or otherwise support generating a second subset of the joint codebook that includes ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, the second subset of sidelink messages being associated with a second group index.

[0226] In some examples, the first group index corresponds to a set of priority levels below the sidelink priority threshold and the second group index corresponds to a set of priority levels above the sidelink priority threshold.

[0227] In some examples, the concatenation component 1270 may be configured as or otherwise support a means for concatenating different subsets of a joint codebook in ascending or descending order with respect to priority level or group index.

[0228] In some examples, to support transmitting the set of feedback messages, the feedback transmission component 1235 may be configured as or otherwise support transmitting an indication of the joint codebook over the PSFCH resources in accordance with the sidelink feedback configuration.

[0229] In some examples, the sidelink messages are associated with respective priority levels, respective group indices, or both. In some examples, the sidelink feedback configuration indicates a sidelink priority threshold, a first mapping between respective priority levels and one or more codebooks, a second mapping between respective group indices and one or more codebooks, or a combination thereof.

[0230] In some examples, multiple sidelink messages are multiplexed with respective instances of the SCI. In some examples, each respective instance of the SCI includes an indication of a counter sidelink allocation index and a total sidelink allocation index associated with a sidelink message from the multiple sidelink messages. In some examples, the counter sidelink allocation index and the total sidelink allocation index are specific to a priority level, a group index, or both. In some examples, the counter sidelink allocation index and the total sidelink allocation index are applicable to different priority levels, different group indexes, or both.

[0231] In some examples, to support generating one or more codebooks, the codebook generation component 1230 may be configured as or otherwise support generating a first codebook that includes ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, the first subset of sidelink messages being associated with a first priority level. In some examples, to support generating one or more codebooks, the codebook generation component 1230 may be configured as or otherwise support generating a second codebook that includes ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, the second subset of sidelink messages being associated with a second priority level different from the first priority level.

[0232] In some examples, to support generating one or more codebooks, the codebook generation component 1230 may be configured as or otherwise support generating a first codebook that includes ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, the first subset of sidelink messages being associated with a first group index. In some examples, to support generating one or more codebooks, the codebook generation component 1230 may be configured as or otherwise support generating a second codebook that includes ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, the second subset of sidelink messages being associated with a second group index different from the first group index.

[0233] In some examples, to support transmitting the set of feedback messages, the feedback transmission component 1235 may be configured as or may otherwise support transmitting, via a first PSFCH resource, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages associated with a first priority level, a first group index, or both. In some examples, to support transmitting the set of feedback messages, the feedback transmission component 1235 may be configured as or may otherwise support transmitting, via a second PSFCH resource, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages associated with a second priority level, a second group index, or both.

[0234] In some examples, the control signaling receiver 1255 may be configured as or may otherwise support receiving control signaling indicating one or more of: a quantity of one or more codebooks; a quantity of PSSCH groups; a quantity of PSSCH priority levels; a sidelink priority threshold; or an indication of whether ACK or NACK bits for sidelink messages associated with different priority levels, different group indices, or both, should be included in a joint codebook or in separate codebooks, and generating the one or more codebooks is based on the control signaling.

[0235] In some examples, the sidelink messages include unicast PSSCH transmissions. In some examples, the sidelink messages include unicast PSSCH transmissions, groupcast PSSCH transmissions, or both. In some examples, the unicast PSSCH transmissions and the groupcast PSSCH transmissions are associated with separate counter sidelink allocation indices and separate total sidelink allocation indices.

[0236] In some examples, to support generating one or more codebooks, the codebook generation component 1230 may be configured as or otherwise support generating a joint codebook that includes ACK or NACK bits corresponding to unicast PSSCH transmissions and groupcast PSSCH transmissions.

[0237] In some examples, to support generating a joint codebook, codebook generation component 1230 may be configured as or otherwise support generating a first subset of a joint codebook that includes ACK or NACK bits corresponding to unicast PSSCH transmissions. In some examples, to support generating a joint codebook, codebook generation component 1230 may be configured as or otherwise support generating a second subset of a joint codebook that includes ACK or NACK bits corresponding to groupcast PSSCH transmissions, where the first subset of the joint codebook precedes the second subset of the joint codebook.

[0238] In some examples, to support transmitting the set of feedback messages, the feedback transmission component 1235 may be configured as or otherwise support transmitting an indication of a joint codebook on the PSFCH resources in accordance with the sidelink feedback configuration.

[0239] In some examples, to support transmitting the set of feedback messages, the feedback transmission component 1235 may be configured as or otherwise support transmitting, via a first PSFCH resource, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including an ACK or NACK bit corresponding to the unicast PSSCH transmission. In some examples, to support transmitting the set of feedback messages, the feedback transmission component 1235 may be configured as or otherwise support transmitting, via a second PSFCH resource, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including an ACK or NACK bit corresponding to the groupcast PSSCH transmission.

[0240] In some examples, the control signaling receiver 1255 may be configured as or may otherwise support receiving RRC signaling indicating whether ACK or NACK bits for unicast PSSCH transmissions and ACK or NACK bits for groupcast PSSCH transmissions should be included in a single codebook or in different codebooks, and generating the one or more codebooks is based on the RRC signaling.

[0241] In some examples, the control signaling receiver 1255 may be configured as or may otherwise support receiving RRC signaling indicating the sidelink feedback configuration, and transmitting the set of feedback messages to the second wireless device based on the RRC signaling.

[0242] In some examples, the plurality of sidelink messages includes a first set of groupcast PSSCH transmissions associated with a first group identifier and a second set of groupcast PSSCH transmissions associated with a second group identifier.

[0243] In some examples, to support generating one or more codebooks, the codebook generation component 1230 may be configured as or otherwise support generating a joint codebook that includes acknowledgment or NACK bits corresponding to a first set of groupcast PSSCH transmissions and a second set of groupcast PSSCH transmissions.

[0244] In some examples, to support generating a joint codebook, codebook generation component 1230 may be configured as or otherwise support generating a first subset of the joint codebook that includes acknowledgment or NACK bits corresponding to a first set of groupcast PSSCH transmissions. In some examples, to support generating a joint codebook, codebook generation component 1230 may be configured as or otherwise support generating a second subset of the joint codebook that includes acknowledgment or NACK bits corresponding to a second set of groupcast PSSCH transmissions.

[0245] In some examples, the concatenation component 1270 may be configured as or otherwise support concatenating different subsets of the joint codebook in ascending order with respect to the group identifier.

[0246] In some examples, to support generating one or more codebooks, codebook generation component 1230 may be configured as or otherwise support generating a first codebook that includes ACK or NACK bits corresponding to a first set of groupcast PSSCH transmissions. In some examples, to support generating one or more codebooks, codebook generation component 1230 may be configured as or otherwise support generating a second codebook that includes ACK or NACK bits corresponding to a second set of groupcast PSSCH transmissions.

[0247] In some examples, to support transmitting a set of feedback messages, the feedback transmission component 1235 may be configured as or otherwise support transmitting an indication of the first and second codebooks on different PSFCH resources according to a sidelink feedback configuration.

[0248] In some examples, the control signaling receiver 1255 may be configured as or may otherwise support receiving RRC signaling indicating whether the acknowledgment or negative acknowledgment bits for the first set of groupcast PSSCH transmissions and the acknowledgment or negative acknowledgment bits for the second set of groupcast PSSCH transmissions should be included in a single codebook or in different codebooks, and generating the one or more codebooks is based on the RRC signaling.

[0249] In some examples, the feedback transmission component 1235 may be configured as or otherwise support a means for retransmitting a set of feedback messages based on the outcome of the LBT procedure, an unsuccessful initial transmission, or both.

[0250] In some examples, the control signaling receiver 1255 may be configured or otherwise support receiving an SCI indicating an ACK feedback indicator associated with multiple sidelink messages. In some examples, the index determination component 1260 may be configured or otherwise support determining whether one or both of a counter sidelink allocation index or a total sidelink allocation index for a subsequent sidelink message is to be reset based on the value of the ACK feedback indicator.

[0251] In some examples, to support generating one or more codebooks, the codebook generation component 1230 may be configured as or otherwise support generating a codebook that includes ACK or NACK bits corresponding to multiple sidelink messages associated with the same value of the ACK feedback indicator.

[0252] In some examples, the control signaling receiver 1255 may be configured as or may otherwise support receiving an SCI indicating a PSSCH group index, a HARQ-ACK trigger field, or both. In some examples, the index determination component 1260 may be configured as or may otherwise support determining, based on the SCI, whether to report HARQ-ACK feedback for the first PSSCH group, the second PSSCH group, or both.

[0253] In some examples, to support generating one or more codebooks, the codebook generation component 1230 may be configured as or otherwise support generating one or more codebooks including HARQ-ACK feedback for the first PSSCH group and the second PSSCH group based on the value of the HARQ-ACK trigger field, where the one or more codebooks are concatenated in ascending order with respect to the PSSCH group index.

[0254] In some examples, the control signaling receiver 1255 may be configured or otherwise support receiving an SCI indicating a counter sidelink allocation index, a total sidelink allocation index, an ACK feedback indicator, or a combination thereof. In some examples, the index determination component 1260 may be configured or otherwise support determining whether one or both of the total sidelink allocation index or the counter sidelink allocation index for a PSSCH group are to be reset based on the value of the ACK feedback indicator.

[0255] In some examples, the control signaling receiver 1255 may be configured as or may otherwise support receiving an SCI indicating an ACK feedback indicator and a total sidelink allocation index associated with a PSSCH group, and generating the one or more codebooks is based on receiving the SCI.

[0256] In some examples, the control signaling receiver 1255 may be configured as or may otherwise support means for receiving RRC signaling indicating an SCI format comprising a group index field, a HARQ-ACK trigger field, a first acknowledgment feedback indicator field associated with the first physical sidelink shared channel group, a second ACK feedback indicator field associated with the second physical sidelink shared channel group, a counter sidelink allocation index field, a first total sidelink allocation index field associated with the first physical sidelink shared channel group, a second total sidelink allocation index field associated with the second physical sidelink shared channel group, or a combination thereof.

[0257] Additionally or alternatively, the communications manager 1220 may support wireless communications at a first wireless device (e.g., a UE 115) according to examples disclosed herein. The control signaling transmitter 1240 may be configured as or otherwise support a means for transmitting control signaling to a second wireless device indicating a sidelink feedback configuration for the second wireless device. The sidelink message transmitter 1245 may be configured as or otherwise support a means for transmitting a plurality of sidelink messages to the second wireless device via a plurality of sidelink resources. The feedback monitoring component 1250 may be configured as or otherwise support a means for monitoring a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages.

[0258] In some examples, the feedback receiving component 1265 may be configured as or may otherwise support receiving, via the PSFCH resources, from the second wireless device, an indication of a joint codebook including multiple ACK or NACK bits corresponding to multiple sidelink messages associated with different priority levels, different group indices, or both.

[0259] In some examples, the sidelink messages are associated with respective priority levels, respective group indices, or both. In some examples, the sidelink feedback configuration indicates a sidelink priority threshold, a first mapping between respective priority levels and one or more codebooks, a second mapping between respective group indices and one or more codebooks, or a combination thereof.

[0260] In some examples, multiple sidelink messages are multiplexed with respective instances of the SCI. In some examples, each respective instance of the SCI includes an indication of a counter sidelink allocation index and a total sidelink allocation index associated with a sidelink message from the multiple sidelink messages. In some examples, the counter sidelink allocation index and the total sidelink allocation index are specific to a priority level, a group index, or both. In some examples, the counter sidelink allocation index and the total sidelink allocation index are applicable to different priority levels, different group indexes, or both.

[0261] In some examples, the feedback receiving component 1265 may be configured or otherwise support receiving, via a first PSFCH resource, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, the first codebook being associated with a first priority level, a first group index, or both. In some examples, the feedback receiving component 1265 may be configured or otherwise support receiving, via a second PSFCH resource, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, the second codebook being associated with a second priority level, a second group index, or both.

[0262] In some examples, to support transmitting control signaling, the control signaling transmitter 1240 may be configured as or otherwise support means for transmitting RRC signaling indicating one or more codebook quantities, PSSCH group quantities, PSSCH priority levels, sidelink priority thresholds, or combinations thereof.

[0263] In some examples, the sidelink messages include unicast PSSCH transmissions. In some examples, the sidelink messages include unicast PSSCH transmissions, groupcast PSSCH transmissions, or both. In some examples, the unicast PSSCH transmissions and the groupcast PSSCH transmissions are associated with separate counter sidelink allocation indices and separate total sidelink allocation indices. In some examples, the sidelink messages include a first set of groupcast PSSCH transmissions associated with a first group identifier and a second set of groupcast PSSCH transmissions associated with a second group identifier.

[0264] In some examples, the feedback receiving component 1265 may be configured as or otherwise support receiving, via the PSFCH resources, a feedback message indicating a joint codebook including ACK or negative acknowledgement bits corresponding to unicast PSSCH transmissions and ACK or negative acknowledgement bits corresponding to groupcast PSSCH transmissions.

[0265] In some examples, the feedback receiving component 1265 may be configured as or may otherwise support receiving, via a first PSFCH resource, a first feedback message indicating a first codebook that includes ACK or NACK bits corresponding to a unicast PSSCH transmission. In some examples, the feedback receiving component 1265 may be configured as or may otherwise support receiving, via a second PSFCH resource, a second feedback message indicating a second codebook that includes ACK or NACK bits corresponding to a groupcast PSSCH transmission.

[0266] In some examples, to support transmitting control signaling, the control signaling transmitter 1240 may be configured as or otherwise support means for transmitting RRC signaling indicating whether the ACK or NACK bits for unicast PSSCH transmissions and the ACK or NACK bits for groupcast PSSCH transmissions should be included in a single codebook or in different codebooks.

[0267] In some examples, to support transmitting control signaling, the control signaling transmitter 1240 may be configured as or otherwise support means for transmitting RRC signaling indicating whether the acknowledgment or negative acknowledgment bits for the first set of groupcast PSSCH transmissions and the acknowledgment or negative acknowledgment bits for the second set of groupcast PSSCH transmissions should be included in a single codebook or in different codebooks.

[0268] In some examples, feedback receiving component 1265 may be configured as or may otherwise support receiving a first feedback message via a first PSFCH resource indicating a first codebook that includes ACK or NACK bits corresponding to a first set of groupcast PSSCH transmissions. In some examples, feedback receiving component 1265 may be configured as or may otherwise support receiving a second feedback message via a second PSFCH resource indicating a second codebook that includes ACK or NACK bits corresponding to a second set of groupcast PSSCH transmissions.

[0269] In some examples, the feedback receiving component 1265 may be configured as or otherwise support receiving a feedback message indicating a codebook containing ACK or NACK bits corresponding to multiple sidelink messages associated with the same acknowledgement feedback indicator value.

[0270] In some examples, the control signaling transmitter 1240 may be configured as or otherwise support means for transmitting an SCI indicating a PSSCH group index, a HARQ-ACK trigger field, a first ACK feedback indicator associated with the first physical sidelink shared channel group, a second ACK feedback indicator associated with the second physical sidelink shared channel group, a counter sidelink allocation index, a first total sidelink allocation index associated with the first physical sidelink shared channel group, a second total sidelink allocation index associated with the second physical sidelink shared channel group, or a combination thereof.

[0271] In some examples, to support transmitting the control signaling, the control signaling transmitter 1240 may be configured as or may otherwise support means for transmitting RRC signaling indicating an SCI format including a group index field, a HARQ-ACK trigger field, a first acknowledgment feedback indicator field associated with the first physical sidelink shared channel group, a second ACK feedback indicator field associated with the second physical sidelink shared channel group, a counter sidelink allocation index field, a first total sidelink allocation index field associated with the first physical sidelink shared channel group, a second total sidelink allocation index field associated with the second physical sidelink shared channel group, or a combination thereof.

[0272] In some examples, to support transmitting control signaling, the control signaling transmitter 1240 may be configured as or may otherwise support transmitting an SCI indicating a counter sidelink allocation index, a total sidelink allocation index, an ACK feedback indicator, or a combination thereof, where the value of the ACK feedback indicator indicates whether one or both of the total sidelink allocation index or the counter sidelink allocation index are reset for a PSSCH group.

[0273] 13 shows a diagram of a system 1300 including a device 1305 supporting techniques for enhanced sidelink feedback transmission according to aspects of the disclosure. The device 1305 may be an example of or may include components of a device 1005, a device 1105, or a wireless device (e.g., a UE 115) as described herein. The device 1305 may include components for two-way voice and data communication, including components for transmitting and receiving communications, such as a communications manager 1320, an I / O controller 1310, a transceiver 1315, an antenna 1325, memory 1330, code 1335, and a processor 1340. These components may be in electronic communication or otherwise (e.g., operatively, communicatively, functionally, electronically, electrically) coupled via one or more buses (e.g., bus 1345).

[0274] The I / O controller 1310 may manage input and output signals for the device 1305. The I / O controller 1310 may also manage peripheral devices not integrated with the device 1305. In some cases, the I / O controller 1310 may represent a physical connection or port to an external peripheral device. In some cases, the I / O controller 1310 may utilize an operating system such as iOS®, ANDROID®, MS-DOS®, MS-WINDOWS®, OS / 2®, UNIX®, LINUX®, or another known operating system. Additionally or alternatively, the I / O controller 1310 may represent or interact with a modem, keyboard, mouse, touchscreen, or similar device. In some cases, the I / O controller 1310 may be implemented as part of a processor, such as the processor 1340. In some cases, a user may interact with the device 1305 through the I / O controller 1310 or through a hardware component controlled by the I / O controller 1310 .

[0275] In some cases, the device 1305 may include a single antenna 1325. However, in some other cases, the device 1305 may have two or more antennas 1325, which may be capable of simultaneously transmitting or receiving multiple wireless transmissions. The transceiver 1315 may communicate bidirectionally via one or more antennas 1325, a wired link, or a wireless link as described herein. For example, the transceiver 1315 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 1315 may also include a modem for modulating packets and providing the modulated packets to the one or more antennas 1325 for transmission, and for demodulating packets received from the one or more antennas 1325. The transceiver 1315, or the transceiver 1315 and the one or more antennas 1325, may be an example of the transmitter 1015, the transmitter 1115, the receiver 1010, the receiver 1110, or any combination or component thereof described herein.

[0276] Memory 1330 may include random access memory (RAM) and read-only memory (ROM). Memory 1330 may store computer-readable computer-executable code 1335, which includes instructions that, when executed by processor 1340, cause device 1305 to perform various functions described herein. Code 1335 may be stored on a non-transitory computer-readable medium, such as system memory or another type of memory. In some cases, code 1335 may not be directly executable by processor 1340, but may (e.g., when compiled and executed) cause a computer to perform functions described herein. In some cases, memory 1330 may include a basic I / O system (BIOS), which may control basic hardware or software operations, such as interaction with peripheral components or devices, among other things.

[0277] The processor 1340 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 1340 may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated with the processor 1340. The processor 1340 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1330) to cause the device 1305 to perform various functions (e.g., functions or tasks supporting techniques for enhanced sidelink feedback transmission). For example, the device 1305 or a component of the device 1305 may include the processor 1340 and the memory 1330 coupled to or associated with the processor 1340, where the processor 1340 and the memory 1330 are configured to perform various functions described herein.

[0278] The communications manager 1320 may support wireless communications at a first wireless device (e.g., UE 115) according to examples disclosed herein. For example, the communications manager 1320 may be configured or otherwise support monitoring sidelink resources for sidelink messages from a second wireless device. The communications manager 1320 may be configured or otherwise support generating one or more codebooks including ACK or NACK bits corresponding to the sidelink messages. The communications manager 1320 may be configured or otherwise support transmitting a set of feedback messages including an indication of the one or more codebooks to the second wireless device via a set of feedback resources according to a sidelink feedback configuration of the first wireless device.

[0279] Additionally or alternatively, the communications manager 1320 may support wireless communications at a first wireless device (e.g., the UE 115) according to examples disclosed herein. For example, the communications manager 1320 may be configured as or otherwise support a means for transmitting control signaling to a second wireless device indicating a sidelink feedback configuration for the second wireless device. The communications manager 1320 may be configured as or otherwise support a means for transmitting a plurality of sidelink messages to the second wireless device via a plurality of sidelink resources. The communications manager 1320 may be configured as or otherwise support a means for monitoring a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages.

[0280] By including or configuring a communications manager 1320 according to examples described herein, the device 1305 may support techniques for higher throughput and greater signaling efficiency by transmitting multiple ACK or NACK bits (e.g., for multiple PSSCH transmissions) on a single PSFCH resource. For example, the device 1305 may generate one or more codebooks (e.g., a Type 2 HARQ-ACK codebook) that include multiple ACK or NACK bits. The device 1305 may transmit an indication of the one or more codebooks on one or more PSFCH resources. Transmitting multiple ACK or NACK bits per PSFCH resource may enable the device 1305 to achieve higher throughput levels and greater signaling efficiency (e.g., by reducing the number of transmissions from the device 1305), among other benefits.

[0281] In some examples, the communications manager 1320 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise cooperating with the transceiver 1315, one or more antennas 1325, or any combination thereof. Although the communications manager 1320 is shown as a separate component, in some examples, one or more functions described with reference to the communications manager 1320 may be supported or implemented by the processor 1340, the memory 1330, the code 1335, or any combination thereof. For example, the code 1335 may include instructions executable by the processor 1340 to cause the device 1305 to perform various aspects of the techniques for enhanced sidelink feedback transmission described herein, or the processor 1340 and the memory 1330 may be otherwise configured to perform or support such operations.

[0282] FIG. 14 shows a flowchart illustrating a method 1400 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The operations of method 1400 may be implemented by a wireless device or components thereof described herein. For example, the operations of method 1400 may be performed by the UE 115 described with reference to FIGS. 1-13. In some examples, the wireless device may execute a set of instructions to control functional elements of the wireless device to perform the described functionality. Additionally or alternatively, the wireless device may implement aspects of the described functionality using dedicated hardware.

[0283] At 1405, the method may include monitoring a plurality of sidelink resources for a plurality of sidelink messages from the second wireless device. The operations of 1405 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1405 may be performed by the sidelink monitoring component 1225, as described with reference to FIG. 12.

[0284] At 1410, the method may include generating one or more codebooks including a plurality of ACK or NACK bits corresponding to a plurality of sidelink messages. The operations of 1410 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1410 may be performed by the codebook generation component 1230, as described with reference to FIG. 12.

[0285] At 1415, the method may include transmitting a set of feedback messages to the second wireless device over the set of feedback resources in accordance with the sidelink feedback configuration of the first wireless device, the set of feedback messages including an indication of the one or more codebooks. The operations of 1415 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1415 may be performed by the feedback transmission component 1235, as described with reference to FIG. 12.

[0286] FIG. 15 shows a flowchart illustrating a method 1500 supporting techniques for enhanced sidelink feedback transmission according to aspects of the present disclosure. The operations of method 1500 may be implemented by a wireless device or components thereof described herein. For example, the operations of method 1500 may be performed by a wireless device described with reference to FIGS. 1-13. In some examples, the wireless device may execute a set of instructions to control functional elements of the wireless device to perform the described functionality. Additionally or alternatively, the wireless device may implement aspects of the described functionality using dedicated hardware.

[0287] At 1505, the method may include monitoring a plurality of sidelink resources for a plurality of sidelink messages from the second wireless device. The operations of 1505 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1505 may be performed by the sidelink monitoring component 1225, as described with reference to FIG. 12.

[0288] At 1510, the method may include generating a joint codebook including multiple ACK or NACK bits corresponding to multiple sidelink messages associated with different priority levels, different group indices, or both. The operations of 1510 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1510 may be performed by the codebook generation component 1230, as described with reference to FIG. 12.

[0289] At 1515, the method may include transmitting a set of feedback messages to the second wireless device over the set of feedback resources in accordance with the sidelink feedback configuration of the first wireless device, the feedback messages including the indication of the joint codebook. The operations of 1515 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1515 may be performed by the feedback transmission component 1235, as described with reference to FIG. 12.

[0290] FIG. 16 shows a flowchart illustrating a method 1600 supporting techniques for enhanced sidelink feedback transmission according to an aspect of the present disclosure. The operations of method 1600 may be implemented by a wireless device or components thereof described herein. For example, the operations of method 1600 may be performed by a wireless device described with reference to FIGS. 1-13. In some examples, the wireless device may execute a set of instructions to control functional elements of the wireless device to perform the described functionality. Additionally or alternatively, the wireless device may implement aspects of the described functionality using dedicated hardware.

[0291] At 1605, the method may include transmitting, to the second wireless device, control signaling indicating a sidelink feedback configuration for the second wireless device. The operations of 1605 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1605 may be performed by the control signaling transmitter 1240, as described with reference to FIG. 12.

[0292] At 1610, the method may include transmitting a plurality of sidelink messages to the second wireless device via a plurality of sidelink resources. The operations of 1610 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1610 may be performed by the sidelink message transmitter 1245, as described with reference to FIG. 12.

[0293] At 1615, the method may include monitoring a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages. The operations of 1615 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1615 may be performed by a feedback monitoring component 1250, as described with reference to FIG. 12.

[0294] FIG. 17 shows a flowchart illustrating a method 1700 supporting techniques for enhanced sidelink feedback transmission according to an aspect of the present disclosure. The operations of method 1700 may be implemented by a wireless device or components thereof described herein. For example, the operations of method 1700 may be performed by a wireless device described with reference to FIGS. 1-13. In some examples, the wireless device may execute a set of instructions to control functional elements of the wireless device to perform the described functionality. Additionally or alternatively, the wireless device may implement aspects of the described functionality using dedicated hardware.

[0295] At 1705, the method may include transmitting, to the second wireless device, control signaling indicating a sidelink feedback configuration for the second wireless device. The operations of 1705 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1705 may be performed by the control signaling transmitter 1240, as described with reference to FIG. 12.

[0296] At 1710, the method may include transmitting a plurality of sidelink messages to the second wireless device via a plurality of sidelink resources. The operations of 1710 may be performed in accordance with examples disclosed herein. In some examples, aspects of the operations of 1710 may be performed by the sidelink message transmitter 1245, as described with reference to FIG. 12.

[0297] At 1715, the method may include monitoring a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of ACK or NACK bits corresponding to the plurality of sidelink messages. The operations of 1715 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1715 may be performed by a feedback monitoring component 1250, as described with reference to FIG. 12.

[0298] At 1720, the method may include receiving, via a first PSFCH resource, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including ACK or NACK bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages associated with a first priority level, a first group index, or both. The operations of 1720 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1720 may be performed by a feedback receiving component 1265, as described with reference to FIG. 12.

[0299] At 1725, the method may include receiving, via a second PSFCH resource, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including ACK or NACK bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages associated with a second priority level, a second group index, or both. The operations of 1725 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1725 may be performed by the feedback receiving component 1265, as described with reference to FIG. 12.

[0300] The following provides a summary of aspects of the present disclosure. Aspect 1: A method for wireless communication in a first wireless device, the method comprising: monitoring a plurality of sidelink resources for a plurality of sidelink messages from a second wireless device; generating one or more codebooks comprising a plurality of acknowledgment or negative acknowledgment bits corresponding to the plurality of sidelink messages; and transmitting a set of feedback messages to the second wireless device over the set of feedback resources in accordance with a sidelink feedback configuration of the first wireless device, the set of feedback messages comprising an indication of the one or more codebooks.

[0301] Aspect 2: The method of aspect 1, wherein generating one or more codebooks includes generating a joint codebook including multiple acknowledgment or negative acknowledgment bits corresponding to multiple sidelink messages associated with different priority levels, different group indices, or both.

[0302] Aspect 3: The method of aspect 2, wherein generating the joint codebook comprises: generating a first subset of the joint codebook comprising acknowledgment or negative acknowledgement bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, where the first subset of sidelink messages is associated with a first priority level; and generating a second subset of the joint codebook comprising acknowledgment or negative acknowledgement bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, where the second subset of sidelink messages is associated with a second priority level different from the first priority level.

[0303] Aspect 4: The method of aspect 2 or 3, wherein generating the joint codebook comprises: generating a first subset of the joint codebook comprising acknowledgment or negative acknowledgement bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, where the first subset of sidelink messages is associated with a first group index; and generating a second subset of the joint codebook comprising acknowledgment or negative acknowledgement bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, where the second subset of sidelink messages is associated with a second group index.

[0304] Aspect 5: The method of aspect 4, wherein the first group index corresponds to a set of priority levels below a sidelink priority threshold and the second group index corresponds to a set of priority levels above a sidelink priority threshold.

[0305] Aspect 6: The method of any of aspects 2 to 5, further comprising concatenating different subsets of the joint codebook in ascending or descending order with respect to priority level or group index.

[0306] Aspect 7: The method of any of aspects 2-6, wherein transmitting the set of feedback messages includes transmitting an indication of the joint codebook over physical sidelink feedback channel resources in accordance with the sidelink feedback configuration.

[0307] Aspect 8: The method of any of aspects 1-7, wherein the plurality of sidelink messages are associated with a respective plurality of priority levels, a respective plurality of group indices, or both, and the sidelink feedback configuration indicates a sidelink priority threshold, a first mapping between the respective plurality of priority levels and one or more codebooks, a second mapping between the respective plurality of group indices and one or more codebooks, or a combination thereof.

[0308] Aspect 9: The method of any of aspects 1 to 8, wherein multiple sidelink messages are multiplexed with respective instances of sidelink control information.

[0309] Aspect 10: The method of aspect 9, wherein each respective instance of the sidelink control information includes an indication of a counter sidelink allocation index and an aggregate sidelink allocation index associated with a sidelink message from the plurality of sidelink messages.

[0310] Aspect 11: The method of aspect 10, wherein the counter sidelink allocation index and the total sidelink allocation index are specific to a priority level, a group index, or both.

[0311] Aspect 12: The method of aspect 10, wherein the counter sidelink allocation index and the total sidelink allocation index are applicable to different priority levels, different group indices, or both.

[0312] Aspect 13: The method of any of aspects 8-12, wherein generating the one or more codebooks comprises: generating a first codebook comprising acknowledgment or negative acknowledgement bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, where the first subset of sidelink messages is associated with a first priority level; and generating a second codebook comprising acknowledgment or negative acknowledgement bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, where the second subset of sidelink messages is associated with a second priority level different from the first priority level.

[0313] Aspect 14: The method of any of aspects 8 to 13, wherein generating the one or more codebooks comprises: generating a first codebook comprising acknowledgment or negative acknowledgement bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, where the first subset of sidelink messages is associated with a first group index; and generating a second codebook comprising acknowledgment or negative acknowledgement bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, where the second subset of sidelink messages is associated with a second group index different from the first group index.

[0314] Aspect 15: The method of any of aspects 8-14, wherein transmitting the set of feedback messages comprises: transmitting, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including acknowledgment or negative acknowledgment bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, the first codebook being associated with a first priority level, a first group index, or both; and transmitting, via second physical sidelink feedback channel resources, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including acknowledgment or negative acknowledgment bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, the second codebook being associated with a second priority level, a second group index, or both.

[0315] Aspect 16: The method of any of aspects 1-15, further comprising receiving control signaling indicating one or more of a quantity of one or more codebooks, a quantity of physical sidelink shared channel groups, a quantity of physical sidelink shared channel priority levels, a sidelink priority threshold, or an indication of whether acknowledgment or non-acknowledgment bits for sidelink messages associated with different priority levels, different group indices, or both, should be included in a joint codebook or in separate codebooks, and wherein generating the one or more codebooks is based at least in part on the control signaling.

[0316] Example 17: The method of any of Examples 1-16, wherein the plurality of sidelink messages includes a unicast physical sidelink shared channel transmission.

[0317] Example 18: The method of any of Examples 1 to 17, wherein the plurality of sidelink messages includes unicast physical sidelink shared channel transmissions, groupcast physical sidelink shared channel transmissions, or both.

[0318] Aspect 19: The method of aspect 18, wherein unicast physical sidelink shared channel transmissions and groupcast physical sidelink shared channel transmissions are associated with separate counter sidelink allocation indices and separate total sidelink allocation indices.

[0319] Aspect 20: The method of aspect 18 or 19, wherein generating one or more codebooks includes generating a joint codebook including acknowledgement or negative acknowledgement bits corresponding to unicast and group-cast physical sidelink shared channel transmissions.

[0320] Aspect 21: The method of aspect 20, wherein generating the joint codebook includes: generating a first subset of the joint codebook including acknowledgement or negative acknowledgement bits corresponding to unicast physical sidelink shared channel transmissions; and generating a second subset of the joint codebook including acknowledgement or negative acknowledgement bits corresponding to groupcast physical sidelink shared channel transmissions, wherein the first subset of the joint codebook precedes the second subset of the joint codebook.

[0321]

[0071] Aspect 22: The method of aspect 20 or 21, wherein transmitting the set of feedback messages includes transmitting an indication of the joint codebook on physical sidelink feedback channel resources in accordance with the sidelink feedback configuration.

[0322] Aspect 23: The method of aspect 18 or 19, wherein transmitting the set of feedback messages comprises: transmitting, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including an acknowledgment or negative acknowledgment bit corresponding to a unicast physical sidelink shared channel transmission; and transmitting, via second physical sidelink feedback channel resources, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including an acknowledgment or negative acknowledgment bit corresponding to a groupcast physical sidelink shared channel transmission.

[0323] Aspect 24: The method of any of aspects 18 to 23, further comprising receiving radio resource control signaling indicating whether acknowledgment or negative acknowledgment bits for unicast physical sidelink shared channel transmissions and acknowledgment or negative acknowledgment bits for groupcast physical sidelink shared channel transmissions should be included in a single codebook or in different codebooks, and wherein generating the one or more codebooks is based at least in part on the radio resource control signaling.

[0324] Aspect 25: The method of any of aspects 1-24, further comprising receiving radio resource control signaling indicating a sidelink feedback configuration, wherein transmitting the set of feedback messages to the second wireless device is based at least in part on the radio resource control signaling.

[0325] Aspect 26: The method of any of aspects 1-25, wherein the plurality of sidelink messages includes a first set of groupcast physical sidelink shared channel transmissions associated with a first group identifier and a second set of groupcast physical sidelink shared channel transmissions associated with a second group identifier.

[0326] Aspect 27: The method of aspect 26, wherein generating one or more codebooks includes generating a joint codebook including acknowledgement or negative acknowledgement bits corresponding to a first set of groupcast physical sidelink shared channel transmissions and a second set of groupcast physical sidelink shared channel transmissions.

[0327] Aspect 28: The method of aspect 27, wherein generating the joint codebook includes: generating a first subset of the joint codebook including acknowledgement or negative acknowledgement bits corresponding to a first set of groupcast physical sidelink shared channel transmissions; and generating a second subset of the joint codebook including acknowledgement or negative acknowledgement bits corresponding to a second set of groupcast physical sidelink shared channel transmissions.

[0328]

[0071] Example 29: The method of example 27 or 28, further comprising concatenating the different subsets of the joint codebook in ascending order with respect to the group identifier.

[0329] Aspect 30: The method of aspect 26, wherein generating one or more codebooks comprises: generating a first codebook including acknowledgement or negative acknowledgement bits corresponding to a first set of groupcast physical sidelink shared channel transmissions; and generating a second codebook including acknowledgement or negative acknowledgement bits corresponding to a second set of groupcast physical sidelink shared channel transmissions.

[0330] Aspect 31: The method of aspect 30, wherein transmitting the set of feedback messages includes transmitting an indication of the first codebook and the second codebook on different physical sidelink feedback channel resources in accordance with the sidelink feedback configuration.

[0331] Aspect 32: The method of any of aspects 26 to 31, further comprising receiving radio resource control signaling indicating whether acknowledgment or negative acknowledgment bits for the first set of groupcast physical sidelink shared channel transmissions and acknowledgment or negative acknowledgment bits for the second set of groupcast physical sidelink shared channel transmissions should be included in a single codebook or in different codebooks, and wherein generating the one or more codebooks is based at least in part on the radio resource control signaling.

[0332] Aspect 33: The method of any of aspects 1-32, further comprising retransmitting the set of feedback messages based at least in part on an outcome of the listen-before-talk procedure, an unsuccessful initial transmission, or both.

[0333] Aspect 34: The method of any of aspects 1 to 33, further comprising: receiving sidelink control information indicating acknowledgement feedback indicators associated with a plurality of sidelink messages; and determining whether to reset one or both of a counter sidelink allocation index or a total sidelink allocation index for subsequent sidelink messages based at least in part on values ​​of the acknowledgement feedback indicators.

[0334]

[0071] Aspect 35: The method of aspect 34, wherein generating one or more codebooks includes generating a codebook including acknowledgement or negative acknowledgement bits corresponding to multiple sidelink messages associated with the same value of the acknowledgement feedback indicator.

[0335] Aspect 36: The method of any of aspects 1-35, further comprising: receiving sidelink control information indicating a physical sidelink shared channel group index, a hybrid automatic repeat request acknowledgment trigger field, or both; and determining whether to report hybrid automatic repeat request acknowledgment feedback for the first physical sidelink shared channel group, the second physical sidelink shared channel group, or both based at least in part on the sidelink control information.

[0336] Aspect 37: The method of aspect 36, wherein generating one or more codebooks comprises generating one or more codebooks containing hybrid automatic repeat request acknowledgment feedback for the first physical sidelink shared channel group and the second physical sidelink shared channel group based at least in part on values ​​of a hybrid automatic repeat request acknowledgment trigger field, wherein the one or more codebooks are concatenated in ascending order with respect to physical sidelink shared channel group index.

[0337] Aspect 38: The method of any of aspects 1 to 37, further comprising receiving sidelink control information indicating a counter sidelink allocation index, a first total sidelink allocation index associated with a first physical sidelink shared channel group, a first acknowledgment feedback indicator associated with the first physical sidelink shared channel group, or a combination thereof; and determining whether to reset one or both of the first total sidelink allocation index or the counter sidelink allocation index for the first physical sidelink shared channel group based at least in part on the value of the first acknowledgment feedback indicator.

[0338] Aspect 39: The method of aspect 38, further comprising receiving sidelink control information indicating a second acknowledgment feedback indicator and a second total sidelink allocation index associated with a second physical sidelink shared channel group, wherein generating the one or more codebooks is based at least in part on receiving the sidelink control information.

[0339] Aspect 40: The method of any of aspects 1-39, further comprising receiving radio resource control signaling indicating a sidelink control information format comprising a group index field, a hybrid automatic repeat request (HAR) acknowledgment trigger field, a first acknowledgment feedback indicator field associated with the first physical sidelink shared channel group, a second acknowledgment feedback indicator field associated with the second physical sidelink shared channel group, a counter sidelink allocation index field, a first total sidelink allocations index field associated with the first physical sidelink shared channel group, a second total sidelink allocations index field associated with the second physical sidelink shared channel group, or a combination thereof.

[0340] Aspect 41: A method for wireless communication in a first wireless device, comprising: transmitting, to a second wireless device, control signaling indicating a sidelink feedback configuration for the second wireless device; transmitting a plurality of sidelink messages to the second wireless device over a plurality of sidelink resources; and monitoring a set of feedback resources for a set of feedback messages from the second wireless device according to the sidelink feedback configuration, wherein the set of feedback messages comprises an indication of one or more codebooks generated by the second wireless device, the one or more codebooks comprising a plurality of acknowledgment or negative acknowledgment bits corresponding to the plurality of sidelink messages.

[0341]

[0071] Aspect 42: The method of aspect 41, further comprising receiving, from the second wireless device, via physical sidelink feedback channel resources, an indication of a joint codebook including multiple acknowledgment or non-acknowledgment bits corresponding to multiple sidelink messages associated with different priority levels, different group indices, or both.

[0342] Aspect 43: The method of aspect 41 or 42, wherein the plurality of sidelink messages are associated with a respective plurality of priority levels, a respective plurality of group indices, or both, and the sidelink feedback configuration indicates a sidelink priority threshold, a first mapping between the respective plurality of priority levels and one or more codebooks, a second mapping between the respective plurality of group indices and one or more codebooks, or a combination thereof.

[0343] Aspect 44: The method of any of aspects 41 to 43, wherein multiple sidelink messages are multiplexed with respective instances of sidelink control information.

[0344]

[0081] Aspect 45: The method of aspect 44, wherein each respective instance of the sidelink control information includes an indication of a counter sidelink allocation index and an aggregate sidelink allocation index associated with a sidelink message from the plurality of sidelink messages.

[0345] Aspect 46: The method of aspect 45, wherein the counter sidelink allocation index and the total sidelink allocation index are specific to a priority level, a group index, or both.

[0346] Aspect 47: The method of aspect 45, wherein the counter sidelink allocation index and the total sidelink allocation index are applicable to different priority levels, different group indices, or both.

[0347] Aspect 48: The method of any of aspects 43 to 47, further comprising: receiving, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including acknowledgement or negative acknowledgement bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, the first codebook being associated with a first priority level, a first group index, or both; and receiving, via second physical sidelink feedback channel resources, a second codebook of the one or more codebooks, the second codebook including acknowledgement or negative acknowledgement bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, the second codebook being associated with a second priority level, a second group index, or both.

[0348] Example 49: The method of any of Examples 41 to 48, wherein transmitting the control signaling includes transmitting radio resource control signaling indicating a quantity of one or more codebooks, a quantity of physical sidelink shared channel groups, a quantity of physical sidelink shared channel priority levels, a sidelink priority threshold, or a combination thereof.

[0349]

[0071] Aspect 50: The method of any of aspects 41 to 49, wherein the plurality of sidelink messages comprises a unicast physical sidelink shared channel transmission.

[0350] Aspect 51: The method of any of aspects 41 to 50, wherein the plurality of sidelink messages includes unicast physical sidelink shared channel transmissions, groupcast physical sidelink shared channel transmissions, or both.

[0351] Aspect 52: The method of aspect 51, wherein unicast physical sidelink shared channel transmissions and groupcast physical sidelink shared channel transmissions are associated with separate counter sidelink allocation indices and separate total sidelink allocation indices.

[0352]

[0071] Aspect 53: The method of aspect 51 or 52, further comprising receiving, via physical sidelink feedback channel resources, a feedback message indicating a joint codebook including acknowledgement or negative acknowledgement bits corresponding to unicast physical sidelink shared channel transmissions and acknowledgement or negative acknowledgement bits corresponding to groupcast physical sidelink shared channel transmissions.

[0353] Aspect 54: The method of aspect 51 or 52, further comprising: receiving, via the first physical sidelink feedback channel resource, a first feedback message indicating a first codebook, the first codebook including acknowledgement or negative acknowledgement bits corresponding to unicast physical sidelink shared channel transmissions; and receiving, via the second physical sidelink feedback channel resource, a second feedback message indicating a second codebook, the second codebook including acknowledgement or negative acknowledgement bits corresponding to groupcast physical sidelink shared channel transmissions.

[0354] Example 55: The method of any of Examples 51 to 54, wherein transmitting the control signaling includes transmitting radio resource control signaling indicating whether an acknowledgment or negative acknowledgment bit for a unicast physical sidelink shared channel transmission and an acknowledgment or negative acknowledgment bit for a groupcast physical sidelink shared channel transmission should be included in a single codebook or in different codebooks.

[0355] Aspect 56: The method of any of aspects 41-55, wherein the plurality of sidelink messages includes a first set of groupcast physical sidelink shared channel transmissions associated with a first group identifier and a second set of groupcast physical sidelink shared channel transmissions associated with a second group identifier.

[0356] Aspect 57: The method of aspect 56, wherein transmitting the control signaling includes transmitting radio resource control signaling indicating whether an acknowledgment or negative acknowledgment bit for the first set of groupcast physical sidelink shared channel transmissions and an acknowledgment or negative acknowledgment bit for the second set of groupcast physical sidelink shared channel transmissions should be included in a single codebook or in different codebooks.

[0357] Aspect 58: The method of any of aspects 55 to 57, further comprising: receiving, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook, the first codebook including acknowledgement or negative acknowledgement bits corresponding to a first set of groupcast physical sidelink shared channel transmissions; and receiving, via second physical sidelink feedback channel resources, a second feedback message indicating a second codebook, the second codebook including acknowledgement or negative acknowledgement bits corresponding to a second set of groupcast physical sidelink shared channel transmissions.

[0358]

[0047] Aspect 59: The method of any of aspects 55 to 57, further comprising receiving a feedback message indicating a codebook including acknowledgement or negative acknowledgement bits corresponding to multiple sidelink messages associated with the same acknowledgement feedback indicator value.

[0359] Aspect 60: The method of any of aspects 41 to 59, further comprising transmitting sidelink control information indicating a physical sidelink shared channel group index, a hybrid automatic repeat request (HAR) acknowledgment trigger field, a first acknowledgment feedback indicator associated with the first physical sidelink shared channel group, a second acknowledgment feedback indicator associated with the second physical sidelink shared channel group, a counter sidelink allocation index, a first total sidelink allocation index associated with the first physical sidelink shared channel group, a second total sidelink allocation index associated with the second physical sidelink shared channel group, or a combination thereof.

[0360] Aspect 61: The method of any of aspects 41-60, wherein transmitting the control signaling includes transmitting radio resource control signaling indicating a sidelink control information format including a group index field, a hybrid automatic repeat request (HAR) acknowledgment trigger field, a first acknowledgment feedback indicator field associated with the first physical sidelink shared channel group, a second acknowledgment feedback indicator field associated with the second physical sidelink shared channel group, a counter sidelink allocation index field, a first total sidelink allocation index field associated with the first physical sidelink shared channel group, a second total sidelink allocation index field associated with the second physical sidelink shared channel group, or a combination thereof.

[0361] Aspect 62: The method of any of aspects 41 to 61, wherein transmitting the control signaling comprises transmitting sidelink control information indicating a counter sidelink allocation index, a total sidelink allocation index, an acknowledgment feedback indicator, or a combination thereof, wherein a value of the acknowledgment feedback indicator indicates whether one or both of the total sidelink allocation index or the counter sidelink allocation index are reset for the physical sidelink shared channel group.

[0362] Aspect 63: An apparatus for wireless communication in a first wireless device, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform any of the methods of aspects 1 to 40.

[0363] Aspect 64: An apparatus for wireless communication in a first wireless device, the apparatus comprising at least one means for implementing the method of any of aspects 1-40.

[0364] Aspect 65: A non-transitory computer-readable medium storing code for wireless communication in a first wireless device, the code including instructions executable by a processor to perform any of the methods of aspects 1 to 40.

[0365] Aspect 66: An apparatus for wireless communication in a first wireless device, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform any of the methods of aspects 41 to 62.

[0366] Aspect 67: An apparatus for wireless communication in a first wireless device, comprising at least one means for implementing the method of any of aspects 41 to 62.

[0367] Aspect 68: A non-transitory computer-readable medium storing code for wireless communication in a first wireless device, the code including instructions executable by a processor to perform any of the methods of aspects 41 to 62.

[0368] It should be noted that the methods described herein describe possible implementations, that the operations and steps may be rearranged or otherwise modified, and that other implementations are possible. Furthermore, aspects from two or more of the methods may be combined.

[0369] Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described as examples, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used throughout much of the description, the techniques described herein may be applicable to networks other than LTE, LTE-A, LTE-A Pro, or NR. For example, the described techniques may be applicable to various other wireless communication systems, such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0370] The information and signals described herein may be represented using any of a wide variety of technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0371] The various example blocks and components described in connection with the disclosure herein may be implemented or performed using a general purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but alternatively, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0372] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. Features implementing the functions may also be physically located in various locations, including being distributed such that portions of the functions are implemented in different physical locations.

[0373] Computer-readable media includes both non-transitory computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. Non-transitory storage media may be any available medium that can be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included within the definition of computer-readable media. As used herein, disk and disc include CDs, laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and discs reproduce data optically using lasers. Combinations of the above are also included within the scope of computer-readable media.

[0374] As used herein, including in the claims, "or" as used in a list of items (e.g., a list of items followed by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such as, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, the phrase "based on" as used herein should not be construed as referring to a closed set of conditions. For example, an exemplary step described as "based on condition A" may be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" is to be interpreted the same as the phrase "based at least in part on."

[0375] The terms "determine" or "determining" encompass a wide variety of actions, and thus "determining" can include calculating, computing, processing, deriving, investigating, looking up (such as via a lookup in a table, database, or another data structure), ascertaining, etc. "Determining" can also include receiving (such as receiving information), accessing (such as accessing data in a memory), etc. "Determining" can also include resolving, selecting, choosing, establishing, and other similar acts.

[0376] In the accompanying figures, similar components or features may have the same reference label. Furthermore, various components of the same type may be distinguished by following the reference label with a dash and a second label that distinguishes between the similar components. If only a first reference label is used herein, the description is applicable to any of the similar components having the same first reference label, regardless of a second reference label, or other subsequent reference label.

[0377] The descriptions set forth herein with reference to the accompanying drawings describe exemplary configurations and do not necessarily represent all examples that may be implemented or fall within the scope of the claims. As used herein, the term "example" means "serving as an example, instance, or illustration" and does not mean "preferred" or "advantageous over other examples." The detailed description includes specific details for the purpose of providing an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0378] The description herein is provided to enable any person skilled in the art to make or use the disclosure. Various modifications of the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 1. A method for wireless communication in a first wireless device, comprising: monitoring a plurality of sidelink resources for a plurality of sidelink messages from a second wireless device; generating one or more codebooks comprising a plurality of acknowledgment or negative acknowledgement bits corresponding to the plurality of sidelink messages, the plurality of sidelink messages being associated with different group indices; and transmitting a set of feedback messages to the second wireless device over a set of feedback resources in accordance with a sidelink feedback configuration of the first wireless device, the set of feedback messages including an indication of the one or more codebooks.

2. generating the one or more codebooks generating a joint codebook comprising the plurality of acknowledgment or negative acknowledgment bits corresponding to the plurality of sidelink messages associated with the different group indices; the method further comprising concatenating different subsets of the joint codebook in ascending or descending order with respect to group index; or transmitting the set of feedback messages transmitting an indication of the joint codebook over physical sidelink feedback channel resources in accordance with the sidelink feedback configuration; or generating the joint codebook, generating a first subset of the joint codebook comprising acknowledgment or negative acknowledgement bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, the first subset of sidelink messages being associated with a first group index; and generating a second subset of the joint codebook comprising acknowledgment or negative acknowledgement bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, the second subset of sidelink messages being associated with a second group index; 2. The method of claim 1, wherein the first group index corresponds to a set of priority levels below a sidelink priority threshold and the second group index corresponds to a set of priority levels above the sidelink priority threshold.

3. the sidelink feedback configuration indicates a sidelink priority threshold, a mapping between respective group indices and the one or more codebooks, or a combination thereof; or the plurality of sidelink messages comprises unicast physical sidelink shared channel transmissions; or the plurality of sidelink messages are multiplexed with respective instances of sidelink control information; each respective instance of sidelink control information comprising an indication of a counter sidelink allocation index and an aggregate sidelink allocation index associated with a sidelink message from the plurality of sidelink messages; the counter sidelink allocation index and the total sidelink allocation index are specific to a group index, or 2. The method of claim 1, wherein the counter sidelink allocation index and the total sidelink allocation index are applicable to different group indices.

4. generating the one or more codebooks generating a first codebook comprising acknowledgment or negative acknowledgement bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages, the first subset of sidelink messages being associated with a first group index; and generating a second codebook comprising acknowledgment or negative acknowledgement bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, the second subset of sidelink messages being associated with a second group index different from the first group index, or transmitting the set of feedback messages transmit, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including acknowledgment or negative acknowledgment bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages associated with a first group index; and transmitting, via second physical sidelink feedback channel resources, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including acknowledgment or negative acknowledgment bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages associated with a second group index.

5. receiving control signaling indicating one or more of the quantity of the one or more codebooks, the quantity of physical sidelink shared channel groups, the quantity of physical sidelink shared channel priority levels, the sidelink priority threshold, or an indication whether acknowledgment or non-acknowledgment bits for sidelink messages associated to different priority levels, different group indices, or both different priority levels and different group indices should be included in a joint codebook or in separate codebooks, wherein generating the one or more codebooks is based at least in part on the control signaling; or receiving radio resource control signaling indicating the sidelink feedback configuration, wherein transmitting the set of feedback messages to the second wireless device is based at least in part on the radio resource control signaling; or and receiving radio resource control signaling indicating a sidelink control information format comprising: a group index field, a hybrid automatic repeat request (HAR) acknowledgment trigger field, a first acknowledgment feedback indicator field associated with a first physical sidelink shared channel group, a second acknowledgment feedback indicator field associated with a second physical sidelink shared channel group, a counter sidelink allocation index field, a first total sidelink allocation index field associated with the first physical sidelink shared channel group, a second total sidelink allocation index field associated with the second physical sidelink shared channel group, or any combination thereof.

6. the plurality of sidelink messages comprise unicast physical sidelink shared channel transmissions, groupcast physical sidelink shared channel transmissions, or both; the unicast physical sidelink shared channel transmissions and the groupcast physical sidelink shared channel transmissions are associated with distinct counter sidelink allocation indices and distinct total sidelink allocation indices; or transmitting the set of feedback messages transmitting, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including an acknowledgment or negative acknowledgment bit corresponding to the unicast physical sidelink shared channel transmission; and transmitting, via second physical sidelink feedback channel resources, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including an acknowledgment or negative acknowledgment bit corresponding to the groupcast physical sidelink shared channel transmission; or receiving radio resource control signaling indicating whether the acknowledgment or negative acknowledgement bits for the unicast physical sidelink shared channel transmissions and the acknowledgment or negative acknowledgement bits for the groupcast physical sidelink shared channel transmissions should be included in a single codebook or in different codebooks, and generating the one or more codebooks is based at least in part on the radio resource control signaling; or generating the one or more codebooks generating a joint codebook including acknowledgement or negative acknowledgement bits corresponding to the unicast physical sidelink shared channel transmissions and the groupcast physical sidelink shared channel transmissions; generating the joint codebook, generating a first subset of the joint codebook that includes acknowledgement or negative acknowledgement bits corresponding to the unicast physical sidelink shared channel transmission; generating a second subset of the joint codebook that includes an acknowledgment or a negative acknowledgement bit corresponding to the groupcast physical sidelink shared channel transmission, wherein the first subset of the joint codebook precedes the second subset of the joint codebook; or transmitting the set of feedback messages 2. The method of claim 1, comprising transmitting an indication of the joint codebook on physical sidelink feedback channel resources in accordance with the sidelink feedback configuration.

7. transmitting the set of feedback messages transmitting, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including an acknowledgment or negative acknowledgment bit corresponding to a unicast physical sidelink shared channel transmission; and and transmitting, via second physical sidelink feedback channel resources, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including an acknowledgment or negative acknowledgment bit corresponding to a groupcast physical sidelink shared channel transmission.

8. the plurality of sidelink messages comprising a first set of groupcast physical sidelink shared channel transmissions associated with a first group identifier and a second set of groupcast physical sidelink shared channel transmissions associated with a second group identifier; generating the one or more codebooks generating a joint codebook including acknowledgement or negative acknowledgement bits corresponding to the first set of groupcast physical sidelink shared channel transmissions and the second set of groupcast physical sidelink shared channel transmissions; generating the joint codebook, generating a first subset of the joint codebook that includes acknowledgement or negative acknowledgement bits corresponding to a first set of the groupcast physical sidelink shared channel transmissions; generating a second subset of the joint codebook including acknowledgement or negative acknowledgement bits corresponding to a second set of the groupcast physical sidelink shared channel transmissions, or generating the one or more codebooks generating a first codebook containing acknowledgement or negative acknowledgement bits corresponding to a first set of the groupcast physical sidelink shared channel transmissions; generating a second codebook containing acknowledgement or negative acknowledgement bits corresponding to a second set of the groupcast physical sidelink shared channel transmissions; transmitting the set of feedback messages transmitting an indication of the first codebook and the second codebook on different physical sidelink feedback channel resources in accordance with the sidelink feedback configuration; or 2. The method of claim 1, further comprising receiving radio resource control signaling indicating whether acknowledgment or negative acknowledgment bits for the first set of groupcast physical sidelink shared channel transmissions and acknowledgment or negative acknowledgment bits for the second set of groupcast physical sidelink shared channel transmissions should be included in a single codebook or in different codebooks, and generating the one or more codebooks is based at least in part on the radio resource control signaling.

9. retransmitting the set of feedback messages based at least in part on the outcome of a listen-before-talk procedure, an unsuccessful initial transmission, or both; or receiving sidelink control information indicative of acknowledgement feedback indicators associated with the plurality of sidelink messages; and and determining whether to reset one or both of a counter sidelink allocation index or a total sidelink allocation index for a subsequent sidelink message based at least in part on a value of the acknowledgment feedback indicator; generating the one or more codebooks generating a codebook comprising acknowledgement or negative acknowledgement bits corresponding to the sidelink messages associated with the same value of the acknowledgement feedback indicator; or receiving sidelink control information indicating a physical sidelink shared channel group index, a hybrid automatic repeat request acknowledgment trigger field, or both; determining, based at least in part on the sidelink control information, whether to report hybrid automatic repeat request (HAR) acknowledgment feedback for the first physical sidelink shared channel group, the second physical sidelink shared channel group, or both; generating the one or more codebooks 2. The method of claim 1, comprising generating the one or more codebooks containing hybrid automatic repeat request (HAR) acknowledgment feedback for the first physical sidelink shared channel group and the second physical sidelink shared channel group based at least in part on a value of the HARR acknowledgment trigger field, wherein the one or more codebooks are concatenated in ascending order with respect to physical sidelink shared channel group index.

10. The method comprising: receiving sidelink control information indicating a counter sidelink allocation index, a first total sidelink allocation index associated with a first physical sidelink shared channel group, a first acknowledgment feedback indicator associated with the first physical sidelink shared channel group, or a combination thereof; determining whether to reset one or both of the first total sidelink allocation index or the counter sidelink allocation index for the first physical sidelink shared channel group based at least in part on a value of the first acknowledgment feedback indicator; and and receiving sidelink control information indicating a second acknowledgment feedback indicator associated with a second physical sidelink shared channel group and a second total sidelink allocation index, wherein generating the one or more codebooks is based at least in part on receiving the sidelink control information.

11. 1. A method for wireless communication in a first wireless device, comprising: transmitting, to a second wireless device, control signaling indicating a sidelink feedback configuration for the second wireless device; and transmitting a plurality of sidelink messages to the second wireless device over a plurality of sidelink resources; and monitoring a set of feedback resources for a set of feedback messages from the second wireless device in accordance with the sidelink feedback configuration, the set of feedback messages including an indication of one or more codebooks generated by the second wireless device, the one or more codebooks including a plurality of acknowledgment or negative acknowledgment bits corresponding to the sidelink messages, the plurality of sidelink messages being associated with different group indices.

12. receiving, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook of the one or more codebooks, the first codebook including acknowledgment or negative acknowledgment bits corresponding to a first subset of sidelink messages from the plurality of sidelink messages associated with a first group index; and receiving, via second physical sidelink feedback channel resources, a second feedback message indicating a second codebook of the one or more codebooks, the second codebook including acknowledgment or negative acknowledgment bits corresponding to a second subset of sidelink messages from the plurality of sidelink messages, associated with a second group index.

13. the sidelink feedback configuration indicates a sidelink priority threshold, a mapping between respective group indices and the one or more codebooks, or a combination thereof; or the plurality of sidelink messages are multiplexed with respective instances of sidelink control information; and each respective instance of sidelink control information comprising an indication of a counter sidelink allocation index and an aggregate sidelink allocation index associated with a sidelink message from the plurality of sidelink messages; the counter sidelink allocation index and the total sidelink allocation index are specific to a priority level, a group index, or both; or the counter sidelink allocation index and the total sidelink allocation index are applicable to different priority levels, different group indices, or both; or the plurality of sidelink messages comprises unicast physical sidelink shared channel transmissions; or the plurality of sidelink messages comprise unicast physical sidelink shared channel transmissions, groupcast physical sidelink shared channel transmissions, or both; 12. The method of claim 11, wherein the unicast physical sidelink shared channel transmissions and the groupcast physical sidelink shared channel transmissions are associated with separate counter sidelink allocation indices and separate total sidelink allocation indices.

14. The method of claim 13, wherein transmitting the control signaling comprises: transmitting radio resource control signaling indicating the quantity of the one or more codebooks, the quantity of physical sidelink shared channel groups, the quantity of physical sidelink shared channel priority levels, a sidelink priority threshold, or a combination thereof; or transmitting radio resource control signaling indicating a sidelink control information format comprising a group index field, a hybrid automatic repeat request (HAR) acknowledgment trigger field, a first acknowledgment feedback indicator field associated with a first physical sidelink shared channel group, a second acknowledgment feedback indicator field associated with a second physical sidelink shared channel group, a counter sidelink allocation index field, a first total sidelink allocation index field associated with the first physical sidelink shared channel group, a second total sidelink allocation index field associated with the second physical sidelink shared channel group, or a combination thereof; or transmitting sidelink control information indicating a counter sidelink allocation index, a total sidelink allocation index, an acknowledgment feedback indicator, or a combination thereof, wherein the value of the acknowledgment feedback indicator indicates whether one or both of the total sidelink allocation index or the counter sidelink allocation index are reset for a physical sidelink shared channel group, or transmitting the control signaling 12. The method of claim 11, comprising transmitting radio resource control signaling indicating whether acknowledgement or negative acknowledgement bits for unicast physical sidelink shared channel transmissions and acknowledgement or negative acknowledgement bits for groupcast physical sidelink shared channel transmissions should be included in a single codebook or in different codebooks.

15. The method comprising: receiving, via physical sidelink feedback channel resources, a feedback message indicating a joint codebook including acknowledgement or negative acknowledgement bits corresponding to unicast physical sidelink shared channel transmissions and acknowledgement or negative acknowledgement bits corresponding to groupcast physical sidelink shared channel transmissions; or receiving, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook containing acknowledgement or negative acknowledgement bits corresponding to the unicast physical sidelink shared channel transmission; and and receiving, via second physical sidelink feedback channel resources, a second feedback message indicating a second codebook containing acknowledgement or negative acknowledgement bits corresponding to the groupcast physical sidelink shared channel transmission.

16. the plurality of sidelink messages comprising a first set of groupcast physical sidelink shared channel transmissions associated with a first group identifier and a second set of groupcast physical sidelink shared channel transmissions associated with a second group identifier; transmitting the control signaling 12. The method of claim 11, comprising transmitting radio resource control signaling indicating whether an acknowledgment or negative acknowledgment bit for the first set of groupcast physical sidelink shared channel transmissions and an acknowledgment or negative acknowledgment bit for the second set of groupcast physical sidelink shared channel transmissions should be included in a single codebook or in different codebooks.

17. receiving, via first physical sidelink feedback channel resources, a first feedback message indicating a first codebook including acknowledgement or negative acknowledgement bits corresponding to a first set of groupcast physical sidelink shared channel transmissions; and receiving, via second physical sidelink feedback channel resources, a second feedback message indicating a second codebook including acknowledgement or negative acknowledgement bits corresponding to a second set of groupcast physical sidelink shared channel transmissions; or 12. The method of claim 11, further comprising receiving a feedback message indicating a codebook including acknowledgement or negative acknowledgement bits corresponding to the plurality of sidelink messages associated with the same acknowledgement feedback indicator value.

18. The method of claim 11, further comprising transmitting sidelink control information indicating a physical sidelink shared channel group index, a hybrid automatic repeat request acknowledgement trigger field, a first acknowledgement feedback indicator associated with a first physical sidelink shared channel group, a second acknowledgement feedback indicator associated with a second physical sidelink shared channel group, a counter sidelink allocation index, a first total sidelink allocation index associated with the first physical sidelink shared channel group, a second total sidelink allocation index associated with the second physical sidelink shared channel group, or a combination thereof.

19. 1. An apparatus for wireless communication in a first wireless device, comprising: a processor; a memory coupled to the processor; and instructions stored in said memory and executable by said processor to cause said apparatus to perform all the steps of the method of any one of claims 1 to 18.

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