Techniques for sidelink resource cancellation using time domain resource allocation

Abstract

Methods, systems, and devices for wireless communication are described. A first user equipment (UE) can be configured to transmit a first sidelink control information (SCI) message associated with a first sidelink transmission from the first UE, the first SCI including a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions. The UE can identify a second SCI message associated with the first SCI message, where the second SCI provides a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission. The UE can then perform a retransmission of the first sidelink transmission in accordance with the release.

Description

[0001] Cross-referencing

[0002] This patent application claims priority to U.S. Patent Application No. 17 / 495,371, filed October 6, 2021, entitled “TECHNIQUES FOR SIDELINK RESOURCE CANCELLATION USING TIME DOMAIN RESOURCE ALLOCATION,” which claims the benefit of U.S. Provisional Patent Application No. 63 / 090,019, filed October 9, 2020, entitled “TECHNIQUES FOR SIDELINK RESOURCE CANCELLATION USING TIME DOMAIN RESOURCE ALLOCATION,” which has been assigned to the assignee of this application. Technical Field

[0003] The following content relates to wireless communications, including techniques for canceling sidelink resources using Time Domain Resource Allocation (TDRA) field values. Background Technology

[0004] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, message sending and receiving, broadcasting, and so on. These systems can support 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-A Advanced (LTE-A) systems, or LTE-A Pro systems) and fifth-generation (5G) systems, which may be referred to as New Radio (NR) systems. These systems can employ various technologies, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or Discrete Fourier Transform Extended Orthogonal Frequency Division Multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include one or more base stations or one or more network access nodes, each of which simultaneously supports communication from multiple communication devices, which may also be referred to as User Equipment (UE).

[0005] A UE can reserve resources on a sidelink channel for communication in a vehicle to everything (V2X) wireless communications system. The UE can reserve resources for an initial transmission and, in some cases, one or more retransmissions. Improvements can be made to techniques for efficient use of resources on a sidelink channel. SUMMARY

[0006] The described techniques relate to improved methods, systems, devices, and apparatuses that support techniques for sidelink resource cancellation using time domain resource allocation (TDRA) field values. Generally, the described techniques provide for the release of previously reserved sidelink resources. Specifically, a sidelink control information (SCI) can include an indication to release a set of resources previously reserved for a retransmission of a sidelink transmission. For example, a first UE can transmit a first SCI reserving resources for a sidelink transmission. In the case that a first transmission of the sidelink transmission is successfully received by a second UE, the first UE (which transmitted the first SCI) and / or the second UE can transmit a second SCI interpreted as releasing the remaining resources scheduled by the initial SCI. In some aspects, the second SCI indicating the release of resources can include one or more TDRA field values reserving additional sidelink resources for sidelink communications. The one or more TDRA field values within the second SCI for indicating additional sidelink resource reservations can include a TDRA field value that is not associated with a time resource reservation (e.g., an “unspecified” TDRA field). In some aspects, a UE receiving the second SCI (e.g., the first UE and / or the second UE) can be configured to determine that the release of sidelink resources indicated by the second SCI is associated with resources reserved by the first SCI based on an explicit indicator (e.g., a transmission identifier, a reception identifier) within the first SCI and / or the second SCI message, based on a configured or determined relationship between the first SCI message and the second SCI message (e.g., a range of resources allocated for the second SCI relative to the first SCI message, a preconfigured relationship between the first SCI message and the second SCI message), or both.

[0007] A method for wireless communications at a first UE is described. The method can include transmitting, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and transmitting, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0008] An apparatus for wireless communications at a first UE is described. The apparatus can include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions can be executable by the processor to cause the apparatus to transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0009] Another apparatus for wireless communications at a first UE is described. The apparatus can include means for transmitting, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, means for identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and means for transmitting, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0010] A non-transitory computer-readable medium storing code for wireless communications at a first UE is described. The code can include instructions executable by a processor to transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0011] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for transmitting, via the first SCI message, a first identifier that associates the first SCI message with the first UE, a second UE to which the first sidelink transmission is directed, or both, where the second SCI message includes a second identifier that associates the second SCI message with the same UE identified by the first identifier, and identifying that the release pertains to the at least one retransmission occasion based on the first identifier and the second identifier.

[0012] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying that the release pertains to the at least one retransmission occasion can include operations, features, means, or instructions for determining that a difference between the first transmission time interval and the second transmission time interval satisfies a threshold difference, the threshold difference can be based on a configured hybrid automatic repeat request (HARQ) feedback time, where the release can be identified as pertaining to the at least one retransmission occasion based on the difference satisfying the threshold difference.

[0013] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying that the release pertains to the at least one retransmission occasion can include operations, features, means, or instructions for determining that a first subchannel of the first SCI message and a second subchannel of the second SCI message can be within a threshold range, the threshold range can be based on a first physical sidelink shared channel (PSSCH) resource during the first transmission time interval and a second PSSCH resource during the second transmission time interval, where the release can be identified as pertaining to the at least one retransmission occasion based on the threshold range being satisfied.

[0014] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying that the release is related to the at least one retransmission occasion can include operations, features, means, or instructions for determining that a second transmission time interval and a subchannel of the second SCI message can be within a threshold amount of the at least one retransmission occasion, where the release can be identified as related to the at least one retransmission occasion based on the threshold amount being satisfied.

[0015] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that the second SCI message can be within a first set of resources reserved for retransmissions of the first sidelink transmission, and identifying that the release is related to the at least one retransmission occasion based on identifying the second SCI message within the first set of resources.

[0016] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that at least one of a second transmission time interval or a subchannel of the second SCI message can be within a configured range of the first SCI message, and identifying that the release is related to the at least one retransmission occasion based on the configured range being satisfied.

[0017] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that the release is related to the at least one retransmission occasion based on transmission time intervals and subchannels of the one or more retransmission occasions.

[0018] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving a control message indicating a relationship between the second SCI message and at least one of the first SCI message or the one or more retransmission occasions, and identifying that the release is related to the at least one retransmission occasion based on the relationship.

[0019] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining a TDRA field value of the first SCI message, a frequency domain resource allocation (FDRA) field value of the first SCI message, a cyclic redundancy check (CRC) portion of the first SCI message, or any combination thereof, and identifying that the release is related to the at least one retransmission occasion based on the TDRA field value of the first SCI message, the FDRA field value of the first SCI message, the CRC portion of the first SCI message, or any combination thereof.

[0020] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that the second SCI message includes second data that includes a checksum or a hash function of at least a portion of the first data included within the first SCI message, and identifying that the release relates to the at least one retransmission occasion based on identifying that the second data included within the second SCI message includes the checksum or the hash function of the first data included within the first SCI message.

[0021] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, and the method, apparatuses, and non-transitory computer-readable medium can include further operations, features, means, or instructions for where the first data includes a first CRC portion of the first SCI message, a set of TDRA values of the first SCI message, a set of FDRA values of the first SCI message, or any combination thereof; and where the second data includes a second CRC portion of the second SCI message, a second set of FDRA values of the second SCI message, a set of demodulation reference signal (DMRS) bit values of the second SCI message, or any combination thereof.

[0022] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the second SCI message includes one or more TDRA field values indicating a second set of resources reserved for retransmission of the second sidelink transmission.

[0023] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the second sidelink transmission includes a retransmission of the second SCI message, a data transmission conveyed via a PSSCH, or any combination thereof.

[0024] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more TDRA field values include one or more time resource indicator values (TRIVs) that can be independent of time resource reservations.

[0025] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving a control message including an indication of a set of TRIVs, the set of TRIVs including a first subset of TRIVs associated with time resource reservations and a second subset of TRIVs that can be independent of time resource reservations, where the one or more TDRA field values in the second SCI message include a TRIV from the second subset of TRIVs.

[0026] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying one or more additional fields within the second SCI message, and identifying that the release pertains to the at least one of the one or more retransmission occasions based on the one or more TDRA field values, the one or more additional fields within the second SCI message, or both.

[0027] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more additional fields within the second SCI message include a first field associated with a DMRS, a second field associated with a port for the DMRS, a third field associated with a priority of the sidelink communication, a fourth field associated with a physical sidelink feedback channel (PSFCH) overhead, a fifth field associated with the FDRA, or any combination thereof.

[0028] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for transmitting a first sidelink transmission in accordance with the first SCI message, and receiving a feedback message from the second UE indicating that the first sidelink transmission was received by the second UE, wherein the UE identifies the second SCI message based on the feedback message generating the second SCI message.

[0029] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that the second SCI message is received from the second UE.

[0030] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a time period before a first retransmission occasion of the one or more retransmission occasions during which at least the first retransmission occasion can not be released, wherein the second SCI message can be identified before a start of the identified time period.

[0031] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a time period after transmission of the first SCI message during which the one or more retransmission occasions can not be released, wherein the second SCI message can be identified after an end of the identified time period.

[0032] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a HARQ configuration associated with the sidelink communication, where identifying the time period after the transmission of the first SCI message can be based on the determined HARQ configuration.

[0033] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving a third sidelink transmission from the second UE, the third UE, or both, on a set of resources associated with the at least one retransmission occasion released via the second SCI message, where the third sidelink transmission can be received based on identifying the second SCI message.

[0034] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for transmitting the retransmission of the first sidelink transmission only on the second subset of the first set of resources includes refraining from performing any retransmission of the first sidelink transmission.

[0035] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a candidate set of resources for transmitting the second SCI message based on transmitting the first SCI message, where the candidate set of resources can have a higher priority than other sidelink transmission messages selected for transmission; and selecting a set of resources from the candidate set of resources for transmitting the second SCI message based on the candidate set of resources having the higher priority.

[0036] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining a first channel occupancy of a sidelink communication network prior to transmitting the second SCI message; and determining a second channel occupancy of the sidelink communication network based on identifying the second SCI providing the release.

[0037] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, the second SCI message can be transmitted with a specified priority that can be greater than a priority associated with other transmissions.

[0038] A method of wireless communication is described. The method can include transmitting, at a first UE, a first SCI message associated with a first sidelink transmission from the first UE during a first transmission time interval, where the first SCI includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and transmitting, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0039] An apparatus for wireless communication at a first UE is described. The apparatus can include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions can be executable by the processor to cause the apparatus to transmit, at a first UE, a first SCI message associated with a first sidelink transmission from the first UE during a first transmission time interval, where the first SCI includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0040] Another apparatus for wireless communication at a first UE is described. The apparatus can include means for transmitting, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions; identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions; and transmitting, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0041] A non-transitory computer-readable medium storing code for wireless communications at a first UE is described. The code can include instructions executable by a processor to transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions; identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions; and transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0042] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for transmitting, via the first SCI message, a first identifier that associates the first SCI message with the first UE, a second UE to which the first sidelink transmission is directed, or both, where the second SCI message includes a second identifier that associates the second SCI message with the same UE identified by the first identifier, and identifying that the release pertains to the at least one retransmission occasion based on the first identifier and the second identifier.

[0043] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying that the release is related to the at least one retransmission occasion can further include operations, features, means, or instructions for determining that a difference between the first transmission time interval and the second transmission time interval satisfies a threshold difference, the threshold difference can be based on a configured HARQ feedback time, where the release can be identified as related to the at least one retransmission occasion based on the difference satisfying the threshold difference.

[0044] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying that the release is related to the at least one retransmission occasion can further include operations, features, means, or instructions for determining that a first subchannel of the first SCI message and a second subchannel of the second SCI message can be within a threshold range, the threshold range can be based on a first PSSCH resource during the first transmission time interval and a second PSSCH resource during the second transmission time interval, where the release can be identified as related to the at least one retransmission occasion based on the threshold range being satisfied.

[0045] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying that the release is related to the at least one retransmission occasion can further include operations, features, means, or instructions for determining that the second transmission time interval and a subchannel of the second SCI message can be within a threshold amount of the at least one retransmission occasion, where the release can be identified as related to the at least one retransmission occasion based on the threshold amount being satisfied.

[0046] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that the second SCI message can be within a first set of resources reserved for retransmissions of the first sidelink transmission, and identifying that the release is related to the at least one retransmission occasion based on identifying the second SCI message within the first set of resources.

[0047] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that at least one of the second transmission time interval or a subchannel of the second SCI message can be within a configured range of the first SCI message, and identifying that the release is related to the at least one retransmission occasion based on the configured range being satisfied.

[0048] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that the release is related to the at least one retransmission occasion based on transmission time intervals and subchannels of the one or more retransmission occasions.

[0049] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving a control message indicating a relationship between the second SCI message and at least one of the first SCI message or the one or more retransmission occasions, and identifying that the release pertains to the at least one retransmission occasion based on the relationship.

[0050] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining a TDRA field value of the first SCI message, a FDRA field value of the first SCI message, a CRC portion of the first SCI message, or any combination thereof, and identifying that the release pertains to the at least one retransmission occasion based on the TDRA field value of the first SCI message, the FDRA field value of the first SCI message, the CRC portion of the first SCI message, or any combination thereof.

[0051] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that the second SCI message includes second data that includes a checksum or a hash function of at least a portion of the first data included within the first SCI message, and identifying that the release pertains to the at least one retransmission occasion based on identifying that the second data included within the second SCI message includes the checksum or the hash function of the first data included within the first SCI message.

[0052] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for where the first data includes a first CRC portion of the first SCI message, a set of TDRA values of the first SCI message, a set of FDRA values of the first SCI message, or any combination thereof, and where the second data includes a second CRC portion of the second SCI message, a set of second FDRA values of the second SCI message, a set of DMRS bit values of the second SCI message, or any combination thereof.

[0053] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the second sidelink transmission includes a retransmission of the second SCI message, a data transmission conveyed via a PSSCH, or any combination thereof.

[0054] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for transmitting a first sidelink transmission according to the first SCI message, and receiving, from the second UE, a feedback message indicating that the first sidelink transmission was received by the second UE, where the UE identifies the second SCI message by generating the second SCI message based on the feedback message.

[0055] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the second SCI message can include operations, features, means, or instructions for receiving the second SCI message from the second UE.

[0056] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more TDRA field values include one or more TRIVs that can be independent of the time resource reservation.

[0057] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving a control message including an indication of a set of TRIVs, the set of TRIVs including a first subset of TRIVs associated with the time resource reservation and a second subset of TRIVs that can be independent of the time resource reservation, where the one or more TDRA field values in the second SCI message include time resource indicator values from the second subset of TRIVs.

[0058] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying one or more additional fields within the second SCI message, and identifying that the release pertains to the at least one of the one or more retransmission occasions based on the one or more TDRA field values, the one or more additional fields within the second SCI message, or both.

[0059] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more additional fields within the second SCI message include a first field associated with a DMRS, a second field associated with a port for the DMRS, a third field associated with a priority of the sidelink communication, a fourth field associated with a PSFCH overhead, a fifth field associated with an FDRA, or any combination thereof.

[0060] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a time period prior to a first retransmission occasion of the one or more retransmission occasions during which at least the first retransmission occasion can not be released, where the second SCI message can be identified prior to a start of the identified time period.

[0061] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a time period subsequent to the transmission of the first SCI message during which the one or more retransmission occasions can not be released, where the second SCI message can be identified after an end of the identified time period.

[0062] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a HARQ configuration associated with the sidelink communication, where identifying the time period subsequent to the transmission of the first SCI message can be based on the determined HARQ configuration.

[0063] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving, from the second UE, the third UE, or both, a third sidelink transmission on a set of resources associated with the at least one retransmission occasion released via the second SCI message, where the third sidelink transmission can be received based on identifying the second SCI message.

[0064] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, transmitting fewer retransmissions of the first sidelink transmission than signaled by the first indication can include operations, features, means, or instructions for refraining from performing any retransmissions of the first sidelink transmission.

[0065] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a candidate set of resources for transmitting the second SCI message based on transmitting the first SCI message, where the candidate set of resources can have a higher priority than other sidelink transmission messages selected for transmission; and selecting a set of resources from the candidate set of resources for transmitting the second SCI message based on the candidate set of resources having the higher priority.

[0066] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining, prior to transmitting the second SCI, a first channel occupancy of the sidelink communication network, and determining a second channel occupancy of the sidelink communication network based on identifying that the second SCI provides the release.

[0067] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the second SCI message can be transmitted with a designated priority that can be greater than a priority associated with other transmissions.

[0068] A method of wireless communication is described at a second UE. The method can include receiving, from a first UE during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE to the second UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and monitoring only a second subset of the first set of resources in accordance with the release of the first subset of the first set of resources.

[0069] An apparatus for wireless communication at a second UE is described. The apparatus can include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions can be executable by the processor to cause the apparatus to receive, from a first UE during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE to the second UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and monitor only a second subset of the first set of resources in accordance with the release of the first subset of the first set of resources.

[0070] Another apparatus for wireless communication at a second UE is described. The apparatus can include means for receiving, from a first UE during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE to the second UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and monitoring only a second subset of the first set of resources in accordance with the release of the first subset of the first set of resources.

[0071] A non-transitory computer-readable medium storing code for wireless communication at a second UE is described. The code can include instructions executable by a processor to receive, from a first UE during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE to the second UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and monitor only a second subset of the first set of resources in accordance with the release of the first subset of the first set of resources.

[0072] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving, via the first SCI message, a first identifier that associates the first SCI message with the first UE, the second UE to which the first sidelink transmission is directed, or both, where the second SCI message includes a second identifier that associates the second SCI message with the same UE identified by the first identifier, and identifying that the release pertains to the at least one retransmission occasion based on the first identifier and the second identifier.

[0073] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, identifying that the release is related to the at least one retransmission occasion can further include operations, features, means, or instructions for determining that a difference between the first transmission time interval and the second transmission time interval satisfies a threshold difference, the threshold difference can be based on a configured HARQ feedback time, where the release can be identified as related to the at least one retransmission occasion based on the difference satisfying the threshold difference.

[0074] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, identifying that the release is related to the at least one retransmission occasion can further include operations, features, means, or instructions for determining that a first subchannel of the first SCI message and a second subchannel of the second SCI message can be within a threshold range, the threshold range can be based on a first PSSCH resource during the first transmission time interval and a second PSSCH resource during the second transmission time interval, where the release can be identified as related to the at least one retransmission occasion based on the threshold range being satisfied.

[0075] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, identifying that the release is related to the at least one retransmission occasion can further include operations, features, means, or instructions for determining that the second transmission time interval and a subchannel of the second SCI message can be within a threshold amount of the at least one retransmission occasion, where the release can be identified as related to the at least one retransmission occasion based on the threshold amount being satisfied.

[0076] Some examples of the method, apparatuses, and non-transitory computer- readable medium described herein can further include operations, features, means, or instructions for identifying that the second SCI message can be within a first set of resources reserved for retransmissions of the first sidelink transmission; and identifying that the release is related to the at least one retransmission occasion based on identifying the second SCI message within the first set of resources.

[0077] Some examples of the method, apparatuses, and non-transitory computer- readable medium described herein can further include operations, features, means, or instructions for identifying that at least one of the second transmission time interval or a subchannel of the second SCI message can be within a configured range of the first SCI message; and identifying that the release is related to the at least one retransmission occasion based on the configured range being satisfied.

[0078] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying, based on the transmission time interval and the subchannel of the one or more retransmission occasions and the second SCI message, that the release pertains to the at least one retransmission occasion.

[0079] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving a control message indicating a relationship between the second SCI message and at least one of the first SCI message or the one or more retransmission occasions; and identifying, based on the relationship, that the release pertains to the at least one retransmission occasion.

[0080] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining a TDRA field value of the first SCI message, a FDRA field value of the first SCI message, a CRC portion of the first SCI message, or any combination thereof; and identifying, based on the TDRA field value of the first SCI message, the FDRA field value of the first SCI message, the CRC portion of the first SCI message, or any combination thereof, that the release pertains to the at least one retransmission occasion.

[0081] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying that the second SCI message includes second data that includes a checksum or a hash function of at least a portion of first data included within the first SCI message; and identifying, based on identifying that the second data included within the second SCI message includes the checksum or the hash function of the first data included within the first SCI message, that the release pertains to the at least one retransmission occasion.

[0082] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for where the first data includes a first CRC portion of the first SCI message, a set of TDRA values of the first SCI message, a set of FDRA values of the first SCI message, or any combination thereof; and where the second data includes a second CRC portion of the second SCI message, a set of second FDRA values of the second SCI message, a set of DMRS bit values of the second SCI message, or any combination thereof.

[0083] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the second sidelink transmission includes a retransmission of the second SCI message, a data transmission conveyed via a PSSCH, or any combination thereof.

[0084] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving, from the first UE, a first sidelink transmission in accordance with the first SCI message, and transmitting, to the first UE, a feedback message indicating that the first sidelink transmission was received, where the UE identifies the second SCI message by receiving the second SCI message based on the feedback message.

[0085] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, identifying the second SCI message can include operations, features, means, or instructions for transmitting, to the first UE, the second SCI message.

[0086] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more TDRA field values include one or more TRIVs that can be independent of the time resource reservation.

[0087] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for receiving a control message including an indication of a set of TRIVs, the set of TRIVs including a first subset of TRIVs associated with the time resource reservation and a second subset of TRIVs that can be independent of the time resource reservation, where the one or more TDRA field values in the second SCI message include time resource indicator values from the second subset of TRIVs.

[0088] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying one or more additional fields within the second SCI message, and identifying that the release pertains to the at least one of the one or more retransmission occasions based on the one or more TDRA field values, the one or more additional fields within the second SCI message, or both.

[0089] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more additional fields within the second SCI message include a first field associated with a DMRS, a second field associated with a port for the DMRS, a third field associated with a priority of the sidelink communication, a fourth field associated with a PSFCH overhead, a fifth field associated with an FDRA, or any combination thereof.

[0090] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a time period prior to a first retransmission occasion of the one or more retransmission occasions during which at least the first retransmission occasion can not be released, where the second SCI message can be identified prior to a start of the identified time period.

[0091] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a time period subsequent to the transmission of the first SCI message during which the one or more retransmission occasions can not be released, where the second SCI message can be identified after an end of the identified time period.

[0092] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a HARQ configuration associated with the sidelink communication, where identifying the time period subsequent to the transmission of the first SCI message can be based on the determined HARQ configuration.

[0093] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for transmitting, to the first UE, the third UE, or both, a third sidelink transmission on a set of resources associated with at least one retransmission occasion released via the second SCI message, where the third sidelink transmission can be transmitted based on identifying the second SCI message.

[0094] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, monitoring fewer retransmission occasions of the one or more retransmission occasions associated with the first sidelink transmission than signaled by the first indication can include operations, features, means, or instructions for refraining from monitoring any of the one or more retransmission occasions.

[0095] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a candidate set of resources for transmitting the second SCI message based on receiving the first SCI message, where the candidate set of resources can have a higher priority than other sidelink transmission messages selected for transmission based on the candidate set of resources having the higher priority.

[0096] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for identifying a set of candidate resources for transmitting the second SCI message based on receiving the first SCI message, where the set of candidate resources can have a lower priority than a resource set selected for transmitting the second SCI message for being selected for transmitting other sidelink transmission messages; and refraining from selecting a resource set from the set of candidate resources for transmitting the other sidelink transmission messages based on the set of candidate resources having the lower priority.

[0097] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining a first channel occupancy of a sidelink communication network prior to transmitting the second SCI; and determining a second channel occupancy of the sidelink communication network based on identifying the second SCI providing the release.

[0098] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the second SCI message can be transmitted with a specified priority that can be greater than a priority associated with other transmissions.

[0099] A method of wireless communication is described at a first UE. The method can include transmitting, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions; identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions; and transmitting, in accordance with the release of the first subset of the first set of resources, retransmissions of the first sidelink transmission only on a second subset of the first set of resources.

[0100] An apparatus for wireless communication at a first UE is described. The apparatus can include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions can be executable by the processor to cause the apparatus to transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0101] Another apparatus for wireless communication at a first UE is described. The apparatus can include means for transmitting, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and transmitting, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0102] A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code can include instructions executable by a processor to transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0103] A method of wireless communication is described. The method can include receiving, from a first UE, a first SCI message associated with a sidelink transmission from the first UE to a second UE during a first transmission time interval, where the first SCI message includes a first indication of a set of resources reserved for retransmission of the sidelink transmission at one or more retransmission occasions, identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and monitoring only a second subset of the set of resources according to the release of the first subset of the set of resources.

[0104] An apparatus for wireless communication at a second UE is described. The apparatus can include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions can be executable by the processor to cause the apparatus to receive, from a first UE, a first SCI message associated with a sidelink transmission from the first UE to the second UE during a first transmission time interval, where the first SCI message includes a first indication of a set of resources reserved for retransmission of the sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and monitor only a second subset of the set of resources according to the release of the first subset of the set of resources.

[0105] Another apparatus for wireless communication at a second UE is described. The apparatus can include means for receiving, from a first UE, a first SCI message associated with a sidelink transmission from the first UE to the second UE during a first transmission time interval, where the first SCI message includes a first indication of a set of resources reserved for retransmission of the sidelink transmission at one or more retransmission occasions, identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and monitoring only a second subset of the set of resources according to the release of the first subset of the set of resources.

[0106] A non-transient computer-readable medium storing code for wireless communication at a second UE is described. The code may include instructions executable by a processor to: receive, during a first transmission time interval, a first SCI message associated with a sidelink transmission from the first UE to the second UE, wherein the first SCI message includes a first indication of a set of resources reserved for retransmission of the sidelink transmission at one or more retransmission times; identify, during a second transmission time interval following the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of the release of at least a first subset of the set of resources reserved for retransmission of the sidelink transmission, the release relating to at least one of the one or more retransmission times; and monitor only a second subset of the first resource set based on the release of the first subset of the first resource set. Attached Figure Description

[0107] Figure 1 Examples of wireless communication systems that support techniques for sidelink resource cancellation using time-domain resource allocation (TDRA) according to various aspects of this disclosure are explained.

[0108] Figure 2 Examples of wireless communication systems that support techniques for sidelink resource cancellation using TDRA are described in accordance with various aspects of this disclosure.

[0109] Figure 3 Examples of resource retention schemes for using TDRA for sidelink resource cancellation are explained, based on various aspects of this disclosure.

[0110] Figure 4 Examples of resource retention schemes for using TDRA for sidelink resource cancellation are explained, based on various aspects of this disclosure.

[0111] Figure 5 An example of the process flow for using TDRA to cancel sidelink resources, based on various aspects of this disclosure, is explained.

[0112] Figure 6 and Figure 7 A block diagram of an apparatus supporting techniques for sidelink resource cancellation using TDRA is shown, according to various aspects of this disclosure.

[0113] Figure 8 A block diagram of a communication manager supporting techniques for sidelink resource cancellation using TDRA, according to various aspects of this disclosure, is shown.

[0114] Figure 9A diagram illustrating a system that includes a device that supports techniques for sidelink resource cancellation using TDRA is shown, in accordance with aspects of the present disclosure.

[0115] Figures 10 to 15 A flow chart illustrating a method that supports techniques for sidelink resource cancellation using TDRA is shown, in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0116] In some wireless communications systems, a user equipment (UE) can reserve resources for communication over a wireless channel. For example, in a vehicle-to-everything (V2X) wireless communications system, a UE can reserve resources on a sidelink channel for transmitting an initial transmission, and in some cases, one or more retransmissions of the initial transmission. The UE can transmit a first sidelink control information (SCI) message over the sidelink channel to reserve one or more resources on the sidelink channel. For example, the SCI message can reserve a first sidelink resource for the initial transmission, and one or more additional sidelink resources for retransmissions. The SCI message can include an indicator of the resource allocation for retransmissions, such that a receiving device can monitor for retransmissions on the corresponding resources. In some cases, the UE can reserve one or more additional resources for retransmissions, but the receiving device can successfully obtain the initial transmission. In this example, the UE can still have reserved the resources, but the UE can not use the reserved resources for retransmissions. In some wireless communications systems, these resources can go unused, reducing spectral efficiency and resource utilization over the wireless communications channel.

[0117] To enable more efficient use of sidelink communications resources, techniques for sidelink resource release are described. Specifically, an SCI message can include an indication to release a set of resources previously reserved for retransmissions of a sidelink transmission. For example, a first UE can transmit a first SCI message reserving resources for a sidelink transmission. In some cases, the reserved resources can include resources within a same time slot as the first SCI message for an initial sidelink transmission, and resources in subsequent time slots for retransmissions of the sidelink transmission at one or more retransmission occasions. In the case that a first transmission of the sidelink transmission is successfully received by a second UE, the first UE (which transmitted the first SCI message) and / or the second UE can transmit a second SCI message interpreted as releasing the remaining resources scheduled by the first SCI message.

[0118] In some aspects, the second SCI message indicating the release of previously reserved sidelink resources can include one or more time domain resource allocation (TDRA) field values that reserve additional sidelink resources for the sidelink communication. The one or more TDRA field values within the second SCI message to indicate the additional sidelink resource reservation can include a time resource indicator value (TRIV) that is not associated with a time resource reservation (e.g., an “unspecified” TRIV). In some aspects, a UE (e.g., the first UE and / or the second UE) receiving the second SCI message can be configured to determine that the release of the sidelink resources indicated by the second SCI message is associated with the resources reserved by the first SCI message based on an explicit indicator (e.g., a transmission identifier, a reception identifier) within the first SCI message and / or the second SCI message, based on a configured or determined relationship between the first SCI message and the second SCI message (e.g., a range of resources allocated for the second SCI message relative to the first SCI message, a preconfigured relationship between the first SCI message and the second SCI message), or both. These techniques described herein can enable more efficient use of resources in sidelink communication networks.

[0119] Aspects of the disclosure are initially described in the context of a wireless communication system. Aspects of the disclosure are further illustrated by and described in connection with apparatus diagrams, system diagrams, and flowcharts relating to techniques for sidelink resource release / cancellation using SCI messages.

[0120] Figure 1 An example of a wireless communication system 100 that supports techniques for sidelink resource cancellation using TDRA is illustrated in accordance with aspects of the present disclosure. The wireless communication system 100 can 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 can 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 can support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, communications with low-cost and low-complexity devices, or any combination thereof.

[0121] The base stations 105 can be dispersed throughout the geographic region to form the wireless communication system 100 and can be of different forms, or have different capabilities. Base stations 105 and UEs 115 can wirelessly communicate via one or more communication links 125. Each base station 105 can provide a coverage area 110 over which UEs 115 and base stations 105 can establish one or more communication links 125. The coverage area 110 can be an example of a geographic area over which base stations 105 and UEs 115 can support signal communication in accordance with one or more radio access technologies.

[0122] The UEs 115 can be dispersed throughout the coverage areas 110 of the wireless communication system 100, and each UE 115 can be stationary, or mobile, or both at different times. The UEs 115 can be devices in different forms or having different capabilities. Some example UEs 115 are illustrated in FIG. 1. A UE 115 described herein can 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. Figure 1 Some example UEs 115 are illustrated in FIG. 1. A UE 115 described herein can be able to communicate as a function of cellular communication capabilities, a wireless Figure 1 network communication capabilities, and / or another type of communication capabilities. A UE 115 can support simultaneous wireless communication with one or more cellular networks, one or more wireless local area networks (WLANs), and / or another type of wireless network.

[0123] The base stations 105 can communicate with the core network 130, or with one another, or both. For example, the base stations 105 can interface with the core network 130 through one or more backhaul links 120 (e.g., via an SI, N2, N3, or another interface). The base stations 105 can communicate with one another over the backhaul links 120 (e.g., via an X2, Xn, or other interface) either directly (e.g., directly between base stations 105), or indirectly (e.g., via core network 130), or both. In some examples, the backhaul links 120 can be or include one or more wireless links.

[0124] One or more of the base stations 105 described herein can include or can be referred to as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next-generation NodeB or giga-NodeB (either of which can be referred to as a gNB), a Home NodeB, a Home eNodeB, or other suitable terminology.

[0125] A UE 115 can include or can 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, where the “device” can also be referred to as a unit, a station, a terminal, or a client, among other examples. A UE 115 can also include or can 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, a UE 115 can 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 can be implemented in various objects such as appliances or vehicles, among other examples.

[0126] The UEs 115 described herein can be able to communicate with various types of devices, such as other UEs 115 that can sometimes act as relays as well as the base stations 105 and the network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, as discussed Figure 1 as illustrated in FIG. 1.

[0127] The UEs 115 and the base stations 105 can wirelessly communicate with one another via one or more communication links 125 over one or more carriers. The term “carrier” can refer to a set of radio frequency spectrum resources with a defined physical layer structure

[0128] In some examples (e.g., in carrier aggregation configurations), a carrier can also have acquisition signaling or control signaling that coordinates operations for other carriers. A carrier can be associated with a frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN)) and can be positioned according to a channel raster for discovery by the UEs 115. Carriers can be operated in a standalone mode where initial acquisition and connection can be achieved via the carriers, or carriers can be operated in a non-standalone mode where acquisition and connection can be achieved using a different carrier (e.g., a carrier of a different radio access technology).

[0129] The communication links 125 shown in wireless communication system 100 can include uplink transmissions from a UE 115 to a base station 105, or downlink transmissions from a base station 105 to a UE 115. Carriers can carry downlink or uplink communications (e.g., in an FDD mode), or can be configured to carry downlink and uplink communications (e.g., in a TDD mode).

[0130] A carrier can be associated with a specific bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth can be referred to as a “system bandwidth” of the carrier or wireless communications system 100. For example, the carrier bandwidth can be one of a number of determined bandwidths (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz)) of a specific radio access technology. Devices of wireless communications system 100 (e.g., base stations 105, UEs 115, or both) can have hardware configurations that support communications over the specific carrier bandwidths or can be configurable to support communications over one of a set of carrier bandwidths. In some examples, wireless communications system 100 can include base stations 105 or UEs 115 that support simultaneous communications via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 can be configured for operating over portions (e.g., a sub-band, a BWP) or all of a carrier bandwidth.

[0131] Signal waveforms transmitted over a carrier can be composed of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In OFDM systems, a resource element can 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 can depend on the modulation scheme (e.g., the order of the modulation scheme, the code rate of the modulation scheme, or both). Thus, the more resource elements that a UE 115 receives and the higher the order of the modulation scheme, the higher the data rates for the UE 115. A wireless communications resource can refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers or beams), and the use of multiple spatial layers can further increase the data rate for communications with a UE 115.

[0132] One or more parameter sets, which can include a subcarrier spacing (Af) and a cyclic prefix, can be supported for a carrier. A carrier can be partitioned into one or more BWPs with the same or different numerology. In some examples, a UE 115 can be configured with multiple BWPs. In some examples, a single BWP for a carrier can be active at a given time, and communications for the UE 115 can be limited to one or more active BWPs.

[0133] Time intervals for a base station 105 or UE 115 can be expressed in multiples of a basic time unit, which may, for example, be a sampling period of Ts=1 / (Δfmax·Nf) seconds, where Δfmax may represent the maximum supported subcarrier spacing, and Nf may represent the maximum supported size of a fast Fourier transform (FFT). Time intervals of a base station 105 can also be expressed in multiples of a basic time unit by s Ts=1 / (Δf max ·N f max·Nf) seconds, where Δfmaxmay represent the maximum supported subcarrier spacing, and Nf may represent the maximum supported size of a fast Fourier transform (FFT). Time intervals of a base station 105 can also be expressed in multiples of a basic time unit by max Ts=1 / (Δf fMaxSupportedDFTSize can represent the maximum supported discrete Fourier transform (DFT) size. Time intervals of the communications resources can be organized as radio frames, each radio frame having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame can be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0134] Each frame can include a plurality of consecutively numbered subframes or slots, and each subframe or slot can have a same duration. In some examples, a frame can be divided into subframes (e.g., in the time domain), and each subframe can be further divided into slots. Alternatively, each frame can include a variable number of slots, and the number of slots can depend on the subcarrier spacing. Each slot can include a number of symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period). In some wireless communications systems 100, a slot can be further divided into multiple mini-slots containing one or more symbols. Excluding the cyclic prefix, each symbol period can contain one or more (e.g., N f ) sampling periods. The duration of a symbol period can depend on the subcarrier spacing or the operating band.

[0135] A subframe, a slot, a mini-slot, or a symbol can be the smallest scheduling unit (e.g., in the time domain) of the wireless communications system 100 and can 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) can be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communications system 100 can be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)).

[0136] Physical channels can be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel can be multiplexed on a downlink carrier, for example, using one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. A control region (e.g., a control resource set (CORESET)) for a physical control channel can be defined in terms of a number of symbol periods and can extend across the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (e.g., CORESETs) can be configured for a set of UEs 115. For example, one or more of the UEs 115 can monitor or search the control region for control information according to one or more search space sets, and each search space set can include one or multiple control channel candidates arranged in an epilogical manner. An aggregation level for a control channel candidate can refer to a number of control channel resources (e.g., control channel elements (CCEs)) associated with encoded information for a control information format having a given payload size. A search space set can include common search space sets configured for sending control information to multiple UEs 115 and UE-specific search space sets configured for sending control information to a specific UE 115.

[0137] In some examples, a base station 105 can be movable and therefore provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies can overlap, but the different geographic coverage areas 110 can be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies can be supported by different base stations 105. The wireless communications system 100 can include, for example, a heterogeneous network in which different types of the base stations 105 provide coverage for various geographic coverage areas 110 using the same or different radio access technologies.

[0138] The wireless communications system 100 can be configured to support ultra-reliable communications or low-latency communications, or various combinations thereof. For example, the wireless communications system 100 can be configured to support ultra-reliable low-latency communications (URLLC) or mission critical communications. UEs 115 can be designed to support ultra-reliable, low-latency, or mission critical functions (e.g., mission critical function). Ultra-reliable communications can include private communication or group communication and can be supported by one or more mission critical services such as mission critical push-to-talk (MCPTT), mission critical video (MCVideo), or mission critical data (MCData). Support for mission critical functions can include prioritization of services, and mission critical services can be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission critical, and ultra-reliable low- latency can be used interchangeably herein.

[0139] In some examples, UE 115 can also be able to communicate directly with other UEs 115 over a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UEs 115 utilizing D2D communications can be within the geographic coverage area 110 of a base station 105. Other UEs 115 in such a group can be outside the geographic coverage area 110 of a base station 105 or be otherwise unserved by a base station 105. In some examples, groups of UEs 115 communicating via D2D communications can 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, a base station 105 facilitates the scheduling of resources for D2D communications. In other cases, D2D communications are carried out between UEs 115 without the involvement of a base station 105.

[0140] In some systems, the D2D communication link 135 can be an example of a communication channel, such as a sidelink communication channel, between vehicles (e.g., UEs 115). In some examples, vehicles can communicate using vehicle-to-everything (V2X) communications, vehicle-to-vehicle (V2V) communications, or some combination of these. A vehicle can signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information relevant to a V2X system. In some examples, vehicles in a V2X system can communicate with roadside infrastructure, such as roadside units, or with a network, or with both, via one or more network nodes (e.g., base stations 105) using vehicle-to-network (V2N) communications.

[0141] The core network 130 can provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 can be an evolved packet core (EPC) or 5G core (5GC), which can include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) and at least one user plane entity that routes packets or interconnects to external networks, such as a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), or a user plane function (UPF). The control plane entity can 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 can be transferred through the user plane entity, which can provide IP address allocation as well as other functions. The user plane entity can be connected to the IP services 150 of the one or more network operators. The IP services 150 can include access to the Internet, Intranet(s), an IP Multimedia Subsystem (IMS), or a Packet-Switched Streaming Service.

[0142] Some of the network devices, such as a base station 105, can include subcomponents such as an access network entity 140, which can be an example of an access node controller (ANC). Each access network entity 140 can communicate with UEs 115 through one or more other access network transmission entities 145, which can be referred to as radio heads, smart radio heads, or transmission / reception points (TRPs). Each access network transmission entity 145 can include one or more antenna panels. In some configurations, various functions of each access network entity 140 or base station 105 can be distributed across various network devices (e.g., radio heads and ANCs) or consolidated into a single network device (e.g., a base station 105).

[0143] The wireless communications system 100 can operate using one or more frequency bands, often in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band, since the wavelengths range from approximately one decimeter to one meter in length. The UHF region includes bands such as the 700 MHz, 800 MHz, 900 MHz, 1.4 GHz, 1.9 GHz, and 2.1 GHz bands. The region from 3 GHz to 30 GHz is known as the super-high frequency (SHF) region or centimeter band, since the wavelengths range from approximately one centimeter to one meter in length. The SHF region includes bands such as the 5 GHz band. The region from 30 GHz to 300 GHz is known as the extremely high frequency (EHF) region or millimeter band, since the wavelengths range from approximately one millimeter to one centimeter in length. The EHF region includes bands such as the 38 GHz and 60 GHz bands. The frequency bands used by the wireless communications system 100 can also include bands outside the UHF region, such as the 2.4 GHz and 5 GHz bands in the SHF region, and the 60 GHz band in the EHF region.

[0144] Wireless communications system 100 can utilize both licensed and unlicensed radio frequency spectrum bands. For example, wireless communications system 100 can employ License Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed frequency band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in unlicensed frequency

[0145] Base stations 105 or UEs 115 can be equipped with multiple antennas, which can be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. Base stations 105 or UEs 115 can use their multiple antennas to improve the reliability and throughput of communications. For instance, base stations 105 or UEs 115 can use beamforming to focus energy in a communication signal towards a receiving device. For example, a base station 105 can use beamforming to project energy towards a UE 115 to which the base station 105 is communicating. Similarly, a UE 115 can use beamforming to project energy towards a base station 105 with which the UE 115 is communicating. Antennas of base stations 105 or UEs 115 can be co-located at the same physical location (e.g., at an antenna assembly such as an antenna tower), or they can be located at different physical locations, such as in different antenna arrays or antenna panels. For example, one or more base station antennas or antenna arrays can be co-located at an antenna assembly such as an antenna tower. In some examples, antennas or antenna arrays associated with a base station 105 can be located at different geographic locations. A base station 105 can have an antenna array with a number of rows and columns of antenna ports that the base station 105 can use for beamforming in support of communications with UEs 115. Likewise, a UE 115 can have one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, an antenna panel can support radio frequency beamforming for signals transmitted via an antenna port.

[0146] Base stations 105 or UEs 115 can use MIMO communications to exploit multipath signal propagation and increase the spectral efficiency of wireless communications. Such techniques can be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by a transmitting device via different antennas or different combinations of antennas. Similarly, the multiple signals can be received by a receiving device via different antennas or different combinations of antennas. Each of the multiple signals can be referred to as a spatial stream, and can carry bits associated with the same data stream (e.g., a same codeword) or different data streams (e.g., different codewords). Different spatial layers can be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO), where multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO), where multiple spatial layers are transmitted to multiple devices.

[0147] Beamforming, which can also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that can be used at a transmitting device or a receiving device (e.g., a base station 105, a UE 115) to shape or steer a beam of energy in a specific direction along with the spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining the signals communicated by antennas of an antenna array such that signals transmitted or received with certain orientations (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation) experience constructive interference while others experience destructive interference. The combination of signals can be performed according to a beamforming weight set associated with a particular orientation. The beamforming weight set can include amplitude weights, phase weights, or both. The beamforming weight set can be defined such that signals transmitted or received with the beam oriented in a particular direction exhibit a desired signal characteristic such as a signal strength that is maximized (or maximally improved), a signal-to-noise ratio that is maximized (or maximally improved), a noise figure that is minimized (or minimized), or some other signal characteristic.

[0148] The base stations 105 or UEs 115 can use beamforming techniques as part of an effort to reduce or minimize interference. For example, a transmitting device (e.g., a base station 105) can apply beamforming to direct a transmitted signal in a desired direction, such as a direction of a receiving device (e.g., a UE 115). The transmitting device can use multiple antennas to conduct the beamforming.

[0149] Some signals, such as data signals associated with a particular receiving device, can be transmitted by a base station 105 in a single beam direction (e.g., a direction associated with the receiving device, such as a UE 115). In some examples, the beam direction associated with transmissions along a single beam direction can be determined based on a signal that was transmitted in one or more beam directions. For example, a UE 115 can receive one or more of the signals transmitted by the base station 105 in different directions and can report to the base station 105 an indication of the signal that the UE 115 received with a highest signal quality, or other acceptable signal quality.

[0150] In some examples, transmissions by a device (e.g., by a base station 105 or a UE 115) can be performed using multiple beam directions, and the device can use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from a base station 105 to a UE 115). A UE 115 can report feedback that indicates precoding weights for one or more beam directions, and the feedback can correspond to a configured number of beams across a system bandwidth or one or more sub-bands. A base station 105 can transmit reference signals (e.g., a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS)) that can be precoded or unprecoded. A UE 115 can provide feedback for beam selection, which can be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-panel type codebook, a linear combination type codebook, a port selection type codebook). Although these techniques are described with reference to signals transmitted in one or more directions by a base station 105, a UE 115 can employ similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE 115) or for transmitting a signal in a single direction (e.g., for transmitting data to a receiving device).

[0151] A receiving device (e.g., a UE 115) can try multiple receive configurations (e.g., directional listening) when receiving various signals from base stations 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device can try multiple receive directions by differentially rotating a polarization plane of an antenna over time, measuring for signals received in different receive directions, or any combination thereof. In some examples, the receiving device can use a single receive configuration to receive signals along a single beam direction (e.g., when receiving a data signal). The single receive configuration can be aligned in a beam direction determined based on listening in different receive directions (e.g., a beam direction determined to have a highest signal strength, highest signal-to-noise ratio (SNR), or otherwise acceptable signal quality based on listening in multiple beam directions).

[0152] The wireless communications system 100 can be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer can be IP -based. A Radio Link Control (RLC) layer can perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer can perform priority handling and multiplexing of logical channels into transport channels. The MAC layer can also use error detection techniques, error correction techniques, or both, to support retransmissions by the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer can provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a base station 105 or core network 130 supporting radio bearers for user plane data. At the physical layer, transport channels can be mapped to physical channels.

[0153] The UEs 115 and the base stations 105 can support retransmissions of data to increase the likelihood that data is received successfully. Hybrid automatic repeat request (HARQ) feedback is one technique used to increase the likelihood that data is received successfully. HARQ can include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., request-based ARQ). HARQ can improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions). In some examples, a device can support same-slot HARQ feedback, where the device can provide HARQ feedback in a specific time slot for data received in a previous time slot. In other cases, the device can provide HARQ feedback in a subsequent time slot or according to some other time interval.

[0154] The UEs 115 of the wireless communications system 100 can support techniques for sidelink resource cancellation (e.g., sidelink resource release). Specifically, the UEs 115 of the wireless communications system 100 can be configured to release sidelink resources previously reserved for a sidelink transmission via a SCI message. By enabling sidelink resources previously reserved for a sidelink transmission, the techniques described herein can provide for more efficient use of sidelink resources and improved spectral efficiency.

[0155] For example, a first UE 115 of the wireless communications system 100 can transmit a first SCI message to a second UE 115 reserving resources for a sidelink transmission from the first UE 115 to the second UE 115. In some cases, the reserved sidelink resources can include resources within the same slot as the first SCI message for the initial sidelink transmission, as well as resources in subsequent slots for retransmissions of the sidelink transmission at one or more retransmission occasions. In cases where the first transmission of the sidelink transmission is not successfully received by the second UE 115, the previously reserved sidelink resources can be used to perform a retransmission of the sidelink transmission. However, in cases where the first transmission of the sidelink transmission is successfully received by the second UE 115, the previously reserved sidelink resources can not be needed for a retransmission. In such cases, the first UE 115 and / or the second UE 115 can transmit a second SCI message that can be interpreted as releasing the sidelink resources reserved by the first SCI message.

[0156] In some cases, the second SCI message can have the same format as the first SCI message (e.g., SCI1, SCI2). In other cases, the first and second SCI messages have different formats. In some aspects, the second SCI message indicating the release of the previously reserved sidelink resources can include one or more TDRA field values reserving additional sidelink resources for the sidelink communication. For example, the second SCI message can include one or more TDRA field values reserving a second set of resources for retransmissions of the second sidelink transmission (e.g., resources for retransmissions of a physical sidelink shared channel (PSSCH), resources for retransmissions of the second SCI message). The one or more TDRA field values within the second SCI message to indicate the additional sidelink resource reservation can include a TRIV that is not related to a time resource reservation (e.g., an “unspecified” TRIV).

[0157] In some aspects, a UE 115 receiving the second SCI message indicating the release of sidelink resources (e.g., the first UE 115 and / or the second UE 115) can be configured to determine that the release of the sidelink resources indicated by the second SCI message is associated with the sidelink resources reserved by the first SCI message based on an explicit indicator within the first SCI message and / or the second SCI message, based on a configured or determined relationship between the first SCI message and the second SCI message, or based on both. For example, in some cases, the first and second SCI messages can each include a transmission identifier and / or a reception identifier associated with the first UE 115 and / or the second UE 115, respectively. In such cases, the UE 115 receiving the second SCI message can be configured to determine that the second SCI message is associated with the release of the sidelink resources reserved by the first SCI message based on the corresponding transmission / reception identifier.

[0158] By way of another example, the first UE 115 and / or the second UE 115 can be configured with (e.g., via RRC signaling) a predefined relationship between the first SCI message and the second SCI message. For example, the UE 115 can be configured to determine a preconfigured relationship between the first SCI and the second SCI (e.g., the second SCI is three time slots after the second SCI and within the same subchannel) such that a UE 115 receiving the second SCI message can be configured to determine that the second SCI message is associated with a release of sidelink resources reserved by the first SCI message based on the preconfigured relationship.

[0159] The techniques described herein can more efficiently use sidelink resources and improve spectral efficiency. Specifically, by enabling a UE 115 to cancel (e.g., release) sidelink resources previously reserved for a sidelink transmission, the techniques described herein can reduce the number of wasted sidelink resources that can not be used in the case of a successful sidelink transmission, thereby more efficiently using sidelink resources within the wireless communications system 100.

[0160] Figure 2 An example of a wireless communications system 200 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is illustrated. In some instances, the wireless communications system 200 can implement aspects of the wireless communications system 100. The wireless communications system 200 can include a UE 115-a and a UE 115-b, which can each include the examples of a UE 115 described with reference to Figure 1 The examples of a UE 115 described.

[0161] In some cases, the wireless communications system 200 can be an example of a V2X wireless communications system. The UE 115-a, the UE 115-b, or both can be examples of a vehicle-UE 115 (V-UE), a pedestrian-UE 115 (P-UE), a road-side unit, a transmission / reception point (TRP), or another device operating in a V2X wireless communications system. In some cases, the UE 115 can be served by one or more base stations 105, one or more road-side units, or any combination thereof.

[0162] UE 115-a and UE 115-b can communicate directly over a wireless channel of a wireless communication system. For example, UE 115-a and UE 115-b can communicate over a sidelink channel 205. In some cases, the sidelink channel 205 can include resources for a physical sidelink control channel (PSCCH) 210, a PSSCH 215, one or more gaps 220 (e.g., gap 220-a and gap 220-b), and a physical sidelink feedback channel (PSFCH) 225. In some cases, the PSFCH 225 can be positioned between gap 220-a and gap 220-b (e.g., in the time domain). The sidelink channel 205 can span multiple subcarriers. For example, the sidelink channel 205 can span up to 27 subchannels, each including ten or more resource blocks. In other examples, the sidelink channel 205 can include more or fewer subchannels, and in still other examples, the number of resource blocks per subchannel can likewise vary.

[0163] To transmit a sidelink transmission to UE 115-b, UE 115-a can reserve resources on the sidelink channel 205. In some cases, UE 115-a can determine a resource allocation. For example, UE 115-a can autonomously decide resources for a sidelink communication. In some other examples, a base station 105 can configure a resource allocation for UE 115-a. For example, the base station 105 can transmit a resource assignment for sidelink resources through downlink control information.

[0164] In an example, UE 115-a can transmit a first SCI message on the PSCCH 210 to reserve one or more resources for a sidelink data transmission. In some cases, UE 115-a can transmit the SCI message in a first slot of the PSCCH 210. The first slot can include sidelink shared channel resources for the sidelink data transmission. In some cases, UE 115-a can reserve one or more additional resources (e.g., slots on the sidelink channel 205) for retransmission of the sidelink data transmission. For example, the first SCI message can reserve two additional slots on the PSSCH 215.

[0165] The first SCI message can include an example of a first type of SCI message (e.g., SCI1). The first type of SCI message can be decoded by all UEs 115 using the sidelink channel 205 to detect reserved resources and avoid collisions. The first type of SCI message can include an indication of a traffic priority, an indication of a demodulation reference signal (DMRS) pattern, an indication of a TDRA field value, an indication of a frequency domain resource allocation (FDRA) field value, an indication of a resource reservation period, or any combination thereof. For example, the indication of a traffic priority can be three bits. In some cases, the first type of SCI message can include a format for a second type of SCI message (e.g., SCI2), a beta offset for a rate matching the second type of SCI message, an indication of a DMRS port, an indication of a modulation and coding scheme (MCS), an MCS table, a number of reserved bits, and a PSFCH overhead indicator, or any combination thereof.

[0166] The FDRA indication and the TDRA indication can include a number of bits based on a number of slot reservations and a number of sub-channels of the reserved resources. For example, the TDRA indication can include five bits for two reservations or nine bits for three reservations. The TRIV in the first SCI message can indicate time domain resource allocation for retransmission resources. For example, the TRIV in the first type of SCI message can include nine bits for three reservations, including a first slot (to) with the first SCI message and an initial transmission, a second slot (ti) for a first retransmission resource, and a third slot (t3) for a second retransmission resource. In some cases, the TRIV can be determined based on ti being between 1 and 30, inclusive, and t2 being greater than ti and less than or equal to 31. For one transmission (e.g., no reserved retransmission resources), the TRIV can be set to 0. For two transmissions (e.g., one reserved retransmission resource), the TRIV can be set to a value of {1,..., 31}. For three transmissions (e.g., two reserved retransmission resources), the TRIV can be set to a value of {32,..., 496}. In some wireless communication systems, remaining values {497,..., 511} can be unspecified. In some implementations, the UE 115-a can use one of these remaining values (e.g., TRIV {497,..., 511}) for a special purpose. For example, the techniques described herein can utilize an unspecified TRIV within an SCI message indicating a release of previously reserved sidelink resources in order to reserve an additional set of sidelink resources for retransmission of a sidelink transmission.

[0167] The first type of SCI message can be decoded by any receiver, including the intended receiver and other sidelink UEs 115, using the sidelink channel 205 to allow for channel sensing and avoid resource collisions. To receive a sidelink data transmission, UE 115-b can perform blind decoding on sidelink sub-channels of the sidelink channel 205 to receive the first SCI message. UE 115-b can identify the reserved resources based on the TDRA indication and the FDRA indication and attempt to decode the sidelink data transmission. In some cases, UE 115-b can not successfully obtain the sidelink data transmission. In this case, UE 115-a can retransmit the sidelink data transmission within the resources reserved for retransmission. UE 115-b can monitor the resources reserved for retransmission and attempt to receive the retransmitted sidelink data. After UE 115-b successfully obtains the sidelink data, UE 115-b can transmit an acknowledgement (ACK) to UE 115-a (e.g., on the PSFCH 225).

[0168] In some cases, UE 115-b can successfully receive the sidelink data from the initial transmission. However, UE 115-a can have reserved one or more retransmission resources via the first SCI message. In some wireless communications systems, these resources can not be used, which reduces channel utilization and spectral efficiency. Accordingly, the wireless communications systems described herein, such as wireless communications systems 100 and 200, can implement techniques for efficiently releasing previously reserved resources in order to improve resource utilization.

[0169] For example, if UE 115-b successfully receives the sidelink data prior to the one or more retransmission resources, the unused retransmission resources can be released. For example, UE 115-a and / or UE 115-b can cancel / release the previously reserved sidelink resources so that other UEs 115 can reserve and use these resources. In some cases, UE 115-a and / or UE 115-b can transmit a second SCI message indicating that the previously reserved sidelink resources are to be released. In some aspects, a UE 115 (e.g., UE 115-a and / or UE 115-b) receiving the second SCI message (e.g., first UE 115-a and / or second UE 115-b) can be configured to determine that the release of the sidelink resources indicated by the second SCI message is associated with the resources reserved by the first SCI message based on an explicit indicator (e.g., a transmission identifier, a reception identifier) within the first SCI message and / or the second SCI message, based on a configured or determined relationship between the first SCI message and the second SCI message (e.g., a range of resources allocated for the second SCI message relative to the first SCI message, a preconfigured relationship between the first SCI message and the second SCI message), or both.

[0170] The techniques described herein can more efficiently use sidelink resources and improve spectral efficiency. Specifically, by enabling the UE 115-a and / or the UE 115-b to cancel (e.g., release) sidelink resources previously reserved for a sidelink transmission, the techniques described herein can reduce the number of wasted sidelink resources that can not be used in the case of a successful sidelink transmission, thereby more efficiently using sidelink resources within the wireless communications system 200.

[0171] Figure 3 An example of a resource reservation scheme 300 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is illustrated. In some examples, the resource reservation scheme 300 can implement or be implemented by aspects of the wireless communications system 100, the wireless communications system 200, or both.

[0172] The first UE 115 can schedule a sidelink transmission to the second UE 115 on a wireless channel. To transmit the sidelink transmission, the first UE 115 can reserve initial sidelink resources 305. The first UE 115 can transmit a first SCI message and an initial transmission of sidelink data using the initial sidelink resources 305. The first SCI message can also reserve one or more retransmission sidelink resources 310 (e.g., retransmission occasions) for retransmission of the sidelink data. For example, the first SCI can indicate a retransmission sidelink resource 310-a (e.g., a first retransmission occasion) and a retransmission sidelink resource 310-b (e.g., a second retransmission occasion). If the second UE 115 does not receive the initial transmission via the initial sidelink resources 305, the first UE 115 can retransmit the sidelink data (e.g., the sidelink transmission) using the retransmission sidelink resources 310.

[0173] In some cases, the second UE 115 can successfully receive the sidelink data from the initial transmission on the initial sidelink resources 305. In this case, although the retransmission sidelink resources 310 are unnecessary for retransmission due to the successful transmission and reception of the sidelink data (e.g., the sidelink transmission) via the initial sidelink resources 305, the retransmission sidelink resources 310 can still be reserved for retransmission. Accordingly, to improve the efficient use of sidelink resources, the techniques described herein support releasing previously reserved resources (e.g., the retransmission sidelink resources 310) via a SCI message. The techniques described herein additionally involve using a TDRA field value in a release / cancel SCI message to reserve an additional set of retransmission sidelink resources 310 (e.g., retransmission sidelink resources 310-c).

[0174] For example, as described previously herein, the first UE 115 can transmit a first SCI message to the second UE 115 via the initial sidelink resources 305. In some cases, the first SCI message can be associated with (e.g., schedule) a first sidelink transmission from the first UE 115 to the second UE 115. In some aspects, the first SCI message indicates a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions. For example, the first SCI message can reserve retransmission sidelink resources 310-b and 310-c for retransmission of the first sidelink transmission. In some cases (e.g., where the first sidelink transmission is successfully received by the second UE 115), the first UE 115 and / or the second UE 115 can transmit a second SCI message on the sidelink resources 315 to cancel or release at least a subset of the previously reserved sidelink resources (e.g., cancel or release retransmission sidelink resources 310-a and / or 310-b). For example, the second SCI message can provide a release of retransmission sidelink resources 310-a and / or retransmission sidelink resources 310-b. In some cases, the first SCI message and the second SCI message can each be a first type of SCI message (e.g., have a common format, such as SCI1, SCI2, or both). In some other examples, the first SCI message can be an example of a first type of SCI (e.g., SCI1), and the second SCI message can be an example of a second type of SCI (e.g., SCI2), or vice versa.

[0175] In some cases, the sidelink resource 315 carrying the second or cancelation SCI message can be selected to facilitate resource cancelation or release. For example, the sidelink resource 315 can correspond to slot no and subcarrier j. The released resource can have been reserved by the first SCI message transmitted in slot nl and subchannel k, occupying Ml subchannels. Additionally or alternatively, the sidelink resource 315 can be associated with a configured relationship (e.g., an RRC configured relationship) with respect to the initial sidelink resource 305. In some cases, the earliest retransmission sidelink resource 310-a and / or 310-b released by the second SCI message transmitted via the sidelink resource 315 can be located at no + n3, where n3 can be a number of slots based on a PSSCH preparation time. For example, the second SCI message can be transmitted at least n3 slots before the released retransmission sidelink resource 310-a and / or 310-b, which can ensure that other UEs 115 using the sidelink channel can process the PSSCH and use the resource. In some cases, the sidelink resource 315 can be at least n2 slots after the initial sidelink resource 305. The number of slots n2 can be based on a feedback timing (e.g., a HARQ configuration) of the first UE 115, the second UE 115, or both. For example, n2 can be a number of slots for the second UE 115 to determine that the initial sidelink data transmission was successfully received, transmit feedback (e.g., an acknowledgement), and for the first UE 115 to receive the feedback.

[0176] In some aspects, the second SCI message transmitted via the sidelink resource 315 can include one or more TDRA field values indicating a second set of resources reserved for retransmission of the second sidelink transmission. For example, as shown, the second SCI message can include one or more TDRA fields indicating the retransmission sidelink resource 310-c reserved for retransmission of the second sidelink transmission. Specifically, the retransmission sidelink resource 310-c reserved by the second SCI message can be reserved for retransmission of the second SCI message itself, the second sidelink data transmission (e.g., a PSSCH transmission), or both. In some aspects, the one or more TDRA field values indicating the second set of resources (e.g., the TDRA field values for reserving the retransmission sidelink resource 310-c) can include one or more TRIVs that are independent of time resource reservations. In this regard, the one or more TDRA field values indicating the retransmission sidelink resource 310-c can include one or more unspecified TRIVs and / or unspecified TDRA field values. Figure 3

[0177] ​For example, in addition to the second SCI message providing a release of the retransmission sidelink resources 310-a and / or 310-b, the second SCI message can further include one or more TDRA field values that reserve retransmission sidelink resources 310-c for retransmission of the second sidelink transmission. In some cases, the one or more TDRA field values can include an unspecified TRIV. For example, as described previously herein, some wireless communications systems can support TRIVs from 0 to 511 (e.g., {0,..., 511}), where TRIVs from 0 to 496 (e.g., {0,..., 496}) are used to indicate reservation of time resources, leaving TRIVs from 497 to 511 (e.g., {497,..., 511}) not used to indicate reservation of time resources. Thus, in some aspects, the techniques described herein can utilize the unspecified TRIVs (e.g., {497,..., 511}) within the second SCI message to indicate a second set of resources reserved for retransmission (e.g., to indicate retransmission sidelink resources 310-c).

[0178] In some aspects, the UE 115 can be configured to determine, based on explicit signaling within the first SCI message and / or the second SCI message, based on a preconfigured relationship between the second SCI message and the first SCI message, and / or the retransmission resources (e.g., retransmission sidelink resources 310) that are released, or any combination thereof, that the second SCI message is associated with a release of resources reserved by the first SCI message. This will be discussed in more detail herein with respect to Figure 5 In more detail.

[0179] Figure 4 An example of a resource reservation scheme 400 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is illustrated. In some examples, resource reservation scheme 400 can implement aspects of, or be implemented by, wireless communications system 100, wireless communications system 200, resource reservation scheme 300, or any combination thereof.

[0180] The first UE 115 can schedule a sidelink transmission to the second UE 115 on a wireless channel. To transmit the sidelink transmission, the first UE 115 can reserve initial sidelink resources 405 (e.g., initial sidelink resources 405-a). The first UE 115 can transmit a first SCI message and an initial transmission of sidelink data using the initial sidelink resources 405-a. The first SCI message can also reserve one or more retransmission sidelink resources 410 for retransmission of the sidelink data. For example, as described previously herein, the first SCI message can reserve the retransmission sidelink resources 410-a and / or 410-b. Figure 4As shown, the first SCI message transmitted via the initial sidelink resource 405-a can indicate the retransmission sidelink resources 410-a and 410-b. If the second UE 115 does not receive the initial sidelink transmission associated with the first SCI message transmitted via the initial sidelink resource 405-a, the first UE 115 can use the retransmission sidelink resources 410-a and 410-b to retransmit the sidelink transmission. Conversely, if the first sidelink transmission is successfully received by the second UE 115, the second SCI message transmitted via the sidelink resource 415 can be used to cancel or release the retransmission sidelink resources 410-a and / or 410-b.

[0181] In some cases, the sidelink channel can include multiple SCI messages that schedule sidelink transmissions on the sidelink channel. For example, as shown in FIG. 4, the sidelink channel can include a first SCI message transmitted via an initial sidelink resource 405-a, a second SCI message transmitted via a sidelink resource 415, and a third SCI message transmitted via a sidelink resource 420. Figure 4 As shown, the SCI message transmitted via the initial sidelink resource 405-a can reserve the retransmission sidelink resources 410-a and 410-b, and the SCI message transmitted via the initial sidelink resource 405-b can reserve the retransmission sidelink resources 410-c and 410-d. In this case, a UE 115 that identifies the second SCI message transmitted via the sidelink resource 415 can be configured to determine whether the second SCI message is associated with the SCI message transmitted via the initial sidelink resource 405-a or the SCI message transmitted via the initial sidelink resource 405-b. In other words, the UE 115 can be configured to determine whether the SCI message transmitted via the sidelink resource 415 is associated with the retransmission sidelink resources 410-a and / or 410-b or the release of the retransmission sidelink resources 410-c and 410-d.

[0182] In some aspects, a UE 115 can be configured to determine that the second SCI message is associated with the release of the resources reserved by the first SCI message based on explicit signaling within the first SCI message and / or the second SCI message, based on a preconfigured relationship between the second SCI message and the first SCI message, and / or the released retransmission resources (e.g., the retransmission sidelink resources 410), or any combination thereof. This will be discussed in more detail herein with respect to Figure 5 In some aspects, a UE 115 can be configured to determine that the second SCI message is associated with the release of the resources reserved by the first SCI message based on explicit signaling within the first SCI message and / or the second SCI message, based on a preconfigured relationship between the second SCI message and the first SCI message, and / or the released retransmission resources (e.g., the retransmission sidelink resources 410), or any combination thereof. This will be discussed in more detail herein with respect to

[0183] Figure 5 An example of a process flow 500 that supports techniques for sidelink resource cancellation using TDRA is illustrated in accordance with aspects of the present disclosure. In some examples, process flow 500 can implement aspects of wireless communications system 100, wireless communications system 200, resource reservation scheme 300, resource reservation scheme 300, or any combination thereof. For example, process flow 500 can illustrate a UE 115 receiving a first SCI message that reserves a set of retransmission resources, and a second SCI message that releases the set of retransmission resources. Figures 1 to 4The described first UE 115-c transmits a first SCI message reserving a first set of resources for a retransmission of a first sidelink transmission, identifies a second SCI message associated with a release of at least a subset of the first set of resources, and other aspects. Process flow 500 can include the first UE 115-c, the second UE 115-d, and the base station 105-b, which can be as described with reference to FIGs. 1-4. Figures 1 to 4 Examples of the described UE 115 and base station 105.

[0184] In some examples, the operations illustrated in process flow 500 can be performed by hardware (e.g., including circuitry, processing blocks, logic components, and other components), code (e.g., software or firmware) executed by a processor, or any combination thereof. Alternative examples of the following can be implemented, where some steps are performed in a different order than described or are not performed at all. In some cases, steps can include additional features not mentioned below, or additional steps can be added.

[0185] At 505, the first UE 115-c, the second UE 115-d, or both can receive a control message (e.g., an RRC message, a downlink control information (DCI) message). In some aspects, the UEs 115-c and / or 115-d can receive the control message from the base station 105-b. In some aspects, the control message can indicate a relationship between a second SCI message associated with a release of previously reserved resources and a first SCI message reserving the resources, a relationship between the second SCI message associated with the release and the released resources themselves, a configured interval or range of resources in which the second SCI message can be received, or any combination thereof.

[0186] For example, as Figure 3 As illustrated, the control message can indicate a relationship between the sidelink resources 315 (e.g., the sidelink resources 315 for transmitting the second SCI message) and the initial sidelink resources 305 (e.g., the initial sidelink resources 305 for transmitting the first SCI message). Additionally or alternatively, the control message can indicate a relationship between the sidelink resources 315 (e.g., the sidelink resources 315 for transmitting the second SCI message) and the retransmission sidelink resources 310-a and / or 310-b (e.g., the retransmission sidelink resources 310 for retransmitting the first sidelink transmission).

[0187] The relationship can indicate a relationship between the second SCI message and the first SCI message and / or sidelink resources released in the time domain, the frequency domain, or both. In some aspects, the control message can indicate a range of time resources and / or a range of frequency resources in which the second SCI message can be transmitted or received. The range of time and / or frequency resources in which the second SCI message can be transmitted or received can be defined with respect to resources used for the first SCI message, resources to be released, or both.

[0188] In some aspects, the control message received at 505 can additionally or alternatively indicate a set of TRIVs. For example, the control message can include an indication of a set of TRIVs (e.g., TRIV {0,..., 511}) that includes a first subset of TRIVs (e.g., TRIV {0,..., 496}) associated with time resource reservations and a second subset of TRIVs (e.g., TRIV {497,..., 511}) that are not associated with time resource reservations. In this regard, the base station 105-b can indicate to the UEs 115-c and 115-d which TRIVs are used for time resource reservations (e.g., which TRIVs are designated) and which TRIVs are not used for time resource reservations (e.g., which TRIVs are not designated). Alternatively, the UEs 115 can determine which TRIVs are designated and which TRIVs are not designated by a pre-configuration (e.g., by the number of bits of the TDRA and the number of reservations allowed).

[0189] At 510, the first UE 115-c can transmit a first SCI message to the second UE 115-d. The first SCI message can be transmitted during a first transmission time interval (e.g., a first slot). In some aspects, the first SCI message can be associated with a first sidelink transmission (e.g., a PSSCH transmission) from the first UE 115-c to the second UE 115-d. In some aspects, the first SCI message can include a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions.

[0190] For example, as Figure 3As shown, the first UE 115-c can transmit, via the initial sidelink resources 305, a first SCI message during a first transmission time interval (e.g., a first slot), where the first SCI message includes a first indication of the retransmission sidelink resources 310-a and 310-b. In this example, the retransmission sidelink resources 310-a can include a first retransmission occasion for retransmitting the first sidelink transmission, and the retransmission sidelink resources 310-b can include a second retransmission occasion for retransmitting the first sidelink transmission. In some aspects, the first SCI message can include an identifier (e.g., transmitter identifier (ID), receiver ID) that associates the first SCI message with the first UE 115-c, the second UE 115-d, or both.

[0191] At 515, the first UE 115-c can transmit, to the second UE 115-d, a first sidelink transmission (e.g., a sidelink data transmission, a PSSCH transmission) associated with the first SCI message. In some aspects, the first UE 115-c can transmit the first sidelink transmission based on transmitting the first SCI message. For example, the first SCI message can schedule the first sidelink transmission from the first UE 115-c to the second UE 115-d. In this regard, the first UE 115-c can transmit the first sidelink transmission (e.g., a PSSCH transmission) to the second UE 115-b in accordance with the first SCI message. In some cases, the first UE 115-c can transmit the first sidelink transmission during the first transmission time interval or a subsequent transmission time interval in which the first SCI message is transmitted.

[0192] At 520, the second UE 115-d can transmit, to the first UE 115-c, a feedback message (e.g., an acknowledgement (ACK), a negative acknowledgement (NACK)). In some aspects, the second UE 115-c can transmit the feedback message at 520 based on receiving (or not receiving) the first sidelink transmission at 515. For example, the second UE 115-d can transmit a NACK to the first UE 115-c in the case that the second UE 115-d does not successfully receive the first sidelink transmission at 515. In this example, the feedback message (e.g., the NACK) can indicate that the second UE 115-d did not successfully receive the first sidelink transmission. Conversely, by way of another example, the second UE 115-d can transmit an ACK to the first UE 115-c in the case that the second UE 115-d does successfully receive the first sidelink transmission at 515. In this example, the feedback message (e.g., the ACK) can indicate that the second UE 115-d did successfully receive the first sidelink transmission.

[0193] At 525, the first UE 115-c, the second UE 115-c, or both can identify a set of resources (e.g., time resources, frequency resources) on which a second SCI message can or can not be transmitted or received. In this regard, the UEs 115-c and / or 115-d can identify when a second SCI message can be transmitted or received that releases (e.g., cancels) resources reserved by the first SCI message. In this regard, the UEs 115 can identify a configured resource range (e.g., a configured time resource range, a configured frequency resource range) in which the second SCI message can be transmitted and / or received. In some cases, the configured resource range on which the second SCI message can be transmitted / received can be defined relative to resources used to transmit the first SCI message (e.g., a first transmission time interval (first slot) during which the first SCI message is transmitted, a subchannel on which the first SCI message is transmitted). Additionally or alternatively, the configured resource range on which the second SCI message can be transmitted / received can be defined relative to resources of the reserved retransmission occasion (e.g., a transmission time interval (slot) of the retransmission occasion, a subchannel of the retransmission occasion).

[0194] Accordingly, the first UE 115-c, the second UE 115-d, or both can identify a set of resources on which a second SCI message can or can not be transmitted or received based on receiving the control message at 505, transmitting or receiving the first SCI message at 510, transmitting or receiving the first sidelink transmission at 515, transmitting or receiving the feedback message at 520, or any combination thereof.

[0195] For example, the first UE 115-c, the second UE 115-d, or both can identify a time period before a first retransmission occasion of the one or more retransmission occasions associated with the first SCI message during which at least the first retransmission occasion is to not be released. For example, as shown, the first UE 115-c and / or the second UE 115-d can determine a time period n3 (e.g., a retransmission occasion) before the retransmission sidelink resource 310-a during which at least the retransmission sidelink resource 310-a is to not be released. By way of another example, the first UE 115-c, the second UE 115-d, or both can identify a time period after transmission of the first SCI message during which the one or more retransmission occasions are to not be released. For example, as shown, the first UE 115-c and / or the second UE 115-d can determine a time period n4 after the transmission of the first SCI message during which at least the retransmission sidelink resource 310-a is to not be released. Figure 3 Figure 3 ​As shown, the first UE 115-c and / or the second UE 115-d can determine a time period n2 after the first SCI message is transmitted via the initial sidelink resources 305 in which one or more retransmission occasions (e.g., retransmission sidelink resources 310-a and / or 310-b) scheduled by the first SCI message are not to be released. In some cases, the determined time period can be based on a HARQ configuration associated with the sidelink communication. For example, the HARQ configuration can specify that a feedback time interval for providing feedback for a sidelink transmission includes two slots. In this example, the time period (e.g., time period n2 illustrated in FIG. 3) after the first SCI message can include at least two slots based on the feedback time interval associated with the HARQ configuration. Figure 3

[0196] At 530, the first UE 115-c, the second UE 115-d, or both can transmit a second SCI message associated with the first SCI message. In some aspects, the second SCI message can be transmitted during a second transmission time interval (e.g., a second slot) after a first transmission time interval in which the first SCI message is transmitted. In some aspects, the second SCI message can provide a release of at least a subset of a first set of resources reserved by the first SCI message for retransmissions of the first sidelink transmission, where the release relates to at least one of the one or more retransmission occasions. For example, as shown, the second SCI message transmitted via the sidelink resources 315 can provide a release of the retransmission sidelink resources 310-a (e.g., the first retransmission occasion), the retransmission sidelink resources 310-b (e.g., the second retransmission occasion), or both. Figure 3

[0197] In some aspects, the second SCI message can include one or more TDRA field values indicating a second set of resources reserved for retransmissions of the second sidelink transmission. The second set of resources can include one or more retransmission occasions for retransmissions of the second sidelink transmission. In some cases, the second SCI message can include one or more TDRA field values including one or more TRIVs that are not related to time resource reservation (e.g., TDRA values including TRIVs between 497 and 511). In some aspects, the second SCI message can be transmitted with a specified priority that is greater than a priority associated with other transmissions. In this regard, the second SCI message can have a higher priority because a receiving device (e.g., the first UE 115-c, the second UE 115-d) is configured to receive and / or decode the second SCI message before other transmissions.

[0198] ​​In some aspects, the UE 115 can be configured (e.g., via RRC signaling) to interpret the TDRA field values (e.g., TRIVs) based on one or more indices or lookup tables to release one or more retransmission occasions. For example, the UE 115 can be configured to reference one or more lookup tables to determine that a first unscheduled TRIV value indicates a release of a first subset of retransmission occasions and a second unscheduled TRIV value indicates a release of a second subset of retransmission occasions.

[0199] In some cases, the number of retransmission occasions within the second set of resources reserved for retransmissions of the second sidelink transmission that can be reserved by the one or more TDRA field values can be limited. However, as will be discussed in further detail herein, additional fields of the first and / or second SCI messages (e.g., FDRA field, DMRS field, DMRS port field, sidelink priority field, PSFCH overhead field) can be reinterpreted to indicate resource reservations and, thus, can expand the number of retransmission occasions within the second set of resources that can be reserved.

[0200] The UE 115 can transmit the second SCI message based on receiving the control message at 505, transmitting or receiving the first SCI message at 510, transmitting or receiving the first sidelink transmission at 515, transmitting or receiving the feedback message at 520, identifying resources in which the second SCI message can be transmitted or received at 525, or any combination thereof. For example, in a case that the first UE 115-c receives the feedback message at 520 indicating that the first sidelink transmission was successfully received by the second UE 115-d, the first UE 115-c can transmit the second SCI message at 530 based on receiving the feedback message. By way of another example, in a case that the second UE 115-d successfully receives the first sidelink transmission at 515, the second UE 115-d can transmit the second SCI message to the first UE 115-c, where the second SCI message releases and / or cancels at least one retransmission occasion reserved for retransmissions of the first sidelink control information.

[0201] In some aspects, the first UE 115-c can prioritize resources that can be used to transmit the second SCI message, while the second UE 115-d (and / or other UEs 115) can de-prioritize resources that can be used to transmit the second SCI message. For example, a UE 115 can identify a set of candidate resources for transmitting the second SCI message based on transmitting the first SCI message. In this example, the UE 115 can determine that the set of candidate resources has a higher priority than a set of candidate resources selected for transmitting other sidelink transmission messages. Continuing the same example, the UE 115 can select a set of resources from the set of candidate resources for transmitting the second SCI message based on the set of candidate resources having the higher priority. By way of another example, a UE 115 can identify a set of candidate resources for transmitting the second SCI message based on receiving the first SCI message. In this example, the UE 115 can determine that the set of candidate resources has a lower priority than a set of candidate resources selected for transmitting other sidelink transmission messages, and can refrain from selecting a set of resources from the set of candidate resources for transmitting the other sidelink transmission messages based on the set of candidate resources having the lower priority.

[0202] At 535, the first UE 115-c, the second UE 115-d, or both can identify the second SCI message. In some aspects, it can be said that the first UE 115-c and / or the second UE 115-d identifies the second SCI message by transmitting the second SCI message, by receiving the second SCI message, or both. For example, from the perspective of the first UE 115-c, the first UE 115-c can identify the second SCI message at 535 by transmitting the second SCI message at 530, by receiving the second SCI message at 530, or both.

[0203] In some aspects, the UE 115 can identify the second SCI message at a time period that is within or outside of a time interval in which the second SCI message can be received or can not be received, as determined at 525. For example, in a case where the UE 115 identifies a time period in which at least a first retransmission occasion will not be released before the first retransmission occasion of the one or more retransmission occasions, the second SCI message can be identified (e.g., transmitted or released) before the identified time period begins. By way of another example, in a case where the UE 115 identifies a time period in which at least a first retransmission occasion will not be released after transmission of the first SCI message, the second SCI message can be identified (e.g., transmitted or released) after the identified time period ends.

[0204] At 540, the first UE 115-c, the second UE 115-d, or both may identify one or more TDRA field values ​​within the second SCI message, which indicate a second resource set reserved for retransmission of the second sidelink transmission (e.g., Figure 3 (Refer to the retransmission side link resource 310-c). In some respects, UE 115 can identify the TDRA field value based on the control message received at 505.

[0205] For example, a control message may include an indication of a set of TRIVs containing a subset of TRIVs (e.g., TRIV{0, ..., 511}), which includes a first subset of TRIVs associated with time resource reservations (e.g., TRIV{0, ..., 496}) and a second subset of TRIVs unrelated to time resource reservations (e.g., TRIV{497, ..., 511}). In this example, UE 115 may identify one or more TDRA field values ​​by identifying one or more TRIVs within a second SCI message, wherein the one or more TRIVs include one or more TRIVs from the second subset of TRIVs (e.g., TRIV{497, ..., 511}). In this respect, UE 115 may identify a second resource set for retransmission reservations of the second sidelink control information based on identifying one or more TDRA field values ​​(e.g., TRIVs) unrelated to time resource reservations.

[0206] At 545, the first UE 115-c, the second UE 115-d, or both may identify one or more additional fields within the second SCI message. These additional fields may include fields associated with DMRS, fields associated with DMRS ports, fields associated with the priority of sidelink communication, fields associated with PSFCH overhead, FDRA fields, or any combination thereof. The one or more additional fields identified within the second SCI message may be used to convey various information. For example, as will be described in further detail herein, one or more additional fields may be used to indicate a second set of resources reserved for retransmission of the second sidelink transmission, may be used to indicate that the second SCI message relates to the release of resources reserved by the first SCI message, or both.

[0207] At 550, the first UE 115-c, the second UE 115-d, or both can identify that the release of reserved resources provided by the second SCI message is related to at least one retransmission timing reserved by the first SCI message. In this regard, as Figure 3As shown, the first UE 115-c and / or the second UE 115-d can identify that the release provided by the second SCI message transmitted via the sidelink resource 315 relates to the retransmission sidelink resource 310-a (e.g., a first retransmission occasion) and / or the retransmission sidelink resource 310-b (e.g., a second retransmission occasion). In some cases, a UE 115 receiving the second SCI message providing the release can be configured to identify that the release relates to the at least one retransmission occasion by decoding the received second SCI message. In additional or alternative cases, a UE 115 receiving the second SCI message providing the release can be configured to identify that the release relates to the at least one retransmission occasion without decoding the received second SCI message.

[0208] In some aspects, the UE 115 can identify that the release relates to the at least one retransmission occasion reserved by the first SCI message based on receiving the control message at 505, transmitting or receiving the first SCI message at 510, transmitting or receiving the first sidelink transmission at 515, transmitting or receiving the feedback message at 520, identifying resources that can be used to transmit or receive the second SCI message at 525, transmitting or receiving the second SCI message at 530, identifying the second SCI message at 535, identifying the TDRA field value at 540, identifying the additional field at 545, or any combination thereof.

[0209] For example, in some cases, the first SCI message can include a first identifier (e.g., transmitter ID, receiver ID) associated with the first UE 115-c and / or the second UE 115-d, and the second SCI message can include a second identifier that associates the second SCI message to the same UE 115 identified by the identifier within the first SCI message. For example, the first SCI message can include a first identifier (e.g., transmitter ID) associated with the first UE 115-c, and the second SCI message can include a second identifier (e.g., corresponding or matching transmitter ID) associated with the first UE 115-c. In this case, the UE 115 can be configured to identify that the release relates to the at least one retransmission occasion scheduled by the first SCI message based on the first identifier (e.g., transmitter ID, receiver ID) of the first SCI message and the second identifier (e.g., transmitter ID, receiver ID) of the second SCI message.

[0210] By another example, the first UE 115-c and / or the second UE 115-d can identify the release in relation to at least one retransmission opportunity reserved by the first SCI message based on a first transmission time interval and a second transmission time interval in which the first SCI message and the second SCI message are received or transmitted. For example, UE 115 can determine that the difference between the first transmission time interval (e.g., a first time slot in which the first SCI message is transmitted / received) and the second transmission time interval (e.g., a second time slot in which the second SCI message is transmitted / received) satisfies a threshold difference. In some aspects, the threshold time difference can be based on a configured HARQ feedback time. In this example, the first UE 115-c and / or the second UE 115-d can be configured to identify the release in relation to at least one retransmission opportunity based on the difference (e.g., the difference between the first and second transmission time intervals) satisfying a threshold difference.

[0211] By another example, the first UE 115-c and / or the second UE 115-d may identify the release in relation to at least one retransmission timing reserved by the first SCI message based on determining that the second SCI message is identified within a defined threshold time range and / or threshold frequency range relative to the first SCI, at least one retransmission timing of the release, or both. For example, UE 115 may determine that the first sub-channel of the first SCI message and the second sub-channel of the second SCI message are within each other's threshold ranges. In some aspects, the threshold ranges may be configured via control signaling (e.g., the control message at 505). Additionally or alternatively, the threshold ranges may be determined based on the first PSSCH resources during a first transmission time interval on which the first SCI message is transmitted and the second PSSCH resources during a second transmission time interval on which the second SCI message is transmitted. In this example, the first UE 115-c and / or the second UE 115-d may be configured to identify the release in relation to at least one retransmission timing based on the threshold range being satisfied. In some respects, UE115 can be configured to determine that the release is related to at least one retransmission opportunity reserved by the first SCI message based on determining that the subchannel of the second transmission time interval and the second SCI message is within a threshold amount of at least one retransmission opportunity associated with the release.

[0212] In some respects, the first UE 115-c, the second UE 115-d, or both may identify the release in relation to at least one retransmission timing reserved by the first SCI message based on a second SCI message within a first resource set identified by the first SCI message. For example, in the first SCI message reservation Figure 3In some cases of the illustrated retransmission sidelink resources 310-a and 310-b, the second SCI message can be transmitted within the retransmission sidelink resources 310-a and can provide a release of the retransmission sidelink resources 310-b. In this case, the first UE 115-c and / or the UE 115-d can identify, based on identifying the second SCI message within the retransmission sidelink resources 310-a (e.g., the retransmission occasion), that the second SCI message provides a release of the retransmission sidelink resources 310-b (e.g., the retransmission occasion).

[0213] In some aspects, the first UE 115-c, the second UE 115-d, or both, can identify, based on the configured resource range (e.g., a resource range configured via the control message received at 505), that the release relates to the at least one retransmission occasion reserved by the first SCI message. The configured resource range can be defined with respect to the first SCI message, the at least one retransmission occasion being released, or both. For example, the UE 115 can identify that a second transmission time interval (e.g., a second slot) of the second SCI message and / or a subchannel of the second SCI message is within the configured resource range associated with the first SCI message (e.g., a configured range of the first transmission time interval, a configured range of the subchannel of the first SCI message). In this case, the UE 115 can identify, based on the configured range(s) being satisfied, that the release relates to the at least one retransmission occasion. For example, the control message can indicate that the second SCI message can be received two or three slots after the first transmission time interval. In this case, the UE 115 can identify, based on identifying the second SCI message two or three slots after the first transmission time interval (e.g., based on identifying that the configured range is satisfied), that the second SCI message is associated with the release.

[0214] Similarly, the UE 115 can identify that the release relates to the at least one retransmission occasion reserved by the first SCI message based on a transmission time interval and / or a subchannel of the at least one retransmission occasion. For example, a configured range can be defined with respect to the transmission time interval and / or the subchannel of the at least one retransmission occasion that is released. In this case, the UE 115 can be configured to identify that the release relates to the at least one retransmission occasion based on the configured range being satisfied. For example, the control message can indicate that the second SCI message can be received two slots before the transmission time interval associated with the at least one retransmission occasion and three subchannels below the subchannel associated with the at least one retransmission occasion. In this case, the UE 115 can identify that the second SCI message is associated with the release based on identifying the second SCI message two slots before the transmission time interval associated with the released at least one retransmission occasion and three subchannels below the subchannel associated with the released at least one retransmission occasion (e.g., based on identifying that the configured range is satisfied). In this regard, the first UE 115-c, the second UE 115-d, or both can be configured to identify a release associated with the second SCI message based on a relationship between the second SCI message and the first SCI message and / or the released resources, which is indicated via the control message received at 505.

[0215] In some aspects, the first UE 115-c, the second UE 115-d, or both can identify that the release relates to the at least one retransmission occasion reserved by the first SCI message based on an indication or field in the first SCI message, the second SCI message, or both. For example, the UE 115 can determine one or more TDRA field values of the first SCI message, a FDRA field value of the first SCI message, a cyclic redundancy check (CRC) portion of the first SCI message, or any combination thereof, and can be configured to determine that the release relates to the at least one retransmission occasion based on the determined indication or field within the first SCI message. By way of another example, the UE 115 can be configured to identify that the release relates to the at least one retransmission occasion based on one or more TDRA field values of the second SCI message determined at 540, one or more additional field values (e.g., a FDRA field value, a DMRS field, a DMRS port field, a sidelink priority field, a PSFCH overhead field) of the second SCI message determined at 545, or any combination thereof.

[0216] Additionally or alternatively, the UE 115 can identify, based on a portion of the second SCI message that includes a checksum or a hash function of a portion of the first SCI message, that the release relates to the at least one retransmission occasion reserved by the first SCI message. For example, the UE 115 can determine that the second SCI message includes second data that includes a checksum or a hash function of at least a portion of first data included within the first SCI message, and can identify, based on identifying that the second data includes the checksum or the hash function of the first data, that the release relates to the at least one retransmission occasion. In this case, the first data included within the first SCI message can include a CRC portion of the first SCI message, a set of FDRA field values of the first SCI message, a set of TDRA field values of the first SCI message, or any combination thereof. Further, the second data included within the second SCI message can include a CRC portion of the second SCI message, a set of FDRA field values of the second SCI message, a set of DMRS bit values of the second SCI message, or any combination thereof.

[0217] In some aspects, the UE 115 can be configured to calculate and / or recalculate a channel occupancy of the sidelink communication network (e.g., the sidelink channel) based on identifying the release. For example, the UE 115 can be configured to determine a first channel occupancy of the sidelink communication network prior to transmitting / receiving the second SCI (e.g., prior to identifying the second SCI message), and can determine a second channel occupancy of the sidelink communication network based on identifying the second SCI message providing the release (e.g., based on identifying the release).

[0218] At 555, the first UE 115-c can transmit, in accordance with the release of the first subset of resources, a retransmission of the first sidelink transmission transmitted at 515 using only the second subset of the first set of resources reserved for retransmission. Further, the second UE 115-d can monitor, in accordance with the identified release, a retransmission occasion of the one or more retransmission occasions. For example, with reference to Figure 3 The first SCI message can include a set of resources reserved for retransmission of the first sidelink transmission (e.g., retransmission sidelink resources 310-a and 310-b). In this example, the second SCI message transmitted via sidelink resources 315 can indicate a release of the retransmission sidelink resource 310-a (e.g., release the first subset of reserved resources). In this regard, the first UE 115-c can transmit a retransmission of the first sidelink transmission using the retransmission sidelink resource 310-b (e.g., using the second subset of reserved resources).

[0219] In some respects, the second SCI message can release or cancel the entire first resource set retained by the first SCI message. For example, the second SCI message can release both retransmission sidelink resources 310-a and 310-b. In this case, the second subset of the first resource set may not include resources, such that the first UE 115-c suppresses any retransmissions performing the first sidelink transmission.

[0220] At 560, the second UE 115-d, the third UE 115 (not shown), or both may use at least a portion of the first subset of resources released via the second SCI message to transmit sidelink transmissions. In this regard, UE 115 may use the resources released by the second SCI message at 560 to transmit and / or receive sidelink transmissions based on the indication at 550 that the release relates to at least one retransmission event. For example, if the second SCI message releases retransmission sidelink resource 310-a, the second UE 115-d may use retransmission sidelink resource 310-b to transmit sidelink transmissions to the first UE 115-c and / or another UE 115.

[0221] In some cases, based on predefined parameters, including the time for transmitting / receiving the second SCI, the time resources used for the released resources, communication parameters at UE 115, or any combination thereof, the reuse of released sidelink resources can be prohibited. For example, if UE 115 switches from transmitting to receiving in a given number of time slots for half-duplex communication, the immediate reuse of resources released via the second SCI message can be prohibited.

[0222] At 565, the first UE 115-c can transmit a retransmission of the second sidelink transmission based on a second resource set retained by one or more TDRA fields within the second SCI message. In this respect, the first UE 115-c can transmit the retransmission of the second sidelink transmission at 565 based on one or more TDRA field values ​​identifying the second SCI message at 535, at 540, or both. For example, refer to... Figure 3 The second SCI message transmitted via sidelink resource 315 may include one or more TDRA field values ​​indicating a retransmission sidelink resource 310-c reserved for retransmission of the second sidelink transmission. In this example, the first UE 115-c may use the retransmission sidelink resource 310-c reserved via the TDRA field value of the second SCI message to perform a retransmission of the second sidelink transmission. In some aspects, the retransmission of the second sidelink transmission performed at 565 may include the retransmission of the second SCI message, the transmission and / or retransmission of data transmitted via PSSCH, or any combination thereof.

[0223] Figure 6A block diagram 600 of a device 605 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is shown. The device 605 can be an example of aspects of a UE 115 as described herein. The device 605 can include a receiver 610, a communications manager 615, and a transmitter 620. The device 605 can also include a processor. Each of these components can be in communication with one another (e.g., via one or more buses).

[0224] The receiver 610 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to techniques for sidelink resource cancellation using TDRA, etc.). Information can be passed on to other components of the device 605. The receiver 610 can be an example of aspects of the transceiver 920 described with reference to FIG. 9. The receiver 610 can utilize a single antenna or a set of antennas. Figure 9

[0225] In the context of a UE 115 that transmits a first SCI message reserving sidelink resources, the communications manager 615 can transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmissions of the first sidelink transmission at one or more retransmission occasions; identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmissions of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmissions of the first sidelink transmission related to at least one of the one or more retransmission occasions; and transmit, in accordance with the release of the first subset of the first set of resources, the retransmissions of the first sidelink transmission only on a second subset of the first set of resources.

[0226] ​In the context of a UE 115 receiving a first SCI message reserving sidelink resources, the communications manager 615 can receive, from a first UE, a first SCI message associated with a first sidelink transmission from the first UE to a second UE during a first transmission time interval, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources for retransmission of the first sidelink transmission related to at least one of the one or more retransmission occasions, and monitor only a second subset of the first set of resources in accordance with the release of the first subset of the first set of resources.

[0227] In the context of a UE 115 transmitting a first SCI message reserving sidelink resources, the communications manager 615 can transmit, from a first UE, a first SCI message associated with a first sidelink transmission from the first UE during a first transmission time interval, where the first SCI message includes a first indication of a set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources for retransmission of the first sidelink transmission related to at least one of the one or more retransmission occasions, and transmit retransmissions of the first sidelink transmission only on a second subset of the set of resources in accordance with the release of the first subset of the set of resources.

[0228] In the context of a UE 115 receiving a first SCI message reserving sidelink resources, the communications manager 615 can receive, from a first UE, a first SCI message associated with a first sidelink transmission from the first UE to a second UE during a first transmission time interval, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources for retransmission of the first sidelink transmission related to at least one of the one or more retransmission occasions, and monitor only a second subset of the first set of resources in accordance with the release of the first subset of the first set of resources. The communications manager 615 can be an example of aspects of the communications manager 910 as described herein.

[0229] The communications manager 615, or its sub-components, can be implemented in hardware, code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communications manager 615, or its sub-components can be executed by a general-purpose 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 designed to perform the functions described in the present disclosure.

[0230] The communications manager 615, or its sub-components, can be physically located in various places in the apparatus, including but not limited to being distributed

[0231] The transmitter 620 can transmit signals generated by other components of the device 605. In some examples, the transmitter 620 can be collocated with a receiver 610 in a transceiver module. The transmitter 620 can be an example of aspects of the transceiver 920 described with reference to FIG. 9. The transmitter 620 can utilize a single antenna or a set of antennas. Figure 9

[0232] Figure 7 FIG. 7 shows a block diagram of a device 705 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure. The device 705 can be an example of aspects of a device 605 or a UE 115 as described herein. The device 705 can include a receiver 710, a communications manager 715, and a transmitter 735. The device 705 can also include a processor. Each of these components can be in communication with one another (e.g., via one or more buses).

[0233] The receiver 710 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to techniques for sidelink resource cancellation using TDRA, etc.). Information can be passed on to other components of the device 705. The receiver 710 can be an example of aspects of the transceiver 920 described with reference to FIG. 9. The receiver 710 can utilize a single antenna or a set of antennas. Figure 9

[0234] ​​The communications manager 715 can be an example of aspects of the communications manager 615 as described herein. The communications manager 715 can include a SCI manager 720, a sidelink transmission manager 725, and a sidelink monitoring manager 730. The communications manager 715 can be an example of aspects of the communications manager 910 described herein.

[0235] The SCI manager 720 can transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from a first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions; and identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions.

[0236] The sidelink transmission manager 725 can transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources.

[0237] The SCI manager 720 can receive, during a first transmission time interval from a first UE, a first SCI message associated with a first sidelink transmission from the first UE to a second UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions; and identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions.

[0238] The sidelink monitoring manager 730 can monitor, in accordance with the release of the first subset of the first set of resources, only a second subset of the first set of resources.

[0239] The transmitter 735 can transmit signals generated by other components of the device 705. In some examples, the transmitter 735 can be collocated with a receiver 710 in a transceiver module. For example, the transmitter 735 can be an example of aspects of the transmitter 920 described with reference to FIG. 9. The transmitter 735 can utilize a single antenna or a set of antennas. Figure 9 The transmitter 735 can transmit signals generated by other components of the device 705. In some examples, the transmitter 735 can be collocated with a receiver 710 in a transceiver module. For example, the transmitter 735 can be an example of aspects of the transmitter 920 described with reference to FIG. 9. The transmitter 735 can utilize a single antenna or a set of antennas. The transmitter 735 can transmit signals generated by other components of the device 705. In some examples, the transmitter 735 can be collocated with a receiver 710 in a transceiver module. For example, the transmitter 735 can be an example of aspects of the transmitter 920 described with reference to FIG. 9. The transmitter 735 can utilize a single antenna or a set of antennas.

[0240] Figure 8 A block diagram 800 of a communications manager 805 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is shown. The communications manager 805 can be an example of aspects of a communications manager 615, a communications manager 715, or a communications manager 910 described herein. The communications manager 805 can include a SCI manager 810, a sidelink transmission manager 815, a sidelink resource release manager 820, a control message reception manager 825, a SCI parameter manager 830, a checksum manager 835, a feedback message reception manager 840, a TDRA manager 845, a HARQ configuration manager 850, a sidelink reception manager 855, a channel occupancy rate manager 860, a sidelink monitoring manager 865, and a feedback message transmission manager 870. Each of these modules can communicate, directly or indirectly, with one another (e.g., via one or more buses).

[0241] The SCI manager 810 can transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from a first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions. In these examples, the first SCI message includes the first indication of the set of resources reserved for retransmission of the first sidelink transmission at the one or more retransmission occasions.

[0242] In some examples, the SCI manager 810 can identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions. In some examples, the SCI manager 810 can identify that the second SCI message is within the first set of resources reserved for retransmission of the first sidelink transmission. In some examples, the SCI manager 810 can identify that at least one of the second transmission time interval or a subchannel of the second SCI message is within a configured range of the first SCI message. In some examples, identifying the second SCI message includes receiving the second SCI message from a second UE.

[0243] In some examples, the SCI manager 810 can identify a time period prior to a first retransmission occasion of the one or more retransmission occasions during which at least the first retransmission occasion is not to be released, where the second SCI message is identified prior to a start of the identified time period. In some examples, the SCI manager 810 can identify a time period following transmission of the first SCI message during which the one or more retransmission occasions are not to be released, where the second SCI message is identified following an end of the identified time period.

[0244] In some examples, the SCI manager 810 can receive, via the first SCI message, a first identifier that associates the first SCI message with the first UE, a second UE to which the first sidelink transmission is directed, or both, where the second SCI message includes a second identifier that associates the second SCI message with the same UE identified by the first identifier. In some examples, the SCI manager 810 can identify that the second SCI message is within the first set of resources reserved for retransmissions of the first sidelink transmission. In some examples, the SCI manager 810 can identify that at least one of a second transmission time interval or a subchannel of the second SCI message is within a configured range of the first SCI message. In some examples, identifying the second SCI message includes transmitting the second SCI message to the first UE. In some cases, the second SCI message is transmitted with a specified priority that is greater than a priority associated with other transmissions. In some cases, the second sidelink transmission includes a retransmission of the second SCI message, a data transmission transmitted via a PSSCH, or any combination thereof.

[0245] In some examples, the sidelink transmission manager 815 can transmit the first sidelink transmission in accordance with the first SCI message. The sidelink transmission manager 815 can transmit retransmissions of the first sidelink transmission only on a second subset of the first set of resources in accordance with a release of a first subset of the first set of resources. In some examples, transmitting retransmissions of the first sidelink transmission only on the second subset of the first set of resources includes refraining from performing any retransmissions of the first sidelink transmission.

[0246] In some examples, the sidelink transmission manager 815 can identify, based on transmitting the first SCI message, a candidate set of resources for transmitting the second SCI message, where the candidate set of resources has a higher priority than a set of resources selected for transmitting other sidelink transmission messages. In some examples, the sidelink transmission manager 815 can select, based on the candidate set of resources having the higher priority, a set of resources from the candidate set of resources for transmitting the second SCI message.

[0247] In some examples, the sidelink transmission manager 815 can transmit, to the first UE, the third UE, or both, a third sidelink transmission on a set of resources associated with the at least one retransmission occasion released via the second SCI message, where the third sidelink transmission is transmitted based on identifying the second SCI message.

[0248] In some examples, the sidelink transmission manager 815 can identify a candidate set of resources for transmitting the second SCI message based on receiving the first SCI message, where the candidate set of resources has a higher priority than a selected resource for transmitting other sidelink transmission messages. In some examples, the sidelink transmission manager 815 can select the set of resources for transmitting the second sidelink transmission based on the candidate set of resources having the higher priority.

[0249] The sidelink monitoring manager 865 can monitor only a second subset of the first set of resources in accordance with the release of the first subset of the first set of resources. In some examples, monitoring only the second subset of the first set of resources includes refraining from monitoring a retransmission occasion of the one or more retransmission occasions.

[0250] The sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on the first identifier and the second identifier. In some examples, the sidelink resource release manager 820 can determine that a difference between the first transmission time interval and the second transmission time interval satisfies a threshold difference based on a configured HARQ feedback time, where the release is identified as related to the at least one retransmission occasion based on the difference satisfying the threshold difference. In some examples, the sidelink resource release manager 820 can determine that a first subchannel of the first SCI message and a second subchannel of the second SCI message are within a threshold range of a first PSSCH resource during the first transmission time interval and a second PSSCH resource during the second transmission time interval, where the release is identified as related to the at least one retransmission occasion based on the threshold range being satisfied.

[0251] In some examples, the sidelink resource release manager 820 can determine that the second transmission time interval and a subchannel of the second SCI message are within a threshold amount of the at least one retransmission occasion, where the release is identified as related to the at least one retransmission occasion based on the threshold amount being satisfied. In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on identifying the second SCI message within the first set of resources. In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on a configured range being satisfied.

[0252] In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on a transmission time interval and a subchannel of the one or more retransmission occasions. In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on the relationship. In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on a TDRA field value of the first SCI message, a FDRA field value of the first SCI message, a CRC portion of the first SCI message, or any combination thereof. In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on identifying, based on a checksum or a hash function included within the second SCI message, that second data included within the second SCI message includes first data included within the first SCI message. In some examples, the sidelink resource release manager 820 can identify that the release is related to at least one of the one or more retransmission occasions based on one or more TDRA field values, one or more additional fields within the second SCI message, or both. In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on the first identifier and the second identifier.

[0253] In some examples, the sidelink resource release manager 820 can determine that a difference between the first transmission time interval and the second transmission time interval satisfies a threshold difference based on a configured HARQ feedback time, where the release is identified as related to the at least one retransmission occasion based on the difference satisfying the threshold difference. In some examples, the sidelink resource release manager 820 can determine that a first subchannel of the first SCI message and a second subchannel of the second SCI message are within a threshold range of a first PSSCH resource during the first transmission time interval and a second PSSCH resource during the second transmission time interval, where the release is identified as related to the at least one retransmission occasion based on the threshold range being satisfied.

[0254] In some examples, the sidelink resource release manager 820 can determine that the second transmission time interval and a subchannel of the second SCI message are within a threshold amount of the at least one retransmission occasion, where the release is identified as related to the at least one retransmission occasion based on the threshold amount being satisfied. In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on identifying the second SCI message within the first set of resources. In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on a configured range being satisfied. In some examples, the sidelink resource release manager 820 can identify that the release is related to the at least one retransmission occasion based on a transmission time interval and a subchannel of the one or more retransmission occasions and the second SCI message.

[0255] The control message reception manager 825 can receive a control message indicating a relationship between the second SCI message and at least one of the first SCI message or the one or more retransmission occasions. In some examples, the control message reception manager 825 can receive a control message including an indication of a TRIV set including a first subset of TRIVs associated with time resource reservations and a second subset of TRIVs unrelated to time resource reservations, where the one or more TDRA field values in the second SCI message include time resource indicator values from the second subset of TRIVs.

[0256] The SCI parameter manager 830 can determine a TDRA field value of the first SCI message, a FDRA field value of the first SCI message, a CRC portion of the first SCI message, or any combination thereof. In some examples, the SCI parameter manager 830 can identify one or more additional fields within the second SCI message. In some cases, the one or more additional fields within the second SCI message include a first field associated with a DMRS, a second field associated with a port for the DMRS, a third field associated with a priority of the sidelink communication, a fourth field associated with a PSFCH overhead, a fifth field associated with a FDRA, or any combination thereof.

[0257] The checksum manager 835 can identify that the second SCI message includes second data including a checksum or a hash function of at least a portion of first data included within the first SCI message. In some examples, the first data includes a first CRC portion of the first SCI message, a set of TDRA values of the first SCI message, a set of FDRA values of the first SCI message, or any combination thereof. In some examples, the second data includes a second CRC portion of the second SCI message, a second set of FDRA values of the second SCI message, a set of DMRS bit values of the second SCI message, or any combination thereof. In some examples, identifying that the second SCI message includes second data including a checksum or a hash function of at least a portion of first data included within the first SCI message. In some examples, the first data includes a first CRC portion of the first SCI message, a set of TDRA values of the first SCI message, a set of FDRA values of the first SCI message, or any combination thereof. In some examples, the second data includes a second CRC portion of the second SCI message, a second set of FDRA values of the second SCI message, a set of DMRS bit values of the second SCI message, or any combination thereof.

[0258] The feedback message reception manager 840 can receive, from the second UE, a feedback message indicating that the second UE received the first sidelink transmission, where the UE identifies the second SCI message by generating the second SCI message based on the feedback message.

[0259] The TDRA manager 845 can determine a TDRA field value of the first SCI message, a FDRA field value of the first SCI message, a CRC portion of the first SCI message, or any combination thereof. In some cases, the one or more TDRA field values include one or more TRIVs that are not related to time resource reservation.

[0260] The HARQ configuration manager 850 can identify a HARQ configuration associated with the sidelink communication, where identifying the time period following transmission of the first SCI message is based on the determined HARQ configuration.

[0261] The sidelink reception manager 855 can receive, from the second UE, the third UE, or both to which the first sidelink transmission is directed, a third sidelink transmission on a set of resources associated with the at least one retransmission occasion released via the second SCI message, where the third sidelink transmission is received based on identifying the second SCI message. In some examples, the sidelink reception manager 855 can receive the first sidelink transmission from the first UE in accordance with the first SCI message.

[0262] The channel occupancy manager 860 can determine a first channel occupancy of the sidelink communication network prior to transmitting the second SCI. In some examples, the channel occupancy manager 860 can determine a second channel occupancy of the sidelink communication network based on identifying the second SCI providing the release.

[0263] The feedback message transmission manager 870 can transmit, to the first UE, a feedback message indicating that the first sidelink transmission was received, where the UE identifies the second SCI message by receiving the second SCI message based on the feedback message.

[0264] Figure 9 A diagram illustrates a system 900 including a device 905 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure. The device 905 can be an example of or include the components of device 605, device 705, or a UE 115 as described herein. The device 905 can include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager 910, an I / O controller 915, a transceiver 920, an antenna 925, memory 930, and a processor 940. These components can be in electronic communication via one or more buses (e.g., bus 945).

[0265] In the context of a UE 115 transmitting a first SCI message reserving sidelink resources, the communications manager 910 can transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions; identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission related to at least one of the one or more retransmission occasions; and transmit, in accordance with the release of the first subset of the first set of resources, retransmissions of the first sidelink transmission only on a second subset of the first set of resources.

[0266] In the context of a UE 115 receiving a first SCI message reserving sidelink resources, the communications manager 910 can receive, from a first UE during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE to a second UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions; identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission related to at least one of the one or more retransmission occasions; and monitor, in accordance with the release of the first subset of the first set of resources, only a second subset of the first set of resources.

[0267] In the context of a UE 115 transmitting a first SCI message reserving sidelink resources, the communications manager 910 can transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions; identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission related to at least one of the one or more retransmission occasions; and transmit, in accordance with the release of the first subset of the first set of resources, retransmissions of the first sidelink transmission only on a second subset of the first set of resources.

[0268] In the context of a UE 115 receiving a first SCI message reserving sidelink resources, the communications manager 910 can receive, from a first UE during a first transmission time interval, a first SCI message associated with a sidelink transmission from the first UE to a second UE, where the first SCI message includes a first indication of a set of resources reserved for retransmissions of the sidelink transmission at one or more retransmission occasions, identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmissions of the sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions, and monitor only a second subset of the set of resources in accordance with the release of the first subset of the set of resources.

[0269] The I / O controller 915 can manage input and output signals for the device 905. The I / O controller 915 can also manage peripherals not integrated into the device 905. In some cases, the I / O controller 915 can represent a physical connection or port to or another known operating system. In other cases, the I / O controller 915 can represent or interact with a modem, a keyboard, a mouse, a touchscreen, or similar devices. In some cases, the I / O controller 915 can be implemented as part of a processor. In some cases, a user can interact with the device 905 via the I / O controller 915 or via hardware components controlled by the I / O controller 915.

[0270] The transceiver 920 can communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 920 can represent a wireless transceiver and can communicate bi-directionally with another wireless transceiver. The transceiver 920 can also include a modem to modulate the packets and to

[0271] In some cases, the wireless device can include a single antenna 925. However, in some cases the device can have more than one antenna 925, which can be capable of concurrently transmitting or receiving multiple wireless transmissions.

[0272] The memory 930 can include random access memory (RAM) and read-only memory (ROM). The memory 930 can store computer-readable, computer-executable code 935 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 930 can contain, among other computer-readable or computer- executable instructions, a basic I / O system (BIOS) which can control basic hardware or software operation such as the interaction with peripheral components or devices.

[0273] The processor 940 can include an intelligent hardware device, (e.g., a general- purpose processor, a DSP, a central processing unit (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 940 can be configured to operate a memory array. In other cases, a memory controller can be integrated into the processor 940. The processor 940 can be configured to execute computer-readable instructions stored in a memory (e.g., the memory 930) to cause the device 905 to perform various functions (e.g., functions or tasks for supporting techniques for sidelink resource cancellation using TDRA).

[0274] The code 935 can include instructions for implementing aspects of the present disclosure including instructions for support wireless communications. The code 935 can be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code 935 can not be directly executable by the processor 940 but can cause a computer (e.g., when compiled and executed) to perform functions described herein.

[0275] Figure 10 A method 1000 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is shown. The operations of method 1000 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1000 can be performed by a communications manager as described with reference to Figures 6 to 9 In some examples, a UE can execute a set of instructions to control its functional elements to perform the functions described below. Additionally or alternatively, the UE can perform aspects of the functions described below using special-purpose hardware.

[0276] At 1005, the UE can transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions. The operations of 1005 can be performed according to the methods described herein. In some examples, aspects of the operations of 1005 can be performed by a SCI manager as described with reference to Figures 6 to 9The described SCI manager to perform.

[0277] At 1010, the UE can identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one retransmission occasion of the one or more retransmission occasions. The operations of 1010 can be performed according to the methods described herein. In some examples, aspects of the operations of 1010 can be performed by a SCI manager as described with reference to FIGs. 7 through 9. Figures 6 to 9 The described SCI manager to perform.

[0278] At 1015, the UE can transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources. The operations of 1015 can be performed according to the methods described herein. In some examples, aspects of the operations of 1015 can be performed by a sidelink transmission manager as described with reference to FIGs. 7 through 9. Figures 6 to 9 The described SCI manager to perform.

[0279] Figure 11 A flow diagram illustrating a method 1100 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is shown. The operations of method 1100 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1100 can be performed by a communications manager as described with reference to FIGs. 7 through 9. Figures 6 to 9 In some examples, a UE can execute a set of instructions to control its functional elements to perform the functions described below. Additionally or alternatively, the UE can perform aspects of the functions described below using special-purpose hardware.

[0280] At 1105, the UE can transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions. The operations of 1105 can be performed according to the methods described herein. In some examples, aspects of the operations of 1105 can be performed by a SCI manager as described with reference to FIGs. 7 through 9. Figures 6 to 9 The described SCI manager to perform.

[0281] At 1110, the UE can identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of the second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions. The operations of 1110 can be performed according to the methods described herein. In some examples, aspects of the operations of 1110 can be performed by a SCI manager as described with reference to Figures 6 to 9 The described SCI manager.

[0282] At 1115, the UE can identify that the second SCI message is within the first set of resources reserved for retransmission of the first sidelink transmission. The operations of 1115 can be performed according to the methods described herein. In some examples, aspects of the operations of 1115 can be performed by a SCI manager as described with reference to Figures 6 to 9 The described SCI manager.

[0283] At 1120, the UE can identify, based on identifying the second SCI message within the first set of resources, that the release pertains to the at least one retransmission occasion. The operations of 1120 can be performed according to the methods described herein. In some examples, aspects of the operations of 1120 can be performed by a sidelink resource release manager as described with reference to Figures 6 to 9 The described SCI manager.

[0284] At 1125, the UE can transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources. The operations of 1125 can be performed according to the methods described herein. In some examples, aspects of the operations of 1125 can be performed by a sidelink transmission manager as described with reference to Figures 6 to 9 The described SCI manager.

[0285] Figure 12 A flow diagram illustrating a method 1200 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is shown. The operations of method 1200 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1200 can be performed by a communications manager as described with reference to Figures 6 to 9 In some examples, a UE can execute a set of instructions to control its functional elements to perform the functions described below. Additionally or alternatively, a UE can perform aspects of the functions described below using special-purpose hardware.

[0286] At 1205, the UE can transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions. The operations of 1205 can be performed according to the methods described herein. In some examples, aspects of the operations of 1205 can be performed by a SCI manager as described with reference to FIGs. Figures 6 to 9 The described SCI manager.

[0287] At 1210, the UE can receive a control message indicating a relationship between the second SCI message and at least one of the first SCI message or the one or more retransmission occasions. The operations of 1210 can be performed according to the methods described herein. In some examples, aspects of the operations of 1210 can be performed by a control message reception manager as described with reference to FIGs. Figures 6 to 9 The described control message reception manager.

[0288] At 1215, the UE can identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions. The operations of 1215 can be performed according to the methods described herein. In some examples, aspects of the operations of 1215 can be performed by a SCI manager as described with reference to FIGs. Figures 6 to 9 The described SCI manager.

[0289] At 1220, the UE can identify, based on the relationship, that the release pertains to the at least one retransmission occasion. The operations of 1220 can be performed according to the methods described herein. In some examples, aspects of the operations of 1220 can be performed by a sidelink resource release manager as described with reference to FIGs. Figures 6 to 9 The described sidelink resource release manager.

[0290] At 1225, the UE can transmit, in accordance with the release of the first subset of the first set of resources, the retransmission of the first sidelink transmission only on a second subset of the first set of resources. The operations of 1225 can be performed according to the methods described herein. In some examples, aspects of the operations of 1225 can be performed by a sidelink transmission manager as described with reference to FIGs. Figures 6 to 9 The described sidelink transmission manager.

[0291] Figure 13A flow diagram illustrating a method 1300 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is shown. The operations of method 1300 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1300 can be performed by a communications manager as described with reference to Figures 6 to 9 In some examples, a UE can execute a set of instructions to control its functional elements to perform the functions described below. Additionally or alternatively, a UE can perform aspects of the functions described below using special-purpose hardware.

[0292] At 1305, the UE can receive, from a first UE during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE to a second UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions. The operations of 1305 can be performed according to the methods described herein. In some examples, aspects of the operations of 1305 can be performed by a SCI manager as described with reference to Figures 6 to 9 FIGS. 13 through 16.

[0293] At 1310, the UE can identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission, the second SCI message providing a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions. The operations of 1310 can be performed according to the methods described herein. In some examples, aspects of the operations of 1310 can be performed by a SCI manager as described with reference to Figures 6 to 9 FIGS. 13 through 16.

[0294] At 1315, the UE can monitor only a second subset of the first set of resources in accordance with the release of the first subset of the first set of resources. The operations of 1315 can be performed according to the methods described herein. In some examples, aspects of the operations of 1315 can be performed by a sidelink monitoring manager as described with reference to Figures 6 to 9 FIGS. 13 through 16.

[0295] Figure 14 A flow diagram illustrating a method 1400 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is shown. The operations of method 1400 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1400 can be performed by a communications manager as described with reference to Figures 6 to 9The described communication manager performs. In some examples, the UE can execute a set of instructions to control its functional elements to perform the functions described below. Additionally or alternatively, the UE can perform aspects of the functions described below using special-purpose hardware.

[0296] At 1405, the UE can transmit, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, where the first SCI message includes a first indication of a set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions. The operations of 1405 can be performed according to the methods described herein. In some examples, aspects of the operations of 1405 can be performed by a SCI manager as described with reference to Figures 6 to 9 The described SCI manager performs.

[0297] At 1410, the UE can identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions. The operations of 1410 can be performed according to the methods described herein. In some examples, aspects of the operations of 1410 can be performed by a SCI manager as described with reference to Figures 6 to 9 The described SCI manager performs.

[0298] At 1415, the UE can transmit, in accordance with the release of the first subset of the first set of resources, retransmission of the first sidelink transmission only on a second subset of the first set of resources. The operations of 1415 can be performed according to the methods described herein. In some examples, aspects of the operations of 1415 can be performed by a sidelink transmission manager as described with reference to Figures 6 to 9 The described sidelink transmission manager performs.

[0299] Figure 15 A flow diagram illustrating a method 1500 that supports techniques for sidelink resource cancellation using TDRA in accordance with aspects of the present disclosure is shown. The operations of method 1500 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1500 can be performed by a communication manager as described with reference to Figures 6 to 9 The described communication manager performs. In some examples, the UE can execute a set of instructions to control its functional elements to perform the functions described below. Additionally or alternatively, the UE can perform aspects of the functions described below using special-purpose hardware.

[0300] At 1505, the UE can receive, from a first UE during a first transmission time interval, a first SCI message associated with a sidelink transmission from the first UE to a second UE, where the first SCI message includes a first indication of a first set of resources reserved for retransmission of the sidelink transmission at one or more retransmission occasions. The operations of 1505 can be performed according to the methods described herein. In some examples, aspects of the operations of 1505 can be performed by a SCI manager as described with reference to FIGs. Figures 6 to 9 The described SCI manager.

[0301] At 1510, the UE can identify, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the first set of resources reserved for retransmission of the sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions. The operations of 1510 can be performed according to the methods described herein. In some examples, aspects of the operations of 1510 can be performed by a SCI manager as described with reference to FIGs. Figures 6 to 9 The described SCI manager.

[0302] At 1515, the UE can monitor only a second subset of the first set of resources in accordance with the release of the first subset of the first set of resources. The operations of 1515 can be performed according to the methods described herein. In some examples, aspects of the operations of 1515 can be performed by a sidelink transmission manager as described with reference to FIGs. Figures 6 to 9 The described sidelink transmission manager.

[0303] implementations, and that the operations and steps can be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods can be combined.

[0304] The following provides an overview of aspects of the disclosure:

[0305] Aspect 1 : A method for wireless communication at a first UE, comprising: transmitting, during a first transmission time interval, a first SCI message associated with a first sidelink transmission from the first UE, wherein the first SCI message includes a first indication of a first set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission occasions; identifying, during a second transmission time interval after the first transmission time interval, a second SCI message associated with the first SCI message, the second SCI message including a second indication of a release of at least a first subset of the first set of resources reserved for retransmission of the first sidelink transmission, the release pertaining to at least one of the one or more retransmission occasions; and transmitting, in accordance with the release of the first subset of the first set of resources, retransmissions of the first sidelink transmission only on a second subset of the first set of resources.

[0306] Aspect 2: The method of aspect 1, further comprising: transmitting, via the first SCI message, a first identifier that associates the first SCI message with the first UE, a second UE to which the first sidelink transmission is directed, or both, wherein the second SCI message includes a second identifier that associates the second SCI message with the same UE identified by the first identifier; and identifying that the release pertains to the at least one retransmission occasion based at least in part on the first identifier and the second identifier.

[0307] Aspect 3: The method of aspect 2, wherein identifying that the release pertains to the at least one retransmission occasion comprises: determining that a difference between the first transmission time interval and the second transmission time interval satisfies a threshold difference, the threshold difference based at least in part on a configured HARQ feedback time, wherein the release is identified as pertaining to the at least one retransmission occasion based at least in part on the difference satisfying the threshold difference.

[0308] Aspect 4: The method of any of aspects 2-3, wherein identifying that the release pertains to the at least one retransmission occasion comprises: determining that a first subchannel of the first SCI message and a second subchannel of the second SCI message are within a threshold range, the threshold range based at least in part on a first PSSCH resource during the first transmission time interval and a second PSSCH resource during the second transmission time interval, wherein the release is identified as pertaining to the at least one retransmission occasion based at least in part on the threshold range being satisfied.

[0309] Aspect 5: The method of any of aspects 2-4, wherein identifying that the release pertains to the at least one retransmission occasion comprises: determining that the second transmission time interval and a subchannel of the second SCI message are within a threshold amount of the at least one retransmission occasion, wherein the release is identified as pertaining to the at least one retransmission occasion based at least in part on the threshold amount being satisfied.

[0310] Aspect 6: The method of any of aspects 1-5, further comprising: identifying that the second SCI message is within a first set of resources reserved for retransmissions of the first sidelink transmission; and identifying that the release pertains to the at least one retransmission occasion based at least in part on identifying the second SCI message within the first set of resources.

[0311] Aspect 7: The method of any of aspects 1-6, further comprising: identifying that at least one of the second transmission time interval or a subchannel of the second SCI message is within a configured range of the first SCI message; and identifying that the release pertains to the at least one retransmission occasion based at least in part on the configured range being satisfied.

[0312] Aspect 8: The method of any of aspects 1 through 7, further comprising: identifying that the release pertains to the at least one retransmission occasion based at least in part on a transmission time interval and a subchannel of the one or more retransmission occasions.

[0313] Aspect 9: The method of any of aspects 1 through 8, further comprising: receiving a control message indicating a relationship between a second SCI message and at least one of the first SCI message or the one or more retransmission occasions; and identifying that the release pertains to the at least one retransmission occasion based at least in part on the relationship.

[0314] Aspect 10: The method of any of aspects 1 through 9, further comprising: determining a TDRA field value of the first SCI message, a FDRA field value of the first SCI message, a CRC portion of the first SCI message, or any combination thereof; and identifying that the release pertains to the at least one retransmission occasion based at least in part on the TDRA field value of the first SCI message, the FDRA field value of the first SCI message, the CRC portion of the first SCI message, or any combination thereof.

[0315] Aspect 11: The method of any of aspects 1 through 10, further comprising: identifying that the second SCI message includes second data that includes a checksum or a hash function of at least a portion of first data included within the first SCI message; and identifying that the release pertains to the at least one retransmission occasion based at least in part on identifying that the second data included within the second SCI message includes the checksum or the hash function of the first data included within the first SCI message.

[0316] Aspect 12: The method of aspect 11, wherein the first data includes a first CRC portion of the first SCI message, a set of TDRA values of the first SCI message, a set of FDRA values of the first SCI message, or any combination thereof; and wherein the second data includes a second CRC portion of the second SCI message, a second set of FDRA values of the second SCI message, a set of DMRS bit values of the second SCI message, or any combination thereof.

[0317] Aspect 13: The method of any of aspects 1 through 12, wherein the second SCI message includes one or more TDRA field values indicating a second set of resources reserved for retransmission of a second sidelink transmission.

[0318] Aspect 14: The method of aspect 13, wherein the second sidelink transmission includes a retransmission of the second SCI message, a data transmission conveyed via a PSSCH, or any combination thereof.

[0319] Aspect 15: The method of any of aspects 13 through 14, wherein the one or more TDRA field values include one or more TRIVs that are not related to time resource reservations.

[0320] Aspect 16: The method of any of aspects 13 through 15, further comprising: receiving a control message including an indication of a set of TRIVs, the set of TRIVs including a first subset of TRIVs associated with time resource reservations and a second subset of TRIVs unrelated to time resource reservations, wherein the one or more TDRA field values in the second SCI message include a TRIV from the second subset of TRIVs.

[0321] Aspect 17: The method of any of aspects 13 through 16, further comprising: identifying one or more additional fields within the second SCI message; and identifying, based at least in part on the one or more TDRA field values, the one or more additional fields within the second SCI message, or both, that the release relates to the at least one of the one or more retransmission occasions.

[0322] Aspect 18: The method of aspect 17, wherein the one or more additional fields within the second SCI message include a first field associated with a DMRS, a second field associated with a port for the DMRS, a third field associated with a priority of the sidelink communication, a fourth field associated with a PSFCH overhead, a fifth field associated with an FDRA, or any combination thereof.

[0323] Aspect 19: The method of any of aspects 1 through 18, further comprising: transmitting a first sidelink transmission in accordance with the first SCI message; and receiving, from the second UE, a feedback message indicating that the first sidelink transmission was received by the second UE, wherein the UE identifies the second SCI message by generating the second SCI message based at least in part on the feedback message.

[0324] Aspect 20: The method of any of aspects 1 through 19, wherein identifying the second SCI message comprises receiving the second SCI message from the second UE.

[0325] Aspect 21: The method of any of aspects 1 through 20, further comprising: identifying a time period prior to a first retransmission occasion of the one or more retransmission occasions during which at least the first retransmission occasion will not be released, wherein the second SCI message is identified prior to a start of the identified time period.

[0326] Aspect 22: The method of any of aspects 1 through 21, further comprising: identifying a time period following transmission of the first SCI message during which the one or more retransmission occasions will not be released, wherein the second SCI message is identified following an end of the identified time period.

[0327] Aspect 23: The method of Aspect 22, further comprising: identifying a HARQ configuration associated with the sidelink communication, wherein identifying the time period after the transmission of the first SCI message is based at least in part on the determined HARQ configuration.

[0328] Aspect 24: The method of any of aspects 1-23, further comprising: receiving a third sidelink transmission from the second UE, the third UE, or both, that the first sidelink transmission is directed to on a set of resources associated with the at least one retransmission occasion released via the second SCI message, wherein the third sidelink transmission is received based at least in part on identifying the second SCI message.

[0329] Aspect 25: The method of any of aspects 1-24, wherein transmitting the retransmission of the first sidelink transmission only on the second subset of the first set of resources comprises refraining from performing any retransmission of the first sidelink transmission.

[0330] Aspect 26: The method of any of aspects 1-25, further comprising: identifying a candidate set of resources for transmitting the second SCI message based at least in part on transmitting the first SCI message, wherein the candidate set of resources has a higher priority than other sidelink transmission messages selected for transmission; and selecting a set of resources for transmitting the second SCI message from the candidate set of resources based at least in part on the candidate set of resources having the higher priority.

[0331] Aspect 27: The method of any of aspects 1-26, further comprising: determining a first channel occupancy of a sidelink communication network prior to transmitting the second SCI message; and determining a second channel occupancy of the sidelink communication network based at least in part on identifying that the second SCI provides the release.

[0332] Aspect 28: The method of any of aspects 1-27, wherein the second SCI message is transmitted with a specified priority that is higher than a priority associated with other transmissions.

[0333] Aspect 29: An apparatus for wireless communication at a first UE, comprising a processor; memory coupled with the processor; and instructions stored in the memory, the instructions being executable by the processor to cause the apparatus to perform the method of any of aspects 1-28.

[0334] Aspect 30: An apparatus for wireless communication at a first UE, comprising at least one means for performing a method of any of aspects 1-28.

[0335] Aspect 31: A non-transitory computer-readable medium storing code for wireless communications at a first UE, the code comprising instructions executable by a processor to implement a method of any of aspects 1 to 28.

[0336] Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system can be described with reference to the techniques described herein, aspects of the described techniques can be applicable to numerous other communication systems, including other cellular communications systems beyond 5G new radio systems. For example, aspects of the described techniques can 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, as well as other systems and radio technologies not explicitly mentioned herein.

[0337] Information and signals described herein can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0338] The various illustrative blocks and components described herein can be implemented or performed with a general-purpose processor, a DSP, an ASIC, a CPU, a 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 can be a microprocessor, but in the alternative, the processor can be any processor, controller, microcontroller, or state machine. A processor can 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).

[0339] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations thereof. Features implementing functions can also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

[0340] 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. A non-transitory storage medium can 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 can 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 the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0341] As used herein, including in the claims “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of’ or “one or more of’) indicates an inclusive list such that, 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, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” can be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on.”

[0342] In the drawings, like reference numerals refer to items of like functionality. In addition, the various features of the figures can be identified, where appropriate, with a letter or number that characterizes an aspect of the example. If only the first reference numeral is used in the text, the description can be applicable to any one of the similar functionalities of the figures having the same first reference numeral, regardless of the second reference numeral, or other subsequent reference numerals.

[0343] The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that can be implemented or that are within the scope of the claims. The term “example” used herein means “serving as an example, instance, or illustration,” and not “preferred” over other examples. The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, can be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0344] The description herein is presented to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. An apparatus for performing wireless communication at a first user equipment (UE), the apparatus comprising: A processing system, comprising one or more processors and one or more memories coupled to the one or more processors, the processing system being configured to cause the device to: During a first transmission time interval, a first sidelink control information message associated with a first sidelink transmission from the first UE is transmitted, wherein the first sidelink control information message includes a first indication of a set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission times, wherein the first sidelink control information message further includes a first identifier that associates the first sidelink control information message with the first UE, a second UE to which the first sidelink transmission is directed, or both. During a second transmission time interval following the first transmission time interval, at least in part based on a second side link control information message including a second identifier, the second side link control information message provides the release of at least a first subset of the resource set reserved by the first side link control information message, the second identifier associating the second side link control information message with the same UE identified by the first identifier; as well as Based on the release of the first subset of the resource set, retransmissions of the first sidelink transmission are transmitted only on the second subset of the resource set.

2. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: The release is identified as relating to at least the first subset of the resource set based at least in part on a first time or frequency relationship between the first sidelink control information message and the second sidelink control information message, a second time or frequency relationship between the second sidelink control information message and the first subset of the resource set, or both of these. The release is related to at least one of the one or more retransmission opportunities.

3. The apparatus of claim 2, wherein, The processing system is further configured to enable the device to: The release is identified as being related to the at least one retransmission timing, based at least in part on the first time or frequency relationship to determine that the difference between the first transmission time interval and the second transmission time interval satisfies a threshold difference, wherein the threshold difference is at least in part based on a configured hybrid automatic repeat request feedback time, and the release is identified as being related to the at least one retransmission timing based at least in part on the difference satisfying the threshold difference.

4. The apparatus of claim 2, wherein, The processing system is further configured to enable the device to: The first sub-channel of the first sidelink control information message and the second sub-channel of the second sidelink control information message are determined to be within a threshold range based at least in part on the first time or frequency relationship, wherein the threshold range is at least in part based on the first physical sidelink shared channel resources during the first transmission time interval and the second physical sidelink shared channel resources during the second transmission time interval, wherein the release is identified as being related to the at least one retransmission timing based at least in part on the threshold range being satisfied.

5. The apparatus of claim 2, wherein, The processing system is further configured to enable the device to: The second transmission time interval and the sub-channel of the second side link control information message are determined to be within a threshold amount of the at least one retransmission timing based at least in part on the second time or frequency relationship, wherein the release is identified as being related to the at least one retransmission timing based at least in part on the threshold amount being met.

6. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: The second side link control information message is identified within the resource set reserved for retransmissions transmitted for the first side link; as well as The release is identified, at least in part, based on a second sidelink control information message that identifies the resource set as being related to at least a first subset of the resource set.

7. The apparatus of claim 2, wherein, The processing system is further configured to enable the device to: The second transmission time interval or at least one of the sub-channels of the second side link control information message is identified as being within the configured range of the first side link control information message, at least in part based on the first time or frequency relationship. as well as The release is identified in relation to the at least one retransmission timing based at least in part on the fact that the configured range is satisfied.

8. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: The release is identified in at least partly based on the transmission time interval and subchannel of the one or more retransmission opportunities, relating to at least the first subset of the resource set.

9. The apparatus of claim 2, wherein, The processing system is further configured to enable the device to: Receive a control message indicating the first time or frequency relationship, the second time or frequency relationship, or both; and The release is identified in relation to the at least one retransmission timing based at least in part on the first time or frequency relationship, the second time or frequency relationship, or both.

10. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: Determine the time-domain resource allocation field value, the frequency-domain resource allocation field value, the cyclic redundancy check portion of the first side-link control information message, or any combination thereof; as well as The release is identified as being related to at least a first subset of the resource set, based at least in part on the time-domain resource allocation field value, the frequency-domain resource allocation field value, the cyclic redundancy check portion of the first side-link control information message, or any combination thereof.

11. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: The second sidelink control information message identifies that it includes second data, the second data including a checksum or hash function of at least a portion of the first data included in the first sidelink control information message; and The release is identified, at least in part, as being related to at least a first subset of the resource set, based on the checksum or hash function of the second data included in the second sidelink control information message and the first data included in the first sidelink control information message.

12. The apparatus as claimed in claim 11, The first data includes a first cyclic redundancy check portion of the first sidelink control information message, a time-domain resource allocation value set of the first sidelink control information message, a frequency-domain resource allocation value set of the first sidelink control information message, or any combination thereof; and The second data includes the second cyclic redundancy check portion of the second side link control information message, the second frequency domain resource allocation value set of the second side link control information message, the demodulation reference signal bit value set of the second side link control information message, or any combination thereof.

13. The apparatus of claim 1, wherein, The second sidelink control information message includes one or more time-domain resource allocation field values ​​indicating a second resource set reserved for retransmission of the second sidelink.

14. The apparatus of claim 13, wherein, The second side link transmission includes retransmission of the second side link control information message, data transmission via the physical side link shared channel, or any combination thereof.

15. The apparatus of claim 13, wherein, The one or more time-domain resource allocation field values ​​include one or more time resource indicator values ​​that are not related to time resource reservation.

16. The apparatus of claim 13, wherein, The processing system is further configured to enable the device to: A control message is received that includes an indication of a set of time resource indicator values, the set of time resource indicator values ​​including a first subset of time resource indicator values ​​associated with time resource reservation and a second subset of time resource indicator values ​​unrelated to time resource reservation, wherein the one or more time domain resource allocation field values ​​in the second side link control information message include time resource indicator values ​​from the second subset of time resource indicator values.

17. The apparatus of claim 13, wherein, The processing system is further configured to enable the device to: Identify one or more additional fields within the second-side link control information message; and The release is identified in at least a first subset of the resource set at which the one or more retransmissions occur, based at least in part on the one or more time-domain resource allocation field values, the one or more additional fields in the second side link control information message, or both.

18. The apparatus of claim 17, wherein, The one or more additional fields in the second sidelink control information message include a first field associated with a demodulation reference signal, a second field associated with a port used for demodulation reference signal, a third field associated with the priority of sidelink communication, a fourth field associated with physical sidelink feedback channel overhead, a fifth field associated with frequency domain resource allocation, or any combination thereof.

19. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: The first side link transmission is transmitted according to the first side link control information message; and The second UE receives a feedback message indicating that it has received the first sidelink transmission, wherein the UE identifies the second sidelink control information message by generating a second sidelink control information message based at least in part on the feedback message.

20. The apparatus of claim 1, wherein, The second side link control information message includes receiving the second side link control information message from the second UE.

21. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: The period is identified prior to the first retransmission opportunity in the one or more retransmission opportunities, during which at least the first retransmission opportunity will not be released, wherein the second side link control information message is identified before the start of the identified period.

22. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: The period of time following the transmission of the first side link control information message is identified, during which the one or more retransmission opportunities will not be released, wherein the second side link control information message is identified after the end of the identified period of time.

23. The apparatus of claim 22, wherein, The processing system is further configured to enable the device to: Identify a hybrid automatic repeat request configuration associated with sidelink communication, wherein the time period identified after the transmission of the first sidelink control information message is at least partially based on the hybrid automatic repeat request configuration.

24. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: A third sidelink transmission is received on a resource set associated with at least the first subset of the resource set released via the second sidelink control information message from the second UE, the third UE, or both of the first sidelink transmission, wherein the third sidelink transmission is received at least in part based on identifying the second sidelink control information message.

25. The apparatus of claim 1, wherein, Retransmission of the first sidelink transmission only on a second subset of the resource set includes suppressing any retransmissions of the first sidelink transmission.

26. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: The candidate resource set for transmitting the second side link control information message is identified at least in part based on the transmission of the first side link control information message, wherein the candidate resource set has a higher priority for being selected for transmitting the second side link control information message than for being selected for other side link transmission messages. as well as The resource set for transmitting the second side link control information message is selected from the candidate resource set, at least in part, based on the fact that the candidate resource set has a higher priority.

27. The apparatus of claim 1, wherein, The processing system is further configured to enable the device to: Before transmitting the second sidelink control information message, determine the first channel occupancy rate of the sidelink communication network; and The second channel occupancy rate of the sidelink communication network is determined at least in part based on the release provided by the second sidelink control information message that identifies the second sidelink.

28. The apparatus of claim 1, wherein, The second side link control information message is transmitted with a specified priority, which is higher than the priority associated with other transmissions.

29. A method for wireless communication at a first user equipment (UE), the method comprising: During a first transmission time interval, a first sidelink control information message associated with a first sidelink transmission from the first UE is transmitted, wherein the first sidelink control information message includes a first indication of a set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission times, wherein the first sidelink control information message further includes a first identifier that associates the first sidelink control information message with the first UE, a second UE to which the first sidelink transmission is directed, or both. During a second transmission time interval following the first transmission time interval, at least in part based on a second side link control information message including a second identifier, the second side link control information message provides the release of at least a first subset of the resource set reserved by the first side link control information message, the second identifier associating the second side link control information message with the same UE identified by the first identifier; as well as Based on the release of the first subset of the resource set, retransmissions of the first sidelink transmission are transmitted only on the second subset of the resource set.

30. An apparatus for performing wireless communication at a first user equipment (UE), the apparatus comprising: A means for transmitting a first sidelink control information message associated with a first sidelink transmission from the first UE during a first transmission time interval, wherein the first sidelink control information message includes a first indication of a set of resources reserved for retransmission of the first sidelink transmission at one or more retransmission times, wherein the first sidelink control information message further includes a first identifier that associates the first sidelink control information message with the first UE, a second UE to which the first sidelink transmission is directed, or both. A means for identifying, at least in part, a second side link control information message that provides the release of at least a first subset of the resource set reserved by the first side link control information message during a second transmission time interval following the first transmission time interval, based on a second side link control information message including a second identifier, wherein the second identifier associates the second side link control information message with the same UE identified by the first identifier. as well as A means for transmitting a retransmission of the first sidelink transmission only on a second subset of the resource set, based on the release of a first subset of the resource set.

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