Techniques for dynamic scheduling of reverse sidelink traffic

Abstract

Methods, systems, and apparatus for wireless communications are described. A first user equipment (UE) may determine a first set of resources for communication over a sidelink communication link between the first UE and a second UE. The first UE may send first sidelink control information including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on determining the first set of resources. The first UE may send second sidelink control information to the second UE via the sidelink communication link, the second sidelink control information indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE over the sidelink communication link, wherein sending the second sidelink control information is based on sending the first sidelink control information. The first UE may receive a reverse sidelink message from the second UE in response to sending the second sidelink control information.

Description

[0001] Cross-references

[0002] This patent application claims priority to U.S. patent application No. 17 / 353,405, filed by FONG et al. on June 21, 2021, entitled “TECHNIQUES FOR DYNAMIC SCHEDULING OF REVERSE SIDELINK TRAFFIC,” which claims priority to U.S. provisional patent application No. 63 / 042,308, filed by FONG et al. on June 22, 2020, entitled “TECHNIQUES FOR DYNAMIC SCHEDULING OF REVERSE SIDELINK TRAFFIC,” which is assigned to the assignee of this application. Technical Field

[0003]

[0014] The following relates generally to wireless communications, and more particularly, to scheduling sidelink communications. Background Art

[0004] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, etc. 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 (e.g., long term evolution (LTE) systems, improved LTE (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 may employ 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 spread 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 base station or network access node simultaneously supporting communication for multiple communication devices (which may also be referred to as user equipment (UE)). Summary of the Invention

[0005] A method for wireless communication at a first user equipment (UE) is described. The method may include sending first sidelink control information (SCI) indicating a first set of resources to a second UE via a sidelink communication link. The method may also include sending second sidelink control information including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on the first set of resources, wherein sending the second sidelink control information is based on sending the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The method may also include receiving a reverse sidelink message from the second UE in response to sending the second sidelink control information.

[0006] An apparatus for wireless communication at a first UE is described. The apparatus may include a processor and a memory coupled to the processor, the processor and the memory being configured to: send first sidelink control information indicating a first set of resources to a second UE via a sidelink communication link. The processor and the memory may also be configured to: send second sidelink control information including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on the first set of resources, wherein sending the second sidelink control information is based on sending the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The processor and the memory may also be configured to: receive a reverse sidelink message from the second UE in response to sending the second sidelink control information.

[0007] Another apparatus for wireless communication at a first UE is described. The apparatus may include: means for transmitting first sidelink control information indicating a first set of resources to a second UE via a sidelink communication link; and means for transmitting second sidelink control information including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on the first set of resources, wherein transmitting the second sidelink control information is based on transmitting the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The apparatus may also include: means for receiving a reverse sidelink message from the second UE in response to transmitting the second sidelink control information.

[0008] A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions executable by a processor to perform the following operations: sending first sidelink control information indicating a first set of resources to a second UE via a sidelink communication link. The processor and memory may also be configured to: send second sidelink control information including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on the first set of resources, wherein sending the second sidelink control information is based on sending the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The processor and memory may also be configured to: receive a reverse sidelink message from the second UE in response to sending the second sidelink control information.

[0009] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending, via the second sidelink control information, an indication of a request to send a new reverse sidelink message, a retransmission of a previous reverse sidelink message, or both, to the second UE, wherein receiving the reverse sidelink message may be in response to sending the indication of the request.

[0010] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending, via the second sidelink control information, a hybrid automatic repeat request (HARQ) process identifier associated with the reverse sidelink transmission from the second UE to the first UE.

[0011] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, means, or instructions for sending a feedback message to the second UE in response to receiving the reverse sidelink message and the HARQ process identifier.

[0012] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following operations: sending a sidelink grant via the sidelink communication link, the sidelink grant indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE, wherein receiving the reverse sidelink message can be based on sending the sidelink grant.

[0013] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending an indication of a modulation and coding scheme (MCS) associated with the reverse sidelink message via at least one of the first sidelink control information or the second sidelink control information, wherein receiving the reverse sidelink message may be based on sending the indication of the MCS.

[0014] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending an indication of a redundant version associated with the reverse sidelink message via the second sidelink control information, wherein receiving the reverse sidelink message may be based on sending the indication of the redundant version.

[0015] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving third sidelink control information, fourth sidelink control information, or both from the second UE, wherein receiving the reverse sidelink message may be based on receiving the third sidelink control information, the fourth sidelink control information, or both.

[0016] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the second sidelink control information indicates a second set of resources for reverse sidelink transmission from the second UE to the first UE via a sidelink communication link, and the reverse sidelink message can be received within the second set of resources.

[0017] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for monitoring the second set of resources associated with the reverse sidelink transmission from the second UE to the first UE based on sending the second sidelink control information, wherein receiving the reverse sidelink message may be based on monitoring the second set of resources.

[0018] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the second set of resources includes a set of time resources and a set of frequency resources allocated for the reverse sidelink transmission from the second UE to the first UE over the sidelink communication link.

[0019] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second sidelink control information, wherein receiving the reverse sidelink message may be based on the indication of the first identifier and the indication of the second identifier.

[0020] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following operations: sending the first sidelink control information via a physical sidelink control channel (PSCCH); and sending the second sidelink control information via a physical sidelink shared channel (PSSCH).

[0021] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first sidelink control information includes first-level sidelink control information, and the second sidelink control information includes second-level sidelink control information.

[0022] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the reverse sidelink scheduling indicator may be indicated in a bit field of the second sidelink control information.

[0023] A method for wireless communication at a first UE is described. The method may include receiving, via a sidelink communication link between the first UE and a second UE, first sidelink control information including a first resource set indicating a first resource set from the second UE. The method may also include receiving, via the sidelink communication link, second sidelink control information including a reverse sidelink scheduling indicator from the second UE based on the first resource set, wherein receiving the second sidelink control information is based on receiving the first sidelink control information, the second sidelink control information being different from the first sidelink control information. The method may also include sending a reverse sidelink message to the second UE in response to receiving the second sidelink control information.

[0024] A device for wireless communication at a first UE is described. The device may include a processor and a memory coupled to the processor, the processor and the memory being configured to: receive first sidelink control information including a first resource set from a second UE via a sidelink communication link between the first UE and the second UE. The processor and the memory may also be configured to cause the device to perform the following operations: receive second sidelink control information including a reverse sidelink scheduling indicator from the second UE via the sidelink communication link based on the first resource set, wherein receiving the second sidelink control information is based on receiving the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The processor and the memory may also be configured to cause the device to perform the following operations: in response to receiving the second sidelink control information, send a reverse sidelink message to the second UE.

[0025] Another apparatus for wireless communication at a first UE is described. The apparatus may include means for receiving, via a sidelink communication link between the first UE and a second UE, first sidelink control information including a first resource set indicating a first resource set from the second UE. The apparatus may also include means for receiving, via the sidelink communication link, second sidelink control information including a reverse sidelink scheduling indicator from the second UE based on the first resource set, wherein receiving the second sidelink control information is based on receiving the first sidelink control information, the second sidelink control information being different from the first sidelink control information. The apparatus may also include means for sending a reverse sidelink message to the second UE in response to receiving the second sidelink control information.

[0026] A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions executable by a processor to perform the following operations: receiving first sidelink control information including a first resource set from a second UE via a sidelink communication link between the first UE and the second UE. The processor and memory may also be configured to: receive second sidelink control information including a reverse sidelink scheduling indicator from the second UE via the sidelink communication link based on the first resource set, wherein receiving the second sidelink control information is based on receiving the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The processor and memory may also be configured to: send a reverse sidelink message to the second UE in response to receiving the second sidelink control information.

[0027] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving, via the second sidelink control information, an indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both, to the second UE, wherein sending the reverse sidelink message may be in response to receiving the indication of the request.

[0028] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving, via the second sidelink control information, a HARQ process identifier associated with the reverse sidelink transmission from the first UE to the second UE.

[0029] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, means, or instructions for receiving a feedback message from the second UE in response to sending the reverse sidelink message and the HARQ process identifier.

[0030] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving a sidelink grant from the second UE via the sidelink communication link, the sidelink grant indicating a set of resources for reverse sidelink transmission from the first UE to the second UE, wherein sending the reverse sidelink message may be based on receiving the sidelink grant.

[0031] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving an indication of an MCS associated with the reverse sidelink message via at least one of the first sidelink control information or the second sidelink control information, wherein sending the reverse sidelink message may be based on receiving the indication of the MCS.

[0032] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving, via the second sidelink control information, an indication of a redundant version associated with the reverse sidelink message, wherein sending the reverse sidelink message may be based on receiving the indication of the redundant version.

[0033] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending third sidelink control information, fourth sidelink control information, or both to the second UE, wherein sending the reverse sidelink message may be based on sending the third sidelink control information, the fourth sidelink control information, or both.

[0034] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the second sidelink control information indicates a set of resources used for reverse sidelink transmission from the second UE to the first UE via a sidelink communication link, and the reverse sidelink message can be sent within the set of resources.

[0035] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the set of resources includes a set of time resources and a set of frequency resources allocated for the reverse sidelink transmission from the first UE to the second UE over the sidelink communication link.

[0036] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second sidelink control information, wherein sending the reverse sidelink message may be based on the indication of the first identifier and the indication of the second identifier.

[0037] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, means, or instructions for receiving the first sidelink control information via a PSCCH; and receiving the second sidelink control information via a PSSCH.

[0038] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first sidelink control information includes first-level sidelink control information, and the second sidelink control information includes second-level sidelink control information, and the reverse sidelink scheduling indicator can be indicated in a bit field of the second sidelink control information.

[0039] A method is described. The method may include: sending first sidelink control information including a reverse sidelink scheduling indicator to a second UE via a sidelink communication link; and sending second sidelink control information to the second UE via the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second sidelink control information is based on sending the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The method may also include: receiving a reverse sidelink message from the second UE in response to sending the second sidelink control information.

[0040] A device is described. The device may include a processor and a memory coupled to the processor, the processor and the memory being configured to: send first sidelink control information including a reverse sidelink scheduling indicator to a second UE via a sidelink communication link. The processor and the memory may also be configured to cause the device to perform the following operations: send second sidelink control information to the second UE via the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second sidelink control information is based on sending the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The processor and the memory may also be configured to cause the device to perform the following operations: in response to sending the second sidelink control information, receive a reverse sidelink message from the second UE.

[0041] Another apparatus is described. The apparatus may include: means for sending first sidelink control information including a reverse sidelink scheduling indicator to a second UE via a sidelink communication link; and means for sending second sidelink control information to the second UE via the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second sidelink control information is based on sending the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The apparatus may also include: means for receiving a reverse sidelink message from the second UE in response to sending the second sidelink control information.

[0042] A non-transitory computer-readable medium storing code is described. The code may include instructions executable by a processor to perform the following operations: send first sidelink control information including a reverse sidelink scheduling indicator to a second UE via a sidelink communication link. The processor and memory may also be configured to send second sidelink control information to the second UE via the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second sidelink control information is based on sending the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The processor and memory may also be configured to receive a reverse sidelink message from the second UE in response to sending the second sidelink control information.

[0043] A method is described. The method may include receiving, via a sidelink communication link between a first UE and a second UE, first sidelink control information including a reverse sidelink scheduling indicator from the second UE. The method may also include receiving, via the sidelink communication link, second sidelink control information from the second UE, the second sidelink control information indicating a set of resources to be used for reverse sidelink transmission from the first UE to the second UE over the sidelink communication link, wherein receiving the second sidelink control information is based on receiving the first sidelink control information, the second sidelink control information being different from the first sidelink control information. The method may also include sending, in response to receiving the second sidelink control information, a reverse sidelink message to the second UE.

[0044] A device is described. The device may include a processor and a memory coupled to the processor, the processor and the memory being configured to: receive first sidelink control information including a reverse sidelink scheduling indicator from a first UE and a second UE via a sidelink communication link between the second UE. The processor and the memory may also be configured to cause the device to perform the following operations: receive second sidelink control information from the second UE via the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second sidelink control information is based on receiving the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The processor and the memory may also be configured to cause the device to perform the following operations: in response to receiving the second sidelink control information, send a reverse sidelink message to the second UE.

[0045] Another apparatus is described. The apparatus may include means for receiving first sidelink control information including a reverse sidelink scheduling indicator from a first UE via a sidelink communication link between the second UE. The apparatus may also include means for receiving second sidelink control information from the second UE via the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second sidelink control information is based on receiving the first sidelink control information, the second sidelink control information being different from the first sidelink control information. The apparatus may also include means for sending a reverse sidelink message to the second UE in response to receiving the second sidelink control information.

[0046] A non-transitory computer-readable medium storing code is described. The code may include instructions executable by a processor to perform the following operations: receiving first sidelink control information including a reverse sidelink scheduling indicator from a first UE and a second UE via a sidelink communication link between the second UE. The processor and memory may also be configured to: receive second sidelink control information from the second UE via the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second sidelink control information is based on receiving the first sidelink control information, and the second sidelink control information is different from the first sidelink control information. The processor and memory may also be configured to: send a reverse sidelink message to the second UE in response to receiving the second sidelink control information.

[0047] A method of wireless communication at a first UE is described. The method may include determining a first set of resources for communication via a sidelink communication link between the first UE and a second UE; and sending a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on determining the first set of resources. The method may further include sending a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI; and receiving a reverse sidelink message from the second UE in response to sending the second SCI.

[0048] An apparatus for wireless communication at a first UE is described. The apparatus may include a processor and a memory coupled to the processor, the processor and the memory being configured to: determine a first set of resources for communication via a sidelink communication link between the first UE and a second UE; and send a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on determining the first set of resources. The processor and the memory may also be configured to: send a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI; and receive a reverse sidelink message from the second UE in response to sending the second SCI.

[0049] Another apparatus for wireless communication at a first UE is described. The apparatus may include: means for determining a first set of resources for communication via a sidelink communication link between the first UE and a second UE; and means for sending a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on determining the first set of resources. The apparatus may also include: means for sending a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI; and means for receiving a reverse sidelink message from the second UE in response to sending the second SCI.

[0050] A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions executable by a processor to: determine a first set of resources for communication via a sidelink communication link between the first UE and a second UE; and send a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on determining the first set of resources. The processor and the memory may also be configured to: send a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI; and receive a reverse sidelink message from the second UE in response to sending the second SCI.

[0051] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending a sidelink grant via the sidelink communication link, the sidelink grant indicating the second set of resources for reverse sidelink transmission from the second UE to the first UE, wherein receiving the reverse sidelink message may be based on receiving the sidelink grant.

[0052] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending an indication of an MCS associated with the reverse sidelink message via at least one of the first SCI or the second SCI, wherein receiving the reverse sidelink message may be based on sending the indication of the MCS.

[0053] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending an indication of a redundant version associated with the reverse sidelink message via the second SCI, wherein receiving the reverse sidelink message may be based on sending the indication of the redundant version.

[0054] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending, via the second SCI, an indication of a request to send a new reverse sidelink message, a retransmission of a previous reverse sidelink message, or both, to the second UE, wherein receiving the reverse sidelink message may be in response to sending the indication of the request.

[0055] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending, via the second SCI, a hybrid automatic repeat request (HARQ) process identifier associated with the reverse sidelink transmission from the second UE to the first UE.

[0056] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, means, or instructions for sending a feedback message to the second UE in response to receiving the reverse sidelink message and the HARQ process identifier.

[0057] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving a third SCI, a fourth SCI, or both from the second UE, wherein receiving the reverse sidelink message may be based on receiving the third SCI, the fourth SCI, or both.

[0058] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for performing the following operations: monitoring the second set of resources associated with the reverse sidelink transmission from the second UE to the first UE based on sending the second SCI, wherein receiving the reverse sidelink message can be based on monitoring the second set of resources.

[0059] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second SCI, wherein receiving the reverse sidelink message may be based on the indication of the first identifier and the indication of the second identifier.

[0060] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the second set of resources includes a set of time resources and a set of frequency resources allocated for the reverse sidelink transmission from the second UE to the first UE over the sidelink communication link.

[0061] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, means, or instructions for: transmitting the first SCI via a PSCCH; and transmitting the second SCI via a PSSCH.

[0062] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first SCI comprises a first type of SCI, and wherein the second SCI comprises a second type of SCI different from the first type of SCI.

[0063] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first SCI comprises a first-level SCI, and wherein the second SCI comprises a second-level SCI.

[0064] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the reverse sidelink scheduling indicator may be indicated in a bit field of the first SCI.

[0065] A method of wireless communication at a first UE is described. The method may include: receiving a first SCI including a reverse sidelink scheduling indicator from a second UE via a sidelink communication link between the first UE and the second UE; receiving a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources to be used for reverse sidelink transmission from the first UE to the second UE over the sidelink communication link, wherein receiving the second SCI is based on receiving the first SCI; and sending a reverse sidelink message to the second UE in response to receiving the second SCI.

[0066] An apparatus for wireless communication at a first UE is described. The apparatus may include a processor and a memory coupled to the processor, the processor and the memory being configured to: receive a first SCI including a reverse sidelink scheduling indicator from a second UE via a sidelink communication link between the first UE and the second UE. The processor and the memory may also be configured to: receive a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources to be used for reverse sidelink transmission from the first UE to the second UE over the sidelink communication link, wherein receiving the second SCI is based on receiving the first SCI; and, in response to receiving the second SCI, send a reverse sidelink message to the second UE.

[0067] Another apparatus for wireless communication at a first UE is described. The apparatus may include: means for receiving, via a sidelink communication link between the first UE and a second UE, a first SCI including a reverse sidelink scheduling indicator from the second UE. The apparatus may also include: means for receiving, via the sidelink communication link, a second SCI from the second UE, the second SCI indicating a set of resources to be used for reverse sidelink transmission from the first UE to the second UE over the sidelink communication link, wherein receiving the second SCI is based on receiving the first SCI; and means for sending a reverse sidelink message to the second UE in response to receiving the second SCI.

[0068] A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions executable by a processor to: receive, from a second UE via a sidelink communication link between the first UE and the second UE, a first SCI including a reverse sidelink scheduling indicator. The processor and memory may also be configured to: receive, from the second UE via the sidelink communication link, a second SCI indicating a set of resources to be used for reverse sidelink transmission from the first UE to the second UE over the sidelink communication link, wherein receiving the second SCI is based on receiving the first SCI; and, in response to receiving the second SCI, send a reverse sidelink message to the second UE.

[0069] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving a sidelink grant via the sidelink communication link, the sidelink grant indicating the second set of resources for reverse sidelink transmission from the second UE to the first UE, wherein sending the reverse sidelink message may be based on receiving the sidelink grant.

[0070] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving an indication of an MCS associated with the reverse sidelink message via at least one of the first SCI or the second SCI, wherein sending the reverse sidelink message may be based on receiving the indication of the MCS.

[0071] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving, via the second SCI, an indication of a redundant version associated with the reverse sidelink message, wherein sending the reverse sidelink message may be based on receiving the indication of the redundant version.

[0072] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving, via the second SCI, an indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both, to the second UE, wherein sending the reverse sidelink message may be in response to receiving the indication of the request.

[0073] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, means, or instructions for receiving, via the second SCI, a HARQ process identifier associated with the reverse sidelink transmission from the first UE to the second UE.

[0074] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, means, or instructions for receiving a feedback message from the second UE in response to sending the reverse sidelink message and the HARQ process identifier.

[0075] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for sending a third SCI, a fourth SCI, or both to the second UE, wherein sending the reverse sidelink message may be based on sending the third SCI, the fourth SCI, or both.

[0076] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for receiving, via the second SCI, an indication of a first identifier associated with the first UE and a second identifier associated with the second UE, wherein sending the reverse sidelink message may be based on the indication of the first identifier and the indication of the second identifier.

[0077] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the set of resources includes a set of time resources and a set of frequency resources allocated for the reverse sidelink transmission from the first UE to the second UE over the sidelink communication link.

[0078] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may also include operations, features, means, or instructions for: receiving the first SCI via a PSCCH; and receiving the second SCI via a PSSCH.

[0079] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first SCI comprises a first type of SCI, and wherein the second SCI comprises a second type of SCI different from the first type of SCI.

[0080] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first SCI comprises a first-level SCI, and wherein the second SCI comprises a second-level SCI.

[0081] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the reverse sidelink scheduling indicator may be indicated in a bit field of the first SCI. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1

[0014] An example of a wireless communication system supporting techniques for dynamic scheduling of reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown.

[0083] Figure 2

[0014] An example of a wireless communication system supporting techniques for dynamic scheduling of reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown.

[0084] Figure 3 An example of a process flow for techniques supporting dynamic scheduling for reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown.

[0085] Figure 4 and 5 A block diagram of a device supporting techniques for dynamic scheduling of reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown.

[0086] Figure 6 A block diagram of a communications manager supporting techniques for dynamic scheduling of reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown.

[0087] Figure 7 A diagram illustrating a system including devices supporting techniques for dynamic scheduling of reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown.

[0088] Figures 8 to 13 A flow chart illustrating a method of supporting techniques for dynamic scheduling of reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0089] A wireless system may support an access link (e.g., a Uu link) and a sidelink (e.g., a sidelink communication link, a PC5 link, or other link between wireless devices) for communication between wireless devices. An access link may refer to a communication link through which a UE accesses a wireless communication system, such as a communication link between a UE and a base station. In contrast, a sidelink may refer to a communication link between UEs, such as a communication link between a first UE and a second UE. In some cases, a base station may send an authorization (e.g., a dynamic authorization, a configured authorization) indicating the time and frequency resources allocated for sidelink communication via a sidelink communication link between a first UE and a second UE. However, in some wireless communication systems, a base station may schedule sidelink transmissions from each UE separately. For example, in order to schedule a sidelink transmission from a first UE to a second UE, the base station may send a grant to the first UE indicating the time and frequency resources for the sidelink transmission to the second UE. Similarly, in order to schedule a sidelink transmission from a second UE to a first UE, the base station may send a grant to the second UE indicating the time and frequency resources for the sidelink transmission to the first UE. However, separately scheduling the sidelink transmissions from the first UE and the second UE may increase control signaling overhead and resource usage. In addition, separately scheduling the sidelink transmissions with each UE may require an access procedure and / or a setup procedure between each respective UE and the base station, which further increases the control signaling overhead and resource usage within the wireless communication system. In addition, low complexity or low capability UEs may not have a sophisticated understanding of the traffic within the sidelink network, and therefore may cause interference within the sidelink network when they receive authorization directly from the base station and schedule their own sidelink transmissions based on the received authorization. For the purposes of the present disclosure, the terms "low complexity UE", "low capability UE", etc. may be used to refer to UEs that exhibit poorer processing capabilities, poorer channel knowledge, etc. compared to "high complexity UE" or "high capability UE". In this regard, these terms will be regarded as relative terms used to help explain the features described herein.

[0090] The techniques described herein relate to signaling for dynamic scheduling of reverse sidelink traffic. In particular, the techniques described herein enable a first UE to dynamically schedule sidelink traffic from a second UE to the first UE (e.g., schedule reverse sidelink traffic). By enabling a UE to schedule sidelink communications at other UEs, the techniques described herein can reduce the control signaling overhead associated with control signaling from a base station. For purposes of the present disclosure, terms such as "sidelink traffic," "sidelink message," and terms such as "reverse sidelink traffic," "reverse sidelink message," can refer to the direction of the sidelink transmission from the perspective of a UE scheduling a sidelink transmission. For example, from the perspective of a first UE (e.g., a "scheduling" UE), a sidelink message can refer to a sidelink transmission sent from the first UE to the second UE. Conversely, a reverse sidelink message can refer to a sidelink transmission sent from the second UE to the first UE.

[0091] According to some aspects of the present disclosure, a first UE may send an SCI to a second UE, wherein the SCI schedules a reverse sidelink transmission from the second UE to the first UE. For example, the first UE may receive a grant from a base station that indicates a first set of resources allocated for sidelink transmission between the first UE and the second UE. In this example, the first UE may send one or more SCIs to the second UE that indicate a second set of resources allocated for reverse sidelink transmission from the second UE to the first UE. In some cases, the SCI (e.g., a first-level SCI / SCI 0–1 or a second-level SCI / SCI0-2) may include a reverse sidelink scheduling indicator that indicates to the second UE the dynamic scheduling of the reverse sidelink traffic by the first UE. The reverse sidelink scheduling indicator may be indicated in a bit field of the SCI. For the purposes of the present disclosure, the term "reverse sidelink scheduling indicator" may refer to any indicator or bit field value used to indicate the dynamic scheduling of the reverse sidelink traffic.

[0092] In some aspects, a second or additional SCI (e.g., a second-level SCI or SCI 0–2) may indicate various parameters associated with the scheduled reverse sidelink transmission. Parameters associated with the reverse sidelink transmission may include a modulation and coding scheme (MCS), a redundancy version, a hybrid automatic repeat request (HARQ) process identifier, and the like. In an additional or alternative implementation, the second SCI may include a reverse sidelink scheduling indicator. The second UE may then send a reverse sidelink message to the first UE based on the reverse sidelink scheduling indicator indicated in the first SCI, the second SCI, or both, and one or more parameters indicated in the second SCI. By enabling a UE to schedule reverse sidelink transmissions from other UEs, control signaling overhead within a wireless communication system may be reduced. In addition, the techniques described herein may enable a higher complexity UE to schedule reverse sidelink transmissions from a lower complexity UE, thereby reducing potential interference and improving wireless signaling reliability.

[0093] Various aspects of the present disclosure are first described in the context of a wireless communication system. Additional aspects of the present disclosure are described in the context of an example process flow. Aspects of the present disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flow charts relating to techniques for dynamic scheduling of reverse sidelink traffic.

[0094] Figure 1 An example of a wireless communication system 100 that supports techniques for dynamic scheduling of reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown. The wireless communication system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an Advanced LTE (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission-critical) communications, low-latency communications, or communications with low-cost and low-complexity devices, or any combination thereof.

[0095] Base stations 105 may be dispersed throughout a geographic area to form wireless communication system 100 and may be devices of varying forms or capabilities. Base stations 105 may include a communication manager 101. Base stations 105 and UEs 115 may communicate wirelessly via one or more communication links 125. Each base station 105 may provide a coverage area 110 over which UEs 115 and base stations 105 may establish one or more communication links 125. Coverage areas 110 may be examples of geographic areas over which base stations 105 and UEs 115 may support transmission of signals according to one or more radio access technologies.

[0096] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary, mobile, or both at different times. The UEs 115 may be devices of different forms or with different capabilities. Figure 1 1. Some example UEs 115 are shown in FIG. 1. The UEs 115 described herein are capable of communicating with various types of devices, such as other UEs 115, base stations 105, or network devices (e.g., core network nodes, relays, integrated access and backhaul (IAB) nodes, or other network devices), such as Figure 1 UE 115 may include a communication manager 102.

[0097] The base stations 105 can communicate with the core network 130, or communicate with each other, or perform both operations described above. For example, the base stations 105 can interface with the core network 130 via one or more backhaul links 120 (e.g., via S1, N2, N3, or other interfaces). The base stations 105 can communicate with each other directly (e.g., directly between the base stations 105) or indirectly (e.g., via the core network 130) on the backhaul links 120 (e.g., via X2, Xn, or other interfaces), or perform both operations described above. In some examples, the backhaul links 120 can be or include one or more wireless links.

[0098] One or more of the base stations 105 described herein may include or may be referred to by those skilled in the art as a base station transceiver, a radio base station, an access point, a radio transceiver, a Node B, an evolved Node B (eNB), a next generation Node B, or a Gigabit Node B (any of which may be referred to as a gNB), a Home Node B, a Home evolved Node B, or some other appropriate terminology.

[0099] UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other appropriate terminology, where a "device" may also be referred to as a unit, a station, a terminal, or a client, among other examples. UE 115 may also include or may 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, UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communication (MTC) device, among other examples, which may be implemented in various items such as appliances, vehicles, meters, and other examples.

[0100] The UE 115 described herein is capable of communicating with various types of devices, such as other UEs 115, which may sometimes act as relays, as well as base stations 105 and network equipment, including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, such as Figure 1 shown.

[0101] The UE 115 and the base station 105 can communicate wirelessly with each other via one or more communication links 125 on one or more carriers. The term "carrier" can refer to a collection of radio frequency spectrum resources having a defined physical layer structure for supporting the communication link 125. For example, a carrier used for the communication link 125 can include a portion of a radio frequency spectrum band (e.g., a bandwidth part (BWP)) that operates according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel can carry acquisition signaling (e.g., synchronization signals, system information), control signaling to coordinate operation for the carrier, user data, or other signaling. The wireless communication system 100 can support communication with the UE 115 using carrier aggregation or multi-carrier operation. Depending on the carrier aggregation configuration, the UE 115 can be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation can be used with both frequency division duplex (FDD) component carriers and time division duplex (TDD) component carriers.

[0102] The signal waveform transmitted on the carrier may be composed of multiple subcarriers (e.g., using a multicarrier modulation (MCM) technique such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may comprise one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both). Therefore, the more resource elements received by the UE 115 and the higher the order of the modulation scheme, the higher the data rate for the UE 115 may be. Wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial layers may further increase the data rate or data integrity for communications with the UE 115.

[0103] The basic time unit (which may be referred to as T s =1 / (Δf max ·N f ) seconds sampling period, where Δf max It can represent the maximum supported subcarrier spacing, and N f The time intervals for the base station 105 or the UE 115 may be expressed as multiples of a maximum supported discrete Fourier transform (DFT) size. The time intervals of the communication resources may be organized according to radio frames, each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0104] Each frame may include a plurality of consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include a number of symbol periods (e.g., depending on the length of a cyclic prefix added in front of each symbol period). In some wireless communication systems 100, a time slot may be further divided into a plurality of mini-slots containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N f The duration of a symbol period may depend on the subcarrier spacing or the operating frequency band.

[0105] A subframe, slot, mini-slot, or symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in the form of bursts of shortened TTIs (sTTIs)).

[0106] Physical channels may be multiplexed on a carrier according to various techniques. For example, physical control channels and physical data channels may be multiplexed on a downlink carrier using one or more of time division multiplexing (TDM), frequency division multiplexing (FDM), or hybrid TDM-FDM techniques. A control region (e.g., a control resource set (CORESET)) for a physical control channel may be defined by a number of symbol periods and may extend across the system bandwidth of a carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESETs) may be configured for a group of UEs 115. For example, one or more of the UEs 115 may monitor or search the control region for control information according to one or more search space sets, and each search space set may include one or more control channel candidates at one or more aggregation levels arranged in a cascaded manner. The aggregation level for the control channel candidates may refer to the number of control channel resources (e.g., control channel elements (CCEs)) associated with the coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for transmitting control information to multiple UEs 115 and a UE-specific search space set for transmitting control information to a specific UE 115 .

[0107] In some examples, base station 105 can be mobile and, therefore, provide communication coverage for mobile geographic coverage areas 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 communication system 100 can include, for example, a heterogeneous network in which different types of base stations 105 use the same or different radio access technologies to provide coverage for various geographic coverage areas 110.

[0108] Some UEs 115 (e.g., MTC or IoT devices) may be low-cost or low-complexity devices and may provide automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technology that allows devices to communicate with each other or base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that incorporate sensors or meters to measure or capture information and relay such information to a central server or application that utilizes the information or presents it to a human interacting with the application. Some UEs 115 may be designed to collect information or implement automated behavior of machines or other equipment. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, climate and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based service billing.

[0109] The wireless communication system 100 can be configured to support ultra-reliable communication or low-latency communication, or various combinations thereof. For example, the wireless communication system 100 can be configured to support ultra-reliable low-latency communication (URLLC) or mission-critical communication. UE 115 can be designed to support ultra-reliable, low-latency or critical functions (e.g., mission-critical functions). Ultra-reliable communication 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 in this article.

[0110] In some examples, UE 115 can 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). In some aspects, communication link 135 may include an example of a sidelink communication link 135 (e.g., a PC5 link). One or more UEs 115 utilizing D2D communication may be within the geographic coverage area 110 of base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of base station 105 or otherwise unable to receive transmissions from base station 105. In some examples, groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, in which each UE 115 transmits to each other UE 115 in the group. In some examples, base station 105 facilitates scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving base station 105.

[0111] 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., UE 115). In some examples, the vehicles can communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination thereof. The vehicles can signal information related to traffic conditions, signal scheduling, weather, safety, emergency situations, or any other information related to the V2X system. In some examples, the vehicles in the V2X system can communicate with roadside infrastructure (such as roadside units) or communicate with the network via one or more network nodes (e.g., base station 105) using vehicle-to-network (V2N) communication, or both.

[0112] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function unit (AMF)) that manages access and mobility, and at least one user plane entity (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function unit (UPF)) that routes packets to or interconnects to an external network. The control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the core network 130. User IP packets may be transmitted through the user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to the network operator IP service 150. Operator IP services 150 may include access to the Internet, an intranet, an IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0113] Some of the network devices (e.g., base stations 105) may include subcomponents such as access network entities 140, which may be examples of access node controllers (ANCs). Each access network entity 140 may communicate with the UE 115 through one or more other access network transport entities 145 (which may be referred to as radio heads, smart radio heads, or transmit / receive points (TRPs)). Each access network transport entity 145 may include one or more antenna panels. In some configurations, the various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or consolidated into a single network device (e.g., base station 105).

[0114] The wireless communication system 100 may operate using one or more frequency bands, which may be in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). The region from 300 MHz to 3 GHz is referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features, but the waves may be sufficient to penetrate structures for macro cells to provide service to UEs 115 located indoors. Transmissions using UHF waves may be associated with smaller antennas and shorter distances (e.g., less than 100 kilometers) compared to transmissions using the lower frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0115] The electromagnetic spectrum is typically subdivided into various categories, bands, channels, etc. based on frequency / wavelength. In 5G NR, two initial operating bands have been identified with the frequency range names FR1 (410 MHz - 7.125 GHz) and FR2 (24.25 GHz - 52.6 GHz). The frequencies between FR1 and FR2 are typically referred to as mid-band frequencies. Although a portion of FR1 is greater than 6 GHz, FR1 is often (interchangeably) referred to as the "sub-6 GHz" band in various documents and articles. Similar naming issues sometimes arise with respect to FR2, which is often (interchangeably) referred to as the "millimeter wave" band in documents and articles, although it is different from the extremely high frequency (EHF) band (30 GHz - 300 GHz), which is identified as the "millimeter wave" band by the International Telecommunication Union (ITU).

[0116] Frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Recent 5G NR research has identified the operating bands of these mid-band frequencies as the frequency range designation FR3 (7.125 GHz–24.25 GHz). Frequency bands falling within FR3 may inherit FR1 characteristics and / or FR2 characteristics, and thus may effectively extend the characteristics of FR1 and / or FR2 to mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5G NR operation above 52.6 GHz. For example, three higher operating bands have been identified as the frequency range designations FR4a or FR4-1 (52.6 GHz–71 GHz), FR4 (52.6 GHz–114.25 GHz), and FR5 (114.25 GHz–300 GHz). Each of these higher frequency bands falls within the EHF band.

[0117] In view of the above, unless otherwise specified, it should be understood that if the term "sub-6 GHz" is used herein, it can be broadly referred to as a frequency that can be less than 6 GHz, can be within FR1, or can include mid-band frequencies. In addition, unless otherwise specified, it should be understood that if the term "millimeter wave" is used herein, it can be broadly referred to as a frequency that can include mid-band frequencies, can be within FR2, or can be within the EHF band.

[0118] The wireless communication system 100 can utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 can employ license assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band (such as the 5 GHz industrial, scientific, and medical (ISM) band). When operating in an unlicensed radio frequency spectrum band, devices (such as base stations 105 and UEs 115) can employ carrier sensing for conflict detection and avoidance. In some examples, operations in the unlicensed band can be based on a carrier aggregation configuration in combination with component carriers operating in a licensed band (e.g., LAA). Operations in the unlicensed spectrum can include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

[0119] The base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of the base station 105 or UE 115 may be located within one or more antenna arrays or antenna panels (which may support MIMO operations or transmit or receive beamforming). For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, the antennas or antenna arrays associated with the base station 105 may be located at different geographical locations. The base station 105 may have an antenna array having a number of rows and columns of antenna ports that the base station 105 may use to support beamforming for communications with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support radio frequency beamforming for signals transmitted via the antenna ports.

[0120] The base station 105 or UE 115 can use MIMO communication to take advantage of multipath signal propagation and improve spectral efficiency by sending or receiving multiple signals via different spatial layers. Such a technique may be referred to as spatial multiplexing. For example, a transmitting device may send multiple signals via different antennas or different combinations of antennas. Similarly, a receiving device may receive multiple signals via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords). Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) (where multiple spatial layers are sent to the same receiving device) and multi-user MIMO (MU-MIMO) (where multiple spatial layers are sent to multiple devices).

[0121] Beamforming (which may 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 form or direct an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming can be achieved by combining signals transmitted via antenna elements of an antenna array so that some signals propagating at a particular orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals transmitted via antenna elements can include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to the signals carried via the antenna elements associated with the device. Adjustments associated with each of the antenna elements can be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0122] As part of the beamforming operation, the base station 105 or the UE 115 can use beam scanning techniques. For example, the base station 105 can use multiple antennas or antenna arrays (e.g., antenna panels) to perform beamforming operations for directional communication with the UE 115. The base station 105 can transmit some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) multiple times in different directions. For example, the base station 105 can transmit signals according to different sets of beamforming weights associated with different transmission directions. The transmissions in different beam directions can be used (e.g., by a transmitting device (such as the base station 105) or by a receiving device (such as the UE 115)) to identify the beam direction for subsequent transmission or reception by the base station 105.

[0123] Base station 105 may transmit some signals (e.g., data signals associated with a particular receiving device (e.g., UE 115)) in a single beam direction (e.g., a direction associated with the receiving device). In some examples, the beam direction associated with transmissions along the single beam direction may be determined based on signals transmitted in one or more beam directions. For example, UE 115 may receive one or more of the signals transmitted by base station 105 in different directions and may report to base station 105 an indication of the signal received by UE 115 having the highest signal quality or otherwise acceptable signal quality.

[0124] In some examples, transmissions by a device (e.g., by a base station 105 or a UE 115) may be performed using multiple beam directions, and the device may use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from the base station 105 to the UE 115). The UE 115 may report feedback indicating precoding weights used for one or more beam directions, and the feedback may correspond to a configured number of beams across the system bandwidth or one or more subbands. The base station 105 may send reference signals (e.g., cell-specific reference signals (CRS), channel state information reference signals (CSI-RS)) that may be precoded or not precoded. The UE 115 may provide feedback for beam selection, which may 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 sent by base station 105 in one or more directions, UE 115 may employ similar techniques to send signals multiple times in different directions (e.g., to identify a beam direction for subsequent transmission or reception by UE 115) or to send signals in a single direction (e.g., to send data to a receiving device).

[0125] When receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from the base station 105, a receiving device (e.g., UE 115) can try multiple reception configurations (e.g., directional listening). For example, the receiving device can try multiple reception directions by receiving via different antenna subarrays, by processing the received signals according to different antenna subarrays, by receiving according to different sets of receive beamforming weights applied to the signals received at multiple antenna elements of the antenna array (e.g., different sets of directional listening weights), or by processing the received signals according to different sets of receive beamforming weights applied to the signals received at multiple antenna elements of the antenna array (any of the above operations can be referred to as "listening" according to different reception configurations or reception directions). In some examples, the receiving device can use a single reception configuration to receive along a single beam direction (e.g., when receiving data signals). A single receive configuration may be aligned on a beam direction determined based on listening according to different receive configuration directions (e.g., a beam direction determined to have the highest signal strength, highest signal-to-noise ratio (SNR), or otherwise acceptable signal quality based on listening according to multiple beam directions).

[0126] UE 115 and base station 105 can support retransmission of data to increase the likelihood that the data is successfully received. HARQ feedback is a technique for increasing the likelihood that data is correctly received on communication link 125. HARQ can include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ can improve throughput at the medium access control (MAC) layer under poor radio conditions (e.g., low signal to noise conditions). In some examples, a device can support same-slot HARQ feedback, wherein the device can provide HARQ feedback in a particular time slot for data received in previous symbols in that time slot. In other cases, the device can provide HARQ feedback in subsequent time slots or according to some other time interval.

[0127] The UE 115 and the base station 105 of the wireless communication system 100 may support techniques for dynamic scheduling of reverse sidelink traffic, which may reduce control signaling overhead and improve the reliability of sidelink communications in the wireless communication system. For example, the base station 105 of the wireless communication system 100 may send a grant to a first UE 115-a, wherein the first grant indicates a first set of resources allocated for sidelink transmission between the first UE 115-a and the second UE 115-b of the wireless communication system 110. In this example, the first UE 115-a may send one or more SCIs to the second UE 115-b, indicating a second set of resources (e.g., a subset of the first set of resources) allocated for reverse sidelink transmission from the second UE 115-b to the first UE 115-a. In addition, the one or more SCIs may include a reverse sidelink scheduling indicator that indicates the dynamic scheduling of the reverse sidelink traffic to the second UE 115-b. The reverse sidelink scheduling indicator may be indicated in a bit field of the one or more SCIs.

[0128] For example, in some cases, a first SCI (e.g., a first level SCI or SCI 0–1) may indicate a first set of resources that may be used by a second UE 115-b to receive a second SCI, to send a reverse sidelink message from the second UE 115-b to the first UE 115-a, or both. In this example, a second SCI (e.g., a second level SCI or SCI 0–2) may include a reverse sidelink scheduling indicator that indicates dynamic scheduling of reverse sidelink traffic to the second UE 115-b. The reverse sidelink scheduling indicator may be indicated in a bit field of the second SCI. The second SCI may also indicate various parameters associated with the scheduled reverse sidelink transmission. Parameters associated with the reverse sidelink transmission may include an MCS, a redundancy version, a HARQ process identifier, and the like. Subsequently, the second UE 115-b may send a reverse sidelink message to the first UE 115-a based on the reverse sidelink scheduling indicator indicated in the first SCI and one or more parameters indicated in the second SCI.

[0129] The techniques described herein may enable a UE 115 to schedule reverse sidelink transmissions from other UEs 115, thereby reducing control signaling overhead within the wireless communication system 100. Additionally, the techniques described herein may enable a higher complexity UE 115 (e.g., a first UE 115-a) to schedule reverse sidelink transmissions from a lower complexity UE (e.g., a second UE 115-b), thereby reducing potential interference and improving wireless signaling reliability.

[0130] Figure 2 An example of a wireless communication system 200 that supports dynamic scheduling of reverse sidelink traffic according to one or more aspects of the present disclosure is shown. In some examples, the wireless communication system 200 can implement aspects of the wireless communication system 100. The wireless communication system 200 can include a first UE 115-a, a second UE 115-b, and a base station 105-a, which can be as described with reference to FIG. Figure 1 An example of a UE 115 and a base station 105 is depicted. The wireless communication system 200 may support signaling for dynamic scheduling of reverse sidelink traffic.

[0131] In some aspects, Figure 2An example wireless communication system 200 may be shown in the context of a wireless factory automation system. For example, in the context of a wireless factory automation system (e.g., wireless communication system 200), a base station 105-a may be mounted on a ceiling of a factory so that it can communicate with various wireless devices within the factory (e.g., a first UE 115-a and a second UE 115-b). In this example, in some cases, the first UE 115-a may include a wireless programmable logic controller (PLC) and the second UE 115-b may include a wireless sensor / actuator (S / A). Thus, the PLC (e.g., the first UE 115-a) may communicate with the base station 105-a via a Uu link (e.g., communication link 205-a), and the S / A (e.g., the second UE 115-b) may communicate with the PLC (e.g., the first UE 115-a) via a PC5 link (e.g., communication link 205-c). In this example, a first UE 115-a (e.g., a PLC) can be installed near the machinery and can be configured to communicate with a collection of S / As (e.g., a second UE 115-b) and / or other wireless devices. In some cases, a single plant may include 100–1000 PLCs, and each PLC may be communicatively coupled to 20–50 S / As.

[0132] In some cases, various wireless devices within a factory may exhibit different levels of complexity or sophistication. For example, a first UE 115-a (e.g., a PLC) may include a higher-complexity wireless device compared to a second UE 115-b (e.g., an S / A) that may include a lower-complexity wireless device. As used herein, the term "higher-complexity device" may be used to refer to a wireless device that exhibits superior processing capabilities, superior channel knowledge of channels within the wireless communication system 200, or both, compared to a "lower-complexity device."

[0133] The first UE 115-a and the second UE 115-b can communicate with the base station 105-a using communication links 205-a and communication links 205-b, respectively, which can be examples of NR or LTE links between the first UE 115-a and the second UE 115-b and the base station 105-a, respectively. In some cases, the communication link 205-a and the communication link 205-b may include examples of access links (e.g., Uu links). The communication link 205-a and the communication link 205-b may include bidirectional links that implement both uplink communication and downlink communication. For example, the first UE 115-a can use the first communication link 205-a to send an uplink signal (such as an uplink control signal or an uplink data signal) to the base station 105-a, and the base station 105-a can use the communication link 205-a to send a downlink signal (such as a downlink control signal or a downlink data signal) to the first UE 115-a. As another example, the second UE 115-b may use the first communication link 205-b to send an uplink signal (such as an uplink control signal or an uplink data signal) to the base station 105-a, and the base station 105-a may use the communication link 205-b to send a downlink signal (such as a downlink control signal or a downlink data signal) to the second UE 115-b. The first UE 115-a and the second UE 115-b may communicate with each other via the communication link 205-c. In some cases, the communication link 205-c may include an example of a link between the two UEs 115 (e.g., a sidelink communication link or a PC5 link).

[0134] In some aspects, the communication link 205-c (e.g., a sidelink communication link) between the first UE 115-a and the second UE 115-b may be included in a sidelink network of the wireless communication system 200. The sidelink network (e.g., a sidelink network including the communication link 205-c) may be configured to operate in "Mode 1" and / or "Mode 2." When operating in Mode 1, the sidelink network (e.g., the communication link 205-c or the sidelink communication link) may be managed (e.g., coordinated) by the base station 105-a. In this regard, during Mode 1 operation, the base station 105-a may manage resource allocation on the communication link 205-c.

[0135] For example, during mode 1 operation, the base station 105-a may schedule sidelink resources by sending a grant (e.g., a dynamic grant, a configured grant) to each of the first UE 115-a and the second UE 115-b. For example, the first UE 115-a and the second UE 115-b may be preconfigured to perform sidelink transmissions using a configured grant, which may be activated via radio resource control (RRC) signaling from the base station 105-a. As another example, the base station 105-a may schedule sidelink transmissions via downlink control information (DCI), wherein the DCI includes a dynamic grant indicating sidelink resources for the sidelink transmissions. In some cases, the first UE 115-a and the second UE 115-b may report activation or deactivation of the grant (e.g., a configured grant, a dynamic grant) by sending a MAC-CE message to the base station 105-a.

[0136] Operating the sidelink communication link (e.g., communication link 205-c) according to Mode 1 may allow the base station 105-a to coordinate and manage sidelink communications. However, in some cases, operating the sidelink communication link (e.g., communication link 205-c) according to Mode 1 may result in excessive control signaling overhead. For example, in some wireless communication systems, the base station 105-a may send control signaling (e.g., a configured grant, a dynamic grant) to a first UE 115-a to schedule sidelink transmissions from the first UE 115-a, and may send additional control signaling to a second UE 115-b to schedule sidelink transmissions from the second UE 115-b. By separately scheduling sidelink transmissions from each of the first UE 115-a and the second UE 115-b, control signaling to and from the base station 105-a may be increased, which may result in increased latency and less reliable wireless communication.

[0137] In contrast, when the sidelink communication link (e.g., communication link 205-c) is operated according to Mode 2, the sidelink network (e.g., communication link 205-c or the sidelink communication link) may not be managed by (e.g., may not be coordinated by) the base station 105-a. Without coordinating or managing resources of the sidelink network during Mode 2 operation, the UEs 115 of the wireless communication system 200 (e.g., the first UE 115-a, the second UE 115-b, additional UEs 115) may follow a contention-based access process in which the various UEs 115 may "compete" for use of the sidelink network (including communication link 205-c). For example, during Mode 2 operation, the first UE 115-a and the second UE 115-b may monitor the sidelink network of the wireless communication system 200 to determine whether other UEs 115 are attempting to transmit over the sidelink network. For example, the first UE 115-a and the second UE 115-b may monitor the sidelink network for transmissions (e.g., SCI 0-1, request to send message) sent by the other UE 115 and may send messages (e.g., SCI 0-1, request to send message) to compete for (e.g., request) use of the sidelink network (e.g., communication link 205-c).

[0138] However, in the context of Mode 2 sidelink operation, each of the first UE 115-a and the second UE 115-b may monitor the sidelink network to schedule their own sidelink transmissions. In the event that the second UE 115-b includes a lower complexity device (e.g., S / A), the second UE 115-b may not have a sophisticated understanding of the traffic within the sidelink network of the wireless communication system 200. Therefore, the sidelink transmissions from the second UE 115-b scheduled by the second UE 115-b may result in increased interference and less reliable wireless communication.

[0139] Thus, the wireless communication system 200 can support techniques for dynamic scheduling of reverse sidelink traffic that reduce the control signaling overhead associated with Mode 1 operation and reduce the need for lower complexity devices to schedule their own sidelink transmissions (as is the case in Mode 2 operation). In particular, the techniques described herein can support signaling that allows a first UE 115-a to schedule reverse sidelink transmissions from a second UE 115-b to the first UE 115-a. By enabling the first UE 115-a to schedule reverse sidelink transmissions from the second UE 115-b, control signaling from the base station 105-a for sidelink message scheduling can be reduced. Additionally, in instances where the first UE 115-a is a higher complexity device than the second UE 115-b, the first UE 115-a can demonstrate a more sophisticated understanding of the sidelink channel (e.g., communication link 205-c) and sidelink network of the wireless communication system 200, thereby reducing interference and enabling more efficient and reliable sidelink communications.

[0140] For example, in some aspects, the base station 105-a may send a grant (e.g., sidelink resource grant 210) to the first UE 115-a. The sidelink resource grant 210 may indicate a first set of resources (e.g., time resources, frequency resources) to be used for communication via a sidelink communication link (e.g., communication link 205-c) between the first UE 115-a and the second UE 115-b. In some aspects, the first UE 115-a may determine the first set of resources to be used for communication via the sidelink communication link (e.g., communication link 205-c) between the first UE 115-a and the second UE 115-b based on the sidelink resource grant 210.

[0141] In addition, in some aspects, the first UE 115-a may determine a second set of resources to use for a reverse sidelink transmission via a sidelink communication link (e.g., communication link 205-c) from the second UE 115-b to the first UE 115-a. In other words, the first UE 115-a may determine a set of resources to use for a reverse sidelink message 230 from the second UE 115-b to the first UE 115-a. In some aspects, the first UE 115-a may determine the second set of resources based on a sidelink resource grant 210 received from the base station 105-a. In some cases, the second set of resources allocated for the reverse sidelink transmission may include a subset of the first set of resources allocated for the sidelink transmission via the sidelink communication link 205-c between the first UE 115-a and the second UE 115-b. In this regard, the first UE 115-a may determine the second set of resources based on the first set of resources. In additional or alternative aspects, the second set of resources may not be a subset of the first set of resources, and the first UE 115-a may determine the second set of resources independently of the first set of resources.

[0142] In some implementations, the first UE 115-a can determine a resource set for a reverse sidelink message 230 and / or schedule the reverse sidelink message 230 based on the knowledge that the second UE 115-b includes data to be sent to the first UE 115-a. For example, the first UE 115-a can receive a sidelink transmission from the second UE 115-b, wherein one or more packets of the sidelink transmission are discarded or otherwise not successfully received / decoded by the first UE 115-a. The sidelink transmission with the discarded packets can be included in the configuration for a semi-persistent scheduling (SPS) reverse sidelink message (e.g., reverse SPS). In this example, the first UE 115-a can determine that the second UE 115-b includes data to be sent to the first UE 115-a, which can trigger the reverse sidelink scheduling techniques described herein. Therefore, the dynamic reverse sidelink scheduling techniques described herein can enable the second UE 115-b to retransmit at least a portion of the reverse sidelink transmission.

[0143] In some aspects, the first UE 115-a may send a first SCI 215-a to the second UE 115-b. The first UE 115-a may send the first SCI 215-a via a sidelink communication link (e.g., communication link 205-c) between the first UE 115-a and the second UE 115-b based on receiving a sidelink resource grant 210, determining a first set of resources, determining a second set of resources, or any combination thereof. In some aspects, the first SCI 215-a may indicate a second set of resources (e.g., time resources, frequency resources) for a reverse sidelink message 230 from the second UE 115-b to the first UE 115-a. In some aspects, the first SCI 215-a may include a reverse sidelink scheduling indicator. The reverse sidelink scheduling indicator may be configured to indicate to the second UE 115-b the first UE 115-a's dynamic scheduling of reverse sidelink traffic from the second UE 115-b. In some cases, the first SCI 215-a may include a first type of SCI 215 or a second type of SCI 215. For example, the first SCI 215-a may include a first level SCI (eg, SCI 0-1) or a second level SCI (eg, SCI 0-2).

[0144] In some aspects, a reverse sidelink scheduling indicator may be indicated in a bit field of the first SCI 215-a. In this regard, a first value in the bit field of the first SCI 215-a may indicate that the first UE 115-a is scheduling reverse sidelink traffic from the second UE 115-b, and a second value in the bit field of the first SCI 215-a may indicate that the first UE 115-a is not scheduling reverse sidelink traffic from the second UE 115-b. In this regard, the reverse sidelink scheduling indicator may be effectively used to dynamically enable or disable reverse sidelink scheduling by the first UE 115-a. In some aspects, the first SCI 215-a may be sent via a physical sidelink control channel (PSCCH).

[0145] In some cases, the first SCI 215-a may additionally include an indication of one or more parameters associated with the reverse sidelink transmission. Parameters associated with the reverse sidelink message 230 that may be indicated in the first SCI 215-a may include, but are not limited to, priority, time / frequency resources, resource reservation period, demodulation reference signal (DMRS) pattern, number of DMRS ports, SCI format, beta offset indicator, MCS, etc. For example, the first SCI 215-a may include an indication of the MCS associated with the reverse sidelink message 230 from the second UE 115-b.

[0146] The first UE 115-a may additionally send a second SCI 215-b to the second UE 115-b. The first UE 115-a may send the second SCI 215-b via a sidelink communication link (e.g., communication link 205-c) between the first UE 115-a and the second UE 115-b based on receiving the sidelink resource grant 210, determining the first set of resources, determining the second set of resources, sending the first SCI 215-a, or any combination thereof. In some aspects, the second SCI 215-b may indicate a second set of resources (e.g., time resources, frequency resources) for the reverse sidelink message 230 from the second UE 115-b to the first UE 115-a. For example, the second SCI 215-b may include a sidelink grant (e.g., a dynamic sidelink grant) indicating a second set of resources for the reverse sidelink transmission from the second UE 115-b to the first UE 115-a. Additionally or alternatively, the first UE 115-a may send a sidelink grant (e.g., a dynamic sidelink grant) via a different sidelink message or transmission than the second SCI 215-b.

[0147] In some aspects, the second SCI 215-b may include a reverse sidelink scheduling indicator. The reverse sidelink scheduling indicator may be configured to indicate to the second UE 115-b the first UE 115-a's dynamic scheduling of reverse sidelink traffic from the second UE 115-b. In this regard, the reverse sidelink scheduling indicator may be indicated via the first SCI 215-a, the second SCI 215-b, or both.

[0148] In some cases, the second SCI 215-b may include a second type of SCI that is different from the first type of SCI 215. For example, in some cases, the second SCI 215-b may include a second level of SCI (e.g., SCI 0–2). In additional or alternative aspects, the second SCI 215-b may include an indication of one or more parameters associated with the reverse sidelink message 230 from the second UE 115-b. Parameters associated with the reverse sidelink message 230 that may be indicated in the second SCI 215-b may include, but are not limited to, an MCS, a redundancy version, a HARQ process identifier, a new data indicator, identifiers associated with the first UE 115-a and the second UE 115-b (e.g., a source identifier, a destination identifier), a channel state information (CSI) request, an area identifier, a communication range requirement, and the like.

[0149] As another example, the second SCI 215-b may include a first identifier associated with the first UE 115-a and a second identifier associated with the second UE 115-b. In some cases, the source identifier may refer to the UE 115 (e.g., the first UE 115-a) that will receive the reverse sidelink message 230, and the destination identifier may refer to the UE 115 (e.g., the second UE 115-b) to which the reverse sidelink message 230 is to be sent. In other cases, the source identifier may refer to the UE 115 (e.g., the second UE 115-b) to which the reverse sidelink message 230 is to be sent, and the destination identifier may refer to the UE 115 (e.g., the first UE 115-a) to which the reverse sidelink message 230 is to be received. Additionally or alternatively, the second SCI 215-b may include an indication of a request to send a new reverse sidelink message 230 to the second UE 115-b, a request to retransmit a previously sent reverse sidelink message 230, or both. In some aspects, the second SCI 215-b may be transmitted via the PSSCH.In some aspects, the second UE 115-b may receive and / or decode the second SCI 215-b based on receiving the first SCI 215-a (e.g., based on data included within the first SCI 215-a).

[0150] In some aspects, the first UE 115-a may send a sidelink message 220 to the second UE 115-b. The first UE 115-a may send the sidelink message 220 via a sidelink communication link (e.g., communication link 205-c) between the first UE 115-a and the second UE 115-b. In some aspects, the first UE 115-a may send the sidelink message 220 in addition to the first SCI 215-a and / or the second SCI 215-b. In some aspects, the sidelink message 220 may be sent via the PSSCH.

[0151] In some aspects, the first UE 115-a may monitor a second set of resources associated with a reverse sidelink transmission from the second UE 115-b to the first UE 115-a. In some aspects, the first UE 115-c may monitor the second set of resources based on determining the second set of resources, transmitting the first SCI 215-a, transmitting the second SCI 215-b, or any combination thereof. For example, the first UE 115-a may monitor a set of time resources and a set of frequency resources associated with the second set of resources to monitor for a reverse sidelink message 230 from the second UE 115-b.

[0152] The first UE 115-a may receive the third SCI 215-c, the fourth SCI 215-d, or both from the second UE 115-b. In some cases, the first UE 115-a may receive the third SCI 215-c and / or the fourth SCI 215-d based on (e.g., in response to) sending the first SCI 215-a, sending the second SCI 215-b, monitoring the second resource set, or any combination thereof. In some aspects, the third SCI 215-c may include a first type of SCI and the fourth SCI 215-d may include a second type of SCI. For example, the third SCI 215-c may include a first level SCI (e.g., SCI 0-1) and the fourth SCI 215-d may include a second level SCI (e.g., SCI 0-2). In some aspects, the third SCI 215-c may be sent via the PSCCH and the fourth SCI 215-d may be sent via the PSSCH. In some aspects, the third SCI 215-c and / or the fourth SCI 215-d may include an indication of one or more parameters (e.g., time resources, frequency resources, MCS, redundancy version, HARQ process identifier) ​​associated with the reverse sidelink message 230 sent from the second UE 115-b to the first UE 115-a, as will be discussed in further detail herein.

[0153] In some aspects, the first UE 115-a may receive a reverse sidelink message 230 from the second UE 115-b. The first UE 115-b may receive the reverse sidelink message 230 from the second UE 115-b via a sidelink communication link (e.g., communication link 205-c) between the first UE 115-a and the second UE 115-b based on (e.g., in response to) sending the first SCI 215-a, sending the second SCI 215-b, monitoring the second set of resources, receiving the third SCI 215-c, receiving the fourth SCI 215-d, or any combination thereof.

[0154] For example, if the first SCI 215-a and / or the second SCI 215-b include an indication of an MCS associated with the reverse sidelink transmission, the second UE 115-b may, based on the indicated MCS, send the reverse sidelink message 230. As another example, if the second SCI 215-b indicates a redundancy version or a request to send the reverse sidelink message 230, the second UE 115-b may, based on the indicated redundancy version, the indicated request, or both, send the reverse sidelink message 230. As another example, if the second SCI 215-b includes an indication of a first identifier associated with the first UE 115-a and a second identifier associated with the second UE 115-b, the second UE 115-b may, based on the first identifier, the second identifier, or both, send the reverse sidelink message 230. Additionally or alternatively, the second UE 115-b may send a sidelink message based on (e.g., in response to) a sidelink grant (e.g., a dynamic sidelink grant) indicated in the second SCI 215-b and / or alternative sidelink signaling.

[0155] As previously mentioned herein, the third SCI 215-c and / or the fourth SCI 215-d may indicate one or more parameters associated with the reverse sidelink message 230. In some cases, the second UE 115-b may use parameters associated with the reverse sidelink traffic indicated by the first SCI 215-a and / or the second SCI 215-b to send the reverse sidelink message 230. In this regard, the third SCI 215-c and / or the fourth SCI 215-d may indicate (e.g., mirror) the same parameters (e.g., time resources, frequency resources, MCS, redundancy version, HARQ process identifier) ​​indicated in the first SCI 215-a and / or the second SCI 215-b. In some cases, when all fields / parameters associated with the reverse sidelink message 230 can be inferred (e.g., determined) by dynamic scheduling of the reverse sidelink message 230 via the first SCI 215-a and / or the second SCI 215-b, the second UE 115-b can refrain from transmitting the third SCI 215-c and / or the fourth SCI 215-d. However, it is noted herein that other UEs 115 within the wireless communication system 200 can monitor the sidelink network for the first level SCI (e.g., the third SCI) to determine the availability of the sidelink network when the sidelink network operates in Mode 2. Therefore, in some cases, when the parameters of the reverse sidelink message 230 can be inferred, the second UE 115-b can refrain from transmitting the fourth SCI 215-d, but can transmit the third SCI 215-c to allow the other UEs 115 to perform sidelink channel sensing and selection.

[0156] Alternatively, in some cases, the second UE 115-b may select its own parameters (e.g., time resources, frequency resources, MCS, redundancy version, HARQ process identifier) ​​for sending the reverse sidelink message 230 that are different from those indicated in the first SCI 215-a and / or the second SCI 215-b. In this regard, the parameters indicated in the first SCI 215-a and / or the second SCI 215-b may be considered "recommended" parameters for use by the second UE 115-b. In the event that the second UE 115-b selects parameters that are different from the recommended parameters indicated in the first SCI 215-a and / or the second SCI 215-b, the selected parameters may be indicated in the third SCI 215-c and / or the fourth SCI 215-d.

[0157] In some cases, the first UE 115-a may send a feedback message 235 to the second UE 115-b. The first UE 115-c may send the feedback message 235 based on (e.g., in response to) sending the first SCI 215-a, sending the second SCI 215-b, receiving the third SCI 215-c, receiving the fourth SCI 215-d, receiving the reverse sidelink message 230, or any combination thereof. In some cases, the first UE 115-c may send the feedback message 235 based on a HARQ process identifier indicated in the second SCI 215-b or the fourth SCI 215-d. For example, the first UE 115-a may send an acknowledgement (ACK) message or a negative acknowledgement (NACK) message to the second UE 115-b based on (e.g., in response to) the HARQ process identifier indicated in the second SCI 215-b, receiving the reverse sidelink message 230, or both.

[0158] The techniques described herein may enable a first UE 115-a to schedule reverse sidelink transmissions from a second UE 115-b, thereby reducing control signaling overhead within the wireless communication system 200. Additionally, the techniques described herein may enable a higher complexity UE 115 (e.g., the first UE 115-a) to schedule reverse sidelink transmissions from a lower complexity UE 115 (e.g., the second UE 115-b), thereby reducing potential interference and improving wireless signaling reliability.

[0159] Figure 3An example of a process flow 300 for supporting dynamic scheduling of reverse sidelink traffic according to one or more aspects of the present disclosure is shown. In some examples, the process flow 300 can implement aspects of the wireless communication system 100 or 200. For example, the process flow 300 can illustrate transmitting a first SCI and a second SCI, monitoring a set of resources associated with a reverse sidelink transmission, and receiving a reverse sidelink transmission, as described with reference to FIG. Figure 1-2 Descriptive.

[0160] In some cases, the process flow 300 may include a first UE 115-c, a second UE 115-d, and a base station 105-b, which may be examples of corresponding devices described herein. Figure 3 The first UE 115-c and the second UE 115-d shown in FIG. 1 may be Figure 2 1 and 115 - b. Figure 3 The base station 105-b shown in FIG may be Figure 2 In some aspects, the first UE 115-c and the second UE 115-d can communicate with each other via a sidelink communication link (such as Figure 2 Communicate via the communication link 205-c) shown in FIG.

[0161] In some examples, the operations shown in process flow 300 can be performed by hardware (e.g., including circuits, processing blocks, logic components, and other components), code executed by a processor (e.g., software or firmware), or any combination thereof. The following alternative examples can be implemented in which some steps are performed in a different order than described or not performed at all. In some cases, the steps may include additional features not mentioned below, or additional steps may be added.

[0162] At 305, the base station 105-b may send a sidelink resource grant to the first UE 115-c. The sidelink resource grant may indicate a first set of resources (e.g., time resources, frequency resources) to be used for communication via a sidelink communication link between the first UE 115-c and the second UE 115-d.

[0163] At 310, the first UE 115-c may determine a first set of resources for communication via a sidelink communication link between the first UE 115-c and the second UE 115-d. In some aspects, the first UE 115-c may determine the first set of resources based on the sidelink resource grant received at 305 from the base station 105-b.

[0164] At 315, the first UE 115-c may determine a second set of resources for reverse sidelink transmissions via the sidelink communication link from the second UE 115-d to the first UE 115-c. In some aspects, the first UE 115-c may determine the second set of resources based on the sidelink resource grant received from the base station 105-a at 305. In some cases, the second set of resources allocated for reverse sidelink transmissions may include a subset of the first set of resources allocated for sidelink transmissions via the sidelink communication link 205-c between the first UE 115-c and the second UE 115-d. In this regard, the first UE 115-c may determine the second set of resources based on the first set of resources. In additional or alternative aspects, the second set of resources may not be a subset of the first set of resources, and the first UE 115-c may determine the second set of resources independently of the first set of resources.

[0165] At 320, the first UE 115-c may send a first SCI to the second UE 115-d. The first UE 115-c may send the first SCI via the sidelink communication link between the first UE 115-c and the second UE 115-d based on receiving a sidelink resource grant, determining a first set of resources, determining a second set of resources, or any combination thereof. In some aspects, the first SCI may indicate a set of resources that may be used by the second UE 115-b to receive a second SCI, send a reverse sidelink message, or both. In some aspects, the first SCI may include a reverse sidelink scheduling indicator. The reverse sidelink scheduling indicator may be configured to indicate to the second UE 115-d the dynamic scheduling of reverse sidelink traffic from the second UE 115-d by the first UE 115-c. In some cases, the first SCI may include a first type of SCI. For example, the first SCI may include a first level SCI (e.g., SCI 0–1) or a second level SCI (e.g., SCI 0-2). In additional or alternative aspects, the first SCI may include an indication of an MCS associated with the reverse sidelink message from the second UE 115-d.

[0166] In some aspects, a reverse sidelink scheduling indicator may be indicated in a bit field of the first SCI. In this regard, a first value in the bit field of the first SCI may indicate that the first UE 115-c is scheduling reverse sidelink traffic from the second UE 115-d, and a second value in the bit field of the first SCI may indicate that the first UE 115-c is not scheduling reverse sidelink traffic from the second UE 115-d. In this regard, the reverse sidelink scheduling indicator may be effectively used to dynamically enable or disable reverse sidelink scheduling by the first UE 115-c. In some aspects, the first SCI may be transmitted via the PSCCH.

[0167] At 325, the first UE 115-c may send a second SCI to the second UE 115-d. The first UE 115-c may send the second SCI via the sidelink communication link between the first UE 115-c and the second UE 115-d based on receiving the sidelink resource grant at 305, determining the first set of resources at 310, determining the second set of resources at 315, sending the first SCI at 320, or any combination thereof.

[0168] In some aspects, the second SCI may include a reverse sidelink scheduling indicator. The reverse sidelink scheduling indicator may be configured to indicate to the second UE 115-d that the first UE 115-a is dynamically scheduling reverse sidelink traffic from the second UE 115-d. In this regard, the reverse sidelink scheduling indicator may be indicated via the first SCI, the second SCI, or both. In some cases, the second SCI may include a second-level SCI (e.g., SCI 0-2). In some aspects, the reverse sidelink scheduling indicator may be indicated in a bit field of the second SCI. In this regard, the first value in the bit field of the second SCI may indicate that the first UE 115-c is scheduling reverse sidelink traffic from the second UE 115-d, and the second value of the bit field of the second SCI may indicate that the first UE 115-c is not scheduling reverse sidelink traffic from the second UE 115-d. In this regard, the reverse sidelink scheduling indicator may be effectively used to dynamically enable or disable reverse sidelink scheduling of the first UE 115-c.

[0169] In some aspects, the second SCI may indicate a second set of resources (e.g., time resources, frequency resources) to be used for the reverse sidelink transmission from the second UE 115-d to the first UE 115-c. For example, the second SCI may include a sidelink grant (e.g., a dynamic sidelink grant) indicating the second set of resources to be used for the reverse sidelink transmission from the second UE 115-d to the first UE 115-c. Additionally or alternatively, the first UE 115-c may send the sidelink grant (e.g., a dynamic sidelink grant) via a sidelink message or transmission that is different from the second SCI.

[0170] In some cases, the second SCI may include a second type of SCI that is different from the first type of SCI. For example, the second SCI may include a second level SCI (e.g., SCI 0–2). In additional or alternative aspects, the second SCI may include an indication of one or more parameters associated with the reverse sidelink message from the second UE 115-d. Parameters associated with the reverse sidelink message that may be indicated in the second SCI may include, but are not limited to, an MCS, a redundancy version, a HARQ process identifier, an identifier associated with the first UE 115-c and the second UE 115-d (e.g., a source identifier, a destination identifier), etc. Additionally or alternatively, the second SCI may include an indication of a request to send a new reverse sidelink message for the second UE 115-d, a request to retransmit a previously sent reverse sidelink message, or both. In some aspects, the second SCI may be sent via the PSSCH.

[0171] At 330, the first UE 115-c may send a sidelink message to the second UE 115-d. The first UE 115-c may send the sidelink message via a sidelink communication link between the first UE 115-c and the second UE 115-d. In some aspects, in addition to sending the first SCI at 320 and / or the second SCI sent at 325, the first UE 115-c may also send the sidelink message at 325. Additionally or alternatively, the second UE 115-d may send the sidelink message based on (e.g., in response to) a sidelink grant (e.g., a dynamic sidelink grant) indicated in the second SCI and / or alternative sidelink signaling. In some aspects, the sidelink message may be sent via the PSSCH.

[0172] At 335, the first UE 115-c may monitor a second set of resources associated with a reverse sidelink transmission from the second UE 115-d to the first UE 115-c. In some aspects, the first UE 115-c may monitor the second set of resources based on determining the second set of resources at 315, sending the first SCI at 320, sending the second SCI at 325, or any combination thereof.

[0173] At 340, the first UE 115-c may receive a third SCI from the second UE 115-d. In some cases, the first UE 115-c may receive the third SCI based on (e.g., in response to) sending the first SCI, sending the second SCI, monitoring the second set of resources, or any combination thereof. In some aspects, the third SCI may include a first type of SCI. For example, the third SCI may include a first level SCI (e.g., SCI 0-1). In some aspects, the third SCI may be sent via a PSCCH.

[0174] At 345, the first UE 115-c may receive a fourth SCI from the second UE 115-d. In some cases, the first UE 115-c may receive the fourth SCI based on (e.g., in response to) sending the first SCI, sending the second SCI, monitoring the second set of resources, or any combination thereof. In some aspects, the fourth SCI may include a second type of SCI. For example, the fourth SCI may include a second level SCI (e.g., SCI 0-2). In some aspects, the fourth SCI may be sent via the PSSCH.

[0175] At 350, the first UE 115-c may receive a reverse sidelink message from the second UE 115-d. The first UE 115-c may receive the reverse sidelink message from the second UE 115-d via the sidelink communication link between the first UE 115-c and the second UE 115-d based on (e.g., in response to) sending the first SCI, sending the second SCI, monitoring the second set of resources, receiving the third SCI, receiving the fourth SCI, or any combination thereof. For example, where the first SCI and / or the second SCI include an indication of a reverse sidelink scheduling indicator, the second UE 115-d may send the reverse sidelink message at 350 based on the indicated reverse sidelink scheduling indicator. As another example, where the first SCI and / or the second SCI include an indication of an MCS associated with the reverse sidelink transmission, the second UE 115-d may send the reverse sidelink message at 350 based on the indicated MCS. As another example, where the second SCI indicates a redundancy version or a request to send a reverse sidelink message, the second UE 115-d may send the reverse sidelink message at 350 based on the indicated redundancy version, the indicated request, or both. As another example, where the second SCI includes an indication of a first identifier associated with the first UE 115-c and a second identifier associated with the second UE 115-d, the second UE 115-d may send the reverse sidelink message at 350 based on the first identifier, the second identifier, or both.

[0176] In some aspects, the third SCI and / or the fourth SCI may indicate one or more parameters associated with the reverse sidelink message sent at 350. In some cases, the second UE 115-d may send a reverse sidelink message based on parameters associated with the reverse sidelink traffic indicated by the first SCI and / or the second SCI. In this regard, the third SCI and / or the fourth SCI may indicate (e.g., mirror) the same parameters (e.g., time resources, frequency resources, MCS, redundancy version, HARQ process identifier) ​​indicated in the first SCI and / or the second SCI. In some cases, when all fields / parameters associated with the reverse sidelink message can be inferred by dynamically scheduling the reverse sidelink message via the first SCI and / or the second SCI, the second UE 115-d may avoid sending the third SCI and / or the fourth SCI. However, it is noted herein that other UEs within the wireless communication system may monitor the sidelink network for the first level SCI (e.g., the third SCI) to determine the availability of the sidelink network when the sidelink network is operating in Mode 2. Thus, in some cases, when parameters of the reverse sidelink message can be inferred, the second UE 115-d may avoid sending the fourth SCI, but may send the third SCI to allow other UEs to perform sidelink channel sensing and selection.

[0177] Alternatively, in some cases, the second UE 115-d may select its own parameters (e.g., time resources, frequency resources, MCS, redundancy version, HARQ process identifier) ​​for sending the reverse sidelink message that are different from those indicated in the first SCI and / or the second SCI. In this regard, the parameters indicated in the first SCI and / or the second SCI may be considered "recommended" parameters for use by the second UE 115-d. In the event that the second UE 115-d selects parameters that are different from the recommended parameters indicated in the first SCI and / or the second SCI, the selected parameters may be indicated in the third SCI and / or the fourth SCI.

[0178] At 355, the first UE 115-c may send a feedback message (e.g., an ACK / NACK) to the second UE 115-d. The first UE 115-c may send the feedback message based on (e.g., in response to) sending the first SCI, sending the second SCI, receiving the third SCI, receiving the fourth SCI, receiving the reverse sidelink message, or any combination thereof. In some cases, the first UE 115-c may send the feedback message based on the HARQ process identifier indicated in the second SCI sent at 325 or the fourth SCI received at 345.

[0179] The techniques described herein may enable a first UE 115-c to schedule reverse sidelink transmissions from a second UE 115-d, thereby reducing control signaling overhead within a wireless communication system, such as the wireless communication system 100 or 200. Additionally, the techniques described herein may enable a higher complexity UE 115 (e.g., the first UE 115-c) to schedule reverse sidelink transmissions from a lower complexity UE (e.g., the second UE 115-d), thereby reducing potential interference and improving wireless signaling reliability.

[0180] Figure 4 A block diagram 400 of a device 405 supporting techniques for dynamic scheduling of reverse sidelink traffic according to one or more aspects of the present disclosure is shown. The device 405 can be an example of aspects of the UE 115 as described herein. The device 405 can include a receiver 410, a communication manager 415, and a transmitter 420. The device 405 can also include a processor. Each of these components can communicate with each other (e.g., via one or more buses).

[0181] The receiver 410 may 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 dynamic scheduling of reverse sidelink traffic, etc.). The information may be communicated to other components of the device 405. The receiver 410 may be a reference Figure 7 Examples of aspects of the transceiver 720 are described. The receiver 410 may utilize a single antenna or a group of antennas.

[0182] The communication manager 415 may perform the following operations: determine a first set of resources for communication via a sidelink communication link between a first UE and a second UE; send a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on determining the first set of resources; send a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI; and receive a reverse sidelink message from the second UE in response to sending the second SCI. The communication manager 415 may also perform the following operations: receive the first SCI including a reverse sidelink scheduling indicator from the second UE via the sidelink communication link between the first UE and the second UE; receive a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is based on receiving the first SCI; and send a reverse sidelink message to the second UE in response to receiving the second SCI. Communications manager 415 may be an example of aspects of communications manager 710 described herein.

[0183] The actions performed by the communication manager 415 as described herein can be implemented to achieve one or more potential advantages. For example, enabling a first UE 115 (e.g., a higher complexity UE 115) to coordinate and schedule reverse sidelink transmissions from a second UE 115 (e.g., a lower complexity UE 115) to the first UE 115 can provide more efficient and reliable sidelink communications. In addition, by enabling dynamic reverse sidelink scheduling, control signaling overhead within a wireless communication system (e.g., wireless communication system 100 or 200) can be reduced.

[0184] By dynamically scheduling the reverse sidelink traffic from the second UE 115 to the first UE 115, the processor of the second UE 115 (e.g., the processor that controls the receiver 410, the communication manager 415, the transmitter 420, etc.) can reduce the processing resources used for the sidelink communication. In addition, the processor of the higher complexity UE 115 (e.g., the processor that controls the receiver 410, the communication manager 415, the transmitter 420, etc.) can be more complex and better equipped to handle the processing requirements for scheduling the sidelink communication. By transferring some processing resources from the lower complexity UE 115 to the higher complexity UE 115, interference and noise within the wireless communication system can be reduced, thereby correspondingly reducing the number of times the processor increases processing power and turns on processing units to retransmit sidelink traffic.

[0185] The communication manager 415 may be an example of a unit for performing various aspects of managing an intelligent repeater as described herein. The communication manager 415 or its subcomponents may be implemented in hardware (e.g., in a communication management circuit). The circuit may include a processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this disclosure.

[0186] In another implementation, the communication manager 415 or its subcomponents may be implemented in code executed by a processor (e.g., as communication management software or firmware), or any combination thereof. If implemented in code executed by a processor, the functionality of the communication manager 415 or its subcomponents may be performed by a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device designed to perform the functions described in this disclosure.

[0187] In some examples, communications manager 415 is configured to perform various operations (eg, receive, determine, send, etc.) using or otherwise cooperating with receiver 410, transmitter 420, or both.

[0188] The communication manager 415 or its subcomponents can be physically located at various locations, including being distributed so that portions of the functionality are implemented by one or more physical components at different physical locations. In some examples, according to various aspects of the present disclosure, the communication manager 415 or its subcomponents can be separate and distinct components. In some examples, according to various aspects of the present disclosure, the communication manager 415 or its subcomponents can be combined with one or more other hardware components (including but not limited to input / output (I / O) components, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof).

[0189] The transmitter 420 may transmit signals generated by other components of the device 405. In some examples, the transmitter 420 may be co-located with the receiver 410 in a transceiver module. For example, the transmitter 420 may be a reference Figure 7 Examples of aspects of the transceiver 720 are described. The transmitter 420 may utilize a single antenna or a group of antennas.

[0190] Figure 5A block diagram 500 of a device 505 supporting techniques for dynamic scheduling of reverse sidelink traffic according to one or more aspects of the present disclosure is shown. The device 505 can be an example of aspects of the device 405 or UE 115 as described herein. The device 505 can include a receiver 510, a communication manager 515, and a transmitter 545. The device 505 can also include a processor. Each of these components can communicate with each other (e.g., via one or more buses).

[0191] The receiver 510 may 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 dynamic scheduling of reverse sidelink traffic, etc.). The information may be communicated to other components of the device 505. The receiver 510 may be a reference Figure 7 Examples of aspects of the transceiver 720 are described. The receiver 510 may utilize a single antenna or a group of antennas.

[0192] The communication manager 515 may be an example of aspects of the communication manager 415 as described herein. The communication manager 515 may include a sidelink resource manager 520, an SCI transmit manager 525, a reverse sidelink receive manager 530, an SCI receive manager 535, and a reverse sidelink transmit manager 540. The communication manager 515 may be an example of aspects of the communication manager 710 as described herein.

[0193] The sidelink resource manager 520 may determine a first set of resources to use for communication over the sidelink communication link between the first UE and the second UE.

[0194] The SCI sending manager 525 can send a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on determining the first resource set, and send a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second resource set used for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI.

[0195] The reverse sidelink reception manager 530 may receive a reverse sidelink message from the second UE in response to sending the second SCI.

[0196] The SCI reception manager 535 can receive a first SCI including a reverse sidelink scheduling indicator from the second UE via a sidelink communication link between the first UE and the second UE, and receive a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources used for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is based on receiving the first SCI.

[0197] The reverse sidelink transmission manager 540 may transmit a reverse sidelink message to the second UE in response to receiving the second SCI.

[0198] The transmitter 545 can transmit signals generated by other components of the device 505. In some examples, the transmitter 545 can be co-located with the receiver 510 in a transceiver module. For example, the transmitter 545 can be a reference Figure 7 Examples of various aspects of the transceiver 720 are described. The transmitter 545 may utilize a single antenna or a group of antennas.

[0199] Figure 6 A block diagram 800 of a communication manager 605 supporting techniques for dynamic scheduling of reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown. The communication manager 605 can be an example of aspects of the communication manager 415, the communication manager 515, or the communication manager 710 described herein. The communication manager 605 can include a sidelink resource manager 610, an SCI transmit manager 615, a reverse sidelink receive manager 620, a feedback message transmit manager 625, an SCI receive manager 630, a sidelink monitor manager 635, a reverse sidelink transmit manager 640, and a feedback message receive manager 645. Each of these modules can communicate with each other directly or indirectly (e.g., via one or more buses).

[0200] The sidelink resource manager 610 may determine a first set of resources for communication via a sidelink communication link between a first UE and a second UE. In some cases, the second set of resources includes a set of time resources and a set of frequency resources allocated for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link. In some cases, the resource set includes a set of time resources and a set of frequency resources allocated for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link.

[0201] The SCI transmission manager 615 may transmit a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on determining the first set of resources. In some examples, the SCI transmission manager 615 may transmit a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein transmitting the second SCI is based on transmitting the first SCI.

[0202] In some examples, the SCI transmission manager 615 may transmit an indication of an MCS associated with the reverse sidelink message via at least one of the first SCI or the second SCI, wherein receiving the reverse sidelink message is based on transmitting the indication of the MCS. In some examples, the SCI transmission manager 615 may transmit an indication of a redundancy version associated with the reverse sidelink message via the second SCI, wherein receiving the reverse sidelink message is based on transmitting the indication of the redundancy version. In some examples, the SCI transmission manager 615 may transmit an indication of a request to transmit a new reverse sidelink message, a retransmission of a previous reverse sidelink message, or both for the second UE via the second SCI, wherein receiving the reverse sidelink message is responsive to transmitting the indication of the request. In some examples, the SCI transmission manager 615 may transmit a HARQ process identifier associated with the reverse sidelink transmission from the second UE to the first UE via the second SCI. In some examples, the SCI transmission manager 615 may transmit an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via a second SCI, wherein receiving the reverse sidelink message is based on the indication of the first identifier and the indication of the second identifier.

[0203] In some examples, the SCI transmission manager 615 may transmit a first SCI via the PSCCH. In some examples, the SCI transmission manager 615 may transmit a second SCI via the PSSCH. In some examples, the SCI transmission manager 615 may transmit a third SCI, a fourth SCI, or both to the second UE, wherein transmitting the reverse sidelink message is based on transmitting the third SCI, the fourth SCI, or both.

[0204] In some cases, the first SCI comprises a first type of SCI, and wherein the second SCI comprises a second type of SCI different from the first type of SCI. In some cases, the first SCI comprises a first level SCI, and wherein the second SCI comprises a second level SCI. In some cases, the reverse sidelink scheduling indicator is indicated in a bit field of the first SCI.

[0205] The reverse sidelink reception manager 620 may receive a reverse sidelink message from the second UE in response to sending the second SCI.

[0206] The SCI reception manager 630 may receive a first SCI including a reverse sidelink scheduling indicator from the second UE via a sidelink communication link between the first UE and the second UE. In some examples, the SCI reception manager 630 may receive a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources used for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is based on receiving the first SCI. In some examples, the SCI reception manager 630 may receive a third SCI, a fourth SCI, or both from the second UE, wherein receiving the reverse sidelink message is based on receiving the third SCI, the fourth SCI, or both.

[0207] In some examples, the SCI reception manager 630 may receive an indication of an MCS associated with a reverse sidelink message via at least one of a first SCI or a second SCI, wherein sending the reverse sidelink message is based on receiving the indication of the MCS. In some examples, the SCI reception manager 630 may receive an indication of a redundancy version associated with the reverse sidelink message via a second SCI, wherein sending the reverse sidelink message is based on receiving the indication of the redundancy version. In some examples, the SCI reception manager 630 may receive an indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both for a second UE via a second SCI, wherein sending the reverse sidelink message is responsive to receiving the indication of the request. In some examples, the SCI reception manager 630 may receive a HARQ process identifier associated with a reverse sidelink transmission from a first UE to a second UE via a second SCI. In some examples, the SCI reception manager 630 may receive an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via a second SCI, wherein sending the reverse sidelink message is based on the indication of the first identifier and the indication of the second identifier.

[0208] In some examples, the SCI reception manager 630 may receive a first SCI via a PSCCH. In some examples, the SCI reception manager 630 may receive a second SCI via a PSSCH. In some cases, the first SCI includes a first type of SCI, and wherein the second SCI includes a second type of SCI that is different from the first type of SCI. In some cases, the first SCI includes a first-level SCI, and wherein the second SCI includes a second-level SCI. In some cases, the reverse sidelink scheduling indicator is indicated in a bit field of the first SCI.

[0209] The reverse sidelink transmission manager 640 may transmit a reverse sidelink message to the second UE in response to receiving the second SCI.

[0210] The feedback message transmission manager 625 may transmit a feedback message to the second UE in response to receiving the reverse sidelink message and the HARQ process identifier. The feedback message reception manager 645 may receive a feedback message from the second UE in response to transmitting the reverse sidelink message and the HARQ process identifier.

[0211] The sidelink monitoring manager 635 may monitor a second set of resources associated with a reverse sidelink transmission from the second UE to the first UE based on sending a second SCI, wherein receiving the reverse sidelink message is based on monitoring the second set of resources.

[0212] Figure 7 A diagram of a system 700 including a device 705 that supports techniques for dynamic scheduling of reverse sidelink traffic in accordance with one or more aspects of the present disclosure is shown. The device 705 may be an example of, or include a component of, the device 405, device 505, or UE 115 as described herein. The device 705 may include components for two-way voice and data communications, including components for sending and receiving communications, including a communications manager 710, an I / O controller 715, a transceiver 720, an antenna 725, a memory 730, and a processor 740. These components may communicate electronically via one or more buses (e.g., bus 745).

[0213] The communication manager 710 may perform the following operations: determining a first set of resources for communication via a sidelink communication link between a first UE and a second UE; sending a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based on determining the first set of resources; sending a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI; and receiving a reverse sidelink message from the second UE in response to sending the second SCI. The communication manager 710 may also perform the following operations: receiving the first SCI including a reverse sidelink scheduling indicator from the second UE via the sidelink communication link between the first UE and the second UE; receiving a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is based on receiving the first SCI; and sending a reverse sidelink message to the second UE in response to receiving the second SCI.

[0214] I / O controller 715 can manage input and output signals for device 705. I / O controller 715 can also manage peripheral devices that are not integrated into device 705. In some cases, I / O controller 715 can represent a physical connection or port to an external peripheral device. In some cases, I / O controller 715 can utilize a computer such as , or another known operating system. In other cases, I / O controller 715 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I / O controller 715 may be implemented as part of a processor. In some cases, a user may interact with device 705 via I / O controller 715 or via hardware components controlled by I / O controller 715.

[0215] The transceiver 720 can communicate bidirectionally via one or more antennas, wired or wireless links as described above. For example, the transceiver 720 can represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 720 can also include a modem for modulating packets and providing the modulated packets to the antenna for transmission, and demodulating packets received from the antenna.

[0216] In some cases, a wireless device may include a single antenna 725. However, in some cases, the device may have more than one antenna 725 that are capable of sending or receiving multiple wireless transmissions simultaneously.

[0217] The memory 730 may include random access memory (RAM) and read-only memory (ROM). The memory 730 may store computer-readable, computer-executable code 735, which includes instructions that, when executed, cause the processor to perform the various functions described herein. In some cases, the memory 730 may also contain, among other things, a basic I / O system (BIOS), which may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0218] The processor 740 may 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, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, the processor 740 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 740. The processor 740 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 730) to cause the device 705 to perform various functions (e.g., functions or tasks that support techniques for dynamic scheduling of reverse sidelink traffic).

[0219] The code 735 may include instructions for implementing various aspects of the present disclosure, including instructions for supporting wireless communications. The code 735 may be stored in a non-transitory computer-readable medium (e.g., system memory or other types of memory). In some cases, the code 735 may not be directly executable by the processor 740, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0220] Figure 8 A flow chart illustrating a method 800 for supporting dynamic scheduling of reverse sidelink traffic according to one or more aspects of the present disclosure is shown. The operations of the method 800 may be implemented by a UE 115 or a component thereof as described herein. For example, the operations of the method 800 may be implemented by a UE 115 or a component thereof as described herein. Figures 4 to 7 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0221] At 805, the UE may determine a first set of resources for communication via a sidelink communication link between the first UE and the second UE. The operations of 805 may be performed according to the methods described herein. In some examples, aspects of the operations of 805 may be as described with reference to Figures 4 to 7The sidelink resource manager described is used to perform the above operations.

[0222] At 810, the UE may send a first SCI including a reverse sidelink scheduling indicator to a second UE via a sidelink communication link based on determining the first set of resources. The operations of 810 may be performed according to the methods described herein. In some examples, aspects of the operations of 810 may be as described with reference to Figures 4 to 7 Described SCI Send Manager to perform.

[0223] At 815, the UE may send a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI. The operations of 815 may be performed according to the methods described herein. In some examples, aspects of the operations of 815 may be performed as described with reference to Figures 4 to 7 Described SCI Send Manager to perform.

[0224] At 820, the UE may receive a reverse sidelink message from the second UE in response to sending the second SCI. The operations of 820 may be performed according to the methods described herein. In some examples, aspects of the operations of 820 may be as described with reference to Figures 4 to 7 Described reverse sidelink receive manager to perform.

[0225] Figure 9 A flow chart illustrating a method 900 for supporting dynamic scheduling of reverse sidelink traffic according to one or more aspects of the present disclosure is shown. The operations of the method 900 may be implemented by a UE 115 or components thereof as described herein. For example, the operations of the method 900 may be implemented by a UE 115 or components thereof as described herein. Figures 4 to 7 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0226] At 905, the UE may determine a first set of resources for communication via a sidelink communication link between the first UE and the second UE. The operations of 905 may be performed according to the methods described herein. In some examples, aspects of the operations of 905 may be as described with reference to Figures 4 to 7 The sidelink resource manager described is used to perform the above operations.

[0227] At 910, the UE may send a first SCI including a reverse sidelink scheduling indicator to a second UE via a sidelink communication link based on determining the first set of resources. The operations of 910 may be performed according to the methods described herein. In some examples, aspects of the operations of 910 may be as described with reference to Figures 4 to 7 Described SCI Send Manager to perform.

[0228] At 915, the UE may send a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI. The operations of 915 may be performed according to the methods described herein. In some examples, aspects of the operations of 915 may be performed as described with reference to Figures 4 to 7 Described SCI Send Manager to perform.

[0229] At 920, the UE may send an indication of an MCS associated with the reverse sidelink message via at least one of the first SCI or the second SCI. The operations of 920 may be performed according to the methods described herein. In some examples, aspects of the operations of 920 may be as described with reference to Figures 4 to 7 Described SCI Send Manager to perform.

[0230] At 925, the UE may receive a reverse sidelink message from the second UE in response to sending the second SCI, wherein receiving the reverse sidelink message is based on sending the indication of the MCS. The operations of 925 may be performed according to the methods described herein. In some examples, aspects of the operations of 925 may be as described with reference to Figures 4 to 7 Described reverse sidelink receive manager to perform.

[0231] Figure 10 A flow chart illustrating a method 1000 for supporting dynamic scheduling of reverse sidelink traffic according to one or more aspects of the present disclosure is shown. The operations of the method 1000 may be implemented by the UE 115 or components thereof as described herein. For example, the operations of the method 1000 may be implemented by the UE 115 or components thereof as described herein. Figures 4 to 7 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0232] At 1005, the UE may determine a first set of resources for communication via a sidelink communication link between the first UE and the second UE. The operations of 1005 may be performed according to the methods described herein. In some examples, aspects of the operations of 1005 may be as described with reference to Figures 4 to 7 The sidelink resource manager described is used to perform the above operations.

[0233] At 1010, the UE may send a first SCI including a reverse sidelink scheduling indicator to a second UE via a sidelink communication link based on determining the first set of resources. The operations of 1010 may be performed according to the methods described herein. In some examples, aspects of the operations of 1010 may be as described with reference to Figures 4 to 7 Described SCI Send Manager to perform.

[0234] At 1015, the UE may send a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based on sending the first SCI. The operations of 1015 may be performed according to the methods described herein. In some examples, aspects of the operations of 1015 may be performed as described with reference to Figures 4 to 7 Described SCI Send Manager to perform.

[0235] At 1020, the UE may send an indication of a redundancy version associated with the reverse sidelink message via the second SCI. The operations of 1020 may be performed according to the methods described herein. In some examples, aspects of the operations of 1020 may be as described with reference to Figures 4 to 7 Described SCI Send Manager to perform.

[0236] At 1025, the UE may receive a reverse sidelink message from the second UE in response to sending the second SCI, wherein receiving the reverse sidelink message is based on sending the indication of the redundancy version. The operations of 1025 may be performed according to the methods described herein. In some examples, aspects of the operations of 1025 may be as described with reference to Figures 4 to 7 Described reverse sidelink receive manager to perform.

[0237] Figure 11 A flow chart illustrating a method 1100 for supporting dynamic scheduling of reverse sidelink traffic according to one or more aspects of the present disclosure is shown. The operations of the method 1100 may be implemented by the UE 115 or components thereof as described herein. For example, the operations of the method 1100 may be implemented by the UE 115 or components thereof as described herein. Figures 4 to 7 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the functions described herein. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the functions described herein.

[0238] At 1105, the UE may receive a first SCI including a reverse sidelink scheduling indicator from the second UE via a sidelink communication link between the first UE and the second UE. The operations of 1105 may be performed according to the methods described herein. In some examples, aspects of the operations of 1105 may be as described with reference to Figures 4 to 7 Described in the SCI Receive Manager to perform.

[0239] At 1110, the UE may receive a second SCI from a second UE via a sidelink communication link, the second SCI indicating a set of resources for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is based on receiving the first SCI. The operations of 1110 may be performed according to the methods described herein. In some examples, aspects of the operations of 1110 may be performed as described with reference to Figures 4 to 7 Described in the SCI Receive Manager to perform.

[0240] At 1115, the UE may send a reverse sidelink message to the second UE in response to receiving the second SCI. The operations of 1115 may be performed according to the methods described herein. In some examples, aspects of the operations of 1115 may be as described with reference to Figures 4 to 7 The reverse sidelink transmission manager described is executed.

[0241] Figure 12 A flow chart illustrating a method 1200 for supporting dynamic scheduling of reverse sidelink traffic according to aspects of the present disclosure is shown. The operations of the method 1200 may be implemented by the UE 115 or components thereof as described herein. For example, the operations of the method 1200 may be implemented by the UE 115 or components thereof as described herein. Figures 1 to 11 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the described functions.

[0242] At 1205, the method may include: sending a first SCI indicating a first set of resources to a second UE via a sidelink communication link. The operations of 1205 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1205 may be as described with reference to Figure 5 The SCI transmission manager 525 described above is executed.

[0243] At 1210, the method may include: sending a second SCI including a reverse sidelink scheduling indicator to a second UE via a sidelink communication link based on the first resource set, wherein sending the second SCI is based on sending the first SCI, and the second SCI is different from the first SCI. The operations of 1210 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1210 may be performed as described with reference to Figure 5 The SCI transmission manager 525 described above is executed.

[0244] At 1215, the method may include: in response to sending the second SCI, receiving a reverse sidelink message from the second UE. The operations of 1215 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1215 may be as described with reference to Figure 5 The reverse sidelink reception manager 530 described is executed.

[0245] Figure 13 A flow chart illustrating a method 1300 for supporting dynamic scheduling of reverse sidelink traffic according to aspects of the present disclosure is shown. The operations of the method 1300 may be implemented by the UE 115 or components thereof as described herein. For example, the operations of the method 1300 may be implemented by the UE 115 or components thereof as described herein. Figures 1 to 11 In some examples, the UE may execute an instruction set to control the functional units of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the described functions.

[0246] At 1305, the method may include: receiving a first SCI including a first resource set indicating a first resource set from the second UE via a sidelink communication link between the first UE and the second UE. The operations of 1305 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1305 may be performed as described with reference to Figure 5 The SCI reception manager 535 described is executed.

[0247] At 1310, the method may include: receiving a second SCI including a reverse sidelink scheduling indicator from a second UE via a sidelink communication link based on the first resource set, wherein receiving the second SCI is based on receiving the first SCI, and the second SCI is different from the first SCI. The operations of 1310 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1310 may be performed as described with reference to Figure 5 The SCI reception manager 535 described is executed.

[0248] At 1315, the method may include, in response to receiving the second SCI, sending a reverse sidelink message to the second UE. The operations of 1315 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1315 may be as described with reference to Figure 5 The reverse sidelink transmission manager 540 described above is executed.

[0249] It should be noted that the methods described herein describe possible implementations, and that the operations and steps may be rearranged or otherwise modified, and other implementations are possible. Furthermore, aspects from two or more methods may be combined.

[0250] The following provides a summary of various aspects of the disclosure:

[0251] Aspect 1: A method for wireless communication at a first UE, comprising: sending a first SCI indicating a first resource set to a second UE via a sidelink communication link; sending a second SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based at least in part on the first resource set, wherein sending the second SCI is at least in part based on sending the first SCI, and the second SCI is different from the first SCI; and receiving a reverse sidelink message from the second UE in response to sending the second SCI.

[0252] Aspect 2: The method according to Aspect 1 further includes: sending an indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE via the second SCI, wherein receiving the reverse sidelink message is in response to sending the indication of the request.

[0253] Aspect 3: The method according to any one of aspects 1 to 2 further includes: sending a HARQ process identifier associated with the reverse sidelink transmission from the second UE to the first UE via the second SCI.

[0254] Aspect 4: The method according to aspect 3 further includes: sending a feedback message to the second UE in response to receiving the reverse sidelink message and the HARQ process identifier.

[0255] Aspect 5: The method according to any one of Aspects 1 to 4 further includes: sending a sidelink grant via the sidelink communication link, the sidelink grant indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE, wherein receiving the reverse sidelink message is at least partially based on sending the sidelink grant.

[0256] Aspect 6: The method according to any one of Aspects 1 to 5 further includes: sending an indication of the MCS associated with the reverse sidelink message via at least one of the first SCI or the second SCI, wherein receiving the reverse sidelink message is at least partially based on sending the indication of the MCS.

[0257] Aspect 7: The method according to any one of Aspects 1 to 6 also includes: sending an indication of a redundant version associated with the reverse sidelink message via the second SCI, wherein receiving the reverse sidelink message is at least partially based on sending the indication of the redundant version.

[0258] Aspect 8: The method according to any one of Aspects 1 to 7 further includes: receiving a third SCI, a fourth SCI, or both from the second UE, wherein receiving the reverse sidelink message is at least partially based on receiving the third SCI, the fourth SCI, or both.

[0259] Aspect 9: A method according to any one of Aspects 1 to 8, wherein the second SCI indicates a second resource set used for reverse sidelink transmission from the second UE to the first UE via a sidelink communication link, and the reverse sidelink message is received within the second resource set.

[0260] Aspect 10: The method according to Aspect 9 further includes: monitoring the second resource set associated with the reverse sidelink transmission from the second UE to the first UE based at least in part on sending the second SCI, wherein receiving the reverse sidelink message is based at least in part on monitoring the second resource set.

[0261] Aspect 11: A method according to any one of Aspects 9 to 10, wherein the second resource set includes a time resource set and a frequency resource set allocated for the reverse sidelink transmission from the second UE to the first UE via the sidelink communication link.

[0262] Aspect 12: The method according to any one of Aspects 1 to 11 further includes: sending an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second SCI, wherein receiving the reverse sidelink message is at least partially based on the indication of the first identifier and the indication of the second identifier.

[0263] Aspect 13: The method according to any one of aspects 1 to 12 further includes: transmitting the first SCI via a PSCCH; and transmitting the second SCI via a PSSCH.

[0264] Aspect 14: The method according to any one of aspects 1 to 13, wherein the first SCI includes a first-level SCI, and the second sidelink control information includes a second-level SCI.

[0265] Aspect 15: The method according to any one of aspects 1 to 14, wherein the reverse sidelink scheduling indicator is indicated in a bit field of the second SCI.

[0266] Aspect 16: A method for wireless communication at a first UE, comprising: receiving a first SCI including a signal indicating a first resource set from the second UE via a sidelink communication link between the first UE and the second UE; receiving a second SCI including a reverse sidelink scheduling indicator from the second UE via the sidelink communication link based at least in part on the first resource set, wherein receiving the second SCI is at least in part based on receiving the first SCI, and the second SCI is different from the first SCI; and sending a reverse sidelink message to the second UE in response to receiving the second SCI.

[0267] Aspect 17: The method according to Aspect 16 further includes: receiving, via the second SCI, an indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both, to the second UE, wherein sending the reverse sidelink message is in response to receiving the indication of the request.

[0268] Aspect 18: The method according to any one of aspects 16 to 17, further comprising: receiving, via the second SCI, a HARQ process identifier associated with the reverse sidelink transmission from the first UE to the second UE.

[0269] Aspect 19: The method according to aspect 18 further includes: receiving a feedback message from the second UE in response to sending the reverse sidelink message and the HARQ process identifier.

[0270] Aspect 20: The method according to any one of Aspects 16 to 19 further includes: receiving a sidelink grant from the second UE via the sidelink communication link, the sidelink grant indicating a set of resources used for reverse sidelink transmission from the first UE to the second UE, wherein sending the reverse sidelink message is at least partially based on receiving the sidelink grant.

[0271] Aspect 21: The method according to any one of Aspects 16 to 20 further includes: receiving an indication of an MCS associated with the reverse sidelink message via at least one of the first SCI or the second SCI, wherein sending the reverse sidelink message is at least partially based on receiving the indication of the MCS.

[0272] Aspect 22: The method according to any one of Aspects 16 to 21 further includes: receiving an indication of a redundant version associated with the reverse sidelink message via the second SCI, wherein sending the reverse sidelink message is at least partially based on receiving the indication of the redundant version.

[0273] Aspect 23: The method according to any one of Aspects 16 to 22 further includes: sending a third SCI, a fourth SCI, or both to the second UE, wherein sending the reverse sidelink message is at least partially based on sending the third SCI, the fourth SCI, or both.

[0274] Aspect 24: A method according to any one of Aspects 16 to 23, wherein the second SCI indicates a resource set used for reverse sidelink transmission from the second UE to the first UE via a sidelink communication link, and the reverse sidelink message is sent within the resource set.

[0275] Aspect 25: The method according to aspect 24, wherein the resource set includes a time resource set and a frequency resource set allocated for the reverse sidelink transmission from the first UE to the second UE through the sidelink communication link.

[0276] Aspect 26: The method according to any one of Aspects 16 to 25 further includes: receiving an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second SCI, wherein sending the reverse sidelink message is at least partially based on the indication of the first identifier and the indication of the second identifier.

[0277] Aspect 27: The method according to any one of aspects 16 to 26, further comprising: receiving the first SCI via a PSCCH; and receiving the second SCI via a PSSCH.

[0278] Aspect 28: A method according to any one of aspects 16 to 27, wherein the first SCI comprises a first-level SCI, and the second SCI comprises a second-level SCI, and the reverse sidelink scheduling indicator is indicated in a bit field of the second SCI.

[0279] Aspect 29: A method for wireless communication at a first UE, comprising: sending a first SCI including a reverse sidelink scheduling indicator to a second UE via a sidelink communication link; sending a second SCI to the second UE via the sidelink communication link, the second SCI indicating a set of resources used for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is at least partially based on sending the first SCI, and the second SCI is different from the first SCI; and receiving a reverse sidelink message from the second UE in response to sending the second SCI.

[0280] Aspect 30: A method for wireless communication at a first UE, comprising: receiving a first SCI including a reverse sidelink scheduling indicator from the second UE via a sidelink communication link between the first UE and the second UE; receiving a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is at least partially based on receiving the first SCI, and the second SCI is different from the first SCI; and in response to receiving the second SCI, sending a reverse sidelink message to the second UE.

[0281] Aspect 31: An apparatus for wireless communication at a first UE, comprising a processor and a memory coupled to the processor, the processor and the memory being configured to perform the method according to any one of aspects 1 to 15.

[0282] Aspect 32: An apparatus for wireless communication at a first UE, comprising at least one unit for performing the method according to any one of aspects 1 to 15.

[0283] Aspect 33: A non-transitory computer-readable medium storing code for wireless communication at a first UE, the code comprising instructions executable by a processor to perform the method according to any one of aspects 1 to 15.

[0284] Aspect 34: An apparatus for wireless communication at a first UE, comprising a processor and a memory coupled to the processor, the processor and the memory configured to perform the method according to any one of aspects 16 to 28.

[0285] Aspect 35: An apparatus for wireless communication at a first UE, comprising at least one means for performing the method according to any one of aspects 16 to 28.

[0286] Aspect 36: A non-transitory computer-readable medium storing code for wireless communication at a first UE, the code comprising instructions executable by a processor to perform the method according to any one of aspects 16 to 28.

[0287] Aspect 37: An apparatus comprising a processor and a memory coupled to the processor, the processor and the memory being configured to perform the method according to any one of aspects 29 to 29.

[0288] Aspect 38: An apparatus comprising at least one unit for performing the method according to any one of aspects 29 to 29.

[0289] Aspect 39: A non-transitory computer-readable medium storing code, the code comprising instructions executable by a processor to perform the method according to any one of aspects 29 to 29.

[0290] Aspect 40: An apparatus comprising a processor and a memory coupled to the processor, the processor and the memory being configured to perform the method according to any one of aspects 30 to 30.

[0291] Aspect 41: An apparatus comprising at least one unit for performing the method according to any one of aspects 30 to 30.

[0292] Aspect 42: A non-transitory computer-readable medium storing code comprising instructions executable by a processor to perform the method according to any one of aspects 30 to 30.

[0293] Aspect 43: A method for wireless communication at a first UE, comprising: determining a first set of resources for communication via a sidelink communication link between the first UE and a second UE; sending a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based at least in part on determining the first set of resources; sending a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is at least in part based on sending the first SCI; and receiving a reverse sidelink message from the second UE in response to sending the second SCI.

[0294] Aspect 44: The method according to Aspect 43 further includes: sending a sidelink grant via the sidelink communication link, the sidelink grant indicating the second set of resources used for reverse sidelink transmission from the second UE to the first UE, wherein receiving the reverse sidelink message is at least partially based on sending the sidelink grant.

[0295] Aspect 45: The method according to Aspect 43 or 44 further includes: sending an indication of a modulation and coding scheme associated with the reverse sidelink message via at least one of the first SCI or the second SCI, wherein receiving the reverse sidelink message is at least partially based on sending the indication of the modulation and coding scheme.

[0296] Aspect 46: The method according to any one of Aspects 43 to 45 further includes: sending an indication of a redundant version associated with the reverse sidelink message via the second SCI, wherein receiving the reverse sidelink message is at least partially based on sending the indication of the redundant version.

[0297] Aspect 47: The method according to any one of Aspects 43 to 45 further includes: sending an indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE via the second SCI, wherein receiving the reverse sidelink message is in response to sending the indication of the request.

[0298] Aspect 48: The method according to any one of aspects 43 to 47, further comprising: sending a HARQ process identifier associated with the reverse sidelink transmission from the second UE to the first UE via the second SCI.

[0299] Aspect 49: The method according to aspect 48 further includes: in response to receiving the reverse sidelink message and the HARQ process identifier, sending a feedback message to the second UE.

[0300] Aspect 50: The method according to any one of Aspects 43 to 49 further includes: receiving a third SCI, a fourth SCI, or both from the second UE, wherein receiving the reverse sidelink message is at least partially based on receiving the third SCI, the fourth SCI, or both.

[0301] Aspect 51: The method according to any one of Aspects 43 to 50 further includes: monitoring the second resource set associated with the reverse sidelink transmission from the second UE to the first UE based at least in part on sending the second SCI, wherein receiving the reverse sidelink message is based at least in part on monitoring the second resource set.

[0302] Aspect 52: The method according to any one of Aspects 43 to 51 further includes: sending an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second SCI, wherein receiving the reverse sidelink message is at least partially based on the indication of the first identifier and the indication of the second identifier.

[0303] Aspect 53: A method according to any one of Aspects 43 to 52, wherein the second resource set includes a time resource set and a frequency resource set allocated for the reverse sidelink transmission from the second UE to the first UE via the sidelink communication link.

[0304] Aspect 54: The method according to any one of aspects 43 to 53, further comprising: transmitting the first SCI via a PSCCH; and transmitting the second SCI via a PSSCH.

[0305] Aspect 55: The method according to any one of aspects 43 to 54, wherein the first SCI comprises a first type of SCI, and wherein the second SCI comprises a second type of SCI different from the first type of SCI.

[0306] Aspect 56: The method according to aspect 55, wherein the first SCI comprises a first-level SCI, and wherein the second SCI comprises a second-level SCI.

[0307] Aspect 57: The method according to any one of aspects 43 to 56, further wherein the reverse sidelink scheduling indicator is indicated in a bit field of the first SCI.

[0308] Aspect 58: A method for wireless communication at a first UE, comprising: receiving a first SCI including a reverse sidelink scheduling indicator from the second UE via a sidelink communication link between the first UE and the second UE; receiving a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is at least partially based on receiving the first SCI; and sending a reverse sidelink message to the second UE in response to receiving the second SCI.

[0309] Aspect 59: The method according to Aspect 58 further includes: receiving a sidelink grant from the second UE via the sidelink communication link, the sidelink grant indicating the resource set used for reverse sidelink transmission from the first UE to the second UE, wherein sending the reverse sidelink message is at least partially based on receiving the sidelink grant.

[0310] Aspect 60: The method according to any one of Aspects 58 to 59 further includes: receiving an indication of a modulation and coding scheme associated with the reverse sidelink message via at least one of the first SCI or the second SCI, wherein sending the reverse sidelink message is at least partially based on receiving the indication of the modulation and coding scheme.

[0311] Aspect 61: The method according to any one of Aspects 58 to 60 further includes: receiving an indication of a redundant version associated with the reverse sidelink message via the second SCI, wherein sending the reverse sidelink message is at least partially based on receiving the indication of the redundant version.

[0312] Aspect 62: The method according to any one of Aspects 58 to 61 further includes: receiving, via the second SCI, an indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both, to the second UE, wherein sending the reverse sidelink message is in response to receiving the indication of the request.

[0313] Aspect 63: The method according to any one of aspects 58 to 62, further comprising: receiving, via the second SCI, a HARQ process identifier associated with the reverse sidelink transmission from the first UE to the second UE.

[0314] Aspect 64: The method according to any one of aspects 58 to 63 further includes: receiving a feedback message from the second UE in response to sending the reverse sidelink message and the HARQ process identifier.

[0315] Aspect 65: The method according to any one of Aspects 58 to 64 further includes: sending a third SCI, a fourth SCI, or both to the second UE, wherein sending the reverse sidelink message is at least partially based on sending the third SCI, the fourth SCI, or both.

[0316] Aspect 66: The method according to any one of Aspects 58 to 65 further includes: receiving an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second SCI, wherein sending the reverse sidelink message is at least partially based on the indication of the first identifier and the indication of the second identifier.

[0317] Aspect 67: A method according to any one of Aspects 58 to 66, wherein the resource set includes a time resource set and a frequency resource set allocated for the reverse sidelink transmission from the first UE to the second UE via the sidelink communication link.

[0318] Aspect 68: The method according to any one of aspects 58 to 67, further comprising: receiving the first SCI via a PSCCH; and receiving the second SCI via a PSSCH.

[0319] Aspect 69: The method according to any one of aspects 58 to 68, wherein the first SCI comprises a first type of SCI, and wherein the second SCI comprises a second type of SCI different from the first type of SCI.

[0320] Aspect 70: The method according to aspect 69, wherein the first SCI comprises a first-level SCI, and wherein the second SCI comprises a second-level SCI.

[0321] Aspect 71: The method according to any one of aspects 58 to 70, further wherein: the reverse sidelink scheduling indicator is indicated in a bit field of the first SCI.

[0322] Aspect 72: An apparatus for wireless communication at a first UE, comprising: a processor, a memory coupled to the processor, the processor and the memory being configured to: determine a first set of resources for communication via a sidelink communication link between the first UE and a second UE; send a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based at least in part on determining the first set of resources; send a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is at least in part based on sending the first SCI; and receive a reverse sidelink message from the second UE in response to sending the second SCI.

[0323] Aspect 73: An apparatus according to Aspect 72, wherein the processor and the memory are further configured to: send an indication of a modulation and coding scheme associated with the reverse sidelink message via at least one of the first SCI or the second SCI, wherein receiving the reverse sidelink message is at least partially based on sending the indication of the modulation and coding scheme.

[0324] Aspect 74: An apparatus according to any one of Aspects 72 to 73, wherein the processor and the memory are further configured to: send an indication of a redundant version associated with the reverse sidelink message via the second SCI, wherein receiving the reverse sidelink message is at least partially based on sending the indication of the redundant version.

[0325] Aspect 75: An apparatus according to any one of Aspects 72 to 74, wherein the processor and the memory are further configured to: send an indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE via the second SCI, wherein receiving the reverse sidelink message is in response to sending the indication of the request.

[0326] Aspect 76: An apparatus according to any one of aspects 72 to 75, wherein the processor and the memory are further configured to: send a HARQ process identifier associated with the reverse sidelink transmission from the second UE to the first UE via the second SCI.

[0327] Aspect 77: An apparatus according to any one of Aspects 72 to 76, the apparatus further comprising an antenna array, wherein the processor and the memory are further configured to: send a feedback message to the second UE in response to receiving the reverse sidelink message and the HARQ process identifier.

[0328] Aspect 78: An apparatus according to any one of Aspects 72 to 77, wherein the processor and the memory are further configured to: receive a third SCI, a fourth SCI, or both from the second UE, wherein receiving the reverse sidelink message is at least partially based on receiving the third SCI, the fourth SCI, or both.

[0329] Aspect 79: An apparatus according to any one of Aspects 72 to 78, wherein the processor and the memory are further configured to: monitor the second resource set associated with the reverse sidelink transmission from the second UE to the first UE based at least in part on sending the second SCI, wherein receiving the reverse sidelink message is based at least in part on monitoring the second resource set.

[0330] Aspect 80: An apparatus according to any one of Aspects 72 to 79, wherein the processor and the memory are further configured to: send an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second SCI, wherein receiving the reverse sidelink message is at least partially based on the indication of the first identifier and the indication of the second identifier.

[0331] Aspect 81: An apparatus according to any one of Aspects 72 to 80, wherein the second resource set includes a time resource set and a frequency resource set allocated for the reverse sidelink transmission from the second UE to the first UE via the sidelink communication link.

[0332] Aspect 82: The apparatus according to any one of aspects 72 to 81, wherein the processor and the memory are further configured to: transmit the first SCI via a PSCCH; and transmit the second SCI via a PSSCH.

[0333] Aspect 83: An apparatus according to any one of aspects 72 to 82, wherein the first SCI comprises a first type of SCI, and wherein the second SCI comprises a second type of SCI different from the first type of SCI.

[0334] Aspect 84: The apparatus of aspect 83, wherein the first SCI comprises a first-level SCI, and wherein the second SCI comprises a second-level SCI.

[0335] Aspect 85: The apparatus according to any one of aspects 72 to 84, wherein the reverse sidelink scheduling indicator is indicated in a bit field of the first SCI.

[0336] Aspect 86: An apparatus for wireless communication at a first UE, comprising: a processor, a memory coupled to the processor, the processor and the memory being configured to: receive a first SCI including a reverse sidelink scheduling indicator from the second UE via a sidelink communication link between the first UE and the second UE; receive a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is at least partially based on receiving the first SCI; and in response to receiving the second SCI, send a reverse sidelink message to the second UE.

[0337] Aspect 87: An apparatus according to Aspect 86, wherein the processor and the memory are further configured to: receive an indication of a modulation and coding scheme associated with the reverse sidelink message via at least one of the first SCI or the second SCI, wherein sending the reverse sidelink message is at least partially based on receiving the indication of the modulation and coding scheme.

[0338] Aspect 88: An apparatus according to any one of Aspects 86 to 87, wherein the processor and the memory are further configured to: receive an indication of a redundant version associated with the reverse sidelink message via the second SCI, wherein sending the reverse sidelink message is at least partially based on receiving the indication of the redundant version.

[0339] Aspect 89: An apparatus according to any one of Aspects 86 to 88, wherein the processor and the memory are further configured to: receive, via the second SCI, an indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both, to the second UE, wherein sending the reverse sidelink message is in response to receiving the indication of the request.

[0340] Aspect 90: An apparatus according to any one of Aspects 86 to 89, the apparatus further comprising an antenna array, wherein the processor and the memory are further configured to: receive a HARQ process identifier associated with the reverse sidelink transmission from the first UE to the second UE via the second SCI.

[0341] Aspect 91: The apparatus of aspect 89, wherein the processor and the memory are further configured to: receive a feedback message from the second UE in response to sending the reverse sidelink message and the HARQ process identifier.

[0342] Aspect 92: An apparatus according to any one of Aspects 86 to 91, wherein the processor and the memory are further configured to: send a third SCI, a fourth SCI, or both to the second UE, wherein sending the reverse sidelink message is at least partially based on sending the third SCI, the fourth SCI, or both.

[0343] Aspect 93: An apparatus according to any one of Aspects 86 to 92, wherein the processor and the memory are further configured to: receive an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second SCI, wherein sending the reverse sidelink message is at least partially based on the indication of the first identifier and the indication of the second identifier.

[0344] Aspect 94: An apparatus according to any one of Aspects 86 to 93, wherein the resource set includes a time resource set and a frequency resource set allocated for the reverse sidelink transmission from the first UE to the second UE via the sidelink communication link.

[0345] Aspect 95: The apparatus according to any one of aspects 86 to 94, wherein the processor and the memory are further configured to: receive the first SCI via a PSCCH; and receive the second SCI via a PSSCH.

[0346] Aspect 96: An apparatus according to any one of aspects 86 to 95, wherein the first SCI comprises a first type of SCI, and wherein the second SCI comprises a second type of SCI different from the first type of SCI.

[0347] Aspect 97: The apparatus of aspect 96, wherein the first SCI comprises a first-level SCI, and wherein the second SCI comprises a second-level SCI.

[0348] Aspect 98: The apparatus of any one of aspects 86 to 97, wherein the reverse sidelink scheduling indicator is indicated in a bit field of the first SCI.

[0349] Aspect 99: An apparatus for wireless communication at a first UE, comprising: a unit for determining a first set of resources for communication via a sidelink communication link between the first UE and a second UE; a unit for sending a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based at least in part on determining the first set of resources; a unit for sending a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is at least in part based on sending the first SCI; and a unit for receiving a reverse sidelink message from the second UE in response to sending the second SCI.

[0350] Aspect 100: An apparatus for wireless communication at a first UE, comprising: a unit for receiving a first SCI including a reverse sidelink scheduling indicator from the second UE via a sidelink communication link between the first UE and the second UE; a unit for receiving a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is at least partially based on receiving the first SCI; and a unit for sending a reverse sidelink message to the second UE in response to receiving the second SCI.

[0351] Aspect 101: A non-transitory computer-readable medium storing code for wireless communication at a first UE, the code comprising instructions executable by a processor to: determine a first set of resources for communication via a sidelink communication link between the first UE and a second UE; send a first SCI including a reverse sidelink scheduling indicator to the second UE via the sidelink communication link based at least in part on determining the first set of resources; send a second SCI to the second UE via the sidelink communication link, the second SCI indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein sending the second SCI is based at least in part on sending the first SCI; and receive a reverse sidelink message from the second UE in response to sending the second SCI.

[0352] Aspect 102: A non-transitory computer-readable medium storing a code for wireless communication at a first UE, the code comprising instructions executable by a processor to perform the following operations: receiving a first SCI including a reverse sidelink scheduling indicator from the second UE via a sidelink communication link between the first UE and the second UE; receiving a second SCI from the second UE via the sidelink communication link, the second SCI indicating a set of resources for reverse sidelink transmission from the first UE to the second UE via the sidelink communication link, wherein receiving the second SCI is at least partially based on receiving the first SCI; and sending a reverse sidelink message to the second UE in response to receiving the second SCI.

[0353] Aspect 103: An apparatus for wireless communication, comprising a processor and a memory coupled to the processor, the processor and the memory configured to perform the method according to any one of aspects 43 to 71.

[0354] Aspect 104: An apparatus for wireless communication, comprising at least one means for performing the method of any one of aspects 43 to 71.

[0355] Aspect 105: A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method according to any one of aspects 43 to 71.

[0356] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for example purposes, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used throughout much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR networks. For example, the techniques described herein may be applicable to various other wireless communication systems, such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0357] The information and signals described herein may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0358] The various illustrative blocks and components described in conjunction with the disclosure herein may be implemented or executed using a general purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration).

[0359] The functions described herein may be implemented using hardware, software executed by a processor, firmware, or any combination thereof. If implemented using software executed by a processor, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or codes. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or a combination of any of these. Features that implement the functions may also be physically located at various locations, including being distributed so that portions of the functions are implemented at different physical locations.

[0360] Computer readable medium includes non-transient computer storage medium and communication medium, and communication medium includes any medium that promotes the transmission of computer program from one place to another place.Non-transient storage medium can be any available medium that can be accessed by general-purpose computer or special-purpose computer.By way of example and not limitation, non-transient computer readable medium can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disc storage, disk storage or other magnetic storage device or can be used for carrying or storing desired program code unit and any other non-transient medium that can be accessed by general-purpose or special-purpose computer or general or special-purpose processor in the form of instruction or data structure.In addition, any connection is suitably referred to as computer readable medium.For example, if software is to be sent from website, server or other remote source using coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technology such as infrared, radio and microwave, then coaxial cable, optical fiber cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave are included in the definition of computer readable medium. As used herein, disk and disc include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein 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.

[0361] As used herein (including in the claims), "or" as used in a list of items (e.g., a list of items ending with a phrase such as "at least one of" or "one or more of") indicates an inclusive list, so 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). Furthermore, as used herein, the phrase "based on" should not be interpreted as a reference to a closed set of conditions. For example, an example step described as "based on condition A" could be based on both condition A and condition B without departing from the scope of this disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on" is interpreted.

[0362] In the accompanying drawings, similar components or features may have the same reference number. In addition, various components of the same type may be distinguished by following the reference number with a dash and a second reference number to distinguish between similar components. If only the first reference number is used in the specification, the description applies to any one of the similar components having the same first reference number, regardless of the second reference number or other subsequent reference numbers.

[0363] The descriptions set forth herein in conjunction with the accompanying drawings describe example configurations and do not represent all examples that can be implemented or within the scope of the claims. The term "example" as used herein means "serving as an example, instance, or illustration," rather than "preferred" or "having advantages over other examples." The detailed description includes specific details for the purpose of providing an understanding of the described techniques. However, these techniques can be implemented without these specific details. In some cases, known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0364] The description herein is provided to enable those skilled in the art to implement or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the overall principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is intended to be used in the broadest sense consistent with the principles and novel features disclosed herein.

Claims

1. An apparatus for wireless communication at a first user equipment (UE), comprising: processor; as well as a memory coupled to the processor, the processor being configured to: sending, via a physical sidelink control channel of the sidelink communication link, first sidelink control information indicating the first set of resources to the second UE; transmitting, based at least in part on the first set of resources, second sidelink control information indicating a reverse sidelink scheduling indicator to the second UE via a physical sidelink shared channel of the sidelink communication link, wherein the transmission of the second sidelink control information is based at least in part on the first sidelink control information, the second sidelink control information being different from the first sidelink control information; as well as In response to the second sidelink control information, a reverse sidelink message is received from the second UE.

2. The device according to claim 1, wherein The processor is further configured to: An indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE is sent via the second sidelink control information, wherein the reverse sidelink message is received in response to the indication of the request.

3. The device according to claim 1, wherein The processor is further configured to: A hybrid automatic repeat request process identifier associated with the reverse sidelink transmission from the second UE to the first UE is sent via the second sidelink control information.

4. The device according to claim 3, wherein The processor is further configured to: In response to the reverse sidelink message and the hybrid automatic repeat request process identifier, a feedback message is sent to the second UE.

5. The device according to claim 1, wherein The processor is further configured to: A sidelink grant is sent via the sidelink communication link, the sidelink grant indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE, wherein the reverse sidelink message is received based at least in part on the sidelink grant.

6. The device according to claim 1, wherein The processor is further configured to: An indication of a modulation and coding scheme associated with the reverse sidelink message is sent via at least one of the first sidelink control information or the second sidelink control information, wherein the reverse sidelink message is received at least in part based on the indication of the modulation and coding scheme.

7. The device according to claim 1, wherein The processor is further configured to: An indication of a redundancy version associated with the reverse sidelink message is sent via the second sidelink control information, wherein the reverse sidelink message is received based at least in part on the indication of the redundancy version.

8. The device according to claim 1, wherein The processor is further configured to: Third sidelink control information, fourth sidelink control information, or both are received from the second UE, wherein the reverse sidelink message is received based at least in part on the third sidelink control information, the fourth sidelink control information, or both.

9. The device according to claim 1, wherein The second sidelink control information indicates a second set of resources used for reverse sidelink transmission from the second UE to the first UE over a sidelink communication link, wherein the reverse sidelink message is received within the second set of resources.

10. The device according to claim 9, wherein The processor is further configured to: The second set of resources associated with the reverse sidelink transmission from the second UE to the first UE is monitored at least in part based on the second sidelink control information, wherein the reverse sidelink message is received based at least in part on the monitored second set of resources.

11. The device according to claim 9, wherein The second set of resources includes a set of time resources and a set of frequency resources allocated for the reverse sidelink transmission from the second UE to the first UE over the sidelink communication link.

12. The apparatus according to claim 1, further comprising: an antenna configured to send an indication of a first identifier associated with the first UE and a second identifier associated with the second UE via the second sidelink control information, wherein the reverse sidelink message is received based at least in part on the indication of the first identifier and the indication of the second identifier.

13. The device according to claim 1, wherein The first sidelink control information comprises first-level sidelink control information, and wherein the second sidelink control information comprises second-level sidelink control information.

14. The device according to claim 1, wherein The reverse sidelink scheduling indicator is indicated in a bit field of the second sidelink control information.

15. An apparatus for wireless communication at a first user equipment (UE), comprising: processor; as well as a memory coupled to the processor, the processor being configured to: receiving, from a second UE via a physical sidelink control channel of a sidelink communication link between the first UE and the second UE, first sidelink control information indicating a first set of resources; receiving, from the second UE via a physical sidelink shared channel of the sidelink communication link, second sidelink control information indicating a reverse sidelink scheduling indicator based at least in part on the first set of resources, wherein the receiving of the second sidelink control information is based at least in part on the first sidelink control information, the second sidelink control information being different from the first sidelink control information; as well as In response to the second sidelink control information, a reverse sidelink message is sent to the second UE.

16. The device according to claim 15, wherein The processor is further configured to: An indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE is received via the second sidelink control information, wherein the reverse sidelink message is sent in response to the indication of the request.

17. The device according to claim 15, wherein The processor is further configured to: A hybrid automatic repeat request process identifier associated with a reverse sidelink transmission from the first UE to the second UE is received via the second sidelink control information.

18. The device according to claim 17, wherein The processor is further configured to: A feedback message is received from the second UE in response to the reverse sidelink message and the hybrid automatic repeat request process identifier.

19. The device according to claim 15, wherein The processor is further configured to: A sidelink grant is received from the second UE via the sidelink communication link, the sidelink grant indicating a set of resources for reverse sidelink transmission from the first UE to the second UE, wherein the reverse sidelink message is sent at least in part based on the sidelink grant.

20. The apparatus according to claim 15, wherein The processor is further configured to: An indication of a modulation and coding scheme associated with the reverse sidelink message is received via at least one of the first sidelink control information or the second sidelink control information, wherein the reverse sidelink message is sent at least in part based on the indication of the modulation and coding scheme.

21. The apparatus according to claim 15, wherein The processor is further configured to: An indication of a redundancy version associated with the reverse sidelink message is received via the second sidelink control information, wherein the reverse sidelink message is sent based at least in part on the indication of the redundancy version.

22. The apparatus according to claim 15, wherein The processor is further configured to: Third sidelink control information, fourth sidelink control information, or both are sent to the second UE, wherein the reverse sidelink message is sent at least in part based on the third sidelink control information, the fourth sidelink control information, or both.

23. The apparatus according to claim 15, wherein The second sidelink control information indicates a set of resources used for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein the reverse sidelink message is sent within the set of resources.

24. The device according to claim 23, wherein The set of resources includes a set of time resources and a set of frequency resources allocated for the reverse sidelink transmission from the first UE to the second UE over the sidelink communication link.

25. The apparatus of claim 15, further comprising: An antenna is configured to receive, via the second sidelink control information, an indication of a first identifier associated with the first UE and a second identifier associated with the second UE, wherein the reverse sidelink message is sent at least in part based on the indication of the first identifier and the indication of the second identifier.

26. The apparatus according to claim 15, wherein The first sidelink control information comprises first-level sidelink control information, and wherein the second sidelink control information comprises second-level sidelink control information, and wherein the reverse sidelink scheduling indicator is indicated in a bit field of the second sidelink control information.

27. An apparatus for wireless communication at a first user equipment (UE), comprising: processor, and a memory coupled to the processor, the processor being configured to: sending, via a physical sidelink control channel of the sidelink communication link, first sidelink control information indicating a reverse sidelink scheduling indicator to the second UE; sending second sidelink control information to the second UE via a physical sidelink shared channel of the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the second UE to the first UE over the sidelink communication link, wherein the second sidelink control information is sent at least in part based on the first sidelink control information, and the second sidelink control information is different from the first sidelink control information; and In response to the second sidelink control information, a reverse sidelink message is received from the second UE.

28. The apparatus according to claim 27, wherein The processor is further configured to: An indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE is sent via the second sidelink control information, wherein the reverse sidelink message is received in response to the indication of the request.

29. The apparatus according to claim 27, wherein The processor is further configured to: A hybrid automatic repeat request process identifier associated with the reverse sidelink transmission from the second UE to the first UE is sent via the second sidelink control information.

30. The apparatus according to claim 29, wherein The processor is further configured to: In response to the reverse sidelink message and the hybrid automatic repeat request process identifier, a feedback message is sent to the second UE.

31. The apparatus according to claim 27, wherein The processor is further configured to: A sidelink grant is sent via the sidelink communication link, the sidelink grant indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE, wherein the reverse sidelink message is received based at least in part on the sidelink grant.

32. The apparatus of claim 27, wherein: The processor is further configured to: An indication of a modulation and coding scheme associated with the reverse sidelink message is sent via at least one of the first sidelink control information or the second sidelink control information, wherein the reverse sidelink message is received at least in part based on the indication of the modulation and coding scheme.

33. An apparatus for wireless communication at a first user equipment (UE), comprising: processor, and a memory coupled to the processor, the processor being configured to: receiving, from a second UE via a physical sidelink control channel of a sidelink communication link between the first UE and the second UE, first sidelink control information indicating a reverse sidelink scheduling indicator; receiving second sidelink control information from the second UE via a physical sidelink shared channel of the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the first UE to the second UE over the sidelink communication link, wherein the second sidelink control information is received based at least in part on the first sidelink control information, and the second sidelink control information is different from the first sidelink control information; and In response to the second sidelink control information, a reverse sidelink message is sent to the second UE.

34. The apparatus according to claim 33, wherein The processor is further configured to: An indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE is received via the second sidelink control information, wherein the reverse sidelink message is sent in response to the indication of the request.

35. The apparatus of claim 33, wherein: The processor is further configured to: A hybrid automatic repeat request process identifier associated with a reverse sidelink transmission from the first UE to the second UE is received via the second sidelink control information.

36. The apparatus of claim 35, wherein: The processor is further configured to: A feedback message is received from the second UE in response to the reverse sidelink message and the hybrid automatic repeat request process identifier.

37. The apparatus of claim 33, wherein: The processor is further configured to: A sidelink grant is received from the second UE via the sidelink communication link, the sidelink grant indicating a set of resources for reverse sidelink transmission from the first UE to the second UE, wherein the reverse sidelink message is sent at least in part based on the sidelink grant.

38. The apparatus of claim 33, wherein: The processor is further configured to: An indication of a modulation and coding scheme associated with the reverse sidelink message is received via at least one of the first sidelink control information or the second sidelink control information, wherein the reverse sidelink message is sent at least in part based on the indication of the modulation and coding scheme.

39. A method for wireless communication at a first user equipment (UE), the method comprising: sending, via a physical sidelink control channel of the sidelink communication link, first sidelink control information indicating the first set of resources to the second UE; transmitting, based at least in part on the first set of resources, second sidelink control information indicating a reverse sidelink scheduling indicator to the second UE via a physical sidelink shared channel of the sidelink communication link, wherein the second sidelink control information is transmitted based at least in part on the first sidelink control information and is different from the first sidelink control information; as well as In response to the second sidelink control information, a reverse sidelink message is received from the second UE.

40. The method of claim 39, further comprising: An indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE is sent via the second sidelink control information, wherein the reverse sidelink message is received in response to the indication of the request.

41. The method of claim 39, further comprising: A hybrid automatic repeat request process identifier associated with the reverse sidelink transmission from the second UE to the first UE is sent via the second sidelink control information.

42. The method of claim 41 , further comprising: In response to the reverse sidelink message and the hybrid automatic repeat request process identifier, a feedback message is sent to the second UE.

43. The method of claim 39, further comprising: A sidelink grant is sent via the sidelink communication link, the sidelink grant indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE, wherein the reverse sidelink message is received based at least in part on the sidelink grant.

44. The method of claim 39, further comprising: An indication of a modulation and coding scheme associated with the reverse sidelink message is sent via at least one of the first sidelink control information or the second sidelink control information, wherein the reverse sidelink message is received at least in part based on the indication of the modulation and coding scheme.

45. The method of claim 39, further comprising: An indication of a redundancy version associated with the reverse sidelink message is sent via the second sidelink control information, wherein the reverse sidelink message is received based at least in part on the indication of the redundancy version.

46. ​​The method of claim 39, further comprising: Third sidelink control information, fourth sidelink control information, or both are received from the second UE, wherein the reverse sidelink message is received based at least in part on the third sidelink control information, the fourth sidelink control information, or both.

47. The method of claim 39, wherein: The second sidelink control information indicates a second set of resources used for reverse sidelink transmission from the second UE to the first UE over a sidelink communication link, wherein the reverse sidelink message is received within the second set of resources.

48. The method of claim 47, further comprising: The second set of resources associated with the reverse sidelink transmission from the second UE to the first UE is monitored based at least in part on the second sidelink control information, wherein the reverse sidelink message is received based at least in part on the monitoring.

49. A method for wireless communication at a first user equipment (UE), the method comprising: receiving, from a second UE via a physical sidelink control channel of a sidelink communication link between the first UE and the second UE, first sidelink control information indicating a first set of resources; receiving, from the second UE via a physical sidelink shared channel of the sidelink communication link based at least in part on the first set of resources, second sidelink control information indicating a reverse sidelink scheduling indicator, wherein the second sidelink control information is received based at least in part on the first sidelink control information and is different from the first sidelink control information; and In response to the second sidelink control information, a reverse sidelink message is sent to the second UE.

50. The method of claim 49, further comprising: An indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE is received via the second sidelink control information, wherein the reverse sidelink message is sent in response to the indication of the request.

51. The method of claim 49, further comprising: A hybrid automatic repeat request process identifier associated with a reverse sidelink transmission from the first UE to the second UE is received via the second sidelink control information.

52. The method of claim 51 , further comprising: A feedback message is received from the second UE in response to the reverse sidelink message and the hybrid automatic repeat request process identifier.

53. The method of claim 49, further comprising: A sidelink grant is received from the second UE via the sidelink communication link, the sidelink grant indicating a set of resources for reverse sidelink transmission from the first UE to the second UE, wherein the reverse sidelink message is sent at least in part based on the sidelink grant.

54. The method of claim 49, further comprising: An indication of a modulation and coding scheme associated with the reverse sidelink message is received via at least one of the first sidelink control information or the second sidelink control information, wherein the reverse sidelink message is sent at least in part based on the indication of the modulation and coding scheme.

55. The method of claim 49, further comprising: An indication of a redundancy version associated with the reverse sidelink message is received via the second sidelink control information, wherein the reverse sidelink message is sent based at least in part on the indication of the redundancy version.

56. The method of claim 49, further comprising: Third sidelink control information, fourth sidelink control information, or both are sent to the second UE, wherein the reverse sidelink message is sent at least in part based on the third sidelink control information, the fourth sidelink control information, or both.

57. A method for wireless communication at a first user equipment (UE), the method comprising: sending, via a physical sidelink control channel of the sidelink communication link, first sidelink control information including a reverse sidelink scheduling indicator to the second UE; sending second sidelink control information to the second UE via a physical sidelink shared channel of the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the second UE to the first UE via the sidelink communication link, wherein the second sidelink control information is sent at least in part based on the first sidelink control information, and the second sidelink control information is different from the first sidelink control information; as well as In response to the second sidelink control information, a reverse sidelink message is received from the second UE.

58. A method for wireless communication at a first user equipment (UE), the method comprising: receiving, from a second UE via a physical sidelink control channel of a sidelink communication link between the first UE and the second UE, first sidelink control information including a reverse sidelink scheduling indicator; receiving second sidelink control information from the second UE via a physical sidelink shared channel of the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the first UE to the second UE over the sidelink communication link, wherein the second sidelink control information is received based at least in part on the first sidelink control information, and the second sidelink control information is different from the first sidelink control information; and In response to the second sidelink control information, a reverse sidelink message is sent to the second UE.

59. A non-transitory computer-readable medium storing code for wireless communication at a first user equipment (UE), the code comprising instructions executable by a processor to: sending, via a physical sidelink control channel of the sidelink communication link, first sidelink control information indicating the first set of resources to the second UE; sending second sidelink control information including a reverse sidelink scheduling indicator to the second UE via a physical sidelink shared channel of the sidelink communication link based at least in part on the first set of resources, wherein The second sidelink control information is sent based at least in part on the first sidelink control information, the second sidelink control information being different from the first sidelink control information; as well as In response to the second sidelink control information, a reverse sidelink message is received from the second UE.

60. The non-transitory computer readable medium of claim 59, wherein: The instructions are further executable by the processor to: An indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE is sent via the second sidelink control information, wherein the reverse sidelink message is received in response to the indication of the request.

61. The non-transitory computer readable medium of claim 59, wherein: The instructions are further executable by the processor to: A hybrid automatic repeat request process identifier associated with the reverse sidelink transmission from the second UE to the first UE is sent via the second sidelink control information.

62. The non-transitory computer readable medium of claim 61, wherein: The instructions are further executable by the processor to: In response to the reverse sidelink message and the hybrid automatic repeat request process identifier, a feedback message is sent to the second UE.

63. The non-transitory computer readable medium of claim 59, wherein: The instructions are further executable by the processor to: A sidelink grant is sent via the sidelink communication link, the sidelink grant indicating a second set of resources for reverse sidelink transmission from the second UE to the first UE, wherein the reverse sidelink message is received based at least in part on the sidelink grant.

64. The non-transitory computer readable medium of claim 59, wherein: The instructions are further executable by the processor to: An indication of a modulation and coding scheme associated with the reverse sidelink message is sent via at least one of the first sidelink control information or the second sidelink control information, wherein the reverse sidelink message is received at least in part based on the indication of the modulation and coding scheme.

65. The non-transitory computer readable medium of claim 59, wherein: The instructions are further executable by the processor to: An indication of a redundancy version associated with the reverse sidelink message is sent via the second sidelink control information, wherein the reverse sidelink message is received based at least in part on the indication of the redundancy version.

66. The non-transitory computer readable medium of claim 59, wherein: The instructions are further executable by the processor to: Third sidelink control information, fourth sidelink control information, or both are received from the second UE, wherein the reverse sidelink message is received based at least in part on the third sidelink control information, the fourth sidelink control information, or both.

67. The non-transitory computer readable medium of claim 59, wherein: The second sidelink control information indicates a second set of resources used for reverse sidelink transmission from the second UE to the first UE over a sidelink communication link, wherein the reverse sidelink message is received within the second set of resources.

68. The non-transitory computer readable medium of claim 67, wherein: The instructions are further executable by the processor to: The second set of resources associated with the reverse sidelink transmission from the second UE to the first UE is monitored based at least in part on the second sidelink control information, wherein the reverse sidelink message is received based at least in part on the monitoring.

69. A non-transitory computer-readable medium storing code for wireless communication at a first user equipment (UE), the code comprising instructions executable by a processor to: receiving, from a second UE via a physical sidelink control channel of a sidelink communication link between the first UE and the second UE, first sidelink control information indicating a first set of resources; receiving, from the second UE via a physical sidelink shared channel of the sidelink communication link, second sidelink control information indicating a reverse sidelink scheduling indicator based at least in part on the first set of resources, wherein The second sidelink control information is received based at least in part on the first sidelink control information, the second sidelink control information being different from the first sidelink control information; as well as In response to the second sidelink control information, a reverse sidelink message is sent to the second UE.

70. The non-transitory computer readable medium of claim 69, wherein: The instructions are further executable by the processor to: An indication of a request to send a new reverse sidelink message, retransmit a previous reverse sidelink message, or both to the second UE is received via the second sidelink control information, wherein the reverse sidelink message is sent in response to the indication of the request.

71. The non-transitory computer readable medium of claim 69, wherein: The instructions are further executable by the processor to: A hybrid automatic repeat request process identifier associated with a reverse sidelink transmission from the first UE to the second UE is received via the second sidelink control information.

72. The non-transitory computer readable medium of claim 71, wherein: The instructions are further executable by the processor to: A feedback message is received from the second UE in response to the reverse sidelink message and the hybrid automatic repeat request process identifier.

73. The non-transitory computer readable medium of claim 69, wherein: The instructions are further executable by the processor to: A sidelink grant is received from the second UE via the sidelink communication link, the sidelink grant indicating a set of resources for reverse sidelink transmission from the first UE to the second UE, wherein the reverse sidelink message is sent at least in part based on the sidelink grant.

74. The non-transitory computer readable medium of claim 69, wherein: The instructions are further executable by the processor to: An indication of a modulation and coding scheme associated with the reverse sidelink message is received via at least one of the first sidelink control information or the second sidelink control information, wherein the reverse sidelink message is sent at least in part based on the indication of the modulation and coding scheme.

75. The non-transitory computer readable medium of claim 69, wherein: The instructions are further executable by the processor to: An indication of a redundancy version associated with the reverse sidelink message is received via the second sidelink control information, wherein the reverse sidelink message is sent based at least in part on the indication of the redundancy version.

76. The non-transitory computer readable medium of claim 69, wherein: The instructions are further executable by the processor to: Third sidelink control information, fourth sidelink control information, or both are sent to the second UE, wherein the reverse sidelink message is sent at least in part based on the third sidelink control information, the fourth sidelink control information, or both.

77. A non-transitory computer-readable medium storing code for wireless communication at a first user equipment (UE), the code comprising instructions executable by a processor to: sending, via a physical sidelink control channel of the sidelink communication link, first sidelink control information including a reverse sidelink scheduling indicator to the second UE; sending second sidelink control information to the second UE via a physical sidelink shared channel of the sidelink communication link, the second sidelink control information indicating a set of resources used for reverse sidelink transmission from the second UE to the first UE over the sidelink communication link, The second sidelink control information is sent based at least in part on the first sidelink control information, the second sidelink control information being different from the first sidelink control information; as well as In response to the second sidelink control information, a reverse sidelink message is received from the second UE.

78. A non-transitory computer-readable medium storing code for wireless communication at a first user equipment (UE), the code comprising instructions executable by a processor to: receiving, from a second UE via a physical sidelink control channel of a sidelink communication link between the first UE and the second UE, first sidelink control information including a reverse sidelink scheduling indicator; receiving second sidelink control information from the second UE via a physical sidelink shared channel of the sidelink communication link, the second sidelink control information indicating a set of resources for reverse sidelink transmission from the first UE to the second UE over the sidelink communication link, The second sidelink control information is received based at least in part on the first sidelink control information, the second sidelink control information being different from the first sidelink control information; as well as In response to the second sidelink control information, a reverse sidelink message is sent to the second UE.

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