RECEIVER SIDE SENSING FOR SIDELINK INTER-UE-COORDINATION

Apparatus, methods, and computer-readable media for facilitating a SL communication for mode 2 resource allocation are disclosed herein. An example method includes performing sensing on one or more SL resources to identify a first set of available resources. The example method further includes adjusting a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold. The example method further includes transmitting a sidelink message indicating a second set of available resources based on the second measurement threshold.

INTRODUCTION

The present disclosure relates generally to communication systems, and more particularly, to wireless communication utilizing sidelink (SL) communication between user equipments (UEs).

BRIEF SUMMARY

In an aspect of the disclosure, a method of wireless communication at a first UE is provided. The method may include performing sensing on one or more SL resources to identify a first set of available resources. The example method may also include adjusting a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold. The example method may also include transmitting a sidelink message indicating a second set of available resources based on the second measurement threshold.

In another aspect of the disclosure, an apparatus for wireless communication is provided. The apparatus may be a UE that includes a memory and at least one processor coupled to the memory, the memory and the at least one processor configured to perform sensing on one or more SL resources to identify a first set of available resources. The memory and the at least one processor may also be configured to adjust a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold. The memory and the at least one processor may also be configured to transmit a sidelink message indicating a second set of available resources based on the second measurement threshold.

In another aspect of the disclosure, an apparatus for wireless communication at a wireless device is provided. The apparatus may include means for performing sensing on one or more SL resources to identify a first set of available resources. The example apparatus may also include means for adjusting a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold. The example apparatus may also include means for transmitting a sidelink message indicating a second set of available resources based on the second measurement threshold.

In another aspect of the disclosure, a non-transitory computer-readable storage medium storing computer executable code for wireless communication at a wireless device is provided. The code, when executed, may cause a processor to perform sensing on one or more SL resources to identify a first set of available resources. The example code, when executed, may also cause the processor to adjust a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold. The example code, when executed, may also cause the processor to transmit a sidelink message indicating a second set of available resources based on the second measurement threshold.

In an aspect of the disclosure, a method of wireless communication at a first UE is provided. The method may include performing a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication. The example method may also include transmitting a sidelink message including a resource availability report indicating a subset of the one or more available resources.

In another aspect of the disclosure, an apparatus for wireless communication is provided. The apparatus may be a first UE that includes a memory and at least one processor coupled to the memory, the memory and the at least one processor configured to perform a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication. The memory and the at least one processor may also be configured to transmit a sidelink message including a resource availability report indicating a subset of the one or more available resources.

In another aspect of the disclosure, an apparatus for wireless communication at a first UE is provided. The apparatus may include means for performing a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication. The example apparatus may also include means for transmitting a sidelink message including a resource availability report indicating a subset of the one or more available resources.

In another aspect of the disclosure, a non-transitory computer-readable storage medium storing computer executable code for wireless communication at a first UE is provided. The code, when executed, may cause a processor to perform a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication. The example code, when executed, may also cause the processor to transmit a sidelink message including a resource availability report indicating a subset of the one or more available resources.

DETAILED DESCRIPTION

Sidelink communication enables a first UE to communicate with another UE directly. Sidelink communication may be based on different types or modes of resource allocation mechanisms. In a first resource allocation mode (which may be referred to herein as “Mode 1”), centralized resource allocation may be provided by a network entity. In a second resource allocation mode (which may be referred to herein as “Mode 2”), distributed resource allocation may be provided. In Mode 2 resource allocation, each UE may autonomously determine resources to use for sidelink transmission. In order to coordinate the selection of sidelink resources by individual UEs, each UE may use a sensing technique to monitor for resource reservations by other sidelink UEs and may select resources for sidelink transmissions from unreserved resources. Devices communicating based on sidelink may determine one or more radio resources in the time and frequency domain that are reserved, or used, by other devices in order to avoid a selection of colliding (e.g., overlapping in time and/or frequency) transmission resources.

Thus, in the second mode (e.g., Mode 2), individual UEs may autonomously select resources for sidelink transmission, e.g., without a central entity such as a base station indicating the resources for the device. The UE may receive various types of information that may be used for sidelink resource selection. To reduce or avoid resource collisions under such instances, and to improve sidelink communication among UEs, the UEs may coordinate among themselves by generating and sharing inter-UE coordination information with other UEs. As an example, a first UE may generate inter-UE coordination information indicating preferred resources, non-preferred resources, or resource conflict information. A second UE may receive inter-UE coordination information from the first UE and may accordingly avoid using the non-preferred resources when communicating with the first UE. In some aspects, the second UE may include an inter-UE coordination information associated with the second UE based on reservation information (e.g., information indicating time and frequency resources reserved for a particular sidelink transmission) or inter-UE coordination information received from the first UE (or other UEs) when transmitting its own resource reservation.

As an example, a receiving UE may perform sensing, then inform the transmitting UE (along with other UEs) about the resources that are available for transmission based on the sensing result. For example, the receiving UE may be a smartphone with a higher processing power and higher battery capacity than the transmitting UE, which may be a smartwatch with limited battery capacity and limited processing power. In such an example, it may be more efficient to have the higher processing power receiving UE with higher battery capacity perform the sensing for the transmitting UE.

In some circumstances, based on the sensing, the receiving UE may identify a first set of available resources that may be smaller than a threshold amount of available resources (e.g., by comparing a size of the available resources with an availability threshold) for a transmission by the transmitting UE. Aspects provided herein enable a receiving UE to adjust one or more parameters, such as a measurement threshold, when identifying a set of available resources that may be suitable for a transmission by the transmitting UE. By enabling the receiving UE to adjust the parameters for identifying available resources, e.g., by adjusting a measurement threshold, the receiving UE may indicate a more consistent amount of available resources for the transmitting UE. The added consistency in the amount of available resources reported by the receiving UE may provide the transmitting UE with information of a set of available resources that may be more suitable for the transmission.

As used herein, the term “sensing” may refer to a procedure where a UE performs one or more measurements (which may be referred to as “sensing measurements”) to identify resources that are available for sidelink transmissions for the UE or another UE. By way of example, sensing measurements may include reference signal received power (RSRP) measurements, reference signal received quality (RSRQ) measurements, signal to interference ratio (SIR) measurements, or the like. A UE may compare sensing measurements associated with a resource with a threshold (which may be referred to as “measurement threshold”). If the sensing measurement associated with the resource is below the measurement threshold, the UE may determine that the resource is available. In another example, if the sensing measurement associated with the resource is above the measurement threshold, the UE may determine that the resource is available. As used herein, the term “inter-UE coordination information” may refer to information exchanged between sidelink UEs to facilitate sidelink communications under resource allocation Mode 2 where each UE may autonomously determine resources to use for sidelink transmission.

Some examples of sidelink communication may include vehicle-based communication devices that can communicate from vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) (e.g., from the vehicle-based communication device to road infrastructure nodes such as a Road Side Unit (RSU)), vehicle-to-network (V2N) (e.g., from the vehicle-based communication device to one or more network nodes, such as a base station), vehicle-to-pedestrian (V2P), cellular vehicle-to-everything (C-V2X), and/or a combination thereof and/or with other devices, which can be collectively referred to as vehicle-to-anything (V2X) communications. Sidelink communication may be based on V2X or other D2D communication, such as Proximity Services (ProSe), etc. In addition to UEs, sidelink communication may also be transmitted and received by other transmitting and receiving devices, such as Road Side Unit (RSU)107, etc. Sidelink communication may be exchanged using a PC5 interface, such as described in connection with the example inFIG.2. In some examples, an intermediary device (e.g., such as a base station102or180) may facilitate communication between an originating device (e.g., a first UE) and a target device (e.g., a second UE) using sidelink communication. For example, a base station may allocate resources for sidelink communication, in some examples. In other examples, the devices may communicate without assistance from an intermediary device.

Although the following description, including the example slot structure ofFIG.2, may provide examples for sidelink communication in connection with 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

Referring again toFIG.1, in some aspects, a sidelink communication device, such as the UE104, may be configured to manage one or more aspects of wireless communication by facilitating resource reservation for UEs applying a power saving mode. As an example, inFIG.1, the UE104may include a SL component198configured to perform sensing on one or more SL resources to identify a first set of available resources. The SL component198may also be configured to adjust a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold. The SL component198may also be configured to transmit a sidelink message indicating a second set of available resources based on the second measurement threshold. The SL component198may also be configured to perform a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication. The SL component198may also be configured to transmit a sidelink message including a resource availability report indicating a subset of the one or more available resources.

Although the following description provides examples directed to 5G NR (and, in particular, to sidelink communications via 5G NR), the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and/or other wireless technologies, in which wireless communication devices may employ power saving modes and perform resource reservations.

In some aspects, a base station102or180may be referred as a RAN and may include aggregated or disaggregated components. As an example of a disaggregated RAN, a base station may include a central unit (CU)106, one or more distributed units (DU)105, and/or one or more remote units (RU)109, as illustrated inFIG.1. A RAN may be disaggregated with a split between an RU109and an aggregated CU/DU. A RAN may be disaggregated with a split between the CU106, the DU105, and the RU109. A RAN may be disaggregated with a split between the CU106and an aggregated DU/RU. The CU106and the one or more DUs105may be connected via an F1 interface. A DU105and an RU109may be connected via a fronthaul interface. A connection between the CU106and a DU105may be referred to as a midhaul, and a connection between a DU105and an RU109may be referred to as a fronthaul. The connection between the CU106and the core network may be referred to as the backhaul. The RAN may be based on a functional split between various components of the RAN, e.g., between the CU106, the DU105, or the RU109. The CU may be configured to perform one or more aspects of a wireless communication protocol, e.g., handling one or more layers of a protocol stack, and the DU(s) may be configured to handle other aspects of the wireless communication protocol, e.g., other layers of the protocol stack. In different implementations, the split between the layers handled by the CU and the layers handled by the DU may occur at different layers of a protocol stack. As one, non-limiting example, a DU105may provide a logical node to host a radio link control (RLC) layer, a medium access control (MAC) layer, and at least a portion of a physical (PHY) layer based on the functional split. An RU may provide a logical node configured to host at least a portion of the PHY layer and radio frequency (RF) processing. A CU106may host higher layer functions, e.g., above the RLC layer, such as a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer. In other implementations, the split between the layer functions provided by the CU, DU, or RU may be different.

An access network may include one or more integrated access and backhaul (IAB) nodes111that exchange wireless communication with a UE104or other IAB node111to provide access and backhaul to a core network. In an IAB network of multiple IAB nodes, an anchor node may be referred to as an IAB donor. The IAB donor may be a base station102or180that provides access to a core network190or EPC160and/or control to one or more IAB nodes111. The IAB donor may include a CU106and a DU105. IAB nodes111may include a DU105and a mobile termination (MT). The DU105of an IAB node111may operate as a parent node, and the MT may operate as a child node.

The frequencies between FR1 and FR2 are often referred to as mid-band frequencies. Recent 5G NR studies have identified an operating band for these mid-band frequencies as 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 features of FR1 and/or FR2 into mid-band frequencies. In addition, higher frequency bands are currently being explored to extend 5GNR operation beyond 52.6 GHz. For example, three higher operating bands have been identified as 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.

FIG.2includes diagrams200and210illustrating example aspects of slot structures that may be used for sidelink communication (e.g., between UEs104, RSU107, etc.). The slot structure may be within a 5G/NR frame structure in some examples. In other examples, the slot structure may be within an LTE frame structure. Although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies. The example slot structure inFIG.2is merely one example, and other sidelink communication may have a different frame structure and/or different channels for sidelink communication. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. Each slot may include 14 or 12 symbols, depending on whether the cyclic prefix (CP) is normal or extended. For normal CP, each slot may include 14 symbols, and for extended CP, each slot may include 12 symbols. The symbols may be CP orthogonal frequency division multiplexing (OFDM) (CP-OFDM) symbols. The symbols may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as single carrier frequency-division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to a single stream transmission). The number of slots within a subframe is based on the CP and the numerology. The numerology defines the subcarrier spacing (SCS) and, effectively, the symbol length/duration, which is equal to ⅟SCS.

For normal CP (14 symbols/slot), different numerologies µ “0” to 4 allow for 1, 2, 4, 8, and 16 slots, respectively, per subframe. For extended CP, the numerology 2 allows for 4 slots per subframe. Accordingly, for normal CP and numerology µ, there are 14 symbols/slot and 2µslots/subframe. The subcarrier spacing may be equal to 2µ* 15 kHz, where µ is the numerology “0” to 4. As such, the numerology µ=0 has a subcarrier spacing of 15 kHz and the numerology µ=4 has a subcarrier spacing of 240 kHz. The symbol length/duration is inversely related to the subcarrier spacing.FIG.2provides an example of normal CP with 14 symbols per slot. Within a set of frames, there may be one or more different bandwidth parts (BWPs) that are frequency division multiplexed. Each BWP may have a particular numerology and CP (normal or extended).

Diagram200illustrates a single resource block of a single slot transmission, e.g., which may correspond to a 0.5 ms transmission time interval (TTI). A physical sidelink control channel may be configured to occupy multiple physical resource blocks (PRBs), e.g., 10, 12, 15, 20, or 25 PRBs. The PSCCH may be limited to a single sub-channel. A PSCCH duration may be configured to be 2 symbols or 3 symbols, for example. A sub-channel may comprise 10, 15, 20, 25, 50, 75, or 100 PRBs, for example. The resources for a sidelink transmission may be selected from a resource pool including one or more subchannels. As a non-limiting example, the resource pool may include between 1-27 subchannels. A PSCCH size may be established for a resource pool, e.g., as between 10-100 % of one subchannel for a duration of 2 symbols or 3 symbols. The diagram210inFIG.2illustrates an example in which the PSCCH occupies about 50% of a subchannel, as one example to illustrate the concept of PSCCH occupying a portion of a subchannel. The physical sidelink shared channel (PSSCH) occupies at least one subchannel. The PSCCH may include a first portion of sidelink control information (SCI), and the PSSCH may include a second portion of SCI in some examples.

A resource grid may be used to represent the frame structure. Each time slot may include a resource block (RB) (also referred to as physical RBs (PRBs)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme. As illustrated inFIG.2, some of the REs may include control information in PSCCH and some REs may include demodulation RS (DMRS). At least one symbol may be used for feedback.FIG.2illustrates examples with two symbols for a physical sidelink feedback channel (PSFCH) with adjacent gap symbols. A symbol prior to and/or after the feedback may be used for turnaround between reception of data and transmission of the feedback. The gap enables a device to switch from operating as a transmitting device to prepare to operate as a receiving device, e.g., in the following slot. Data may be transmitted in the remaining REs, as illustrated. The data may comprise the data message described herein. The position of any of the data, DMRS, SCI, feedback, gap symbols, and/or LBT symbols may be different than the example illustrated inFIG.2. Multiple slots may be aggregated together in some aspects.

FIG.3is a block diagram300of a first wireless communication device310in communication with a second wireless communication device350. The communication may be based on sidelink or an access link. In some examples, the wireless communication devices310,350may communicate based on V2X or other D2D communication. In other aspects, the wireless communication devices310,350may communicate over an access link based on uplink and downlink transmissions. The communication may be based on sidelink using a PC5 interface (e.g., between two UEs). The communication may be based on an access link using a Uu interface (e.g., between a base station and a UE). The wireless communication devices310,350may comprise a UE, an RSU, a base station, etc. In some implementations, the first wireless communication device310may correspond to a base station and the second wireless communication device350may correspond to a UE.

As shown inFIG.3, the first wireless communication device310includes a transmit processor (TX processor316), a transceiver318including a transmitter318aand a receiver318b, antennas320, a receive processor (RX processor370), a channel estimator374, a controller/processor375, and memory376. The example second wireless communication device350includes antennas352, a transceiver354including a transmitter354aand a receiver354b, an RX processor356, a channel estimator358, a controller/processor359, memory360, and a TX processor368. In other examples, the first wireless communication device310and/or the second wireless communication device350may include additional or alternative components.

Packets may be provided to the controller/processor375that implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer.

The controller/processor359can be associated with the memory360that stores program codes and data. The memory360may be referred to as a computer-readable medium. The controller/processor359may provide demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing. The controller/processor359is also responsible for error detection using an acknowledgment (ACK) and/or negative ACK (NACK) protocol to support hybrid automatic repeat request HARQ operations.

Channel estimates derived by the channel estimator358from a reference signal or feedback transmitted by the first wireless communication device310may be used by the TX processor368to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor368may be provided to different antenna352via separate transmitters354a. Each transmitter354amay modulate an RF carrier with a respective spatial stream for transmission.

The transmission is processed at the first wireless communication device310in a manner similar to that described in connection with the receiver function at the second wireless communication device350. Each receiver318breceives a signal through its respective antenna320. Each receiver318brecovers information modulated onto an RF carrier and provides the information to the RX processor370.

The controller/processor375can be associated with the memory376that stores program codes and data. The memory376may be referred to as a computer-readable medium. The controller/processor375provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing. The controller/processor375is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor368or the TX processor316, the RX processor356or the RX processor370, and the controller/processor359or the controller/processor375may be configured to perform aspects in connection with the SL component198ofFIG.1.

FIG.4illustrates an example400of sidelink communication between devices, as presented herein. The communication may be based on a slot structure including aspects described in connection withFIG.2or another sidelink structure. For example, a first UE402may transmit a sidelink transmission410, e.g., including a control channel (e.g., PSCCH) and/or a corresponding data channel (e.g., PSSCH), that may be received by a second UE406and/or a third UE408. The sidelink transmission410may be received directly from the first UE402, e.g., without being transmitting through a base station.

The first UE402, the second UE406, and/or the third UE408may each be capable of operating as a transmitting device in addition to operating as a receiving device. Thus, the second UE406is illustrated as transmitting a sidelink transmission412that is received by the first UE402. One or more of the sidelink transmissions410,412may be broadcast or multicast to nearby devices. For example, the first UE402may transmit communications intended for receipt by other UEs within a range401of the first UE402. In other examples, one or more of the sidelink transmissions410,412may be groupcast to nearby devices that are a member of a group. In other examples, one or more of the sidelink transmissions410,412may be unicast from one UE to another UE.

A sidelink transmission may provide sidelink control information (SCI) including information to facilitate decoding the corresponding data channel. For example, a transmitting device (sometimes referred to as an “originating device,” a “transmitting UE”, or an “originating UE”) may transmit SCI including information that a receiving device (sometimes referred to as a “target device,” a “receiving UE,” or a “target UE”) may use to avoid interference. For example, the SCI may indicate reserved time resources and/or reserved frequency resources that will be occupied by the data transmission, and may be indicated in a control message from the transmitting device. The number of TTIs, as well as the RBs that will be occupied by the data transmission, may be indicated in a control message from the first UE402. In some examples, the SCI may be used by a receiving device to avoid interference by refraining from transmitting on the occupied resources during a data transmission.

One or more of the first UE402, the second UE406, and/or the third UE408may include an SL component, similar to the SL component198described in connection withFIG.1.

Sidelink communication enables a first UE to communicate with another UE directly. For example, the first UE and the other UE may communicate without routing the communication through a base station. Sidelink may be beneficial for vehicle-based communications (e.g., V2V, V2I, V2N, V2P, C-V2X, etc.) that allows a vehicle UE to communicate directly with another UE or a pedestrian UE. When dealing with V2X communication, power consumption by the vehicle UE might not be a concern.

However, it may be beneficial to implement power saving modes for some devices. Two examples of power saving modes include partial sensing or random selection and discontinuous reception (DRX). In either DRX or partial sensing, the UE may skip sensing for resource reservations for portions of time. The skipped sensing may save battery power at the UE, for example.

Sidelink communication may be based on different types or modes of resource allocation mechanisms. In a first resource allocation mode (which may be referred to herein as “Mode 1”), centralized resource allocation may be provided by a network entity. For example, and referring to the example ofFIG.1, a base station102/180may determine resources for sidelink communication and may allocate resources to different UEs to use for sidelink transmissions. In this first mode, a UE receives the allocation of sidelink resources from the base station102/180. In a second resource allocation mode (which may be referred to herein as “Mode 2”), distributed resource allocation may be provided. In Mode 2, each UE may autonomously determine resources to use for sidelink transmission. In order to coordinate the selection of sidelink resources by individual UEs, each UE may use a sensing technique to monitor for resource reservations by other sidelink UEs and may select resources for sidelink transmissions from unreserved resources. Devices communicating based on sidelink may determine one or more radio resources in the time and frequency domain that are used by other devices in order to select transmission resources that avoid collisions with other devices. The sidelink transmission and/or the resource reservation may be periodic or aperiodic, where a UE may reserve resources for transmission in a current slot and up to two future slots.

Thus, in the second mode (e.g., Mode 2), individual UEs may autonomously select resources for sidelink transmission, e.g., without a central entity such as a base station indicating the resources for the device. A first UE may reserve the selected resources in order to inform other UEs about the resources that the first UE intends to use for sidelink transmission(s).

In some examples, the resource selection for sidelink communication may be based on a sensing-based mechanism. For instance, before selecting a resource for a data transmission, a UE may first determine whether resources have been reserved by other UEs.

For example, as part of a sensing mechanism for resource allocation Mode 2, the UE may determine (e.g., sense) whether a selected sidelink resource has been reserved by other UE(s) before selecting the sidelink resource for a data transmission. If the UE determines that the sidelink resource has not been reserved by other UEs, the UE may use the selected sidelink resource for transmitting the data, e.g., in a PSSCH transmission. The UE may estimate or determine which radio resources (e.g., sidelink resources) may be in-use and/or reserved by others by detecting and decoding sidelink control information (SCI) transmitted by other UEs. The UE may use a sensing-based resource selection algorithm to estimate or determine which radio resources are in-use and/or reserved by others. The UE may receive SCI from another UE that includes reservation information based on a resource reservation field included in the SCI. The UE may continuously monitor for (e.g., sense) and decode SCI from peer UEs. The SCI may include reservation information, e.g., indicating slots and RBs that a particular UE has selected for a future transmission. The UE may exclude resources that are used and/or reserved by other UEs from a set of candidate resources for sidelink transmission by the UE, and the UE may select/reserve resources for a sidelink transmission from the resources that are unused and therefore form the set of candidate resources. The UE may continuously perform sensing for SCI with resource reservations in order to maintain a set of candidate resources from which the UE may select one or more resources for a sidelink transmission. Once the UE selects a candidate resource, the UE may transmit SCI indicating its own reservation of the resource for a sidelink transmission. The number of resources (e.g., sub-channels per subframe) reserved by the UE may depend on the size of data to be transmitted by the UE. Although the example is described for a UE receiving reservations from another UE, the reservations may also be received from an RSU or other device communicating based on sidelink.

FIG.5is an example500of time and frequency resources showing reservations for sidelink transmissions, as presented herein. The resources may be included in a sidelink resource pool, for example. The resource allocation for each UE may be in units of one or more sub-channels in the frequency domain (e.g., sub-channels SC1 to SC 4), and may be based on one slot in the time domain (e.g., slots “1” to 8). The UE may also use resources in the current slot to perform an initial transmission, and may reserve resources in future slots for retransmissions. In the illustrated example ofFIG.5, two different future slots are being reserved by UE1 and UE2 for retransmissions. The resource reservation may be limited to a window of a pre-defined slots and sub-channels, such as an 8 time slots by 4 sub-channels window as shown in example500, which provides 32 available resource blocks in total. This window may also be referred to as a resource selection window.

A first UE (“UE1) may reserve a sub-channel (e.g., SC 1) in a current slot (e.g., slot 1) for its initial data transmission502, and may reserve additional future slots within the window for data retransmissions (e.g., a first data retransmission504and a second data retransmission506). For example, the first UE may reserve sub-channels SC 3 at slot 3 and SC 2 at slot 4 for future retransmissions as shown byFIG.5. The first UE then transmits information regarding which resources are being used and/or reserved by it to other UE(s). The first UE may do so by including the reservation information in a reservation resource field of the SCI, e.g., a first stage SCI.

FIG.5illustrates that a second UE (“UE2”) reserves resources in sub-channels SC 3 and SC 4 at slot “1” for a current data transmission508, reserves a first data retransmission510at slot 4 using sub-channels SC 3 and SC 4, and reserves a second data retransmission512at slot 7 using sub-channels SC “1” and SC 2, as shown byFIG.5. Similarly, the second UE may transmit the resource usage and reservation information to other UE(s), such as using the reservation resource field in SCI.

A third UE may consider resources reserved by other UEs within the resource selection window to select resources to transmit its data. The third UE may first decode SCIs within a time period to identify which resources are available (e.g., candidate resources). For example, the third UE may exclude the resources reserved by UE1 and UE2 and may select other available sub-channels and time slots from the candidate resources for its transmission and retransmissions, which may be based on a number of adjacent sub-channels in which the data (e.g., packet) to be transmitted can fit.

WhileFIG.5illustrates resources being reserved for an initial transmission and two retransmissions, the reservation may be for an initial transmission and a single transmission or only for an initial transmission.

The UE may determine an associated signal measurement (such as RSRP) for each resource reservation received by another UE. The UE may consider resources reserved in a transmission for which the UE measures an RSRP below a threshold to be available for use by the UE. A UE may perform signal/channel measurement for a sidelink resource that has been reserved and/or used by other UE(s), such as by measuring the RSRP of the message (e.g., the SCI) that reserves the sidelink resource. Based at least in part on the signal/channel measurement, the UE may consider using/reusing the sidelink resource that has been reserved by other UE(s). For example, the UE may exclude the reserved resources from a candidate resource set if the measured RSRP meets or exceeds the threshold, and the UE may consider a reserved resource to be available if the measured RSRP for the message reserving the resource is below the threshold. The UE may include the resources in the candidate resources set and may use/reuse such reserved resources when the message reserving the resources has an RSRP below the threshold, because the low RSRP indicates that the other UE is distant and a reuse of the resources is less likely to cause interference to that UE. A higher RSRP indicates that the transmitting UE that reserved the resources is potentially closer to the UE and may experience higher levels of interference if the UE selected the same resources.

For example, the UE may determine a set of candidate resources (e.g., by monitoring SCI from other UEs and removing resources from the set of candidate resources that are reserved by other UEs in a signal for which the UE measures an RSRP above a threshold value). The UE may also select N resources for transmissions and/or retransmissions of a TB. As an example, the UE may randomly select the N resources from the set of candidate resources previously determined. For each transmission, the UE may reserve future time and frequency resources for an initial transmission and up to two retransmissions. The UE may reserve the resources by transmitting SCI indicating the resource reservation. For example, in the example inFIG.5, the second UE may transmit SCI reserving resources for the current data transmission508, the first data retransmission510, and the second data retransmission512.

There may be a timeline for a sensing-based resource selection. For example, the UE may sense and decode the SCI received from other UEs during a sensing window, e.g., a time duration prior to resource selection. Based on the sensing history during the sensing window, the UE may be able to maintain a set of available candidate resources by excluding resources that are reserved by other UEs from the set of candidate resources. A UE may select resources from its set of available candidate resources and transmits SCI reserving the selected resources for sidelink transmission (e.g., a PSSCH transmission) by the UE. There may be a time gap between the UE’s selection of the resources and the UE transmitting SCI reserving the resources.

In the resource allocation Mode 2, a higher layer may request the UE104that includes the SL component198to determine a subset of resources from which the higher layer may select resources for PSSCH/PSCCH transmissions.FIG.6illustrates an example timing diagram600for a UE that may be triggered to select a resource for sidelink transmission in response to a resource selection trigger650. The timing diagram shows a timing for sensing for resource reservations from other UEs, such as the resource reservations described in connection withFIG.5. As an example, the resource selection trigger650may include having data for transmission. AlthoughFIG.6is described in connection with a UE, the resource selection may also be applied by other sidelink devices. In response to the resource selection trigger650, the UE may consider signals received within a sensing window602of duration T_0 and determine information (e.g., SCI with resource reservations) received within the sensing window602. For example, the UE may determine which resources were used by other UE(s) or reserved by other UE(s) during the sensing window602. The UE may anticipate that the previously used resources may also be used by the other UE in the future. A signal received in the sensing window may include SCI indicating a resource reservation for a resource within the resource selection window604following the resource selection trigger650. Based on the past use of resources and/or the reservation of resources (e.g., the “sensing” of resources), the UE may determine which resources are scheduled for use and/or determine which resources are not scheduled for use. For example, based on the sensing of the resources during the sensing window602, the UE may determine that a first resource606and a second resource608may be reserved during the slot associated with the resource selection trigger650and/or during a future slot. The UE may exclude candidate resources that are reserved by other UEs from a candidate set of resources when selecting a sidelink transmission resource. In some examples, the UE may exclude candidate resources that are reserved by another UE and that meet one or more conditions, such as the reservation signal meeting an RSRP threshold. The UE may select resource610for a transmission.

In some wireless communication systems, a receiving UE may perform sensing, then inform the transmitting UE (along with other UEs) about the resources that are available for transmission based on the sensing result. For example, the receiving UE may be a smartphone with a higher processing power and higher battery capacity than the transmitting UE, which may be a smartwatch with limited battery capacity and limited processing power. Therefore, it may be more efficient to have the higher processing power with higher battery capacity receiving UE to perform the sensing for the transmitting UE.

In some instances, multiple UEs may transmit at the same time and may not receive the overlapping communication (e.g., SCI indicating resource reservations) from each other and/or from a base station. Such a UE may miss or be unaware of transmissions and sidelink reservations by other UEs. Therefore, two UEs may reserve the same resource block for a future sidelink transmission, which may result in a resource collision. A resource collision occurs for sidelink transmissions that overlap at least partially in time, and which may overlap, at least partially, in frequency.

To reduce or avoid resource collisions under such instances, and to improve sidelink communication among UEs, the UEs may coordinate among themselves by generating and sharing inter-UE coordination information with other UEs.FIG.7Ais a diagram700illustrating the exchange of inter-UE coordination information, where a first UE (“UE-A”)712transmits inter-UE coordination information716to a second UE (“UE-B″)714. In some aspects, the transmission of inter-UE coordination information may include resource reservation forwarding by the UE-A.

The inter-UE coordination information716may include information based on the UE’s sensing information (e.g., resource reservations of other UEs that are sensed by UE712(e.g., UE-A)), inter-UE coordination information from another UE, resources that are bad, undesirable, or non-preferred for the UE-A712(e.g., resources subject to high interference), resources which are preferred or better than other resources for the UE-A712, etc.

The inter-UE coordination information716may indicate candidate resources for sidelink transmission or preferred resources for transmissions by UE-B714. In some aspects, the indication of preferred resources for UE-B’s transmission may be referred to as “Type A” inter-UE coordination information. The UE-A712may use the inter-UE coordination information716to inform the UE-B714about which sub-channels and slots may be used for communicating with the UE-A712and/or which sub-channels and slots may not be used because they are occupied or reserved by the UE-A712and/or other UEs. The UE-A may indicate a set of resources that may be more suitable for UE-B’s transmission based on UE-A’s evaluation. The candidate resources may indicate a group of resources from which the UE-B714(e.g., UE-B) may select for the sidelink transmission718. As illustrated, the sidelink transmission718may be for UE-A712or for one or more different UEs, e.g., UE-C719. In some aspects, the UE-A may be a potential receiver of the UE-B’s transmission, and the inter-UE coordination information may enable mode 2 resource allocation that is based on resource availability from a potential receiver’s perspective, which may address reception challenges for a hidden node. In some aspects, the inter-UE coordination information716may indicate resources for a sidelink transmission, e.g., particular resources on which the UE-B714is to transmit the sidelink transmission718rather than candidate resources that the UE-B714may select.

In some aspects, the inter-UE coordination information716may indicate a set of resources that may not be preferred for UE-B’s transmission, such as resources that may not be available for UE-B to transmit a sidelink transmission based on the UE-A’s evaluation. In some aspects, the indication of non-preferred resources for UE-B’s transmission may be referred to as “Type B” inter-UE coordination information.

In some aspects, the inter-UE coordination information716may indicate a half-duplex conflict. For example, the inter-UE coordination information716may indicate a collision in time and/or frequency for two transmitting UEs that are unable to receive the other, respective transmission in a half-duplex mode. In some aspects, the inter-UE coordination information716may indicate a collision of resources (e.g., reserved resources) in time and/or frequency. In some aspects, the indication of a collision/conflict in resources may be referred to as “Type C” inter-UE coordination information.

Based at least in part on the inter-UE coordination information716from the UE-A712, the UE-B704may make a better decision on which resources to use and/or reserve for its sidelink transmission718to avoid resource collisions. The UE-A712may share its inter-UE coordination information716with multiple UEs, and the UE-B714may receive the inter-UE coordination information716from multiple UEs. Inter-UE coordination information716may be transmitted in any of various ways.

The UE-A712may transmit inter-UE coordination information716in a PSFCH, e.g., indicating a resource collision or a half-duplex conflict indication. The UE-A712may transmit inter-UE coordination information716in SCI. For example, the UE-A712may transmit shared sensing information, candidate resource information for a sidelink transmission, or particular resources for a sidelink transmission in SCI-2 transmitted in PSSCH. For example, a first portion of SCI (e.g., SCI-1) may be transmitted in PSCCH, and a second portion of SCI (e.g., SCI-2) may be transmitted in PSSCH. The UE-A712may transmit inter-UE coordination information716in a MAC-CE, e.g., on the PSSCH. The UE-A712may transmit the inter-UE coordination information716in a new physical channel (e.g., that is different than PSCCH, PSSCH, PSFCH, etc.). For example, the UE-A712may transmit the inter-UE coordination information716in a physical channel that is configured for or dedicated to inter-UE configuration information. The UE-A712may transmit the inter-UE coordination information716in RRC signaling.

In some aspects, the UE-A712may transmit the inter-UE coordination information716periodically. In some aspects, the UE-A712may transmit aperiodic inter-UE coordination information716in response to a trigger. Among other examples, the trigger may be based on the occurrence of an event, such as the occurrence of/detection of a resource collision, the occurrence of/detection of a half-duplex conflict, etc. For example, if the UE-A712detects a resource collision, the UE-A712may respond by transmitting inter-UE coordination information716.

The UE-B714may utilize the inter-UE coordination information716in various ways.

If the inter-UE coordination information716includes information about resources that are preferred for transmissions of the UE-B714and/or resources that are not preferred for transmissions of the UE-B714, the UE-B704may select resource(s) to be used for its sidelink transmission resource selection, or resource re-selection, may be based on both UE-B’s sensing result (if available) and the received inter-UE coordination information716according to a first option. In a second option, the UE-B714may select resource(s) to be used for its sidelink transmission resource selection, or resource re-selection, may be based on the received inter-UE coordination information716and not based on sensing. In a third option, the UE-B714may select resource(s) to be used for its sidelink transmission resource selection, or resource re-selection, may be based on the received inter-UE coordination information716(which may allow the UE-B to use or not use sensing in combination with the inter-UE coordination information716).

FIG.7Bis a diagram750illustrating the exchange of inter UE coordination information that a UE702may provide to multiple UEs. As illustrated inFIG.7B, the UE702may be more capable of performing sensing in comparison with the UE704, the UE706, or the UE708. For example, the UE702, which may be a receiving UE that receives a transmission from the UE704, the UE706, or the UE708) may have a higher processing power and/or higher battery capacity than the UE704, the UE706, or the UE708. Therefore, it may be more efficient for the higher battery capacity/processing power UE702to perform sensing and transmit (e.g., groupcast) resource availability information722to the UE704, the UE706, and the UE708. Moreover, the UE702may have information about the UE704, the UE706, and the UE708based on measuring RSRP of signals on incoming links. For example, the UE702may be able to measure RSRP on a link between the UE702and the UE704, a link between the UE702and the UE706, and a link between the UE702and the UE708. By measuring the different links, the UE702may be able to better identify resources that are available.

In some circumstances, based on the sensing, the receiving UE702may identify a first set of available resources that may be smaller than a threshold amount of resources (e.g., determined to be unsuitably small by comparing a size of the available resources with an availability threshold) for the transmission724from the UE704to the UE702. Aspects provided herein enable a receiving UE to re-evaluate a set of available resources that may be suitable for a sidelink transmission by adjusting a measurement threshold, resulting in more consistent amount of available resources identified in inter-UE coordination information.

FIG.8is an example diagram800illustrating a communication flow between UEs including the transmission of inter-UE coordination information, in accordance with the aspects presented herein. Both the UE802and the UE804inFIG.8may be operating under sidelink resource allocation Mode 2. The UE802inFIG.8may correspond with the UE-A712inFIG.7Aand/or the UE702inFIG.7Band the UE804inFIG.8may correspond with the UE-B714inFIG.7Aand/or the UE704inFIG.7B. In some aspects, the UE802may have a higher processing power and/or a higher battery capacity than the UE804. The UE802may perform sensing (e.g., as described in connection withFIGS.5and6) to identify resources that are available for the UE804, at810. In some aspects, the UE802may generate a resource availability report812that the UE802transmits to other UEs. A resource availability report may refer to a set of information representing availability of each of one or more resources. As one example, each “0” represented in the resource availability report812may indicate that a resource mapped to the “0” is unavailable for the UE804and each “1” represented in the resource availability report812may indicate that a resource mapped to the “1” is available for the UE804. Although the example is illustrated for a single UE receiving the availability report812, which may occur as a unicast, the UE802may similarly broadcast or groupcast the availability report812to multiple UEs, in some aspects. As part of the sensing, at810, the UE802may perform one or more sensing measurements, such as SIR measurements, RSRP measurements, RSRQ measurements, or the like. The UE802may compare a result of the sensing measurement on each of the resources to a measurement threshold. In some aspects, if the result of the sensing measurement on the resource is below than the measurement threshold, the UE802may determine that resource to be available for UE804. If the result of the sensing measurement on the resource is not below the measurement threshold, the UE802may determine that resource to be unavailable for UE804. In some aspects, if the result of the sensing measurement on the resource is above than the measurement threshold, the UE802may determine that resource to be available for UE804. If the result of the sensing measurement on the resource is not above the measurement threshold, the UE802may determine that resource to be unavailable for UE804.

In some aspects, the measurement threshold may be associated with (e.g., may be a function of) one or more priorities of a packet associated with an associated transmission (such as the transmission824) of the UE804. In some aspects, the measurement threshold may be associated with (e.g., may be a function of) one or more modulation and coding scheme (MCS) associated with the UE804.

In some aspects, the UE802may determine that the identified available resources identified at810(such as the resources indicated as available in the resource availability report812) may be unsuitably small for the UE804. For example, the UE802may determine that the identified available resources identified at810may be unsuitably small for the UE804by comparing a size of the available resources to an availability threshold. In some aspects, the size of the available resources and the availability threshold may be defined in terms of a total number of resources. In some aspects, the size of the available resources and the availability threshold may be defined in terms of a percentage compared with the resources that are being sensed. For example, the availability threshold may be 50%, and the UE802may determine the size of the available resources to be unsuitably small for UE804if the available resources are below 50% of the total amount of resources in the resource selection window. Upon determining the size of the available resources to be unsuitably small, the UE802may, at814, adjust a measurement threshold and re-identify available resources based on the adjusted measurement threshold. For example, the UE802may decrease a SIR threshold by a number of decibels (dBs), and then re-identify available resources based on the new SIR threshold by comparing SIR associated with the resources with the new SIR threshold. For each resource, if the SIR associated with the resource is above the SIR threshold, the resource may be determined by the UE802to be available for the UE804. In some aspects, the UE802may keep adjusting the measurement threshold and re-identify available resources based on the adjusted measurement threshold until a maximum allowed/minimum allowed measurement threshold is reached, or until the amount of available resources reach the availability threshold. As one example, the UE802may generate a resource availability report816. In some aspects, each “0” in the resource availability report816may indicate that a resource mapped to the “0” is unavailable for the UE804and each “1” in the resource availability report816may indicate that a resource mapped to the “1” is available for the UE804. As illustrated inFIG.8, a size of the resources indicated as available in the resource availability report816may be above the availability threshold of 50% because more than 50% of the resources are available.

In some aspects, the UE802may sort each of the available resources in a descending starting from the resource associated with a measurement furthest away from the measurement threshold. For example, the UE may sort all resources that have higher SIR than the SIR threshold in descending order of SIR level.

In some aspects, the UE802may provide a resource availability report818to the UE804. In some aspects, the resource availability report818may include the resource availability report816. In some aspects, the resource availability report818may include a report that sorts top X % available resources in a descending starting from the resource associated with a measurement furthest away from the measurement threshold. In some aspects, X may be defined based on an availability threshold or a different threshold. The UE may adjust the measurement threshold until a report that X% of available resources may be identified or until a maximum allowed/minimum allowed measurement threshold is reached.

In some aspects, the UE802may also schedule one or more resources for the UE804by transmitting a resource reservation820to one or more UEs. In some aspects, the UE802may not schedule the one or more resources for the UE804. In some aspects, upon receiving the resource availability report818, the UE804may select one or more resources that are indicated as available in the resource availability report818for a transmission824to the UE802. In some aspects, as illustrated in822ofFIG.8, the UE804may select (denoted by “S”) one or more resources indicated as being available in the resource availability report818. The UE804may use the one or more selected resources to transmit the transmission824to the UE802.

FIG.9is a flowchart900of a method of wireless communication. The method may be performed by a UE (e.g., the UE104, the UE702, the UE802; the apparatus1302). The method may enable a receiving UE to re-identify a first set of available resources that may be suitable for the transmission of the transmitting UE by adjusting a measurement threshold, resulting in more efficient sidelink transmissions.

At902, the UE may perform sensing on one or more SL resources to identify a first set of available resources. For example, the UE802may perform sensing on one or more SL resources to identify a first set of available resources at810. In some aspects,902may be performed by sensing component1342inFIG.13.

At904, the UE may adjust a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold. For example, the UE802may adjust a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold at814. In some aspects,904may be performed by availability component1344inFIG.13. For example, the size may be defined based on a percentage relative to the one or more SL resources. As one example, if 50% of resources are available in the one or more SL resources, the size of the first set of available resources may be 50%.

At906, the UE may transmit a sidelink message indicating a second set of available resources based on the second measurement threshold. For example, the UE802may transmit a sidelink message indicating a second set of available resources (e.g., the resource availability report818) that are available based on the second measurement threshold. In some aspects,906may be performed by SL component1346inFIG.13.

FIG.10is a flowchart1000of a method of wireless communication. The method may be performed by a UE (e.g., the UE104, the UE702, the UE802; the apparatus1302). The method may enable a receiving UE to re-identify a first set of available resources that may be suitable for the transmission of the transmitting UE by adjusting a measurement threshold, resulting in more efficient sidelink transmissions.

At1002, the UE may perform sensing on one or more SL resources to identify a first set of available resources. For example, the UE802may perform sensing on one or more SL resources to identify a first set of available resources at810. In some aspects,1002may be performed by sensing component1342inFIG.13.

At1004, the UE may adjust a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold. For example, the UE802may adjust a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold at814. In some aspects,1004may be performed by availability component1344inFIG.13. In some aspects, the availability threshold may include a percentage of available resources from the one or more SL resources. For example, the size may be defined based on a percentage relative to the one or more SL resources. As one example, if 50% of resources are available in the one or more SL resources, the size of the first set of available resources may be 50%. In some aspects, the availability threshold may include a size of available resources from the one or more SL resources. In some aspects, the first measurement threshold is a first SIR ratio value, and the measurement second threshold is a second SIR ratio value. As one example, the first SIR ratio value may be lower or higher than the second SIR ratio value. In some aspects, the first SIR ratio value or the second SIR ratio value may be based on a function of one or more of a priority associated with a sidelink communication associated with a second UE based on the sensing or a MCS associated with the second UE. In some aspects, the first measurement threshold may be a first RSRQ threshold, and the second measurement threshold may be a second RSRQ threshold. The first RSRQ threshold may be lower or higher than the second RSRQ threshold. In some aspects, the second measurement threshold may be based on one or more of: a packet priority associated with a sidelink communication associated with a second UE, a MCS associated with the second UE, a cast type associated with the second UE, a remaining packet delay budget associated with the sidelink communication associated with the second UE, a communication range specification associated with the second UE, a HARQ ACK utilization status associated with the sidelink communication associated with the second UE, a channel busy ratio (CBR), or a distance between the UE and the second UE.

At1006, the UE may transmit a sidelink message indicating a second set of available resources based on the second measurement threshold. For example, the UE802may transmit a sidelink message indicating a second set of available resources (e.g., the resource availability report818) that are available based on the second measurement threshold. In some aspects,1006may be performed by SL component1346inFIG.13. In some aspects, the second set of resources may be indicated in a resource availability report including a list of each resource in the second set of available resources based on the sensing. In some aspects, the second set of resources is indicated in a resource availability report including a top percentage of available resources based on the second measurement threshold.

In some aspects, at1008, the UE may schedule at least one available resource of the second set of available resources for a second UE. For example, the UE802may schedule at least one available resource of the second set of available resources for a second UE804by transmitting a reservation820. The at least one available resource of the second set of available resources for a second UE may be used by the second UE to transmit a transmission to the UE, such as the transmission824. In some aspects, the UE may not schedule the at least one available resource of the second set of available resources for the second UE. In some aspects,1008may be performed by SL component1346inFIG.13.

In some aspects, at1010, the UE may receive, from a second UE, a sidelink communication based on the sensing and carried by at least one available resource of the second set of available resources. For example, the UE802may receive, from a second UE804, a sidelink communication (e.g., the transmission824) based on the sensing and carried by at least one available resource of the second set of available resources.

FIG.11is a flowchart1100of a method of wireless communication. The method may be performed by a UE (e.g., the UE104, the UE702, the UE802; the apparatus1302). The method may enable a receiving UE to re-identify a first set of available resources that may be suitable for the transmission of the transmitting UE by adjusting a measurement threshold, resulting in more efficient sidelink transmissions.

At1102, the UE may perform a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication. For example, the UE802may perform a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication at810. In some aspects,1102may be performed by sensing component1342inFIG.13.

At1104, the UE may transmit a sidelink message including a resource availability report indicating a subset of the one or more available resources. For example, the UE802may transmit a sidelink message including a resource availability report indicating a subset of the one or more available resources (e.g., the resource availability report818). In some aspects,1104may be performed by SL component1346inFIG.13.

FIG.12is a flowchart1200of a method of wireless communication. The method may be performed by a UE (e.g., the UE104, the UE702, the UE802; the apparatus1302). The method may enable a receiving UE to re-identify a first set of available resources that may be suitable for the transmission of the transmitting UE by adjusting a measurement threshold, resulting in more efficient sidelink transmissions.

At1202, the UE may perform a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication. For example, the UE802may perform a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication at810. In some aspects,1202may be performed by sensing component1342inFIG.13.

At1204, the UE may rank the one or more available resources based on the sensing measurement. The subset of the one or more available resources may correspond to a fraction of the one or more available resources having a lowest or highest sensing measurement. For example, the UE802may rank the one or more available resources based on the sensing measurement. In some aspects,1204may be performed by availability component1344inFIG.13.

At1206, the UE may adjust a threshold for the sensing measurement based on a first set of available resources being below an availability threshold and further based on one or more of: a packet priority associated with a sidelink communication associated with a second UE, a MCS associated with the second UE, a cast type associated with the second UE, a remaining packet delay budget associated with the sidelink communication associated with the second UE, a communication range specification associated with the second UE, a HARQ ACK utilization status associated with the sidelink communication associated with the second UE, a CBR, or a distance between the UE and the second UE. For example, the UE802may adjust a measuremenbt threshold at814. In some aspects,1206may be performed by availability component1344inFIG.13.

At1208, the UE may transmit a sidelink message including a resource availability report indicating a subset of the one or more available resources. For example, the UE802may transmit a sidelink message including a resource availability report indicating a subset of the one or more available resources (e.g., the resource availability report818). In some aspects,1208may be performed by SL component1346inFIG.13. In some aspects, the subset corresponds to a percentage value of the one or more available resources of the one or more SL resources. In some aspects, the resource availability report indicates a ranking of each resource in the subset of the one or more available resources.

FIG.13is a diagram1300illustrating an example of a hardware implementation for an apparatus1302. The apparatus1302may be a UE, a component of a UE, or may implement UE functionality. In some aspects, the apparatus1302may include a cellular baseband processor1304(also referred to as a modem) coupled to a cellular RF transceiver1322. In some aspects, the apparatus1302may further include one or more subscriber identity modules (SIM) cards1320, an application processor1306coupled to a secure digital (SD) card1308and a screen1310, a Bluetooth module1312, a wireless local area network (WLAN) module1314, a Global Positioning System (GPS) module1316, or a power supply1318. The cellular baseband processor1304communicates through the cellular RF transceiver1322with the UE104and/or BS102/180. The cellular baseband processor1304may include a computer-readable medium / memory. The computer-readable medium / memory may be non-transitory. The cellular baseband processor1304is responsible for general processing, including the execution of software stored on the computer-readable medium / memory. The software, when executed by the cellular baseband processor1304, causes the cellular baseband processor1304to perform the various functions described supra. The computer-readable medium / memory may also be used for storing data that is manipulated by the cellular baseband processor1304when executing software. The cellular baseband processor1304further includes a reception component1330, a communication manager1332, and a transmission component1334. The communication manager1332includes the one or more illustrated components. The components within the communication manager1332may be stored in the computer-readable medium / memory and/or configured as hardware within the cellular baseband processor1304. The cellular baseband processor1304may be a component of the UE350and may include the memory360and/or at least one of the TX processor368, the RX processor356, and the controller/processor359. In one configuration, the apparatus1302may be a modem chip and include just the baseband processor1304, and in another configuration, the apparatus1302may be the entire UE (e.g., see350ofFIG.3) and include the additional modules of the apparatus1302.

The communication manager1332may include a sensing component1342that is configured to perform sensing on one or more SL resources to identify a first set of available resources or perform a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication, e.g., as described in connection with902inFIG.9,1002inFIG.10,1102inFIG.11,or1202inFIG.12.

The communication manager1332may further include an availability component1344that may be configured to adjust a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold, rank the one or more available resources based on the sensing measurement, or adjust a measurement threshold, e.g., as described in connection with904inFIG.9,1004inFIG.10,or1204and1206inFIG.12.

The communication manager1332may further include an SL component1346that may be configured to transmit a sidelink message indicating a second set of available resources based on the second measurement threshold, schedule the at least one available resource of the second set of available resources for a second UE, receive, from a second UE, a sidelink communication based on the sensing and carried by at least one available resource of the second set of available resources, or transmit a sidelink message including a resource availability report indicating a subset of the one or more available resources, e.g., as described in connection with906inFIG.9,1006,1008or1010inFIG.10,1104inFIG.11,or1208inFIG.12.

As shown, the apparatus1302may include a variety of components configured for various functions. In one configuration, the apparatus1302, and in particular the cellular baseband processor1304, may include means for performing sensing on one or more of SL resources to identify a set of available resources, such as the sensing component1342or a transceiver. The cellular baseband processor1304may further include means for increasing a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold, such as the availability component1344. The cellular baseband processor1304may further include means for transmitting a sidelink message indicating a second set of available resources based on the second measurement threshold, such as the SL component1346or a transceiver. The cellular baseband processor1304may further include means for receiving, from a second UE, a sidelink communication based on the sensing and carried by at least one available resource of the second set of available resources, such as the SL component1346or a transceiver. The cellular baseband processor1304may further include means for scheduling the at least one available resource of the second set of available resources for a second UE, such as the SL component1346or a transceiver. The cellular baseband processor1304may further include means for performing a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication, such as the sensing component1342or a transceiver. The cellular baseband processor1304may further include means for ranking the one or more available resources based on the sensing measurement, such as the availability component1344. The cellular baseband processor1304may further include means for adjusting a measurement threshold, such as the availability component1344. The cellular baseband processor1304may further include means for transmitting a sidelink message including a resource availability report indicating a subset of the one or more available resources, such as the SL component1346or a transceiver. The means may be one or more of the components of the apparatus1302configured to perform the functions recited by the means. As described supra, the apparatus1302may include the TX Processor368, the RX Processor356, and the controller/processor359. As such, in one configuration, the means may be the TX Processor368, the RX Processor356, and the controller/processor359configured to perform the functions recited by the means.

Aspect 1 is an apparatus for wireless communication at a first UE, comprising: a memory; and at least one processor coupled to the memory, the memory and the at least one processor configured to: perform sensing on one or more SL resources to identify a first set of available resources; adjust a first measurement threshold to a second measurement threshold based on a size of the first set of available resources being below an availability threshold; and transmit a sidelink message indicating a second set of available resources based on the second measurement threshold.

Aspect 2 is the apparatus of aspect 1, wherein the at least one processor and the memory are further configured to: receive, from a second UE, a sidelink communication and carried by at least one available resource of the second set of available resources.

Aspect 3 is the apparatus of any of aspects 1-2, wherein the at least one processor coupled to the memory are further configured to: schedule the at least one available resource of the second set of available resources for the second UE.

Aspect 4 is the apparatus of any of aspects 1-3, wherein the first measurement threshold is a first SIR ratio value, and wherein the second measurement threshold is a second SIR ratio value, the first SIR ratio value being higher than the second SIR ratio value.

Aspect 5 is the apparatus of any of aspects 1-4, wherein the first SIR ratio value or the second SIR ratio value is based on a function of one or more of: a priority associated with a sidelink communication associated with a second UE or a MCS associated with the second UE.

Aspect 6 is the apparatus of any of aspects 1-5, wherein the first measurement threshold is a first RSRQ threshold, and wherein the second measurement threshold is a second RSRQ threshold, the first RSRQ threshold being higher than the second RSRQ threshold.

Aspect 7 is the apparatus of any of aspects 1-6, wherein the availability threshold comprises a percentage of available resources from the one or more SL resources.

Aspect 8 is the apparatus of any of aspects 1-7, wherein the availability threshold comprises a threshold size of available resources from the one or more SL resources.

Aspect 9 is the apparatus of any of aspects 1-8, wherein the second set of available resources is indicated in a resource availability report comprising a list of each resource in the second set of available resources.

Aspect 10 is the apparatus of any of aspects 1-9, wherein the second set of available resources is indicated in a resource availability report comprising a top percentage of available resources based on the second measurement threshold.

Aspect 11 is the apparatus of any of aspects 1-10, wherein the second measurement threshold is based on one or more of: a packet priority associated with a sidelink communication associated with a second UE, a MCS associated with the second UE, a cast type associated with the second UE, a remaining packet delay budget associated with the sidelink communication associated with the second UE, a communication range specification associated with the second UE, a HARQ ACK utilization status associated with the sidelink communication associated with the second UE, a CBR, or a distance between the first UE and the second UE.

Aspect 12 is the apparatus of any of aspects 1-11, further comprising an antenna coupled to the at least one processor.

Aspect 13 is an apparatus for wireless communication at a first UE, comprising: a memory; and at least one processor coupled to the memory and configured to: perform a sensing measurement on one or more SL resources to determine one or more available resources for sidelink communication; and transmit a sidelink message including a resource availability report indicating a subset of the one or more available resources.

Aspect 14 is the apparatus of aspect 13, wherein the subset corresponds to a percentage value of the one or more available resources of the one or more SL resources.

Aspect 15 is the apparatus of any of aspects 13-14, wherein the at least one processor and the memory are further configured to: rank the one or more available resources based on the sensing measurement, wherein the subset of the one or more available resources correspond to a fraction of the one or more available resources having a lowest sensing measurement.

Aspect 16 is the apparatus of any of aspects 13-15, wherein the resource availability report indicates a ranking of each resource in the subset of the one or more available resources.

Aspect 17 is the apparatus of any of aspects 13-16, wherein the at least one processor coupled to the memory are further configured to: adjust a threshold for the sensing measurement based on a first set of available resources being below an availability threshold and further based on one or more of: a packet priority associated with the sidelink communication associated with a second UE, a MCS associated with the second UE, a cast type associated with the second UE, a remaining packet delay budget associated with the sidelink communication associated with the second UE, a communication range specification associated with the second UE, a HARQ ACK utilization status associated with the sidelink communication associated with the second UE, a CBR, or a distance between the first UE and the second UE.

Aspect 18 is the apparatus of any of aspects 13-17, further comprising an antenna coupled to the at least one processor.

Aspect 19 is a method of wireless communication for implementing any of aspects 1 to 12.

Aspect 20 is an apparatus for wireless communication including means for implementing any of aspects 1 to 12.

Aspect 22 is a method of wireless communication for implementing any of aspects 13 to 18.

Aspect 23 is an apparatus for wireless communication including means for implementing any of aspects 13 to 18.