Patent Description:
The following relates generally to wireless communications, and more specifically to sidelink groupcast configuration.

Technical document <NPL>. When Option <NUM> is used for a groupcast transmission, all the receiver UEs share a PSFCH, and when Option <NUM> is used, each receiver uses a separate PSFCH for HARQ ACK/NACK.

Technical document <NPL>. It is agreed to support two options for the sidelink HARQ feedback from the receiver UEs to the transmitter UE when HARQ feedback is enabled. Option <NUM>: Receiver UE transmits HARQ-NACK on PSFCH if it fails to decode the corresponding TB after decoding the associated PSCCH. It transmits no signal on PSFCH otherwise. Option <NUM>: Receiver UE transmits HARQ-ACK on PSFCH if it successfully decodes the corresponding TB. It transmits HARQ-NACK on PSFCH if it does not successfully decode the corresponding TB after decoding the associated PSCCH which targets the receiver UE.

Technical document<NPL>. With respect to HARQ retransmission, it discloses that it can be non-adaptive HARQ, wherein all parameters of the retransmission are the same as the initial transmission, and adaptive HARQ, wherein one or more parameters of the retransmission are determined dynamically.

Technical document <NPL>. It describes two different options for feedback. In Option <NUM>, receiver UE transmits HARQ-NACK on PSFCH if it fails to decode the corresponding TB after decoding the associated PSCCH. It transmits no signal on PSFCH otherwise. In Option <NUM>, receiver UE transmits HARQ-ACK on PSFCH if it successfully decodes the corresponding TB; transmits HARQ-NACK otherwise. The HARQ feedback mechanism affects RAN2 L2/ L3 protocol in certain way. A detailed (transmitter) UE behavior is to be specified for selecting between Option <NUM>, Option <NUM> (or a mix) considering the aspects: (a) total number of member UEs in the group (i.e. PSFCH overhead); (b) amount of available HARQ feedback resources; (c) reliability required for corresponding V2X PSSCH packet transmission (DTX probability); (d) latency/ PDB of the V2X PSSCH packet.

The present invention is defined by the attached claims.

A wireless communications system may support both access links and sidelinks for communications between wireless devices. An access link may refer to a communication link between a UE and a base station. For example, an access link may support uplink signaling, downlink signaling, connection procedures, etc. A sidelink may refer to any communication link between similar wireless devices (e.g., a communication link between UEs, or a backhaul communication link between base stations). It is noted that while various examples provided herein are discussed for UE sidelink devices, such sidelink techniques may be used for any type of wireless devices that use sidelink communications. For example, a sidelink may support device-to-device (D2D) communications, vehicle-to-everything (V2X) or vehicle-to-vehicle (V2V) communications, message relaying, discovery signaling, beacon signaling, or any combination of these or other signals transmitted over-the-air from one UE to one or more other UEs.

As demand for sidelink communication increases (e.g., due to increased V2X demand for autonomous and semi-autonomous vehicles, D2D communication between Internet-of-Things (IoT) devices, etc.), techniques to efficiently and reliably enhance throughput and reliability of sidelink channels is desirable. Techniques such as discussed in various aspects of the present disclosure provide for sidelink groupcast communications in which an identification of a UE is determined based at least in part on a member identification of the UE within the group. Techniques such as discussed in one or more aspects of the present disclosure may also provide for sidelink groupcast communications in which feedback resources for acknowledgment feedback are based on a UE identification and a size of the group.

In some cases, a UE may determine whether a common feedback resource set is to be shared among multiple UEs of the group, or whether separate feedback resources are configured for each UE, based at least in part on the size of the group. In some cases, when separate feedback resources are configured for each UE in a group of sidelink groupcast UEs, the specific feedback resources for a UE may be determined based on a UE position within the group of UEs (i.e., a UE identification relative to identifications associated with other UEs in the group) and a size of the group. For example, a first UE (e.g., based on a lowest value of a UE identifier of each of the member UEs of the group) may determine that a first set of feedback resources are to be used for providing acknowledgment feedback to a second UE of the group. In such a case, a third UE (e.g., having a higher value UE identifier than the second UE) may provide acknowledgment feedback using a second set of feedback resources that are determined based on the third UE identification minus one, due to the second UE not needing acknowledgement feedback resources (i.e., due to the second UE being the transmitting UE that receives the acknowledgment feedback from other UEs of the group).

In some cases, a higher layer, such as an application layer at each UE or a mid-ware layer at each UE, may provide a UE member ID (e.g., based on communications from a group leader of the group of UEs) to a lower layer (e.g., layer-<NUM>) at the UE. In some implementations, the lower layer may include one or more of a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, or a medium access control (MAC) at each UE. The may then determine a identification based on the UE member ID, a group identification, a group size, or any combinations thereof. In some cases, a UE may map its UE member ID to a first subset of bits of a source layer-<NUM> ID and the group ID to a second subset of bits in a destination layer-<NUM> ID.

Techniques such as discussed herein thus provide for enhanced reliability and efficiency in determining UE identifications and feedback resources in sidelink groupcast communications. For example, by enabling the determination of a UE identification and feedback resources based on a group size, or UE identification, or both, efficient determination of feedback resources may be provided without additional signaling and associated added overhead. Further, by determining source layer-<NUM> IDs and destination layer-<NUM> IDs based on the UE member ID and group ID, respectively, a layer-<NUM> ID may be determined at each UE, which further reduces signaling and overhead associated with sidelink groupcast configuration. Additionally, in some cases, determination of whether common feedback resources or separate feedback resources are used by a group of UEs may be determined at each UE based on the group size, which may also allow for reduced signaling overhead.

Aspects of the disclosure are initially described in the context of a wireless communications system. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to sidelink groupcast configuration to support feedback control.

<FIG> illustrates an example of a wireless communications system <NUM> that supports sidelink groupcast configuration to support feedback control in accordance with one or more aspects of the present disclosure. The wireless communications system <NUM> includes base stations <NUM>, UEs <NUM>, and a core network <NUM>. In some examples, the wireless communications system <NUM> may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some cases, wireless communications system <NUM> may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low-cost and low-complexity devices.

Base stations <NUM> may be dispersed throughout a geographic area to form the wireless communications system <NUM> and may be devices in different forms or having different capabilities. Base stations <NUM> and UEs <NUM> may wirelessly communicate via one or more communication links <NUM>. Each base station <NUM> may provide a coverage area <NUM> over which UEs <NUM> and the base station <NUM> may establish communication links <NUM>. The coverage area <NUM> may be an example of a geographic area over which a base station <NUM> and a UE <NUM> support the communication of signals according to one or more radio access technologies.

UEs <NUM> may be dispersed throughout a coverage area <NUM> of the wireless communications system <NUM>, and each UE <NUM> may be stationary, or mobile, or both at different times. UEs <NUM> may be devices in different forms or having different capabilities. The UEs <NUM> described herein may be able to communicate with various types of devices, such as other UEs <NUM>, base stations <NUM>, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment), as shown in <FIG>.

Base stations <NUM> may communicate with the core network <NUM>, or with one another, or both. Base stations <NUM> may communicate with one another over backhaul links <NUM> (e.g., via an X2, Xn, or other interface) either directly (e.g., directly between base stations <NUM>), or indirectly (e.g., via core network <NUM>), or both. In some examples, backhaul links <NUM> may be or include one or more wireless links. One or more of base stations <NUM> described herein may include or may be referred to by a person of ordinary skill in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next-generation NodeB or giga-NodeB (either of which may be referred to as a gNB), a Home NodeB, a Home eNodeB, or other suitable terminology. In some examples, a UE <NUM> may communicate with the core network <NUM> through communication link <NUM>.

In some examples, a UE <NUM> 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, a machine type communications (MTC) device, or the like, which may be implemented in various objects such as appliances, vehicles, meters, or the like.

The UEs <NUM> described herein may be able to communicate with various types of devices, such as other UEs <NUM> that may sometimes act as relays as well as base stations <NUM> and network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, relay base stations, and the like, as shown in <FIG>.

UEs <NUM> and base stations <NUM> may wirelessly communicate with one another via one or more communication links <NUM> over one or more carriers. The term "carrier" may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communication links <NUM>. For example, a carrier used for a communication link <NUM> may include a portion of a radio frequency spectrum band (e.g., a bandwidth part (BWP)) that is operated according to physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR).

A carrier may be associated with a frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN)) and may be positioned according to a channel raster for discovery by UEs <NUM>. A carrier may be operated in a standalone mode where initial acquisition and connection may be conducted by UEs <NUM> via the carrier, or the carrier may be operated in a non-standalone mode where a connection is anchored using a different carrier (e.g., of the same or a different radio access technology).

Communication links <NUM> shown in the wireless communications system <NUM> may include uplink transmissions from a UE <NUM> to a base station <NUM>, or downlink transmissions from a base station <NUM> to a UE <NUM>. Carriers may carry downlink or uplink communications (e.g., in an FDD mode) or may be configured to carry downlink and uplink communications (e.g., in a TDD mode).

For example, the carrier bandwidth may be one of a number of predetermined bandwidths for carriers of a particular radio access technology (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> megahertz (MHz)). Devices of the wireless communications system <NUM> (e.g., base stations <NUM>, UEs <NUM>, or both) may have hardware configurations that support communications over a particular carrier bandwidth or may be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communications system <NUM> may include base stations <NUM> or UEs <NUM> that support simultaneous communications via carriers associated with multiple carrier bandwidths. In some examples, each served UE <NUM> may be configured for operating over portions (e.g., a sub-band, a BWP) or all of a carrier bandwidth.

The electromagnetic spectrum is often subdivided, based on frequency/wavelength, into various classes, bands, channels, etc. In <NUM> NR two initial operating bands have been identified as frequency range designations FR1 (<NUM> - <NUM>) and FR2 (<NUM> - <NUM>). Although a portion of FR1 is greater than <NUM>, FR1 is often referred to (interchangeably) as a "Sub-<NUM>" band in various documents and articles.

One or more numerologies for a carrier may be supported, where a numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into BWPs having the same or different numerologies. In some examples, a UE <NUM> may be configured with multiple BWPs. In some cases, a single BWP for a carrier is active at a given time, and communications for the UE <NUM> may be restricted to active BWPs.

Time intervals for base stations <NUM> or UEs <NUM> may be expressed in multiples of a basic time unit which may, for example, refer to a sampling period of Ts = <NUM>/(Δfmax · Nf) seconds, where Δfmax may represent the maximum supported subcarrier spacing, and Nf may represent the maximum supported discrete Fourier transform (DFT) size. Time intervals of a communications resource may be organized according to radio frames each having a specified duration (e.g., <NUM> milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from <NUM> to <NUM>).

In some cases, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a number of slots.

A subframe, a slot, a mini-slot, or a symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communications system <NUM> and may be referred to as a transmission time interval (TTI). In some cases, 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 communications system <NUM> may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)).

One or more control regions (e.g., CORESETs) may be configured for a set of UEs <NUM>. For example, UEs <NUM> may monitor or search control regions for control information according to one or more search space sets, and each search space set may include one or multiple control channel candidates in one or more aggregation levels arranged in a cascaded manner.

Each base station <NUM> may provide communication coverage via one or more cells, for example a macro cell, a small cell, a hot spot, or other types of cells, or various combinations thereof. The term "cell" may refer to a logical communication entity used for communication with a base station <NUM> (e.g., over a carrier) and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID), or others). In some examples, a cell may also refer to a geographic coverage area <NUM> or a portion of a geographic coverage area <NUM> (e.g., a sector) over which the logical communication entity operates. Such cells may range from smaller areas (e.g., a structure, a subset of structure) to larger areas depending on various factors such as the capabilities of the base station <NUM>. For example, a cell may be or include a building, a subset of a building, exterior spaces between or overlapping with geographic coverage areas <NUM>, or the like.

A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs <NUM> with service subscriptions with the network provider supporting the macro cell. A small cell may be associated with a lower-powered base station <NUM>, as compared with a macro cell, and a small cell may operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells may provide unrestricted access to UEs <NUM> with service subscriptions with the network provider or may provide restricted access to UEs <NUM> having an association with the small cell (e.g., UEs <NUM> in a closed subscriber group (CSG), UEs <NUM> associated with users in a home or office, and the like). A base station <NUM> may support one or multiple cells and may also support communications over the one or more cells using one or multiple component carriers. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB), or others) that may provide access for different types of devices.

In other examples, overlapping geographic coverage areas <NUM> associated with different technologies may be supported by different base stations <NUM>. The wireless communications system <NUM> may include, for example, a heterogeneous network in which different types of base stations <NUM> provide coverage for various geographic coverage areas <NUM> using the same or different radio access technologies.

The wireless communications system <NUM> may support synchronous or asynchronous operation. For synchronous operation, the base stations <NUM> may have similar frame timings, and transmissions from different base stations <NUM> may be approximately aligned in time. For asynchronous operation, the base stations <NUM> may have different frame timings, and transmissions from different base stations <NUM> may, in some examples, not be aligned in time.

Some UEs <NUM>, such as MTC or IoT devices, may be low cost or low complexity devices and may provide for automated communication between machines (e.g., via Machine-to-Machine (M2M) communication). In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application program that makes use of the information or presents the information to humans interacting with the application program. Some UEs <NUM> may be designed to collect information or enable automated behavior of machines or other devices.

In some examples, half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for UEs <NUM> include entering a power saving deep sleep mode when not engaging in active communications, operating over a limited bandwidth (e.g., according to narrowband communications), or a combination of these techniques. For example, some UEs <NUM> may be configured for operation using a narrowband protocol type that is associated with a predefined portion or range (e.g., set of subcarriers or resource blocks (RBs)) within a carrier, within a guard-band of a carrier, or outside of a carrier.

UEs <NUM> may be designed to support ultra-reliable, low-latency, or critical functions (e.g., mission critical functions).

In some cases, a UE <NUM> may also be able to communicate directly with other UEs <NUM> over a device-to-device (D2D) communication link (e.g., using a peer-to-peer (P2P) or D2D protocol).

In some systems, the D2D communication link (e.g., a sidelink communication link <NUM>) may be an example of a communication channel, such as a sidelink communication channel, between vehicles (e.g., UEs <NUM>). In some examples, vehicles may communicate using vehicle-to-everything (V2X) communications, vehicle-to-vehicle (V2V) communications, or some combination of these. A vehicle may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information relevant to a V2X system. In some cases, vehicles in a V2X system may communicate with roadside infrastructure, such as roadside units, or with the network via one or more network nodes (e.g., base stations <NUM>) using vehicle-to-network (V2N) communications, or with both. Further, in some cases, groupcast communications among a group of UEs <NUM> may be performed via sidelink communication links <NUM>, and configuration of identifications and feedback resources in sidelink groupcast communications may be performed according to various aspects discussed herein.

The core network <NUM> may be an evolved packet core (EPC) or <NUM> core (5GC), which may include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), a user plane function (UPF)). The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for UEs <NUM> served by base stations <NUM> associated with the core network <NUM>. User IP packets may be transferred through the user plane entity, which may provide IP address allocation as well as other functions. The user plane entity may be connected to the network operators IP services. The operators IP services may include access to the Internet, Intranet(s), an IP Multimedia Subsystem (IMS), or a Packet-Switched Streaming Service.

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

The wireless communications system <NUM> may operate using one or more frequency bands, such as frequency bands in the range of <NUM> megahertz (MHz) to <NUM> gigahertz (GHz). The region from <NUM> to <NUM> may be known as the ultra-high frequency (UHF) region or decimeter band, since 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 penetrate structures sufficiently for a macro cell to provide service to UEs <NUM> located indoors. Transmission of UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than <NUM> kilometers) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below <NUM>.

The wireless communications system <NUM> may also operate in a super high frequency (SHF) region using frequency bands from <NUM> to <NUM>, also known as the centimeter band, or in an extremely high frequency (EHF) region of the spectrum (e.g., from <NUM> to <NUM>), also known as the millimeter band. In some examples, the wireless communications system <NUM> may support millimeter wave (mmW) communications between UEs <NUM> and base stations <NUM>, and EHF antennas of the respective devices may be smaller and more closely spaced than UHF antennas. In some cases, this may facilitate use of antenna arrays within a device. The propagation of EHF transmissions, however, may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions.

When operating in unlicensed radio frequency spectrum bands, devices such as base stations <NUM> and UEs <NUM> may employ carrier sensing for collision detection and avoidance. Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, D2D transmissions, or the like.

A base station <NUM> or UE <NUM> 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 a base station <NUM> or UE <NUM> may be located within one or more antenna arrays or antenna panels, which may support MIMO operations or transmit or receive beamforming. Additionally or alternatively, an antenna panel may support radio frequency beamforming for a signal transmitted via an antenna port.

Base stations <NUM> or UEs <NUM> may use MIMO communications to exploit multipath signal propagation and increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. 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). MIMO techniques include single-user MIMO (SU-MIMO), where multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO), where multiple spatial layers are transmitted to multiple devices.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station <NUM> or a UE <NUM>) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device.

The wireless communications system <NUM> may be a packet-based network that operates according to a layered protocol stack. A MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use error detection techniques, error correction techniques, or both to support retransmissions at the MAC layer to improve link efficiency.

UEs <NUM> and base stations <NUM> may support retransmissions of data to increase the likelihood that data is received successfully. Hybrid automatic repeat request (HARQ) feedback is one technique for increasing the likelihood that data is received correctly over a communication link <NUM>. HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions). In some cases, a device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot.

One or more of the base stations <NUM> may include a base station communications manager, which may configure one or more sidelink parameters for sidelink communication between a first UE <NUM> and a second UE <NUM> over a sidelink communication link <NUM> and transmit, to one or more of the sidelink UEs <NUM>, a message indicating the one or more sidelink parameters.

UEs <NUM> may include a UE communications manager <NUM>, which may determine sidelink communications parameters and configurations for sidelink communications. In some cases, the UE communications manager <NUM> may receive, from another sidelink UE <NUM>, sidelink groupcast information of a sidelink group, which may include a group size and a UE member identification. Based on the sidelink groupcast information, the UE may determine an identification for communications with the sidelink group and communicate with the sidelink group based at least in part on the determined identification. In some cases, the UE communications manager <NUM> may determine, based at least in part on a group size of the sidelink group, a feedback resource configuration for the sidelink group, which may include a configuration in which acknowledgment feedback is provided by multiple UEs <NUM> using common feedback resources, or in which acknowledgment feedback is provided in separate feedback resources by individual UEs <NUM>. In cases where separate feedback resources are configured, specific UE <NUM> resources within a set of different available resources may be determined based on a group size and a UE position within the group. The UE communications manager <NUM> may be an example of aspects of the UE communications manager <NUM> described herein.

<FIG> illustrates an example of a wireless communications system <NUM> that supports sidelink groupcast configuration to support feedback control in accordance with one or more aspects of the present disclosure. In some examples, wireless communications system <NUM> may implement aspects of wireless communications system <NUM>. In some examples, the wireless communications system <NUM> may include a first UE <NUM>-a, a second UE <NUM>-b, a third UE <NUM>-c, a fourth UE <NUM>-d, and base station <NUM>-a which may be examples of UEs <NUM> and base stations <NUM> described with reference to <FIG>. In some examples, the UE <NUM>-a, the UE <NUM>-b, and the UE <NUM>-c may be members of a group <NUM> of UEs <NUM> and the UE <NUM>-d may not be part of the group <NUM>. One or more of the UEs <NUM> may communication with the base station <NUM> using a corresponding access link <NUM>.

In this example, the first UE <NUM>-a, second UE <NUM>-b, and third UE <NUM>-c may be members of a sidelink groupcast communications group, in which members of the group may communicate with other members of the group to provide data or other information via sidelinks <NUM>. In some cases, an applications layer at the first UE <NUM>-a may prompt the creation of the sidelink groupcast communications group, and the group may be established through communications with the applications layer of other UEs <NUM> in the group. It is noted that the illustrated sidelink groupcast communications group provide communications between three UEs <NUM>, which are illustrated in wireless communications system <NUM> for the sake of brevity, and the techniques described below may be applicable to other numbers of UEs <NUM> within a system that may establish a groupcast communications group. Further, sidelink communication techniques may be used for device-to-device communication of wireless devices other than UEs, such as base station communications (e.g., wireless backhaul links between base stations or transmit-receive points (TRPs), etc.), communications between access points, and the like.

In some cases, upper layer applications that work to establish the sidelink groupcast communications group may provide group information to lower layers (e.g., to a UE access stratum (AS) which may include layer-<NUM> and layer-<NUM> layers, etc.). Such group information may be used to, for example, determine a HARQ feedback resource that is to be used by each UE <NUM> that receives communications in the group. In some cases, such HARQ feedback resources may be common acknowledgment resources that are shared among multiple UEs <NUM> (e.g., all UEs <NUM> that receive a groupcast transmission may share a same physical sidelink feedback channel (PSFCH) resource). In other cases, such HARQ resources may include separate acknowledgment feedback resources for different UEs <NUM> in the group (e.g., each UE <NUM> that receives a groupcast transmission may use a separate PSFCH resource to provide HARQ feedback). In some cases, separate lower layer signaling (e.g., layer-<NUM> signaling of a physical or AS layer at UEs <NUM>) may not be provided for groupcast communications, and thus in order for separate PSFCH resources to be implemented, each UE <NUM> in the group should be able to individually derive a distinct PSFCH to use. Thus, each group member UE's <NUM> AS layer may need an additional identifier from the upper layers to support independent selection of a PSFCH resource from a list that is not overlapping with a PSFCH resource of any other group member.

For HARQ operation, the AS layer may need an identifier that is both unique and able to indicate its position in the group. For example, in a group of five members, four PSFCH resources would be needed to provide feedback to a transmitting UE <NUM>, and a receiving UE <NUM> would need to be able to determine which of the four PSFCH resources it is to use. In cases where the application layer (e.g., a V2X application layer) provides a group identification of the sidelink groupcast communications group, additional information would be needed to identify a unique ID for the UE <NUM>. Thus, for HARQ operation (such as acknowledgement (ACK) based feedback), each group member UE's <NUM> AS layer would also need to be able to determine if all members had responded so that it can determine whether to perform retransmission. Further, given that each of the group member may act as a transmitter, all the UEs <NUM> in the group should be aware of the group size.

In some cases, such as platooning where a group of vehicles travel together in a convoy, an application layer protocol (e.g., a V2X application layer) may form the sidelink groupcast communications group, and negotiation may happen between UEs <NUM> that are members of the group. A group leader, such as a platoon leader in a platooning application, in some cases, will know the size of the group, and be able to assign each of the group members a UE member identifier. The group leader may then provide sidelink groupcast information of the sidelink group, which may include the group size and group member identifier of each UE <NUM> that is a member, which may then be provided to the AS layer at each UE <NUM>. This information may be used to identify the PSFCH resources at each UE <NUM>.

For example, in a group of five UEs <NUM>, the group leader may inform one group member of the Group Identifier (e.g., group ID), group size (e.g., <NUM>), and assign a member ID (e.g., UE member ID = <NUM>). With this information, a V2X layer at a UE <NUM> may map the group ID into a destination Layer-<NUM> ID, which may be passed to the AS layer for operation. At the same time, when generating the source Layer-<NUM> ID, the UE <NUM> may reflect the UE member ID in a subset of bits (e.g., in the last <NUM> bits) of the source Layer-<NUM> ID. Additionally, the group size (e.g., <NUM>) will be passed down to the AS layer. When the V2X layer configures the AS layer regarding a QoS flow for this V2X application, it would indicate that the QoS flow is for groupcast, and provide the corresponding QoS parameters (e.g., sidelink QoS identifier (PQI) and communications range for sidelink transmissions).

When the AS layer at a receiving UE <NUM> receives such information from the upper layers, it can operate accordingly. For example, if the UE <NUM> needs to perform a transmission, based on the QoS flow ID (PFI) and corresponding QoS context, the destination Layer-<NUM> ID and source Layer-<NUM> ID may be retrieved. In addition, the AS layer at the UE <NUM> may check the group size and determine whether separate PSFCH resources are to be used for each UE <NUM> to provide acknowledgment feedback. In some cases, a group size threshold value may be configured (e.g., as part of a sidelink groupcast configuration), in which group sizes at or below the threshold value (e.g., <NUM> group members) have separate PSFCH resources, and group sizes above the threshold value use common PSFCH resources. In cases where separate PSFCH resources are used for acknowledgment feedback, the AS layer at a UE <NUM> may derive the source Layer-<NUM> ID from the source Layer-<NUM> ID (e.g. take the last <NUM> bits of the Layer-<NUM> ID), which reflects the member ID of the UE and include the source Layer-<NUM> ID in sidelink control information (SCI).

Additionally, for a UE <NUM> in the group that is receiving a packet, such a receiving UE <NUM> can also be informed at the AS layer of the group size and UE member ID information associated with the group. Accordingly, when the packet is received, the UE <NUM> may use the group size and its own UE member ID to derive the PSFCH resources to use for providing acknowledgment feedback of the packet. For example, if the receiving UE <NUM> has a member ID=<NUM> and the transmitting UE <NUM> has a member ID=<NUM>, the receiving UE <NUM> may use the group size to infer that the transmitting UE <NUM> member ID (member ID=<NUM>) (e.g. mod (Layer-<NUM> ID, group size)), and determine that it should use the PSFCH resource indexed at four (i.e. receiving UE member ID -<NUM>, since the receiving UE member ID > transmitting UE member ID). Thus, the group size and UE member ID information provided by the application layer in such cases allows for separate feedback resources to be used at each member UE <NUM>. In cases where the number of UEs <NUM> in the group is relatively large, and above the threshold value, common feedback resources may be used by multiple UEs of the group. In some cases, such operation may be inferred at each UE <NUM> by the group size that is provided in SCI. In other cases, the type of feedback operation may be explicitly indicated in the SCI when a transmission is performed.

<FIG> illustrates an example of a UE protocol stack <NUM> that supports sidelink groupcast configuration to support feedback control in accordance with one or more aspects of the present disclosure. In some examples, UE protocol stack <NUM> may implement aspects of wireless communications system <NUM> or <NUM>. In this example, a first UE <NUM>-d may communicate with a second UE <NUM>-e in a sidelink groupcast group. Each of the first UE <NUM>-d and the second UE <NUM>-e include an application layer <NUM>, an optional mid-ware layer <NUM>, a layer-<NUM><NUM>, and a layer-<NUM><NUM>.

In some cases, layer-<NUM><NUM> and layer-<NUM><NUM> may be referred to as the AS layer. Layer-<NUM><NUM> may include a physical layer that provides physical transport channels for over the air signals. Layer-<NUM><NUM> may include, for example, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer. Optional mid-ware layer <NUM> may include, for example a group management mid-ware layer that may distribute sidelink groupcast information to the lower layers (e.g., layer-<NUM><NUM> and layer-<NUM><NUM>). In other cases, the application layer <NUM> (e.g., a V2X application layer) may perform group management and distribute sidelink groupcast information to the lower layers. As discussed with reference to <FIG>, in some cases source and destination layer-<NUM> IDs, and a layer-<NUM> ID may be determined by each UE <NUM> and used for groupcast communications and to determine resources for acknowledgment feedback transmission.

<FIG> illustrates an example of a process flow <NUM> that supports sidelink groupcast configuration to support feedback control in accordance with one or more aspects of the present disclosure. In some examples, process flow <NUM> may implement aspects of wireless communications system <NUM> or <NUM>. Process flow <NUM> may be implemented by first UE <NUM>-f, second UE <NUM>-g, or any other examples of UEs <NUM> or base stations <NUM> as described herein. Alternative examples of the following may be implemented, where some steps are performed in a different order than described or are not performed at all. In some cases, steps may include additional features not mentioned below, or further steps may be added.

At <NUM>, the first UE <NUM>-f may determine sidelink groupcast parameters. In some cases, the first UE <NUM>-f may be a group leader for sidelink groupcast communications (e.g. a platoon leader in V2X sidelink communications), and may identify a number of other UEs, including the second UE <NUM>-g, as group members. In some examples, the UE <NUM>-f may determine a member ID of the UE <NUM>-f. In some cases, the first UE <NUM>-f may determine member IDs for each UE <NUM> in the group, as part of the determination of the sidelink groupcast parameters. Further, the first UE <NUM>-f may determine a group ID associated with the sidelink groupcast communications group. In some cases, sidelink groupcast parameters may be determined by a group management mid-ware layer, at an application layer, or combination thereof.

At <NUM>, the first UE <NUM>-f may determine a sidelink groupcast feedback configuration. In some cases, the first UE <NUM>-f may identify acknowledgment feedback resources for use in providing sidelink groupcast feedback. In some case, the acknowledgment feedback resources may include separate resources for different UEs <NUM> of the sidelink groupcast communications group. Such an acknowledgment feedback resource configuration may be determined as discussed with reference to <FIG>, for example.

At <NUM>, the first UE <NUM>-f may transmit the sidelink groupcast information to the second UE <NUM>-g, which may include a group ID, a member ID of the second UE <NUM>-g, a group size, and an optional feedback configuration indication (e.g., indicating common or separate feedback resources). In some cases, the sidelink groupcast information may be provided in a SCI that is transmitted to the second UE <NUM>-g.

At <NUM>, the first UE <NUM>-f may determine a UE identification that is to be provided to lower layers (e.g., an AS layer). Likewise, at <NUM>, the second UE <NUM>-g may determine a UE identification that is to be provided to lower layers (e.g., an AS layer). In some cases, the UE identification may include a source layer-<NUM> ID, a destination layer-<NUM> ID, a layer-<NUM> ID, or any combinations thereof. Such UE identification(s) may be determined as discussed with reference to <FIG>, for example.

At <NUM>, the first UE <NUM>-f may transmit a sidelink communication to at least the second UE <NUM>-g, and one or more other UEs that may be included in the sidelink groupcast communications group. At <NUM>, the second UE <NUM>-g may receive and decode the sidelink communication, and generate acknowledgment feedback (e.g., a HARQ ACK/NACK indication).

At <NUM>, the second UE <NUM>-g may determine feedback resources that are to be used to transmit the acknowledgment feedback to the first UE <NUM>-f. Such a determination of acknowledgment feedback resources may be performed as discussed with reference to <FIG>, for example. At <NUM>, the second UE <NUM>-g may transmit a feedback communication with acknowledgment feedback to the first UE <NUM>-f.

At <NUM>, the first UE <NUM>-f may determine whether to retransmit the sidelink communication based on received feedback. In some cases, the first UE <NUM>-f may determine to retransmit the sidelink communication based on receiving one or more NACKs from other UEs <NUM> of the group. Additionally or alternatively, the first UE <NUM>-f may determine to retransmit the sidelink communication based on receiving acknowledgment feedback from fewer than all of the UEs <NUM> in the group (e.g., based on the group size of the sidelink groupcast communications group).

<FIG> shows a block diagram <NUM> of a device <NUM> that supports sidelink groupcast configuration to support feedback control in accordance with one or more aspects of the present disclosure. The device <NUM> may be an example of aspects of a UE <NUM> (e.g., a first UE or a second UE) as described herein. The device <NUM> may include a receiver <NUM>, a communications manager <NUM>, and a transmitter <NUM>. The device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

The receiver <NUM> 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 sidelink groupcast configuration to support feedback control, etc.). Information may be passed on to other components of the device <NUM>. The receiver <NUM> may be an example of aspects of the transceiver <NUM> described with reference to <FIG>. The receiver <NUM> may utilize a single antenna or a set of antennas.

The communications manager <NUM> may receive, from a second UE, sidelink groupcast information of a first sidelink group including, a group size of the first sidelink group, and a member identification of the first UE within the first sidelink group, where the first sidelink group includes a plurality of members including at least the first UE and the second UE, determine, at the first UE, an identification for communication with the first sidelink group based on the sidelink groupcast information, and communicate with the first sidelink group based on the determined identification.

The communications manager <NUM> may also configure a first sidelink group for sidelink groupcast communication, where the first sidelink group includes a plurality of members including at least the first UE and a second UE, determine a member identification of the first UE, determine, based on a group size of the first sidelink group and the determined identification of the first UE, a feedback resource configuration for the sidelink group, where the feedback resource configuration includes a common feedback resource use by the plurality of members or separate feedback resources corresponding to each of the plurality of members, transmit, to other of the plurality of members of the first sidelink group, sidelink groupcast information that indicates at least the feedback resource configuration, communicate with the first sidelink group based on the determined identification and the feedback resource configuration, and determine, at the first UE, an identification for communication with the first sidelink group based on the sidelink groupcast information. The communications manager <NUM> may be an example of aspects of the communications manager <NUM> described herein.

The communications manager <NUM> may be an example of means for performing various aspects of sidelink groupcast configuration as described herein. The communications manager <NUM>, or its sub-components, may be implemented in hardware (e.g., in communications manager circuitry) The circuitry may comprise of processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

In another implementation, the communications manager <NUM>, or its sub-components, may be implemented in code (e.g., as communications management software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communications manager <NUM>, or its sub-components may be executed by a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device.

In some examples, the communications manager <NUM> may be configured to perform various operations (e.g., receiving, determining, transmitting) using or otherwise in cooperation with the receiver <NUM>, the transmitter <NUM>, or both.

In some examples, the communications manager <NUM> may be implemented as an integrated circuit or chipset for a mobile device modem, and a receiver <NUM> and transmitter <NUM> may be implemented as analog components (e.g., amplifiers, filters, antennas) coupled with the mobile device modem to enable wireless transmission and reception over one or more bands.

The communications manager <NUM> as described may be implemented to realize one or more potential advantages. One implementation may allow the device <NUM> to support feedback control for sidelink groupcast communication. As such, the device <NUM> may determine device identification and feedback resources and may experience enhanced reliability and efficiency. In some examples, the device <NUM> may experience a decreased power consumption and increased battery life, among other benefits.

<FIG> shows a block diagram <NUM> of a device <NUM> that supports sidelink groupcast configuration to support feedback control in accordance with one or more aspects of the present disclosure. The device <NUM> may be an example of aspects of a device <NUM>, or a UE <NUM> (e.g., a first UE or a second UE) as described herein. The device <NUM> may include a receiver <NUM>, a communications manager <NUM>, and a transmitter <NUM>. The device <NUM> may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses).

The communications manager <NUM> may be an example of aspects of the communications manager <NUM> as described herein. The communications manager <NUM> may include a sidelink configuration manager <NUM>, an identification manager <NUM>, a sidelink communications manager <NUM>, and a feedback configuration manager <NUM>. The communications manager <NUM> may be an example of aspects of the communications manager <NUM> described herein.

In some cases, the sidelink configuration manager <NUM> may receive, from a second UE, sidelink groupcast information of a first sidelink group including, a group size of the first sidelink group, and a member identification of the first UE within the first sidelink group, where the first sidelink group includes a plurality of members including at least the first UE and the second UE. The identification manager <NUM> may determine, at the first UE, an identification for communication with the first sidelink group based on the sidelink groupcast information. The sidelink communications manager <NUM> may communicate with the first sidelink group based on the determined identification.

In some cases, the sidelink configuration manager <NUM> may configure a first sidelink group for sidelink groupcast communications, where the first sidelink group includes a plurality of members including at least the first UE and a second UE. The feedback configuration manager <NUM> may determine, based on a group size of the first sidelink group, a feedback resource configuration for the sidelink group, where the feedback resource configuration includes a common feedback resource use by the plurality of members or separate feedback resources corresponding to each of the plurality of members. The sidelink communications manager <NUM> may transmit, to other of the plurality of members of the first sidelink group, sidelink groupcast information that indicates at least the feedback resource configuration and communicate with the first sidelink group based on the determined identification and the feedback resource configuration. The identification manager <NUM> may determine, at the first UE, an identification for communications with the first sidelink group based on the sidelink groupcast information.

<FIG> shows a block diagram <NUM> of a communications manager <NUM> that supports sidelink groupcast configuration to support feedback control in accordance with one or more aspects of the present disclosure. The communications manager <NUM> may be an example of aspects of a communications manager <NUM>, a communications manager <NUM>, or a communications manager <NUM> described herein. The communications manager <NUM> may include a sidelink configuration manager <NUM>, an identification manager <NUM>, a sidelink communications manager <NUM>, a L2 ID manager <NUM>, a L1 ID manager <NUM>, a feedback configuration manager <NUM>, a feedback determination manager <NUM>, and a QoS flow manager <NUM>. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses).

The sidelink configuration manager <NUM> may receive, from a second UE, sidelink groupcast information of a first sidelink group including, a group size of the first sidelink group, and a member identification of the first UE within the first sidelink group, where the first sidelink group includes a plurality of members including at least the first UE and the second UE. In some cases, the sidelink groupcast information further includes a group identifier of a first sidelink group.

In some examples, the sidelink configuration manager <NUM> may configure a first sidelink group for sidelink groupcast communications, where the first sidelink group includes a plurality of members including at least the first UE and a second UE. In some cases, the sidelink groupcast information is received at an application layer of the first UE or at a group management mid-ware layer at the first UE. In some cases, the sidelink groupcast information further indicates a group identifier of the first sidelink group, a group size of the first sidelink group, and a corresponding member identification within the first sidelink group of each of the plurality of members.

The identification manager <NUM> may determine, at the first UE, an identification for communications with the first sidelink group based on the sidelink groupcast information. In some examples, the identification manager <NUM> may determine a member identification of the first UE.

The sidelink communications manager <NUM> may communicate with the first sidelink group based on the determined identification.

In some examples, the sidelink communications manager <NUM> may transmit, to other of the plurality of members of the first sidelink group, sidelink groupcast information that indicates at least the feedback resource configuration. In some examples, the sidelink communications manager <NUM> may communicate with the first sidelink group based on the determined identification and the feedback resource configuration.

The feedback configuration manager <NUM> may determine, based on a group size of the first sidelink group and a member identification of the first UE, a feedback resource configuration for the sidelink group, where the feedback resource configuration includes a common feedback resource use by the plurality of members or separate feedback resources corresponding to each of the plurality of members.

In some examples, the feedback configuration manager <NUM> may determine, based on the group size of the first sidelink group, whether each of the members of the first sidelink group uses separate feedback resources for providing acknowledgment feedback information to other of the members of the first sidelink group.

In some cases, the first UE determines whether separate feedback resources or common feedback resources are used for providing the acknowledgement feedback information based on whether a number of members of the first sidelink group is above a threshold number of members. In some cases, the separate feedback resources are used for providing acknowledgement feedback information when a number of members of the first sidelink group is at or below a threshold number of members. According to the present invention, the common resources are used for providing acknowledgement feedback information when the number of members of the first sidelink group exceeds the threshold number of members.

In some cases, the first UE determines whether the separate feedback resources or the common feedback resources are used for providing the acknowledgement feedback information based on a pre-configuration of the first UE, control signaling received from another UE or a base station, or any combinations thereof. In some cases, the first UE determines whether separate feedback resources or common feedback resources are used for providing the acknowledgement feedback information based on RRC signaling received at the first UE, a SIB received at the first UE, a MAC control element received at the first UE, or any combinations thereof. In some cases, a number of the separate feedback resources corresponds to a number of members of the first sidelink group minus one.

The L2 ID manager <NUM> may manage a layer-<NUM> ID of the UE. In some cases, the identification is a destination layer-<NUM> identification, and the member identification of the first UE is included as a first subset of bits of a source layer-<NUM> identification. In some cases, the group identifier is mapped into a second subset of bits of a destination layer-<NUM> identification. In some cases, a number of bits of the first subset of bits is determined based on the group size of the first sidelink group. In some cases, the identification is a source layer-<NUM> identification, and the identification of the first UE is included as a first subset of bits of the source layer-<NUM> identification, and where the group identifier is mapped into a second subset of bits of a destination layer-<NUM> identification. In some cases, a number of bits of the first subset of bits is determined based on the group size of the first sidelink group.

The L1 ID manager <NUM> may determine a layer-<NUM> identification based on the source layer-<NUM> identification, where the layer-<NUM> identification is indicated in a physical layer control information transmission to the first sidelink group. In some cases, the layer-<NUM> identification corresponds to a subset of the source layer-<NUM> identification that indicates the group identifier of the first sidelink group and the member identification of the first UE within the first sidelink group.

The feedback determination manager <NUM> may determine, based at least in part on the group size of the first sidelink group and the member identification of the first UE within the first sidelink group, a set of feedback resources for transmitting acknowledgment feedback information to one or more members of the first sidelink group.

In some examples, the feedback determination manager <NUM> may receive a first groupcast communication from the second UE. In some examples, the feedback determination manager <NUM> may determine acknowledgment feedback for the first groupcast communication. In some examples, the feedback determination manager <NUM> may transmit the acknowledgment feedback for the first groupcast communication to the second UE using the set of feedback resources.

In some examples, the feedback determination manager <NUM> may transmit a groupcast communication to other of the plurality of members of the first sidelink group. In some examples, the feedback determination manager <NUM> may determine to retransmit the groupcast communication based on the acknowledgment feedback from at least one of the plurality of members of the first sidelink group.

In some examples, the feedback determination manager <NUM> may determine that at least one of the plurality of members of the first sidelink group provides a negative acknowledgment, determining that an acknowledgment feedback from at least one of the plurality of members of the first sidelink group is not received at the first UE, or any combinations thereof. In some examples, the feedback determination manager <NUM> may transmit a groupcast communication to other of the plurality of members of the first sidelink group. In some examples, the feedback determination manager <NUM> may monitor, based on the feedback resource configuration, for acknowledgment feedback from the other of the plurality of members of the first sidelink group.

The QoS flow manager <NUM> may configure an access stratum layer at the first UE for a QoS flow for groupcast communications associated with a layer-<NUM> identification, and where the access stratum layer determines a QoS flow identification and a QoS context and derives a layer-<NUM> identification for the QoS flow.

<FIG> shows a diagram of a system <NUM> including a device <NUM> that supports sidelink groupcast configuration to support feedback control in accordance with one or more aspects of the present disclosure. The device <NUM> may be an example of or include the components of device <NUM>, device <NUM>, or a UE <NUM> as described herein. The device <NUM> may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager <NUM>, an I/O controller <NUM>, a transceiver <NUM>, an antenna <NUM>, memory <NUM>, and a processor <NUM>. These components may be in electronic communication via one or more buses (e.g., bus <NUM>).

The communications manager <NUM> may also configure a first sidelink group for sidelink groupcast communications, where the first sidelink group includes a plurality of members including at least the first UE and a second UE, determine a member identification of the first UE, determine, based on a group size of the first sidelink group and the determined member identification of the first UE, a feedback resource configuration for the sidelink group, where the feedback resource configuration includes a common feedback resource use by the plurality of members or separate feedback resources corresponding to each of the plurality of members, transmit, to other of the plurality of members of the first sidelink group, sidelink groupcast information that indicates at least the feedback resource configuration, communicate with the first sidelink group based on the determined identification and the feedback resource configuration, and determine, at the first UE, an identification for communication with the first sidelink group based on the sidelink groupcast information.

The processor <NUM> 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, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor <NUM> may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor <NUM>. The processor <NUM> may be configured to execute computer-readable instructions stored in a memory (e.g., the memory <NUM>) to cause the device <NUM> to perform various functions (e.g., functions or tasks supporting sidelink groupcast configuration to support feedback control).

<FIG> shows a flowchart illustrating a method <NUM> that supports sidelink groupcast configuration to support feedback control in accordance with one or more aspects of the present disclosure. The operations of method <NUM> may be implemented by a UE <NUM> or its components as described herein. For example, the operations of method <NUM> may be performed by a communications manager as described with reference to <FIG>. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, a UE may perform aspects of the functions described below using special-purpose hardware.

At <NUM>, the UE may receive, from a second UE, sidelink groupcast information of a first sidelink group including, a group size of the first sidelink group, and a member identification of the first UE within the first sidelink group, where the first sidelink group includes a plurality of members including at least the first UE and the second UE. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a sidelink configuration manager as described with reference to <FIG>.

At <NUM>, the UE may determine an identification for communication with the first sidelink group based on the sidelink groupcast information. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by an identification manager as described with reference to <FIG>.

At <NUM>, the UE may communicate with the first sidelink group based on the determined identification. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a sidelink communications manager as described with reference to <FIG>.

At <NUM>, the UE may determine, based on the group size of the first sidelink group, whether each of the plurality of members of the first sidelink group uses separate feedback resources for providing acknowledgment feedback information to other of the plurality of members of the first sidelink group. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback configuration manager as described with reference to <FIG>.

At <NUM>, the UE may determine, based at least in part on the group size of the first sidelink group and the member identification of the first UE within the first sidelink group, a set of feedback resources for transmitting acknowledgment feedback information to one or more members of the first sidelink group. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback determination manager as described with reference to <FIG>.

At <NUM>, the UE may receive a first groupcast communication from the second UE. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback determination manager as described with reference to <FIG>.

At <NUM>, the UE may determine acknowledgment feedback for the first groupcast communication. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback determination manager as described with reference to <FIG>.

At <NUM>, the UE may transmit the acknowledgment feedback for the first groupcast communication to the second UE using the set of feedback resources. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback determination manager as described with reference to <FIG>.

At <NUM>, the UE may transmit a groupcast communication to other of the plurality of members of the first sidelink group. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback determination manager as described with reference to <FIG>.

At <NUM>, the UE may monitor for acknowledgment feedback from the other of the plurality of members of the first sidelink group. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback determination manager as described with reference to <FIG>.

At <NUM>, the UE may determine to retransmit the groupcast communication based on the acknowledgment feedback from at least one of the plurality of members of the first sidelink group. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback determination manager as described with reference to <FIG>.

At <NUM>, the UE may configure a first sidelink group for sidelink groupcast communication, where the first sidelink group includes a plurality of members including at least the first UE and a second UE. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a sidelink configuration manager as described with reference to <FIG>.

At <NUM>, the UE may determine a member identification for the first UE. The operations of the <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by an identification manager as described with reference to <FIG>.

At <NUM>, the UE may determine, based on a group size of the first sidelink group and the determined member identification of the first UE, a feedback resource configuration for the sidelink group, where the feedback resource configuration includes a common feedback resource used by the plurality of members or separate feedback resources corresponding to each of the plurality of members. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback configuration manager as described with reference to <FIG>.

At <NUM>, the UE may transmit, to other of the plurality of members of the first sidelink group, sidelink groupcast information that indicates at least the feedback resource configuration. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a sidelink communications manager as described with reference to <FIG>.

At <NUM>, the UE may communicate with the first sidelink group based on the determined identification and the feedback resource configuration. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a sidelink communications manager as described with reference to <FIG>.

At <NUM>, the UE may configure a first sidelink group for sidelink groupcast communications, where the first sidelink group includes a plurality of members including at least the first UE and a second UE. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a sidelink configuration manager as described with reference to <FIG>.

At <NUM>, the UE may determine, based on a group size of the first sidelink group, a feedback resource configuration for the sidelink group, where the feedback resource configuration includes a common feedback resource used by the plurality of members or separate feedback resources corresponding to each of the plurality of members. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback configuration manager as described with reference to <FIG>.

At <NUM>, the UE may determine an identification for communications with the first sidelink group based on the sidelink groupcast information. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by an identification manager as described with reference to <FIG>.

At <NUM>, the UE may monitor, based on the feedback resource configuration, for acknowledgment feedback from the other of the plurality of members of the first sidelink group. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback determination manager as described with reference to <FIG>. In some cases, separate feedback resources are used for providing acknowledgement feedback information when a number of the plurality of members of the first sidelink group is at or below a threshold number of members. In some cases, common resources are used for providing acknowledgement feedback information when the number of the plurality of members of the first sidelink group exceeds the threshold number of members.

At <NUM>, the UE may determine to retransmit the groupcast communication based on acknowledgment feedback from at least one of the plurality of members of the first sidelink group. The operations of <NUM> may be performed according to the methods described herein. In some examples, aspects of the operations of <NUM> may be performed by a feedback determination manager as described with reference to <FIG>.

The following provides an overview of examples of the present disclosure:.

Techniques described herein may be used for various wireless communications systems such as CDMA, time division multiple access (TDMA), frequency division multiple access (FDMA), OFDMA, single carrier frequency division multiple access (SC-FDMA), and other systems.

A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider.

By way of example, and not limitation, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

Claim 1:
A method (<NUM>) for wireless communication at a first user equipment, UE, comprising:
receiving, from a second UE, (<NUM>) sidelink groupcast information of a first sidelink group, the sidelink groupcast information including a group size of the first sidelink group, and a member identification of the first UE within the first sidelink group, wherein the first sidelink group includes at least the first UE and the second UE;
determining (<NUM>), at the first UE, an identification for communication with the first sidelink group; and
communicating (<NUM>) with the first sidelink group based at least in part on the determined identification, characterised by:
determining, at the first UE, based at least in part on the group size of the first sidelink group, a feedback operation type corresponding to common feedback resources used by a plurality of members of the first sidelink group, based at least in part on a number of the plurality of members of the first sidelink group exceeding a threshold number of members.