Inter-UE coordination for sidelink communications on the unlicensed spectrum

Abstract

Disclosed are methods, systems, and computer-readable medium to perform operations including: transmitting, from a first user equipment (UE) to a second UE, inter-UE coordination (IUC) information for resource allocation for unlicensed sidelink (SL-U) communication, the IUC information specifying one or more available resources for SL-U communication for interlaced transmissions between at least two resource block (RB) sets; and performing a SL-U communication using at least one resource specified in the IUC information.

Description

INTER-UE COORDINATION FOR SIDELINK COMMUNICATIONS ON THE UNLICENSED SPECTRUMCLAIM OF PRIORITY

[0001] This application claims priority under 35 U.S.C. §119(e) to U.S. Patent Application Serial No. 63 / 547,229 filed on November 3, 2023, the entire contents of which are hereby incorporated by reference.BACKGROUND

[0002] Wireless communication networks provide integrated communication platforms and telecommunication services to wireless user devices. Example telecommunication services include telephony, data (e.g., voice, audio, and / or video data), messaging, and / or other services. The wireless communication networks have wireless access nodes that exchange wireless signals with the wireless user devices using wireless network protocols, such as protocols described in various telecommunication standards promulgated by the Third Generation Partnership Project (3GPP). Example wireless communication networks include time division multiple access (TDMA) networks, frequency-division multiple access (FDMA) networks, orthogonal frequency-division multiple access (OFDMA) networks, Long Term Evolution (LTE), and Fifth Generation New Radio (5G NR). The wireless communication networks facilitate mobile broadband service using technologies such as OFDM, multiple input multiple output (MIMO), advanced channel coding, massive MIMO, beamforming, and / or other features.SUMMARY

[0003] UEs coordinate with one another to determine which resources are to be used for SL-U communication between the UEs. In a first inter-UE coordination (IUC) scheme, a first UE sends coordination to a second UE. The coordination information sent from the first UE specifies the preferred or non-preferred resources for the second UE to transmit to the first UE. This is also called a proactive IUC scheme with respect to the first UE. In a second IUC scheme, a first UE sends coordination information that indicates the presence of expected or potential resource conflicts on the resources indicated by the sidelink control information (SCI) sent to the first UE by a second UE. The indication can be a single bit using a physical sidelink feedback channel (PSFCH) occasion.

[0004] The transmissions between UEs for SL-U can be interlaced on subchannels that are among a number of different RB sets. When the first UE sends coordination information to the second UE for IUC specifying the preferred resources, the UE signals not only the subchannel in an RB set that is to be used, but also which RB sets are included in the resources for SL-U transmissions. The UE signals the subchannel index, the RB set information, and, in some cases, a lowest RB set index for contiguous RB sets. The inclusion of these data enables the first and second UEs to communicate using SL-U and interlace transmissions among different RB sets.

[0005] In an aspect, a process includes transmitting, from a first user equipment (UE) to a second UE, inter-UE coordination (IUC) information for resource allocation for unlicensed sidelink (SL-U) communication, the IUC information specifying one or more available resources for SL-U communication for interlaced transmissions between at least two resource block (RB) sets. The process includes performing a SL-U communication using at least one resource specified in the IUC information.

[0006] In some implementations, the IUC information causes a physical layer in the second UE to exclude in resource selection or reselection the one or more available resources of the IUC information from candidate single-slot resources obtained during a resource selection procedure.

[0007] In some implementations, the IUC information includes one or more combinations of timing resource index values (TRIV). In some implementations, the TRIV includes a first resource location including a resource block (RB) set index. In some implementations, the IUC information includes one or more combinations of frequency resource index values (FRIV).

[0008] In some implementations, the IUC information is transmitted in a medium access control (MAC) control element (CE). In some implementations, the IUC information is transmitted in the MAC CE and in sidelink control information (SCI) format 2. In some implementations, the SCI includes a field specifying a number of subchannels for each of one or more RB sets. In some implementations, the SCI includes a field specifying a number of RB sets. In some implementations, the SCI includes a field specifying a number of consecutive slots for resource allocation. In some implementations, the SCI includes a field specifying a lowest RB set index. In some implementations, the SCI includes a field specifying that SL-U uses interlaced RB sets. In some implementations, the SCI includes a field specifying a number of subchannels and a number of RB sets from a resource pool. In some implementations, the MAC CE is a MAC CE for IUC information, and wherein the MAC CE for information includes a field specifying lowest RB set indices for a first resource location of each TRIV. In some implementations, the MAC CE is a MAC CE for IUC information, and wherein the MAC CE for information includes a field specifying a resource combination as a code point value of SCI format 2-C. In some implementations, the MAC CE is a MAC CE for IUC information, and wherein the MAC CE for information includes a field specifying a number of consecutive slots. In some implementations, the MAC CE is a MAC CE for an IUC request, and wherein the MAC CE for the request includes a field specifying a number of RB sets. In some implementations, the MAC CE is a MAC CE for an IUC request, and wherein the MAC CE for the request includes a field specifying a number of sub-channels per RB set. In some implementations, the MAC CE is a MAC CE for an IUC request, and wherein the MAC CE for the request includes a field specifying a number of consecutive slots.

[0009] In an aspect, the process includes identifying one or more candidate physical sidelink feedback channel (PSFCH) occasions for specifying inter-UE coordination (IUC) information for resource allocation for unlicensed sidelink (SL-U) communication for a first UE. The IUC information specifies at least one conflicting resource from sidelink control information (SCI) transmission by a second UE. The process includes transmitting, from a first user equipment (UE) to a second UE, PSFCH data on the identified one or more candidate PSFCH occasions, the PSFCH data specifying the at least one conflicting resource.

[0010] In some implementations, the PSFCH occasion is selected as a first available candidate slot in a resource pool after a predetermined time gap after the SCI transmission by the second UE. In some implementations, the PSFCH occasion is at least a predetermined time before the at least one conflicting resource. In some implementations, the second UE is configured tomonitor all candidate PSFCH occasions that are after a first time gap after the SCI transmission by the second UE and before a second time gap prior to the at least one conflicting resource. In some implementations, the second UE stops monitoring PSFCH occasions responsive to detecting the PSFCH data from the first UE.

[0011] In some implementations, a number of candidate PSFCH occasions is one of 1, 2, 3, or 4.

[0012] In some implementations, a first candidate PSFCH occasion is on a first slot which is at least a predetermined number of slots after the SCI transmission of the second UE, and wherein a second candidate PSFCH occasion is on a second slot which is at least the predetermined number of slots after the SCI transmission of the second UE.

[0013] In some implementations, the PSFCH occasion is selected as a last available candidate slot in a resource pool prior to a predetermined time gap prior to a slot of the at least one resource associated with conflict information of second UE.

[0014] In some implementations, multiple PSFCH occasions are counted starting from the last available slot in the resource pool that includes PSFCH resources.

[0015] In some implementations, a last candidate PSFCH occasion is on a last slot which is at least a predetermined number of slots before a slot of the resource associated with the conflict information, and wherein a second last candidate PSFCH occasion is on a second last slot which is at least the predetermined number of slots before a slot of the resource associated with the conflict information.

[0016] In some implementations, multiple PSFCH occasions are counted starting from a first available slot in the resource pool that includes PSFCH resources and that satisfies a predetermined time gap from the SCI transmission of the second UE.

[0017] In some implementations, multiple PSFCH occasions are counted starting from the last available slot in the resource pool before a slot of the resource associated with the conflict information and that includes PSFCH resources backward to previous candidate PSFCH resources.

[0018] In an aspect, a system comprising one or more computers and one or more storage devices on which are stored instructions that are operable, when executed by the one or morecomputers, to cause the one or more computers to perform operations of the foregoing processes.

[0019] In an aspect, a system comprising one or more computers and one or more storage devices on which are stored instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations of the foregoing processes.

[0020] A non-transitory computer storage medium encoded with instructions that, when executed by one or more computers, cause the one or more computers to perform operations of the method of any of foregoing processes.

[0021] An apparatus comprising one or more baseband processors configured to perform operations of the method of any of the foregoing processes.

[0022] The details of one or more embodiments of these systems and methods are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of these systems and methods will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF THE FIGURES

[0023] FIG. 1 illustrates an example communication system that includes sidelink communications, according to some implementations.

[0024] FIG. 2A illustrates an example scheme for inter-UE coordination for resource allocation (RA).

[0025] FIG. 2B illustrates an example scheme for inter-UE coordination for resource allocation.

[0026] FIG. 3 illustrates an example timing diagram for the inter-UE coordination for RA scheme of FIG. 2B.

[0027] FIGS. 4A-4B each illustrate an example medium access control (MAC) control element (CE) providing information for inter-UE coordination for SL-U in accordance with the example scheme of FIG. 2 A.

[0028] FIG. 4C illustrates an example MAC CE for an inter-UE coordination request for SL- U in accordance with the example scheme of FIG. 2 A.

[0029] FIG. 5 illustrates an example of a resource pool for SL-U.

[0030] FIG. 6 illustrates an example timing diagram for the inter-UE coordination for RA scheme of FIG. 2B.

[0031] FIGS. 7A-7B each illustrates an example messaging scheme for the inter-UE coordination for RA scheme of FIG. 2B.

[0032] FIG. 8 illustrates an example timing diagram for the inter-UE coordination for RA scheme of FIG. 2B.

[0033] FIG. 9 illustrates an example timing diagram for the inter-UE coordination for RA scheme of FIG. 2B.

[0034] FIG. 10 illustrates an example timing diagram for the inter-UE coordination for RA scheme of FIG. 2B.

[0035] FIGS. 11 A-l IB each illustrates a flowchart of an example method, according to some implementations.

[0036] FIG. 12 illustrates an example user equipment (UE), according to some implementations.

[0037] FIG. 13 illustrates an example access node, according to some implementations.DETAILED DESCRIPTION

[0038] In sidelink (SL) communications, a first UE is configured to communicate directly with a second UE without a base station. For SL transmissions, a UE is configured to perform operations based on available resource block (RB) sets in the unlicensed spectrum. In the unlicensed spectrum, the UE is competing with other technologies (e.g., WiFi devices) for channel access. The first UE selects a channel for sidelink operation using unlicensed spectrum (SL-U) communications and subsequently can transmit to another UE using the selected channel. The UE may not always successfully complete a transmission, such as physical sidelink shared channel (PSSCH) or physical sidelink control channel (PSCCH) transmission.

[0039] The network allocates resources from candidate resources that include an RB set in a resource pool. The network defines a sub-channel within each RB set, as described in greater detail in relation to FIG. 5. The sub-channels are in the frequency domain. In legacy operation, a set of consecutive sub-channels are selected for a set of N sub-channels (e.g., a set of 10 subchannels). A UE can select the consecutive sub-channels for the transmission (e.g., 2 subchannels). However, for SL-U, a resource pool can include multiple RB sets. In an example, the resource pool includes two RB sets (RB set 1 and RB set 2), each including 5 sub-channels. The UE can select a first set of sub-channels in RB set 1 or RB set 2. Alternatively, the UE can select a first sub-channel from RB set 1 and a second sub-channel from RB set 2, wherein resources are allocated from two different RB sets. In legacy resource allocation signaling, the resource allocation is designated (in either mode 1 or mode 2) by an index or starting subchannel of the RB set, as the sub-channels that are selected are consecutive in legacy operation. For example, a UE may indicate the index of sub-channel 2 to allocate sub-channels 2 and 3 of the RB set as candidate resources. In SL-U, because there are multiple RB sets available, the allocation information includes additional information that enables other UEs to determine each of the sub-channel(s) and RB set(s) allocated for transmission by the UE.

[0040] UEs coordinate with one another to determine which resources are to be used for SL-U communication between the UEs. In a first inter-UE coordination (IUC) scheme, described in further detail below with respect to FIG. 2A, a first UE sends coordination to a second UE. The coordination information sent from the first UE specifies the preferred or non-preferred resources for the second UE to transmit to the first UE. This is also called a proactive IUC scheme with respect to the first UE. In a second IUC scheme, described in further detail below with respect to FIG. 2B, a first UE sends coordination information that indicates the presenceof expected or potential resource conflicts on the resources indicated by the sidelink control information (SCI) sent to the first UE by a second UE. The indication can be a single bit using a physical sidelink feedback channel (PSFCH) occasion.

[0041] The transmissions between UEs for SL-U can be interlaced on subchannels that are among a number of different RB sets. When the first UE sends coordination information to the second UE for IUC specifying the preferred resources, the UE signals not only the subchannel in an RB set that is to be used, but also which RB sets are included in the resources for SL-U transmissions. The UE signals the subchannel index, the RB set information, and, in some cases, a lowest RB set index for contiguous RB sets. The inclusion of these data enables the first and second UEs to communicate using SL-U and interlace transmissions among different RB sets.

[0042] The systems and methods described herein are configured to enable interlaced transmissions in the SL-U using IUC information. Specifically, these fields specify the RB sets, frequency subchannels in those RB sets, and lowest RB set index for preferred or non-preferred resources. In an example, these data are specified in SCI fields (e.g., a modified SCI format 2C) for inter-UE coordination requests and for inter-UE coordination information. In another example, the first UE can use a modified control (MAC) control element (CE) format for inter- UE coordination requests and for sending inter-UE coordination information.

[0043] This disclosure specifies candidate PSFCH occasions for signaling IUC information representing resource conflicts to the second UE from the first UE. As previously described, the UE can signal resource conflicts for IUC using a PSFCH occasion. When the UE is using the PSFCH to signal SL-U coordination information, the UE uses a particular occasion to ensure that there is enough time for the second UE to avoid scheduling the SL-U transmission on a conflicting resource. Specifically, a minimum time gap is defined in which PSFCH occasions are not used to transmit IUC information to the second UE from the first UE. in some implementations, multiple PSFCH occasions can be candidates for transmitting IUC conflict information, as subsequently described in further detail. The PSFCH can be derived by a slot where the second UE’s SCI is transmitted. In another example, the PSFCH occasion is derived by a slot where an expected or a potential resource conflict occurs on a physical PSSCH resource indicated by the second UE’s SCI.

[0044] FIG. 1 illustrates an example communication system 100 that includes sidelink communications, according to some implementations. It is noted that the system of FIG. 1 ismerely one example of a possible system, and that features of this disclosure may be implemented in other wireless communication systems.

[0045] The following description is provided for an example communication system that operates in conjunction with fifth generation (5G) networks as provided by 3GPP technical specifications. However, the example implementations are not limited in this regard and the described examples may apply to other networks that may benefit from the principles described herein, such as 3GPP Long Term Evolution (LTE) networks, Wi-Fi or Worldwide Interoperability for Microwave Access (WiMaX) networks, and the like. Furthermore, other types of communication standards are possible, including future 3 GPP systems (e.g., Sixth Generation (6G)), IEEE 802.16 protocols, or the like. While aspects may be described herein using terminology commonly associated with 5G NR, aspects of the present disclosure can be applied to other systems, such as 3G, 4G, and / or systems subsequent to 5G (e.g., 6G).

[0046] Frequency bands for 5G NR may be separated into two different frequency ranges. Frequency Range 1 (FR1) may include frequency bands operating in sub-6 GHz frequencies, some of which are bands that may be used by previous standards and may potentially be extended to cover new spectrum offerings from 410 Megahertz (MHz) to 7125 MHz. Frequency Range 2 (FR2) may include frequency bands from 24.25 Gigahertz (GHz) to 52.6 GHz. Bands in the millimeter wave (mmWave) range of FR2 may have smaller coverage but potentially higher available bandwidth than bands in the FR1.

[0047] As shown, the communication system 100 includes a number of user devices. More specifically, the communication system 100 includes two UEs 105 (UE 105-1 and UE 105-2 are collectively referred to as “UE 105” or “UEs 105”), two base stations 110 (base station 110-1 and base station 110-2 are collectively referred to as “base station 110” or “base stations 110”), two cells 115 (cell 115-1 and cell 115-2 are collectively referred to as “cell 115” or “cells 115”), and one or more servers 135 in a core network (CN) 140 that is connected to the Internet 145.

[0048] In some implementations, the UEs 105 can directly communicate with base stations 110 via links 120 (link 120-1 and link 120-2 are collectively referred to as “link 120” or “links 120”), which utilize a direct interface with the base stations referred to as a “Uu interface.” Each of the links 120 can represent one or more channels. The links 120 are illustrated as an air interface to enable communicative coupling, and can be consistent with cellular communication protocols, such as a GSM protocol, a CDMA network protocol, a UMTSprotocol, a 3 GPP LTE protocol, an Advanced long term evolution (LTE-A) protocol, a LTE- based access to unlicensed spectrum (LTE-U), a 5G protocol, a NR protocol, an NR-based access to unlicensed spectrum (NR-U) protocol, and / or any of the other communications protocols discussed herein.

[0049] As shown, certain user devices may be able to conduct communications with one another directly, e.g., without an intermediary infrastructure device such as base station 110-1. In this example, UE 105-1 may conduct communications directly with UE 105-2. Similarly, the UE 105-2 may conduct communications directly with UE 105-1. Such peer-to-peer communications may utilize a “sidelink” interface such as a PC5 interface. In certain implementations, the PC5 interface supports direct cellular communication between user devices (e.g., between UEs 105), while the Uu interface supports cellular communications with infrastructure devices such as base stations. For example, the UEs 105 may use the PC5 interface for a radio resource control (RRC) signaling exchange between the UEs (also called PC5-RRC signaling). The PC5 / Uu interfaces are used only as an example, and PC5 as used herein may represent various other possible wireless communications technologies that allow for direct sidelink communications between user devices, while Uu in turn may represent cellular communications conducted between user devices and infrastructure devices, such as base stations.

[0050] In some implementations, the UEs 105 may be configured with parameters for communicating via the Uu interface and / or the sidelink interface. In some examples, the UEs 105 may be “pre-configured” with some parameters. In these examples, the parameters may be hardwired into the UEs 105 or coded into spec. Additionally and / or alternatively, the UEs 105 may receive the parameters from the one or more of the base stations 110.

[0051] To transmit / receive data to / from one or more base stations 110 or UEs 105, the UEs 105 may include a transmitter / receiver (or alternatively, a transceiver), memory, one or more processors, and / or other like components that enable the UEs 105 to operate in accordance with one or more wireless communications protocols and / or one or more cellular communications protocols. The UEs 105 may have multiple antenna elements that enable the UEs 105 to maintain multiple links 120 and / or sidelinks 125 to transmit / receive data to / from multiple base stations 110 and / or multiple UEs 105. For example, as shown in FIG. 1, UE 105-1 may connect with base station 110-1 via link 120 and simultaneously connect with UE 105-2 via sidelink 125.

[0052] In some implementations, one or more sidelink radio bearers may be established on the sidelink 125. The sidelink radio bearers can include signaling radio bearers (SL-SRB) and / or data radio bearers (SL-DRB).

[0053] The PC5 interface may alternatively be referred to as a sidelink interface and may include one or more logical channels, including but not limited to a Physical Sidelink Control Channel (PSCCH), a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Discovery Channel (PSDCH), a Physical Sidelink Broadcast Channel (PSBCH), Physical Sidelink Feedback Channel (PSFCH), and / or any other like communications channels. The PSFCH carries feedback related to the successful or failed reception of a sidelink transmission. The PSSCH can be scheduled by sidelink control information (SCI) carried in the sidelink PSCCH. In some examples, the sidelink interface can operate on an unlicensed spectrum (e.g., in the unlicensed 5 Gigahertz (GHz) and 6 GHz bands) or a (licensed) shared spectrum.

[0054] In one example, the sidelink interface implements vehicle-to-everything (V2X) communications. The V2X communications may, for example, adhere to 3 GPP Cellular V2X (C-V2X) specifications, or to one or more other or subsequent standards whereby vehicles and other devices and network entities may communicate. V2X communications may utilize both long-range (e.g., cellular) communications as well as short- to medium -range (e.g., non- cellular) communications. Cellular-capable V2X communications may be called Cellular V2X (C-V2X) communications. C-V2X systems may use various cellular radio access technologies (RATs), such as 4GLTE or 5GNRRATs (orRATs subsequent to 5G, e.g., 6GRATs). Certain LTE standards usable in V2X systems may be called LTE-Vehicle (LTE-V) standards. As used herein in the context of V2X systems, and as defined above, the term “user devices” may refer generally to devices that are associated with mobile actors or traffic participants in the V2X system, e.g., mobile (able-to-move) communication devices such as vehicles, pedestrian user equipment (PUE) devices, and roadside units (RSUs).

[0055] In some implementations, UEs 105 may be physical hardware devices capable of running one or more applications, capable of accessing network services via one or more radio links 120 with a corresponding base station 110 (also referred to as a “serving” base station), and capable of communicating with one another via sidelink 125. Link 120 may allow the UEs 105 to transmit and receive data from the base station 110 that provides the link 120. The sidelink 125 may allow the UEs 105 to transmit and receive data from one another. The sidelink 125 between the UEs 105 may include one or more channels for transmitting information fromUE 105-1 to UE 105-2 and vice versa and / or between UEs 105 and UE-type RSUs and vice versa.

[0056] In some implementations, the base stations 110 are capable of communicating with one another over a backhaul connection 130 and may communicate with the one or more servers 135 within the CN 140 over another backhaul connection 133. The backhaul connections can be wired and / or wireless connections.

[0057] In some implementations, the UEs 105 are configured to use a resource pool for sidelink communications. A sidelink resource pool defines the time-frequency resources used for sidelink communications, and may be divided into multiple time slots, frequency channels, and frequency sub-channels. In some examples, the UEs 105 are synchronized and perform sidelink transmissions aligned with slot boundaries. A UE may be expected to select several slots and sub-channels for transmission of the transport block. In some examples, a UE may use different sub-channels for transmission of the transport block across multiple slots within its own resource selection window.

[0058] In some implementations, an exceptional resource pool may be configured for the UEs 105, perhaps by the base stations 110. The exceptional resource pool includes resources that the UEs 105 can use in exceptional cases, such as Radio Link Failure (RLF). The exceptional resource pool may include resources selected based on a random allocation of resources.

[0059] In some implementations, a UE that is initiating a communication with another UE is referred to as a transmitter UE (TX UE), and the UE receiving the communication is referred to as a receiver UE (RX UE). For example, UE 105-1 may be a TX UE and UE 105-2 may be an RX UE. Although FIG. 1 illustrates a single TX UE communicating with a single RX UE, a TX UE may communicate with more than one RX UE via sidelink.

[0060] In some implementations, a TX UE that is initiating sidelink communication may determine the available resources (e.g., sidelink resources) and may select a subset of these resources to communicate with an RX UE based on a resource allocation scheme. Example resource allocation schemes include Mode 1 and Mode 2 resource allocation schemes. In Mode 1 resource allocation scheme (referred to as “Mode 1”), the resources are allocated by a network node for in-coverage UEs. In Mode 2 resource allocation scheme (referred to as “Mode 2”), the TX UE selects the sidelink resources (e.g., sidelink transmission resources).

[0061] In some implementations, the communication system 100 supports different cast types, including unicast, broadcast, and groupcast (or multicast) communications. Unicast refers to direction communications between two UEs. Broadcast refers to a communication that is broadcast by a single UE to a plurality of other UEs. Groupcast refers to communications that are sent from a single UE to a set of UEs that satisfy a certain condition (e.g., being a member of a particular group).

[0062] FIG. 2A illustrates an example scheme 200 for inter-UE coordination for resource allocation (RA). This scheme shows a proactive scheme in which a UE (such as one of UEs 105 of FIG. 1) is configured to send coordination information that specifies a set of preferred or non-preferred resources for SL-U transmissions by a second UE. The example IUC scheme 200 shows that the first UE (e.g., UE-A) communications to the second UE (e.g., UE-B) that a subset of resources is available, including {A3, B2, C4}. These resources are indicated to the second UE (UE-B) prior to UE-B’s resource reservation. In another example, the first UE (UE- A) can be configured to signal resources that are not preferred or unavailable for SL-U transmissions by the UE-B. In this example, the UE-A indicates a subset of resources including {A1,A2, A4, Bl, B3, B4, Cl, C2, C3} as being unavailable. The set of resources are indicated by UE-A to UE-B before UE-B’s resource reservation occurs.

[0063] The UE-A is configured to specify the list of resources that are either available or not available using modified SCI or a modified MAC CE. The SCI or MAC CE is modified because it specifies one or more RB set indexes for respective RB sets in which designated subchannels in the frequency domain are specified for use as SL-U resources. The UE-A indicates the RB set index to enable the SL-U transmissions from the UE-B to be interlaced on subchannels among a number of different RB sets. The fields of the SCI or MAC CE are subsequently described in further detail below. Specifically, fields of the modified MAC CEs are described in relation to FIGS. 4A-4C.

[0064] The IUC message contents for signaling using the scheme 200 can include the following. The first UE (e.g., UE-A) is associated with a resource pool configuration or preconfiguration. The resource pool configuration or configuration enables one of the following. For the indication of a resource set, the SCI or MAC CE can specify a number N combinations of resources using either time resource indicator values (TRIV) or frequency resource indicator values (FRIV) for an indicated resource reservation period. In some implementations, the value of resource reservation period is omitted at least when indicated in an explicit request of theUE-B. in some implementations, the first resource location of each TRIV is separately indicated by the UE-A.

[0065] As previously indicated, a MAC CE or the 2nd SCI format are used as a container for the IUC information transmission from UE-A to UE-B. In some implementations, for a small value of N combinations of resources, the UE-A uses the MAC CE. In some implementations, a UE implementation can additionally use SCI-2 for signaling these combinations. When the UE-A uses both the MAC CE and SCI-2 containers for signaling the combinations N, a same resource set is indicated in the MAC CE and the SCI-2 containers. In another example, for larger numbers N of combinations, the UE-A uses only a MAC CE. In some implementations, this threshold can be at N = 2. In another example, a MAC CE is used as the container of IUC information transmission from UE-A to UE-B without providing an option for SCI-2 as a container.

[0066] The second UE (UE-B) is configured to receive the preferred or non-preferred resources set in the SCI or MAC CE. The UE-B is configured to handle IUC specifying a non-preferred resource set during the resource selection procedure. Specifically, the physical layer at UE-B excludes in its resource selection or reselection the candidate single-slot resource(s) obtained after Step 6 of the resource selection procedure.

[0067] FIG. 2B illustrates an example scheme 210 for inter-UE coordination for resource allocation. The IUC scheme 210 is a reactive scheme because a first UE (UE-A) signals a potential resource conflict to UE-B, and UE-B schedules SL-U communications without using the identified conflicting resources. The coordination information sent from UE-A to UE-B indicates the presence of expected / potential resource conflicts on the resources indicated by UE-B’s SCI. As shown in FIG. 2B, the conflicting resources are shaded and labeled “UE-C,” “UE-B,” and “UE-B / UE-C.” In an aspect, the UE-A can send a PSFCH occasion instance having a format of 0 to indicate presence of expected resource conflict on reserved resource(s) indicated by UE-B’s SCI.

[0068] The UE-A can use the following PSFCH resources for IUC. In an aspect, the UE-A uses the same parameters for IUC that the UE-A uses for PSFCH for SL hybrid automatic repeat request (HARQ) messages. In this example, the UE-A uses a same period of the PSFCH resources as for SL HARQ, a same number of cycles shift pairs in a physical resource block as for SL HARQ, and a same number of PSFCH resources for multiplexing. In another aspect,the UE-A uses a separate parameter than as for PSFCH for SL HARQ. In this example, the UE-A uses a set of PRBs for PSFCH transmission and reception designated by the parameter.

[0069] The index of a PSFCH resource of UE-A for IUC transmission can be determined in a same manner as the PSFCH for SL HARQ is determined. Specifically, the index PID is an Ll- source identifier (ID) indicated by the SCI of UE-B’s. MID is the group member identifier. In sidelink groupcast, each receiver UE uses its group member ID to determine its own PSFCH resource. The value of MID is set to 0.

[0070] FIG. 3 illustrates an example PSFCH occasion mapping configuration 300 for the inter- UE coordination for RA scheme 310 of FIG. 2B. For UE-A’s PSFCH occasion mapping, the resource pool configuration or pre-configuration uses one of one or more options. In a first option, the PSFCH occasion that signals IUC resources is shown as occasion 302 which occurs after Time Gap 1. In this example, the UE-A derives the PSFCH occasion 302 by a slot 306 where UE-B’s SCI is transmitted. The UE-A is configured to reuse PSSCH-to-PSFCH timing to determine PSFCH occasion 302. The UE-A ensures that there is enough time for Time Gap 2 between PSFCH occasion 302 and a slot 308 with a resource conflict. In a second option, the UE-A derives the PSFCH occasion 304 based on the slot 308 where expected conflict is occurring. The UE-A is configured to ensure that Time Gap 2 is a large enough time gap between the PSFCH occasion 304 and expected conflict slot 308. The UE-A further ensures that Time Gap l is a large enough time gap between the PSFCH occasion 302 and the SCI 306 ofUE-B.

[0071] The UE-A configures the PSFCH occasion prioritization as follows. When a PSFCH transmission or reception for the IUC scheme 210 overlaps with long term evolution (LTE) SL transmissions or receptions (TX / RX) and / or uplink (UL) transmissions for a given UE, the UE- A is configured to reuse prioritization rules that apply for the PSFCH for SL HARQ.

[0072] In SCI format 1-A, if higher layer parameter transmissionStructureForPSCCHandPSSCH in SL-BWP-Config is configured, then Table 1 represents the 2nd-stage SCI formats for SL operation in the shared spectrum.Table 1: 2nd-stage SCI formats for SL operation in shared spectrum

[0073] FIGS. 4A-4B each illustrate an example MAC CE 400, 410, 420. Each of the MAC CEs provides information for inter-UE coordination for SL-U in accordance with the example scheme 200 of FIG. 2 A. MAC CE 400, MAC CE 410, and MAC CE 420 each include fields that specify resources for interlaced communication for SL-U. The MAC CEs include the SL MAC CE for IUC Information or a new sidelink MAC CE for inter-UE Coordination Information for SL-U.

[0074] Several fields are added to the SL MAC CE for IUC for SL-U. A first field is a LRL field that indicates lowest RB set indices for the first resource location of each time resource index value (TRIV). The size of the field can be 3 bits. In FIG. 4A, MAC CE 400 has fields marked LRIo and LRL. A second field includes a RCi field. The RCi field indicates a resource combination as the code point value of the SCI format 2-C resource combinations field. In an example, this specifies resources for retransmission locations. The field is 28 bits, as shown by sub field lengths (9+6+9+4) = 28 bits. A third field includes an MCSti field. The MCSti field indicates a number of consecutive slots for the allocated resources for SL-U.

[0075] FIG. 4C illustrates an example MAC CE for an inter-UE coordination request for SL- U in accordance with the example scheme 200 of FIG. 2A. The MAC CE 420 includes a modified sidelink MAC CE for IUC request or a new sidelink MAC CE for inter-UE Coordination request for SL-U. The added fields include a number of RB sets field which can be 3 bits. The fields include a number of sub-channels per RB set field that can be 4 bits. The fields include a MCSt field, as previously described. There is no field for a number of subchannels or a number of consecutive slots in the MAC CE 420.

[0076] The new fields of the MAC CEs 400, 410, and 420 enable a UE to specify or request resources for SL-U that are interlaced in different RB sets. Specifically, the UE can allocate resources on one or more consecutive subchannels in RBs of different RB sets. The resource pool for the UE-A for SL-U is subsequently described in further detail with respect to FIG. 5.

[0077] The UE-A can use SCI to specify resource allocation during IUC for SL-U. Specifically, the UE-A can specify the resource allocation using a set of new fields for SCI format 2-C. The fields specify which subchannels are being allocated, which RB sets are allocated, and what the lowest RB set index is for the first and second resources.

[0078] For interlaced RB-based PSCCH / PSSCH in which the higher layer parameter transmissionStructureForPSCCHandPSSCH is configured to interlace the RBs, the following fields are configurable by the UE-A for IUC for SL-U. If a providing or requesting indicator field is set to 0, the UE-A is providing available resources using IUC information, as described in 3GPP TS 38.212 Section 8.4.1.3 Rel 17. The fields can be configured as follows. A “resource combinations” field is modified to specify RB set indexes as shown:9 + K), where NRBset< 5 is the number of RB sets in resource pool and Nsubchannei 10 isthe number of sub-channels in an RB set.A lowest RB set indices field is defined as 2 • \log2NRBset)], where NRBset< 5 is the number of RB sets in resource pool and Nsubchannei 10 isthe number of sub-channels in an RB set.

[0079] A number of consecutive slots for MCSt field is defined as 2 • log2(Nmax-MCSt)], where Nmax-MCStis the maximum number of consecutive slots for a resource allocation.

[0080] If the providing or requesting indicator field is set to 1, the UE-A is sending an IUC request to the UE-B. The fields include a number of RB sets field defined as \log2(NRBset] bits. The fields include a number of sub-channels per RB set field defined as \log2bits. There is no field for the number of sub-channels. The number of consecutive slots for MCSt field is defined as Fg2(Nmax-MCSt) bits (e.g., 2 bits), where Nmax-Mcst is the maximum number of consecutive slots for a resource allocation.

[0081] FIG. 5 illustrates an example of a resource pool 500 for SL-U. Each RB set#0 to RB set#4 (5 total RB sets) has subchannels including subchannel #0 to subchannel #4 in the frequency domain. In this example, the selected indicated resources include sub-channel #3and sub-channel #4 of RB set #2 and RB set #3. The lowest sub-channel index for initial transmission is subchannel #3. The lowest RB set index for initial transmission is RB set index #2. The UE-A can signal these values in the fields of the MAC CE or the SCI as described previously in relation to FIGS. 2A-4C. As previously discussed, this IUC scheme 200 enables the UE-A to allocate resources interlaced among RB sets for SL-U.

[0082] FIG. 6 illustrates an example PSFCH occasion timing diagram 600 for the inter-UE coordination for RA scheme 210 of FIG. 2B. The scenario of timing diagram 600 occurs when the higher layer parameter sl-PSFCH-Occasion = ‘0.’ In the timing diagram 600, the PSFCH occasion 606 is sent by the UE-A after a configured minimum time gap “5 / - MinTimeGapPSFCFF after UE-B’s SCI 602. The PSFCH occasion 606 signaling resource availability is sent before a minimum time prior to the UE-B’s reserved resource with the collision 604. In other words, the PSFCH occasion is derived by a slot 602 where UE-B’s SCI is transmitted. Specifically, the UE-A transmits the PSFCH data on a first slot 606 that includes PSFCH resources and is at least the time gap “ sl-MinTimeGapPSFCFF of the resource pool after a slot 602 of a PSCCH reception that provides the SCI format 1-A. The PSFCH resource is in a slot 606 that is at least T3 slots before the resource 604 associated with the conflict information. In SL-U, multiple candidate PSFCH transmission occasions may be configured or pre-configured to N, N={1,2,3,4}. Multiple PSFCH occasions are counted by the UE-A starting from the first slot that includes PSFCH resource and at least sl-MinTimeGapPSFCH of the resource pool after a slot of a PSCCH reception that provides the SCI format 1-A. The UE-A can Continue counting until either N is reached or the PSFCH resource is not T3 slots before the resource associated with the conflict information. The UE-A’ s behavior on receiving PSFCH for conflict information is the same as receiving PSFCH for HARQ-ACK information in a unicast case. Specifically, a receiver UE (e.g., UE-B or third UE) attempts to monitor all candidate PSFCH occasion(s) satisfying the time gap limitations. If one PSFCH is detected, the receiver UE can omit monitoring following candidate PSFCH occasion(s), if any.

[0083] The UE-A’s behavior on transmitting PSFCH for conflict information is the same as transmitting PSFCH for HARQ-ACK information. Each PSFCH transmission is in a slot 606 that is at least sl-MinTimeGapPSFCH slots after UE-B’s SCI transmission and at least T3 slots before the resource associated with the conflict information. The first candidate PSFCH occasion is on the first slot (e.g., slot 606) which is at least sl-MinTimeGapPSFCH slots after UE-B’s SCI transmission, the second candidate PSFCH occasion is on the second slot (not shown) which is at least sl-MinTimeGapPSFCH slots after UE-B’s SCI transmission, and soforth for additional slots. Configurations showing multiple eligible PSFCH occasions are described in relation to FIGS. 7A-7B and FIGS. 9-10.

[0084] FIG. 7A illustrates an example timing diagram 700 for the inter-UE coordination for RA scheme of FIG. 2B. The timing diagram shows examples in which multiple PSFCH occasions 702, 704, and 706 are eligible for carrying RA conflict information for IUC for SL- U. In an example scenario, two candidate PSFCH transmission occasions are configured or pre-configured. In this example, two candidate PSFCH transmission occasions are reached, as shown by first and second PSFCH occasions.

[0085] FIG. 7B illustrates an example timing diagram 710 for the inter-UE coordination for RA scheme of FIG. 2B. The timing diagram shows examples in which multiple PSFCH occasions 712, 714, and 716 are eligible for carrying RA conflict information for IUC for SL- U. In this example, three candidate PSFCH transmission occasions are configured or preconfigured. However, in this example, only the first two (occasions 712 and 714) are reached, as the third occasion is within the minimum time gap T3 near the collision slot 720 for UE-B. Because the T3 limit is reached, only two PSFCH occasions are used.

[0086] FIG. 8 illustrates an example timing diagram 800 for the inter-UE coordination for RA scheme 210 of FIG. 2B. This shows the IUC scheme 210 in SL-U when the higher layer parameter sl-PSFCH-Occasion = ‘ 1.’ The PSFCH occasion is derived by a slot 804 where expected / potential resource conflict occurs on a PSSCH resource indicated by UE-B’s SCI 802. The UE-A transmits the PSFCH in a latest slot 806 that includes PSFCH resources and is at least T3 slots of the resource pool before a slot of the resource associated with conflict information. The PSFCH resource is in a slot 806 that is at least sl-MinTimeGapPSFCH slots after a slot 802 of a PSCCH reception that provides the SCI format 1-A. In SL-U, multiple candidate PSFCH transmission occasions may be configured or pre-configured to N, N={1,2,3,4}.

[0087] FIG. 9 shows a timing diagram 900 including examples I, II, and III for counting PSFCH resources between the SCI slot 802 and the conflict resource slot 804. Here, a number of qualified candidate PSFCH transmission occasions is greater than or equal to a number of configured or pre-configured candidate PSFCH transmissions occasions. Two candidate PSFCH transmission occasions are configured or pre-configured. Three candidate PSFCH transmission occasions meet the time gap restrictions (e.g., there are three qualified candidate PSFCH transmission occasions).

[0088] In a first example (I), multiple PSFCH occasions are counted starting from a latest slot that includes PSFCH resources such that the Nth candidate PSFCH resource after that slot is at least T3 slots of the resource pool before a slot of the resource associated with conflict information. The PSFCH resource is in a slot 806 that is at least sl-MinTimeGapPSFCH slots after a slot of a PSCCH reception that provides the SCI format 1-A 802. A given UE’s behavior on receiving PSFCH for conflict information is the same as receiving PSFCH for HARQ-ACK information in a unicast case. A given UE’s behavior on transmitting PSFCH for conflict information is the same as transmitting PSFCH for HARQ-ACK information, where each PSFCH transmission is in a slot that is at least sl-MinTimeGapPSFCH slots after UE-B’s SCI transmission and at least slots before the resource associated with the conflict information. The Nth candidate PSFCH occasion is in a latest slot that includes PSFCH resources and at least slots before a slot of the resource associated with conflict information, the (N - l)th candidate PSFCH occasion is in a second latest slot that include includes PSFCH resources and at least slots before a slot of the resource associated with conflict information, and so forth. Here, N is the number of candidate PSFCH occasions for a PSCCH / PSSCH transmission.

[0089] In a second example (II), multiple PSFCH occasions are counted starting from a first slot that includes PSFCH resources and is at least sl-MinTimeGapPSFCH slots after a slot of a PSCCH reception that provides the SCI format 1-A 802. In this example, the sl-PSFCH- Occasion = ‘ 1 ’ is not different from sl-PSFCH-Occasion = ‘0’ case, or the configuration of sl- PSFCH-Occasion = ‘ 1’ is not valid in SL-U.

[0090] In a third example (III), a backward counting approach is used for identifying the PSFCH occasions. Multiple PSFCH occasions are counted starting from a latest slot 806 that includes PSFCH resources is at least T3 slots of the resource pool before a slot of the resource associated with conflict information, backward to the previous available candidate PSFCH resource(s). The PSFCH resource is in a slot that is at least sl-MinTimeGapPSFCH slots after a slot of a PSCCH reception that provides the SCI format 1-A 802.

[0091] FIG. 10 illustrates an example timing diagram 1000 for the inter-UE coordination for RA scheme 210 of FIG. 2B. In this example, a number of qualified candidate PSFCH transmission occasions is less than the number of configured or pre-configured candidate PSFCH transmissions occasions. Here, four candidate PSFCH transmission occasions are configured or pre-configured. Three candidate PSFCH transmission occasions 1004, 1006, and 1008 meet the time gap restrictions, and occasion 1002 does not qualify.

[0092] In a first example (I), the three PSFCH occasions are selected by counting the multiple PSFCH occasions starting from a first slot after the sl-MinTimeGapPSFCH timing gap is satisfied. Here, occasions 1004, 1006, and 1008 are each selected as shown. In the second example (II), the PSFCH occasions are selected by counting starting from a latest slot that includes PSFCH resources such that the Nth candidate PSFCH resource after that slot is at least T3 slots of the resource pool before a slot of the resource associated with conflict information. Here, the fourth, third, and second occasions are identified. This is similar to the first example (I) described in relation to FIG. 9. In a third example (III), a backward counting approach is used for identifying the PSFCH occasions. Multiple PSFCH occasions are counted starting from a latest slot 1008 that includes PSFCH resources is at least T3 slots of the resource pool before a slot of the resource associated with conflict information, backward to the previous available candidate PSFCH resource(s). This is similar to example (III) described in relation to FIG. 9.

[0093] FIG. 11A illustrates a flowchart of an example method 1100, according to some implementations. For clarity of presentation, the description that follows generally describes method 1100 in the context of the other figures in this description. For example, method 1100 can be performed by UE 105 of FIG. 1. It will be understood that method 1100 can be performed, for example, by any suitable system, environment, software, hardware, or a combination of systems, environments, software, and hardware, as appropriate. In some implementations, various steps of method 1100 can be run in parallel, in combination, in loops, or in any order.

[0094] The process 1100 includes transmitting (1102), from a first user equipment (UE) to a second UE, inter-UE coordination (IUC) information for resource allocation for unlicensed sidelink (SL-U) communication, the IUC information specifying one or more available resources for SL-U communication for interlaced transmissions between at least two resource block (RB) sets. The process 1100 includes performing (1104) a SL-U communication using at least one resource specified in the IUC information.

[0095] The example method 1100 shown in FIG. 11A can be modified or reconfigured to include additional, fewer, or different steps (not shown in FIG. 11 A), which can be performed in the order shown or in a different order. In some implementations, the IUC information causes a physical layer in the second UE to exclude in resource selection or reselection the one ormore available resources of the IUC information from candidate single-slot resources obtained during a resource selection procedure.

[0096] In some implementations, the IUC information includes one or more combinations of timing resource index values (TRIV). In some implementations, the TRIV includes a first resource location including a resource block (RB) set index. In some implementations, the IUC information includes one or more combinations of frequency resource index values (FRIV).

[0097] In some implementations, the IUC information is transmitted in a medium access control (MAC) control element (CE). In some implementations, the IUC information is transmitted in the MAC CE and in sidelink control information (SCI) format 2. In some implementations, the SCI includes a field specifying a number of subchannels for each of one or more RB sets. In some implementations, the SCI includes a field specifying a number of RB sets. In some implementations, the SCI includes a field specifying a number of consecutive slots for resource allocation. In some implementations, the SCI includes a field specifying a lowest RB set index. In some implementations, the SCI includes a field specifying that SL-U uses interlaced RB sets. In some implementations, the SCI includes a field specifying a number of subchannels and a number of RB sets from a resource pool. In some implementations, the MAC CE is a MAC CE for IUC information, and wherein the MAC CE for information includes a field specifying lowest RB set indices for a first resource location of each TRIV. In some implementations, the MAC CE is a MAC CE for IUC information, and wherein the MAC CE for information includes a field specifying a resource combination as a code point value of SCI format 2-C. In some implementations, the MAC CE is a MAC CE for IUC information, and wherein the MAC CE for information includes a field specifying a number of consecutive slots. In some implementations, the MAC CE is a MAC CE for an IUC request, and wherein the MAC CE for the request includes a field specifying a number of RB sets. In some implementations, the MAC CE is a MAC CE for an IUC request, and wherein the MAC CE for the request includes a field specifying a number of sub-channels per RB set. In some implementations, the MAC CE is a MAC CE for an IUC request, and wherein the MAC CE for the request includes a field specifying a number of consecutive slots.

[0098] FIG. 11B illustrates a flowchart of an example method 1120, according to some implementations. For clarity of presentation, the description that follows generally describes method 1120 in the context of the other figures in this description. For example, method 1120 can be performed by UE 105 of FIG. 1. It will be understood that method 1120 can beperformed, for example, by any suitable system, environment, software, hardware, or a combination of systems, environments, software, and hardware, as appropriate. In some implementations, various steps of method 1120 can be run in parallel, in combination, in loops, or in any order.

[0099] The process 1120 includes identifying (1122) one or more candidate physical sidelink feedback channel (PSFCH) occasions for specifying inter-UE coordination (IUC) information for resource allocation for unlicensed sidelink (SL-U) communication for a first UE. The IUC information specifies at least one conflicting resource from sidelink control information (SCI) transmission by a second UE. The process 1120 includes transmitting (1124), from a first user equipment (UE) to a second UE, PSFCH data on the identified one or more candidate PSFCH occasions, the PSFCH data specifying the at least one conflicting resource.

[0100] The example method 1120 shown in FIG. 11B can be modified or reconfigured to include additional, fewer, or different steps (not shown in FIG. 1 IB), which can be performed in the order shown or in a different order. In some implementations, the PSFCH occasion is selected as a first available candidate slot in a resource pool after a predetermined time gap after the SCI transmission by the second UE. In some implementations, the PSFCH occasion is at least a predetermined time before the at least one conflicting resource. In some implementations, the second UE is configured to monitor all candidate PSFCH occasions that are after a first time gap after the SCI transmission by the second UE and before a second time gap prior to the at least one conflicting resource. In some implementations, the second UE stops monitoring PSFCH occasions responsive to detecting the PSFCH data from the first UE.

[0101] In some implementations, a number of candidate PSFCH occasions is one of 1, 2, 3, or 4.

[0102] In some implementations, a first candidate PSFCH occasion is on a first slot which is at least a predetermined number of slots after the SCI transmission of the second UE, and wherein a second candidate PSFCH occasion is on a second slot which is at least the predetermined number of slots after the SCI transmission of the second UE.

[0103] In some implementations, the PSFCH occasion is selected as a last available candidate slot in a resource pool prior to a predetermined time gap prior to the at least one conflicting resource of second UE.

[0104] In some implementations, multiple PSFCH occasions are counted starting from the last available slot in the resource pool that includes PSFCH resources.

[0105] In some implementations, multiple PSFCH occasions are counted starting from a first available slot in the resource pool that includes PSFCH resources and that satisfies a predetermined time gap from the SCI transmission of the second UE. In some implementations, multiple PSFCH occasions are counted starting from the last available slot in the resource pool that includes PSFCH resources backward to previous candidate PSFCH resources.

[0106] FIG. 12 illustrates an example UE 1200, according to some implementations. The UE 1200 may be similar to and substantially interchangeable with UEs 105 of FIG. 1.

[0107] The UE 1200 may be any mobile or non-mobile computing device, such as, for example, mobile phones, computers, tablets, industrial wireless sensors (for example, microphones, pressure sensors, thermometers, motion sensors, accelerometers, inventory sensors, electric voltage / current meters, etc.), video devices (for example, cameras, video cameras, etc.), wearable devices (for example, a smart watch), relaxed-IoT devices.

[0108] The UE 1200 may include processors 1202, RF interface circuitry 1204, memory / storage 1206, user interface 1208, sensors 1210, driver circuitry 1212, power management integrated circuit (PMIC) 1214, one or more antenna(s) 1216, and battery 1218. The components of the UE 1200 may be implemented as integrated circuits (ICs), portions thereof, discrete electronic devices, or other modules, logic, hardware, software, firmware, or a combination thereof. The block diagram of FIG. 12 is intended to show a high-level view of some of the components of the UE 1200. However, some of the components shown may be omitted, additional components may be present, and different arrangement of the components shown may occur in other implementations.

[0109] The components of the UE 1200 may be coupled with various other components over one or more interconnects 1220, which may represent any type of interface, input / output, bus (local, system, or expansion), transmission line, trace, optical connection, etc. that allows various circuit components (on common or different chips or chipsets) to interact with one another.

[0110] The processors 1202 may include processor circuitry such as, for example, baseband processor circuitry (BB) 1222A, central processor unit circuitry (CPU) 1222B, and graphics processor unit circuitry (GPU) 1222C. The processors 1202 may include any type of circuitryor processor circuitry that executes or otherwise operates computer-executable instructions, such as program code, software modules, or functional processes from memory / storage 1206 to cause the UE 1200 to perform operations as described herein.[OHl] In some implementations, the baseband processor circuitry 1222 A may access a communication protocol stack 1224 in the memory / storage 1206 to communicate over a 3 GPP compatible network. In general, the baseband processor circuitry 1222 A may access the communication protocol stack to perform user plane functions at a physical (PHY) layer, medium access control (MAC) layer, radio link control (RLC) layer, packet data convergence protocol (PDCP) layer, service data adaptation protocol (SDAP) layer, and PDU layer; and perform control plane functions at a PHY layer, MAC layer, RLC layer, PDCP layer, RRC layer, and a non-access stratum layer. In some implementations, the PHY layer operations may additionally / altematively be performed by the components of the RF interface circuitry 1204. The baseband processor circuitry 1222 A may generate or process baseband signals or waveforms that carry information in 3 GPP-compatible networks. In some implementations, the waveforms for NR may be based cyclic prefix orthogonal frequency division multiplexing (OFDM) “CP-OFDM” in the uplink or downlink, and discrete Fourier transform spread OFDM “DFT-S-OFDM” in the uplink.

[0112] The memory / storage 1206 may include one or more non -transitory, computer-readable media that includes instructions (for example, communication protocol stack 1224) that may be executed by one or more of the processors 1202 to cause the UE 1200 to perform various operations described herein. The memory / storage 1206 include any type of volatile or nonvolatile memory that may be distributed throughout the UE 1200. In some implementations, some of the memory / storage 1206 may be located on the processors 1202 themselves (for example, LI and L2 cache), while other memory / storage 1206 is external to the processors 1202 but accessible thereto via a memory interface. The memory / storage 1206 may include any suitable volatile or non-volatile memory such as, but not limited to, dynamic random access memory (DRAM), static random access memory (SRAM), erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), Flash memory, solid-state memory, or any other type of memory device technology.

[0113] The RF interface circuitry 1204 may include transceiver circuitry and radio frequency front module (RFEM) that allows the UE 1200 to communicate with other devices over a radio access network. The RF interface circuitry 1204 may include various elements arranged intransmit or receive paths. These elements may include, for example, switches, mixers, amplifiers, filters, synthesizer circuitry, control circuitry, etc.

[0114] In the receive path, the RFEM may receive a radiated signal from an air interface via antenna(s) 1216 and proceed to filter and amplify (with a low-noise amplifier) the signal. The signal may be provided to a receiver of the transceiver that downconverts the RF signal into a baseband signal that is provided to the baseband processor of the processors 1202.

[0115] In the transmit path, the transmitter of the transceiver up-converts the baseband signal received from the baseband processor and provides the RF signal to the RFEM. The RFEM may amplify the RF signal through a power amplifier prior to the signal being radiated across the air interface via the antenna(s) 1216. In various implementations, the RF interface circuitry 1204 may be configured to transmit / receive signals in a manner compatible with NR access technologies.

[0116] The antenna(s) 1216 may include one or more antenna elements to convert electrical signals into radio waves to travel through the air and to convert received radio waves into electrical signals. The antenna elements may be arranged into one or more antenna panels. The antenna(s) 1216 may have antenna panels that are omnidirectional, directional, or a combination thereof to enable beamforming and multiple input, multiple output communications. The antenna(s) 1216 may include microstrip antennas, printed antennas fabricated on the surface of one or more printed circuit boards, patch antennas, phased array antennas, etc. The antenna(s) 1216 may have one or more panels designed for specific frequency bands including bands in FR1 or FR2.

[0117] The user interface 1208 includes various input / output (VO) devices designed to enable user interaction with the UE 1200. The user interface 1208 includes input device circuitry and output device circuitry. Input device circuitry includes any physical or virtual means for accepting an input including, inter alia, one or more physical or virtual buttons (for example, a reset button), a physical keyboard, keypad, mouse, touchpad, touchscreen, microphones, scanner, headset, or the like. The output device circuitry includes any physical or virtual means for showing information or otherwise conveying information, such as sensor readings, actuator position(s), or other like information. Output device circuitry may include any number or combinations of audio or visual display, including, inter alia, one or more simple visual outputs / indicators (for example, binary status indicators such as light emitting diodes “LEDs” and multi -character visual outputs), or more complex outputs such as display devices ortouchscreens (for example, liquid crystal displays “LCDs,” LED displays, quantum dot displays, projectors, etc.), with the output of characters, graphics, multimedia objects, and the like being generated or produced from the operation of the UE 1200.

[0118] The sensors 1210 may include devices, modules, or subsystems whose purpose is to detect events or changes in its environment and send the information (sensor data) about the detected events to some other device, module, subsystem, etc. Examples of such sensors include, inter alia, inertia measurement units including accelerometers, gyroscopes, or magnetometers; microelectromechanical systems or nanoelectromechanical systems including 3-axis accelerometers, 3-axis gyroscopes, or magnetometers; level sensors; temperature sensors (for example, thermistors); pressure sensors; image capture devices (for example, cameras or lensless apertures); light detection and ranging sensors; proximity sensors (for example, infrared radiation detector and the like); depth sensors; ambient light sensors; ultrasonic transceivers; microphones or other like audio capture devices; etc.

[0119] The driver circuitry 1212 may include software and hardware elements that operate to control particular devices that are embedded in the UE 1200, attached to the UE 1200, or otherwise communicatively coupled with the UE 1200. The driver circuitry 1212 may include individual drivers allowing other components to interact with or control various input / output (I / O) devices that may be present within, or connected to, the UE 1200. For example, driver circuitry 1212 may include a display driver to control and allow access to a display device, a touchscreen driver to control and allow access to a touchscreen interface, sensor drivers to obtain sensor readings of sensors 1210 and control and allow access to sensors 1210, drivers to obtain actuator positions of electro-mechanic components or control and allow access to the electro-mechanic components, a camera driver to control and allow access to an embedded image capture device, audio drivers to control and allow access to one or more audio devices.

[0120] The PMIC 1214 may manage power provided to various components of the UE 1200. In particular, with respect to the processors 1202, the PMIC 1214 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion.

[0121] In some implementations, the PMIC 1214 may control, or otherwise be part of, various power saving mechanisms of the UE 1200. A battery 1218 may power the UE 1200, although in some examples the UE 1200 may be mounted deployed in a fixed location and may have a power supply coupled to an electrical grid. The battery 1218 may be a lithium ion battery, a metal-air battery, such as a zinc-air battery, an aluminum-air battery, a lithium-air battery, andthe like. In some implementations, such as in vehicle-based applications, the battery 1218 may be a typical lead-acid automotive battery.

[0122] FIG. 13 illustrates an example access node 1300 (e.g., a base station or gNB), according to some implementations. The access node 1300 may be similar to and substantially interchangeable with base stations 110. The access node 1300 may include processors 1302, RF interface circuitry 1304, core network (CN) interface circuitry 1306, memory / storage circuitry 1308, and one or more antenna(s) 1310.

[0123] The components of the access node 1300 may be coupled with various other components over one or more interconnects 1312. The processors 1302, RF interface circuitry 1304, memory / storage circuitry 1308 (including communication protocol stack 1314), antenna(s) 1310, and interconnects 1312 may be similar to like-named elements shown and described with respect to FIG. 12. For example, the processors 1302 may include processor circuitry such as, for example, baseband processor circuitry (BB) 1316A, central processor unit circuitry (CPU) 1316B, and graphics processor unit circuitry (GPU) 1316C.

[0124] The CN interface circuitry 1306 may provide connectivity to a core network, for example, a 5th Generation Core network (5GC) using a 5GC -compatible network interface protocol such as carrier Ethernet protocols, or some other suitable protocol. Network connectivity may be provided to / from the access node 1300 via a fiber optic or wireless backhaul. The CN interface circuitry 1306 may include one or more dedicated processors or FPGAs to communicate using one or more of the aforementioned protocols. In some implementations, the CN interface circuitry 1306 may include multiple controllers to provide connectivity to other networks using the same or different protocols.

[0125] As used herein, the terms “access node,” “access point,” or the like may describe equipment that provides the radio baseband functions for data and / or voice connectivity between a network and one or more users. These access nodes can be referred to as BS, gNBs, RAN nodes, eNBs, NodeBs, RSUs, TRxPs or TRPs, and so forth, and can include ground stations (e.g., terrestrial access points) or satellite stations providing coverage within a geographic area (e.g., a cell). As used herein, the term “NG RAN node” or the like may refer to an access node 1300 that operates in an NR or 5G system (for example, a gNB), and the term “E-UTRAN node” or the like may refer to an access node 1300 that operates in an LTE or 4G system (e.g., an eNB). According to various implementations, the access node 1300 may be implemented as one or more of a dedicated physical device such as a macrocell base station,and / or a low power (LP) base station for providing femtocells, picocells or other like cells having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells.

[0126] In some implementations, all or parts of the access node 1300 may be implemented as one or more software entities running on server computers as part of a virtual network, which may be referred to as a CRAN and / or a virtual baseband unit pool (vBBUP). In V2X scenarios, the access node 1300 may be or act as a “Roadside Unit.” The term “Roadside Unit” or “RSU” may refer to any transportation infrastructure entity used for V2X communications. An RSU may be implemented in or by a suitable RAN node or a stationary (or relatively stationary) UE, where an RSU implemented in or by a UE may be referred to as a “UE-type RSU,” an RSU implemented in or by an eNB may be referred to as an “eNB-type RSU,” an RSU implemented in or by a gNB may be referred to as a “gNB-type RSU,” and the like.

[0127] Various components may be described as performing a task or tasks, for convenience in the description. Such descriptions should be interpreted as including the phrase “configured to.” Reciting a component that is configured to perform one or more tasks is expressly intended not to invoke 35 U.S.C. § 112(f) interpretation for that component.

[0128] For one or more embodiments, at least one of the components set forth in one or more of the preceding figures may be configured to perform one or more operations, techniques, processes, or methods as set forth in the example section below. For example, the baseband circuitry as described above in connection with one or more of the preceding figures may be configured to operate in accordance with one or more of the examples set forth below. For another example, circuitry associated with a UE, base station, network element, etc. as described above in connection with one or more of the preceding figures may be configured to operate in accordance with one or more of the examples set forth below in the example section.Examples

[0129] Example 1 includes a method includes transmitting, from a first user equipment (UE) to a second UE, inter-UE coordination (IUC) information for resource allocation for an unlicensed sidelink (SL-U) communication, the IUC information indicating one or more available resources for SL-U communication for interlaced transmissions between at least two resource block (RB) sets; and performing a SL-U communication using at least one resource specified in the IUC information.

[0130] Example 2 includes the method of example 1, wherein the IUC information is included in sidelink control information (SCI) format, and wherein a field of the SCI format indicatesa resource pool, where N^bBbanneiindicates a number of sub channels in an RB set, and where Y=[log2lVrsv period],anc^ ^rsv_period includes a number of entries in a resource reserve period list, when configured, or 0 otherwise.

[0131] Example 3 include the method of example 1 or example 2, the IUC information indicates lowest RB set indices using 2 ■ [log2NRBset] bits.

[0132] Example 4 includes the method of any of examples 1 through 3, wherein NRBset< 5 and N^bs^annel< 10.

[0133] Example 5 includes the method of any of examples 1 through 4, wherein the IUC information is provided responsive to an IUC request, wherein the IUC request includes a field indicating a number of RB sets in a resource pool NRBsetusing [log2(iVRBset)] bits.

[0134] Example 6 includes the method of any of examples 1 through 5, wherein the IUC information is provided responsive to an IUC request, wherein the IUC request includes a field indicating a number of sub channels per RB set N^bs^annelusing [log2N^bs^annel)] bits.

[0135] Example 7 includes the method of any of examples 1 through 6, wherein the IUC information indicates a number of consecutive slots for the SL-U communication, the number of consecutive slots being 2 - [log2^Nmax-MCSt')] where Nmax-MCStis the maximum of consecutive slots for a resource allocation.

[0136] Example 8 includes the method of any of examples 1 through 7, wherein sidelink control information (SCI) includes a first field indicating a number of subchannels for each of one or more RB sets from a resource pool, a second field indicating a number of RB sets from the resource pool, a third field indicating a number of consecutive slots for resource allocation, a fourth field indicating a lowest RB set index, and a fifth field indicating that SL-U uses interlaced RB sets.

[0137] Example 9 includes the method of any of examples 1 through 8, wherein a medium access control (MAC) control element (CE) for the IUC information includes a field that indicates lowest RB set indices for a first resource location of each timing resource index values (TRIV), the field being 4 or fewer bits.

[0138] Example 10 includes the method of any of examples 1 through 9, wherein a medium access control (MAC) control element (CE) for the IUC information includes a field that indicates a resource combination as a code point value of SCI format 2-C, the field being 28 or fewer bits.

[0139] Example 11 includes the method of any of examples 1 through 10, wherein a medium access control (MAC) control element (CE) is for an IUC request, and wherein the MAC CE indicates a number of RB sets.

[0140] Example 12 includes the method of any of examples 1 through 11, wherein a medium access control (MAC) control element (CE) is for an IUC request, and wherein the MAC CE indicates a number of sub channels per RB set and a number of RB sets.

[0141] Example 13 includes the method of any of examples 1 through 12, wherein the IUC information indicates lowest sub channel indices as 2 ■ log2N fubchannei] bits, where N subchannel indicates a number of sub channels in an RB set, and wherein the IUC information indicates a number of sub channels as log2N fubchannei] bits, where N fubchannei indicates a number of sub channels in an RB set.

[0142] Example 14 includes the method of any of examples 1 through 13, wherein the IUC information indicates a number of RB sets as [log2NRBset] bits, where NRBsetindicates a number of RB sets in a resource pool; and wherein the IUC information indicates a number of sub channels per RB set as log2N ^channel ] bits, where N Subchannel isanumber of RB sets per sub channel.

[0143] Example 15 includes a method comprising: identifying one or more candidate physical sidelink feedback channel (PSFCH) occasions for specifying inter-UE coordination (IUC) information for resource allocation for unlicensed sidelink (SL-U) communication for a first UE, the IUC information specifying at least one conflicting resource from sidelink control information (SCI) transmission by a second UE; and transmitting, from a first user equipment (UE) to a second UE, PSFCH data on a PSFCH occasion of the identified one or more candidate PSFCH occasions, the PSFCH data specifying the at least one conflicting resource.

[0144] Example 16 includes the method of example 15, wherein the PSFCH occasion is identified as a first available candidate slot in a resource pool after a predetermined time gap after the SCI transmission by the second UE.

[0145] Example 17 includes the method of any of examples 15 through 16, wherein the PSFCH occasion is at least a predetermined time before the at least one conflicting resource.

[0146] Example 18 includes the method of any of examples 15 through 17, wherein the second UE is configured to monitor all candidate PSFCH occasions that are after a first time gap after the SCI transmission by the second UE and before a second time gap prior to the at least one conflicting resource.

[0147] Example 19 includes the method of any of examples 15 through 18, wherein the second UE stops monitoring PSFCH occasions responsive to detecting the PSFCH data from the first UE.

[0148] Example 20 includes the method of any of examples 15 through 19, wherein a number of candidate PSFCH occasions is one of 1, 2, 3, or 4.

[0149] Example 21 includes the method of any of examples 15 through 20, wherein a first candidate PSFCH occasion is on a first slot which is at least a predetermined number of slots after the SCI transmission of the second UE, and wherein a second candidate PSFCH occasion is on a second slot which is at least the predetermined number of slots after the SCI transmission of the second UE.

[0150] Example 22 includes the method of any of examples 15 through 21, wherein the PSFCH occasion is selected as a last available candidate slot in a resource pool prior to a predetermined time gap prior to a slot of the at least one resource associated with conflict information of the second UE.

[0151] Example 23 includes the method of any of examples 15 through 22, wherein multiple PSFCH occasions are counted starting from the last available slot in a resource pool that includes PSFCH resources.

[0152] Example 24 includes the method of any of examples 15 through 23, wherein a last candidate PSFCH occasion is on a last slot which is at least a predetermined number of slots before a slot of the resource associated with conflict information of the second UE, and wherein a second last candidate PSFCH occasion is on a second last slot which is at least the predetermined number of slots before a slot of the resource associated with the conflict information.

[0153] Example 25 includes the method of any of examples 1 through 24, wherein multiple PSFCH occasions are counted starting from a first available slot in a resource pool that includes PSFCH resources and that satisfies a predetermined time gap from the SCI transmission of the second UE.

[0154] Example 26 includes the method of any of examples 1 through 25, wherein multiple PSFCH occasions are counted starting from the last available slot in a resource pool before a slot of the resource associated with conflict information of the second UE and that includes PSFCH resources backward to previous candidate PSFCH resources.

[0155] Example 27 includes a method comprising: identifying one or more candidate physical sidelink feedback channel (PSFCH) occasions for specifying inter-UE coordination (IUC) information for resource allocation for unlicensed sidelink (SL-U) communication for a first UE, the IUC information specifying at least one conflicting resource from sidelink control information (SCI) transmission by a second UE; and receiving, at a first user equipment (UE) from a second UE, PSFCH data on a PSFCH occasion of the identified one or more candidate PSFCH occasions, the PSFCH data specifying the at least one conflicting resource.

[0156] Example 28 includes the method of example 27, wherein the first UE attempts to receive the PSFCH data on a set of first available candidate slots indexed in ascending order in time that include PSFCH resources and that are at least a given number of slots after a last slot of a PSSCH reception that provides the SCI format until the first UE detects a PSFCH with conflict information.

[0157] Example 29 includes the method of any of examples 27 through 28, wherein the first UE attempts to receive the PSFCH data when the slot is at least a given time before the PSFCH with conflict information.

[0158] Example 30 includes the method of any of examples 27 through 29, wherein the first UE attempts to receive the PSFCH data on a set of latest available candidate slots indexed in ascending order in time that include PSFCH resources and that are at least a given number of slots before a slot including a PSFCH with conflict information until the first UE detects the PSFCH with conflict information.

[0159] Example 31 includes the method of any of examples 27 through 30, wherein the first UE attempts to receive the PSFCH with conflict information when the PSFCH resource is in a slot that is at least a given number of slots after a slot of a PSCCH transmission that provides the SCI.

[0160] Example 32 includes a system comprising one or more computers and one or more storage devices on which are stored instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations of any of examples 1 through 31.

[0161] Example 33 includes a system comprising one or more computers and one or more storage devices on which are stored instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations of any of examples 1 through 31.

[0162] Example 34 includes a non-transitory computer storage medium encoded with instructions that, when executed by one or more computers, cause the one or more computers to perform operations of any of examples 1 through 31.

[0163] Example 35 includes an apparatus comprising one or more baseband processors configured to perform operations of the method of any of any of examples 1 through 31.

[0164] Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.

[0165] It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

Claims

WHAT IS CLAIMED IS:

1. One or more processors configured to, when executing instructions stored in a memory, perform operations comprising: transmitting, from a first user equipment (UE) to a second UE, inter-UE coordination (IUC) information for resource allocation for an unlicensed sidelink (SL-U) communication, the IUC information indicating one or more available resources for SL-U communication for interlaced transmissions between at least two resource block (RB) sets; and performing a SL-U communication using at least one resource specified in the IUC information.

2. The one or more processors of claim 1, wherein the IUC information is included in sidelink control information (SCI) format, and wherein a field of the SCI format indicates resource combinations including:where NRBsetindicates a number of RB sets in a resource pool, where Nsubchannei indicates a number of sub channels in an RB set, and where Y = [log27Vrsv period, and iVrsv periodincludes a number of entries in a resource reserve period list, when configured, or 0 otherwise.

3. The one or more processors of claim 2, wherein the IUC information indicates lowest RB set indices using 2 ■ [log2NRBset] bits.

4. The one or more processors of claim 2, wherein NRBset< 5 and Nsubchannei10.

5. The one or more processors of claim 1, wherein the IUC information is provided responsive to an IUC request, wherein the IUC request includes a field indicating a number of RB sets in a resource pool NRBsetusing [log2(lVRBset)] bits.

6. The one or more processors of claim 1, wherein the IUC information is provided responsive to an IUC request, wherein the IUC request includes a field indicating a number of sub channels per RB set N subchannel using \\og2(NsR^bs^ianneL)] bits.

7. The one or more processors of claim 1, wherein the IUC information indicates a number of consecutive slots for the SL-U communication, the number of consecutive slots being 2 • [log2^Nmax-MCSt')] where Nmax-MCStis the maximum of consecutive slots for a resource allocation.

8. The one or more processors of claim 1, wherein sidelink control information (SCI) includes a first field indicating a number of subchannels for each of one or more RB sets from a resource pool, a second field indicating a number of RB sets from the resource pool, a third field indicating a number of consecutive slots for resource allocation, a fourth field indicating a lowest RB set index, and a fifth field indicating that SL-U uses interlaced RB sets.

9. The one or more processors of claim 1, wherein a medium access control (MAC) control element (CE) for the IUC information includes a field that indicates lowest RB set indices for a first resource location of each timing resource index values (TRIV), the field being 4 or fewer bits.

10. The one or more processors of claim 1, wherein a medium access control (MAC) control element (CE) for the IUC information includes a field that indicates a resource combination as a code point value of SCI format 2-C, the field being 28 or fewer bits.

11. The one or more processors of claim 1, wherein a medium access control (MAC) control element (CE) is for an IUC request, and wherein the MAC CE indicates a number of RB sets.

12. The one or more processors of claim 1, wherein a medium access control (MAC) control element (CE) is for an IUC request, and wherein the MAC CE indicates a number of sub channels per RB set and a number of RB sets.

13. The one or more processors of claim 1, wherein the IUC information indicates lowest sub channel indices as 2 ■ log2N fubchannei] bits, where N fubchannei indicates a number of sub channels in an RB set, andwherein the IUC information indicates a number of sub channels as log2N fubchannei bits, where N fubchannei indicates a number of sub channels in an RB set.

14. The one or more processors of claim 1, wherein the IUC information indicates a number of RB sets as [log2NRBset] bits, where NRBsetindicates a number of RB sets in a resource pool; and wherein the IUC information indicates a number of sub channels per RB set as log2N Subchannel] bits, where N Subchannel is anumber of RB sets per sub channel.

15. A method comprising: identifying one or more candidate physical sidelink feedback channel (PSFCH) occasions for specifying inter-UE coordination (IUC) information for resource allocation for unlicensed sidelink (SL-U) communication for a first UE, the IUC information specifying at least one conflicting resource from sidelink control information (SCI) transmission by a second UE; and transmitting, from a first user equipment (UE) to a second UE, PSFCH data on a PSFCH occasion of the identified one or more candidate PSFCH occasions, the PSFCH data specifying the at least one conflicting resource.

16. The method of claim 15, wherein the PSFCH occasion is identified as a first available candidate slot in a resource pool after a predetermined time gap after the SCI transmission by the second UE.

17. The method of claim 15, wherein the PSFCH occasion is at least a predetermined time before the at least one conflicting resource.

18. The method of claim 15, wherein the second UE is configured to monitor all candidate PSFCH occasions that are after a first time gap after the SCI transmission by the second UE and before a second time gap prior to the at least one conflicting resource.

19. The method of claim 15, wherein the second UE stops monitoring PSFCH occasions responsive to detecting the PSFCH data from the first UE.

20. The method of claim 15, wherein a number of candidate PSFCH occasions is one of 1, 2, 3, or 4.

21. The method of claim 15, wherein a first candidate PSFCH occasion is on a first slot which is at least a predetermined number of slots after the SCI transmission of the second UE, and wherein a second candidate PSFCH occasion is on a second slot which is at least the predetermined number of slots after the SCI transmission of the second UE.

22. The method of claim 15, wherein the PSFCH occasion is selected as a last available candidate slot in a resource pool prior to a predetermined time gap prior to a slot of the at least one resource associated with conflict information of the second UE.

23. The method of claim 15, wherein multiple PSFCH occasions are counted starting from the last available slot in a resource pool that includes PSFCH resources.

24. The method of claim 15, wherein a last candidate PSFCH occasion is on a last slot which is at least a predetermined number of slots before a slot of the resource associated with conflict information of the second UE, and wherein a second last candidate PSFCH occasion is on a second last slot which is at least the predetermined number of slots before a slot of the resource associated with the conflict information.

25. The method of claim 15, wherein multiple PSFCH occasions are counted starting from a first available slot in a resource pool that includes PSFCH resources and that satisfies a predetermined time gap from the SCI transmission of the second UE.

26. The method of claim 15, wherein multiple PSFCH occasions are counted starting from the last available slot in a resource pool before a slot of the resource associated with conflict information of the second UE and that includes PSFCH resources backward to previous candidate PSFCH resources.

27. A method comprising: identifying one or more candidate physical sidelink feedback channel (PSFCH) occasions for specifying inter-UE coordination (IUC) information for resource allocation for unlicensed sidelink (SL-U) communication for a first UE, the IUC information specifying at least one conflicting resource from sidelink control information (SCI) transmission by a second UE; and receiving, at a first user equipment (UE) from a second UE, PSFCH data on a PSFCH occasion of the identified one or more candidate PSFCH occasions, the PSFCH data specifying the at least one conflicting resource.

28. The method of claim 27, wherein the first UE attempts to receive the PSFCH data on a set of first available candidate slots indexed in ascending order in time that include PSFCH resources and that are at least a given number of slots after a last slot of a PSSCH reception that provides the SCI format until the first UE detects a PSFCH with conflict information.

29. The method of claim 28, wherein the first UE attempts to receive the PSFCH data when the slot is at least a given time before the PSFCH with conflict information.

30. The method of claim 27, wherein the first UE attempts to receive the PSFCH data on a set of latest available candidate slots indexed in ascending order in time that include PSFCH resources and that are at least a given number of slots before a slot including a PSFCH with conflict information until the first UE detects the PSFCH with conflict information.

31. The method of claim 30, wherein the first UE attempts to receive the PSFCH with conflict information when the PSFCH resource is in a slot that is at least a given number of slots after a slot of a PSCCH transmission that provides the SCI.

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