Channel access techniques for frame-based equipment in sidelink communications using shared spectrum

Abstract

Methods, systems, and devices are described for wireless communication in which a device is operable in a frame-based equipment (FBE) mode for sidelink communication. One or more fixed frame period (FFP) configurations may be used by different sidelink devices, and a first device (e.g., a first user equipment (UE)) may send an indication of the FFP configuration for sidelink communications to one or more other devices. The FFP configuration may include an idle cycle configuration coordinated across a plurality of devices for initiating a channel access procedure. Alternatively, different sidelink devices may have different FFP configurations, and a joint mode may be provided for performing the channel access procedure at each of the sidelink devices.

Description

Technical Field

[0001] The following relates to channel access techniques for frame-based equipment in wireless communications, including sidelink communications using a shared spectrum. Background Art

[0002] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcast, and the like. These systems may be able to support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth generation (4G) systems (such as long term evolution (LTE) systems, advanced LTE (LTE-A) systems, or LTE-A Pro systems) and fifth generation (5G) systems (which may be referred to as new radio (NR) systems). These systems may employ techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include one or more base stations, each of which supports wireless communications for communication devices, which may be referred to as user equipment (UE).

[0003] Some wireless communication systems may support sidelink communications between UEs in a shared radio frequency spectrum. The shared radio frequency spectrum may be unlicensed, licensed to multiple operators, or spectrum licensed to a single operator with opportunistic access by other devices (e.g., licensed radio frequency spectrum, unlicensed radio frequency spectrum, or a combination of licensed and unlicensed radio frequency spectrum). Improved techniques for facilitating sidelink communications in a shared radio frequency spectrum may be desirable. Summary of the invention

[0004] The described technology relates to improved methods, systems, devices and apparatuses for supporting channel access techniques for frame-based equipment (FBE) in sidelink communications using shared spectrum. For example, the described technology provides that a first user equipment (UE) may be configured with timing of a frame structure for sidelink communications via a shared channel. The timing of the frame structure may correspond to a fixed frame period (FFP), and the first UE may initiate sidelink communications at the boundary of the FFP. The first UE may also support a technology for collision avoidance such as by sending an indication of an FFP configuration for sidelink communications between at least the first UE and the second UE operating in FBE mode to at least a second UE. The FFP configuration may include an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure. The first UE may monitor a sidelink channel during a first idle period of the idle period configuration based on the FFP configuration, and send communications based on the channel access procedure indicating that the sidelink channel is available for sidelink communications. In some cases, the first UE and the second UE may be in the same first UE group, and the FFP configuration is used at each UE in the first UE group. Alternatively, the first UE and the second UE may have different FFP configurations, and a joint mode may be provided for performing the channel access procedure at each of the first UE and the second UE.

[0005] A method for wireless communication at a first user equipment (UE) is described. The method may include: sending an indication of a fixed frame period configuration for sidelink communication between at least the first UE and the second UE operating in a frame-based equipment mode to at least a second UE, the fixed frame period configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure; monitoring a sidelink channel during a first idle period according to the channel access procedure, the first idle period being identified based on the idle period configuration of the fixed frame period configuration; and sending sidelink communication to at least the second UE based on the channel access procedure indicating that the sidelink channel is available for sidelink communication.

[0006] An apparatus for wireless communication at a first UE is described. The apparatus may include a processor, a memory coupled to the processor, and instructions stored in the memory. The instructions may be executed by the processor to cause the apparatus to: send an indication of a fixed frame period configuration for sidelink communication between at least the first UE and the second UE operating in a frame-based equipment mode to at least a second UE, the fixed frame period configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure; monitor a sidelink channel during a first idle period according to the channel access procedure, the first idle period being identified based on the idle period configuration of the fixed frame period configuration; and send sidelink communication to at least the second UE based on the channel access procedure indicating that the sidelink channel is available for sidelink communication.

[0007] Another apparatus for wireless communication at a first UE is described. The apparatus may include: means for sending an indication of a fixed frame period configuration for sidelink communication between at least the first UE and the second UE operating in a frame-based equipment mode to at least a second UE, the fixed frame period configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure; means for monitoring a sidelink channel during a first idle period according to the channel access procedure, the first idle period being identified based on the idle period configuration of the fixed frame period configuration; and means for sending sidelink communication to at least the second UE based on the channel access procedure indicating that the sidelink channel is available for sidelink communication.

[0008] A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions that can be executed by a processor to perform the following operations: sending an indication of a fixed frame period configuration for sidelink communication between at least the first UE and the second UE operating in a frame-based equipment mode to at least a second UE, the fixed frame period configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure; monitoring a sidelink channel during a first idle period according to the channel access procedure, the first idle period being identified based on the idle period configuration of the fixed frame period configuration; and sending sidelink communication to at least the second UE based on the channel access procedure indicating that the sidelink channel is available for sidelink communication.

[0009] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the first UE and the second UE may be in a first UE group, and the same fixed frame period configuration is used at each UE in the first UE group. Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may include operations, features, components, or instructions for performing the following actions: receiving side link configuration information indicating a zone identifier for side link communication, wherein the first UE group each has the same zone identifier.

[0010] Some examples of the methods, apparatuses, and non-transitory computer-readable media described herein may include operations, features, components, or instructions for performing the following actions: receiving sidelink configuration information indicating a central node associated with the first UE group, and the first UE group includes UEs whose proximity to the central node is less than a threshold. In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the central node is selected at a network entity or at one or more UEs in the first UE group.

[0011] In some examples of the methods, devices, and non-transitory computer-readable media described herein, the monitoring of the side link channel may include operations, features, components, or instructions for performing the following actions: determining to contend for channel access during the first idle period based on a conflict avoidance procedure, wherein the conflict avoidance procedure is based on a random starting point for channel contention, a priority rule for channel contention, a reservation indication provided from the second UE, or any combination thereof; and monitoring the side link channel during the first idle period based on the conflict avoidance procedure. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the conflict avoidance procedure provides for mapping higher priority traffic to be sent in the side link communication to an earlier start time for initiating the channel access procedure. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the conflict avoidance procedure prioritizes channel contention for UEs based on one or more of the following: the amount of traffic to be sent in the side link communication, the priority of the traffic to be sent, a random selection based on the identity of the UE, a priority indication provided from a central node of a UE group including the first UE and the second UE, or any combination thereof. Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for performing the following actions: receiving a fixed frame period reservation indication from the second UE during a second idle period; and suppressing initiation of the channel access procedure during the second idle period based on the fixed frame period reservation indication.

[0012] In some examples of the methods, devices, and non-transitory computer-readable media described herein, the second UE may have a different fixed frame period configuration from the first UE, and a joint mode may be provided for performing the channel access procedure at each of the first UE and the second UE. In some examples of the methods, devices, and non-transitory computer-readable media described herein, both the first UE and the second UE may have the same zone identifier for sidelink communication, and each UE having the same zone identifier follows an idle period associated with the fixed frame period configuration of each UE having the same zone identifier. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the joint mode provides that each UE having a first zone identifier for sidelink communication and sharing a first fixed frame period configuration follows an idle period associated with the first fixed frame period configuration, and the joint mode provides that the first UE blanks transmission during the monitoring period of other UEs to which the first UE sends sidelink communications. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the joint mode further provides that each UE having the first zone identifier blanks transmission during the monitoring period of other UEs having the first zone identifier and a different fixed frame period configuration.

[0013] Some examples of the methods, devices, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for performing the following actions: receiving an indication of the fixed frame period configuration for at least the second UE via sidelink control information. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the sidelink control information indicates one or more of the periodicity of the fixed frame period, the offset associated with the fixed frame period, the duration of the available channel occupancy time shared during the fixed frame period, or any combination thereof. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the sidelink control information of the indication of the fixed frame configuration is provided as part of an initial connection that initializes the sidelink communication between the first UE and at least the second UE. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the sidelink control information is provided to a set of multiple UEs each having a first zone identifier for sidelink communication in an anchor UE groupcast transmission, or the sidelink control information is provided separately from each UE in the set of multiple UEs each having the first zone identifier.

[0014] Some examples of the methods, devices, and non-transitory computer-readable media described herein may include operations, features, components, or instructions for performing the following actions: sending a blanking request to at least the second UE before monitoring the side link channel, the blanking request indicating a request for the second UE to suppress transmission during a listen-before-talk (LBT) duration associated with the channel access procedure. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the blanking request may be provided in a side link control information transmission from the first UE. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the blanking request may be a single blanking request for a single fixed frame period or a semi-static blanking request applied to two or more fixed frame periods. In some examples of the methods, devices, and non-transitory computer-readable media described herein, the blanking request further indicates a priority associated with a service to be sent from the first UE, and wherein the priority is used at least at the second UE to determine whether to blank the transmission during the LBT duration. In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first UE provides an indication of whether the sidelink communication includes one or more symbols that have been blanked based on a received blanking request from a different UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 An example of a wireless communication system supporting a channel access technique for frame-based equipment (FBE) in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is illustrated.

[0016] Figure 2 An example of a wireless communication system supporting a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is illustrated.

[0017] Figure 3 Examples of different FBE configurations for channel access techniques supporting FBE in sidelink communications using shared spectrum in accordance with one or more aspects of the present disclosure are illustrated.

[0018] Figure 4 Examples of idle periods for different FBE configurations supporting a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure are illustrated.

[0019] Figure 5 Examples of idle periods for different FBE configurations supporting a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure are illustrated.

[0020] Figure 6 and Figure 7A block diagram of a device supporting a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is shown.

[0021] Figure 8 A block diagram of a communication manager supporting a channel access technique for FBE in sidelink communications using a shared spectrum is shown in accordance with one or more aspects of the present disclosure.

[0022] Fig. 9 A diagram of a system including devices supporting a channel access technique for FBE in sidelink communications using a shared spectrum is shown in accordance with one or more aspects of the present disclosure.

[0023] Fig.10 and Fig.11 A flow chart illustrating a method of supporting a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0024] Some wireless communication systems may support sidelink communications, in which a user equipment (UE) may communicate directly with one or more other UEs in a shared spectrum (e.g., a shared radio frequency spectrum). In such systems, UEs communicating on the sidelink may support a load-based equipment (LBE) mode or a frame-based equipment (FBE) mode. In the LBE mode, the UE may contend for access to a shared channel at any time to send sidelink data on the shared channel. In the FBE mode, the UE may contend for access to a shared channel at a fixed time to send sidelink data on the shared channel. For example, in the FBE mode, the UE may be configured with a fixed frame period (FFP), and the UE may contend for access to the shared channel at the boundary of the FFP to send sidelink data in the FFP. However, in some cases, the technique for configuring the timing of the frame structure for sidelink communication on the shared channel may be undefined. In addition, in the FBE system, the technique for contending for access to the shared channel at the boundary of the FFP at the UE may be flawed.

[0025] As described herein, a wireless communication system may support efficient techniques for facilitating sidelink communications in a shared spectrum (e.g., in an FBE system). A first UE may be configured with timing of a frame structure for sidelink communications via a shared channel. The timing of the frame structure may correspond to an FFP, and the first UE may initiate sidelink communications at the boundary of the FFP. In some cases, a conflict avoidance procedure may be provided, in which the first UE may send an indication of an FFP configuration for sidelink communications to at least a second UE. The FFP configuration may include an idle period configuration coordinated across at least a first UE and a second UE for initiating a channel access procedure. The first UE may monitor a sidelink channel during a first idle period of the idle period configuration based on the FFP configuration, and transmit communications based on the channel access procedure indicating that the sidelink channel can be used for sidelink communications. In some cases, the first UE and the second UE may be in the same first UE group, and the FFP configuration may be used at each UE in the first UE group. Alternatively, the first UE and the second UE may have different FFP configurations, and a joint mode may be provided for performing the channel access procedure at each of the first UE and the second UE.

[0026] In some cases, UE groups may be defined based on the same zone ID as part of the sidelink configuration, and all UEs with the same zone ID may have the same FFP. In other cases, UE groups may be defined based on proximity to a central node that may be identified by a network node (e.g., a network entity such as a base station) or selected by the UE. Within each UE group with the same FFP, a conflict avoidance technique for contending for channel access to initiate FFP may be used (e.g., a rule-based determination of which UE will initiate FFP, a selection based on a UE identifier, or an identified central node may initiate FFP).

[0027] In some cases, different UEs may have different FFPs, and a joint mode for channel access idle periods may be implemented by blanking UE transmissions during idle periods of contention procedures of other UEs, thereby avoiding conflicts between one or more UE transmissions and another UE channel access procedure. Multiple options for determining which UEs have shared idle periods may be available. For example, a first option is for all UEs with the same zone ID not to transmit during the idle periods of any other UEs with the same zone ID. A second option is that the UE will not transmit during the idle period in which the UEs share the FFP, and will blank transmission during the LBT time (e.g., less than 16 μs) for the UEs with the same zone ID or the UEs to which the UE transmits. A third option is that the UE will not transmit during the idle period in which the UEs share the FFP, and will blank transmission during the LBT time (e.g., less than 16 μs) for the UEs to which the UE transmits (e.g., unless the UE transmits to it, it will not blank for other UEs with the same zone ID).

[0028] In some cases, the UE may exchange information indicating the FFP in sidelink control information (SCI) sent via physical sidelink control channel (PSSCH) communication (e.g., SCI-2 in the PSSCH during initial connection configuration). Additionally or alternatively, the indication of the FFP may be indicated by an anchor UE multicast transmission. In addition, in the case where the UEs have different FFPs, the lack of UE transmission may result in inefficiency due to insufficient resource utilization. In such cases, the UE may send an indication of a blanking request, such as a 1-bit indication in the SCI indicating the presence / absence of a blanking request, or a 2-bit indication in which an additional bit indicates a single blanking request or a semi-persistent blanking request. In addition, the priority of the service to be sent may be indicated (e.g., by using more than three bits in the SCI), which may allow other UEs to ignore the blanking request in the presence of higher priority services.

[0029] Aspects of the present disclosure are first described in the context of a wireless communication system. Aspects of the present disclosure are further illustrated and described by and with reference to FFP configurations, apparatus diagrams, system diagrams, and flow charts related to channel access techniques for FBE in sidelink communications using shared spectrum.

[0030] Figure 1An example of a wireless communication system 100 that supports a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is illustrated. The wireless communication system 100 may include one or more network entities 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an Advanced LTE (LTE-A) network, an LTE-A Pro network, a New Radio (NR) network, or a network operating according to other systems and radio technologies, including future systems and radio technologies not explicitly mentioned herein.

[0031] The network entities 105 may be dispersed throughout a geographic area to form the wireless communication system 100, and may include devices in different forms or with different capabilities. In various examples, the network entities 105 may be referred to as network elements, mobility elements, radio access network (RAN) nodes, or network equipment, among other nomenclature. In some examples, the network entities 105 and the UE 115 may communicate wirelessly via one or more communication links 125 (e.g., radio frequency (RF) access links). For example, the network entity 105 may support a coverage area 110 (e.g., a geographic coverage area) within which the UE 115 and the network entity 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area within which the network entity 105 and the UE 115 may support signal communications according to one or more radio access technologies (RATs).

[0032] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary or mobile, or stationary and mobile at different times. The UEs 115 may be devices in different forms or with different capabilities. Figure 1 Some example UEs 115 are illustrated in FIG. 1 . The UEs 115 described herein may be capable of supporting communications with various types of devices, such as Figure 1 Other UEs 115 or network entities 105 are shown.

[0033] As described herein, a node of the wireless communication system 100 (which may be referred to as a network node or a wireless node) may be a network entity 105 (e.g., any network entity described herein), a UE 115 (e.g., any UE described herein), a network controller, an apparatus, a device, a computing system, one or more components, or another suitable processing entity configured to perform any of the techniques described herein. For example, the node may be a UE 115. As another example, the node may be a network entity 105. As another example, a first node may be configured to communicate with a second node or a third node. In one aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a UE 115. In another aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a network entity 105. In other aspects of this example, the first node, the second node, and the third node may be different relative to these examples. Similarly, references to UE 115, network entity 105, apparatus, device, computing system, etc. may include disclosure of UE 115, network entity 105, apparatus, device, computing system, etc. as nodes. For example, a disclosure that UE 115 is configured to receive information from network entity 105 also discloses that the first node is configured to receive information from a second node.

[0034] In some examples, the network entities 105 may communicate with the core network 130, or communicate with each other, or both. For example, the network entities 105 may communicate with the core network 130 via one or more backhaul communication links 120 (e.g., according to S1, N2, N3, or other interface protocols). In some examples, the network entities 105 may communicate with each other through the backhaul communication link 120 (e.g., according to X2, Xn, or other interface protocols) directly (e.g., directly between each network entity 105) or indirectly (e.g., via the core network 130). In some examples, the network entities 105 may communicate with each other via the midhaul communication link 162 (e.g., according to the midhaul interface protocol) or the fronthaul communication link 168 (e.g., according to the fronthaul interface protocol) or any combination thereof. The backhaul communication link 120, the midhaul communication link 162, or the fronthaul communication link 168 may be or include one or more wired links (e.g., electrical links, optical fiber links), one or more wireless links (e.g., radio links, wireless optical links), and other examples or various combinations thereof. UE 115 may communicate with core network 130 via communication link 155 .

[0035] One or more of the network entities 105 described herein may include or may be referred to as a base station 140 (e.g., a transceiver base station, a radio base station, an NR base station, an access point, a radio transceiver, a Node B, an evolved Node B (eNB), a next generation Node B, or a Gigabit Node B (any of which may be referred to as a gNB), a 5G NB, a next generation eNB (ng-eNB), a home Node B, a home evolved Node B, or other suitable terms). In some examples, the network entity 105 (e.g., a base station 140) may be implemented in an aggregated (e.g., monolithic, stand-alone) base station architecture, which may be configured to utilize a protocol stack physically or logically integrated within a single network entity 105 (e.g., a single RAN node, such as a base station 140).

[0036] In some examples, the network entity 105 may be implemented in a disaggregated architecture (e.g., a disaggregated base station architecture, a disaggregated RAN architecture) that may be configured to utilize a protocol stack that is physically or logically distributed between two or more network entities 105, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance), or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN)). For example, the network entity 105 may include one or more of the following: a central unit (CU) 160, a distributed unit (DU) 165, a radio unit (RU) 170, a RAN intelligent controller (RIC) 175 (e.g., a near real-time RIC (near RT RIC), a non-real-time RIC (non-RT RIC)), a service management and orchestration (SMO) 180 system, or any combination thereof. The RU 170 may also be referred to as a radio head, a smart radio head, a remote radio head (RRH), a remote radio unit (RRU), or a transmit receive point (TRP). One or more components of the network entity 105 in the decomposed RAN architecture may be co-located, or one or more components of the network entity 105 may be located in distributed locations (e.g., separate physical locations). In some examples, one or more network entities 105 of the decomposed RAN architecture may be implemented as virtual units (e.g., virtual CU (VCU), virtual DU (VDU), virtual RU (VRU)).

[0037] The functional split between CU 160, DU 165, and RU 170 is flexible and may support different functionalities, depending on which functions (e.g., network layer functions, protocol layer functions, baseband functions, RF functions, and any combination thereof) are performed at CU 160, DU 165, or RU 170. For example, a functional split of a protocol stack may be employed between CU 160 and DU 165 such that CU 160 may support one or more layers of a protocol stack and DU 165 may support one or more different layers of a protocol stack. In some examples, CU 160 may host higher protocol layer (e.g., layer 3 (L3), layer 2 (L2)) functionality and signaling (e.g., radio resource control (RRC), service data adaptation protocol (SDAP), packet data convergence protocol (PDCP)). The CU 160 may be connected to one or more DUs 165 or RUs 170, and the one or more DUs 165 or RUs 170 may host lower protocol layers, such as layer 1 (L1) (e.g., physical (PHY) layer) or L2 (e.g., radio link control (RLC) layer, medium access control (MAC) layer) functionality and signaling, and may each be at least partially controlled by the CU 160. Additionally or alternatively, a functional split of the protocol stack may be employed between the DU 165 and the RU 170, such that the DU 165 may support one or more layers of the protocol stack, and the RU 170 may support one or more different layers of the protocol stack. The DU 165 may support one or more different cells (e.g., via one or more RUs 170). In some cases, the functional split between CU 160 and DU 165 or between DU 165 and RU 170 can be within the protocol layer (e.g., some functions of the protocol layer can be performed by one of CU 160, DU 165, or RU 170, while other functions of the protocol layer are performed by different ones of CU 160, DU 165, or RU 170). CU 160 can be further functionally split into CU control plane (CU-CP) and CU user plane (CU-UP) functions. CU 160 can be connected to one or more DUs 165 via midhaul communication links 162 (e.g., F1, F1-c, F1-u), and DU 165 can be connected to one or more RUs 170 via fronthaul communication links 168 (e.g., open fronthaul (FH) interface). In some examples, midhaul communication link 162 or fronthaul communication link 168 may be implemented based on interfaces (eg, channels) between layers of a protocol stack supported by respective network entities 105 that communicate via those communication links.

[0038] In some wireless communication systems (e.g., wireless communication system 100), infrastructure and spectrum resources for radio access may support wireless backhaul link capabilities to supplement wired backhaul connections, thereby providing an IAB network architecture (e.g., to core network 130). In some cases, in an IAB network, one or more network entities 105 (e.g., IAB nodes 104) may be partially controlled by each other. One or more IAB nodes 104 may be referred to as donor entities or IAB donors. One or more DUs 165 or one or more RUs 170 may be controlled in part by one or more CUs 160 associated with a donor network entity 105 (e.g., donor base station 140). One or more donor network entities 105 (e.g., IAB donors) may communicate with one or more additional network entities 105 (e.g., IAB nodes 104) via supported access and backhaul links (e.g., backhaul communication links 120). The IAB node 104 may include an IAB mobile terminal (IAB-MT) controlled (e.g., scheduled) by a coupled IAB donor's DU 165. The IAB-MT may include an independent set of antennas for relaying communications with the UE 115, or may share the same antennas of the IAB node 104 (e.g., of the RU 170) for access via the DU 165 of the IAB node 104 (e.g., referred to as a virtual IAB-MT (vIAB-MT)). In some examples, the IAB node 104 may include a DU 165 that supports communication links with additional entities (e.g., IAB node 104, UE 115) within a relay chain or configuration (e.g., downstream) of the access network. In such cases, one or more components of the decomposed RAN architecture (e.g., one or more IAB nodes 104 or components of the IAB node 104) may be configured to operate according to the techniques described herein.

[0039] In the case where the techniques described herein are applied to the context of a decomposed RAN architecture, one or more components of the decomposed RAN architecture may be configured to support sidelink communications using a fixed frame period as described herein. For example, some operations described as being performed by a UE 115 or a network entity 105 (e.g., a base station 140) may additionally or alternatively be performed by one or more components of the decomposed RAN architecture (e.g., an IAB node 104, a DU 165, a CU 160, a RU 170, a RIC 175, a SMO 180).

[0040] UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where a "device" may also be referred to as a unit, a station, a terminal, or a client, etc. UE 115 may also include or may be referred to as a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, UE 115 may include or may be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communication (MTC) device, etc., which may be implemented in various objects such as appliances or vehicles, meters, etc.

[0041] The UE 115 described herein may be capable of communicating with various types of devices such as other UEs 115 which may sometimes act as relays, as well as network entities 105 and network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, etc. Figure 1 shown.

[0042] The UE 115 and the network entity 105 may wirelessly communicate with each other via one or more communication links 125 (e.g., access links) using resources associated with one or more carriers. The term "carrier" may refer to a collection of RF spectrum resources having a physical layer structure defined for supporting the communication link 125. For example, a carrier for the communication link 125 may include a portion of an RF spectrum band (e.g., a bandwidth portion (BWP)) that operates according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling for coordinating carrier operations, user data, or other signaling. The wireless communication system 100 may support communications with the UE 115 using carrier aggregation or multi-carrier operation. Depending on the carrier aggregation configuration, the UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation may be used for both frequency division duplex (FDD) and time division duplex (TDD) component carriers. Communication between the network entity 105 and other devices may refer to communication between these devices and any part (e.g., entity, sub-entity) of the network entity 105. For example, the terms "send", "receive", or "communicate" when referring to the network entity 105 may refer to any part of the network entity 105 (e.g., base station 140, CU 160, DU 165, RU 170) of the RAN communicating with another device (e.g., directly or via one or more other network entities 105).

[0043] In some examples, such as in a carrier aggregation configuration, a carrier may also have acquisition signaling or control signaling that coordinates the operation of other carriers. A carrier may be associated with a frequency channel (e.g., an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute RF Channel Number (EARFCN)) and may be identified based on a channel raster for discovery by UE 115. A carrier may operate in a standalone mode, in which case initial acquisition and connection may be performed by UE 115 via the carrier, or a carrier may operate in a non-standalone mode, in which case the connection is anchored using a different carrier (e.g., a different carrier of the same or different radio access technology).

[0044] The communication link 125 shown in the wireless communication system 100 may include downlink transmissions (e.g., forward link transmissions) from the network entity 105 to the UE 115, uplink transmissions (e.g., return link transmissions) from the UE 115 to the network entity 105, or both, as well as other transmission configurations. A carrier may carry either downlink communications or uplink communications (e.g., in an FDD mode), or may be configured to carry both downlink communications and uplink communications (e.g., in a TDD mode).

[0045] A carrier may be associated with a particular bandwidth of the RF spectrum, and in some examples, the carrier bandwidth may be referred to as a "system bandwidth" of the carrier or wireless communication system 100. For example, the carrier bandwidth may be one of a set of bandwidths of carriers of a particular radio access technology (e.g., 1.4 megahertz (MHz), 3 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz, 40 MHz, or 80 MHz). A device of the wireless communication system 100 (e.g., a network entity 105, a UE 115, or both) may have a hardware configuration that supports communications using a particular carrier bandwidth, or may be capable of being configured to support communications using one of the carrier bandwidths in the set of carrier bandwidths. In some examples, the wireless communication system 100 may include a network entity 105 or a UE 115 that supports concurrent communications using carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured to operate using a portion (e.g., a subband, a BWP) or all of the carrier bandwidth.

[0046] The signal waveform transmitted via the carrier may include multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques, such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system using MCM technology, a resource element may refer to a resource of one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, in which case the symbol period and the subcarrier spacing may be inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both), so that a relatively high number of resource elements (e.g., in the transmission duration) and a relatively high order modulation scheme may correspond to a relatively high communication rate. Wireless communication resources may refer to a combination of RF spectrum resources, time resources, and spatial resources (e.g., spatial layers or beams), and the use of multiple spatial resources may increase the data rate or data integrity used for communication with UE 115.

[0047] One or more numerologies for a carrier may be supported, and the numerologies may include subcarrier spacing (Δf) and cyclic prefixes. A carrier may be divided into one or more BWPs with the same or different numerologies. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time, and communications of a UE 115 may be constrained to one or more active BWPs.

[0048] The time interval for the network entity 105 or the UE 115 may be expressed as a multiple of a basic time unit, which may be, for example, T s =1 / (Δf max ·N f ) seconds sampling period, where the sampling period, Δf max It can represent the supported subcarrier spacing, and N f The supported discrete Fourier transform (DFT) size may be indicated. The time intervals of the communication resources may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023).

[0049] Each frame may include multiple consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, the frame may be divided into subframes (e.g., in the time domain), and each subframe may be further divided into a certain number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include a certain number of symbol periods (e.g., depending on the length of the cyclic prefix appended in front of each symbol period). In some wireless communication systems 100, the time slot may be further divided into a plurality of micro time slots associated with one or more symbols. Excluding the cyclic prefix, each symbol period may be associated with one or more (e.g., N f The duration of a symbol period may depend on the subcarrier spacing or the operating frequency band.

[0050] A subframe, slot, mini-slot, or symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communication system 100 and may be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in a burst of a shortened TTI (sTTI)).

[0051] Carrier multiplexing physical channels may be used for communication according to various techniques. Physical control channels and physical data channels may be multiplexed via downlink carriers for signaling using, for example, one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. A control region (e.g., a control resource set (CORESET)) of a physical control channel may be defined by a set of symbol periods and may extend across a system bandwidth or a subset of a system bandwidth of a carrier. One or more control regions (e.g., CORESETs) may be configured for a set of UEs 115. For example, one or more UEs in UE115 may monitor or search a control region for control information according to one or more search space sets, and each search space set may include one or more control channel candidates in one or more aggregation levels arranged in a cascaded manner. The aggregation level of a control channel candidate may refer to the amount of control channel resources (e.g., control channel elements (CCEs)) associated with coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for transmitting control information to a plurality of UEs 115 , and a UE-specific search space set for transmitting control information to a specific UE 115 .

[0052] In some examples, the network entities 105 (e.g., base stations 140, RUs 170) may be mobile and thus provide communication coverage for mobile coverage areas 110. In some examples, different coverage areas 110 associated with different technologies may overlap, but the different coverage areas 110 may be supported by the same network entity 105. In some other examples, overlapping coverage areas 110 associated with different technologies may be supported by different network entities 105. The wireless communication system 100 may include, for example, a heterogeneous network in which different types of network entities 105 provide coverage for various coverage areas 110 using the same or different radio access technologies.

[0053] Some UEs 115 may be configured to employ a reduced power consumption mode of operation, such as half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception but does not transmit and receive concurrently). In some examples, half-duplex communication may be performed at a reduced peak rate. Other power saving techniques for UEs 115 include entering a power saving deep sleep mode when not engaged in active communications, operating using limited bandwidth (e.g., according to narrowband communications), or a combination of these techniques. For example, some UEs 115 may be configured to operate using a narrowband protocol type that is associated with a defined portion or range (e.g., a subcarrier or resource block (RB) set) within a carrier, within a guard band of a carrier, or outside a carrier.

[0054] The wireless communication system 100 may be configured to support ultra-reliable communication or low-latency communication or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low-latency communication (URLLC). UE 115 may be designed to support ultra-reliable or low-latency or critical functions. Ultra-reliable communication may include private communication or group communication, and may be supported by one or more services (such as push-to-talk, video, or data). Support for ultra-reliable, low-latency functions may include prioritization of services, and such services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, and ultra-reliable low-latency may be used interchangeably herein.

[0055] In some examples, a UE 115 may be configured to support communication directly with other UEs 115 via a device-to-device (D2D) communication link 135 (e.g., according to a peer-to-peer (P2P), D2D, or sidelink protocol). In some examples, one or more UEs 115 in a group that are performing D2D communication may be within a coverage area 110 of a network entity 105 (e.g., a base station 140, a RU 170), which may support aspects of such D2D communication configured or (e.g., scheduled) by the network entity 105. In some examples, one or more UEs 115 of such a group may be outside of the coverage area 110 of the network entity 105, or may otherwise be unable or not configured to receive transmissions from the network entity 105. In some examples, a group of UEs 115 communicating via D2D communication may support a one-to-many (1:M) system, in which each UE 115 transmits to each of the other UEs 115 in the group. In some examples, network entity 105 may facilitate scheduling of resources for D2D communications. In some other examples, D2D communications may be performed between UEs 115 without involving network entity 105.

[0056] In some systems, the D2D communication link 135 can be an example of a communication channel (such as a sidelink communication channel) between vehicles (e.g., UE 115). In some examples, the vehicles can communicate using vehicle-to-everything (V2X) communication, vehicle-to-vehicle (V2V) communication, or some combination of these items. The vehicles can signal information related to traffic conditions, signal scheduling, weather, safety, emergency situations, or any other information related to the V2X system. In some examples, vehicles in the V2X system can communicate with roadside infrastructure (such as roadside units), or communicate with the network via one or more network nodes (e.g., network entity 105, base station 140, RU 170) using vehicle-to-network (V2N) communication, or both.

[0057] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) for managing access and mobility and at least one user plane entity (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)) for routing packets or interconnecting to an external network. The control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management of UE 115 served by a network entity 105 (e.g., a base station 140) associated with the core network 130. User IP packets may be delivered through the user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to the IP service 150 of one or more network operators. IP services 150 may include access to the Internet, an intranet, an IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0058] The wireless communication system 100 may operate using one or more frequency bands that may be in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally speaking, the region from 300 MHz to 3 GHz is referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelength ranges from about one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features (which may be referred to as clusters), but these waves may be sufficient to penetrate structures so that macro cells provide services to UEs 115 located indoors. Communications using UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) than communications using lower frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0059] The wireless communication system 100 may utilize licensed and unlicensed RF spectrum bands. For example, the wireless communication system 100 may employ license assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology using unlicensed bands (such as the 5 GHz Industrial, Scientific, and Medical (ISM) band). When operating using unlicensed RF spectrum bands, devices such as network entity 105 and UE 115 may employ carrier sensing for conflict detection and avoidance. In some examples, operations using unlicensed bands may be based on carrier aggregation configuration (e.g., LAA) in conjunction with component carriers operating using licensed bands. Operations using unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, and the like.

[0060] The network entity 105 (e.g., base station 140, RU 170) or UE 115 may be equipped with multiple antennas that can be used to employ technologies such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of the network entity 105 or UE 115 may be located in one or more antenna arrays or antenna panels, which may support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, antennas or antenna arrays associated with the network entity 105 may be located at different geographical locations. The network entity 105 may include an antenna array having a collection of multiple rows and columns of antenna ports that the network entity 105 can use to support beamforming for communications with the UE 115. Similarly, the UE 115 may include one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support RF beamforming for signals sent via the antenna ports.

[0061] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a network entity 105, a UE 115) to shape or direct an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining signals conveyed via antenna elements of an antenna array so that some signals propagating along a particular direction relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals conveyed via antenna elements may include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to signals carried via antenna elements associated with the device. Adjustments associated with each of these antenna elements may be defined by a set of beamforming weights associated with a particular direction (e.g., relative to the antenna array of the transmitting device or the receiving device or relative to some other direction).

[0062] The wireless communication system 100 may be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or PDCP layer may be IP-based. The RLC layer may perform packet segmentation and reassembly to communicate via logical channels. The MAC layer may perform priority processing and multiplexing of logical channels into transport channels. The MAC layer may also implement error detection techniques, error correction techniques, or both to support retransmission to improve link efficiency. In the control plane, the RRC layer may provide the establishment, configuration, and maintenance of an RRC connection that supports a radio bearer for user plane data between the UE 115 and the network entity 105 or the core network 130. The PHY layer may map a transport channel to a physical channel.

[0063] The wireless communication system 100 may utilize unshared (e.g., licensed) and shared (e.g., unlicensed, licensed to more than one operator, licensed to one or more operators in the case of opportunistic use) radio frequency spectrum bands. For example, the wireless communication system 100 may employ license assisted access (LAA), LTE-unlicensed (LTE-U) radio access technology, NR technology in unlicensed bands (NR-U, including sidelink U) such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in unlicensed radio frequency spectrum bands, devices such as network entities 105 and UEs 115 may employ carrier sensing for conflict detection and avoidance. For example, the network entity 105 and the UE 115 may employ a listen-before-talk (LBT) procedure to ensure that a frequency channel (e.g., an LBT subchannel or a band that can be accessed via the LBT procedure) is idle before sending data. In some examples, operation in an unlicensed band may be based on a carrier aggregation configuration (e.g., LAA) in conjunction with component carriers operating in a licensed band. Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

[0064] The LBT procedure may be an example of a channel access procedure. The channel access procedure may include monitoring a channel, determining whether the channel is idle based on the monitoring, and transmitting on the channel when the channel is idle. The device may determine that the channel is idle (e.g., available for use) after monitoring the channel and failing to detect a transmission on the channel or failing to detect a transmission on the channel with a signal strength that satisfies a threshold. Alternatively, the device may determine that the channel is not idle (e.g., not available for use) after monitoring the channel and detecting one or more transmissions on the channel or detecting one or more transmissions on the channel with a signal strength that satisfies a threshold. The UE 115 may initiate a channel access procedure by monitoring the channel for transmissions from another device (e.g., another UE 115 or a network entity 105). In some cases, initiating a channel access procedure may refer to executing a channel access procedure.

[0065] In some implementations, there may be different categories of LBT procedures, including Category 1 LBT (e.g., no LBT), Category 2 LBT (e.g., LBT without a backoff period including one-time channel sensing for a fixed period), Category 3 LBT (e.g., LBT with a random (or other) backoff period and a fixed-size contention window), and Category 4 LBT (e.g., LBT with a random (or other) backoff period and a variable-size contention window). In some cases, a Category 2 LBT procedure may be referred to as a one-time or single-shot LBT procedure, in which the UE 115 may perform channel sensing for a defined duration (e.g., 25 μs). Additionally, a Category 4 LBT procedure may be referred to as a fairness-based LBT procedure for performing channel sensing with a backoff, in which the backoff may be used to prevent the UE 115 from accessing the channel immediately after detecting that the channel is idle.

[0066] The wireless communication system 100 may support sidelink communications between UEs 115 in a shared (e.g., unlicensed) spectrum. Sidelink communications may occur in a transmit or receive resource pool (e.g., a sidelink resource pool). The minimum resource allocation unit for sidelink communications may be a subchannel in the frequency domain, and the resource allocation for sidelink communications in the time domain may be a time slot. Some time slots may not be able to be used for the sidelink (e.g., a subset of all time slots of a carrier may be able to be used for the sidelink), and some time slots may contain feedback resources. In some aspects, the RRC configuration for sidelink communications may be preconfigured (e.g., preloaded on the UE 115) or signaled to the UE 115 (e.g., from the network entity 105). In some examples, the network entity 105 facilitates the scheduling of resources for sidelink communications (e.g., in resource allocation mode 1). In other cases, sidelink communications are performed between UEs 115 without the participation of the network entity 105 (e.g., in resource allocation mode 2).

[0067] In some aspects, a UE 115 communicating via a sidelink in a shared spectrum may support an LBE mode or an FBE mode. The UE 115 may receive system information (e.g., remaining minimum system information (RMSI)) from the network entity 105 indicating an FBE mode (e.g., a semi-static channel access mode) in which the UE 115 may operate. In the LBE mode, the UE 115 may contend for access to a shared channel at any time to send sidelink data on the shared channel. In the FBE mode, the UE 115 may contend for access to a shared channel at a fixed time to send sidelink data on the shared channel. For example, in the FBE mode, the UE may be configured with an FFP, and the UE may contend for access to a shared channel at a boundary of the FFP to send sidelink data in the FFP. In some cases, the UE 115 may receive an indication of the FFP configuration of the UE 115 (e.g., from the network entity 105 in a system information block 1 (SIB1)). The FFP configuration may indicate the FFP (eg, the periodicity of radio frames) in which the UE 115 may communicate. In some examples, the FFP configuration may be signaled to the UE 115 using UE-specific RRC signaling (eg, for a FBE secondary cell (SCell)).

[0068] The FFP may include idle periods and periods for sending data, and in some cases, the FFP may be limited to values ​​of 1 ms, 2 ms, 2.5 ms, 4 ms, 5 ms, and 10 ms (e.g., including the idle periods). The starting position of the FFP within every two radio frames may be from an even radio frame and may be given by i*P, where and P is a fixed frame period in ms. The idle period (e.g., in FFP) for a given subcarrier spacing (SCS) may be equal to Where the minimum idle period allowed is equal to max(5% of FFP, 100μs), Ts is the symbol duration of a given SCS, and when the FBE mode of operation is indicated, the physical random access channel (PRACH) resources are considered invalid if they overlap with the idle period of the FFP. Table 1 provides the minimum number of occupied symbols for idle mode in FFP of different SCSs.

[0069] Table 1: Minimum number of occupied symbols in idle periods in FFP of different SCS

[0070] SCS(kHz) Minimum number of occupied symbols for idle 15 2 30 3 60 6 120 12

[0071] Figure 2 An example of a wireless communication system 200 supporting a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is illustrated. The wireless communication system 200 includes a wireless device 205, which may be a reference Figure 1The wireless communication system 200 also includes UE 115-a (UE0), UE 115-b (UE1), and UE 115-c (UE2), which may be reference UEs 105 and 105. Figure 1 An example of a UE 115 is depicted. The wireless communication system 200 may implement aspects of the wireless communication system 100. For example, the wireless communication system 200 may support a channel access technique for FBE in sidelink communications using a shared spectrum (eg, in an FBE system).

[0072] According to various aspects, prior to communicating sidelink data 215 with UE 115-b in a shared channel (e.g., in a shared or unlicensed spectrum), UE 115-a may identify an FFP configuration for sidelink communications in the shared channel. The FFP configuration may refer to a configuration of the timing of a frame structure for sidelink communications in the shared channel, wherein the frame structure includes a plurality of frame periods (e.g., a plurality of FFPs) having a fixed frame duration. Figure 3 Examples of different FFP configurations are illustrated in . The FFP configuration may indicate the periodicity of the radio frames (e.g., the length of the FFP), and UE 115-a may contend for access to the shared channel at the boundaries of these FFPs. In one example, UE 115-a (UE0) and UE 115-b (UE1) may be configured to communicate during FFP 220, and UE 115-c (UE2) may be configured to communicate during FFP 225. The lengths of FFP 220 and FFP 225 (e.g., the periodicity of the radio frames configured for UE0, UE1, and UE2) may be the same or may be different.

[0073] In some aspects, the wireless device 205 may send an indication of an FFP configuration 210 for sidelink communication in a shared channel to the UE 115-a. For example, if the wireless device 205 is a network entity 105, the network entity 105 may send the FFP configuration 210 to the UE 115-a in an RRC configuration. For example, the network entity 105 may configure the FFP configuration 210 (e.g., for resource allocation mode 1 for sidelink communication) to the UE 115-a using RRC signaling. Because the network entity 105 may identify sidelink traffic at the UE 115-a (e.g., for transmission by the UE 115-a), and the network entity 105 may identify periodic traffic from the sidelink transmission of the UE 115-a, the network entity may be able to provide the UE 115-a with an appropriate FFP configuration 210. That is, the network entity may determine the FFP configuration 210 for the UE 115-a based on the sidelink traffic at the UE 115-a (e.g., to maximize throughput). In one example, the FFP configuration 210 may be based on the amount of sidelink traffic at the UE 115 - a , the average length of bursts of sidelink transmissions from the UE 115 - a , and the like.

[0074] In other examples, the wireless device 205 may be a UE 115, and the FFP configuration 210 may be sent to the UE 115-a in a PC-5 RRC configuration (e.g., using a connection to the UE 115-a via a PC-5 interface). In such cases, the UE 115 that provides the FFP configuration 210 to the UE 115-a may be referred to as an anchor UE 115 and may provide control information to multiple UEs 115 (e.g., out-of-coverage UEs). For example, the anchor UE 115 may provide the FFP configuration to multiple UEs 115 (e.g., including UE 115-a). In some examples, the anchor UE 115 of the multiple UEs 115 may be preconfigured (e.g., at a programmable logic controller (PLC)). In other examples, the anchor UE 115 of the multiple UEs 115 may be RRC configured. In yet other examples, the anchor UE 115 may be selected by multiple UEs 115 (e.g., multiple users may form a group and may select a central node as the anchor UE 115).

[0075] In some cases, the anchor UE 115 may support a channel access technique for FBE in a sidelink communication using a shared spectrum by providing an FFP configuration to the UE 115-a. For example, the anchor UE 115 may receive an indication of ongoing traffic from a plurality of UEs 115 connected to the anchor UE 115 (e.g., an indication of a traffic pattern at each of the plurality of UEs 115), and the anchor UE 115 may determine the FFP configuration for each UE based on the traffic pattern at the UE 115 (e.g., and traffic patterns at other UEs 115). Additionally or alternatively, the anchor UE 115 may receive information (e.g., related to a traffic pattern at each of the plurality of UEs 115) from the network entity 105, and the anchor UE 115 may signal the FFP configuration (e.g., for resource allocation mode 1 for sidelink communication) based on the information received from the network entity 105. In other aspects, the FFP configuration may be pre-configured at the UE 115 - a , or the UE 115 - a may self-configure the FFP configuration (eg, each UE 115 may configure its own FFP based on its own traffic).

[0076] Once UE 115-a is able to identify the appropriate FFP configuration, UE 115-a may communicate with other UEs 115 (e.g., UE 115-c) according to the FFP configuration. For example, UE 115-a may perform a channel access procedure to obtain access to a COT (e.g., within an FFP or across one or more FFPs), and UE 115-a may send sidelink data 215 to UE 115-c in the COT. In addition, UE 115-a may support efficient techniques for contending for access to a shared channel at the boundaries of an FFP according to the FFP configuration. If UE 115-a does not have sidelink data 215 to send at the beginning of the FFP, UE 115-a may not initiate a channel access procedure (e.g., initiate an FFP or COT) to obtain access to a shared channel during the FFP. Otherwise, if UE 115-a has sidelink data 215 to send at the start of FFP, and UE 115-a is able to share the COT with another UE 115, UE 115-a can use the techniques described herein to determine whether to initiate a channel access procedure to occupy a shared channel during FFP or to share the COT with another UE 115.

[0077] According to some aspects, in the case where there are multiple FFPs in the sidelink communication, in order to reduce the probability that one UE 115 blocks one or more other UEs 115 from accessing the channel, a group-based FFP configuration may be implemented. In such cases, UEs in the same group may share the same period and offset of the FFP. In this case, each UE 115 may observe an idle period according to the group-based FFP configuration. In some cases, if UE 115-a (UE0) is initiating COT at a given time, the applicable FFP for UE 115-a is the FFP associated with UE 115-a. In other cases, if UE 115-a (UE0) is sharing a COT initiated by UE 115-c (UE2) at a given time, the applicable FFP for UE 115-a (UE0) is the FFP associated with UE 115-c (UE2). In each case, UE 115 may not send anything during the LBT time (e.g., less than 16 μs) just before the FFP of UE 115 in the same group starts. In some cases, the UE group 115 may be based on a zone ID provided with sidelink configuration information, and users with the same zone ID share the same FFP configuration. In other cases, a central node (e.g., an anchor UE 115 selected from a plurality of UEs 115 or indicated by a network entity) may be identified, and a distance below a threshold between the central node and other UEs 115 indicates that the UEs 115 share the same zone ID and are therefore in the same group.

[0078] In some cases, if all UEs 115 in a group align the FFP, multiple UEs 115 may contend for the channel at the same time and cause a collision. In order to reduce the possibility of collisions in the LBT procedure between multiple UEs 115 in the group, the UEs 115 may perform one or more collision mitigation procedures. For example, a random starting point for the LBT procedure may be provided, such as by randomly selecting a cyclic prefix (CP) extension at each UE 115. Additionally or alternatively, a mapping rule may be provided between the length of the CP extension and the service priority (e.g., a higher priority service may be mapped to a shorter CP extension).

[0079] In some cases, a set of one or more rules may be defined for determining which UE 115 may initiate channel contention for FFP. For example, a predefined rule indicating which device may initiate FFP may be provided (e.g., via sidelink configuration information, or predefined rules programmed at each UE 115) (e.g., UE 115 with longer traffic has a higher probability of initiating FFP, UE 115 with higher priority traffic has a higher probability of initiating FFP, or a combination thereof). In other examples, the UE 115 may randomly determine which device may initiate FFP (e.g., based on UE ID). In other examples, a network entity or a central node may decide which UE 115 may initiate FFP (e.g., for mode 1, the network entity may assign an appropriate UE 115 to initiate FFP based on the sidelink traffic mode, or for mode 2, all sidelink devices in the same group will notify the central node of their own traffic, and the central node may decide which UE may initiate FFP based on the collected information). In yet other examples, an FFP reserved field may be provided with SCI 1 (eg, in an FFP reserved field indicating which FFP UE 115 is requesting), and other UEs 115 may avoid contending for channel access within the reserved FFP.

[0080] Figure 3 Examples of different FBE configurations 300 for channel access techniques supporting FBE in sidelink communications using shared spectrum in accordance with one or more aspects of the present disclosure are illustrated. UE 115 may use multiple time slots for communication, and the sidelink UE may use a subset of these time slots for sidelink communications (e.g., according to a sidelink resource pool). The time slots used for communication at UE 115 may include time slots available for sidelink 315 and time slots not available for sidelink 320. Figure 3 In the example of , the length of the FFP can be configured as 4 physical time slots, and the FFP can be 2ms when the SCS is 30kHz. In some cases, there may be one or more ways to construct the FFP for sidelink communication in the shared spectrum (e.g., and the alignment of the FFP with the logical time slot). The FFP may follow the specified values ​​or a subset of these values.

[0081] In the first example 305, three FFPs 325 are illustrated, including a first FFP 325-a, a second FFP 325-b, and a third FFP 325-c. In this example, the side link service may not be aligned with the starting point of the second FFP 325-b because the first time slot available for the side link in the second FFP 325-b is not the first time slot in the second FFP 325-b. Therefore, the UE 115 may not occupy the channel during the second FFP 325-b. On the contrary, the UE 115 may occupy the channel during the first FFP 325-a and the third FFP 325-c. In the second example 310, the resource configuration of the side link resource pool may be based on the FFP configuration. The resource configuration of the side link resource pool may ensure that the time slot for the side link 315 is located at the FFP starting point (e.g., the first time slot in each FFP). For example, in the second example 310, the first time slot in each of the FFPs 330 (including the first FFP 330-a, the second FFP 330-b, and the third FFP 330-c) may be an available time slot for the side link 315. Therefore, the UE 115 may occupy the channel during each FFP 330 of this example. According to various techniques such as those discussed herein, the UE 115 in the wireless communication system 100 may use the reference Figure 3 Any of the FFP structures described can be used for sidelink communications in a shared spectrum. Figure 2 As discussed, in some aspects, UEs 115 in the same UE group may use the same FFP. In other aspects, UEs 115 in the same UE group may use different FFPs, and reference is made to Figure 4 and Figure 5 Exemplary techniques for channel contention in such aspects are discussed.

[0082] Figure 4 An example of idle periods of different FBE configurations 400 for a channel access technique supporting FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is illustrated. In this example, three UEs 115 may exist and have different FFP configurations, including a first FFP configuration 405 of a first UE (UE0), a second FFP configuration 410 of a second UE (UE1), and a third FFP configuration 415 of a third UE (UE2). The first FFP configuration 405 may have a first FFP duration 420, which may include an associated transmit period 425 and an idle period 430. The second FFP configuration 410 may have a second FFP duration 435, which may include an associated transmit period 440 and an idle period 445. The third FFP configuration 415 may have a third FFP duration 450, which may include an associated transmit period 455 and an idle period 460.

[0083] According to various aspects, such different FFPs (e.g., different periods and offsets) for UEs with the same zone ID or in relatively close proximity may cause one UE to persistently block one or more other UEs. To avoid such persistent blocking, a joint mode may be configured across each of the UEs in the same UE group (e.g., for UEs with the same zone ID). Figure 4 Several options for this federation mode are illustrated, although other examples may be implemented and are within the scope of the present disclosure. Figure 4 In each of the described options in the examples of , a first UE (UE0) shares an FFP of a second UE (UE1) during a first instance of a first FFP duration 420, the first UE (UE0) transmits data to the second UE (UE1), and each of the first UE (UE0), the second UE (UE1), and the third UE (UE2) are in the same UE group (e.g., UEs with the same zone ID or within a relatively close proximity). In the first option 465, the first UE (UE0) may follow all idle periods of each of the first FFP 420, the second FFP 435, and the third FFP 450 of the UEs with the same zone ID and the UEs to which the first UE (UE0) transmits. In this first option 465, the first UE does not transmit anything during an instance of the first idle period 430, the second idle period 445, or the third idle period 460.

[0084] In the second option 470, UE0 may follow the idle period of the FFP of the UE (in this example, which corresponds to UE1) with which it is sharing the FFP start time. In this option 470, for other UEs, which may include UEs with the same zone ID and UEs to which the first UE transmits, corresponding to UE2 in this example, UE0 may refrain from transmitting during the LBT time (e.g., less than 16 μs) just before the start of the FFP of the other UEs (e.g., UE1 and UE2 in the subsequent FFP 420). Therefore, in Figure 4 In the example of , for the second option 470 , UE0 follows the first idle period 430 and the second idle period 445 of the first instance of FFP 420 , and refrains from transmitting during the first LBT 475 of UE1 and the second LBT 480 of UE2 in subsequent instances of FFP 420 .

[0085] In a third option 485, UE0 may follow the idle period of the FFP of the UE with which it is sharing the FFP start time (e.g., UE1 during the first instance of FFP 420 in this example), and for other UEs, not transmit during the LBT time (e.g., less than 16 μs) just before the start of the FFP of the UE to which UE0 is transmitting (corresponding to UE1 in this example). Thus, Figure 4 The third option 485 of the example provides that UE0 follows the first idle period 430 and the second idle period 445 during the first instance of FFP 420, and UE0 refrains from transmitting during the first LBT 475 of UE1 during subsequent instances of FFP 420.

[0086] Since different UEs have different FFPs, the FFP configuration may be shared with other UEs, and each UE may use the shared FFP configuration to determine a joint mode for performing channel access. In some cases, the UE may use an SCI (e.g., SCI2) to indicate the FFP configuration. In some cases, the SCI may indicate the period and offset of the FFP, or may include a dynamic indication of the duration of an available shared period. In other cases, the UE may exchange FFP configurations during the initial sidelink connection establishment (e.g., sent via a physical sidelink shared channel (PSSCH)). In some cases, the FFP configuration of a group of UEs with the same zone ID may be shared among the group. For example, an anchor UE may groupcast the FFP configuration of all UEs with the same zone ID, or each UE may announce its FFP configuration in the SCI (e.g., in SCI2). Figure 4 In the example of , in some cases, resource consumption can be used because UEs with the same zone ID will not compete in a subsequent FFP regardless of whether other UEs compete for the channel. According to various aspects, the UE can send a blanking request for a subsequent FFP, and other UEs can refrain from channel contention based on the blanking request and compete for channel access in other ways. Figure 5 Examples of such blanking indication techniques are discussed.

[0087] Figure 5 An example of idle periods for different FBE configurations 500 for supporting a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is illustrated. Figure 4 , three UEs 115 may exist and have different FFP configurations, including a first FFP configuration 505 of a first UE (UE0), a second FFP configuration 510 of a second UE (UE1), and a third FFP configuration 515 of a third UE (UE2). The first FFP configuration 505 may have a first FFP duration 520, which may include an associated transmit period 525 and an idle period 530. The second FFP configuration 510 may have a second FFP duration 535, which may include an associated transmit period 540 and an idle period 545. The third FFP configuration 515 may have a third FFP duration 550, which may include an associated transmit period 555 and an idle period 560.

[0088] According to various aspects, a UE may send a blanking request 565, which may indicate to other UEs that the UE sending the blanking request 565 will contend for channel access within a subsequent FFP. Figure 5 In the example of , a third UE (UE2) may send a blanking request 565 during a second instance of the third FFP duration 550, indicating that UE2 will contend for channel access in a subsequent instance of the third FFP duration 550 (e.g., the next FFP instance in time). For the FFP associated with the blanking request 565 request, the blanking request 565 may indicate to other UEs (such as UE0) to follow the idle period, or to refrain from transmitting during the LBT time. Figure 5 In each of the described options in the examples of , the first UE (UE0) shares the FFP of the second UE (UE1) during the first instance of the first FFP duration 520, the first UE (UE0) sends data to the second UE (UE1), and each of the first UE (UE0), the second UE (UE1), and the third UE (UE2) has the same zone ID. In the first option 570, UE0 may follow the idle period of each of the first FFP 520 and the second FFP 535 to which UE0 sends, shares the FFP start time, or sends a blanking request 565. In this first option 570, UE0 may not send anything during the instances of the first idle period 530 and the second idle period 545, and may not send anything during the instance of the third idle period 560 after the blanking request 565.

[0089] In a second option 575, UE0 may follow the idle period of the FFP of the UE with which it is sharing the FFP start time, which in this example corresponds to UE1 for the first instance of the first FFP duration 520. In this option 575, for other UEs corresponding to UE1 in subsequent instances of the first FFP duration 520 and UE2 in this example, UE0 may refrain from transmitting during the LBT time (e.g., less than 16 μs) just before the start of the FFP of the UE to which UE0 transmits or sends the blanking request 565 (e.g., UE1 and UE2 in the subsequent FFP 420). Thus, in Figure 5 In the example of , for the second option 575 , UE0 follows the first idle period 530 and the second idle period 545 of the first instance of FFP 420 , and refrains from transmitting during the first LBT 580 of UE1 in subsequent instances of FFP 420 and the second LBT 585 of UE2 that occurs after the blanking request 565 .

[0090] In some cases, the blanking request 565 may be a one-bit indication provided in the SCI to indicate whether a blanking request exists. In some cases, the blanking request 565 may be provided in each case where the device wishes to contend for channel access, which may be referred to as a single blanking request. In other cases, the blanking request 565 may be a persistent or semi-static blanking request applied to multiple subsequent FFPs, which may be referred to as a semi-static blanking request. Such a semi-static blanking request may allow a device with periodic services to avoid sending a separate blanking request 565 for each transmission. In some cases, an indication of a single blanking request or a semi-static blanking request may be provided by a bit sent with the SCI (e.g., SCI2). In such examples, one bit of the blanking request 565 may indicate whether a single request exists, and another bit may indicate whether a semi-static blanking request exists. In other examples, an RRC configuration that can configure the blanking request 565 may be provided. In some cases, a UE with ongoing services may have time constraints and high priority services, and the UE may not want to stop its own services and remain silent to allow other UEs to compete for channels during the FFP. In such cases, along with the blanking request 565, a priority indication for the associated traffic may also be provided, and the UE receiving the blanking request 565 may determine whether to suppress transmission during an idle period or during the LBT time just before the associated FFP begins. In some cases, the priority indication may be provided in the blanking request 565 using three bits to indicate up to eight different priority levels.

[0091] Additionally or alternatively, a UE (e.g., UE1) that dynamically blanks one or more symbols for channel contention of other UEs (e.g., UE2) may provide an indication of which symbols are blanked to one or more other UEs (e.g., UE0, etc.) communicating with the UE. For example, a UE (e.g., UE2) may send a blanking request 565, and a receiving UE (e.g., UE1) may determine to fulfill the blanking request and may indicate actual transmitted symbols for sidelink communication with one or more other UEs in the SCI, such as by a dynamic indication of an actual transmitted length of the symbol, a dynamic indication of the number of blanked symbols, and / or the position of the blanked symbols.

[0092] Figure 6 A block diagram 600 of a device 605 supporting a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is shown. The device 605 may be an example of aspects of a UE 115 as described herein. The device 605 may include a receiver 610, a transmitter 615, and a communication manager 620. The device 605 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0093] The receiver 610 may provide means for receiving information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to channel access techniques for FBE in sidelink communications using shared spectrum), user data, control information, or any combination thereof. The information may be communicated to other components of the device 605. The receiver 610 may utilize a single antenna or a collection of multiple antennas.

[0094] The transmitter 615 may provide means for transmitting signals generated by other components of the device 605. For example, the transmitter 615 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to channel access techniques for FBE in sidelink communications using shared spectrum), user data, control information, or any combination thereof. In some examples, the transmitter 615 may be co-located with the receiver 610 in a transceiver module. The transmitter 615 may utilize a single antenna or a collection of multiple antennas.

[0095] The communication manager 620, the receiver 610, the transmitter 615, or various combinations thereof, or various components thereof may be examples of means for performing various aspects of the channel access techniques for FBE in sidelink communications using shared spectrum as described herein. For example, the communication manager 620, the receiver 610, the transmitter 615, or various combinations thereof, or components thereof may support methods for performing one or more of the functions described herein.

[0096] In some examples, the communication manager 620, the receiver 610, the transmitter 615, or various combinations or components thereof may be implemented in hardware (e.g., in a communication management circuit). The hardware may include a processor, a digital signal processor (DSP), a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a microcontroller, discrete gate or transistor logic, discrete hardware components, or any combination thereof that is configured to or otherwise supports components for performing the functions described in the present disclosure. In some examples, the processor and a memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by executing instructions stored in the memory by the processor).

[0097] Additionally or alternatively, in some examples, the communication manager 620, the receiver 610, the transmitter 615, or various combinations or components thereof may be implemented in code executed by a processor (e.g., as communication management software or firmware). If implemented in code executed by a processor, the functionality of the communication manager 620, the receiver 610, the transmitter 615, or various combinations or components thereof may be performed by a general purpose processor (e.g., configured as or otherwise supporting components for performing the functions described in the present disclosure), a DSP, a CPU, an ASIC, an FPGA, a microcontroller, or any combination of these or other programmable logic devices.

[0098] In some examples, communication manager 620 may be configured to perform various operations (e.g., receive, obtain, monitor, output, transmit) using or otherwise cooperating with receiver 610, transmitter 615, or both. For example, communication manager 620 may receive information from receiver 610, transmit information to transmitter 615, or be integrated in conjunction with receiver 610, transmitter 615, or both to obtain information, output information, or perform various other operations as described herein.

[0099] According to examples as disclosed herein, the communication manager 620 may support wireless communications at a first UE. For example, the communication manager 620 may be configured to or otherwise support a component for sending an indication of an FFP configuration for sidelink communications between at least the first UE and the second UE operating in FBE mode to at least a second UE, the FFP configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure. The communication manager 620 may be configured to or otherwise support a component for monitoring a sidelink channel during a first idle period according to a channel access procedure, the first idle period being identified based on an idle period configuration of the FFP configuration. The communication manager 620 may be configured to or otherwise support a component for sending sidelink communications to at least a second UE based on a channel access procedure indicating that the sidelink channel is available for sidelink communications.

[0100] By including or configuring the communication manager 620 according to the examples described herein, the device 605 (e.g., a processor controlling or otherwise coupled to the receiver 610, the transmitter 615, the communication manager 620, or a combination thereof) can support techniques for reduced processing, reduced overhead, and reduced power consumption. Specifically, because the device can provide COT sharing or can be configured to either initiate a channel access procedure or share the COT, the device can more efficiently contend for access to a shared channel and can avoid unnecessary execution of channel access procedures. Therefore, less time and processing resources can be used at the device for channel access procedures, and the device can achieve reduced processing, reduced overhead, reduced power consumption, or any combination thereof.

[0101] Figure 7 A block diagram 700 of a device 705 supporting a channel access technique for FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is shown. The device 705 may be an example of aspects of the device 605 or UE 115 as described herein. The device 705 may include a receiver 710, a transmitter 715, and a communication manager 720. The device 705 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

[0102] The receiver 710 may provide means for receiving information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to channel access techniques for FBE in sidelink communications using shared spectrum), user data, control information, or any combination thereof. The information may be communicated to other components of the device 705. The receiver 710 may utilize a single antenna or a collection of multiple antennas.

[0103] The transmitter 715 may provide means for transmitting signals generated by other components of the device 705. For example, the transmitter 715 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to channel access techniques for FBE in sidelink communications using shared spectrum), user data, control information, or any combination thereof. In some examples, the transmitter 715 may be co-located with the receiver 710 in a transceiver module. The transmitter 715 may utilize a single antenna or a collection of multiple antennas.

[0104] The device 705 or its various components may be examples of components for performing various aspects of the channel access technique of FBE in the sidelink communication using shared spectrum as described herein. For example, the communication manager 720 may include the FFP configuration manager 725, the LBT manager 730, the sidelink communication manager 735, or any combination thereof. The communication manager 720 may be an example of various aspects of the communication manager 620 as described herein. In some examples, the communication manager 720 or its various components may be configured to use or otherwise cooperate with the receiver 710, the transmitter 715, or both to perform various operations (e.g., receive, obtain, monitor, output, send). For example, the communication manager 720 may receive information from the receiver 710, transmit information to the transmitter 715, or be integrated with the receiver 710, the transmitter 715, or both to obtain information, output information, or perform various other operations as described herein.

[0105] According to examples as disclosed herein, the communication manager 720 may support wireless communication at a first UE. The FFP configuration manager 725 may be configured to or otherwise support a component for sending an indication of an FFP configuration for sidelink communication between at least the first UE and the second UE operating in FBE mode to at least a second UE, the FFP configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure. The LBT manager 730 may be configured to or otherwise support a component for monitoring a sidelink channel during a first idle period according to a channel access procedure, the first idle period being identified based on an idle period configuration of the FFP configuration. The sidelink communication manager 735 may be configured to or otherwise support a component for sending sidelink communication to at least a second UE based on a channel access procedure indicating that the sidelink channel is available for sidelink communication.

[0106] Figure 8 A block diagram 800 of a communication manager 820 supporting a channel access technique for FBE in a sidelink communication using a shared spectrum is shown according to one or more aspects of the present disclosure. The communication manager 820 may be an example of aspects of the communication manager 620, the communication manager 720, or both as described herein. The communication manager 820 or its various components may be examples of components for performing various aspects of the channel access technique for FBE in a sidelink communication using a shared spectrum as described herein. For example, the communication manager 820 may include an FFP configuration manager 825, an LBT manager 830, a sidelink communication manager 835, a group identification manager 840, a collision avoidance manager 845, an FFP mode manager 850, a blanking request manager 855, or any combination thereof. Each of these components may communicate directly or indirectly with each other (e.g., via one or more buses).

[0107] According to examples as disclosed herein, the communication manager 820 may support wireless communication at a first UE. The FFP configuration manager 825 may be configured to or otherwise support a component for sending an indication of an FFP configuration for sidelink communication between at least the first UE and the second UE operating in FBE mode to at least a second UE, the FFP configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure. The LBT manager 830 may be configured to or otherwise support a component for monitoring a sidelink channel during a first idle period according to a channel access procedure, the first idle period being identified based on an idle period configuration of the FFP configuration. The sidelink communication manager 835 may be configured to or otherwise support a component for sending a sidelink communication to at least a second UE based on a channel access procedure indicating that the sidelink channel is available for sidelink communication.

[0108] In some examples, the first UE and the second UE are in a first UE group, and wherein the same FFP configuration is used at each UE in the first UE group. In some examples, the group identification manager 840 may be configured as or otherwise support a component for receiving side link configuration information indicating a zone identification for side link communication, wherein the first UE group each has the same zone identification. In some examples, the group identification manager 840 may be configured as or otherwise support a component for receiving side link configuration information indicating a central node associated with the first UE group, and the first UE group includes UEs whose proximity to the central node is less than a threshold. In some examples, the central node is selected at a network entity or at one or more UEs in the first UE group.

[0109] In some examples, to support monitoring the side link channel, the conflict avoidance manager 845 may be configured as or otherwise support a component for determining to contend for channel access during the first idle period based on a conflict avoidance procedure, wherein the conflict avoidance procedure is based on a random starting point for channel contention, a priority rule for channel contention, a reservation indication provided from the second UE, or any combination thereof. In some examples, to support monitoring the side link channel, the conflict avoidance manager 845 may be configured as or otherwise support a component for monitoring the side link channel during the first idle period based on a conflict avoidance procedure. In some examples, the conflict avoidance procedure provides for mapping higher priority traffic to be sent in the side link communication to an earlier start time for initiating a channel access procedure. In some examples, the conflict avoidance procedure prioritizes channel contention for UEs based on one or more of the following: the amount of traffic to be sent in the side link communication, the priority of the traffic to be sent, a random selection based on the identity of the UE, a priority indication provided from a central node of a UE group including the first UE and the second UE, or any combination thereof.

[0110] In some examples, the collision avoidance manager 845 may be configured or otherwise support components for receiving an FFP reservation indication from a second UE during a second idle period. In some examples, the collision avoidance manager 845 may be configured or otherwise support components for suppressing initiation of a channel access procedure during the second idle period based on the FFP reservation indication. In some examples, the second UE has a different FFP configuration from the first UE, and a joint mode is provided for performing a channel access procedure at each of the first UE and the second UE. In some examples, both the first UE and the second UE have the same zone identity for sidelink communication, and each UE having the same zone identity follows an idle period associated with the FFP configuration of each UE having the same zone identity.

[0111] In some examples, the joint mode provides that each UE having a first zone identifier for sidelink communication and sharing a first FFP configuration follows an idle period associated with the first FFP configuration. In some examples, the joint mode provides that the first UE blanks transmission during monitoring periods of other UEs to which the first UE transmits sidelink communications. In some examples, the joint mode further provides that each UE having a first zone identifier blanks transmission during monitoring periods of other UEs having the first zone identifier and a different FFP configuration.

[0112] In some examples, the FFP configuration manager 825 may be configured to or otherwise support components for receiving an indication of the FFP configuration for at least a second UE via sidelink control information. In some examples, the sidelink control information indicates one or more of the periodicity of the FFP, an offset associated with the FFP, a duration of available channel occupancy time shared during the FFP, or any combination thereof. In some examples, the sidelink control information indicating the fixed frame configuration is provided as part of an initial connection that initializes sidelink communications between the first UE and at least the second UE. In some examples, the sidelink control information is provided in an anchor UE multicast transmission to a set of multiple UEs each having a first zone identifier for sidelink communications, or the sidelink control information is provided individually from each UE in the set of multiple UEs each having a first zone identifier.

[0113] In some examples, the blanking request manager 855 may be configured to or otherwise support a component for sending a blanking request to at least a second UE before monitoring a side link channel, the blanking request indicating a request for the second UE to suppress transmission during an LBT duration associated with a channel access procedure. In some examples, the blanking request is provided in a side link control information transmission from a first UE. In some examples, the blanking request is a single blanking request for a single FFP or a semi-static blanking request applied to two or more FFPs. In some examples, the blanking request further indicates a priority associated with a service to be sent from the first UE, and wherein the priority is used by at least the second UE to determine whether to blank the transmission during the LBT duration. In some examples, the first UE provides an indication of whether the side link communication includes one or more symbols that have been blanked based on received blanking requests from different UEs.

[0114] Fig. 9 A diagram of a system 900 including a device 905 supporting a channel access technique for FBE in sidelink communications using a shared spectrum in accordance with one or more aspects of the present disclosure is shown. The device 905 may be an example of a device 605, a device 705, or a UE 115 as described herein, or include components thereof. The device 905 may communicate (e.g., wirelessly) with one or more network entities 105, one or more UEs 115, or any combination thereof. The device 905 may include components for two-way voice and data communications, including components for sending and receiving communications, such as a communication manager 920, an input / output (I / O) controller 910, a transceiver 915, an antenna 925, a memory 930, a code 935, and a processor 940. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., a bus 945).

[0115] I / O controller 910 may manage input and output signals for device 905. I / O controller 910 may also manage peripheral devices that are not integrated into device 905. In some cases, I / O controller 910 may represent a physical connection or port to an external peripheral device. In some cases, I / O controller 910 may utilize an operating system, such as or another known operating system. Additionally or alternatively, I / O controller 910 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I / O controller 910 may be implemented as part of a processor (such as processor 940). In some cases, a user may interact with device 905 via I / O controller 910 or via hardware components controlled by I / O controller 910.

[0116] In some cases, the device 905 may include a single antenna 925. However, in some other cases, the device 905 may have more than one antenna 925, which may be capable of concurrently transmitting or receiving multiple wireless transmissions. The transceiver 915 may communicate bidirectionally via one or more antennas 925, wired or wireless links, as described herein. For example, the transceiver 915 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 915 may also include a modem for: modulating packets; providing the modulated packets to one or more antennas 925 for transmission; and demodulating packets received from one or more antennas 925. The transceiver 915 or the transceiver 915 and one or more antennas 925 may be examples of transmitters 615, transmitters 715, receivers 610, receivers 710, or any combination thereof or components thereof as described herein.

[0117] The memory 930 may include random access memory (RAM) and read-only memory (ROM). The memory 930 may store computer-readable, computer-executable code 935 including instructions that, when executed by the processor 940, cause the device 905 to perform various functions described herein. The code 935 may be stored in a non-transitory computer-readable medium, such as a system memory or another type of memory. In some cases, the code 935 may not be directly executable by the processor 940, but may (e.g., when compiled and executed) cause the computer to perform the functions described herein. In some cases, the memory 930 may also include, among other things, a basic I / O system (BIOS) that may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0118] The processor 940 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 940 may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated into the processor 940. The processor 940 may be configured to execute computer-readable instructions stored in a memory (e.g., a memory 930) to cause the device 905 to perform various functions (e.g., functions or tasks of a channel access technology supporting FBE in sidelink communications using a shared spectrum). For example, the device 905 or a component of the device 905 may include a processor 940 and a memory 930 coupled to or coupled to the processor 940, and the processor 940 and the memory 930 are configured to perform the various functions described herein.

[0119] According to examples as disclosed herein, the communication manager 920 may support wireless communications at a first UE. For example, the communication manager 920 may be configured to or otherwise support a component for sending an indication of an FFP configuration for sidelink communications between at least the first UE and the second UE operating in FBE mode to at least a second UE, the FFP configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure. The communication manager 920 may be configured to or otherwise support a component for monitoring a sidelink channel during a first idle period according to a channel access procedure, the first idle period being identified based on an idle period configuration of the FFP configuration. The communication manager 920 may be configured to or otherwise support a component for sending sidelink communications to at least a second UE based on a channel access procedure indicating that the sidelink channel is available for sidelink communications.

[0120] By including or configuring a communication manager 920 according to the examples described herein, the device 905 can support techniques for reduced processing, reduced overhead, and reduced power consumption. Specifically, because the device can provide COT sharing or can be configured to initiate a channel access procedure or share the COT, the device can more efficiently compete for access to a shared channel and can avoid unnecessary execution of channel access procedures. Therefore, less time and processing resources can be used at the device for channel access procedures, and the device can achieve reduced processing, reduced overhead, reduced power consumption, or any combination thereof.

[0121] In some examples, the communication manager 920 may be configured to perform various operations (e.g., receive, monitor, transmit) using or otherwise cooperating with the transceiver 915, one or more antennas 925, or any combination thereof. Although the communication manager 920 is illustrated as a separate component, in some examples, one or more functions described with reference to the communication manager 920 may be supported or performed by the processor 940, the memory 930, the code 935, or any combination thereof. For example, the code 935 may include instructions executable by the processor 940 to cause the device 905 to perform various aspects of the channel access technique for FBE in sidelink communications using shared spectrum as described herein, or the processor 940 and the memory 930 may be otherwise configured to perform or support such operations.

[0122] Fig.10 A flow chart illustrating a method 1000 for a channel access technique supporting FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is shown. The operations of the method 1000 may be implemented by a UE or a component thereof as described herein. For example, the operations of the method 1000 may be implemented by a UE or a component thereof as described in reference to Figures 1 to 9The UE 115 described herein may be executed. In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the described functions.

[0123] Optionally, at 1005, the method may include: receiving an indication of the FFP configuration of at least the second UE via the sidelink control information. The operations of 1005 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1005 may be performed as described in reference to Figure 8 The described FFP configuration manager 825 is executed.

[0124] At 1010, the method may include: sending an indication of an FFP configuration for sidelink communication between at least a first UE and a second UE operating in FBE mode to at least a second UE, the FFP configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure. The operations of 1010 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1010 may be performed as described in reference to Figure 8 The described FFP configuration manager 825 is executed.

[0125] At 1015, the method may include: monitoring the side link channel during a first idle period according to a channel access procedure, the first idle period being identified based on an idle period configuration of the FFP configuration. The operations of 1015 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1015 may be performed as described in reference to Figure 8 The described LBT manager 830 is executed.

[0126] At 1020, the method may include: sending the sidelink communication to at least the second UE based on the channel access procedure indicating that the sidelink channel is available for sidelink communication. The operations of 1020 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1020 may be performed as described in reference to Figure 8 The described side link communication manager 835 is executed.

[0127] Fig.11 A flow chart illustrating a method 1100 for a channel access technique supporting FBE in sidelink communications using a shared spectrum according to one or more aspects of the present disclosure is shown. The operations of the method 1100 may be implemented by a UE or a component thereof as described herein. For example, the operations of the method 1100 may be implemented by a UE or a component thereof as described in reference to Figures 1 to 9 The UE 115 described herein may be executed. In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the described functions.

[0128] At 1105, the method may include: sending an indication of an FFP configuration for sidelink communication between at least the first UE and the second UE operating in FBE mode to at least the second UE, the FFP configuration including an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure. The operations of 1105 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1105 may be performed as described in reference Figure 8 The described FFP configuration manager 825 is executed.

[0129] At 1110, the method may include: monitoring the side link channel during a first idle period according to a channel access procedure, the first idle period being identified based on an idle period configuration of the FFP configuration. The operations of 1110 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1110 may be performed as described in reference to Figure 8 The described LBT manager 830 is executed.

[0130] At 1115, the method may include: determining to contend for channel access during the first idle period based on a conflict avoidance procedure, wherein the conflict avoidance procedure is based on a random starting point for channel contention, a priority rule for channel contention, a reservation indication provided from the second UE, or any combination thereof. The operations of 1115 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1115 may be performed as described in reference Figure 8 The described conflict avoidance manager 845 is executed.

[0131] At 1120, the method may include monitoring the side link channel during the first idle period based on a collision avoidance procedure. The operations of 1120 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1120 may be performed as described in reference to Figure 8 The described conflict avoidance manager 845 is executed.

[0132] At 1125, the method may include: receiving an FFP reservation indication from a second UE during a second idle period. The operations of 1125 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1125 may be performed as described in reference to Figure 8 The described conflict avoidance manager 845 is executed.

[0133] At 1130, the method may include: refraining from initiating a channel access procedure during the second idle period based on the FFP reservation indication. The operations of 1130 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1130 may be performed as described in reference Figure 8The described conflict avoidance manager 845 is executed.

[0134] At 1135, the method may include: sending the sidelink communication to at least the second UE based on the channel access procedure indicating that the sidelink channel is available for sidelink communication. The operations of 1135 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1135 may be performed as described in reference to Figure 8 The described side link communication manager 835 is executed.

[0135] The following provides an overview of various aspects of the disclosure:

[0136] Aspect 1: A method for wireless communication at a first UE, the method comprising: sending an indication of a fixed frame period configuration for sidelink communication between at least the first UE and the second UE operating in a frame-based equipment mode to at least a second UE, the fixed frame period configuration comprising an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure; monitoring a sidelink channel during a first idle period according to the channel access procedure, the first idle period being identified at least in part based on the idle period configuration of the fixed frame period configuration; and sending sidelink communication to at least the second UE based at least in part on the channel access procedure indicating that the sidelink channel is available for sidelink communication.

[0137] Aspect 2: The method according to aspect 1, wherein the first UE and the second UE are in a first UE group, and wherein the same fixed frame period configuration is used at each UE in the first UE group.

[0138] Aspect 3: According to the method of aspect 2, the method also includes: receiving side link configuration information indicating a zone identifier for side link communication, wherein the first UE group each has the same zone identifier.

[0139] Aspect 4: According to the method described in any one of Aspects 2 to 3, the method further includes: receiving side link configuration information indicating a central node associated with the first UE group, and the first UE group includes UEs whose proximity to the central node is less than a threshold.

[0140] Aspect 5: The method according to aspect 4, wherein the central node is selected at a network entity or at one or more UEs in the first UE group.

[0141] Aspect 6: A method according to any one of Aspects 1 to 5, wherein the monitoring of the side link channel includes: determining to compete for channel access during the first idle period based at least in part on a conflict avoidance procedure, wherein the conflict avoidance procedure is based at least in part on a random starting point for channel contention, a priority rule for channel contention, a reservation indication provided from the second UE, or any combination thereof; and monitoring the side link channel during the first idle period based at least in part on the conflict avoidance procedure.

[0142] Aspect 7: The method according to aspect 6, wherein the collision avoidance procedure provides for mapping higher priority traffic to be transmitted in the sidelink communication to an earlier start time for initiating the channel access procedure.

[0143] Aspect 8: A method according to any one of Aspects 6 to 7, wherein the conflict avoidance procedure prioritizes channel contention of UEs based at least in part on one or more of: the amount of traffic to be sent in the side link communication, the priority of the traffic to be sent, a random selection based on the identity of the UE, a priority indication provided from a central node of a UE group including the first UE and the second UE, or any combination thereof.

[0144] Aspect 9: According to the method described in any one of Aspects 6 to 8, the method further includes: receiving a fixed frame period reservation indication from the second UE in a second idle period; and suppressing initiation of the channel access procedure during the second idle period based at least in part on the fixed frame period reservation indication.

[0145] Aspect 10: A method according to any one of Aspects 1 to 9, wherein the second UE has a fixed frame period configuration different from that of the first UE, and a joint mode is provided for performing the channel access procedure at each of the first UE and the second UE.

[0146] Aspect 11: A method according to Aspect 10, wherein both the first UE and the second UE have the same zone identifier for sidelink communication, and wherein each UE having the same zone identifier follows an idle period associated with the fixed frame period configuration of each UE having the same zone identifier.

[0147] Aspect 12: A method according to any one of Aspects 10 to 11, wherein the joint mode stipulates that each UE having a first zone identifier for sidelink communication and sharing a first fixed frame period configuration follows an idle period associated with the first fixed frame period configuration, and the joint mode stipulates that the first UE blanks transmission during a monitoring period of other UEs to which the first UE sends sidelink communications.

[0148] Aspect 13: The method according to aspect 12, wherein the joint mode further stipulates that each UE having the first region identifier blanks transmission during the monitoring period of other UEs having the first region identifier and a different fixed frame period configuration.

[0149] Aspect 14: According to the method according to any one of Aspects 1 to 13, the method also includes: receiving an indication of the fixed frame period configuration of at least the second UE via sidelink control information.

[0150] Aspect 15: A method according to Aspect 14, wherein the sidelink control information indicates one or more of the periodicity of the fixed frame period, an offset associated with the fixed frame period, the duration of the available channel occupancy time shared during the fixed frame period, or any combination thereof.

[0151] Aspect 16: A method according to any one of Aspects 14 to 15, wherein the sidelink control information indicating the fixed frame configuration is provided as part of an initial connection, and the initial connection initializes the sidelink communication between the first UE and at least the second UE.

[0152] Aspect 17: A method according to any one of Aspects 14 to 16, wherein the sidelink control information is provided to multiple UEs each having a first zone identifier for sidelink communication in an anchor UE multicast transmission, or the sidelink control information is provided individually from each UE of the multiple UEs each having the first zone identifier.

[0153] Aspect 18: According to the method described in any one of Aspects 1 to 17, the method further includes: sending a blanking request to at least the second UE before monitoring the side link channel, the blanking request indicating a request for the second UE to suppress transmission during an LBT duration associated with the channel access procedure.

[0154] Aspect 19: The method according to aspect 18, wherein the blanking request is provided in a sidelink control information transmission from the first UE.

[0155] Aspect 20: The method according to any one of aspects 18 to 19, wherein the blanking request is a single blanking request for a single fixed frame period or a semi-static blanking request applied to two or more fixed frame periods.

[0156] Aspect 21: A method according to any one of Aspects 18 to 20, wherein the blanking request further indicates a priority associated with a service to be sent from the first UE, and wherein the priority is used at least at the second UE to determine whether to blank the transmission during the LBT duration.

[0157] Aspect 22: A method according to any one of aspects 18 to 21, wherein the first UE provides an indication of whether the sidelink communication includes one or more symbols that have been blanked based at least in part on received blanking requests from different UEs.

[0158] Aspect 23: An apparatus for performing wireless communications at a first UE, the method comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method according to any one of Aspects 1 to 22.

[0159] Aspect 24: An apparatus for wireless communication at a first UE, the method comprising: at least one component for performing the method according to any one of aspects 1 to 22.

[0160] Aspect 25: A non-transitory computer-readable medium storing a code for wireless communication at a first UE, the code comprising instructions executable by a processor to perform a method according to any one of aspects 1 to 22.

[0161] It should be noted that the methods described herein describe possible implementations, and that the various operations and steps may be rearranged or otherwise modified and that other implementations are possible. Furthermore, aspects from two or more methods may be combined.

[0162] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for example purposes, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein may also be applicable to networks other than LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to various other wireless communication systems, such as Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and other systems and radio technologies not explicitly mentioned herein.

[0163] The information and signals described herein may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the specification may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0164] The various illustrative blocks and components described in conjunction with the disclosure herein may be implemented or performed with a general purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0165] The functions described herein may be implemented using hardware, software executed by a processor, firmware, or any combination thereof. If implemented using software executed by a processor, the functions may be stored as one or more instructions or codes of a computer-readable medium, or sent using a computer-readable medium. Other examples and specific implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hard wiring, or a combination of any of these items. Features that implement the functions may also be physically located at different locations, including being distributed so that the various parts of the functions are implemented at different physical locations.

[0166] Computer-readable medium includes both non-transient computer storage medium and communication medium, and it includes any medium that facilitates computer program to be transmitted from one position to another position.Non-transient storage medium can be any available medium that can be accessed by general or special-purpose computer.By way of example and not limitation, non-transient computer-readable medium can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disc storage device, disk storage device or other magnetic storage device, or can be used for carrying or storing desired program code parts and any other non-transient medium that can be accessed by general or special-purpose computer or general or special-purpose processor in the form of instruction or data structure.In addition, any connection is appropriately referred to as computer-readable medium.For example, if software is sent from website, server or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology such as infrared, radio and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave are included in the definition of computer-readable medium. As used herein, disks and discs include CDs, laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs. Disks can reproduce data magnetically, and discs can reproduce data optically using lasers. Combinations of the above are also included within the scope of computer-readable media.

[0167] As used herein (including in the claims), "or" used in a list of items (e.g., a list of items followed by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, so that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). In addition, as used herein, the phrase "based on" should not be interpreted as a reference to a closed set of conditions. For example, an example step described as "based on condition A" can be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on."

[0168] The term "determining" encompasses a variety of actions, and thus, "determining" may include calculating, computing, processing, deriving, investigating, looking up (such as via looking up in a table, database or other data structure), ascertaining, and the like. Furthermore, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data stored in a memory), etc. Additionally, "determining" may include parsing, obtaining, selecting, choosing, establishing, and other such similar actions.

[0169] In the drawings, similar components or features may have the same reference label. In addition, various components of the same type may be distinguished by following the reference label with a dash and a second label to distinguish between the similar components. If only the first reference label is used in the specification, the description may apply to any of the similar components having the same first reference label, regardless of the second or other subsequent reference labels.

[0170] The descriptions set forth herein in conjunction with the accompanying drawings describe example configurations and do not represent all examples that may be implemented or within the scope of the claims. The term "example" as used herein means "used as an example, instance, or illustration," rather than "preferred" or "advantageous over other examples." The specific implementation includes specific details to provide an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some cases, known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0171] The description herein is provided to enable one of ordinary skill in the art to implement or use the present disclosure. Various modifications to the present disclosure will be apparent to one of ordinary skill in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a first user equipment (UE), the method comprising: sending, to at least a second UE, an indication of a fixed frame period configuration for sidelink communications between at least the first UE and the second UE operating in a frame-based equipment mode, the fixed frame period configuration comprising an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure; monitoring a sidelink channel during a first idle period according to the channel access procedure, the first idle period being identified based at least in part on the idle period configuration of the fixed frame period configuration; as well as A sidelink communication is sent to at least the second UE based at least in part on the channel access procedure indicating that the sidelink channel is available for sidelink communication.

2. The method of claim 1, wherein the first UE and the second UE are in a first UE group, and wherein the same fixed frame period configuration is used at each UE in the first UE group.

3. The method according to claim 2, further comprising: Sidelink configuration information indicating a zone identity for sidelink communication is received, wherein the first UE group each has a same zone identity.

4. The method according to claim 2, further comprising: Sidelink configuration information indicating a central node associated with the first UE group is received, and the first UE group includes UEs whose proximity to the central node is less than a threshold. 5 . The method according to claim 4 , wherein the central node is selected at a network entity or at one or more UEs in the first UE group.

6. The method of claim 1 , wherein the monitoring the sidelink channel comprises: determining to contend for channel access during the first idle period based at least in part on a collision avoidance procedure, wherein the collision avoidance procedure is based at least in part on a random starting point for channel contention, a priority rule for channel contention, a reservation indication provided from the second UE, or any combination thereof; as well as The sidelink channel is monitored during the first idle period based at least in part on the collision avoidance procedure.

7. The method of claim 6, wherein the collision avoidance procedure provides for mapping higher priority traffic to be transmitted in the sidelink communication to an earlier start time for initiating the channel access procedure.

8. The method of claim 6, wherein the conflict avoidance procedure prioritizes channel contention for UEs based at least in part on one or more of: the amount of traffic to be sent in the sidelink communication, the priority of the traffic to be sent, a random selection based on an identity of the UE, a priority indication provided from a central node of a UE group including the first UE and the second UE, or any combination thereof.

9. The method according to claim 6, further comprising: receiving a fixed frame period reservation indication from the second UE during a second idle period; as well as Initiating the channel access procedure during the second idle period is refrained from based at least in part on the fixed frame period reservation indication.

10. The method of claim 1, wherein the second UE has a different fixed frame period configuration from the first UE, and a joint mode is provided for performing the channel access procedure at each of the first UE and the second UE.

11. The method of claim 10, wherein both the first UE and the second UE have the same zone identifier for sidelink communication, and wherein each UE having the same zone identifier follows an idle period associated with the fixed frame period configuration of each UE having the same zone identifier.

12. The method according to claim 10, wherein: The joint mode provides that each UE having a first zone identity for sidelink communication and sharing a first fixed frame period configuration follows an idle period associated with the first fixed frame period configuration, and The joint mode provides for the first UE to blank transmissions during monitoring periods of other UEs to which the first UE transmits sidelink communications.

13. The method of claim 12, wherein the joint mode further specifies that each UE having the first region ID blanks transmission during the monitoring period of other UEs having the first region ID and a different fixed frame period configuration.

14. The method according to claim 1, further comprising: An indication of the fixed frame period configuration for at least the second UE is received via sidelink control information.

15. A method according to claim 14, wherein the sidelink control information indicates one or more of the periodicity of the fixed frame period, an offset associated with the fixed frame period, the duration of available channel occupancy time shared during the fixed frame period, or any combination thereof.

16. The method of claim 14, wherein the sidelink control information of the indication of the fixed frame configuration is provided as part of an initial connection that initializes sidelink communications between the first UE and at least the second UE.

17. The method of claim 14, wherein the sidelink control information is provided to a plurality of UEs each having a first zone identifier for sidelink communication in an anchor UE groupcast transmission, or the sidelink control information is provided individually from each of the plurality of UEs each having the first zone identifier.

18. The method according to claim 1, further comprising: Prior to said monitoring the sidelink channel, a blanking request is sent to at least the second UE, the blanking request indicating a request for the second UE to refrain from transmitting during a listen-before-talk (LBT) duration associated with the channel access procedure.

19. The method of claim 18, wherein the blanking request is provided in a sidelink control information transmission from the first UE.

20. The method of claim 18, wherein the blanking request is a single blanking request for a single fixed frame period or a semi-static blanking request applied to two or more fixed frame periods.

21. The method of claim 18, wherein the blanking request further indicates a priority associated with a service to be transmitted from the first UE, and wherein the priority is used by at least the second UE to determine whether to blank transmission during the LBT duration.

22. The method of claim 18, wherein the first UE provides an indication of whether the sidelink communication includes one or more symbols that have been blanked based at least in part on a received blanking request from a different UE.

23. An apparatus for wireless communication at a first user equipment (UE), the apparatus comprising: processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to: sending, to at least a second UE, an indication of a fixed frame period configuration for sidelink communications between at least the first UE and the second UE operating in a frame-based equipment mode, the fixed frame period configuration comprising an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure; monitoring a sidelink channel during a first idle period according to the channel access procedure, the first idle period being identified based at least in part on the idle period configuration of the fixed frame period configuration; as well as A sidelink communication is sent to at least the second UE based at least in part on the channel access procedure indicating that the sidelink channel is available for sidelink communication.

24. The apparatus of claim 23, wherein the first UE and the second UE are in a first UE group, and wherein the same fixed frame period configuration is used at each UE in the first UE group.

25. The apparatus of claim 23, wherein the instructions for monitoring the sidelink channel are executable by the processor to cause the apparatus to: determining to contend for channel access during the first idle period based at least in part on a collision avoidance procedure, wherein the collision avoidance procedure is based at least in part on a random starting point for channel contention, a priority rule for channel contention, a reservation indication provided from the second UE, or any combination thereof; and The sidelink channel is monitored during the first idle period based at least in part on the collision avoidance procedure.

26. The apparatus of claim 23, wherein the second UE has a different fixed frame period configuration from the first UE, and a joint mode is provided for performing the channel access procedure at each of the first UE and the second UE.

27. An apparatus for wireless communication at a first user equipment (UE), the apparatus comprising: means for sending, to at least a second UE, an indication of a fixed frame period configuration for sidelink communications between at least the first UE and the second UE operating in a frame-based equipment mode, the fixed frame period configuration comprising an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure; means for monitoring a sidelink channel during a first idle period in accordance with the channel access procedure, the first idle period being identified based at least in part on the idle period configuration of the fixed frame period configuration; and Means for sending sidelink communications to at least the second UE based at least in part on the channel access procedure indicating that the sidelink channel is available for sidelink communications.

28. The apparatus of claim 27, wherein the first UE and the second UE are in a first UE group, and wherein the same fixed frame period configuration is used at each UE in the first UE group.

29. A non-transitory computer-readable medium storing code for wireless communication at a first user equipment (UE), the code comprising instructions executable by a processor to: sending, to at least a second UE, an indication of a fixed frame period configuration for sidelink communications between at least the first UE and the second UE operating in a frame-based equipment mode, the fixed frame period configuration comprising an idle period configuration coordinated across at least the first UE and the second UE for initiating a channel access procedure; monitoring a sidelink channel during a first idle period according to the channel access procedure, the first idle period being identified based at least in part on the idle period configuration of the fixed frame period configuration; as well as A sidelink communication is sent to at least the second UE based at least in part on the channel access procedure indicating that the sidelink channel is available for sidelink communication.

30. The non-transitory computer-readable medium of claim 29, wherein the first UE and the second UE are in a first UE group, and wherein a same fixed frame period configuration is used at each UE in the first UE group.

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