CN119605119A

CN119605119A - Discovery reference signal window configuration for sidelink

Info

Publication number: CN119605119A
Application number: CN202380056404.XA
Authority: CN
Inventors: 刘智豪; 薛义生; J·孙; G·基希; 张晓霞; 骆涛; S·斯特凡纳托斯
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2022-08-11
Filing date: 2023-06-27
Publication date: 2025-03-11
Also published as: EP4569693A1; WO2024035998A1

Abstract

Methods, systems, and devices for wireless communications are described. The described technology provides a User Equipment (UE) that supports communicating synchronization information to other UEs via a side-link synchronization signal block (S-SSB) using a side-link channel. The UE may be configured with one or more Discovery Reference Signal (DRS) windows including a plurality of S-SSB reception occasions and a plurality of S-SSB transmission occasions. The UE may monitor for transmissions of the S-SSB during the reception occasion and transmit the S-SSB during the transmission occasion.

Description

Discovery reference signal window configuration for side links

Cross reference

This patent application claims priority from greek patent application 20220100680 entitled "discover reference signal window configuration for side link," filed by LIU et al at 2022, 8, 11, which is assigned to the assignee of the present application and expressly incorporated herein by reference.

Technical Field

The following relates to wireless communications, including discovery reference signal window configurations for side links.

Background

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be able to support communication with multiple users by sharing the 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, LTE-advanced (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 supporting wireless communications for communication devices, which may be referred to as User Equipment (UEs).

A wireless communication system may support communication between UEs, and such communication may be referred to as sidelink communication. In some cases, the first UE may relay control information and data from the network to the second UE using a side link channel. The second UE may be outside the coverage of the network and the side link communication technology may support communication between the second UE and the network.

Disclosure of Invention

The described technology relates to improved methods, systems, devices, and apparatus supporting discovery reference signal window configuration for side links. For example, the described techniques provide a User Equipment (UE) that supports communicating synchronization information to other UEs via a side link Synchronization Signal Block (SSB) using a side link channel. The UE may be configured with one or more Discovery Reference Signal (DRS) windows including a plurality of S-SSB reception occasions and a plurality of S-SSB transmission occasions. The UE may monitor for transmission of the S-SSB on a first side link channel during the reception occasion and transmit the S-SSB on a second side link channel during the transmission occasion. Thus, the configuration of the one or more DRS windows may support the use of side link channels to communicate the synchronization information to multiple UEs.

A method for wireless communication at a first User Equipment (UE) is described. The method may include receiving signaling indicating a configuration for one or more discovery reference signal windows, according to which the one or more discovery reference signal windows include two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions, monitoring reception of a first sidelink synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based on the configuration, and transmitting a second sidelink synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows based on the configuration.

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 executable by the processor to cause the apparatus to receive signaling indicating a configuration for one or more discovery reference signal windows, according to which the one or more discovery reference signal windows include two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions, monitor reception of a first side link synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based on the configuration, and transmit a second side link synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows based on the configuration.

Another apparatus for wireless communication at a first UE is described. The apparatus may include means for receiving signaling indicating a configuration for one or more discovery reference signal windows, the one or more discovery reference signal windows including two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions according to the configuration, means for monitoring reception of a first side link synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based on the configuration, and means for transmitting a second side link synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows based on the configuration.

A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions executable by a processor to receive signaling indicating a configuration for one or more discovery reference signal windows, according to which the one or more discovery reference signal windows include two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions, monitor reception of a first side link synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based on the configuration, and transmit a second side link synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows based on the configuration.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, receiving the signaling indicating the configuration may include operations, features, components, or instructions for receiving signaling indicating a receive discovery reference signal window including the two or more synchronization signal block reception occasions and a transmit discovery reference signal window including the two or more synchronization signal block transmission occasions.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the resources of the receive discovery reference signal window and the resources of the transmit discovery reference signal window may not overlap in the time domain.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the resources of the receive discovery reference signal window and the resources of the transmit discovery reference signal window may at least partially overlap in the time domain.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, at least one of the synchronization signal block reception occasions may be positioned between at least two of the synchronization signal block transmission occasions in the time domain.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the resources of the receive discovery reference signal window and the resources of the transmit discovery reference signal window may not overlap in the frequency domain.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, receiving the signaling indicating the configuration may include operations, features, components, or instructions for receiving signaling indicating a discovery reference signal window including the two or more synchronization signal block reception opportunities and the two or more synchronization signal block transmission opportunities.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, receiving the signaling indicating the configuration may include operations, features, components, or instructions to receive an indication of a first number of the two or more synchronization signal block transmission occasions, a second number of the two or more synchronization signal block reception occasions, or both the first number and the second number.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, receiving the signaling indicating the configuration may include operations, features, components, or instructions for receiving an indication of a spacing in the time domain between a first synchronization signal block occasion and a second synchronization signal block occasion of the one or more discovery reference signal windows.

In some examples of the methods, apparatus, and non-transitory computer readable media described herein, the indication of the spacing indicates a number of time slots.

In some examples of the methods, apparatus, and non-transitory computer readable media described herein, the indicated number of time slots may be 0.

Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions to perform a listen before talk procedure during the one or more discovery reference signal windows, wherein the first UE sends the second sidelink synchronization signal block message in response to clearing the listen before talk procedure.

Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, means, or instructions for receiving the first sidelink synchronization signal block message from the second UE based on the monitoring, wherein the first UE transmits the second sidelink synchronization signal block message during at least one synchronization signal block transmission occasion in response to receiving the first sidelink synchronization signal block message during at least one of the two or more synchronization signal block reception occasions.

Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, components, or instructions to determine that a synchronization accuracy of the first UE meets a synchronization accuracy threshold, wherein the first UE sends the second sidelink synchronization signal block message in response to determining that the synchronization accuracy of the first UE meets the synchronization accuracy threshold.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, each of the two or more synchronization signal block reception occasions and each of the two or more synchronization signal block transmission occasions corresponds to a respective time slot of the one or more discovery reference signal windows.

A method for wireless communication at a first UE is described. The method may include receiving signaling indicating a configuration for one or more discovery reference signal windows, each discovery reference signal window of the one or more discovery reference signal windows including a first synchronization signal block occasion for transmitting a first sidelink synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second sidelink synchronization signal block message by the first UE, and a set of additional synchronization signal block transmission occasions configured for use by any UE of a set of UEs including the first UE and the second UE, monitoring transmission of the first sidelink synchronization signal block message by the second UE during the first synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration, attempting to transmit the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration, wherein whether the first UE transmits the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows is configured for use by any UE of the set of UEs including the first UE and the second UE, and whether the second UE transmits the second sidelink synchronization signal block message during the first synchronization signal block transmission occasion is monitored during the first synchronization signal block.

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 executable by the processor to cause the apparatus to receive signaling indicating a configuration for one or more discovery reference signal windows, each discovery reference signal window of the one or more discovery reference signal windows including a first synchronization signal block occasion for transmitting a first sidelink synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second sidelink synchronization signal block message by the first UE, and a set of additional synchronization signal block transmission occasions for use by any UE of a set of UEs including the first UE and the second UE, monitor transmission of the first sidelink synchronization signal block message by the second UE during the first synchronization signal block of the one or more discovery reference signal windows based on the configuration, attempt to transmit the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration, wherein the first synchronization signal block is configured to be used by any UE in the set of UEs including the first UE and the second UE, monitor whether the second UE is transmitting the second sidelink synchronization signal block message during the first synchronization signal block occasion during the first synchronization signal block of the one or more discovery reference signal windows, and whether the additional synchronization signal block is transmitted by the second synchronization signal block during the first synchronization signal block occasion during the first synchronization signal block of the first UE.

Another apparatus for wireless communication at a first UE is described. The apparatus may include means for receiving signaling indicating a configuration for one or more discovery reference signal windows, each discovery reference signal window of the one or more discovery reference signal windows including a first synchronization signal block occasion for transmitting a first sidelink synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second sidelink synchronization signal block message by the first UE, and a set of additional synchronization signal block transmission occasions configured for use by any one of a set of UEs including the first UE and the second UE, means for monitoring transmission of the first sidelink synchronization signal block message by the second UE during the first synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration, means for attempting to transmit the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration, wherein whether the first UE transmits the second sidelink synchronization signal block message during the first sidelink synchronization signal block occasion is monitored by the first UE during the first synchronization signal block occasion and whether the additional synchronization signal block is received by the first UE during the first synchronization signal block transmission occasion of the first synchronization signal block.

A non-transitory computer-readable medium storing code for wireless communication at a first UE is described. The code may include instructions executable by a processor to receive signaling indicating a configuration for one or more discovery reference signal windows, each discovery reference signal window of the one or more discovery reference signal windows including a first synchronization signal block occasion for transmitting a first sidelink synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second sidelink synchronization signal block message by the first UE, and a set of additional synchronization signal block transmission occasions configured for use by any UE of a set of UEs including the first UE and the second UE, monitor transmission of the first sidelink synchronization signal block message by the second UE during the first synchronization signal block of the one or more discovery reference signal windows based on the configuration, attempt to transmit the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration, wherein the first synchronization signal block transmission occasion is based on whether the first synchronization signal block is used by any UE in the set of UEs including the first UE and the second UE, and whether the additional synchronization signal block transmission occasion is received by the second UE during the first synchronization signal block transmission occasion, wherein the first synchronization signal block is based on whether the first synchronization signal block is transmitted by the first sidelink synchronization signal block during the first synchronization signal block.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, attempting to transmit the second side link synchronization signal block message during the second synchronization signal block occasion includes performing a listen-before-talk procedure during the second synchronization signal block occasion, and the methods, apparatus, and non-transitory computer-readable media may further include operations, features, components, or instructions for transmitting the second side link synchronization signal block message during a synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based on the listen-before-talk procedure failing during the second synchronization signal block occasion.

Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for determining that the first side link synchronization signal block message is not present in the first synchronization signal block occasion based on the monitoring during the first synchronization signal block occasion, and monitoring transmission of the first side link synchronization signal block message by the second UE during a synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based on the absence of the first side link synchronization signal block message in the first synchronization signal block occasion.

Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, components, or instructions to determine that a synchronization accuracy of the first UE may be below a synchronization accuracy threshold, and monitor transmission of the first side link synchronization signal block message by the second UE during a synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based on determining that the synchronization accuracy of the first UE may be below the synchronization accuracy threshold.

Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for receiving a first side link synchronization signal block message during a first additional synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions and transmitting a second side link synchronization signal block message during a second additional synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based on receiving the first side link synchronization signal block message during the first additional synchronization signal block transmission occasion.

In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, each of the first synchronization signal block occasion, the second synchronization signal block occasion, and the additional synchronization signal block transmission occasion corresponds to a respective time slot of the one or more discovery reference signal windows.

Drawings

Fig. 1 illustrates an example of a wireless communication system supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure.

Fig. 2 illustrates an example of a wireless communication system supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure.

Fig. 3A and 3B illustrate examples of resource diagrams supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure.

Fig. 4 illustrates an example of a resource diagram supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure.

Fig. 5 illustrates an example of a process flow supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure.

Fig. 6 illustrates an example of a process flow supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure.

Fig. 7 and 8 illustrate block diagrams of devices supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure.

Fig. 9 illustrates a block diagram of a communication manager supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the disclosure.

Fig. 10 illustrates a diagram of a system including a device supporting discovery reference signal window configuration for a side link, in accordance with one or more aspects of the present disclosure.

Fig. 11-14 show flowcharts illustrating methods of supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure.

Detailed Description

A wireless communication system may support side link communications (e.g., internet of vehicles (V2X) communications) between User Equipment (UEs). In some examples, the UEs may share a side link synchronization block (S-SSB) to support synchronization of the UEs receiving the S-SSB with a network entity. Some of these S-SSB transmissions may be performed during a configured Discovery Reference Signal (DRS) window. For example, a UE within the coverage of a trusted synchronization source (e.g., the network entity) may receive synchronization information from the network entity. In order to benefit neighboring UEs that are not within the coverage of the network entity and thus do not receive the synchronization information, the UE may become an S-SSB transmitter (e.g., a first synchronization reference (syncRef) node) and transmit the S-SSBs containing the synchronization information from the network entity to the neighboring UEs.

One of the neighboring UEs (the second UE) may receive the S-SSBs from the first syncRef node and use the S-SSBs to synchronize with the network entity. In some examples, the second UE may determine to also send an S-SSB (to become the second syncRef node) to another neighboring UE (the third UE) based on some threshold and criteria (e.g., the distance between the two UEs). Thus, the synchronization information may remain propagated through the system. However, half-duplex limitations at the UEs (e.g., the second UE) may limit the ability of the UEs to efficiently receive and/or transmit S-SSBs without interfering with other communications. Additionally, due to Listen Before Talk (LBT) uncertainty in the system, the syncRef node can use additional opportunities to send these S-SSBs.

To support S-SSB transmission and reception in a wireless communication system that may include half-duplex UEs, the techniques described herein support configuration of one or more DRS windows that include multiple S-SSB transmission opportunities and multiple S-SSB receiver opportunities. In one example, two DRS window configurations may be defined, where a first DRS window includes multiple S-SSB receiver opportunities (e.g., resources) and a second DRS window includes multiple S-SSB transmission opportunities (e.g., resources). The two DRS windows may be contiguous, non-overlapping, or time-combined (e.g., interleaved). In another example, one DRS window may be configured so as to include S-SSB transmit opportunities and S-SSB transmit-receiver opportunities (e.g., in an interleaved mode). Thus, two DRS windows may be configured for a UE, one for receiving S-SSBs by the UE and the other for transmitting S-SBS by the UE.

In some cases, a configuration of a single DRS window may be used, where the single DRS window includes a first time slot for transmitting an S-SSB by a first syncRef node (e.g., an upstream node), a second time slot for transmitting an S-SSB by a second syncRef node (e.g., a downstream node), and a set of S-SSB opportunities (referred to as additional SSB transmit opportunities) available for S-SSB reception or S-SSB transmission. Additionally, the first syncRef node may be restricted from transmitting during the second time slot. Thus, a single DRS window may be configured in which different S-SSB occasions are assigned to different UEs as S-SSB transmission opportunities (influenced by the LBT of the assigned UEs, with one or other UEs monitoring to potentially receive S-SSBs), and may further include one or more additional S-SSB occasions with which any UE may transmit, depending on whether the UE is able to transmit earlier in the DRS window during its assigned S-SSB occasion. In some such cases, if the LBT fails in a legacy slot, the second syncRef node may not receive timing from the first syncRef node. To prevent possible timing problems, if it is determined that the timing/frequency accuracy is below a threshold, the second syncRef may monitor the S-SSB from the first syncRef node before starting S-SSB transmission, thus relinquishing transmission opportunities until the S-SSB transmission is more likely to be accurate.

Aspects of the present disclosure are first described in the context of a wireless communication system. Aspects of the present disclosure are further described with respect to a wireless communication system that illustrates side link communication and network synchronization, resource diagrams, and process flow diagrams. Aspects of the present disclosure are further illustrated and described with reference to apparatus diagrams, system diagrams, and flowcharts relating to discovery reference signal window configurations for side links.

Fig. 1 illustrates an example of a wireless communication system 100 supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure. 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, wireless communication system 100 may be a Long Term Evolution (LTE) network, an LTE-advanced (LTE-a) network, an LTE-a Pro network, a New Radio (NR) network, or a network that operates according to other systems and radio technologies, including future systems and radio technologies not explicitly mentioned herein.

The network entities 105 may be dispersed throughout a geographic region to form the wireless communication system 100 and may include devices in different forms or with different capabilities. In various examples, the network entity 105 may be referred to as a network element, mobility element, radio Access Network (RAN) node or network equipment, or the like. In some examples, the network entity 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. Coverage area 110 may be an example of a geographic area within which network entity 105 and UE 115 may support signal communications in accordance with one or more Radio Access Technologies (RATs).

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 UE 115 may be a device in a different form or with different capabilities. Some example UEs 115 are illustrated in fig. 1. The UEs 115 described herein may be capable of supporting communication with various types of devices, such as other UEs 115 or network entities 105 as shown in fig. 1.

As described herein, a node (which may be referred to as a network node or wireless node) of the wireless communication system 100 may be a network entity 105 (e.g., any of the network entities described herein), a UE 115 (e.g., any of the UEs 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 UE 115. As another example, the node may be a network entity 105. As another example, the first node may be configured to communicate with the 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 a UE 115, network entity 105, apparatus, device, or computing system, etc. may include disclosure of the UE 115, network entity 105, apparatus, device, or computing system, etc. as a node. For example, the disclosure of UE 115 being configured to receive information from network entity 105 also discloses that the first node is configured to receive information from the second node.

In some examples, the network entity 105 may communicate with the core network 130, or with each other, or both. For example, the network entity 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 directly (e.g., directly between the network entities 105) or indirectly (e.g., via the core network 130) via the backhaul communication link 120 (e.g., according to X2, xn, or other interface protocols). In some examples, network entities 105 may communicate with each other via a forward communication link 168 (e.g., according to a forward interface protocol) or a forward communication link 162 (e.g., according to a forward interface protocol), or any combination thereof. The backhaul communication link 120, the intermediate communication link 162, or the forward communication link 168 may be or include one or more wired links (e.g., electrical links, fiber optic links), one or more wireless links (e.g., radio links, wireless optical links), and the like, or various combinations thereof. UE 115 may communicate with core network 130 via communication link 155.

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 giganode 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 terminology). In some examples, the network entity 105 (e.g., base station 140) may be implemented in an aggregated (e.g., monolithic, free-standing) base station architecture that may be configured to utilize a protocol stack that is physically or logically integrated within a single network entity 105 (e.g., a single RAN node, such as base station 140).

In some examples, the network entity 105 may be implemented in an decentralized architecture (e.g., an decentralized base station architecture, an decentralized 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 an O-RAN alliance), or a virtualized RAN (vrna) (e.g., a cloud RAN (C-RAN)), for example, the network entity 105 may include one or more of 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), a non-real-time RIC (non-RT RIC)), a Service Management and Orchestration (SMO) 180 system, or any combination thereof, for example, 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 receiving point (RRU) or a receiving entity may be located in one or more virtual architectures, such as a plurality of virtual entities 105 may be located in one or more of the decentralized architectures, or may be implemented in one or more virtual entities 105, such as a distributed network architecture (e.g., virtual entities 105 Virtual RU (VRU)).

The split of functionality between the CUs 160, DUs 165, and RUs 170 is flexible and may support different functionalities, depending on which functions are performed at the CUs 160, DUs 165, or RUs 170 (e.g., network layer functions, protocol layer functions, baseband functions, RF functions, and any combination thereof). For example, a functional split of the protocol stack may be employed between the CU 160 and the DU 165 such that the CU 160 may support one or more layers of the protocol stack and the DU 165 may support one or more different layers of the 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)). 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 each is at least partially controlled by CU 160. Additionally or alternatively, a functional split of the protocol stack may be employed between the DU 165 and 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 may be within the protocol layer (e.g., some functions of the protocol layer may be performed by one of CU 160, DU 165, or RU 170 while other functions of the protocol layer are performed by a different one of CU 160, DU 165, or RU 170). CU 160 may be further functionally split into CU control plane (CU-CP) and CU user plane (CU-UP) functions. CU 160 may be connected to one or more DUs 165 via a neutral communication link 162 (e.g., F1-c, F1-u), and DUs 165 may be connected to one or more RUs 170 via a forward communication link 168 (e.g., an open Forward (FH) interface). In some examples, the intermediate communication link 162 or the forward communication link 168 may be implemented according to an interface (e.g., a channel) between layers of a protocol stack supported by respective network entities 105 communicating via such communication links.

In some wireless communication systems (e.g., wireless communication system 100), the infrastructure and spectrum resources for radio access may support wireless backhaul link capabilities to supplement the wired backhaul connection to provide 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 controlled in part by each other. One or more of the IAB nodes 104 may be referred to as a donor entity or IAB donor. The one or more DUs 165 or the one or more RUs 170 may be controlled in part by one or more CUs 160 associated with the 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 the DU 165 of the coupled IAB donor. The IAB-MT may include a separate set of antennas for relaying communications with the UE 115, or may share the same antenna (e.g., of RU 170) of the IAB node 104 (e.g., referred to as a virtual IAB-MT (vIAB-MT)) for access via the DU 165 of the IAB node 104. In some examples, the IAB node 104 may include a DU 165 supporting a communication link 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 split RAN architecture (e.g., one or more IAB nodes 104 or components of IAB nodes 104) may be configured to operate in accordance with the techniques described herein.

Where the techniques described herein are applied in the context of a split RAN architecture, one or more components of the split RAN architecture may be configured to support discovery reference signal window configuration for side links as described herein. For example, some operations described as being performed by UE 115 or network entity 105 (e.g., base station 140) may additionally or alternatively be performed by one or more components of an exploded RAN architecture (e.g., IAB node 104, DU 165, CU 160, RU 170, RIC 175, SMO 180).

UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device or subscriber device, or some other suitable terminology, where "device" may also be referred to as a unit, station, terminal or client, etc. The UE 115 may also include or be referred to as a personal electronic device, such as a cellular telephone, a Personal Digital Assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, the 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.

The UEs 115 described herein may be capable of communicating with various types of devices, such as other UEs 115 that 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, and so forth, as shown in fig. 1.

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 set of RF spectrum resources having a physical layer structure defined to support the communication link 125. For example, the carrier for communication link 125 may include a portion (e.g., a bandwidth portion (BWP)) of an RF spectrum band operating in accordance with one or more physical layer channels for a given radio access technology (e.g., LTE-A, LTE-a Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling to coordinate carrier operation, user data, or other signaling. The wireless communication system 100 may support communication with UEs 115 using carrier aggregation or multi-carrier operation. According to a carrier aggregation configuration, the UE 115 may be configured with a plurality of 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 portion (e.g., entity, sub-entity) of the network entity 105. For example, the terms "transmit," "receive," or "communication," when referring to a network entity 105, may refer to any portion of the network entity 105 (e.g., base station 140, CU 160, DU 165, RU 170) of the RAN that communicates with another device (e.g., directly or via one or more other network entities 105).

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

The signal waveform transmitted via the carrier may include a plurality of subcarriers (e.g., using a multi-carrier modulation (MCM) technique, such as Orthogonal Frequency Division Multiplexing (OFDM) or discrete fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may refer to a symbol period (e.g., duration of one modulation symbol) and a resource of one subcarrier, in which case the symbol period and 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) such that a relatively higher number of resource elements (e.g., in the transmit duration) and a relatively higher order modulation scheme may correspond to relatively higher rate communications. Wireless communication resources may refer to a combination of RF spectrum resources, time resources, and spatial resources (e.g., spatial layers, beams), and the use of multiple spatial resources may increase the data rate or data integrity for communication with UE 115.

The time interval for the network entity 105 or UE 115 may be expressed in multiples of a basic time unit, which may refer to a sampling period of T _s＝1/(Δf_max·N_f seconds, for example, where Δf _max may represent a supported subcarrier spacing and N _f may represent a supported Discrete Fourier Transform (DFT) size. The time intervals of the communication resources may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms)). Each radio frame may be identified by a System Frame Number (SFN) (e.g., ranging from 0 to 1023).

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

A subframe, slot, minislot, 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 the TTI) may be variable. Additionally or alternatively, a minimum scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in bursts of shortened TTIs (sTTI)).

According to various techniques, physical channels may be multiplexed for communication using carriers. For example, the physical control channels and physical data channels may be multiplexed using one or more of Time Division Multiplexing (TDM), frequency Division Multiplexing (FDM), or hybrid TDM-FDM techniques to signal via downlink carriers. The control region (e.g., control resource set (CORESET)) of the physical control channel may be defined by a set of symbol periods and may extend across the system bandwidth of the carrier or a subset of the system bandwidth. One or more control regions (e.g., CORESET) may be configured for the set of UEs 115. For example, one or more of UEs 115 may monitor or search the control region for control information based on one or more sets of search spaces, and each set of search spaces may include one or more control channel candidates in one or more aggregation levels arranged in a cascaded manner. The aggregation level of control channel candidates may refer to the number of control channel resources (e.g., control Channel Elements (CCEs)) associated with coding information for a control information format having a given payload size. The set of search spaces may include a common set of search spaces configured for transmitting control information to a plurality of UEs 115 and a UE-specific set of search spaces for transmitting control information to a specific UE 115.

The network entity 105 may provide communication coverage via one or more cells (e.g., macro cells, small cells, hot spots, or other types of cells, or any combination thereof). The term "cell" may refer to a logical communication entity for communicating with the network entity 105 (e.g., using a carrier) and may be associated with an identifier (e.g., a Physical Cell Identifier (PCID), a Virtual Cell Identifier (VCID), or other cell identifier) for distinguishing between neighboring cells. In some examples, a cell may also refer to a coverage area 110 or a portion (e.g., a sector) of coverage area 110 over which a logical communication entity operates. Such cells may range from smaller areas (e.g., structures, subsets of structures) to larger areas, depending on various factors such as the capabilities of the network entity 105. For example, a cell may be or include a building, a subset of buildings, or an outside space between or overlapping coverage areas 110, etc.

The macro cell typically covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs 115 with service subscription with the network provider supporting the macro cell. The small cell may be associated with a lower power network entity 105 (e.g., lower power base station 140) than the macro cell, and the small cell may operate using the same or a different (e.g., licensed, unlicensed) frequency band as the macro cell. The small cell may provide unrestricted access to UEs 115 with service subscription with the network provider or may provide restricted access to UEs 115 associated with the small cell, e.g., UEs 115 in a Closed Subscriber Group (CSG), UEs 115 associated with users in a home or office. The network entity 105 may support one or more cells and may also use one or more component carriers to support communications via the one or more cells.

In some examples, a carrier may support multiple cells and different cells may be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB)) that may provide access for different types of devices.

In some examples, the network entity 105 (e.g., base station 140, RU 170) may be mobile and, thus, provide communication coverage to the mobile coverage area 110. In some examples, different coverage areas 110 associated with different technologies may overlap, but 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 use the same or different radio access technologies to provide coverage for respective coverage areas 110.

The wireless communication system 100 may support synchronous operation or asynchronous operation. For synchronous operation, the network entities 105 (e.g., base stations 140) may have similar frame timing, and transmissions from different network entities 105 may be approximately aligned in time. For asynchronous operation, the network entities 105 may have different frame timings, and in some examples, transmissions from different network entities 105 may be out of time alignment. The techniques described herein may be used for synchronous or asynchronous operation.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices and may allow for automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication techniques that allow devices to communicate with each other or network entity 105 (e.g., base station 140) without human intervention. In some examples, M2M communications or MTC may include communications from devices integrating sensors or meters to measure or capture information and relay such information to a central server or application that uses or presents the information to a person interacting with the application. Some UEs 115 may be designed to collect information or to enable automatic behavior of a machine or other device. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, health care monitoring, field survival monitoring, weather and geographic event monitoring, formation management and tracking, remote security sensing, physical access control, and transaction-based business charging.

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 communications (URLLC). The UE 115 may be designed to support ultra-reliable, low latency, or critical functions. Ultra-reliable communications may include private communications or group communications, 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 prioritizing services, and such services may be used for public safety or general business applications. The terms "ultra-reliable," "low latency," and "ultra-reliable low latency" are used interchangeably herein.

In some examples, UEs 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 peer-to-peer (P2P), D2D, or side link protocols). In some examples, one or more UEs 115 in a group that are performing D2D communications may be within coverage area 110 of a network entity 105 (e.g., base station 140, RU 170) that may support aspects of such D2D communications configured (e.g., scheduled) by network entity 105. In some examples, one or more UEs 115 in such a group may be outside of the coverage area 110 of the network entity 105 or otherwise unavailable or not configured to receive transmissions from the network entity 105. In some examples, groups 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, the network entity 105 may facilitate scheduling of resources for D2D communications. In some other examples, D2D communication may be performed between UEs 115 without involving network entity 105.

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

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 (5 GC), which may include at least one control plane entity (e.g., mobility Management Entity (MME), access and mobility management function (AMF)) that manages access and mobility and at least one user plane entity (e.g., serving gateway (S-GW), packet Data Network (PDN) gateway (P-GW), or User Plane Function (UPF)) that routes packets or interconnects to an external network. The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for UEs 115 served by a network entity 105 (e.g., base station 140) associated with the core network 130. The user IP packets may be communicated through a user plane entity, which may provide IP address assignment, as well as other functions. The user plane entity may be connected to IP services 150 of one or more network operators. IP services 150 may include access to the internet, intranets, IP Multimedia Subsystem (IMS), or packet switched streaming services.

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, the region from 300MHz to 3GHz is referred to as the Ultra High Frequency (UHF) region or decimeter range because the wavelength range is about one decimeter to one meter in length. UHF waves may be blocked or redirected by building and environmental features (which may be referred to as clusters), but these waves may be sufficiently penetrating the structure for the macro cell to serve 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 smaller frequencies and longer waves in the High Frequency (HF) or Very High Frequency (VHF) portions of the spectrum below 300 MHz.

The wireless communication system 100 may utilize licensed and unlicensed RF spectrum bands. For example, the wireless communication system 100 may employ Licensed Assisted Access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology that uses unlicensed frequency bands, such as the 5GHz industrial, scientific, and medical (ISM) frequency bands. Devices such as network entity 105 and UE 115 may employ carrier sensing for collision detection and avoidance when operating with unlicensed RF spectrum bands. In some examples, operation using an unlicensed frequency band may be based on a carrier aggregation configuration in combination with component carriers operating using a licensed frequency band (e.g., LAA). Operations using unlicensed spectrum may include downlink transmission, uplink transmission, P2P transmission, or D2D transmission, among others.

The network entity 105 (e.g., base station 140, RU 170) or UE 115 may be equipped with multiple antennas that may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication, or beamforming. The antennas of network entity 105 or UE 115 may be located within one or more antenna arrays or antenna panels that may support MIMO operation 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 a antenna tower). In some examples, antennas or antenna arrays associated with network entity 105 may be located at different geographic locations. The network entity 105 may include an antenna array having a set of multiple rows and columns of antenna ports that the network entity 105 may use to support beamforming for communication with the UE 115. Also, 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 transmitted via the antenna port.

The network entity 105 or UE 115 may utilize multipath signal propagation and improve spectral efficiency by transmitting or receiving multiple signals via different spatial layers using MIMO communication. Such techniques may be referred to as spatial multiplexing. The plurality of signals may be transmitted, for example, by the sender device via different antennas or different combinations of antennas. Similarly, the plurality of signals may be received by the recipient device via different antennas or different combinations of antennas. Each of the plurality of signals may be referred to as a separate spatial stream and may carry information associated with the same data stream (e.g., the same codeword) or a different data stream (e.g., a different codeword). Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) in which multiple spatial layers are transmitted to the same receiver device, and multi-user MIMO (MU-MIMO) in which multiple spatial layers are transmitted to multiple devices.

Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that may be used at a sender device or a receiver device (e.g., network entity 105, UE 115) to shape or steer antenna beams (e.g., transmit beams, receive beams) along a spatial path between the sender device and the receiver device. Beamforming may be achieved by combining signals communicated via antenna elements of an antenna array such that some signals propagating along a particular orientation relative to the antenna array experience constructive interference while other signals experience destructive interference. The adjustment of the signal communicated via the antenna element may include the sender device or the receiver device applying an amplitude offset, a phase offset, or both to the signal carried via the antenna element associated with the device. The adjustment associated with each of these antenna elements may be defined by a set of beamforming weights associated with a particular orientation (e.g., with respect to an antenna array of the sender device or the receiver device or with respect to some other orientation).

The network entity 105 or UE 115 may use beam sweep techniques as part of the beamforming operation. For example, the network entity 105 (e.g., base station 140, RU 170) may use multiple antennas or antenna arrays (e.g., antenna panels) for beamforming operations for directional communication with the UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times by the network entity 105 in different directions. For example, the network entity 105 may transmit signals according to different sets of beamforming weights associated with different transmit directions. The beam directions may be identified (e.g., by a sender device (such as network entity 105) or by a receiver device (such as UE 115)) using transmissions in different beam directions for later transmission or reception by network entity 105.

Some signals, such as data signals associated with a particular receiver device, may be transmitted by a sender device (e.g., sender network entity 105, sender UE 115) in a single beam direction (e.g., a direction associated with a receiver device (such as receiver network entity 105 or receiver UE 115)). In some examples, the beam direction associated with transmission in a single beam direction may be determined based on signals transmitted in one or more beam directions. For example, the UE 115 may receive one or more of the signals transmitted by the network entity 105 in different directions and may report an indication to the network entity 105 of the signal received by the UE 115 with the highest signal quality or other acceptable signal quality.

In some examples, the transmission by the device (e.g., by the network entity 105 or UE 115) may be performed using multiple beam directions, and the device may use a combination of digital precoding or beamforming to generate a combined beam for transmission (e.g., from the network entity 105 to the UE 115). UE 115 may report feedback indicating precoding weights for one or more beam directions and the feedback may correspond to a set of beams across a system bandwidth or configuration of one or more sub-bands. The network entity 105 may transmit reference signals (e.g., cell-specific reference signals (CRSs), channel state information reference signals (CSI-RS)), which may or may not be pre-coded. The UE 115 may provide feedback for beam selection, which may be a Precoding Matrix Indicator (PMI) or codebook-based feedback (e.g., a multi-panel codebook, a linear combined codebook, a port-selective codebook). Although these techniques are described with reference to signals transmitted in one or more directions by network entity 105 (e.g., base station 140, RU 170), UE 115 may use similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by UE 115), or for transmitting signals in a single direction (e.g., for transmitting data to a recipient device).

The receiving device (e.g., UE 115) may perform the receiving operation according to a plurality of receiving configurations (e.g., directed listening) upon receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from the receiving device (e.g., network entity 105). For example, the receiving device may perform reception according to multiple reception directions by receiving via different antenna sub-arrays, processing the received signals according to different antenna sub-arrays, receiving according to different sets of reception beamforming weights (e.g., different sets of directional listening weights) applied to signals received at multiple antenna elements of the antenna array, or processing the received signals according to different sets of reception beamforming weights applied to signals received at multiple antenna elements of the antenna array, any of which may be referred to as "listening" according to different reception configurations or reception directions. In some examples, the recipient device may use a single receive configuration to receive in a single beam direction (e.g., when receiving the data signal). The single receive configuration may be aligned along a beam direction determined based on listening according to different receive configuration directions (e.g., a beam direction determined to have the highest signal strength, highest signal-to-noise ratio (SNR), or other acceptable signal quality based on listening according to multiple beam directions).

In some examples of the wireless communication system 100, one or more UEs 115 may share S-SSBs to support synchronization of UEs 115 receiving these S-SSBs with the network entity 105. The transmission of these S-SBS may be performed during a configured DRS window. For example, a first UE 115 within coverage of a trusted synchronization source (e.g., network entity 105) may receive synchronization information (e.g., SSB) from network entity 105. To benefit neighboring UEs 115 that are not within the coverage of the network entity 115 (e.g., the UE 115 does not receive the synchronization information), the first UE 115 may become an S-SSB transmitter (e.g., the first syncRef node) and send the S-SSBs containing the synchronization information from the network entity to other UEs 105.

The second UE 115, which may not be within the coverage of the network entity, may receive the S-SSBs from the first syncRef node and use the S-SSBs to synchronize with the network entity. In some examples, the second UE 115 may determine to also send an S-SSB to the third UE 115 (becoming the second syncRef node). Thus, the synchronization information may remain propagated through the system. However, UE 115 may have half-duplex limitations that inhibit efficient S-SSB transmission and reception. Additionally, the syncRef node may use additional opportunities to send these S-SSBs due to LBT uncertainty in the system.

To support S-SSB transmission and reception in the wireless communication system 100, which may include a half-duplex UE 115, the techniques described herein support configuration of one or more DRS windows that include multiple S-SSB transmission opportunities and multiple S-SSB reception opportunities. In one example, two DRS windows may be configured such that a first DRS window includes the plurality of S-SSB receiver opportunities (resources) and a second DRS window includes the plurality of S-SSB transmission opportunities. The two DRS windows may be contiguous, non-overlapping, or time-combined (e.g., interleaved). In another example, one DRS window may be configured to include an S-SSB transmit opportunity and an S-SSB transmit receive opportunity (e.g., in an interleaved mode).

The techniques described herein also support configurations for a single DRS window that includes an S-SSB transmit opportunity, an S-SSB receive opportunity, and an additional set of S-SSB opportunities available for transmission or reception. In some cases, to prevent timing problems, the S-SSB receiving UE 115 (e.g., the second syncRef node) may monitor the S-SSB from the first syncRef node before starting the S-SSB transmission, thus relinquishing the transmission opportunity until the S-SSB transmission may be accurate.

Fig. 2 illustrates an example of a wireless communication system 200 supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the disclosure. In some examples, wireless communication system 200 may implement aspects of wireless communication system 100 or may be implemented by aspects of wireless communication system 100. For example, wireless communication system 200 may include UE 115-a and network entity 105-a (which may be examples of corresponding devices as described herein).

In some implementations of the wireless communication system 200, the network entity 105-a may have a coverage area 205, which may be an example of the coverage area 110 as described with respect to fig. 1. The UE 115-a may reside within the coverage area 205 and the network entity 105-a may communicate with the UE 115-a and share information via a communication link 125-a (e.g., an access link). In some examples, the network entity 105-a may send synchronization information (e.g., in an SSB message) to the UE 115-a via the communication link 125-a.

In some cases, UE 115-a may determine that neighbor UE 115 is not receiving synchronization information and determine to send S-SSBs to neighbor UEs 115 (e.g., UE 115-b and UE 115-c). For example, the UE 115-a may directly access timing and synchronization information from the network entity 105-a (e.g., synchronization source) and thus may be considered a first syncRef node (node that directly accesses timing/synchronization information). In such examples, UE 115-a may determine to become an S-SSB transmitter (e.g., first syncRef node) and transmit an S-SSB to support a neighboring UE (e.g., UE 115-b). In this way, synchronization information may be propagated through the wireless communication system 200.

According to some configurations, the number of S-SSB instances within one S-SSB period may be limited. In frequency 1 (FR 1), the number of S-SSB instances or slots may be 1 (e.g., k=1) when the subcarrier spacing is 15 kHz. In FR1 with a 30kHz subcarrier spacing, the number of S-SSB instances or slots is 1 or 2 (e.g., k=1, or k=2). However, since the UE 115 is to perform and clear the LBT procedure (e.g., LBT uncertainty) before transmitting the S-SSB, the S-SSB transmitting node may be configured with more opportunities to transmit the S-SSB. Thus, as illustrated in fig. 2, the UE 115 may be configured with a DRS window 215 starting at an S-SSB instance that supports adding S-SSB candidate locations for each S-SSB instance. A DRS window (e.g., DRS window 215) may be defined starting from the S-SSB instance, and the node may be configured to transmit the S-SSB during up to K S-SSB slots within the L candidate locations after the LBT is cleared. For example, the node transmits during up to K S-SSB slots within L S-SSB candidate locations 220 after clearing the LBT (e.g., K=4 in L=10 candidate locations, or K=8 in L=20 candidate locations).

According to the configuration of the DRS window 215, an S-SSB transmission 225 may be attempted at a first S-SSB candidate location 220 that is a nominal S-SSB candidate location 220. However, LBT may fail at the nominal S-SSB candidate location 220, which may prevent transmission of S-SSB. Thus, the configuration of multiple S-SSB candidate locations 220 may support multiple attempts at S-SSB transmission 225. The UE 115-a may attempt LBT during the S-SSB candidate position 220 of the DRS window 215 and transmit the S-SSB based on the clear LBT. By introducing multiple S-SSB candidate locations 220 around each S-SSB instance (e.g., DRS windows from each S-SSB instance), LBT uncertainty in the system can be resolved by supporting multiple locations for performing LBT procedures and multiple locations for S-SSB transmissions. In the event that LBT is successful, the downstream node (e.g., UE 115-b) may rely on the first syncRef node (e.g., UE 115-a) as a timing reference for synchronization with the network entity 105-a.

In some examples of the disclosure, the UE 115-b may determine that the UE 115-c does not have timing information sent from the first syncRef node (e.g., UE 115-a). For example, the UE 115-b may detect that a third UE (e.g., UE 115-c) is a threshold distance from the UE 115-b and the UE 115-a such that the UE 115-c is not in the coverage area 205 of the network entity 105-a. The threshold distance may be such that the UE 115-c may not have a communication link with a trusted synchronization source (e.g., network entity 105-a) and may not have a distance to a communication link of the first syncRef node (e.g., UE 115-a) that may be used by the UE 115-b as a timing reference. To prevent timing and synchronization issues, the second UE 115-b may attempt to become an S-SSB transmitter (e.g., a second syncRef node) based on a threshold or criteria, such as a distance threshold or a Reference Signal Received Power (RSRP) threshold. However, UE 115-b may be limited by half-duplex constraints, and thus cannot monitor for S-SSB messages from the first syncRef node and send S-SSB messages to UE 115-c in the same set of resources.

Due to the half-duplex nature of nodes (e.g., UEs 115) in the system, at least two orthogonal S-SSB timing configurations may be defined. For example, one timing allocation (e.g., first sl-SSB-TimeAllocation) is defined for receiving S-SSBs from a selected syncRef node (e.g., first syncRef node or UE 115-a), and a second timing allocation (e.g., second sl-SSB-TimeAllocation) is defined for transmitting S-SSBs. Each timing allocation (e.g., sl-SSB-TimeAllocation) may specify a slot offset (e.g., sl-TimeOffsetSSB) from a period (e.g., a period of 160 ms), a slot interval (e.g., sl-time interval) between S-SSBs in the period (e.g., a period between S-SSB candidate locations 220), and a number of S-SSB transmit instances within a period (e.g., sl-NumSSB-WithinPeriod). However, such a configuration may lead to LBT uncertainty because there is one S-SSB candidate location for S-SSB transmissions of a particular node.

As described herein, to limit or reduce LBT uncertainty, multiple S-SSB candidate slots are introduced around each candidate instance. Further, to address half duplex operation of the syncRef node, the techniques described herein support configurations for multiple S-SSB transmit opportunities and multiple S-SSB receive opportunities in one or more DRS windows (such as DRS window 215). Further, as described herein, the one or more DRS windows may be configured as non-overlapping or overlapping windows (with interleaving resources). These various configurations may support reduced resource overhead and/or reduced UE complexity. These DRS window configurations are described in further detail with respect to fig. 3A, 3B, and 4.

Fig. 3A illustrates an example of resource diagrams 300 and 301 supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure. In some examples, resource diagrams 300 and 301 may be implemented by aspects of wireless communication systems 100 and 200. For example, resource diagrams 300 and 301 may be implemented by UE 115 and network entity 105 (which may be examples of corresponding devices as described herein).

Aspects of the present disclosure may support various configurations of one or more DRS windows in a network. In some examples, at least two DRS windows may allow allocation of two sets of S-SSB time resources (e.g., one set for S-SSB transmissions and one set for S-SSB candidate monitoring). The set of S-SSB occasions for monitoring S-SSB transmissions from the syncRef node (e.g., S-SSB transmitter) may be associated with a receiving DRS window (e.g., receiving DRS window 310 or receiving DRS window 330), and the set of S-SSB occasions for S-SSB transmissions having multiple candidate locations may be associated with a transmitting DRS window (e.g., transmitting DRS window 315 and transmitting DRS window 335). In some examples, the configuration of a DRS window (e.g., a receive DRS window or a transmit DRS window) may include a number of S-SSB occasions and a slot interval between S-SSB occasions. In a defined timing allocation configuration (e.g., sl-SSB-TimeAllocation), S-SSB candidate slots (e.g., opportunities) may be defined to include and follow S-SSB instances. In some cases, if it is determined that the S-SSB candidate slots should be consecutive, a slot interval between the S-SSB candidate slots may be set to 0.

In accordance with aspects of the present disclosure, resource diagram 300 illustrates a DRS configuration that includes two DRS windows, where the receiving DRS window 310 and the transmitting DRS window 315 do not overlap. For example, the S-SSB candidate slot interval for both the receive DRS window 310 and the transmit DRS window 315 may be set to 0 to allow the S-SSB candidate slots to be contiguous. In some examples, the slot interval may be set to 0 to shorten the length of the DRS window (e.g., the receive DRS window 310 and/or the transmit DRS window 315). Thus, the receiver may not monitor the S-SSB candidates for an extended amount of time and may minimize transmit and receive switching. It should be appreciated that SSB opportunities to receive DRS window 310 and transmit one or more of DRS window 315 may be discontinuous (e.g., positioned in an intermediate slot interval).

As illustrated by resource diagram 300, the transmit DRS window 315 can begin after the receive DRS window 310 is completed. In this way, the UE may wait until the UE has received at least a portion of the S-SSB message in the receive DRS window 310 before sending the S-SSB message in the send DRS window 315.

The receive DRS window 310 includes a plurality of S-SSB receive opportunities 320 for receiving S-SSB messages. In the presence of LBT uncertainty at the sender node, the configuration of multiple reception occasions may support more opportunities for receiving S-SSB messages. Additionally, the transmit DRS window 315 may include a plurality of S-SSB transmit opportunities 325 for transmitting S-SSB messages. In the presence of LBT uncertainty, including multiple S-SSB transmission opportunities may support more opportunities for clearing LBT and transmitting S-SSB messages. In some cases, the configuration of the transmit DRS window 315 may support the transmission of S-SSB bursts in a set of S-SSB transmit occasions (e.g., multiple occasions).

The resource diagram 300 may be used with a small number of S-SSB reception occasions 320 and S-SSB transmission occasions 325. Since the transmit DRS window 315 may wait until the receive DRS window 310 is complete, a large number of S-SSB receive opportunities 320 and S-SSB transmit opportunities 325 may cause a large delay in the system. Thus, the resource diagram 300 provides support for basic reception and transmission between two UEs 115 with a small number of S-SSB candidate locations. Further, resource diagram 300 may support reduced UE complexity because the UE may not continuously or periodically switch between S-SSB transmit occasions and S-SSB receive occasions.

Resource diagram 301 illustrates a DRS window configuration with two time-combined DRS windows (e.g., interlace mode). The DRS configuration may include a receiving DRS window 330 with a plurality of S-SSB receive opportunities 340 and a transmitting DRS window 335 with a plurality of S-SSB transmit opportunities 345. As illustrated, the S-SSB transmit opportunity 345 of the transmit DRS window 335 may not overlap with the S-SSB receive opportunity 340 of the receive DRS window 330.

The transmit DRS window 335 of the resource diagram 301 can begin during the receive DRS window 330. In such implementations, the slot interval 350 (e.g., the spacing in the time domain) may be set to be greater than 0. In some cases, the slot interval 350 may be set equal to the length of one S-SSB reception occasion 340 or S-SSB transmission occasion 345. For example, during the period of the candidate slot interval 350, the syncRef node can switch between receiving the DRS window 330 and transmitting the DRS window 335. Thus, the syncRef node may not wait until all of the S-SSB reception opportunities 340 from syncRef UE are monitored before starting to transmit the DRS window 335.

Resource diagram 301 may be implemented with a large number of S-SSB receive occasions 340 and S-SSB transmit occasions 345. Enabling the syncRef node to switch between receiving the DRS window 330 and transmitting the DRS window 335, thereby supporting the syncRef node to transmit the S-SSB message after receiving the S-SSB message. However, according to resource diagram 301, the syncref node may switch back and forth between a receiving DRS window 330 for monitoring S-SSB messages and a transmitting DRS window 335 for transmitting received S-SSB messages, which may result in increased UE complexity. In some examples, the LBT procedure may fail at an S-SSB transmission occasion 345 in the transmission DRS window 335 and may wait until the next reception DRS window slot (e.g., the opportunity in the reception DRS window 330) to attempt to transmit at another S-SSB transmission occasion 345, which may result in a delay in the communication of synchronization information.

As illustrated in fig. 3A, the receive DRS window 310 and the transmit DRS of the resource diagram 300 and the receive DRS window 330 and the transmit DRS window 335 of the resource diagram 301 may be located in different frequency resources. In some examples, the different frequency resources are orthogonal. It should be appreciated that the respective receiving and transmitting DRS windows may be located in the same or overlapping frequency resources. Further, the S-SSB transmission occasion and the S-SSB reception occasion of fig. 3A may correspond to a time slot (e.g., the S-SSB reception occasion 320 is a respective time slot), or may be positioned in portions of the respective time slot. It should be appreciated that the S-SSB transmit opportunity and the S-SSB receive opportunity may correspond to other types of transmit time intervals.

However, the configuration illustrated in resource diagrams 300 and 301 may result in a large overhead in the network. In some cases, multiple S-SSB candidate slots in each DRS window may be excluded from the data resource pool. Thus, the configuration of multiple orthogonal DRS windows may cause the S-SSB candidate overhead to increase accordingly with the number of DRS windows. For example, for S-SSB candidate slots within one DRS window, the syncRef node may transmit up to K S-SSB slots (e.g., K may be equal to 1) at the earliest slot (e.g., S-SSB candidate opportunity) of the clear LBT procedure. In some cases, if the LBT is cleared in advance, the resources of the remaining S-SSB transmission opportunities may not be used.

Fig. 3B illustrates an example of a resource diagram 302 supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the disclosure. In some examples, resource diagram 300 may be implemented by aspects of wireless communication systems 100 and 200. For example, resource diagram 302 may be implemented by UE 115 and network entity 105 (which may be examples of corresponding devices as described herein).

In some examples, one DRS window 355 may be configured, and even and odd index slots (e.g., opportunities) within the DRS window 355 may be associated with two orthogonal S-SSB resources for reception and transmission, respectively. For example, a single DRS window 355 may be a DRS window (e.g., a receive/transmit DRS window) for both the reception and transmission of S-SSB messages. The DRS window 355 may include a plurality of S-SSB reception occasions (e.g., S-SSB reception occasion 360) and a plurality of S-SSB transmission occasions (e.g., S-SSB transmission occasion 365). In some examples, the syncRef node may monitor for S-SSB messages in even-indexed slots (e.g., S-SSB reception opportunities). Thus, in odd indexed slots (e.g., S-SSB transmit occasions), the syncRef node may attempt to clear the LBT procedure and transmit an S-SSB message.

In some cases, the syncRef node may wait until an S-SSB message is received and/or until the timing or frequency accuracy (e.g., synchronization accuracy threshold) is above a threshold (e.g., synchronization accuracy threshold), and not send the S-SSB message in the DRS window 355. Thus, in one example, if the UE does not receive the S-SSB during the S-SSB reception opportunity 360, the UE may not use the S-SSB transmission opportunity 365 to perform the LBT procedure and/or transmit the S-SSB. Thereafter, if the UE receives the S-SSB during a subsequent S-SSB reception occasion, the UE may perform LBT and/or transmit the S-SSB during an S-SSB transmission occasion subsequent to the S-SSB reception occasion in which the S-SSB is received. The S-SSB transmission occasion and the S-SSB transmission occasion of fig. 3B may be located in the same or overlapping frequency resources, or in different and/or orthogonal frequency resources. As described with respect to fig. 3A, the S-SSB transmit occasion and the S-SSB receive occasion of fig. 3B may correspond to a time slot (e.g., S-SSB receive occasion 360 is a time slot), or may be positioned in portions of a time slot. It should be appreciated that the S-SSB transmit opportunity and the S-SSB receive opportunity may correspond to other types of transmit time intervals.

Fig. 4 illustrates an example of a resource diagram 400 supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the disclosure. In some examples, resource diagram 400 may be implemented by aspects of wireless communication systems 100 and 200. For example, resource diagram 400 may be implemented by UE 115 and network entity 105 (which may be examples of corresponding devices as described herein).

Some implementations may have a single DRS window configuration (e.g., receive/transmit DRS window 405) for both receiving and transmitting in accordance with the present disclosure. In some examples, the receive/transmit DRS window 405 can include a first S-SSB occasion 410, a second S-SSB occasion 415, and an additional S-SSB set of transmit occasions 420. In some cases, an additional set of S-SSB transmit opportunities 420 is included to provide additional LBT and S-SSB transmit or receiver opportunities for receiving/transmitting the DRS window 405. For example, additional S-SSB transmit sets of occasions 420 may be dynamically used (e.g., the occasions may be used for S-SSB reception or transmission). In some cases, the first S-SSB occasion 410 may be reserved as a send S-SSB occasion to send S-SSB messages from syncRef nodes (e.g., the first syncRef node that relies on timing and/or synchronization information via the S-SSB messages) to the second syncRef node. A second S-SSB occasion may be reserved for sending S-SSB messages from the second syncRef node to the neighboring UE 115. In some implementations, the first syncRef node will not transmit during the second S-SSB occasion and will wait until after the second S-SSB occasion to attempt to transmit again (e.g., perform another LBT procedure). Thus, the second syncRef node may not be allowed to transmit during the first S-SSB occasion. Both the first syncRef node and the second syncRef node may transmit during the occasions of the additional S-SSB transmit occasion set 420 according to various conditions, circumstances, or implementations.

In some other implementations, the resource diagram 400 includes both a receive DRS window and a transmit DRS window. Thus, the additional S-SSB transmit opportunity set 420 may overlap between the receive DRS window and the transmit DRS window. The first S-SSB occasion 410 may be in a receive DRS window and is for receiving an S-SSB message from the first syncRef node, and the second S-SSB occasion 415 may be in a transmit DRS window and is for transmitting an S-SSB message by the second syncRef node.

In some examples, both the first syncRef node and the second syncRef node may transmit S-SSB messages in the additional S-SSB transmit opportunity set 420. However, half-duplex limitations may lead to synchronization problems at the UE. For example, the first syncRef node and the second syncRef node may transmit during the same S-SSB occasion in the additional S-SSB transmit occasion set 420. Thus, the second syncRef node may not receive timing and synchronization information (via S-SSB messages) from the first syncRef node due to overlapping transmission and half-duplex limitations.

Thus, in view of half-duplex limitations, the second syncRef node may determine that the synchronization accuracy (e.g., timing and/or frequency accuracy) is below a certain threshold (e.g., synchronization accuracy threshold), and thus synchronize with the first syncRef node based on the received S-SSB. The second syncRef node can monitor for S-SSB messages from the first syncRef node and the second syncRef node does not begin S-SSB transmission (after clearing LBT) until S-SSB messages are received and detected in the receive/transmit DRS window 405. Thus, the second syncRef node may relinquish any possible transmission opportunity in the receive/transmit DRS window 405 until an S-SSB message is received, thereby improving synchronization accuracy in the wireless communication system.

In some examples, the second syncRef node may not receive the S-SSB message from the first syncRef node until the first S-SSB occasion 425 in the set of additional S-SSB transmit occasions 420. For example, due to LBT failure, an S-SSB message may not be sent from the first syncRef node to the second syncRef node during the first S-SSB occasion 410. Thus, the second syncRef node may relinquish the transmission opportunity during the second S-SSB opportunity 415 and wait until an S-SSB transmission opportunity in the additional S-SSB transmission opportunity set 420. The second syncRef node may receive the S-SSB message from the first syncRef node during the first S-SSB occasion 425 in the set of additional S-SSB transmit occasions 420 in the receive/transmit DRS window 405. During a second S-SSB occasion 430 in the set of additional S-SSB transmit occasions 420, the second syncRef node may transmit an S-SSB message (e.g., based on the clear LBT). Thus, the second syncRef node may use the additional set of S-SSB transmit occasions 420 to ensure that the second syncRef node receives S-SSB messages from the first syncRef node in order to support improved synchronization accuracy in the wireless communication system.

Fig. 5 illustrates an example of a process flow 500 supporting discovery reference window configuration for a side link in accordance with various aspects of the disclosure. The process flow 500 may implement aspects of the wireless communication systems 100 and 200 or may be implemented by aspects of the wireless communication systems 100 and 200. For example, process flow 500 may illustrate operations between UE 115-d, UE 115-e, UE 115-f, and network entity 105-b (which may be examples of corresponding devices described herein). In the following description of process flow 500, operations between UE 115-d, UE 115-e, UE 115-f, and network entity 105-b may be transmitted in a different order than the example order shown, or the operations performed may be performed in a different order or at a different time. Some operations may also be omitted from process flow 500 and other operations may be added to process flow 500.

At 505-a, the network entity 105-b may send a configuration for one or more DRS windows. The UE 115-d may receive signaling from the network entity 105-b that includes the configuration for the one or more DRS windows. At 505-b, UE 115-e may receive signaling indicating the configuration for the one or more DRS windows. According to the configuration, the configuration of the one or more DRS windows may include two or more SSB reception opportunities and two or more SSB transmission opportunities. In some cases, the UE 115-e may be considered a first UE and the UE 115-d may be considered a second UE. At 505-b, the signaling indicating the configuration may be side chain control signaling (e.g., side chain control information (SCI)). In some examples, the UE 115-e may relay the configuration for the one or more DRS windows to the UE 115-f using control signaling.

In some examples, the UE 115-e receiving the signaling indicating the configuration includes receiving signaling indicating receipt of a DRS window. The receive DRS window may include two or more SSB receive opportunities. Additionally, receiving, at the UE 115-e, the signaling indicating the configuration may also include receiving signaling indicating to send a DRS window. The transmit DRS window may include two or more SSB transmit opportunities. In some cases, the resources of the receiving DRS window and the resources of the transmitting DRS window may not overlap in the time domain. In some other cases, the resource of the receiving DRS window and the resource of the transmitting DRS window may at least partially overlap in the time domain. In such cases, at least one of the SSB reception occasions may be positioned (e.g., in an interleaved mode) in the time domain at least between at least two of the SSB transmission occasions. In some cases, the resources of the receiving DRS window and the resources of the transmitting DRS window may not overlap in the frequency domain (e.g., are located in different frequency resources, which may be orthogonal).

In some other examples, the UE 115-e receiving the signaling indicating the configuration includes receiving signaling indicating a DRS window (e.g., a single DRS window). For example, the DRS window may include the two or more SSB reception opportunities and the two or more SSB transmission opportunities. In some cases, at least one of the SSB reception occasions may be positioned (e.g., in an interleaved mode) in the time domain between at least two of the SSB transmission occasions.

In some implementations, the UE 115-e receiving the signaling indicating the configuration includes receiving an indication of a first number of the two or more SSB transmission occasions. Additionally, the configuration may include a second number of the two or more SSB reception opportunities, or both the first number and the second number.

In some examples, the UE 115-e receiving the signaling indicating the configuration includes receiving an indication of a spacing between a first SSB occasion and a second SSB occasion of the one or more DRS windows in the time domain. For example, the indication of the spacing between the first SSB occasion and the second SSB occasion may indicate a number of slots. In some examples, the indicated number of slots may be 0 such that the first SSB occasion and the second SSB occasion are adjacent to each other. In some cases, each of the two or more SSB reception occasions and each of the two or more transmission occasions may correspond to a respective time slot of the one or more DRS windows.

At 510, the UE 115-e may monitor for receipt of an S-SSB message from the UE 115-d during the two or more SSB reception occasions of the one or more DRS windows based at least in part on the configuration.

At 515, the UE 115-e may receive a first S-SSB message from the UE 115-d during the two or more SSB reception occasions of the one or more DRS windows. In some examples, the UE 115-e may receive the first S-SSB message from the UE 115-d based at least on the monitoring at 510. In some cases, the first S-SSB message may include synchronization or timing information from the UE 115-d. In such cases, the UE 115-e may not be in the coverage area of the network entity 105-b and the UE 115-d may be in the coverage area of the network entity 105-b. In such examples, the UE 115-d may send the first S-SSB message to the UE 115-e. The first S-SSB message may include synchronization or timing information from the network entity 105-b.

At 520, in some implementations, the UE 115-e may determine that the synchronization accuracy of the UE 115-e meets a synchronization accuracy threshold. The synchronization accuracy may include timing or frequency accuracy of the wireless system. The wireless system may be an example of the wireless communication system 100 or the wireless communication system 200.

At 525, in some cases, the UE 115-e may perform an LBT procedure during the one or more DRS windows. For example, the UE 115-e may send a second S-SSB message in response to clearing the LBT procedure. In some examples, the one or more DRS windows may contain two or more SSB transmission opportunities in the event that the LBT procedure fails.

At 530, UE 115-e may send the second S-SSB message to UE 115-f based at least on the configuration. UE 115-e may send the second S-SSB message to UE 115-f during at least one of the two or more SSB transmission occasions of the one or more DRS windows. In some examples, the UE 115-e may send the second S-SSB message to the UE 115-f during at least one SSB transmission occasion in response to receiving the first S-SSB message from the UE 115-d during at least one of the two or more SSB reception occasions. In some examples, the UE 115-e may send the second S-SSB message in response to determining that the synchronization accuracy of the UE 115-e meets the synchronization accuracy threshold and/or in response to clearing the LBT procedure.

Fig. 6 illustrates an example of a process flow 600 supporting discovery reference window configuration for a side link in accordance with various aspects of the disclosure. The process flow 600 may implement aspects of the wireless communication systems 100 and 200 or may be implemented by aspects of the wireless communication systems 100 and 200. For example, process flow 600 may illustrate operations between UE 115-g, UE 115-h, UE 115-i, and network entity 105-c (which may be examples of corresponding devices described herein). In the following description of process flow 600, operations between UE 115-g, UE 115-h, UE 115-i, and network entity 105-c may be transmitted in a different order than the example order shown, or the operations performed may be performed in a different order or at a different time. Some operations may also be omitted from process flow 600 and other operations may be added to process flow 600.

At 605-a, the network entity 105-c may send signaling to the UE 115-g indicating a configuration for one or more DRS windows. The configuration of each of the one or more DRS windows may include a first SSB occasion for transmitting a first S-SSB message and a second SSB occasion for transmitting a second S-SSB message. Additionally, the configuration of the one or more DRS windows may include additional SSB transmission opportunity sets.

At 605-b, the UE 115-g may send the signaling to the UE 115-h indicating the configuration for the one or more DRS windows. The configuration of each of the one or more DRS windows may include the first SSB occasion to send the first S-SSB message and the second SSB occasion to send the second S-SSB message. Additionally, the configuration of the one or more DRS windows can include the additional set of SSB transmit opportunities.

Further, at 605-b, the UE 115-h may receive the signaling from the UE 115-g indicating the configuration for the one or more DRS windows. In some examples, the UE 115-h may relay the configuration of the one or more DRS windows to the UE 115-i. The configuration of each of the one or more DRS windows may include the first SSB occasion to send the first S-SSB message and the second SSB occasion to send the second S-SSB message. The first SSB occasion may be used by UE 115-g to transmit the first S-SSB and by UE 115-h to monitor UE 115-g for transmission of the first S-SSB message. The second SSB occasion may be used by UE 115-h to send the second S-SSB message and by UE 115-i to monitor UE 115-h for the sending of the second S-SSB message. In some cases, the UE 115-h may be considered a first UE and the UE 115-g may be considered a second UE. Additionally, the configuration of the one or more DRS windows can include the additional set of SSB transmit opportunities. The additional set of SSB transmit occasions may be configured for transmission of S-SSBs by any UE 115 in the set of UEs 115. The set of UEs 115 may include UEs 115-g and UEs 115-h. In some examples, each of the first SSB occasion, the second SSB occasion, and the additional SSB transmission occasion may correspond to a respective time slot of the one or more DRS windows.

At 610, UE 115-h may monitor for transmission of the first S-SSB message from UE 115-g during the first SSB occasion of the one or more DRS windows based at least on the configuration of the one or more DRS windows received at 605-b.

At 615, the UE 115-h may receive the first S-SSB message from the UE 115-g during the first SSB occasion of the one or more DRS windows.

At 620, UE 115-h may attempt to transmit the second S-SSB during the second SSB occasion of the one or more DRS windows. In some examples, whether to send the second S-SSB message during the SSB occasion is based on whether the first S-SSB message was received during the first SSB occasion, whether the synchronization accuracy of UE 115-h is greater than a synchronization accuracy threshold, and/or whether UE 115-h successfully performs an LBT procedure during the second SSB occasion.

At 625, in some examples, the UE 115-h may monitor for transmission of the first S-SSB message from the UE 115-g during SSB occasions in the set of additional SSB transmission occasions. UE 115-h may monitor for transmission of the first S-SSB message from UE 115-g during the SSB occasion in the set of additional SSB transmission occasions based at least on failure to receive or decode the first message during the first SSB occasion (e.g., determining that the first S-SSB message is not present). For example, the LBT procedure performed by the UE 115-g may fail during the first SSB occasion, and thus the UE 115-g may refrain from transmitting the S-SSB during the first SSB occasion. Further, since the synchronization accuracy threshold is determined to be unsatisfied, UE 115-h may monitor the first S-SSB message during the set of additional SSB transmit occasions.

At 630, the UE 115-h may transmit the first S-SSB message during a first additional SSB transmission occasion of the set of additional SSB transmission occasions, and receive the first S-SSB message during the first additional SSB transmission occasion of the set of additional SSB transmission occasions based on the UE 115-g.

At 640, UE 115-a may transmit the second S-SSB message during the set of additional SSB transmit occasions. Whether the UE 115-h transmits the second S-SSB message during the set of additional SSB transmission occasions may be based at least on whether the UE 115-h transmits the second S-SSB message during the second SSB occasion. In some cases, the UE 115-h may not send the second S-SSB message during the second SSB occasion because the LBT procedure by the UE 115-h fails. In some other cases, the UE 115-h may send a second S-SSB message to the UE 115-i during a second additional SSB transmission occasion of the set of additional SSB transmission occasions based at least on receiving the first S-SSB message during the first additional SSB transmission occasion. Additionally, the UE 115-h may send the second S-SSB message during the SSB transmission occasions in the additional set of transmission occasions based on a successful LBT procedure performed during the SSB transmission occasions in the additional set of transmission occasions.

Fig. 7 illustrates a block diagram 700 of an apparatus 705 supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure. Device 705 may be an example of aspects of UE 115 as described herein. 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).

Receiver 710 may provide means for receiving information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to discovery reference signal window configurations for side links). Information may be passed to other components of device 705. Receiver 710 may utilize a single antenna or a set of multiple antennas.

Transmitter 715 may provide means for transmitting signals generated by other components of device 705. For example, the transmitter 715 may transmit information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to discovery reference signal window configurations for the side links). 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 set of multiple antennas.

The communication manager 720, receiver 710, transmitter 715, or various combinations thereof, or various components thereof, may be examples of means for performing aspects of discovery reference signal window configuration for a side link as described herein. For example, the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may support methods for performing one or more of the functions described herein.

In some examples, the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be implemented in hardware (e.g., in communication management circuitry). The hardware may include processors, digital Signal Processors (DSPs), central Processing Units (CPUs), application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs) or other programmable logic devices, microcontrollers, discrete gate or transistor logic elements, discrete hardware components, or any combinations thereof, configured or otherwise supporting the components for performing the functions described herein. In some examples, a processor and a memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by the processor executing instructions stored in the memory).

Additionally or alternatively, in some examples, the communication manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be implemented in code (e.g., as communication management software or firmware) that is executed by a processor. If implemented in code executed by a processor, the functions of the communication manager 720, the receiver 710, the transmitter 715, 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 herein), DSP, CPU, ASIC, FPGA, a microcontroller, or any combination of these or other programmable logic devices.

In some examples, communication manager 720 may be configured to perform various operations (e.g., receive, obtain, monitor, output, transmit) using or otherwise in conjunction with receiver 710, transmitter 715, or both. 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.

Additionally or alternatively, according to examples as disclosed herein, the communication manager 720 may support wireless communication at the first UE. For example, the communication manager 720 may be configured as or otherwise support means for receiving signaling indicating a configuration for one or more discovery reference signal windows, which include two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions according to the configuration. The communication manager 720 may be configured or otherwise enabled to monitor for receipt of a first sidelink synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based on the configuration. The communication manager 720 may be configured or otherwise enabled to transmit a second side chain synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows based on the configuration.

Additionally or alternatively, according to examples as disclosed herein, the communication manager 720 may support wireless communication at the first UE. For example, the communication manager 720 may be configured or otherwise support means for receiving signaling indicating a configuration for one or more discovery reference signal windows, each of the one or more discovery reference signal windows including a first set of synchronization signal block occasions for transmitting a first side link synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second side link synchronization signal block message by the first UE, and an additional set of synchronization signal block transmission occasions configured for use by any of a set of UEs including the first UE and the second UE. The communication manager 720 may be configured or otherwise enabled to monitor the second UE for transmission of the first sidelink synchronization signal block message during the first synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration. The communication manager 720 may be configured or otherwise enabled to attempt to send the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration. In some examples, the communication manager 720 may be configured or otherwise support means for the first UE to monitor the second UE for transmission of the first side link synchronization signal block message during the set of additional synchronization signal block transmission occasions based on whether the first UE received the first side link synchronization signal block message during the first synchronization signal block occasion, and the first UE to transmit the second side link synchronization signal block message during the set of additional synchronization signal block transmission occasions based on whether the first UE transmitted the second side link synchronization signal block message during the second synchronization signal block occasion.

By including or configuring a communication manager 720 according to examples as described herein, a device 705 (e.g., a processor controlling or otherwise coupled to a receiver 710, a transmitter 715, a communication manager 720, or a combination thereof) may support techniques for reducing processing due to improved synchronization with a network. For example, by performing the S-SSB procedure according to the DRS window configuration described herein, synchronization information may be more efficiently notified to individual UEs, resulting in reduced processing overhead due to lack or reduction of synchronization with the network.

Fig. 8 illustrates a block diagram 800 of a device 805 that supports discovery reference signal window configuration for a side link in accordance with one or more aspects of the disclosure. Device 805 may be an example of aspects of device 705 or UE 115 as described herein. The device 805 may include a receiver 810, a transmitter 815, and a communication manager 820. The device 805 may also include a processor. Each of these components may communicate with each other (e.g., via one or more buses).

The receiver 810 may provide means for receiving information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to discovery reference signal window configurations for side links). Information may be passed to other components of device 805. The receiver 810 may utilize a single antenna or a set of multiple antennas.

The transmitter 815 may provide a means for transmitting signals generated by other components of the device 805. For example, the transmitter 815 may transmit information (such as packets, user data, control information, or any combination thereof) associated with various information channels (e.g., control channels, data channels, information channels related to discovery reference signal window configurations for the side links). In some examples, the transmitter 815 may be co-located with the receiver 810 in a transceiver module. The transmitter 815 may utilize a single antenna or a set of multiple antennas.

The device 805 or various components thereof may be an example of means for performing aspects of discovery reference signal window configuration for a side link as described herein. For example, communication manager 820 may include a configuration signaling interface 825, an SSB monitoring component 830, an SSB sending component 835, or any combination thereof. Communication manager 820 may be an example of aspects of communication manager 720 as described herein. In some examples, communication manager 820 or various components thereof may be configured to perform various operations (e.g., receive, obtain, monitor, output, transmit) using or otherwise in conjunction with receiver 810, transmitter 815, or both. For example, communication manager 820 may receive information from receiver 810, transmit information to transmitter 815, or be integrated with receiver 810, transmitter 815, or both, to obtain information, output information, or perform various other operations as described herein.

According to examples as disclosed herein, the communication manager 820 may support wireless communication at the first UE. The configuration signaling interface 825 may be configured as or otherwise support means for receiving signaling indicating a configuration for one or more discovery reference signal windows, which include two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions, according to the configuration. SSB monitoring component 830 may be configured or otherwise enabled to monitor for receipt of a first sidelink synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based on the configuration. The SSB sending component 835 may be configured as or otherwise support means for sending a second side chain synchronization signal block message to a third UE during at least one of the two or more synchronization signal block sending occasions of the one or more discovery reference signal windows based on the configuration.

Additionally or alternatively, according to examples as disclosed herein, the communication manager 820 may support wireless communication at the first UE. The configuration signaling interface 825 may be configured as or otherwise support means for receiving signaling indicating a configuration for one or more discovery reference signal windows, each of the one or more discovery reference signal windows comprising a first synchronization signal block occasion for transmitting a first side link synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second side link synchronization signal block message by the first UE, and a set of additional synchronization signal block transmission occasions configured for use by any one of a set of UEs including the first UE and the second UE. SSB monitoring component 830 may be configured or otherwise enabled to monitor the transmission of the first sidelink synchronization signal block message by the second UE during the first synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration. SSB sending component 835 may be configured as or otherwise support means for attempting to send the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration. In some examples, SSB receiving component 840 may be configured or otherwise enabled to monitor, by the first UE, transmission of the first side link synchronization signal block message during the set of additional synchronization signal block transmission occasions based on whether the first UE received the first side link synchronization signal block message during the first synchronization signal block occasion, and additional occasion component 845 may be configured or otherwise enabled to transmit, by the first UE, the second side link synchronization signal block message during the set of additional synchronization signal block transmission occasions based on whether the first UE transmitted the second side link synchronization signal block message during the second synchronization signal block occasion.

Fig. 9 illustrates a block diagram 900 of a communication manager 920 supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the disclosure. Communication manager 920 may be an example of aspects of communication manager 720, communication manager 820, or both, as described herein. The communication manager 920 or various components thereof may be an example of means for performing aspects of discovery reference signal window configuration for a side link as described herein. For example, the communication manager 920 can include a configuration signaling interface 925, an SSB monitoring component 930, an SSB sending component 935, an SSB occasion configuration interface 940, an additional occasion component 945, an SSB absence component 950, a synchronization accuracy component 955, an SSB receiving component 960, an LBT component 965, or any combination thereof. Each of these components may communicate with each other directly or indirectly (e.g., via one or more buses).

Additionally or alternatively, according to examples as disclosed herein, the communication manager 920 may support wireless communication at the first UE. The configuration signaling interface 925 may be configured as or otherwise support means for receiving signaling indicating a configuration for one or more discovery reference signal windows, which include two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions, according to the configuration. The SSB monitoring component 930 may be configured or otherwise enabled to monitor for receipt of a first sidelink synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based on the configuration. The SSB transmission component 935 may be configured or otherwise enabled to transmit a second side-chain synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows based on the configuration.

In some examples, to support receiving the signaling indicating the configuration, the configuration signaling interface 925 may be configured as or otherwise support means for receiving signaling indicating a receive discovery reference signal window including the two or more synchronization signal block reception occasions and a transmit discovery reference signal window including the two or more synchronization signal block transmission occasions.

In some examples, to support receiving the signaling indicating the configuration, the configuration signaling interface 925 may be configured as or otherwise support means for receiving signaling indicating a discovery reference signal window including the two or more synchronization signal block reception occasions and the two or more synchronization signal block transmission occasions.

In some examples, to support receiving the signaling indicating the configuration, SSB occasion configuration interface 940 may be configured as or otherwise support means for receiving an indication of a first number of the two or more synchronization signal block transmission occasions, a second number of the two or more synchronization signal block reception occasions, or both the first number and the second number.

Additionally or alternatively, according to examples as disclosed herein, the communication manager 920 may support wireless communication at the first UE. In some examples, the configuration signaling interface 925 may be configured as or otherwise support means for receiving signaling indicating a configuration for one or more discovery reference signal windows, each of the one or more discovery reference signal windows including a first set of synchronization signal block occasions for transmitting a first side link synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second side link synchronization signal block message by the first UE, and an additional set of synchronization signal block transmission occasions configured for use by any of a set of UEs including the first UE and the second UE. In some examples, SSB monitoring component 930 may be configured or otherwise enabled to monitor the transmission of the first side link synchronization signal block message by the second UE during the first synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration. In some examples, SSB sending component 935 may be configured as or otherwise support means for attempting to send the second side link synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration. In some examples, SSB receiving component 960 may be configured as or otherwise support means for the first UE to monitor transmission of the first side link synchronization signal block message by the second UE during the set of additional synchronization signal block transmission occasions based on whether the first UE received the first side link synchronization signal block message during the first synchronization signal block occasion, and additional occasion component 945 may be configured as or otherwise support means for the first UE to transmit the second side link synchronization signal block message during the set of additional synchronization signal block transmission occasions based on whether the first UE transmitted the second side link synchronization signal block message during the second synchronization signal block occasion.

In some examples, the additional occasion component 945 may be configured as or otherwise support means for transmitting the second side link synchronization signal block message during a synchronization signal block transmission occasion of the additional set of synchronization signal block transmission occasions based on the listen before talk procedure failing during the second synchronization signal block occasion.

In some examples, SSB absence component 950 may be configured or otherwise enabled to determine that the first side link synchronization signal block message is absent from the first synchronization signal block occasion based on the monitoring during the first synchronization signal block occasion. In some examples, SSB monitoring component 930 may be configured or otherwise enabled to monitor transmission of the first side link synchronization signal block message by the second UE during a synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based on an absence of the first side link synchronization signal block message in the first synchronization signal block occasion.

In some examples, the synchronization accuracy component 955 may be configured as or otherwise support means for determining that the synchronization accuracy of the first UE is below a synchronization accuracy threshold. In some examples, SSB monitoring component 930 may be configured or otherwise enabled to monitor transmission of the first sidelink synchronization signal block message by the second UE during a synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based on determining that the synchronization accuracy of the first UE is below the synchronization accuracy threshold.

In some examples, synchronization accuracy component 955 may be configured as or otherwise support means for determining that synchronization accuracy of the first UE meets a synchronization accuracy threshold, wherein the first UE sends the second side link synchronization signal block message in response to determining that the synchronization accuracy of the first UE meets the synchronization accuracy threshold.

In some examples, SSB reception component 960 may be configured as or otherwise support means for receiving the first side link synchronization signal block message from the second UE based on the monitoring, wherein the first UE transmits the second side link synchronization signal block message during at least one synchronization signal block transmission occasion in response to receiving the first side link synchronization signal block message during at least one of the two or more synchronization signal block reception occasions.

In some examples, SSB receiving component 960 may be configured as or otherwise support a component for the first UE to receive the first sidelink synchronization signal block message during a first additional synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions. In some examples, SSB transmission component 935 may be configured or otherwise enabled to transmit a second side link synchronization signal block message during a second additional synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based at least in part on receiving the first side link synchronization signal block message during the first additional synchronization signal block transmission occasion.

In some examples, LBT component 965 may be configured as or otherwise support means for performing a listen before talk procedure during the one or more discovery reference signal windows, wherein the first UE sends the second side link synchronization signal block message in response to clearing the listen before talk procedure.

Fig. 10 illustrates a diagram of a system 1000 including a device 1005 supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure. Device 1005 may be or include an example of device 705, device 805, or UE 115 as described herein. The device 1005 may communicate (e.g., wirelessly) with one or more network entities 105, one or more UEs 115, or any combination thereof. Device 1005 may include components for two-way voice and data communications, including components for sending and receiving communications, such as a communications manager 1020, an input/output (I/O) controller 1010, a transceiver 1015, an antenna 1025, a memory 1030, code 1035, and a processor 1040. These components may be in electronic communication or otherwise (e.g., operatively, communicatively, functionally, electronically, electrically) coupled via one or more buses (e.g., bus 1045).

The I/O controller 1010 may manage input signals and output signals of the device 1005. The I/O controller 1010 may also manage peripheral devices that are not integrated into the device 1005. In some cases, I/O controller 1010 may represent a physical connection or port to an external peripheral device. In some cases, I/O controller 1010 may utilize an operating system, such as Or another known operating system. Additionally or alternatively, the I/O controller 1010 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I/O controller 1010 may be implemented as part of a processor, such as processor 1040. In some cases, a user may interact with the device 1005 via the I/O controller 1010 or via hardware components controlled by the I/O controller 1010.

In some cases, the device 1005 may include a single antenna 1025. However, in some other cases, the device 1005 may have more than one antenna 1025 that may be capable of concurrently transmitting or receiving multiple wireless transmissions. The transceiver 1015 may communicate bi-directionally via one or more antennas 1025, wired links, or wireless links as described herein. For example, transceiver 1015 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1015 may also include a modem for modulating packets, for providing the modulated packets to one or more antennas 1025 for transmission, and for demodulating packets received from the one or more antennas 1025. The transceiver 1015, or the transceiver 1015 and the one or more antennas 1025, may be examples of a transmitter 715, a transmitter 815, a receiver 710, a receiver 810, or any combination thereof, or any component thereof, as described herein.

Memory 1030 may include Random Access Memory (RAM) and Read Only Memory (ROM). Memory 1030 may store computer-readable, computer-executable code 1035 comprising instructions that, when executed by processor 1040, cause device 1005 to perform the various functions described herein. Code 1035 may be stored in a non-transitory computer readable medium, such as system memory or another type of memory. In some cases, code 1035 may not be directly executable by processor 1040, but may (e.g., when compiled and executed) cause a computer to perform the functions described herein. In some cases, memory 1030 may include, among other things, a basic I/O system (BIOS) that may control basic hardware or software operations, such as interactions with peripheral components or devices.

Processor 1040 may include intelligent hardware devices (e.g., general purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combinations thereof). In some cases, processor 1040 may be configured to operate the memory array using a memory controller. In some other cases, the memory controller may be integrated into the processor 1040. Processor 1040 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 1030) to cause device 1005 to perform various functions (e.g., support functions or tasks for discovery reference signal window configuration for side links). For example, the device 1005 or components of the device 1005 may include a processor 1040 and a memory 1030 coupled to or coupled to the processor 1040, the processor 1040 and the memory 1030 configured to perform various functions described herein.

Additionally or alternatively, according to examples as disclosed herein, the communication manager 1020 may support wireless communication at the first UE. For example, the communication manager 1020 may be configured as or otherwise support means for receiving signaling indicating a configuration for one or more discovery reference signal windows, the one or more discovery reference signal windows including two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions according to the configuration. The communications manager 1020 may be configured or otherwise enabled to monitor for receipt of a first sidelink synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based on the configuration. The communication manager 1020 may be configured or otherwise support means for transmitting a second side chain synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows based on the configuration.

Additionally or alternatively, according to examples as disclosed herein, the communication manager 1020 may support wireless communication at the first UE. For example, the communication manager 1020 may be configured or otherwise support means for receiving signaling indicating a configuration for one or more discovery reference signal windows, each of the one or more discovery reference signal windows including a first set of synchronization signal block occasions for transmitting a first side link synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second side link synchronization signal block message by the first UE, and an additional set of synchronization signal block transmission occasions configured for use by any of a set of UEs including the first UE and the second UE. The communications manager 1020 may be configured or otherwise enabled to monitor the transmission of the first sidelink synchronization signal block message by the second UE during the first synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration. The communications manager 1020 may be configured or otherwise support means for attempting to transmit the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration. In some examples, to attempt to transmit the side link synchronization signal block message, the communication manager 1020 may be configured as or otherwise support means for the first UE to monitor the second UE for transmission of the first side link synchronization signal block message during the set of additional synchronization signal block transmission occasions based on whether the first UE received the first side link synchronization signal block message during the first synchronization signal block occasion, and the first UE to transmit the second side link synchronization signal block message during the set of additional synchronization signal block transmission occasions based on whether the first UE transmitted the second side link synchronization signal block message during the second synchronization signal block occasion.

By including or configuring a communication manager 1020 according to examples as described herein, the device 1005 may support techniques for improving communication reliability due to improved synchronization with a network. For example, by performing the S-SSB procedure according to the DRS window configuration described herein, synchronization information can be more efficiently notified to individual UEs, resulting in reliably improved communications by improving synchronization.

In some examples, the communication manager 1020 may be configured to perform various operations (e.g., receive, monitor, transmit) using or otherwise in conjunction with the transceiver 1015, the one or more antennas 1025, or any combination thereof. Although communication manager 1020 is illustrated as a separate component, in some examples, one or more of the functions described with reference to communication manager 1020 may be supported or performed by processor 1040, memory 1030, code 1035, or any combination thereof. For example, code 1035 may include instructions executable by processor 1040 to cause device 1005 to perform aspects of discovery reference signal window configuration for a side link as described herein, or processor 1040 and memory 1030 may be otherwise configured to perform or support such operations.

Fig. 11 shows a flow diagram illustrating a method 1100 of supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the disclosure. The operations of method 1100 may be implemented by a UE or components thereof as described herein. For example, the operations of method 1100 may be performed by UE 115 as described with reference to fig. 1-10. In some examples, a UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described functionality.

At 1105, the method may include receiving signaling indicating a configuration for one or more discovery reference signal windows, the one or more discovery reference signal windows including two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions according to the configuration. The operations of 1105 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1105 may be performed by the configuration signaling interface 925 as described with reference to fig. 9.

At 1110, the method may include monitoring for receipt of a first sidelink synchronization signal block message from a second UE during the two or more synchronization signal block receipt opportunities of the one or more discovery reference signal windows based on the configuration. 1110 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1110 may be performed by SSB monitoring component 930 as described with reference to fig. 9.

At 1115, the method may include transmitting, based on the configuration, a second side chain synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows. 1115 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1115 may be performed by SSB sending component 935 as described with reference to fig. 9.

Fig. 12 shows a flow diagram illustrating a method 1200 of supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the disclosure. The operations of method 1200 may be implemented by a UE or components thereof as described herein. For example, the operations of method 1200 may be performed by UE 115 as described with reference to fig. 1-10. In some examples, a UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described functionality.

At 1205, the method may include receiving signaling indicating a configuration for a receive discovery reference signal window including two or more synchronization signal block reception occasions and a transmit discovery reference signal window including two or more synchronization signal block transmission occasions. Operations of 1205 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operation of 1205 may be performed by the configuration signaling interface 925 as described with reference to fig. 9.

At 1210, the method may include monitoring for reception of a first sidelink synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the reception discovery reference signal window based on the configuration. The operations of 1210 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1210 may be performed by SSB monitoring component 930 as described with reference to fig. 9.

At 1215, the method may include transmitting a second sidelink synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the transmit discovery reference signal window based on the configuration. The operations of 1215 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1215 may be performed by SSB sending component 935 as described with reference to fig. 9.

Fig. 13 shows a flow diagram illustrating a method 1300 of supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure. The operations of method 1300 may be implemented by a UE or components thereof as described herein. For example, the operations of method 1300 may be performed by UE 115 as described with reference to fig. 1-10. In some examples, a UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described functionality.

At 1305, the method may include receiving signaling indicating a configuration for a discovery reference signal window including two or more synchronization signal block reception opportunities and two or more synchronization signal block transmission opportunities. 1305 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1305 may be performed by the configuration signaling interface 925 as described with reference to fig. 9.

At 1310, the method may include monitoring for receipt of a first sidelink synchronization signal block message from a second UE during the two or more synchronization signal block receipt opportunities of the discovery reference signal window based on the configuration. Operations of 1310 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1310 may be performed by SSB monitoring component 930 as described with reference to fig. 9.

At 1315, the method may include transmitting a second sidelink synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the discovery reference signal window based on the configuration. The operations of 1315 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operation of 1315 may be performed by SSB sending component 935 as described with reference to fig. 9.

Fig. 14 shows a flow diagram illustrating a method 1400 of supporting discovery reference signal window configuration for a side link in accordance with one or more aspects of the present disclosure. The operations of method 1400 may be implemented by a UE or components thereof as described herein. For example, the operations of method 1400 may be performed by UE 115 as described with reference to fig. 1-10. In some examples, a UE may execute a set of instructions to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described functionality.

At 1405, the method may include receiving signaling indicating a configuration for one or more discovery reference signal windows, each discovery reference signal window of the one or more discovery reference signal windows including a first synchronization signal block occasion for transmitting a first side link synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second side link synchronization signal block message by the first UE, and a set of additional synchronization signal block transmission occasions configured for use by any one of a set of UEs including the first UE and the second UE. 1405 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1405 may be performed by the configuration signaling interface 925 as described with reference to fig. 9.

At 1410, the method may include monitoring, based on the configuration, transmission of the first sidelink synchronization signal block message by the second UE during the first synchronization signal block occasion of the one or more discovery reference signal windows. 1410 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1410 may be performed by SSB monitoring component 930 as described with reference to fig. 9.

At 1415, the method may include attempting to transmit the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows based on the configuration. 1415 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1415 can be performed by SSB sending component 935 as described with reference to fig. 9.

In some examples, whether the first UE monitors the transmission of the first side link synchronization signal block message by the second UE during the set of additional synchronization signal block transmission occasions is based on whether the first UE receives the first side link synchronization signal block message during the first synchronization signal block occasion. For example, if the first UE did not receive the first side link synchronization signal block message during the first synchronization signal block occasion, the method may include monitoring for transmission of the first side link synchronization signal block message by the second UE during the set of additional synchronization signal block transmission occasions at 1420. The first UE may not monitor the second UE for transmission of the first side link synchronization signal block message during the set of additional synchronization signal block transmission occasions if the first UE receives the first side link synchronization signal block message during the first synchronization signal block occasion. Operations of 1420 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1420 may be performed by SSB monitoring component 930 as described with reference to fig. 9.

Additionally or alternatively, whether the first UE transmits the second side link synchronization signal block message during the set of additional synchronization signal block transmission occasions is based on whether the first UE transmits the second side link synchronization signal block message during the second synchronization signal block occasion. For example, if the second side link synchronization signal block message is not transmitted during the second synchronization signal block occasion, the method may include transmitting the second side link synchronization signal block message during the set of additional synchronization signal block transmission occasions at 1425. The first UE may not transmit the second side link synchronization signal block message during the set of additional synchronization signal block transmission occasions if the second side link synchronization signal block message is transmitted during the second synchronization signal block occasion. The operations of 1425 may be performed according to examples as disclosed herein. In some examples, aspects of the operation of 1425 may be performed by SSB sending component 935 as described with reference to fig. 9.

The following provides an overview of aspects of the disclosure:

Aspect 1 a method for wireless communication at a first UE, the method comprising receiving signaling indicating a configuration for one or more discovery reference signal windows, according to the configuration, the one or more discovery reference signal windows comprising two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions, monitoring reception of a first side link synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based at least in part on the configuration, and transmitting a second side link synchronization signal block message to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows based at least in part on the configuration.

Aspect 2 the method of aspect 1, wherein receiving the signaling indicating the configuration comprises receiving signaling indicating a receive discovery reference signal window comprising the two or more synchronization signal block reception occasions and a transmit discovery reference signal window comprising the two or more synchronization signal block transmission occasions.

Aspect 3 the method of aspect 2, wherein the resources of the receive discovery reference signal window and the resources of the transmit discovery reference signal window do not overlap in the time domain.

Aspect 4 the method of any one of aspects 2 to 3, wherein the resources of the receive discovery reference signal window and the resources of the transmit discovery reference signal window overlap at least partially in the time domain.

Aspect 5 the method of aspect 4, wherein at least one of the synchronization signal block reception occasions is positioned in the time domain between at least two of the synchronization signal block transmission occasions.

Aspect 6 the method of any one of aspects 2 to 5, wherein the resources of the receive discovery reference signal window and the resources of the transmit discovery reference signal window do not overlap in the frequency domain.

Aspect 7 the method of aspect 1, wherein receiving the signaling indicating the configuration comprises receiving signaling indicating a discovery reference signal window, the discovery reference signal window comprising the two or more synchronization signal block reception opportunities and the two or more synchronization signal block transmission opportunities.

Aspect 8 the method of aspect 7, wherein at least one of the synchronization signal block reception occasions is positioned in the time domain between at least two of the synchronization signal block transmission occasions.

Aspect 9 the method of any one of aspects 1 to 8, wherein receiving the signaling indicating the configuration comprises receiving an indication of a first number of the two or more synchronization signal block transmission occasions, a second number of the two or more synchronization signal block reception occasions, or both the first number and the second number.

Aspect 10 the method of any one of aspects 1 to 9, wherein receiving the signaling indicating the configuration comprises receiving an indication of a spacing in the time domain between a first synchronization signal block occasion and a second synchronization signal block occasion of the one or more discovery reference signal windows.

Aspect 11 the method of aspect 10, wherein the indication of the spacing indicates a number of time slots.

Aspect 12 the method of aspect 11, wherein the indicated number of time slots is 0.

Aspect 13 the method of any one of aspects 1 to 12, further comprising performing a listen before talk procedure during the one or more discovery reference signal windows, wherein the first UE sends the second sidelink synchronization signal block message in response to clearing the listen before talk procedure.

Aspect 14 the method of any one of aspects 1 to 13, further comprising receiving the first sidelink synchronization signal block message from the second UE based at least in part on the monitoring, wherein the first UE transmits the second sidelink synchronization signal block message during at least one synchronization signal block transmission occasion in response to receiving the first sidelink synchronization signal block message during at least one of the two or more synchronization signal block reception occasions.

Aspect 15 the method of any one of aspects 1 to 14, further comprising determining that a synchronization accuracy of the first UE meets a synchronization accuracy threshold, wherein the first UE sends the second sidelink synchronization signal block message in response to determining that the synchronization accuracy of the first UE meets the synchronization accuracy threshold.

Aspect 16 the method according to any one of aspects 1 to 15, wherein each of the two or more synchronization signal block reception occasions and each of the two or more synchronization signal block transmission occasions corresponds to a respective time slot of the one or more discovery reference signal windows.

Aspect 17 is a method for wireless communication at a first UE, the method comprising receiving signaling indicating a configuration for one or more discovery reference signal windows, each of the one or more discovery reference signal windows comprising a first set of synchronization signal block occasions for transmitting a first side link synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second side link synchronization signal block message by the first UE, and an additional set of synchronization signal block transmission occasions configured for use by any one of a set of UEs including the first UE and the second UE, monitoring, based at least in part on the configuration, transmission of the first side link synchronization signal block message by the second UE during the first synchronization signal block occasion of the one or more discovery reference signal windows, and based at least in part on the configuration, attempting, during the second synchronization signal block occasion of the one or more side link synchronization signal windows, wherein whether the first UE monitors the transmission of the first sidelink synchronization signal block message by the second UE during the set of additional synchronization signal block transmission occasions is based at least in part on whether the first UE receives the first sidelink synchronization signal block message during the first synchronization signal block occasion, and whether the first UE transmits the second sidelink synchronization signal block message during the set of additional synchronization signal block transmission occasions is based at least in part on whether the first UE transmits the second sidelink synchronization signal block message during the second synchronization signal block occasion.

Aspect 18 the method of aspect 17, wherein attempting to transmit the second side link synchronization signal block message during the second synchronization signal block occasion comprises performing a listen before talk procedure during the second synchronization signal block occasion, the method further comprising transmitting the second side link synchronization signal block message during a synchronization signal block transmission occasion in the set of additional synchronization signal block transmission occasions based at least in part on the listen before talk procedure failing during the second synchronization signal block occasion.

Aspect 19 the method of any one of aspects 17-18, further comprising determining that the first side link synchronization signal block message is absent in the first synchronization signal block occasion based at least in part on the monitoring during the first synchronization signal block occasion, and monitoring transmission of the first side link synchronization signal block message by the second UE during a synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based at least in part on the absence of the first side link synchronization signal block message in the first synchronization signal block occasion.

Aspect 20 the method of any one of aspects 17-19, further comprising determining that a synchronization accuracy of the first UE is below a synchronization accuracy threshold, and monitoring transmission of the first side link synchronization signal block message by the second UE during a synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based at least in part on determining that the synchronization accuracy of the first UE is below the synchronization accuracy threshold.

Aspect 21 the method of any one of aspects 17 to 20, further comprising receiving the first side link synchronization signal block message during a first additional synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions, and transmitting the second side link synchronization signal block message during a second additional synchronization signal block transmission occasion of the set of additional synchronization signal block transmission occasions based at least in part on receiving the first side link synchronization signal block message during the first additional synchronization signal block transmission occasion.

Aspect 22 the method of any one of aspects 17-21, wherein each of the first synchronization signal block occasion, the second synchronization signal block occasion, and the additional synchronization signal block transmission occasion corresponds to a respective time slot of the one or more discovery reference signal windows.

Aspect 23 an apparatus for wireless communication at a first UE, the apparatus comprising a processor, a memory coupled with the processor, and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method of any one of aspects 1-16.

Aspect 24 an apparatus for wireless communication at a first UE, the apparatus comprising at least one means for performing the method of any one of aspects 1-16.

Aspect 25 is a non-transitory computer-readable medium storing code for wireless communication at a first UE, the code comprising instructions executable by a processor to perform the method of any one of aspects 1 to 16.

Aspect 26 an apparatus for wireless communication at a first UE, the apparatus comprising a processor, a memory coupled with the processor, and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method of any one of aspects 17-22.

Aspect 27 is an apparatus for wireless communication at a first UE, the apparatus comprising at least one means for performing the method of any one of aspects 17-22.

Aspect 28 a non-transitory computer-readable medium storing code for wireless communication at a first UE, the code comprising instructions executable by a processor to perform the method of any one of aspects 17 to 22.

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

Although aspects of the LTE, LTE-A, LTE-a Pro or NR system may be described for exemplary 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.

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

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

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 or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the present 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, hardwired or a combination of any of these. Features that implement the functions may also be physically located at different locations, including portions that are distributed such that the functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one location to another. Non-transitory storage media can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media can comprise RAM, ROM, electrically Erasable Programmable ROM (EEPROM), flash memory, compact Disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general purpose or special purpose computer, or a general purpose or special purpose processor. Further, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, includes CD, laser disc, optical disc, digital Versatile Disc (DVD), floppy disk and blu-ray disc. The magnetic disk may magnetically reproduce data, and the optical disk may optically reproduce data using a laser. Combinations of the above are also included within the scope of computer-readable media.

As used herein (including in the claims), an "or" used in an item enumeration (e.g., an item enumeration with a phrase such as "at least one of" or "one or more of" attached) indicates an inclusive enumeration such that, for example, enumeration 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 construed as a reference to a closed condition set. For example, example steps described as "based on condition a" may 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". In addition, as used herein, the phrase "collection" should be interpreted to include the possibility of having a collection of one member. That is, the phrase "set" should be interpreted in the same manner as "one or more".

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

In the drawings, similar components or features may have the same reference numerals. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description may be applied to any one of the similar components having the same first reference label, regardless of the second reference label or other subsequent reference labels.

The description set forth herein in connection with the appended drawings describes example configurations and is not intended to represent all examples that may be implemented or within the scope of the claims. The term "example" as used herein means "serving as an example, instance, or illustration," rather than "preferred" or "advantageous over other examples. The detailed description includes specific details for providing an understanding of the described technology. However, these techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

The description herein is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An apparatus for wireless communication at a first User Equipment (UE), the apparatus 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:

Receiving signaling indicating a configuration for one or more discovery reference signal windows, the one or more discovery reference signal windows including two or more synchronization signal block reception occasions and two or more synchronization signal block transmission occasions according to the configuration;

monitoring for reception of a first sidelink synchronization signal block message from a second UE during the two or more synchronization signal block reception occasions of the one or more discovery reference signal windows based at least in part on the configuration, and

Based at least in part on the configuration, a second sidelink synchronization signal block message is transmitted to a third UE during at least one of the two or more synchronization signal block transmission occasions of the one or more discovery reference signal windows.

2. The apparatus of claim 1, wherein to receive the signaling indicating the configuration, the instructions are executable by the processor to cause the apparatus to:

Signaling is received indicating a receive discovery reference signal window comprising the two or more synchronization signal block reception opportunities and a transmit discovery reference signal window comprising the two or more synchronization signal block transmission opportunities.

3. The apparatus of claim 2, wherein the resources of the receive discovery reference signal window and the resources of the transmit discovery reference signal window do not overlap in the time domain.

4. The apparatus of claim 2, wherein the resources of the receive discovery reference signal window and the resources of the transmit discovery reference signal window overlap at least partially in the time domain.

5. The apparatus of claim 4, wherein at least one of the synchronization signal block reception occasions is positioned in the time domain between at least two of the synchronization signal block transmission occasions.

6. The apparatus of claim 2, wherein the resources of the receive discovery reference signal window and the resources of the transmit discovery reference signal window do not overlap in the frequency domain.

7. The apparatus of claim 1, wherein to receive the signaling indicating the configuration, the instructions are executable by the processor to cause the apparatus to:

Signaling is received indicating a discovery reference signal window comprising the two or more synchronization signal block reception occasions and the two or more synchronization signal block transmission occasions.

8. The apparatus of claim 7, wherein at least one of the synchronization signal block reception occasions is positioned in the time domain between at least two of the synchronization signal block transmission occasions.

9. The apparatus of claim 1, wherein to receive the signaling indicating the configuration, the instructions are executable by the processor to cause the apparatus to:

An indication of a first number of the two or more synchronization signal block transmit occasions, a second number of the two or more synchronization signal block receive occasions, or both the first number and the second number is received.

10. The apparatus of claim 1, wherein to receive the signaling indicating the configuration, the instructions are executable by the processor to cause the apparatus to:

An indication of a spacing in the time domain between a first synchronization signal block occasion and a second synchronization signal block occasion of the one or more discovery reference signal windows is received.

11. The apparatus of claim 10, wherein the indication of the spacing indicates a number of time slots.

12. The apparatus of claim 11, wherein the indicated number of time slots is 0.

13. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to:

A listen before talk procedure is performed during the one or more discovery reference signal windows, wherein the instructions are executable by the processor to cause the apparatus to send the second side link synchronization signal block message in response to clearing the listen before talk procedure.

14. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to:

Based at least in part on the monitoring, the first sidelink synchronization signal block message is received from the second UE, wherein the instructions are executable by the processor to cause the apparatus to transmit the second sidelink synchronization signal block message during at least one synchronization signal block transmission occasion in response to receiving the first sidelink synchronization signal block message during at least one of the two or more synchronization signal block reception occasions.

15. The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to:

Determining that the synchronization accuracy of the first UE meets a synchronization accuracy threshold, wherein the instructions are executable by the processor to cause the apparatus to send the second sidelink synchronization signal block message in response to determining that the synchronization accuracy of the first UE meets the synchronization accuracy threshold.

16. The apparatus of claim 1, wherein each of the two or more synchronization signal block reception occasions and each of the two or more synchronization signal block transmission occasions corresponds to a respective time slot of the one or more discovery reference signal windows.

17. An apparatus for wireless communication at a first User Equipment (UE), the apparatus comprising:

A processor;

a memory coupled to the processor, and

Receiving signaling indicating a configuration for one or more discovery reference signal windows, each of the one or more discovery reference signal windows comprising a first set of synchronization signal block occasions for transmitting a first side link synchronization signal block message by a second UE, a second synchronization signal block occasion for transmitting a second side link synchronization signal block message by the first UE, and an additional set of synchronization signal block transmission occasions configured for use by any one of a set of UEs including the first UE and the second UE;

Monitoring, based at least in part on the configuration, transmission of the first side link synchronization signal block message by the second UE during the first synchronization signal block occasion of the one or more discovery reference signal windows, and

Based at least in part on the configuration, attempting to send the second sidelink synchronization signal block message during the second synchronization signal block occasion of the one or more discovery reference signal windows, wherein:

Monitoring, by the first UE, whether to transmit the first side link synchronization signal block message during the set of additional synchronization signal block transmit occasions based at least in part on whether the first UE received the first side link synchronization signal block message during the first synchronization signal block occasion, and

Whether the first UE transmits the second side link synchronization signal block message during the set of additional synchronization signal block transmission occasions is based at least in part on whether the first UE transmits the second side link synchronization signal block message during the second synchronization signal block occasion.

18. The apparatus of claim 17, wherein:

The instructions are further executable by the processor to cause the apparatus to perform a listen before talk procedure during the second synchronization signal block occasion in order to attempt to send the second side link synchronization signal block message during the second synchronization signal block occasion, and

The instructions are further executable by the processor to cause the apparatus to transmit the second side link synchronization signal block message during a synchronization signal block transmit occasion of the set of additional synchronization signal block transmit occasions based at least in part on the listen before talk procedure failing during the second synchronization signal block occasion.

19. The apparatus of claim 17, wherein the instructions are further executable by the processor to cause the apparatus to:

Determining that the first side link synchronization signal block message is absent from the first synchronization signal block occasion based at least in part on the monitoring during the first synchronization signal block occasion, and

The method further includes monitoring, by the second UE, transmission of the first sidelink synchronization signal block message during a synchronization signal block transmission opportunity of the set of additional synchronization signal block transmission opportunities based at least in part on an absence of the first sidelink synchronization signal block message in the first synchronization signal block opportunity.

20. The apparatus of claim 17, wherein the instructions are further executable by the processor to cause the apparatus to:

Determining that the synchronization accuracy of the first UE is below a synchronization accuracy threshold, and

The method further includes monitoring, by the second UE, transmission of the first sidelink synchronization signal block message during a synchronization signal block transmission opportunity of the set of additional synchronization signal block transmission opportunities based at least in part on determining that the synchronization accuracy of the first UE is below the synchronization accuracy threshold.

21. The apparatus of claim 17, wherein the instructions are further executable by the processor to cause the apparatus to:

Receiving the first side link synchronization signal block message during a first additional synchronization signal block transmission opportunity of the set of additional synchronization signal block transmission opportunities, and

The method further includes transmitting a second side link synchronization signal block message during a second additional synchronization signal block transmission opportunity of the set of additional synchronization signal block transmission opportunities based at least in part on receiving the first side link synchronization signal block message during the first additional synchronization signal block transmission opportunity.

22. The apparatus of claim 17, wherein each of the first synchronization signal block occasion, the second synchronization signal block occasion, and the additional synchronization signal block transmit occasion corresponds to a respective slot of the one or more discovery reference signal windows.

23. A method for wireless communication at a first User Equipment (UE), the method comprising:

24. The method of claim 23, wherein receiving the signaling indicating the configuration comprises:

25. The method of claim 23, wherein receiving the signaling indicating the configuration comprises:

26. The method of claim 23, wherein receiving the signaling indicating the configuration comprises:

27. A method for wireless communication at a first User Equipment (UE), the method comprising:

28. The method of claim 27, wherein attempting to send the second side link synchronization signal block message during the second synchronization signal block occasion comprises performing a listen-before-talk procedure during the second synchronization signal block occasion, the method further comprising:

The second side link synchronization signal block message is transmitted during a synchronization signal block transmission opportunity of the set of additional synchronization signal block transmission opportunities based at least in part on the listen before talk procedure failing during the second synchronization signal block opportunity.

29. The method of claim 27, the method further comprising:

30. The method of claim 27, the method further comprising: