Source-based synchronization for wireless devices

Abstract

Methods, systems, and devices for wireless communication are described. A first device may activate an independent synchronization source mode based on one or more conditions associated with the first device. The independent synchronization source pattern may operate corresponding to the first device as a reference for synchronization. The first device may transmit one or more synchronization signals indicating a device type of the first device and indicating that the first device is operating as the reference for synchronization. For example, the first device may select one or more bits or identifiers corresponding to the device type to be included in the one or more synchronization signals. A second device receiving the one or more synchronization signals may select the first device as a reference for synchronization based on the device type. The second device may synchronize with the first device using the synchronization signal.

Description

Technical Field

[0001] The following relates to wireless communications, including source-based synchronization for wireless devices. Background Art

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

[0003] The described technology relates to improved methods, systems, devices, and apparatuses that support source-based synchronization for wireless devices. For example, the described technology provides a first device acting as an independent synchronization source to indicate its device type to one or more other devices, wherein the one or more other devices can synchronize with the first device based on the indicated device type. In addition, the first device can activate an independent synchronization source mode (e.g., to operate as a reference for synchronization) based on one or more conditions associated with the first device being satisfied. When operating as a reference for synchronization, the first device can send a synchronization signal to the one or more other devices. The synchronization signal can indicate the device type associated with the first device, and can indicate that the first device is operating as the reference for synchronization. For example, the first device can select one or more bits or identifiers corresponding to the device type to include in the synchronization signal. The first device can be an example of a roadside unit (RSU), an on-board unit (OBU), etc.

[0004] A second device (e.g., an OBU, an RSU, etc.) receiving the synchronization signal may select the first device as a reference for synchronization based on the device type or other factors. Additionally or alternatively, the synchronization signal may indicate a priority of a data packet to be sent by the first device, and the second device may select the first device as a reference for synchronization based on the indicated priority. The second device may use the synchronization signal to synchronize with the first device. A method for wireless communication at a first wireless device is described. The method may include: activating an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization; and sending one or more synchronization signals by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as the reference for synchronization.

[0005] An apparatus for wireless communication at a first wireless device 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: activate an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization; and send one or more synchronization signals by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as the reference for synchronization.

[0006] Another apparatus for wireless communication at a first wireless device is described. The apparatus may include: means for activating an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization; and means for sending one or more synchronization signals by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as the reference for synchronization.

[0007] A non-transitory computer-readable medium storing code for wireless communication at a first wireless device is described. The code may include instructions executable by a processor to: activate an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization; and transmit one or more synchronization signals by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as the reference for synchronization.

[0008] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, sending the one or more synchronization signals may include operations, features, components, or instructions for sending an indication of a priority of the first wireless device, the priority indicating that the first wireless device is acting as an independent synchronization source or indicating a priority group associated with the first wireless device.

[0009] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more synchronization signals include a bit field indicating a coverage status of the first wireless device, and the methods, apparatus, and non-transitory computer-readable media may include further operations, features, components, or instructions for selecting one or more bits of the bit field indicating the coverage status based on the device type associated with the first wireless device and the independent synchronization source mode, wherein the one or more bits indicate the device type associated with the first wireless device and indicate that the first wireless device may be operating as the reference for synchronization.

[0010] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more synchronization signals include a sidelink master information block (MIB), and the methods, apparatus, and non-transitory computer-readable media may include further operations, features, components, or instructions for selecting one or more bits for the sidelink MIB based on the device type associated with the first wireless device and the independent synchronization source mode, wherein the one or more bits indicate the device type associated with the first wireless device and indicate that the first wireless device may be operating as the reference for synchronization.

[0011] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for selecting a first identifier from a set of identifiers associated with the independent synchronization source mode and generating the one or more synchronization signals based on the first identifier, wherein the set of identifiers corresponds to the device type associated with the first wireless device.

[0012] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for receiving a second one or more synchronization signals and deactivating the independent synchronization source mode for the first wireless device based on receiving the second one or more synchronization signals, the second one or more synchronization signals indicating a device type associated with the second wireless device.

[0013] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the device type associated with the first wireless device and the device type associated with the second wireless device may be the same, and the methods, apparatus, and non-transitory computer-readable media may include further operations, features, components, or instructions for receiving a second identifier corresponding to the device type associated with the second wireless device as part of the second one or more synchronization signals, wherein deactivating the independent synchronization source mode for the first wireless device is based at least in part on a comparison of the first identifier and the second identifier.

[0014] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the device type associated with the first wireless device may be different from the device type associated with the second wireless device, and the methods, apparatus, and non-transitory computer-readable media may include further operations, features, components, or instructions for receiving a second identifier corresponding to the device type associated with the second wireless device as part of the second one or more synchronization signals, wherein deactivating the independent synchronization source mode for the first wireless device may be based on the device type associated with the second wireless device.

[0015] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more conditions associated with the first wireless device may be satisfied based on a deployment scenario of the first wireless device.

[0016] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first wireless device may be a RSU.

[0017] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for determining one or more applications supported by the first wireless device, wherein the one or more conditions associated with the first wireless device may be satisfied based on the one or more applications.

[0018] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for determining that the one or more conditions associated with the first wireless device are satisfied based on a priority of a packet for transmission by the first wireless device.

[0019] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more synchronization signals include a reserved bit field, and the methods, apparatus, and non-transitory computer-readable media may include further operations, features, components, or instructions for selecting one or more bits for the reserved bit field based on the priority of the packet, wherein the one or more bits indicate the priority of the packet.

[0020] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, at least one of the one or more bits indicates a device priority for the packet, the device priority corresponding to one or both of an RSU and an OBU.

[0021] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for monitoring a second one or more synchronization signals from a second wireless device over a time period, wherein activating the independent synchronization source mode may be based on the absence of the second one or more synchronization signals during the monitoring over the time period.

[0022] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more synchronization signals include a side link synchronization signal (SLSS).

[0023] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first device type corresponds to an RSU and the second device type corresponds to an OBU.

[0024] A method for wireless communication at a second wireless device is described. The method may include: receiving one or more synchronization signals from a first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization; selecting the first wireless device as the reference for synchronization based on the one or more synchronization signals and the device type; and synchronizing with the first wireless device based on the selection.

[0025] An apparatus for wireless communication at a second wireless device 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 one or more synchronization signals from a first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization; select the first wireless device as the reference for synchronization based on the one or more synchronization signals and the device type; and synchronize with the first wireless device based on the selection.

[0026] Another apparatus for wireless communication at a second wireless device is described. The apparatus may include: means for receiving one or more synchronization signals from a first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization; means for selecting the first wireless device as the reference for synchronization based on the one or more synchronization signals and the device type; and means for synchronizing with the first wireless device based on the selection.

[0027] A non-transitory computer-readable medium storing code for wireless communication at a second wireless device is described. The code may include instructions executable by a processor to: receive one or more synchronization signals from a first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization; select the first wireless device as the reference for synchronization based on the one or more synchronization signals and the device type; and synchronize with the first wireless device based on the selection.

[0028] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for sending one or more synchronization signals indicating that the timing of the second wireless device can be based on the first wireless device as the reference for synchronization for the second wireless device.

[0029] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for receiving a bit field indicating a coverage status of the first wireless device as part of the one or more synchronization signals, wherein one or more bits for the bit field indicate the device type associated with the first wireless device and indicate that the first wireless device can be operating as the reference for synchronization, and wherein selecting the first wireless device as the reference for synchronization can be based on the one or more bits.

[0030] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for receiving a sidelink MIB as part of the one or more synchronization signals, wherein one or more bits for the sidelink MIB indicate the device type associated with the first wireless device and indicate that the first wireless device may be operating as the reference for synchronization, and wherein selection of the first wireless device as the reference for synchronization may be based on the one or more bits.

[0031] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for receiving a first identifier from a set of identifiers associated with an independent synchronization source mode as part of the one or more synchronization signals, wherein the set of identifiers corresponds to the device type associated with the first wireless device, and wherein selecting the first wireless device as the reference for synchronization may be based on the first identifier.

[0032] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for receiving a second one or more synchronization signals indicating a device type associated with a third wireless device and indicating that the third wireless device may be operating as a second reference for synchronization, wherein the second one or more synchronization signals include a second identifier from the set of identifiers associated with the independent synchronization source mode and corresponding to the device type associated with the third wireless device, wherein selecting the first wireless device as the reference for synchronization may be based on a comparison of the first identifier and the second identifier.

[0033] In some examples of the methods, apparatuses, and non-transitory computer-readable media described herein, the device type associated with the first wireless device and the device type associated with the third wireless device can be the same.

[0034] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, selecting the first wireless device as the reference for synchronization may include operations, features, components, or instructions for selecting the first wireless device based on a deployment scenario of the second wireless device, one or more applications supported by the second wireless device, or a combination thereof.

[0035] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for selecting the first wireless device as the reference for synchronization, and selecting the first wireless device as the reference for synchronization may be based on the device type associated with the first wireless device and the device type associated with the second wireless device.

[0036] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, components, or instructions for receiving a reserved bit field as part of the one or more synchronization signals, wherein one or more bits for the reserved bit field indicate a priority of a packet for transmission by the first wireless device, and wherein selecting the first wireless device as the reference for synchronization may be based on the priority of the packet.

[0037] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, at least one of the one or more bits indicates a device priority for the packet, the device priority corresponding to one or both of the RSU and the OBU, and selecting the first wireless device as the reference for synchronization may be based on the device priority.

[0038] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the one or more synchronization signals include a SLSS.

[0039] In some examples of the methods, apparatus, and non-transitory computer-readable media described herein, the first device type corresponds to an RSU and the second device type corresponds to an OBU. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 An example of a wireless communication system supporting source-based synchronization for wireless devices in accordance with one or more aspects of the present disclosure is illustrated.

[0041] Figure 2 An example of a wireless communication system supporting source-based synchronization for wireless devices in accordance with one or more aspects of the present disclosure is illustrated.

[0042] Figure 3 An example of synchronization signal coverage supporting source-based synchronization for wireless devices in accordance with one or more aspects of the present disclosure is illustrated.

[0043] Figure 4 An example of a process flow supporting source-based synchronization for wireless devices in accordance with one or more aspects of the present disclosure is illustrated.

[0044] Figure 5 and Figure 6 A block diagram of a device supporting source-based synchronization for wireless devices in accordance with one or more aspects of the present disclosure is shown.

[0045] Figure 7 A block diagram of a communication manager supporting source-based synchronization for wireless devices is shown in accordance with one or more aspects of the present disclosure.

[0046] Figure 8 A diagram of a system including a device supporting source-based synchronization for wireless devices is shown in accordance with one or more aspects of the present disclosure.

[0047] Figures 9 to 12 A flow chart illustrating a method of supporting source-based synchronization for wireless devices in accordance with one or more aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0048] In some wireless communication systems, a user equipment (UE) may receive a synchronization signal from a synchronization source (e.g., a synchronization source) to enable the UE to synchronize with the synchronization source before establishing a connection and communicating with the synchronization source. For example, the synchronization signal may allow the UE to send and receive messages with the synchronization source according to a timing as indicated by the synchronization signal (e.g., the UE adjusts the timing to align with the timing of the synchronization source to enable communication between the UE and the synchronization source or other devices synchronized with the synchronization source). In some cases, the synchronization source may be a network entity such as a base station, a synchronization reference UE, or a similar wireless device that is connected (e.g., directly or indirectly) to a global navigation satellite system (GNSS) or other timing source, wherein the timing associated with the synchronization signal is determined based on the GNSS.

[0049] Alternatively, the synchronization source may be outside the coverage area for the GNSS and may determine the timing to be indicated by the synchronization signal without a direct connection to the GNSS. The synchronization source in this scenario may be referred to as an "independent" synchronization source. For example, the synchronization source may belong to a group or cluster and may synchronize communications with other devices in the group or cluster (such as the UE). In such a case, when the synchronization source is outside the GNSS coverage, the UE may attempt to establish a connection with the synchronization source and may receive a synchronization signal for the synchronization. In some examples, the synchronization source may use a side link synchronization signal (SLSS) for synchronization purposes. The synchronization source may send one or more SLSSs to the UE, and the UE may synchronize with the synchronization source based on the one or more SLSSs.

[0050] In some cases, the UE may receive multiple synchronization signals (e.g., multiple SLSSs) from corresponding multiple synchronization sources, and may select a synchronization source to synchronize with. For example, the UE may prioritize a synchronization source that is directly connected (i.e., directly synchronized) to the GNSS over a synchronization source that is indirectly connected to the GNSS. The UE may further prioritize a synchronization source that has any connection (e.g., direct or indirect) to the GNSS over an out-of-coverage synchronization source (e.g., an independent synchronization source). However, in some scenarios, the UE may not be able to distinguish between synchronization sources for selection. For example, some independent synchronization sources may provide more reliable synchronization or may be more useful to the UE than other independent synchronization sources.

[0051] As described herein, the UE may select an independent synchronization source based on: a device type associated with the independent synchronization source, a priority of a data packet to be sent by the independent synchronization source, a deployment scenario of the UE, one or more applications supported by the UE, or a combination thereof. For example, one or more independent synchronization sources and the UE may each be a device that is part of a vehicle-to-everything (V2X) system such as a roadside unit (RSU), an on-board unit (OBU), etc., and may communicate via a sidelink communication link. A first independent synchronization source may send one or more synchronization signals (such as SLSS) to the UE, and may include an indication of a device type associated with the first independent synchronization source in the synchronization signal. The indication may be one or more bits included in a sidelink master information block (MIB). Additionally or alternatively, the indication may be a SLSS identifier (ID) corresponding to the device type. The techniques described herein may also support other types of synchronization information indicated by one or more synchronization signals.

[0052] The second independent synchronization source may also send one or more SLSSs indicating a device type associated with the second independent synchronization source to the UE. The UE may select the first independent synchronization source or the second independent synchronization source as a reference for synchronization, for example, based on the corresponding one or more synchronization signals received at the UE. The UE may synchronize with the selected independent synchronization source and may establish communication with the independent synchronization source based on the synchronization.

[0053] In some examples, an independent synchronization source may be an example of a device that activates and deactivates an independent synchronization source mode. For example, the device may not initially operate as an independent synchronization source (the independent synchronization source mode is deactivated). Upon determining that one or more conditions associated with the independent synchronization source mode are met, the device may determine to activate the independent synchronization source mode, and may, for example, begin to work as a reference for synchronization by sending a synchronization signal. Some examples of the one or more conditions may include, but are not limited to: a deployment scenario of the device, one or more applications supported by the device, a priority of a packet to be sent by the device, and the like. In some cases, for example, if the independent synchronization source receives a synchronization signal from another device, the independent synchronization source may deactivate the independent synchronization source mode.

[0054] Aspects of the present disclosure are first described in the context of a wireless communication system. Aspects of the present disclosure are illustrated by additional wireless communication systems, synchronization signal coverage diagrams, and process flows. Aspects of the present disclosure are further illustrated and described by and with reference to apparatus diagrams, system diagrams, and flow diagrams related to source-based synchronization for wireless devices.

[0055] Figure 1An example of a wireless communication system 100 supporting source-based synchronization for wireless devices according to one or more aspects of the present disclosure is illustrated. The wireless communication system 100 may include one or more network entities 105, one or more UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an Advanced LTE (LTE-A) network, an LTE-A Pro network, a New Radio (NR) network, or a network operating according to other systems and radio technologies, including future systems and radio technologies not explicitly mentioned herein.

[0056] The network entities 105 may be dispersed throughout a geographic area to form the wireless communication system 100, and may include devices in different forms or with different capabilities. In various examples, the network entities 105 may be referred to as network elements, mobility elements, radio access network (RAN) nodes, or network equipment, among other nomenclature. In some examples, the network entities 105 and the UE 115 may communicate wirelessly via one or more communication links 125 (e.g., radio frequency (RF) access links). For example, the network entity 105 may support a coverage area 110 (e.g., a geographic coverage area), and the UE 115 and the network entity 105 may establish one or more communication links 125 over the coverage area. The coverage area 110 may be an example of a geographic area over which the network entity 105 and the UE 115 may support signal communications according to one or more radio access technologies (RATs).

[0057] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary or mobile, or stationary and mobile at different times. The UEs 115 may be devices in different forms or with different capabilities. Figure 1 Some example UEs 115 are illustrated in FIG. 1. The UEs 115 described herein may be capable of communicating with various types of devices such as Figure 1 Communicating with other UEs 115 or network entities 105 as shown.

[0058] As described herein, a node of the wireless communication system 100 (which may be referred to as a network node or a wireless node) may be a network entity 105 (e.g., any network entity described herein), a UE 115 (e.g., any UE described herein), a network controller, an apparatus, a device, a computing system, one or more components, or another suitable processing entity configured to perform any of the techniques described herein. For example, the node may be a UE 115. As another example, the node may be a network entity 105. As another example, a first node may be configured to communicate with a second node or a third node. In one aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a UE 115. In another aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a network entity 105. In yet other aspects of this example, the first node, the second node, and the third node may be different relative to these examples. Similarly, references to UE 115, network entity 105, apparatus, device, computing system, etc. may include disclosure of UE 115, network entity 105, apparatus, device, computing system, etc. as nodes. For example, a disclosure that UE 115 is configured to receive information from network entity 105 also discloses that the first node is configured to receive information from a second node.

[0059] In some examples, the network entities 105 may communicate with the core network 130, or with each other, or both. For example, the network entities 105 may communicate with the core network 130 via one or more backhaul communication links 120 (e.g., according to S1, N2, N3, or other interface protocols). In some examples, the network entities 105 may communicate with each other through the backhaul communication link 120 (e.g., according to X2, Xn, or other interface protocols) directly (e.g., directly between the network entities 105) or indirectly (e.g., via the core network 130). In some examples, the network entities 105 may communicate with each other via the midhaul communication link 162 (e.g., according to the midhaul interface protocol) or the fronthaul communication link 168 (e.g., according to the fronthaul interface protocol) or any combination thereof. The backhaul communication link 120, the midhaul communication link 162, or the fronthaul communication link 168 may be or may include one or more wired links (e.g., electrical links, optical fiber links), one or more wireless links (e.g., radio links, wireless optical links), and other examples or various combinations thereof. UE 115 may communicate with core network 130 via communication link 155 .

[0060] One or more of the network entities 105 described herein may include or may be referred to as a base station 140 (e.g., a transceiver base station, a radio base station, an NR base station, an access point, a radio transceiver, a Node B, an evolved Node B (eNB), a next-generation Node B, or a giga-Node B (any of which may be referred to as a gNB), a 5G NB, a next-generation eNB (ng-eNB), a home Node B, a home evolved Node B, or other suitable terms). In some examples, the network entity 105 (e.g., a base station 140) may be implemented in an aggregated (e.g., monolithic, stand-alone) base station architecture, which may be configured to utilize a protocol stack physically or logically integrated within a single network entity 105 (e.g., a single RAN node, such as a base station 140).

[0061] In some examples, the network entity 105 may be implemented in a disaggregated architecture (e.g., a disaggregated base station architecture, a disaggregated RAN architecture) that may be configured to utilize a protocol stack that is physically or logically distributed between two or more network entities 105, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance), or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN)). For example, the network entity 105 may include one or more of the following: a central unit (CU) 160, a distributed unit (DU) 165, a radio unit (RU) 170, a RAN intelligent controller (RIC) 175 (e.g., a near real-time RIC (near RT RIC), a non-real-time RIC (non-RT RIC)), a service management and orchestration (SMO) 180 system, or any combination thereof. The RU 170 may also be referred to as a radio head, a smart radio head, a remote radio head (RRH), a remote radio unit (RRU), or a transmit receive point (TRP). One or more components of the network entity 105 in the decomposed RAN architecture may be co-located, or one or more components of the network entity 105 may be located in distributed locations (e.g., separate physical locations). In some examples, one or more network entities 105 of the decomposed RAN architecture may be implemented as virtual units (e.g., virtual CU (VCU), virtual DU (VDU), virtual RU (VRU)).

[0062] The functional split between CU 160, DU 165, and RU 170 is flexible and may support different functionalities depending on which functions (e.g., network layer functions, protocol layer functions, baseband functions, RF functions, and any combination thereof) are performed at CU 160, DU 165, or RU 170. For example, a functional split of a protocol stack may be employed between CU 160 and DU 165 such that CU 160 may support one or more layers of a protocol stack and DU 165 may support one or more different layers of a protocol stack. In some examples, CU 160 may host higher protocol layer (e.g., layer 3 (L3), layer 2 (L2)) functionality and signaling (e.g., radio resource control (RRC), service data adaptation protocol (SDAP), packet data convergence protocol (PDCP)). The CU 160 may be connected to one or more DUs 165 or RUs 170, and the one or more DUs 165 or RUs 170 may host lower protocol layers, such as layer 1 (L1) (e.g., physical (PHY) layer) or L2 (e.g., radio link control (RLC) layer, medium access control (MAC) layer) functionality and signaling, and may each be at least partially controlled by the CU 160. Additionally or alternatively, a functional split of the protocol stack may be employed between the DUs 165 and the RUs 170, such that the DUs 165 may support one or more layers of the protocol stack, and the RUs 170 may support one or more different layers of the protocol stack. The DUs 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 midhaul communication links 162 (e.g., F1, F1-c, F1-u), and DU 165 may be connected to one or more RUs 170 via fronthaul communication links 168 (e.g., open fronthaul (FH) interface). In some examples, midhaul communication link 162 or fronthaul communication link 168 may be implemented based on interfaces (eg, channels) between layers of a protocol stack supported by respective network entities 105 communicating over those communication links.

[0063] In some wireless communication systems (e.g., wireless communication system 100), infrastructure and spectrum resources for radio access may support wireless backhaul link capabilities to supplement wired backhaul connections, thereby providing an IAB network architecture (e.g., to core network 130). In some cases, in an IAB network, one or more network entities 105 (e.g., IAB nodes 104) may be partially controlled by each other. One or more IAB nodes 104 may be referred to as donor entities or IAB donors. One or more DUs 165 or one or more RUs 170 may be controlled in part by one or more CUs 160 associated with a donor network entity 105 (e.g., donor base station 140). One or more donor network entities 105 (e.g., IAB donors) may communicate with one or more additional network entities 105 (e.g., IAB nodes 104) via supported access and backhaul links (e.g., backhaul communication links 120). The IAB node 104 may include an IAB mobile termination (IAB-MT) controlled (e.g., scheduled) by a DU 165 of a coupled IAB donor. The IAB-MT may include an independent set of antennas for relaying communications with the UE 115, or may share the same antennas of the IAB node 104 (e.g., of the RU 170) for access via the DU 165 of the IAB node 104 (e.g., referred to as a virtual IAB-MT (vIAB-MT)). In some examples, the IAB node 104 may include a DU 165 that supports communication links with additional entities (e.g., IAB node 104, UE 115) within a relay chain or configuration (e.g., downstream) of the access network. In such a case, one or more components of the decomposed RAN architecture (e.g., one or more IAB nodes 104 or components of the IAB node 104) may be configured to operate according to the techniques described herein.

[0064] For example, an access network (AN) or RAN may include an access node (e.g., an IAB donor), communications between an IAB node 104, and one or more UEs 115. The IAB donor may facilitate connectivity between the core network 130 and the AN (e.g., via a wired or wireless connection to the core network 130). That is, the IAB donor may refer to a RAN node having a wired or wireless connection to the core network 130. The IAB donor may include a CU 160 and at least one DU 165 (e.g., and RU 170), wherein the CU 160 may communicate with the core network 130 via an interface (e.g., a backhaul link). The IAB donor and the IAB node 104 may communicate via an F1 interface according to a protocol defining signaling messages (e.g., an F1 AP protocol). Additionally or alternatively, CU 160 may communicate with the core network via an interface (which may be an example of part of a backhaul link) and may communicate with other CUs 160 (e.g., CU 160 associated with an alternative IAB donor) via an Xn-C interface (which may be an example of part of a backhaul link).

[0065] An IAB node 104 may refer to a RAN node that provides IAB functionality (e.g., access for UE 115, wireless self-backhaul capabilities, etc.). DU 165 may act as a distributed scheduling node toward child nodes associated with IAB node 104, and IAB-MT may act as a scheduled node toward a parent node associated with IAB node 104. That is, an IAB donor may be referred to as a parent node that communicates with one or more child nodes (e.g., an IAB donor may relay for UE transmissions through one or more other IAB nodes 104). Additionally or alternatively, depending on the relay chain or configuration of the AN, an IAB node 104 may also be referred to as a parent node or child node of other IAB nodes 104. Thus, the IAB-MT entity of the IAB node 104 may provide a Uu interface for the child IAB node 104 to receive signaling from the parent IAB node 104, and a DU interface (eg, DU 165) may provide a Uu interface for the parent IAB node 104 to signal the child IAB node 104 or the UE 115.

[0066] For example, the IAB node 104 may be referred to as a parent node supporting child IAB node communications and as a child node associated with the IAB donor. The IAB donor may include a CU 160 having a wired or wireless connection (e.g., backhaul communication link 120) to the core network 130, and may act as a parent node of the IAB node 104. For example, the DU 165 of the IAB donor may relay transmissions to the UE 115 via the IAB node 104, and may directly signal the transmissions to the UE 115. The CU 160 of the IAB donor may signal the establishment of a communication link to the IAB node 104 via the F1 interface, and the IAB node 104 may schedule transmissions (e.g., transmissions relayed from the IAB donor to the UE 115) via the DU 165. That is, data may be relayed to and from the IAB node 104 via signaling on the NR Uu interface of the MT to the IAB node 104. Communications with the IAB node 104 may be scheduled by the DU 165 of the IAB donor, and communications with the IAB node 104 may be scheduled by the DU 165 of the IAB node 104 .

[0067] Where the techniques described herein are applied to the context of a decomposed RAN architecture, one or more components of the decomposed RAN architecture may be configured to support source-based synchronization for wireless devices as described herein. For example, some operations described as being performed by a UE 115 or a network entity 105 (e.g., a base station 140) may additionally or alternatively be performed by one or more components of the decomposed RAN architecture (e.g., an IAB node 104, a DU 165, a CU 160, a RU 170, a RIC 175, a SMO 180).

[0068] UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable term, where a "device" may also be referred to as a unit, a station, a terminal, or a client, among other examples. UE 115 may also include or may be referred to as a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, UE 115 may include or may be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communication (MTC) device, among other examples, which may be implemented in various objects such as appliances or vehicles, meters, and other examples.

[0069] The UE 115 described herein may be capable of communicating with various types of devices such as other UEs 115 which may sometimes act as relays, as well as network entities 105 and network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, such as Figure 1 shown.

[0070] 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) on one or more carriers. The term "carrier" may refer to a set of RF spectrum resources having a defined physical layer structure to support the communication link 125. For example, a carrier for the communication link 125 may include a portion of an RF spectrum band (e.g., a bandwidth portion (BWP)) that operates according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR). Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information), control signaling for coordinating carrier operations, user data, or other signaling. The wireless communication system 100 may support communications with the UE 115 using carrier aggregation or multi-carrier operation. Depending on the carrier aggregation configuration, the UE 115 may be configured to have multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation may be used for both frequency division duplex (FDD) and time division duplex (TDD) component carriers. Communication between the network entity 105 and other devices may refer to communication between these devices and any portion (e.g., entity, sub-entity) of the network entity 105. For example, the terms "sending," "receiving," or "communicating," when referring to the 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).

[0071] In some examples, such as in a carrier aggregation configuration, a carrier may also have acquisition signaling or control signaling that coordinates the operation of other carriers. A carrier may be associated with a frequency channel (e.g., an Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) Absolute RF Channel Number (EARFCN)) and may be located according to a channel raster for discovery by UE 115. A carrier may operate in a standalone mode, in which case initial acquisition and connection may be performed by UE 115 via the carrier, or a carrier may operate in a non-standalone mode, in which case the connection is anchored using a different carrier (e.g., of the same or different radio access technology).

[0072] The communication link 125 shown in the wireless communication system 100 may include downlink transmissions (e.g., forward link transmissions) from the network entity 105 to the UE 115, uplink transmissions (e.g., return link transmissions) from the UE 115 to the network entity 105, or both, as well as other transmission configurations. A carrier may carry 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).

[0073] A carrier may be associated with a particular bandwidth of the RF spectrum, and in some examples, the carrier bandwidth may be referred to as the "system bandwidth" of the carrier or wireless communication system 100. For example, the carrier bandwidth may be one of a set of bandwidths of carriers for a particular radio access technology (e.g., 1.4 megahertz (MHz), 3 MHz, 5 MHz, 10 MHz, 15 MHz, 20 MHz, 40 MHz, or 80 MHz). Devices of the wireless communication system 100 (e.g., the network entity 105, the UE 115, or both) may have a hardware configuration that supports communication on a particular carrier bandwidth or may be configurable to support communication on one of the carrier bandwidths in the set of carrier bandwidths. In some examples, the wireless communication system 100 may include a network entity 105 or a UE 115 that supports concurrent communication via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured to operate on a portion (e.g., a subband, a BWP) or all of the carrier bandwidth.

[0074] The signal waveform transmitted by the carrier may include multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques, such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element may refer to a resource of one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, in which case the symbol period and the subcarrier spacing may be inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both), so that the more resource elements a device receives and the higher the order of the modulation scheme, the higher the data rate of the device may be. 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 used for communication with UE 115.

[0075] One or more parameter sets for a carrier may be supported, where the parameter set may include subcarrier spacing (Δf) and cyclic prefix. A carrier may be divided into one or more BWPs with the same or different parameter sets. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time, and communications of a UE 115 may be constrained to one or more active BWPs.

[0076] The time interval of the network entity 105 or the UE 115 may be expressed in multiples of a basic time unit, which may be referred to as T s =1 / (Δf max ·N f ) seconds sampling period, where Δf max It can represent the maximum supported subcarrier spacing, and N f The maximum supported discrete Fourier transform (DFT) size may be indicated. 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).

[0077] Each frame may include a plurality of consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some examples, a frame may be divided into subframes (e.g., in the time domain), and each subframe may be further divided into a certain number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include a certain number of code element periods (e.g., depending on the length of the cyclic prefix added before each symbol period). In some wireless communication systems 100, a time slot may also be divided into a plurality of mini-time slots containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N f The duration of a symbol period may depend on the subcarrier spacing or the operating frequency band.

[0078] A subframe, a time slot, a mini-time slot, or a 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 transmit time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (e.g., in a burst of a shortened TTI (sTTI)).

[0079] Physical channels may be multiplexed on a carrier according to various techniques. For example, physical control channels and physical data channels may be multiplexed on a downlink carrier using one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. A control region (e.g., a control resource set (CORESET)) of a physical control channel may be defined by a set of symbol periods and may extend across a system bandwidth or a subset of a system bandwidth of a carrier. One or more control regions (e.g., CORESETs) may be configured for a set of UEs 115. For example, one or more UEs in UE 115 may monitor or search a control region to obtain control information according to one or more search space sets, and each search space set may include one or more control channel candidates in one or more aggregation levels arranged in a cascaded manner. The aggregation level of a control channel candidate may refer to the amount of control channel resources (e.g., control channel elements (CCEs)) associated with coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for transmitting control information to multiple UEs 115 , and a UE-specific search space set for transmitting control information to a specific UE 115 .

[0080] 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 used to communicate with the network entity 105 (e.g., on a carrier) and may be associated with an identifier (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID), or other) used to distinguish adjacent cells. In some examples, a cell may also refer to a coverage area 110 or a portion of a coverage area 110 (e.g., a sector) on 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 may include a building, a subset of a building, or an external space between or overlapping coverage areas 110, as well as other examples.

[0081] A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access to UEs 115 that have service subscriptions with a network provider that supports the macro cell. A small cell may be associated with a lower power network entity 105 (e.g., a lower power base station 140) (compared to a macro cell), and the small cell may operate in the same or different (e.g., licensed, unlicensed) frequency band as the macro cell. A small cell may provide unrestricted access to UEs 115 that have service subscriptions with a network provider, or may provide restricted access to UEs 115 associated with a small cell (e.g., UEs 115 in a closed subscriber group (CSG), UEs 115 associated with users in a home or office). A network entity 105 may support one or more cells, and may also use one or more component carriers to support communications on one or more cells.

[0082] 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 to different types of devices.

[0083] In some examples, the network entities 105 (e.g., base stations 140, RUs 170) may be mobile and thus provide communication coverage for mobile coverage areas 110. In some examples, different coverage areas 110 associated with different technologies may overlap, but the different coverage areas 110 may be supported by the same network entity 105. In some other examples, overlapping coverage areas 110 associated with different technologies may be supported by different network entities 105. The wireless communication system 100 may include, for example, a heterogeneous network in which different types of network entities 105 provide coverage for various coverage areas 110 using the same or different radio access technologies.

[0084] The wireless communication system 100 may support synchronous 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 timing, and in some examples, transmissions from different network entities 105 may not be aligned in time. The techniques described herein may be used for either synchronous operation or asynchronous operation.

[0085] Some UEs 115, such as MTC or IoT devices, may be low-cost or low-complexity devices and may allow automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technology that allows devices to communicate with each other or with a network entity 105 (e.g., base station 140) without human intervention. In some examples, M2M communication or MTC may include communication from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application that utilizes the information or presents the information to a person interacting with the application. Some UEs 115 may be designed to collect information or implement automated behavior of machines or other devices. 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, fleet management and tracking, remote security sensing, physical access control, and transaction-based commercial charging.

[0086] Some UEs 115 may be configured to employ a reduced power consumption mode of operation, such as half-duplex communication (e.g., a mode that supports unidirectional communication via transmission or reception but does not transmit and receive concurrently). In some examples, half-duplex communication may be performed with a reduced peak rate. Other power saving techniques for UE 115 include entering a power saving deep sleep mode when not engaged in active communications, operating over a limited bandwidth (e.g., according to narrowband communications), or a combination of these techniques. For example, some UEs 115 may be configured to operate using a narrowband protocol type that is associated with a defined portion or range (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a guard band of a carrier, or outside a carrier.

[0087] The wireless communication system 100 may be configured to support ultra-reliable communication or low-latency communication or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low-latency communication (URLLC). The UE 115 may be designed to support ultra-reliable or low-latency or critical functions. Ultra-reliable communication may include private communication or group communication, and may be supported by one or more services (such as push-to-talk, video, or data). Support for ultra-reliable, low-latency functions may include prioritization of services, and such services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, and ultra-reliable low-latency are used interchangeably herein.

[0088] In some examples, a UE 115 may be able to communicate directly with other UEs 115 over a device-to-device (D2D) communication link 135 (e.g., according to a peer-to-peer (P2P), D2D, or sidelink protocol). In some examples, one or more UEs 115 in a group that are performing D2D communication may be within a coverage area 110 of a network entity 105 (e.g., a base station 140, a RU 170), which may support aspects of such D2D communication configured or scheduled by the network entity 105. In some examples, one or more UEs 115 in such a group may be outside the coverage area 110 of the network entity 105, or may otherwise be unable or not configured to receive transmissions from the network entity 105. In some examples, a group of UEs 115 communicating via D2D communication may support a one-to-many (1:M) system, in which each UE 115 transmits to each of the other UEs 115 in the group. In some examples, the network entity 105 may facilitate scheduling of resources for D2D communication. In some other examples, D2D communications may be performed between UEs 115 without involving network entity 105 .

[0089] In some systems, the D2D communication link 135 can be an example of a communication channel between vehicles (e.g., UE 115), such as a sidelink communication channel. In some examples, the vehicles can communicate using vehicle-to-everything (V2X) communications, vehicle-to-vehicle (V2V) communications, or some combination of these. The vehicles can signal information related to traffic conditions, signal scheduling, weather, safety, emergency situations, or any other information related to the V2X system. In some examples, vehicles in the V2X system can communicate with roadside infrastructure such as roadside units using vehicle-to-network (V2N) communications, or communicate with the network via one or more network nodes (e.g., network entity 105, base station 140, RU 170), or both.

[0090] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), which may include at least one control plane entity (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) for managing access and mobility and at least one user plane entity (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)) for routing packets or interconnecting to an external network. The control plane entity may manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management of UE 115 served by a network entity 105 (e.g., a base station 140) associated with the core network 130. User IP packets may be delivered through the user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to an IP service 150 for one or more network operators. IP services 150 may include access to the Internet, an intranet, an IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0091] 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 kilohertz (GHz). Generally speaking, the region from 300 MHz to 3 GHz is referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelength range is approximately 1 decimeter to 1 meter. UHF waves may be blocked or redirected by buildings and environmental features that may be referred to as clusters, but these waves may be sufficient to penetrate structures so that macro cells provide service to UEs 115 located indoors. Transmission of UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) than transmission using smaller frequencies and longer wavelengths of the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0092] The wireless communication system 100 may also operate in a super high frequency (SHF) region using a frequency band from 3 GHz to 30 GHz (also known as a centimeter band) or in an extremely high frequency (EHF) region of a spectrum (e.g., from 30 GHz to 300 GHz) (also known as a millimeter band). In some examples, the wireless communication system 100 may support millimeter wave (mmW) communications between a UE 115 and a network entity 105 (e.g., a base station 140, RU170), and the EHF antenna of the corresponding device may be smaller and closer than the UHF antenna. In some examples, this may facilitate the use of antenna arrays within the device. However, the propagation of EHF transmissions may be affected by greater atmospheric attenuation and a shorter range than SHF or UHF transmissions. The technology disclosed herein may be adopted across transmissions using one or more different frequency regions, and the use of frequency bands specified across these frequency regions may vary by country or regulatory agency.

[0093] The wireless communication system 100 may utilize licensed and unlicensed RF spectrum bands. For example, the wireless communication system 100 may use licensed assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in unlicensed bands such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in an unlicensed RF spectrum band, devices such as network entities 105 and UEs 115 may employ carrier sensing for conflict detection and avoidance. In some examples, operations in unlicensed bands may be based on carrier aggregation configurations (e.g., LAA) in conjunction with component carriers operating in licensed bands. Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, as well as other examples.

[0094] The network entity 105 (e.g., base station 140, RU 170) or UE 115 may be equipped with multiple antennas that can be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of the network entity 105 or UE 115 may be located within one or more antenna arrays or antenna panels that can support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, antennas or antenna arrays associated with the network entity 105 may be located at different geographical locations. The network entity 105 may have an antenna array having a set of rows and columns of antenna ports that the network entity 105 can use to support beamforming for communications with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support RF beamforming for signals sent via the antenna ports.

[0095] The network entity 105 or the UE 115 may use MIMO communication to utilize multipath signal propagation and improve spectral efficiency by sending or receiving multiple signals via different spatial layers. Such a technology may be referred to as spatial multiplexing. For example, multiple signals may be sent by a transmitting device via different antennas or different combinations of antennas. Similarly, multiple signals may be received by a receiving device via different antennas or different combinations of antennas. Each of the multiple 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 different data streams (e.g., different codewords). Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO technology includes single-user MIMO (SU-MIMO), in which multiple spatial layers are sent to the same receiving device, and multi-user MIMO (MU-MIMO), in which multiple spatial layers are sent to multiple devices.

[0096] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a network entity 105, a UE 115) to shape or direct an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining signals conveyed via antenna elements of an antenna array so that some signals propagating in a particular direction relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals conveyed via antenna elements may include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to signals carried via antenna elements associated with the device. Adjustments associated with each of these antenna elements may be defined by a set of beamforming weights associated with a particular direction (e.g., relative to the antenna array of the transmitting device or the receiving device or relative to some other direction).

[0097] The network entity 105 or UE 115 may use beam scanning techniques as part of a 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) to perform beamforming operations for directional communication with UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be sent multiple times by the network entity 105 along different directions. For example, the network entity 105 may send signals according to different sets of beamforming weights associated with different transmission directions. Transmission along different beam directions may be used to identify (e.g., by a transmitting device (such as network entity 105), or by a receiving device (such as UE 115)) the beam direction for later transmission or reception by the network entity 105.

[0098] Some signals (such as data signals associated with a particular receiving device) may be sent by a transmitting device (e.g., transmitting network entity 105, transmitting UE 115) along a single beam direction (e.g., a direction associated with a receiving device such as receiving network entity 105 or receiving UE 115). In some examples, a beam direction associated with transmission along a single beam direction may be determined based on signals sent along one or more beam directions. For example, UE 115 may receive one or more of the signals sent by network entity 105 along different directions, and may report to network entity 105 an indication of the signal received by UE 115 with the highest signal quality or other acceptable signal quality.

[0099] In some examples, transmission by a device (e.g., by 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 network entity 105 to UE 115). UE 115 may report feedback indicating precoding weights for one or more beam directions, and the feedback may correspond to a configured set of beams across a system bandwidth or one or more subbands. Network entity 105 may send a reference signal (e.g., a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS)), which may or may not be precoded. UE 115 may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-faceted codebook, a linear combination codebook, a port selection codebook). Although these techniques are described with reference to signals sent along one or more directions by a network entity 105 (e.g., base station 140, RU 170), UE 115 may use similar techniques to send signals multiple times along different directions (e.g., to identify a beam direction for subsequent transmission or reception by UE 115), or to send signals along a single direction (e.g., to send data to a receiving device).

[0100] A receiving device (e.g., UE 115) may perform receiving operations according to multiple receiving configurations (e.g., directional listening) when receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from a receiving device (e.g., network entity 105). For example, the receiving device may perform reception according to multiple receiving directions by: receiving via different antenna subarrays, processing the received signals according to different antenna subarrays, receiving according to different receiving beamforming weight sets (e.g., different directional listening weight sets) applied to signals received at multiple antenna elements of an antenna array, or processing the received signals according to different receiving beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as "listening" according to different receiving configurations or receiving directions. In some examples, the receiving device may use a single receiving configuration to receive along a single beam direction (e.g., when receiving a data signal). A 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).

[0101] The wireless communication system 100 may be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or PDCP layer may be IP-based. The RLC layer may perform packet segmentation and reassembly to communicate through logical channels. The MAC layer may perform priority handling and multiplexing of logical channels to transport channels. The MAC layer may also use error detection techniques, error correction techniques, or both to support retransmission at the MAC layer to improve link efficiency. In the control plane, the RRC protocol layer may provide the establishment, configuration, and maintenance of an RRC connection for a radio bearer that supports user plane data between the UE 115 and the network entity 105 or the core network 130. At the PHY layer, transport channels may be mapped to physical channels.

[0102] A UE 115 attempting to access a wireless network may perform an initial cell search by detecting a primary synchronization signal (PSS) from a network entity 105. The PSS may enable synchronization of time slot timing and may indicate a physical layer identification value. The UE 115 may then receive a secondary synchronization signal (SSS). The SSS may enable radio frame synchronization and may provide a cell identification value, which may be combined with a physical layer identification value to identify a cell. The SSS may also enable detection of a duplex mode and a cyclic prefix length. Some systems (such as TDD systems) may send an SSS but not a PSS. After receiving the PSS and SSS, the UE 115 may receive a master information block (MIB), which may be sent in a physical broadcast channel (PBCH). In some cases, the PSS, SSS, and PBCH may be received in a synchronization signal / PBCH block (SSB). The MIB may include system bandwidth information, SFN, and physical channel HARQ indicator channel (PHICH) configuration. After decoding the MIB, the UE 115 may receive one or more system information blocks (SIBs). For example, a first SIB (SIB1) may contain cell access parameters and scheduling information for other SIBs. Decoding SIB1 may enable UE 115 to receive a second SIB (SIB2). SIB2 may contain RRC configuration information related to random access channel (RACH) procedures, paging, physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), power control, sounding reference signal (SRS), and cell barring, among other examples.

[0103] In some cases, the wireless communication system 100 may include or support a network used for vehicle-based communications, also referred to as a V2X network, an enhanced V2X (eV2X) network, a V2V network, a cellular V2X (C-V2X) network, or other similar networks. The vehicle-based communication network may provide always-on telematics, where UEs (e.g., vehicle UEs (v-UEs)) communicate directly with the network (V2N), with pedestrian UEs (V2P), with infrastructure equipment (V2I), and with other v-UEs (e.g., via the network and / or directly). The vehicle-based communication network may support a safe, always-connected driving experience by providing intelligent connectivity in which traffic signals / timing, real-time traffic and routing, safety alerts for pedestrians / cyclists, collision avoidance information, etc. are exchanged.

[0104] The wireless communication system 100 may support D2D communication (e.g., including V2X communication). For example, the first UE 115 may communicate with the second UE 115 on a sidelink channel. In the sidelink communication, the first UE 115 may synchronize with the synchronization source (e.g., the second UE 115) before establishing a connection and communicating with the synchronization source (e.g., similar to the synchronization procedure implemented for communicating with the network entity 105). Therefore, for sidelink synchronization, the first UE 115 may receive a SLSS (such as a sidelink PSS (S-PSS) or a sidelink SSS (S-SSS)) and a physical sidelink broadcast channel (PSBCH), where the S-PSS, S-SSS, and PSBCH are received in a sidelink SSB (S-SSB). In some examples, the S-PSS and S-SSS may be collectively referred to as SLSS. In some cases, the PSBCH may be additionally referred to as SLSS.

[0105] In general, the synchronization source for the first UE 115 may include GNSS, a network entity 105 (e.g., an eNB, a gNB, or a component of the network entity 105), a synchronization reference UE (also referred to as a SyncRef UE), etc. The baseline synchronization source may include GNSS and network entity-based synchronization. Additionally or alternatively, the first UE 115 may include a UE capability to support S-SSB-based synchronization (e.g., with a SyncRef UE as a source). The first UE 115 may use a data-assisted / non-SSB-based synchronization mechanism, a synchronization SSB-based synchronization mechanism (e.g., an S-SSB search may be performed within a time window), or a combination thereof.

[0106] In some cases, synchronization based only on GNSS may not be sufficient or robust for different use cases or scenarios. For example, in V2X communication, the first UE 115 may be an example of a v-UE (such as an OBU) and may experience high mobility (e.g., if the v-UE is driving or otherwise moving). When the first UE 115 attempts to synchronize with GNSS, such as when the first UE 115 drives through a tunnel, enters a deep parking garage, etc., some scenarios may introduce difficulties, and the synchronization signals sent by the GNSS device may be unreliable. Additionally or alternatively, synchronization signals based on GNSS may be unavailable. In such a case, the first UE 115 may receive one or more synchronization signals (e.g., SLSS) from an independent synchronization source (such as a second UE 115) via a side link channel. In some examples, the first UE 115 may receive additional synchronization signals (e.g., SLSS) from additional independent synchronization sources (e.g., additional UEs 115).

[0107] Depending on the context, different synchronization sources may be more appropriate than other synchronization sources. For example, an RSU may provide increased reliability for synchronization with a first UE 115 in a local area of ​​the RSU. However, if the first UE 115 moves outside the local area, the RSU may no longer be used as a synchronization source. Alternatively, depending on the mobility of the first UE 115, the mobility of the OBU may be higher than that of the RSU, which may result in unstable or otherwise inconsistent synchronization. However, in some V2X scenarios, the first UE 115 may synchronize with the OBU in order to communicate directly with the OBU, for example, the RSU may not be sufficient to enable communication between the first UE 115 and the OBU.

[0108] In some examples, the first UE 115 may select a synchronization source to use as a reference for synchronization based on a priority scheme. For example, a synchronization source may be associated with a priority value or a priority group. The priority value may indicate the priority of the synchronization source as an independent synchronization source. Multiple priority groups may be defined based on the number of hops away from a direct synchronization source (such as a GNSS device). As the number of hops away from the GNSS increases, the quality of synchronization provided by the synchronization source decreases. Therefore, a device that is directly synchronized to the GNSS may be associated with a relatively higher priority group than a device that is one or more hops away from the GNSS.

[0109] According to the techniques described herein, the first UE 115 may select a synchronization source (e.g., an independent synchronization source, which may also be referred to herein as an independent synchronization source) based on the device type of the synchronization source, which may be indicated as part of one or more SLSSs. For example, the synchronization source may select one or more bits to include in a sidelink MIB (SL-MIB) associated with the device type. In some examples, the synchronization source may select an SLSSID included in the SLSS corresponding to the device type, and the first UE 115 may determine the device type based on the SLSSID. In some cases, as part of the SLSS, the synchronization source may also indicate a priority for a packet (e.g., a data packet) to be sent by the synchronization source, and the first UE 115 may select the synchronization source based on the indicated priority.

[0110] In addition, if the first UE 115 receives multiple SLSSs from multiple independent synchronization sources, the first UE 115 may select from the multiple independent synchronization sources based on the following: corresponding device type, corresponding priority value or priority group, device type of the first UE 115, deployment scenario of the first UE 115, indicated group priority, etc., as well as other examples. In any case, the first UE 115 may synchronize with the selected synchronization source based on the corresponding received SLSS, so that the communication between the first UE 115 and the selected synchronization source is aligned in timing.

[0111] The techniques described herein also support scenarios in which a synchronization source, such as a second UE 115, may determine to activate or deactivate an independent synchronization source mode, for example, based on one or more conditions being satisfied. For example, the second UE 115 may activate the independent synchronization source mode based on the deployment scenario of the second UE 115, the packet priority of packets sent by the second UE 115, one or more supported applications of the second UE 115, or a combination thereof, as well as other examples.

[0112] Figure 2 An example of a wireless communication system 200 that supports source-based synchronization for wireless devices according to one or more aspects of the present disclosure is illustrated. In some examples, the wireless communication system 200 can implement aspects of the wireless communication system 100. The wireless communication system 200 may include a UE 115, which may be a wireless device as described above with reference to FIG. Figure 1 The wireless communication system 200 may also include a GNSS satellite 205, which may be an example of a GNSS device operating as a GNSS-based synchronization source. In some examples, the wireless communication system 200 may be an example of a V2X system (such as an LTE V2X system), and the UE 115 may be an example of an OSU, an RSU, or other V2X device or a combination thereof. In addition, the UE 115 operating as a synchronization source may be referred to as a SyncRef UE.

[0113] The wireless communication system 200 may illustrate an example of a synchronization chain, where a UE 115 may receive synchronization signals (e.g., SLSS) from other UEs 115 or GNSS satellites 205. A UE 115 in the wireless communication system 200 may obtain synchronization information (e.g., S-PSS, S-SSS, PSBCH, S-SSB, etc.) to synchronize with the GNSS to support efficient and reliable communication with other devices in the wireless communication system 200. The UE 115 may select a synchronization source from which to obtain synchronization information (e.g., synchronization signals) to operate as a reference for synchronization based on one or more priority groups, which may correspond to the reliability of the synchronization source. For example, the UE 115 may synchronize with the GNSS directly or indirectly. Direct synchronization may refer to synchronization with a GNSS device (such as a GNSS satellite 205) operating as a synchronization source. Indirect synchronization may refer to synchronization with a device that in turn synchronizes directly with the GNSS. That is, a device synchronized with the GNSS may act as a synchronization source by broadcasting GNSS-based synchronization signals to other devices so that the other devices may synchronize with the GNSS without having a direct connection to the GNSS device.

[0114] A synchronization source may be considered to be in GNSS coverage if it has a direct connection to the GNSS or is synchronized to a second synchronization source which in turn has a direct connection to the GNSS (e.g., if the synchronization source is synchronized to a second synchronization source that is in coverage). A synchronization source may be considered to be out of GNSS coverage if it is synchronized to a second synchronization source that is out of GNSS coverage.

[0115] In some cases, a device such as a SyncRef UE may operate as an independent synchronization source. Here, an independent synchronization source may be synchronized with an internal clock (e.g., its own internal clock) and may send synchronization signals that enable other devices to synchronize with the timing of the independent synchronization source. The independent synchronization source may not be synchronized with the GNSS and may not rely on the GNSS for timing. Therefore, an independent synchronization source may be considered to be outside of GNSS coverage.

[0116] A synchronization source (e.g., a device operating as a synchronization source) may belong to a priority group depending on the level of indirect synchronization, e.g., based on the number of communication links over which a synchronization signal from a GNSS device may propagate before reaching a receiving device that uses the synchronization signal to perform synchronization. Direct synchronization may be associated with an increased reliability of the synchronization reference, and reliability may decrease as the number of communication links increases. Thus, a synchronization source that provides direct GNSS synchronization (e.g., in the coverage of the GNSS) may belong to a higher priority group than a synchronization source that provides indirect GNSS synchronization. Additionally, an independent synchronization source may belong to a lower priority group than a synchronization source that is directly connected to the GNSS.

[0117] exist Figure 2 , GNSS satellites 205 and UEs 115 may be associated with a corresponding number of priority groups based on a “hop” from the GNSS in the synchronization chain. As the most direct GNSS synchronization source, GNSS satellite 205 may belong to the highest priority group, such as priority group 1. For example, UE 115-a at the first hop may belong to priority group 2 based on UE 115-a having a direct connection to GNSS satellite 205. UE 115-b may belong to priority group 3 based on UE 115-b being at the second hop in the synchronization chain. UE 115-c and UE 115-e may both belong to the lowest priority group, such as priority group 4. Here, UE 115-c belongs to priority group 4 based on UE 115-c being at the third hop in the synchronization chain, and UE 115-e belongs to priority group 4 based on UE 115-e operating as an independent synchronization source.

[0118] UE 115 may select a synchronization source based on the priority (e.g., priority group) of the synchronization source to use as a reference for synchronization. In addition, according to the techniques described herein, UE 115 may select a synchronization source based on the device type of the synchronization source. For example, a synchronization source such as an independent synchronization source may be an RSU, an OBU, or another V2X device. An RSU operating as an independent synchronization source may be more suitable for some synchronization scenarios than an OBU, while an OBU may be an appropriate independent synchronization source in other synchronization scenarios. In some examples, an independent synchronization source may be associated with a priority (e.g., a priority value) indicating that the independent synchronization source serves as a reference for synchronization.

[0119] The synchronization signal (e.g., one or more synchronization signals) sent by the synchronization source may indicate synchronization information associated with or based on the priority group of the synchronization source, the device type associated with the synchronization source, etc., as well as other examples. For example, the SyncRef UE may send one or more SLSSs, such as one or more PSSs, SSSs, PSBCHs, or a combination thereof. The one or more SLSSs may include a SLSS ID and an indicator field in coverage (e.g., inCoverage). In some cases, the SLSS ID and inCoverage may be carried on the PSBCH, such as in the sidelink MIB or SSB transmission of the SyncRef UE. In some examples, the synchronization signal may be generated based on the selected SLSS ID. In some cases, the synchronization signal may additionally indicate the type of synchronization, such as GNSS-based synchronization (e.g., typeSync=GNSS), the subframe source used to send / receive the synchronization signal (e.g., the first source or the second source in the subframe, such as source-1 or source-2), etc., as well as other examples.

[0120] For a SyncRefUE that is synchronized with a GNSS (e.g., directly or indirectly), the value of the inCoverage bit field may indicate whether the SyncRef UE is within GNSS coverage (or, in some cases, within the coverage of a network entity). For example, inCoverage=0 (e.g., inCoverage=false) may indicate that the SyncRef UE is not in the coverage of the GNSS, while inCoverage=1 (e.g., inCoverage=true) may indicate that the SyncRef UE is in the coverage of the GNSS.

[0121] A SyncRef UE as an independent synchronization source may always be considered to be out of GNSS coverage (e.g., in Coverage = false). Therefore, the independent synchronization source may reuse the in Coverage bit field to indicate the device type of the independent synchronization source. For example, a first value of the inCoverage bit field (e.g., in Coverage = 1 or in Coverage = true) may correspond to a first device type, such as an RSU, while a second value of the inCoverage bit field (e.g., inCoverage = 0 or inCoverage = false) may correspond to a second device type, such as an OBU. The independent synchronization source may select a bit for the inCoverage bit field of the SLSS that corresponds to the device type of the independent synchronization source.

[0122] The SLSSID may indicate the synchronization source of the SyncRef UE. For example, some SLSSIDs may be reserved for SyncRef UEs in GNSS coverage. SLSSID=0 may be used by a SyncRef UE synchronized to GNSS or another SyncRef UE that synchronizes to GNSS itself. Other SLSS IDs may be reserved for SyncRef UEs outside of GNSS coverage, and still other SLSS IDs may be reserved for independent synchronization sources. In addition, the SLSS IDs reserved for independent synchronization sources may also be used to indicate the device type of the independent synchronization source.

[0123] For example, a SyncRef UE in the coverage of a GNSS satellite 205 may randomly select a SLSS ID from a first set of IDs (e.g., 0 to 167) for synchronization sources in GNSS coverage. A SyncRef UE outside the coverage of a GNSS satellite 205 may randomly select a SLSS ID from a second set of IDs for synchronization sources outside GNSS coverage. Additionally or alternatively, a SyncRef UE as an independent synchronization source may randomly select a SLSSID from a subset of SLSSIDs (e.g., 170 to 335) corresponding to a device type associated with the SyncRef UE. For example, a first subset of SLSS IDs (e.g., 170 to 252) may be reserved for RSUs, and a second subset of SLSS IDs (e.g., 253 to 335) may be reserved for OBUs. An RSU as an independent synchronization source may randomly select a SLSS ID from the first subset, and an OBU as an independent synchronization source may randomly select a SLSSID from the second subset.

[0124] In some cases, a SyncRef UE operating as an independent synchronization source may indicate the device type of the SyncRef UE via one or more reserved bits of a sidelink MIB associated with the SLSS. For example, the sidelink MIB may include a bit field for the number of reserved bits (e.g., 27), which the SyncRef UE may use to indicate the device type. A first value of one or more of the reserved bits may correspond to an RSU, a second value may correspond to an OBU, and so on. In some examples, the first value and the second value to be used for the corresponding device type may be indicated in a system information block (SIB) (e.g., to the SyncRef UE), may be RRC configured, or may be pre-configured.

[0125] The receiving device may select the synchronization source based on an indication included in a synchronization signal from the synchronization source. For example, when the synchronization source is synchronized to GNSS, the UE 115 receiving the synchronization signal from the synchronization source may determine the priority (e.g., priority level, priority group) of the synchronization source based on the SLSSID and inCoverage. In some examples, the synchronization source may additionally or alternatively send an indication of the priority to the UE 115. The UE 115 may select the synchronization source as a reference for synchronization based on the determined priority. For example, the UE 115 may receive multiple synchronization signals from multiple synchronization sources, and may select the synchronization source with the highest priority indicated by the corresponding synchronization signal.

[0126] When the synchronization source is an independent synchronization source, the UE 115 receiving the synchronization signal may determine the device type of the independent synchronization source based on the following: SLSS ID, the value of inCoverage, the value of one or more reserved bits, the priority indicating that the independent synchronization source acts as an independent synchronization source, or a combination thereof. For example, the UE 115 may receive multiple synchronization signals from multiple independent synchronization sources and may distinguish between independent synchronization sources based on the corresponding indicated device types. The UE 115 may select an independent synchronization source as a reference for synchronization based on the device type (e.g., based on an indication of the device type).

[0127] exist Figure 2In an example of , the wireless communication system 200 may include UEs 115 that synchronize to a GNSS and UEs 115 that operate as or synchronize to an independent synchronization source. For example, a UE 115-a may be able to communicate directly with a GNSS satellite 205, for example, and may be in GNSS coverage. The GNSS satellite 205 may therefore belong to priority group 1 because the GNSS satellite 205 provides a direct source for synchronization with the GNSS. Thus, the UE 115-a may select the GNSS satellite 205 over other indirect synchronization sources (such as other UEs 115 belonging to other priority groups) when available. For example, the UE 115-a may select the GNSS satellite 205 as a synchronization source and may synchronize directly with the GNSS by receiving a synchronization signal 210 from the GNSS satellite 205.

[0128] UE 115-a may become a synchronization reference (e.g., SyncRefUE) for additional UEs 115. As the first hop in the synchronization chain, UE 115-a may belong to priority group 2. Here, the synchronization signal 215-a sent by UE 115-a may include inCoverage=true (e.g., inCoverage=1) and SLSS ID=0, indicating that UE 115-a is in coverage of GNSS satellites 205 (e.g., inCoverage=1) and is directly synchronized to GNSS satellites 205 (e.g., SLSS ID=0). When a connection to GNSS satellites 205 is not available, UE 115 (such as UE 115-b) may select UE 115-a as a reference for synchronization (e.g., a synchronization source) based on the fact that UE 115-a has a direct connection to GNSS satellites 205. For example, UE 115-b may receive synchronization signal 215-a from UE 115-a and may determine that UE 115-a is associated with priority group 2 based on inCoverage=true and SLSSID=0. UE 115-b may synchronize and communicate with UE 115-a based on synchronization signal 215-a.

[0129] UE 115-b may also become a reference for synchronization (e.g., a SyncRef UE) for additional UEs 115 (such as UE 115-c). UE 115-b may be located at the second hop of the synchronization chain, where a synchronization signal from a GNSS satellite 205 may be propagated to UE 115-b via two communication links (e.g., as synchronization signal 210 and synchronization signal 215-a). Therefore, UE 115-b may belong to priority group 3, and synchronization signal 215-b may indicate inCoverage=false (e.g., inCoverage=0) and SLSS ID=0. UE 115-c may receive synchronization signal 215-b, and may synchronize and communicate with UE 115-b. In addition, UE 115-c may also become a SyncRef UE for UE 115-d and any other UE 115. That is, UE 115-c may send synchronization signal 215-c based on GNSS timing from UE 115-a relayed by UE 115-b. Based on the position of UE 115-c in the synchronization chain, for example, at the third hop, UE 115-c may belong to priority group 4, and synchronization signal 215-c may indicate inCoverage=false (e.g., inCoverage=0). In addition, synchronization signal 215-c may indicate the SLSSID corresponding to the SyncRef UE that is out of coverage. UE 115-d may synchronize with UE 115-c based on synchronization signal 215-c.

[0130] exist Figure 2 In the example of , UE 115-e and UE 115-f may belong to group 220, which may also be referred to as a cluster. Clusters may be formed for a synchronization source based on different UEs connected to the same synchronization source via SLSS sent by the synchronization source. Additionally or alternatively, UEs may join a cluster based on deployment scenarios, synchronization sources, etc. For example, vehicle UEs that are close to each other may form a cluster to communicate with other vehicle UEs in the cluster, and synchronization with the same synchronization source may enable communication between the vehicle UEs.

[0131] UE 115-e may be an example of a SyncRef UE that acts as an independent synchronization source, for example, according to an independent synchronization source mode. Figure 3In more detail, UE 115-e may determine to operate as an independent synchronization source based on the following: the deployment scenario of UE 115-e, the priority of the data packets to be sent by UE 115-e, one or more applications supported by UE 115-e, etc. Additionally or alternatively, UE 115-e may become an independent synchronization source when GNSS satellite 205 (e.g., direct or indirect synchronization signals from the GNSS) is not available or unavailable. For example, some V2X scenarios (such as communication between UE 115-e and UE 115-f in group 220) may not require GNSS synchronization. For example, as long as UE 115-e and UE 115-f are synchronized with each other, groupcast or unicast transmission between UE 115-e and UE 115-f can be successful.

[0132] As an independent synchronization source, UE 115-e may belong to priority group 4. Priority group 4 may correspond to UE 115 acting as an independent synchronization source and to UE 115 synchronized with an independent synchronization source. For example, a UE 115 acting as an independent synchronization source (such as UE 115-e) may synchronize with its own internal clock and may belong to priority group 4. In addition, UE 115-f may be an example of a UE 115 synchronized with UE 115-e, which in turn synchronizes to its own internal clock. That is, UE 115-e may not be synchronized with GNSS satellites 205 and may be considered to be out of GNSS coverage; UE 115-e may also not receive synchronization signals 215 from any of UE 115-a, UE 115-b, UE 115-c, or UE 115-d. UE 115-e may send a synchronization signal 225 to UE 115-f that indicates that UE 115-e is operating as an independent synchronization source and indicates a device type associated with UE 115-e. For example, UE 115-e may be an example of an RSU and the device type of the RSU may be indicated via: a value of a bit in the inCoverage bit field corresponding to the RSU, an SLSSID reserved for the RSU, or one or more reserved bits with values ​​associated with the RSU, or a combination thereof.

[0133] UE 115-f may receive synchronization signal 225 and may identify or otherwise determine the device type of UE 115-e. UE 115-f may select UE 115-e as a reference for synchronization based on the following: synchronization signal 225, device type, deployment scenario of UE 115-f, one or more applications supported by UE 115-f, or a combination thereof and other examples. For example, an RSU may be a stationary device and may be limited or otherwise confined to a local area, but may provide more reliable or consistent synchronization than an OBU (which may be mobile). In addition, an RSU operating as an independent synchronization source may enable synchronization even in a scenario with increased latency or communication delay. Therefore, in some cases, UE 115-f may select UE 115-e based on the fact that UE 115-e is an RSU.

[0134] However, in some cases, an OBU may be more suitable as an independent synchronization source. For example, if UE 115-f is an RSU and UE 115-e is an OBU, synchronizing with UE 115-e may enable UE 115-f to expand its local coverage area as UE 115-e moves away from UE 115-f. Alternatively, if both UE 115-e and UE 115-f are OBUs, and UE 115-e is an OBU with which UE 115-f is attempting to communicate as part of a cluster or other group scenario (e.g., to enable local communication between a group of UEs 115), UE 115-f may select UE 115-e based on UE 115-e being an OBU.

[0135] Alternatively, in some examples, UE 115-f may refrain from selecting UE 115-e as a reference for synchronization based on device type, deployment scenario of UE 115-f, one or more applications supported by UE 115-f, etc. For example, UE 115-f may not select UE 115-e if UE 115-f is likely not to reside in a local area where UE 115-e, as an RSU, provides coverage. Similarly, UE 115-f may refrain from selecting an OBU as a synchronization source if UE 115-f is an RSU, and may not select UE 115-e if UE 115-e is an OBU.

[0136] In any case, based on selecting UE 115-e as an independent synchronization source, UE 115-f may synchronize with UE 115-e using synchronization signal 225. After synchronization, UE 115-f and UE 115-e may establish a communication link, such as a sidelink communication link, to communicate over.

[0137] In some examples, based on synchronization with UE 115-e, UE 115-f may act as a SyncRef UE for one or more other UEs 115. For example, UE 115-f may send one or more synchronization signals indicating that the timing of UE 115-f is based on UE 115-e as a reference for synchronization for UE 115-f. In other words, UE 115-f may send one or more synchronization signals indicating that UE 115-f is synchronized with an independent synchronization source (e.g., UE 115-e).

[0138] Figure 3 An example of a synchronization signal coverage 300 supporting source-based synchronization for a wireless device in accordance with one or more aspects of the present disclosure is illustrated. In some examples, the synchronization signal coverage 300 can implement aspects of the wireless communication systems 100 and / or 200. For example, the synchronization signal coverage 300 can illustrate example deployment scenarios for various types of transport UEs (such as RSUs 310 and OBUs 315) that can synchronize with an independent synchronization source or satellite 305, as described in reference to FIG. Figure 2 as described.

[0139] exist Figure 3 In the example of FIG. 3 , the RSUs 310 may be stationary devices distributed along the tunnel 307, such that RSU 310-a and RSU 310-f are located outside the tunnel 307 at either end, while RSU 310-b, RSU 310-c, RSU 310-d, and RSU 310-e may be located within the tunnel 307. Based on the locations of the RSUs 310, RSU 310-a and RSU 310-f may have direct connections to satellite 305-a and satellite 305-b, respectively, while RSU 310-b, RSU 310-c, RSU 310-d, and RSU 310-e may not be able to communicate directly with satellite 305. RSU 310-a may receive a synchronization signal 320-a from satellite 305-a and may be synchronized with satellite 305-a. RSU 310-f may receive synchronization signal 320-g from satellite 305-b for synchronization with satellite 305-b. RSU 310 within tunnel 307 may rely on RSU 310-a and / or RSU 310-f to receive synchronization signals 320-b, 320-c, 320-d, and 320-e. For example, RSU 310-a, RSU 310-f, or both may relay one or more synchronization signals 320 to RSU 310 within tunnel 307 so that RSU 310 within tunnel 307 may be indirectly synchronized with satellite 305-a or satellite 305-b.

[0140] OBU 315-a, OBU 315-b, and OBU 315-c may be examples of mobile vehicle UEs driving through tunnel 307. In some examples, OBU 315 may be in a queue, and data may be periodically exchanged to enable dynamic management and operation of OBU 315 in the queue. For example, OBU 315 may communicate to determine the location of each OBU 315 and coordinate maneuvers. To facilitate such operations, OBU 315 may be synchronized with each other via synchronization signals 325-a and 325-b, so that the timing of communication between OBU 315 has high reliability (e.g., reliability above a threshold) and low latency (e.g., latency target below a threshold).

[0141] Figure 3 Various scenarios may be illustrated in which a UE (such as RSU 310 or OBU 315) may activate the independent synchronization source mode to operate as an independent synchronization source. Figure 3 The independent synchronization source in the example may support the use of SLSS for synchronization between UEs, especially when GNSS connection is unavailable or unreliable. A UE receiving SLSS from one or more independent synchronization source modes may select an independent synchronization source as a reference for synchronization based on the following: the device type of the independent synchronization source (e.g., associated with the independent synchronization source), the device type of the UE receiving the SLSS, or a combination thereof, as well as other examples.

[0142] For example, activation of the independent synchronization source mode by the UE may depend on satisfying one or more conditions associated with the UE, which in turn may depend on the device type of the UE. That is, the RSU 310 may activate the independent synchronization source mode in a different scenario or based on different conditions than the OBU 315. In addition, the UE may deactivate the independent synchronization source mode based on whether one or more other UEs associated with the corresponding device type are operating as independent synchronization sources.

[0143] The OBU 315 may activate the independent synchronization source mode based on one or more supported applications of the OBU 315. Figure 3 In an example of, the queue OBU 315 may form a cluster (e.g., a local synchronization cluster) and may communicate via multicast. The OBU 315 may support one or more applications associated with the queue arrangement and based on the cluster. The leading OBU 315 (such as OBU 315-c) may activate the independent synchronization source mode based on determining that the one or more applications meet one or more conditions associated with the OBU 315-c. The OBU 315-c may send a synchronization signal 325-b to the OBU 315-b. The synchronization signal 325-b may indicate the type of device associated with the OBU 315-c (e.g., OBU) and may indicate that the OBU 315-c is working as a reference for synchronization.

[0144] For example, as referenced Figure 2 As described, OBU 315-c may select one or more bits for the side link MIB based on the device type for the synchronization signal 325-b, such as one or more reserved bits, or one or more bits of a bit field for indicating the coverage state (e.g., inCoverage). Additionally or alternatively, OBU 315-c may select a first identifier from a set of identifiers (e.g., SLSS ID) associated with an independent synchronization source mode and corresponding to the device type. In some examples, a first identifier set associated with an independent synchronization source (e.g., outside the coverage of a GNSS) may be divided into identifier subsets, each of which may correspond to a device type. Here, OBU 315-c may select a first identifier from a subset corresponding to the OBU. Upon receiving the synchronization signal 325-b, OBU 315-b may select OBU 315-c as a reference for synchronization based on the synchronization signal 325-b and the device type of OBU 315-c.

[0145] In another example, if OBU 315-c has important data (e.g., high priority packets) to be sent to another device, OBU 315-c may activate independent synchronization source mode. For example, OBU 315-c may be an example of an emergency vehicle or an emergency vehicle, and may accordingly become an independent synchronization source. OBU 315-c may determine to meet one or more conditions associated with OBU 315-c based on the priority of the packet to be sent by OBU 315-c. In such examples, OBU 315-c may indicate the priority of the packet in synchronization signal 325 (e.g., synchronization signal 325-b or 325-c). In some cases, synchronization signal 325 (e.g., synchronization signal 325-b or 325-c) may also indicate the priority of the packet to be received by another UE, for example, based on the device type of the receiving UE. For example, if the packet relates to a maneuver to be performed by an OBU 315-c on a road in a tunnel 307, the packet may have a relatively high priority associated with being received by other OBUs 315 on the road (e.g., so that other OBUs 315 may avoid OBU 315-c), and may have a relatively low priority associated with being received by an RSU 310 located within the tunnel 307 (e.g., because the RSU 310 may be stationary). Furthermore, the packet may have an even lower relative priority associated with being received by an RSU 310 outside the tunnel 307, because the maneuver performed by the OBU 315-c within the tunnel 307 may be irrelevant to the RSU 310 outside the tunnel 307.

[0146] When OBU 315-c has a high priority packet to send, OBU 315, RSU 310, or both may select OBU 315-c as an independent synchronization source, for example, based on an indication of the packet priority in a synchronization signal 325 (e.g., synchronization signal 325-b or 325-c) sent by OBU 315-c. Synchronizing with OBU 315-c may enable OBU 315, RSU 310, or both to receive the high priority packet.

[0147] In some cases, OBU 315 may activate independent synchronization source mode based on whether one or more other devices (e.g., associated with the corresponding device type) also work as independent synchronization sources. For example, OBU 315-c may determine or otherwise select a time window with a random duration in which other synchronization signals are monitored. If OBU 315-c does not detect any synchronization signal from any other synchronization source during the time window, OBU 315-c may activate independent synchronization source mode. However, if OBU 315-c receives a synchronization signal (such as synchronization signal 325-c), OBU 315-c may suppress activation of independent synchronization source mode to avoid conflicts or congestion caused by several independent synchronization sources working at once.

[0148] In addition, the OBU 315 operating as an independent synchronization source may deactivate the independent synchronization source mode based on detecting a synchronization signal from another independent synchronization source. In some cases, the OBU 315 may deactivate the independent synchronization source mode based on the device type associated with the other independent synchronization source, the device type of the OBU 315, etc., as well as other examples. For example, after the OBU 315-c has activated the independent synchronization source mode, the OBU 315-c may receive a synchronization signal 325-c from the RSU 310-f. According to the techniques described herein, the synchronization signal 325-c may indicate the device type associated with the RSU 310-f (e.g., RSU). Based on the RSU 310-f being associated with the RSU device type, the OBU 315-c may deactivate the independent synchronization source mode. That is, the RSU may generally be associated with a relatively high reliability as a reference for synchronization, or in a Figure 3 In the example of , RSU 310 - f may be synchronized directly to satellite 305 - b , which may provide improved accuracy for synchronization.

[0149] In some cases, an OBU 315 (such as OBU 315-c) working as an independent synchronization source may receive a synchronization signal from a device associated with the same device type as OBU315-c (e.g., from another OBU 315). For example, OBU 315-c may receive a synchronization signal 325-b from OBU 315-b. In such a case, OBU 315-c may determine whether to deactivate the independent synchronization source mode by applying a rule that may be based on SLSSID. As a non-limiting example, OBU 315-c may compare the SLSSID of OBU315-c with the SLSSID associated with OBU 315-b, for example, indicated by synchronization signal 325-b. The rule may prioritize the smaller or larger values ​​of SLSSID. For example, an OBU 315 associated with a relatively large value of SLSSID may be a preferred independent synchronization source, for example, an OBU 315 with a larger SLSSID value may be prioritized by other OBUs 315 based on the rule. If OBU 315-c determines that the SLSSID of OBU 315-b is greater than the SLSSID of OBU 315-c, OBU 315-c may deactivate the independent synchronization source mode. In contrast, if OBU 315-c determines that the SLSSID of OBU 315-b is less than the SLSSID of OBU 315-c, OBU 315-c may maintain the independent synchronization source mode (e.g., the independent synchronization source mode may not be deactivated). Other examples of rules or rule combinations may be applied to support determining whether OBU 315 deactivates the independent synchronization source mode.

[0150] In some examples, similar rules may be applied to the receiving OBU 315 to select an independent synchronization source, for example, based on receiving a synchronization signal. For example, when the receiving OBU 315 receives multiple synchronization signals (e.g., synchronization signal 325) from multiple independent synchronization sources of the same device type, the OBU 315 may prioritize or otherwise distinguish between the multiple independent synchronization sources based on the rule. Figure 3In an example of, OBU 315-b (e.g., when not operating as an independent synchronization source) may receive synchronization signal 325-b from OBU 315-c (e.g., operating as an independent synchronization source) and receive synchronization signal 325-a from OBU 315-a (e.g., operating as an independent synchronization source). OBU 315-b may compare the value of the SLSSID associated with OBU 315-a (e.g., indicated in synchronization signal 325-a) with the value of the SLSSID associated with OBU 315-c (e.g., indicated in synchronization signal 325-c). The SLSSID associated with OBU 315-c may have a greater value than the SLSSID associated with OBU 315-a. OBU 315-b may select OBU 315-c as a reference for synchronization based on the comparison and according to the rule. If the OBU 315-b receives multiple synchronization signals from multiple RSUs 310, the OBU 315-b may apply the same procedure (eg, comparison and rule), for example, to select an RSU 310 as a reference for synchronization.

[0151] The RSU 310 may be associated with one or more conditions for determining whether to activate the independent synchronization source mode, which may be the same as or different from the one or more conditions associated with the OBU 315. For example, the RSU 310 may activate the independent synchronization source mode based on one or more supported applications of the RSU 310. Figure 3 In the example of , the RSU 310 within the tunnel 307 may support a different set of applications than the RSU 310 outside the tunnel 307. The applications supported by the RSU 310 within the tunnel 307 may not satisfy the one or more conditions, while the applications supported by the RSU 310 outside the tunnel 307 may satisfy the one or more conditions. Therefore, the RSU 310-f may, for example, activate the independent synchronization source mode based on determining that the one or more applications satisfy one or more conditions associated with the RSU 310-f. The RSU 310-f may send a synchronization signal 325-c to the OBU 315-c, send a synchronization signal 320-f to the RSU 310-e, or both based on activating the independent synchronization source mode. The synchronization signal 325-c and the synchronization signal 320-f may indicate a device type (e.g., RSU) associated with the RSU 310-f and may indicate that the RSU 310-f is operating as a reference for synchronization.

[0152] For example, as referenced Figure 2As described, the RSU 310-f may select one or more bits for the sidelink MIB, such as one or more reserved bits, or one or more bits of a bit field for indicating coverage status (e.g., inCoverage), for the synchronization signal 325-c and the synchronization signal 320-f based on the device type (e.g., RSU). Additionally or alternatively, the RSU 310-f may select a first identifier from a set of identifiers (e.g., SLSSID) associated with an independent synchronization source mode and corresponding to a device type. In some examples, the first set of identifiers associated with an independent synchronization source (e.g., outside the coverage of a GNSS) may be divided into subsets of identifiers, each of which may correspond to a device type. Here, the RSU 310-f may select a first identifier from a subset corresponding to the RSU. Upon receiving the synchronization signal 325-c, the OBU 315-c may select the RSU 310-f as a reference for synchronization based on the synchronization signal 325-c and the device type of the RSU 310-f. Additionally or alternatively, the RSU 310-e may select the RSU 310-f as a reference for synchronization based on the synchronization signal 320-f and the device type of the RSU 310-f.

[0153] In another example, if the RSU 310-f has important data (e.g., a high priority packet) to be sent to another device, the RSU 310-f may activate the independent synchronization source mode. For example, the RSU 310-f may be an example of an emergency device or may have information related to an emergency situation to be sent to other devices, and may become an independent synchronization source accordingly. The RSU 310-f may determine that one or more conditions associated with the RSU 310-f are satisfied based on the priority of the packet for transmission by the RSU 310-f. In such examples, the RSU 310-f may indicate the priority of the packet in the synchronization signal 320 or the synchronization signal 325. In some cases, the synchronization signal 320 or the synchronization signal 325 may also indicate the device priority of the packet to be received by another UE, for example, corresponding to the device type (RSU, OBU, etc.) of the receiving UE.

[0154] When the RSU 310-f has a high priority packet to send, the OBU 315, the RSU 310, or both may select the RSU 310-f as an independent synchronization source, for example, based on the packet priority and / or an indication of the device priority for the packet in the synchronization signal 320 or the synchronization signal 325 sent by the RSU 310-f. Synchronizing with the RSU 310-f may enable the OBU 315, the RSU 310, or both to receive the high priority packet.

[0155] The RSU 310 may activate the independent synchronization source mode based on the deployment scenario of the RSU 310. Some deployment scenarios may provide a more reliable or more accurate reference for synchronization than other deployment scenarios. For example, an RSU 310 deployed in a tunnel 307 may not be an independent synchronization source because indirect synchronization with a satellite 305-a or a satellite 305-b via other RSUs 310 may support improved performance compared to an RSU 310 acting as an independent synchronization source. For another example, the RSU 310 may be deployed in a parking garage, and the independent synchronization source mode may be activated to provide local synchronization to an OBU 315. Here, an OBU 315 located in the parking garage may synchronize with the RSU 310 to support communication with other local OBUs 315, and in some cases (e.g., for an underground parking garage or a large parking garage), it may not be possible to access a GNSS-based synchronization signal.

[0156] The RSU 310 may activate the independent synchronization source mode based on whether one or more other devices (eg, associated with the corresponding device type) are also operating as independent synchronization sources. Figure 3 In an example of , RSU 310-f may receive synchronization signal 320-f from RSU 310-e and may receive synchronization signal 325-c from OBU 315-c. RSU 310-f may refrain from activating independent synchronization source mode based on detecting one or both of synchronization signals 320-f and 325-c, for example, to avoid congestion associated with multiple devices operating as independent synchronization sources. In some examples, RSU 310-f may refrain from activating independent synchronization source mode based on a device type of the independent synchronization source associated with the synchronization signal (e.g., based on an indication of the device type in the synchronization signal). For example, RSU 310-f may refrain from activating the independent synchronization source based on the synchronization signal 320-f indicating a device type associated with RSU 310-e (e.g., based on receiving a synchronization signal from another RSU), but may continue to activate the independent synchronization source mode if RSU 310-f receives a synchronization signal from an OBU.

[0157] In some cases, an RSU 310 (such as RSU 310-f) that has activated the independent synchronization source mode may determine to deactivate the independent synchronization source mode based on receiving a synchronization signal from a device associated with the same device type as the RSU 310-f (e.g., from another RSU 310). For example, the RSU 310-f may receive a synchronization signal 320-f from the RSU 310-e. In such a case, the RSU 310-f may determine whether to deactivate the independent synchronization source mode by applying a rule that may be based on the SLSSID. As a non-limiting example, the RSU 310-f may compare the SLSSID of the RSU 310-f with the SLSSID associated with the RSU 310-e, for example, as indicated by the synchronization signal 320-f. The rule may prioritize smaller or larger values ​​of the SLSSID. For example, an RSU 310 associated with a relatively large value of SLSSID may be a preferred independent synchronization source, e.g., an RSU 310 with a larger SLSSID value may be prioritized by other RSUs 310 based on the rule. If RSU 310-f determines that the SLSSID of RSU 310-e is greater than the SLSSID of RSU 310-f, RSU 310-f may deactivate the independent synchronization source mode. In contrast, if RSU 310-f determines that the SLSSID of RSU 310-e is less than the SLSSID of RSU 310-f, RSU 310-f may maintain the independent synchronization source mode (e.g., the independent synchronization source mode may not be deactivated). Other examples of rules or rule combinations may be applied to support determining whether RSU 310 deactivates the independent synchronization source mode.

[0158] In some examples, similar rules may be applied to the receiving RSU 310 to select an independent synchronization source as a reference for synchronization, for example, based on receiving a synchronization signal. For example, when the receiving RSU 310 receives multiple synchronization signals (e.g., synchronization signal 320) from multiple independent synchronization sources of the same device type, the RSU 310 may prioritize or otherwise distinguish between the multiple independent synchronization sources based on the rule. Figure 3In an example of , RSU 310-e (e.g., when not operating as an independent synchronization source) may receive synchronization signal 320-f from RSU 310-f (e.g., operating as an independent synchronization source) and receive synchronization signal 320-e from RSU 310-d (e.g., operating as an independent synchronization source). RSU 310-e may compare the value of the SLSSID associated with RSU 310-f (e.g., indicated in synchronization signal 320-f) with the value of the SLSSID associated with RSU 310-d (e.g., indicated in synchronization signal 320-e). The SLSSID associated with RSU 310-f may have a greater value than the SLSSID associated with RSU 310-d. RSU 310-e may select RSU 310-f as a reference for synchronization based on the comparison and according to the rule.

[0159] Generally speaking, a UE (such as an OBU 315 or an RSU 310) receiving a synchronization signal from an independent synchronization source may select an independent synchronization source as a reference for synchronization based on the device type of the independent synchronization source. For example, generally speaking, a UE may prioritize the selection of an RSU (such as an RSU 310) over the selection of an OBU (such as an OBU 315) as a synchronization reference. In addition, although an OBU 315 may select an RSU 310 or another OBU 315 as an independent synchronization source, an RSU 310 may only select another RSU 310 and may not select an OBU 315 as an independent synchronization source. However, any rule or priority ordering may be overcome by the priority of the packet to be sent by the independent synchronization source. That is, if the synchronization signal sent by the independent synchronization source indicates a sufficiently high priority (e.g., such that the priority satisfies a threshold) for the packet sent by the independent synchronization source, the RSU 310, the OBU 315, or both may select the independent synchronization source, regardless of the device type associated with the independent synchronization source.

[0160] Figure 4 An example of a process flow 400 for supporting source-based synchronization for wireless devices in accordance with one or more aspects of the present disclosure is illustrated. In some examples, the process flow 400 can implement aspects of the wireless communication systems 100 and / or 200. The process flow 400 can include a device 405-a, a device 405-b, and a device 405-c, which can be as described herein. Figures 1 to 3Examples of UEs described herein. For example, device 405-a, device 405-b, and device 405-c may each be associated with a corresponding device type, such as an RSU, an OBU, etc., as well as other example devices (e.g., V2X devices). As described herein, device 405-a may attempt to synchronize and communicate with an independent synchronization source in a wireless communication system (such as a V2X system). Devices 405-b and 405-c may be examples of independent synchronization sources and may send one or more synchronization signals to device 405-a.

[0161] In the following description of process flow 400, operations between devices 405 may be sent in a different order than shown, or operations performed by devices 405 may be performed in a different order or at a different time. Some operations may also be omitted from process flow 400, or other operations may be added to process flow 400. It should be understood that although device 405 is shown as performing several operations of process flow 400, any wireless device may perform the operations shown.

[0162] At 410, device 405-b may activate an independent synchronization source mode based on one or more conditions associated with device 405-b being satisfied. Independent synchronization source mode may correspond to device 405-b operating as a reference for synchronization. For example, the one or more conditions may be satisfied based on a deployment scenario of device 405-b, such as when device 405-b is an RSU. Additionally or alternatively, device 405-b may determine one or more applications supported by device 405-b, and the one or more conditions may be satisfied based on the one or more applications being supported by device 405-b.

[0163] In some cases, the one or more conditions may be satisfied based on a priority of a packet for transmission by the device 405-b.The device 405-b may determine a priority of the packet and may determine that the one or more conditions are satisfied based on the priority of the packet.

[0164] In some examples, the one or more conditions may be satisfied based on device 405-b monitoring one or more other synchronization signals and failing to detect any other synchronization signals during the monitoring period. For example, device 405-b may monitor the second synchronization signal for a time period (e.g., having a randomly selected duration). If device 405-b does not detect the second synchronization signal (e.g., or any other synchronization signal) within the time period, device 405-b may activate independent synchronization source mode. In other words, device 405-b may activate independent synchronization source mode based on the absence of the second synchronization signal during the monitoring period (e.g., within the time period).

[0165] At 415, the device 405-b may select one or more bits to include in the synchronization signal. In some examples, the synchronization signal may include multiple synchronization signals, such as multiple SLSS, sidelink PSS, sidelink SSS, PSBCH, or a combination thereof. The synchronization signal may include a bit field (e.g., inCoverage) for indicating the coverage state of the device 405-b, and the device 405-b may select one or more bits of the bit field for indicating the coverage state based on the device type (e.g., RSU, OBU) associated with the device 405-b and the independent synchronization source mode. The one or more bits may indicate or otherwise correspond to the device type associated with the device 405-b. For example, a bit value of 0 may correspond to an OBU device type, and a bit value of 1 may correspond to an RSU device type. If the device 405-b is an OBU, the device 405-b may select one or more bits with a bit value of 0 to indicate the OBU device type; if the device 405-b is an RSU, the device 405-b may select one or more bits with a bit value of 1 to indicate the RSU device type. In some cases, the one or more bits may also indicate that device 405 - b is operating as a reference for synchronization.

[0166] Additionally or alternatively, the synchronization signal may include a sidelink MIB, and the device 405-b may select one or more bits for the sidelink MIB (e.g., one or more reserved bits of the sidelink MIB) based on the device type associated with the device 405-b and the independent synchronization source mode. The one or more bits of the sidelink MIB may indicate the device type and may indicate that the device 405-b is operating as a reference for synchronization. For example, the device 405-b may receive an RRC message, a SIB, etc., which indicates one or more bit values ​​to be used for one or more bits corresponding to the device type associated with the device 405-b. In some cases, the device 405-b may be pre-configured with one or more bit values ​​corresponding to the device type.

[0167] In some cases, such as when the device 405-b activates the independent synchronization source mode based on the priority of the packet, the device 405-b may select one or more bits of the reserved bit field for inclusion in the synchronization signal based on the priority of the packet. For example, the device 405-b may select the one or more bits so that the one or more bits indicate the priority of the packet. In addition, at least one of the one or more bits may indicate a device priority for the packet, where the device priority may correspond to a device type of the receiving device. The device priority may, for example, correspond to an RSU (e.g., a receiving RSU), an OBU (e.g., a receiving OBU), or both.

[0168] At 420, device 405-b may select a first identifier from a set of identifiers associated with an independent synchronization source mode. The set of identifiers may correspond to a device type associated with device 405-b. For example, device 405-b may be an example of an RSU, and the first identifier may be randomly selected from a set of identifiers corresponding to the RSU. Device 405-b may alternatively be an example of an OBU, and the first identifier may be randomly selected from a set of identifiers corresponding to the OBU. Device 405-b may generate a synchronization signal based on the first identifier. The first identifier (and the set of identifiers) may be an example of a SLSSID.

[0169] At 425, device 405-b may send one or more synchronization signals, and device 405-a may receive the one or more synchronization signals, which may include examples of SLSS, PSS, SSS, PSBCH, etc., as well as other examples or examples of SLSS, PSS, SSS, PSBCH, etc., as well as other examples. For example, the synchronization signal may be an example of SLSS, and in some cases may include both PSS and SSS. The synchronization signal may indicate a device type associated with device 405-b, and may indicate that device 405-b is operating as a reference for synchronization. For example, the synchronization signal may be generated based on an SLSS ID (e.g., selected at 420) corresponding to a device type associated with device 405-b. Additionally or alternatively, based on selecting one or more bits at 415, the synchronization signal may include a bit field (e.g., inCoverage) for indicating a coverage state of device 405-b, wherein one or more bits of the bit field selected at 415 indicate a device type associated with device 405-b. Additionally or alternatively, the synchronization signal may include one or more reserved bits, such as one or more bits of the sidelink MIB selected by the device 405-b at 415, which may indicate a device type associated with the device 405-b. In some examples, one or more of the reserved bits may indicate a priority of the packet, such as a device priority of the packet for the RSU, the OBU, or both.

[0170] In some examples, the synchronization signal may indicate a priority of device 405-b. The priority of device 405-b may indicate or be associated with the priority of device 405-b acting as an independent synchronization source. Alternatively, the priority of device 405-b may indicate or be associated with a priority group associated with device 405-b (e.g., a priority group to which device 405-b belongs).

[0171] At 430, device 405-c may send a second one or more synchronization signals, and device 405-a may receive the second one or more synchronization signals, which may include SLSS, PSS, SSS, PSBCH, etc., as well as other examples. For example, the synchronization signal may be an example of SLSS, and in some cases may include both PSS and SSS. Device 405-b may also receive a second one or more synchronization signals from device 405-c. The second synchronization signal may indicate a device type associated with device 405-c, and may indicate that device 405-c is operating as a second reference for synchronization. For example, the second synchronization signal may be generated based on a second SLSS ID associated with an independent synchronization source mode. The second SLSSID may be associated with an identifier set corresponding to a device type associated with device 405-c. If the device type associated with device 405-c is the same as the device type associated with device 405-b, the first SLSSID and the second SLSSID may be associated with the same identifier set. Alternatively, the first SLSS ID and the second SLSS ID may each be associated with a corresponding identifier set. For example, a first SLSS ID may be associated with a first set of identifiers corresponding to a device type associated with device 405 - b , and a second SLSS ID may be associated with a second set of identifiers corresponding to a device type associated with device 405 - c .

[0172] Additionally or alternatively, the second synchronization signal may include a bit field (e.g., inCoverage) for indicating the coverage status of device 405-c, wherein one or more bits of the bit field indicate a device type associated with device 405-c and indicate that device 405-c is operating as a second reference for synchronization. Additionally or alternatively, the second synchronization signal may include one or more reserved bits, such as one or more bits of a sidelink MIB, which may indicate a device type associated with device 405-c and indicate that device 405-c is operating as a second reference for synchronization. In some examples, one or more of the reserved bits may indicate a priority for packets sent by device 405-c, such as a device priority for packets for RSUs, OBUs, or both.

[0173] In some examples, the synchronization signal may indicate a priority of device 405-c. The priority of device 405-c may indicate or be associated with a priority of device 405-c acting as an independent synchronization source. Alternatively, the priority of device 405-c may indicate or be associated with a priority group associated with device 405-c (e.g., a priority group to which device 405-c belongs).

[0174] At 435, device 405-a may determine a first priority for a first packet to be sent by device 405-b based on the synchronization signal received at 425 (e.g., based on one or more bits included in the synchronization signal received at 425). Device 405-a may also determine a second priority for a second packet to be sent by device 405-c based on the synchronization signal received at 430 (e.g., based on one or more bits included in the second synchronization signal received at 430). In some cases, device 405-a may determine the device priority for the first packet, the device priority for the second packet, or both based on a device type associated with device 405-a. For example, if device 405-a is an RSU, device 405-a may determine the device priority based on an indication of a device priority for a packet corresponding to the RSU (e.g., in the synchronization signal).

[0175] At 440, device 405-b may determine the device type associated with device 405-c, for example, based on the indication included in the second synchronization signal. For example, device 405-b may determine the device type associated with device 405-c based on one or more reserved bits (e.g., of the sidelink MIB) corresponding to the device type, one or more bits of a bit field for indicating the coverage state of device 405-c (e.g., inCoverage), a second SLSSID associated with the second synchronization signal, or a combination thereof.

[0176] At 445, device 405-a may determine a device type associated with device 405-b, for example, based on an indication included in the synchronization signal. Additionally, if device 405-a receives a second synchronization signal at 430, device 405-a may determine a device type associated with device 405-c, for example, based on an indication included in the second synchronization signal. For example, device 405-a may determine a device type associated with device 405-b based on one or more reserved bits (e.g., of a sidelink MIB) that correspond to the device type and are indicated by the synchronization signal, one or more bits of a bit field for indicating a coverage state of device 405-b in the synchronization signal (e.g., inCoverage), a first SLSS ID associated with the synchronization signal, or a combination thereof. Device 405-a can determine the device type associated with device 405-c based on: one or more reserved bits (e.g., of the side link MIB) corresponding to the device type and indicated by the second synchronization signal, one or more bits of a bit field for indicating the coverage status of device 405-c in the second synchronization signal (e.g., inCoverage), a second SLSSID associated with the second synchronization signal, or a combination thereof.

[0177] In some examples, the device type associated with device 405-b and the device type associated with device 405-c may be the same. In other examples, the device type associated with device 405-b may be different from the device type associated with device 405-c.

[0178] At 450, device 405-b may compare an identifier of device 405-c (e.g., corresponding to a device type associated with device 405-c) and an identifier of device 405-b (e.g., corresponding to a device type associated with device 405-b). For example, device 405-b may compare a first SLSS ID (e.g., selected at 420) with a second SLSS ID (e.g., indicated by the second synchronization signal).

[0179] At 455, device 405-a may compare an identifier of device 405-c (e.g., indicated in the second synchronization signal) with an identifier of device 405-b (e.g., indicated in the first synchronization signal). For example, device 405-a may compare a first SLSS ID (e.g., indicated by the synchronization signal) with a second SLSS ID (e.g., indicated by the second synchronization signal).

[0180] At 460, the device 405-b may optionally determine to deactivate the independent synchronization source mode. For example, the device 405-b may deactivate the independent synchronization source mode based on receiving the second synchronization signal at 430. Additionally or alternatively, the device 405-b may deactivate the independent synchronization source mode based on the device type determined at 440, the comparison of the identifiers at 450, etc., as well as other examples.

[0181] For example, if the device type associated with device 405-b and the device type associated with device 405-c are the same, device 405-b may compare the first SLSS ID and the second SLSSID at 450, and may deactivate the independent synchronization source mode based on a rule associated with the comparison. As a specific non-limiting example, if the second SLSS ID is greater than the first SLSSID, device 405-b may deactivate the independent synchronization source mode. Alternatively, if the device type associated with device 405-b and the device type associated with device 405-c are different, device 405-b may deactivate the independent synchronization source mode based on the device type of device 405-c and, in some cases, the device type of device 405-b. For example, if device 405-b is an OSU, device 405-b may deactivate the independent synchronization source mode based on the fact that device 405-c is an RSU.

[0182] In some cases, device 405-b may refrain from deactivating the independent synchronization source mode based on the device type associated with device 405-b and, in some examples, the device type associated with device 405-c at 460. For example, if device 405-b is an RSU, device 405-b may refrain from deactivating the independent synchronization source mode based on device 405-c being an OBU.

[0183] At 465, device 405-a may select device 405-c as a reference for synchronization, for example, based on the second synchronization signal received at 430, the packet priority determined at 435, the identifier compared at 455, the device type determined at 445, etc., as well as other examples. For example, device 405-a may select device 405-c as a reference for synchronization based on the second SLSSID, one or more bits of the sidelink MIB sent as part of the second synchronization signal, one or more bits of a bit field for indicating the coverage status of device 405-c, a priority of a packet to be sent by device 405-c, etc. In some cases, device 405-a may select device 405-c as a reference for synchronization based on a device type associated with device 405-c and, in some examples, based on a device type associated with device 405-a. Additionally or alternatively, device 405-a may select device 405-c based on an indication of the priority of device 405-c and an indication of the priority of device 405-b. For example, device 405-a may select device 405-c if the corresponding priority is relatively higher than the priority corresponding to device 405-b.

[0184] In some cases, device 405 - a may select device 405 - c as a reference for synchronization based on the deployment type of device 405 - a , one or more applications supported by device 405 - a , or a combination thereof, among other examples.

[0185] At 470 , device 405 - a may synchronize with device 405 - c based on the second synchronization signal.

[0186] Figure 5 A block diagram 500 of a device 505 supporting source-based synchronization for a wireless device according to one or more aspects of the present disclosure is shown. The device 505 may be an example of aspects of a UE 115 as described herein. The device 505 may include a receiver 510, a transmitter 515, and a communication manager 520. The device 505 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0187] Receiver 510 may provide means for receiving information, such as packets associated with various information channels (e.g., control channels, data channels, information channels related to source-based synchronization for wireless devices), user data, control information, or any combination thereof. The information may be communicated to other components of device 505. Receiver 510 may utilize a single antenna or a collection of multiple antennas.

[0188] The transmitter 515 may provide means for transmitting signals generated by other components of the device 505. For example, the transmitter 515 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to source-based synchronization for wireless devices), user data, control information, or any combination thereof. In some examples, the transmitter 515 may be co-located with the receiver 510 in a transceiver module. The transmitter 515 may utilize a single antenna or a collection of multiple antennas.

[0189] The communication manager 520, the receiver 510, the transmitter 515, or various combinations thereof or various components thereof may be examples of means for performing various aspects of source-based synchronization for wireless devices as described herein. For example, the communication manager 520, the receiver 510, the transmitter 515, or various combinations thereof or components thereof may support methods for performing one or more of the functions described herein.

[0190] In some examples, the communication manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be implemented in hardware (e.g., in a communication management circuit). The hardware may include a processor, a digital signal processor (DSP), a central processing unit (CPU), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a microcontroller, discrete gate or transistor logic components, discrete hardware components, or any combination thereof that is configured as or otherwise supports components for performing the functions described herein. In some examples, the processor and a memory coupled to the processor may be configured to perform one or more of the functions described herein (e.g., by executing instructions stored in the memory by the processor).

[0191] Additionally or alternatively, in some examples, the communication manager 520, the receiver 510, the transmitter 515, or various combinations or components thereof may be implemented in code executed by a processor (e.g., as communication management software or firmware). If implemented in code executed by a processor, the functionality of the communication manager 520, the receiver 510, the transmitter 515, 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 functionality described in the present disclosure), a DSP, a CPU, an ASIC, an FPGA, a microcontroller, or any combination of these or other programmable logic devices.

[0192] In some examples, communication manager 520 may be configured to perform various operations (e.g., receive, obtain, monitor, output, send) using or otherwise cooperating with receiver 510, transmitter 515, or both. For example, communication manager 520 may receive information from receiver 510, transmit information to transmitter 515, or be integrated with receiver 510, transmitter 515, or both to obtain information, output information, or perform various other operations as described herein.

[0193] According to examples as disclosed herein, the communication manager 520 may support wireless communications at a first wireless device. For example, the communication manager 520 may be configured to or otherwise support components for activating an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization. The communication manager 520 may be configured to or otherwise support components for sending one or more synchronization signals by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization.

[0194] Additionally or alternatively, the communication manager 520 may support wireless communication at the second wireless device according to examples as disclosed herein. For example, the communication manager 520 may be configured to or otherwise support components for receiving one or more synchronization signals from the first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization. The communication manager 520 may be configured to or otherwise support components for selecting the first wireless device as a reference for synchronization based on the one or more synchronization signals and the device type. The communication manager 520 may be configured to or otherwise support components for synchronizing with the first wireless device based on the selection.

[0195] By including or configuring the communication manager 520 according to the examples described herein, the device 505 (e.g., a processor that controls or otherwise couples with the receiver 510, the transmitter 515, the communication manager 520, or a combination thereof) can support techniques for source-based synchronization. For example, the device 505 can operate as an independent synchronization source and can send one or more synchronization signals that indicate the device type of the device 505 and indicate that the device 505 is operating as a reference for synchronization. The device 505 can dynamically activate or deactivate the independent synchronization source mode according to the techniques described herein, which can reduce power consumption and improve overall performance at the device 505. Alternatively, the device 505 can operate as a receiving device that can select an independent synchronization source based on its device type, which can improve communication efficiency, reduce conflicts and congestion, and improve resource utilization efficiency, among other examples.

[0196] Figure 6 A block diagram 600 of a device 605 supporting source-based synchronization for a wireless device according to one or more aspects of the present disclosure is shown. The device 605 may be an example of aspects of the device 505 or UE 115 as described herein. The device 605 may include a receiver 610, a transmitter 615, and a communication manager 620. The device 605 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

[0197] Receiver 610 may provide means for receiving information, such as packets associated with various information channels (e.g., control channels, data channels, information channels related to source-based synchronization for wireless devices), user data, control information, or any combination thereof. The information may be communicated to other components of device 605. Receiver 610 may utilize a single antenna or a collection of multiple antennas.

[0198] The transmitter 615 may provide means for transmitting signals generated by other components of the device 605. For example, the transmitter 615 may transmit information such as packets associated with various information channels (e.g., control channels, data channels, information channels related to source-based synchronization for wireless devices), user data, control information, or any combination thereof. In some examples, the transmitter 615 may be co-located with the receiver 610 in a transceiver module. The transmitter 615 may utilize a single antenna or a collection of multiple antennas.

[0199] Device 605 or its various components may be examples of components for performing various aspects of source-based synchronization for wireless devices as described herein. For example, communication manager 620 may include synchronization source component 625, synchronization signal transmitter 630, synchronization signal receiver 635, reference selection component 640, synchronization component 645, or any combination thereof. Communication manager 620 may be an example of various aspects of communication manager 520 as described herein. In some examples, communication manager 620 or its various components may be configured to use or otherwise cooperate with receiver 610, transmitter 615, or both to perform various operations (e.g., receive, obtain, monitor, output, send). For example, communication manager 620 may receive information from receiver 610, transmit information to transmitter 615, or be integrated with receiver 610, transmitter 615, or both to obtain information, output information, or perform various other operations as described herein.

[0200] According to examples as disclosed herein, the communication manager 620 may support wireless communications at the first wireless device. The synchronization source component 625 may be configured to or otherwise support means for activating an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization. The synchronization signal transmitter 630 may be configured to or otherwise support means for transmitting one or more synchronization signals by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization.

[0201] Additionally or alternatively, the communication manager 620 may support wireless communication at the second wireless device according to examples as disclosed herein. The synchronization signal receiver 635 may be configured to or otherwise support components for receiving one or more synchronization signals from the first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization. The reference selection component 640 may be configured to or otherwise support components for selecting the first wireless device as a reference for synchronization based on the one or more synchronization signals and the device type. The synchronization component 645 may be configured to or otherwise support components for synchronizing with the first wireless device based on the selection.

[0202] Figure 7A block diagram 700 of a communication manager 720 supporting source-based synchronization for a wireless device in accordance with one or more aspects of the present disclosure is shown. The communication manager 720 may be an example of aspects of the communication manager 520, the communication manager 620, or both as described herein. The communication manager 720 or its various components may be examples of components for performing various aspects of source-based synchronization for a wireless device as described herein. For example, the communication manager 720 may include a synchronization source component 725, a synchronization signal transmitter 730, a synchronization signal receiver 735, a reference selection component 740, a synchronization component 745, a priority component 750, a device type component 755, or any combination thereof. Each of these components may communicate directly or indirectly with each other (e.g., via one or more buses).

[0203] According to examples as disclosed herein, the communication manager 720 may support wireless communications at the first wireless device. The synchronization source component 725 may be configured to or otherwise support means for activating an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization. The synchronization signal transmitter 730 may be configured to or otherwise support means for transmitting one or more synchronization signals by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization.

[0204] In some examples, to support sending one or more synchronization signals, priority component 750 may be configured or otherwise support components for sending an indication of a priority of the first wireless device, indicating that the first wireless device is acting as an independent synchronization source or indicating a priority group associated with the first wireless device.

[0205] In some examples, the one or more synchronization signals include a bit field indicating a coverage status of the first wireless device, and the device type component 755 may be configured to or otherwise support components for selecting one or more bits of the bit field indicating the coverage status based on a device type associated with the first wireless device and an independent synchronization source mode, wherein the one or more bits indicate the device type associated with the first wireless device and indicate that the first wireless device is operating as a reference for synchronization.

[0206] In some examples, the one or more synchronization signals include a side link MIB, and the device type component 755 may be configured to or otherwise support components for selecting one or more bits for the side link MIB based on a device type associated with the first wireless device and an independent synchronization source mode, wherein the one or more bits indicate a device type associated with the first wireless device and indicate that the first wireless device is operating as a reference for synchronization.

[0207] In some examples, the device type component 755 can be configured to or otherwise support components for selecting a first identifier from a set of identifiers associated with an independent synchronization source mode, wherein the set of identifiers corresponds to a device type associated with the first wireless device. In some examples, the synchronization signal transmitter 730 can be configured to or otherwise support components for generating one or more synchronization signals based on the first identifier.

[0208] In some examples, the synchronization signal receiver 735 can be configured or otherwise support components for receiving a second one or more synchronization signals indicating a device type associated with the second wireless device. In some examples, the synchronization source component 725 can be configured or otherwise support components for deactivating an independent synchronization source mode for the first wireless device based on receiving the second one or more synchronization signals.

[0209] In some examples, the device type associated with the first wireless device and the device type associated with the second wireless device are the same device type, and the synchronization signal receiver 735 may be configured to or otherwise support components for receiving a second identifier corresponding to the device type associated with the second wireless device as part of a second one or more synchronization signals, wherein deactivation of the independent synchronization source mode for the first wireless device is based on a comparison of the first identifier and the second identifier.

[0210] In some examples, the device type associated with the first wireless device is different from the device type associated with the second wireless device, and the synchronization signal receiver 735 may be configured to or otherwise support components for receiving a second identifier corresponding to the device type associated with the second wireless device as part of a second one or more synchronization signals, wherein deactivation of the independent synchronization source mode for the first wireless device is based on the device type associated with the second wireless device.

[0211] In some examples, one or more conditions associated with the first wireless device are satisfied based on a deployment scenario of the first wireless device. In some examples, the first wireless device is an RSU.

[0212] In some examples, the synchronization source component 725 may be configured or otherwise support components for determining one or more applications supported by the first wireless device, where one or more conditions associated with the first wireless device are satisfied based on the one or more applications.

[0213] In some examples, the synchronization source component 725 may be configured or otherwise support means for determining that one or more conditions associated with the first wireless device are satisfied based on a priority of a packet for transmission by the first wireless device. In some examples, the one or more synchronization signals include a reserved bit field, and the synchronization source component 725 may be configured or otherwise support means for selecting one or more bits for the reserved bit field based on a priority of the packet, wherein the one or more bits indicate a priority of the packet. In some examples, at least one of the one or more bits indicates a device priority for the packet, the device priority corresponding to one or both of an RSU and an OBU.

[0214] In some examples, the synchronization signal receiver 735 may be configured as or otherwise support components for monitoring a second one or more synchronization signals from a second wireless device over a time period, wherein activation of the independent synchronization source mode is based on the absence of the second one or more synchronization signals during the monitoring over the time period.

[0215] In some examples, the one or more synchronization signals include a SLSS.In some examples, the first device type corresponds to an RSU and the second device type corresponds to an OBU.

[0216] Additionally or alternatively, the communication manager 720 may support wireless communication at the second wireless device according to examples as disclosed herein. The synchronization signal receiver 735 may be configured to or otherwise support components for receiving one or more synchronization signals from the first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization. The reference selection component 740 may be configured to or otherwise support components for selecting the first wireless device as a reference for synchronization based on the one or more synchronization signals and the device type. The synchronization component 745 may be configured to or otherwise support components for synchronizing with the first wireless device based on the selection.

[0217] In some examples, synchronization component 745 may be configured or otherwise support components for sending one or more synchronization signals indicating that the timing of the second wireless device is based on the first wireless device as a reference for synchronization for the second wireless device.

[0218] In some examples, the reference selection component 740 may be configured as or otherwise support components for receiving a bit field indicating a coverage status of a first wireless device as part of one or more synchronization signals, wherein one or more bits for the bit field indicate a device type associated with the first wireless device and indicate that the first wireless device is operating as a reference for synchronization, and wherein selection of the first wireless device as a reference for synchronization is based on the one or more bits.

[0219] In some examples, the reference selection component 740 may be configured as or otherwise support components for receiving a side link MIB as part of one or more synchronization signals, wherein one or more bits for the side link MIB indicate a device type associated with the first wireless device and indicate that the first wireless device is operating as a reference for synchronization, and wherein selection of the first wireless device as a reference for synchronization is based on the one or more bits.

[0220] In some examples, the reference selection component 740 may be configured to or otherwise support components for receiving a first identifier from a set of identifiers associated with an independent synchronization source mode as part of one or more synchronization signals, wherein the set of identifiers corresponds to a device type associated with a first wireless device, and wherein selection of the first wireless device as a reference for synchronization is based on the first identifier.

[0221] In some examples, the synchronization signal receiver 735 may be configured to or otherwise support components for receiving a second one or more synchronization signals that indicate a device type associated with a third wireless device and that the third wireless device is operating as a second reference for synchronization, wherein the second one or more synchronization signals include a second identifier from a set of identifiers associated with an independent synchronization source mode and corresponding to a device type associated with the third wireless device, wherein selecting the first wireless device as a reference for synchronization is based on a comparison of the first identifier and the second identifier.

[0222] In some examples, the device type associated with the first wireless device and the device type associated with the third wireless device are the same device type.

[0223] In some examples, to support selection of the first wireless device as a reference for synchronization, the reference selection component 740 may be configured to or otherwise support components for selecting the first wireless device based on a deployment scenario of the second wireless device, one or more applications supported by the second wireless device, or a combination thereof.

[0224] In some examples, selecting the first wireless device as a reference for synchronization is based on a device type associated with the first wireless device and a device type associated with the second wireless device.

[0225] In some examples, the priority component 750 may be configured to or otherwise support components for receiving a reserved bit field as part of one or more synchronization signals, wherein one or more bits for the reserved bit field indicate a priority of a packet for transmission by a first wireless device, and wherein selection of the first wireless device as a reference for synchronization is based on the priority of the packet.

[0226] In some examples, at least one of the one or more bits indicates a device priority for the packet, the device priority corresponding to one or both of the RSU and the OBU. In some examples, selecting the first wireless device as a reference for synchronization is based on the device priority.

[0227] In some examples, the one or more synchronization signals include a SLSS.In some examples, the first device type corresponds to an RSU and the second device type corresponds to an OBU.

[0228] Figure 8 A diagram of a system 800 including a device 805 supporting source-based synchronization for wireless devices according to one or more aspects of the present disclosure is shown. The device 805 may be an example of a device 505, a device 605, or a UE 115 as described herein, or include components thereof. The device 805 may communicate (e.g., wirelessly) with one or more network entities 105, one or more UEs 115, or any combination thereof. The device 805 may include components for two-way voice and data communications, including components for sending and receiving communications, such as a communication manager 820, an input / output (I / O) controller 810, a transceiver 815, an antenna 825, a memory 830, a code 835, and a processor 840. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., a bus 845).

[0229] I / O controller 810 can manage input signals and output signals of device 805. I / O controller 810 can also manage peripheral devices that are not integrated into device 805. In some cases, I / O controller 810 can represent a physical connection or port to an external peripheral device. In some cases, I / O controller 810 can utilize an operating system such as or another known operating system. Additionally or alternatively, I / O controller 810 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I / O controller 810 may be implemented as part of a processor such as processor 840. In some cases, a user may interact with device 805 via I / O controller 810 or via hardware components controlled by I / O controller 810.

[0230] In some cases, the device 805 may include a single antenna 825. However, in some other cases, the device 805 may have more than one antenna 825 that may be capable of concurrently transmitting or receiving multiple wireless transmissions. The transceiver 815 may communicate bidirectionally via one or more antennas 825, a wired link, or a wireless link as described herein. For example, the transceiver 815 may represent a wireless transceiver and may communicate bidirectionally with another wireless transceiver. The transceiver 815 may also include a modem for modulating packets, providing the modulated packets to one or more antennas 825 for transmission, and for demodulating packets received from one or more antennas 825. The transceiver 815 or the transceiver 815 and the one or more antennas 825 may be examples of transmitters 515, transmitters 615, receivers 510, receivers 610, or any combination thereof or components thereof as described herein.

[0231] The memory 830 may include random access memory (RAM) and read-only memory (ROM). The memory 830 may store computer-readable, computer-executable code 835 including instructions that, when executed by the processor 840, cause the device 805 to perform various functions described herein. The code 835 may be stored in a non-transitory computer-readable medium such as a system memory or another type of memory. In some cases, the code 835 may not be directly executable by the processor 840, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein. In some cases, among other things, the memory 830 may contain a basic I / O system (BIOS) that may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0232] The processor 840 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 840 may be configured to operate a memory array using a memory controller. In some other cases, the memory controller may be integrated into the processor 840. The processor 840 may be configured to execute computer-readable instructions stored in a memory (e.g., a memory 830) so that the device 805 performs various functions (e.g., functions or tasks that support source-based synchronization for wireless devices). For example, the device 805 or a component of the device 805 may include a processor 840 and a memory 830 coupled to or coupled to the processor 840, and the processor 840 and the memory 830 are configured to perform the various functions described herein.

[0233] According to examples as disclosed herein, the communication manager 820 may support wireless communications at a first wireless device. For example, the communication manager 820 may be configured to or otherwise support components for activating an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization. The communication manager 820 may be configured to or otherwise support components for sending one or more synchronization signals by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization.

[0234] Additionally or alternatively, the communication manager 820 may support wireless communication at the second wireless device according to examples as disclosed herein. For example, the communication manager 820 may be configured to or otherwise support components for receiving one or more synchronization signals from the first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization. The communication manager 820 may be configured to or otherwise support components for selecting the first wireless device as a reference for synchronization based on the one or more synchronization signals and the device type. The communication manager 820 may be configured to or otherwise support components for synchronizing with the first wireless device based on the selection.

[0235] By including or configuring the communication manager 820 according to the examples described herein, the device 805 can support techniques for source-based synchronization. For example, the device 805 can operate as an independent synchronization source and can send one or more synchronization signals, which indicate the device type of the device 805 and indicate that the device 805 is working as a reference for synchronization. The device 805 can dynamically activate or deactivate the independent synchronization source mode according to the techniques described herein, which can improve coordination between devices, increase communication reliability and reduce latency. Alternatively, the device 805 can operate as a receiving device, which can select an independent synchronization source based on the device type of the independent synchronization source, which can improve coordination between devices, increase communication reliability and reduce power consumption.

[0236] In some examples, the communication manager 820 may be configured to perform various operations (e.g., receive, monitor, transmit) using or otherwise cooperating with the transceiver 815, one or more antennas 825, or any combination thereof. Although the communication manager 820 is illustrated as a separate component, in some examples, one or more functions described with reference to the communication manager 820 may be supported or performed by the processor 840, the memory 830, the code 835, or any combination thereof. For example, the code 835 may include instructions that are executable by the processor 840 to cause the device 805 to perform various aspects of source-based synchronization for wireless devices as described herein, or the processor 840 and the memory 830 may be otherwise configured to perform or support such operations.

[0237] Fig. 9 A flow chart illustrating a method 900 for supporting source-based synchronization for a wireless device according to one or more aspects of the present disclosure is shown. The operations of the method 900 may be implemented by a UE or a component thereof as described herein. For example, the operations of the method 900 may be implemented by a UE or a component thereof as described in reference to Figures 1 to 8 The described UE 115 may be performed. In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the described functions.

[0238] At 905, the method may include: activating an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization. The operations of 905 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 905 may be performed as described in reference to Figure 7 The described synchronization source component 725 performs.

[0239] At 910, the method may include: sending, by a first wireless device operating in an independent synchronization source mode, one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization. The operations of 910 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 910 may be performed by reference to Figure 7 The described synchronization signal transmitter 730 is performed.

[0240] Fig.10 A flow chart illustrating a method 1000 for supporting source-based synchronization for a wireless device according to one or more aspects of the present disclosure is shown. The operations of the method 1000 may be implemented by a UE or a component thereof as described herein. For example, the operations of the method 1000 may be implemented by a UE or a component thereof as described in reference to Figures 1 to 8 The described UE 115 may be performed. In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the described functions.

[0241] At 1010, the method may include: activating an independent synchronization source mode for the first wireless device based on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization. The operations of 1010 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1010 may be performed by reference to Figure 7 The described synchronization source component 725 performs.

[0242] At 1015, the method may include: selecting a first identifier from a set of identifiers associated with an independent synchronization source mode, wherein the set of identifiers corresponds to a device type associated with the first wireless device. The operations of 1015 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1015 may be performed as described in reference to Figure 7 The device type component 755 described is executed.

[0243] At 1020, the method may include generating one or more synchronization signals based on the first identifier. The operations of 1020 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1020 may be performed as described in reference Figure 7 The described synchronization signal transmitter 730 is performed.

[0244] At 1025, the method may include: sending, by a first wireless device operating in an independent synchronization source mode, one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization. The operations of 1025 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1025 may be performed by reference to Figure 7 The described synchronization signal transmitter 730 is performed.

[0245] At 1030, the method may include receiving a second one or more synchronization signals indicating a device type associated with the second wireless device. The operations of 1030 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1030 may be performed as described in reference to Figure 7 The described synchronization signal receiver 735 is performed.

[0246] At 1035, the method may include: deactivating the independent synchronization source mode for the first wireless device based on receiving the second one or more synchronization signals. The operations of 1035 may be performed according to examples disclosed herein. In some examples, aspects of the operations of 1035 may be performed as described in reference Figure 7 The described synchronization source component 725 performs.

[0247] Fig.11 A flow chart illustrating a method 1100 for supporting source-based synchronization for a wireless device according to one or more aspects of the present disclosure is shown. The operations of the method 1100 may be implemented by a UE or a component thereof as described herein. For example, the operations of the method 1100 may be implemented by a UE or a component thereof as described in reference to Figures 1 to 8 The described UE 115 may be performed. In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the described functions.

[0248] At 1105, the method may include: receiving one or more synchronization signals from the first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization. The operations of 1105 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1105 may be performed by reference to Figure 7 The described synchronization signal receiver 735 is performed.

[0249] At 1110, the method may include selecting the first wireless device as a reference for synchronization based on the one or more synchronization signals and the device type. The operations of 1110 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1110 may be performed by reference to Figure 7 The described reference selection component 740 is executed.

[0250] At 1115, the method may include: synchronizing with the first wireless device based on the selection. The operations of 1115 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1115 may be performed as described in reference Figure 7 The described synchronization component 745 performs.

[0251] Fig.12 A flow chart illustrating a method 1200 for supporting source-based synchronization for a wireless device according to one or more aspects of the present disclosure is shown. The operations of the method 1200 may be implemented by a UE or a component thereof as described herein. For example, the operations of the method 1200 may be implemented by a UE or a component thereof as described in reference to Figures 1 to 8 The described UE 115 may be performed. In some examples, the UE may execute an instruction set to control the functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform various aspects of the described functions.

[0252] At 1205, the method may include: receiving one or more synchronization signals from the first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization. The operations of 1205 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1205 may be performed by reference to Figure 7 The described synchronization signal receiver 735 is performed.

[0253] At 1210, the method may include: receiving a reserved bit field as part of one or more synchronization signals, wherein one or more bits for the reserved bit field indicate a priority of a packet for transmission by the first wireless device. The operations of 1210 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1210 may be described with reference to Figure 7 The described priority component 750 is performed.

[0254] At 1215, the method may include: selecting the first wireless device as a reference for synchronization based on the one or more synchronization signals, the device type, and the priority of the group. The operations of 1215 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1215 may be performed by reference to Figure 7 The described reference selection component 740 is executed.

[0255] At 1220, the method may include: synchronizing with the first wireless device based on the selection. The operations of 1220 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1220 may be performed as described in reference to Figure 7 The described synchronization component 745 performs.

[0256] At 1225, the method may include sending one or more synchronization signals indicating that the timing of the second wireless device is based on the first wireless device as a reference for synchronization for the second wireless device. The operations of 1225 may be performed according to examples as disclosed herein. In some examples, aspects of the operations of 1225 may be performed as described in reference to Figure 7 The described synchronization component 745 performs.

[0257] The following provides an overview of various aspects of the disclosure:

[0258] Aspect 1: A method for wireless communication at a first wireless device, the method comprising: activating an independent synchronization source mode for the first wireless device based at least in part on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization; and sending one or more synchronization signals by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as the reference for synchronization.

[0259] Aspect 2: A method according to aspect 1, wherein sending the one or more synchronization signals includes: sending an indication of a priority of the first wireless device, the priority indicating that the first wireless device acts as an independent synchronization source or indicating a priority group associated with the first wireless device.

[0260] Aspect 3: A method according to any one of Aspects 1 to 2, wherein the one or more synchronization signals include a bit field indicating the coverage status of the first wireless device, and the method further includes: selecting one or more bits of the bit field for indicating the coverage status based at least in part on the device type associated with the first wireless device and the independent synchronization source mode, wherein the one or more bits indicate the device type associated with the first wireless device and indicate that the first wireless device is operating as the reference for synchronization.

[0261] Aspect 4: A method according to any one of Aspects 1 to 3, wherein the one or more synchronization signals include a side link MIB, and the method further includes: selecting one or more bits for the side link MIB based at least in part on the device type associated with the first wireless device and the independent synchronization source mode, wherein the one or more bits indicate the device type associated with the first wireless device and indicate that the first wireless device is operating as the reference for synchronization.

[0262] Aspect 5: According to the method described in any one of Aspects 1 to 4, the method also includes: selecting a first identifier from a set of identifiers associated with the independent synchronization source mode, wherein the set of identifiers corresponds to the device type associated with the first wireless device; and generating the one or more synchronization signals based at least in part on the first identifier.

[0263] Aspect 6: According to the method described in Aspect 5, the method also includes: receiving a second one or more synchronization signals, wherein the second one or more synchronization signals indicate a device type associated with a second wireless device; and deactivating the independent synchronization source mode for the first wireless device based at least in part on receiving the second one or more synchronization signals.

[0264] Aspect 7: A method according to Aspect 6, wherein the device type associated with the first wireless device and the device type associated with the second wireless device are the same device type, and the method further includes: receiving a second identifier corresponding to the device type associated with the second wireless device as part of the second one or more synchronization signals, wherein deactivating the independent synchronization source mode for the first wireless device is at least partially based on a comparison of the first identifier and the second identifier.

[0265] Aspect 8: A method according to any one of Aspects 6 to 7, wherein the device type associated with the first wireless device is different from the device type associated with the second wireless device, and the method further includes: receiving a second identifier corresponding to the device type associated with the second wireless device as part of the second one or more synchronization signals, wherein deactivating the independent synchronization source mode for the first wireless device is at least partially based on the device type associated with the second wireless device.

[0266] Aspect 9: The method according to any one of aspects 1 to 8, wherein the one or more conditions associated with the first wireless device are satisfied based at least in part on a deployment scenario of the first wireless device.

[0267] Aspect 10: The method according to aspect 9, wherein the first wireless device is a RSU.

[0268] Aspect 11: According to any one of Aspects 1 to 10, the method also includes: determining one or more applications supported by the first wireless device, wherein the one or more conditions associated with the first wireless device are satisfied at least in part based on the one or more applications.

[0269] Aspect 12: The method according to any one of aspects 1 to 11, the method further comprising: determining that the one or more conditions associated with the first wireless device are satisfied based at least in part on a priority of a packet for transmission by the first wireless device.

[0270] Aspect 13: A method according to Aspect 12, wherein the one or more synchronization signals include a reserved bit field, and the method further comprises: selecting one or more bits for the reserved bit field based at least in part on the priority of the packet, wherein the one or more bits indicate the priority of the packet.

[0271] Aspect 14: The method according to aspect 13, wherein at least one of the one or more bits indicates a device priority for the packet, the device priority corresponding to one or both of an RSU and an OBU.

[0272] Aspect 15: According to any one of Aspects 1 to 14, the method further includes: monitoring a second one or more synchronization signals from a second wireless device within a time period, wherein activating the independent synchronization source mode is at least partially based on the absence of the second one or more synchronization signals during the monitoring within the time period.

[0273] Aspect 16: The method according to any one of aspects 1 to 15, wherein the one or more synchronization signals include SLSS.

[0274] Aspect 17: The method according to any one of aspects 1 to 16, wherein the first device type corresponds to an RSU, and the second device type corresponds to an OBU.

[0275] Aspect 18: A method for wireless communication at a second wireless device, the method comprising: receiving one or more synchronization signals from a first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization; selecting the first wireless device as the reference for synchronization based at least in part on the one or more synchronization signals and the device type; and synchronizing with the first wireless device based at least in part on the selection.

[0276] Aspect 19: According to the method according to Aspect 18, the method also includes: sending one or more synchronization signals, wherein the one or more synchronization signals indicate that the timing of the second wireless device is at least partially based on the first wireless device as the reference for synchronization of the second wireless device.

[0277] Aspect 20: According to the method described in any one of Aspects 18 to 19, the method also includes: receiving a bit field indicating the coverage status of the first wireless device as part of the one or more synchronization signals, wherein one or more bits used for the bit field indicate the device type associated with the first wireless device and indicate that the first wireless device is operating as the reference for synchronization, and wherein selecting the first wireless device as the reference for synchronization is at least partially based on the one or more bits.

[0278] Aspect 21: According to the method described in any one of Aspects 18 to 20, the method also includes: receiving a side link MIB as part of the one or more synchronization signals, wherein one or more bits used for the side link MIB indicate the device type associated with the first wireless device and indicate that the first wireless device is operating as the reference for synchronization, and wherein selecting the first wireless device as the reference for synchronization is at least partially based on the one or more bits.

[0279] Aspect 22: According to the method described in any one of Aspects 18 to 21, the method also includes: receiving a first identifier from a set of identifiers associated with an independent synchronization source mode as part of the one or more synchronization signals, wherein the set of identifiers corresponds to the device type associated with the first wireless device, and wherein selecting the first wireless device as the reference for synchronization is at least partially based on the first identifier.

[0280] Aspect 23: According to the method of Aspect 22, the method also includes: receiving a second one or more synchronization signals, the second one or more synchronization signals indicating a device type associated with a third wireless device and indicating that the third wireless device is operating as a second reference for synchronization, wherein the second one or more synchronization signals include a second identifier from the set of identifiers associated with the independent synchronization source mode and corresponding to the device type associated with the third wireless device, wherein selecting the first wireless device as the reference for synchronization is at least partially based on a comparison of the first identifier and the second identifier.

[0281] Aspect 24: The method of aspect 23, wherein the device type associated with the first wireless device and the device type associated with the third wireless device are the same device type.

[0282] Aspect 25: A method according to any one of Aspects 18 to 24, wherein selecting the first wireless device as the reference for synchronization includes: selecting the first wireless device based at least in part on a deployment scenario of the second wireless device, one or more applications supported by the second wireless device, or a combination thereof.

[0283] Aspect 26: The method according to any one of aspects 18 to 25, wherein selecting the first wireless device as the reference for synchronization is based at least in part on the device type associated with the first wireless device and the device type associated with the second wireless device.

[0284] Aspect 27: According to any one of Aspects 18 to 26, the method further includes: receiving a reserved bit field as part of the one or more synchronization signals, wherein one or more bits used for the reserved bit field indicate a priority of a packet to be sent by the first wireless device, and wherein selecting the first wireless device as the reference for synchronization is at least partially based on the priority of the packet.

[0285] Aspect 28: A method according to Aspect 27, wherein at least one of the one or more bits indicates a device priority for the group, the device priority corresponds to one or both of the RSU and the OBU, and selecting the first wireless device as the reference for synchronization is at least partially based on the device priority.

[0286] Aspect 29: The method according to any one of aspects 18 to 28, wherein the one or more synchronization signals include SLSS.

[0287] Aspect 30: The method according to any one of aspects 18 to 29, wherein the first device type corresponds to an RSU and the second device type corresponds to an OBU.

[0288] Aspect 31: An apparatus for performing wireless communications at a first wireless device, 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 perform a method according to any one of Aspects 1 to 17.

[0289] Aspect 32: An apparatus for wireless communication at a first wireless device, the apparatus comprising at least one component for performing the method according to any one of aspects 1 to 17.

[0290] Aspect 33: A non-transitory computer-readable medium storing code for wireless communication at a first wireless device, the code comprising instructions executable by a processor to perform the method according to any one of aspects 1 to 17.

[0291] Aspect 34: An apparatus for wireless communication at a second wireless device, 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 perform a method according to any one of Aspects 18 to 30.

[0292] Aspect 35: An apparatus for wireless communication at a second wireless device, the apparatus comprising at least one component for performing the method according to any one of aspects 18 to 30.

[0293] Aspect 36: A non-transitory computer-readable medium storing code for wireless communication at a second wireless device, the code comprising instructions executable by a processor to perform the method according to any one of aspects 18 to 30.

[0294] It should be noted that the methods described herein describe possible implementations, and that the various operations and steps may be rearranged or otherwise modified and other implementations are possible. Furthermore, aspects from two or more methods may be combined in a method.

[0295] Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for example purposes, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein may also be applicable to networks other than LTE, LTE-A, LTE-A Pro, or NR networks. For example, the techniques described 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.

[0296] The information and signals described herein may be represented using any of a variety of different technologies and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be mentioned throughout the specification may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0297] The various illustrative blocks and components described in conjunction with the disclosure herein may be implemented or performed using a general purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic components, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0298] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. When implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on a computer-readable medium, or sent via a computer-readable medium. Other examples and specific 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, hard wiring, or any combination of these items. Features that implement the functions may also be physically located at different locations, including being distributed so that the functions are implemented at different physical locations.

[0299] Computer-readable medium includes both non-transient computer storage medium and communication medium, and it includes any medium that facilitates computer program to be transmitted from one place to another place.Non-transient storage medium can be any available medium that can be accessed by general or special-purpose computer.By way of example and not limitation, non-transient computer-readable medium can include RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disc (CD) ROM or other optical disc storage device, disk storage device or other magnetic storage device, or can be used for carrying or storing desired program code parts and can be accessed by general or special-purpose computer or general or special-purpose processor in the form of instruction or data structure Any other non-transient medium.In addition, any connection is appropriately referred to as computer-readable medium.For example, if software is sent from website, server or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technology such as infrared, radio and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, includes CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0300] As used herein (including in the claims), "or" used in a list of items (e.g., a list of items followed by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, so that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). In addition, as used herein, the phrase "based on" should not be interpreted as a reference to a closed set of conditions. For example, an example step described as "based on condition A" can be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on."

[0301] The terms "determine" or "determining" encompass a variety of actions, and thus, "determining" may include calculating, computing, processing, deriving, investigating, looking up (such as via looking up in a table, database or other data structure), ascertaining, and similar actions. Additionally, "determining" may include receiving (such as receiving information), accessing (such as accessing data in a memory), and similar actions. Additionally, "determining" may include resolving, obtaining, selecting, choosing, establishing, and other such similar actions.

[0302] In the drawings, similar components or features may have the same reference label. In addition, various components of the same type may be distinguished by following the reference label with a dash and a second label to distinguish between similar components. If only the first reference label is used in the specification, the description may apply to any of the similar components having the same first reference label regardless of the second reference label, or other subsequent reference labels.

[0303] The descriptions set forth herein in conjunction with the accompanying drawings describe example configurations and do not represent all examples that may be implemented or within the scope of the claims. The term "example" as used herein means "used as an example, instance, or illustration," rather than "preferred" or "advantageous over other examples." The detailed description includes specific details for providing an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0304] The description herein is provided to enable one of ordinary skill in the art to implement or use the present disclosure. Various modifications to the present disclosure will be apparent to one of ordinary skill in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a first wireless device, the method include: activating an independent synchronization source mode for the first wireless device based at least in part on one or more conditions associated with the first wireless device being satisfied, wherein the independent synchronization source mode corresponds to the first wireless device operating as a reference for synchronization; as well as One or more synchronization signals are sent by the first wireless device operating in the independent synchronization source mode, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as the reference for synchronization.

2. The method of claim 1, wherein sending the one or more synchronization signals include: An indication of a priority of the first wireless device is transmitted, the priority indicating that the first wireless device acts as an independent synchronization source or indicating a priority group associated with the first wireless device.

3. The method of claim 1 , wherein the one or more synchronization signals include a bit field indicating a coverage status of the first wireless device, the method further comprising: include: One or more bits of the bit field for indicating the coverage status are selected based at least in part on the device type associated with the first wireless device and the independent synchronization source mode, wherein the one or more bits indicate the device type associated with the first wireless device and indicate that the first wireless device is operating as the reference for synchronization.

4. The method of claim 1, wherein the one or more synchronization signals include a sidelink master information block, the method further comprising: include: One or more bits for the sidelink master information block are selected based at least in part on the device type associated with the first wireless device and the independent synchronization source mode, wherein the one or more bits indicate the device type associated with the first wireless device and indicate that the first wireless device is operating as the reference for synchronization.

5. The method according to claim 1, further comprising: include: selecting a first identifier from a set of identifiers associated with the independent synchronization source mode, wherein the set of identifiers corresponds to the device type associated with the first wireless device; as well as The one or more synchronization signals are generated based at least in part on the first identifier.

6. The method according to claim 5, further comprising: include: receiving a second one or more synchronization signals, the second one or more synchronization signals indicating a device type associated with a second wireless device; as well as The independent synchronization source mode for the first wireless device is deactivated based at least in part on receiving the second one or more synchronization signals.

7. The method of claim 6, wherein the device type associated with the first wireless device and the device type associated with the second wireless device are the same device type, the method further comprising: include: A second identifier corresponding to the device type associated with the second wireless device is received as part of the second one or more synchronization signals, wherein deactivating the independent synchronization source mode for the first wireless device is based at least in part on a comparison of the first identifier and the second identifier.

8. The method of claim 6, wherein the device type associated with the first wireless device is different from the device type associated with the second wireless device, the method further comprising: include: A second identifier corresponding to the device type associated with the second wireless device is received as part of the second one or more synchronization signals, wherein deactivating the independent synchronization source mode for the first wireless device is based at least in part on the device type associated with the second wireless device.

9. The method of claim 1, wherein the one or more conditions associated with the first wireless device are satisfied based at least in part on a deployment scenario of the first wireless device.

10. The method of claim 9, wherein the first wireless device is a roadside unit.

11. The method according to claim 1, further comprising: include: One or more applications supported by the first wireless device are determined, wherein the one or more conditions associated with the first wireless device are satisfied based at least in part on the one or more applications.

12. The method according to claim 1, further comprising: include: The one or more conditions associated with the first wireless device are determined to be satisfied based at least in part on a priority of a packet for transmission by the first wireless device.

13. The method of claim 12, wherein the one or more synchronization signals include a reserved bit field, the method further comprising: include: One or more bits for the reserved bit field are selected based at least in part on the priority of the packet, wherein the one or more bits indicate the priority of the packet.

14. The method of claim 13, wherein at least one of the one or more bits indicates a device priority for the packet, the device priority corresponding to one or both of a roadside unit and an onboard unit.

15. The method according to claim 1, further comprising: include: Monitoring for a second one or more synchronization signals from a second wireless device over a time period, wherein activating the independent synchronization source mode is based at least in part on an absence of the second one or more synchronization signals during the monitoring over the time period.

16. The method of claim 1, wherein the one or more synchronization signals comprises a sidelink synchronization signal.

17. The method of claim 1, wherein the first device type corresponds to a roadside unit and the second device type corresponds to an onboard unit.

18. A method for wireless communication at a second wireless device, the method include: receiving one or more synchronization signals from a first wireless device, the one or more synchronization signals indicating a device type associated with the first wireless device and indicating that the first wireless device is operating as a reference for synchronization; selecting the first wireless device as the reference for synchronization based at least in part on the one or more synchronization signals and the device type; as well as Synchronizing with the first wireless device is performed based at least in part on the selection.

19. The method according to claim 18, further comprising: include: One or more synchronization signals are transmitted, the one or more synchronization signals indicating that timing of the second wireless device is based at least in part on the first wireless device as the reference for synchronization of the second wireless device.

20. The method according to claim 18, further comprising: include: receiving a bit field indicating a coverage status of the first wireless device as part of the one or more synchronization signals, wherein one or more bits for the bit field indicate the device type associated with the first wireless device and indicate that the first wireless device is operating as the reference for synchronization, and wherein selecting the first wireless device as the reference for synchronization is based at least in part on the one or more bits.

21. The method according to claim 18, further comprising: include: receiving a sidelink master information block as part of the one or more synchronization signals, wherein one or more bits for the sidelink master information block indicate the device type associated with the first wireless device and indicate that the first wireless device is operating as the reference for synchronization, and wherein selecting the first wireless device as the reference for synchronization is based at least in part on the one or more bits.

22. The method according to claim 18, further comprising: include: A first identifier from a set of identifiers associated with an independent synchronization source mode is received as part of the one or more synchronization signals, wherein the set of identifiers corresponds to the device type associated with the first wireless device, and wherein selecting the first wireless device as the reference for synchronization is based at least in part on the first identifier.

23. The method according to claim 22, further comprising: include: receiving a second one or more synchronization signals indicating a device type associated with a third wireless device and indicating that the third wireless device is operating as a second reference for synchronization, wherein the second one or more synchronization signals include a second identifier from the set of identifiers associated with the independent synchronization source mode and corresponding to the device type associated with the third wireless device, wherein selecting the first wireless device as the reference for synchronization is based at least in part on a comparison of the first identifier and the second identifier.

24. The method of claim 23, wherein the device type associated with the first wireless device and the device type associated with the third wireless device are the same device type.

25. The method of claim 18, wherein the first wireless device is selected as the reference for synchronization include: The first wireless device is selected based at least in part on a deployment scenario of the second wireless device, one or more applications supported by the second wireless device, or a combination thereof.

26. The method of claim 18, wherein selecting the first wireless device as the reference for synchronization is based at least in part on the device type associated with the first wireless device and the device type associated with the second wireless device.

27. The method according to claim 18, further comprising: include: A reserved bit field is received as part of the one or more synchronization signals, wherein one or more bits for the reserved bit field indicate a priority of a packet for transmission by the first wireless device, and wherein selecting the first wireless device as the reference for synchronization is based at least in part on the priority of the packet.

28. The method according to claim 27, in: At least one bit of the one or more bits indicates a device priority for the packet, the device priority corresponding to one or both of a roadside unit and an onboard unit; and Selecting the first wireless device as the reference for synchronization is based at least in part on the device priority.

29. The method of claim 18, wherein the one or more synchronization signals comprises a sidelink synchronization signal.

30. The method of claim 18, wherein the first device type corresponds to a roadside unit and the second device type corresponds to an onboard unit.

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