TW202037210A - Sidelink synchronization methods for v2x in nr - Google Patents

Abstract

Methods for sidelink synchronization may be used by a wireless transmit/receive unit (WTRU) that wants to a join a group of WTRUs, such as a vehicle platoon. The WTRU may receive configuration information for sidelink communications including measurement thresholds. The WTRU may monitor a sidelink channel for signals from synchronization sources. The WTRU may perform a sidelink measurements and determine synchronization source type and hop number for the synchronization sources. The WTRU may compile a list of synchronization sources with sidelink measurement above a first threshold and select a platoon leader type. If there is no platoon leader in the list, the WTRU may select the synchronization source with hop number below a hop threshold. Otherwise, the WTRU may select the synchronization source for which the value of the sidelink measurement is greater than a second sidelink measurement threshold. The WTRU may establish a link with the selected synchronization source.

Description

V2X side chain synchronization method in NR

Cross references to related applications

This application claims to protect the rights and interests of U.S. Provisional Application No. 62/736,795 filed on September 26, 2018, the content of which is incorporated herein by reference.

The recent 3rd Generation Partnership Project (3GPP) standards discussion defined several deployment scenarios, such as indoor hotspots, dense cities, villages, urban macros, and high speeds. Based on the general requirements of the International Telecommunication Union (ITU-R), Next Generation Mobile Network (NGMN) and 3GPP, the use cases of emerging 5G systems can be broadly classified as enhanced mobile broadband (eMBB) and large-scale machines Type communication (mMTC) and ultra-reliable and low-latency communication (URLLC). These use cases focus on meeting different performance requirements, such as higher data rates, higher spectral efficiency, low power and higher energy efficiency, and/or lower latency and higher reliability. In addition, for various deployment scenarios, consider a wide range of spectrum bands ranging from 700 MHz to 80 GHz.

The method for side-chain synchronization can be used by wireless transmission/reception units (WTRU) that want to join a WTRU group such as a fleet of vehicles, and can be used for the Internet of Vehicles (V2X) in New Radio (NR). The WTRU may receive configuration information for side-chain communication, where the configuration information includes measurement thresholds. The WTRU may monitor the side-chain channel for signals from multiple synchronization sources. The WTRU may perform side-chain measurement on the side-chain synchronization signal from each of the complex synchronization sources, and determine the value for each of the complex synchronization sources based on the information carried in the corresponding side-chain synchronization signal Synchronization source type and hop count. The WTRU may compile a list of synchronization sources for the plurality of synchronization sources (for which the side-chain measurement value is greater than the first side-chain measurement threshold). The WTRU may select a synchronization source whose synchronization source type is the team leader type. If no synchronization source in the list is of the team leader synchronization source type, the WTRU may select a synchronization source with a hop count less than the first hop count threshold. If no synchronization source in the synchronization source list has a hop count less than the first hop count threshold, the WTRU may select a synchronization source whose side-chain measurement value is greater than the second side-chain measurement threshold. The WTRU may establish a link with the selected synchronization source.

FIG. 1A is a diagram showing an exemplary communication system 100 in which one or more of the disclosed embodiments are implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 can enable multiple wireless users to access these contents by sharing system resources (including wireless bandwidth). For example, the communication system 100 may use one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA) , Single carrier FDMA (SC-FDMA), zero-tail unique word DFT-extended OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtering OFDM, filter bank multi-carrier (FBMC), etc. Wait.

As shown in FIG. 1A, the communication system 100 may include wireless transmission/reception units (WTRU) 102a, 102b, 102c, 102d, RAN 104/113, CN106/115, public switched telephone network (PSTN) 108, and the Internet 110 And other networks 112, but it should be understood that the disclosed embodiments encompass any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. As an example, any of the WTRUs 102a, 102b, 102c, 102d may be referred to as a "station" and/or "STA", which may be configured to transmit and/or receive wireless signals, and may include user equipment ( UE), mobile station, fixed or mobile user unit, user-based unit, pager, mobile phone, personal digital assistant (PDA), smart phone, portable computer, small laptop, personal computer, wireless sensor , Hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMD), vehicles, drones, medical devices and applications (such as remote surgery), industrial devices and applications (For example, robots and/or other wireless devices operating in an industrial and/or automated processing chain environment), consumer electronics devices, devices operating on commercial and/or industrial wireless networks, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as UE.

The communication system 100 may also include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b may be configured to have a wireless interface with at least one of the WTRU 102a, 102b, 102c, 102d to facilitate access to one or more communication networks (for example, CN 106/115, Internet 110 and/or network 112). As an example, the base stations 114a, 114b may be base station transceiver stations (BTS), node B, e node B, local node B, local e node B, gNB, NR node B, website controller, access point (AP) , Wireless router, etc. Although the base stations 114a, 114b are each described as a single element, it should be understood that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

The base station 114a may be part of the RAN 104/113, and it may also include other base stations and/or network elements (not shown) such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. Shows). The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies can be in licensed spectrum, unlicensed spectrum, or a combination of licensed spectrum and unlicensed spectrum. Cells can provide wireless service coverage to specific geographic areas that can be relatively fixed or change over time. Cells can also be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Therefore, in an embodiment, the base station 114a may include three transceivers, for example, one for each sector of the cell. In an embodiment, the base station 114a may use multiple input multiple output (MIMO) technology, and may use a complex transceiver for each sector of the cell. For example, beamforming can be used to transmit and/or receive signals in a desired spatial direction.

The base stations 114a, 114b can communicate with one or more of the WTRUs 102a, 102b, 102c, 102d through an air interface 116, which can be any suitable wireless communication link (for example, radio frequency (RF), Microwave, centimeter wave, micro wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 can be established using any suitable radio access technology (RAT).

More specifically, as described above, the communication system 100 may be a multiple access system, and may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a and WTRU 102a, 102b, 102c in the RAN 104/113 may implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use wideband CDMA (WCDMA) To build the air interface 115/116/117. WCDMA may include communication protocols such as High Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include high-speed downlink (DL) packet access (HSDPA) and/or high-speed UL packet access (HSUPA).

In one embodiment, the base station 114a and the WTRU 102a, 102b, 102c may implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may use Long Term Evolution (LTE) and/or LTE Advanced (LTE-A) and/or Professional LTE Advanced (LTE-A Pro) to establish the air interface 116.

In one embodiment, the base station 114a and the WTRU 102a, 102b, 102c may implement radio technologies such as NR radio access, which may use New Radio (NR) to establish the air interface 116.

In one embodiment, the base station 114a and the WTRU 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may, for example, use dual connectivity (DC) principles to implement LTE radio access and NR radio access together. Therefore, the air interface used by the WTRU 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions to/from multiple types of base stations (e.g., eNBs and gNBs).

In other embodiments, the base station 114a and the WTRU 102a, 102b, 102c may implement IEEE 802.11 (i.e., wireless fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000, etc. 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rate GSM Evolution (EDGE) ), GSM EDGE (GERAN) and other radio technologies.

The base station 114b in FIG. 1A can be, for example, a wireless router, a local node B, a local eNode B, or an access point, and any suitable RAT can be used to facilitate the use of mobile devices such as commercial areas, homes, vehicles, campuses, and industrial Wireless connection of local areas such as facilities, air corridors (for example, for drones), roads, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement radio technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRU 102c, 102d may use a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a pico cell ( picocell) or femtocell (femtocell). As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Therefore, the base station 114b does not need to access the Internet 110 via the CN 106/115.

The RAN 104/113 may communicate with CN 106/115, which may be configured to provide voice, data, applications, and/or Voice over Internet Protocol (VoIP) services to the WTRU 102a, 102b, 102c, 102d Any type of network of one or more of them. Data can have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. CN 106/115 can provide call control, billing services, mobile location-based services, prepaid calls, Internet connections, video distribution, etc., and/or perform advanced security functions, such as user authentication. Although not shown in FIG. 1A, it should be understood that the RAN 104/113 and/or CN 106/115 can directly or indirectly communicate with other RANs, which use the same RAT as the RAN 104/113 or different RAT. For example, in addition to connecting to RAN 104/113 that can use NR radio technology, CN 106/115 can also communicate with another RAN (not shown) that uses GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology .

CN 106/115 can also be used as a gateway for WTRU 102a, 102b, 102c, 102d to access PSTN 108, Internet 110, and/or other networks 112. PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use a common communication protocol, such as the Transmission Control Protocol (TCP)/Internet Protocol (IP) Internet Protocol Suite TCP, User Datagram Protocol (UDP) and/or IP. The network 112 may include wireless and/or wired communication networks owned and/or operated by other service providers. For example, the network 112 may include another CN connected to one or a plurality of RANs, which may use the same RAT as the RAN 104/113 or a different RAT.

Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (for example, WTRUs 102a, 102b, 102c, 102d may include different wireless links and different wireless networks. Multiple transceivers for communication). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that can use cellular-based radio technology, and to communicate with a base station 114b that can use IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120, a transmission/reception element 122, a speaker/microphone 124, a keypad 126, a display/touch pad 128, a non-removable memory 130, and a removable memory Body 132, power supply 134, global positioning system (GPS) chipset 136 and/or other peripheral devices 138, etc. It should be understood that the WTRU 102 may include any sub-combination of the above-mentioned elements while remaining consistent with the embodiment.

The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with the DSP core, a controller, a microcontroller, Dedicated integrated circuit (ASIC), field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), state machine, etc. The processor 118 may perform signal encoding, data processing, power control, input/output processing, and/or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120, which may be coupled to the transmission/reception element 122. Although the processor 118 and the transceiver 120 are described as separate components in FIG. 1B, it should be understood that the processor 118 and the transceiver 120 may be integrated into an electronic package or a chip together.

The transmission/reception element 122 may be configured to transmit signals to a base station (for example, base station 114a) or receive signals from a base station (for example, base station 114a) through the air interface 116. For example, in one embodiment, the transmission/reception element 122 may be an antenna configured to transmit and/or receive RF signals. For example, in one embodiment, the transmission/reception element 122 may be a transmitter/detector configured to transmit and/or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmission/reception element 122 may be configured to transmit and/or receive both RF signals and optical signals. It should be understood that the transmission/reception element 122 may be configured to transmit and/or receive any combination of wireless signals.

In addition, although the transmission/reception element 122 is depicted as a single element in FIG. 1B, the WTRU 102 may include any number of transmission/reception elements 122. More specifically, the WTRU 102 may use MIMO technology. Thus, in an embodiment, the WTRU 102 may include two or more transmission/reception elements 122 (eg, multiple antennas) for transmitting and/or receiving wireless signals through the air interface 116.

The transceiver 120 may be configured to modulate the signal to be transmitted by the transmission/reception element 122 and be configured to demodulate the signal received by the transmission/reception element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

The processor 118 of the WTRU 102 may be coupled to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (for example, a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), In addition, user input data may be received from the speaker/microphone 124, the keypad 126, and/or the display/touch panel 128 (for example, a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 can also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 can access information from any type of suitable memory, and store data in any type of suitable memory. The memory may be, for example, non-removable memory 130 and/or removable memory.体132. The non-removable memory 130 may include random access memory (RAM), read-only memory (ROM), hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from memory that is not physically located on the WTRU 102 (such as on a server or a home computer (not shown)), and store data in the memory.

The processor 118 may receive power from the power source 134 and may be configured to distribute the power to other components in the WTRU 102 and/or to control the power of other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry battery packs (eg, nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (eg, longitude and latitude) regarding the current location of the WTRU 102. The WTRU 102 may receive location information in addition to or in place of the GPS chipset 136 information from base stations (eg, base stations 114a, 114b) through the air interface 116, and/or based on receiving from two or more adjacent base stations The timing of the received signal determines its location. It should be understood that while being consistent with the embodiment, the WTRU 102 may obtain location information by any suitable location determination method.

The processor 118 may also be coupled to other peripheral devices 138, which may include one or more software and/or hardware modules that provide additional features, functions, and/or wireless or wired connections. For example, the peripheral device 138 may include an accelerometer, an electronic compass (e-compass), a satellite transceiver, a digital camera (for photos and/or video), a universal serial bus (USB) port, a vibration device, a TV transceiver, Hands-free headsets, Bluetooth® modules, frequency modulation (FM) radio units, digital music players, media players, video game console modules, Internet browsers, virtual reality and/or augmented reality (VR/AR) ) Devices, activity trackers, etc. The peripheral device 138 may include one or more sensors, and the sensors may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor Sensor, temperature sensor, time sensor, geographic location sensor, altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biosensor, and/or Humidity sensor.

The WTRU 102 may include a full-duplex radio, for which some or all of the signals (eg, with special subframes for both UL (eg, for transmission) and downlink (eg, for reception)) Related) transmission and reception can be parallel and/or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce signal processing by hardware (such as a choke coil) or through a processor (such as a separate processor (not shown) or through the processor 118). And/or substantially eliminate self-interference. In one embodiment, WRTU 102 may include the transmission and reception of some or all of the signals (for example, associated with special subframes for UL (for example, for transmission) or downlink (for example, for reception)) Half-duplex radio.

FIG. 1C is a system diagram showing the RAN 104 and the CN 106 according to an embodiment. As described above, the RAN 104 can communicate with the WTRUs 102a, 102b, and 102c over the air interface 116 using E-UTRA radio technology. The RAN 104 can also communicate with the CN 106.

The RAN 104 may include eNodeBs 160a, 160b, 160c, but it should be understood that the RAN 104 may include any number of eNodeBs while being consistent with the embodiment. Each of the eNodeBs 160a, 160b, 160c may include one or more transceivers for communicating with the WTRU 102a, 102b, 102c via the air interface 116. In an embodiment, the eNodeB 160a, 160b, 160c may implement MIMO technology. Therefore, the eNodeB 160a may, for example, use multiple antennas to transmit wireless signals to and/or receive wireless signals from the WTRU 102a.

Each of the eNodeBs 160a, 160b, 160c can be associated with a special cell (not shown), and can be configured to handle radio resource management decisions, handover decisions, scheduling use in UL and/or DL者 etc. As shown in Figure 1C, eNodeBs 160a, 160b, and 160c can communicate with each other through the X2 interface.

The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a service gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the foregoing elements is described as part of CN 106, it should be understood that any of these elements may be owned and/or operated by entities other than the CN operator.

The MME 162 can be connected to each of the eNodeBs 162a, 162b, and 162c in the RAN 104 through the S1 interface, and can serve as a control node. For example, the MME 162 may be responsible for authenticating users of WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a special service gateway during the initial attachment of WTRUs 102a, 102b, 102c, and so on. The MME 162 may provide control plane functions for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies such as GSM and/or WCDMA.

The SGW 164 can be connected to each of the eNodeBs 160a, 160b, and 160c in the RAN 104 through the S1 interface. The SGW 164 can generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The SGW 164 may also perform other functions, such as anchoring the user plane during the handover between eNodeBs, triggering paging when DL data is available to the WTRUs 102a, 102b, and 102c, managing and storing the context of the WTRUs 102a, 102b, and 102c, and so on.

SGW 164 can be connected to PGW 166, which can provide WTRU 102a, 102b, 102c with access to a packet-switched network such as the Internet 110 to facilitate communication between WTRU 102a, 102b, 102c and IP-enabled devices Communication.

CN 106 can facilitate communication with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network such as the PSTN 108 to facilitate communication between the WTRUs 102a, 102b, 102c and traditional landline communication devices. For example, the CN 106 may include or communicate with an IP gateway (such as an IP Multimedia Subsystem (IMS) server) as an interface between the CN 106 and the PSTN 108. Additionally, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired or wireless networks owned and/or operated by other service providers.

Although the WTRU is described as a wireless terminal in FIGS. 1A to 1D, it is expected that in certain representative embodiments, such a terminal may (e.g., temporarily or permanently) use the communication network Wired communication interface.

In a representative embodiment, the other network 112 may be a WLAN.

A WLAN in an infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STA) associated with the AP. APs may have access or interfaces to distributed systems (DS) or other types of wired/wireless networks, which pass traffic into and/or out of the BSS. The traffic from outside the BSS to the STA can be reached by the AP and can be delivered to the STA. Traffic originating from the STA to destinations other than the BSS can be sent to the AP for delivery to the respective destinations. The traffic between STAs in the BSS can be sent by the AP, for example, the source STA can send the traffic to the AP and the AP can deliver the traffic to the destination STA. The traffic between STAs in the BSS can be considered and/or referred to as peer-to-peer traffic. Peer-to-peer traffic can be sent between the source STA and the destination STA (for example, directly between them) using direct link establishment (DLS). In some representative embodiments, DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using IBSS (for example, all STAs) can directly communicate with each other. The IBSS communication mode can sometimes be referred to as an "ad-hoc" communication mode.

When using the 802.11ac infrastructure operating mode or a similar operating mode, the AP can transmit beacons on a fixed channel (such as the main channel). The main channel can have a fixed width (for example, 20MHz wide bandwidth) or dynamically set the width through transmission. The main channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example, in an 802.11 system. For CSMA/CA, STAs including APs (for example, each STA) can sense the main channel. If the main channel is sensed/detected by a special STA and/or is determined to be busy, the special STA may back off. One STA (for example, only one station) can transmit at any given time in a given BSS.

High throughput (HT) STAs can communicate using 40MHz wide channels, for example, by combining the main 20MHz channel with adjacent or non-adjacent 20MHz channels to form a 40MHz wide channel.

VHT STA can support 20MHz, 40MHz, 80MHz and/or 160MHz wide channels. 40MHz and/or 80MHz channels can be formed by combining continuous 20MHz channels. A 160MHz channel can be formed by combining 8 continuous 20MHz channels or by combining two discontinuous 80MHz channels (which can be called an 80+80 configuration). For the 80 + 80 configuration, after the channel is encoded, the data can be divided into two streams by a segmented parser. Inverse Fast Fourier Transform (IFFT) processing and time domain processing can be done separately on each stream. These streams can be mapped to two 80MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80+80 configuration can be reversed, and the combined data can be sent to the media access control (MAC).

The sub-1 GHz operating mode is supported by 802.11af and 802.11ah. The channel operating bandwidth and carrier in 802.11af and 802.11ah are reduced compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum . According to a representative embodiment, 802.11ah can support meter type control/machine type communication such as MTC devices in a macro coverage area. The MTC device may have certain capabilities, for example, limited capabilities include supporting (eg, only supporting) certain and/or limited bandwidth. The MTC device may include a battery with a battery life above a critical value (eg, to maintain a very long battery life).

WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The main channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the main channel may be set and/or limited by STAs among all STAs operating in the BSS supporting the minimum bandwidth operation mode. In the 802.11ah example, even if the AP and other STAs in the BBS support 2MHz, 4MHz, 8MHz, 16MHz, and/or other channel bandwidth operation modes, for STAs that support (for example, only support) 1MHz mode (for example, MTC) Type device), the main channel can be 1MHz wide. Carrier sensing and/or network allocation vector (NAV) settings may depend on the status of the main channel. If the main channel is busy, for example, due to the STA (which only supports the 1MHz operating mode) transmitting to the AP, even if most of the frequency band remains free and available, the entire available frequency band can be considered busy.

In the United States, the available frequency bands that can be used by 802.11ah range from 902MHz to 928MHz. In South Korea, the available frequency band ranges from 917.5 MHz to 923.5 MHz. In Japan, the available frequency band ranges from 916.5 MHz to 927.5 MHz. According to the country code, the total bandwidth available for 802.11ah is 6 MHz to 26 MHz.

FIG. 1D is a system diagram showing the RAN 113 and the CN 115 according to the embodiment. As described above, the RAN 113 can communicate with the WTRUs 102a, 102b, 102c through the air interface 116 using NR radio technology. RAN 113 can also communicate with CN 115.

The RAN 113 may include gNB 180a, 180b, and 180c, but it should be understood that the RAN 113 may include any number of gNBs while remaining consistent with the embodiment. Each gNB 180a, 180b, 180c may include one or a plurality of transceivers for communicating with the WTRU 102a, 102b, 102c through the air interface 116. In an embodiment, gNB 180a, 180b, and 180c may implement MIMO technology. For example, gNB 180a, 108b may utilize beamforming to transmit signals to and/or receive signals from gNB 180a, 180b, 180c. Therefore, gNB 180a may, for example, use multiple antennas to transmit wireless signals to and/or receive wireless signals from WTRU 102a. In an embodiment, gNB 180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB 180a may transmit complex component carriers (not shown) to WTRU 102a. A subset of these component carriers can be on the unlicensed spectrum, while the remaining component carriers can be on the licensed spectrum. In an embodiment, the gNB 180a, 180b, and 180c may implement coordinated multipoint (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180c).

The WTRU 102a, 102b, 102c may communicate with gNB 180a, 180b, 180c using transmissions associated with the scalable parameter configuration. For example, for different transmissions, different cells, and/or different parts of the wireless transmission spectrum, the OFDM symbol spacing and/or OFDM subcarrier spacing may vary. The WTRU 102a, 102b, 102c may use sub-frames or transmission time intervals (TTIs) of various or scalable lengths (for example, contain different numbers of OFDM symbols and/or continuously change the length of the absolute time) and gNB 180a, 180b, 180c Communication.

The gNB 180a, 180b, 180c may be configured to communicate with the WTRU 102a, 102b, 102c in a discrete configuration and/or a non-discrete configuration. In a discrete configuration, the WTRU 102a, 102b, 102c can communicate with gNB 180a, 180b, 180c without also accessing other RANs (such as eNodeB 160a, 160b, 160c, for example). In a discrete configuration, the WTRU 102a, 102b, 102c may use one or more of the gNB 180a, 180b, 180c as the anchor point of action. In a discrete configuration, the WTRU 102a, 102b, 102c may use signals in the unlicensed frequency band to communicate with the gNB 180a, 180b, 180c. In a non-discrete configuration, the WTRU 102a, 102b, 102c can communicate with/connect to gNB 180a, 180b, 180c with gNB 180a, 180b, 180c, while also communicating with another RAN (for example, eNodeB 160a, 160b, 160c) /connection. For example, the WTRU 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-discrete configuration, the eNodeB 160a, 160b, 160c may act as the mobility anchor for the WTRU 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and/or for the serving WTRU 102a, 102b, 102c Delivery volume.

Each of gNB 180a, 180b, 180c can be associated with a special cell (not shown), and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and/or DL, and network Road cutting support, dual connectivity, intercommunication between NR and E-UTRA, routing of user plane data to user plane functions (UPF) 184a, 184b, control plane information access and mobility management functions ( AMF) routing of 182a, 182b, etc. As shown in Figure 1D, gNB 180a, 180b, and 180c can communicate with each other through the Xn interface.

The CN 115 shown in FIG. 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possibly data networks (DN) 185a, 185b. Although each of the aforementioned elements is described as part of the CN 115, it should be understood that any of these elements can be owned and/operated by entities other than the CN operator.

The AMF 182a, 182b can be connected to one or a plurality of gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface, and can act as a control node. For example, AMF 182a, 182b can be responsible for authenticating users of WTRU 102a, 102b, 102c, supporting network interception (for example, processing different PDU conversations with different requirements), selecting special SMF 183a, 183b, managing registration areas, and NAS messaging Termination, mobility management, etc. Network cutting can be used by AMF 182a, 182b to customize CN support for WTRU 102a, 102b, 102c based on the type of service being utilized by WTRU 102a, 102b, 102c. For example, you can create different network cuts for different use cases, such as services that rely on ultra-reliable low-latency (URLLC) access, services that rely on enhanced large-scale mobile broadband (eMBB) access, and machine Type of communication (MTC) access services, and/or similar services. The AMF 162 may be an interface between the RAN 113 and other RANs (not shown) that use other radio technologies (for example, LTE, LTE-A, LTE-A Pro, and/or non-3GPP access technologies such as WiFi) The switch provides control plane functions.

The SMF 183a, 183b can be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. SMF 183a, 183b can also be connected to UPF 184a, 184b in CN 115 via N4 interface. SMF 183a, 183b can select and control UPF 184a, 184b, and configure the routing of traffic through UPF 184a, 184b. SMF 183a, 183b can perform other functions, such as managing and assigning WTRU IP address, managing PDU dialogue, controlling policy implementation and QoS, and providing notification of downlink data. The PDU dialog type can be IP-based, non-IP-based, Ethernet-based, and so on.

UPF 184a, 184b can be connected to one or a plurality of gNBs 180a, 180b, 180c in RAN 113 via N3 interface, which can provide WTRU 102a, 102b, 102c with access to a packet switching network (such as Internet 110), To facilitate communication between the WTRU 102a, 102b, 102c and the IP-enabled device. UPF 184a, 184b can perform other functions, such as routing and forwarding packets, implementing user plane policies, supporting multi-homed PDU dialogue, handling user plane QoS, buffering downstream packets, and providing mobility anchors.

CN 115 can facilitate communication with other networks. For example, the CN 115 may include an IP gateway, or may communicate with it (for example, an IP Multimedia Subsystem (IMS) server), which serves as an interface between the CN 115 and the PSTN 108. Additionally, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and/or wireless networks owned and/or operated by other service providers. In one embodiment, the WTRU 102a, 102b, 102c can be connected to the UPF 184a, 184b through the N3 interface and the UPF 184a, 184b and the local data network (DN) 185a, 185b through the N6 interface through the UPF 184a, 184b. DN 185a, 185b.

With reference to FIGS. 1A to 1D and the corresponding descriptions of FIGS. 1A to 1D, one or more or all of the functions described herein for one or more of the following may be performed by one or more analog devices (not shown): WTRU 102a -d, base station 114a-b, eNodeB 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, And/or any other devices described herein. The simulation device may be one or a plurality of devices configured to simulate one or more or all of the functions described herein. For example, the simulation device can be used to test other devices and/or simulate network and/or WTRU functions.

The simulation device can be designed to perform one or more tests of other devices in the laboratory environment and/or the operator's network environment. For example, one or a plurality of analog devices may be implemented and/or deployed as part of a wired and/or wireless communication network while performing one or a plurality or all of the functions to test other devices in the communication network. One or more analog devices can perform one or more or all functions while temporarily implemented/deployed as part of a wired and/or wireless communication network. The simulation device can be directly coupled to another device for testing purposes and/or can use air wireless communication to perform testing.

One or plural analog devices can perform one or plural functions including all functions, rather than being implemented/deployed as part of a wired and/or wireless communication network. For example, the simulation device can be utilized in test laboratories and/or non-deployed (for example, testing) wired and or wireless communication network test scenarios to implement testing of one or more components. One or more simulation devices can be test equipment. The analog device may use direct RF coupling and/or wireless communication via an RF circuit (for example, it may include one or multiple antennas) to transmit and/or receive data.

In wireless communications, as the carrier frequency increases, severe path loss may become a key limitation to ensure adequate coverage. Transmission in millimeter wave (mmW) systems may additionally suffer from non-line-of-sight losses, such as diffraction loss, penetration loss, oxygen absorption loss, and/or blade loss. During the initial access, the base station and the WTRU may need to overcome these high path losses and discover each other. Using dozens or even hundreds of antenna elements to generate beamforming signals is an effective way to compensate for severe path loss by providing significant beamforming gain. Beamforming techniques may include digital beamforming, analog beamforming, and hybrid beamforming.

In the 3GPP Internet of Vehicles (V2X) standardization process, several use cases were considered, including the following use case groups: vehicle platooning, extended sensors, advanced driving, and remote driving. Each use case group can have different latency, reliability, and data rate requirements, such as the examples summarized in Table 1. Use case group End-to-end dive time (ms) reliability(%) Data rate (Mbps) Vehicle fleet 10 99.99 65 Advanced driving 3 99.999 53 Extended sensor 3 99.999 1000 Remote driving 5 99.999 UL: 25, DL: 1 Table 1: Sample latency, reliability and data rate requirements of the V2X use case group

The use cases within each use case group can have different latency, reliability, and/or data rate requirements. For example, a lower degree of automation in a video sharing scenario (which can be part of an extended sensor use case set) may have a latency requirement of 50 ms, a reliability requirement of 90%, and a data rate requirement of 10 Mbps. In another example, a higher degree of automation in sharing sensor information between WTRUs supporting V2X applications (which can also be part of an extended sensor set) can have a 3 ms latency requirement and 99.999% reliability Requirements and 25 Mbps data rate requirements.

In 3GPP V2X, the vehicle can be in transmission mode 3 (ie, mode 3 user) or can be in transmission mode 4 (ie, mode 4 user). Mode 3 users can directly use the resources allocated by the base station for side-chain (SL) communication between vehicles or between vehicles and pedestrians. Mode 4 users can obtain a list of candidate resources allocated by the base station, and select resources from the candidate resources for their SL communication. Here, user, UE, WTRU, and vehicle WTRU may equally and interchangeably refer to vehicle.

2 is a signaling diagram of an exemplary side-chain WTRU information exchange process 200 for communication between a (vehicle) WTRU 201 and gNB and/or eNB 202 for V2X side-chain transmission, for example, according to 5G NR V2X and/or LTE V2X. Once the WTRU 201 is camped on the cell associated with the gNB/eNB 202, the WTRU 201 may receive System Information Block (SIB) type 21 (SIB21) 204, which may include a V2X side chain communication configuration. For example, SIB21 204 may include SL-V2X-ConfigCommon information element (IE), which may include but is not limited to including components v2x-CommRxPool , v2x-CommTxPoolNormalCommon , v2-CommTxPoolExceptional and/or v2x-InterFreqInfoList . v2x-InterFreqInfoList may be a list about adjacent frequencies (for example, up to seven adjacent frequencies) used for V2X side chain communication. The WTRU 201 may send the side chain WTRU information 206 to the gNB/eNB 202 in one or multiple messages. For example, as part of the side chain WTRU information 206, the vehicle WTRU 201 may send a message (one or more) to the gNB/eNB 202, which indicates to the gNB/eNB 202 that the WTRU 201 is willing to receive V2X side chain communications and/or request assignment and / Or are interested (or not interested) in releasing the transmission resources used for V2X side chain communication. The WTRU 201 and the gNB/eNB 202 may exchange one or more RRCConnectionReconfiguration messages 208, which may include the SL-V2X-ConfigDedicated IE. For example, the SL-V2X-ConfigDedicated IE may include but is not limited to commTxResources and/or V2x-InterFreqInfoList .

The research project on NR V2X considers Uu-based side chain resource allocation/reconfiguration to identify enhancements to the LTE Uu interface and NR Uu interface, to control the NR side chain from the cellular network, and to identify the enhancement of the NR Uu interface, To control the LTE side chain communication from the cellular network. In the context of LTE V2X synchronization, when the WTRU connects to the eNB, the WTRU may already have cell timing. If the WTRU is not within the coverage of the eNB, the WTRU may use the Global Navigation Satellite System (GNSS) for timing synchronization. When the WTRU cannot find the timing from the eNB or GNSS, the WTRU may rely on the side chain WTRU for timing information. GNSS satellites have atomic oscillators that provide a stable and accurate time reference. The GNSS receiver can track signals from a plurality of satellites and retrieve a local time reference for the global positioning system (GPS) receiver with an absolute error of less than 1 μs. For coordinated multipoint transmission, the residual using GPS can be about 10 ns. GNSS can be used for frequency synchronization by phase-locking the local oscillator to the incoming signal and stabilizing the carrier frequency. For modern vehicles equipped with GNSS receivers, GNSS solutions for synchronization can be used for V2X.

For example, for synchronization in V2X, a WTRU may receive side-chain synchronization signals (SLSS) from other WTRUs on the side-chain. The SLSS may include a primary side chain synchronization signal (PSSS), a secondary side chain synchronization signal (SSSS), and/or a physical side chain broadcast channel (PSBCH) signal, which may further include synchronization information. The WTRU can use the information carried in the SLSS to obtain timing information. Thresholds used for synchronization measurement (for example, synchronization thresholds) can be received in RRC messaging (for example, v2x-SyncConfig and/or SL-V2X-Preconfiguration IE).

The SLSS may include, but is not limited to, any one or more of the following example signals: PSSS, SSSS, PSBCH, and/or demodulation reference signal (DMRS) for demodulating the PSBCH. For example, PSSS and SSSS can be transmitted in adjacent time slots in the same subframe. Side chain-ID (SID) can be divided into two groups. For example, the SID in the range {0, 1, ..., 167} may be reserved for the in-coverage WTRU (ie, a WTRU that can receive a signal strong enough to connect with the cell associated with the eNB), and the range { The SIDs in 168,169,...,335} can be used to cover the outer WTRU. The subframes used as radio resources to transmit SLSS and PSBCH can be configured by higher layers

NR V2X requirements can be different from LTE V2X requirements. For example, for NR V2X services, in order to be able to support higher bandwidth, reliability and higher density of vehicles and users, the existing LTE SLSS may not be sufficient. The capacity of the side chain channel may need to be increased. For example, LTE V2X may not include a beam-centric design, so directional beams can be used to enhance LTE SLSS for NR V2X. For some use cases, such as vehicle fleet formation, different processes can be used for synchronization timing reference and coverage. Therefore, modifications to NR synchronization can be implemented to apply NR synchronization to NR V2X.

A team may include a group of WTRUs, and one of the WTRUs in the group may be configured, assigned, or selected as the team leader, and the other WTRUs may be called team followers. The team leader may be responsible for managing other WTRUs in the team. For example, the team leader can provide one or more of the team followers with any of the following functions: coordination between multiple WTRUs (team followers); unified synchronization timing reference; and/or resource scheduling of other WTRUs Cheng. The team leader can be the team manager. Figure 3 is a network diagram of an example team 300, which includes team leader (PL) WTRU 302 (jump 0), team follower WTRU 304 (jump 1, because it is a neighbor of PL WTRU 302), and team follower WTRU 306 ( Skip 2 because it is two links away from the PL WTRU 302) and the WTRU 301 that wants to join the vehicle fleet 300. As described further below, the WTRU 301 may use information based on the received SL synchronization signals PL SL-SYNC 310, H1 SL-SYNC 312, and H2 SL-SYNC 314 (such as reference signal received power (RSRP), as a leader Or follower's synchronization source type, hop count, one or plural thresholds, and/or priority order rules) to select the synchronization source from the team members WTRUs 302, 304, and 306 to connect to the vehicle team 300. The method disclosed herein is described as an application for vehicle fleets; any method can be similarly applied to any application involving WTRU groups (such as mesh networks, relay networks, or any other WTRU group formation) or Example.

The side-chain synchronization method disclosed in this article can be used in NR V2X for use cases such as vehicle teaming, and can also be used for other NR use cases. Any synchronization method, access method, and/or messaging mechanism described herein can be used by the WTRU to synchronize with the vehicle team in order to become a member of the vehicle team.

In an example, the method of side chain synchronization can be based on measurement, measurement type, and/or synchronization source type. The WTRU can synchronize with one of the synchronization sources in the vehicle fleet. For example, the WTRU may first try to synchronize with the team leader. In one example, the WTRU may not be able to synchronize with the team leader (for example, because the WTRU did not receive the SLSS from the team leader, or the SLSS from the team leader is too weak for the WTRU to decode correctly). If the WTRU fails to synchronize with the team leader, the WTRU may synchronize with one of the team followers. In one example, the WTRU may use one or multiple signal measurements to determine the source with which the WTRU can synchronize. For example, if the signal measurement result from a synchronization source (eg, a WTRU in the team) is higher than a critical value, the WTRU may synchronize with the synchronization source. Otherwise, the WTRU may choose to synchronize with another synchronization source. In one example, when the complex synchronization source has signal measurements above the threshold, the WTRU may select the synchronization source with the highest measurement value.

In the example method described herein, configuration information for side-chain communication may be received from an eNB and/or from another WTRU (eg, on a side-chain). For example, the configuration information for side-chain communication can be received from the eNB in the SIB. In any of the example methods described here, the WTRU can search for the synchronization source by monitoring the side-chain channel (one or more) for signals from the synchronization source (for example, vehicle team members). For example, the WTRU searches for the synchronization source by monitoring the side-chain channels (one or more) and receiving side-chain signals (such as any SLSS). In any of the example methods described here, the WTRU can perform measurements on the same signal it receives to search for a synchronization source, or perform measurements on different side-chain signals.

In any of the example methods described herein, the types of measurements that can be performed by the WTRU for side chain synchronization can include, but are not limited to, include any one or more of the following measurements: RSRP (equivalently, side chain RSRP (S -RSRP)), reference signal reception quality (RSRQ) (equivalently, side-chain RSRQ (S-RSRQ)), received signal strength indicator (RSSI) (equivalently, side-chain RSSI (S-RSSI)), signal Noise ratio (SNR), correlation (equivalently, SL correlation) and/or signal to interference ratio (SINR). The synchronization source selection may be based on any one or more of the different types of measurements made on the signals received from the synchronization source (eg, the team leader and/or one or more team followers). In any of the example methods described herein, the WTRU may perform measurements on signals received from a synchronization source, such as SLSS (for example, including the same signal and/or different signals it receives when searching by the synchronization source). In any of the example methods described herein, the SLSS may include a side-chain synchronization signal block (SL-SSB) (allowing the WTRU to perform measurements (eg RSRP)) and any one or plural parts of the SL-SSB. For example, the SL-SSB may include any of the following parts: PSSS, SSSS, and/or PSBCH signals. In this case, the WTRU may perform measurements on any one or more of the PSSS, SSSS, and/or PSBCH signals. In another example, the SLSS may include a reference signal, such as a channel state information reference signal (CSI-RS) and/or a PSBCH demodulation reference signal (DMRS). In this case, the WTRU may perform measurements on any one or more of the CSI-RS and/or PSBCH DMRS received from one or multiple synchronization sources in the SLSS. In any of the example methods described herein, measurement using CSI-RS and/or PSBCH DMRS can be performed independently of measurement using SL-SSB or in conjunction with SL-SSB or in combination with SL-SSB measurement.

In any of the example methods described herein, the synchronization source type may be one of the team leader (and/or the team co-leader if more than one WTRU may be the team leader) or the team follower. In any of the example methods described herein, the WTRU may determine the synchronization source type based on the information carried in the (side-chain) signal received from the synchronization source. For example, the WTRU may determine the synchronization source type from the information carried in any of the above-mentioned SLSSs, and the synchronization source type may be implicitly or explicitly signaled. The WTRU may determine the synchronization source type from the information carried in any SLSS used for measurement (and/or for searching by the synchronization source) and/or other SLSS received from the synchronization source. For example, the SLSS (for example, in the PSSS, SSSS, and/or PSBCH signal) may carry an explicit indication of the source type (for example, a bit, where "1" indicates the team leader, and the bit "0" indicates that the team follows By). In another example, the SLSS (for example, in PSSS, SSSS, and/or PSBCH signals) may carry the number of hops associated with the synchronization source (for example, the number of hops equal to 0 indicates the team leader, and the number of hops greater than 0 indicates the team Followers are equal to the minimum number of links to the team leader), so that the WTRU can implicitly determine the synchronization source type from the hop count information carried in the SL-SSB. You can use SL-SSB to broadcast the hop count. For example, the number of hops can be broadcast in PSBCH. The number of hops can be included in the information element in the PSBCH signal or carried in the PSBCH signal payload. In this case, the WTRU can implicitly determine the synchronization source type from the number of hops broadcast in the PSBCH. In another example, the hop count can be embedded in the DMRS, and the DMRS can be carried on the PSBCH. The WTRU can implicitly determine the synchronization source type from the hop count information carried in the DMRS of the PSBCH. In another example, the hop count can be carried in SPSS and/or SSSS, and can be broadcast in SPSS and/or SSSS in SLSS. In this case, the WTRU can implicitly determine the synchronization source type from the hop count information carried in the SPSS and/or SSSS. Any combination of PSBCH, DMRS, SPSS, and/or SSSS (or other synchronization signals) can be used to broadcast the hop count.

In one example, the synchronization source selection based only on S-RSRP does not consider the synchronization source type. For example, if the WTRU is closer to the team follower than the team leader, the S-RSRP from the team follower may be higher than the S-RSRP from the team leader. If S-RSRP is the only criterion for synchronization source selection, the WTRU may choose team followers instead of team leaders in some cases. In one example, the synchronization source type can also be considered as part of the synchronization source selection criteria. For example, the team leader may have a higher priority than the team follower. In one example, when the S-RSRP measurements from the team leader and team follower are higher than the threshold, even if the S-RSRP of the team follower is higher than the S-RSRP of the team leader, the WTRU can choose the team leader Rather than team followers. Therefore, the synchronization source selection may depend on the synchronization source type and the measurement or measurement type (for example, S-RSRP), and may be based on the priority order between the synchronization source type and the measurement or measurement type.

In the example, the synchronization source selection can be based on any one of the following criteria: the measurement or measurement type measured from the team leader or follower (for example, S-RSRP); the synchronization source type (for example, the team leader type, Team follower type); and/or priority and priority rules. 4 is a flowchart of an exemplary synchronization source selection method 400 based on measurement, measurement type, and synchronization source type. The exemplary synchronization source selection method 400 may be executed by a (vehicle) WTRU that wants to join a vehicle team. In this exemplary synchronization source selection method 400, the synchronization source type takes precedence over the measured (eg RSRP) value.

At 402, the WTRU may receive configuration information for side-chain communication, and the configuration information may include at least a side-chain measurement threshold. For example, the configuration information can be received from the eNB in the SIB. At 404, the WTRU may search by the synchronization source (for example, by monitoring the side chain to search for the signal from the synchronization source and/or successfully receive the side chain signal from the synchronization source, such as SLSS). At 406, the WTRU may perform measurements (eg, side-chain RSRP, side-chain correlation) on the signal (eg, SLSS) received from the synchronization source. At 408, the WTRU may compile a list of synchronization sources (from the "candidate" synchronization sources from which the WTRU is making measurements), the synchronization sources in the list having measurement values (one or more) greater than the side chain measurement threshold (for example, measured RSRP). At 410, for each synchronization source in the list, the WTRU may check the synchronization source type (eg, team leader or team follower). As described above, the synchronization source type may be determined based on implicit information (such as hop count) and/or explicit information (source type indication) carried in the SLSS received by the WTRU.

If the synchronization source type is the team leader, then at 412, the WTRU may select the team leader as the synchronization source, and at 414, establish a (side) link with the team leader so that the WTRU can obtain from the team leader Timing information. Otherwise, if there is no synchronization source of the team leader type in the list (ie, all synchronization sources in the list are team followers), then at 416, the WTRU may select the list with the highest measurement value (for example, the highest RSRP) Synchronization source. In this case, at 418, the WTRU may establish a communication (side) link with the selected team follower so that the WTRU can obtain timing information from the team follower.

5 is a flowchart of an exemplary synchronization source selection method 500 based on absolute and relative measurements, measurement types, and synchronization source types. This exemplary synchronization source selection method 500 can be executed by a (vehicle) WTRU that wants to join a vehicle team. In the exemplary synchronization source selection method 500, the synchronization source type takes precedence over the measured (eg RSRP) value. However, if the measurement value (such as RSRP) is very strong (ie, higher than the second critical value higher than the first critical value), the priority of the synchronization source type can be downgraded, and the highest measurement value (such as , The highest RSRP) synchronization source.

At 502, the WTRU may receive configuration information for side-chain communication, which includes one or more side-chain measurement thresholds. For example, the one or more side chain measurement thresholds may include the first side chain measurement threshold and the second side chain measurement threshold. At 504, the WTRU may search by the synchronization source. At 506, the WTRU may perform measurements (eg, RSRP, correlation) on the signal received from the synchronization source (eg, SLSS). At 508, the WTRU may compile a first list of synchronization sources (from synchronization sources where the WTRU is making measurements) that have a measurement value greater than the first side-chain measurement threshold (eg, measured RSRP), and information about A second list of synchronization sources of measurement values (for example, measured RSRP) of the second side chain measurement threshold, wherein the second threshold is greater than the first threshold.

At 510, for each synchronization source in the first and second lists, the WTRU may check the synchronization source type (eg, team leader or team follower). If the synchronization source type is the team leader, then at 512, the WTRU may further check whether the measurement value from the team leader (for example, the measured RSRP) is higher or lower than the second side chain measurement threshold (ie, the team leader) Is it in the second list). If the team leader’s measurement value is higher than the second side chain measurement threshold, then at 514, the WTRU may select the team leader as the synchronization source, and at 516, establish a communication (side) link with the team leader (to The WTRU can obtain timing information from the team leader). If the measurement value of the team leader is lower than the second side chain measurement threshold, then at 518, the WTRU may further check whether the measurement value of the team follower is higher or lower than the second side chain measurement threshold (ie, the second side chain measurement threshold). 2. Whether there are team followers in the list). If the measurement values of all team followers are lower than the second side chain measurement threshold, return to 514, and the WTRU can select the team leader as the synchronization source, and at 516, establish a communication (side) chain with the team leader road. If the team follower's measurement value is higher than the second sidechain measurement threshold (ie, there is a team follower on the second list), then at 520, the WTRU may select the team follower with the highest measurement value (for example, the highest RSRP) As a synchronization source, and at 522, a communication (side) link is established with the selected team follower (so that the WTRU can obtain timing information from the team follower).

In one example, the first side chain measurement threshold and the second side chain measurement threshold for the team leader may be the same as the first side chain measurement threshold and the second side chain measurement threshold for the team follower Or different. The critical value can be configured, predetermined or indicated semi-statically or dynamically. For example, the threshold may be included in the configuration information, 502.

Another example synchronization source selection method may be based on measurement type, synchronization source type and/or hop count. When the measured value based on the side chain signal from the team leader (for example, S-RSRP) is lower than the critical value, the measured value based on one or more team followers (for example, S-RSRP) is higher than the critical value In the case of, the WTRU may determine which team follower is selected as the synchronization source. If one of the team followers has a better measurement than the other or multiple team followers (e.g., S-RSRP), the WTRU may select the team follower with the highest measurement or S-RSRP (e.g., team Followers can all be the same sync source type). However, compared to another team follower who has a higher measurement value but is farther away from the team leader (ie, has a larger number of hops), is closer to the team leader (ie, has a lower number of hops) and even Team followers with lower measurement values (S-RSRP) can also be selected as the synchronization source. Therefore, in this example, the synchronization source selection may depend on the number of hops from the synchronization source (for example, in the case where the selected synchronization source is a team follower) to the team leader. If one team follower has fewer hops to the team leader (e.g., one hop) and other team followers have more hops to the leader (e.g., two hops or more), then even the measured value is lower (But above the acceptable threshold), the WTRU may also choose team followers with fewer jumps. Therefore, in addition to measurement or measurement type and/or synchronization source type, the synchronization source selection may depend on the number of hops from the synchronization source (or team follower) to the team leader.

Therefore, the exemplary method for synchronization source selection can be based on the following: measurement or measurement type measured from the team leader or team follower; synchronization source type; and/or synchronization source (or team follower) and team leader The number of hops.

FIG. 6 is a flowchart of an exemplary synchronization source selection method 600 based on measurement, measurement type, synchronization source type, and hop count. This exemplary synchronization source selection method 600 can be executed by a (vehicle) WTRU that wants to join a vehicle team. In the exemplary synchronization source selection method 600, the synchronization source type may have a higher priority than the measurement or measurement type (for example, RSRP or S-RSRP). The number of hops may have a higher priority order than measurement or measurement type. Other priority orders can be used.

At 602, the WTRU may receive configuration information for side-chain communication, the configuration information including one or more side-chain measurement thresholds. For example, the one or more side chain measurement thresholds may include the side chain measurement threshold T1, the first hop count threshold H1, and/or the second hop threshold H2. In other examples, any threshold may be pre-configured at the WTRU or received via other messaging. At 604, the WTRU may search by the synchronization source. At 606, the WTRU may perform measurements (eg, RSRP, correlation) on the signal (eg, SLSS) received from the synchronization source. At 608, the WTRU may compile a list of synchronization sources whose measurement and/or measurement type (e.g., measured RSRP or S-RSRP) is greater than the measurement threshold T1 and/or the number of hops is less than the first hop threshold H1 (e.g., This can be a combined list, or a first list based on measurement and a second list based on hop count). For example, the number of hops can count the jumps between the synchronization source and the team leader, where the team leader serves as a reference point. For example, if the synchronization source is the team leader, the hop count can be zero. If the synchronization source is a team follower, the number of hops can be 1 or greater than 1, which corresponds to the minimum number of links between the synchronization source and the team leader.

At 610, the WTRU may check the synchronization source type of the synchronization source in the list. If the type of synchronization source is the team leader, then at 612, the WTRU may select the team leader as the synchronization source, and at 614, establish a communication (side) link with the team leader (so that the WTRU can lead from the team Get timing information). Otherwise, if there is no synchronization source of the team leader type in the list (ie, all synchronization sources in the list are team followers), then at 616, the WTRU may further compare the measurement values and/or measurements between the synchronization sources Type (such as RSRP or S-RSRP) and hop count. At 618, the WTRU may determine for each synchronization source in the list whether the number of hops (ie, the number of links to the team leader) is less than the second hop threshold H2. If the hop count of one or more synchronization sources (team followers) is less than the second hop threshold H2, then at 624, the WTRU may select the synchronization source with the hop count less than the second hop threshold H2 with the highest measured value (RSRP Or S-RSRP) synchronization source (such as a team follower), and at 626, a link with the selected synchronization source is established. If for all synchronization sources between team followers, the number of hops is greater than the second hop threshold H2, then at 620, the WTRU may perform a hop that is less than the first hop threshold H1 (but not less than the second hop threshold H2). Select any synchronization source (such as any team follower) with the highest measurement value (such as the highest RSRP) from the number of synchronization sources, and at 622, it is less than the first hop threshold H1 (but not less than the second hop threshold H2). ) The synchronization source with the number of hops establishes a link with the selected synchronization source with the highest measurement.

In another example, the method used for side chain synchronization source selection may be based on synchronization source type, hop count, measurement type, and/or link capacity. For example, if a team follower has fewer hops (to the team leader), but the link (one or more) between the team follower and the team leader is weak, even if measured from the signal from the team follower The measurement value (for example, S-RSRP) is high, and the team followers may not be selected. In this case, you can select a synchronization source that has a lower measurement value (for example, S-RSRP) but has a higher measurement link between the team follower and the team leader (for example, S-RSRP). RSRP). Therefore, in the example, in addition to the measurement and/or measurement type of the link measured from the team follower, the synchronization source selection method may depend on the measurement and/or measurement of the link between the team follower and the team leader Measurement type. For example, in addition to the measurement of the link between the WTRU and the synchronization source (team follower) and/or the synchronization source type, the synchronization source selection method may depend on the synchronization source (eg team follower) to the team leader The number of hops and related measurements and/or measurement types (such as S-RSRP) associated with the hop/link between the synchronization source and the team leader.

The example synchronization source selection method can be based on any one or more of the following criteria: the measurement and/or measurement type (for example, S-RSRP) measured from the team leader or follower; the synchronization source type (for example, the team leader, Team follower); the number of hops between the synchronization source (or team follower) and the team leader; and/or measurements associated with the jumps between the synchronization source (for example, the team follower) and the team leader and/ Or measurement type (for example, S-RSRP).

FIG. 7 is a flowchart of an exemplary synchronization source selection method 700 based on measurement, measurement type, synchronization source type, hop count, and link capacity. This exemplary synchronization source selection method 700 can be executed by a (vehicle) WTRU that wants to join a vehicle team. In this exemplary synchronization source selection method 700, the synchronization source type may have a higher priority order than the measurement or measurement type (for example, S-RSRP). The number of hops can have a higher priority than the measurement or measurement type. The link capacity can also have a higher priority than the measurement or measurement type. Other priorities can be used.

At 702, the WTRU may receive configuration information for side chain communication, which may include one or more side chain measurement thresholds, one or more hop thresholds, and/or one or more link capacity thresholds. For example, the one or more side chain measurement thresholds may include a side chain measurement threshold T1, a first hop count threshold H1, a second hop threshold H2, and/or a link capacity threshold C. At 704, the WTRU may search by the synchronization source. At 706, the WTRU may perform measurements (eg, RSRP, correlation) on signals received from a synchronization source (eg, PSSS, SSSS, and/or PSBSCH signals, which may be received as part of SLSS). At 708, the WTRU may schedule measurements with greater than side chain measurement threshold T1 (eg, measured RSRP or S-RSRP) and/or hop counts less than the first hop threshold H1 and/or greater than the capacity threshold C A list of synchronization sources for link capacity (for example, this can be a combined list or a separate list, such as a first list based on measurement, a second list based on hop count, and a third list based on link capacity). The link capacity can be associated with the hop or link between the synchronization source and the team leader. The hop count may be a jump between the synchronization source and the team leader, where the team leader has a hop count equal to zero, and the team follower has a hop count greater than zero. In an example, the link capacity of a team follower with a path including one or more links to the team leader can be calculated as any of the following example capacity calculations: individual link capacity (for example, the path has The capacity of the link with the lowest capacity, which forms the bottleneck); the average link capacity of all links in the path; or the total capacity, which adds up all the links associated with the hop path between the synchronization source and the team leader The capacity of the road.

At 710, the WTRU may check the synchronization source type of the synchronization source in the list. If the type of synchronization source is the team leader, then at 712, the WTRU may select the team leader as the synchronization source, and at 714, establish a communication (side) link with the team leader (so that the WTRU can lead from the team Get timing information). Otherwise, if there is no synchronization source of the team leader type in the list (ie, all synchronization sources in the list are team followers), then at 716, the WTRU may further compare the measurements and/or measurements between the synchronization sources Type (such as RSRP or S-RSRP) and hop count. At 718, the WTRU may determine whether the hop count (ie, the number of links to the team leader) is less than the second hop threshold H2 for each synchronization source in the list. If the hop count of one or more synchronization sources (team followers) is less than the second hop threshold H2, then at 724, the WTRU can use the highest measured value (RSRP) among the synchronization sources with the hop count less than the second hop threshold H2. Or S-RSRP) select a synchronization source (for example, a team follower), and in 726, establish a link with the selected synchronization source. If for all synchronization sources between team followers, the number of hops is greater than the second hop threshold H2, then at 720, the WTRU may choose a hop that is less than the first hop threshold H1 (but not less than the second hop threshold H2) Any synchronization source with the highest link capacity among the number of synchronization sources (for example, any team follower), and at 722, and at 722, it is the same as the hop that is less than the first hop threshold H1 (but not less than the second hop threshold H2) The selected synchronization source with the highest link capacity among the number of synchronization sources establishes a link.

In another example, the synchronization source selection method may be based on the synchronization source type, number of hops, measurement type, link capacity, and/or traffic load associated with the link to the team leader. For example, the method used for synchronization source selection may be based on the following: measurement or measurement type (e.g., S-RSRP) measured from the team leader and/or team follower; synchronization source type (e.g., team leader type, team following Type); the number of hops between the synchronization source and the team leader; the measurement and/or measurement type associated with the link between the synchronization source and the team leader; the link between the synchronization source and the team leader The associated average measurement (for example, the average RSRP); the link capacity associated with the link between the synchronization source and the team leader; and/or the information associated with the link between the synchronization source and the team leader务 load.

FIG. 8 is a flowchart of an exemplary synchronization source selection method 800 based on measurement, measurement type, synchronization source type, number of hops, link capacity, and traffic load. This exemplary synchronization source selection method 800 can be executed by a (vehicle) WTRU that wants to join a vehicle team. In this exemplary synchronization source selection method 800, the synchronization source type may have a higher priority order than the measurement or measurement type (for example, S-RSRP). The number of hops can have a higher priority than the measurement or measurement type. Link capacity and/or traffic load may have a higher priority order than measurement or measurement type. Other priority orders can be used.

At 802, the WTRU may receive configuration information for side chain communication, which may include one or more side chain measurement thresholds, one or more hop thresholds, and/or one or more link capacity thresholds. For example, the one or more side chain measurement thresholds may include a side chain measurement threshold T1, a first hop count threshold H1, a second hop threshold H2, and/or a link capacity threshold C. At 804, the WTRU may search by the synchronization source. At 806, the WTRU may perform measurements (eg, RSRP, correlation) on signals received from a synchronization source (eg, PSSS, SSSS, and/or PSBSCH signals, which may be received as part of SLSS). At 808, the WTRU may schedule measurements with greater than the side chain measurement threshold T1 (eg, measured RSRP or S-RSRP) and/or hop counts less than the first hop threshold H1 and/or greater than the capacity threshold C A list of synchronization sources for link capacity (for example, this can be a combined list or a separate list, such as a first list based on measurement, a second list based on hop count, and a third list based on link capacity). The link capacity can be associated with the hop or link between the synchronization source and the team leader. The hop count may be a jump between the synchronization source and the team leader, where the team leader has a hop count equal to zero, and the team follower has a hop count greater than zero. In an example, the link capacity of a team follower with a path including one or more links to the team leader can be calculated as any of the following example capacity calculations: individual link capacity (for example, the path has The capacity of the link with the lowest capacity, which forms the bottleneck); the average link capacity on all links in the path; or the total capacity, which adds up all the links associated with the hop path between the synchronization source and the team leader The capacity of the link. In the example, the traffic load can be calculated on the link between the synchronization source and the team leader.

At 810, the WTRU may check the synchronization source type of the synchronization source in the list. If the type of synchronization source is the team leader, then at 712, the WTRU may select the team leader as the synchronization source, and at 714, establish a communication (side) link with the team leader (so that the WTRU can lead from the team Get timing information). Otherwise, if there is no synchronization source of the team leader type in the list (ie, all synchronization sources in the list are team followers), then at 816, the WTRU may further compare the signal measurements between the synchronization sources (eg RSRP) and the number of hops (and/or link capacity and/or traffic load) associated with the hop/link. At 818, the WTRU may determine for each synchronization source in the list whether the hop count (ie, the number of links to the team leader) is less than the second hop threshold H2. If the number of hops is less than the second hop threshold H2, then at 824, the WTRU may select a synchronization source (such as a team follower) with a hop number less than the second hop threshold H2 and the lowest traffic load among the synchronization sources, and At 826, a link with the selected synchronization source is established. If for all synchronization sources in the team’s followers, the number of hops is greater than the second hop threshold H2, then at 820, the WTRU may have a hop number less than the first hop threshold H1 (but not less than the second hop threshold H2) Select any synchronization source with the highest link capacity (for example, any team follower) among the synchronization sources, and at 822, and in the hop with less than the first hop threshold H1 (but not less than the second hop threshold H2) The selected synchronization source with the highest link capacity among the number of synchronization sources establishes a link.

9 is a flowchart of an exemplary synchronization source selection method 900 based on measurement, measurement type, synchronization source type, and hop count. This exemplary synchronization source selection method 900 can be executed by a (vehicle) WTRU that wants to join a vehicle team. In 902, the WTRU may receive configuration information for side-chain communication, which may include one or more side-chain measurement thresholds, hop count thresholds, and/or link capacity thresholds. For example, the side chain configuration information may include a first side chain measurement threshold T1, a second side chain measurement threshold T2, and a hop count (hop count) threshold H. In an example, the second side chain measurement threshold T2 is greater than the first side chain measurement threshold T1.

At 904, the WTRU may search by the synchronization source. At 906, the WTRU may perform measurements (eg, RSRP, correlation) on the signal (eg, SLSS) received from the synchronization source. At 908, the WTRU may determine the synchronization source type for each synchronization source, and at 909, the WTRU may determine the number of hops for each synchronization source. In one example, the WTRU may determine the synchronization source type and/or the number of hops for each synchronization source based on the information carried in the SLSS received from the respective synchronization sources, for example, based on the information carried in the SPSS, SSSS, and/or PSBCH signals. In one example, the SPSS, SSSS, and/or PSBCH signal may carry a synchronization source type indicator, which explicitly indicates the synchronization source type (for example, team leader type or team follower type) to the WTRU. In one example, the SPSS, SSSS, and/or PSBCH signal may carry a hop count field, which indicates to the WTRU the number of hops or links between the synchronization source and the team leader. In one example, the SLSS may not include the synchronization source type indicator, and the WTRU may determine the synchronization source type of each synchronization source based on the hop count field received in the SLSS (for example, the hop count equals 0 to indicate the team Leader, hop count greater than 0 indicates team follower).

At 910, the WTRU may compile a synchronization source list (from the synchronization source from which the WTRU is making measurements), the synchronization sources in the list having a measurement value (eg, measured RSRP) greater than the first side chain measurement threshold T1. At 912, the WTRU may consider the synchronization source type of the synchronization source in the list. If the type of synchronization source is the team leader, then at 914, the WTRU may select the team leader as the synchronization source, and at 916, establish a communication (side) link with the team leader (so that the WTRU can lead from the team Get timing information). Otherwise, if there is no synchronization source of the team leader type in the list (ie, all synchronization sources in the list are team followers), then at 918, the WTRU may further compare the hop count of the synchronization source. At 920, the WTRU may determine whether the number of hops (ie, the number of links to the team leader) is less than the hop threshold H for each synchronization source in the list. If the hop count is less than the hop threshold H, then at 924, the WTRU may select a synchronization source (such as a team follower) among the synchronization sources whose hop count is less than the hop threshold H, and at 916, establish a synchronization source with the selected synchronization source (at In this case, team followers) link. If for all synchronization sources between team followers, the number of hops is greater than the hop threshold H, then at 922, the WTRU may select a synchronization source whose measurement value (for example, measured RSRP) is greater than the second measurement threshold T2 (team follower ), and at 916, a link with the selected synchronization source (in this case, the team follower) is established.

In another example, the method for side chain synchronization and source selection may be based on one or more of the following: source type, hop count, parameter configuration (for example, subcarrier spacing (SCS), cyclic prefix (CP)), Bandwidth part (BWP), link capacity and/or traffic load (associated with the jump between the synchronization source and the team leader). The WTRU may receive side-chain configuration information. The side-chain configuration information may include one or more thresholds corresponding to measurement, hop count, link capacity, and/or traffic load. The method used for side-chain synchronization and source selection can be based on any of the following criteria: measurement and/or measurement type (e.g., S-RSRP or RSRP) measured from team leader or follower; synchronization source type (e.g. , Team leader type, team follower type); synchronization source or the number of jumps between the team follower and the team leader; related to the synchronization source or the jump or jump path between the team follower and the team leader Measurement and/or measurement type (for example, S-RSRP); average measurement associated with synchronization source or jump between team follower and team leader (for example, average S-RSRP); with synchronization source or team follower The link capacity associated with the jump and/or jump path between the team leader; the traffic load associated with the synchronization source or the jump and/or jump path between the team follower and the team leader; and The bandwidth associated with the jump and/or jump path between the synchronization source or the team follower and the team leader; the bandwidth associated with the jump and/or jump path between the synchronization source or the team follower and the team leader Parameter configuration; the number of resource blocks associated with the synchronization source or the jump and/or jump path between the team follower and the team leader; and/or the synchronization source or the jump between the team follower and the team leader The number of bandwidth parts (BWP) associated with the hopped path. Different combinations of selection criteria and/or priority order can be applied to the above information or parameters to optimize synchronization, including V2X side chain synchronization.

The method can be used for side chain synchronization to assist information communication. The synchronization assistance information may include any one or more of the following information: the measurement and/or measurement type; synchronization source type; hop count or hop sequence: average or total measurement associated with the hop or the path of the hop (for example, S-RSRP); the link capacity associated with the hop or hop path; and/or the traffic load associated with the hop or hop path. For example, the WTRU may collect any of the following information or any of the following information may be signaled to the WTRU: Measurements and/or measurement types (e.g., S-RSRP or RSRP) measured from the team leader or team follower ); synchronization source type (for example, team leader type, team follower type); the number of hops between the synchronization source and the team leader; related to the jump and/or jump path between the synchronization source and the team leader The measurement and/or measurement type (for example, S-RSRP); the average and/or total measurement and/or associated with the jump and/or jump path between the synchronization source (for example, the team follower) and the team leader Measurement type (such as S-RSRP); capacity associated with the jump and/or jump path between the synchronization source and the team leader; and/or the jump and/or jump between the synchronization source and the team leader The load associated with the path.

In one example, the following information can be broadcast or communicated to the WTRU for the selection of the V2X side chain synchronization source: measurement and/or measurement type (for example, S-RSRP); hop count or hop sequence from synchronization source to team leader; The capacity associated with the hop's path; the traffic load associated with the hop's path; the parameter configuration associated with the hop's path; the BWP information associated with the hop's path; and/or include the synchronization source Priority order of priority. For example, the hop count, synchronization source type, and/or synchronization source priority order may be broadcast from one WTRU to other WTRUs. The WTRU may determine and select a synchronization source based on any one or more of the number of hops, synchronization source type, and/or synchronization source priority.

The team leader (or any WTRU including team followers) may communicate the synchronization assistance information to the WTRU. For example, the team leader can broadcast, multicast, or unicast synchronized auxiliary information to one, plural, or all WTRUs. The WTRU may report information related to the synchronized auxiliary information to the team leader. The team leader can gather all the information reported from the WTRU, convert the received information into a set of synchronized auxiliary information, and convey the updated synchronized auxiliary information back to the WTRU.

Example methods can be used to communicate the synchronization assistance information to the WTRU. For example, the NR physical side chain control channel (NR-PSCCH) can be used to convey synchronization assistance information to the WTRU. In another example, SLSS or PSBCH can be used to send the synchronization assistance information to the WTRU. In another example, a side-chain group common control channel (for example, SL-GC-PDCCH), which can be a physical downlink control channel (PDCCH), can be used to send synchronization assistance information to the WTRU. In another example, the group common control entity side chain control channel (GC-SL-PSCCH or GC-PSCCH) or the group common control entity side chain common channel (GC-SL-PSSCH or GC-PSSCH) can be used , And can be multicast, unicast or broadcast or transmitted on demand.

In another example, side chain system information can be used. The side chain system information may include side chain residual minimum system information (SL-RMSI) and/or side chain other system information (SL-OSI), which can be broadcast, multicast, unicast, or transmitted on demand. In another example, a side-chain random access channel (SL-RACH) can be used. SL-RACH can include a two-step or four-step RACH method. For example, side chain message 1 (SL-MSG1) and/or message 2 (SL-MSG2) can be used in the two-step RACH method. In addition, side chain message 3 (SL-MSG3) and/or message 4 (SL-MSG4) can be used in the four-step RACH method. SL-RACH can be used to request synchronization of auxiliary information for broadcast, multicast, unicast, or on-demand for synchronization of auxiliary information. SL-RACH can be used to send the synchronization auxiliary information via broadcast, multicast, unicast or on-demand.

In one example, the synchronization information can be divided into two (or more) groups, such as the first synchronization auxiliary information and the second synchronization auxiliary information. The second synchronization assistance information may have a higher priority order than the first synchronization assistance information. Additional priority rules can be applied to each set of synchronized auxiliary information. For example, a set of priority rules can be used in the first synchronized auxiliary information. Another set of priority rules can be used for the second synchronization auxiliary information.

The first synchronization assistance information may be delivered in a semi-static or dynamic manner, and the second synchronization assistance information may be delivered in a dynamic manner (or a semi-static manner). In an example, the second synchronization assistance information can override the first synchronization assistance information. The replacement indicator can be carried in the synchronization auxiliary information. For example, the replacement indicator can be carried in the second synchronization auxiliary information. When the WTRU receives the second synchronization assistance information, the WTRU may check the replacement indicator. If the replacement indicator indicates replacement or "on", the WTRU may replace the first synchronization assistance information with the second synchronization assistance information. The WTRU may use the second synchronization assistance information for synchronization source selection. If the replacement indicator indicates "non-replacement" or "off," the WTRU may append the second synchronization assistance information to the first synchronization assistance information. In this case, the WTRU may use both the first synchronization assistance information and the second synchronization assistance information to assist in synchronization source selection.

The first synchronization assistance information and the second synchronization assistance information may be delivered in different cycles, resources, and/or via different signals or channels. For example, the first synchronization assistance information may be delivered less frequently (for example, in a larger period), and the second synchronization assistance information may be delivered more frequently (for example, in a smaller period). The first synchronization assistance information can be delivered using NR-PSCCH, and the second synchronization assistance information can be delivered using SL-GC-PDCCH. In another example, PSSS, SSSS, and/or PSBCH may be used to deliver the first synchronization assistance information, and PSCCH or SL-GC-PDCCH may be used to deliver the second synchronization assistance information. The first synchronization assistance information may be delivered in a periodic manner, and the second synchronization assistance information may be delivered in a non-periodical manner or an event-triggered manner. The above different combinations can be used to optimize V2X side chain synchronization.

FIG. 10 is a flowchart of an exemplary method 1000 for synchronizing auxiliary information for NR V2X side chains, which can be executed by a WTRU as a member of a vehicle team. At 1002, the WTRU may receive the side chain synchronization configuration. At 1004, the WTRU may receive the first side chain synchronization assistance information. At 1006, the WTRU may receive a priority order rule for the first side chain synchronization parameter. At 1008, the WTRU may receive the second side chain synchronization assistance information. At 1010, the WTRU may receive a priority order rule for the second side chain synchronization parameter. At 1012, the WTRU may select a synchronization source based on the synchronization assistance information and the priority rules associated with the first synchronization assistance information and the second synchronization assistance information. The synchronization method and synchronization source selection method for the V2X side chain can be based on any combination or subset of the sub-components of the method and technology herein.

Although the features and elements in a specific combination or order are described above, those of ordinary skill in the art will recognize that each feature or element can be used alone or in any combination with other features and elements. In addition, the method described herein can be implemented in a computer program, software, or firmware introduced into a computer-readable medium for a computer or a processor to run. Examples of computer-readable media include electrical signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), register, cache, semiconductor memory devices, such as internal hard drives and removable hard drives Magnetic media such as discs, magneto-optical media, and optical media such as CD-ROM hard drives and digital versatile hard drives (DVDs). The processor associated with the software can be used to implement a radio frequency transceiver for use in a WTRU, WTRU, terminal, base station, RNC, or any host computer.

C: Link capacity threshold H1: The critical value of the first hop H2: Second jump threshold N2, N3, N4, N6, N11, S1, X2, Xn: Interface PSBCH: physical side chain broadcast channel SL: side chain SSSS: auxiliary side chain synchronization signal T1: Side chain measurement threshold RSRP: Reference signal received power 100: Communication system 102, 102a, 102b, 102c, 102d, 201, 301: wireless transmission/reception unit (WTRU) 104/113: Radio Access Network (RAN) 106/115: Core Network (CN) 108: Public Switched Telephone Network (PSTN) 110: Internet 112: other networks 114a, 114b: base station 116: Air Interface 118: processor 120: Transceiver 122: transmission/reception element 124: speaker/microphone 126: Small keyboard 128: display/touchpad 130: non-removable memory 132: removable memory 134: Power 136: Global Positioning System (GPS) Chipset 138: Peripheral Equipment 160a, 160b, 160c: eNodeB 162: Mobility Management Entity (MME) 164: Service Gateway (SGW) 166: Packet Data Network (PDN) Gateway (or PGW) 180a, 180b, 180c: gNB 182a, 182b: Access and mobility management function (AMF) 183a, 183b: Conversation Management Function (SMF) 184a, 184b: User Plane Function (UPF) 185a, 185b: data network (DN) 200: Example side chain WTRU information exchange process 202: gNB/eNB 204: System Information Block (SIB) Type 21 (SIB21) 206: Sidechain WTRU Information 208: RRCConnectionReconfiguration (RRC connection reconfiguration) message 300: Vehicle Team 302, 304, 306: Team Leader (PL) WTRU 310:PL SL-SYNC 312: H1 SL-SYNC 314: H2 SL-SYNC 400, 500, 600, 700, 800, 900: Example synchronization source selection method 602, 604, 606, 608, 610, 612, 614, 616, 618, 620, 622, 624, 626: process 1000: Example synchronization method of auxiliary information

A more detailed understanding can be obtained from the following description given by way of example in conjunction with the drawings, in which the same reference numerals in the drawings denote the same elements, and in which: Figure 1A is a system diagram illustrating an exemplary communication system in which one or more of the disclosed embodiments may be implemented. FIG. 1B is a system diagram showing an exemplary wireless transmission/reception unit (WTRU) that may be used in the communication system shown in FIG. 1A according to an embodiment. FIG. 1C is a system diagram showing an example radio access network (RAN) and an example core network (CN) that can be used in the communication system shown in FIG. 1A according to an embodiment. FIG. 1D is a system diagram showing another example RAN and another example CN that can be used in the communication system shown in FIG. 1A according to an embodiment. Figure 2 is a signaling diagram of an exemplary side-chain WTRU information exchange process for communication between a (vehicle) WTRU and an eNB for vehicle-to-everything (V2X) side-chain transmission; Figure 3 is a network diagram of an example vehicle team including team leaders and team followers; Figure 4 is a flowchart of an exemplary synchronization source selection method based on measurement, measurement type, and synchronization source type; Figure 5 is a flowchart of an exemplary synchronization source selection method based on absolute and relative measurement, measurement type, and synchronization source type; Figure 6 is a flowchart of an exemplary synchronization source selection method based on measurement, measurement type, synchronization source type, and hop count; Figure 7 is a flowchart of an exemplary synchronization source selection method based on measurement, measurement type, synchronization source type, hop count, and link capacity; Figure 8 is a flowchart of an exemplary synchronization source selection method based on measurement, measurement type, synchronization source type, hop count, link capacity, and traffic load; Figure 9 is a flowchart of an exemplary synchronization source selection method based on measurement, measurement type, synchronization source type, and hop count; and Figure 10 is a flowchart of an exemplary method of synchronizing auxiliary information for NR V2X sidechains, which can be executed by a WTRU as a member of a vehicle team.

H1: The critical value of the first hop

H2: Second jump threshold

RSRP: Reference signal received power

T1: Side chain measurement threshold

600: Example synchronization source selection method

602, 604, 606, 608, 610, 612, 614, 616, 618, 620, 622, 624, 626: process

Claims (20)

A wireless transmission/reception unit (WTRU) configured to select a synchronization source in a fleet of vehicles, the WTRU including: A transceiver; and A processor, where The transceiver is configured to receive configuration information for side-chain communication, where the configuration information includes at least a first side-chain measurement threshold, a second side-chain measurement threshold, and a first hop count threshold; The transceiver is configured to monitor at least one side chain channel for signals from a plurality of synchronization sources, where the synchronization source is a WTRU in the vehicle fleet; The transceiver is configured to perform side-chain measurements on side-chain synchronization signals from each of the complex synchronization sources; The processor is configured to determine the synchronization source type and hop count of each of the plurality of synchronization sources based on the information carried in the respective side chain synchronization signals; The processor is configured to compile a list of one of the synchronization sources from the plurality of synchronization sources, and a value measured by the side chain is greater than the first side chain measurement threshold; The processor is configured to select the synchronization source with the team leader type when a synchronization source in the list of synchronization sources is a team leader synchronization source type; The processor is configured to, in the case that no synchronization source in the list of synchronization sources is a team leader synchronization source type: In the case that a synchronization source in the list of synchronization sources has a hop count less than the first hop count threshold, select the synchronization source that has a hop count less than the first hop count threshold; In a case where there is no synchronization source in the list of synchronization sources that has a hop count less than the first hop count threshold, select the synchronization source whose value measured by the side chain is greater than the second side chain measurement threshold; as well as The transceiver is configured to establish a link with the selected synchronization source. The WTRU according to claim 1, wherein the configuration information is received in a system information block (SIB) from an evolved node B (eNB). The WTRU according to claim 1, wherein the configuration information further includes a first link capacity threshold. The WTRU of claim 1, wherein the transceiver is configured to perform side chain measurements according to at least one of the following: reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-noise ratio (SNR) ), signal to interference ratio (SINR) or correlation. The WTRU according to claim 1, wherein the information carried in the side chain synchronization signal includes a synchronization source type indicator indicating one of a team leader type and a team follower type, and the processor It is configured to determine the synchronization source type of each of the plurality of synchronization sources based on the synchronization source type indicator. The WTRU according to claim 1, wherein the information carried in the side-chain synchronization signal includes a hop count field, the hop count field indicating a number of links between the synchronization source and a team leader , And the processor is configured to determine the hop count of each of the plurality of synchronization sources based on the hop count field. The WTRU according to claim 6, wherein the processor is configured to determine the synchronization source type of each of the plurality of synchronization sources based on the hop count field, such that a hop count of 0 indicates a team Leader type, and a hop count greater than zero indicates a team follower type. The WTRU according to claim 1, wherein the side chain synchronization signal includes at least one of the following signals: a primary side chain synchronization signal (PSSS), a secondary side chain synchronization signal (SSSS), and a physical side chain broadcast A signal carried on the channel (PSBCH), a side chain synchronization signal block (SL-SSB), a channel status information reference signal (CSI-RS), or a PSBCH demodulation reference signal (PSBCH-DMRS). The WTRU of claim 1, wherein the transceiver is further configured to receive a signal including timing information from the selected synchronization source. For the WTRU described in claim 1, the WTRU is configured as a vehicle WTRU. A method for selecting a synchronization source in a vehicle fleet executed by a wireless transmission/reception unit (WTRU), the method includes: Receiving configuration information for side-chain communication, where the configuration information includes at least a first side-chain measurement threshold, a second side-chain measurement threshold, and a first hop count threshold; Monitor at least one side chain channel for signals from a plurality of synchronization sources, where the synchronization source is a WTRU in the vehicle fleet; Perform side-chain measurement on the side-chain synchronization signal from each of the complex synchronization sources; Determine the synchronization source type and the number of hops for each of the complex synchronization sources based on the information carried in the respective side chain synchronization signals; Compiling a list of one of the synchronization sources from the plurality of synchronization sources, and a value measured by the side chain is greater than the first side chain measurement threshold; In a case where a synchronization source in the list of synchronization sources is the team leader synchronization source type, select the synchronization source with the team leader type; In the case that no synchronization source in the list of synchronization sources is a team leader synchronization source type: In a case in which a synchronization source in the list of synchronization sources has a hop count less than the first hop count threshold, select the synchronization source that has a hop count less than the first hop count threshold; In the case that no synchronization source in the list of synchronization sources has a hop count less than the first hop count threshold, select the same step source whose value measured by the side chain is greater than the second side chain measurement threshold; as well as A link with the selected synchronization source is established. The method according to claim 11, wherein the configuration information is received in a system information block (SIB) from an evolved node B (eNB). The method according to claim 11, wherein the configuration information further includes a first link capacity threshold. The method according to claim 11, wherein the execution of the side chain measurement is based on at least one of the following: reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-noise ratio (SNR), signal interference Ratio (SINR) or correlation. The method according to claim 11, wherein the information carried in the side-chain synchronization signal includes a synchronization source type indicator indicating one of a team leader type and a team follower type, and the determination is The synchronization source type of each synchronization source in the plural synchronization sources is based on the synchronization source type indicator. The method according to claim 11, wherein the information carried in the side-chain synchronization signal includes a hop count field, and the hop count field indicates a number of links between the synchronization source and a team leader, And the determination of the hop count of each of the plurality of synchronization sources is based on the hop count field. The method according to claim 16, wherein the determination of the synchronization source type of each of the plurality of synchronization sources is based on the hop count field, so that a hop count of 0 indicates the team leader type, and is greater than A hop count of zero indicates a team follower type. The method according to claim 11, wherein the side chain synchronization signal includes at least one of the following signals: a primary side chain synchronization signal (PSSS), a secondary side chain synchronization signal (SSSS), and a physical side chain broadcast A signal carried on the channel (PSBCH), a side chain synchronization signal block (SL-SSB), a channel status information reference signal (CSI-RS), or a PSBCH demodulation reference signal (PSBCH-DMRS). The method according to claim 11, further including: A signal including timing information is received from the selected synchronization source. The method of claim 11, wherein the WTRU is a vehicle WTRU.

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