JP2022139370A - System, wireless terminal device, vehicle, control device, base station, method, and program that perform selection control of wireless resource allocation control mode in inter-terminal direct communication - Google Patents

Abstract

To appropriately select a wireless resource allocation control mode for allocating wireless resources for inter-terminal direct communication to a plurality of UEs within the same group, and ensure low-delay and highly reliable inter-terminal direct communication within the same group.SOLUTION: As a wireless resource allocation control mode for allocating wireless resources for inter-terminal direct communication to a plurality of UEs 20 belonging to a group, are selectable a first mode in which a base station allocates a wireless resource for inter-terminal direct communication, and a second mode in which any of the plurality of UEs allocates a wireless resource of inter-terminal direct communication. A base station 10 checks whether all UEs in the group are located within a cell coverage of the base station 10 and are in a synchronized state in which the UEs have completed wireless connection setting with the base station 10 and synchronized with the base station 10, and when confirming that all the UEs in the group are in a synchronized state with the base station 10, the base station 10 transmits, to the plurality of UEs, resource control information for inter-terminal direct communication including a first mode allowance message allowing an operation in the first mode.SELECTED DRAWING: Figure 8

Description

TECHNICAL FIELD The present invention relates to selection control of a radio resource allocation control mode in inter-terminal direct communication of a plurality of radio terminal devices capable of communicating via a base station of a mobile communication network. The present invention relates to selection control of a radio resource allocation control mode in direct communication between terminals when forming a group.

Conventionally, between short-range devices (D2D: Device-to- A communication method is known in which direct wireless communication is performed using a device). In particular, V2X using cellular communication technology of mobile communication systems is also called "cellular V2X."

LTE (Long Term Evolution) and next-generation (NR) specifications of 3GPP (3rd Generation Partnership Project) require communication between short-range devices such as V2V, V2I, V2P, and V2X without going through a mobile communication network (core network). D2D), a standard specification of a Sidelink communication method for direct wireless communication using an interface called PC5 has been established (see, for example, Non-Patent Documents 1, 2, 3, and 4).

As radio resource allocation control modes in the Sidelink communication system, a mode SL Mode-1 (hereinafter referred to as "first mode") in which the base station allocates Sidelink radio resources, and a mode in which the radio terminal device itself allocates Sidelink radio resources. SL Mode-2 (hereinafter also referred to as “second mode”) is known (see, for example, Patent Document 1 and Non-Patent Document 1). The first mode has the advantage of realizing efficient direct communication between terminals (between in-vehicle terminals) by sidelink radio resource allocation control from the base station within the range of the cell of the base station. Since the necessary synchronization and selection of radio resources depend on the synchronization signal and control signal transmitted by the base station, there is a problem that it cannot be applied outside the cell area of the base station. On the other hand, in the second mode, the wireless terminal device can autonomously communicate by detecting or randomly selecting necessary wireless resources without relying on the base station. On the other hand, especially when there are many terminals that perform autonomous direct communication between terminals, the signals transmitted by the terminals collide with each other, increasing the rate of mutual interference, and as a result, the quality of direct communication between terminals deteriorates. The problem is that it is easy.

EP 3136811

Pavel Mach, Zdenek Becavar, and Tomas Vanek, "In-Band Device-to-Device Communication in OFDMA Cellular Networks: A Survey and Challenges," IEEE Communication Serveys & Tutorials, vol.17, no.4, pp.1885-1922 , June 2015. 3GPP TR22.886 V16.2.0, "Study on enhancement of 3GPP support for 5G V2X services (Release 16)," Dec. 2018. 3GPP TR37.985 V16.0.0, "Overall description of Radio Access Network (RAN) aspects for Vehicle-to-everything (V2X) based on LTE and NR (Release 16)," June 2020. 3GPP TR38.885 V16.0.0, "Study on NR Vehicle-to-Everything (V2X) (Release 16)," March 2019.

In recent years, radio resource allocation control mode selection control ( Also called "Dynamic Mode Selection" or "Dynamic Mode Switching") has been proposed.

However, for example, one or a plurality of wireless terminal devices can be used to transmit control messages between vehicles required for platooning of following vehicles or to share real-time information such as position information, speed information, and acceleration information between multiple vehicles. When a group (group) is formed and direct communication is performed between terminals (between in-vehicle terminals) within the same group, the radio resource allocation control mode of a plurality of radio terminal apparatuses within the same group must be the same. Therefore, there is a problem that it is desirable to appropriately select the radio resource allocation control mode in a plurality of radio terminal apparatuses in the same group, and to ensure low-delay and high-reliability direct communication between terminals in the same group. .

A system according to an aspect of the present invention performs selection control of a radio resource allocation control mode when a plurality of radio terminal apparatuses capable of communicating via a base station of a mobile communication network form a group and perform direct communication between terminals. It is a system that does In this system, as a radio resource allocation control mode for allocating radio resources for inter-terminal direct communication of the plurality of radio terminal devices belonging to the group, the base station allocates radio resources for inter-terminal direct communication to the plurality of radio terminal devices. A first mode and a second mode in which one of the plurality of wireless terminal devices allocates wireless resources for inter-terminal direct communication of the plurality of wireless terminal devices can be selected. In this system, all of the plurality of wireless terminal devices belonging to the group are located within the range of the cell of the base station, complete wireless connection setup with the base station, and perform downlink communication with the base station. and means for checking whether or not the uplink is in a synchronized state, and if all the plurality of wireless terminal devices belonging to the group are confirmed to be in a synchronized state with the base station, the first mode means for transmitting, to the plurality of wireless terminal devices, resource control information for the direct terminal communication including a first mode allowable message allowing operation of the terminal-to-terminal direct communication.

In the system, the resource control information for direct communication between terminals may include group identification information that can identify the group or terminal identification information for each of a plurality of wireless terminal devices belonging to the group.

In the system, any one of the plurality of wireless terminal devices belonging to the group is configured to receive the resource control information for the inter-terminal direct communication by all the plurality of wireless terminal devices belonging to the group. means for checking whether or not the downlink and the uplink are synchronized with the base station, and all other wireless terminal devices other than the wireless terminal device belonging to the group; means for transmitting a mode designation message designating the first mode to all the other wireless terminal devices when confirming that they are in a state of synchronization with the base station; and means for checking whether the mode designation message has been successfully received. Here, when all the plurality of wireless terminal devices belonging to the group successfully receive the mode designation message, the one wireless terminal device or all the plurality of wireless terminal devices belonging to the group are in the first mode. A request message requesting resource allocation control based on the base station may be transmitted to the base station side.

In the system, all the plurality of wireless terminal devices belonging to the group are connected to the base station after completion of receiving the resource control information for the direct communication between terminals. means for confirming whether or not the downlink and uplink are in a synchronized state between the base stations; means for transmitting a mode designation message designating the first mode to all of the other wireless terminal devices when confirming that they are in a synchronized state; and receiving the mode designation message by all of the other wireless terminal devices. and means for confirming whether or not successful. Here, when all of the plurality of wireless terminal devices belonging to the group successfully receive the mode designation message, all the plurality of wireless terminal devices belonging to the group are connected to all the plurality of wireless terminals belonging to the group. A request message may be sent to the base station side to request resource control of direct terminal-to-terminal communication of the device.

In the system, the one wireless terminal device or all of the plurality of wireless terminal devices belonging to the group have completed reception of resource control information for the inter-terminal direct communication and are in a synchronized state with the base station. It may be confirmed that all the other wireless terminal devices are in the synchronized state by receiving synchronization state information indicating that the wireless terminal devices are in the synchronized state. Here, the one wireless terminal device or all of the plurality of wireless terminal devices belonging to the group receive group identification information capable of identifying the group together with the synchronization state information from all of the other wireless terminal devices. You may

In the system, the group may be statically formed by a plurality of preset wireless terminal devices, or ad-hoc formed by a plurality of wireless terminal devices located close to each other.

In the system, the wireless terminal device may be provided in each of a plurality of vehicles that form the group and run on the moving route.

A wireless terminal device according to another aspect of the present invention is a wireless terminal that can communicate via a base station of a mobile communication network, forms a group with one or a plurality of nearby wireless terminal devices, and performs direct communication between terminals. It is a device. This radio terminal device is in a synchronized state in which all the plurality of radio terminal devices belonging to the group have completed reception of the resource control information for the direct communication between terminals and have synchronized downlinks and uplinks with the base station. means for confirming whether or not the base station is in synchronization with the base station; means for transmitting a mode designation message that designates the first mode to all the wireless terminal devices; means for confirming whether or not all the other wireless terminal devices have successfully received the mode designation message; Prepare.

A vehicle according to still another aspect of the present invention is a vehicle that travels along a moving route in a group with another vehicle, and includes the wireless terminal device.

A control device according to still another aspect of the present invention provides a radio resource allocation control mode when a plurality of radio terminal devices capable of communicating via a base station of a mobile communication network form a group and perform direct communication between terminals. It is a control device that performs selection control. In this control device, as a radio resource allocation control mode for allocating radio resources for inter-terminal direct communication of the plurality of radio terminal devices belonging to the group, the base station allocates radio resources for inter-terminal direct communication to the plurality of radio terminal devices. A first mode for allocation and a second mode for allocating radio resources for inter-terminal direct communication of the plurality of radio terminal devices by one of the plurality of radio terminal devices can be selected. This control device is configured so that all the plurality of wireless terminal devices belonging to the group are located within the range of the cell of the base station, have completed wireless connection setup with the base station, and are ready for downlink with the base station. means for confirming whether or not a link and an uplink are in a synchronized state, and if confirming that all the plurality of wireless terminal apparatuses belonging to the group are in a synchronized state with the base station, means for transmitting, to the plurality of wireless terminal devices, resource control information for the direct terminal communication including a first mode allow message allowing mode operation.

The control device is a base station of a mobile communication network, a node between the base station and the core network, or a CU (Central Unit) or MEC (Multi-access Edge Computing) device provided outside the core network, good too.

A base station according to still another aspect of the present invention is a base station of a mobile communication network and includes the control device.

A method according to still another aspect of the present invention selects a radio resource allocation control mode when a plurality of radio terminal apparatuses capable of communicating via a base station of a mobile communication system form a group and perform inter-terminal direct communication. It is a method of control. In this method, as a radio resource allocation control mode for allocating radio resources for inter-terminal direct communication of a plurality of radio terminal devices belonging to the group, the base station allocates radio resources for inter-terminal direct communication to the plurality of radio terminal devices. making it possible to select from a first mode and a second mode in which any one of the plurality of wireless terminal devices allocates wireless resources for inter-terminal direct communication of the plurality of wireless terminal devices; Synchronization in which all of the belonging wireless terminal devices are located within the range of the cell of the base station and radio connection setup is completed with the base station, and the downlink and uplink are synchronized with the base station. and confirming whether all the plurality of wireless terminal devices belonging to the group are in a synchronized state with the base station, a first mode permitting operation in the first mode. and transmitting resource control information for the direct terminal communication including a mode allow message to the plurality of wireless terminal devices.

A program according to still another aspect of the present invention selects a radio resource allocation control mode when a plurality of radio terminal apparatuses capable of communicating via a base station of a mobile communication system form a group and perform direct communication between terminals. It is a program executed in a computer or processor provided in a control device that performs control. This program is a radio resource allocation control mode for allocating radio resources for inter-terminal direct communication of the plurality of radio terminal devices belonging to the group, wherein the base station allocates radio resources for inter-terminal direct communication to the plurality of radio terminal devices. a program code for enabling selection from a first mode and a second mode in which any one of the plurality of wireless terminal devices allocates radio resources for inter-terminal direct communication of the plurality of wireless terminal devices; All of the plurality of wireless terminal devices belonging to the group are located within the range of the cell of the base station, have completed wireless connection setup with the base station, and have downlink and uplink connections with the base station. a program code for checking whether it is in a synchronized synchronized state; and program code for transmitting to the plurality of wireless terminals resource control information for the direct terminal communication including a first mode allowable message allowing operation.

A program according to still another aspect of the present invention is a wireless terminal device capable of communicating via a base station of a mobile communication network, forming a group with one or a plurality of nearby wireless terminal devices, and performing inter-terminal direct communication. is a program executed on a computer or processor provided in the . According to this program, all the plurality of wireless terminal devices belonging to the group are in a synchronous state in which the reception of the resource control information for the direct communication between terminals is completed and the downlink and uplink are synchronized with the base station. and a program code for confirming whether or not all wireless terminal devices belonging to the group other than the wireless terminal device itself are in a synchronized state with the base station; Program code for transmitting a mode designation message designating the first mode to all other wireless terminals, and checking whether all the other wireless terminals have successfully received the mode designation message. program code for

The second mode may be selected as the initial radio resource allocation control mode in each of the system, the radio terminal device, the vehicle, the control device, the base station, the method and the program.

According to the present invention, when direct communication is performed between terminals within a group formed of a plurality of wireless terminal devices capable of communicating via a base station of a mobile communication network, a plurality of wireless terminal devices within the same group can be connected to a terminal. By appropriately selecting a radio resource allocation control mode for allocating radio resources for inter-terminal direct communication, low-delay and highly reliable terminal-to-terminal direct communication can be reliably performed within the same group.

1 is a schematic configuration diagram showing an example of the overall configuration of a communication system according to an embodiment; FIG. FIG. 4 is an explanatory diagram showing an example of radio frames of downlink (DL) and uplink (UL) of Uu communication and sidelink communication (SL) in the communication system according to the embodiment; FIG. 4 is an explanatory diagram showing another example of radio frames of downlink (DL) and uplink (UL) of Uu communication and sidelink communication (SL) in the communication system according to the embodiment; FIG. 4 is an explanatory diagram showing still another example of radio frames of downlink (DL) and uplink (UL) of Uu communication and sidelink communication (SL) in the communication system according to the embodiment; (a) and (b) are explanatory diagrams showing an example of a first radio resource allocation control mode (SL Mode-1) in the communication system according to the embodiment. (a) and (b) are explanatory diagrams showing an example of a second radio resource allocation control mode (SL Mode-2) in the communication system according to the embodiment. 4 is an explanatory diagram showing an example of dynamic switching control of radio resource allocation control modes (SL Mode-1, SL Mode-2) in the communication system according to the embodiment; FIG. 4 is a sequence diagram showing an example of dynamic switching control from a second radio resource allocation control mode (SL Mode-2) to a first radio resource allocation control mode (SL Mode-1) in the communication system according to the embodiment; FIG. 4 is a sequence diagram showing another example of dynamic switching control from the second radio resource allocation control mode (SL Mode-2) to the first radio resource allocation control mode (SL Mode-1) in the communication system according to the embodiment; FIG. FIG. 4 is a sequence diagram showing an example of determining a connection state between a UE and a base station in the communication system according to the embodiment; FIG. 3 is a sequence diagram showing an example of synchronization establishment of Sidelink communication (SL) of UEs located within the range of a cell of a base station in the communication system according to the embodiment and determination of the connection state; FIG. 4 is a sequence diagram showing an example of synchronization establishment and connection state determination of Sidelink communication (SL) of a UE located outside the service area of a cell of a base station in the communication system according to the embodiment;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The system according to the embodiment described in this document is a system that, when a plurality of vehicles such as trucks are platooning, is mounted on a plurality of vehicles that can communicate via a base station of a mobile communication network. This system performs selection control of a radio resource allocation control mode when radio terminal apparatuses form a group (group) and perform direct communication between terminals according to the Sidelink communication method.

Here, this paper assumes application to LTE (Long Term Evolution) / LTE-Advanced mobile communication systems (hereinafter referred to as "LTE system") and fifth generation mobile communication systems (hereinafter referred to as "5G system"). Although embodiments of the invention are described, the concepts of the invention are applicable to any system that uses similar cell and physical channel configurations. In addition, the reference signal sequence used for channel estimation and the coding scheme used for error correction are not limited to those defined in the LTE system or the 5G system, as long as they are suitable for these uses. , can be of any kind. Embodiments of the present invention may be applied to next-generation mobile communication systems after the fifth generation (also referred to as "NR system").

FIG. 1 is a schematic configuration diagram showing an example of the overall configuration of a communication system according to one embodiment of the present invention. In FIG. 1, the communication system according to the present embodiment is an example of a 5G system, and a base station 10 with a two-cell configuration connected to a core network (for example, EPC, 5GC, or NGC) 15 of a mobile communication network. Prepare. Note that although the example in FIG. 1 shows an example in which one base station 10 is provided, the number of base stations may be plural. Also, the cells formed by the base station 10 may be a single cell or three or more cells.

The core network 15 is, for example, an IP (Internet Protocol)-based EPC (Evolved Packet Core) defined by 3GPP (3rd Generation Partnership Project). The core network 15 may be a core network dedicated to the 5G system, or a core network shared by the 5G system and the LTE system. A core network device (EPC device or 5GC device) is a logical node SCEF (Service Capability Exposure Function), NEF (Network Exposure Function), UPF (User Plane Function) for processing user data, and the like. The core network device (EPC device or 5GC device) may be a VAE (V2X Application Enabler) that enables coordination of multiple V2X (Vehicle-to-Everything) services. A part of the functions of the core network device (for example, the functions of the UPF or the functions of the logical nodes other than the UPF) may be included in the base station 10 as in the present embodiment.

The base station 10 is, for example, a gNodeB (gNB) or en-gNodeB (en-gNB) of the 5G system, and via antennas 101 and 102, a communication terminal located in a cell that is a wireless communication area formed by the own station. It can wirelessly communicate with a device (also referred to as “terminal”, “user terminal”, “user device”, “UE”, “mobile station”, “mobile device”, etc., hereinafter referred to as “UE”) 20 .

The base station 10 includes, for example, a base station apparatus 100 provided inside a building or the like, and a plurality of antennas 101 and 102 corresponding to two cells forming the cell formed by the base station 10 . Each of the plurality of antennas 101 and 102 is provided on top of a building, pillar, steel tower, or the like. The antennas 101 and 102 may be omnidirectional antennas, or antennas composed of a plurality of antenna elements capable of forming one or a plurality of beams in a predetermined direction (for example, a large number of antenna elements two-dimensionally or three-dimensionally It may be a Massive MIMO antenna consisting of arrayed array antennas or the like. In the illustrated example, two antennas 101 and 102 are provided, but the number of antennas may be singular or three or more.

The base station apparatus 100 includes, for example, a DU (distributed unit) 110, a CU (aggregation unit) 120, a CNE (core network apparatus) 130, and an MEC (multi-access edge computing) apparatus 140. In the illustrated example, the CNE 130 is an example of a 5G core, but in a non-standalone (NSA) configuration in which LTE controls 5G layer 3 (L3), it may be an EPC. Also, the MEC device 140 may be provided in a node between the base station 10 and the core network 15, or may be provided outside the core network.

The DU 110 has, for example, RFU (Radio Unit) 111 and RFU 112 . The RFU 111 and RFU 112 include, for example, an amplifier section, a frequency conversion section, a transmission/reception switching section (DUP), a quadrature modulation/demodulation section, and the like. The DU 110 may have some functions of a BBU (baseband unit) described below. In the illustrated example, since two cells are configured per base station, two RFUs 111 and 112 are provided, but the number of RFUs may be singular or three or more.

CU120 has BBU (baseband unit) 121 and CU controller 122 which controls each part of CU120, for example. The BBU 121 performs, for example, control information and user data (IP packets) to be transmitted and received, and conversion (modulation/demodulation) of baseband signals such as OFDM signals transmitted and received via wireless transmission paths. For example, QPSK, 16QAM, 64QAM, or the like can be used as the modulation method. Baseband signals are sent to and received from DU 110 . The CU controller 122 is composed of, for example, a CPU and a memory, and controls each part of the CU 120 by executing a preinstalled program.

A CU 120 may connect to multiple DUs. Also, the CU 120 may be connected to the DU of a remotely installed slave station via a high-speed communication line such as an optical communication line using optical fibers. Alternatively, a plurality of BBUs 121 may be provided in the CU 120 and connected to each RFU. For example, the BBU 121 is composed of a plurality of BBU#1 and BBU#2, and a plurality of external connection units 121a connected to each of the BBU#1 and BBU#2 are provided. A plurality of remotely located external RFU#1 and RFU#2 may be remotely connected via a high-speed communication line such as.

The CNE 130 has the aforementioned UPF function, and communicates with various nodes on the core network 15 using a predetermined communication interface and protocol. The CNE 130 relays various data such as user data between the core network 15 and the CU 120 , and relays various data such as user data between the core network 15 and the CU 120 and the MEC device 140 .

The MEC device 140 is composed of, for example, a CPU and a memory, and executes a program installed in advance or a program downloaded via a communication network to perform transmission/reception with the UE 20 located in the cell of the base station 10. It is possible to process various data received and execute various controls for the UE 20 residing in the cell of the base station 10 . Moreover, the MEC device 140 can also function as various means for selection control of the radio resource allocation control mode, which will be described later, by executing a predetermined program.

Note that selection control of the radio resource allocation control mode, which will be described later, may be performed by the CU 120 described above instead of the MEC device 140 . For example, the CU controller of the CU 120 may function as various means for selection control of radio resource allocation control modes, which will be described later, by executing a predetermined program. Also, the CU 120 and the MEC device 140 may cooperate with each other to perform selection control of the radio resource allocation control mode, which will be described later.

UEs 20(1) to 20(3) are vehicles (trucks in the illustrated example) 30(1) to 30(3) that move on a road 90 as a moving route located within a cell formed by the base station 10. installed in the Vehicles 30(1) to 30(3) on which UEs 20(1) to 20(3) are mounted form a preset group and cooperate with each other to form a vehicle group and move.

In the illustrated example, three UEs 20(1) to 20(3) mounted on three vehicles 30(1) to 30(3) are present in the cell of the base station 10. However, a plurality of UEs 20 mounted on a plurality of vehicles 30 of two or four or more may be present. Also, in the illustrated example, three vehicles 30(1) to 30(3) form a vehicle group in a platoon (along the longitudinal direction of each other) and travel in a group, that is, in a platoon. However, the relative positional relationship between the vehicles 30 is not limited as long as the UEs 20 mounted on the plurality of vehicles 30 are in a positional relationship in which they can communicate directly with each other. Furthermore, the vehicle 30 may be a moving object such as an automobile, truck, bus, or motorcycle that moves on a road 90 that is a movement route on the ground, or a movement that can fly and move along a movement route in space such as the sky. It may be a body, or it may be a moving body that can move along a movement route underground, above water (for example, sea), or under water (for example, under the sea).

In addition, in the following description, when describing configurations, functions, etc. that are common to the plurality of UEs 20(1) to 20(3), the UE 20 etc. are described without parentheses, and the plurality of vehicles 30(1) to 30 The vehicle 30 or the like is also used without parentheses when describing the configuration, function, etc., that are common to (3).

The UE 20 of the vehicle 30 connects the base station 10 of the mobile communication network (cellular network) by a communication method via a base station, which is a first communication method (for example, a next-generation NR method such as 3G, LTE, or 5G). (Communication based on the communication method via a base station is hereinafter also referred to as “Uu communication”). 5G Uu communication includes URLLC (Ultra Reliable & Low Latency Communication) for ultra-reliable and low-latency communication, eMBB (Enhanced Mobile BroadBand) for high-speed and large-capacity communication, and a large number of low-cost, low-power consumption terminals simultaneously connected. communication types such as mMTC (Massive Machine Type Communication). In particular, ultra-high-reliability/low-delay communication URLLC is suitable for applications such as remote monitoring and remote control in automated driving truck platooning (see FIG. 1) and automated driving/platooning BRT (Bus Rapid Transit).

For example, in the truck platooning with automatic driving of the following vehicle in FIG. .) 30(2) and 30(3) are unmanned automatic driving. Remote operation of UEs 20(1) to 20(3) of vehicles 30(1) to 30(3) and network side via base station 10 and core network 15 of mobile communication network in truck platooning with automatic driving of following vehicle Uu communication is performed with the monitoring center. For example, the remote operation monitoring center can receive monitor images (still images, moving images) and sensor information of each vehicle 30(1) to 30(3) through uplink Uu communication. In addition, the remote operation monitoring center can transmit control signals such as emergency stop signals to each vehicle 30(1) to 30(3) by downlink Uu communication. Through Uu communication between this vehicle and the remote operation monitoring center on the network side, centralized remote management and remote control of multiple vehicles 30(1) to 30(3) are realized, reducing the burden on the driver and improving safety. can be done.

The UE 20 includes, for example, an antenna 21, a transmission/reception switching unit (DUP), a reception unit, a CP removal unit, an FFT unit, a signal separation unit, a propagation path compensation unit, a demodulation unit, a decoding unit, a DMRS propagation path (channel) estimation unit, a signal It comprises a multiplexer, an IFFT section, a CP inserter, a transmitter and a controller. Antenna 21 can be used for both Uu and Sidelink communications. The DMRS propagation path (channel) estimator estimates a radio propagation path (equivalent propagation path), for example, based on the reception result of known demodulation reference signals (DMRS) transmitted from the base station 10 . The demodulator demodulates and decodes the data signal included in the transmission signal based on the estimation result of the radio channel (equivalent channel). Since the other components have the same functions as the conventional one, the description thereof will be omitted.

In addition, the UE 20 of the vehicle 30 performs wireless communication with other vehicles (hereinafter also referred to as "vehicle-to-vehicle direct communication") using a second communication method that does not involve a base station of a mobile communication network (cellular network). This can be done by direct communication between the terminals installed in the Radio links between terminals in direct communication between terminals are downlink (DL), which is the radio link from the base station side to the terminal side in communication via base stations, and uplink, which is the radio link from the terminal side to the base station side. (UL), also called Sidelink. The second communication method is, for example, a Sidelink communication method using a wireless interface between terminals called PC5. The PC5 interface is a D2D (Device to Device) interface in which UEs, UEs and other devices (e.g., vehicles), vehicles, or vehicles and other devices directly communicate between terminals without going through a base station. Yes, it has been standardized since 3GPP Release 12 for LTE and after Release 16 for 5G.

Transmission of control messages between vehicles and following vehicles in automated driving truck platooning (see Fig. 1), automated driving/platooning BRT (Bus Rapid Transit), etc., in which multiple vehicles are electronically connected through inter-terminal communication. The Sidelink communication method, in which the terminals mounted on each vehicle communicate directly with each other, is suitable for the transmission of surrounding monitoring video from the vehicle to the leading vehicle.

For example, in the following vehicle automatic driving truck platooning in FIG. 1, vehicle control messages (e.g., speed, acceleration, distance between vehicles, control information such as steering), monitor images (still images, moving images), and sensor information. Sidelink (FL) in the figure is inter-vehicle communication from the preceding vehicle to the following vehicle, and Sidelink (BL) is inter-vehicle communication from the following vehicle to the preceding vehicle. Autonomous truck platooning using this inter-vehicle communication (direct communication between terminals) can eliminate the shortage of drivers and improve the working environment. Furthermore, by applying ultra-low latency and highly reliable 5G communication for inter-vehicle communication (direct communication between terminals), it is possible to shorten the distance between vehicles during platooning, and improve fuel consumption efficiency by reducing the air resistance of the vehicle group. In addition, _CO2 emissions can be reduced, and traffic congestion can be alleviated by increasing road capacity.

In the Sidelink communication scheme, a single terminal-to-terminal direct communication (hereinafter referred to as "single-hop communication") may be performed between the UE of a vehicle to which data is to be transmitted and not through the UE of another vehicle. Alternatively, multi-hop communication involving multiple terminal-to-terminal direct communications via UEs in multiple other vehicles may be performed.

In the Sidelink communication system, a Layer-2 ID is a communication identifier (frame identifier) that identifies a frame (also called a "MAC packet"), which is a data processing unit in the data link layer (Layer-2) of a layered communication model. is defined.

In a layered communication model in the UE 20, for example, layer 1 (L1) consisting of a physical layer, a MAC (media access control) layer, an RLC (radio link control) layer, and a PDCP (packet data convergence) layer from the bottom to the top. Layer 2 (L2) that processes data in units of frames, network layer that processes data in units of packets using various protocols (eg IP, Non-IP, ARP), application layer, etc. . Data in the application layer is also called a "message".

The UE 20 uses, for example, part of uplink radio resources of mobile communication, and designates a Destination L2ID (Dst.L2ID), which is a frame identifier as a communication identifier of a transmission destination (communication destination) in Layer 2 (L2). sends data (messages) frame by frame. The UE 20 of the vehicle 30 on the receiving side determines whether or not the frame identifier (Dst.L2ID) of the destination included in the header of the received frame matches the frame identifier (L2ID) assigned to its own device. .

When the UE 20 of the vehicle 30 determines that the frame identifier (Dst.L2ID) of the destination included in the header of the received frame matches the frame identifier (L2ID) assigned to its own device, the received frame A packet containing the data (message) of . On the other hand, when the UE 20 of the vehicle 30 determines that the frame identifier (Dst.L2ID) of the destination included in the header of the received frame does not match the frame identifier (L2ID) assigned to its own device, the reception By processing the data so that the packet containing the data (message) of the received frame is not passed to the upper layer, it is possible to prevent the data from being used by the application.

In the example of FIG. 1, the UEs 20(1) to 20(3) of a plurality of vehicles 30(1) to 30(3) may be in the same cell or in different cells. may In addition, the UEs 20(1) to 20(3) of the vehicles 30(1) to 30(3) perform direct communication between terminals by the Sidelink communication method and Uu communication by the communication method via the base station selectively or simultaneously. may be

FIG. 2 is an explanatory diagram showing an example of radio frames of downlink (DL) and uplink (UL) of Uu communication and sidelink communication (SL) in the communication system according to the present embodiment. In FIG. 2, different frequency bands are used in the downlink of Uu communication (hereinafter referred to as "DL"), the uplink of Uu communication (hereinafter referred to as "UL"), and the Sidelink communication (hereinafter referred to as "SL"). .

In FIG. 2, DL and UL radio frames 401 and 402 each have a predetermined subcarrier interval (15 kHz in the example shown) and a predetermined number (10 in the example shown) of time slots (“subframes”). ) has a predetermined time length (10 ms in the illustrated example).

A leading time slot 401a in a DL radio frame 401 includes a block (SSB) consisting of a downlink SS (synchronization signal) and a PBCH (physical broadcast channel), and a PBCH_DMRS (reference for PBCH demodulation) for demodulating PBCH information. signal) is a special time slot that contains In the second and subsequent DL time slots, PDCCH (physical downlink control channel) for downlink control, PDSCH (physical downlink shared channel) for data transmission, and DMRS for demodulating PDCCH and PDSCH data OFDM (Orthogonal Frequency Division Multiplexing) symbols used for each (data demodulation reference signal) can be assigned.

A leading time slot 402a in the UL radio frame 402 is a special time slot containing an uplink PRACH (Physical Random Access Channel). In the second and subsequent time slots of UL, PUCCH (physical uplink control channel) for uplink control, PUSCH (physical uplink shared channel) for data transmission, and DMRS for demodulating PUCCH and PUSCH data (reference signal for data demodulation) can be assigned an OFDM symbol to be used for each.

In FIG. 2, the SL radio frame 403 has a predetermined subcarrier interval (60 kHz, which is wider than DL/UL in the illustrated example), and has a predetermined number (40, which is greater than DL/UL in the illustrated example). It has a predetermined time length (10 ms in the example shown) consisting of time slots.

The leading time slot 403a in the SL radio frame 403 is SLSS (Sidelink Synchronization Signal) and PSBCH composed of Sidelink Primary Synchronization Signal (S-PSS) and Sidelink Secondary Synchronization Signal (S-SSS) used for synchronizing Sidelink communication. (Physical Sidelink broadcast channel) and PSBCH_DMRS (PSBCH demodulation reference signal) for demodulating PSBCH information are special time slots. For SLSS, PSBCH and PSBCH_DMRS, for example, out of the service area of the cell of the base station 10, any one of the plurality of UEs 20 (hereinafter also referred to as "leader UE" or "master UE") 20(1) is the main entity. can be used for synchronization processing and connection establishment processing of Sidelink communication performed between other UEs (hereinafter also referred to as "member UEs") 20(2) and 20(3) (see FIG. 12 described later).

Whether or not each UE is the leader UE may be specified from the mobile communication network side (for example, MEC device), or may be specified by a storage medium incorporated in the UE (for example, a subscriber information storage medium SIM (Subscriber It may be determined based on the information written in the Identity Module Card)).

Other time slots in the radio frame 403 of SL include PSCCH (Physical Sidelink Control Channel) for L1/L2 control of Sidelink communication, PSFCH (Physical Sidelink Feedback Channel) for data retransmission (HARQ-ACK/NACK feedback), OFDM (Orthogonal Frequency Division Multiplexing) symbols used for each of PSSCH (Physical Sidelink Shared Channel) for data transmission and DMRS for demodulating data of PSCCH, PSFCH and PSSCH can be allocated. PSCCH is, for example, within the service area of the cell of the base station 10, one of the plurality of UEs 20 (leader UE, master UE) 20 (1) is the main body, and the other member UEs 20 (2) and 20 (3) ) can be used for synchronization processing and connection establishment processing of Sidelink communication performed between (see FIG. 11 described later).

FIG. 3 is an explanatory diagram showing another example of radio frames of downlink (DL) and uplink (UL) of Uu communication and sidelink communication (SL) in the communication system according to the present embodiment. In the example of FIG. 3, DL and UL are operated by TDD (time division multiplexing) in the same frequency band, and SL is operated by an independent frequency band different from DL and UL.

In FIG. 3, a radio frame 411 shared by DL and UL has a predetermined subcarrier interval (15 kHz in the example shown) and has a predetermined time length consisting of a predetermined number (20 in the example shown) of time slots. (10 ms in the example shown).

The leading time slot 411a in the shared radio frame 411 is a special time slot containing a block (SSB) consisting of downlink SS and PBCH and PBCH_DMRS. OFDM symbols used for downlink PDCCH, PDSCH, and DMRS can be allocated to a plurality of time slots denoted by "D" in the figure. Two time slots 411b marked with "S" in the figure are special time slots containing uplink GP (guard period), PRACH and SRS (sounding reference signal), respectively. OFDM symbols used for uplink PUCCH, PUSCH and DMRS can be allocated to a plurality of time slots denoted by "U" in the figure.

In FIG. 3, the SL radio frame 412 has a predetermined subcarrier interval (60 kHz in the illustrated example) and has a predetermined time length (40 in the illustrated example) consisting of a predetermined number (40 in the illustrated example) of time slots. 10 ms).

A leading time slot 412a in the SL radio frame 412 is a special time slot containing SLSS, PSBCH, and PSBCH_DMRS used for synchronization of Sidelink communication. Other time slots may be assigned OFDM symbols used for PSCCH, PSFCH, PSSCH and DMRS.

FIG. 4 is an explanatory diagram showing still another example of radio frames of downlink (DL) and uplink (UL) of Uu communication and sidelink communication (SL) in the communication system according to the present embodiment. In the example of FIG. 4, DL, UL and SL are operated by TDD (time division multiplexing) in the same frequency band.

In FIG. 4, a radio frame 421 shared by DL, UL and SL has a predetermined subcarrier interval (60 kHz in the example shown) and is composed of a predetermined number (40 in the example shown) of time slots. It has a time length (10 ms in the example shown). The first time slot 421a is a special time slot that includes an uplink PRACH, a block (SSB) consisting of downlink SS and PBCH, and PBCH_DMRS. The second time slot 421b from the beginning is a special time slot containing SS and PBCH blocks used for synchronization of Sidelink communication.

Other plural time slots of the shared radio frame 421 are a DL time slot 421c(1), a UL time slot 421c(2), and an SL time slot 421c(3) separated by GP (guard period). and OFDM symbols used for the downlink PDCCH and PDSCH can be assigned to the DL time slot 421c(1). OFDM symbols used for uplink PUCCH and PUSCH can be allocated to the UL time slot 421c(2). The OFDM symbols used for the PSCCH and PSSCH can be assigned to the SL time slot 421c(3).

Note that, in other examples of radio resources, some of the UL resources that are standardized in LTE D2D and the like may be used as SL resources.

The UEs 20(1) to 20(3) of the vehicles 30(1) to 30(3) determine and set the transmission/reception timing of radio frames when performing direct communication between terminals according to the Sidelink communication method. For example, it is possible to select from the Uu synchronization method as the first synchronization method and the SLSS synchronization method as the second synchronization method. Also, as another synchronization method, a GNSS synchronization method may be used.

The Uu synchronization method includes a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), etc., which are periodically transmitted by the base station 10 of the mobile communication network (cellular network) for cell search and DL synchronization establishment on the terminal side. is used as a reference for inter-terminal synchronization. The SL synchronization method realizes inter-terminal synchronization using SLSS, and is used when other synchronization references cannot be used, such as inside a tunnel or in an area outside the service area of a base station. On the other hand, the GNSS synchronization method is a method in which a GNSS (Global Navigation Satellite System) receiver as current position acquisition means provided in the UE 20 uses a time reference obtained by receiving radio waves from GNSS satellites as a reference for inter-terminal synchronization. Yes, and the signal source of the time reference is the GNSS receiver within the device itself.

For example, the UE 20 of the vehicle 30 uses the Uu synchronization method to determine the transmission/reception timing of the radio frame of the Sidelink communication system within the range of the cell of the base station 10, and the common signal from the base station outside the range of the cell of the base station 10. , and other synchronization reference signal sources cannot be used, the SLSS synchronization method is used to determine the transmission/reception timing of the radio frame of the Sidelink communication method.

SL Mode-1 as a first mode in which the base station 10 allocates SL radio resources as a radio resource (time slot) allocation control mode in the Sidelink communication scheme illustrated in FIGS. , also referred to as “Mode-1” for short.) and SL Mode-2 (hereinafter also referred to as “Mode-2” for short) as a second mode in which each UE 20 autonomously selects an SL radio resource. be. Mode-1 and Mode-2 can be selected and applied to each group (group) composed of UEs 20 of a plurality of vehicles 30. FIG. A group (group) may be statically formed with a plurality of preset UEs, or may be ad hoc formed with a plurality of UEs located close to each other.

FIGS. 5(a) and 5(b) are explanatory diagrams showing an example of the first radio resource allocation control mode (Mode-1) in the communication system according to the embodiment. In Mode-1, efficient direct communication (inter-terminal direct communication) between UEs 20 is realized by Sidelink radio resource allocation control from the base station 10 within the range of the cell 10A of the base station 10 shown in FIG. 5(a). have the advantage of Within the range of the cell 10A of the base station 10, the UEs 20 of the vehicles 30(1) to 30(3) belonging to the first group G1 use radio resources allocated by Sidelink radio resource allocation control from the base station 10. UEs 20(4) and 20(5) of vehicles 30(4) and 30(5) belonging to the second group G2 can perform terminal-to-terminal direct communication with each other. can communicate directly between

However, in Mode-1, synchronization and radio resource selection required for direct communication between terminals depend on synchronization signals and control signals transmitted by the base station 10. Therefore, as shown in FIG. UE 20(1) to 20(3) of vehicles 30(1) to 30(3) belonging to group G1 cannot directly communicate between Sidelink terminals. I have a problem.

FIGS. 6A and 6B are explanatory diagrams showing an example of the second radio resource allocation control mode (Mode-2) in the communication system according to the embodiment. In Mode-2, even within the range of the cell 10A of the base station 10 shown in FIG. Direct communication between terminals can be performed by autonomously detecting or randomly selecting necessary wireless resources without relying on the station 10 . Similarly, the UEs 20(4) and 20(5) of the vehicles 30(4) and 30(5) belonging to the group G2 autonomously detect or randomly select necessary radio resources without relying on the base station 10. can be used for direct communication between terminals. In Mode-2, as shown in FIG. 6(b), UEs 20(1) to 20(3) of vehicles 30(1) to 30(3) are outside the service area 10X of the cell 10A of the base station 10. Without relying on the base station 10, it is possible to autonomously detect or randomly select necessary radio resources, autonomously allocate them to each UE, and perform direct communication between terminals.

However, in Mode-2, especially when there are many UEs that perform autonomous direct communication between terminals, the signals transmitted by the UEs collide and the rate of mutual interference increases. There is a problem that the quality of communication tends to deteriorate.

Therefore, in the present embodiment, a plurality of UEs 20 in the same group G1 are located within the range of the cell 10A of the base station 10, and have completed wireless connection setup with the base station 10. A radio resource allocation control mode (Mode- 1, Mode-2) are controlled dynamically. By performing such control, the advantages of Mode-1 and Mode-2 can be compensated for and their advantages can be exploited.

FIG. 7 is an explanatory diagram showing an example of dynamic switching control of radio resource allocation control modes (Mode-1, Mode-2) in the communication system according to the embodiment. For example, as shown in FIG. 7(a), the CU 120 or the MEC device 140 of the base station 10 is arranged such that all the UEs 20 of the plurality of vehicles 30 belonging to the same group G1 are located within the range of the cell 10A of the base station 10 and When the radio connection setting with the station 10 is completed and it is confirmed that the downlink and the uplink are in a synchronized state with the base station 10, the sidelink communication radio resource allocation control mode is set to the initial setting. Switch from Mode-2 (second mode) to Mode-1 (first mode), resource control information for direct communication between terminals including a first mode allowed message (Mode-1 Allowed) that allows Mode-1 operation ( SL resource control information) to multiple UEs 20(1) to 20(3) in group G1.

On the other hand, in the present embodiment, as shown in FIG. 7B, the CU 120 or the MEC device 140 of the base station 10 is at least one UE (in the illustrated example, UE20(1) and UE20(2)) are located outside the service area 10X of the cell 10A of the base station 10, and confirmed that the downlink and uplink with the base station 10 are in an asynchronous state. In this case, control is executed to maintain the radio resource allocation control mode for Sidelink communication at the initial setting Mode-2.

FIG. 8 is a sequence showing an example of dynamic switching control from the second radio resource allocation control mode (SL Mode-2) to the first radio resource allocation control mode (SL Mode-1) in the communication system according to the present embodiment It is a diagram. Note that the three UEs 20(1), 20(2), and 20(3) in FIG. 3). A single group (group) is formed by these UEs 20(1), 20(2), and 20(3). Also, the radio resource allocation control mode for Sidelink communication before the dynamic switching control of FIG. 8 is executed is Mode-2, which is the initial setting.

In FIG. 8, first, between a plurality of UEs 20(1), 20(2), 20(3) belonging to group G1 and the base station 10, an RRC (radio resource control) state check as a radio connection state check is performed. is executed (S101). CU 120 or MEC device 140 of base station 10 confirms that all UEs 20(1), 20(2), 20(3) belonging to group G1 are in the "RRC_CONNECTED" state based on the result of the RRC state check, that is, It can be confirmed that the UEs 20(1), 20(2), 20(3) are located within the range of the cell 10A of the base station 10 and are in synchronization with the base station 10 (S102).

In addition, since the UEs 20(1), 20(2), and 20(3) of the plurality of vehicles 30(1), 30(2), and 30(3) are moving, each UE 20(1), 20(2) ), 20(3) are located within the range of the cell 10A of the base station 10, and between each UE 20(1), 20(2), 20(3) and the base station 10 Confirmation of whether or not it is in a synchronous state is performed periodically.

The CU 120 or the MEC device 140 of the base station 10 confirms that it is located within the range of the cell 10A of the base station 10 and that wireless connection setting including synchronization processing has been completed with the base station 10 (S102). , UE 20 (1), 20 (2), and 20 (3), each of which includes Mode-1 permission information ("Mode-1 Allowed") as a first mode permission message that allows Mode-1 operation Resource control information for direct communication (Sidelink resource control information) is transmitted (S103). If the Mode-1 permission information is "1: Mode-1 Allowed", it can be confirmed that Mode-1 operation is permitted, and if "0: Mode-1 Not Allowed", Mode-1 You can confirm that the motion is not allowed.

The resource control information (SL resource control information) includes a UE group ID that can identify the group to which the UEs 20(1), 20(2), and 20(3) that are controlled UEs that switch the radio resource allocation control mode belong. be done. With this target UE group ID, when a plurality of UE groups exist in the cell of the base station 10, it is possible to limit the target UE group whose sidelink communication radio resource allocation control mode is switched to Mode-1. Note that instead of including the UE group ID in the resource control information (SL resource control information), individual terminal identification information (UE ID) that can identify the control target UE that switches the radio resource allocation control mode may be included. The aforementioned Layer-2 ID may be used as the individual terminal identification information.

After transmitting Sidelink resource control information to each UE 20(1), 20(2), 20(3), the CU 120 or the MEC device 140 of the base station 10 requests resource allocation control based on Mode-1 from each UE. A reception waiting state for a request message (Sidelink scheduling request message) is started (S104).

When each UE 20(1), 20(2), 20(3) receives Mode-1 allowable information that allows Mode-1 operation from the CU 120 or the MEC device 140 of the base station 10, SS/ Sidelink synchronization processing using PBCH (SLSS/PSBCH) blocks is skipped (S105).

In addition, if each UE 20 (1), 20 (2), 20 (3) does not receive Mode-1 allowable information that allows Mode-1 operation, it checks the synchronization state of Uu communication, Uu communication is asynchronous or not. When the Uu communication is asynchronous, each of the UEs 20(1), 20(2), and 20(3) executes a process of maintaining the default Mode-2 as the sidelink communication radio resource allocation control mode (S106). Specifically, the leader UE 20 (1) transmits SS/PBCH (SLSS/PSBCH) blocks for Sidelink communication to the member UEs 20 (2) and 20 (3). Based on the SS/PBCH (SLSS/PSBCH) block of the Sidelink communication received from the leader UE 20(1), the sidelink communication synchronization is established.

In S105 above, when each UE 20 (1), 20 (2), 20 (3) receives the Mode-1 allowable information, the leader UE 20 (1) all other member UE 20 (2) belonging to the same group , 20(3) to receive Uu synchronization state information transfer indicating the synchronization state of Uu communication, and determine whether each member UE 20(2), 20(3) (Uu) is in the Uu communication synchronization state ( S107). The Uu sync state information transfer includes the aforementioned UE group ID and Uu sync state information. If the Uu synchronization state information is "1: Uu In-Sync", it can be confirmed that the Uu communication is in the synchronization state, and if it is "0: Uu Out-of-Sync", the Uu communication is in the asynchronous state. I can confirm that. Also, by receiving the Uu synchronization state information transfer including the UE group ID, the leader UE 20(1) can confirm the member UEs regarding whether or not they can operate Mode-1 with each other. When there are a plurality of UE groups in the cell, it is possible to limit the UE groups to switch the radio resource allocation control mode of Sidelink communication to Mode-1.

When the leader UE 20 (1) confirms that all other member UEs 20 (2) and 20 (3) belonging to the same group are in the Uu communication synchronization state (S108), each member UE 20 (2) and 20 ( 3), a mode specifying message (SL mode flag: Mode-1) specifying Mode-1 is transmitted (S109).

Leader UE20(1) has successfully received a mode designation message (SL mode flag: Mode-1) designating Mode-1 by all other member UE20(2), 20(3) belonging to the same group. Check whether or not The leader UE 20 (1) sends SL mode flag acknowledgments indicating successful reception of the mode designation message (SL mode flag: Mode-1) from all member UEs 20 (2) and 20 (3) in the group. (ACK), select Mode-1 as the radio resource allocation control mode (S111), and send a request message (SL scheduling request message) requesting resource allocation control based on Mode-1 to the CU 120 of the base station 10 or the MEC. It is transmitted to the device 140 (S112).

Note that the leader UE 20 (1) sends an SL HARQ acknowledgment (ACK) to the retransmission of the mode designation message (SL mode flag: Mode-1) to each member UE 20 ( 2), 20(3) may confirm successful reception of the mode designation message (SL mode flag: Mode-1).

When the CU 120 or the MEC device 140 of the base station 10 receives the request message (SL scheduling request message) from the leader UE 20(1), it executes resource allocation control based on Mode-1.

FIG. 9 shows another example of dynamic switching control from the second radio resource allocation control mode (SL Mode-2) to the first radio resource allocation control mode (SL Mode-1) in the communication system according to the present embodiment. It is a sequence diagram showing. Note that S201 to S206 in FIG. 9 are the same as S101 to S106 in FIG. 8 described above, so description thereof will be omitted.

In FIG. 9, after all UEs 20 (1), 20 (2), 20 (3) in the group receive the Mode-1 allowable information, each UE 20 (1), 20 (2), 20 (3) is in the Uu communication synchronization state (S207), select Mode-1 as the radio resource allocation control mode (S208), and request message (SL scheduling request message) requesting resource allocation control based on Mode-1 to the CU 120 or MEC device 140 of the base station 10 (S209).

When the CU 120 or the MEC device 140 of the base station 10 receives the request message (SL scheduling request message) from each of the UEs 20(1), 20(2), and 20(3), it executes resource allocation control based on Mode-1. do.

FIG. 10 is a sequence diagram showing an example of determining the connection state between the UE 20 and the base station 10 in the communication system according to this embodiment. The connection state determination illustrated in FIG. 10 can be used in the RRC state check (S101, S201) in FIGS. 8 and 9 described above.

In FIG. 10, the UE 20 receives downlink SS (synchronization signal) and PBCH (broadcast channel) blocks and system information from the base station 10, and transmits a random access (RA) preamble (PRACH) to the base station 10. , a random access response (RAR) and a timing advance (TA) command are received from the base station 10 to perform the initial access procedure to the base station 10 (S301-S304). The base station 10 transmits an RRC connection setup message to the UE 20 in response to the RRC (radio resource control) connection request message received from the UE 20 (S304, S305), and receives an RRC connection setup completion message transmitted from the UE 20 via PUSCH. A message is received (S306). Upon receiving the RRC connection setup complete message, the base station 10 confirms that the target UE 20 is located within the range of its own cell and is in DL/UL synchronization with the UE 20 at the time of initial connection. be able to. After that, by checking the CRC (Cyclic Redundancy Check) decoding result of PUCCH periodically transmitted by UE 20 for CQI (channel quality indicator) transmission, etc. (S308), base station 10 confirms the connection state with UE 20. can be determined.

By receiving HARQ-ACK transmitted by PDCCH from the base station 10 in response to the RRC connection setup complete message, the UE 20 is located within the cell range of the base station 10 at the time of initial connection, and It can be confirmed that there is DL/UL synchronization with the base station 10 . After that, the UE 20 can determine the connection state with the base station 10 by checking the decoding result of the PBCH periodically transmitted by the base station 10 (S309).

FIG. 11 is a sequence diagram showing an example of synchronization establishment of Sidelink communication (SL) and determination of connection state of UE 20 located within the cell range of base station 10 in the communication system according to the present embodiment. In FIG. 11 , within the range of the cell of the base station 10 , each UE 20 establishes synchronization of Sidelink communication by establishing DL and UL synchronization with the base station 10 . The connection state of Sidelink communication within the range is, for example, as shown in FIG. It can be confirmed by successful reception of PSCCH in the BL direction to member UE 20(2) (S402).

FIG. 12 is a sequence diagram showing an example of synchronization establishment and connection state determination of Sidelink communication (SL) of the UE 20 located outside the cell of the base station 10 in the communication system according to the present embodiment. Outside the cell area of the base station 10, communication with the base station does not occur, and short-distance communication is assumed compared to Uu communication, and the SLSS synchronization method Timing Advance is not normally applied. For example, as shown in FIG. 12, synchronization of Sidelink communication is established by transmitting/receiving SS/PBCH (SLSS/PSBCH) of Sidelink communication from leader UE 20(1) to member UE 20(2) (S501). . In addition, as shown in FIG. 12, for example, the connection state of Sidelink communication in the out-of-range is the successful reception of the PSCCH in the FL direction from the member UE 20(2) to the leader UE 20(1) (S502) and the leader UE 20(1). ) to the member UE 20(2) by successful reception of PSCCH in the BL direction (S503).

As described above, according to this embodiment, direct communication between terminals ( When performing Sidelink communication), appropriately select a radio resource allocation control mode that allocates radio resources for direct communication between terminals to a plurality of UEs 20 (1), 20 (2), and 20 (3) in the same group, Even when the number of UEs in the same group increases, low-delay and highly reliable direct communication between terminals can be reliably performed within the same group.

Also, the processing steps described herein and the wireless communication system, mobile communication system, control device, MEC device, base station and wireless terminal device (terminal, terminal device, user equipment (UE), mobile station, mobile device) The components of may be implemented by various means. For example, these processes and components may be implemented in hardware, firmware, software, or any combination thereof.

For hardware implementation, a processing unit or the like used to implement the above steps and components in an entity (e.g., various wireless communication devices, Node B, eNodeB, gNodeB, terminals, hard disk drives, or optical disk drives) means of one or more of an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processor (DSPD), a programmable logic device (PLD), a field programmable gate array ( FPGA), processor, controller, microcontroller, microprocessor, electronic device, other electronic unit designed to perform the functions described herein, computer, or any combination thereof. good too.

Also, for firmware and/or software implementations, means such as processing units used to implement the above components may be programs (e.g., procedures, functions, modules, instructions) that perform the functions described herein. , etc.). In general, any computer/processor readable medium tangibly embodying firmware and/or software code means, such as a processing unit, used to implement the above steps and components described herein. may be used to implement For example, firmware and/or software code may be stored in memory and executed by a computer or processor, such as in a controller. The memory may be implemented within the computer or processor, or external to the processor. The firmware and/or software code may also be, for example, random access memory (RAM), read only memory (ROM), non-volatile random access memory (NVRAM), programmable read only memory (PROM), electrically erasable PROM (EEPROM). ), flash memory, floppy disk, compact disk (CD), digital versatile disk (DVD), magnetic or optical data storage devices, etc. good. The code may be executed by one or more computers or processors and may cause the computers or processors to perform certain aspects of the functionality described herein.

Also, the medium may be a non-temporary recording medium. Also, the code of the program is not limited to a specific format as long as it can be read and executed by a computer, processor, or other device or machine. For example, the program code may be source code, object code, or binary code, or may be a mixture of two or more of these codes.

Moreover, the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein are applicable to other variations without departing from the spirit or scope of this disclosure. This disclosure, therefore, is not to be limited to the examples and designs described herein, but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

10: Base station 10A: Cell 10X: Out of range 14: MEC device 15: Core network 20: UE (radio terminal device)
21: Antenna 30: Vehicle 90: Road 100: Base station device 101: Antenna 102: Antenna 122: CU controller 140: MEC device

Pavel Mach, Zdenek Becavar, and Tomas Vanek, "In-Band Device-to-Device Communication in OFDMA Cellular Networks: A Survey and Challenges," IEEE Communication Surveys & Tutorials, vol.17, no.4, pp.1885-1922 , June 2015. 3GPP TR22.886 V16.2.0, "Study on enhancement of 3GPP support for 5G V2X services (Release 16)," Dec. 2018. 3GPP TR37.985 V16.0.0, "Overall description of Radio Access Network (RAN) aspects for Vehicle-to-everything (V2X) based on LTE and NR (Release 16)," June 2020. 3GPP TR38.885 V16.0.0, "Study on NR Vehicle-to-Everything (V2X) (Release 16)," March 2019.

The leading time slot 403a in the SL radio frame 403 is an SLSS ( Sidelink synchronization signal), PSBCH (physical sidelink broadcast channel), and PSBCH_DMRS (PSBCH demodulation reference signal) for demodulating PSBCH information. For SLSS, PSBCH and PSBCH_DMRS, for example, out of the service area of the cell of the base station 10, any one of the plurality of UEs 20 (hereinafter also referred to as "leader UE" or "master UE") 20(1) is the main entity. can be used for synchronization processing and connection establishment processing of Sidelink communication performed between other UEs (hereinafter also referred to as "member UEs") 20(2) and 20(3) (see FIG. 12 described later).

The Uu synchronization method uses the Primary Synchronization Signal (PSS) and the Secondary Synchronization Signal (SSS) periodically transmitted by the base station 10 of the mobile communication network (cellular network) for cell search and DL synchronization establishment on the terminal side. ) as a reference for synchronizing between terminals. The SL synchronization method realizes inter-terminal synchronization using SLSS, and is used when other synchronization references cannot be used, such as inside a tunnel or in an area outside the service area of a base station. On the other hand, the GNSS synchronization method is a method in which a GNSS (Global Navigation Satellite System) receiver as current position acquisition means provided in the UE 20 uses a time reference obtained by receiving radio waves from GNSS satellites as a reference for inter-terminal synchronization. Yes, and the signal source of the time reference is the GNSS receiver within the device itself.

In S105 above, when each UE 20 (1), 20 (2), 20 (3) receives the Mode-1 allowable information, the leader UE 20 (1) all other member UE 20 (2) belonging to the same group , 20(3) to receive Uu synchronization state information transfer indicating the synchronization state of Uu communication, and determine whether each member UE 20(2), 20(3) (Uu) is in the Uu communication synchronization state ( S107). The Uu sync state information transfer includes the aforementioned UE group ID and Uu sync state information. If the Uu synchronization state information is "1: Uu In-Sync", it can be confirmed that the Uu communication is in the synchronization state, and if it is "0: Uu Out-of-Sync", the Uu communication is in the asynchronous state. I can confirm that. Also, by receiving the Uu synchronization state information transfer containing the UE group ID, the leader UE 20(1) can confirm the member UEs regarding whether or not they can perform Mode-1 operation with each other. When a plurality of UE groups exist within 10 cells, it is possible to limit the UE groups whose sidelink communication radio resource allocation control mode is switched to Mode-1.

Claims (19)

A system for performing selection control of a radio resource allocation control mode when a plurality of radio terminal devices capable of communicating via a base station of a mobile communication network form a group and perform direct communication between terminals,
a first mode in which the base station allocates radio resources for inter-terminal direct communication for the plurality of radio terminal devices as a radio resource allocation control mode for allocating radio resources for inter-terminal direct communication for the plurality of radio terminal devices belonging to the group; , a second mode in which any one of the plurality of wireless terminal devices allocates radio resources for inter-terminal direct communication of the plurality of wireless terminal devices,
All of the plurality of wireless terminal devices belonging to the group are located within the range of the cell of the base station, have completed wireless connection setup with the base station, and have downlink and uplink connections with the base station. a means for checking whether it is in a synchronized synchronized state;
resources for direct communication between terminals including a first mode allow message that allows operation in the first mode when all the plurality of wireless terminal apparatuses belonging to the group are confirmed to be in a synchronized state with the base station; means for transmitting control information to the plurality of wireless terminals;
A system characterized by comprising: The system of claim 1, wherein
A system, wherein the resource control information for direct communication between terminals includes group identification information capable of identifying the group or terminal identification information for each of a plurality of wireless terminal devices belonging to the group. In the system of claim 1 or 2,
any one of the plurality of wireless terminal devices belonging to the group,
determining whether or not all the plurality of wireless terminal devices belonging to the group have completed reception of the resource control information for the direct communication between terminals and are in a synchronized state in which the downlink and the uplink are synchronized with the base station; a means of verifying and
When it is confirmed that all the wireless terminal devices other than the wireless terminal device belonging to the group are in a synchronized state with the base station, all the other wireless terminal devices are set to the first mode. means for transmitting a mode-specific message that specifies
means for checking whether all other wireless terminals have successfully received the mode designation message;
A system characterized by comprising: The system of claim 3, wherein
When all of the plurality of wireless terminal devices belonging to the group successfully receive the mode designation message, the one wireless terminal device or all of the plurality of wireless terminal devices belonging to the group use resources based on the first mode. A system characterized by transmitting a request message requesting allocation control to the base station side. In the system of claim 1 or 2,
Each of all the plurality of wireless terminal devices belonging to the group,
determining whether or not all the plurality of wireless terminal devices belonging to the group have completed reception of the resource control information for the direct communication between terminals and are in a synchronized state in which the downlink and the uplink are synchronized with the base station; a means of verifying and
When it is confirmed that all the wireless terminal devices other than the wireless terminal device belonging to the group are in a synchronized state with the base station, all the other wireless terminal devices are set to the first mode. means for transmitting a mode-specific message that specifies
means for checking whether all other wireless terminals have successfully received the mode designation message;
A system characterized by comprising: The system of claim 5, wherein
When all the plurality of wireless terminal devices belonging to the group successfully receive the mode designation message, all the plurality of wireless terminal devices belonging to the group are the terminals of all the plurality of wireless terminal devices belonging to the group. transmitting a request message requesting resource control for inter-direct communication to the base station side. In the system according to any one of claims 3 to 6,
Synchronization indicating that the one wireless terminal device or all of the plurality of wireless terminal devices belonging to the group are in a synchronized state with the base station after completing reception of resource control information for the direct communication between terminals. A system, wherein status information is received from said all other wireless terminals to confirm that said all other wireless terminals are in said synchronized state. The system of claim 7, wherein
The one wireless terminal device or all of the plurality of wireless terminal devices belonging to the group receive group identification information capable of identifying the group together with the synchronization state information from all of the other wireless terminal devices. A system characterized by In the system according to any one of claims 1 to 8,
A system according to claim 1, wherein said group is fixedly formed by a plurality of preset wireless terminal devices, or ad-hoc formed by a plurality of wireless terminal devices located close to each other. In the system according to any one of claims 1 to 9,
A system, wherein the second mode is selected as the initial radio resource allocation control mode. In the system according to any one of claims 1 to 9,
The system, wherein the wireless terminal device is provided in each of a plurality of vehicles that form the group and run on the moving route. A wireless terminal device capable of communicating via a base station of a mobile communication network, forming a group with one or a plurality of nearby wireless terminal devices, and performing direct communication between terminals,
determining whether or not all the plurality of wireless terminal devices belonging to the group have completed reception of the resource control information for the direct communication between terminals and are in a synchronized state in which the downlink and the uplink are synchronized with the base station; a means of verifying and
When it is confirmed that all the wireless terminal devices other than the wireless terminal device belonging to the group are in a synchronized state with the base station, all the other wireless terminal devices are set to the first mode. means for transmitting a mode-specific message that specifies
means for checking whether all other wireless terminals have successfully received the mode designation message;
A wireless terminal device comprising: A vehicle that travels on a moving route in a group with other vehicles,
A vehicle comprising the wireless terminal device according to claim 12 . A control device that performs selection control of a radio resource allocation control mode when a plurality of radio terminal devices capable of communicating via a base station of a mobile communication network form a group and perform direct communication between terminals,
a first mode in which the base station allocates radio resources for inter-terminal direct communication for the plurality of radio terminal devices as a radio resource allocation control mode for allocating radio resources for inter-terminal direct communication for the plurality of radio terminal devices belonging to the group; , a second mode in which any one of the plurality of wireless terminal devices allocates radio resources for inter-terminal direct communication of the plurality of wireless terminal devices,
All of the plurality of wireless terminal devices belonging to the group are located within the range of the cell of the base station, have completed wireless connection setup with the base station, and have downlink and uplink connections with the base station. a means for checking whether it is in a synchronized synchronized state;
resources for direct communication between terminals including a first mode allow message that allows operation in the first mode when all the plurality of wireless terminal apparatuses belonging to the group are confirmed to be in a synchronized state with the base station; means for transmitting control information to the plurality of wireless terminals;
A control device comprising: 15. The control device of any one of claims 14,
The control device is a CU (Central Unit) or MEC (Multi-access Edge Computing) device provided outside the base station of the mobile communication network, a node between the base station and the core network, or the core network, A control device characterized by: A base station of a mobile communication network,
A base station comprising the control device according to claim 14. A method for selecting and controlling a radio resource allocation control mode when a plurality of radio terminal apparatuses capable of communicating via a base station of a mobile communication system form a group and perform direct communication between terminals,
a first mode in which the base station allocates radio resources for inter-terminal direct communication for the plurality of radio terminal devices as a radio resource allocation control mode for allocating radio resources for inter-terminal direct communication for the plurality of radio terminal devices belonging to the group; , a second mode in which any one of the plurality of wireless terminal devices allocates radio resources for inter-terminal direct communication of the plurality of wireless terminal devices;
All of the plurality of wireless terminal devices belonging to the group are located within the range of the cell of the base station, have completed wireless connection setup with the base station, and have downlink and uplink connections with the base station. checking whether it is in a synchronized synchronized state;
resources for direct communication between terminals including a first mode allow message that allows operation in the first mode when all the plurality of wireless terminal apparatuses belonging to the group are confirmed to be in a synchronized state with the base station; transmitting control information to the plurality of wireless terminals;
A method comprising: Executed in a computer or processor provided in a control device that performs selection control of a radio resource allocation control mode when a plurality of radio terminal devices capable of communicating via a base station of a mobile communication system form a group and perform direct communication between terminals A program that
a first mode in which the base station allocates radio resources for inter-terminal direct communication for the plurality of radio terminal devices as a radio resource allocation control mode for allocating radio resources for inter-terminal direct communication for the plurality of radio terminal devices belonging to the group; a second mode in which any one of the plurality of wireless terminal devices allocates radio resources for inter-terminal direct communication of the plurality of wireless terminal devices;
All of the plurality of wireless terminal devices belonging to the group are located within the range of the cell of the base station, have completed wireless connection setup with the base station, and have downlink and uplink connections with the base station. program code for checking whether it is in a synchronized synchronized state;
resources for direct communication between terminals including a first mode allow message that allows operation in the first mode when all the plurality of wireless terminal apparatuses belonging to the group are confirmed to be in a synchronized state with the base station; program code for transmitting control information to the plurality of wireless terminals;
A system characterized by comprising: A program executed in a computer or processor provided in a wireless terminal device capable of communicating via a base station of a mobile communication network, forming a group with one or a plurality of nearby wireless terminal devices, and performing direct communication between terminals. hand,
determining whether or not all the plurality of wireless terminal devices belonging to the group have completed reception of the resource control information for the direct communication between terminals and are in a synchronized state in which the downlink and the uplink are synchronized with the base station; program code for checking,
When it is confirmed that all the wireless terminal devices other than the wireless terminal device belonging to the group are in a synchronized state with the base station, all the other wireless terminal devices are set to the first mode. program code for sending a mode-specific message specifying
program code for checking whether all the other wireless terminals have successfully received the mode designation message;
A program characterized by comprising:

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