JP2023071686A - System for performing harq retransmission control in data transmission via inter-terminal direct communication, radio terminal device, vehicle, base station, method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the HARQ retransmission delay during the mode SL Mode-1 (first mode) operation in which a base station allocates a radio resource of Sidelink.

SOLUTION: A base station monitors a feedback channel to a transmission side radio terminal device from a reception side radio terminal device of data transmission via inter-terminal direct communication, decodes the feedback channel, notifies the transmission side radio terminal device of a permission message including information on a radio resource for HARQ retransmission when the decoding result includes HARQ negative acknowledgment from the reception side radio terminal device. The base station may receive a feedback message including the HARQ negative acknowledgment and a radio resource allocation request from the reception side radio terminal device of data transmission via the inter-terminal direct communication, and transmit the permission message including the HARQ negative acknowledgment and information on the radio resource for HARQ retransmission to the reception side radio terminal device of data transmission in response to the feedback message.

SELECTED DRAWING: Figure 7

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to HARQ retransmission control in data transmission through direct communication between terminals of a plurality of wireless terminal apparatuses capable of communicating through a base station of a mobile communication network.

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 formulated (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). In addition, in order to improve the reliability of user data transmission (hereinafter referred to as "SL transmission") by the Sidelink communication method, SL HARQ (Hybrid Automatic Repeat Request) fed back from the receiving terminal through PSFCH (Physical Sidelink Feedback Channel) HARQ retransmission control based on ACK/NACK is known (Patent Document 2, Non-Patent Document 5).

EP 3136811 U.S. Patent Application Publication No. 2020/0314959

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. Shao-Yu Lien, Der-Jiunn Deng, Chun-Cheng Lin, Hua-Lung Tsai, Tao Chen, Chao Guo, And Shin-Ming Cheng, "3GPP NR Sidelink Transmissions Toward 5G V2X," IEEE Access, vol.8, pp .35368-35382, February 2020 (DOI: 10.1109/ACCESS.2020.2973706).

In the first mode in which the base station allocates Sidelink radio resources, dynamic radio resources for SL transmission are first allocated for SL transmission via an uplink control channel PUCCH or the like, regardless of the initial transmission and HARQ retransmission. A radio resource allocation request (SR: Scheduling Request) is requested from the base station, and a grant message (Grant) for permitting SL transmission by the radio resources allocated by the base station is sent from the base station on the downlink control channel (PDCCH). It is secured by notifying the terminal side.

However, during the first mode operation, L1/ Since L2 signaling is performed, there is a problem that the HARQ retransmission delay increases during the first mode operation.

A base station according to a first aspect of the present invention has a function of communicating with a plurality of wireless terminal devices that perform direct communication between terminals, and is a mobile communication network capable of controlling radio resources used for the direct communication between terminals. is the base station of This base station monitors a feedback channel from a receiving side wireless terminal device to a transmitting side wireless terminal device of data transmission via the direct terminal communication, and decodes the feedback channel; means for notifying the wireless terminal device on the transmitting side of a grant message including information on radio resources for HARQ retransmission when the decoding result of the channel for receiving includes a HARQ negative acknowledgment from the wireless terminal device on the receiving side; Prepare.

A wireless terminal device according to a first aspect is a wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between terminals with peripheral wireless terminal devices. When this wireless terminal device transmits data to the peripheral wireless terminal device via the direct communication between terminals, the wireless terminal device does not receive a HARQ negative acknowledgment from the peripheral wireless terminal device. means for receiving a grant message including information on radio resources for HARQ retransmission; and means for performing HARQ retransmission of said data transmission to a wireless terminal device.

A system according to a first aspect includes the base station and the wireless terminal device according to the first aspect.

A method according to a first aspect is a method of performing HARQ retransmission control in data transmission via direct communication between terminals. This method includes monitoring a feedback channel from a receiving-side wireless terminal device to a transmitting-side wireless terminal device in data transmission via the direct communication between terminals, decoding the feedback channel; when a channel decoding result includes a HARQ negative acknowledgment from the radio terminal device on the receiving side, notifying the radio terminal device on the transmitting side of a grant message including information on radio resources for HARQ retransmission; include.

A program in a base station according to a first aspect is a base of a mobile communication network having a function of communicating with a plurality of wireless terminal devices that perform direct communication between terminals and capable of controlling radio resources used for the direct communication between terminals. It is a program that runs on a computer or processor that resides in the station. A program code for monitoring a feedback channel from a wireless terminal device on the receiving side to a wireless terminal device on the transmitting side of data transmission via the direct communication between terminals and decoding the feedback channel; to notify the transmission-side wireless terminal of a grant message including information on radio resources for HARQ retransmission when the decoding result of the feedback channel includes a HARQ negative acknowledgment from the reception-side wireless terminal; program code;

A program in a wireless terminal device according to a first aspect is a computer or processor provided in a wireless terminal device having a function of communicating via a base station of a mobile communication network and a function of performing direct communication between peripheral wireless terminal devices and terminals. is a program executed in This program performs HARQ retransmission from the base station without receiving HARQ negative acknowledgment from the peripheral wireless terminal device when data transmission is performed to the peripheral wireless terminal device via the direct terminal-to-terminal communication. a program code for receiving a grant message including information on radio resources for said peripheral radio terminal device in response to said grant message received from said base station without receiving a HARQ negative acknowledgment from said peripheral wireless terminal device; and program code for performing HARQ retransmission of the data transmission to the wireless terminal device.

A base station according to a second aspect of the present invention is a base of a mobile communication network having a function of communicating with a plurality of wireless terminal devices that perform direct communication between terminals and capable of controlling radio resources used for the direct communication between terminals. station. The base station includes means for receiving a feedback message including a HARQ negative acknowledgment and a radio resource allocation request from a radio terminal device on the receiving side of data transmission via the direct communication between terminals; means for transmitting a grant message including a HARQ negative acknowledgment and information of radio resources for HARQ retransmission to a wireless terminal receiving said data transmission.

A first wireless terminal device according to a second aspect is a wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between terminals with peripheral wireless terminal devices. The wireless terminal apparatus includes means for receiving data transmission from the peripheral wireless terminal apparatus via the direct communication between terminals, and transmitting a feedback message including a HARQ negative acknowledgment for the data transmission and a radio resource allocation request to the base station. and means for

A second wireless terminal device according to a second aspect is a wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between terminals with peripheral wireless terminal devices. When this wireless terminal device transmits data to the peripheral wireless terminal device via the direct communication between terminals, the wireless terminal device does not receive a HARQ negative acknowledgment from the peripheral wireless terminal device. means for receiving a grant message including a HARQ negative acknowledgment and radio resource information for HARQ retransmission; and means for performing HARQ retransmission of the data transmission to the peripheral wireless terminal devices.

A system according to a second aspect includes the base station, the first wireless terminal device, and the second wireless terminal device according to the second aspect.

A method according to a second aspect is a method of performing HARQ retransmission control in data transmission via direct communication between terminals. This method includes receiving a feedback message including a HARQ negative acknowledgment and a radio resource allocation request from a wireless terminal device on the receiving side of data transmission via the direct terminal communication; sending a grant message including a negative acknowledgment and radio resource information for HARQ retransmissions to a wireless terminal receiving the data transmission.

A program in a base station according to a second aspect is a base of a mobile communication network having a function of communicating with a plurality of wireless terminal devices that perform direct communication between terminals and capable of controlling radio resources used for the direct communication between terminals. It is a program that runs on a computer or processor that resides in the station. This program comprises a program code for receiving a feedback message including a HARQ negative acknowledgment and a radio resource allocation request from a radio terminal device on the receiving side of data transmission via the direct communication between terminals; and program code for transmitting a grant message including the HARQ negative acknowledgment and information of radio resources for HARQ retransmission to a wireless terminal receiving the data transmission.

A program in a first wireless terminal device according to a second aspect is provided for a wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between peripheral wireless terminal devices and terminals. It is a program executed in the computer or processor provided. This program transmits a program code for receiving data transmission from the peripheral wireless terminal devices via the direct communication between terminals, and a feedback message including a HARQ negative acknowledgment for the data transmission and a radio resource allocation request to the base station. program code for transmission to;

A program in a second wireless terminal device according to a second aspect is provided for a wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between peripheral wireless terminal devices and terminals. It is a program executed in the computer or processor provided. This program performs HARQ denial from the base station without receiving HARQ denial from the peripheral wireless terminal when data transmission is performed to the peripheral wireless terminal via the direct communication between terminals. program code for receiving a grant message including a response and radio resource information for HARQ retransmission; program code for HARQ retransmission of the data transmission to the neighboring wireless terminals accordingly.

A vehicle according to another aspect of the present invention is a vehicle that travels on a moving route. This vehicle includes any one of the wireless terminal devices described above.

Advantageous Effects of Invention According to the present invention, it is possible to reduce HARQ retransmission delay during operation of allocation control mode in which a base station allocates radio resources for direct communication between terminals.

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 examples of configuration examples of radio resources (RE) of a time slot 431 at the time of initial transmission and HARQ retransmission of SL data transmission according to the reference example, respectively. FIG. 4 is a sequence diagram showing an example of initial transmission and HARQ retransmission of SL data transmission during SL Mode-1 operation according to the reference example; 4 is a sequence diagram showing an example of initial transmission and HARQ retransmission of SL data transmission during SL Mode-1 operation in the communication system according to the embodiment; FIG. FIG. 8 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 data transmission of FIG. 7; FIG. 4 is a sequence diagram showing another example of initial transmission of SL data transmission and HARQ retransmission during SL Mode-1 operation 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 SL Mode in which a base station of a mobile communication network allocates wireless resources when a plurality of wireless terminal devices mounted on a plurality of vehicles perform direct communication between terminals according to the Sidelink communication method. A system that can reduce HARQ (hybrid automatic repeat request) retransmission delay during operation of -1 (first mode).

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 arranged 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 device 100 includes, for example, a DU (distributed unit) 110, a CU (aggregated unit) 120, a CNE (core network device) 130, and an MEC (Multi-access Edge Computing) device 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/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 the selection control of the radio resource allocation control mode, which will be described later, may be performed by the above-described CU 120 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.

The illustrated example shows a case where three UEs 20(1) to 20(3) mounted on three vehicles 30(1) to 30(3) are located 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 that enables direct communication 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 mobile 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). In the inter-terminal direct communication, the UE that is the data transmission source is also called the transmission side UE 20T, and the data transmission destination UE is also called the reception side UE 20R.

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, for applications such as automatic driving truck platooning (see Fig. 1), automatic driving / platooning BRT (Bus Rapid Transit), railway vehicles running on railroad tracks, remote monitoring, remote control, etc. Reliable, low-latency communication URLLLC is suitable.

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 “direct communication between terminals”) 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 The radio links between terminals in direct communication between terminals are the downlink (DL), which is the radio link from the base station side to the terminal side in communication via base stations, and the 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.

Autonomous driving truck platooning (see Figure 1) and autonomous driving/platooning BRT (Bus Rapid Transit), or driving on a railroad track that electronically connects multiple vehicles running on the road through inter-terminal communication. The Sidelink communication method, in which the terminals mounted on each vehicle communicate directly with each other, is used for the transmission of control messages between each vehicle in the electronic connection between railway vehicles and the transmission of surrounding monitoring video from the following vehicle to the leading vehicle. Suitable.

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 a UE of a vehicle to which data is to be transmitted and not via a 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 401b, PDCCH (physical downlink control channel) for downlink control, PDSCH (physical downlink shared channel) for data transmission, and PDCCH and PDSCH data demodulation. OFDM (Orthogonal Frequency Division Multiplexing) symbols used for each DMRS (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 UL time slots 402b, PUCCH (physical uplink control channel) for uplink control, PUSCH (physical uplink shared channel) for data transmission, and PUCCH and PUSCH data for demodulation. An OFDM symbol used for each DMRS (data demodulation reference signal) can be assigned. In time slots in which resources are allocated to PUSCH, control information to be transmitted by PUCCH may be multiplexed on PUSCH without using PUCCH.

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 first 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).

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 403b in the SL radio frame 403 include a PSCCH (Physical Sidelink Control Channel) for L1/L2 control of Sidelink communication, and a PSFCH (Physical Sidelink Feedback Channel) for data retransmission (HARQ-ACK/NACK feedback). , the PSSCH (Physical Sidelink Shared Channel) for data transmission, and the OFDM (Orthogonal Frequency Division Multiplexing) symbols used for each of the PSCCH, PSFCH and DMRS for demodulating the data of the PSSCH. 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 .

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).

A 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 411c 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. 411d can allocate OFDM symbols used for uplink PUCCH, PUSCH and DMRS to a plurality of time slots denoted by "U" in the figure. In time slots in which resources are allocated to PUSCH, control information to be transmitted by PUCCH may be multiplexed on PUSCH without using PUCCH.

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 412b can be assigned OFDM symbols used for PSCCH, PSFCH as a feedback channel, 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.

The other multiple 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). In time slots in which resources are allocated to PUSCH, control information to be transmitted by PUCCH may be multiplexed on PUSCH without using PUCCH. 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 configuration examples of radio resources (RE) of the time slot 431 at the time of initial transmission and HARQ retransmission of SL data transmission according to the reference example, respectively. AGC (automatic gain control), PSCCH, PSSCH, DMRS, and Guard (guard period) are assigned to the leading portion of the SL data transmission time slot 431 . AGC is information for controlling the gain of the receiving amplifier so that the receiving amplifier of the receiving side UE does not saturate. At the initial transmission of data transmission of (1) SL in FIG. At the time of HARQ retransmission of SL data transmission in FIG. 5(b), HARQ retransmission including PSFCH for returning HARQ response message (HARQ-ACK or HARQ-NACK) and Guard and AGC for the PSFCH Since the radio resource group 431a for SL is inserted, some radio resources cannot be used for SL data transmission.

FIG. 6 is a sequence diagram showing an example of initial transmission and HARQ retransmission of SL data transmission during SL Mode-1 operation according to the reference example. In FIG. 6, the transmission-side UE 20T executes RRC connection reconfiguration (RRC Reconfiguration Procedure) with the base station 10, and performs negotiation for transmission/reception of a scheduling request message in data transmission by SL Mode-1 (S101 ).

When the RRC connection reconfiguration with the base station 10 is completed, the transmitting side UE 20T transmits a scheduling request (Scheduling Request) message requesting radio resource allocation for the initial transmission of SL data transmission to the base station 10 via PUCCH. (S102), when a Grant message including information on the radio resource allocated for the initial transmission is received from the base station 10 via the PDCCH (S103), the initial transmission data is received using the PSSCH set for the radio resource. It transmits to the side UE 20R (S104).

When the reception side UE 20R fails to receive the initial transmission data, HARQ- A HARQ retransmission request including NACK (negative acknowledgment) is returned to the transmitting side UE 20T (S105). The transmitting-side UE 20T that has received the HARQ-NACK feeds back a scheduling request message requesting radio resource allocation for HARQ retransmission of SL to the base station 10 via PUCCH (S106), and includes information on the allocated radio resource. When a grant message is received from the base station 10 via the PDCCH (S107), the PSSCH set for that radio resource is used to transmit HARQ retransmission data to the receiving side UE 20R (S108). When the receiving side UE 20R successfully receives the HARQ retransmission data, the HARQ- An ACK (acknowledgement) is returned to the transmitting side UE 20T (S109).

In the reference example of FIG. 6, when the reception side UE 20R fails to receive the SL initial transmission data, the transmission side UE 20T receives the HARQ retransmission request including HARQ-NACK by the time the transmission side UE 20T transmits the HARQ retransmission data to the reception side UE 20R. (S105), feedback transmission of a scheduling request message (S106), and reception of a grant message (S107), which are three stages of intermediate signaling processing, which increases the HARQ retransmission delay.

Therefore, in the present embodiment, as described below, when the reception side UE 20R fails to receive the SL initial transmission data, the transmission side UE 20T transmits HARQ retransmission data to the reception side UE 20R. Staging reduces the HARQ retransmission delay.

FIG. 7 is a sequence diagram showing an example of initial transmission and HARQ retransmission of SL data transmission during SL Mode-1 operation in the communication system according to the embodiment. FIG. 8 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 data transmission of FIG. In FIG. 7, the description of the processing common to FIG. 6 is omitted.

In FIG. 7, when negotiation for transmission and reception of a scheduling request message in data transmission by SL Mode-1 is performed between the transmitting side UE 20T and the base station 10 (S201), between the receiving side UE 20R and the base station 10 RRC connection reconfiguration is performed, and negotiation for transmission/reception of a scheduling request message when direct feedback (FB) transmission of a HARQ retransmission request from the receiving side UE 20R to the base station 10 is performed (S202).

When the reception side UE 20R fails to receive the initial transmission data, a part of the UL/SL shared radio frame allocated for the initial transmission of SL (for example, the fifth slot 442c of the radio frame 442 in FIG. 8 (2) A HARQ retransmission request including HARQ-NACK (negative acknowledgment) is returned to the transmitting side UE 20T using the PSFCH set in the SL required radio resource group 431a) (S206).

In addition, in the AGC (for PSFCH) section (see FIG. 8) transmitted prior to the PSFCH of the HARQ retransmission request from the receiving side UE 20R, the base station 10 is configured so that the PSFCH can be received without using Timing Advance and demodulation reference signals. In order to do so, a predetermined signal sequence whose reception timing can be detected (reception timing can be estimated) at the base station 10 is multiplexed and transmitted. As this signal sequence, for example, a CAZAC (Constant Amplitude and Zero Auto-Correlation Code) sequence such as a ZC (Zadoff-Chu) sequence that is also used in RACH (Random Access Channel) and the like can be used.

The base station 10 monitors the PSFCH in the UL/SL shared radio frame addressed to the transmitting side UE 20T, which is transmitted from the receiving side UE 20R. When the base station 10 decodes the PSFCH and confirms the HARQ retransmission request including the HARQ-NACK (negative acknowledgment) (S207), it does not wait for the scheduling request (SR) message from the transmitting side UE 20T. to the transmitting side UE 20T on the PDCCH (S208).

The transmitting side UE 20T transmits the HARQ retransmission data to the receiving side UE 20R using the PSSCH set in the allocated radio resource (S209). When the receiving side UE 20R successfully receives the HARQ retransmission data, it returns HARQ-ACK (acknowledgment) to the transmitting side UE 20T using the PSFCH set to a part of the radio resource allocated to the SL HARQ retransmission ( S210).

According to the example of FIG. 7, when the receiving side UE 20R fails to receive the SL initial transmission data, before the transmitting side UE 20T transmits HARQ retransmission data to the receiving side UE 20R, from the receiving side UE 20R to the transmitting side UET HARQ retransmission delays can be reduced because only two stages of intermediate signaling processing of message transmission/reception (S206) and message transmission/reception (S208) from the base station 10 to the transmitting side UE 20T are required.

Also, according to the example of FIG. 7, a scheduling request (SR) for HARQ retransmission from the transmitting UE 20T to the base station 10 is unnecessary, which reduces control overhead between the transmitting UE 20T and the base station 10. be able to.

FIG. 9 is a sequence diagram showing another example of initial transmission and HARQ retransmission of SL data transmission during SL Mode-1 operation in the communication system according to the embodiment. In FIG. 9, the description of the processing common to FIG. 6 is omitted.

In the example of FIG. 9, the radio frames illustrated in FIGS. 2 to 4 can be used as the radio frames of the downlink (DL) and uplink (UL) of Uu communication and the radio frames of Sidelink communication (SL). .

In FIG. 9, when negotiation for transmission and reception of a scheduling request message in data transmission by SL Mode-1 is performed between the transmitting side UE 20T and the base station 10 (S301), between the receiving side UE 20R and the base station 10 RRC connection reconfiguration is performed, and negotiation is performed for transmission/reception of a scheduling request message when directly transmitting a HARQ retransmission request from the receiving side UE 20R to the base station 10 (S302).

When the reception side UE 20R fails to receive the initial transmission data, a HARQ retransmission request (feedback message) including SL HARQ-NACK (negative acknowledgment) and a HARQ retransmission scheduling request message is set in a part of the UL radio frame. The PUCCH is multiplexed on or on the PUSCH and directly fed back to the base station 10 (S306).

When the base station 10 receives the HARQ retransmission request including the SL HARQ-NACK (negative acknowledgment) and the HARQ retransmission scheduling request message from the receiving side UE 20R, the SL HARQ-NACK (negative acknowledgment) and the radio allocated for the SL HARQ retransmission A grant message including resource information is transmitted to the transmitting side UE 20T on the PDCCH (S307). The transmitting-side UE 20T can acquire SL HARQ-NACK information via the base station 10 without using the PSFCH.

The transmitting side UE 20T transmits HARQ retransmission data to the receiving side UE 20R using the PSSCH set in the allocated radio resource (S308). When the receiving side UE 20R successfully receives the HARQ retransmission data, it returns HARQ-ACK (acknowledgment) to the transmitting side UE 20T using the PSFCH set to a part of the radio resource allocated to the SL HARQ retransmission ( S309).

According to the example of FIG. 9, when the reception side UE 20R fails to receive the SL initial transmission data, the reception side UE 20R sends feedback to the base station by the time the transmission side UE 20T transmits HARQ retransmission data to the reception side UE 20R. HARQ retransmission delays can be reduced because only two stages of intermediate signaling processing of direct message transmission/reception (S306) and message transmission/reception (S307) from the base station 10 to the transmitting side UE 20T are required.

Also, according to the example of FIG. 9, since there is no message transmission/reception for HARQ retransmission using the PSFCH from the receiving side UE20R to the transmitting side UE20T, it is possible to reduce the overhead associated with the PSFCH. Also, the radio resources for the AGC and Guard sections of the PSFCH can be reduced.

As described above, according to the present embodiment, it is possible to reduce HARQ retransmission delay of SL during operation of the allocation control mode in which the base station 10 allocates radio resources for SL communication between terminals existing within the range of the base station.

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 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. Shao-Yu Lien, Der-Jiunn Deng, Chun-Cheng Lin, Hua-Lung Tsai, Tao Chen, Chao Guo, And Shin-Ming Cheng, "3GPP NR Sidelink Transmissions Toward 5G V2X," IEEE Access, vol.8, pp .35368-35382, February 2020 (DOI: 10.1109/ACCESS.2020.2973706).

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 SL Mode in which a base station of a mobile communication network allocates wireless resources when a plurality of wireless terminal devices mounted on a plurality of vehicles perform direct communication between terminals according to the Sidelink communication method. A system that can reduce HARQ ( Hybrid Automatic Repeat Request) retransmission delay during operation of -1 (first mode).

FIGS. 5(a) and 5(b) are explanatory diagrams showing configuration examples of radio resources (RE) of the time slot 431 at the time of initial transmission and HARQ retransmission of SL data transmission according to the reference example, respectively. AGC (automatic gain control), PSCCH, PSSCH, DMRS, and Guard (guard period) are assigned to the leading portion of the SL data transmission time slot 431 . AGC is information for controlling the gain of the receiving amplifier so that the receiving amplifier of the receiving side UE does not saturate. At the initial transmission of SL data transmission in FIG . At the time of HARQ retransmission of SL data transmission in FIG. 5(b), HARQ retransmission including PSFCH for returning HARQ response message (HARQ-ACK or HARQ-NACK) and Guard and AGC for the PSFCH Since the radio resource group 431a for SL is inserted, some radio resources cannot be used for SL data transmission.

Note that in the AGC (for PSFCH) interval (see FIG. 8) transmitted prior to the PSFCH of the HARQ retransmission request from the receiving-side UE 20R, the base station 10 receives the PSFCH without using Timing Advance and demodulation reference signals. In order to make it possible, a predetermined signal sequence whose reception timing can be detected (reception timing can be estimated) at the base station 10 is multiplexed and transmitted. As this signal sequence, for example, a CAZAC (Constant Amplitude and Zero Auto-Correlation Code) sequence such as a ZC (Zadoff-Chu) sequence that is also used in RACH (Random Access Channel) and the like can be used.

According to the example of FIG. 7, when the reception side UE 20R fails to receive the SL initial transmission data, the transmission side UE 20T from the reception side UE 20R to the transmission side UE 20T by the time the transmission side UE 20T transmits HARQ retransmission data to the reception side UE 20R HARQ retransmission delay can be reduced because only two stages of intermediate signaling processing of message transmission/reception (S206) to and from the base station 10 to the transmission side UE 20T (S208) are required.

When the base station 10 receives a HARQ retransmission request including a SL HARQ-NACK (negative acknowledgment) and a HARQ retransmission scheduling request message from the receiving side UE 20R, the SL HARQ-NACK (negative acknowledgment) and the SL HARQ retransmission are allocated. A grant message including radio resource information is transmitted to the transmitting side UE 20T by PDCCH (S307). The transmitting-side UE 20T can acquire SL HARQ-NACK information via the base station 10 without using the PSFCH.

Claims (15)

A base station of a mobile communication network having a function of communicating with a plurality of wireless terminal devices performing direct communication between terminals and capable of controlling radio resources used for the direct communication between terminals,
means for monitoring a feedback channel from a receiving-side wireless terminal device to a transmitting-side wireless terminal device for data transmission via the direct terminal communication, and decoding the feedback channel;
means for notifying the transmission-side wireless terminal of a grant message including information on radio resources for HARQ retransmission when the decoding result of the feedback channel includes a HARQ negative acknowledgment from the reception-side wireless terminal; and,
A base station comprising: A base station of a mobile communication network having a function of communicating with a plurality of wireless terminal devices performing direct communication between terminals and capable of controlling radio resources used for the direct communication between terminals,
means for receiving a feedback message including a HARQ negative acknowledgment and a radio resource allocation request from a wireless terminal receiving data transmission via the direct terminal communication;
means for transmitting, in response to the feedback message, a grant message including the HARQ negative acknowledgment and radio resource information for HARQ retransmission to a wireless terminal receiving the data transmission;
A base station comprising: A wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between terminals with peripheral wireless terminal devices,
radio resource for HARQ retransmission from the base station without receiving a HARQ negative acknowledgment from the peripheral wireless terminal device when data transmission is performed to the peripheral wireless terminal device via the terminal-to-terminal direct communication; means for receiving an authorization message containing information about
means for performing HARQ retransmission of the data transmission to the peripheral wireless terminal device in response to the grant message received from the base station without receiving an HARQ negative acknowledgment from the peripheral wireless terminal device;
A wireless terminal device comprising: A wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between terminals with peripheral wireless terminal devices,
means for receiving data transmission from the peripheral wireless terminal device via the direct communication between terminals;
means for transmitting a feedback message to the base station including a HARQ negative acknowledgment for the data transmission and a radio resource allocation request;
A wireless terminal device comprising: A wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between terminals with peripheral wireless terminal devices,
HARQ negative acknowledgment and HARQ retransmission from the base station without receiving a HARQ negative acknowledgment from the neighboring wireless terminal device when data transmission is performed to the neighboring wireless terminal device via the terminal-to-terminal direct communication. means for receiving a grant message containing information of radio resources for
means for performing HARQ retransmission of the data transmission to the peripheral wireless terminal device in response to the grant message received from the base station without receiving an HARQ negative acknowledgment from the peripheral wireless terminal device;
A wireless terminal device comprising: A system comprising the base station of claim 1 and the wireless terminal device of claim 3. A system comprising the base station of claim 2, the wireless terminal device of claim 4, and the wireless terminal device of claim 5. A vehicle traveling on a travel route,
A vehicle comprising the wireless terminal device according to any one of claims 3 to 5. A method for performing HARQ retransmission control in data transmission via direct communication between terminals,
monitoring a feedback channel from a wireless terminal device on the receiving side to a wireless terminal device on the transmitting side of data transmission via the direct communication between terminals, and decoding the feedback channel;
Notifying the wireless terminal device on the transmitting side of a grant message including information on radio resources for HARQ retransmission when the decoding result of the feedback channel includes a HARQ negative acknowledgment from the wireless terminal device on the receiving side. and,
A method comprising: A method for performing HARQ retransmission control in data transmission via direct communication between terminals,
Receiving a feedback message including a HARQ negative acknowledgment and a radio resource allocation request from a wireless terminal device receiving data transmission via the direct terminal communication;
transmitting, in response to the feedback message, a grant message including the HARQ negative acknowledgment and radio resource information for HARQ retransmission to a wireless terminal receiving the data transmission;
A method comprising: A program executed in a computer or processor provided in a base station of a mobile communication network that has a function of communicating with a plurality of wireless terminal devices that perform direct communication between terminals and is capable of controlling wireless resources used for direct communication between terminals There is
a program code for monitoring a feedback channel from a wireless terminal device on the receiving side to a wireless terminal device on the transmitting side of data transmission via the direct communication between terminals and decoding the feedback channel;
to notify the transmission-side wireless terminal of a grant message including information on radio resources for HARQ retransmission when the decoding result of the feedback channel includes a HARQ negative acknowledgment from the reception-side wireless terminal; program code for
A program characterized by comprising: A program executed in a computer or processor provided in a base station of a mobile communication network that has a function of communicating with a plurality of wireless terminal devices that perform direct communication between terminals and is capable of controlling wireless resources used for direct communication between terminals There is
a program code for receiving a feedback message including a HARQ negative acknowledgment and a radio resource allocation request from a wireless terminal device on the receiving side of data transmission via the direct terminal communication;
program code for transmitting, in response to the feedback message, a grant message including the HARQ negative acknowledgment and radio resource information for HARQ retransmission to a wireless terminal device receiving the data transmission;
A program characterized by comprising: A program to be executed in a computer or processor provided in a wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between terminals with peripheral wireless terminal devices,
radio resource for HARQ retransmission from the base station without receiving a HARQ negative acknowledgment from the peripheral wireless terminal device when data transmission is performed to the peripheral wireless terminal device via the terminal-to-terminal direct communication; program code for receiving an authorization message containing information about
Program code for performing HARQ retransmission of the data transmission to the peripheral wireless terminal device in response to the grant message received from the base station without receiving an HARQ negative acknowledgment from the peripheral wireless terminal device. and,
A program characterized by comprising: A program to be executed in a computer or processor provided in a wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between terminals with peripheral wireless terminal devices,
a program code for receiving data transmission from the peripheral wireless terminal device via the terminal-to-terminal direct communication;
program code for transmitting a feedback message including a HARQ negative acknowledgment for the data transmission and a radio resource allocation request to the base station;
A program characterized by comprising: A program to be executed in a computer or processor provided in a wireless terminal device having a function of performing communication via a base station of a mobile communication network and a function of performing direct communication between terminals with peripheral wireless terminal devices,
HARQ negative acknowledgment and HARQ retransmission from the base station without receiving a HARQ negative acknowledgment from the neighboring wireless terminal device when data transmission is performed to the neighboring wireless terminal device via the terminal-to-terminal direct communication. program code for receiving a grant message including radio resource information for
Program code for performing HARQ retransmission of the data transmission to the peripheral wireless terminal device in response to the grant message received from the base station without receiving an HARQ negative acknowledgment from the peripheral wireless terminal device. and,
A program characterized by comprising:

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