KR20170036598A - Method and apparatus for vehicle-to-vehicle communication using direct communication in mobile communication system - Google Patents

Abstract

The purpose of the present invention is to provide vehicle-to-vehicle data communication in a mobile communication system by performing direct communication by a vehicle terminal mounted in a vehicle. According to the present invention, in a method of a vehicle terminal communicating with another vehicle terminal using a direction communication, the method comprising the following steps of: the vehicle terminal dividing a radio resource region by priority; when data of a first priority to be transmitted occurs, transmitting an identification signal for notifying transmission of the data of the first priority by using set identified resource; checking presence of a signal transmitted from another vehicle terminal in the identified resource before transmitting data of a second priority lower than the first priority in a radio resource region corresponding to the second priority; when a signal from the another vehicle terminal is detected in the identified resource, receiving the data of the first priority transmitted by the another vehicle terminal in a radio resource region corresponding to the first priority; and transmitting the data of the second priority in the radio resource region corresponding to the second priority.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for communicating between vehicles using direct communication in a mobile communication system,

The present invention relates to a vehicle communication method using direct communication in a mobile communication system, and more particularly, to a vehicle communication method in which a mobile communication terminal mounted on a vehicle transmits and receives data in a direct communication manner with a mobile communication terminal mounted on a nearby vehicle .

In the 3GPP standardization organization, standardization activities of direct communication technology between terminals are performed, and the efficiency of direct communication is increased through management of base stations in a mobile communication environment. In addition, by using the direct communication function in the vehicle communication (Vehicular Communication or Vehicle to Everything, V2X) service, the traffic safety and the road efficiency of the vehicle are increased, and the Internet service is provided to the devices in the vehicle, Research is underway to support the Connected Car function. The vehicle terminal located within the communication radius of the base station can communicate with the general terminal and the roadside apparatus by using the wireless connection with the base station and improve the communication function between the vehicles.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle communication method and apparatus using direct communication in which a vehicle terminal mounted on a vehicle directly communicates with a vehicle to provide data communication between vehicles and communication with a peripheral device .

According to one embodiment of the present invention, a method is provided in which a vehicle terminal communicates with another vehicle terminal using direct communication. The inter-vehicle communication method includes the steps of: prioritizing a radio resource region; transmitting an identification signal for informing data transmission of the first priority using an established identification resource when data of a first priority to be transmitted occurs; , Checking whether there is a signal transmitted from another vehicle terminal in the identified resource before transmitting the data of the second priority lower than the first priority in the radio resource region corresponding to the second priority, Receiving a first priority data transmitted from the other vehicle terminal in a radio resource region corresponding to the first priority when a signal from the other vehicle terminal is detected in the resource, And transmitting the second priority data in the radio resource region corresponding to the second priority.

According to the embodiment of the present invention, a vehicle terminal mounted on a vehicle or held by a passenger can provide a vehicle mobile communication role to a peripheral terminal.

1 is a diagram illustrating an example of a wireless communication network to which an embodiment of the present invention is applied.
2 is a diagram illustrating a communication node constituting the wireless communication network shown in FIG.
3 is a diagram illustrating an example of a V2X communication environment according to an embodiment of the present invention.
4 is a diagram illustrating a radio resource region of inter-vehicle communication according to an embodiment of the present invention.
5 is a diagram illustrating an example of a transmission method using direct communication according to an embodiment of the present invention.
6 and 7 are views showing another example of a radio resource region used by a vehicle terminal in inter-vehicle communication according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification and claims, when a section is referred to as "including " an element, it is understood that it does not exclude other elements, but may include other elements, unless specifically stated otherwise. Also, the terms "first "," second ", and the like can be used to describe various components, but the components are not limited by terms such as " first " The terms "first "," second ", and the like are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Throughout the specification, a terminal is referred to as a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station (HR- A subscriber station (SS), a portable subscriber station (PSS), an access terminal (AT), a user equipment (UE) , HR-MS, SS, PSS, AT, UE, and the like.

Also, a base station (BS) is an advanced base station (ABS), a high reliability base station (HR-BS), a node B, an evolved node B, ), An access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR) -BS, a relay station (RS), a relay node (RN) serving as a base station, an advanced relay station (ARS) serving as a base station, a high reliability relay station (HR- A femto BS, a home Node B, a home eNodeB, a pico BS, a metro BS, a micro BS, Etc.) or all or some of the ABS, Node B, eNodeB, AP, RAS, BTS, MMR-BS, RS, RN, ARS, HR- There's also an included feature.

A method and apparatus for communication between vehicles using direct communication in a mobile communication system according to an embodiment of the present invention will now be described in detail with reference to the drawings.

First, a wireless communication network to which embodiments of the present invention are applied will be described. The wireless communication networks to which the embodiments according to the present invention are applied are not limited to those described below, and the embodiments according to the present invention can be applied to various wireless communication networks. Here, the wireless communication network may be used in the same sense as a wireless communication system.

1 is a diagram illustrating an example of a wireless communication network to which an embodiment of the present invention is applied.

Referring to FIG. 1, a wireless communication network 100 includes a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3 , 130-4, 130-5, and 130-6. A plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, May each support at least one communication protocol. For example, a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-6 may be respectively a communication protocol based on code division multiple access (CDMA), a communication protocol based on wideband CDMA (WCDMA), a communication protocol based on time division multiple access (TDMA), a communication based on frequency division multiple access Protocol, an orthogonal frequency division multiplexing (OFDM) based communication protocol, an orthogonal frequency division multiple access (OFDMA) based communication protocol, and a single carrier (FD) based communication protocol. A plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, May have a structure as shown in FIG. 2, respectively.

2 is a diagram illustrating a communication node constituting the wireless communication network shown in FIG.

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to the network to perform communication. The communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, and the like. Each component included in the communication node 200 may be connected by a bus 270 and communicate with each other.

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods in accordance with embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be constituted of at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may comprise at least one of read-only memory (ROM) and random access memory (RAM).

1, the communication nodes 110-1, 110-2, 110-3, 120-1 and 120-2 may be base stations, and the communication nodes 130-1, 130-2, 130 -3, 130-4, 130-5, and 130-6 may be a User Equipment (UE). For convenience of description, the communication nodes 110-1, 110-2, 110-3, 120-1, and 120-2 are referred to as first to fifth base stations 110-1, 110-2, 110-3, 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 are referred to as first to sixth UEs (user equipment. The first to sixth UEs 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may be a UE or a vehicle occupant mounted on the vehicle described in the embodiment of the present invention. May be a terminal.

Each of the first base station 110-1, the second base station 110-2 and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third UE 130-3 and the fourth UE 130-4 may belong to the cell coverage of the first base station 110-1. The second UE 130-2, the fourth UE 130-4 and the fifth UE 130-5 may belong to the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth UE 130-4, the fifth UE 130-5 and the sixth UE 130-6 can belong to the cell coverage of the third base station 110-3 have. The first UE 130-1 may belong to the cell coverage of the fourth base station 120-1. The sixth UE 130-6 may belong to the cell coverage of the fifth base station 120-2.

The first to fifth base stations 110-1, 110-2, 110-3, 120-1 and 120-2 and the first to sixth UEs 130-1, 130-2, 130-3 and 130-4 130-5 and 130-6 can each support cellular communication (e.g., long term evolution (LTE), advanced LTE-A (advanced), etc. defined in 3GPP have. The first to fifth base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands and operate in the same frequency band. The first to fifth base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other via an ideal backhaul or a non-idle backhaul , An ideal backhaul or a non-ideal backhaul. The first to fifth base stations 110-1, 110-2, 110-3, 120-1 and 120-2 are connected to a core network (not shown) through an ideal backhaul or a non-ideal backhaul, respectively . The first to fifth base stations 110-1, 110-2, 110-3, 120-1 and 120-2 transmit signals received from the core network to the corresponding UEs 130-1, 130-2, 130- 130-2, 130-3, 130-4, 130-5, and 130-6, and transmits the signals received from the corresponding UEs 130-1, 130-2, 130-3, To the core network.

The first to fifth base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can support OFDMA-based downlink transmission, Link (uplink) transmission. Each of the first to fifth base stations 110-1, 110-2, 110-3, 120-1, and 120-2 includes a multiple input multiple output (MIMO) transmission (e.g., a single user- (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, direct device to device communication (MIMO, MU, MIMO, massive MIMO etc.) , D2D) [or ProSe (proximity services)]. The first to sixth UEs 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 are connected to the base stations 110-1, 110-2, 110-3, 120-1, and 120-2 and the operations supported by the base stations 110-1, 110-2, 110-3, 120-1, and 120-2.

For example, the second base station 110-2 may transmit a signal to the fourth UE 130-4 based on the SU-MIMO scheme, and the fourth UE 130-4 may transmit a signal based on the SU-MIMO scheme And may receive a signal from the second base station 110-2. Or the second base station 110-2 may transmit a signal to the fourth UE 130-4 and the fifth UE 130-5 based on the MU-MIMO scheme, and the fourth UE 130-4 and / Each of the fifth UEs 130-5 may receive a signal from the second base station 110-2 by the MU-MIMO scheme. Each of the first base station 110-1, the second base station 110-2 and the third base station 110-3 can transmit a signal to the fourth UE 130-4 based on the CoMP scheme, The UE 130-4 can receive signals from the first base station 110-1, the second base station 110-2 and the third base station 110-3 by the CoMP scheme. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 includes UEs 130-1, 130-2, 130-3, 130-4 , 130-5, and 130-6) and a CA scheme. Each of the first base station 110-1, the second base station 110-2 and the third base station 110-3 coordinates D2D between the fourth UE 130-4 and the fifth UE 130-5 and the fourth UE 130-4 and the fifth UE 130-5 may perform D2D by coordination of the second base station 110-2 and the third base station 110-3, can do.

3 is a diagram illustrating an example of a V2X communication environment according to an embodiment of the present invention.

3, a vehicle communication (V2X, Vehicle to Everything, V2X) is a vehicle on a road such as a V2V (Vehicle-to-Vehicle), a V2I (Vehicle-to-Infra) Refers to all types of communication technologies applicable to the vehicle, and transmits and receives data necessary for improving road safety and traffic efficiency of the vehicle. V2V uses direct communication (D2D) method, and V2N uses base station-terminal interface.

A terminal mounted on a vehicle or a terminal held by a vehicle occupant (hereinafter referred to as "vehicle terminal") may be located in a coverage area of a base station, temporarily out- Lt; / RTI >

The frequency band F1 used for V2V may be allocated exclusively, in which case the direct vehicle-to-vehicle communication may be done using an independent frequency band F2. In addition, V2V and a common mobile communication system (e.g., LTE system) can share a frequency band. V2X assumes V2V dedicated frequency environment and base station environment.

Since V2X sends and receives the data required for traffic safety and road efficiency management, it supports priority and QoS (Quality of Service) according to the characteristics of data. In other words, data that is event-driven to be urgently processed and transmitted periodically may be transmitted at a higher priority and lower priority.

The upper layer of the vehicle terminal needs a buffer for storing and transmitting data generated by the application to support priority and QoS. To this end, the vehicle terminal uses buffers classified according to service priorities, and receives data transmitted by applications according to characteristics. The buffers are mapped to logical channels separated according to data characteristics (for example, QoS), and allocate and transmit radio resources in the L2 / L3 layer. V2X applications and upper layers manage to prevent excessive data from being generated when generating data.

That is, in case of information generated periodically, if there is a possibility that an excessive amount of data may be generated within a predetermined time by a plurality of applications, the data generation amount may be reduced in the application or buffer management step, or data having a low priority or QoS may be deleted. For example, data for vehicle communication occurring at intervals of 100 ms, such as vehicle position information, vehicle speed, etc., may be generated at a cycle of 200 ms or generated data may be deleted from the buffer if the communication load is large. Such a procedure may operate in conjunction with an RRC (Radio Resource Control) layer and a MAC (Media Access Control) layer and an upper layer.

In inter-vehicle communication, that is, V2V, the vehicle terminal transmits data in a broadcast manner and performs scheduling in an autonomous resource allocation manner. For scheduling, a maximum allowed data rate of the vehicle terminal is set. The maximum transmission allowable data rate may be transmitted to the vehicle terminal or pre-defined in the vehicle terminal. Thus, it is possible to limit the monopoly of a resource generated when one vehicle terminal transmits excessive data. When the base station transmits the maximum transmission permissible data rate of the vehicle terminal to the vehicle terminal, the base station can broadcast the system information through a channel for transmitting the system information, and this value can be managed by the base station. This value can be designated for each cell and can be fixedly designated by the location of the base station (urban, highway, etc.), or can be variably specified depending on the average speed, density, etc. of the vehicle in the cell.

FIG. 4 is a diagram illustrating a radio resource region of inter-vehicle communication according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating an example of a transmission method using direct communication according to an embodiment of the present invention.

4, a radio resource area (for example, a resource pool) used when a vehicle terminal transmits data between vehicles is divided into a control channel area (SC (Sidelink Control) pool) and a data channel area , And a control channel region (SC pool) and a data channel region (data pool) may be repeated with a certain period (SC Period). The control channel region (SC pool) and the data channel region (data pool) may be divided into a plurality of subintervals in the time domain. In this case, the length of one sub-section may be equal to the length of one sub-frame in the LTE system or may be set differently. Also, the radio resource region may be composed of a predetermined number of physical resource blocks (PRBs) on the frequency axis. That is, a plurality of PRBs may be bundled to form one radio resource region.

A control channel is allocated to a control channel region (SC pool), and a control channel transmits control information necessary for the receiving terminal to demodulate the data channel. The data channel is assigned a data channel for transmitting actual data.

The vehicle terminal selects a radio resource on the time axis and a frequency axis and uses it for data transmission.

In order to increase the reception performance, as shown in Fig. 5, the vehicle terminal can transmit the control channel C repeatedly twice, and transmit the data channel D four times repeatedly.

The radio resource area used when the vehicle terminal transmits data between vehicles may be preset in the vehicle terminal or may be designated through a channel through which the base station transmits system information.

The distributed resource allocation scheme is a scheme in which a vehicle terminal arbitrarily selects and transmits radio resources (for example, time and frequency locations) to be actually used within a corresponding radio resource region. The size of the resource to be transmitted, the modulation / demodulation information, the transmission power magnitude, and the like can be determined in consideration of the state of the buffer of the vehicle terminal.

A method of distributing and allocating a radio resource region using a value calculated by a terminal identifier or the like is possible as a method of lowering the collision probability due to the random selection of radio resources. Specifically, the vehicle terminal performs a modulo operation on the terminal identifier and uses the radio resource region according to the value. By doing so, the vehicle terminals having the same value use a certain radio resource region, and accordingly, the radio resource region used by the vehicle terminal can be dispersed.

6 and 7 are views showing another example of a radio resource region used by a vehicle terminal in inter-vehicle communication according to an embodiment of the present invention.

6 and 7, a plurality of radio resource regions used by one vehicle terminal can be designated (for example, four).

Specifically, as shown in FIG. 6, a plurality of radio resource regions used by one vehicle terminal can be assigned to the same frequency region and the same time region. Therefore, in a plurality of radio resource regions used by one vehicle terminal, a control channel region (SC pool) can be allocated at the same time. For example, all radio resource regions may be started at the same time (for example, 0 ms).

Also, as shown in FIG. 7, a plurality of radio resource regions may be sequentially allocated in a time domain so that a control channel region (SC pool) of a plurality of radio resource regions is continuous in time. For example, when the time interval of the control channel region is set to 10 ms, the first radio resource region starts at 0 ms, the second radio resource region starts at 10 ms, the third radio resource region starts at 20 ms, The fourth radio resource region may start at 30ms.

The data channel starts from behind the SC channel and is maintained for the SC period, and the time length of each radio resource zone may be different. As shown in FIG. 7, when the positions of the control channels are different in a plurality of radio resource regions, the time required for the vehicle terminal to wait for a long time to transmit data is reduced.

When direct communication between vehicles is performed in an independent frequency band, it is possible to broadcast a channel for managing vehicle communication. The device broadcasting the channel may be a terminal transmitting the synchronization signal and directly broadcasts the communication cell configuration information (e.g., bandwidth, ID, time information, in-coverage identification, etc.) together with the synchronization signal. In addition, by broadcasting the radio resource region information and neighboring usable frequency information, the vehicle terminal can receive the information and perform direct communication. In this case, the vehicle terminal can perform inter-vehicle communication using only the independent frequency.

Hereinafter, a vehicle-to-vehicle communication method of a vehicle terminal according to an embodiment of the present invention will be described in more detail.

[V2X communication priority management method]

The vehicle terminal can transmit data according to the priority order. The method of transmitting data according to the priority order can be applied as follows.

As a method 1, a vehicle terminal can distinguish a radio resource region according to a priority order, and transmit data to a radio resource region mapped to a priority order at the time of transmission. Specifically, the vehicle terminal manages the state of the buffer, selects a radio resource region mapped to a high priority when data is input to a high priority buffer, and selects and transmits radio resources within the selected radio resource region. In this case, the radio resource region having a high priority is designated to a large extent to lower the collision probability.

As a method 2, when a plurality of radio resource areas to be used by the vehicle terminal are designated, the vehicle terminal uses a lot of radio resource areas when transmitting high priority data. That is, the vehicle terminal selects and transmits radio resources in one radio resource region in the case of low priority data, and selects and transmits radio resources in a plurality of radio resource regions in the case of high priority data.

Method 3 is a method of applying the transmission probability according to the priority order. Specifically, the vehicle terminal uses the transmission probability value and designates the transmission probability value according to the priority. For example, the vehicle terminal may designate a transmission probability value of 1 in a high priority buffer to always transmit data in a high priority buffer, and a transmission probability value (e.g., 0.25) in a low priority buffer, To transmit data of the low priority buffer with a probability of 1/4.

Method 4 is a method of specifying a transmission time position in accordance with a priority order. Specifically, the transmission opportunity of the data channel in one radio resource region is repeated a predetermined number of times within the SC period. The vehicle terminal assigns high priority data to the previous transmission opportunity in time and transmits the low priority data, and transmits the low priority data to the transmission opportunity later in time, thereby reducing the transmission time.

The size and the transmission probability value of the radio resource region mentioned above can be set to a variable value of the base station, and the mobile terminal can be instructed through the channel for transmitting the system information. In this case, the base station can adjust the collision probability by variably designating the size of the radio resource region and the transmission probability value according to the cell environment.

[Configuration method of control channel]

In order to reduce the transmission latency of direct communication between vehicles and to increase the transmission efficiency, the vehicle terminal can simultaneously transmit the control channel and the data channel, or omit the control channel.

A method of simultaneously transmitting a control channel and a data channel is to transmit the control channel and the data channel in the same subframe (1 ms) so that the receiving terminal simultaneously receives the control channel and the data channel. In this case, there is a method of assigning the control channel to the front part (for example, the first slot) of the subframe and allocating the data channel to the rear part (for example, the second slot) of the subframe.

There is also a method of including a control channel in a data channel. In this case, the control channel is located inside the data channel. Control channel symbols may be disposed adjacent to a DMRS (Modulation Reference Signal), or control channel symbols may be distributed and allocated to data channel allocation resources. In this case, the receiving terminal first extracts the control channel at a predetermined position by receiving one subframe, and demodulates the data channel using the extracted control information. In this case, since the control channel is repeatedly transmitted twice and the data channel is repeatedly transmitted four times, it is divided into a portion for transmitting the control channel and the data channel together and a portion for transmitting only the data channel. That is, the control channel is transmitted twice in the data channel, and only the data channel is transmitted in the data channel twice.

Some control channel information may be preset or omitted in order to reduce the amount of data transmitted to the control channel. The method of omitting is to transmit the size of the data channel using a fixed size, and the receiving terminal processes all packets received and successfully demodulated with valid data. The information used as semi-static to reduce the control channel can be broadcasted or set by the base station as the system information, and the receiving terminal can use the information to demodulate it. For example, the frequency hopping flag is used as a fixed value, the Sidelink Control Layer-1 ID is used as a single identifier in V2X, and the TAI (Timing Advance Indication) is used as a V2X And the modulation and coding scheme may be a fixed value for each cell. Therefore, the transmission of information such as the frequency hopping flag, the side link control layer-1 identifier, the TAI, and the modulation and coding scheme can be omitted. Also, the resource allocation information is represented by time-axis information and frequency-axis information, thereby reducing the number of bits used for resource allocation information.

[Method for avoiding collision of control channel]

Since direct communication between vehicles is transmitted in a broadcast manner, it is difficult for the transmitting vehicle terminal to confirm receipt and collision with another transmitting vehicle terminal. A method for solving such a problem is proposed in which an identification signal in a control channel region transmitted by another vehicle terminal is received and transmitted when another vehicle terminal does not transmit the identification signal.

First, the first symbol of the control channel can be used as an indicator signal. The transmitting terminal transmits a signal to the first symbol of the control channel and then transmits the remaining control channel and data channel. The other vehicle terminal receives the first symbol of the control channel and transmits the control channel and the data channel when the other terminal is empty.

Alternatively, the entire control channel can be used as an identification signal, in which case it can only be used when transmitting large data.

Alternatively, there may be a method of reducing collisions by preferentially processing high priority radio resources. First, the radio resource region is classified in priority order, and when transmitting high priority data, the transmitting vehicle terminal transmits a signal using a separate identification resource. The other transmitting vehicle terminal first receives the identification resource before transmitting it to the low priority radio resource region and performs the transmitting operation if there is no signal. However, when a signal is detected in the identification resource, the vehicle terminal receives a high priority area without transmitting low priority data.

The vehicle terminal can indirectly measure the use state of the radio resource. The vehicle terminal receives the control channel, measures the usage, and reports the measured information to the base station. The base station calculates the usage rate of the control channel and broadcasts the usage rate of the control channel through the channel for transmitting the system information. The vehicle terminal can control the transmission based on the utilization rate information of the control channel, thereby varying the collision probability at the time of transmission.

The vehicle terminal can measure the received power of the control channel and the data channel or measure the received power of the DMRS symbol. Also, the vehicle terminal can measure the received power using only the control channel successfully demodulated, and can combine the received power, the received power of the DMRS symbol, and the received power of the demodulated control channel. The measured information may be transmitted via a Radio Resource Control (RRC) message to the base station.

[Configuration of data channel]

In the direct communication between vehicles, many vehicle terminals arbitrarily select radio resources in the radio resource region using a distributed allocation scheme and use them for data transmission. Therefore, there is a need for a method for increasing the transmission performance by lowering the time axis collision probability of the inter-terminal transmission resources. In the structure in which the data channel is transmitted four times for collision avoidance and transmission performance, the temporal position of the fourth transmission is designated in the data channel region, and the transmission pattern is represented by a bitmap. For example, the transmitter configures various transmission combinations (e.g., a Transmit Resource Pattern) representing four transmission subframes in a bitmap represented by 8 bits, and the vehicle terminal constructs one transmission combination (for example, '11001010' ) Is selected and used for transmission. The transmit combination is repeated for the SC period.

As a method for reducing the collision probability, the length of the transmission combination is set to be long, and the vehicle terminal uses the corresponding combination. Specifically, a transmission combination in which four transmission sub-frames are displayed in 16 bits is configured. In this case, the time to transmit one data becomes longer from 8 ms to 16 ms, resulting in a time delay.

Alternatively, it is possible to perform an operation of receiving another data channel without transmitting at some opportunity among the four transmission opportunities. Specifically, the vehicle terminal transmits the data channel only three times in four transmission patterns, performs the receiving operation once at a randomly selected time, and can demodulate the data of the other vehicle terminals.

[Signaling Method with Base Station]

In order to avoid the problem of the distributed allocation scheme mainly used in direct communication between vehicles, the vehicle terminal can operate in a central control manner under the control of the base station. Specifically, the vehicle terminal transmits control information and transmits transmission data information to the base station, and the base station allocates radio resources (for example, a control channel and a data channel transmission resource). The transmitting vehicle terminal can transmit the vehicle communication data using the allocated radio resources. This procedure requires a signaling procedure between the base station and the vehicle terminal, which causes a time delay. In order to avoid this, the vehicle terminal can transmit the data generated by the periodic (for example, 100 ms) for the first time by the distributed allocation method, and transmit the subsequent periodic data by the central control method.

To this end, the transmitting terminal performs a resource allocation request procedure to the base station when transmitting data. The request information may include the data transmission period or start time and the size of the data. Upon receipt of the request information, the base station analyzes the use state of the resource, allocates radio resources to be transmitted and transmits the allocated radio resources to the transmitting terminal, and indicates that the radio resources are periodically allocated (for example, 100 ms). The base station can immediately transmit an allocation or activation message or transmit an allocation message when the vehicle terminal has reached a predetermined period, and can display the start time of transmission data in the allocation message.

Upon receiving the radio resource allocation information from the base station, the vehicle terminal transmits the control channel and the data channel using the control information allocated by the base station when new data is input. The base station can use the time window information to be transmitted, and the vehicle terminal can transmit the data within the window time range.

The characteristics of the data are classified according to the logical channels mapped in the upper layer, and the period of the data generated periodically may not be accurate. Therefore, data generated later than a designated period can be transmitted in a distributed control manner.

The periodically allocated radio resources may be deactivated by the base station or the vehicle terminal may stop using a timer. That is, if data is not input more than two times, it can be treated that the periodically allocated radio resource is released, and the vehicle terminal can periodically report the buffer information to the base station. When the vehicle terminal performs the handover, the serving cell can periodically transmit the allocated information to the target cell.

The performance of the inter-vehicle communication can be improved by using the transmission radius of the downlink channel of the base station. Specifically, when a transmission radius required for data to be broadcasted by direct communication is required, the vehicle terminal may transmit data to the base station, and the base station may transmit the data to the peripheral vehicle terminal or broadcast the downlink data.

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, Such an embodiment can be readily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (1)

A method for a vehicle terminal to communicate with another vehicle terminal using direct communication,
Dividing a radio resource region into priorities;
Transmitting an identification signal for informing the data transmission of the first priority using the set identification resource when data of a first priority to be transmitted occurs,
Confirming whether there is a signal transmitted from another vehicle terminal in the identified resource before transmitting the data of the second priority lower than the first priority in the radio resource region corresponding to the second priority;
Receiving the first priority data transmitted from the other vehicle terminal in a radio resource region corresponding to the first priority when a signal from the other vehicle terminal is detected in the identified resource,
Transmitting the data of the second priority order in the radio resource region corresponding to the second priority order
Vehicle communication method.

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