KR20190048305A - Method for vehicle to vehicle multicast and message retransmission, and apparatus for the same - Google Patents

Abstract

The present invention relates to a method and apparatus for retransmitting a multicast and a message between vehicles, capable of increasing reliability of a group multicast between vehicles in a vehicle network for cluster driving and improving radio resource efficiency when retransmitting an error message. To achieve the purpose of the present invention, a driving method of a communications terminal arranged in one group leader of a cluster driving group consisting of the group leader and a plurality of group members, comprises the following steps of: transmitting a message including information for cluster driving to the group members in a multicast method; receiving a feedback message for the message from each of the group members; and retransmitting the message to one or more group members who have requested retransmission of the message based on the feedback message.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for multi-

The present invention relates to a method and apparatus for inter-vehicle multicast and message retransmission, and more particularly, to a method and system for inter-vehicle multi-vehicle communication in which the reliability of inter-vehicle group multicast is increased in a cluster driving vehicle network, And a method and apparatus for retransmitting a message and a message.

Recently, as interest in autonomous vehicles has increased, discussions are underway to develop technologies that can support platooning using 5G mobile communication. The trucks and buses are expected to be economically effective because they have characteristics similar to those of conventional trains. It is expected that the trucking cluster will have a positive effect on the freight transportation industry, such as excellent fuel economy, lower incidence of accidents, solving truck driver shortage problem, compared with general truck driving. The crowd driving is a method in which a plurality of vehicles connected by a vehicle-to-vehicle (V2V) line runs on the road. In such a crowd driving, the leading vehicle can control the steering device, the excel and the brake of the rear vehicle together to keep the interval of the vehicle constant, so that the air resistance can be lowered to increase the fuel efficiency and reduce the exhaust gas emission.

We are also developing technology to support V2X (Vehicle-to-Everything) service in 4G and 5G mobile communication. Prior to the development of V2X technology, device-to-device (D2D) technology was developed first, and application of D2D communication method to V2V is considered.

D2D technology is a technology developed to achieve capacity increase and cell coverage increase of a mobile communication network by performing direct communication between terminals using a frequency band in which a mobile terminal communicates with a base station. In terms of direct communication between terminals, V2V is similar to D2D, but it is difficult to apply D2D technology developed for direct communication between general user terminals to V2V service which requires a very high level of 'safety' . That is, it is necessary to improve the communication reliability of the D2D method to a level suitable for the V2V service and apply it to the V2V service. As an example, D2D uses a 'broadcast' scheme for data transmission between terminals. This is a structure in which the same data message is repeatedly transmitted 2-3 times without Hybrid Automatic Repeat Request (HARQ) feedback between the transmitting and receiving terminals, and this method will not satisfy the communication reliability required for the V2V service do. Therefore, it is required to develop a method and apparatus for inter-vehicle multicast and message retransmission for driving a vehicle cluster.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for inter-vehicle multicast and message retransmission capable of supporting stable vehicle cluster travel by utilizing 5G mobile communication technology.

An object of the present invention is to provide a method and apparatus for inter-vehicle multicast and message retransmission, which can increase the reliability of group multicast in V2V communication and increase radio resource efficiency upon retransmission of an error message based on HARQ feedback.

According to another aspect of the present invention, there is provided a method for driving a communication terminal disposed in a group leader among a group driving group including a group leader and a plurality of group members, Sending a message comprising a plurality of group members in a multicast manner to the plurality of group members; receiving a feedback message for the message from each of the plurality of group members; And retransmitting the message to the one or more group members that requested it.

In the method of driving a communication terminal according to the present invention, in the step of retransmitting the message, when the number of group members requesting retransmission of the message is more than a predetermined number, the message is retransmitted in a multicast manner.

According to another aspect of the present invention, there is provided a method of retransmitting a message in a unicast manner when a number of group members requesting retransmission of the message is less than a predetermined number.

The method of driving a communication terminal according to the present invention is characterized in that, prior to the step of transmitting the message, a vehicle positioned at the head of the cluster driving group at the time of formation of the intervehicular communication network transmits instruction information indicating that the vehicle is the group leader, To the member.

In the method of driving a communication terminal of the present invention, in the step of transmitting the message, the message is transmitted to the plurality of group members using a PC5 interface supporting a near service.

In the method of driving a communication terminal of the present invention, in the step of transmitting the message, the message including the ID of the group leader is transmitted to the message.

In the method of driving a communication terminal of the present invention, in transmitting the message, the message including the group ID of the group member is transmitted to the message.

According to another aspect of the present invention, there is provided a method for driving a communication terminal disposed in a group leader among a group driving group including a group leader and a plurality of group members, Receiving a plurality of feedback messages for each of the plurality of messages from each of the plurality of group members; transmitting a plurality of feedback messages to the plurality of group members in a multicast manner; Generating an index code message by index-coding the plurality of messages requested to be retransmitted based on the index code message; and transmitting the index code message to the plurality of group members.

In the method of driving a communication terminal according to the present invention, in the step of generating the index code message, side information including information on a transmission succeeded based on the plurality of feedback messages is generated. The index code message is generated based on the side information.

The method of driving a communication terminal according to the present invention transmits the index code message in a multicast manner when the number of group members requesting retransmission of the plurality of messages is more than a predetermined number in the step of transmitting the index code message.

In the method of driving a communication terminal according to the present invention, in the step of retransmitting the message, when the number of group members requesting retransmission of the plurality of messages is less than a predetermined number, the index code message is transmitted in a unicast manner.

In the method of driving a communication terminal of the present invention, in the step of transmitting the plurality of messages, the plurality of messages are transmitted to the plurality of group members by using a PC5 interface supporting proximity services.

The method of driving a communication terminal according to the present invention is characterized in that, prior to the step of transmitting the plurality of messages, a vehicle positioned at the head of the cluster driving group at the time of forming the intervehicular communication network transmits instruction information, To a group member of the second group.

According to another aspect of the present invention, there is provided a method of driving a communication terminal disposed in a first group member of a group driving group including a group leader and a plurality of group members, The method comprising the steps of: receiving in a multicast manner a message including information for a cluster movement; transmitting a feedback message to the group leader, the feedback message including information on the success or failure of receipt of the message; And receiving a retransmitted message from the group leader.

In the method of driving a communication terminal according to the present invention, when receiving the retransmitted message, when the number of group members requesting retransmission of the message is more than a predetermined number, the retransmitted message is received in a multicast manner.

In the method of driving a communication terminal according to the present invention, in the step of receiving the retransmitted message, when the number of group members requesting retransmission of the message is less than a predetermined number, the retransmitted message is received in a unicast manner.

According to the present invention, In the step of transmitting the feedback message, the feedback message is transmitted to the group leader using the PC5 interface supporting the near service.

In the method of driving a communication terminal of the present invention, in the step of transmitting the feedback message, And transmits the feedback message including the ID of the communication terminal of the group member and the ID of the group leader.

A method of driving a communication terminal according to the present invention includes the steps of: receiving from a group leader a plurality of messages including information for the cluster running from the group leader in a multicast manner; and transmitting a plurality of feedback messages for each of the plurality of messages to the group And transmitting the retransmitted message to the reader; and receiving the retransmitted message from the group leader based on the plurality of feedback messages. The retransmitted message is an index code message generated by index-coded the plurality of messages.

The method of driving a communication terminal according to the present invention is characterized in that, prior to the step of receiving the plurality of messages, when forming an inter-vehicle communication network, instruction information indicating that the vehicle is the group leader is received from a vehicle positioned at the head of the community driving group .

According to the present invention, reliability of multicast and error message retransmission between V2V terminals at the time of vehicle cluster traveling can be improved, and stability of the vehicle community traveling can be improved. In addition, according to the present invention, an index coding scheme can be applied to retransmit an error message based on HARQ feedback, thereby improving the efficiency of radio resources.

1 is a conceptual diagram showing a first embodiment of a communication system.
2 is a block diagram showing a first embodiment of a communication node constituting a communication system.
3 is a view showing the types of vehicle-to-everything (V2X).
4 is a view for explaining the concept of platooning of a vehicle.
5 is a diagram showing a communication link of a vehicle-to-everything (V2X) communication.
6 is a diagram illustrating a Proximity Service (ProSe) interface structure.
7 is a diagram illustrating a format of a data packet address and a group communication method of a near-service PC 5 interface.
8 is a diagram illustrating a V2V group multicast method for cluster travel.
Figure 9 is a diagram illustrating a V2V group multicast and feedback method for cluster travel.
10 is a diagram showing a method of transmitting and feedbacking a plurality of messages in a multicast manner.
11 is a diagram illustrating an example of an index encoding method upon retransmission of a message according to a feedback result.
12 is a diagram illustrating another example of an index encoding method in retransmitting a message according to a feedback result.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms 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. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a conceptual diagram showing a first embodiment of a communication system.

1, a communication system 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. Here, the communication system 100 may be referred to as a " communication network ". Each of the plurality of communication nodes may support at least one communication protocol. For example, each of the plurality of communication nodes may be a wireless communication device based on a communication protocol based on a code division multiple access (CDMA) communication protocol, a communication protocol based on a wideband CDMA (WCDMA), a communication protocol based on a time division multiple access (TDMA) based communication protocol, an orthogonal frequency division multiplexing (OFDM) based communication protocol, an OFDMA (orthogonal frequency division multiple access) based communication protocol, a single carrier-FDMA based communication protocol, a non-orthogonal multiple access-based communication protocol, and a space division multiple access (SDMA) -based communication protocol. Each of the plurality of communication nodes may have the following structure.

2 is a block diagram showing a first embodiment of a communication node constituting a communication system.

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).

Referring again to FIG. 1, the communication system 100 includes a plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2, a plurality of user equipments ) 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. 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 terminal 130-3 and the fourth terminal 130-4 may belong to the coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4 and the fifth terminal 130-5 may belong to the coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5 and the sixth terminal 130-6 may belong to the coverage of the third base station 110-3 . The first terminal 130-1 may belong to the coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the coverage of the fifth base station 120-2.

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1 and 120-2 includes a Node B, an evolved Node B, a base transceiver station (BTS) A radio base station, a radio transceiver, an access point, an access node, a roadside unit (RSU), a radio remote head (RRH), a transmission point (TP) , A transmission and reception point (TRP), a relay node, and the like. Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 includes a terminal, an access terminal, a mobile terminal, May be referred to as a station, a subscriber station, a mobile station, a portable subscriber station, a node, a device, and the like.

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, Each may support cellular communication (e.g., long term evolution (LTE), LTE-A (advanced), etc. defined in 3GPP standards). Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands, or may operate in the same frequency band. Each of the plurality of 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-ideal backhaul, Or non-idle backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to a core network (not shown) through an idle backhaul or a non-idle backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding terminals 130-1, 130-2, 130-3, 130 130-2, 130-3, 130-4, 130-5, and 130-6, and transmits the signals received from the terminals 130-1, 130-2, 130-3, 130-4, Lt; / RTI >

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can support downlink transmission based on OFDMA, and uplink ) Transmission. Also, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may perform multiple input multiple output (MIMO) transmission (for example, MIMO, MIMO, MIMO, Coordinated Multipoint (CoMP), Carrier Aggregation, Unlicensed Band, Device to Device (D2D) ) Communication (or proximity services (ProSe)). Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 includes base stations 110-1, 110-2, 110-3, and 120-1 , 120-2, and 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 can transmit a signal to the fourth terminal 130-4 based on the SU-MIMO scheme, and the fourth terminal 130-4 can transmit a signal based on the SU-MIMO scheme And may receive a signal from the second base station 110-2. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO scheme, the fourth terminal 130-4, And the fifth terminal 130-5 may receive signals 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 terminal 130-4 based on the CoMP scheme, The terminal 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 method. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 includes terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6) and a carrier aggregation scheme. Each of the first base station 110-1, the second base station 110-2 and the third base station 110-3 coordinates D2D communication between the fourth terminal 130-4 and the fifth terminal 130-5, the fourth terminal 130-4 and the fifth terminal 130-5 may be coordinated by the coordination of the second base station 110-2 and the third base station 110-3, Can be performed.

3 is a view showing the types of vehicle-to-everything (V2X).

3, the vehicle communication V2X includes a vehicle-to-vehicle (V2V) 301, a vehicle-to-pedestrian (V2P) 302 that is a vehicle- And a vehicle-to-infrastructure (V2I) 303, which is a large-infrastructure (network) communication. For the service such as autonomous driving, the vehicle needs all functions of V2V (301), V2P (302), and V2I (303). For the autonomous driving stability, V2V (301 ) Is becoming more and more important.

4 is a view for explaining the concept of platooning of a vehicle.

4, the vehicles of the group driving group 400 may be composed of a group leader 401 and one or more group members 402, and the vehicles of the group leader 401 and the group member 402 may be grouped into vehicles A communication terminal 320 for V2V 301 communication is disposed. The group leader (401) can monitor and control the entire traveling zone by controlling the speed and the inter-vehicle distance of the traveling vehicle by integrating the front road situation monitoring at the front and the traffic information received from the network have. The group member 402 can maintain the speed and the inter-vehicle distance of the vehicle constant under the control of the group leader 401 in the backward direction in the cluster driving.

The vehicles in the cluster can perform V2V (301) communication with the vehicle through the communication terminal 320 and V2I (302) communication with the network.

Here, the contact point of the infrastructure interface for the V2I (302) communication may be an RSU (Road Side Unit), and the mobile communication base station 310 may include an RSU function. The autonomous vehicles can acquire information about the traffic situation ahead and around from the network through the V2I (302) interface, and can perform the vehicle driving based on the obtained information. Meanwhile, in the case of the cluster driving, the cluster driving group leader 401 may determine the corresponding operation of each vehicle with respect to the traffic situation information acquired through the V2I 302, and may transmit the determined operation to the group member 402. In this way, communication between the group leader 401 and the group members 402 and between the group members 402 is essential for ensuring a safe and smooth running of the community, so that the V2V (301) It is an important factor.

5 is a diagram showing a communication link of a vehicle-to-everything (V2X) communication.

Referring to FIG. 5, a communication link of a mobile communication-based vehicle network to which a group multicast and a message retransmission method are applied is illustrated. The downlink and the uplink, which are mobile communication channels, can be applied to the V2I 302 communication between the vehicle 302 and the base station 310 on which the communication terminals 321 and 322 are mounted. Further, in the present invention, the side link 304 defined in D2D, which is a direct communication of the communication terminals 321 and 322 disposed in each vehicle, can be applied for V2V 301 communication between the cluster traveling vehicles.

6 is a diagram illustrating a Proximity Service (ProSe) interface structure.

Referring to FIG. 6, a communication system for ProSe includes a communication terminal 321, a base station (eNB), a packet exchanger (Evolved Packet Core: EPC), and a ProSe function ) Can be added. In the 3rd Generation Partnership Project (3GPP) standard, a connection point between functional nodes configured for a mobile communication service is referred to as a reference point, and a Uu interface and an S1 interface are reference points defined for existing mobile communication services. Here, PC3, PC4, and PC5 (305) interfaces can be added for the ProSe service. The ProSe function (ProSe Function) can transmit Security parameters, Group IDs, Group IP multicast address, and radio resource parameters to the communication terminals 321 and 322. When having the direct communication (D2D) function between the communication terminals 321 and 322, these communication terminals 321 and 322 can be called a device. In the present invention, the reference point for the side link for direct communication between the communication terminals 321 and 322 can be defined as the PC5 interface 305. [

7 is a diagram illustrating a format of a data packet address and a group communication method of a near-service PC 5 interface.

Referring to FIG. 7, there is shown a structure of a data packet 500 applied at the PC 5 (305) interface of the D2D side link, and shows a format and a communication method of an address header of a MAC layer data packet. V 501 and R 502 are for future scalability with version and reserved bits and the source 503 (Source) portion may be the ID of the ProSe sender. Also, the destination 504 (Destination) may be the group ID for the recipient.

There is only one ProSe communication terminal UE on the transmission side, and one-to-many broadcast transmission can be performed for the group by designating the receiving side group ID. At this time, if there is one member belonging to the group ID, one-to-one communication can be performed. In the case of broadcast and multicast in mobile communication, an error packet retransmission technique such as HARQ is not applied. The ProSe PC5 interface does not support the HARQ feedback and retransmission functions S20 and S30 and the same data packet is repeatedly transmitted to the receiving devices 520 and 530 by the transmitting device 510 A half-speed transmission) can be applied. Such broadcast and multicast schemes are focused on improving resource efficiency to share radio resources, even if the communication reliability is reduced due to the omission of retransmission.

However, if conventional broadcast or multicast approach is applied to autonomous vehicle driving, which requires very high stability, such as crowd driving, there may be problems in driving safety. Accordingly, the present invention proposes a method and apparatus for inter-vehicle multicast and message retransmission that can apply a multicast scheme to V2V communication and retransmit an error message.

8 is a diagram illustrating a V2V group multicast method for cluster travel.

Referring to FIG. 8, the vehicles in the cluster driving group 600 may include a group leader 601 for controlling the cluster driving and a plurality of group members 602. A communication terminal (device) for V2V communication may be disposed in the group leader 601 and the group member 602. [ The group leader 601 of the cluster driving group 600 and the plurality of group members 602 can transmit and receive data through the group multicast 603. [ Here, when the V2V communication network is formed, the vehicle positioned at the head of the cluster driving group 600 becomes the group leader 601, and the vehicles positioned at the rear end become the group member 602. [ At this time, the group leader 601 may transmit an indication to the plurality of group members 602 that the leader 601 is a leader. The plurality of group members 602 that have received the instruction information indicating the leader can know which vehicle is the group leader in the group driving group 600. [

The group leader 601 configures the same traffic situation information and cluster run control signal into a group multicast packet 605 and simultaneously transmits a group multicast packet 605 through a group multicast 603 method to a plurality Lt; / RTI > Further, each of the plurality of group members 602 transmits a group multicast packet 605 including the running information of the subject vehicle to the group leader 601 and the other group member 602 through the group multicast 603 method .

Looking at the address format of the group multicast packet 605, V and R are for future scalability with version and reserved bits, and the Source portion may be the ID of the ProSe sender. Also, the destination may be the group ID for the recipient. That is, the communication terminal (e.g., the transmitting device) of the group leader 601 as the sender specifies the specific communication terminal (UE) ID (e.g., group leader ID) For example, the receiving device) may specify a group ID that is shared by that group.

Each of the communication terminals (for example, receiving devices) of the plurality of group members 602 that have received the group multicast packet from the communication terminal (for example, the transmitting device) of the group leader 601 is a sender of the multicast packet (Group leader 601) to feedback (604) a multicast reception result (ACK or NACK) at a ratio of 1: 1, respectively. At this time, the logical transmission address of the feedback 604 that the communication terminal (e.g., the receiving device) disposed in the group member 602 transmits to the communication terminal (for example, the transmitting device) disposed in the group reader 601, May be the group member ID of each member 602 (e.g., UE ID). The received ID can be the group leader ID that is the sender of the multicast packet. Address information is preset between the group leader 601 and the group member 602. The group leader 601 and the group member 602 send and receive address information using an abbreviated arbitrary representation instead of the address information. can do.

8, an example in which a communication terminal (for example, a transmitting device) of the group leader 601 transmits a multicast data packet to a communication terminal (for example, receiving devices) of a plurality of group members 602 have. However, the present invention is not limited to this, and each communication terminal (e.g., receiving device) of a plurality of group members 602 may send a multicast data packet to a communication terminal (e.g., a transmitting device) To a communication terminal (for example, a receiving device) of the base station 602. In addition, the group leader 601 and the group member 602 in the cluster driving group 600 can be changed so that the functions of the sender and the receiver of each communication terminal disposed in each vehicle in the cluster driving group 600 can be changed.

Figure 9 is a diagram illustrating a V2V group multicast and feedback method for cluster travel. The cluster driving group may be composed of one group leader 510 and N group members. In FIG. 9, one group leader 510 and two group members 520 and 530 are shown as cities Respectively.

Referring to FIG. 9, the sender group leader 510 may transmit the same message (msg-1) to the group members 520 and 503 in a multicast manner (S110).

Each of the group members 520 and 530 receiving the multicast message (msg-1) from the group leader 510 transmits a reception result of the multicast message (msg-1) to the group leader 510 (S120). At this time, each of the group members 520 and 530 may transmit an ACK when the multicast message (msg-1) is successfully received, and may transmit a NACK if the multicast message (msg-1) is unsuccessful.

The group leader 510 receiving the feedback message from each of the group members 520 and 530 confirms the feedback result and performs retransmission of the message msg-1 when a transmission error of the message msg-1 occurs (S130).

At this time, when receiving the NACK from the plurality of group members 520 and 530, the group leader 510 may retransmit the message (msg-1) to the plurality of group members 520 and 530 in a multicast manner. Meanwhile, when receiving a NACK from one group member, the group leader 510 can retransmit the message (msg-1) to the corresponding group member in a unicast manner.

Each of the group members 520 and 530 receiving the retransmitted message msg-1 may transmit a feedback message to the group leader 510 regarding the reception result of the retransmitted message msg-1 (S140) . In step S140, the first group member 520 transmits a NACK to the group leader 510, and the second group member 530 transmits an ACK to the group leader 510 as an example.

The group leader 510 receives the feedback message from the plurality of group members 520 and 530 and transmits a message msg (1) to the first group member 520 that has received the error of transmission of the message msg- -1) may be retransmitted (S150). At this time, the group leader 510 may transmit the message (msg-1) to the first group member 520 in a unicast manner, and the group leader 510 may transmit the message (msg- (Msg-1) to the second group member 530 that has received the ACK message.

Then, the first group member 520 receiving the re-transmitted message msg-1 can transmit a feedback message to the group leader 510 about the reception result of the message msg-1 in step S160.

As described above, the message re-transmission between the group leader 510 and the group members 520 and 530 and the feedback message between the group leader 510 and the group members 520 and 530 are performed until all messages (msg- Lt; / RTI > can be performed.

The group leader 510 can retransmit the message (msg-1) in a multicast manner when the number of group members requesting retransmission of the message is more than a predetermined number (for example, three). Then, the group leader 510 sends a message (msg-1) to each group member in a unicast manner when the failed group member of the message msg-1 is one or a small number (for example, less than 3 group members) 1) can be retransmitted. In the unicast method, the sender ID of the packet of the feedback message becomes the receiver ID of the packet to be retransmitted again. Then, the communication terminal arranged in the vehicle can set the maximum number of retransmissions to the system parameter in order to prevent the retransmission of the message (msg-1) from being infinitely repeated.

10 is a diagram showing a method of transmitting and feedbacking a plurality of messages in a multicast manner. In FIG. 10, the cluster driving group is composed of one group leader 710 and three group members 720, 730, and 740, for example.

Referring to FIG. 10, a very large amount of information can be transmitted / received in V2V during a cluster travel, and the group leader 710 transmits a plurality of different messages (msg-1, msg-2, msg-3, 730) can be transmitted to the plurality of group members 720, 730, 740 in a multicast manner (S210).

Each of the plurality of group members 720, 730 and 740 receiving a plurality of different messages (msg-1, msg-2, msg-3) from the group leader 710 includes a plurality of messages msg- the first feedback message for the reception result of the first message (msg-1) among the first message (msg-2, msg-3) to the group leader 710 (S220).

Each of the plurality of group members 720, 730 and 740 then transmits a second feedback message for the reception result of the second message (msg-2) among the plurality of messages (msg-1, msg-2, msg-3) To the group leader 710 (S230).

Next, each of the plurality of group members 720, 730, and 740 transmits a third feedback message about the reception result of the third message (msg-3) among the plurality of messages (msg-1, msg-2, msg-3) To the group leader 710 (S240).

Next, the group leader 710 receiving the first to third feedback messages from each of the plurality of group members 720, 730, and 740 may perform retransmission of the error message.

At this time, the group leader 710 does not transmit each error message to each group member. The group leader 710 can transmit a plurality of messages (msg-1, msg-2, msg-3) to the group member that transmitted the NACK by applying an index coding scheme. Specifically, the group leader 710 converts the plurality of messages (msg-1, msg-2, and msg-3) into one index code message by applying an index coding scheme. Then, the index code message can be transmitted to the group member that transmitted the NACK (S250). In this manner, when index coding is applied to retransmissions of error messages, the number of retransmission messages can be reduced and radio resource use efficiency can be increased.

11 is a diagram illustrating an example of an index encoding method upon retransmission of a message according to a feedback result.

11, the feedback results of the three group members 720, 730, and 740 for a plurality of messages (msg-1, msg-2, and msg-3) . The first group member 720 may feed back a NACK for the first message (msg-1) and an ACK for the second and third messages (msg-2, msg-3). The second group member 730 may feed back the NACK for the second message (msg-2) and feedback the ACK for the first and third messages (msg-1, msg-3). The third group member 740 may feed back a NACK to the third message (msg-3) and feed back an ACK for the first and second messages (msg-1, msg-2).

In this manner, when there is one message that each of the three group members 720, 730, and 740 can not normally receive, the group leader 710 transmits the first message (msg-1), the second message ) And the third message (msg-3). However, in order to increase the efficiency of the radio resource due to the retransmission of the message, the message can be retransmitted in the index coding manner.

The group leader 710 transforms a plurality of messages (msg-1, msg-2, msg-3) into one index code message by applying an index coding scheme, and three group members 720, 730 , 740). ≪ / RTI >

If the sender and each receiver know what information (e.g., side information 802) they have, they can encode (compress) the message to be retransmitted using this information (side information 802). Here, the side information 802 is a message indicating that the transmission succeeded and the group members 720, 730, and 740, based on the plurality of feedback messages received from the group members 720, 730, and 740 to the group leader 710, And includes information about a message to be retransmitted to each of them.

For example, the side information 802 of the plurality of group members 720, 730, and 740 can be known by looking at the feedback message received from the communication terminal (e.g., device) of the group leader 710. That is, the first group member (device-1) normally receives the second and third messages {msg-2, msg-3}, and the second group member 1 and msg-3}, and the third group member (device-3) normally receives the first and second messages {msg-1, msg-2} have. This side information 802 can be mathematically represented in a small form 803 and represented as a side information graph 804.

In the small form 803 (1 | 2,3), the communication terminal (device-1) of the first group member 720 normally receives the second and third messages (msg-2, msg-3) 2 and the third message (msg-2, msg-3). In the small form 803 (2 | 1,3), the communication terminal (device-2) of the second group member 730 receives the first and third messages (msg-1 and mag-3) , It means that the contents of the first and third messages (msg-1, mag-3) are known. In the small form 803 (3 | 1,2), the communication terminal (device-3) of the third group member 740 normally receives the first and second messages (msg-1 and mag-2) , It means that the contents of the first and second messages (msg-1, mag-2) are known.

In the side information graph 804, the nodes (①, ②, ③) refer to the communication terminals (devices) of the first to third group members 720, 730, 740, have. That is, it is indicated that the communication terminal (device-1) of the first group member knows the second and third messages (msg-2, msg-3).

In the information graph 804, when the arrows between the nodes (①, ②, ③) are closed, the communication terminal (device) of the group reader 710 combines the two messages into an XOR (logical exclusive arithmetic operation) And transmitted to the index code message 805. The group member receiving the index code message 805 can decode the desired information by performing an XOR (logical exclusive arithmetic operation) on the index code message 805 and already known information (side information).

11, the nodes of the three group members 720, 730 and 740 are both closed, so that the communication terminal (device) of the group leader 710 transmits the first to third messages msg-1 , msg-2, msg-3) into one index code message 805 and transmit it. In this manner, the first to third messages (msg-1, msg-2, and msg-3) are converted into one index code message 805 and transmitted, , msg-3), respectively, by 2/3 of the radio resources.

12 is a diagram illustrating another example of an index encoding method in retransmitting a message according to a feedback result.

12, the communication terminal of the group leader 710 transmits the first to third messages msg-1, msg-2, and msg-3 to the first to third group members 720, 730, 740, and the result of the feedback on the small form 901 and the side information graph 902 is shown.

Referring to the small form 901 and the side information graph 902, the first group member 720 normally receives the second message (msg-2) and knows the contents of the second message (msg-2). The second group member 730 normally receives the first and third messages msg-1 and msg-3 and knows the contents of the first and third messages msg-1 and msg-3. Then, the third group member 740 normally receives the first message (msg-1) and knows the contents of the first message (msg-1).

The nodes of the three group members 720, 730 and 740 are closed between the nodes ① and ② so that the communication terminal of the group leader 710 transmits the first and second messages msg-1 and msg -2) to generate one index code message 903, and transmits the generated one index code message 903 as a plurality of group members in a multicast manner. Since the communication terminal (device) of the group leader 710 has to separately transmit the third message, it is possible to retransmit the third message to a plurality of group members without applying index coding. Thus, if the first and second messages (msg-1 and msg-2) are converted into one index code message 903 and the third message (msg-3) is separately retransmitted, The radio resources can be reduced by 1/3 compared with the case where the third messages (msg-1, msg-2, and msg-3) are transmitted.

The methods according to the present invention can be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the computer readable medium may be those specially designed and constructed for the present invention or may be available to those skilled in the computer software.

Examples of computer readable media include hardware devices that are specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

301: Vehicle-to-Vehicle (V2V) 302: Vehicle-to-Pedestrian (V2P)
303: Vehicle-to-infrastructure (V2I) 302: Communication terminal
400: Cluster driving group 401: Group leader
402: Group Member

Claims (20)

A method of driving a communication terminal arranged in a group leader among a group driving group composed of a group leader and a plurality of group members,
Transmitting a message including information for cluster driving to the plurality of group members in a multicast manner;
Receiving a feedback message for the message from each of the plurality of group members; And
And retransmitting the message to one or more group members that requested retransmission of the message based on the feedback message.
A method of driving a communication terminal. The method according to claim 1,
In the step of retransmitting the message,
And retransmitting the message in a multicast manner when the number of group members requesting retransmission of the message is more than a predetermined number,
A method of driving a communication terminal. The method according to claim 1,
In the step of retransmitting the message,
Wherein when the number of group members requesting retransmission of the message is less than a predetermined number, the message is retransmitted in a unicast manner,
A method of driving a communication terminal. The method according to claim 1,
Prior to transmitting the message,
Further comprising the step of, when forming the inter-vehicle communication network, transmitting, to the plurality of group members, the instruction information indicating that the vehicle is the group leader, the vehicle positioned at the head of the group driving group.
A method of driving a communication terminal. The method according to claim 1,
In the step of transmitting the message,
And transmitting the message to the plurality of group members using a PC5 interface supporting a close service,
A method of driving a communication terminal. The method of claim 5,
In the step of transmitting the message,
Transmitting the message including the ID of the group leader to the message,
A method of driving a communication terminal. The method of claim 5,
In the step of transmitting the message,
Transmitting the message including the group ID of the group member to the message,
A method of driving a communication terminal. A method of driving a communication terminal arranged in a group leader among a group driving group composed of a group leader and a plurality of group members,
Transmitting a plurality of messages including information for a cluster run to the plurality of group members in a multicast manner;
Receiving a plurality of feedback messages for each of the plurality of messages from each of the plurality of group members;
Generating an index code message by index-coding the plurality of messages for which retransmission is requested based on a plurality of feedback messages; And
And transmitting the index code message to the plurality of group members.
A method of driving a communication terminal. The method of claim 8,
In the step of generating the index code message,
Generates side information including information on a transmission succeeded based on the plurality of feedback messages,
And generating the index code message based on the side information.
A method of driving a communication terminal. The method of claim 8,
In the step of transmitting the index code message,
And transmitting the index code message in a multicast manner when the number of group members requesting retransmission of the plurality of messages is greater than or equal to a predetermined number.
A method of driving a communication terminal. The method of claim 8,
In the step of retransmitting the message,
And transmitting the index code message in a unicast manner when the number of group members requesting retransmission of the plurality of messages is less than a predetermined number.
A method of driving a communication terminal. The method of claim 8,
In the step of transmitting the plurality of messages,
And transmitting the plurality of messages to the plurality of group members using a PC5 interface supporting a close service,
A method of driving a communication terminal. The method of claim 8,
Prior to transmitting the plurality of messages,
Further comprising the step of, when forming the inter-vehicle communication network, transmitting, to the plurality of group members, the instruction information indicating that the vehicle is the group leader, the vehicle positioned at the head of the group driving group.
A method of driving a communication terminal. A driving method of a communication terminal arranged in a first group member among a group driving group composed of a group leader and a plurality of group members,
Receiving a message from the group leader in a multicast manner, the message including information for driving the cluster;
Transmitting a feedback message including information on the success or failure of reception of the message to the group leader; And
And receiving a retransmitted message from the group leader based on the feedback message.
A method of driving a communication terminal. 15. The method of claim 14,
In receiving the retransmitted message,
Receiving a retransmitted message in a multicast manner when the number of group members requesting retransmission of the message is greater than or equal to a predetermined number;
A method of driving a communication terminal. 15. The method of claim 14,
In receiving the retransmitted message,
Receiving the retransmitted message in a unicast manner when the number of group members requesting retransmission of the message is less than a predetermined number;
A method of driving a communication terminal. 15. The method of claim 14,
In transmitting the feedback message,
And transmitting the feedback message to the group leader using a PC5 interface supporting a close service,
A method of driving a communication terminal. 15. The method of claim 14,
In transmitting the feedback message,
Transmitting the feedback message including an ID of a communication terminal of the group member and an ID of the group leader;
A method of driving a communication terminal. 15. The method of claim 14,
Receiving from the group leader a plurality of messages including information for the cluster run in a multicast manner;
Transmitting a plurality of feedback messages for each of the plurality of messages to the group leader; And
And receiving a retransmitted message from the group leader based on the plurality of feedback messages,
Wherein the retransmitted message is an index code message generated by index-coded the plurality of messages,
A method of driving a communication terminal. 15. The method of claim 14,
Prior to the step of receiving the plurality of messages,
Further comprising the step of receiving, when forming the inter-vehicle communication network, the instruction information indicating that the vehicle is the group leader, from the vehicle positioned at the head of the community driving group.
A method of driving a communication terminal.

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