KR102328492B1 - Multi-hoped based v2x data transmit and receipt device - Google Patents

Abstract

The present invention relates to a multi-hop based vehicle-to-everything (V2X) data transmission device and a multi-hop based V2X data receiving device and, more specifically, to a multi-hop based V2X data transmission device, which generates a data packet with hopping count information included in a header and mediates the data packets generated by a V2X communication standard until the remaining number of hopping becomes zero, and a multi-hop based V2X data receiving device. According to the present invention, the multi-hop based V2X data transmission device comprises a generation unit generating a packet including hopping information and a transmitter transmitting the packet in a V2X communication standard according to the hopping information. The packet includes a first header, a second header, and a third header. The first header includes information on the number of remaining hopping counts subtracted according to transmission of the packet, the second header includes information on the maximum number of hops of the packet, and the third header includes identification information of the packet. The packet is included in at least one of a basic safety message (BSM) message generated by a vehicle and a radio technical commission for maritime services (RTCM) message generated by a roadside device.

Description

V2X data transmission device and reception device of multi-hop method {MULTI-HOPED BASED V2X DATA TRANSMIT AND RECEIPT DEVICE}

The present invention relates to a V2X data transmission apparatus and a reception apparatus of a multi-hop method, and more particularly, generates a data packet including hopping number information in a header, and the remaining number of hopping is the data packet generated by the V2X communication standard. It relates to a multi-hop method V2X data transmission device and reception device that can mediate until 0.

Recently, a vehicle is becoming the result of a complex industrial technology fusion of electrical, electronic, and communication technologies in the center of mechanical engineering, and in this respect, a vehicle is also called a smart car. Smart cars connect drivers, vehicles, and transportation infrastructure to provide various user-customized mobility services as well as traditional vehicle technologies such as traffic safety/complexity resolution. Such connectivity may be implemented using V2X (Vehicle to Everything) communication technology.

WAVE (Wireless Access for Vehicular Environment) technology, which is being promoted as a V2X communication standard technology, consists of IEEE 802.11p and IEEE 1609.x standards. WAVE technology is a short-distance wireless communication standard technology that supports a communication distance of 1km and supports a communication speed of at least 1Mbps to a maximum of 54Mbps. This technology is a technology for communication between vehicles moving at high speed, and requires transmission of individual broadcast messages in a very short wireless connection time. It also supports multiple channels (7 channels) and variable transmit power.

The vehicle safety service is based on the WAVE (Wireless Access in Vehicular Access) standard, which is a short-range wireless communication standard between vehicles. This is done by broadcasting them periodically.

However, there arises a problem that the transmission distance is limited due to the nature of vehicle-to-vehicle communication in a broadcast method based on the WAVE standard. Therefore, the need to extend the physical WAVE data transmission distance is emerging.

Republic of Korea Patent Publication No. 10-1563001 (2015. 10. 23. Announcement) Republic of Korea Patent Publication No. 10-2083878 (2020. 03. 03. Announcement) Republic of Korea Patent Publication No. 10-2073739 (2020. 02. 05. Announcement)

An object of the present invention for solving the above-described problems is to provide a multi-hop method V2X data transmission apparatus and a reception apparatus.

Another object of the present invention is to use a vehicle equipped with a V2X module as a router, and to transmit data to a device of a final destination by hopping as many as a predetermined number of hops to transmit V2X data in a multi-hop method. A device and a receiving device are provided.

Another object of the present invention is to utilize a vehicle equipped with a V2X module as a router and hop as much as a predetermined number of hops to further extend the data transmission distance on the WAVE standard. It is to provide a V2X data transmission device and a reception device.

In order to achieve the above object, a multi-hop V2X data transmission apparatus according to an embodiment of the present invention transmits the packet in a V2X communication standard according to a generator generating a packet containing hopping information and the hopping information. In the V2X data transmission apparatus including a transmitter, the packet includes a first header, a second header and a third header, wherein the first header includes information on the number of remaining hopping counts subtracted according to the transmission of the packet. The second header includes information on the maximum number of hops of the packet, the third header includes identification information of the packet, and the packet includes a BSM (Basic Safety Message) message generated by a vehicle. and RTCM (Radio Technical Commission for Maritime Services) messages generated by the roadside device.

The first header further includes lifetime information for storing the remaining time of the packet, the second header further includes transmission method information indicating a transmission method of the packet, and the third header includes: It characterized in that it further includes initial source information indicating information of the device that generated the packet.

When the transmission method of the packet included in the second header is unicast, the third header may further include final destination information of the packet.

In order to achieve the above object, a multi-hop V2X data receiving apparatus according to an embodiment of the present invention is a BSM (Basic Safety Message) message generated in the vehicle and RTCM (Radio Technical Commission for Maritime Services) generated in the roadside device ) included in at least one of the messages, the receiver for receiving a packet containing hopping information; a processing unit for processing the packet; and a transmitter for transmitting the packet in a V2X communication standard according to the hopping information, wherein the packet includes a first header, a second header and a third header, the first header comprising: , information on the number of remaining hopping counts subtracted according to the transmission of the packet, the second header includes information on the maximum number of hops of the packet, and the third header includes identification information of the packet.

The first header further includes lifetime information for storing the remaining time of the packet, the second header further includes transmission method information indicating a transmission method of the packet, and the third header includes: and initial source information indicating information of a device that generated the packet, wherein the processing unit extracts extension information from the BSM message or the RTCM message, and when the remaining hopping number information is not 0, the remaining number of hops is subtracted, and the transmitter is characterized in that it transmits the BSM message or the RTCM message toward another V2X data receiving device.

According to the multi-hop method V2X data transmission device and reception device of the present invention, it is possible to transmit data to mediate until it reaches the final destination vehicle by using a vehicle equipped with a V2X module as a router, so that excessive traffic to the network can be prevented from occurring.

According to the present invention, the multi-hop method V2X data transmission device and reception device, it is possible to transmit data in a unicast or topologically-scoped broadcast transmission method instead of a broadcast method, so that The transmission distance can be further extended.

1 is a block diagram showing an apparatus for transmitting and receiving V2X data of a multi-hop method according to the present invention.
2 is a flowchart illustrating a multi-hop V2X data transmission method according to the present invention.
3 is a flowchart illustrating a multi-hop V2X data reception method according to the present invention.
4 is a flowchart illustrating a first embodiment of a method for receiving V2X data in a multi-hop method according to the present invention.
5 is a flowchart illustrating a second embodiment of a method for receiving V2X data in a multi-hop method according to the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to components in each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated in different drawings.

In the description of the embodiment of the present invention, if it is determined that a detailed description of a related known configuration or function interferes with the understanding of the embodiment of the present invention, the detailed description thereof will be omitted.

In addition, in describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and the essence, order, or order of the components are not limited by the terms.

As used herein, the singular also includes the plural, unless the phrase specifically states otherwise. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components in addition to the stated components.

A data packet according to the present invention is generated (transmitting end) and processed (receiving end) in the application layer (layer). Therefore, when generating a data packet, productivity can be improved because it can be created without worrying about the communication of the packet or the matter to be modified later.

The V2X communication transceiver apparatus according to the present invention includes a V2X module, is capable of transmitting and receiving data based on wireless communication using the V2X communication standard, and may be a known one. The V2X communication standard described in this specification may be a well-known one, and in one embodiment, it may be a Wireless Access for Vehicular Environment (WAVE) consisting of IEEE 802.11p and IEEE 1609.x standards, but is not limited thereto.

V2X communication means communication between vehicles and everything on the road, such as vehicles and vehicles (V2V), vehicles and pedestrians (V2P), and traffic facilities (V2I) such as base stations, vehicles, and traffic lights.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block diagram illustrating a multi-hop V2X data transmission apparatus 100 and a reception apparatus 200 according to the present invention.

First, the transmitting apparatus 100 according to the present invention, with reference to FIG. 1 , a generating unit 110 that generates a packet containing hopping information and a transmitting unit that transmits a packet through wireless communication using the V2X communication standard according to the hopping information ( 120).

The generating unit 110 according to the present invention generates a packet containing hopping information. The packet generated by the generator 110 largely includes a header and a payload, and the header includes a first header, a second header, and a third header. The payload includes the remaining data of the packet except for the header. In general, in the header of a packet, an address or order to which data is to be delivered is recorded.

The header of the packet according to the present invention includes hopping information. In this specification, hopping may refer to a state in which data is transmitted and received between a node and a node. The V2X data transmission device 100 and the reception device 200 according to the present invention may be included in a vehicle to transmit/receive data between vehicles. In this case, each vehicle may act as a router. Accordingly, it is possible to transmit data received from one vehicle to another. In this case, data transfer from one vehicle to another may be referred to as hopping. In the present specification, hopping information may be information necessary, generated or modified during hopping, and in brief, information on the source of data generation, information on routers receiving and retransmitting data in the middle, destination information containing information on the final destination, or Information on the number of remaining hopping counts may be included.

The generating unit 110 according to the present invention generates a packet containing hopping information, and includes the generated packet in a Basic Safety Message (BSM) message or a Radio Technical Commission for Maritime Services (RTCM) message. The BSM message is called a safety message and is a message containing basic information of the vehicle related to the location, speed, acceleration, brake operation, etc. of the vehicle to provide a vehicle safety service. BSM messages are generated in the vehicle and forwarded to other vehicles. RTCM message is GPS correction data used by RTK module, which encapsulates RTCM differential correction for GPS and other radio navigation signals as defined in RTCM special committee (Radio Services Committee) DSRC media and then defined final It can be reconfigured in the expected format. It contains information to increase the absolute and relative accuracy estimates generated by direct use in various positioning systems based on the RTCM standard. RTCM information is information that corrects the location information of each object so that the exact location can be known. The transmitting apparatus 100 according to the present invention may further include a BSM generating module or an RTCM generating module for generating a BSM or RTCM message. RTCM information is encoded and generated in RTCM, an international standard message protocol, in the roadside device (RSU, base station) and delivered to each vehicle through WAVE communication. When the RTCM message is out of the transmission range of the roadside device, it becomes difficult to transmit it smoothly. The packet according to the present invention includes hopping information, so that each vehicle serves as a router to deliver the BSM message or RTCM message to the final destination, so that the vehicle can smoothly arrive at the final destination. For example, in the case of RTCM provided by a roadside device, the data providing area is generally 500 meters in radius of the roadside device, but when RTCM is transmitted using hopping according to the present invention, the data providing area can be expanded several times. . The generator 110 may include a packet containing hopping information in a BSM message or an RTCM message (hereinafter, 'message'). Each header of the BSM message or RTCM message may further include an extended information header. Extension information added to each message is recorded in the extension information header. The extension information header may include hopping information according to the present invention, and may further include additional information.

The packet generated by the generator 110 according to the present invention includes a first header, a second header, and a third header.

The first header includes information on the number of remaining hopping counts subtracted according to packet transmission according to the V2X module. The remaining number of hopping information, which will be described later, is subtracted by, for example, each time the value included in the maximum number of hopping information is transmitted or mediated by the V2X transmission device 100, and when it becomes 0, the packet is transmitted It is information (or value) that disappears from the network.

The first header includes next header information in which the existence of the next header is recorded, version information to identify the version of the corresponding protocol, and the time that the packet can endure until it reaches its final destination, that is, the remaining time information of the packet. may include The time (value) included in the remaining time information can prevent old messages from remaining in the network.

The second header includes information on the maximum number of hops of the packet. The maximum number of hops can be set when generating the first packet. The maximum number of hops is not changed by intermediaries or routers.

The second header further includes transmission method information indicating a transmission method of the packet. The transmission method information may be a unicast or topologically-scoped broadcast method. In unicast, a specific destination is determined, and messages are delivered by hopping until a message is relayed to the destination. The unicast method can be used when relaying BSM messages. The topology curly method is a method of relaying messages until the remaining number of hopping is exhausted. The topologically method can be used in the mediation of RTCM messages. The unicast method and the topologically method will be described later with reference to FIGS. 4 and 5 .

The second header further includes Daum header information in which the existence of the next header is recorded, class information in which whether the device has the corresponding message when there is no neighbor around the device receiving the mediated message, and length information of the packet excluding the header. may include

The third header includes identification information of the packet. The identification information is information used when detecting whether or not there are duplicate packets. The identification information may be a serial number of a packet. The third header further includes initial source information indicating information on the device that generated the packet in addition to the identification information. The initial source information may be a serial number of the device that generated the packet. The identification information and the initial source information are used to determine whether a corresponding packet is the same as a previously received packet when the receiving apparatus receives a packet, which will be described later.

The third header further includes final destination information of the packet when the transmission method of the packet included in the second header is unicast. In the unicast method, a message is delivered to a specific destination, and information on the specific destination is included in the third header.

The transmitter 120 according to the present invention transmits a packet generated by the generator 110 and included in the message to another V2X receiver 200 . That is, the transmitter 120 transmits the message to the other receiver 200 . When transmitting a message including a packet, the transmitter 120 may transmit it to other nearby vehicles or things equipped with the V2X receiving device 200 .

The receiving device 200 according to the present invention is included in at least one of a BSM (Basic Safety Message) message generated in a vehicle and a Radio Technical Commission for Maritime Services (RTCM) message generated in a roadside device, and includes hopping information. It includes a receiver 210 for receiving a packet, a processor 220 for processing the packet, and a transmitter 230 for retransmitting the packet in the V2X communication standard according to the hopping information.

The receiver 210 according to the present invention receives a message transmitted by the transmitter 120 of the transmitter 100 . The message received by the receiver 210 is processed by the processor 220 . The message received by the receiver 210 includes a packet containing hopping information. The packet includes a first header, a second header, and a third header, and information included in each header is as described above.

The processing unit 220 according to the present invention determines whether the extension information is included in the first received message. As described above, the extended information may be included in the header of the message, and when additional information is recorded in the message, it is recorded in the extended information. The extended information may include hopping information according to the present invention, or additional information other than the hopping information may be recorded. Accordingly, when the header of the message includes extended information, the processing unit 220 processes (decrypts) the received message with the possibility that there may be hopping information according to the present invention.

The processing unit 220 according to the present invention processes the header of the received message to extract hopping information of the packet. As described above, the hopping information includes information included in the first header, the second header, and the third header. First, the processing unit 220 checks the remaining time information of the first header and, when the remaining time is 0, deletes the corresponding packet. When the remaining time information is not 0, the processing unit 220 checks the transmission method information of the second header.

If the transmission method information recorded in the second header is a unicast method, it is checked whether the corresponding packet is a packet that is duplicated with a previously received packet (or a message that is duplicated with a previously received message). In this case, the identification information of the third header and the initial source information are used. It is determined whether the packet is a duplicate by comparing whether the identification information and the original source information recorded in the corresponding packet are the same as the identification information and the original source information recorded in the previously received packet. In the case of a duplicate packet, the message including the corresponding packet is deleted, and in the case of a non-overlapping packet, the final destination information recorded in the third header of the free packet is extracted. When the final destination information and the received information of the receiving device match, the entire message is processed and stored in the database of the receiving device 200 . If the final destination information and the received information of the receiving device do not match, the value of the remaining hopping count information recorded in the first header of the corresponding packet is subtracted by one. When the deducted remaining hopping count information is 0, the corresponding packet and message are deleted. When the subtracted residual hopping count information is not 0, the corresponding packet and message are transmitted to the other V2X receiving device 200 by the transmitter 230, which will be described later. That is, if the remaining number of hopping information is not 0, the remaining number of hopping is subtracted and the message is retransmitted. As described above, when the message transmission method is a unicast method, the corresponding message is preferably a BSM message.

If the transmission method information recorded in the second header is the topological method, it is checked whether the corresponding packet is a packet that is duplicated with a previously received packet (or a message that is duplicated with a previously received message). In this case, the identification information of the third header and the initial source information are used. It is determined whether the packet is a duplicate by comparing whether the identification information and the original source information recorded in the corresponding packet are the same as the identification information and the original source information recorded in the previously received packet. In the case of a duplicate packet, a message including the corresponding packet is deleted, and in the case of a non-duplicated packet, the entire corresponding message is processed and stored in the database of the receiving device 200 . In the case of the topological method, unlike the unicast method with a specific final destination, if the number of remaining hopping is not 0 even after processing the message, the received message is retransmitted to another V2X receiving device 200 . Therefore, after processing the message, the remaining hopping count information (value) recorded in the first header is subtracted by 1, and when the remaining hopping count information becomes 0, the message is deleted. If the remaining hopping count information is not 0, another V2X It retransmits to the receiving device 200 . That is, if the remaining number of hopping information is not 0, the remaining number of hopping is subtracted and the message is retransmitted.

The transmitter 230 according to the present invention transmits a packet generated by the generator 110 and included in the message to another V2X receiver 200 . That is, the transmitter 230 transmits the message to the other receiver 200 . When transmitting a message including a packet, the transmitter 230 may transmit it to other nearby vehicles or things equipped with the V2X receiving device 200 . The transmitter 230 subtracts the above-described remaining number of hopping every time a packet is transmitted.

The transmitter 230 according to the present invention retransmits the received message to another V2X receiving device 200 when the subtracted residual hopping count information is not 0. That is, the reception device 200 serves as the transmission device 100 . As shown in FIG. 1 , the receiving device 200 after the transmitting device 100 of the original source performs the role of the transmitting device 100 serving as a router until the information on the number of remaining hops becomes 0. . The transmitter 230 transmits a packet and a message including the packet in the V2X communication standard according to hopping information such as the number of remaining hopping times. That is, the packet and the message including the packet may be transmitted between the V2X data transmission devices 100 until the remaining number of hopping becomes 0 to arrive at the final destination.

The multi-hop V2X data transmission device 100 and the multi-hop V2X data reception device 200 according to the present invention may be integrated and operated as one device, which may be a multi-hop V2X communication device. . Also, the V2X data transmission apparatus 100 may be included in a vehicle, a base station including a roadside device, and the like, respectively.

2 is a flowchart illustrating a multi-hop V2X data transmission method according to the present invention.

In the multi-hop method of transmitting V2X data according to the present invention, referring to FIG. 2 , generating a packet containing hopping information (S101) and transmitting the packet in a V2X communication standard according to the hopping information (S103) ) is included.

Step S101 is a step of generating a packet containing hopping information. The packet includes a first header, a second header and a third header as described above. In each header, information included in the hopping information is recorded and stored. The information included in the hopping information includes information on the number of remaining hopping times, information on the maximum number of hopping times, packet identification information, lifetime information, transmission method information, initial source information, and final destination information, as described above. The description of the hopping information is the same as described above, and therefore a detailed description thereof will be omitted.

The packet generated in step S101 is included in at least one of a BSM (Basic Safety Message) message generated by the vehicle and a Radio Technical Commission for Maritime Services (RTCM) message generated by the roadside device. The BSM message or the RTCM message (hereinafter, 'message') further includes extended information. Extended information may be included in the header of each message. In the extended information, information added to each message is recorded. The extended information may include hopping information according to the present invention, and other additional information may be further included.

Step S103 is a step of transmitting a packet and a message including the packet to the other V2X receiving device 200 according to the hopping information. In step S103 , the packet generated by the generating unit 110 and included in the message is transmitted to the other V2X receiving device 200 . That is, the transmitter 120 transmits the message to the other receiver 200 . When transmitting a message including a packet, the transmitter 120 may transmit it to other nearby vehicles or things equipped with the V2X receiving device 200 .

3 is a flowchart illustrating a multi-hop V2X data reception method according to the present invention.

The V2X data reception method of the multi-hop method according to the present invention, with reference to FIG. 3, at least any one of a BSM (Basic Safety Message) message generated in a vehicle and a Radio Technical Commission for Maritime Services (RTCM) message generated in a roadside device It is included in one, and includes a step of receiving a packet containing hopping information (S201), a step of processing the packet (S203), and a step of transmitting the message in a V2X communication standard according to the hopping information (S205).

Step S201 is a step in which the receiving device 200 receives a message. The message received in step S201 may be the message transmitted in step S103. The message may be a BSM message or an RTCM message. The message includes a packet containing hopping information. A description of a case in which the message does not include a packet containing hopping information will be described later in step S203. The description of the packet containing the hopping information included in the message is the same as described above.

Step S203 is a step of processing a packet containing hopping information in the received message. The embodiment of step S203 may vary depending on the transmission method of the corresponding packet, and each embodiment will be described later with reference to FIGS. 4 and 5 . However, in step S203, when processing the packet containing the hopping information, the existence of extension information is determined from each message, and if the extension information exists, the extension information is processed and extracted, and the hopping information is Existence is checked, and if hopping information exists, the remaining number of hopping counts is subtracted if the remaining hopping count information is not 0. If the remaining hopping count information is 0, the message can be deleted without processing.

Step S205 is a step in which the message from which the number of remaining hopping is subtracted from step S203 is retransmitted toward another V2X data receiving apparatus 200 according to hopping information.

Steps S203 and S205 have different embodiments depending on a transmission method of a packet or message among the information included in the hopping information. Hereinafter, each embodiment will be described with reference to FIGS. 4 and 5 .

4 is a flowchart illustrating a first embodiment of a method for receiving V2X data in a multi-hop method according to the present invention.

A first embodiment of the multi-hop method V2X data reception method, with reference to FIG. 4 , the steps of receiving a message (S201), processing a packet in the received message (S203), and retransmitting the received message (S205).

Step S201 is a step in which the receiving device 200 receives a message, as described above.

Step S203 of the first embodiment is a step of processing the received message, a step of determining whether extension information is present in the header of the message (S20311), a step of determining whether a packet transmission method is unicast (S20312), receiving Determining whether one message is a duplicate message (S20313), determining whether the final destination of the received message is the corresponding receiving device 200 (S20314), and processing (decrypting) the corresponding message to the database of the receiving device 200 and storing (S20315).

In step S20311, it is first determined whether the received message includes extended information. As described above, the extended information may be included in the header of the message, and when additional information is recorded in the message, it is recorded in the extended information. The extended information may include hopping information according to the present invention, or additional information other than the hopping information may be recorded. Therefore, when the header of the message includes extension information, the received message is processed (decrypted) with the possibility that there may be hopping information according to the present invention. However, if the header of the message does not include extension information, there is no hopping information, so the reception method is terminated.

Step S20312 is a step of processing the received message, extracting a packet from the processed message, and determining whether the transmission method information recorded in the second header of the extracted packet is a unicast method. For example, in the case of the unicast method, a specific value (eg, 1) may be recorded in a specific position of the corresponding packet.

In step S20313, if the transmission method of the corresponding packet is determined to be unicast in step S20312, it is checked whether the corresponding packet is a packet duplicated with a previously received packet (or a message duplicated with a previously received message). In this case, the identification information of the third header and the initial source information are used. It is determined whether the packet is a duplicate by comparing whether the identification information and the original source information recorded in the corresponding packet are the same as the identification information and the original source information recorded in the previously received packet. In the case of a duplicate packet, the message including the corresponding packet is deleted, and in the case of a non-overlapping packet, the final destination information recorded in the third header of the free packet is extracted.

Step S20314 is a step of determining whether the extracted final destination information matches information of the receiving device 200 that has received the corresponding message. If the final destination information does not match the information of the receiving device 200, the corresponding message is retransmitted to the other receiving device 200 (S205), if the final destination information matches the information of the receiving device 200, step S20315 The message is processed in

Step S20315 is a step of processing the entire message and storing it in the database of the receiving device 200 .

If the final destination information does not match the information of the receiving device 200 in step S20314, the corresponding message is retransmitted to the other receiving device 200 in step S205.

Step S205 of the first embodiment is a step of retransmitting the received message to another receiving apparatus 200 .

Step S205 of the first embodiment includes the steps of subtracting the remaining number of hopping of the corresponding message (S20511), determining whether the remaining number of hopping is 0 (S20512), and if the remaining number of hopping is not 0, the message is sent to another receiving device ( 200) and retransmitting (S20513).

Step S20511 is a step of subtracting the remaining number of hopping of the corresponding message. In step S20511, the value of the remaining number of hopping information recorded in the first header of the corresponding packet is subtracted by one.

Step S20512 is a step of determining whether the number of remaining hopping counts is 0. In step S20512, when the subtracted residual hopping count information is 0, the corresponding packet and message are deleted.

Step S20513 is a step in which the corresponding packet and message are transmitted to another V2X receiving device 200 when the subtracted residual hopping count information is not 0. That is, in step S20513, if the remaining number of hopping information is not 0, the remaining number of hopping is subtracted and the message is retransmitted. As described above, when the message transmission method is a unicast method, the corresponding message is preferably a BSM message.

5 is a flowchart illustrating a second embodiment of a method for receiving V2X data in a multi-hop method according to the present invention.

The second embodiment of the multi-hop method V2X data reception method, referring to FIG. 5 , the steps of receiving a message (S201), processing a packet in the received message (S203), and retransmitting the received message (S205).

Step S201 is the same as in the first embodiment.

Step S203 of the second embodiment is a step of processing the received message, a step of determining whether extension information is present in the header of the message (S20321), a step of determining whether a packet transmission method is topologically (S20322), and receiving It includes a step of determining whether one message is a duplicate message (S20323) and a step of processing (decrypting) the corresponding message and storing the message in a database of the receiving device 200 (S20324).

Step S20321 is the same as step S20311.

Step S20322 is a step of processing the received message, extracting a packet from the processed message, and determining whether the transmission method information recorded in the second header of the extracted packet is a topological method. For example, in the case of the topological method, a specific value (eg, 2) may be recorded at a specific location of the corresponding packet.

In step S20323, if the transmission method of the corresponding packet is determined to be topologically in step S20322, it is checked whether the corresponding packet is a packet that is duplicated with a previously received packet (or a message that is duplicated with a previously received message). In this case, the identification information of the third header and the initial source information are used, which is the same as in step S20313.

Step S20324 is a step of processing the entire message and storing it in the database of the receiving device 200 .

After step S20324, the received corresponding message is retransmitted to another receiving device 200 (S205).

Step S205 of the second embodiment includes subtracting the number of remaining hopping counts of the received message (S20521), determining whether the subtracted number of remaining hopping counts of the received message is 0 (S20522), and when the remaining number of hopping is not 0 Retransmitting the corresponding message to the other receiving device 200 (S20523).

Step S20521 is the same as step S20511.

Step S20522 is the same as step S20512.

Step S20523 is the same as step S20513. As described above, when the transmission method of the message is a topological method, it is preferable that the corresponding message is an RTCM message.

On the other hand, V2X communication is a service that can reduce traffic accidents and traffic jams by providing vehicle safety services in a wireless environment, detecting risks that may occur while driving and notifying the driver in advance.

V2X communication, as described above, generally uses WAVE (Wireless Access in Vehicular Access) technology. WAVE technology is a short-distance wireless communication standard technology that supports a communication distance of 1km and supports a communication speed of at least 1Mbps to a maximum of 54Mbps. WAVE technology is a technology for communication between vehicles moving at high speed and requires transmission of individual broadcast messages in a very short wireless connection time. In addition, it supports multiple channels (7 channels) and variable transmission power, and direct vehicle-to-vehicle communication is possible through multiple overlaps in the communication area and fast initialization.

The vehicle safety service is based on the WAVE standard, a short-range wireless communication standard between vehicles, by periodically broadcasting a safety message (Basic Safety Message, BSM) to surrounding vehicles through vehicle-to-vehicle (V2V) communication. is done However, due to the nature of vehicle-to-vehicle communication in a broadcast manner, excessive traffic is generated in the network in a densely vehicular area such as an intersection or highway in the city, which sharply increases the failure probability and delay of safety message transmission.

Therefore, in the present invention, in order to solve the communication congestion problem that occurs in the process of performing the vehicle safety service, the relationship between the channel busy ratio and the number of vehicles is approximated mathematically, and the total network congestion is estimated using this. And based on this, we propose a transmission power control algorithm that controls the data transmission power of the V2X module.

The transmitters 120 and 230 according to the present invention measure the congestion level by observing the channel load in order to measure the congestion level of the network or channel. In the present invention, the concept of Channel Busy Ratio (CBR) is introduced to observe the channel load. The channel load tends to increase as there are more nodes that communicate in a short distance, ie, surrounding vehicles. Since the channel load tends to increase as there are more nodes that communicate in a short distance, that is, the number of surrounding vehicles, it is meaningful to analyze the relationship between CBR and the number of surrounding vehicles. In the present invention, the relationship between CBR and the number of surrounding vehicles is approximated mathematically, and the total network congestion is estimated using this. In the present invention, since problems such as the Hidden Node Problem and the Exposed Node Problem occur between nodes within a two-hop distance in a wireless ad-hoc communication environment, the overall network congestion is defined as a two-hop network congestion.

CBR represents the percentage of channel utilization within the safety message transmission period. As shown in Equation 1, CBR can be defined as a value obtained by dividing packet transmission/reception times (tT, tR) by the safety message transmission period (T). In the present invention, CBR is used as an indicator indicating how congested the channel is.

(수식 1)

(Formula 1)

The number of remote vehicles (RVs) is the number of vehicles within a one-hop communication distance of the host vehicle (HV) and means the number of vehicles within a distance that can communicate with the HV. In the present invention, in order to organize the relationship between CBR and the number of surrounding vehicles, a virtual time slot is introduced by applying the virtual time frame (VTF) concept of the S. Bai thesis. The virtual time slot size (Ss) is the time it takes to transmit or receive one safety message, and the number of virtual time slots (Sn) is the maximum number of times a safety message can be transmitted/received during the safety message transmission period (T). . Therefore, the size of the virtual time slot is the size of the safety message (M) divided by the communication speed (C), and the number of virtual time slots is the safety message transmission period divided by the size of the virtual time slot. If this is expressed as a formula, it is as (Equations 2, 3).

(수식 2)

(Equation 2)

(수식 3)

(Equation 3)

For example, if the size of the safety message is assumed to be 400 bytes and the safety message broadcast period is fixed to 100 ms, the size of one virtual time slot is about 1.08 ms based on the 3Mbps communication speed and the number of virtual time slots is about 93.

Since CBR is the ratio of channel utilization within the safety message transmission period, it is obtained by dividing the product of the virtual time slot size, the number of virtual time slots, and the probability (p) of using one virtual time slot by the safety message transmission period (T) (Equation 4) can be expressed as

(수식 4)

(Equation 4)

Here, the probability that one virtual time slot is not used is expressed as (Equation 5) if the number of RVs within a one-hop distance is N. Therefore, CBR can be approximated by (Equation 6).

(수식 5)

(Equation 5)

(수식 6)

(Equation 6)

Reference Figure 1 is a table showing the communication distance per data transmission power of the V2X module according to the present invention, Reference Figure 2 is a pseudo code of the data transmission power control algorithm of the V2X module according to the present invention.

(참고도 1)

(Reference 1)

(참고도 2)

(Reference Figure 2)

The present invention proposes an algorithm for adjusting the data transmission power of the V2X module provided by the transmitting device 100 or the receiving device 200 based on the congestion level. The transmitters 120 and 230 further include a congestion maintenance unit (not shown) that calculates the congestion level (CBR2hop) of the network or channel, and increases or decreases the TX Power based on this to keep the channel load constant. It is assumed that the communication distance per transmission power is known as shown in FIG. 1 . Reference Figure 2 is a pseudo code of the proposed algorithm.

In order to estimate the overall network congestion level (CBR2hop), the congestion maintenance unit uses the CBR (CBR1hop) of one hop distance and TX power information received from all surrounding RVs. If this is written as a formula, it is as (Equation 7). Here, CBR1hop is the value actually measured at the HV, and Rd is the vehicle density around the RV calculated using the TX Power information received from the surrounding RVs. OA is the area where the communication radius of RV and HV overlaps.

(수식 7)

(Equation 7)

(수식 8)

(Equation 8)

(수식 9)

(Equation 9)

Rd is the density of surrounding vehicles, which is the number of vehicles in the RV divided by the two-hop communication range (TX_Area2hop). This is possible by assuming that it is always maintained at 0.5 by the algorithm proposed by CBR2hop. When calculating Rd of all RVs in HV as shown in (Equation 7), the complexity of the algorithm for calculating CBR2hop becomes O(2n) considering the overlapping communication range between RVs. Therefore, in the present invention, CBR2hop was estimated by sampling the most distant 8 RVs from the east, west, south, north, northeast, northwest, southeast, and southwest of the HV.

Reference Figure 3 is a table showing a simulation environment for verifying the algorithm proposed in the present invention.

(참고도 3)

(Reference 3)

A simulation for verifying the algorithm proposed in the present invention was performed for 30 seconds in a two-lane 3km highway environment as shown in FIG. 3 . Nodes were performed in a static environment where they do not move. In addition, the simulation was divided into a case in which the data transmission power control algorithm according to the present invention is not applied (TPC Off) and a case in which it is applied (TPC On). In a scenario where the transmit power control algorithm is not applied, the vehicle transmit power is maintained as it is 15.0 dBm, and when the algorithm is applied, the initial transmit power is 15.0 dBm.

In order to evaluate the performance of the proposed two-hop congestion estimation-based safety message transmission power control algorithm, two evaluations are made. Whether the congestion level of two hops has been properly estimated and whether the congestion has been alleviated in the transmission of safety messages by adjusting the transmit power. For this, the performance indicators of Ideal CBR2hop, Estimated CBR2hop, CBR1hop and PER are used.

Ideal CBR2hop is a calculation of 2-hop CBR by directly sharing CBR measured in simulation by all nodes, Estimated CBR2hop is a calculation of 2-hop CBR using shared TX power through the algorithm proposed in the present invention, and CBR1hop is a unit The higher the channel is used for the time, the higher the channel utilization rate.

Reference Fig. 4 is a table showing parameter values for performance evaluation of the data transmission power control algorithm according to the present invention, Reference Fig. 5 is a graph comparing values calculated by averaging all the vehicles in the simulation, and Reference Fig. 6 is a time table This is a graph comparing Ideal CBR2hop and Estimated CBR2hop in the Free scenario.

(참고도 4)

(Reference 4)

(참고도 5)

(Reference 5)

(참고도 6)

(Reference Figure 6)

In the present invention, the performance of the proposed context-aware-based transmit power control algorithm is verified through simulation. The simulation was performed using Qualnet, a network simulator, and the parameter values are as shown in reference FIG. 4 .

Ideal CBR2hop and Estimated CBR2hop were compared to verify whether the overall network congestion estimation was correct. Reference Figure 5 is a comparison by averaging the values calculated by all vehicles in the simulation, and it can be seen that in the Medium or Free scenario except for the Heavy scenario, it is estimated similarly. The reason why similar estimates are not made in the Heavy scenario is that the proposed algorithm assumes that CBR2hop is maintained at 0.5 distributedly in each vehicle. However, in the heavy scenario, this assumption cannot be satisfied, so the Estimated CBR2hop also has a lot of errors. Reference Figure 6 shows that the Ideal CBR2hop and Estimated CBR2hop are compared in the free scenario over time, and it can be seen that it is estimated almost perfectly.

Reference Figure 7 is a graph comparing Packet Error Rate (PER) when the algorithm according to the present invention is applied and not applied, and Reference Figure 8 is one-hop when the algorithm according to the present invention is applied and not applied. Channel Busy Ratio (CBR1hop) This is a graph comparing V2X modules according to the distribution density.

(참고도 7)

(Reference Figure 7)

(참고도 8)

(Reference figure 8)

In order to evaluate the performance of the proposed algorithm, the cases in which the algorithm is applied and the cases in which the algorithm is not applied are simulated and compared according to the distribution density of Packet Error Rate (PER) and 1-Hop Channel Busy Ratio (CBR1hop) vehicles. Reference Figure 7 and Reference Figure 8 are the results. According to Figure 7, when the proposed algorithm is applied (TPC ON), the Packet Error Rate shows an error rate of 0.1 or less in all scenarios, and when the proposed algorithm is not applied (TPC OFF), the Packet Error Rate is 0.1 in the Heavy scenario. shows that it exceeds This shows that the proposed algorithm effectively reduces the Packet Error Rate and improves the reliability of V2V communication in a congestion situation.

Referring to FIG. 8 , it can be seen that when the algorithm proposed in the Heavy and Medium scenarios is applied, the CBR1hop is lower than in the case where the algorithm is not applied, and the CBR1hop is higher in the Free scenario. Through this, the proposed algorithm reduces channel utilization by reducing transmit power in scenarios with high congestion (Heavy, Medium), but increases communication reliability by reducing PER and increases transmission power in scenarios with low congestion (Free). It shows that communication efficiency is increased by increasing channel utilization.

In conclusion, it is possible to estimate the total network congestion by using CBR (Channel Busy Ratio), and based on this, we propose a transmission power control algorithm that controls transmission power. The proposed algorithm estimates the overall network congestion level using the TX power field in the header of the WSMP message and controls the transmission power to keep the overall network congestion constant based on this. As a result of simulation through Qualnet, the estimation of overall network congestion was accurately performed, and the transmission power control algorithm lowered the packet error rate and showed that the reliability of vehicle-to-vehicle communication was improved.

In the present specification, the generating unit 110 , the transmitting unit 120 , the receiving unit 210 , the processing unit 220 , and the transmitting unit 230 may be processors that execute consecutive execution processes stored in a memory. Alternatively, it may operate as software modules driven and controlled by a processor. Furthermore, the processor may be a hardware device.

For reference, the multi-hop method of receiving V2X data according to an embodiment of the present invention may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded in the medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software. Examples of computer-readable media include hard disks, magnetic media such as floppy disks and magnetic tapes, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floppy disks, and ROM, RAM, A hardware device specifically configured to store and execute program instructions, such as flash memory, may be included. Examples of program instructions include not only machine codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In this specification, a "part" includes a unit realized by hardware, a unit realized by software, and a unit realized using both. In addition, one unit may be implemented using two or more hardware, and two or more units may be implemented by one hardware.

The protection scope of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is added once again that the protection scope of the present invention cannot be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

100: sending device
110: generator
120: transmitter
200: receiving device
210: receiver
220: processing unit
230: transmitter

Claims (5)

a generator for generating a packet containing hopping information and including the packet in a message; And In the V2X data transmission device comprising a transmission unit for transmitting the message to the V2X data reception device in the V2X communication standard according to the hopping information,
The message is a BSM (Basic Safety Message) message generated in the vehicle or an RTCM (Radio Technical Commission for Maritime Services) message generated in the roadside device,
The message includes an extension information header including the packet,
The packet includes a header in which the hopping information is recorded,
The header includes a first header, a second header and a third header,
The first header includes information on the number of remaining hopping counts subtracted according to the transmission of the packet and lifetime information in which the remaining time of the packet is stored,
The second header includes information on the maximum number of hops of the packet and transmission method information indicating a transmission method of the packet,
The third header includes identification information of the packet, initial source information indicating information on a device that generated the packet, and final destination information of the packet,
The V2X data receiving device,
a receiver for receiving the message; a processing unit for processing the message; and a transmitter for transmitting the message in a V2X communication standard according to the hopping information,
When the processing unit processes the message,
It is determined whether the extension information header is present in the message,
If the extended information header does not exist in the message as a result of determining whether the extended information header exists, the message is not processed any more;
When the extended information header is present in the message as a result of determining whether the extended information header exists, the extended information header is extracted from the message, the packet is extracted from the extracted extended information header, and the extracted packet extracting the header from, extracting the transmission method information from a second header of the extracted header, and determining the transmission method of the packet based on the extracted transmission method information,
As a result of determining the transmission method, when the packet transmission method is a unicast method, the final destination information is extracted from the extracted third header of the header, and the final destination information of the received message is determined based on the extracted final destination information. Determining whether the destination is the receiving device,
As a result of determining whether the final destination is the receiving device, when the final destination of the received message is the receiving device, the multi-hop method V2X data transmission apparatus, characterized in that the received message is stored in a database. delete delete delete delete

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