WO2019164019A1

WO2019164019A1 - V2x communication device and geo-networking transmission method

Info

Publication number: WO2019164019A1
Application number: PCT/KR2018/002065
Authority: WO
Inventors: 백서영; 고우석
Original assignee: 엘지전자(주)
Priority date: 2018-02-20
Filing date: 2018-02-20
Publication date: 2019-08-29

Abstract

Disclosed is a geo-networking transmission method of a V2X communication device. A geo-networking transmission method according to an embodiment of the present invention comprises the steps of: receiving a geo-networking packet from a sender V2X transmission device; checking whether the received geo-networking packet is a packet pre-stored in a buffer; when the received geo-networking packet is not a pre-stored packet, determining whether to progress forwarding of the geo-networking packet; when it is determined to progress the forwarding, storing the geo-networking packet in the buffer, configuring a timeout duration, and starting a timer for re-transmission of the packet; and when the timer expires, transmitting the geo-networking packet.

Description

V2X Communication Device and Geonetworking Transmission Method

The present invention relates to an apparatus for V2X communication and a method for transmitting a geonetworking thereof, and more particularly, to a method for setting a timer and a communication range in a method for geonetworking transmission of a contention-based algorithm.

Recently, vehicles have become the result of complex industrial technologies in which electrical, electronic, and communication technologies converge at the center of mechanical engineering. In this respect, vehicles are also called smart cars. Smart cars connect drivers, vehicles, and traffic infrastructure to provide a variety of customized mobility services, as well as traditional vehicle technologies such as traffic safety and complexity. This connectivity can be implemented using Vehicle to Everything (V2X) communication technology.

Various services can be provided through V2X communication. In addition, a plurality of frequency bands have been used to provide various services. Even in this environment, reliable delivery and provision of safety services is a very important issue due to the characteristics of vehicle communication.

In V2X communication, a geonetworking transmission method using hopping may be used to transfer data out of the transmission range. In geonetworking transmissions, packet forwarding algorithms may be used for data hopping and destination delivery. Especially in the V2X communication environment where the communication environment is dynamically changed, the packet forwarding algorithm must consider efficiency and reliability.

In order to solve the above technical problem, a geo-networking transmission method of the V2X communication device and the V2X communication device is disclosed.

According to an aspect of the present invention, there is provided a method for transmitting a geonetworking by a V2X communication device, the method comprising: receiving a geonetworking packet from a sender V2X communication device; Checking whether the received geonetworking packet is a packet previously stored in a buffer; If the received geonetworking packet is not a previously stored packet, storing the geonetworking packet in a buffer, setting a timeout duration, and starting a timer for retransmitting the packet; And transmitting the geonetworking packet when the timer expires, wherein the timeout period indicates a time period during which the packet is buffered in the buffer.

In the geonetworking transmission method of a V2X communication device according to an embodiment of the present invention, the maximum communication distance of the sender V2X communication device includes a plurality of sectors, and each of the plurality of sectors has a constant timeout period.

In the geonetworking transmission method of a V2X communication device according to an embodiment of the present invention, the timeout period of the plurality of sectors is determined based on a distance between the sender V2X device and the V2X device that transmitted the received packet. The larger the distance, the smaller the timeout period.

In the geonetworking transmission method of a V2X communication device according to an embodiment of the present invention, the geonetworking packet includes communication range information of a V2X communication device transmitting the geonetworking packet.

In the geonetworking transmission method of a V2X communication device according to an embodiment of the present invention, the value of the communication range information is a difference value between the location of the surrounding V2X communication devices and the location of the V2X communication device communicating during the first time interval. Is determined by the maximum value.

In the geonetworking transmission method of a V2X communication device according to an embodiment of the present invention, the peripheral V2X communication device is a V2X communication device in which a response packet or a forwarding packet to the packet transmitted by the V2X communication device is received.

In the geonetworking transmission method of a V2X communication device according to an embodiment of the present invention, the value of the communication range information is a difference between the position of the surrounding V2X communication devices and the location of the V2X communication device communicating during the first time interval. The maximum of the values is used during the second time interval.

V2X communication apparatus according to an embodiment of the present invention, the memory for storing data; A communication unit for transmitting and receiving a radio signal including a geonetworking packet; And a processor for controlling the memory and the communication unit, the processor receiving a geonetworking packet from a sender V2X communication device, checking whether the received geonetworking packet is a packet previously stored in a buffer, If the networking packet is not a pre-stored packet, the geonetworking packet is stored in a buffer, a timeout duration is set, a timer for retransmitting the packet is started, and the geonetworking packet is terminated when the timer expires. Wherein the timeout period represents a time period during which the packet is buffered in the buffer.

According to the present invention, by setting the CBF buffer waiting time in consideration of the CBF buffer as well as the buffer of the access layer, it is possible to improve the latency of the CBF operation in terms of the system. By dividing the communicable area into certain sectors, since the CBF buffer times out at the same time for routers in the sector, unnecessary latency in forwarding can be reduced.

According to the present invention, by varying the communication range, the latency of the CBF algorithm can be improved. By applying a dynamic change in communication range due to interference in a multi-channel environment to the CBF algorithm, unnecessary latency can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this application for further understanding of the invention, illustrate embodiments of the invention, together with a detailed description that illustrates the principles of the invention.

1 shows a protocol structure of an ITS system according to an embodiment of the present invention.

2 illustrates a packet structure of a network / transport layer according to an embodiment of the present invention.

3 is a header structure of a geonetworking packet according to an embodiment of the present invention, and shows a structure of a basic header and a common header.

FIG. 4 illustrates a method for geonetworking of a GUC type according to an embodiment of the present invention and a GUC packet header configuration according thereto.

FIG. 5 illustrates a topologically scoped broadcast (TSB) type geonetworking method and a TSB packet header configuration according thereto according to another embodiment of the present invention.

FIG. 6 illustrates a SHB (Single Hop Broadcast) type geonetworking method and an SHB packet header configuration according to another embodiment of the present invention.

FIG. 7 illustrates a Geographically-Scope Broadcast (GBC) / Geographically-Scoped Anycast (GAC) type geonetworking method and a BC / GAC packet header configuration according to another embodiment of the present invention.

8 illustrates beacon type geonetworking and a beacon packet header configuration according to another embodiment of the present invention.

9 illustrates the configuration of a location service (LS) request packet header and an LS response packet header according to an embodiment of the present invention.

10 shows position vector information according to an embodiment of the present invention.

11 illustrates a packet forwarding method of a greedy forwarding algorithm according to an embodiment of the present invention.

12 is a conceptual diagram of a non-region contention-based algorithm according to an embodiment of the present invention.

13 illustrates contention-based transmission according to an embodiment of the present invention.

14 illustrates a packet delivery method of an area contention-based algorithm according to an embodiment of the present invention.

15 shows an ITS-G5 architecture according to an embodiment of the invention.

16 illustrates an example of timeout time according to distance when using the CBF algorithm according to an embodiment of the present invention.

17 illustrates an example of a timeout time considering a buffer when using a CBF algorithm according to an embodiment of the present invention.

18 illustrates an example of a timeout time in consideration of a buffer when using the CBF algorithm according to an embodiment of the present invention.

19 illustrates an example of different communication ranges of routers in a multi-channel environment, in accordance with an embodiment of the invention.

20 shows a GUC packet structure according to an embodiment of the present invention.

21 shows a GAC / GBC packet structure according to an embodiment of the present invention.

22 (a) shows an LS request packet structure according to an embodiment of the present invention, and FIG. 22 (b) shows an LS response packet structure according to an embodiment of the present invention.

23 illustrates a communication range measuring method according to an embodiment of the present invention.

24 illustrates a communication range measuring method according to another embodiment of the present invention.

25 shows a configuration of a V2X communication device according to an embodiment of the present invention.

Preferred embodiments of the present invention will be described in detail, examples of which are illustrated in the accompanying drawings. DETAILED DESCRIPTION The following detailed description with reference to the accompanying drawings is intended to explain preferred embodiments of the invention rather than to show only embodiments that may be implemented in accordance with embodiments of the invention. The following detailed description includes details in order to provide a thorough understanding of the present invention, but the present invention does not require all of these details. The present invention is not to be used separately the embodiments described below. Multiple or all embodiments may be used together, and specific embodiments may be used in combination.

Most of the terms used in the present invention are selected from general ones widely used in the art, but some terms are arbitrarily selected by the applicant, and their meanings are described in detail in the following description as necessary. Therefore, the present invention should be understood based on the intended meaning of the term and not the simple name or meaning of the term.

The present invention relates to a V2X communication device, and the V2X communication device may be included in an intelligent transport system (ITS) system to perform all or some functions of the ITS system. The V2X communication device can communicate with vehicles and vehicles, vehicles and infrastructure, vehicles and bicycles, and mobile devices. The V2X communication device may be abbreviated as a V2X device. According to an embodiment, the V2X device may correspond to an onboard unit (OBU) of the vehicle or may be included in the OBU. OBU may be referred to as On Board Equipment (OBE). The V2X communication device may correspond to a road side unit (RSU) of the infrastructure or may be included in the RSU. The RSU may be referred to as Road Side Equipment (RSE). Alternatively, the V2X communication device may correspond to the ITS station (ITS-S) or may be included in the ITS station. Any OBU, RSU, mobile equipment, etc. that perform V2X communication may all be referred to as ITS stations or V2X communication devices. In geonetworking communication, a V2X communication device may be referred to as a router.

V2X communication devices can communicate based on various communication protocols. The V2X communication device may implement the WAVE (Wireless Access In Vehicular Environments) protocol of IEEE 1609.1-4. In this case, the V2X communication device may be referred to as a WAVE device or a WAVE communication device.

The V2X communication device may transmit a Cooperative Awareness Message (CAM) or a Decentralized Environmental Notification Message (DENM). The CAM is distributed in the ITS network and provides information about at least one of the presence, location, communication state, or running state of the ITS station. DENM provides information about detected events. The DENM can provide information about any driving situation or event detected by the ITS station. For example, the DENM can provide information about situations such as vehicle accidents, vehicle problems, traffic conditions, and the like, such as emergency electronic brakes.

Application layer: The application layer may implement and support various use cases. For example, the application may provide road safety, efficient traffic information, and other application information.

Facilityities layer: The facility layer can support the effective realization of the various uses defined in the application layer. For example, the facility layer may perform application support, information support, and session / communication support.

Access layer: The access layer may transmit a message / data received from a higher layer through a physical channel. For example, the access layer may include an IEEE 802.11 and / or 802.11p standard based communication technology, an ITS-G5 wireless communication technology based on the physical transmission technology of the IEEE 802.11 and / or 802.11p standard, and satellite / broadband wireless mobile communication. Data communication can be performed / supported based on 2G / 3G / 4G (LTE) / 5G wireless cellular communication technology, broadband terrestrial digital broadcasting technology such as DVB-T / T2 / ATSC, GPS technology, and IEEE 1609 WAVE technology.

Networking & Transport Layer: The network / transport layer can form a network for vehicle communication between homogeneous / heterogeneous networks by using various transport protocols and network protocols.

The transport layer is a connection layer between services provided by upper layers (session layer, presentation layer, application layer) and lower layers (network layer, data link layer, physical layer). The transport layer can manage the transmission data to arrive exactly at the destination. At the transmitting side, the transport layer processes the data into packets of appropriate size for efficient data transmission, and at the receiving side, the transport layer can perform processing to restore the received packets to the original file. As an embodiment, protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Basic Transport Protocol (BTP) may be used as the transport protocol.

The network layer can manage logical addresses and determine the delivery path of packets. The network layer may receive the packet generated at the transport layer and add a logical address of the destination to the network layer header. As an embodiment, the packet path may be considered unicast / broadcast between vehicles, between vehicles and fixed stations, and between fixed stations. As an embodiment, Geo-Networking, with mobility support IPv6 networking, over IPv6, and the like can be considered as a networking protocol.

The ITS architecture may further include a management layer and a security layer.

The transport layer generates a BTP packet, and the network layer may generate a geo-networking packet by encapsulating the BTP packet. Geo-networking packets may be encapsulated into LLC packets. In the embodiment of Figure 2, the data includes a message set, which may be a basic safety message.

BTP is a protocol for transmitting messages such as CAM and DENM generated by the facility layer to the lower layer. The BTP header consists of A type and B type. The type A BTP header may include a destination / destination port and a source port, which are required for transmission and reception for interactive packet transmission. The B type header may include destination port and destination port information, which is required for transmission for non-interactive packet transmission. Descriptions of the fields / information included in the header are as follows.

Destination Port: The destination port identifies the facility entity corresponding to the destination of the data (BTP-PDU) included in the BTP packet.

Source Port: A field generated in the case of a BTP-A type, indicating a port of a protocol entity of a facility layer in a source through which a corresponding packet is transmitted. This field may have a size of 16 bits.

Destination Port Info: This field is generated for the BTP-B type and may provide additional information when the destination port is the best known port. This field may have a size of 16 bits.

The geonetworking packet includes a basic header and a common header according to the protocol of the network layer, and optionally includes an extension header according to the geonetworking mode. The geonetworking header is described again below.

The LLC header is added to the geonetworking packet to generate the LLC packet. The LLC header provides the function of distinguishing IP data and geonetworking data. IP data and geonetworking data can be distinguished by the Ethertype of SNAP. As an embodiment, when IP data is transmitted, the Ethertype may be set to 0x86DD and included in the LLC header. As an embodiment, when geonetworking data is transmitted, the Ethertype may be set to 0x86DC and included in the LLC header. The receiver may check the Ethertype field of the LLC packet header and forward and process the packet to the IP data path or the geonetworking path according to the value.

FIG. 3 (a) shows the basic header of the geonetworking packet header shown in FIG. 2, and FIG. 3 (b) shows the common header of the geonetworking packet header shown in FIG.

The basic header can be 32 bits (4 bytes). The basic header may include at least one of a version field, an NH field (Next Header), an LT (LifeTime) field, and a Remaining Hop Limit (RHL) field. The fields included in the basic header are described below. The bit size constituting each field is only an embodiment and may be changed.

Version (4-bit): The version field indicates the version of the geonetworking protocol.

NH (4 bits): The NH (Next Header) field indicates the type of the next header / field. If the field value is 1, the common header is followed. If the field value is 2, the secured secure packet may be followed.

LT (8 bits): The LT (LifeTime) field indicates the maximum survival time of the packet.

RHL (8 bits): The Remaining Hop Limit (RHL) field indicates the remaining hop limit. The RHL field value may be decremented by 1 each time it is forwarded by a GeoAdhoc router. If the RHL field value is 0, the packet is no longer forwarded.

The common header can be 64 bits (8 bytes). Common headers include NH (NextHeader) field, HT (HeaderType) field, HST (Header Sub-Type) field, TC (Traffic Class) field, Flags field, PayloadLength field, PL (Maximum Hop Limit) field It may include at least one of. Description of each field is as follows.

NH (4 bits): The NH (Next Header) field indicates the type of the next header / field. A field value of 0 may indicate an undefined "ANY" type, 1 indicates a BTP-A type packet, 2 indicates a BTP-B type packet, and 3 indicates an IPv6 IP diagram.

HT (4 bits): The header type field indicates the geonetworking type. Geonetworking types include Beacon, GeoUnicast, GeoAnycast, GeoBroadcast, Topologically-Scoped Broadcast, and Location Service (LS).

HST (4-bit): The Header Subtype field indicates the detailed type along with the header type. As an embodiment, when the HT type is set to TSB, when the HST value is '0', a single hop may be indicated, and when it is '1', a multi hop may be designated.

TC (8 bits): The traffic class field may include a Store-Carry-Forward (SCF), Channel Offload, and TC ID. The SCF field indicates whether to store a packet when there is no neighbor to deliver the packet. The channel offload field indicates that a packet can be delivered to another channel in case of a multichannel operation. The TC ID field is a value assigned during packet transmission in the facility layer and may be used to set a contention window value in the physical layer.

Flag (8 bits): The flag field indicates whether the ITS device is mobile or stationary, and may be the last 1 bit as an embodiment.

PL (8 bits): The Payload Length field indicates the data length following the geonetworking header in bytes. For example, in the case of a geo-networking packet carrying a CAM, the PL field may indicate the length of the BTP header and the CAM.

MHL (8-bit): The Maximum Hop Limit (MHL) field may indicate the maximum number of hops.

The geonetworking header includes the above-described basic header, common header and extended header. The extension header is configured differently according to the geonetworking type. Hereinafter, a header configuration according to each geonetworking type will be described.

In the present specification, a V2X communication device performing geonetworking may be referred to as a router or a geoad hoc router. A V2X communication device that transmits a geonetworking packet may be referred to as a source router or a sander. A V2X communication device that receives a geonetworking packet from a source router and relays / forwards it to a sander may be referred to as a forwarding router or a forwarder. The V2X communication device or the V2X communication device in the final destination area of the geonetworking packet may be referred to as a destination or a destination router.

FIG. 4 (a) shows a method of data transmission of a Geographically-Scoped Unicast (GUC) type, and FIG. 4 (b) shows a GUC header configuration.

GUC is a method of passing data from a specific source router to a destination router. As shown in FIG. 4A, the source router S may transmit data in a GUC type to the destination router N8 via multi-hop. The source router must have information about the destination router in its location table. If there is no information about the destination router, the source router can use the "LS request and LS reply" process to find the desired destination.

In FIG. 4B, the GUC packet header includes a basic header, a common header, and an extension header. The HT field of the common header indicates a GUC, and the extended header includes an SN field, an SO PV (Source Position Vector) field, and a DE PV (Destination Position Vector) field. Description of the included fields is as follows.

Sequence Number (SN): The Sequence Number field indicates a value used for checking packet redundancy. The value of the sequence number field is incremented by one when a packet is sent from the source. The receiving router may determine whether a packet is duplicated by using a sequence number (or a sequence number and a TST value). SN is a value used for multi-hop transmission.

SO PV: Indicates the position of the source and may be in a long position vector format.

DE PV: indicates the location of the destination, and may be in a short position vector format.

FIG. 5 (a) shows a method of data transmission of a TSB (Topologically Scoped Broadcast) type, and FIG. 5 (b) shows a TSB header configuration.

TSB is a broadcast scheme that adjusts the distance that data is transmitted by the number of hops. Location based information is not used. Since only the number of hops determines whether data is delivered, the location address of the destination or local information to which the data is delivered is not used. Data can be forwarded from the source router s to all routers within n hops.

5 (a) shows a TSB data transmission of n-2. The source router broadcasts the signal by setting n = 2, and routers within the transmission range of the source router receive this signal. Since N = 2, forwarding routers N1, N2, N3 that have received data in one hop re-broadcast the received packet. Since N = 2, routers receiving a re-broadcasted signal do not re-broadcast the received packet. In this TSB transmission method, a single hop (n = 1) may be referred to as a single hop broadcast (SHB).

In FIG. 5B, the TSB packet header includes a basic header, a common header, and an extended header. The HT field of the common header indicates a TSB, and the extension header includes an SN field and an SO PV (Source Position Vector) field. Description of the included fields is as follows.

In the case of the TSB header, since the number of transmissions is limited by the number of hops, the destination address may be omitted.

FIG. 6 (a) shows a data transfer method of a single hop broadcast (SHB) type, and FIG. 5 (b) shows a structure of an SHB header.

SHB corresponds to a case where the hop number is 1 (n = 1) in the above-described TSB. SHB packets are sent only to routers within the source router transmission range. Since data can be transmitted with the least latency, SHB can be used to send safety messages such as CAM. As shown in FIG. 6 (a), the packet is transmitted only to one-hop range routers N1, N2, and N3 of the source S.

In FIG. 6B, the SHB packet header includes a basic header, a common header, and an extension header. The HT field of the common header indicates the TSB, and the extension header includes an SO PV (Source Position Vector) field. Description of the included fields is as follows.

In the case of the SHB packet, since the number of transmissions is limited by the number of hops, the destination address may be omitted. Since the multihop transmission is not performed, the SN field for redundancy check may also be omitted.

FIG. 7 (a) shows a method of transferring data of a Geographically-Scope Broadcast (GBC) / Geographically-Scoped Anycast (GAC) type, and FIG. 4 (b) shows a GBC / GAC header configuration.

GeoBroadcast / GBC is a transmission method that broadcasts a packet to all routers in a specific region, and GeoAnycast / GAC transmits a packet only to one router that first receives the packet in a specific region. Transmission method. In GBC, if the data delivered from the source router is delivered to a specific destination area, the packet is broadcast within the defined area. In the GAC, when a packet is delivered to one router in a particular destination area, the packet is no longer sent.

In FIG. 7B, the GBC / GAC header includes a basic header, a common header, and an extended header. The HT field of the common header indicates GBC or GAC, and the extended header includes an SN field, an SO PV (Source Position Vector) field, and destination region information. The destination area information includes a latitude (GeoAreaPosLatitude) field, a longitude (GeoAreaPosLongitude) field of the center of the destination area, and distance fields (Distance a, b) and an angle field for indicating a range of the area.

8 shows a header configuration of a beacon packet. The beacon packet header may include a basic header, a common header and an extension header, and the extension header may include SO PV information.

The beacon packet may be configured similarly to the SHB packet header described above. The difference is that SHB packets can be appended with a message later to be used to carry data such as CAM, and beacons are used as headers without data added. CAM or beacons using SHB may be sent periodically. By sending and receiving a CAM or beacon, a router can obtain location information of neighboring routers and use this location information to perform routing. In an embodiment, the beacon may not be transmitted if the CAM is transmitted.

9 (a) shows an LS request packet header, and FIG. 9 (b) shows an LS response packet header.

If there is no destination information in its location table, the source router may request geonetworking address information (GN_ADDR) for the destination in the vicinity. This address information request may be performed by transmitting the LS request packet LS request information LS_request. When the information requested by the source router is included in the location table of the router that receives the LS request packet, the corresponding router may transmit LS response information LS_reply. In addition, the router of the destination may transmit the LS response information with respect to the LS request information.

LS response information includes position vector information of GN_ADDR. The source router may update the location table through the LS response information. The source router can perform GUC transmission by using the geonetworking address information received in response.

In Figure 9 (a), the configuration of the LS request packet header is similar to the GUC header. In the LS request packet header, a geonetworking address request field (RequestGN_ADDR) is included instead of the destination address field of the GUC header.

In FIG. 9B, the LS response packet header configuration is the same as the GUC packet header. However, the SO PV field includes position vector information of the router, and the DE PV field includes position vector information of the router which transmitted the request.

As discussed above, the geonetworking packet header includes a position vector (PV) field associated with the location. Types of position vectors include long PV and short PV. 10 (a) shows long position vector information and FIG. 10 (b) shows short position vector information.

As shown in FIG. 10A, the long position vector information includes the following subfields.

GN_ADDR: The geonetworking address field may consist of a total of 64 bits. A geoad hoc router that performs geonetworking transmissions has one unique geonetworking address value. The geonetworking address field may include the following subfields.

a) M: A field for distinguishing between a geonetworking address or a manually set value. For example, if the value is '1', the value may be set manually.

b) ST: The ITS-S type field indicates the type of the ITS station. ITS-S type is pedestrian, cyclist, moped, motorcycle, passenger car, bus, light truck, heavy truck, trailer, special vehicle It may include trams, RSUs.

c) MID: As V2X device identification information, a MAC address may be used.

TST (TimeSTamp): The type stamp field indicates the time at which the ITS station obtained the latitude / longitude value from the geoad hoc router. As a millisecond unit, a Universal Time Coordinated (UTC) value may be used.

Latitude (LAT), Long (Longitude): The latitude field and the longitude field indicate latitude and longitude values of the geoad hoc router.

Position Accuracy Indicator (PAI): Indicates the accuracy of the geoad hoc router location.

S (Speed): Indicates the speed of the geoad hoc router.

H (Heading): Indicates the direction of the geoad hoc router.

As shown in FIG. 10B, the short position vector information includes a GN_ADDR field, a TST field, a LAT field, and a long field. Description of each field is as described above for the long position vector.

Various packet forwarding methods may be used for geonetworking transmission. For example, greedy forwarding algorithm, contention-based forwarding algorithm, non-area contention-based forwarding algorithm, area contention-based forwarding algorithm, area advanced forwarding Algorithms and the like can be used. Forwarding algorithms are used to effectively deliver and distribute data to desired areas. In the case of the greedy forwarding algorithm, the source router determines the forwarding router, and in the case of the contention-based forwarding algorithm, the receiving router determines whether to forward the packet using contention. In the following, a V2X device / router processing a geonetworking algorithm may be referred to as an ego router.

In geonetworking, each V2X device acts as a router and can use an ad hoc method to determine the routing of packets. Each V2X device transmits the vehicle's location information, speed information, and head direction information to the surroundings, and using this information, each V2X device can determine the routing of packets. The periodically received information is stored in a LocT (location table) of the network & transport layer, and the stored information can time out after a certain time. LocT may be stored in a location table entry (LocTE).

For geonetworking protocol operation, each ad hoc router must have information about another ad hoc router. Information about the peripheral router may be received through the SHB or beacon packet. The router may update LocT when new information is received. The transmission period of the SHB or beacon packet may change depending on the channel state. The location / location table may be referred to as LocT.

Information about the neighbor router is stored in the LocT, and the stored information may include at least one of the following information. Information stored in the LocT may be deleted from the list when the lifetime set to the soft-state expires.

GN_ADDR: Geo-network address of the ITS station

Type of ITS-S: Type of ITS station, for example indicating whether it is a vehicle or an RSU.

Version: Geo-networking version used for the ITS station

Position vector PV: Position vector information includes geographic position information, velocity information, heading information, time stamp information indicating the position measurement time, position accuracy indicator (PAI) information indicating the accuracy of the provided position. It may include at least one of.

Flag LS_PENDING: A flag indicating when a location service request is in progress because the current LocT does not have an address for the destination.

FLAG IS_NEIGHBOUR (IS_NEIGHBOUR flag): Flag indicating if there is a geoad hoc router that can communicate within the communication range.

DPL: Duplicate Packet List for Source GN_ADDR

Typestamp: the timestamp of the last packet indicating the end of the duplication

Packet Data Rate (PDR): The packet rate that Geoad Hoc Routers must maintain

The greedy forwarding algorithm decides to which of the neighbor routers Sander knows which packet to forward. Sander's LocT (Location Table) can be updated to the latest value through periodically distributed SHB or beacon packets. The sander selects the router closest to the destination from LocT so that packets can be delivered to the destination with the least hops.

In Fig. 11, routers 1 to 5 exist within the communication range of the source router. The source router transmits the packet by setting the MAC address of router 2 closest to the destination as the link layer destination address.

The greedy-forwarding algorithm uses no buffering and can quickly forward packets to their destinations as long as the connection between routers is not broken. However, if the connection between routers is lost, i.e., if the router to transmit the next hop is out of the transmission range or disappears, the packet cannot be delivered and reliability may be deteriorated.

The following describes the packet delivery method of the contention-based forwarding algorithm.

The contention-based forwarding algorithm, unlike the greedy forwarding algorithm described above, determines whether the receiver forwards a packet by contention / content. Any receiver that receives a packet broadcast by Sander can be a potential forwarder. The receiver sets the timer according to the distance, and the receiver which the timer expires forwards the packet first. If no packet is received from other receivers until the timer expires, the receiver forwards the packet when the timer expires. If a packet is received before the timer expires, the receiver times out its timer and does not forward the packet.

The contention-based forwarding algorithm, unlike the greedy forwarding algorithm, does not need to know the location of neighboring neighbor routers. Even if the SHB packet or the beacon packet is not periodically transmitted, that is, even without a location table, packet forwarding may be performed. Since there are a plurality of candidate forwarders, reliability may be increased and packet forwarding to the destination may be increased. However, the buffering time required for packet delivery can increase latency. In addition, the use of additional buffers is required.

A contention-based algorithm is an algorithm in which a receiver determines the next sender through contention / contention, instead of the sander determining the next hop. Sander broadcasts a GN (GeoNetworking) packet, and all routers around it that receive the GN packet store it in the CBF buffer and start a timer. The timer is set as in Equation 1 below.

T0_CBF: timeout for CBF buffered packets

TO_CBF_MIN: Minimum duration that a packet is buffered in the CBF packet buffer

TO_CBF_MAX: Maximum duration that packets are buffered in CBF packet buffers

PROG: The difference in the distance of the sander from the destination and the local distance between the ad hoc routers from the destination. That is, the difference between D and d4 in FIG.

DIST_MAX: The theoretical maximum communication range of radio access technology. By way of example, this value may be specified in the specification describing the ITS access technology or in the 'itsGnDefaultMaxCommunicationRange' of the GN protocol.

In Equation 1, PROG ≦ DIST_MAX indicates a case where a packet is delivered to a router within a maximum communication range. The value of TO_CBF_MIN-TO_CBF_MAX is always negative. Therefore, the larger the value of PROG / DIST_MAX, the smaller the buffering time. DIST_MAX can be a fixed value that is preset, so that larger PROG values result in packets being buffered for less periods of time, so packets are re-broadcasted faster. In other words, the router closest to the destination with the fewest PROGs retransmits the packet fastest.

In Equation 1, PRFG> DIST_MAX represents a case where a packet is delivered to a router outside the maximum communication range. If the router is not within the transmission range of the sander, the router can buffer the minimum time and then retransmit the packet. If the router is not within the transmission range of the sander, it means that the information about the sander is not stored in the router's location table.

For geobroadcast, geoanicast, and geounicast packets that assume multihop in geonetworking, the extended header includes the PV of the source router and the PV of the destination, but not the PV of the forwarding router. The router that receives the packet can know the location of the forwarding router that forwarded the packet through GN_ADDR corresponding to the MID stored in its LocT (Location Table). During transmission, the geonetworking packet of the network layer is delivered to the link layer, and the link layer adds MIDs (MAC IDs) of the source and the destination. The link layer packet configuration is shown in FIG. The source MID is the MID of the Sander Router, and the destination MID can be 'Broadcast' in CBF. A packet is transmitted to a neighbor router in a broadcast type in a DSAP (Destination Service Access Point) of an LLC header, and a sander MID is transmitted to a source destination (Service Access Point) SSAP. In other words, in order to use a non-region contention-based forwarding algorithm, information of neighboring neighbor routers through beacons or SHBs should be stored in the location table.

In an embodiment, the TO_CBF_MIN and TO_CBF_MAX values in relation to Equation 1 described above may be set to values preset in the GN protocol. In the GN protocol, the TO_CBF_MIN value and the TO_CBF_MAX value may be defined in MIB itsGnCbfMinTime, itsGnCbfMaxTime, respectively. As an embodiment, the TO_CBF_MIN value may be set to 1 ms and the TO_CBF_MAX value to 100 ms. When the maximum communication distance DIST_MAX is set to 300ms, which is a typical DSRC transmission range, the buffer timer value of the CBF operation is calculated.

Assuming that PROG of forwarder candidate 1 is 300m, the timer setting value of forwarder candidate 1 is determined from equation (1) as TO_CBF = 100 + (1-100) / 300 * 300 = 1ms. Assuming that PROG of forwarder candidate 2 is 200m, the timer setting value of forwarder candidate 2 is determined from equation (1) as TO_CBF = 100 + (1-100) / 300 * 200 = 34ms. Therefore, the timer of the forwarder candidate 1 broadcasts the packet if it does not receive a signal forwarding the same packet for 1 ms after receiving the packet. The forwarder candidate 2 broadcasts the packet if it does not receive a signal forwarding the same packet for 34 ms.

Region contention-based forwarding algorithms aim at spreading data efficiently over a given area. Therefore, there is no fixed destination and the timer setting may be determined considering only the distance to the source. Area contention based algorithm proceeds when the router belongs to a specific area, and the purpose is to quickly distribute / deliver information within the area.

In FIG. 13, the packet broadcasted by the source router S is delivered to routers 1 to 6. Router 2, furthest from the source router, first broadcasts the packet, which receives Router 1 and Router 3 stops the timer and does not forward the same packet. Routers 4-6 do not receive packets forwarded by Router 2. Therefore, routers 4-6 run their own timers and broadcast their received packets when the timer expires. When Router 5 forwards the packet, Router 4, which has received the packet, terminates its timer and removes the packet that is ready for transmission from the buffer. Router 6, which has not received a packet forwarded by another router, forwards the packet when its timer expires. For area contention-based algorithms, the source router can quickly forward and share packets in all directions within a particular area.

In the area CBF transmission, the timeout in which the CBF packet stays in the CBF buffer may be calculated as in Equation 2 below.

In Equation 2, values of TO_CBF_MIN and TO_CBF_MAX are as described in Equation 1. However, in Equation 2, DIST represents a distance difference between the router itself and the sender. The sender can be either a previous forwarder or a source router. The router can refer to its LocT to determine the location of the sander.

The timer may be set so that a router far from the sander first broadcasts a CBF packet. In contrast to the non-area CBF described above, a timer is set for a non-area CBF to send a packet first to a router close to the destination, and a router far from the sander to send a packet first for a region-CBF. The timer is set.

15 shows an ITS-G5 architecture according to an embodiment of the invention.

The ITS-G5 architecture includes an application & facility layer, a transport & network layer, an access layer, a management layer, and a security layer. The management layer coordinates inter-layer motion. When the application & facility layer generates the required message, the transport layer encapsulates the message to include in the header the port information to which the message will be delivered.

The network layer adds the information needed for ad hoc network communication to the message header and forwards the message to the access layer. The access layer transmits packets in an enhanced distributed channel access (EDCA) manner. EDCA refers to a method in which a packet having a high priority occupies the channel in preference to a channel content, discriminating the order of accessing the channel according to a traffic class. Four buffers may be configured according to the traffic class. There are four types of buffers: VO (Voice), VI (Video), BE (Best Effort), and BK (Background). The access layer includes GateKeeper logic for decentralized congestion control (DCC). Therefore, the access layer may control the flow of packets and control the power according to the busy situation of the channel. To this end, four buffers equal to the traffic class configured for EDCA can be used. (ETSI TS 102 612)

In Fig. 15, the operation of the CBF is as follows. Packets forwarded to CBF are stored in the CBF buffer of the network layer. When the timeout time set in the above-mentioned area CBF algorithm and non-area CBF algorithm elapses, the corresponding packet is delivered to the access layer in the CBR buffer. The access layer stores the packet in the gatekeeper's buffer based on the traffic class included in the packet header. All buffers in the access layer operate with a First Input First Output (FIFO) type, and when the packet's lifetime expires while stored in the buffer, the packet is destroyed.

As in Equation 1 and Equation 2, the time-out time for determining the time that a packet waits in the CBF buffer in the CBR algorithm is determined in inverse proportion to the distance between the sander and the router itself. That is, as shown in FIG. 16, the waiting time of a packet in the CBF buffer is calculated differently according to the distance to the sender. The embodiment of FIG. 16 is an example of an area CBF algorithm, and is calculated assuming that the value of DIS_MAX is 300m.

In the example of FIG. 16, the ad hoc router farther from the sender, the packet is queued in the CBF buffer for a shorter time. Therefore, in terms of the network layer, since the router farthest from the sender broadcasts first, transmission efficiency can be improved. However, in terms of the system as a whole, the desired transmission efficiency may not be achieved. This is because the transmission time to the actual channel may be different from the intended time due to the buffer for the gatekeeper and EDCA operation included in the access layer.

The internal buffer situation of the system (ITS-G5) of each router that receives a packet from the sender is different from each other independently. The amount of data accumulated in the buffer can vary depending on the application you use and the opportunity to access the channel. The packet stored in the CBF buffer at the network layer for the CBF operation is delivered to the access layer when the timeout time set according to the distance from the sender ends. Packets delivered to the access layer are stored in a corresponding buffer based on the traffic class information in the packet header. The buffer refers to both the buffer present in the gatekeeper and the buffer for EDCA, and may be stored in the gatekeeper's buffer first.

In FIG. 17, the traffic class buffer of each router represents the combined size of the buffer used by the gatekeeper logic and the buffer used for the EDCA. CBF packets broadcast by the sender are received by routers R1, R2, and R3. The received packet is stored in the CBF buffer of each router. The waiting time in the CBF buffer corresponds to 1ms for R1, 4.3ms for R2, and 7.6ms for R3, respectively.

The forwarding packet of R1 is first timed out of the CBR buffer and forwarded to the access layer. However, if the queue of R1's access layer is almost full, the forwarding packet must be queued and waiting until other packets are sent. The forwarding packet of R3 is stored in the CBF buffer for 7.6 ms, and the packet is forwarded to the access layer unless another router broadcasts the same packet. R3 does not have many packets stored in the buffer queue. As a result, a situation may occur in which a forwarding packet of R3 is broadcast before a forwarding packet of R1.

Although the timer for the CBF is precisely set based on the distance at the network layer, the broadcasting order of packets in the overall system side may be different from the setting order of the network layer. The amount of packets accumulated in the queue of each router's access layer is constantly changing, which no other router knows about. As shown in the embodiment of FIG. 17, the forwarding order may not be inversely proportional to distance, and if R3 and R1 are broadcast after being stored in the CBF buffer for the same 1 ms latency, efficiency is improved in terms of system latency. Can be.

The present invention proposes a method for calculating a timeout time for each sector in order to reduce latency, which is a disadvantage of CBF. Within the same sector, packets are stored in the CBR buffer with the same timeout, and the time actually broadcast can be determined differently depending on the internal queue state of each access layer. Equation for setting timeout according to an embodiment of the present invention is as follows.

TO_CBF: Timeout for CBF Buffered Packets

TO_CBF_MIN: Minimum time a packet should stay in the CBF packet buffer

TO_CBF_MAX: Maximum time a packet should stay in the CBF packet buffer

SECTOR_NUM_MAX: Maximum number of compartments dividing the maximum communication distance (DIST_MAX)

SECTOR_NUM: (1) In the case of the area CBF, SECTOR_NUM represents the numerical value of the sector (SECTOR) to which it belongs, and the sector is determined to be larger as the distance from the sander increases. (2) For non-area CBF, SECTOR_NUM represents the numeric value of the sector to which this value belongs after acquiring the distance difference between the destination and the sender and the distance between the destination and the router's local distance.

In one embodiment, the sector may be set as shown in Table 1 below.

SECTOR_NUM (섹터 넘버)SECTOR_NUM (sector number)	센더와 라우터 간의 거리Distance between sender and router	CBF 버퍼에서의 대기 시간Wait time in CBF buffer
77	300m 초과Over 300m	1ms1 ms
66	251m~300m251m ~ 300m	1ms1 ms
55	201m~250m201m ~ 250m	17.5ms17.5ms
44	151m~200m151m ~ 200m	34ms34 ms
33	101m~150m101m ~ 150m	50.5ms50.5 ms
22	51m~100m51m ~ 100m	67ms67 ms
1One	1m~50m1m ~ 50m	83.5ms83.5 ms

As shown in Table 1, when the maximum communication range is assumed to be 300m, the maximum number of sectors (SECTOR_NUM_MAX) can be set to six. The wait time for each sector may be set as shown in Table 1, and the wait time values in Table 1 are obtained using Equation 3.

As an embodiment, the six sectors may not be equally spaced. For the divided sectors, the sector number SECTOR_NUM may be set such that a value farther from the sender has a larger waiting value. The CBF buffer wait times of routers included in the same sector are all set identically. However, a router that first broadcasts a packet in the same sector is determined based on the buffer state of the access layer.

Applying the time-out time in sectors described above, since the R1 to R3 routers all belong to sector 6, the waiting time in the CBF buffer is all 1ms. In FIG. 18, packets accumulated in the buffer of the access layer have the least R3. Thus, the R3 router can first broadcast the packet.

In the case of the operation of FIG. 18, the latency of the system is greatly reduced compared to FIG. 17. In addition, when R1 and R2 receive a packet broadcast by the R3 router, R1 and R2 delete the forwarding packet waiting in the buffer, making the buffer queue more efficient.

Hereinafter, a description will be given of a method of setting a timeout by transmitting a substantial communication distance of the sender.

The DIST_MAX value of the CBF algorithm is determined based on the theoretical maximum communication distance of the access layer description. This value may be determined as the power / power value of the transmitting ITS station channel. However, in a multichannel environment, there may be interference between adjacent channels and characteristics of an antenna included in an actual ITS station may be different. Thus, the actual communication range may be different for each ITS station and may change dynamically. When TCP (Transmit Power Control) DCC is applied to change power dynamically, the dynamic characteristics of the communication range may be greater.

The above equations, which make time to determine the timeout of a buffer in the current CBF algorithm, are provided on the assumption that the communication range between the sender and the sender is the same. The location of the sender is not included in the packet header. Candidate forwarders consult the MAC source address of a packet received from the sender. That is, candidate forwarders may compare the MAC source address of the received packet with the values contained in their location table, and estimate the location of the sender from the location table.

Geonetworking Packet-The MPDU includes a MAC header, LLC header, geonetworking header and payload. Payload is optional. The MAC header includes a destination MAC address and a source MAC address.

Assuming only a single channel is used and the routers have the same communication range, the sender's location vector is stored in the neighbor router's location table. In the case of a non-region CBF, the candidate forwarder may know how close it is to the destination compared to the sender. Since the communication range of the sender is assumed to be the same as the communication range of the sender, the setting time of the timer in the buffer of the router may also be determined based on the communication range of the sender. Thus, among the routers in the destination direction from the sender, the timer of the router closest to the destination ends first, and the packet is broadcast to the surroundings. In the case of the area CBF, the purpose is to propagate the packet in a geographic area, and the router is located farther from the sender, the timer is first timed out and transmits the packet to the surroundings.

In a multi-channel environment, the communication range can vary depending on interference, power control DCC, antenna location, vehicle height, and the like. Thus, the use of a fixed maximum communication range value can lead to inefficiency. ETSI-ITS uses a plurality of channels by frequency allocation. The communication method of 802.11 may have a lot of interference, and when the channel power is adjusted to DCC, the communication range and the interference may be changed dynamically.

In Fig. 19, the theoretical communication range and the actual communication range of the sender are different. The sender's theoretical communication range includes candidate forwarder 1 and candidate forwarder 2, but the sender's actual communication range includes only candidate forwarder 2. Therefore, when the sender transmits multihop data, candidate forwarder 1 does not receive the packet.

In the example of FIG. 19, candidate forwarder 2 is located at the boundary of the sender's communication range, so that a low waiting time of the CBF buffer is suitable. However, since the waiting time is calculated in the theoretical communication range, the waiting time is increased, and thus the packet propagation speed is slowed down. Therefore, in order to solve such a problem, a description will be given of a method of forwarding its own communication range during forwarding and determining a CBF waiting time based on the reception router.

20 to 22, the same description as the packet header configuration described with reference to FIGS. 4, 7, and 9 does not overlap. In the case of FIGS. 20 to 22, a communication range field is added.

Communication range information indicates the actual communication range of the sender. The value of the communication range field may be a theoretical value considering transmission power, antenna characteristics, interference, and the like. In addition, the value of the communication range field may be an estimated value based on the measured communication situation. In multi-hop transmission, the communication range value can be changed every hop. The communication range value may be determined by each sender. The displayed distance value may be indicated in meters (m). As an example, the distance value may be displayed based on a particular unit, such as 10 meters or 20 meters.

In terms of equity, it can be assumed that the communication range of the ad-hoc router is the same. However, it is not assumed to be the maximum communication range of the theoretical access layer. Due to peripheral obstacles, the communication line may not be guaranteed in the communication, or the communication range may vary due to various factors such as a fading channel environment and interference caused by other surrounding channels. However, routers around them are subject to similar environmental impacts, so the range of communication can be assumed to be similar. In this case, the router may determine its own communication range using the location vector included in the geonetworking header of the data received from the neighbor router to the SHB.

In FIG. 23, a difference between location information received from neighboring routers and a location of a user for a predetermined time T may be calculated, and a maximum value may be determined as the maximum communication range of the device, and the packet may be included in a packet and transmitted. The maximum distance value obtained by monitoring for a certain time interval may be used for the next time interval. That is, the router may use the maximum distance value checked during the T time interval from time t to T + t during the next T time interval from time T + t to 2T + t. The router may observe the maximum communication range again during the second interval (T + t ~ 2T + t) and use the updated value at the next interval.

The maximum communication range may be calculated by adaptively reflecting. The maximum communication range may be obtained as shown in Equation 4.

CR_t: current communication range

CR_t-1: past communication range

MAX_t: Maximum distance from neighboring routers observed over time interval (T)

α: weight value assigned to previous CR_t-1 value, 0 <α <1

β: weight value given to the current communication range, 0 <β <1

During the time interval T 'greater than the time interval T, the average of the maximum distance values obtained for each time interval T may be set as the maximum communication range. For example, setting the average of the maximum distance values obtained for 10T as a possible communication range, the router can be used in the calculation of the buffer of the CBF, in which case the calculation can be performed according to a sliding window method. .

When calculating the communication range by the above-described method, since only the location information of the surrounding vehicles is used, there is a disadvantage in that the communication range value depends on the available vehicle position or the number of vehicles. Limits on distance or number of vehicles may be placed to reduce errors due to measurements. For example, when the specific communication ranger is less than or equal to the predetermined threshold value, a previously obtained value may be used or a theoretical communication range value may be used. In addition, when the number of neighbor routers used to calculate the communication range is less than or equal to a predetermined threshold value, a previously obtained value or a theoretical communication range value may be used.

The invention described above in FIG. 23 assumes that neighboring routers have the same communication range. However, when a difference in communication range occurs, the accuracy of the communication range obtained according to the embodiment of FIG. 23 may be lowered. Therefore, the present invention proposes a method of using a location of a router transmitting a packet corresponding to a response of a packet transmitted by the router. Receiving the response confirms that the data sent by the router has been delivered. Therefore, the router can confirm that there is a router that responds to the communication range.

When the sender broadcasts the packet, at least one of the forwarder candidates that received the packet forwards the packet. Forwarded packets are also propagated in a broadcast manner, and senders belonging to the forwarder's communication range can also receive these packets. Whether the packet sent by itself is forwarded can be confirmed through the SN in the packet. Since routers broadcasting the same packet as the transmitted packet are certainly included in the communication range, the ego router can estimate the communication range using only the locations of these routers. This method can be useful especially when communication using CBF occurs frequently in vehicle networks.

In addition, when a packet corresponding to a response of a packet transmitted in a single hop is received, the router which transmitted the response packet is sure to exist within the communication range of the ego router, so that the communication range is obtained using the location information of the router. can do. The router may obtain a communication range by using the location information of the router which transmitted the forwarding packet or the response packet.

In an embodiment of the present invention, the access layer uses a communication technology of 802.11p. The 802.11p access layer does not use signals such as Clear To Send (CTS), Request To Send (RTS), or Acknowledge (ACK). The RTS is a signal that the transmitting device reserves a radio link for transmission, and the CTS is a signal that the receiving party is ready to receive the signal and does not transmit to all node devices listening to the radio link from now on. The ACK is a signal for receiving a packet of a receiving device and informing the reception, and may indicate that the channel has become available. However, as an embodiment, a communication technology other than 802.11p may be used as the access layer technology of the V2X communication device. If another communication technology uses RTS, CTS, ACK, these signals may be used to measure the communication range. The measured communication range is delivered to the network layer and may be included in the packet header. The router may use the measured communication range information to determine the timeout time of the CBF packet.

When the communication range is determined as shown in FIGS. 23 to 24, DIST_MAX in Equations 1 to 3 may be set to the determined actual communication range. In this case, the range of actual communication can be estimated based on the location information of the neighbor routers, and it can be shared with the candidate forwarders. Therefore, buffer setting may be more efficient in CBF transmission. Since the actual communication range according to the channel environment of the actual field may be smaller than the theoretical maximum communication range than the theoretical maximum communication range, the CBR buffer latency can be set more efficiently, and thus the system latency can be improved. In the embodiment of FIG. 19, the candidate forwarder 2 may forward the packet after a shorter buffer wait time than the conventional method.

In FIG. 25, the V2X communication device 25000 may include a communication unit 25010, a processor 25020, and a memory 25030.

The communication unit 25010 may be connected to the processor 25020 to transmit / receive a radio signal. The communication unit 25010 may upconvert data received from the processor 25020 into a transmission / reception band to transmit a signal, or downconvert the received signal. The communication unit 25010 may implement at least one of the physical layer and the access layer.

The communication unit 25010 may include a plurality of sub-RF units for communicating in accordance with a plurality of communication protocols. As an embodiment, the communication unit 25010 includes 2G including Dedicated Short Range Communication (DSRC), ITS-G5 wireless communication technology based on physical transmission technology of the IEEE 802.11 and / or 802.11p standards, and satellite / wideband wireless mobile communication. Data communication may be performed based on / 3G / 4G (LTE) / 5G wireless cellular communication technology, broadband terrestrial digital broadcasting technology such as DVB-T / T2 / ATSC, GPS technology, IEEE 1609 WAVE technology, and the like. The communication unit 25010 may include a plurality of transceivers that implement each communication technology.

The processor 25020 may be connected to the communication unit 25010 to implement operations of layers according to the ITS system or the WAVE system. The processor 25020 may be configured to perform an operation according to various embodiments of the present disclosure according to the above-described drawings and descriptions. In addition, at least one of a module, data, a program, or software for implementing the operation of the V2X communication device 25000 according to various embodiments of the present disclosure described above may be stored in the memory 25030 and executed by the processor 25020. have.

The memory 25030 is connected to the processor 25020 and stores various information for driving the processor 25020. The memory 25030 may be included in the processor 25020 or may be installed outside the processor 25020 and connected to the processor 25020 by known means.

The processor 25020 of the V2X communication device 25000 may perform the geonetworking packet transmission described in the present invention. A method of transmitting a geonetworking packet by the V2X communication device 25000 will be described below.

26 is a flowchart illustrating a geonetworking transmission method according to an embodiment of the present invention.

The V2X communication device receives a geonetworking packet from the sender V2X communication device (S26010).

The V2X communication device checks whether the received geonetworking packet is a packet previously stored in the buffer (S26020).

If the received geonetworking packet is a packet previously stored in the buffer, the V2X communication device discards the received geonetworking packet (S26030).

If the V2X communication device does not store the received geonetworking packet in the buffer, the V2X communication device stores the received geonetworking packet in the buffer and starts a timer (26040). The V2X communication device sets a timeout duration and starts a timer for packet retransmission.

The V2X communication device transmits a packet when the timer expires (S26050).

The timeout period represents the time period during which a packet is buffered in a buffer. The maximum communication distance of the sander V2X communication device may include a plurality of sectors. Each of the plurality of sectors may have a constant time out period. The sector and time out period may be set as shown in Table 1. The timeout period of the plurality of sectors may be determined based on the distance between the sender V2X device and the V2X device that transmitted the received packet. The larger the distance, the smaller the timeout period can be.

20 to 22, the geo-networking packet may include communication range information of the V2X communication device for transmitting the geo-networking packet. The value of the communication range information may be determined as the maximum value of difference values between the positions of the peripheral V2X communication apparatuses and the positions of the V2X communication apparatuses that communicated during the specific time interval. The peripheral V2X communication device may correspond to a V2X communication device in which a response packet or a forwarding packet is received for a packet transmitted by the V2X communication device. The value of the communication range information may be used during the second time interval as a maximum value of difference values between the position of the V2X communication apparatuses and the position of the V2X communication apparatus that communicated during the specific time interval. Determination and use of the communication range information value are as described with reference to FIGS. 23 and 24.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of a hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code may be stored in memory and driven by the processor. The memory may be located inside or outside the processor, and may exchange data with the processor by various known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

It is understood by those skilled in the art that various changes and modifications can be made in the present invention without departing from the spirit or scope of the invention. Accordingly, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Reference is made herein to both apparatus and method inventions, and the descriptions of both apparatus and method inventions may be complementary to one another.

Various embodiments have been described in the best mode for carrying out the invention.

The present invention is used in the field of vehicle communications.

It will be apparent to those skilled in the art that various changes and modifications can be made in the present invention without departing from the spirit or scope of the invention. Accordingly, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

In the geo-networking transmission method of the V2X communication device,

Receiving a geonetworking packet from a sender V2X communication device;

Checking whether the received geonetworking packet is a packet previously stored in a buffer;

If the received geonetworking packet is not a previously stored packet, storing the geonetworking packet in a buffer, setting a timeout duration, and starting a timer for retransmitting the packet; And

Transmitting the geonetworking packet when the timer expires,

And the timeout period represents a time period during which the packet is buffered in the buffer.
The method of claim 1,

The maximum communication distance of the sender V2X communication device includes a plurality of sectors, each of the plurality of sectors having a constant timeout period.
The method of claim 2,

The timeout period of the plurality of sectors is determined based on the distance between the sender V2X device and the V2X device that transmitted the received packet, the larger the timeout period, the smaller the geonetworking transmission method.
The method of claim 3, wherein

And the geonetworking packet includes communication range information of a V2X communication device transmitting the geonetworking packet.
The method of claim 3, wherein

And wherein the value of the communication range information is determined as a maximum value of difference values between a location of surrounding V2X communication devices and a location of the V2X communication device communicating during the first time interval.
The method of claim 5,

And the surrounding V2X communication device is a V2X communication device receiving a response packet or a forwarding packet to a packet transmitted by the V2X communication device.
The method of claim 5,

And wherein the value of the communication range information is used during the second time interval as a maximum of difference values between the position of the surrounding V2X communication devices and the position of the V2X communication device communicating during the first time interval.
In the V2X communication device,

A memory for storing data;

A communication unit for transmitting and receiving a radio signal including a geonetworking packet; And

A processor controlling the memory and the communication unit,

The processor,

Receive geonetworking packets from the sender V2X communication device,

Check whether the received geonetworking packet is a packet already stored in the buffer,

If the received geonetworking packet is not a pre-stored packet, store the geonetworking packet in a buffer, set a timeout duration, start a timer for retransmission of the packet,

Transmit the geonetworking packet when the timer expires,

Wherein the timeout period represents a time period during which the packet is buffered in the buffer.
The method of claim 8,

The maximum communication distance of the sender V2X communication device comprises a plurality of sectors, each of the plurality of sectors having a constant timeout period.
The method of claim 9,

The timeout period of the plurality of sectors is determined based on a distance between the sender V2X device and the V2X device that transmitted the received packet, and the larger the distance, the smaller the timeout period.
The method of claim 10,

And the geonetworking packet includes communication range information of a V2X communication device transmitting the geonetworking packet.
The method of claim 10,

And the value of the communication range information is determined as a maximum value of difference values between a location of surrounding V2X communication devices and a location of the V2X communication device communicating during a first time interval.
The method of claim 12,

The peripheral V2X communication device is a V2X communication device, wherein a response packet or a forwarding packet to a packet transmitted by the V2X communication device is received.
The method of claim 12,

And the value of the communication range information is used during the second time interval as a maximum value of difference values between the position of the surrounding V2X communication devices and the position of the V2X communication device communicating during the first time interval.