FR3098077A1 - METHOD AND DEVICE FOR CONFIGURING VEHICLE-TO-VEHICLE COMMUNICATION - Google Patents

Abstract

The invention relates to a device and method for configuring vehicle-to-vehicle communication based on vehicle-to-vehicle frequency configuration and on establishing IPv6 paths between vehicles. The method includes defining a role for each vehicle of a plurality of vehicles, the roles including a lead vehicle role, a tail vehicle role and at least one lambda vehicle role where a lambda vehicle is a vehicle positioned between the lead vehicle and the rear vehicle; then assigning to each of the leading and trailing vehicles at least one vehicle-to-vehicle communication frequency, and assigning to the lambda vehicle at least two different vehicle-to-vehicle communication frequencies, a first frequency for communicating with a vehicle preceding it and a second frequency for communicating with a vehicle following it; then performing for each vehicle a protocol for discovering immediate neighbors, an immediate neighbor of a vehicle being a vehicle preceding it and / or a vehicle immediately following it; and configuring each vehicle to reach only its and / or its immediate neighbor (s) with the assigned vehicle-to-vehicle communication frequencies. Figure for the abstract: Fig. 5

Description

Method and device for configuring vehicle-to-vehicle communication

Field of invention

The invention lies in the field of vehicle-to-vehicle (V2V) communications allowing the establishment of a grouping of vehicles by platoons, and relates more particularly to a method and a device for configuring a V2V communication, based on a configuration vehicle-to-vehicle frequencies and establishing IPv6 paths between vehicles.

State of the art

The grouping of vehicles by platoons or road convoy or "platooning" according to the established Anglicism, is a way of increasing the capacity of the roads. The road convoy generally involves vehicle perception sensors such as camera, radar and ultrasound to ensure coordinated movement between each vehicle in the convoy.

In the case of use of automobiles, the solutions for managing a road convoy are mainly based on the use of perception sensors combined with the use of vehicular communication. This operation is faulty when the sensors are obstructed or their performance is not optimal, even if communication systems are used.

A first platooning experiment took place in 1997 by the NAHSC (“National Automated Highway Systems Consortium”). It was a convoy of eight fully automated motor vehicles and traveling with relatively short inter-distances. The lane of this convoy was equipped with magnetic sensors that served as reference markers to keep the vehicles in their lane. The vehicles were equipped with communication systems that allowed them to exchange information such as their acceleration, relative speed and distance from the vehicle in front. The main drawback of this method is that it requires equipping all the road infrastructures with magnetic sensors to readjust the position of the elements of the convoy in the traffic lane.

A second experiment was carried out within the framework of the “Dutch Connect & Drive” project between 2009 and 2010. For this case, automated motor vehicles were equipped with the CACC function (“Cooperative Adaptive Cruise Control”) to carry out the platooning. This technique is mainly based on radar sensors and the exchange of standard messages of the ITS-G5 standard. The main drawback lies in the exchange of standard ITS-G5 messages which requires, on reception by the vehicle, processing to know whether it is data to be used for platooning or whether it is information disseminated by a vehicle for other purposes. The ITS-G5 messages which are transmitted in the inter-vehicular communication pose two problems:
-The messages are transmitted with a frequency of at most 10 Hz (10 messages per second, ie one message every 100 ms in the nominal case), which poses a problem of reactivity of the convoy.
-The messages are transmitted in "broadcast" and therefore do not identify a recipient, which complicates the logic of the receivers. Indeed, a receiver does not know if this message is addressed to him, and he has difficulty determining his position in the convoy. Moreover, when several vehicles receive the same information at the same time, how does each one know where to position themselves, how does one know whether any vehicle is concerned by the information or not?

Also, this type of approach requires a message classification operation, which takes time and also affects the reactivity of the convoy.

More recently, a third experiment took place in 2016 in the Netherlands, as part of the “European Truck Platooning Challenge” in which several car manufacturers such as Volvo, Scania and Daimler took part. The techniques developed mainly combine the use of sensor data (radar and cameras), Wi-Fi communication between vehicles to exchange video streams and other vehicle data, and a display screen placed inside the cockpit to allow the driver to visualize what is happening in front of him and to regain control if necessary. These techniques have two main drawbacks: this requires the driver of the following vehicles to be constantly focused on the display screen and, moreover, if the data flows (especially video) are too high, this risks degrading the quality of the communication and therefore the responsiveness of the convoy.

The following patent applications provide methods for implementing platooning:
- KR20110036316 A “Method for platooning of electric car” published on 07/04/2011, proposes a platooning system for electric vehicles, through inter-vehicle communication, in the express lane. Each vehicle is equipped with a connectivity box that allows it to connect with the vehicles in front and behind it. The disadvantage of this method is that the vehicles are physically connected, which is not possible for use in real conditions.
-US 2019/0079540 A1 "Method for platooning of vehicles and vehicle using same" published on 03/14/2019, proposes a platooning system in which a lead vehicle provides a control signal and one or more follower vehicles which receive this signal adapt(s) their conduct accordingly. This method includes determining the state of the group of vehicles and adjusting the inter-distance. In this approach, the information is transmitted in broadcast and the objective is to adapt the formation of the platooning to the quality of the transmission. The problem is not that targeted by the invention.
-US 2019/0045337 A1 "V2V Communication Method, Device and System" published on 02/07/2019, proposes a method which uses a fixed base station to inform cars in a convoy of certain radio parameters to use. However, this poses a problem of operation of the convoy in the absence of a base station, since the base station networks are not deployed at all the places where there are roads.

For the realization of platooning based on exchanges of V2V messages without using a base station, a single communication interface is used in each vehicle. In the patent application JP2005018581 A “Inter-Vehicle Communication Vehicle”, two distinct antennas called MIMO placed at the front and at the rear of the vehicle are connected to a single communication interface configured in a single communication channel. All interfaces and antennas in all cars are in the same channel. However, the use of a single communication interface in a single channel with one or more antennas has drawbacks:
- the propagation of messages in convoys longer than the radio range allowed by the regulations in force relating to the power of transmission is problematic. Typically, in France, at 5.9GHz it is allowed to use a maximum transmit power of 33 dBm which, in practice, leads to maximum distances of around 800m to 1km. Therefore, in a convoy where the 1st vehicle is more than 1km from the last, there may be messages lost between the 1st and the last.
- the use of a single interface causes the creation of additional interference. A message received by a vehicle but addressed to another more distant vehicle is necessarily repeated (repetition by the link layer) by the vehicle having received it, which creates interference in the channel.
the use of multiple antennas in MIMO mode on a single communication interface offers better reception quality thanks to “spatial diversity”, but there is still the problem of creating additional interference in the channel in transmission.

There is then a need to overcome the drawbacks of the known approaches and to propose a solution allowing Vehicle-to-Vehicle (V2V) communication between the vehicles of a linear convoy. The present invention meets this need.

An object of the present invention relates to a method and a device for Vehicle-to-Vehicle communication in order to set up a cooperative platooning between different vehicles of a convoy, which are based on a configuration of the vehicle-to-vehicle frequencies, and on the establishment of IP paths between vehicles.

The invention will find numerous applications whether in the civil or military field. Thus, in the remainder of the description, the term platooning designates a convoy of vehicles, whether the convoy is civilian or military, whether the vehicles are military vehicles, automobiles, trucks, train wagons, mobile platforms robotized, whether the convoy moves on land or at sea or even in the air.

The present invention is applicable to the automotive industry, the Internet of Things (IoT), vehicular networks (IEEE 802.11-OCB), intelligent transport systems with the development of the autonomous and connected vehicle (which can be considered as a connected object that disseminates information through a V2V communication network). The invention is of interest to companies in the automotive industry, such as car manufacturers or research institutes operating in this field.

Thus, the general principle of the invention consists in implementing platooning between two or more vehicles of a convoy, by the use of distinct communication channels having different frequencies at the front and at the rear of the vehicle. , and by establishing routes between vehicles in convoy by defining the role of each vehicle and propagating them by IP prefixes.

Advantageously, the method and the device of the invention do not use a base station to establish communications.

Advantageously, the proposed solution allows a fluid management of a convoy, by the coordination which is established between the vehicles, because it is based on an interaction by exchanges of data from one vehicle to another, rather than by a perception .

• définir un rôle pour chaque véhicule d’une pluralité de véhicules, les rôles comprenant un rôle de véhicule de tête, un rôle de véhicule de queue et au moins un rôle de véhicule lambda où un véhicule lambda est un véhicule positionné entre le véhicule de tête et le véhicule de queue ;
• attribuer à chacun des véhicules de tête et de queue au moins une fréquence de communication véhicule-à-véhicule, et attribuer audit au moins un véhicule lambda au moins deux fréquences différentes de communication véhicule-à-véhicule, une première fréquence pour communiquer avec un véhicule le précédant et une deuxième fréquence pour communiquer avec un véhicule le suivant ;
• effectuer pour chaque véhicule un protocole de découverte de voisins immédiats, un voisin immédiat d’un véhicule étant un véhicule qui le précède et/ou un véhicule qui le suit immédiatement ; et
• configurer chaque véhicule pour joindre uniquement son et/ou ses voisin(s) immédiat(s) avec les fréquences de communication véhicule-à-véhicule attribuées.

To achieve the desired results, there is provided a computer-implemented method for configuring vehicle-to-vehicle communication, the method comprising the steps of:

• define a role for each of a plurality of vehicles, the roles including a lead vehicle role, a tail vehicle role and at least one lambda vehicle role where a lambda vehicle is a vehicle positioned between the lead vehicle and the tail vehicle;
• allocating to each of the leading and trailing vehicles at least one vehicle-to-vehicle communication frequency, and allocating to said at least one lambda vehicle at least two different vehicle-to-vehicle communication frequencies, a first frequency for communicating with a preceding vehicle and a second frequency for communicating with a following vehicle;
• performing for each vehicle an immediate neighbor discovery protocol, an immediate neighbor of a vehicle being a vehicle preceding it and/or a vehicle immediately following it; And
• configure each vehicle to reach only its and/or its immediate neighbor(s) with the assigned vehicle-to-vehicle communication frequencies.

According to alternative or combined embodiments:
-the role definition step is done from a centralized server by activating remote role definition scripts.
the step of allocating vehicle-to-vehicle communication frequencies consists in allocating to a lambda vehicle a first frequency for communications with a vehicle preceding it, and a second frequency for communications with a vehicle following it.
the step of allocating vehicle-to-vehicle communication frequencies consists of allocating the lead vehicle the same frequency as one of the two frequencies of a lambda vehicle and allocating the tail vehicle the same frequency as the one of the two frequencies of a lambda vehicle.
- the allocated frequencies are in the 5.9 GHz frequency band called ITS.
the immediate neighbor discovery step consists for each vehicle in generating messages to announce its presence and its address space.
the step of configuring each vehicle consists for each vehicle in receiving and processing messages received from other vehicles.
-the immediate neighbor discovery step is based on the "Neighbor Discovery Protocol" protocol and consists of generating ICMPv6 "Router Advertisement" messages that allow each vehicle to announce its IPv6 prefix, and the configuration step of each vehicle consists in receiving and processing ICMPv6 “Router Advertisement” messages received from other vehicles.

The method further includes a step of route propagation to immediate neighbors to establish vehicle-to-vehicle communication for the plurality of vehicles and allow each vehicle to communicate with all others through a routing protocol.

The invention covers a computer program product comprising non-transitory code instructions making it possible to perform the steps of the claimed method, when the program is executed on a computer.

The invention further covers a device for configuring vehicle-to-vehicle communication between a plurality of vehicles, the device comprising means for implementing the steps of the method according to any one of the claims.

According to alternative or combined embodiments:
- each vehicle has a communication box including:
- two wireless vehicle-to-vehicle communication interfaces;
- a vehicle role definition module configured to define the role of the vehicle, the role being able to be a lead vehicle role, a tail vehicle role or a lambda vehicle role, a lambda vehicle being a vehicle positioned between a lead vehicle and a tail vehicle;
-a frequency configuration module configured to assign to at least one interface of the communication box on board a leading or trailing vehicle, at least one vehicle-to-vehicle communication frequency, or to assign to each communication interface of the communication unit on board a lambda vehicle, at least two different vehicle-to-vehicle communication frequencies, a first frequency for communicating with a vehicle preceding it and a second frequency for communicating with a vehicle following it; And
a message processing module configured to perform an immediate neighbor discovery protocol for the vehicle, an immediate neighbor of a vehicle being a vehicle preceding it and/or a vehicle immediately following it, and to configure the vehicle to so as to reach only its and/or its immediate neighbour(s) with the assigned vehicle-to-vehicle communication frequency(ies).
- the two wireless vehicle-to-vehicle communication interfaces are configurable according to IEEE 802.11-OCB technology.
-at least one antenna is coupled to at least one wireless vehicle-to-vehicle communication interface.

The invention covers a vehicle comprising a communication box as claimed.

Description of figures

Different aspects and advantages of the invention will appear in support of the description of a preferred mode of implementation of the invention but not limiting, with reference to the figures below:

shows an example of implementation of the device of the invention in one embodiment;

illustrates a datagram format of an IPv6 type RA message;

illustrates a variant embodiment of the device of the invention implemented on an electronic card on board a vehicle;

illustrates a sequence of steps for configuring the device of the invention after the role has been assigned to a vehicle;

illustrates for a platooning of several vehicles, the definition of role per vehicle and the allocation of frequencies to each interface of each vehicle;

illustrates the number of iterations necessary for the propagation of routes for different convoys ranging from two to N vehicles; And

illustrate the steps for setting up communication within a platoon, from frequency configuration to route propagation for, a lambda vehicle, a lead vehicle and a tail vehicle.

Detailed description of the invention

Before describing in detail an implementation of the invention, the terminology used in the description is given.

IEEE 802.11-OCB: this is a Wireless LAN type communication link defined by the IEEE. In this link, the PHY and MAC layers are those of the 802.11 protocol but without control messages or authentication. The operating mode is called OCB for “Outside the Context of a BSS ID” according to English terminology. This link operates in the 5.9GHz band. 10MHz wide channels are allocated as follows: 5875 MHz – 5885 MHz; 5885MHz - 5895MHz; 5895 MHz – 5905 MHz and 5905 MHz – 5915 MHz. IEEE 802.11-OCB networks are used for communications between vehicles, as wireless access in vehicular environments.

IPv6: Internet Protocol version 6 is an Open Systems Interconnection (OSI) model Layer 3 connectionless network protocol with 128-bit IPv6 addresses.

IPv6 prefix: the prefix of an IPv6 address is made up of the first n bits of this address. For example, the address 2001:db8:1::1/48 has the prefix 2001:db8:1:: of length 48 bits (n == 48).

LL for local link or “Link-local” in English. An LL-type IPv6 address is a network address that can only be used on a link. Packets whose source or destination are LL addresses cannot be transmitted beyond a link (they are not "forwarded").

NDP for “Neighbor Discovery Protocol” in English [RFC 3971] is a protocol responsible for discovering other network nodes on the same local link, determining the link layer addresses of other nodes, searching for routers available and the management of routes to other active neighboring nodes. The NDP neighbor discovery protocol enables equipment to integrate into the local environment, ie the link over which IPv6 packets are physically transmitted. It allows dialogue with the devices connected to the same medium. It is not a question for a device of knowing exactly the list of all the other devices connected on the link, but only of managing those with which it dialogues.

ICMPv6 for "Internet Control Message Protocol version 6" in English [RFC 4443] is a generic management protocol for running IPv6. It allows the transmission of many different message types which are used to identify the type of message being transmitted.

RA for "Router Advertisement" in English is a type of ICMPv6 packet defined in the NDP protocol. It allows routers to advertise their presence with various link parameters, either periodically or in response to a router's solicitation.

PIO for "Prefix Information Option" in English is an option defined in RA messages [RFC 4861].

RIO for "Route Information Option" in English is an option defined on RA messages [RFC 4191].

FIG. 1 shows an exemplary implementation of the device (100) of the invention which comprises at least two vehicle-to-vehicle wireless communication interfaces (102, 104), a vehicle role definition module (106), a frequency configuration module (108) and an IP message processing module (110).

In a preferred implementation, the communication interfaces (102, 104) are configurable according to IEEE 802.11-OCB technology, the frequencies operate in the 5.9 GHz frequency band, more particularly according to the ITS-G5 standard, and the messages are messages IPv6 type 'Router Advertisement'. Figure 2 illustrates a datagram format of an IPv6 RA message including the following fields: 'Type=134' (the value 134 specifies that it is an RA), 'Code=0' , 'Checksum' , 'Maximum hops', 'Flags', 'Router Lifetime', 'Time for which the entry is held in the routing table', 'Maximum time with retransmission' and 'Options'. Those skilled in the art may refer to the existing literature for more detailed definitions of these different fields and in particular [RFC 4861].

In a particular embodiment, the message processing module (110) processes (sending, analyzing, receiving) three types of RA messages defined in the 'Option' field:
-TYPE1: the RA has a value of the 'Router LifeTime' field different from '0' and a PIO containing the prefix of the Ethernet interface of a connectivity box which sends the RA and the LL address of this interface. This TYPE1 is used to configure an IPv6 address on a computer embedded in the vehicle and to define the LL address of the connectivity box as the default route (SLAAC Stateless Address Auto-Configuration Protocol, [RFC 4862]).
-TYPE2: the RA has a value of the 'LifeTime' field equal to zero, an 'RIO-1' containing the prefix of the Ethernet interface of the connectivity box which sends the RA and the LL address of the IEEE 802.11 interface -OCB from which it sends the RA. RA's TYPE2 is used in the invention to advertise the IPv6 prefix to immediate neighbors via IEEE 802.11-OCB interfaces. A connectivity box that receives a TYPE2 RA is able to add a new entry in its routing table to join the corresponding prefix (network).
-TYPE3: the RA has a value of the 'LifeTime' field equal to zero, an 'RIO-1' containing the prefix of the Ethernet interface of the connectivity box which sends the RA, an 'RIO-2' containing the prefix of the Ethernet interface of an immediate neighbor and the LL address of the IEEE 802.11-OCB interface of the connectivity box that sends the RA. The TYPE3 of RA makes it possible, within the framework of the invention, to propagate learned routes (by the prefixes belonging to other connectivity boxes) to other vehicles.
-TYPE2 with a non-zero 'Router LifeTime' field value is defined in [RFC4191]. TYPE2 with 'Router LifeTime' field value of zero is not defined in any document. Type2 implementations with a non-zero 'Router LifeTime' field value exist but they no longer work if zero 'LifeTime' is forced. In the context of the invention, software modifications are made to overcome this problem in order to send TYPE2 and TYPE3 messages with a 'LifeTime' of zero.

[RFC2894] "IPv6 Router Renumbering" describes the operation for receiving a prefix on an interface and using information relating to this prefix on another interface. However, this does not do prefix propagation. Two distinct values are used: a 'Prefix-Match' received on one interface and a 'to be replaced' sent on another interface, these two values being mapped in a table. In the context of the invention, a single prefix value is used, and as it is received on one interface, it is sent on another interface.

No prior art document describes the combined sending of two 'RIOs': an RIO containing the prefix of another interface (RIO-1) and an 'RIO' containing the prefix received from another router (RIO -2).

As illustrated in Figure 3, the device of the invention can be implemented on an electronic card enclosed in a communication box (300) in order to be easily embedded in a vehicle (302). In a particular embodiment, the electronic card has an operating system which has the functionalities necessary to support IEEE 802.11-OCB and all the dependency modules. The operating system can be “OpenWrt” with a kernel (“kernel”) modified to adapt it to IEEE 802.11-OCB. The IPv6 protocol must be able to be activated on the electronic card so as to configure the two interfaces (102, 104) in IPv6 on OCB.

In one embodiment, the card has an Ethernet interface (304) to connect it to an on-board computer (306) by means of an Ethernet cable (308) and allow its configuration.

In one embodiment, an antenna (308-ar, 308-av) is respectively connected to each interface (102, 104). As detailed below, depending on the role of the vehicle, one or both antennas is/are active.

In one embodiment of a convoy restricted to two vehicles, each vehicle is equipped with the device of the invention with two active antennas, an antenna at the front and an antenna at the rear of each vehicle. Each antenna is connected to an interface of the electronic card, configurable in OCB.

In one embodiment, a remote machine (server) can supervise and control the convoy in real time. This can ensure rapid reconfiguration of the roles and frequencies of the interfaces of the communication box of each vehicle in the convoy, in the event, for example, of a convoy that is making a U-turn at the level of a roundabout and where the convoy order is reversed. It is then necessary to quickly reconfigure the frequencies of each interface of each box to avoid a too long interruption of the communication between the vehicles, which would cause a failure in the platooning.

Returning to FIG. 1, the role definition module (106) defines the role of the vehicle according to its location in the convoy. Thus, a vehicle can have one of three roles:
-Lead vehicle role: this is the vehicle placed at the head of the convoy, the one that takes on the role of leader in the convoy.
- Role of tail vehicle: it is the follower vehicle placed at the very end of the convoy, the one who is at the tail of the convoy.
-Role of lambda vehicle: it is a vehicle of the convoy placed at any position different from the position of the lead vehicle and the tail vehicle.

Once the role has been assigned to a vehicle and defined in the role definition module (106), the vehicle's interfaces are configured in the interface frequency configuration module (108).

In one embodiment, the assignment of the role to each vehicle is made by a vehicle fleet manager. The fleet manager can be a software program on a centralized server which pilots the convoy remotely, distributes roles remotely, activates scripts remotely.

In an alternative embodiment of a convoy with few vehicles, the assignment of the role to each vehicle is made by a physical operator vehicle fleet manager, who decides the order of the vehicles.

In one embodiment, role definition scripts are implemented in an on-board computer of each vehicle. These scripts allow a fleet manager to indicate the position or the role (head, lambda, tail) of the vehicle considered in the platooning. In one embodiment, the roles can be defined as "Leader", "First follower", "Second follower", etc.

In one embodiment, a reset script is implemented in the on-board computer of each vehicle in order to separately reset the configuration of the V2V communication device of the invention dedicated to platooning in each vehicle.

FIG. 4 illustrates a sequence of steps (400) for configuring the device of the invention, after assigning the role to a vehicle (defined in the role definition module). In a first step (402), the method makes it possible to configure the frequency or frequencies of one or each of the two interfaces of the device, according to the role of the vehicle.

Thus for the lead vehicle: its specific position means that it needs to communicate directly and only with the vehicle following it, since there is no vehicle in front of it. Also, for a leading vehicle, only the interface connected to the rear antenna of the vehicle is configured in IEEE 802.11-OCB with one of the appropriate frequencies available.

For the trailing vehicle: its particular position means that it needs to communicate directly and only with the vehicle in front of it, since no vehicle is following it. Also, for a rear vehicle, only the interface connected to the front antenna of the vehicle is configured in IEEE 802.11-OCB with one of the appropriate frequencies available.

For an average vehicle: its position means that it needs to communicate with the vehicle in front of it and with the vehicle behind it. Also for an ordinary vehicle, the two interfaces, connected respectively to the antennas at the front and at the rear of the vehicle must be configured in IEEE 802.11-OCB with appropriate different frequencies available.

Interfaces are configured with different frequencies on each front and rear interface and pass V2V communication through appropriately configured interfaces. Advantageously, this makes it possible to avoid interference during the execution of the process of setting up the platooning.

Configuring frequencies on interfaces consists of configuring at least two frequencies to support IEEE 802.11-OCB. In one embodiment, it is possible to use four (non-licensed) center frequencies in the ITS-G5 frequency band, namely the frequencies 5870 MHz, 5880 MHz, 5890 MHz and 5900 MHz, with a bandwidth of 10 MHz frequencies. The distribution of roles to the vehicles makes it possible to optimize the use of the four frequencies to support a large number of vehicles in the platooning.

Figure 5 illustrates for a platooning of several vehicles, the role definition per vehicle and the allocation of frequencies to each interface of each vehicle. Thus, the rear interface of the lead vehicle is configured at the same ‘F1’ frequency as the front interface of the lambda vehicle following it; the rear interface of a lambda vehicle is configured at the same frequency ('F2', 'F3', …'Fx') as the front interface of the vehicle following it, which is either a lambda vehicle or the vehicle of tail. The frequencies are configured so that for two vehicles following each other, the antenna placed at the rear of the vehicle in front can communicate with the antenna placed at the front of the following vehicle. As specified above, the leading vehicle and the trailing vehicle have a specific configuration given their particular positions in the convoy.

Returning to FIG. 4, after the step (402) of configuring the frequencies, the method passes to a step (404) of discovering the immediate neighbors. For the context of the invention, is considered to be an immediate neighbor of a vehicle A, a vehicle B which follows it and/or which immediately precedes it in the convoy. The step of discovery of immediate neighbors aims to establish a V2V communication of each vehicle with its immediate neighbor(s).

In an embodiment based on IEEE 802.11-OCB, the method initiates the neighbor discovery protocol by generating ICMPv6 type RA messages, which allows each vehicle (i.e. by the on-board connectivity device) to announce its presence and its address space by its own IPv6 prefix. The neighbor discovery protocol also makes it possible to process received RA messages. FIG. 4 illustrates by step (406), the reception of RA messages by a vehicle. Thus, if a vehicle receives an RA message (YES branch, step 406), signifying that it has an immediate neighbor, the method in a following step (408), makes it possible to check whether the IPv6 prefix of the received RA message is already present. in a vehicle routing table that will contain the route(s) to reach the immediate neighbors.

If the prefix is already present in the routing table, signifying that the vehicle sending the message RA is already known as an immediate neighbor by the receiver vehicle, the method ends. If the prefix is not present in the routing table of the recipient vehicle, the method makes it possible to add it to the table (410) and to continue with the step of receiving a new RA message (406). An entry in a vehicle's routing table includes the prefix received from the immediate neighbor, the LL address of the next hop to reach that prefix, and the name of the exit interface.

When no RA message is received (NO branch, step 406), the method ends.

At the end of the process, each vehicle is configured to reach only and directly its immediate neighbour(s), its routing table containing the appropriate route(s) for the join. So :
-The leading vehicle is able to communicate only with the lambda vehicle which follows it, since it only knows the prefix of the latter.
- A normal vehicle is able to communicate with both the vehicle following it and the one preceding it, because it has learned the two prefixes through its two active interfaces.
-The tail vehicle is able to communicate only with the lambda vehicle in front of it, since it only knows the prefix of the latter.

In one embodiment, the "TYPE1 and TYPE2" RA messages are used for the discovery of immediate neighbors.

Advantageously, once the configuration of each vehicle has been established, and its routing table filled, the device of the invention makes it possible to establish V2V communication throughout the convoy by a route propagation method, so that the vehicle head (i.e. the on-board computer) can communicate with any vehicle in the convoy (i.e. with an on-board computer in each vehicle), regardless of its position in the convoy.

This phase is triggered on a communication box of a lambda vehicle when its two IEEE 802.11-OCB interfaces are active and it has learned at least two new routes via these immediate neighbors. In one embodiment, TYPE1 and TYPE3 of RA messages are sent.

Each communication box of a lambda vehicle propagates the routes it learns from its immediate neighbors via its front and rear IEEE 802.11-OCB interfaces. Thus, for a convoy of N vehicles, each vehicle must have N-1 routes in its routing table to be able to reach all the vehicles in the convoy. The route propagation process is done iteratively.

FIG. 6 illustrates the number of iterations necessary for the propagation of routes for different convoys ranging from two vehicles to N vehicles. Thus, the person skilled in the art understands that for a convoy composed of:
-2 vehicles (V1, V2): there is no need for propagation, and therefore no iteration;
-3 vehicles (V1 to V3): 1 iteration is needed;
-4 vehicles (V1 to V4): 2 iterations are needed;
-5 vehicles (V1 to V5): 3 iterations are needed;
-N vehicles (V1 to VN): N-2 iterations are needed.

Indeed in a more detailed way, for the example of a convoy of 5 vehicles, by the process of discovery of immediate neighbors:
-V1 has learned a single route, to V2;
-V2 has learned two routes, to V1 and V3;
-V3 has learned two routes, to V2 and V4;
-V4 has learned two routes, to V3 and V5; And
-V5 has learned a single route, to V4.

Then, by the first iteration for propagation:
-V1 has learned two routes, to V2 and to V3 via V2;
-V2 has learned three routes, to V1 and V3 and to V4 via V3;
-V3 has learned all four routes, to V2 and V4, to V1 via V2 and to V3 via V4;
-V4 has learned three routes, to V3 and V5 and to V2 via V3; And
-V5 has learned two routes, to V4 and to V3 via V4.

Then, by the second iteration for propagation:
-V1 has learned three routes, to V2 and to V3 and V4 via V2;
-V2 has learned all four routes, to V1 and V3 and to V4 and V5 via V3;
-V3 has the same routes as the first iteration;
-V4 has learned all four routes, to V3 and V5 and to V1 and V2 via V3; And
-V5 has learned three routes, to V4 and to V3 and V2 via V4.

And by the third iteration for propagation:
-V1 has learned all four routes, to V2 and to V3, V4 and V5 via V2;
-V2 has the same routes as the second iteration;
-V3 has the same routes as the first and second iterations;
-V4 has the same routes as the second iteration; And
-V5 has learned all four routes, to V4 and to V3, V2 and V1 via V4.

Those skilled in the art understand the simplification of language used when speaking of "Vehicle" but that it is in fact the process implemented on the device of the invention, in particular on the communication box embedded in each vehicle which communicates through these antennas connected to the interfaces configured in IEEE 802.11-OCB.

Thus for a convoy of N vehicles (N>2), the route propagation is done after N-2 iterations, N-2 being the maximum number of iterations after which the lead vehicle and the tail vehicle have learned all the roads.

At the end of the route propagation process, in an embodiment based on IEEE 802.11-OCB, all the vehicles in the convoy can communicate in V2V in IPv6, regardless of their position in the convoy. The leading vehicle can send information directly to the trailing vehicle in a completely transparent way.

In one embodiment, the method can perform the discovery of immediate neighbors and relay the information sent by the lead vehicle from near-by-near. However, this variant introduces a lot of latency into the operation of the system, which is undesirable.

FIG. 7a illustrates the steps (700) for setting up communication within a platoon, going from the configuration of the frequencies to the propagation of the route for a lambda vehicle having a preceding vehicle and a following vehicle. After an optional step of resetting (702) or reinitializing the configuration of the vehicle, the method passes to a step (704) of propagation initialization for lambda vehicle. The next step (706) consists of receiving an RA message, on the local link of the front interface (I_av) or on the local link of the rear interface (I_ar).

In a next step (708), the method makes it possible to check whether the prefix indicated as PIO in the message received at the front interface or at the rear interface is different from the prefix of the recipient vehicle. If the PIO is identical to the prefix of the recipient vehicle, the process loops back to the start. If the PIO received is different from the prefix of the recipient vehicle, the method makes it possible to add (710) a new entry in the routing table of the lambda vehicle to define the transmitting vehicle as part of the route. In a next step (712), the method makes it possible to check whether there are in the routing table at least two prefixes different from that of the lambda vehicle. If so, the method allows (714) to continue the route propagation to the immediate neighbors with the appropriate RIO information. If not, the process waits to have to check the prefix of a new entry in the routing table.

Figures 7b and 7c illustrate the steps for setting up communication within a platoon, from frequency configuration to route propagation for a lead vehicle (Fig. 7b) and a tail vehicle (Fig. 7c). The different steps with respect to the method for a lambda vehicle (FIG. 7a) are step 704 which launches the propagation protocol respectively for a lead vehicle or for a tail vehicle and step 706 corresponding to the reception of an RA message, which is respectively received on the rear interface (I_ar) for the lead vehicle, or on the front interface (I-av) for the tail vehicle. The process continues with a step of prefix verification (708) and addition (710) or not of a new entry in the routing table, respectively of the lead vehicle or the tail vehicle. Then the process stops.

The optional reset step (702) makes it possible to manage situations where at any time a leading vehicle can become a trailing vehicle and vice versa. Similarly, a lambda vehicle can be redefined as a lead or tail vehicle.

A concrete implementation for a platooning of three vehicles was carried out under the following conditions. An OpenWrt OS image was generated for a blank electronics board, the OS kernel was modified to support OCB and matching frequencies, and some configuration and/or additions of software modules and drivers necessary for the operation and use of the card in the kernel of the operating system have been made. Since the OpenWrt operating system no longer supports the RADVD software natively, it was necessary to cross-compile on a computer (since the architectures are not identical) and to repatriate the generated binary into the already functional card in order to make it possible to send RA messages on interfaces configured to support IEEE 802.11-OCB.

Once the map is prepared, the vehicles are identified (VFLEX1, VFLEX2, VFLEX3) and an operator decides the order in which the platooning will take place with a lead vehicle (“Leader”) which is at the head of the platooning, a first follower vehicle (“First Follower”) which immediately follows the leader, and a second follower vehicle (“Second Follower”) which is at the tail of the platooning. Each communication box is identified (VBOARD1, VBOARD2, VBOARD3), the indices corresponding to those assigned to the vehicle. For example, VBOARD1 is in VFLEX1. Two frequencies (5880 MHz and 5890 MHz) are allocated for platooning three vehicles: the 5880 MHz frequency for communication between the rear interface of the Leader vehicle and the front interface of the First Follower, and the 5890 MHz frequency for communication between the rear interface of the First Follower and the front interface of the Second Follower.

After resetting the communication devices of each vehicle, the operator defines the role of each vehicle. For example, VFLEX3 is defined as "Leader", VFLEX2 is defined as "First Follower", and VLFEX1 is defined as "Second Follower". The operator runs a role definition script on each vehicle's on-board computer. This triggers the execution of corresponding scripts in each communication box.

Thus defining VFLEX3 as “Leader” triggers the execution of a script (for example “./leader.sh”) in the VBOARD3 device. The OCB interface connected to the antenna placed at the front of the VFLEX3 is then deactivated and the OCB interface connected to the antenna placed at the rear of the vehicle is configured in OCB at the 5880 MHz frequency.

Similarly, setting VFLEX2 as “First Follower” triggers execution of a script (e.g. “./first_follower.sh”) in VBOARD2. This configures the interface connected to the antenna placed at the front of the VFLEX2 in OCB at the 5880 MHz frequency and that connected to the antenna placed at the rear at the 5890 MHz frequency; ODHCP6C and RADVD being already in operation.

Similarly, setting VFLEX1 as "Second Follower" triggers the execution of a script (e.g. "./second_follower.sh") in VBOARD1. This deactivates the OCB interface connected to the antenna placed at the rear of the VFLEX1 and configures that connected to the antenna placed at the front of the vehicle in OCB at the 5890 MHz frequency.

Thus, after a few seconds (approximately 20 seconds) the communication boxes of VFLEX vehicles can communicate two by two in V2V. A latency of about 1.2 to 1.5 ms was measured between two immediate neighbors.

The route propagation step is triggered in the VBOARD2 as soon as it has learned the prefixes of these immediate neighbors. The trigger conditions being that the vehicle is placed between two vehicles in the convoy. This implies that the VBOARD2 has its two OCB interfaces connected to the active antennas placed at the front and rear of the vehicle, and that the VBOARD2 has learned at least two prefixes, different from its own prefix. Route propagation triggers the execution of a script (for example "./route_propagation.sh") which checks the two previous conditions then announces the routes learned via its two OCB interfaces (for example by restarting software such as " radvd” (Router Advertisement Deamon) which allows to send “Router Advertisements (RA)” which contain “Prefix Information Option” (PIO) and “Route Information Option” (RIO)).

Advantageously, the inventors noted a latency of the order of 3 ms between the tail vehicle and the lead vehicle, knowing that the vehicles tolerate up to 50 ms of latency in the communication exchanges.

Thus, the invention allows a vehicle to be equipped with two separate antennas, each of these antennas being connected to a separate communication interface. An antenna is located at the front of the vehicle (in the front bumper for example) and an antenna at the rear (in the rear bumper for example). Each of the communication interfaces is configured in a separate communication channel and IP communication protocols are used.

The advantages of the present invention compared to existing solutions are essentially:
-the use of IP protocols on the interfaces which allows the establishment of a multi-hop IP network between all the cars, without scale limit. The length of a convoy can go well beyond 1km and IP messages are propagated from hop to hop over unlimited distances.
-the use of separate channels at the front and at the rear of the vehicle which avoids the creation of interference due to the repetition of messages. The messages are not repeated by the link layer but are routed by the IP "forwarding" process by the network layer.
-the establishment of a communication in a distinct channel by a distinct interface between two vehicles makes it possible to guarantee good quality in transmission and in reception for lower power levels, since the propagation distances are short between two immediate neighboring vehicles .

Claims (15)

A computer-implemented method for configuring vehicle-to-vehicle communication, the method comprising the following steps:
-defining a role for each vehicle of a plurality of vehicles, the roles including a lead vehicle role, a tail vehicle role and at least one lambda vehicle role where a lambda vehicle is a vehicle positioned between the head and tail vehicle;
allocating to each of the leading and trailing vehicles at least one vehicle-to-vehicle communication frequency, and allocating to said at least one lambda vehicle at least two different vehicle-to-vehicle communication frequencies, a first frequency for communicating with a preceding vehicle and a second frequency for communicating with a following vehicle;
- Carry out for each vehicle an immediate neighbor discovery protocol, an immediate neighbor of a vehicle being a vehicle which precedes it and/or a vehicle which immediately follows it; And
- configure each vehicle to reach only its and/or its immediate neighbor(s) with the assigned vehicle-to-vehicle communication frequencies. The method according to claim 1 wherein the role definition step is done from a centralized server by activating remote role definition scripts. The method of claim 1 or 2 wherein the step of allocating vehicle-to-vehicle communication frequencies comprises allocating to a lay vehicle a first frequency for communications with a preceding vehicle, and a second frequency for communications with a following vehicle. The method of any of claims 1 to 3 wherein the step of assigning vehicle-to-vehicle communication frequencies includes assigning the lead vehicle the same frequency as one of the two frequencies of a vehicle lambda and assigning the tail vehicle the same frequency as one of the two frequencies of a lambda vehicle. The method according to any one of claims 1 to 4 in which the assigned frequencies are in the 5.9 GHz frequency band called ITS. The method according to any one of claims 1 to 5 wherein the step of discovering immediate neighbors consists for each vehicle in generating messages to announce its presence and its address space. The method according to any one of claims 1 to 6 wherein the step of configuring each vehicle consists for each vehicle of receiving and processing messages received from other vehicles. The method according to any one of claims 1 to 7 in which the immediate neighbor discovery step is based on the "Neighbor Discovery Protocol" protocol and consists in generating ICMPv6 "Router Advertisement" messages which allow each vehicle to announce its IPv6 prefix, and the configuration step of each vehicle consists in receiving and processing ICMPv6 “Router Advertisement” messages received from other vehicles. The method according to any of claims 1 to 8 further comprising a step of road propagation to immediate neighbors to establish vehicle-to-vehicle communication for the plurality of vehicles and to enable each vehicle to communicate with all others through a routing protocol. A computer program product, said computer program comprising non-transitory code instructions for carrying out the steps of the method according to any one of claims 1 to 9, when said program is executed on a computer. A device for configuring vehicle-to-vehicle communication between a plurality of vehicles, the device comprising means for implementing the steps of the method according to any one of claims 1 to 9. The device according to claim 11 in which each vehicle carries a communication box comprising:
- two wireless vehicle-to-vehicle communication interfaces (102, 104);
-a vehicle role definition module (106) configured to define the role of the vehicle, the role being able to be a lead vehicle role, a tail vehicle role or a lambda vehicle role, a lambda vehicle being a vehicle positioned between a lead vehicle and a tail vehicle;
-a frequency configuration module (108) configured to assign to at least one interface of the on-board communication box in a leading or trailing vehicle, at least one vehicle-to-vehicle communication frequency, or to assign to each interface communication from the communication box on board a lambda vehicle, at least two different vehicle-to-vehicle communication frequencies, a first frequency for communicating with a vehicle preceding it and a second frequency for communicating with a vehicle following it; And
-a message processing module (110) configured to perform an immediate neighbor discovery protocol for the vehicle, an immediate neighbor of a vehicle being a vehicle preceding it and/or a vehicle immediately following it, and to configure the vehicle so as to reach only its and/or its immediate neighbour(s) with the assigned vehicle-to-vehicle communication frequency(ies). The device according to claim 12 wherein the two wireless vehicle-to-vehicle communication interfaces (102, 104) are configurable according to IEEE 802.11-OCB technology. The device of claim 12 or 13 further comprising at least one antenna (308-ar, 308-av) coupled to at least one wireless vehicle-to-vehicle communication interface (102, 104). A vehicle comprising a communication box according to any one of claims 11 to 13.