WO2007026279A1

WO2007026279A1 - Method for transmitting messages between vehicles communicating via an inter-vehicle network

Info

Publication number: WO2007026279A1
Application number: PCT/IB2006/052914
Authority: WO
Inventors: Hans-Jürgen Reumerman; Tobias Helbig
Original assignee: Philips Intellectual Property & Standards Gmbh; Koninklijke Philips Electronics N. V.
Priority date: 2005-08-31
Filing date: 2006-08-23
Publication date: 2007-03-08

Abstract

The invention relates to a vehicle having at least two antennas (AF, AB, AL, AR), the antennas being provided for transceiving messages (20) from /to other antennas (AF, AB, AL, AR) of other vehicles (A-G) or objects (H), wherein a message transmitted by an antenna includes an information element (21) of the transmitting antenna, a receiving unit (15) is provided for forwarding received messages depending on the information element (21) included in the received message (20). Further, it relates to an inter-vehicle network including a plurality of vehicles (A -G) as described above and to a method for transmitting messages (20) between vehicles (A-G) communicating via an inter-vehicle network, wherein a vehicle (A-G)) having at least two antennas (AB, AF, AR AL) for transceiving of messages (20) from /to other vehicles (A-G) or objects (H), the method comprises the steps of: providing an information element (21) in a message (20) characterizing the transmit antenna ID and/ or the dissemination strategy; forwarding a received message (20) depending on the receiving antenna and/or the information element (21).

Description

Method for transmitting messages between vehicles communicating via an inter- vehicle Network

The invention relates to a vehicle having at least two antennas for transceiving messages from two other antennas of other vehicles or objects. The invention further relates to a inter- vehicle network including a plurality of such vehicles. Further, it relates to a method for transmitting messages between vehicles communicating via an inter- vehicle network.

In the field of car-to-car communication there are sensor-equipped cars which interact cooperatively to avoid collisions. For example, cars maybe warned when entering an intersection that should be kept free for a fire truck. Likewise, car-to-car communication is considered crucial to avoid collisions during lane change or merge maneuvers and for reporting of invisible obstacles, possibly talking to obscured or shadowed objects.

An inter- vehicle communication is based on an ad-hoc wireless network because it is flexible and fully distributed in the sense that such networks do not rely on an essential authority to coordinate transmissions in a network. In vehicular ad-hoc networks users or mobile nodes or simply vehicles share a single broadcast channel typically via a random access protocol. Such networks are attractive because they typically have minimal deployment costs. Further, they can operate in unlicensed bands and allow the dynamically increasing capacity and a coverage as more users are added to a network. Further, they alleviate or eliminate the need for centralized network administration.

One of the main research areas in vehicle communication is a design of restrictive flooding algorithm where vehicles can disseminate messages without actually knowing the network or MAC idea of the destination node, often being not even interested in addressing a single node. For example, a vehicle whose sensors have picked up a potential hazard situation once has to inform all vehicles in a certain geographic area like a particular highway or a intersection. This vehicle will send out a message with a certain time to live and range to live value, ensuring that the zone of relevance is covered. Due to initially low equipment penetration of communication systems the communication range may occasionally be limited such that no other vehicle is in reach. This demands either smart re-broadcasting techniques or some sort of multi-hop forwarding, meaning that the message is physically picked up from passing vehicles and transported until other equipped vehicles are within communication reach and available to continue message dissemination.

By using standard omni- directional antennas a message flooding e.g. backwards along a specific road would be possible by a) keeping an up-to-date list of neighbor vehicles (based on regular beacons or hello messages) and their associated MAC address which must be unique for privacy reasons may be changed over time to avoid the tracking of vehicles; b) comparing the absolute position of the vehicle with the own position and calculating the neighbors relative positions as: behind, left, front, 3O⁰NE etc.; c) addressing the vehicle in terms of desired direction (e.g. "behind") by checking the neighbor list for any available vehicles and using the associated MAC address; d) sending the message to the identified destination, in this example, to the car behind.

Following the reception of this message a vehicle needs to determine whether or not to continue transmitting it to the car behind and so forth. The message therefore has to pass the application layer of a processor and thereby suffers the CPU processing delay.

Therefore, it is an object of the present invention to provide a vehicle and an inter- vehicle network and further a method for transmitting messages in an easy way without any processing delays, which are caused by passing higher application layers. It is a further object to provide a vehicle and a method being able to communicate efficiently without flooding the communication medium.

The object is solved by the features of the independent claims. The invention is based on a thought that antennas are mounted at least on two sides of a vehicle. If the message contains its source in an information element it is possible during receiving such message to evaluate the information element included in the message and to forward the message depending on the information element without passing the message to the application layer.

So it is not required to keep an up-to-date list of neighbor vehicles and to compare the absolute position of the vehicle with the own position. Further, it is not required to address vehicles. By use of the inventive method and the inventive vehicle it is only required to send out the message in this forwarding direction which is derived from the information element.

It is, in particular, advantageous to include a transmit antenna ID element and an dissemination strategy element in the information element of the message. By this, it is possible within the receiving unit of the receiving vehicle to recognize the source of the message and also to recognize the dissemination strategy to decide in which direction the message needs to be forwarded without passing the message to the application layer.

By addressing anonymous vehicles by means of sectorized antennas it is not necessary to know which vehicles are in the neighborhood.

By means of sectorized antennas, messages that are received by the front looking antenna are automatically passed to the backward looking antenna and so rapidly achieve applications like the electronic break-like etc. This is possible by means of the information element contained in the message header that can be evaluated in hardware without passing the application layer and thereby causing CPU processing delays. In a further embodiment of the invention it is advantageous to mount at least four sectorized antennas on the vehicle. One antenna is mounted at the front side, one at the back side, one at the left side and the fourth antenna is mounted at the right side of the vehicle. By mounting antennas at the four sides of a vehicle it is possible to forward messages in each direction. In particular, the receiving unit is provided with a switching unit, which evaluates a message to decide where the message comes from and/or for evaluating the intended direction of the message. Since the information where the message comes from and the dissemination strategy is included in the message header it is very easy to recognize this information element. So the decision how to handle the message is based on these information.

The object of the invention is also solved by an inter- vehicle network including a plurality of vehicles as described above.

Further, the object is solved by a method for transmitting messages between vehicles communicating via an inter- vehicle network, wherein each vehicle having at least two antennas for transceiving messages from/to other vehicles or objects. The method comprises the steps of: providing an information element in a message characterizing the transmit antenna ID and/or the dissemination strategy, forwarding a received message depending on its information element.

The invention is described in detail below with reference to the accompanying schematic drawings, wherein

Fig. 1 shows a schematic illustration of the vehicle according to the present invention; Fig. 2a shows a schematic illustration of the message according to the present invention; Fig. 2b shows a header according to the present invention;

Fig. 3 shows a switching table according to the present invention;

Fig. 4 shows a schematic illustration of a plurality of vehicles communicating according to the present invention; Figs. 5a-5c show different scenarios according to the present invention.

It is referred to Fig. 1, in which a schematic illustration of a vehicle according to the present invention is illustrated. The vehicle includes a receiving unit 15. The receiving unit 15 is coupled to four antennas AF, AB, AL and AR. These antennas are mounted at the vehicle at the front, the back, the left and the right side.

To increase the clarity the receiving side and the transmitting sides are illustrated in fig. 1 separately, whereas it is obvious that the antennas are each capable of receiving and transmitting.

The receiving unit 15 includes evaluation units 11, 12, 13 and 14 for evaluating the messages received by one of the antennas AF, AB, AL and AR. The evaluation units are coupled to a switching table 17. The switching table 17 is illustrated exemplary in Fig. 3. Further, the evaluation units 11-14 are connected to the switching unit 16. The switching unit 16 includes five outputs A₁-A₅. Output A₁ is coupled to the antenna AF for transmitting a message by use of the front side antenna AF. The output A₂ is coupled to the antenna AB mounted at the back of the vehicle. The output A₃ is coupled to the antenna AL at the left side, wherein the output A₄ is coupled to the antenna AR at the right side of the vehicle. Further, the output A₅ of the switching unit 16 is connected with an interface processor 18 of a CPU, which is not illustrated. The CPU may be included in a controlling unit of the vehicle. Further, it is possible that the interface processor 18 is coupled to the navigation system or to a communication system of the vehicle. The switching unit 16 is realized as a cross-bar matrix which maybe include buffering units for the case of two messages to be send to one output A₁-A₅ simultaneously.

The Fig's. 2a and 2b illustrate a message 20 including a message header and the data part 22. An information element 21 is included in the header of the message 20. In Fig. 2b the information element 21 is illustrated, wherein it is divided in a first part 23, illustrating the transmit antenna ID element 23 and a second part including the dissemination strategy element 24.

The switching table 17 as illustrated in Fig. 3 includes the assignment between inputs and outputs in respect to the antennas. A message received with the front side antenna AF is forwarded to the output A₂ of the antenna AB at the back. A message received with the antenna AB at the back is forwarded to the output A₁ coupled to the front side antenna AF. A message received with the antenna AL at the left side is coupled to the output A₄ at the right side of the vehicle. The message received with the right side antenna AR is on the one hand forwarded to the output A₃ to the left side antenna AL and further to the output A₅ for forwarding the right side received message to the interface unit 18 for forwarding the received message to a CPU of the vehicle.

In the following the invention will be described on the example illustrated in Fig. 4. Fig. 4 depicts a road scenario comprising vehicles A-G. Further, there is an object H arranged near the road for providing, for instance, traffic information or updates of the road maps used in a navigation system. In the depicted scenario the vehicle A identifies by means of its on-board sensors a hazard and forwards this information to the vehicle B driving in front of the vehicle A. During encounter with vehicle C and D vehicle B will hand over the information of the hazard to other vehicles C and D in the surrounding.

The vehicle A may receive the information of the hazard by use of not illustrated on-board sensors. However, it is also possible but not illustrated that one of the vehicles F or G transmits a message including the information of a hazard. This message is then picked up by the passing vehicle A. Due to the fact that the message includes the transmitting antenna ID 23 and the element 24 for the dissemination strategy, certain forwarding strategies maybe enabled in hardware, in particular, in the switching table 17 without the time consuming process of transferring the message to the on-board telematics or application processors.

According to the invention the receiving unit 15 can, on the one hand, evaluate the direction where the message comes from and, on the other hand, recognize the intended direction of the message both contained in the information element 21 as explained above. The message including the information of the hazard between the vehicles F and G is also forwarded to the vehicle E. The vehicle E receives the message including the information of the hazard with its front side antenna AF and with its left side antenna AL. The message transmitted by the vehicle A includes both the transmit antenna ID element 23 and the dissemination strategy element 24. In case of a hazard, dissemination strategy element is set to forward this message to all directions for a predetermined time or area.

If the vehicle A receives the message including the dissemination strategy element indicating that each receiving vehicle should receive this message it will be forwarded also to the application processors of the vehicle to initiate a warning of the driver or to influence the navigation system for finding alternative routes.

Fig. 5a illustrates three vehicles A-C. Example Fig. 5a illustrates a lane change warning assistant relying on information that is laterally exchanged between vehicles A and B. It is important to note that the warning message is not forwarded to any of the other unaffected vehicles such as vehicle C, to avoid driver distraction or inappropriate reaction to an irrelevant warning.

In the same way Fig. 5b illustrates an emergency break warning confined to one single lane, sometimes also called extended electronic break lights. This can be realized by only the front and back antennas AF and AB transmitting respective received warning messages from the vehicle A driving in front of the vehicle B without transmitting the message to vehicle C.

Fig. 5c illustrates a scenario for a message forwarding. For further applications it is possible to set up a message, which should be coupled to a public switched telephone network PSTN or a wireless access network. If no base station or node is in the transmission area, it is possible to transmit the message generated in vehicle A to the vehicle C in front of the vehicle A and to vehicle B on the opposite lane. If one of the vehicles C or B passes a base station or node the message is coupled into the PSTN or other suited network to be forwarded to the receiver. In such case the object H as illustrated in fig.4 may be used for transmitting the message into a PSTN or other suited network.

While, the intention is to enable smart dissemination algorithms by means of a special message header flags, which are denoted as information elements as shown in Fig. 2a and Fig. 2b it is possible to define a default behavior. For instance, every message received from the back side antenna AB can be forwarded to the front side antenna AF and left side antenna AL, each message received from the right side antenna AR, may be forwarded to the left side antenna AL simply by internally enhancing the received message with the information about which locally installed antenna picked up the message.

According to one embodiment of the invention each vehicle contains at least 4 or more transmit/receive antennas, labeled front, right, left or back (AF, AR, AL, AB). Each transmitted message is labeled with the identification ID 23 of the antenna used for transmission, i.e. a message sent by the front antenna contains a label "F". This label can either be a special preamble or an appended header field to be evaluated by each receiving unit 15. It is also possible to define combinations of these labels for the case where one message is multicasted on several of the four antennas. However not all combinations are useful, for instance "L+R", could be excluded from the list of possible combinations. Further possible combination may be "forward" and "left" (F+L, assuming right-side driving) or "omni" for all antennas except the incoming one.

The header evaluation units 11-14 within each receiving unit 15 not only extracts information on where to switch the incoming received message, but also can apply plausibility checks and trigger warnings to the driver via the user interface processor 18. If for instance a message labeled "R" or "F" is received by the front receive antenna AF, there is a risk for potential collision. In such a case the message is switched to the user interface 18 and to the processor for subsequent interpretation and driver warning. The header label evaluation units 11-14 may also update the information element to reflect the local transmit antenna that is used for forwarding the message.

Optionally, the switching table 17 can be dynamically influenced by the road environment, inferred by the presence of vehicles as indicated from either of the 4 antennas. For example an "F" labeled message received from the back antenna AB, would normally be sent to front only, but the presence of communication opportunities at right and left could be used to multicast the message to F, L, R simultaneously to increase the coverage range of the message.

By using the invention it is possible to distribute message in an very easy way without flooding the medium and without causing high latencies due to the application layer processing.

Claims

CLAIMS:

1. Vehicle having at least two antennas (AF, AB , AL, AR), the antennas being provided for transceiving messages (20) from /to other antennas (AF, AB, AL, AR) of other vehicles (A-G) or objects (H), wherein a message transmitted by an antenna includes an information element (21) of the transmitting antenna, a receiving unit (15) is provided for forwarding received messages depending on the receiving antenna and/or the information element (21) included in the received message (20).

2. Vehicle as claimed in claim 1, wherein the information element (21) included in the message (20) includes a transmit antenna ID element (23) and a dissemination strategy element (24).

3. Vehicle as claimed in claim lor 2, wherein the antennas (AF, AB, AL, AR) being sectorized antennas having no addressing of the destination for the message to be sent.

4. Vehicle as claimed in one of the claims 1 to 3, wherein a vehicle comprises at least four sectorized antennas (AF, AB, AL, AR) being mounted at the front (AF), back (AB), left (AL) and right side (AR) of the vehicle.

5. Vehicle as claimed in one of the claims 1 to 4, wherein the receiving unit

(15) includes at least one evaluating unit (11, 12, 13, 14) for evaluating where the message comes from and/or for evaluating the intended direction of the message.

6. Vehicle as claimed in one of the claims 1 to 5, wherein the evaluating unit (11,12, 13, 14) is coupled to a switching table (17), wherein the switching table stores how to handle received messages and controls the forwarding of messages to one or more of the transmit antennas depending on the input antenna and the information element (21) included in the message header.

7. Vehicle as claimed in one of the claims 1 to 6, wherein the evaluating unit

(11,12, 13, 14) is coupled to switching unit (16), wherein the switching unit (16) switches the messages to outputs (A1-A5) of the switching unit (16) depending on the evaluation of the evaluation unit (11, 12, 13, 14), a user interface processor (18) is coupled to the receiving unit (15) provided for controlling the communication with the vehicle.

8. Inter- vehicle network including a plurality of vehicles (A -G) as claimed in the claims 1-7.

9. Method for transmitting messages (20) between vehicles (A-G) communicating via an inter vehicle network, wherein a vehicle (A-G)) having at least two antennas (AB, AF, AR AL) for transceiving of messages (20) from /to other vehicles (A-G) or objects (H), the method comprises the steps of: providing an information element (21) in a message (20) characterizing the transmit antenna ID and/ or the dissemination strategy, forwarding a received message (20) depending on the receiving antenna and/or the information element (21).