Patent Publication Number: US-2012034876-A1

Title: Method and apparatus for vehicle-to-vehicle communication

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2010-174806, filed Aug. 3, 2010, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a vehicle-to-vehicle communication technique that has a security function. 
     BACKGROUND 
     In recent years, it has been proposed that a vehicle-to-vehicle communication technique should be developed, which uses electromagnetic waves in, for example, the 700-MHz or 5.8-GHz band, thereby achieving wireless communication between the apparatuses mounted in vehicles (hereinafter referred to “vehicle-mounted apparatuses”). The vehicle-to-vehicle communication enables the driver of any vehicle traveling on a road to obtain safety information, safety driving guidance and traffic safety data, via the vehicle-mounted apparatuses, from the vehicle-mounted apparatuses of the other vehicles traveling on the road. 
     More specifically, the vehicle-to-vehicle communication can give traffic information to the driver of a vehicle, for example at an intersection or in the shade of tall buildings where he or she cannot see ahead well. In addition, the communication enables the driver of any vehicle to receive, from the vehicle traveling immediately in front, various event data items, such as brake data, turn data and speed data. From these event data items, the driver of the vehicle can recognize the traffic state (including congestion) in front on the road. 
     In the vehicle-to-vehicle communication, an authentication process must be performed in order to accomplish a security function so that the vehicle-mounted apparatus of each vehicle may exchange the safety information, safety driving guidance and traffic safety data with only the authenticated vehicle-mounted apparatuses, thereby to prevent communication with the vehicle-mounted apparatuses of unidentified or inappropriate vehicles. 
     In practice, however, the authentication process may be difficult to perform through the wireless communication between the vehicle-mounted apparatuses. This is because immergence information must be transmitted at, for example, an intersection or on a congested road, and the communication traffic, including the communication for achieving the authentication process, should therefore be restricted as much as possible, because. 
     To be more specific, the time overhead of any vehicle-mounted apparatus will increase if the apparatus performs authentication process every time it receives immergence information, thereby to check the authenticity of the apparatus that has transmitted the information. Moreover, the authentication process is practically impossible with respect to a vehicle that is coming to and going from, for example, an intersection, within a short time. Particularly in a traffic jam, the vehicle-mounted apparatus of each vehicle needs to authenticate the vehicle-mounted apparatus of several other vehicles traveling nearby. Further, a single authentication process cannot predict when the vehicle from which the immergence information has been received will travel away. In view of this, a vehicle-to-vehicle communication technique is demanded, which can efficiently perform an authentication process for achieving a security function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram explaining the configuration of a system according to an embodiment; 
         FIG. 2  is a diagram explaining the effect of vehicle-to-vehicle communication according to the embodiment; 
         FIG. 3  is a diagram explaining the relation the vehicle-to-vehicle communication according to the embodiment has with a traffic state; 
         FIG. 4  is a diagram explaining how the system according to the embodiment operates; 
         FIG. 5  is a flowchart explaining how a roadside apparatus according to the embodiment operates; 
         FIG. 6  is a flowchart explaining how a vehicle-mounted apparatus according to the embodiment operates; 
         FIG. 7  is a flowchart explaining how the vehicle-mounted apparatus according to the embodiment transmits information; 
         FIG. 8  is a flowchart explaining how the vehicle-mounted apparatus according to the embodiment receives information; 
         FIG. 9  is a timing chart explaining how a system according to the embodiment operates; 
         FIG. 10  is a flowchart explaining how a vehicle-mounted apparatus according to another embodiment operates; and 
         FIG. 11  is a flowchart explaining how a vehicle-mounted apparatus according to still another embodiment operates. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a vehicle-mounted apparatus includes a wireless communication unit, an authentication data acquisition unit, a data transmitting/receiving unit, and a controller. The authentication data acquisition unit is configured to perform an authentication process with a roadside apparatus, through the wireless communication unit, and thereby to acquire authentication data showing that the apparatus is authenticated in a specified area of a road. The data transmitting/receiving unit is configured to transmit and receive information containing the authentication data, to and from the vehicle-mounted apparatus mounted in any other vehicle. The controller is configured to control the data transmitting/receiving unit in accordance with the authentication data, causing the data transmitting/receiving unit to transmit and receive data other than the authentication data. 
     Embodiments will be described with reference to the accompanying drawings. 
     [Configuration of the System] 
     A system according to this embodiment is a data communication system composed mainly of vehicle-mounted apparatuses  10 A and  10 B and a roadside apparatus  20 . The apparatuses  10 A and  10 B are mounted in two vehicles, respectively. For convenience, the apparatus  10 B mounted in one vehicle shall be regarded as communication partner to the apparatus  10 A mounted in the other vehicle. The vehicle-mounted apparatuses  10 A and  10 B and the roadside apparatus  20  have wireless communication devices  11 A,  11 B and  21 , respectively. Each of these wireless communication devices includes an antenna configured to received and transmit electric waves. The wireless communication devices  11 A,  11 B and  21  are designed to perform data communication in, for example, a narrowband wireless communication scheme known as Dedicated Short-Range Communication (DSRC). To be more specific, these wireless communication devices are used in vehicle-to-vehicle communication (VTVC) or road-to-vehicle communication (RTVC). 
     The vehicle-mounted apparatus  10 A has a global positioning system (GPS) device  12 A, a controller  13 A, and a memory  14 A. Similarly, the vehicle-mounted apparatus  10 B has a Global Positioning System (GPS) device  12 B, a controller  13 B, and a memory  14 B. The GPS devices  12 A and  12 B output position data items representing the present positions of the two vehicles in which the apparatuses  10 A and  10 B are mounted. The controllers  13 A and  13 B are constituted by a computer. Each of the controllers  13 A and  13 B can process information including authentication data, position data and event data (described later) and can control the other components of the vehicle-mounted apparatus. The memories  14 A and  14 B are controlled by the controllers  13 A and  13 B, respectively, and store the authentication data, position data and event data. 
     The controllers  13 A and  13 B control displays  30 A and  30 B that are provided outside the vehicle-mounted apparatuses  10 A and  10 B, respectively. That is, the controllers  13 A and  13 B cause the displays  30 A and  30 B to display the position data output from the GPS devices  12 A and  12 B and the event data received by the wireless communication devices  11 A and  11 B. 
     The vehicle-mounted apparatuses  10 A and  10 B may have not only the wireless communication devices  11 A and  11 B of DSRC type, respectively, but also wireless communication devices using infrared beams and performing data communication with each other. 
     [Operation of the System] 
     How the system according to the embodiment will be explained. 
     The system according to this embodiment is advantageous if used to achieve vehicle-to-vehicle communication at such an intersection  300  as shown in  FIG. 2  and  FIG. 3 , which is a special area on a road. Vehicles  100 A and  100 B may be traveling at the intersection  300  as shown in  FIG. 2 . The drivers of the vehicles  100 A and  100 B may not see each other&#39;s vehicle, because of the building  200  standing at a corner of the intersection  300 . In this case, the vehicle-to-vehicle communication between the vehicle-mounted apparatuses  10 A and  10 B can transmit to each other the information indicating that the vehicles  100 A and  100 B are approaching the intersection  300 . 
     As shown in  FIG. 3 , several vehicles  100 A to  100 F may be caught in a traffic jam at the intersection  300  and in an area around the intersection  300 . In this case, the system according to this embodiment can efficiently perform an authentication process between any two of the vehicles  100 A to  100 F. 
     How the system according to the embodiment operates will be explained in detail, with reference to  FIG. 4  to  FIG. 9 . 
     As shown in  FIG. 4 , roadside apparatuses  20  are installed at an intersection and in an area around the intersection. In  FIG. 4 , the roadside apparatuses  20  are not shown for convenience, and the wireless communication devices  21 A to  21 D incorporated in the respective roadside apparatuses  20 A are shown. Alternatively, only one roadside apparatus  20  is installed at, for example, a position near the intersection, and the wireless communication devices  21 A to  21 D may communicate with this roadside apparatus  20 . In either case, the wireless communication devices  21 A to  21 D perform road-to-vehicle communication (RTVC) by means of narrowband wireless communication, in limited areas  210 A to  210 D. 
     How an authentication process is performed to achieve the vehicle-to-vehicle communication (VTVC) between the roadside apparatus  20  and the vehicle-mounted apparatuses of the vehicles traveling will be explained with reference to the flowcharts of  FIGS. 5 and 6  and the timing chart of  FIG. 9 . Hereinafter, “S” designates any step shown in the flowcharts, and “T” designates any timing shown in the timing chart. 
     The roadside apparatus  20  starts communicating with, for example, with the vehicle-mounted apparatus  10 A of the vehicle  100 A, by using the wireless communication devices  21 A (S 1 , T 1 ). The roadside apparatus  20  then performs the authentication process in a prescribed sequence (S 2 , T 2 ). More precisely, the roadside apparatus  20  receives ID data from the vehicle-mounted apparatus  10 A, and determines whether the ID data is genuine (S 3 ). This embodiment is based on the assumption that the roadside apparatus  20  is authenticated because it can more easily acquire authenticity than each vehicle-mounted apparatus. The roadside apparatus  20  and any authenticated vehicle-mounted apparatus have apparatus authenticating function of a known type, and can therefore authenticate each other. (The apparatus authenticating function includes a function of managing the key data for authenticating the communication partner.) 
     The roadside apparatus  20  may determine that its communication partner, i.e., vehicle-mounted apparatus  10 A, is an authenticated one. Then, the roadside apparatus  20  issues authentication data (K) that is valid in a specified area and transmits this data to the vehicle-mounted apparatus  10 A (S 4 , T 3 ). The “specified area” is such an intersection as shown in  FIG. 4  and an area adjacent to the intersection. If the roadside apparatus  20  determines that the vehicle-mounted apparatus  10 A is not an authenticated one (NO in S 3 ), it performs a prescribed error process (S 5 ) without issuing authentication data (K). The error process is, for example, a process of transmitting a message to the vehicle-mounted apparatus  10 A, informing that the apparatus  10 A cannot be authenticated. 
     Meanwhile, the vehicle-mounted apparatus  10 A starts communicating with the roadside apparatus  20  via the wireless communication device  11 A as shown in  FIG. 6  (S 11 ). The vehicle-mounted apparatus  10 A receives the authentication data (K) from the roadside apparatus  20  if it has been determined to be authenticated by the roadside apparatus  20  (S 12  to S 14 ). In the vehicle-mounted apparatus  10 A, the controller  13 A receives the authentication data (K) though the wireless communication device  11 A and stores the data (K) in the memory  14 A. 
     The roadside apparatus  20  performs the authentication process also on the vehicle-mounted apparatus  10 B of the vehicle  100 B that has passed, for example, a narrowband wireless communication area  210 B as shown in  FIG. 4 . Assume that the roadside apparatus  20  has authenticated the vehicle-mounted apparatus  10 B. Then, in the vehicle-mounted apparatus  10 B, the controllers  13 B receives the authentication data (K) transmitted from the roadside apparatus  20 , though the wireless communication device  11 B, and stores the data (K) in the memory  14 B. As described above, the authentication data (K) is data valid at such an intersection as shown in  FIG. 4  and in an area adjacent to the intersection. 
     The sequence of the vehicle-to-vehicle communication between the vehicle-mounted apparatuses  10 A and  10 B, both authenticated, will now be explained in detail, with reference to the flowcharts of  FIGS. 7 and 8 . 
     Assume that the vehicle  100 E comes to the intersection while the vehicle  100 A is traveling toward the intersection as shown in  FIG. 4 . Also assume that the driver of the vehicle  100 A therefore treadles on the brake pedal. That is, the event of pressing the brake pedal is assumed to have occurred as shown in  FIG. 7  (YES in S 21 , T 5 ). In the vehicle-mounted apparatus  10 A, the controller  13 A generates event data representing that the brake pedal has been pressed in the vehicle  100 A. 
     Then, the controller  13 A acquires the authentication data (K) stored in the memory  14 A and also the position data from the GPS devices  12 A, and generates transmission information containing the event data, authentication data (K) and position data (S 22 ). The controller  13 A transmits the transmission information trough the wireless communication device  11 A ( 523 , T 6 ). 
     As shown in  FIG. 4 , the vehicle  100 B is at the rear of the vehicle  100 E. Suppose that the driver of the vehicle  100 B cannot see the vehicle  100 A approaching the intersection at this moment. As shown in  FIG. 8 , in the vehicle-mounted apparatus  10 B of the vehicle  100 B, the controller  13 B receives, via the wireless communication device  11 B, the transmission information containing the event data, authentication data (K) and position data transmitted from the vehicle-mounted apparatus  10 A (YES in S 31 , T 7 ). 
     The transmission information transmitted from the vehicle-mounted apparatus  10 A of the vehicle  100 A may be received not only by the vehicle-mounted apparatus  10 B of the vehicle  100 B, but also by the vehicle-mounted apparatuses  100  to  10 F of the vehicle-mounted apparatuses  100 C to  100 F. 
     The vehicle-mounted apparatus  10 B of the vehicle  100 E extracts the authentication data (K) from the transmission information received, and discriminates the authentication data (S 32 , T 8 ). More precisely, the controller  13 B of the vehicle-mounted apparatus  10 B first extracts the authentication data (K) stored in the memory  14 B and then compares this authentication data (K) with the authentication data (K) of the vehicle-mounted apparatus  10 A (S 33 ). 
     If the authentication data (K) stored in the memory  14 B is found identical to the authentication data (K) of the vehicle-mounted apparatus  10 A, the controller  13 B of the vehicle-mounted apparatus  10 B determines that the vehicle-mounted apparatus  10 A of the vehicle  100 A has been authenticated (YES in S 33 ). On the other hand, if the authentication data (K) stored in the memory  14 B is not found identical to the authentication data (K) of the vehicle-mounted apparatus  10 A, the controller  13 B of the vehicle-mounted apparatus  10 B determines that the vehicle-mounted apparatus  10 A of the vehicle  100 A has not been authenticated (T 11 , if NO in S 33 ). In this case, the controller  13 B invalidates all information received from the vehicle-mounted apparatus  10 A of the vehicle  100 A. 
     If the vehicle-mounted apparatus  10 A is found authenticated, the controller  13 B of the vehicle-mounted apparatus  10 B determines that the information received is valid, and then perform a prescribed process (S 34 , T 10 ). That is, the controller  13 B extracts the position data and event data from the information it has received and analyzes these data items extracted (T 9 ). More precisely, the controller  13 B can confirm, from the result of analyzing the position data and event data, that the vehicle  100 A is approaching the intersection and that the brake pedal has been treaded on in the vehicle  100 A, though the driver of the vehicle  100 B cannot see the vehicle  100 A approaching the intersection. 
     The controller  13 B may control the display  30 B, thereby to cause the display  30 B to display the result of analyzing the position data and the event data. In this case, the driver of the vehicle  100 B can visually confirm that the vehicle  100 A is approaching the intersection. The driver of the vehicle  100 E can therefore slow down the vehicle  100 B, not to collide with the vehicle  100 A approaching the intersection. 
     Thus, the vehicle-to-vehicle communication enables the vehicle-mounted apparatuses of the vehicles traveling at or near an intersection and in the specified areas near the intersection can receive the position data and event data from one another. The vehicle-mounted apparatus of each of these vehicles therefore analyzes the position data and even data contained in the information it has received, thereby detecting any other vehicle approaching the intersection. Note that the event data is not limited to brake data, and includes turn data and speed data. 
     Each vehicle-mounted apparatus analyzes the information received by means of the vehicle-to-vehicle communication, first finding any other vehicle approaching the intersection and the traveling state thereof, and then informing the driver of the vehicle of the other vehicle that is approaching the intersection and the traveling state thereof. This helps the driver to achieve safety driving. Further, each vehicle-mounted apparatus can give caution to the driver of any vehicle or inform him or her of how vehicles are traveling in front and at the rear. This also assists the driver to drive in safety. Moreover, if traffic congestion often occurs in the specified area, the vehicle-mounted apparatus of each vehicle analyzes the information it has received, thereby calculating the average speed of any other vehicle existing in the specified area. This enables the driver of the vehicle to confirm how much the road is congested. Still further, if the specified area has a sharp turn, disabling the driver of any vehicle in the area to see the other vehicles traveling in front, the vehicle-mounted apparatus of each vehicle analyzes the information received, thereby enabling the driver to recognize any vehicle coming toward the vehicle. 
     The vehicle-mounted apparatuses that can perform the vehicle-to-vehicle communication with one another are authenticated by the roadside apparatus  20 . Thus, the vehicle-to-vehicle communication between the vehicle-mounted apparatuses not authenticated, if attempted, is invalidated. This reliably ensures security. Since only the vehicle-mounted apparatuses authenticated in any specified area can exchange information with one another, they never use the information transmitted from the vehicle-mounted apparatus of any vehicle that exists outside the specified area. Conversely, the vehicle-mounted apparatuses existing outside the specified area are prevented from receiving invalid information. 
     In the authenticating method according to the embodiment, the authentication process is not performed in the specified area by means of vehicle-to-vehicle communication, but the result of the authentication process performed through road-to-vehicle communication is utilized. That is, road-to-vehicle communication is accomplished though a so-called “indirect vehicle-to-vehicle communication” performed as, “substituted authentication process.” In other words, an indirect mutual authentication can be achieved between vehicles. As a result, the authentication process between many vehicle-mounted apparatuses needs not be performed in the specified area, and the mutual authentication function is ensured between the vehicle-mounted apparatuses. The authentication process in the vehicle-to-vehicle communication can therefore be performed at an increased efficiency. 
     The roadside apparatus  20  may be configured to issue authentication data containing encryption data. More precisely, the transmitting-side vehicle-mounted apparatus (i.e., apparatus  10 A) transmits transmission data encoded with the encryption data. The receiving-side vehicle-mounted apparatus (i.e., apparatus  10 B) receives the transmission data. If the authentication data authenticates the transmission data, the receiving-side vehicle-mounted apparatus decodes the transmission data with the encryption key contained in the authentication data. The encryption data may be of a common key type or a public key type. 
     Other Embodiment 
     The flowcharts of  FIGS. 10 and 11  explain another embodiment. The system configuration of the other embodiment is similar to the configuration shown in  FIG. 1 , and will not be described. The authentication process performed in the road-to-vehicle communication is similar to the process shown in the flowcharts of  FIGS. 5 and 6 , and will not be explained, either. 
     How the system according to this embodiment operates will be explained with reference to the flowchart of  FIG. 10 , on the assumption that the specified area is one where the driver of any vehicle on a greatly arched bridge cannot see ahead well. 
     Two vehicles  100 A and  100 B may be traveling on the arched bridge, the vehicle  100   b  at the rear of the vehicle  100 A. In this case, the communication device  11 A incorporated in the vehicle-mounted apparatus  10 A of the vehicle  100 A transmits transmission data containing authentication data (K), position data and event data. The vehicle-mounted apparatus  10 B of the vehicle  100 B traveling at the rear of the vehicle  100 A receives the transmission data via its communication device  11 B. On the basis of the authentication data (K), the vehicle-mounted apparatus  10 B performs such indirect mutual authentication as described above. 
     The vehicle-mounted apparatus  10 B of the vehicle  100 B traveling behind the vehicle  100 A may determine that the vehicle-mounted apparatus  10 A of the vehicle  100 A is authenticated. Then, the vehicle-mounted apparatus  10 B analyzes the event data contained in the authentication data received, acquiring the speed data about the vehicle  100 A traveling in front (Step S 41 ). The vehicle-mounted apparatus  10 B further uses the position data about the vehicle  100 A, calculating the distance between the vehicles  100 BA and the vehicle  100 A traveling in front (Step S 42 ). The vehicle-mounted apparatus  10 B causes the display  30 B to display the speed of the vehicle  100 A and the inter-vehicle distance so calculated (Step S 43 ). The driver of the vehicle  100 B can therefore confirm the existence of the vehicle  100 A, the speed thereof and the inter-vehicle distance. This enables the driver of the vehicle  100 B can therefore infer the degree of traffic jam on the arched bridge on which the driver of any vehicle cannot see ahead well. 
     As the vehicle-mounted apparatus  10 B of the vehicle  100 B traveling at the rear of the vehicle  100 A transmits and receives data in this vehicle-to-vehicle communication, it can determine the traffic state in a specified area, such as an arched bridge on which the driver of any vehicle cannot see ahead well. If the vehicle  100 A is traveling slowly and if the inter-vehicle distance is therefore relatively long with respect to the vehicle  100 B traveling behind, the driver of the vehicle  100 B can know that the bridge is considerably congested. On the other hand, the driver of the vehicle  100 A can confirm the traffic jam in the specified area, e.g., arched bridge, from the speed of the vehicle  100 B traveling behind and the inter-vehicle distance. 
     How the system operates will be explained, on the assumption that the specified area extends from an entrance to a toll road to an exit thereof. 
     As the vehicle  100 A, for example, passes the entrance gate of the toll road, the roadside apparatus  20  installed at the entrance gate determines whether the vehicle-mounted apparatus  10 A is authenticated or not. If the roadside apparatus  20  determines that the vehicle-mounted apparatus  10 A is authenticated, it transmits the authentication data, which the vehicle-mounted apparatus  10 A receives (Step S 51 ). In the vehicle-mounted apparatus  10 A, the controller  13 A stores the authentication data in the memory  14 A (Step S 52 ). 
     The vehicle-mounted apparatus  10 A of the vehicle  100 A can exchange position data and event data with, for example, the vehicle-mounted apparatus  10   b  of the vehicle  100 B, which has also received the same authentication data from the roadside apparatus  20 , by virtue of the vehicle-to-vehicle communication described above. 
     As the vehicle  100 A passes the exit gate of the toll road, the vehicle-mounted apparatus  10 A communicates with the roadside apparatus  20  installed at the exit gate. This roadside apparatus  20  transmits a command to the vehicle-mounted apparatus  10 A, instructing that the authentication data the apparatus  10 A received at the entrance gate should be erased. In the vehicle-mounted apparatus  10 A, the authentication data is therefore erased from the memory  14 A (Step S 53 ). 
     By virtue of the road-to-vehicle communication, the vehicle-mounted apparatus  10 A of the vehicle  100 A can erase the authentication data received from the roadside apparatus  20  after the vehicle  100 A has traveled out of the specified area of the highway or toll road (e.g., area extending from the entrance gate to the exit gate). Therefore, the vehicle-mounted apparatus  10 A of the vehicle  100 A can invalidate the vehicle-to-vehicle communication with the vehicle-mounted apparatus  10 B of the vehicle  100 B after the vehicle  100 A has left the highway or toll road and entered an ordinary road. 
     Highways or toll roads do not always stray far away from local roads. Some are very near to local roads. If this is the case, the vehicle-mounted apparatus of a vehicle that has just exited the highway or toll road and come into a local road may receive information from the vehicle-mounted apparatuses of vehicles traveling on the highway or toll road if it keeps storing the authentication data it has received on the highway or toll road. This information is not related to the traffic state of the local road the vehicle is now traveling on, and is therefore not necessary at all. The receipt of the unnecessary information is avoided by erasing the authentication data received from the roadside apparatus  20 . 
     The function of erasing authentication data, according to this embodiment, is useful in a parking lot where an area extending from the entrance and exit can be designated as a specified area. In this case, the vehicle-to-vehicle communication can be validated while the vehicle remains in the parking lot, and can be invalidated once the vehicle has left the parking lot and come into a local road. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.