JP2013012244A - Road side communication device and transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a road side communication device and a transmission method therefor capable of reducing consumption of radio resources, while maintaining provision of necessary information.SOLUTION: The road side communication device for repeatedly radio-transmitting mixture information including road-vehicle communication information and road-road communication information secures assignment of the radio resources preferentially regarding the road-vehicle communication information, and, regarding the road-road communication information, for example, divides the information into pieces of data, and transmits the data in series to complete transmission of the whole data.

Description

  The present invention relates to a roadside communication device installed on a road side and a transmission method thereof in a communication system for realizing an intelligent transport system (ITS).

  In recent years, for the purpose of promoting traffic safety and preventing traffic accidents, advanced road traffic systems that improve the safety of vehicles by receiving information from infrastructure equipment installed on the road and utilizing this information have been studied. (For example, refer to Patent Document 1). Such a system is mainly realized by a plurality of roadside communication devices as communication devices on the infrastructure side and an in-vehicle communication device that is a communication device mounted on each vehicle. The in-vehicle communication device of each vehicle acquires driving support information (for example, obstacle information and intersection information) from the roadside communication device, and notifies the driver of these information.

Japanese Patent No. 3915612

  The information provided by the conventional roadside communication device as described above does not change for a long time, such as dynamic information that changes in a short time, such as sensor information and signal information, and the distance from the base point to the intersection, road alignment, etc. There is static information. On the vehicle side, safe driving assistance for the driver is performed based on the acquired dynamic information and static information.

  Here, since the dynamic information has a short data update period, it is necessary to transmit the dynamic information in a short cycle according to the period. On the other hand, since static information does not change for a long period of time, it is not necessary to transmit to the same vehicle frequently, but static information is quickly sent to vehicles that enter the communication area of the roadside communication device one after another. Since it is necessary to provide the information, it is necessary to perform transmission in a short cycle, similarly to the dynamic information. Furthermore, in an urban area, since there are many intersections and the distance between the intersections is short, not only information near one intersection but also information up to an intersection ahead is required. As described above, there is a problem that the amount of information to be transmitted by the roadside communication device is large and occupies most of the limited radio resource (communication band).

  In view of such a conventional problem, an object of the present invention is to provide a roadside communication apparatus and its transmission method capable of reducing consumption of radio resources while maintaining provision of necessary information.

  For example, in a roadside communication device that repeatedly transmits wirelessly at least to a vehicle-mounted communication device, mixed information including information on a near area that is within a predetermined range as viewed from the transmission point and information on a far area that is outside the range. Radio resources are preferentially allocated to the information of the remote area, and information of the remote area is received based on the fact that the distance from the transmission point is farther than the near area. The in-vehicle communication device that has started the process may perform the differential radio resource allocation relatively less than the information in the near area so that the information acquisition is completed when the in-vehicle communication device reaches the far area.

  In the roadside communication device configured as described above, radio resource allocation is preferentially secured for near-area information transmission, and far-area information is relatively less than near-area information regarding radio resource allocation. By performing the discriminative treatment, it is possible to reduce the consumption of radio resources as a whole.

In the roadside communication apparatus as described above, information on the far area is divided into a plurality of data, one data selected from the plurality of data is transmitted at a time, and all data is transmitted by a plurality of times of transmission. It is also possible to send data.
In this case, all information in the far area is transmitted by a plurality of times of transmission. On the receiving side, a plurality of received data can be combined with each other to obtain all information in the far area.

In the roadside communication apparatus as described above, the far area is divided into a plurality of areas according to the distance from the transmission point, and the number of “multiple times” may be increased as the distance is longer.
In this case, it is possible to reduce the total information amount of the far area in one transmission by reducing the data amount in one transmission as the area is farther away.

In the roadside communication apparatus as described above, it is preferable that identification information for acquiring information on a far area before the division by combining a plurality of divided data with each other is given to each data.
In this case, the vehicle side that has received the plurality of data can reliably acquire the information of the far area before the division based on the identification information.

In the roadside communication apparatus as described above, information on the far area may be transmitted by a transmission method that is faster than information on the near area.
In this case, since the time required for transmission is relatively shortened in the high-speed transmission method, it is possible to reduce the time during which information in the far area occupies radio resources in one transmission.

In the roadside communication apparatus as described above, information on the far area may be transmitted with a higher degree of compression than information on the near area.
In this case, since the usage rate of the radio resource with respect to the information amount can be reduced by transmitting with a high degree of compression, it is possible to reduce the time that the information in the far area occupies the radio resource in one transmission.

In the roadside communication apparatus as described above, the near area information and the far area information may not change at least within one cycle time of the traffic light.
In this case, regarding static information that does not change for a long period of time and information with relatively little change, it is possible to reduce the consumption of radio resources due to information in a far area.

  On the other hand, as a method, mixed information including information on a near area that is within a predetermined range when viewed from the transmission point and information on a far area that is outside the range is repeatedly transmitted wirelessly from the roadside communication device to at least the in-vehicle communication device. In the transmission method, radio resource allocation is secured preferentially for the near-area information, and for the far-area information, the distance from the transmission point is farther than the near-area, As the in-vehicle communication device that has started receiving information in the near area reaches the far area, the information acquisition is completed, so that the radio resource allocation is relatively less than the information in the near area. It may be.

  In the transmission method as described above, radio resource allocation is preferentially secured for near-area information transmission, and far-area information is handled with less discriminatory relative to near-area information regarding radio resource allocation. By doing so, it is possible to reduce the consumption of radio resources as a whole.

  In addition, for example, a roadside that repeatedly transmits wireless information to a vehicle-mounted communication device and another roadside communication device including mixed information including information on a near area that is within a predetermined range as viewed from the transmission point and information on a far area that is outside the range. In the communication device, radio resource allocation is secured preferentially for the road-to-vehicle communication information in the near area, and the road-to-road communication information in the far area is relative to the information in the near area. You may make it allocate few discriminatory radio | wireless resources.

  In addition, as a method, the in-vehicle communication device and other roadside communication are repeatedly performed from the roadside communication device by mixing information including near area information within a predetermined range as viewed from the transmission point and far area information outside the range. In a transmission method for wireless transmission to a device, radio resource allocation is secured preferentially for information on road-to-vehicle communication in the near area, and information for road-to-road communication in the far area is assigned to the information in the near area. You may make it perform the allocation of the discriminating radio | wireless resource relatively less than information.

  (1) And, the present invention is a roadside communication device that wirelessly transmits mixed information including roadway-to-vehicle communication information and roadway-to-roadway communication information to the in-vehicle communication device and other roadside communication devices, Radio resource allocation is preferentially secured for road-to-vehicle communication information, and discriminative radio resource allocation is performed for road-to-road communication information that is relatively less than information for road-to-vehicle communication. Is.

  (2) In addition, the method is a transmission method in which mixed information including road-to-vehicle communication information and road-to-road communication information is wirelessly transmitted from the road-side communication device to the in-vehicle communication device and other road-side communication devices. Thus, radio resource allocation is ensured preferentially for the road-to-vehicle communication information, and for the road-to-road communication information, there is relatively less discriminating radio resource than the road-to-vehicle communication information. Assign.

  (3) Furthermore, the present invention is a roadside communication device that repeatedly transmits mixed information including information on road-to-vehicle communication and information on road-to-road communication to an in-vehicle communication device and other roadside communication devices, Static information that does not change for a long time in road-to-vehicle communication and information with relatively little change in road-to-road communication are divided in time and transmitted alternately.

  (4) Further, as a method, there is a transmission method in which mixed information including road-to-vehicle communication information and road-to-road communication information is repeatedly transmitted to an in-vehicle communication device and other roadside communication devices, Static information that does not change for a long time in inter-vehicle communication and information with relatively little change in the road-to-road communication are temporally divided and transmitted alternately.

(5) The present invention viewed from another viewpoint is that the in-vehicle communication device and the like repeatedly perform mixed information including information on a near area that is within a predetermined range as viewed from the transmission point and information on a far area that is outside the range. A roadside communication device that wirelessly transmits to a roadside communication device of
Allocating radio resources preferentially for road-to-vehicle communication information, and performing relatively less discriminatory radio resource allocation for road-to-road communication information than the road-to-vehicle communication information It is.

(6) In addition, as a method, it is possible to repeatedly transmit mixed information including information on a near area within a predetermined range as viewed from the transmission point and information on a far area outside the range from the roadside communication device, and the like. A transmission method for wireless transmission to a roadside communication device of
Allocating radio resources preferentially for road-to-vehicle communication information, and performing relatively less discriminatory radio resource allocation for road-to-road communication information than the road-to-vehicle communication information It is.

(7) Furthermore, the present invention repeats mixed information including information on a near area within a predetermined range as viewed from the transmission point and information on a far area outside the range, and the in-vehicle communication device and other roadside communication devices A roadside communication device that wirelessly transmits to
Static information that does not change for a long time in road-to-vehicle communication and information that has relatively little change in road-to-road communication are divided in time and transmitted alternately.

(8) Further, as a method, the vehicle-mounted communication device and other roadside communication devices that repeat mixed information including near-area information within a predetermined range as viewed from the transmission point and far-area information outside the range are used. A wireless transmission method,
Static information that does not change for a long time in road-to-vehicle communication and information that has relatively little change in road-to-road communication are divided in time and transmitted alternately.

  According to the roadside communication apparatus or the transmission method of the present invention, it is possible to reduce consumption of radio resources while maintaining provision of necessary information.

It is a top view which shows an example of the road near the intersection where the roadside communication apparatus was installed. It is a block diagram which shows the outline of the internal structure of a roadside communication apparatus and a vehicle-mounted communication apparatus. It is a top view which shows the expansion of the typical road in a city area. It is a figure which shows the reference example of the frame structure of the static information transmitted from a roadside communication apparatus. (A) shows a state in which the information in area B is divided into 8 to form 8 data groups B1 to B8, and (b) shows the information in area C divided into 12 and C1 to C12. The 12 data groups are shown. It is the figure which looked at the information transmitted periodically with progress of time from the top. (A) is a figure which shows the frame structure at the time of transmitting area B and C information similarly to area A information similarly to FIG. 4, (b) is the roadside communication which concerns on 2nd Embodiment. It is a figure which shows the frame structure of the information which an apparatus transmits.

  FIG. 1 is a plan view showing an example of a road near an intersection where a roadside communication device is installed. The roadside communication device 1 shown in the vicinity of the center of the figure is installed, for example, on a column of a traffic light 2 at an intersection. On the other hand, each vehicle traveling on the road is equipped with an in-vehicle communication device capable of communicating with the roadside communication device 1. Such a roadside communication device 1 is similarly installed at other intersections adjacent in all directions.

  Each roadside communication device 1 is connected to the central control unit 4 of the traffic control center. The central control unit 4 and the roadside communication device 1 are connected by wire (however, wireless is also possible), and between the roadside communication devices 1 (roadside communication), between the roadside communication device 1 and the in-vehicle communication device (" Wireless communication is used for road-to-vehicle communication from “road” to “car” or vehicle-to-vehicle communication from “car” to “road”) and between vehicle-mounted communication devices (vehicle-to-vehicle communication).

  FIG. 2 is a block diagram showing an outline of the internal configuration of the roadside communication device 1 and the in-vehicle communication device 3. The roadside communication device 1 includes a communication unit (transmission / reception unit) 11 connected to an antenna 10, a control unit 12 that performs control related to communication, and a storage unit 13 connected to the control unit 12. The roadside communication device 1 periodically transmits dynamic information and static information, and the in-vehicle communication device 3 receives these information. The in-vehicle communication device 3 includes a communication unit (transmission / reception unit) 31 connected to the antenna 30, a control unit 32 that performs control related to communication, and a storage unit 33 that stores necessary information.

  The dynamic information transmitted from the roadside communication device 1 is, for example, sensor information from an infrared sensor or a beacon for detecting a vehicle and acquiring speed and traffic information, as well as signal information of the traffic light 2, etc. Information that changes in a short time. The static information is information that does not change over a long period of time, such as the distance from here to the next intersection, road alignment, etc., starting from the intersection where the roadside communication device 1 is installed. The in-vehicle communication device 3 provides information for safe driving support to the driver based on the received information.

In the roadside communication device 1 and the vehicle-mounted communication device 3 as described above, communication between roads, roads and vehicles, between roads, and between vehicles is performed by a time division multiplexing method within a limited frequency band.
Hereinafter, a configuration of information transmitted (broadcast) from the roadside communication device 1 to the in-vehicle communication device 3 will be described.

  FIG. 3 is a plan view showing a typical road spread in an urban area. Now, consider the roadside communication device 1 installed at the intersection S0 in the center of this figure, and the transmission point of the roadside communication device 1 is at the center of the intersection S0. The area A having a predetermined radius centered on this area is a near area when viewed from the intersection S0, and at least the vehicle-mounted communication device 3 (FIG. 2) of the vehicle traveling in the vicinity of the intersection S0 should be promptly provided with the latest information. Is desirable.

  In addition, for example, the roadside communication device 1 at one intersection provides information from the intersection to the two intersections ahead. That is, the roadside communication device 1 of the intersection S0 includes information on the area B having a predetermined radius that is farther from the area A, including the intersections S1 to S4 that are one ahead when viewed from the intersection S0 in addition to the information on the area A. And information on the area C having a predetermined radius that is further away from the area B, including the intersections S5 to S8 that are two points ahead from the intersection S0.

  FIG. 4 is a diagram illustrating a reference example of a frame configuration of static information transmitted from the roadside communication device 1. If the information of each area A, B, C is configured in a frame as it is, the amount of information increases as shown in the figure. When such information is transmitted periodically (in the order of 1, 2,...), A large amount of radio resources (communication bandwidth) are occupied.

  Therefore, in the present invention, radio resource allocation is preferentially secured for information in area A that is a near area as viewed from the transmission point, and information for areas B and C that are other far areas is secured. It is assumed that the discriminative radio resource allocation is relatively less than the information of area A.

  That is, for example, it is necessary to quickly and preferentially provide information on area A to vehicles in area A, but since it is a little later that the vehicle reaches area B that is a little away, The provision timing may be slightly delayed from the information provision in area A. Further, since the vehicle arrives at the further distant area C later, the timing for providing information on the area C may be delayed from the information provision on the areas A and B. In other words, the area farther away from the transmission point has more time to deliver the area information.

<< First Embodiment >>
Therefore, the roadside communication device 1 according to the first embodiment transmits the information in the area B and the information in the area C sequentially in small portions without transmitting all the information at once. (A) of FIG. 5 shows the state which divided | segmented the information of the area B into eight, and was made into the 8 data group of B1-B8. FIG. 5B shows a state in which the information in area C is divided into 12 pieces to form 12 data groups C1 to C12.

  The reason why the number of divisions is larger in area C than in area B is because it is farther away and the time margin for information transmission is larger. For example, IDs of 1/8 to 8/8 are assigned as identification information to the divided data B1 to B8, respectively. Similarly, IDs of 1/12 to 12/12 are assigned to the divided data C1 to C12, respectively. Therefore, the in-vehicle communication device 3 that receives it can immediately grasp the number of divisions at any timing and determine whether or not all necessary data has been prepared. Note that a checksum function may be added so that data that has failed to be received may be discarded, and accurate information acquisition may be performed.

  The data B1 to B8 and C1 to C12 divided as described above constitute one frame together with the area A information. FIG. 6 is a diagram of information periodically transmitted over time as viewed from the top. In the figure, all the information on area A is subject to transmission every time and is included in one frame. On the other hand, regarding the information of area B, only the subdivided data B1 is transmitted in the first transmission. Similarly, regarding the information of area C, only the subdivided data C1 is transmitted in the first transmission.

  Similarly, for area B, B2, B3,. . . , B8 is transmitted, transmission of all data is completed in the eighth transmission, and transmission returns to B1 in the ninth transmission. For area C, C2, C3,. . . , C12, and transmission of all data is completed in the twelfth transmission, and the transmission returns to C1 in the thirteenth (not shown) transmission.

  As described above, radio resource allocation is preferentially secured for information transmission in area A. Further, the information on the areas B and C is transmitted over several cycles with the subdivided data shifted in time. According to such a transmission method, the amount of information of one transmission is reduced as apparent from the comparison with FIG. Therefore, it is possible to reduce the consumption of radio resources when transmitting such information.

  The in-vehicle communication device 3 can obtain the information on the area A as it is by receiving it once. On the other hand, the in-vehicle communication device 3 acquires the data B1 to B8 by receiving 8 times for the information of the area B, and then combines the information based on the ID of each data to acquire the original information before the division. Similarly, regarding the information of area C, after acquiring the data C1 to C12 by receiving 12 times, the information is combined based on the ID of each data, and the original information before the division is acquired.

  The transmission as described above is performed from all roadside communication devices 1. Therefore, when viewed from the traveling vehicle, information near the nearest intersection (area A information) is always delivered with priority, and the farther the area from the current location (area B information, area C information), the more time is spent. All information will arrive.

  If the transmission cycle in FIG. 6 is, for example, 100 msec, the in-vehicle communication device of the vehicle traveling in the communication area (the area that can communicate with any one of the roadside communication devices 1) has the information on area A during the first 100 msec. To get. As for the information of area B, it takes 800 msec to receive all the information in the 8th cycle, but even if it is running at 80 km / h, it takes about 18 m to run at 800 msec. There is no practical problem with the acquisition timing. Similarly, as for the information of area C, it takes 1.2 seconds to receive all the information in the 12th cycle. However, even if the vehicle travels at 80 km / h, it takes about 27 m to travel at 1.2 sec. Thus, there is no practical problem as the acquisition timing of the area C information.

<< Second Embodiment >>
(A) of FIG. 7 is a figure which shows the frame structure at the time of transmitting transmission of area B and C information similarly to area A information similarly to FIG. 4, On the other hand, (b) is It is a figure which shows the frame structure of the information which the roadside communication apparatus which concerns on 2nd Embodiment transmits. In (b), each information of area A, area B, and area C is transmitted by mutually different transmission methods.

  For example, the area B information is transmitted at a transmission rate twice that at the time of transmitting the area A information. In addition, the area C information is transmitted at a transmission rate three times that at the time of transmitting the area A information. In order to obtain a high transmission rate, it is possible to prevent unnecessary radio resources from being used, for example, by using a multi-level modulation method. As a result, even if the amount of data transmitted in one transmission is the same, consumption of radio resources can be reduced by shortening the time for occupying radio resources.

  In general, when communication is performed in a high-speed transmission mode such as multi-level modulation, higher line quality is required. Since road-to-vehicle communication is mobile communication, the line quality varies. However, even if the in-vehicle communication device 3 of the vehicle fails to receive the information of the area B or the information of the area C, there is an opportunity to receive the same data many times while moving in the communication area. Even if it takes a long time to complete reception, there is no particular problem.

  Specifically, for example, BPSK (two-phase phase modulation) or QPSK (four-phase phase modulation) is used for information transmission in area A, 16QAM (16-value quadrature amplitude modulation) is used for information transmission in area B, and 64QAM (64-value quadrature amplitude modulation) can be employed for information transmission.

  In the above example, the radio resource occupancy time is shortened by changing the transmission rate. Even if the transmission rate is the same, the same is achieved by changing the correction capability of the error correction method to be used. In addition, it is possible to shorten the occupation time of radio resources. In general, an error correction method improves the correction capability if the redundancy is increased. Therefore, the data length of the information of the area B and the information of the area C can be reduced by reducing the redundancy compared to the information of the area A. Can be shortened. Thereby, the same effect is acquired.

<< Third Embodiment >>
In addition, the same thing as the second embodiment can be realized by changing the degree of data compression. That is, the information on area A is kept as it is (uncompressed), and the information on area B and the information on area C are transmitted by sequentially increasing the data compression level, as in FIG. Consumption of radio resources can be reduced. In this case, it takes time to restore the compressed data on the receiving side, but this restoration time does not significantly affect the entire reception time.

<Others>
In each of the embodiments described above, transmission of static information has been described. However, some dynamic information includes information having a relatively long information update cycle. For such information, similar to the static information, transmission may be performed with priority in the near area, and in the far area, transmission may be performed so as to consume as little radio resources as possible. For example, dynamic information that does not change at least within one cycle time of the traffic light (from the green signal to the next green signal) can be handled as described above. Thereby, it is possible to reduce the consumption of radio resources due to the information in the far area even with respect to the dynamic information with relatively little change.

In each of the above embodiments, the case of transmitting information on the three areas A, B, and C has been described, but the number of areas may be two or four or more. The size and shape of the area can be changed according to the road conditions.
Moreover, although the roadside communication apparatus 1 shall be installed in the support | pillar of the signal apparatus 2, the installation form is not limited to this, You may install it by standing a support | pillar etc. independently. Further, it may be combined with a control device (not shown) of the traffic light 2 and configured as a part of the traffic light 2.

  It is also possible to realize a roadside communication device and a transmission method that combine the technical features of the first to third embodiments. That is, in order to reduce the allocation of radio resources for far-area information compared to the near area, each embodiment adopts (b) division (first embodiment) and (b) a high-speed transmission method. (Second Embodiment), (c) The transmission is performed with a high degree of compression (Third Embodiment). However, a roadside communication device or a transmission method in which (a) to (c) are arbitrarily combined may be used. In combination, the effect of reducing the consumption of radio resources can be further enhanced.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of claims for patent, and is intended to include all modifications within the scope and meaning equivalent to the scope of claims for patent.

1 Roadside communication device 2 Traffic light 3 In-vehicle communication device A area (near area)
B, C area (far area)
S0-S8 intersection

Claims (8)

A roadside communication device that repeatedly transmits mixed information including roadway-to-vehicle communication information and roadway-to-roadway communication information to vehicle-mounted communication devices and other roadside communication devices,
Preferentially allocate radio resources to the information on road-to-vehicle communication, and allocate relatively less discriminatory radio resources to information on the road-to-road communication than information on the road-to-vehicle communication. Roadside communication device to perform. A transmission method for wirelessly transmitting mixed information including road-to-vehicle communication information and road-to-road communication information from the roadside communication device to the in-vehicle communication device and other roadside communication devices,
Preferentially allocate radio resources to the information on road-to-vehicle communication, and allocate relatively less discriminatory radio resources to information on the road-to-road communication than information on the road-to-vehicle communication. The transmission method to perform. A roadside communication device that repeatedly transmits mixed information including roadway-to-vehicle communication information and roadway-to-roadway communication information to vehicle-mounted communication devices and other roadside communication devices,
A roadside communication device that transmits static information that does not change for a long time in the road-to-vehicle communication and information that has a relatively small change in the road-to-road communication in a time-division manner and alternately. A transmission method for repeatedly transmitting mixed information including road-to-vehicle communication information and road-to-road communication information to vehicle-mounted communication devices and other roadside communication devices,
A transmission method in which static information that does not change for a long time in the road-to-vehicle communication and information with relatively little change in the road-to-road communication are temporally divided and transmitted alternately. A roadside communication device that repeatedly transmits wirelessly mixed information including near-field information within a predetermined range as viewed from the transmission point and far-area information outside the range to the in-vehicle communication device and other roadside communication devices. And
Roadside that preferentially secures radio resource allocation for road-to-vehicle communication information, and performs relatively less discriminatory radio resource allocation for road-to-road communication information than the road-to-vehicle communication information. Communication device. Transmission that wirelessly transmits mixed information including near-area information within a predetermined range as viewed from the transmission point and far-area information outside the range from the roadside communication device to the in-vehicle communication device and other roadside communication devices A method,
Transmission that preferentially secures radio resource allocation for road-to-vehicle communication information and performs relatively less discriminatory radio resource allocation for road-to-road communication information than the road-to-vehicle communication information. Method. A roadside communication device that repeatedly transmits wirelessly mixed information including near-field information within a predetermined range as viewed from the transmission point and far-area information outside the range to the in-vehicle communication device and other roadside communication devices. And
A roadside communication device that alternately transmits static information that does not change for a long time in road-to-vehicle communication and information that has relatively little change in road-to-road communication in time division. A transmission method of repeatedly transmitting mixed information including information on a near area within a predetermined range as viewed from a transmission point and information on a far area outside the range to an in-vehicle communication device and other roadside communication devices. ,
A transmission method in which static information that does not change for a long time in road-to-vehicle communication and information that has relatively little change in road-to-road communication are temporally divided and transmitted alternately.

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