JP5818206B2 - Method for estimating the required number of radio resources allocated to a plurality of roadside communication devices installed in a predetermined area, and radio resource allocation method - Google Patents

Description

  The present invention provides, for example, a method for estimating the required number of radio resources allocated to a road communication device installed in a predetermined area, which is used in an intelligent transport system (ITS), and radio resource allocation Regarding the method.

In recent years, for the purpose of promoting traffic safety and preventing traffic accidents, vehicle safety has been achieved by receiving information from infrastructure devices installed on roads or exchanging information between vehicles and utilizing these information. An intelligent road traffic system that improves the above has been studied (for example, see Patent Document 1).
Such an intelligent road traffic system is mainly composed of a plurality of roadside communication devices which are wireless communication devices on the infrastructure side and a plurality of in-vehicle communication devices which are wireless communication devices mounted on each vehicle.

  In this case, a combination of communication performed between communication subjects includes road-to-road communication performed by road-side communication devices, road-vehicle (or road-road) communication performed by a road-side communication device and a vehicle-mounted communication device, and vehicle-mounted communication. Vehicle-to-vehicle communication performed between aircraft.

Japanese Patent No. 2806801

  In the above-mentioned intelligent road traffic system, road-to-vehicle communication, road-to-road communication, road-to-road communication, and road-to-step communication, including road-to-vehicle communication, can be carried out between roads within a limited frequency band. In order to perform communication between road vehicles and between vehicles, time division multiplexing (TDMA) that divides radio resources in the time domain and provides time slots that are time zones dedicated to transmission of roadside communication devices. Multi-access method is adopted.

  In the multi-access scheme based on TDMA, a plurality of time slots dedicated to transmission by roadside communication devices are usually set in one radio frame. That is, one radio frame includes a plurality of time slots set in different time zones. In this way, a plurality of time slots are provided in one radio frame, and by assigning these time slots to each roadside communication device, a radio resource is assigned to each of the plurality of roadside communication devices.

Here, roadside communicators are usually installed at intersections on roads, etc., but when adjacent intersections are relatively close, each of the roadside communicators installed at these intersections can transmit wirelessly (services). Area) may overlap each other. When the service areas overlap, interference occurs in the transmission signals of the two-way communication devices in the overlapping portions, and it becomes difficult to obtain these transmission signals with high accuracy on the in-vehicle communication device side.
For this reason, different time slots set in different time zones within one radio frame are allocated at least between roadside communication devices in a positional relationship in which interference occurs. This prevents interference.

However, there is a limit to the number of time slots that can be set in one radio frame. For this reason, when applying the above-mentioned intelligent road traffic system on an actual road, a predetermined area is added while restricting the assignment of different time slots to roadside communication devices in a positional relationship where interference occurs. It is necessary to know in advance how many time slots are required when time slots are assigned to each roadside communication device.
Furthermore, from the viewpoint of saving radio resources, it is also required to search for an assignment that can reduce the required number of time slots and to reduce the required number of time slots.

  The present invention has been made in view of such circumstances, a method capable of easily estimating a minimum value for the required number of radio resources allocated to a road communication device installed in a predetermined area, and An object of the present invention is to provide a radio resource allocation method used for this.

(1) The present invention relates to a method for estimating a required number of radio resources when a plurality of different radio resources that do not overlap each other are allocated to a plurality of road communication devices installed in a predetermined area, An interference area identifying step for identifying an interference area in which the communication device interferes with other road communication devices in the predetermined area for each of a plurality of different directions; a predetermined number of road communication devices are installed; A unit area setting step for setting a unit area based on a size of each of the plurality of different directions of the specified interference area, and a size of each different direction, and each of the roadside communication devices included in the unit area Allocation step for allocating radio resources to each of the roadside communication devices so that they do not interfere with each other; Obtaining the number of radio resources required for allocation in a loop as an estimated value of the required number of radio resources allocated to the plurality of road communication devices installed in the predetermined area. It is characterized by.

According to the method configured as described above, the road communication devices are arranged so that the road communication devices included in the unit area set based on the size of the interference area do not interfere with each other by the assigning step. In contrast, even if a plurality of unit areas are arranged adjacent to each other, the radio resources of each road communication device are those of road communication devices installed in other unit areas adjacent to the unit area including the own device. The allocation may be such that the radio resources are different from each other. As a result, if radio resources are allocated within a unit area, radio resources can be allocated such that each road communication device does not interfere with each other not only within the unit area but also between adjacent unit areas. . As a result, if the required number of radio resources necessary for allocating to each road communication device in the unit area is obtained, the required number of radio resources to be allocated to the road communication device in a predetermined area in which a plurality of unit areas are arranged adjacent to each other is obtained. The estimated value can be obtained, and the minimum value can be easily obtained.
In the interference area specifying step, the road communication device that is the target of specifying the interference area is all of the road communication devices installed in the predetermined area, and the road communication devices installed in the predetermined area. There may be a plurality of on-road communication devices that constitute a part of all.

(2) In the above method, it is preferable that the interference area specifying step further specifies the size of the maximum interference area for each of the plurality of different directions from the specified interference areas.
In this case, if the size of the unit area is set so as to include the interference area of the maximum range size in each of a plurality of different directions, the road communication devices of each other can be more reliably connected between the adjacent unit areas. Radio resources can be allocated so as not to cause interference.

(3) The allocating step in the above method includes the interference area in any of the plurality of different directions that can be arranged in the unit area, even if the interference area is arranged in any position in the unit area. It is preferable that radio resources are allocated to each of the road communication devices in the unit area so that the radio resources allocated to the road communication devices to be assigned are different from each other.

  In this case, it is possible to limit the allocation of radio resources to each roadside communication device included in the unit area while avoiding interference between the roadside communication devices due to the mutual interference area, and the assignment in the assignment step The number of radio resources required for the communication can be further reduced.

(4) In the allocation step, the interference area that includes both the road communication device in the unit area and the road communication device outside the unit area is placed in the interference area regardless of the position. The radio resource may be allocated to each road communication device in the unit area so that the radio resources allocated to the included road communication device are different from each other.
Also in this case, each road communication device can more reliably allocate radio resources that do not interfere with road communication devices installed in other unit areas adjacent to the unit area including the own device. .

(5) (6) In the above method, the predetermined area, the interference area, and the unit area may be specified in units of installation positions of the plurality of road communication devices arranged in the predetermined area. In this case, it is easy to handle the area and the area focusing on the road communication device.
Furthermore, the installation position may include an estimated installation position where the road communication device estimated from the installation position can be installed. In this case, the road communication device is not currently installed, but is installed in the future. The allocation of radio resources can also be considered for possible locations.

(7) In the above method, the radio resources are preferably time slots set side by side in the time axis direction, and a plurality of different radio resources can be easily obtained by setting so as not to overlap in the time axis direction. be able to.

(8) In the unit area setting step, the interference area specified for each of the plurality of different directions may be a majority area in which many of the same exist, and a minority area having a smaller number than the majority area. And the unit area is set based on the majority area, and in the assignment step, the roadside communication devices included in the unit area set based on the majority area do not interfere with each other. As described above, radio resources are allocated to each of these road communication devices, and then the road communication devices included in the minority area are not affected by interference with other road communication devices other than the own device. The radio resource of the roadside communication device included in the group area may be allocated.
In this case, since the unit area is first set based on the majority area, the regularity in assigning radio resources is increased in the subsequent assignment step, which is simplified and facilitated. Furthermore, radio resources are allocated separately for road communication devices included in the minority area. However, since there are a small number of radio resources allocated for road communication devices included in the minority area, exceptional processing is performed. Even if it is done, the entire allocation step is facilitated.

(9) Further, the present invention is a radio resource allocation method for allocating a plurality of different radio resources that do not overlap each other to each of a plurality of road communication devices installed in a predetermined area,
An interference area specifying step for specifying, in a plurality of different directions, an interference area where at least some of the road communication devices interfere with other road communication devices in the predetermined area; A unit area setting step for setting a unit area based on the size of each of the plurality of different directions of the identified interference area, while a road communication device is installed, An allocation step of allocating radio resources to the road communication devices so that the road communication devices included in the unit area do not interfere with each other.

  According to the radio resource allocation method having the above-described configuration, if radio resources are allocated within a unit area, the on-road communication devices do not interfere with each other not only within the unit area but also between adjacent unit areas. Radio resources can be allocated.

  ADVANTAGE OF THE INVENTION According to this invention, the minimum value about the required number of the radio | wireless resources allocated to the roadside communication apparatus installed in the predetermined area can be estimated easily.

It is a schematic perspective view which shows the whole structure of the intelligent transport system (ITS) used as the application object of this invention. It is a block diagram which shows the internal structure of a roadside communication apparatus and a vehicle-mounted communication apparatus. It is a conceptual diagram which shows an example of the time slot of road-to-vehicle communication. 5 is a flowchart illustrating a method for estimating a required number of first slots according to an embodiment of the present invention. It is the figure which showed the road shape in the area for setting a target area. It is a figure which shows the model of the road and installation candidate point in the target area of this embodiment. It is a figure which shows an interference area when the one roadside communication apparatus is made into a reference | standard. It is a figure which shows the aspect which patterned the interference area for every direction, (a) is a pattern of the interference area of the north-south direction, (b) is a pattern of the interference area of the east-west direction, (c) is northeast- The pattern of the interference area in the southwest direction and the pattern of the interference area in the northwest-southeast direction are shown. It is a figure which shows an example of a unit area. (A) is a figure which shows an example when arrange | positioning only the maximum range pattern of the interference area of a north-south direction in the said unit area so that a unit area may be filled with respect to each installation candidate point contained in a unit area. (B) is a figure which shows an example when arrange | positioning only the maximum range pattern of the interference area of the east-west direction with respect to each installation candidate point contained in a unit area in the said unit area so that a unit area may be buried. is there. It is a figure which shows an example when it arrange | positions in the said unit area so that only the maximum range pattern of the interference area of a diagonal direction may be filled with each unit candidate point included in a unit area, (a) When the maximum range pattern of the interference area in the northeast-southwest direction is applied, (b) shows the case where the maximum range pattern of the interference area in the northwest-southeast direction is applied. It is the figure which showed the relationship between the installation candidate point outside the range of a target unit area, and the installation candidate point in a target unit area, (a) is the case where the interference area K3 of the northeast-southwest direction is applied (B) has shown the case where the interference area of the northwest-southeast direction is applied. It is a figure for demonstrating an example of the allocation method of the 1st slot with respect to each installation candidate point contained in a unit area. FIG. 14 is a diagram for describing an example of a method of assigning the first slot to each installation candidate point included in the unit area, and shows a continuation of FIG. 13. It is a figure which shows an example of allocation of the 1st slot with respect to a unit area, and is the maximum range pattern of the interference area of each direction arrange | positioned in a unit area, and the slot number of the 1st slot allocated to each installation candidate point V Showing the relationship. It is a figure which shows a part of area comprised by arranging the unit area to which allocation shown in FIG. 13 was applied adjacently. It is a figure which shows the installation candidate point in the target area which concerns on a modification. (A) is a figure which shows an example which allocated the radio | wireless resource to each installation candidate point by the unit area set based on the interference area classified into a majority area, (b) is a figure which shows in a minority area. It is a figure which shows an example which allocated the radio | wireless resource to each installation candidate point by the unit area set after considering the interference relationship of the interference area classified. It is a figure which shows the result of having arrange | positioned each said installation candidate point in a grid | lattice model, paying attention only to the interference relationship of each installation candidate point, (a) shows each installation candidate point in an actual geographical position. It is the figure represented by the arrangement according to this, and (b) is a figure which shows an example which arranged and represented the installation candidate point V in the grid | lattice model based on the interference relationship between each installation candidate point. It is a figure which shows the result of having arrange | positioned the said each installation candidate point in a grid | lattice model, paying attention only to the geographical positional relationship of each installation candidate point, (a) shows each installation candidate point V by actual geography. FIG. 5B is a diagram showing the result of dividing the geographical area so that each installation candidate point V is arranged for each cell, and FIG. FIG. 6 is a diagram showing an example in which the installation candidate points V are arranged and represented in a grid pattern. It is a figure which shows the other example of a setting of a unit area.

[1. Overall configuration of applicable system]
FIG. 1 is a schematic perspective view showing an overall configuration of an intelligent road traffic system (ITS) to which the present invention is applied. In this system example, as an example of the road structure, a grid structure in which a plurality of roads in the north-south direction and the east-west direction intersect with each other is assumed.
As shown in FIG. 1, an intelligent traffic system includes a traffic signal 1, a roadside communication device (on-road communication device) 2, an in-vehicle communication device 3 (see FIG. 2), a central device 4, and a vehicle 5 equipped with the in-vehicle communication device 3. And a roadside sensor 6 composed of a vehicle detector, a monitoring camera or the like.

The traffic signal 1 and the roadside communication device 2 are installed at each of a plurality of intersections Ji (i = 1 to 12 in the example), and are connected to the router 8 via a communication line 7 such as a telephone line. . This router 8 is connected to the central device 4 in the traffic control center.
The central device 4 constitutes a local area network (LAN) with the traffic signal device 1 and the roadside communication device 2 at each intersection Ji included in the area under its control. Therefore, the central device 4 can perform bidirectional communication with each traffic signal 1 and each roadside communication device 2. The central device 4 may be installed on the road instead of the traffic control center.

The roadside sensor 6 is installed in various places on the road in the jurisdiction area for the purpose of counting the number of vehicles flowing into each intersection Ji. The roadside sensor 6 includes a vehicle sensor that ultrasonically senses the vehicle 5 that passes underneath, or a monitoring camera that shoots traffic conditions on the road in time series. The sensing information S4 and the image data S5 are transmitted via the communication line 7. Is transmitted to the central device 4 via
In FIG. 1 and FIG. 2, only one signal lamp is depicted at each intersection Ji for the sake of simplicity of illustration, but each actual intersection Ji is used for ascending and descending roads that intersect each other. At least four signal lamps are installed.

[2. Central device)
The central device 4 has a control unit including a workstation (WS), a personal computer (PC), and the like. This control unit collects and processes various types of traffic information from the roadside communication device 2 and the roadside sensor 6. (Calculation), recording, signal control and information provision are performed in an integrated manner.
Specifically, the control unit of the central device 4 performs system control for adjusting the traffic signal group 1 on the same road for the traffic signal 1 at the intersection Ji belonging to its own network, and this system control is applied to the road network. Extended wide area control (surface control) can be performed.

In addition, the central device 4 has a communication unit that is a communication interface connected to the LAN side via the communication line 7, and this communication unit includes a signal control command S1 relating to the lamp color switching timing of the signal lamp, Traffic information S2 including traffic jam information and the like is transmitted to the traffic signal device 1 and the roadside communication device 2 every predetermined time (see FIG. 1).
Further, the central device 4 transmits road alignment information S7 indicating the shape and gradient of the road to each roadside communication device 2.

  The signal control command S1 is transmitted every calculation period (for example, 1.0 to 2.5 minutes) of the signal control parameter when performing the system control and the wide area control, and the traffic information S2 is transmitted every 5 minutes, for example. Is done. Further, the road alignment information S7 indicating the road shape or the like hardly changes unless there is a large-scale construction or the like, and is hardly updated. For example, the road linear information S7 is transmitted every few days.

  Further, the communication unit of the central device 4 is generated when the vehicle passes through the vehicle information S3 including the current position of the vehicle 5 received by the communication device 2 from the in-vehicle communication device 3 from the roadside communication device 2 corresponding to each intersection Ji. Sensing information S4 of a vehicle sensor (not shown) consisting of a pulse signal and image data S5 consisting of digital information of a road photographed by a surveillance camera are received, and the control unit of the central device 4 Based on various information, the system control and the wide area control are executed.

[3. (Wireless communication system etc.)
In an intelligent road traffic system, a plurality of roadside communication devices 2 installed at each of a plurality of intersections constituting a wireless communication system communicate wirelessly with a vehicle-mounted communication device 3 of a vehicle traveling around the roadside vehicle (road vehicle ( Inter-roadway communication) is possible. Each roadside communication device 2 is also capable of wireless communication (inter-road communication) with other roadside communication devices 2 that are located within a predetermined range within which their transmission waves reach.
The in-vehicle communication device 3 that also constitutes a wireless communication system can perform wireless communication with the roadside communication device 2 and can perform wireless communication (vehicle-to-vehicle communication) with other in-vehicle communication devices 3 using a carrier sense method. is there.

As described above, in the ITS of this embodiment, communication between the vehicle-mounted communication devices 3 (vehicle-to-vehicle communication) and communication between the road-side communication device 2 and the vehicle-mounted communication device 3 (from “road” to “car”). Wireless communication is used for the communication between the vehicle and the “road” from the “car” to the “road”.
In addition, although the central apparatus 4 provided in the traffic control center can perform bidirectional communication with each roadside communication device 2 by wire, wireless communication may be performed between these devices.

A dedicated time slot (first slot SL1 in FIG. 3) for wireless transmission by itself is assigned to the roadside communication device 2 by the TDMA system, and a time slot other than this time slot (second slot in FIG. 3). No wireless transmission is performed for SL2). That is, the radio resource is divided in the time domain, thereby setting the time slot.
Further, the time zone other than the time slot for the roadside communication device 2 is opened as a transmission time by the CSMA method for the in-vehicle communication device 3.
Although the roadside communication device 2 and the vehicle-mounted communication device 3 use the same frequency band for communication, the transmission time zones of the roadside communication device 2 and the vehicle-mounted communication device 3 are distinguished as described above. A collision between the transmission signal and the transmission signal by the in-vehicle communication device 3 can be avoided.

  The roadside communication device 2 and the in-vehicle communication device 3 are not particularly limited with respect to reception of transmission signals. Accordingly, the roadside communication device 2 can receive transmission signals from the in-vehicle communication device 3 and can also receive transmission signals from other roadside communication devices 2. The in-vehicle communication device 3 can receive transmission signals from the roadside communication device 2 and other in-vehicle communication devices 3.

  The roadside communication device 2 has a time synchronization function with other roadside communication devices 2 in order to control its transmission timing. The time synchronization of the roadside communication device 2 is performed by, for example, GPS synchronization that adjusts its own clock to the GPS time, air synchronization that adjusts its own clock to a transmission signal from another roadside communication device 2, or the like.

[4. Roadside communication device)
FIG. 2 is a block diagram showing the internal configuration of the roadside communication device 2 and the in-vehicle communication device 3.
The roadside communication device 2 includes a wireless communication unit (transmission / reception unit) 21 to which an antenna 20 for wireless communication is connected, a wired communication unit 22 that performs bidirectional communication with the central device 4, and a processor (CPU) that performs communication control thereof. A central processing unit) and a storage unit 24 connected to the control unit 23, such as a ROM or a RAM.

The storage unit 24 of the roadside communication device 2 stores a computer program for realizing a transmission control method described later executed by the control unit 23, communication device IDs of the communication devices 2 and 3, slot information S6 described later, road alignment information. S7 and the like are stored.
The control unit 23 of the roadside communication device 2 temporarily stores the traffic information S2 and the road alignment information S7 received from the central device 4 received by the wired communication unit 22 in the storage unit 24 and via the wireless communication unit 21. And has a function of broadcasting.
In addition, the control unit 23 temporarily stores the vehicle information S3 received by the wireless communication unit 21 in the storage unit 24 and transfers the vehicle information S3 to the central device 4 via the wired communication unit 22, and the wireless communication unit 21 It also has a function of broadcast transmission via the network.

  Further, the control unit 23 generates slot information S6 which is allocation information of time slots used by the own device and other devices, and signal information S8 related to the color of the signal lamp at the intersection where the own device is arranged, and broadcasts it. It also has a function to transmit.

[5. (Time slot contents)
FIG. 3 is a conceptual diagram showing an example of a time slot for road-to-vehicle communication in the present embodiment. As shown in FIG. 3, in the road-to-vehicle communication, radio frames arranged side by side in the time axis direction are used.
The length of the radio frame in the time axis direction is set to 100 milliseconds, for example, and includes a first slot SL1 and a second slot SL2. Fifteen first slots SL1 and second slots SL2 are arranged alternately in the time axis direction in the radio frame.

  The first slot SL1 is a time slot assigned to the roadside communication device 2, and wireless transmission by the roadside communication device 2 is permitted in this time zone. On the other hand, the second slot SL2 is a time slot for the in-vehicle communication device 3, and since this time period is opened for wireless transmission by the in-vehicle communication device 3, the roadside communication device 2 performs wireless transmission in the second slot SL2. Absent.

Slot numbers i (i = 1 to 15 in FIG. 3) are assigned to the first slots SL1, respectively. This slot number i is incremented or decremented within the radio frame.
One of the plurality of first slots SL1 included in the radio frame is assigned to the roadside communication device 2. The roadside communication device 2 identifies which slot is assigned to the own device by the slot number i. The slot information S6 includes the slot number i associated with the roadside communication device 2 to which the slot number i is assigned and the specific information, and each communication device that has received the slot information S6 Thus, the time slot assignment of the roadside communication device 2 can be recognized.

  Since a plurality of radio frames are arranged side by side in the time axis direction as described above, the first slot SL1 for each slot number assigned to any roadside communication device 2 has a radio frame length of 1 respectively. It is periodically arranged with a period, that is, 100 milliseconds as one period. Therefore, the roadside communication device 2 performs transmission using the first slot SL1 every 100 milliseconds.

A plurality of roadside communication devices 2 can also be assigned to the same slot. In this case, the positional relationship between the roadside communication devices 2 to which slots are assigned in an overlapping manner requires that the wireless transmission areas (service areas) do not overlap and are sufficiently separated.
When the service areas of the roadside communication devices 2 overlap or when the service areas do not overlap, but the positional relationship between the roadside communication devices 2 is close in distance, different slots are assigned. This is to prevent interference caused by transmission signals of other roadside communication devices 2 in the service area of each roadside communication device 2.

  That is, as will be described later, the roadside communication devices 2 in a positional relationship that may cause interference with each other by belonging to the same interference area are different in time as in the roadside communication devices 2A and 2B shown in FIG. A slot is assigned. In the roadside communication device 2A, the first slot SL1 of slot number 1 is assigned, and in the roadside communication device 2B, the first slot SL1 of slot number 2 is assigned. As described above, since the first slots SL1 that do not overlap each other are allocated, it is possible to prevent the interference from occurring even if the positional relationship is likely to cause the interference.

  As described above, in the above system, the radio resources are allocated to the respective roadside communication devices 2 by allocating the plurality of first slots SL1 set in the time axis direction by the TDMA method to the respective roadside communication devices 2. .

[6. (In-vehicle communication device)
Returning to FIG. 2, the in-vehicle communication device 3 includes a communication unit (transmission / reception unit) 31 connected to the antenna 30 for wireless communication, a control unit 32 including a processor that performs communication control on the communication unit 31, and the like. And a storage unit 33 including a storage device such as a ROM or a RAM connected to the control unit 32.
The storage unit 33 stores a computer program for communication control executed by the control unit 32, communication device IDs of the communication devices 2 and 3, and the like.

The control unit 32 of the in-vehicle communication device 3 causes the communication unit 31 to perform wireless communication based on the carrier sense method for inter-vehicle communication, and the communication control function in the time division multiplexing method like the roadside communication device 2 is I don't have it.
Accordingly, the communication unit 31 of the in-vehicle communication device 3 always senses the reception level of a predetermined carrier frequency, and when the value is equal to or greater than a certain threshold, wireless transmission is not performed, and when the value is less than the threshold Only intended to perform wireless transmission.

  Further, when the in-vehicle communication device 3 receives the slot information S6 from the roadside communication device 2, a time other than the time slot (first slot SL1 in FIG. 3) dedicated to the roadside communication device 2 described in the slot information S6. Radio transmission by the carrier sense method is performed using the band (second slot SL2 in FIG. 3).

In addition, the control unit 32 of the in-vehicle communication device 3 wirelessly transmits the vehicle information S3 including the current position, direction, speed, and the like of the vehicle 5 (the in-vehicle communication device 3) to the outside via the communication unit 31 by broadcast. .
Further, the control unit 32 receives the traffic information S2, the vehicle information S3, the road alignment information S7, and the signal information S8 transmitted from the roadside communication device 2, and transmits from the other vehicle 5 (in-vehicle communication device 3). The vehicle information S3 is received, and based on these pieces of information, there is also a function of performing safe driving support control that avoids a right-handed collision or a head-on collision.

[7. (How to estimate the required number of time slots)
When there is a sufficient distance between the adjacent roadside communication devices 2 and the service areas do not overlap with each other, there is no interference between the roadside communication devices 2 having such a relationship. There are no restrictions on allocation.
However, when the distance between the adjacent roadside communication devices 2 is relatively short and the service areas overlap each other, if the same first slot SL1 is assigned to each roadside communication device 2 (same slot number), the service area Therefore, it is necessary to assign different (different slot numbers) first slots SL1 between the roadside communication devices 2 having such a positional relationship.

  Here, as shown in FIG. 3, there is a limit to the number of first slots SL1 that can be set in one radio frame. For this reason, when applying the above system on an actual road, as described above, the roadside communication devices in a positional relationship in which interference occurs are restricted by assigning different time slots to each other. When time slots are assigned to each roadside communication device in the area, it is necessary to know in advance how many time slots are required.

  Hereinafter, as one embodiment of the present invention, when the above system is applied to a predetermined area, when the first slot SL1 is assigned to each roadside communication device 2 in the area, how many first slots A method of estimating whether SL1 is necessary or the necessary number will be described.

[7.1 Setting of installation candidate points and determination of target area]
FIG. 4 is a flowchart showing a method for estimating the required number of first slots SL1 according to an embodiment of the present invention.
In this method, first, the road shape of the area to which the system is applied is specified, and installation candidate points for installing the roadside communication device 2 are set (step S1).
FIG. 5 is a diagram showing a road shape in an area for setting a target area. In FIG. 5, the upward direction on the paper is the north direction.
For example, the installation candidate point V (installation position) of the roadside communication device 2 is set from the shape of the road E provided in the area M shown in FIG. The installation candidate point V is basically set at an intersection, and is also set at a point where a signal or the like is provided, although it is not an intersection.

Next, a target area P that is an estimation target of the required number of time slots is determined from within the area M (step S2 in FIG. 4). In the present embodiment, the case where the entire area M where the intersections shown in FIG.
In the target area P, as shown by the alternate long and short dash line in FIG. 5, the road shape can be approximated to a lattice shape, and the installation candidate point V can be approximated to an intersection of the lattice-shaped road shape.

In FIG. 5, there is a point VS that is not set as the installation candidate point V even though the one-dot chain line in the vertical direction intersects with the one-dot chain line in the horizontal direction. It can be said that it is an estimated installation candidate point that can be estimated from the installation candidate point V, and this is also treated as the installation candidate point V.
The point VS as the estimated installation candidate point may be a case where no traffic signal happens to be installed at a corresponding location on the road E, and there is a possibility that a traffic signal will be installed in the future or a road will be installed to become an intersection. Because there is.
As a result, although it is unlikely that a roadside communication device will be installed at present, the allocation of radio resources can also be considered for positions that may be installed in the future.

FIG. 6 is a diagram illustrating models of the road E and the installation candidate points V in the target area P of the present embodiment. As shown in FIG. 6, the road E and the installation candidate points V in the target area P are approximated in a lattice shape.
Since the method of this embodiment is a slot allocation method related to interference between roadside communication devices, the target area P and the interference area and unit area described later are specified in units of installation candidate points V. be able to. This is because the identification of each area can be performed on a model as shown in FIG.

[7.2 Identification of interference area]
Next, the interference area of the roadside communication device 2 in the target area P is specified (step S3 in FIG. 4). The interference area is an area in which one roadside communication device 2 interferes with another roadside communication device 2 other than its own device in the target area P. The roadside communication devices 2 located in the same interference area are in a relationship in which interference occurs due to overlap between the service areas. That is, this interference area indicates that the roadside communication devices 2 located in the area interfere with each other, and indicates the interference relationship between the roadside communication devices 2 in the target area P.
The interference area is specified for each of a plurality of different directions with reference to the installation candidate point V where the roadside communication device 2 is installed. Further, since the interference area is determined based on the interference between the roadside communication devices 2, as described above, the interference area can be specified in units of installation candidate points V.
FIG. 7 is a diagram illustrating an interference area K when one roadside communication device 2 is used as a reference. In the drawing, each white circle indicates an installation candidate point V. A hatched circle indicates an installation candidate point V where the roadside communication device 2 serving as a reference is installed. In the figure, the upward direction on the paper is the north direction.

In the illustrated example, the interference area K is grasped for each of four different directions: an interference area K1 in the north-south direction, an interference area K2 in the east-west direction, an interference area K3 in the northeast-southwest direction, and an interference area K4 in the northwest-southeast direction. .
The north-south interference area K1 extends from the reference installation candidate point V in a range including three installation candidate points V in the south direction and the north direction, respectively. The east-west interference area K2 extends from the reference installation candidate point V in a range including two installation candidate points V in the east and west directions. The northeast-southwest interference area K3 extends from the reference installation candidate point V in a range including one installation candidate point V in each of the northeast direction and the southwest direction. The interference area K4 in the northwest-southeast direction extends from the reference installation candidate point V in a range including one installation candidate point V in each of the northwest direction and the southeast direction.

In the interference area K, for example, the propagation loss inside and outside the service area when the roadside communication device 2 is installed at all the installation candidate points V in the target area P is investigated, and each installation candidate point V is based on the investigation result. The interference area K is identified.
Furthermore, the interference area K of the maximum range is specified for each direction from the interference areas K of the specified installation candidate points V.
In the present embodiment, it is assumed that the interference area K shown in FIG. 7 is the interference area K in the maximum range in all directions in the specified interference area K.

  The transmission output of the roadside communication device 2 when grasping the interference area K is determined in advance so as to be an appropriate value in the target area P, and is set to the predetermined value. This is because when the transmission output of the roadside communication device 2 fluctuates, the service area also fluctuates.

  When the interference area K of each roadside communication device 2 is specified with respect to each direction, the size of the interference area K of the maximum range among the specified interference areas K of each roadside communication device 2 with respect to each direction is further determined. Identify.

In order to specify the size of the maximum interference area K, the interference area K in each direction is patterned.
FIG. 8 is a diagram showing a mode in which the interference area K is patterned in each direction. (A) is a pattern of the interference area K1 in the north-south direction, and (b) is a pattern of the interference area K2 in the east-west direction. (C) has shown the pattern of the interference area K3 of the northeast-southwest direction interference area K3, and the interference area K4 of the northwest-southeast direction. In the drawing, each white circle indicates an installation candidate point V.

As shown in FIG. 8A, the interference area K1 in the north-south direction is divided into three patterns including a pattern including four installation candidate points V, a pattern including three, and a pattern including two. Among these, a pattern including four installation candidate points V is a pattern of the maximum range of the interference area K (maximum range pattern) in the north-south direction, and the size can be specified as four installation candidate points V.
As shown in FIG. 8B, the interference area K2 in the east-west direction is divided into two patterns including a pattern including three installation candidate points V and a pattern including two. Among these, the pattern including three installation candidate points V is the maximum range pattern of the interference area K in the east-west direction, and the size thereof can be specified as three installation candidate points V.
As shown in FIG. 8C, the northeast-southwest interference area K3 and the northwest-southeast interference area K4 are only patterns including two installation candidate points V, respectively. And the maximum range pattern of the interference area K in the northwest-southeast direction. The size can be specified as two installation candidate points V.

As described above, the size of the maximum interference area K is specified for each direction.
In the present embodiment, the size of the maximum range of the interference area K is specified, but it is not always necessary to specify the size of the maximum range. As will be described later, the size of the interference area K in the maximum range is used to set the unit area U. For example, the size of the interference area of each installation candidate point V is compared with other sizes. The maximum size after removing values that are recognized as abnormal can be specified as the size of the interference area K in the maximum range, or a statistically valid value can be obtained.

  Moreover, although the case where the interference area K of all the installation candidate points V in the target area P is specified is shown above, the interference area K of all the installation candidate points V is not necessarily specified, Of the installation candidate points V in the target area P, points that do not clearly need to specify the interference area K or points that are difficult to investigate may not be specified.

[7.3 Setting of unit area]
Next, a unit area U is set based on the size of the maximum range pattern (maximum range interference area K) of the interference area K (step S4 in FIG. 4). The unit area U includes a predetermined number of roadside communication devices 2 (installation candidate points V) and is an element constituting the target area P. In the present embodiment, the unit area U constitutes the target area P by arranging a plurality of adjacent units along the north-south direction and the east-west direction.

The unit area U is set to an area in which the size of each direction matches or includes the size of each direction of the maximum range pattern of the interference area K specified above.
In other words, the unit area U is an area that can include the interference area K pattern in each direction to aggregate and simplify the interference relationships in the target area P.

  FIG. 9 is a diagram illustrating an example of the unit area U. As illustrated in FIG. In the drawing, each white circle indicates an installation candidate point V.

As a result of the identification by the interference area identifying step, the maximum range pattern of the interference area K in the north-south direction is equivalent to four installation candidate points V, and the maximum range pattern of the interference area K in the east-west direction is equivalent to three installation candidate points V. Then, each side has a rectangular shape along the north-south direction and the east-west direction.
Thereby, the unit area U includes the size of the maximum range pattern of the interference area K in the northeast-southwest direction and the northwest-southeast direction.
Thus, the unit area U is set to an area that matches the size of the maximum range pattern of the interference area K in the north-south and east-west directions, and includes all the patterns of the interference area K shown in FIG. it can. In this way, the unit area U can summarize and simplify the interference relationships in the target area P.

[7.4 Allocation of first slot]
As described above, when the unit area U is set, next, the first slot SL1 assigned to each roadside communication device 2 installed at the installation candidate point V in the unit area U is determined (step S5 in FIG. 4). ).
Here, in the allocation of the first slot SL1 for each of the installation candidate points V in the unit area U, the roadside communication devices 2 arranged at the installation candidate points V in the unit area U do not interfere with each other. One slot SL1 is allocated.
Further, when assigning the first slot SL1, no matter which position of the interference area K in each direction that can be arranged in the unit area U is arranged in any position in the unit area U, the installation candidates included in the interference area U The first slot SL1 assigned to the point V is assigned so that the slot numbers are different from each other.

More specifically, the allocation is performed so as to satisfy the following conditions (a) and (b).
(A) The installation candidate points V belonging to the same interference area K when a plurality of the maximum range patterns of the interference area K in one direction are arranged in the unit area U so that the unit area U is filled. The first slot SL1 assigned to (the roadside communication device 2 installed in) is assigned to be different first slots SL1.
(B) The allocation satisfies the condition (a) regardless of the direction of the maximum range pattern of the interference area K in any direction.

  When the first slot SL1 is assigned to the unit area U under the above conditions, the first slot SL1 is assigned to each installation candidate point V so that the installation candidate points V included in the unit area U do not interfere with each other. In addition, when the target area P is configured by arranging a plurality of unit areas U having the same allocation adjacent to each other, the first slot SL1 allocated to each installation candidate point V is adjacent to the unit area U including itself. Can be assigned differently to the first slot SL1 of the installation candidate point V of the unit area U. The roadside communication devices 2 of the installation candidate points V interfere with each other between the adjacent unit areas U. Can be assigned to the first slot SL1.

FIG. 10A shows a case where only the maximum range pattern of the interference area K1 in the north-south direction is arranged in the unit area U so that the unit area U is filled for each of the installation candidate points V included in the unit area U. It is a figure which shows an example. Each white circle indicates an installation candidate point V.
In FIG. 10A, for each installation candidate point V included in the unit area U, a maximum range pattern including four installation candidate points V among the patterns of the interference area K1 in the north-south direction is arranged. . As shown in FIG. 10A, in the unit area U, three maximum range patterns of the interference area K1 are arranged. In the installation candidate points V (installed in the roadside communication device 2) belonging to each of these interference areas K1, the first slots SL1 assigned to the installation candidate points V belonging to the same interference area K1 are mutually based on the above limitation. The first slot SL1 is assigned so that the first slot SL1 is different.

  When the first slot SL1 is assigned as described above, if the unit areas U having the same assignment are arranged adjacently in the north-south direction, the installation candidate point V2 belonging to the adjacent unit area U2 is similarly assigned in FIG. Therefore, the allocation pattern is composed of four different first slots SL1 and is regularly arranged in the north-south direction. Due to such a relationship, the installation candidate point V10 of the adjacent unit area U10 and the installation candidate point V of the unit area U are always different from each other within the range of the widest pattern of the interference area K1 in the north-south relationship. The first slot SL1 is assigned.

FIG. 10B shows a case where only the maximum range pattern of the interference area K2 in the east-west direction is arranged in the unit area U so that the unit area U is filled for each of the installation candidate points V included in the unit area U. It is a figure which shows an example.
In FIG. 10B, for each installation candidate point V included in the unit area U, a maximum range pattern including three installation candidate points V among the patterns of the interference area K2 in the east-west direction is arranged. .

Similarly in this case, the first slot SL1 is assigned so that the first slots SL1 assigned to the installation candidate points V belonging to the same interference area K2 become different first slots SL1 based on the restriction.
Accordingly, in FIG. 10B, the installation candidate point V11 of the adjacent unit area U11 and the installation candidate point V of the unit area U have the widest pattern in the interference area K2 in the east-west relationship as well. Within the range, the first slots SL1 different from each other are always assigned.

FIG. 11 illustrates an example when only the maximum range pattern of the oblique interference area is arranged in each unit area U so that the unit area U is filled for each of the installation candidate points V included in the unit area U. (A) shows the case where the maximum range pattern of the interference area K3 in the northeast-southwest direction is arranged, and (b) shows the case where the maximum range pattern of the interference area K4 in the northwest-southeast direction is arranged. Yes.
In the present embodiment, the maximum range pattern of the interference areas in the oblique directions (northeast-southwest direction and northwest-southeast direction) is only a pattern including two installation candidate points V.
Therefore, when the maximum range pattern of the interference area K in the oblique direction is arranged at each installation candidate point V in the unit area U, as shown in FIG. It is necessary to arrange two patterns including the installation candidate points V adjacent to both sides in the direction.

The unit area U is adjacent to each other in the north-south direction and the east-west direction, which coincides with the direction in which the unit area U is adjacently arranged, by setting different slots within the maximum range pattern applied in the unit area U. Even in the relationship with the unit area U, the allocation does not overlap within the interference area pattern.
However, since the maximum range pattern of the interference area in the oblique direction does not match the range of the unit area U and both ends, the unit area U does not match the direction in which the unit area U is arranged adjacently. It is necessary to apply two patterns to one installation candidate point V per direction.
Therefore, the first slot SL1 is assigned to each of the two patterns so that the first slots SL1 assigned to the installation candidate points V belonging to the same interference area K3 become different first slots SL1.

  Here, in FIGS. 11A and 11B, the interference areas K3 and K4 include the installation candidate points V outside the range of the target unit area U. However, since the allocation of the first slot SL1 in the other adjacent unit area U and the allocation of the first slot SL1 in the target unit area U are the same, the target area U corresponding to the installation candidate point V outside the range. Can be regarded as being included in the interference area K.

  FIG. 12 is a diagram illustrating the relationship between the installation candidate points V outside the target unit area U and the installation candidate points V within the target unit area U. As shown in FIG. 12A, when the interference area K3 (K3-1, K3-2) in the northeast-southwest direction is applied, the installation candidate point located at the upper left corner of the page in the target unit area U. V1 belongs to the same interference areas K3-1 and K3-2 as the installation candidate points V12 and V13 outside the target unit area U. Therefore, it is necessary to assign different first slots SL1 to the installation candidate points V1 between the installation candidate points V12 and V13 outside the range of the target unit area U.

Here, since the allocation of the first slot SL1 of the adjacent unit area U including the installation candidate point V12 outside the range is the same as the allocation of the first slot SL1 of the target unit area U, the installation candidate points outside the range V12 has the same positional relationship as the installation candidate point V2 in the target unit area U.
Therefore, when the first slot SL1 is assigned between the installation candidate point V1 of the target unit area U and the installation candidate point V12 of the unit area U outside the range, the installation in the target unit area U is performed. What is necessary is just to allocate so that it may become different 1st slot SL1 between candidate point V1 and V2.
Similarly, when the first slot SL1 is assigned between the installation candidate point V1 of the target unit area U and the installation candidate point V13 of the unit area U outside the range, What is necessary is just to allocate so that it may become different 1st slot SL1 between the installation candidate points V1 and V3.

In the case of FIG. 12B, when the interference area K4 (K4-1, K4-2) in the northwest-southeast direction is applied, the installation candidate point V1 is the installation candidate point V14 outside the target unit area U. And, it is necessary to allocate a different first slot SL1 with the installation candidate point V6 within the range of the target unit area U.
Since the installation candidate point V14 outside the range is in the same positional relationship as the installation candidate point V5 in the target unit area U, between the installation candidate point V1 in the target unit area U and the installation candidate point V14 outside the range. Thus, when assigning the first slot SL1, it is only necessary to assign different first slots SL1 between the installation candidate points V1 and V5 in the target unit area U.

  The same applies to the other installation candidate points V in the target unit area U. When a different first slot SL1 is allocated to the installation candidate point V outside the range, the corresponding target unit area U Is assigned to the installation candidate point V.

As described above, the first slot SL1 is assigned to each installation candidate point V included in the unit area U so that the assignment satisfies all the conditions (a) and (b) shown in FIGS. assign.
Thus, even if the interference areas K3 and K4 are arranged at positions where both the installation candidate points V in the unit area U and the installation candidate points V outside the unit area U are included, they are included in the interference areas K3 and K4. The first slots SL1 assigned to the installation candidate points V are assigned such that the slot numbers are different from each other.

  For assignment of the first slot SL1 of each installation candidate point V included in the unit area U (the roadside communication device 2 installed in the unit area U), for example, a search is performed using a workstation or a personal computer. The calculation may be performed, or the calculation can be performed using other search algorithms.

  As described above, there is a limit to the number of first slots SL1, and there is a demand for saving radio resources as much as possible for future expansion and the like. For this reason, the necessary number of first slots SL1 necessary for allocation is calculated to be a minimum value.

  FIGS. 13 and 14 are diagrams for explaining an example of a method of assigning the first slot SL1 to each installation candidate point V included in the unit area U. FIG. In FIG. 13 and FIG. 14, in order to specify the position of each installation candidate point V in the unit area U, numbers M (= 1, 2, 3) in order from the left for each column in the unit area U. And numbers N (= 1 to 4) are assigned to each row in order from the bottom.

In this assignment method, first, any one installation candidate point V in the unit area U is selected as a reference point, and a first slot SL1 having an arbitrary slot number is assigned. In FIG. 13A, (M, N) = (1, 1) is selected as a reference point, and the first slot SL1 with slot number “1” is assigned.
At this time, a non-interference installation candidate point that is an installation candidate point V that cannot cause interference with the reference point is identified from the relationship between the interference areas related to the reference point. In this embodiment, as shown in FIG. 13A, two locations (M, N) = (2, 3) and (3, 3) are specified as non-interference installation candidate points.

  When the non-interfering installation candidate point is specified, as shown in FIG. 13B, the first slot having the same slot number as the reference point is set as one of the non-interfering installation candidate points. Assign SL1. In FIG. 13B, the first slot SL1 having the same slot number “1” as the reference point is assigned to the non-interference installation candidate point of (M, N) = (2, 3). Up to this point, in the unit area U, the first slot with the slot number “1” at (M, N) = (1,1) and (M, N) = (2,3) as reference points. SL1 is assigned.

Next, (M, N) = (2, 1) is newly selected as the reference point, and a first slot number different from the slot number “1” of the previous reference point is selected for the new reference point. The slot SL1 (slot number “2”) is assigned. In this case as well, as in the case of the previous reference point, the non-interference installation candidate point is specified, and the first slot SL1 having the same slot number “2” as the reference point is assigned.
Further, (M, N) = (3, 1) is selected as the reference point, and the first slot SL1 (slot number “3”) having a slot number different from each of the reference points is similarly assigned.
As a result, as shown in FIG. 13C, the allocation of the first slot SL1 is completed for the row of N = 1 and the row of N = 3.

  Next, allocation is performed by paying attention to N = 2 rows. The installation candidate points V belonging to the N = 2 rows are slots other than the slot numbers “1” to “3” and different from each other due to the allocation of the N = 1, 3 rows and the relationship between the interference areas. It is necessary to assign the numbered first slot SL1. Therefore, as shown in FIG. 14A, the slot number “4” is used for (M, N) = (1, 2), the slot number “5” is used for (M, N) = (2, 2), The first slot SL1 with slot number “6” is assigned to (M, N) = (3, 2).

  Regarding the allocation of N = 4 rows, the installation candidate points V that are in the relationship of the non-interference installation candidate points are identified for each of the installation candidate points V of N = 2, and the relationship of the specified non-interference installation candidate points is established. The first slot SL1 having the same slot number is assigned to the installation candidate point V. In FIG. 14B, slot number “6” is used for (M, N) = (1, 4), slot number “4” is used for (M, N) = (2, 4), and (M, N). = (3, 4) is assigned the first slot SL1 with slot number “5”.

  As described above, allocation can be performed to each installation candidate point V included in the unit area U using the first slots SL1 having six different slot numbers.

  FIG. 15 is a diagram illustrating an example of assignment of the first slot SL1 to the unit area U obtained as a result of the above calculation. The numbers shown in the circles indicating the installation candidate points V in the figure are slot numbers, and in the example shown in the figure, “6” is obtained as the minimum value of the required number of first slots SL1 required for allocation. It was. Note that the allocation in FIG. 15 shows a case where the allocation pattern is different from those in FIGS.

FIG. 15A shows the relationship between the maximum range pattern of the north-south interference area K1 arranged in the unit area U and the slot number of the first slot SL1 assigned to each installation candidate point V. FIG. As shown in the figure, it can be seen that the first slot SL1 having a different slot number is assigned to the four installation candidate points V included in the maximum range pattern of the same interference area K1.
FIG. 15B shows the relationship between the maximum range pattern of the east-west interference area K2 arranged in the unit area U and the slot number of the first slot SL1 assigned to each installation candidate point V. As shown in the figure, the first slot SL1 having a different slot number is assigned to the three installation candidate points V included in the maximum range pattern of the same interference area K2.
15C and 15D show the maximum range pattern of the interference areas K3 and K4 in the northeast-southwest direction and the northwest-southeast direction arranged in the unit area U, and the first assigned to each installation candidate point V. The relationship with the slot number of one slot SL1 is shown. As shown in the figure, the first slot SL1 having a different slot number is assigned to two installation candidate points V included in the maximum range pattern of the same interference areas K3 and K4.

As described above, it can be seen from FIG. 15 that the allocation of the first slot SL1 to the unit area U satisfies the restriction determined by the arrangement of the interference area K in each direction.
As described above, the unit area U is arranged in the first slot so that the installation candidate points V do not interfere with each other between the adjacent unit areas U even if a plurality of the unit areas U are adjacently arranged to constitute the target area P. SL1 is assigned.

FIG. 16 is a diagram showing a part of an area formed by arranging a plurality of unit areas U to which the above assignment is applied.
As shown in FIG. 16, even if the interference area K in each direction is arranged at any installation candidate point V, the first slot SL1 having a different slot number is assigned to the installation candidate point V belonging to the same interference area K. It can be seen that

[7.5 Acquisition of minimum required number of first slots]
In the calculation for determining the first slot SL1 to be allocated to the installation candidate point V in the unit area U, the necessary number of the first slots SL1 necessary for the allocation is calculated to be the minimum value as described above. To do.
As described above, the unit areas U based on the allocation of the first slot SL1 obtained by the calculation are arranged between the adjacent unit areas U even if a plurality of unit areas U are adjacently arranged to constitute the target area P. Since the candidate point V does not cause interference, the minimum value of the required number of first slots SL1 required for allocation in the unit area U is the same as the minimum value of the required number of first slots SL1 required for allocation in the target area P. It becomes.
Therefore, the minimum value of the required number of first slots SL1 required for allocation in the unit area U obtained by the above calculation is estimated for the minimum value of the required number of first slots SL1 required for allocation in the target area P. Obtained as a value (step S6 in FIG. 4).

[8. (Effect)
In the case where the first slot SL1 that is configured as described above and is a plurality of different radio resources that do not overlap each other is assigned to each of the installation candidate points V (the roadside communication device 2 installed in the target area P), This is a method for estimating the required number of slots SL1, and the roadside communication devices 2 installed at the respective installation candidate points V are set in a plurality of different interference areas K that interfere with other roadside communication devices 2 in the target area P. An interference area specifying step (step S3 in FIG. 4) for specifying each direction and a predetermined number of roadside communication devices 2 are installed, and the sizes of the plurality of different directions are set in the specified interference area K. The unit area setting step for setting the unit area U based on the sizes of the plurality of different directions, and the installation candidate points V included in the unit area U do not interfere with each other. As described above, the allocation step (step S5 in FIG. 4) for allocating the first slot SL1 to each installation candidate point V, and the number (the minimum value) of the first slots SL1 necessary for allocation in the allocation step are as follows. A step (step S6 in FIG. 4) of obtaining as an estimated value of the required number (minimum value) of the first slots SL1 allocated to the plurality of roadside communication devices 2 installed in the target area P. Yes.

  According to the method configured as described above, the installation candidates are arranged so that the installation candidate points V included in the unit area U set based on the size of the interference area K do not interfere with each other in the allocation step. Since the first slot SL1 is assigned to the point V, even if a plurality of unit areas U are arranged adjacent to each other, the first slot SL1 of each installation candidate point V is another unit adjacent to the unit area U including its own device. The first slot SL1 can be assigned different from the first slot SL1 of the installation candidate point V installed in the area U. Thereby, not only within the unit area U but also between the adjacently arranged unit areas U, the first slot SL1 can be assigned such that the mutual installation candidate points V do not give interference. As a result, when the necessary number of first slots SL1 necessary for assigning each installation candidate point V in the unit area U is obtained, the installation candidate points V in the target area P formed by arranging a plurality of unit areas U adjacent to each other are obtained. An estimated value of the required number of first slots SL1 to be allocated can be obtained, and the minimum value can be easily obtained.

  Furthermore, in the present embodiment, the allocation step (step S5 in FIG. 4) is included in the interference area K regardless of the position in the unit area U where the interference area K in each direction is arranged. The first slot SL1 is assigned to each installation candidate point V in the unit area U so that the first slots SL1 assigned to the installation candidate points V have different slot numbers.

  In this case, the allocation of the first slot SL1 to each installation candidate point V included in the unit area can be limited while avoiding interference between the installation candidate points V due to the mutual interference area K, The number of first slots SL1 required for allocation in the allocation step, that is, the estimated value of the required number of first slots SL1 allocated to the installation candidate points V can be obtained as a smaller value.

[9. Modification of unit area setting and slot allocation)
FIG. 17 is a diagram illustrating installation candidate points in the target area P according to the modification. FIG. 17 shows a part of the target area P, and each of the 16 installation candidate points V is approximated by a lattice model. In the figure, a circle is an installation candidate point V, and an alphabet in the circle is for specifying the installation candidate point V. Symbols A to P are allocated to the 16 installation candidate points V. Hereinafter, in the description of FIG. 17, the installation candidate points are indicated as installation candidate points V (A) to V (P).

  In the unit area setting step of the above embodiment, the unit area U is set to an area that matches the maximum range in each direction of the interference area K, and is set within the minimum range that can include the interference area K. In this modification, the unit area U is set without considering the exceptional interference area (interference relationship) specified by some installation candidate points V in the whole.

In FIG. 17, the interference area K at each installation candidate point V is specified as extending to the installation candidate points V adjacent in a total of eight directions of up, down, left, and right and four diagonal directions, and is represented by a broken line in the drawing. Yes.
In addition, regarding the installation candidate points V (C), V (E), and V (K) in the figure, in addition to the adjacent eight directions, as shown by the solid line in the figure, the installation candidate points V (E) and the installation candidates The interference area K5 is configured with the point V (C), and the interference area K6 is configured with the installation candidate point V (E) and the installation candidate point V (K). It has been identified.

  Here, when setting the unit area U in consideration of the interference relationship between the installation candidate points V (C), V (E), and V (K), as in the unit area U21 shown in FIG. The installation candidate points V are set in a range including 9 places of 3 × 3. The unit area U21 set in this way can include interference relationships (interference areas K5, K6) between the installation candidate points V (C), V (E), and V (K).

  However, in the unit area setting step of this modification, the interference area K specified for each of a plurality of different directions is divided into a majority area where there are many identical things and a minority area where the number is smaller than the majority area. And a unit area U is set based on the majority area.

More specifically, in FIG. 17, the interference area K1, the interference area K2 in the east-west direction, the interference area K3 in the northeast-southwest direction, and the interference areas K3 extending in a total of eight directions of up, down, left and right and four diagonal directions, Since the interference area K4 in the northwest-southeast direction is configured by each of the installation candidate points V, there are many identical relationships (interference areas K1 to K4). Therefore, these interference areas K1 to K4 are classified as majority areas.
On the other hand, in the interference areas K5 and K6, assuming that there are only a few interference relationships (interference areas K) in the target area P that can be seen at the installation candidate points V (C), V (E), and V (K), The number is smaller than the interference areas K1 to K4, which are the majority areas, and is classified as a minority area.

  Therefore, in this modification, as shown in FIG. 17, the unit area U22 is set based on the interference areas K1 to K4 classified as the majority area. In this case, the unit area U22 is set to a range in which the installation candidate points V include 4 locations of 2 × 2.

  In this modification, in the allocation step performed after the unit area setting step, each of these installation candidate points is set so that the installation candidate points V included in the unit area set based on the majority area do not interfere with each other. Radio resources are allocated to V. Thereafter, the radio resource of the installation candidate point V included in the minority area is allocated so that the installation candidate point V included in the minority area does not cause interference.

FIG. 18A is a diagram illustrating an example in which radio resources are allocated to the respective installation candidate points V by the unit areas U22 set based on the interference areas K1 to K4 classified as the majority areas. In the figure, the circles indicate the installation candidate points V, and the numbers in the circles indicate the slot numbers of the first slots SL1 assigned to the installation candidate points V.
The four installation candidate points V included in each unit area U22 are assigned the first slots SL1 having different slot numbers (0 to 3) so as not to interfere with each other. As with the other installation candidate points V, the slot allocation is performed for the installation candidate points V (C), V (E), and V (K) included in the interference areas K5 and K6 based on the unit area U22. .
In this case, since the unit area U22 is set based on a majority area that exists in large numbers, in the subsequent allocation step, the regularity in performing slot allocation is increased, which is simplified and facilitated.

In FIG. 18A, even if the unit area U22 is set and the slot is assigned, the installation candidate points V (C), V (E), and V (K) included in the interference areas K5 and K6 are different from each other. Since the first slot SL1 having the slot number is assigned, interference due to the interference relationship indicated by the interference areas K5 and 6 does not occur.
As a result of setting the unit area U22 and performing slot assignment, when interference occurs due to the interference relationship of the minority area, the installation candidate point V included in the minority area is different from the other installation candidate points V. Radio resources of the installation candidate points V included in the minority area are allocated so as not to interfere with each other.

FIG. 18B is a diagram showing an example in which radio resources are allocated to the respective installation candidate points V by the unit area U21 set in consideration of the interference relationship of the interference areas K5 and 6 classified as minority areas. is there.
In FIG. 18B, the first slots SL1 having different slot numbers (0 to 8) are allocated so that the nine installation candidate points V included in each unit area U21 do not interfere with each other. Therefore, the required number of first slots SL1 in this case is “9”.

On the other hand, in this modified example, as shown in FIG. 18A, since the allocation is performed by the unit area U22 including four installation candidate points V, the required number of the first slots SL1 is “4”.
In order to eliminate interference in the minority area, the first slot SL1 may be further required. However, since the interference relationship by the minority area is a small number and exceptional, it is about 1 to 2 pieces. It is possible to cope individually by allocating the slots to only necessary areas, and the number of necessary slots is not greatly increased. Therefore, in this modification, the number of necessary slots can be minimized.

  As described above, according to the present modification, the unit area U is set based on the majority area. Therefore, in the subsequent allocation step, radio resource allocation is simplified and facilitated. Furthermore, radio resources are allocated separately for the installation candidate points V included in the minority area. However, since the radio resources are allocated for the installation candidate points V included in the minority area are small, for example, the minority group Even if exceptional processing such as allocation of radio resources for an area is performed, the entire allocation step is facilitated.

[10. About the placement of each candidate point for installation)
In each of the above-described embodiments, the position of each candidate installation point V on the road is approximately applied to a model representing the road shape in a grid, and the installation is considered to be installed at the intersection of the grid road A case where each area is specified by the candidate point V is shown.
It is necessary to arrange and represent the installation candidate points V in a lattice model in order to specify each area and facilitate other processing.
On the other hand, the positional relationship between each installation candidate point V installed on an actual road is complicated, and the interference area (interference relationship) is also complicated.
In the case of the above embodiment, the installation candidate points V are arranged and represented in the lattice model based on the positional relationship while considering the interference relationship between the installation candidate points V. Can also be expressed by being arranged in a lattice model based on the actual positional relationship on the road and the interference relationship.

Hereinafter, a process of representing each installation candidate point V in a grid pattern will be described by focusing on only the interference relationship between the installation candidate points V.
FIG. 19 is a diagram showing a result of arranging each installation candidate point V in a lattice model, focusing on only the interference relationship between each installation candidate point V. FIG. 19A shows each installation candidate point V, It is the figure represented by arrangement | positioning according to an actual geographical position, (b) represented and arranged the installation candidate point V in the grid | lattice model based on the interference relationship between each installation candidate point V. It is a figure which shows an example.

  In FIG. 19, circles are installation candidate points V, and alphabets in the circles are for specifying the installation candidate points V. Symbols A to G are assigned to the seven installation candidate points V. Hereinafter, in the description of FIG. 19, each installation candidate point is indicated as installation candidate points V (A) to V (G). Moreover, the solid line K30 which connects each installation candidate point V has shown the interference relationship, and the installation candidate points V connected by this solid line K30 have the relationship which interference arises by being included in the same interference area K. .

In this process, each installation candidate point V having a geographical positional relationship and an interference relationship as shown in FIG. 19A is arranged on the lattice model based on the interference relationship. More specifically, an arrangement in which mutual interference relations are arranged on a lattice model is obtained.
The arrangement in which the interference relationship is arranged on the lattice model is, for example, an arrangement as shown in FIG. 19B, and the respective installation candidate points V are arranged on the lattice line as much as possible. An arrangement that is organized and represented in In addition, the arrangement of each installation candidate point V as shown in FIG. 19B is an arrangement obtained only by the interference relationship.
The arrangement according to the interference relationship between the respective installation candidate points V is repeatedly obtained while changing parameters and the like. Then, an optimum arrangement is adopted as a processing result from a plurality of arrangements obtained by repeated execution.

  As described above, the arrangement of the installation candidate points V based on the mutual interference relationship can be represented by the lattice model. Such a lattice model in which the installation candidate points V are regularly arranged based on the interference relationship is a virtual area where the installation candidate points V are installed, and the interference relationship does not depend on the geographical relationship. It can be said that it is a logical domain based on

Next, a process of representing each installation candidate point V in a grid pattern will be described, focusing on only the geographical positional relationship between the installation candidate points V.
FIG. 20 is a diagram illustrating a result of arranging each installation candidate point V in a lattice model, focusing only on the geographical positional relationship between each installation candidate point V. FIG. 20A illustrates each installation candidate point. FIG. 5 is a diagram showing V in an arrangement according to an actual geographical position; FIG. 5B is a diagram showing a result of grid division of a geographical area so that each installation candidate point V is arranged for each cell; (C) is a figure which shows an example which summarized the cell and arrange | positioned and represented each installation candidate point V in the grid | lattice form.

  In this process, an area in which each installation candidate point V having a geographical positional relationship and an interference relationship as shown in FIG. 20A is installed is shown in FIG. 20B. And divided into constituent grids. At this time, the installation candidate points V are divided so as to be individually arranged in a plurality of cells obtained by dividing the region.

Next, as shown in FIG. 20C, the cells in which the installation candidate points V are arranged are aggregated while maintaining the geographical positional relationship to obtain the arrangement. In FIG. 20C, a cell including the installation candidate point V (D) is fixed as a reference, and cells including other installation candidate points V are moved and aggregated.
In FIG. 20C, the arrangement of the installation candidate points V is represented as a lattice model based only on the geographical positional relationship. Therefore, the mutual interference relationship is not considered. For example, the installation candidate point V (A) and the installation candidate point V (C) are in an interference relationship with each other, but in the positional relationship, the installation candidate point V ( In this process, such an event may occur.

  As described above, the arrangement of the installation candidate points V based only on the geographical positional relationship can be represented by the lattice model. Therefore, the lattice model in which the installation candidate points V are regularly arranged based on the geographical positional relationship is a virtual area where the installation candidate points V are installed, and is based on the geographical positional relationship. It is an area.

In the above-described embodiment, while considering the interference relationship between the installation candidate points V, the installation candidate points V are arranged in the area represented by the grid model based on the geographical positional relationship (see FIG. 5, FIG. 6), the target area P, the unit area U, and the interference area K are specified in units of installation candidate points V. As described above, the installation candidate points are based on the interference relationship that is a logical area. The target area P, the unit area U, and the interference area K may be specified in units of installation candidate points V in a virtual region where the arrangement of V is expressed as a lattice model.
Similarly, the target area P, the unit area U, and the interference area K are arranged in units of installation candidate points V in a virtual region in which the arrangement of the installation candidate points V is represented as a lattice model based on the geographical positional relationship. May be specified.

[11. About the size of the unit area)
In the embodiment described above, the unit area U is set to an area that matches the size of the maximum range in each direction of the specified interference area K, so that the minimum rectangle that can include the pattern of each interference area K is Although what was set up as an example was illustrated (see FIG. 9), for example, as shown in FIG. 21, a rectangle having a range larger than the maximum range size in each direction of the specified interference area K is formed. It can also be set. FIG. 21A shows a unit area U set larger by one installation candidate point V in the east-west direction, and FIG. 21B shows two installation candidate points V in the east-west direction, installation candidates in the north-south direction. A unit area U set larger by one point V is shown.

The size of the unit area U affects the required number of slots in the subsequent allocation of the first slot SL1, but slot allocation was performed based on the unit area U set to be the smallest rectangle. The required number of slots is not always the minimum value.
When the unit area U is set, the degree of freedom of slot allocation in the unit area U is set by setting it about one or two installation candidate points V larger than the smallest rectangle that can include the pattern of each interference area K. As a result, the number of slots in slot assignment may be smaller when the unit area U set to a slightly larger rectangle is adopted than the smallest rectangle.

  Therefore, when setting the unit area U, in addition to the one set to the minimum rectangle, a plurality of patterns prepared within a range slightly larger than the minimum rectangle (about one to two installation candidate points V) should be prepared. For example, the required number of slots can be obtained for each and the best result can be adopted.

[12. Other variations)
In addition, this invention is not limited to the said embodiment.
The method for estimating the minimum value of the required number of first slots SL1 assigned to each of the installation candidate points V of the target area P according to the present invention is installed, for example, by a computer program for causing an estimation device to execute the estimation method to be installed. It can be executed using a workstation or a personal computer.

  The computer program receives the measurement result of the interference area K in the target area P of the roadside communication device 2 and specifies the size of the interference area K of the roadside communication device 2 in the target area P; A step of setting the unit area U based on the size, a step of assigning the first slot SL1 of the roadside communication device 2 installed at the installation candidate point V in the unit area U, and the installation candidate point V of the target area P, respectively Obtaining an estimated value of the required number of first slots SL1 to be allocated to the first slot SL1.

  Moreover, in the said embodiment, the case where the time slot (1st slot SL1) of a several different time slot | zone is allocated to each roadside communication apparatus 2 as a radio | wireless resource by employ | adopting a TDMA system in communication by the roadside communication apparatus 2. Although shown, the present invention can also be applied to a case where, for example, an FDMA scheme that divides a region in the frequency direction and allocates radio resources so as not to overlap in the frequency direction is adopted.

Moreover, although the case where it grasped | ascertained about the interference area K for every four directions of north-south, east-west, northeast-southwest, and northwest-southeast was shown in the said embodiment, the roadside communication apparatus installed in each installation candidate point V was shown. Depending on the degree of interference and the geographical conditions, for example, the interference area K can be grasped only in two directions of north-south and east-west directions, and directions other than the above directions can be additionally grasped. You can also.
Further, not only the direction but also the installation candidate point V determined by a specific positional relationship, such as the positional relationship of the Keima flying shape from one installation candidate point V, can be used for grasping and specifying the interference area K.

  In the above embodiment, the case where the unit area U is rectangular is illustrated, but when a plurality of the unit areas U are arranged adjacent to each other, the installation candidate points V to be installed in the target area P are the plurality of unit areas U. As long as it can be placed so that it can be included in any of the above, and can be installed with a certain regularity, it is not limited to a rectangular shape, but other shapes such as other polygons and L-shapes. You can also.

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

2 Roadside communication device K1 Interference area P Target area SL1 First slot U Unit area

Claims (11)

In a case where a plurality of different radio resources that do not overlap each other are allocated to each of a plurality of road communication devices installed in a predetermined area, a method for estimating a necessary number of the radio resources,
Based on the positional relationship of the plurality of road communication devices on the road and the interference relationship of the plurality of road communication devices, the installation positions of the plurality of road communication devices are applied to a lattice model to install the plurality of road communication devices. Setting the position to each intersection of the grids in the grid model;
An interference area specifying step of specifying an interference area in which the road communication device interferes with other road communication devices in the predetermined area in units of a plurality of different directions;
Based on the previous SL different in size for each direction is given the interference area each size, and the unit area setting step of setting the unit area including the installation position of a predetermined number,
Allocating radio resources to the installation positions where the road communication devices are installed so that the road communication devices included in the unit area do not interfere with each other;
Obtaining the number of radio resources required for allocation in the allocation step as an estimate of the required number of radio resources allocated to the installation positions of the plurality of road communication devices installed in the predetermined area; A method characterized by comprising.   2. The method according to claim 1, wherein the interference area specifying step further specifies a size of a maximum interference area for each of the plurality of different directions from the specified interference areas. The assignment step, the locatable in a unit area, the even plurality of different directions any interference area as disposed in any position of the unit area, the street communication device included in the interference area The method according to claim 1 or 2, wherein radio resources are allocated to the installation positions of the roadside communication devices in the unit area so that radio resources allocated to the installation positions are different radio resources. In the allocation step, the interference area including both the installation position of the road communication device in the unit area and the installation position of the road communication device outside the unit area may be arranged at any position. as radio resources allocated to the installation position of the road communication device included in the interference area is a different radio resource, wherein assigning the radio resources to the installation position of each road communication device of said unit area Item 3. The method according to Item 1 or 2.   The method according to any one of claims 1 to 4, wherein the predetermined area, the interference area, and the unit area are specified in units of installation positions of the plurality of road communication devices arranged in the predetermined area.   The method according to claim 5, wherein the installation position includes an estimated installation position where the road communication device estimated from the installation position can be installed.   The method according to claim 1, wherein the radio resources are time slots set side by side in a time axis direction. The unit area setting step classifies the interference areas specified for the plurality of different directions according to the relationship of interference determined by the relative positions of the installation positions constituting each interference area. among the interference area of the same relationship as the highest classifying majority area, in terms of a classification other than the majority area was minority area, the unit area based on the interference areas included in the majority area Set
In the allocation step, wireless communication is performed with respect to the installation positions of the road communication devices so that the road communication devices included in the unit area set based on the interference area of the majority area do not interfere with each other. allocate resources, then, as road communication device included in the interference area of the minority areas do not interfere with the other road communication apparatus other than the self apparatus, the interference area included in the minority area The method as described in any one of Claims 1-7 which allocates a radio | wireless resource to the said installation position of a roadside communication apparatus. A radio resource allocation method for allocating a plurality of different radio resources that do not overlap each other to each of a plurality of road communication devices installed in a predetermined area,
Based on the positional relationship of the plurality of road communication devices on the road and the interference relationship of the plurality of road communication devices, the installation positions of the plurality of road communication devices are applied to a lattice model to install the plurality of road communication devices. Setting the position to each intersection of the grids in the grid model;
Interference area specifying step of specifying an interference area in which at least some of the road communication devices among the road communication devices interfere with other road communication devices in the predetermined area in units of a plurality of different directions. When,
Based on the previous SL different in size for each direction is given the interference area each size, and the unit area setting step of setting the unit area including the installation position of a predetermined number,
An allocation step of allocating radio resources to the installation positions where the road communication devices are installed so that the road communication devices included in the unit area do not interfere with each other. A radio resource allocation method as a feature.   A computer program for causing a computer to execute a process for estimating the required number of radio resources when assigning a plurality of different radio resources that do not overlap each other to a plurality of road communication devices installed in a predetermined area. And
  Based on the positional relationship of the plurality of road communication devices on the road and the interference relationship of the plurality of road communication devices, the installation positions of the plurality of road communication devices are applied to a lattice model to install the plurality of road communication devices. Setting the position to each intersection of the grids in the grid model;
  An interference area specifying step of specifying an interference area in which the road communication device interferes with other road communication devices in the predetermined area in units of a plurality of different directions;
  A unit area setting step for setting a unit area including a predetermined number of the installation positions based on the size of each of the interference areas whose sizes are specified for the plurality of different directions;
  Allocating radio resources to the installation positions where the road communication devices are installed so that the road communication devices included in the unit area do not interfere with each other;
  Obtaining the number of radio resources required for allocation in the allocation step as an estimate of the required number of radio resources allocated to the installation positions of the plurality of road communication devices installed in the predetermined area; A computer program to be executed.   A computer program for causing a computer to execute radio resource allocation processing for allocating a plurality of different radio resources that do not overlap each other to a plurality of road communication devices installed in a predetermined area,
  Based on the positional relationship of the plurality of road communication devices on the road and the interference relationship of the plurality of road communication devices, the installation positions of the plurality of road communication devices are applied to a lattice model to install the plurality of road communication devices. Setting the position to each intersection of the grids in the grid model;
  Interference area specifying step of specifying an interference area in which at least some of the road communication devices among the road communication devices interfere with other road communication devices in the predetermined area in units of a plurality of different directions. When,
  A unit area setting step for setting a unit area including a predetermined number of the installation positions based on the size of each of the interference areas whose sizes are specified for the plurality of different directions;
  A computer program for executing an assignment step of allocating radio resources to the installation positions where the road communication devices are installed so that the road communication devices included in the unit area do not interfere with each other. .

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