WO2013069688A1 - 周波数選択方法およびコグニティブ無線システム - Google Patents
周波数選択方法およびコグニティブ無線システム Download PDFInfo
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- WO2013069688A1 WO2013069688A1 PCT/JP2012/078852 JP2012078852W WO2013069688A1 WO 2013069688 A1 WO2013069688 A1 WO 2013069688A1 JP 2012078852 W JP2012078852 W JP 2012078852W WO 2013069688 A1 WO2013069688 A1 WO 2013069688A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/20—Control channels or signalling for resource management
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- G—PHYSICS
- G08—SIGNALLING
- G08G—TRAFFIC CONTROL SYSTEMS
- G08G1/00—Traffic control systems for road vehicles
- G08G1/01—Detecting movement of traffic to be counted or controlled
- G08G1/056—Detecting movement of traffic to be counted or controlled with provision for distinguishing direction of travel
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- G—PHYSICS
- G08—SIGNALLING
- G08G—TRAFFIC CONTROL SYSTEMS
- G08G1/00—Traffic control systems for road vehicles
- G08G1/09—Arrangements for giving variable traffic instructions
- G08G1/091—Traffic information broadcasting
- G08G1/094—Hardware aspects; Signal processing or signal properties, e.g. frequency bands
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/003—Arrangements for allocating sub-channels of the transmission path
- H04L5/0058—Allocation criteria
- H04L5/0066—Requirements on out-of-channel emissions
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/14—Spectrum sharing arrangements between different networks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/56—Allocation or scheduling criteria for wireless resources based on priority criteria
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/02—Services making use of location information
- H04W4/029—Location-based management or tracking services
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
- H04W64/006—Locating users or terminals or network equipment for network management purposes, e.g. mobility management with additional information processing, e.g. for direction or speed determination
Definitions
- the present invention relates to a frequency selection technique in a cognitive radio system.
- an unlicensed person may use a frequency that is assigned to the licensee (primary user) but is not actually used.
- a frequency is referred to as a secondary usable frequency or white space.
- white space When a secondary user uses such a white space, it is necessary to detect available frequencies and to determine which frequency is preferably used.
- Non-Patent Document 1 the use of a spectrum (white space) database has been studied in order to support the rapid determination of usable frequencies.
- the secondary user is expected to quickly determine the frequencies used for communication.
- cognitive radio using white space to communications for vehicles (moving bodies) is also being studied.
- a characteristic feature of cognitive radio for vehicles is that the position of the vehicle changes frequently, and the usable frequency changes accordingly.
- Google Inc. "Proposal by Google Inc. to Provide a TV Band Device Database Management Solution", [online], [October 17, 2011 search], ⁇ URL: http://www.scribd.com/doc/ 24784912 / 01-04-10-Google-White-Spaces-Database-Proposal>
- Non-Patent Document 1 assumes a fixed terminal as an information providing destination, and has not studied a method for providing information to a high-speed mobile terminal such as a vehicle. Due to the movement of the vehicle, the secondarily available frequency changes drastically both temporally and spatially. In order to transmit such a change from the database to the vehicle, the amount of information becomes enormous, so it is necessary to transmit it efficiently.
- An object of the present invention is to efficiently provide white space information from a database device having white space information to a mobile terminal and to appropriately determine a frequency used for communication in the mobile terminal.
- a frequency determination method includes a database device that stores, for each frequency, a prohibited region, which is a region where a licensee uses radio waves, and a wireless communication device that is configured to wirelessly communicate with the database device.
- the frequency determination method includes a step in which a mobile communication device acquires position information of its own device, a step in which the mobile communication device notifies position information to a database device, and a database device that provides distance information for each frequency.
- the distance information includes a first distance that is a distance in a first direction from the position indicated by the notified position information to the prohibited area, and a second distance from the position indicated by the notified position information to the prohibited area. Information including a second distance that is a distance in the direction.
- the amount of data transmitted from the database device to the mobile communication device can be reduced.
- the distance to the prohibited area related to the moving direction of the mobile communication device is obtained by interpolation processing, it is possible to suppress the influence of the data amount reduction and calculate the usable distance with high accuracy.
- the step of determining a frequency to be used for communication is based on the first distance and the second distance included in the distance information, for each frequency, the distance to the prohibited area in the moving direction of the mobile communication device. It is preferable to include an available distance calculating step obtained by interpolation and a frequency selecting step for determining a frequency giving the longest distance among the distances obtained by the available distance calculating step as a frequency used for communication.
- the frequency selection criterion need not be limited to the usable distance. It is also preferable to determine the frequency to be used in consideration of the available distance and other factors. For example, it is also preferable to determine a frequency to be used on the basis of the amount of data that can be communicated before it becomes unavailable. In this case, the frequency to be used is determined in consideration of the available distance and the communication speed.
- the first interpolation processing method is a method called triangular interpolation in this specification.
- the boundary of the prohibited area is separated from the current position of the mobile communication device by a first distance in the first direction and from the current position of the mobile communication device by a second distance in the second direction.
- the distance to the prohibited area in the moving direction of the mobile communication device is obtained on the assumption that the line is a straight line connecting the points.
- the second interpolation processing method is a method called elliptic interpolation in this specification.
- elliptical interpolation the boundary of the forbidden area is separated from the current position of the mobile communication device by a first distance in the first direction and from the current position of the mobile communication device by a second distance in the second direction.
- the distance to the prohibited area in the moving direction of the mobile communication device is obtained on the assumption that the ellipse passes through the point.
- the third interpolation processing method is a method called rectangular interpolation in this specification.
- rectangular interpolation the boundary of the forbidden area is separated from the current position of the mobile communication device by a first distance in the first direction and from the current position of the mobile communication device by a second distance in the second direction.
- the distance to the prohibited area in the direction of movement of the mobile communication device is determined on the assumption that the rectangle passes through the point.
- the distance information generated by the database device includes information indicating whether the prohibited area in the first direction and the prohibited area in the second direction are the same area or different areas.
- the mobile communication device it is preferable to employ elliptical interpolation if the prohibited areas in the first direction and the second direction are the same area, and adopt rectangular interpolation if the areas are different.
- the appropriate interpolation method also changes. In this way, by properly using the elliptical interpolation and the rectangular interpolation according to the situation, the distance to the prohibited area in the moving direction can be calculated more appropriately.
- the mobile communication device further includes a step of notifying the database device of the movement direction of the own device, wherein the database device is closest to the movement direction of the mobile communication device from among the predetermined directions. It is also preferred that one direction is selected as the first direction and the second direction.
- the information required by the mobile communication device in the process of determining the frequency to be used is the distance to the prohibited area in the two directions closest to the moving direction. Therefore, the mobile communication device notifies the database device of the movement direction, and the database device notifies the mobile communication device only of distance information in two directions close to the movement direction. By doing so, the amount of data communication between the database device and the mobile communication device can be reduced.
- the first direction and the second direction can be orthogonal to each other.
- the first direction and the second direction may be selected from four directions shifted by 90 degrees in advance. These four directions can be the east, west, south, and north directions.
- the first direction and the second direction are not necessarily orthogonal to each other.
- the direction may be selected from eight directions shifted by 45 degrees in advance.
- the direction can be selected from N directions of a predetermined 360 / N degrees (N is an integer). Further, these N directions are not necessarily divided into 360 degrees.
- the mobile communication device determines a frequency to be used for communication in consideration of the planned movement path of the device itself.
- the distance to the prohibited area in the direction of movement of the current position is calculated based on the distance information at the current position, and if the distance exceeds the distance to the next intermediate point on the planned movement path, the distance at the next intermediate point
- the distance from the current position of the mobile communication device to the next intermediate point is obtained based on the information and the movement direction at the next intermediate point to determine the distance to the prohibited area for the next intermediate point movement direction,
- the usable distance at the next intermediate point exceeds the distance to the next intermediate point
- the usable distance is calculated based on the next intermediate point as necessary.
- This repetition can be performed as many times as necessary.
- the usable distance of each frequency can be calculated in consideration of the planned movement path of the mobile communication device, so that a more appropriate frequency can be selected.
- the present invention can be understood as a frequency determination method including at least a part of the above processing.
- the present invention can also be understood as a computer program that executes this method.
- the present invention can also be understood as a wireless communication system, mobile communication device, or database device having means for executing at least a part of the above processing.
- Each of the above means and processes can be combined with each other as much as possible to constitute the present invention.
- a wireless communication system as one embodiment of the present invention is as follows.
- a wireless communication system that includes a database device and a mobile communication device and performs communication by selecting a frequency from frequencies that can be used by the mobile communication device,
- the database device includes: A prohibited area storage means for storing a prohibited area, which is an area where the licensee uses radio waves, for each frequency; Based on the position information notified from the mobile communication device, for each frequency, the first distance that is the distance in the first direction from the position indicated by the notified position information to the prohibited area, and the notified position information A distance information generating means for determining a second distance that is a distance in a second direction from the position indicated by the forbidden area and generating distance information including the first distance and the second distance; Have The mobile communication device Position information acquisition means for acquiring position information; Distance information requesting means for notifying the database device of position information and obtaining the distance information; Use frequency determining means for determining a frequency to be used for communication based on the notified distance information and the moving direction of the own device;
- a mobile communication device that determines and communicates a frequency to be used based on distance information notified from a database device that stores, for each frequency, a prohibited region that is a region where a licensee uses radio waves, Position information acquisition means for acquiring position information; The position information is notified to the database device, the first distance that is the distance in the first direction from the position indicated by the position information to the prohibited area, and the second distance from the position indicated by the position information to the prohibited area.
- Use frequency determining means for determining a frequency to be used for communication based on the notified distance information and the moving direction of the own device; Have
- the database device as one aspect of the present invention is: A prohibited area storage means for storing a prohibited area, which is an area where the licensee uses radio waves, for each frequency; Based on the position information notified from the mobile communication device, for each frequency, the first distance that is the distance in the first direction from the position indicated by the notified position information to the prohibited area, and the notified position information are Distance information generating means for determining a second distance that is a distance in a second direction from the position to be shown to the prohibited area, and generating distance information including the first distance and the second distance;
- FIG. 1 is a diagram showing a system overview of a wireless communication system according to an embodiment.
- FIG. 5 is a diagram showing a data structure of white space information in the first embodiment.
- (A) shows a triangular interpolation method
- FIG. 6 is a flowchart showing an overall flow of wireless communication processing performed by an in-vehicle terminal in the first to fourth embodiments.
- the flowchart which shows the detail of the frequency selection process in a vehicle-mounted terminal in 1st Embodiment.
- the flowchart which shows the white space information generation process in the database apparatus in 2nd Embodiment.
- FIG. 1 shows a schematic diagram of a wireless communication system according to the present embodiment.
- the radio communication system is generally composed of a database device 10 and a vehicle 20 including an in-vehicle terminal 21.
- the in-vehicle terminal 21 communicates with other in-vehicle terminals using a white space.
- the white space is a frequency that is not used by the primary user (license) and is a frequency that can be used by the secondary user.
- the in-vehicle terminal 21 uses the white space as a secondary user as long as it does not interfere with the primary user.
- the in-vehicle terminal 21 uses the white space information obtained from the database device 10 to determine a frequency that can be used at the current position.
- the database device 10 has information (white space information) that can identify areas where the frequencies are currently available and areas where the frequencies cannot be used for various frequencies.
- the database device 10 has white space information regardless of how the database device 10 creates white space information.
- white space information for example, if the primary user is a broadcaster having a fixed radio tower, the location of the radio tower, the strength of transmission power (radio wave reach), and the broadcast time are collected. It is conceivable to create based on such information. In addition, it is conceivable to generate white space information by collecting the frequency usage status at each position in real time and collecting it in the database device 10 or performing statistical processing on the collected information.
- the distance that the vehicle 20 can use this frequency can be calculated in consideration of the current position and the moving direction of the vehicle 20 as shown in FIG. Although the definition of a preferable frequency for the vehicle 20 varies depending on application requirements, the frequency that can be used for the longest distance (or time) is considered preferable here.
- the frequency selection process is performed by the vehicle 20 in order to avoid the concentration of the processing load on the database device 10. Therefore, the database device 10 basically performs only the process of notifying the vehicle 20 of information regarding the white space.
- the problem here is how to transmit information about the white space from the database device 10 to the vehicle 20. As shown in FIG. 3, it is understood that the availability of the frequency can be accurately calculated by notifying the vehicle 20 of the distance from the current position of the vehicle 20 to the interference area in each direction. However, it is practically impossible to send information in all directions from the viewpoint of the communication data amount, and it is necessary to reduce the data amount.
- the database apparatus 10 notifies the vehicle 20 of the distance to the interference region in a predetermined direction centered on the current position of the vehicle 20, as shown in FIG. 4A or 4B. .
- the distance to the interference region in four directions 401 to 404 that are shifted by 90 degrees from each other (for example, direction 401 is east, direction 402 is north, direction 403 is west, and direction 404 is south). Is notified to the vehicle 20.
- the distances to the interference areas in each direction 401 to 404 are 100 m, 350 m, 250 m, and ⁇ ⁇ ⁇ ⁇ 150 m, respectively, data (100, 350, 250, 150) is notified from the database device 10 to the vehicle 20. Is done.
- a white space vector or abbreviated as WSV. This white space vector corresponds to the distance information in the present invention.
- the distance to the interference area is notified to the vehicle 20 in the directions 411 to 418 in eight directions that are shifted by 45 degrees from each other.
- the WSV of (100, 370, 350, 410, 250, 220, 150, 180) is notified to the vehicle 20.
- the resolution in the direction the more detailed the white space shape can be notified to the vehicle 20, the communication data amount increases correspondingly, and there is a problem that the calculation amount in the database device 10 increases.
- there is no upper limit to the direction resolution there is no upper limit to the direction resolution.
- a sufficient effect can be obtained with about 8 (45 degree units).
- FIG. 5 shows a data structure of white space information transmitted from the database device 10 to the vehicle 20.
- FIG. 5 shows an example in which a WSV composed of four components is employed as shown in FIG. 4A.
- the white space information is composed of numerical values up to the interference area in each of the four directions for each of the frequencies f1 to fn. This numerical value is quantized and expressed in units of an appropriate distance (for example, 10 meters), so that the data amount of white space information can be reduced.
- ⁇ Frequency determination method The vehicle 20 that has acquired the white space information from the database device 10 determines an optimum frequency for communication based on this information.
- This frequency determination process includes the following two steps. 1. 1. Calculate available distance for each frequency. Select the frequency that gives the maximum available distance
- step 1 described above that is, the process of calculating the usable distance of a frequency from the white space vector (WSV) for the frequency will be described.
- the calculation is performed on the assumption that the moving direction of the vehicle is constant and does not change in the middle.
- a method for calculating in consideration of the moving route of the vehicle will be described in another embodiment.
- the first method is a method of obtaining the usable distance on the assumption that the boundary of the interference region is a straight line.
- this first method is referred to as “triangular interpolation”.
- FIG. 6A is a diagram for explaining triangular interpolation.
- the point 601 indicates the position of the vehicle
- the angle ⁇ indicates the moving direction of the vehicle.
- ⁇ i and ⁇ i + 1 are the two directions closest to the moving direction of the vehicle among the WSV components
- d ⁇ i and d ⁇ i + 1 are the distances to the interference region in the ⁇ i direction and the ⁇ i + 1 direction. It is.
- the d .theta.i apart points 602 from the current position 601 in the theta i direction of the vehicle, d .theta.i + 1 apart points 603 to theta i + 1 directions from the current position 601 of the vehicle, the interference region and a non-interference area It turns out that it is a boundary. However, except for the points 602 and 603, the boundary between the interference region and the non-interference region is unknown. Therefore, in the method shown in FIG. 6A, assuming that the boundary of the interference area is a straight line connecting point 602 and point 603, the distance to the interference area in the vehicle movement direction is obtained.
- the distance d est to the interference region in the moving direction ⁇ of the vehicle is expressed by the following equation.
- the second method is a method of obtaining the usable distance on the assumption that the boundary of the interference area is an elliptic curve.
- this second method is referred to as “elliptical interpolation”.
- FIG. 6B is a diagram for explaining elliptic interpolation. Among the elements in FIG. 6B, the same elements as those in FIG. 6A are denoted by the same reference numerals, and the description thereof is omitted.
- Point 604 in FIG. 6B is a point that forms a rectangle together with points 601, 602, and 603. In the method shown in FIG. 6B, it is assumed that the boundary between the interference region and the non-interference region is an ellipse centered at the point 604 and having radii of the line segments 602-604 and 603-604, respectively.
- the distance d est to the interference region in the moving direction ⁇ of the vehicle is expressed by the following equation.
- the third method is a method for obtaining the usable distance on the assumption that the boundary of the interference area is rectangular.
- this third method is referred to as “rectangular interpolation”.
- FIG. 6C is a diagram illustrating rectangular interpolation. Among the elements in FIG. 6C, the same elements as those in FIGS. 6A and 6B are denoted by the same reference numerals, and the description thereof is omitted.
- the boundary between the interference region and the non-interference region is a line segment having both ends of point 602 and point 604 and a line segment having both ends of point 603 and point 604.
- the distance d est to the interference region in the moving direction ⁇ of the vehicle is expressed by the following equation.
- the usable distance in the moving direction of the vehicle is obtained by the above estimation.
- the calculation of the usable distance is performed for all frequencies. Then, of the available distances obtained for each frequency, the frequency that gives the longest available distance is regarded as the most preferable frequency, and this frequency is determined as the used frequency (process 2).
- FIG. 7 shows a functional block diagram of the database device 10 and the vehicle 20 constituting the wireless communication system according to the present embodiment.
- the database device 10 is a computer (electronic computer) having an auxiliary storage device such as a CPU, RAM, HDD, etc., and the CPU reads and executes a computer program such as an operating system or an application program as the following functional units. Operate. That is, the database device 10 functions as the wireless communication unit 11, the white space information creation unit 12, and the interference area information storage unit 13.
- the wireless communication unit 11 is an interface for communicating with the in-vehicle terminal 21 of the vehicle 20. Any communication method can be adopted as long as it can communicate with the in-vehicle terminal 21. For example, LTE (Long Term Evolution), Mobile WiMax (IEEE 802.16e), WAVE (IEEE 802.16p), iBurst (IEEE 802.120), etc. Can be adopted.
- LTE Long Term Evolution
- Mobile WiMax IEEE 802.16e
- WAVE IEEE 802.16p
- iBurst IEEE 802.120
- the white space information creation unit 12 acquires vehicle position information and refers to the interference region information storage unit 13 to create information indicating the distance to the surrounding interference region at the vehicle position. This distance is calculated only for a predetermined number of directions (eg 4). The combination of these distance values is the white space vector described above.
- the interference area information storage unit 13 stores the frequency use area of the primary user at each point in time for a plurality of frequencies. In other words, the interference area information storage unit 13 stores, for a plurality of frequencies, an area in which a secondary user cannot use (uses interference to the primary user when used) at an arbitrary point in time.
- the method for creating the interference area information storage unit 13 is not limited.
- the interference area may be acquired from information such as the position of the radio tower, transmission output, and broadcast time, or the interference area may be acquired by measuring in real time, or statistical processing is performed for measurement over a certain period. An interference area may be acquired.
- a specific data holding method for interference area information in the database apparatus 10 may be used. Any existing method such as a distributed relational database can be used as the data holding method.
- the database apparatus 10 does not have to be configured by only one computer, but may be configured as a distributed system including a plurality of computers connected to each other via a network.
- the vehicle 20 includes an in-vehicle terminal 21, an inter-vehicle communication device 25, and a GPS device 26.
- the in-vehicle terminal is a computer including a CPU, RAM, ROM, and the like, and operates as the following functions when the CPU reads and executes a computer program such as an operating system or an application program. That is, the radio communication unit 22, the white space information request unit 23, and the use frequency band determination unit 24 operate.
- the wireless communication unit 22 is an interface for communicating with the database device 10. Any wireless communication method can be adopted as long as it can communicate with the database device 10, such as LTE (Long Term Evolution), Mobile WiMax (IEEE 802.16e), WAVE (IEEE 802.16p), iBurst (IEEE 802.120), etc. Can be adopted.
- LTE Long Term Evolution
- Mobile WiMax IEEE 802.16e
- WAVE IEEE 802.16p
- iBurst IEEE 802.120
- the white space information request unit 23 acquires the position information obtained from the GPS device 26, and creates a white space information request including the position information.
- the created white space information request is sent to the database device 10 via the wireless communication unit 22.
- the transmission timing of the white space information request is a timing when it is necessary to determine a frequency to be used for communication such as when communication is started or when a frequency that has been used until then becomes unavailable.
- the use frequency band determination unit 24 determines the frequency to be used based on the white space information obtained from the database device 10 as a result of the white space information request and the current position obtained from the GPS device 26. Since the method of determining the use frequency has been described above, it will not be repeated here.
- the inter-vehicle communication device 25 is a device that performs wireless communication with other vehicles.
- the wireless communication method may be arbitrary, but it is preferable to support a wide frequency band so that more white space can be used.
- the inter-vehicle communication device 25 has a function of performing spectrum sensing for detecting a frequency that can be used at the present time. It is preferable that spectrum sensing can be performed in as wide a frequency band as possible. Any existing method can be adopted as the spectrum sensing method. For example, depending on the wireless communication method to be detected, the frequency is in use by energy detection, wavelet decomposition technique, pilot-based spectrum sensing, spectrum sensing based on eigenvalue, feature detection, matched filter method, etc. Or whether it is unused.
- FIG. 8 is a flowchart showing processing of the inter-vehicle communication method by the vehicle 20 in the present embodiment.
- the inter-vehicle communication device 25 detects a frequency that can be used at the current position (S801).
- S802-NO and S803-YES the available frequency is detected again after a time.
- S805 only one usable frequency is detected.
- step S804 the in-vehicle terminal 21 requests white space information from the database device 10, and determines a frequency to be used based on the obtained white space information. Then, the vehicle-to-vehicle communication device 25 performs data communication using the determined frequency (S805). Details of the frequency selection processing in step S804 will be described later in detail with reference to FIGS. 9A and 9B.
- the inter-vehicle communication device 25 continues the surrounding spectrum sensing (S806). If the currently used frequency is available (S807-YES), data communication is continued as it is (S811). On the other hand, when the currently used frequency is not available or expected to be unavailable (S807-NO), the frequency changing process is performed. When a plurality of usable frequencies are detected (S808-YES), the in-vehicle terminal 21 executes frequency selection processing based on white space information (S809), and performs frequency switching handover (vertical handover). Implement (S810). Note that the process of step S809 is the same as the process of step S804.
- FIG. 9A is a flowchart of processing performed in the in-vehicle terminal 21, and FIG. 9B is a flowchart of processing performed in the database device 10.
- FIG. 9A When the frequency selection process is started, the in-vehicle terminal 21 acquires the current position from the GPS device 26 (S901).
- the white space information request unit 23 generates a white space information request including the current position, and transmits this request to the database device 10 via the wireless communication unit 22 (S902).
- the white space information creation unit 12 extracts the current position of the vehicle included in the white space information request (S910). Then, from the current position of the vehicle extracted from the white space information request, the frequency can be used for each predetermined direction (for example, four directions as shown in FIG. 4A or eight directions as shown in FIG. 4B). The distance (distance to the interference area) is calculated (S912). A white space vector for one frequency is generated from the combination of these distances (S913).
- the white space information creation unit 12 repeatedly executes the processing from step S912 to step S913 for all frequencies stored in the interference region information storage unit 13 to obtain a white space vector for each frequency.
- the white space information creation unit 12 creates white space information as shown in FIG. 5 from the white space vector for each frequency, and sends it back to the in-vehicle terminal 21 via the wireless communication unit 11 (S915).
- the use frequency band determination unit 24 When the in-vehicle terminal 21 receives the white space information from the database device 10 (S903), the use frequency band determination unit 24 repeatedly executes steps S905 and S906 for each frequency to calculate a usable distance. Specifically, the use frequency band determination unit 24 selects components in two directions closest to the moving direction of the vehicle from the white space vector of the target frequency (S905). Then, using any of the interpolation methods shown in FIGS. 6A to 6C, the distance from the current position to the interference area in the moving direction is calculated (S906). Here, the distance is calculated using the interpolation method (triangular interpolation) shown in FIG.
- the utilization frequency band determining unit 24 determines the frequency that gives the longest usable distance as the frequency used for inter-vehicle communication (S908).
- the use frequency band determination unit 24 transmits this frequency to the vehicle-to-vehicle communication device 25, and the vehicle-to-vehicle communication device 25 executes vehicle-to-vehicle communication using this frequency.
- the communication amount between the database device 10 and the vehicle 20 is reduced. Can be reduced. Although the amount of communication is reduced, interpolation processing is performed in the vehicle 20 to calculate the distance that each frequency can be used. Therefore, it is possible to suppress deterioration in accuracy due to reduction in the amount of information. Therefore, it is possible for the vehicle 20 to select an appropriate frequency in consideration of the radio wave usage status of the primary user while suppressing the amount of communication between the database device 10 and the vehicle 20.
- the database apparatus performs only minimal processing. This can be said to be an efficient method in terms of system operation, considering that the database device has to process many white space information requests from a plurality of vehicles.
- the contents of data exchanged between the database device 10 and the vehicle 20 are different from those in the first embodiment.
- the white space vector has a large number of components such as four or eight.
- FIGS. 6A to 6C when calculating the frequency usable distance, only two components closest to the moving direction of the vehicle are used. Therefore, in the present embodiment, as shown in FIGS. 10A and 10B, the database device 10 notifies the vehicle 20 of only two components closest to the moving direction of the vehicle.
- ⁇ 0 is the east direction (0 degree)
- ⁇ 1 is the north direction (90 degrees)
- ⁇ 2 is the west direction (180 degrees)
- ⁇ 3 is the south direction (270 degrees).
- the moving direction of the vehicle is a 60 degree direction
- the two directions closest to the moving direction of the vehicle are ⁇ 0 (0 degree) and ⁇ 1 (90 degrees). Therefore, only the distance in the ⁇ 0 direction and the ⁇ 1 direction is notified to the vehicle 20, and the distance in the other directions is not notified to the vehicle 20.
- FIG. 11 shows the data structure of the white space information in the present embodiment.
- the white space information is the same as in the first embodiment in that the white space information is composed of white space vectors for each frequency, but in this embodiment, the white space vector includes only two components (d 1 and d 2 ). It is different. Furthermore, data ( ⁇ i and ⁇ i + 1 ) for specifying the directions of these two components (d 1 and d 2 ) are included. In addition, if the two directions included in the white space vector are mutually recognizable between the database device 10 and the vehicle 20, the data regarding the direction is not necessary.
- FIGS. 9A and 9B are flowcharts showing the flow of frequency selection processing in the in-vehicle terminal 21 and the database device 10, respectively. Since it is basically the same as the processing of the first embodiment (FIGS. 9A and 9B), the same reference numerals are assigned to the portions that perform the same processing, and description thereof is omitted. In the following description, differences from the first embodiment will be mainly described.
- the in-vehicle terminal 21 needs to notify the database device 10 not only of the current position but also the moving direction of the vehicle when requesting white space information. Therefore, the white space information request unit 23 acquires the moving direction of the vehicle 20 (S1201), creates a white space information request including the current position and the moving direction, and transmits the white space information request to the database device 10 (S1202). *
- the white space information creation unit 12 of the database device 10 that has received the white space information request from the in-vehicle terminal 21 extracts the position information and the moving direction of the vehicle from the white space information request (S1204). Then, the white space information creation unit 12 selects two directions closest to the moving direction of the vehicle from a plurality of predetermined directions (S1205). In creating the white space vector, the distance from the vehicle position to the interference region is calculated only in the two directions selected here (S1206), and the white space vector is created (S1207). White space information is created from the white space vector for each frequency obtained in this way, and is returned to the in-vehicle terminal 21.
- the in-vehicle terminal 21 selects the component close to the moving direction of the vehicle. There is no need to perform the process (step S905 in FIG. 9A).
- the use frequency band determination unit 24 calculates the usable distance in the movement direction from the two components included in the white space information by a technique such as triangular interpolation (S1203). Subsequent processing is the same as in the first embodiment.
- the communication amount increases in that it is necessary to transmit the traveling direction information, but the communication amount can be reduced in that only two components of the white space vector are transmitted.
- the direction of the target for calculating the distance from the vehicle position to the interference area is limited to only two, the amount of calculation in the database device 10 can be reduced.
- the effect according to the first embodiment can be realized while realizing such a further effect.
- FIG. 6A triangular interpolation
- FIG. 6B elliptical interpolation
- Figure 6C Either interpolation method was used.
- An object of the present embodiment is to further improve the calculation accuracy of the usable distance by adopting an appropriate interpolation method according to the situation.
- Each component in the white space vector indicates the distance from the current position of the vehicle to the interference area in the predetermined direction.
- each represents a distance to the same interference region as shown in FIG. 13A, and up to a different interference region as shown in FIG. 13B. There are two cases of representing the distance.
- the boundary between the interference region and the non-interference region at an angle between them is preferably regarded as an ellipse. It turns out that it is. Therefore, in such a case, it is preferable to use elliptical interpolation (FIG. 6B) to calculate the usable distance.
- FIG. 13B when the components in two adjacent directions represent distances to different interference areas, the boundary between the interference area and the non-interference area at an angle between them can be regarded as a rectangle. . Therefore, in such a case, rectangular interpolation (FIG. 6C) is used to calculate the usable distance.
- the available distance varies depending on the position and size of the interference region 1302 or the moving direction of the vehicle. For example, if the size of the interference area 1302 is smaller than that shown in FIG. 13B, the position is shifted to the left, or the moving direction of the vehicle is more to the right (d ⁇ i direction), use The possible distance is longer.
- the shape of the boundary changes depending on the positional relationship and the like.
- the shape of the boundary is a rectangle, it is possible to avoid an overly optimistic or pessimistic guess and to calculate an appropriate usable distance on average.
- the white space information (white space vector). Since this information only represents whether the interference area in the adjacent direction is the same interference area or a different interference area, 1-bit information is sufficient.
- this information is referred to as an adjacent determination bit. For example, if the adjacency determination bit is “0”, it indicates that the interference area is the same, and if it is “1”, it indicates that the interference area is different.
- FIG. 14A and 14B are diagrams showing the data structure of white space information in the present embodiment.
- FIG. 14A shows an example in which an adjacency determination bit is added to the white space information of the second embodiment.
- One adjacent determination bit is added to the end of the white space vector of each frequency.
- the white space information stores the components of only the two directions closest to the moving direction of the vehicle in the white space vector. Therefore, the adjacency determination bit only needs to indicate whether the interference regions in the two directions are the same or different, and only one adjacency determination bit is required.
- FIG. 14B shows an example in which an adjacency determination bit is added to the white space information of the first embodiment.
- a plurality of adjacency determination bits are added to the end of the white space vector of each frequency.
- all the components of the white space vector are stored in the white space vector. Therefore, there are as many combinations of adjacent directions as the number of components of the white space vector. Therefore, in this example, the same number of adjacent determination bits as the number of components of the white space vector are added.
- FIG. 15A and FIG. 15B are flowcharts showing the flow of frequency selection processing in the in-vehicle terminal 21 and the database device 10, respectively.
- the process shown in the figure is based on the second embodiment, and is basically the same as the process of the second embodiment (FIGS. 9A and 9B).
- FIGS. 9A and 9B are denoted by the same reference numerals and description thereof is omitted. In the following description, differences from the second embodiment will be mainly described.
- step S901, S1201, and S1202 processing for requesting white space information from the in-vehicle terminal 21 to the database device 10 (steps S901, S1201, and S1202) is the same as in the second embodiment.
- step S1505 the process of creating the white space information in the database device 10 is almost the same as in the second embodiment, except that step S1505 is present after step S1207.
- step S1505 the white space information creation unit 12 determines whether the interference regions existing in the two directions selected in step S1205 are the same interference region or different interference regions, and sets the adjacent determination bit according to the determination result to white. Append to space vector. For example, if the interference areas in the two directions are the same interference area, “0” is added as an adjacent determination bit, and “1” is added if the interference areas are different.
- the white space information in which the adjacent determination bit is added to each white space vector is generated and transmitted from the database device 10 to the in-vehicle terminal 21.
- an adjacency determination bit is added for each combination of two adjacent directions.
- the in-vehicle terminal 21 that has received the white space information from the database device 10 calculates the usable distance for each frequency as follows. First, with reference to an adjacent determination bit added to a white space vector of a certain frequency, it is determined whether interference areas in two directions included in the white space vector are the same area or different areas ( S1501).
- the usable distance for all frequencies is calculated using different interpolation methods depending on whether the interference areas in the two directions are the same or different. Then, a frequency that gives a longer distance among the calculated available distances is selected as a frequency to be used (S908).
- the present embodiment by adopting an appropriate interpolation method according to the relationship of the interference area, it is possible to improve the calculation accuracy of the usable distance compared to the case where the same interpolation method is always adopted, and therefore frequency selection. Processing can be made more accurate.
- the communication amount between the database device 10 and the in-vehicle terminal 21 increases by adding the adjacency determination bit, but the increase amount is only 1 bit, which is not a problem. Rather, since the accuracy of frequency selection can be remarkably improved by this slight increase in communication volume, it can be said that the improvement effect per communication volume is very large.
- the usable frequency distance is calculated on the assumption that the vehicle always travels in a certain direction. However, in reality, the vehicle does not always go straight, but changes direction. Therefore, in the present embodiment, the usable distance of the frequency is calculated with higher accuracy by considering the planned travel route of the vehicle.
- FIG. 16A and FIG. 16B are diagrams showing examples of situations that cause problems when it is assumed that the traveling direction of the vehicle is always constant.
- a point 1601 is the current position of the vehicle 20
- a line 1602 is a planned travel route acquired from a car navigation device or the like.
- the vehicle 20 can actually use this frequency for a relatively long time. However, assuming that the vehicle goes straight as in the first to third embodiments, the vehicle 20 enters the interference region 1603. When entering, it is erroneously determined that the frequency becomes unusable.
- the vehicle 20 enters the interference area 1605 by changing the direction, but assuming that the vehicle goes straight, it does not enter the interference area, so the frequency can be used for a longer time than the actual one. Is erroneously determined.
- the above-described erroneous determination problem is solved by calculating the usable distance of each frequency in consideration of the travel route of the vehicle as follows.
- FIG. 17 a calculation method of the usable distance of each frequency in the present embodiment will be described.
- the functional configurations of the database device 10 and the vehicle 20 in the present embodiment are the same as those in the first to third embodiments (FIG. 7), and a description thereof will be omitted.
- the overall flow of communication processing in this embodiment is the same as that in the first to third embodiments (FIG. 8), and the white space information creation processing in the database device 10 is also in the first to third embodiments (FIG. 9B).
- FIG. 17 is a flowchart showing details of frequency selection processing (steps S804 and S809 in FIG. 8) in the in-vehicle terminal 21.
- the flowchart in FIG. 17 is basically the same as the process in the first embodiment (FIG. 9A), and therefore, the same reference numerals are given to the parts that perform the same process, and the description thereof is omitted. In the following description, differences from the first embodiment will be mainly described.
- the in-vehicle terminal 21 acquires the current position (S901), acquires a planned travel route from a car navigation device or the like, and determines an intermediate point on the travel route (S1701).
- the intermediate point is a position at which the vehicle 20 can be considered to change direction, and is typically a point where the vehicle turns right or left.
- intermediate point candidates are set at predetermined distance intervals on the travel route.
- points N 1 , N 2 , and N 3 are shown as intermediate point candidates.
- the point N 0 is the current position of the vehicle 20.
- the traveling direction ⁇ i of the vehicle between two adjacent points is calculated, and the variation of the traveling direction ⁇ i + 1 ⁇ i is greater than or equal to a predetermined threshold value the become points N i adopts as the midpoint.
- the intermediate point can be determined as described above, the method shown in FIG. 18A cannot cope with a case where the traveling direction is gradually changed. Therefore, it is preferable to determine the midpoint by the method shown in FIG. 18B in addition to the above method. That is, the distance between the initial position N 0 and the candidate point N i and D i, the difference in direction from the traveling direction and the point N 0 at point N 0 to the point N i and [psi i. Then, employing the D i ⁇ sin ⁇ i point is equal to or greater than a predetermined threshold value N i as the midpoint.
- This method can be said to be a method of determining the intermediate point between the point where the route traveled straight toward the traveling direction of the initial position N 0 and the actual traveling position are more than a predetermined threshold.
- White space information request processing is the same as in the first embodiment. Based on the white space information, the calculation method of the usable distance for each frequency (the processing in the loop of steps S904 to S907) is significantly different from that of the first embodiment.
- Steps S1703 to S1707 are a loop for each intermediate point.
- the target intermediate point is N i, and processing is performed focusing on the target intermediate point Ni and the next intermediate point Ni + 1 .
- the target intermediate point is the point N 0 (current position of the vehicle).
- step S906 adopts the moving direction at the point N i.
- it may be employed as these mean if the direction from the moving direction and the point N i at point Ni on the point N i + 1 are different.
- the distance between the point N i and point N i + 1 may be a real distance may be a linear distance, moving a line segment connecting the point N i and point N i + 1 at point N i It may be the distance of the line segment projected in the direction.
- the utilization frequency band determining unit 24 sets the variable Ni to the point Ni and the point Ni. The distance between +1 is added (S1705). Then, the white space information request unit 23 requests the database device 10 for white space information for the next intermediate point Ni + 1 (step S1706). Then, the above process is repeated for the next intermediate point.
- step S906 When the usable distance obtained in step S906 is equal to or smaller than the distance between the point Ni and the point Ni + 1 (S1704-NO), the calculated usable distance is added to the variable D (step S1708). The value of the variable D after the addition is stored as the usable distance at this frequency.
- the usable distance of each frequency is calculated in consideration of the planned travel route of the vehicle, the usable distance can be calculated with higher accuracy. Therefore, it is possible to select a more appropriate frequency.
- the white space information for one intermediate point is acquired from the database device 10, and the white space information for the next intermediate point is acquired according to the calculation result.
- the white space information for a plurality of intermediate points may be acquired from the database device 10 at once.
- white space information for intermediate points within a predetermined distance from the current position may be acquired in a batch, or white space information for a predetermined number of intermediate points from the current position may be acquired in a batch. May be.
- the in-vehicle communication device has been described as performing cognitive radio with another vehicle, but the communication partner is not limited to the vehicle, and any device can be the communication partner.
- the mobile communication device has been described as a communication device mounted on an automobile, the mobile communication device according to the present invention may be a communication device mounted on a train, an airplane, a ship, or the like other than a vehicle. It may be a mobile communication terminal that is carried by a person, or a communication device that is moved by bringing the vehicle into a vehicle or the like and moving the vehicle.
- the frequency that can be used is selected as a frequency that uses a longer frequency, but the frequency selection criterion is not limited to this. In general, it is conceivable to perform frequency selection in consideration of factors other than the usable distance. For example, considering the communication speed for each frequency, the frequency may be selected based on the amount of data that can be communicated while it is available (basically, it can be evaluated as the product of the available distance and the communication speed).
- Database device 11 Wireless communication unit 12 White space information creation unit 13 Interference area information storage unit 20 Vehicle 21 In-vehicle terminal 22 Wireless communication unit 23 White space information request unit 24 Use frequency band determination unit 25 Inter-vehicle communication device 26 GPS device
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Abstract
Description
データベース装置と移動通信装置とから構成され、移動通信装置が使用可能な周波数の中から周波数を選択して通信を行う無線通信システムであって、
前記データベース装置は、
免許者が電波を使用している領域である禁止領域を周波数ごとに記憶する禁止領域記憶手段と、
前記移動通信装置から通知される位置情報に基づいて、周波数ごとに、通知された位置情報が示す位置から禁止領域までの第1の方向の距離である第1の距離と、通知された位置情報が示す位置から禁止領域までの第2の方向の距離である第2の距離とを求め、第1の距離および第2の距離を含む距離情報を生成する距離情報生成手段と、
を有し、
前記移動通信装置は、
位置情報を取得する位置情報取得手段と、
位置情報を前記データベース装置へ通知して、前記距離情報を取得する距離情報要求手段と、
通知された距離情報および自装置の移動方向に基づいて通信に利用する周波数を決定する利用周波数決定手段と、
を有する。
免許者が電波を使用している領域である禁止領域を周波数ごとに記憶するデータベース装置から通知される距離情報に基づいて、使用する周波数を決定して通信する移動通信装置であって、
位置情報を取得する位置情報取得手段と、
位置情報を前記データベース装置へ通知して、当該位置情報が示す位置から禁止領域までの第1の方向の距離である第1の距離と、当該位置情報が示す位置から禁止領域までの第2の方向の距離である第2の距離とを含む距離情報を取得する距離情報要求手段と、
通知された距離情報および自装置の移動方向に基づいて通信に利用する周波数を決定する利用周波数決定手段と、
を有する。
免許者が電波を使用している領域である禁止領域を周波数ごとに記憶する禁止領域記憶手段と、
移動通信装置から通知される位置情報に基づいて、周波数ごとに、通知された位置情報が示す位置から禁止領域までの第1の方向の距離である第1の距離と、通知された位置情報が示す位置から禁止領域までの第2の方向の距離である第2の距離とを求め、第1の距離および第2の距離を含む距離情報を生成する距離情報生成手段と、
を有する。
<システム概要>
本発明の第一の実施形態は、車載通信装置(車載端末)を備えた車両とデータベース装置とから構成される無線通信システムである。図1に、本実施形態にかかる無線通信システムの概要図を示す。無線通信システムは、大略、データベース装置10と、車載端末21を備える車両20とから構成される。
ここで問題となるのは、データベース装置10から車両20に対して、どのようにホワイトスペースに関する情報を伝達するのかという点である。図3に示すように、現在の車両20の位置から各方向について干渉領域までの距離を車両20に通知すれば、周波数の利用可能を正確に算出できることが分かる。しかしながら、全方向についての情報を送ることは通信データ量の観点から現実的に不可能であり、データ量の削減が必要となる。
データベース装置10からホワイトスペース情報を取得した車両20は、この情報に基づいて、通信に最適な周波数を決定する。この周波数決定処理は、以下の2つのステップから構成される。
1.周波数ごとに、利用可能距離を算出する
2.最大の利用可能距離を与える周波数を選択する
[機能構成]
図7に、本実施形態にかかる無線通信システムを構成するデータベース装置10と車両20の機能ブロック図を示す。データベース装置10は、CPU、RAM、HDDなどの補助記憶装置などを有するコンピュータ(電子計算機)であり、オペレーティングシステムやアプリケーションプログラムなどのコンピュータプログラムをCPUが読み込んで実行することで、以下の機能部として動作する。すなわち、データベース装置10は、無線通信部11、ホワイトスペース情報作成部12、干渉領域情報記憶部13として機能する。
図8は、本実施形態における車両20による車車間通信方法の処理を示すフローチャートである。車両20が通信を開始する際には、まず、車車間通信装置25が現在位置で利用可能な周波数の検出を行う(S801)。ここで、利用可能な周波数が検出されない場合(S802-NOかつS803-YES)には、時間をおいて再度利用可能な周波数を検出する。一方、利用可能な周波数が1つのみ検出された場合(S802-NOかつS803-NO)には、その周波数を利用してデータ通信を開始する(S805)。
本実施形態によれば、データベース装置10から車両20へ送信するホワイトスペースに関する情報を、ホワイトスペースベクトルという情報量を落とした形式で通知するため、データベース装置10と車両20との間の通信量を削減できる。通信量を削減しているが、車両20において補間処理を実施して、各周波数が利用可能な距離を算出しているので情報量削減による精度の劣化を抑制することができる。したがって、データベース装置10と車両20との間の通信量を抑制しつつ、車両20がプライマリーユーザの電波利用状況を考慮して、適切な周波数を選択することが可能となる。
本実施形態では、第1の実施形態と比較して、データベース装置10と車両20との間のやりとりするデータの内容を異ならせる。第1の実施形態では、図4Aや図4Bに示すように、ホワイトスペースベクトルは4つあるいは8つなど多数の成分を有している。しかしながら、図6A~図6Cに示すように、周波数の利用可能距離の算出の際には、車両の移動方向に最も近い2つの成分しか使用していない。そこで、本実施形態では、図10Aや図10Bに示すように、データベース装置10は、車両の移動方向に最も近い2つの成分のみを車両20へ通知するようにする。
第1および第2の実施形態では、車両の現在位置から干渉領域までの距離(周波数の利用可能距離)を求める際の補間方法として、三角補間(図6A)、楕円補間(図6B)、矩形補間(図6C)のいずれかの補間方式を採用していた。本実施形態では、状況に応じて適切な補間方式を採用することで、利用可能距離の算出精度をさらに向上させることを目的とする。
上記第1から第3の実施形態では、車両が常に一定方向に走行することを前提として、周波数の利用可能距離を算出している。しかしながら、実際には車両は常に直進するのではなく方向転換を行う。そこで、本実施形態では車両の予定走行経路も考慮することで、より精度良く周波数の利用可能距離を算出する。
上記の第1から第4の実施形態は、適宜組み合わせることが可能である。また、上記の実施形態の説明は、本発明を説明する上での例示に過ぎず、本発明の範囲を上記の実施形態に限定するものではない。当業者であれば、本発明の技術思想にしたがって、上記で開示された実施形態に種々の変形を加えることは容易であろう。
11 無線通信部
12 ホワイトスペース情報作成部
13 干渉領域情報記憶部
20 車両
21 車載端末
22 無線通信部
23 ホワイトスペース情報要求部
24 利用周波数帯決定部
25 車車間通信装置
26 GPS装置
Claims (20)
- 免許者が電波を使用している領域である禁止領域を周波数ごとに記憶するデータベース装置と、前記データベース装置と無線通信可能な移動通信装置とから構成される無線通信システムにおいて前記移動通信装置が通信に利用する周波数を決定する周波数決定方法であって、
前記移動通信装置が、自装置の位置情報を取得するステップと、
前記移動通信装置が、前記位置情報を前記データベース装置へ通知するステップと、
前記データベース装置が、周波数ごとに、通知された位置情報が示す位置から禁止領域までの第1の方向の距離である第1の距離と、通知された位置情報が示す位置から禁止領域までの第2の方向の距離である第2の距離とを求め、第1の距離および第2の距離を含む距離情報を生成するステップと、
前記データベース装置が、周波数ごとの距離情報を前記移動通信装置へ通知するステップと、
前記移動通信装置が、通知された距離情報および自装置の移動方向に基づいて、通信に利用する周波数を決定するステップと、
を含む、周波数決定方法。 - 前記通信に利用する周波数を決定するステップでは、
周波数ごとに、前記移動通信装置の移動方向についての禁止領域までの距離を、前記距離情報に含まれる第1の距離および第2の距離に基づいて補間によって求める利用可能距離算出工程と、
前記利用可能距離算出工程によって求められた距離のうち最も長い距離を与える周波数を、通信に利用する周波数として決定する周波数選択工程と、
を含む、請求項1に記載の周波数決定方法。 - 前記利用可能距離算出工程では、禁止領域の境界が、前記移動通信装置の現在位置から前記第1の方向に前記第1の距離だけ離れた点と、前記移動通信装置の現在位置から前記第2の方向に前記第2の距離だけ離れた点とを結ぶ直線であると仮定して、前記移動通信装置の移動方向についての禁止領域までの距離を求める、
請求項2に記載の周波数決定方法。 - 前記利用可能距離算出工程では、禁止領域の境界が、前記移動通信装置の現在位置から前記第1の方向に前記第1の距離だけ離れた点と、前記移動通信装置の現在位置から前記第2の方向に前記第2の距離だけ離れた点とを通る楕円であると仮定して、前記移動通信装置の移動方向についての禁止領域までの距離を求める、
請求項2に記載の周波数決定方法。 - 前記利用可能距離算出工程では、禁止領域の境界が、前記移動通信装置の現在位置から前記第1の方向に前記第1の距離だけ離れた点と、前記移動通信装置の現在位置から前記第2の方向に前記第2の距離だけ離れた点とを通る矩形であると仮定して、前記移動通信装置の移動方向についての禁止領域までの距離を求める、
請求項2に記載の周波数決定方法。 - 前記距離情報には、前記移動通信装置から通知された位置情報が示す位置から前記第1の方向にある禁止領域と、前記移動通信装置から通知された位置情報が示す位置から前記第2の方向にある禁止領域とが、同じ領域であるか異なる領域であるかを示す情報が含まれており、
前記利用可能距離算出工程では、
前記第1の方向にある禁止領域と前記第2の方向にある禁止領域とが同じ領域であれば、禁止領域の境界が、前記移動通信装置の現在位置から前記第1の方向に前記第1の距離だけ離れた点と、前記移動通信装置の現在位置から前記第2の方向に前記第2の距離だけ離れた点とを通る楕円であると仮定して、前記移動通信装置の移動方向についての禁止領域までの距離を求め、
前記第1の方向にある禁止領域と前記第2の方向にある禁止領域とが異なる領域であれば、禁止領域の境界が、前記移動通信装置の現在位置から前記第1の方向に前記第1の距離だけ離れた点と、前記移動通信装置の現在位置から前記第2の方向に前記第2の距離だけ離れた点とを通る矩形であると仮定して、前記移動通信装置の移動方向についての禁止領域までの距離を求める、
請求項2に記載の周波数決定方法。 - 前記移動通信装置が、自装置の移動方向を前記データベース装置へ通知するステップ、をさらに含み、
あらかじめ定められた複数の方向の中から、前記移動通信装置の移動方向に最も近い2つの方向を、前記第1の方向および第2の方向として選択する、
請求項1~6のいずれかに記載の周波数決定方法。 - 前記第1の方向および第2の方向は直交する、
請求項7に記載の周波数決定方法。 - 前記第1の方向および第2の方向は、予め定められた90度ずつずれた4つの方向の中から選択される、
請求項8に記載の周波数決定方法。 - 前記距離情報を生成するステップでは、周波数ごとに、前記移動通信装置から通知された位置情報が示す位置から当該周波数が利用不可能な領域までの距離を、予め定められた90度ずつずれた第1~第4の方向について求め、これらの距離を含む距離情報として生成する、
請求項1~6のいずれかに記載の周波数決定方法。 - 前記通信に利用する周波数を決定するステップでは、前記移動通信装置が、自装置の予定移動経路も考慮して、通信に利用する周波数を決定する、
請求項1~10のいずれかに記載の周波数決定方法。 - 前記通信に利用する周波数を決定するステップは、
自装置の予定移動経路を取得する工程と、
前記予定移動経路上に中間点を設定する工程と、
前記中間点における距離情報を前記データベース装置から取得する工程と、
周波数ごとに、現在位置における距離情報に基づいて現在位置の移動方向についての禁止領域までの距離を求め、当該距離が予定移動経路上の次の中間点までの距離を超える場合には、次の中間点における距離情報と当該次の中間点における移動方向に基づいて当該次の中間点の移動方向についての禁止領域までの距離を求め、前記移動通信装置の現在位置から前記次の中間点までの距離と、前記次の中間点において求められた禁止領域までの距離の和を、当該周波数を利用可能な距離として算出する利用可能距離算出工程と、
前記利用可能距離算出工程によって求められた距離のうち最も長い距離を与える周波数を、通信に利用する周波数として決定する周波数選択工程と、
を含む請求項11に記載の周波数決定方法。 - データベース装置と移動通信装置とから構成され、移動通信装置が使用可能な周波数の中から周波数を選択して通信を行う無線通信システムであって、
前記データベース装置は、
免許者が電波を使用している領域である禁止領域を周波数ごとに記憶する禁止領域記憶手段と、
前記移動通信装置から通知される位置情報に基づいて、周波数ごとに、通知された位置情報が示す位置から禁止領域までの第1の方向の距離である第1の距離と、通知された位置情報が示す位置から禁止領域までの第2の方向の距離である第2の距離とを求め、第1の距離および第2の距離を含む距離情報を生成する距離情報生成手段と、
を有し、
前記移動通信装置は、
位置情報を取得する位置情報取得手段と、
位置情報を前記データベース装置へ通知して、前記距離情報を取得する距離情報要求手段と、
通知された距離情報および自装置の移動方向に基づいて通信に利用する周波数を決定する利用周波数決定手段と、
を有する、
無線通信システム。 - 前記利用周波数決定手段は、
周波数ごとに、前記移動通信装置の移動方向についての禁止領域までの距離を、前記距離情報に含まれる第1の距離および第2の距離に基づいて補間によって求め、
求められた距離のうち最も長い距離を与える周波数を、通信に利用する周波数として決定する、
請求項13に記載の無線通信システム。 - 免許者が電波を使用している領域である禁止領域を周波数ごとに記憶するデータベース装置から通知される距離情報に基づいて、使用する周波数を決定して通信する移動通信装置であって、
位置情報を取得する位置情報取得手段と、
位置情報を前記データベース装置へ通知して、当該位置情報が示す位置から禁止領域までの第1の方向の距離である第1の距離と、当該位置情報が示す位置から禁止領域までの第2の方向の距離である第2の距離とを含む距離情報を取得する距離情報要求手段と、
通知された距離情報および自装置の移動方向に基づいて通信に利用する周波数を決定する利用周波数決定手段と、
を有する移動通信装置。 - 前記利用周波数決定手段は、
周波数ごとに、前記移動通信装置の移動方向についての禁止領域までの距離を、前記距離情報に含まれる第1の距離および第2の距離に基づいて補間によって求め、
求められた距離のうち最も長い距離を与える周波数を、通信に利用する周波数として決定する、
請求項15に記載の移動通信装置。 - 免許者が電波を使用している領域である禁止領域を周波数ごとに記憶する禁止領域記憶手段と、
移動通信装置から通知される位置情報に基づいて、周波数ごとに、通知された位置情報が示す位置から禁止領域までの第1の方向の距離である第1の距離と、通知された位置情報が示す位置から禁止領域までの第2の方向の距離である第2の距離とを求め、第1の距離および第2の距離を含む距離情報を生成する距離情報生成手段と、
を有するデータベース装置。 - 前記距離情報生成手段は、前記移動通信装置から通知される移動方向に基づいて、あらかじめ定められた複数の方向の中から、前記移動通信装置の移動方向に最も近い2つの方向を、前記第1の方向および第2の方向として選択する、
請求項17に記載のデータベース装置。 - 前記第1の方向および第2の方向は直交する、
請求項18に記載のデータベース装置。 - 前記距離情報生成手段は、前記第1の方向にある禁止領域と、前記第2の方向にある禁止領域とが、同じ領域であるか異なる領域であるかを示す情報を前記距離情報に含める、
請求項17~19のいずれかに記載のデータベース装置。
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