JP2014155026A - Radio communication device and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress interference to communication in a primary system if a radio communication device moves.SOLUTION: By the acquisition of "idle frequencies of the present position" of the radio communication device and "idle frequencies at a proceeding destination position" of the radio communication device, each boundary position where the idle frequencies are changed over is estimated based on the idle frequencies. When the radio communication device proceeds (moves) from the present position to the proceeding destination position, an idle frequency for use for cognitive radio communication is changed over based on the "estimated boundary position".

Description

  The present invention relates to a radio communication apparatus that performs cognitive radio communication while moving, and more particularly, to a technique for selecting a communication frequency used for cognitive radio communication.

  An existing wireless communication system (referred to as a “primary system”) in which a plurality of wireless communication devices communicate using wireless communication is premised on communication using a pre-assigned frequency. Further, different frequencies are assigned to different primary systems so that communication in one primary system does not interfere with communication in another primary system. However, since the frequency range that can be used for wireless communication is limited, if the number of primary systems increases, there may be a shortage of frequencies to be allocated. Therefore, a communication technology called cognitive radio communication has been attracting attention today, and research and development are being actively promoted.

  Cognitive radio communication is the following communication technology. Although the primary system performs communication using a previously assigned frequency, the assigned frequency is not necessarily continuously used for 24 hours. Therefore, the frequency allocated to the primary system has a time zone that is not actually used. In addition, in a primary system that communicates in a certain area such as a television broadcasting station, the frequency assigned to the primary system is not used outside the area. The cognitive wireless communication is a technology for performing wireless communication using a frequency (called “free frequency” or “white space”) that is not used in time or place by the primary system.

  In this way, cognitive radio communication is a communication technology that uses idle frequencies. However, when cognitive radio communications are performed while a wireless communication device is moving, the frequency being used when moving is entered into an area where the idle frequency is not set. Thus, there is a possibility of interfering with the communication of the primary system. Therefore, a technique has been proposed in which an effective time in which an available frequency can be used is set as an available frequency, and the use of the available frequency is stopped when the effective time elapses (Patent Document 1).

JP 2007-88940 A

  However, the proposed technique has a problem that interference with the communication of the primary system during cognitive radio communication cannot be sufficiently suppressed. This means that when cognitive radio communication is carried out while moving at high speed like a radio communication device mounted on a car, the frequency used for cognitive radio communication is a free frequency by moving a long distance within the effective time. This is because there is a possibility of entering an area that is not.

  The present invention has been made in view of the above-described problems of the prior art, and is capable of suppressing interference with the communication of the primary system even when the wireless communication device moves at high speed. The purpose is to provide technology.

  In order to solve the above-described problem, the wireless communication device and the wireless communication method of the present invention include a “vacant frequency at the current position” of the wireless communication device and an “advance destination position” (hereinafter referred to as “advance destination position”) of the wireless communication device. ) ”, And the boundary position where the vacant frequency is switched is estimated based on these vacant frequencies. Then, the idle frequency used for cognitive radio communication is switched based on the estimated boundary position.

  In this way, the idle frequency used for cognitive radio communication is switched based on the estimated boundary position, so that even when the radio communication device moves at high speed, the interference with the primary system is sufficiently suppressed, while cognitive Wireless communication can be continued. The “advance destination position” may be a predicted position after a predetermined time of the wireless communication device or a predicted position after traveling a predetermined distance of the wireless communication device, and the current position and moving speed of the wireless communication device, It is determined based on the moving direction, map information, and the like.

  In the above-described wireless communication apparatus of the present invention, the boundary position may be estimated as follows. That is, when there is a boundary position between the current current position and the destination position (when the empty frequency at the current position is different from the empty frequency at the destination position), the current position is first set as the first reference point and the destination. A first process using the position as the second reference point is performed. Next, a third reference point is set between the first reference point and the second reference point, and the boundary position is “the first reference point side from the third reference point” or “the second reference point from the third reference point”. It is determined which range is on the “point side”, and a second process is performed in which both ends of the range determined to have the boundary position are set as new first reference points and second reference points. It may be.

  In this way, the range in which the boundary position exists can be narrowed by reducing the distance between the first reference point and the second reference point, so that the estimation accuracy of the boundary position can be increased.

  Further, in the above-described wireless communication apparatus of the present invention, the third process with the first reference point as the boundary position may be performed after the second process is repeated.

  By doing so, the process of narrowing the range where the boundary position exists is repeated, so that the estimation accuracy of the boundary position can be further increased. Further, a reference point on the current position side among the first reference point and the second reference point (first reference point, position on the current position side in the range where the boundary position exists) is estimated as the boundary position. In this way, the current position side is estimated as the boundary position from the actual boundary position (the boundary of the area where the used empty frequency is actually permitted). As a result, the cognitive radio communication can be stopped with a high probability before the radio communication device exceeds the actual boundary position, and further, interference with the primary system can be suppressed.

  In the wireless communication device of the present invention described above, when there is a boundary position between the current position and the destination position (when the empty frequency at the current position is different from the empty frequency at the destination position), the current position The boundary position may be estimated based on the radio wave intensity permitted in communication using the vacant frequency.

  Just because a specified idle frequency is used, it does not mean that radio waves can be output with unlimited radio field strength. This is because, as the radio field intensity increases, the range over which the radio wave reaches increases, so that if the radio wave is output with unlimited radio field intensity, it will interfere with the communication of the surrounding primary system. For this reason, when a vacant frequency is designated, the permission radio wave intensity is also designated in some form. Here, the permitted radio wave intensity is a radio wave intensity that is set so as not to interfere with the surrounding primary system if the radio wave is blown at a lower (or lower) intensity. Of course, if the boundary of the primary system is far away, the permitted radio wave intensity is set to a large value, and conversely, if the boundary is close, the permitted radio wave intensity is set to a small value. Thus, since the permitted radio wave intensity is set according to the distance to the boundary of the surrounding primary system, the distance to the boundary position can be estimated based on the permitted radio wave intensity at the current position.

  In the above-described wireless communication apparatus of the present invention, a communication stop section is set on the current position side from the estimated boundary position, and the cognitive wireless communication is stopped when the wireless communication apparatus is in the communication stop section. May be.

  In this way, even if there is an error between the estimated boundary position and the actual boundary position, the cognitive radio communication that is being executed is stopped before the estimated boundary position. It is possible to further suppress the interference.

It is explanatory drawing which showed notionally the mode that the vehicle 10 performed cognitive radio | wireless communication using the idle frequency of television. It is explanatory drawing which shows the rough radio | wireless communications system 1 for the vehicle 10 to perform cognitive radio | wireless communication. It is explanatory drawing which shows the structure of the radio | wireless communication apparatus 100 of a present Example. It is a flowchart which shows the communication start time control process which the radio | wireless communication apparatus 100 of a present Example performs at the time of a cognitive radio communication start. It is a flowchart which shows the boundary estimation process of a present Example. It is explanatory drawing which illustrates a mode that the "boundary position of the frequency in use" of a present Example is estimated. It is a flowchart which shows the communication execution control process which the radio | wireless communication apparatus 100 of a present Example performs during cognitive radio communication execution. It is explanatory drawing for demonstrating the effect acquired by the radio | wireless communication apparatus 100 of a present Example. 10 is a flowchart showing a communication start time control process of Modification 1; 10 is a flowchart illustrating a communication execution control process according to Modification 1; 10 is a flowchart illustrating a communication execution control process according to Modification 2; It is explanatory drawing which shows a mode that the idle frequency used for the cognitive radio | wireless communication of the modification 2 is switched. FIG. 10 is an explanatory diagram illustrating an example of estimating a “boundary position of in-use frequency” according to Modification 3;

Hereinafter, examples will be described in order to clarify the contents of the present invention described above.
A. Device configuration :
First, an outline of cognitive radio communication performed in the vehicle 10 equipped with the radio communication device 100 of the present embodiment will be briefly described. In this embodiment, cognitive radio communication is performed using a frequency for a system that performs television broadcasting (a kind of primary system). A unique frequency is assigned to each television broadcast station, and each television broadcast station transmits a television signal toward each area using the assigned frequency. In this embodiment, the description will be made on the assumption that cognitive radio communication is performed using a vacant frequency for television broadcasting. Of course, the same applies to the case where cognitive radio communication is performed using a vacant frequency other than a system that performs television broadcasting. The wireless communication device 100 of the present embodiment can be applied.

  FIG. 1 conceptually shows a plurality of television broadcasting stations A to C and areas RA to RC in which the television broadcasting stations transmit television signals. For example, the television broadcast station A transmits a television signal to the region RA, the television broadcast station B transmits a television signal to the region RB, and the television broadcast station C transmits a television signal to the region RC. In addition, each of the television broadcast stations A to C transmits a television signal using a unique frequency assigned in advance. Therefore, in the area RA, the frequency assigned to the television broadcast station B or the television broadcast station C is not used, and in the area RB, the frequency assigned to the television broadcast station A or the television broadcast station C is not used. . Similarly, in the area RC, the frequency allocated to the television broadcast station A or the television broadcast station B is not used. The vehicle 10 performs cognitive radio communication with other vehicles (not shown) using these unused frequencies (vacant frequencies). In addition, each area | region RA-RC where each television broadcasting station A-C transmits a television signal is a vast thing which has a radius of several tens Km. On the other hand, the range in which the vehicle 10 can communicate with other vehicles is typically about 100 m to 150 m in radius. As described above, the areas RA to RC, the communication area of the vehicle 10, and the size of the vehicle 10 are greatly different in digit, but for convenience of display, they are displayed at a ratio different from the actual ratio in FIG. Yes.

  FIG. 2 shows a rough wireless communication system 1 for the vehicle 10 to perform cognitive wireless communication. As shown in the figure, the vehicle 10 is equipped with the wireless communication device 100 of the present embodiment and can be connected to the wireless base station 2. The radio base station 2 is connected to the database 4 through the public communication line network 3. The database 4 stores a large amount of information relating to vacant frequencies. The wireless communication device 100 can acquire necessary data by exchanging data with the vehicle control unit 12 that controls the vehicle 10. The radio base stations 2 are installed in various locations according to the output intensity, population density, and the like of each radio base station 2.

  FIG. 3 shows a detailed configuration of the wireless communication apparatus 100. As shown in the figure, a wireless communication device 100 according to the present embodiment includes a GPS unit 108 and a communication control unit connected to the communication control unit 102 around a communication control unit 102 that controls the overall operation of the wireless communication device 100. The wireless communication unit 104 and the storage unit 106 are connected to the terminal 102 via the bus 110. Among them, the wireless communication unit 104 controls processing of performing wireless communication with the wireless base station 2 (see FIG. 2), other vehicles, and the like under the control of the communication control unit 102. In addition, the storage unit 106 stores the processing result of the communication control unit 102 and various data obtained along with the communication. The GPS unit 108 receives a GPS signal from a GPS satellite (not shown) and detects the current position.

B. Communication control processing:
Next, communication control processing executed when the wireless communication apparatus 100 performs cognitive wireless communication will be described. In the present embodiment, as communication control processing, “communication start control processing” performed at the start of cognitive radio communication and “communication execution control processing” performed during execution of cognitive radio communication are performed. Hereinafter, “communication start control process” and “communication execution control process” will be described in this order.

B-1. Control processing at the start of communication:
FIG. 4 shows a flowchart of the communication start time control process according to this embodiment. This process is started by the communication control unit 102 by the operation of the driver of the vehicle 10 or in response to a request from the vehicle control unit 12. When the communication start control process is started, the communication control unit 102 determines whether or not the wireless communication unit 104 has received a beacon (S100). The beacon is a signal periodically broadcast from the radio base station 2, and the beacon is used for information indicating the address (destination information) of the radio base station 2 that is the transmission source and for communication with the radio base station 2. Information indicating the frequency to be used is included.

  When the wireless communication unit 104 has received a beacon (S100: yes), based on the beacon received from the wireless base station 2, the “wireless base station address (destination information)” and “frequency for communication with the wireless base station” Are specified and stored in the storage unit 106 (S102). The “radio base station address (destination information)” is information for designating a specific radio base station 2 when transmitting a signal from the radio communication device 100, such as the MAC address of the radio base station 2. In other words, by specifying “address of radio base station (destination information)”, it is possible to specify the radio base station 2 with which the radio communication apparatus 100 can communicate. The “frequency for communication with the radio base station” is a frequency used when the radio communication apparatus 100 communicates with the radio base station 2, unlike the idle frequency used for cognitive radio communication.

  Thus, after specifying “the address of the wireless base station (destination information)” and “the frequency for communication with the wireless base station” based on the beacon received from the wireless base station 2, the “current position” and the “destination position” are specified. (S104). This process is performed in the following procedure. The communication control unit 102 transmits a signal instructing the GPS unit 108 to detect the “current position”. Upon receiving this signal, the GPS unit 108 receives a GPS signal from a GPS satellite, detects the “current position”, and transmits the “current position” to the communication control unit 102. When receiving the “current position” from the GPS unit 108, the communication control unit 102 stores the received “current position” in the storage unit 106. Further, the communication control unit 102 determines the predicted position of the wireless communication device 100 (vehicle 10) after a predetermined time based on the “current position”, the moving speed and direction of the wireless communication device 100 (vehicle 10), map information, and the like. The “advance destination position” is specified, and the “advance destination position” is stored in the storage unit 106.

  Thus, when the current position and the destination position are specified (S104), the wireless base station 2 specified in the process of S102 (with the “radio base station address” specified in the process of S102) is added. A first vacant frequency request signal requesting “vacant frequency of position” and “vacant frequency of destination position” is transmitted. Of course, the first vacant frequency request signal is transmitted from the radio communication unit 104 using the “frequency for communication with the radio base station” specified in the process of S102. “Available frequency at current location” is an available frequency that is permitted to be used for cognitive radio communication at the current location, and “Available frequency at destination location” is used for cognitive radio communication at the destination location. It is a free frequency that is allowed to do. Accordingly, the first vacant frequency request signal includes information indicating the current position and the destination position. When the first vacant frequency request signal is transmitted to the radio base station 2 in this way, it waits until it receives the “vacant frequency at the current position” and the “vacant frequency at the destination position” (S108).

  When receiving the first vacant frequency request signal from the wireless communication device 100, the radio base station 2 transmits the first vacant frequency request signal to the database 4 shown in FIG. Here, in the database 4, the “location of the television broadcast station”, “frequency used for transmission of the television signal”, and “frequency used for transmission of the television signal” are associated with each television broadcast station. Is stored in a range that is prohibited from being used (hereinafter referred to as “prohibited range”). When the database 4 receives the first vacant frequency request signal from the radio base station 2, the database 4 specifies the current position and the destination position based on information indicating the current position and the destination position included in the signal. Subsequently, it is determined whether or not each of the current position and the destination position is included in the prohibited range over a preset frequency range. As a result, the frequency where the current position is not included in the prohibited range is specified as “free frequency at the current position”, and the frequency where the destination position is not included in the prohibited range is specified as “free frequency at the destination position”. . Then, the identified “vacant frequency at the current position” and “vacant frequency at the destination position” are transmitted to the radio base station 2. Upon receiving the “vacant frequency at the current position” and the “vacant frequency at the destination position” from the database 4, the radio base station 2 transmits the received “current” to the radio communication apparatus 100 that has transmitted the first vacant frequency request signal. "Free frequency at position" and "Free frequency at destination position" are transmitted.

  When the communication control unit 102 of the wireless communication apparatus 100 receives the “vacant frequency at the current position” and the “vacant frequency at the destination position” (S108: yes), the received “vacant frequency at the current position” and “the destination position” Is stored in the storage unit 106 (S110). Then, among these, the “vacant frequency at the current position” is selected (S112), and cognitive radio communication with another vehicle is started using the selected “vacant frequency at the current position” (S114).

  Subsequently, boundary estimation processing is performed (S116). The idle frequency is a frequency that can be used in a predetermined area because it is a frequency that is not used by the primary system. Therefore, in the boundary estimation process of S116, a process is performed to estimate the boundary position of the area that is permitted to use the “free frequency at the current position” that has been used (used) this time. In the following, the boundary position of the area in which the use of the “free frequency at the current position” that has been started (used) is permitted is expressed as “the boundary position of the used frequency”.

  FIG. 5 shows a flowchart of the boundary estimation process of the present embodiment. When the boundary estimation process is started, the communication control unit 102 compares the “vacant frequency at the current position” and the “vacant frequency at the destination position” stored in the process of S110 in FIG. Is determined (S200). Here, when the “use frequency boundary position” exists between the current position and the destination position, the “current position idle frequency” and the “destination position idle frequency” are different, and the “use frequency boundary position” "Does not exist between the current position and the destination position, the" vacant frequency at the current position "and the" vacant frequency at the destination position "are the same. Therefore, in the determination process of S200, it is determined whether or not the “use frequency boundary position” exists between the current position and the destination position. As a result, when the “boundary position of the used frequency” does not exist between the current position and the destination position (S200: no), the fact is stored in the storage unit 106 (S202).

  On the other hand, when the “boundary position of the used frequency” exists between the current position and the destination position (S200: yes), processing for estimating the boundary position is performed. In this process, first, an intermediate position X3 = (position X2−position X1) / 2 between the position X1 and the position X2 is specified with the current position as the position X1 and the destination position as the position X2 (S204). Then, a free frequency that is permitted to be used for cognitive wireless communication at the specified intermediate position X3 (hereinafter referred to as “free frequency at the intermediate position X3”) for the wireless base station 2 specified in the process of S102 of FIG. ) Is transmitted (S206). Of course, the second vacant frequency request signal is transmitted from the wireless communication unit 104 using the “frequency for communication with the wireless base station” identified in the process of S102 of FIG. The second empty frequency request signal includes information indicating the intermediate position X3. When the second free frequency request signal is transmitted to the radio base station 2 in this way, the process waits until the “free frequency at the intermediate position X3” is received (S208).

  When receiving the second vacant frequency request signal from the wireless communication apparatus 100, the radio base station 2 transmits the second vacant frequency request signal to the database 4 shown in FIG. When the database 4 receives the second vacant frequency request signal from the radio base station 2, the database 4 specifies the intermediate position X3 based on the information indicating the intermediate position X3 included in the signal. Subsequently, it is determined whether or not the intermediate position X3 is included in the prohibited range over a preset frequency range, and the frequency at which the intermediate position X3 is not included in the prohibited range is determined as “free space in the intermediate position X3. Identified as "frequency". Then, the identified “free frequency at the intermediate position X3” is transmitted to the radio base station 2. When receiving the “vacant frequency at the intermediate position X3” from the database 4, the radio base station 2 transmits the received “vacant frequency at the intermediate position X3” to the wireless communication device 100 that has transmitted the second empty frequency request signal. To do.

  When the communication control unit 102 of the wireless communication apparatus 100 receives the “vacant frequency at the intermediate position X3” (S208: yes), the free frequency permitted to be used for cognitive wireless communication at the position X1 (hereinafter “position X1”). Are compared with the received “free frequency at the intermediate position X3” to determine whether or not they are different from each other (S210). Of course, here, since the “vacant frequency at the position X1” is the “vacant frequency at the current position”, the “vacant frequency at the current position” and the “vacant frequency at the intermediate position X3” are compared.

  FIG. 6 illustrates a state in which the “boundary position of the in-use frequency” according to the present embodiment is estimated. As shown in the upper part of FIG. 6A, when the “use frequency boundary position” exists between the position X1 (here, the current position) and the intermediate position X3, the “free frequency at position X1” (FIG. Middle “ch1”) and “empty frequency at intermediate position X3” (“ch2” in the figure) are different. On the other hand, as shown in the upper part of FIG. 6B, when the boundary position of the use-permitted area of “free frequency at position X1” does not exist between the position X1 and the intermediate position X3, the boundary already exists. Since it is determined that the position exists between the position X1 and the position X2 (here, the destination position) (S200: yes), the boundary position exists between the intermediate position X3 and the position X2. is there. In this case, “vacant frequency at position X1” (“ch1” in the figure) and “vacant frequency at intermediate position X3” (“ch1” in the figure) are the same. Therefore, in the determination process of S210 in FIG. 5, it is determined whether the “boundary position of the used frequency” exists between the position X1 and the intermediate position X3 or between the intermediate position X3 and the position X2. .

  As a result, when it is determined that the “use frequency boundary position” exists between the position X1 and the intermediate position X3 (S210: yes in FIG. 5), the intermediate position X3 is newly set as the position X2 (S212). FIG. 6 (a)). On the other hand, when it is determined that the “use frequency boundary position” exists between the intermediate position X3 and the position X2 (S210: no), the intermediate position X3 is newly set as the position X1 (S214, (Refer FIG.6 (b)). As described above, by performing the processing of S204 to S214, at least one of the position X1 and the position X2 can be brought close to the “boundary position of the use frequency”, so the distance between the position X1 and the position X2, that is, “use” The range where the “frequency boundary position” exists can be narrowed. As described above, in the wireless communication apparatus 100 according to the present embodiment, the intermediate position X3 is set, and the boundary position is “between the position X1 and the intermediate position X3” or “between the intermediate position X3 and the position X2”. Are determined to be within the range, and both ends of the range in which the boundary position is determined to be the new first reference point and the second reference point (S204 to S214). The process of narrowing the range where “the boundary position of” exists is performed. In the wireless communication apparatus 100 according to the present embodiment, the process of narrowing the range in which the “use frequency boundary position” exists is repeated a predetermined number of times. Of course, the greater the number of repetitions of this process, the narrower the range in which the “use frequency boundary position” exists.

  When the process of narrowing the range where the “use frequency boundary position” exists (S204 to S214) is repeated a predetermined number of times (S216: yes), the position X1 is stored in the storage unit 106 as the “use frequency boundary position”. In other words, the position X1 that is the position closest to the current position in the range where the “use frequency boundary position” exists (is estimated).

  As described above, when starting the cognitive radio communication, the wireless communication device 100 according to the present embodiment acquires the “vacant frequency at the current position” and the “vacant frequency at the destination position”, and the “vacant frequency at the current position”. Cognitive radio communication using " Also, if a “use frequency boundary position” exists between the current position and the destination position, the “use frequency boundary position” is estimated and stored.

  Note that the communication control unit 102 of the wireless communication apparatus 100 receives and stores a list of “current position free frequencies” when there are a plurality of “current position free frequencies”. Select “Free position frequency”. If there are a plurality of “vacant frequencies at the destination location”, a list of “vacant frequencies at the destination location” is received and stored. If there are a plurality of “vacant frequencies at the intermediate position X3”, a list of “vacant frequencies at the intermediate position X3” is received and stored. Then, in the determination process of S200 in FIG. 5, it is determined whether or not the boundary position of “the vacant frequency of the current position” that has started (used) this time is between the current position and the destination position. Therefore, it is determined whether or not the “free frequency at the current position” that has started (used) this time is included in the list of “free frequency at the destination position”. Similarly, in the determination process of S210 in FIG. 5, the boundary position of “the vacant frequency of the current position” that has started (used) this time is “between position X1 and intermediate position X3” or “intermediate position X3 and Since it is only necessary to determine which range is “between the position X2” and “free frequency at the current position” that has been used (used) this time is included in the list of “free frequency at the intermediate position X3”. To determine whether or not

  Further, in the process of S112 of FIG. 4, when the same idle frequency as the “vacant frequency at the destination position” is included in the “vacant frequency at the current position” list, the empty frequency may be selected. . This makes it possible to use the “vacant frequency at the current position” at which the use starts, even at the destination position, so that the distance that can be moved without switching the idle frequency used for cognitive radio communication can be increased.

B-2. Control processing during communication:
FIG. 7 shows a flowchart of the communication execution control process of this embodiment. This process is periodically executed by the communication control unit 102 during execution of cognitive radio communication. When the communication execution control process is started, it is determined whether or not the “use frequency boundary position” is stored (S300). As a result, when the “use frequency boundary position” is not stored (S300: no), it is determined whether or not the wireless communication device 100 (vehicle 10) has moved a predetermined distance (for example, 100 m) (S304). ). Further, even when the “use frequency boundary position” is stored (S300: yes), if the wireless communication apparatus 100 has not moved to the “use frequency boundary position”, the wireless communication apparatus 100 is predetermined. It is determined whether or not the distance has been moved (S304).

  When the wireless communication apparatus 100 moves a predetermined distance, the current position and the destination position are newly specified as in S100 to S110 of FIG. 4, and the “free frequency at the current position” and “progress” corresponding thereto are specified. The “vacant frequency at the previous position” is stored in the storage unit 106 (S306 to S316). Then, similarly to S116 of FIG. 4, a process (boundary estimation process) for newly estimating and storing “boundary position of used frequency” is performed (S318). As described above, the wireless communication device 100 according to the present embodiment estimates and stores the “boundary position of the used frequency” every time the vehicle travels a predetermined distance. The predetermined distance is a distance that is equal to or less than the distance from the current position to the destination position. This makes it possible to increase the probability that the “use frequency boundary position” is estimated prior to the entry of the wireless communication device 100 in the region where the wireless communication device 100 (vehicle 10) enters. As a result, the wireless communication device 100 can be prevented from entering an area where the “use frequency boundary position” is not estimated, and cognitive wireless communication interferes with the primary system (here, a system that performs television broadcasting). It is possible to suppress this.

  On the other hand, if it is determined in S300 that the “use frequency boundary position” is stored (S300: yes), the wireless communication device 100 (vehicle 10) moves to the “use frequency boundary position”. It is determined whether or not it has been done (S302). And if the radio | wireless communication apparatus 100 moves to the "boundary position of a use frequency" (S302: yes), the cognitive radio communication currently performed will be stopped (S320). That is, since the “use frequency boundary position” is a boundary of an area in which a vacant frequency being used can be used, cognitive radio communication using the vacant frequency is stopped. Next, the “Destination frequency that can be used for cognitive radio communication with the“ Frequency frequency at the destination location ”stored when the“ Boundary location of the usage frequency ”was previously estimated, that is, the“ Boundary location of the usage frequency ”. “Free position frequency” is selected (S322). Then, cognitive radio communication with another vehicle is started using the selected “vacant frequency at the destination position” (S324). As described above, when the wireless communication apparatus 100 according to the present embodiment moves to the “boundary position of the used frequency”, it switches the free frequency being used for the cognitive wireless communication to the “free frequency at the destination position”.

  FIG. 8 is an explanatory diagram for explaining an effect obtained by the wireless communication device 100 according to the present embodiment. As shown in FIG. 8A, the wireless communication device 100 (vehicle 10) of the present embodiment every time it moves a predetermined distance (a distance equal to or less than the distance from the current position to the destination position, for example, 100 m). Estimate and store “boundary position of operating frequency”. Then, as shown in FIG. 8B, the wireless communication device 100 (vehicle 10) according to the present embodiment stops the cognitive wireless communication being executed and moves to “use” when it moves to the “use frequency boundary position”. The cognitive radio communication is started using the “vacant frequency at the destination position” that can be used for the cognitive radio communication at the “frequency boundary position”. In other words, the vacant frequency being used for cognitive radio communication is switched to the “vacant frequency at the destination position”.

  Accordingly, the wireless communication device 100 according to the present embodiment estimates the “boundary position of the used frequency” and does not switch the unused frequency until it moves to this “boundary position of the used frequency”. Thus, it is possible to continue cognitive radio communication without frequently switching. In addition to estimating the “use frequency boundary position”, the “use frequency boundary position” is used as a boundary to switch to the “free frequency at the destination position” that can be used for cognitive radio communication. Thus, cognitive radio communication can be continued while suppressing interference with the primary system (system that performs television broadcasting).

  In addition, the wireless communication device 100 according to the present embodiment estimates the “boundary position of the used frequency” every time it moves a predetermined distance, that is, “a distance equal to or less than the distance from the current position to the destination position”. Therefore, it is possible to increase the probability that the “use frequency boundary position” is estimated prior to the entry of the wireless communication device 100 in the region where the wireless communication device 100 (vehicle 10) enters. As a result, the wireless communication apparatus 100 can be prevented from entering an area where the “use frequency boundary position” is not estimated, and the cognitive wireless communication can be further prevented from interfering with the primary system. It becomes.

  Further, when estimating the “use frequency boundary position”, the wireless communication apparatus 100 according to the present embodiment, as described above with reference to FIG. 6, uses “use frequency” between two positions (position X1 and position X2). If there is a “boundary position”, a process of bringing at least one of the two positions closer to the “boundary position of the used frequency”, that is, a range where the “boundary position of the used frequency” exists by reducing the distance between the two positions. Narrow. Therefore, it is possible to improve the estimation accuracy of the “use frequency boundary position”. In addition, the position closest to the current position among the two positions, that is, the position closest to the current position in the range where the “use frequency boundary position” exists is set as the “use frequency boundary position”. The cognitive radio communication being executed at the “boundary position” is stopped. Therefore, the cognitive radio communication being performed can be stopped before the radio communication device 100 (vehicle 10) exceeds the “boundary of the area where the available unused frequency is actually permitted”, and the primary system It is possible to suppress interference.

  In addition, when there is a “use frequency boundary position” between two positions (position X1 and position X2), the wireless communication apparatus 100 according to the present embodiment sets at least one of the two positions as “use frequency boundary. Since the process of approaching the “position” is repeated, the distance between the two positions can be further reduced to narrow the range in which the “use frequency boundary position” exists. Accordingly, it is possible to further improve the estimation accuracy of the “boundary position of the used frequency”.

  The communication control unit 102 acquires current position information indicating the current position of the wireless communication apparatus 100, and therefore corresponds to the “current position acquisition unit” in the present invention. Further, since the communication control unit 102 acquires the destination position information indicating the position of the destination of the wireless communication apparatus 100, the communication control unit 102 corresponds to the “destination position acquisition unit” in the present invention. Further, since the communication control unit 102 acquires current position frequency information indicating a vacant frequency of the current position and destination position frequency information indicating a vacant frequency of the destination, it corresponds to the “frequency information acquisition unit” in the present invention. ing. Further, since the communication control unit 102 estimates the boundary position of the use frequency (the boundary position where the vacant frequency changes) based on the vacant frequency at the current position and the vacant frequency at the destination, the “boundary estimating means” in the present invention. It corresponds to. Further, the communication control unit 102 switches the idle frequency used for cognitive radio communication when the radio communication device 100 moves from the current position to the destination position based on the boundary position (boundary position) of the use frequency. Corresponds to “switching means” in FIG. Further, when the vacant frequency at the current position is different from the vacant frequency at the destination, the communication control unit 102 first sets the current position as the position X1 (first reference point) and the destination position as the position X2 (second reference point). ) (First process). Next, an intermediate position (predetermined position) between the position X1 (first reference point) and the position X2 (second reference point) is set as an intermediate position X3 (third reference point), and “empty intermediate position X3” "Frequency" (third reference point frequency information indicating the empty frequency of the third reference point) is acquired, and "empty frequency of the position X1" (empty frequency of the first reference point) and "empty frequency of the intermediate position X3" (first As a result of comparison with the vacant frequencies of the three reference points), if the vacant frequencies are different, the intermediate position X3 (third reference point) is set as a new position X2 (second reference point), and if the vacant frequencies are the same, the intermediate position X3 The process (second process) with the (third reference point) as a new position X1 (first reference point) is repeated a predetermined number of times (until a predetermined condition is satisfied). Then, a process (third process) is performed in which the position X1 (first reference point) is “boundary position of the used frequency” (boundary position). Therefore, the communication control unit 102 corresponds to “first processing means”, “second processing means”, and “third processing means” in the present invention.

C. Modified example:
Next, a modification of the present embodiment will be described.

C-1. Modification 1
In the embodiment described above, the “use frequency boundary position” is estimated every time the wireless communication apparatus 100 moves a predetermined distance, and when the wireless communication apparatus 100 reaches the “use frequency boundary position”, the cognitive wireless communication is performed. It was decided to switch the frequency to be used to “Available frequency at destination”. Not limited to this, when the wireless communication apparatus 100 reaches the “use frequency boundary position”, the frequency used for the cognitive wireless communication is switched to the “vacant frequency at the destination position” and the next “use frequency boundary” The “position” may be estimated.

  FIG. 9 shows a flowchart of the communication start time control process of the first modification. This process is started by the communication control unit 102 by the operation of the driver of the vehicle 10 or in response to a request from the vehicle control unit 12. When the communication start time control process of Modification 1 is started, the communication control unit 102 specifies the communication environment with the radio base station 2 (S400 to S402) in the same manner as S100 to S102 of FIG. Is identified (S404). Subsequently, the “vacant frequency at the current position” is acquired from the radio base station 2 and stored (S406 to S410). Then, the cognitive radio communication using the “vacant frequency at the current position” is started (S412 to S414).

  Subsequently, after specifying the “destination location” (S416), the “vacant frequency at the destination location” is acquired from the radio base station 2 and stored (S418 to S422). Then, the “vacant frequency at the current position” and the “vacant frequency at the destination position” are compared to determine whether they are different from each other (S424). That is, it is determined whether or not the “use frequency boundary position” exists between the current position and the destination position.

  As a result, when the “boundary position of the used frequency” does not exist between the current position and the destination position (S424: no), the wireless communication device 100 (vehicle 10) after a predetermined time further than the destination position. Is determined as a new destination position (S416). Then, a vacant frequency of a new destination position is acquired (S418 to S422), and it is determined whether or not a “use frequency boundary position” exists between the current position and the destination position (S424). The processes of S416 to S422 are repeated until the “use frequency boundary position” exists between the current position and the destination position. In other words, the destination position is moved away from the current position until a “use frequency boundary position” is found.

  When the “use frequency boundary position” exists between the current position and the destination position (S424: yes), the “use frequency boundary position” is estimated in the same manner as in S116 of FIG. And storing (border estimation process) (S426). Since the process of determining whether or not the “use frequency boundary position” exists between the current position and the destination position has already been performed, in the boundary estimation process of the first modification, FIG. The processes of S200 and S202 shown are not performed. As described above, the wireless communication device 100 according to the first modification keeps the destination position away from the current position until the “boundary position of the used frequency” exists between the current position and the destination position. If the “boundary position of the used frequency” exists between the current position and the destination position, the “boundary position of the used frequency” is estimated. Therefore, it is possible to estimate the “boundary position of the used frequency” that exists at a position away from the current position.

  FIG. 10 shows a flowchart of the communication execution control process of the present modification. This process is periodically executed by the communication control unit 102 during execution of cognitive radio communication. When the communication execution control process of this modification is started, it is determined whether or not the wireless communication device 100 (vehicle 10) has moved to the “boundary position of the used frequency” (S500). And if the radio | wireless communication apparatus 100 (vehicle 10) moves to the "boundary position of use frequency" (S500: yes), the cognitive radio communication currently performed will be stopped (S502). Then, the cognitive radio communication is started using the “free frequency at the destination position” stored when the “boundary position of the used frequency” was estimated last time (S504 to S506).

  Next, as in S400 to S410 of FIG. 9, the current position is specified and “free frequency at the current position” is acquired (S508 to S518). Then, as in S416 to S426 in FIG. 9, the destination position is set to the current destination position until the “use frequency boundary position” is located between the current position and the destination position. When the "use frequency boundary position" is located between the current position and the destination position, the "use frequency boundary position" is estimated (S520 to S526).

  As described above, the wireless communication device 100 according to the first modification estimates the “use frequency boundary position” even when the “use frequency boundary position” exists at a position away from the current position. . When the wireless communication device 100 reaches the “use frequency boundary position”, the frequency used for the cognitive wireless communication is switched to the “vacant frequency at the destination position”, and the next “use frequency boundary position” is set. presume. In this case, not only the next “use frequency boundary position” (here, referred to as “first boundary position”) but also the next “use frequency boundary position” (here referred to as “second boundary position”) is previously set. You may make it estimate. That is, “the destination position from the first boundary position” is separated from the “first boundary position”, and the “second boundary position” is “the first boundary position” and “the destination position from the first boundary position”. If the second boundary position exists, the “second boundary position” may be estimated. In this way, even if the vacant frequency cannot be received at the “first boundary position” close to the wireless communication apparatus 100 due to congestion of the public communication line network, the vacant frequency has already been received at the “second boundary position”. In addition, since the next “boundary position of the used frequency” is estimated, it is possible to reduce the cognitive radio communication from interfering with the primary system at the “second boundary position”.

C-2. Modification 2
In the embodiment described above, at the timing when the wireless communication device 100 reaches the “boundary position of the used frequency”, the cognitive wireless communication that is being executed is stopped and the cognitive wireless communication that uses the “vacant frequency at the destination position” is performed. It was decided to start. However, the present invention is not limited to this, and the cognitive radio communication that is being executed may be stopped and the cognitive radio communication using the “vacant frequency at the destination position” may be started at the following timing.

  FIG. 11 shows a flowchart of the communication execution control process of the second modification. The communication execution control process of the second modification is different from the communication execution control process (FIG. 7) of the embodiment in the process surrounded by a broken line in the figure. That is, in the communication execution control process according to the second modification, the wireless communication device 100 is separated from the position before the “use frequency boundary position” (for example, the “use frequency boundary position” by a predetermined distance toward the current position). When the position is reached (S602: yes), the cognitive radio communication being executed is stopped (S620). When the wireless communication device 100 reaches the “boundary position of the used frequency” (S622: yes), the cognitive wireless communication using the “vacant frequency at the destination position” is started (S624 to S626).

  As illustrated in FIG. 12, the wireless communication device 100 according to the second modification stops the cognitive wireless communication being performed at a position before “the boundary position of the used frequency”, and the “boundary position of the used frequency” indicates “ Start cognitive radio communication using "free frequency at destination position". Therefore, even if there is an error between the estimated "use frequency boundary position" and the actual "use frequency boundary position", the cognitive that is being executed before the estimated "use frequency boundary position". Since the wireless communication is stopped, it is possible to further suppress the cognitive wireless communication from interfering with the primary system.

  Here, by performing the boundary estimation process described above with reference to FIG. 6, the position X1 that is close to the “use frequency boundary position” is set as a position at which the cognitive radio communication being executed is stopped, and the “use frequency boundary position” The position X2 that is close to the position may be a position at which cognitive wireless communication using the “vacant frequency at the destination position” is started. In this way, the wireless communication apparatus 100 is executing cognitive wireless communication (using the free frequency at the current position) at the position X1 that is the position closest to the current position in the range where the “use frequency boundary position” exists. And the wireless communication device 100 performs cognitive wireless communication using the “free frequency at the destination position” at the position X2 that is the position on the most destination position side in the range where the “use frequency boundary position” exists. Will start. As a result, it is possible to further suppress the cognitive radio communication from interfering with the primary system.

  As described above, the communication control unit 102 wirelessly transmits a section (communication stop section set on the current position side from the boundary position) from the position before the “use frequency boundary position” to the “use frequency boundary position”. When there is the communication device 100, the cognitive radio communication is stopped. Therefore, the communication control unit 102 corresponds to the “communication stop unit” in the present invention.

C-3. Modification 3
In the above-described embodiment, the predicted position of the wireless communication device 100 (vehicle 10) after a predetermined time is specified as the “advance destination position”. In this modification, the “advance destination position” is specified as follows.

  In this modification, in specifying the “destination position”, first, the radio base station 2 determines the radio field strength (permitted radio field strength) permitted in the cognitive radio communication using the “vacant frequency at the current position” from the database 4. To get through. As shown in FIG. 13, the permitted radio field intensity is a radio field intensity permitted within a range that does not interfere with the primary system. In other words, the permitted radio wave intensity corresponds to the distance from the current position to the “use frequency boundary position”, and if the permitted radio wave intensity is small, it is assumed that the “use frequency boundary position” is close to the current position (see FIG. 13 (a)), if the permitted radio wave intensity is high, it is estimated that the “use frequency boundary position” is far from the current position (see FIG. 13B). Therefore, in the present modification, when the permitted radio wave intensity is less than a predetermined value, that is, when it is estimated that the “boundary position of the used frequency” is close to the current position, “after the first predetermined time of the wireless communication device 100” When the permitted radio wave intensity is greater than or equal to a predetermined value, that is, when the “use frequency boundary position” is estimated to be far from the current position, the wireless communication device 100 The predicted position “after a second predetermined time longer than the first predetermined time” is specified as the “advance destination position”.

  In this way, the “advance destination position” is set closer to the “use frequency boundary position” than when the predicted position of the wireless communication device 100 (vehicle 10) after a predetermined time is specified as the “advance destination position”. can do. As a result, it is possible to reduce the number of times of the process of estimating the “use frequency boundary position” (the processes of S204 to S216 in FIG. 5), thereby reducing the processing load on the communication control unit 102 and the load on the public communication line network. However, it is possible to reduce the interference of the cognitive radio communication with the primary system.

  Note that the communication control unit 102 determines, based on the permitted radio wave intensity (the radio wave intensity permitted in communication using the idle frequency at the current position) when the idle frequency at the current position is different from the idle frequency at the destination. Estimate the “frequency boundary position”. Therefore, the communication control unit 102 corresponds to “boundary estimation means” in the present invention.

  As described above, the wireless communication device 100 according to the present embodiment and the modification has been described. However, the present invention is not limited to the above-described embodiment and the modification, and may be implemented in various modes without departing from the gist thereof. it can.

1 ... wireless communication system, 2 ... wireless base station, 3 ... public communication network,
4 ... database, 10 ... vehicle, 12 ... vehicle control unit,
DESCRIPTION OF SYMBOLS 100 ... Wireless communication apparatus, 102 ... Communication control part, 104 ... Wireless communication part,
106 ... Storage unit, 108 ... GPS unit, 110 ... Bus

Claims (6)

A wireless communication device that performs cognitive wireless communication using a vacant frequency that is not used by a party who has been assigned a frequency used for wireless communication,
Current position acquisition means for acquiring current position information indicating the current position of the wireless communication device;
Progress destination position acquisition means for acquiring destination position information indicating the position of the destination of the wireless communication device;
Frequency information acquisition means for acquiring current position frequency information indicating the empty frequency of the current position and destination position frequency information indicating the empty frequency of the destination;
Boundary estimation means for estimating a boundary position where the vacant frequency changes based on the vacant frequency of the current position and the vacant frequency of the destination
A wireless communication apparatus comprising: switching means for switching the idle frequency used for the cognitive wireless communication based on the boundary position when the wireless communication apparatus moves from the current position to the destination position. The wireless communication device according to claim 1,
The boundary estimation means includes
First processing means for performing a first process using the current position as a first reference point and the destination position as a second reference point when the empty frequency at the current position is different from the empty frequency at the destination. When,
After the first process is performed, a third reference point that is a predetermined position between the first reference point and the second reference point is a third reference point and indicates the free frequency of the third reference point. When the point frequency information is acquired and the free frequency of the first reference point and the free frequency of the third reference point are compared, if the free frequency is different, the third reference point is replaced with the new second reference point. And a second processing means for performing a second process using the third reference point as a new first reference point when the idle frequencies are the same. The wireless communication device according to claim 2,
The second processing means is means for repeating the second processing until a predetermined condition is satisfied,
A wireless communication apparatus comprising: third processing means for performing a third process using the first reference point as the boundary position after the second process is performed. The wireless communication device according to claim 1,
The boundary estimation means includes
Means for estimating the boundary position based on radio wave intensity permitted in communication using the empty frequency at the current position when the empty frequency at the current position is different from the empty frequency at the destination A wireless communication device. A wireless communication device according to any one of claims 1 to 4,
A wireless communication device comprising communication stop means for stopping the cognitive wireless communication when the wireless communication device is in a communication stop section set on the current position side from the boundary position. A wireless communication method for performing cognitive wireless communication using a vacant frequency that is not used by a party who has been assigned a frequency used for wireless communication,
Obtaining current position information indicating the current position of the wireless communication device;
Obtaining destination position information indicating a destination position of the wireless communication device;
Obtaining current position frequency information indicating the empty frequency of the current position and destination position frequency information indicating the empty frequency of the destination; and
Estimating a boundary position where the idle frequency changes based on the idle frequency of the current position and the idle frequency of the destination;
Switching the idle frequency used for the cognitive radio communication based on the boundary position when the radio communication device moves from the current position to the destination position.

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