JP6241619B2 - Frequency management apparatus and frequency management method in wireless system - Google Patents

Description

  The present invention relates to a radio system, and more particularly, to a frequency management apparatus and a frequency management method for managing frequency usage of a radio station.

  Cognitive radio that recognizes the surrounding radio environment and optimizes communication parameters according to the radio environment is known, but another radio communication system shares the frequency band allocated to one radio communication system It is necessary to consider the problem of interference. Hereinafter, the primary system (interfered system) is the system to which the frequency band is originally allocated and suffers interference, the secondary system (interfering system) is the system that gives interference by secondary use of the frequency band, and the primary system These receiving stations are called primary receiving stations, and the transmitting station of the secondary system is called a secondary transmitting station.

  When the secondary system shares the frequency band with the primary system, the secondary system needs to prevent the existing service provided by the primary system from being affected. Therefore, the transmission power of the secondary transmission station needs to be adjusted to be equal to or lower than the maximum transmission power that allows the primary reception station to maintain a predetermined reception quality. Hereinafter, the maximum transmission power is referred to as allowable transmission power, and the actual transmission power adjusted to be equal to or less than the maximum transmission power is referred to as actual transmission power. Here, as a standard for maintaining a predetermined reception quality, a CIR (Carrier to Interference Ratio) or a CINR (Carrier to Interference plus Noise Ratio) of the primary receiving station is maintained at a predetermined value or higher, It is conceivable to set the amount of interference to a predetermined value or less.

  A system for controlling the transmission power of the secondary transmitting station so as not to interfere with the primary receiving station is disclosed in Patent Document 1, for example. According to Patent Document 1, a value obtained by equally dividing the interference power allowable in the primary reception station (hereinafter referred to as allowable interference power) by the number of secondary transmission stations is calculated, and interference by the secondary transmission station is equal to or less than the value. The allowable transmission power is calculated as follows. Thereby, the total interference by the plurality of secondary transmission stations is suppressed to be equal to or lower than the allowable interference power, and a predetermined reception quality can be maintained at the primary reception station even when the plurality of secondary transmission stations transmit simultaneously.

  Hereinafter, an outline of a system configuration as assumed in Patent Document 1 will be described with reference to FIG. In FIG. 1, the spectrum manager SM (coordinator in Patent Document 1) manages the frequency usage of the secondary transmission station Ts. In particular, the spectrum manager SM1 manages the secondary transmission stations Ts11 and Ts12, and the spectrum manager SM2 is the secondary transmission station. Ts21 and Ts22 are managed. Further, the spectrum managers SM1 and SM2 share information on the secondary transmission stations Ts under their management via a common database DB (management node in Patent Document 1). According to Patent Literature 1, two allowable transmission power determination processes of a centralized type and a cooperative distributed type are disclosed.

  In the centralized type, information of a plurality of secondary transmission stations Ts is collected in the database DB, and the database DB calculates the allowable transmission power of all secondary transmission stations Ts (Ts11, Ts12, Ts21, Ts22). The calculated allowable transmission power is notified to the managed secondary transmission station Ts via each spectrum manager SM.

  In the cooperative distributed type, the spectrum managers SM share information (for example, the total number of secondary transmission stations) regarding the secondary transmission stations Ts under their management via the database DB. Each spectrum manager (eg, SM1) takes into account the interference that a secondary transmitting station (eg, Ts21, Ts22) managed by another spectrum manager (eg, SM2) gives to the primary receiving station, and is under its own management. The allowable transmission power of the secondary transmission station (for example, Ts11, Ts12) is calculated.

JP 2011-166721 A

  However, the technique described in Patent Document 1 increases the amount of processing required for calculating the allowable transmission power regardless of whether it is a centralized type or a cooperative distributed type. Hereinafter, this problem will be described.

  In the centralized type, the database DB calculates the allowable transmission power of each secondary transmitting station Ts in the coordinated distributed type. Each time the secondary transmitting station Ts changes the frequency usage status, (Every time you start or stop using the frequency) Therefore, when the total number of secondary transmitting stations that are using the frequency increases, there is a high possibility that changes in the frequency usage status such as start and stop of frequency usage will frequently occur. Each time the database DB or spectrum manager SM calculates the allowable transmission power for all secondary transmission stations that are using the frequency, the processing amount increases.

Furthermore, when the allowable transmission power is determined as follows, the increase in the amount of processing becomes significant. For example, as shown in FIG. 1, it is assumed that a plurality of primary receiving stations Rp (here, Rp1, Rp2, Rp3) exist in the service area (primary system service area) of the primary transmitting station Tp. The allowable transmission power of the secondary transmission station Ts is determined so that all primary reception stations Rp can maintain a predetermined reception quality in consideration of interference from each secondary transmission station Ts to each primary reception station Rp. There is a need to. If the allowable transmission power of the n-th secondary transmission station (1 ≦ n ≦ N) (this allowable transmission power is equivalent isotropic radiated power taking the antenna gain into account) is P (n), the m-th interference I _m of the primary receiving station (1 ≦ m ≦ M) can be represented by the following formula (1).

Here, L _{n, m} is a path loss from the n-th secondary transmitting station to the m-th primary receiving station, and is calculated using a propagation model such as a Hata formula. For the sake of simplicity, Equation (1) above assumes that the receiving antenna gain of the m-th primary receiving station is 1, and the influence of shadowing on the interference signal is also omitted. I _{max, m} is the allowable interference power of the m-th primary receiving station, and the total interference value I _m needs to be less than or equal to this value as shown in the inequality of equation (1). That is, in order to set the total interference value in all the primary receiving stations as the allowable interference power, the combination of the allowable transmission powers of the secondary transmission stations satisfying the inequality of Expression (1) for all m (1 ≦ m ≦ M) { P (1), P (2),..., P (N)} need to be searched.

  However, the combinations of allowable transmission powers of secondary transmission stations that satisfy the inequality of equation (1) for all m rapidly increase as the number of secondary transmission stations increases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a frequency management method capable of suppressing an increase in the amount of calculation when determining the allowable transmission power of a transmission station in a system on the interference side, and It is to provide an apparatus and a wireless system.

A frequency management device according to the present invention is a frequency management device that manages the frequency usage of a radio station in a radio system that shares a frequency allocated to another radio system,
Targeting frequency use accepting means for accepting a frequency use status change notification from a first radio station that changes frequency use status, and a second radio station whose interference reach range overlaps at least a part of the interference reach range of the first radio station And an allowable transmission power setting means for setting an allowable transmission power , wherein the allowable transmission power setting means is a medium in the second radio station having an interference reachable range that overlaps an interference reachable range of the first radio station. Then, the overlapping range of the interference reachable range is limited to the second radio station that overlaps at least a part of the service range of another radio system, and is set as the setting target of the allowable transmission power. .
A frequency management method according to the present invention is a frequency management method for managing the frequency usage of a radio station in a radio system sharing a frequency allocated to another radio system, wherein the frequency usage accepting unit changes the frequency usage status. The frequency utilization status change notification is received from one radio station, and the allowable transmission power setting means further includes the interference among the second radio stations where the interference coverage overlaps at least a part of the interference coverage of the first radio station. The overlapping range of the reachable range is limited to the second radio station that overlaps at least a part of the service range of the other radio system, and is set as the setting target of the allowable transmission power .
A radio system according to the present invention is a radio system sharing a frequency allocated to another radio system, and a plurality of radio stations sharing the frequency and at least one managing frequency use of the plurality of radio stations. A frequency management device, and when the frequency management device receives a notification regarding a change in frequency usage status from the first radio station, based on the notified change in the frequency status, the interference of the first radio station Among the second radio stations in which at least a part of the reachable range overlaps with the interference reachable range, the overlapped range of the interference reachable range is further transmitted to the second radio station that overlaps at least part of the service range of the other radio system. It is limited, and it is set as the setting object of the said permissible transmission power .

  ADVANTAGE OF THE INVENTION According to this invention, the increase in the computational complexity at the time of determining the allowable transmission power of the transmission station in the system of the side which gives interference can be suppressed.

FIG. 1 is a schematic system configuration diagram for explaining the background art. FIG. 2 is a system configuration diagram for explaining the radio communication system according to the first embodiment of the present invention. FIG. 3 is a block diagram showing a schematic configuration of the frequency management device (spectrum manager) according to the first embodiment. FIG. 4 is a flowchart showing the operation of the spectrum manager shown in FIG. FIG. 5 is a system configuration diagram illustrating an example of an interference arrival area in the first embodiment. FIG. 6 is a sequence diagram showing a first operation example when there is a transmission start request in the wireless system according to the first embodiment. FIG. 7 is a sequence diagram showing an operation when there is a transmission stop notification in the wireless system according to the first embodiment. FIG. 8 is a sequence diagram showing a second operation example when there is a transmission start request in the wireless system according to the first embodiment. FIG. 9 is a system configuration diagram for explaining a radio communication system according to the second embodiment of the present invention. FIG. 10 is a diagram illustrating an example of a management area configuration of the wireless system according to the second embodiment. FIG. 11 is a system configuration diagram for explaining a radio communication system according to the third embodiment of the present invention. FIG. 12 is a block diagram showing a schematic configuration of a frequency management device (spectrum manager) according to the third embodiment. FIG. 13 is a system configuration diagram for explaining a radio communication system according to a fourth embodiment of the present invention. FIG. 14 is a block diagram showing a schematic configuration of a frequency management device (spectrum manager) according to the fourth embodiment. FIG. 15 is a system configuration diagram for explaining a radio system according to the fifth embodiment of the present invention. FIG. 16 is a graph of interference power density for explaining the influence on adjacent frequencies in the wireless communication system according to the fifth embodiment.

  According to an embodiment of the present invention, in a frequency management device in a radio system (secondary system) that uses a frequency allocated to a primary system, an interference reachable range with a radio station that has transmitted a notification regarding a change in frequency usage status Are excluded from the calculation target of the allowable transmission power, and the allowable transmission power is calculated only for the wireless stations having the overlapping interference coverage. As a result, only the secondary transmitting station that is actually interfering with the range in which the transmission of the secondary transmitting station that changes the frequency usage influences interference (increase or decrease in interference) is subject to calculation of allowable transmission power. It can be. That is, unnecessary secondary transmission stations can be excluded from the calculation of the allowable transmission power, so that the processing amount can be reduced. In addition, out of the radio stations whose interference coverage overlaps with the radio station that has transmitted the notification regarding the change of the frequency usage status, only those whose interference coverage overlaps the service area of the primary system are subject to calculation of allowable transmission power. This can further reduce the amount of calculation.

  In the following description, a system in which the primary system is, for example, a TV broadcasting system and the secondary system is, for example, a cellular system is assumed as an example. The secondary transmitting station can be, for example, a base station, a relay station, or a terminal station in a cellular system. In this way, the frequency sharing mode in which the primary system is TV broadcast is called TV white space use. Of course, this configuration is merely an example, and the combination of the primary system and the secondary system is not limited to such a configuration. The combination of the primary system and the secondary system can be, for example, a combination of a TV system and a WRAN (Wireless Regional Access Network) system, or a combination of a TV system and a local radio such as a local government or a disaster prevention radio. In other examples, the primary system may be a wireless microphone or a special purpose radio (for example, an apartment radio, an in-house radio, an agricultural radio, etc.), and the secondary system is a wireless local area network (LAN). There may be. Further, the present invention is not necessarily limited to only a combination of wireless systems having different priorities when using frequencies, such as a primary system and a secondary system, and it is assumed that frequencies are shared in wireless systems having the same priority. It may be a configuration. Furthermore, in the present invention, a plurality of wireless systems may exist as secondary systems. The plurality of secondary transmission stations do not necessarily belong to the same radio system, and may be transmission stations belonging to different secondary systems. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1. 1. First Embodiment 1.1) System Configuration As shown in FIG. 2, the radio system according to the first embodiment of the present invention includes a secondary transmitting station 20 (20_1 to 20_4), a spectrum manager 50, and a radio environment database 30. It shall be. As will be described later, there may be a plurality of spectrum managers, but here, in order not to complicate the description, a case of a single spectrum manager is illustrated.

  The secondary transmitting station 20 communicates with a secondary receiving station (not shown) by sharing the frequency of the primary system. When the primary system is TV broadcast, a plurality of frequencies (TV channels) are candidates for sharing. Before starting frequency sharing, the secondary transmitting station 20 notifies the spectrum manager 50 of a start request, and receives information on available frequencies and allowable transmission power at those frequencies from the spectrum manager 50. The start request of the secondary transmitting station 20 can include other information (device ID, position, antenna height, antenna directivity) regarding the secondary transmitting station 20 and is registered in the spectrum manager 50 or the radio environment database 30. Is done.

1.2) Usable frequency and actual usable frequency The usable frequency refers to a frequency that the spectrum manager 50 permits the secondary transmitting station 20 to use. For example, when the secondary transmitting station 20 is outside the primary system service area 12 of a certain frequency, or when it is a predetermined distance away from the end of the primary system service area 12, the frequency is used by the secondary transmitting station 20 Possible frequency. The secondary transmitting station 20 is permitted to transmit at an available frequency if the actual transmission power is equal to or lower than the allowable transmission power determined by the spectrum manager. As will be described later, the usable frequency is determined by the spectrum manager 50 in addition to the condition that the secondary transmitting station 20 is outside the primary system service area 12 and uses the frequency of the primary system service area 12. A frequency that satisfies another condition can also be used.

  On the other hand, an actual use frequency to be described later refers to a frequency that the secondary transmission station actually uses for transmission. That is, the secondary transmitting station actually uses one (or a plurality of) frequencies among the available frequencies notified from the spectrum manager as the actual usable frequencies. After receiving the notification about the available frequency and its allowable transmission power, the secondary transmission station 20 determines the actual usage frequency and the actual transmission power, and starts communication. Further, when the secondary transmission station 20 stops using the frequency, the secondary transmission station 20 may notify the spectrum manager 50 to that effect.

1.3) Notification of Actual Utilization Frequency and Actual Transmission Power The actual utilization frequency and actual transmission power determined by the secondary transmission station 20 may or may not be notified to the spectrum manager 50. When the actual usage frequency and the actual transmission power are not notified, the spectrum manager 50 manages only the available frequency and the allowable transmission power without grasping the actual usage frequency and the actual transmission power of the secondary transmission station 20. Therefore, the secondary transmitting station 20 can freely change the actual usage frequency and the actual transmission power within the allowable range or within the allowable range, and can flexibly change the frequency usage. However, since the spectrum manager 50 does not have information on the actual usage frequency and the actual transmission power, it is difficult to grasp the interference state, and as a result, conservative frequency sharing is performed with the allowable transmission power suppressed to a low level. Hereinafter, in this embodiment, a case where the actual use frequency and the actual transmission power are not notified will be described, and the case where the notification is notified will be described later as a second embodiment.

1.4) Radio Environment Database Information stored in the radio environment database 30 is, for example, as follows.
Predetermined information about the primary system (for example, information on the position of the primary transmitting station 10, service area, transmission power, antenna height, antenna directivity, position of the primary receiving station 11, antenna height, antenna directivity, etc. Information about). Here, when the primary system is a TV broadcasting system, there are innumerable TV receiving stations and it is difficult to grasp all of them, so typical values are used for the height of the antenna and the antenna directivity. It is assumed that the TV receiving stations exist in a grid pattern (for example, a grid with an interval of 100 m) on the map. The spectrum manager according to the present embodiment controls the transmission power of the secondary transmission station so that the reception quality of the assumed TV reception station is maintained at a predetermined level. Hereinafter, it is assumed that the primary receiving station 11 represents this assumed TV receiving station, and the spectrum manager 50 calculates allowable transmission power for this assumed TV receiving station.

  Predetermined information related to the secondary system (for example, information related to the device ID, position, antenna height, antenna directivity, etc. of the secondary transmitting station 20). These pieces of information are registered via the spectrum manager 50 when the secondary transmitting station 20 accesses the spectrum manager 50 (when a request for starting use of a frequency is issued).

  -Path loss information between different radio stations. For example, the path loss between the secondary transmitting station 20 and the primary receiving station 11 or between the primary transmitting station 10 and the primary receiving station 11 is preliminarily determined using a predetermined propagation model using the distance between radio stations and the antenna height as parameters. Estimate and store.

  However, some of these pieces of information may be stored in an integrated form. The radio environment database 30 provides the stored information to the request source (for example, the spectrum manager 50) as necessary. Note that the radio environment database 30 may be a device in which some or all of the functions of the spectrum manager 50 are integrated. Conversely, some or all of the functions of the radio environment database 30 are integrated in the spectrum manager 50. May be.

1.5) Spectrum Manager The spectrum manager 50 has a function of calculating the allowable transmission power at each frequency to the secondary transmission station 20 and notifying the available frequency and the allowable transmission power. For example, the allowable transmission power is set to 0 [W] for the frequency that cannot be used, and the allowable transmission power is set to be higher than 0 [W] for the available frequency, and the secondary transmission station is notified of the allowable transmission power for all frequencies. Can communicate available frequencies.

  When the spectrum manager 50 according to the present embodiment manages a single or a plurality of secondary transmission stations 20 and receives a notification regarding a change in frequency usage from a managed secondary transmission station, the spectrum manager 50 refers to information on interference reachability described later. Then, the calculation target of the allowable transmission power is narrowed down, and the allowable transmission power is set for the secondary transmission station 20 that is the calculation target.

  Hereinafter, “notification regarding change in frequency usage status” refers to a request to start frequency usage, a notification to stop frequency usage, a request to change transmission power, a request to change frequency, or a measurement report of a radio environment. The spectrum manager 50 may be called a Geo-location Database or a White Space Database as another name integrated with the wireless environment database 30 or a part thereof. The wireless environment database 30 or a part thereof may be referred to as a Geo-location Database or a White Space Database.

  As shown in FIG. 3, the spectrum manager 50 includes a network communication unit 501, a frequency use reception unit 502, a database information storage unit 503, and an allowable transmission power determination unit 504. The network communication unit 501 has a function for each unit of the spectrum manager 50 to communicate with the secondary transmission station 20 and the wireless environment database 30.

  The frequency usage receiving unit 502 receives a notification regarding the change of the frequency usage status from the secondary transmission station 20 under the management of the spectrum manager 50 via the network communication unit 501. For example, when receiving a frequency use start request, the frequency use receiving unit 502 stores information (device ID, position, antenna height, antenna directivity, etc.) related to the secondary transmission station 20 included in the request information as database information. Registration is performed in the storage unit 503 and the wireless environment database 30. Subsequently, the frequency usage receiving unit 502 instructs the allowable transmission power setting unit 504 to calculate the allowable transmission power. Similarly, when receiving another notification (for example, notification of frequency use suspension), the frequency use accepting unit 502 instructs the allowable transmission power setting unit 504 to calculate the allowable transmission power.

  The database information storage unit 503 holds information acquired from the wireless environment database 30 and information acquired from the secondary transmission station 20. When each secondary transmitting station that is using the frequency does not notify the spectrum manager 50 of the actual used frequency, the spectrum manager 50 cannot grasp which frequency each secondary transmitting station 20 is using. The available frequency is stored in the database information storage unit 503.

  When the allowable transmission power setting unit 504 receives an instruction for calculating the allowable transmission power from the frequency usage receiving unit 502, the allowable transmission power setting unit 504 appropriately extracts information necessary for calculating the allowable transmission power from the database information storage unit 503 and calculates the information. Information necessary for the calculation includes the position of the primary transmitting station 10 described above, the service area, the transmission power, the height of the antenna, the information on the antenna directivity, the position of the primary receiving station 11, the height of the antenna, and the antenna directivity. , Allowable interference power, device ID of secondary transmission station 20, position, antenna height, antenna directivity, and part or all of path loss information between various radio stations, etc. May be stored in advance in the allowable transmission power setting unit 504.

  The allowable transmission power determination unit 504 receives a request for calculation of allowable transmission power from the frequency use reception unit 502. And the secondary transmission station 20 which issued the notification regarding the change of a frequency utilization condition (for example, which issued the request | requirement of frequency utilization start), and another secondary transmission which has already selected using the interference reach | attainment range mentioned later, and is already frequency sharing The allowable transmission power at each frequency is calculated only for the stations.

  Although not shown in FIG. 3, the spectrum manager 50 is provided with a control unit that controls the overall operation, and the network communication unit 501, the frequency use reception unit 502, the database information storage unit 503, and the permission described above. The operation of the transmission power determination unit 504 is controlled. The functions of the control unit, the frequency use accepting unit 502, and the allowable transmission power setting unit 504 can also be realized by executing a program stored in a memory (not shown) on a computer (CPU or program control processor). .

1.6) Frequency Management Operation In FIG. 4, the frequency usage reception unit 502 of the spectrum manager 50 notifies the frequency transmission status change (frequency) from the secondary transmission station 20 under the management of the spectrum manager 50 through the network communication unit 501. A use start request or a use stop notification is received (step S10).

  Subsequently, the frequency usage receiving unit 502 acquires information necessary for calculating the allowable transmission power from the database information storage unit 503 (step S11). As described above, the information necessary for this calculation includes the position of the primary transmitting station 10, the service area, the transmission power, the height of the antenna, the information on the antenna directivity, the position of the primary receiving station 11, and the height of the antenna. , Antenna directivity, allowable interference power, device ID of the secondary transmission station 20, position, antenna height, antenna directivity, and path loss between various radio stations. If all necessary information is not stored in the database information storage unit 503 (NO in step S12), the frequency use receiving unit 502 accesses the wireless environment database 30 through the network communication unit 501, and only the missing information is stored. Is acquired from the wireless environment database 30 (step S13).

  When all necessary information is stored in the database information storage unit 503 (YES in step S12) or when missing information is acquired (step S13), the allowable transmission power determination unit 504 A secondary transmission station 20 that has received a request for calculation of allowable transmission power from the use reception unit 502 and has issued a notification regarding a change in frequency usage status, and another secondary transmission station that overlaps with the secondary transmission station 20 and an interference arrival area. The calculation target is set (step S14). When the secondary transmission station to be calculated is determined in this way, the allowable transmission power determination unit 504 calculates the allowable transmission power for the calculation target secondary transmission station for each frequency by the calculation method described below, and calculates the calculated allowable transmission power. The transmission power is notified to each secondary transmission station (step S15).

1.7) Calculation of Allowable Transmission Power Next, a method of calculating the allowable transmission power will be described. Here, the index of the secondary transmission station that is already using the frequency under the management of the spectrum manager 50 is set to n = 1 to N. It shall be expressed as

  First, the allowable transmission power determination unit 504 specifies the usable frequency of the secondary transmission station 20 (represented by index n = 0) that has notified the start request. The available frequency is a frequency of the primary system service area 12 when the secondary transmission station 20 is outside the primary system service area 12 or when it is a predetermined distance away from the end thereof. By checking this condition for all frequencies (for example, all channels of TV), all available frequencies can be specified.

In the present embodiment, the usable frequency of each secondary transmission station 20 is stored in the database information storage unit 503. That is, if the frequency of the primary system is f _i (the frequency index is i = 1 to I), the set of usable frequencies {f _{i (n, k)} } (frequency index of the n-th secondary transmitting station ₎ I (n, k), where k is an index in the set) is registered in the database information storage unit 503. For example, if the usable frequency of the n-th secondary transmission station is {f ₁ , f ₃ , f ₆ }, i (n, 1) = 1, i (n, 2) = 3, i (n, 3) = 6.

Hereinafter, one of the available frequency of the secondary transmission station 20 and the frequency f _i, be described how to calculate the allowable transmission power of the frequency f _i. However, it is assumed that the other secondary transmitting station only when the frequency f _i is available frequency, in use the frequency f _i. In this case, the allowable transmission power can be determined in consideration of the case where the total interference is maximized by using the same frequency for each secondary transmission station.

  First, after describing a method for determining a secondary transmission station that is a target of calculation of allowable transmission power, which is a feature of the embodiment of the present invention, a specific calculation method of allowable transmission power will be described.

<Limitation of calculation target>
In the present embodiment, an interference reachable range is used in order to limit secondary transmission stations that are targets of calculation of allowable transmission power. In particular, the set S 干 渉 {1, 2,..., N} of secondary transmission stations to be calculated is obtained by using an interference arrival area that is a geographical interference reachable range. However, the secondary transmitting station 20 with n = 0 is excluded from S because it is a transmitting station that has notified the start request and is necessarily a calculation target.

The interference arrival area refers to an area where interference substantially reaches geographically when the secondary transmission station transmits at the maximum transmission power. Here, the “maximum transmission power” means the upper limit value of the transmission power due to the hardware limit of the secondary transmission station, or the upper limit value of the transmission power range permitted by the frequency rule when the frequency is shared (the maximum allowable transmission power). Value) and the like. Further, in the secondary transmitting station that already uses the frequency, the spectrum manager 50 knows the allowable transmission power, so the “maximum transmission power” may be set as the allowable transmission power, and the spectrum manager 50 manages the actual transmission power. In this case, the “maximum transmission power” may be the actual transmission power. Therefore, the interference reachable area refers to an area that depends on the maximum transmission power and the path loss from the secondary transmission station to the surroundings and is estimated to be equal to or greater than a threshold _ITh that is considered to be a sufficiently small value of the interference power. Also, the interference reaching area may be simply within a predetermined distance. Hereinafter, the configuration of the wireless system shown in FIG. 5 will be considered in order to more specifically describe the method for limiting the secondary transmission stations to be calculated.

In the radio system illustrated in FIG. 5, primary receiving stations 11_1 to 11_3 exist in the primary service area 12 of the primary transmitting station 10, secondary transmitting stations 20_0 to 20_4 exist in the vicinity of the primary service area 12, and the secondary transmitting station Assume that 20_0 to 20_4 have interference arrival areas IA20_0 to IA20_4, respectively. However, since the primary receiving station 11 is assumed to exist in a grid pattern in the primary system service area 12, there are actually other stations, but here, for convenience of explanation, adjacent secondary stations 11 exist. Only the primary receiving stations 11_1 to 11_3 that overlap with the interference arrival area of the transmitting station are illustrated. Hereinafter, it is assumed that the secondary transmission stations 20_1 to 20_4 are already using the frequency, and a method for calculating the allowable transmission power when the secondary transmission station 20_0 newly starts using the frequency will be described. However, the frequency f _i to calculate the allowable transmission power in this example is assumed to be the available frequency taking the secondary transmission station 20_1～20_4.

  First, assuming that the secondary transmission station 20_0 starts transmission with the maximum transmission power, interference increases in the interference arrival area IA20_0 of the secondary transmission station 20_0. Therefore, there is a possibility that the total interference amount may increase due to the transmission of the secondary transmission station 20_0 in the interference arrival areas IA20_1, IA20_2, and IA20_3 that overlap with the interference arrival area IA20_0, and the secondary transmission stations 20_1, 20_2, and 20_3. It may affect the allowable transmission power. Therefore, by excluding the secondary transmission station 20_4 whose interference arrival areas do not overlap from the calculation target, the set S of the indexes n of the secondary transmission stations to be calculated becomes S = {1, 2, 3}.

  Furthermore, the number of secondary transmission stations to be calculated can be further reduced by considering the overlap between the primary system service area 12 and the interference arrival area. Considering the common area of the interference transmission area IA20_0 of the secondary transmitting station and the primary system service area 12, interference with the primary receiving stations 11_1 to 11_3 increases in the primary system service area 12. Further, the primary receiving station 11_1 is further within the interference arrival area IA20_1, and the primary receiving station 11_3 is within the interference arrival area IA20_3. Therefore, it is the interference arrival areas IA20_1 and IA20_3 that the total amount of interference from the plurality of secondary transmission stations to the primary reception station due to the transmission by the secondary transmission station 20_0 is allowed, and these secondary transmission stations are allowed. The transmission power is calculated.

  On the other hand, there is no primary receiving station in the interference coverage area overlapping range between the secondary transmitting station 20_2 and the secondary transmitting station 20_0. Therefore, the influence of interference with the secondary transmission station 20_2 does not have to be considered in calculating the allowable transmission power, and the set S of the indexes n of the secondary transmission stations to be calculated is S = {1, 3}.

<Calculate allowable transmission power>
The allowable transmission power is calculated by the following method for the secondary transmission station set S that is the calculation target of the allowable transmission power obtained as described above.

The allowable transmission power in the n-th secondary transmitting station using the frequency f _i P (n, f _i) and to, permitted transmission power P when the zeroth secondary transmission station that reports the start request to use the frequency f _i (0, f _i ). At this time, the interference I (f _i , m) to the m-th primary receiving station is given by the following equation (2), and this value needs to be equal to or less than the allowable interference power I _max (f _i , m).

In the formula (2), if the frequency f _i is not available frequency for the n-th secondary transmitting station, handled as P (n, f i) = _{0 (i.e.,} not consider interference from the n-th secondary transmitting station) . The interference between adjacent frequencies will be described later. Moreover, L (n, f i, _m) represents the path loss between the first n secondary transmitting station and the m primary receiving station when using the frequency f _i, of the secondary transmission station information (position, It is calculated according to a propagation model such as a formula using the antenna height and the information (position, antenna height, etc.) of the primary receiving station. This path loss calculation can be calculated by the allowable transmission power determination unit 504, or can be calculated by the wireless environment database 30 when the secondary transmission station information is registered in the wireless environment database 30.

  Further, m in the expression (2) is m = 1, 2, 3 in order to suppress interference with the primary receiving stations 11_1 to 11_3 in the overlapping area of the secondary transmitting station 20_0 and the primary system service area 12. Consider. That is, combinations of allowable transmission powers of secondary transmission stations 20_0, 20_1, and 20_3 that satisfy the inequality of Expression (2) in all of m = 1, 2, and 3 are obtained. Here, the secondary transmission stations 20_1 and 20_3 that have already used the frequency newly set a smaller one of the allowable transmission power obtained as a combination and the previous allowable transmission power as the new allowable transmission power. By selecting the smaller allowable transmission power, primary receiving stations other than the primary receiving stations 11_1 to 11_3 (the overlapping area of the interference reaching area IA20_1 and the primary system service area 12, or the overlapping of the interference reaching area IA20_3 and the primary system service area 12) A primary receiving station (not shown) existing in the area can also be protected from interference.

To perform frequency sharing protecting the primary system, all the primary receiving station using a frequency f _i for (1 ≦ m ≦ M), must satisfy the formula (2). Acceptable combination of satisfying P (n, f _i) is usually present in numerous, for example, a combination that the total communication capacity of the secondary transmission station is maximized, considering the fairness among the secondary transmission station A combination can be determined by an arbitrary policy of the allowable transmission power setting unit 504, such as a combination of transmission powers. If the number of secondary transmission stations to be calculated (the number of elements of S) can be reduced in Equation (2), the amount of calculation for searching for a combination of allowable transmission powers can also be reduced.

The search for the allowable transmission power is performed at the frequencies f _{1 to} f _I , and the allowable transmission power combination of each secondary transmission station is obtained for each frequency. The permissible transmission power determination unit 504 uses the information on the permissible transmission power of each frequency calculated in this way under the control of the secondary transmitting station 20 that has issued a frequency use start request and the spectrum manager 50 and is already using another secondary frequency. Notify the transmitting station.

  Note that the spectrum manager 50 is not necessarily required to notify the secondary transmission station 20 of all available frequencies. That is, some frequencies can be selected from the available frequencies and notified to the secondary transmitting station 20, and the remaining frequencies can be notified by setting them as unusable frequencies (frequency where the allowable transmission power is 0). . For example, a frequency that has an allowable transmission power equal to or higher than a certain threshold can be set as an available frequency. Alternatively, it is possible to set some frequencies from the higher allowable transmission power as usable frequencies, and select some frequencies from the smaller number set as the usable frequencies by other secondary transmission stations. It is also possible to set as an available frequency. In this way, by limiting the frequencies to be notified as available frequencies in advance, the number of frequencies set as available frequencies can be reduced compared to the case of notifying all available frequencies, and the influence of unnecessary interference can be reduced. It can be omitted when calculating the equation (2). As a result, a larger allowable transmission power can be allocated to the secondary transmission station that newly starts using the frequency.

1.8) System Operation Sequence Next, with reference to FIGS. 6 and 7 sequentially, the secondary transmission station 20_0 issues a frequency usage status change notification, and the secondary transmission stations 20_1 to 20_4 managed by the spectrum manager 50. The operation of the entire wireless system will be described by exemplifying the case where the same frequency is being used.

<Start using frequency>
In FIG. 6, when the secondary transmitting station 20_0 notifies the spectrum manager 50 of a notification (frequency use start request) regarding the change of the frequency usage status (operation S101), the spectrum manager 50 reads from the radio environment database 30 as necessary. Shortage information is acquired and information is registered (operation S102). When all necessary information is prepared, the spectrum manager 50 limits the secondary transmission stations to be calculated, and calculates the allowable transmission power of each frequency related to the limited secondary transmission stations (operation S103). Here, secondary transmission stations 20_1 and 20_3 whose secondary transmission stations overlap with the secondary transmission station 20_0 are selected as secondary transmission stations for which the allowable transmission power is calculated, and the allowable transmission power of these secondary transmission stations is calculated. Shall. Thus, the spectrum manager 50 notifies the secondary transmission station 20_0 and the secondary transmission stations 20_1 and 20_3 of the calculation result of the allowable transmission power (operation S104).

  The secondary transmitting station 20_0 determines the actual usage frequency and the actual transmission power using the available frequency notified from the spectrum manager 50_1 and its allowable transmission power (operation S105), and starts communication sharing the frequency. Further, the secondary transmitting stations 20_1 and 20_3 change the actual use frequency and the actual transmission power if necessary to change the notified allowable transmission power (operations S106 and S107), and continue the communication using the frequency sharing.

<Frequency stop>
In FIG. 7, when the secondary transmitting station 20_0 notifies the spectrum manager 50 of the stop of frequency usage (operation S110), the spectrum manager 50 registers that the secondary transmitting station 20_0 has stopped in the wireless environment database 30, and others. Information necessary for calculating the allowable transmission power of the secondary transmission station is acquired from the wireless environment database 30 (operation S111).

Here, the secondary transmission station that is the target of calculation of the allowable transmission power is a secondary transmission station that has overlapped interference coverage areas when the secondary transmission station 20_0 originally transmitted, and here, the secondary transmission stations 20_1 and 20_3. Is chosen. The calculation of the allowable transmission power is performed by using the expression except the term relating to the secondary transmission station 20_0 in the expression (2) (if the index of the secondary transmission station 20_0 is n = 0, the expression P (0, f _i ) / L (corresponding to excluding 0, f _i , m)), the allowable transmission power of the secondary transmission stations 20_1 and 20_3 is calculated (operation S112) and notified (operation S113). Each of the secondary transmitting stations 20_1 and 20_3 holds the notified value of the allowable transmission power, and changes the actual use frequency and the actual transmission power in accordance with the change of the allowable transmission power. Operation S114, S115), communication by frequency sharing is continued.

1.9) When the actual usage frequency and the actual transmission power are notified The case where the actual usage frequency and the actual transmission power are not notified to the spectrum manager has been described above, but the actual usage frequency and the actual transmission power are notified to the spectrum manager. As a result, it is possible to grasp the actual frequency usage status (actual usage frequency and actual transmission power), and more actively share the frequency.

  The actual usage frequency and the actual transmission power are notified when the secondary transmitting station 20 starts frequency sharing, requests a change in the actual transmission power during frequency sharing, or requests a change in the actual usage frequency. It is time to do. In this case, since the spectrum manager 50 grasps the actual use frequency and the actual transmission power of each secondary transmission station 20, it becomes easier to grasp the interference state given by the secondary transmission station 20, and more actively frequency sharing is performed. Can do.

  In FIG. 8, the start request (operation S121) by the secondary transmitting station 20_0, acquisition of necessary information from the wireless environment database 30 and registration of information (operation S122) are the same as operations S101 and S102 in FIG.

  Subsequently, the spectrum manager 50 calculates the allowable transmission power of the secondary transmission station 20_0 and the secondary transmission station to be calculated (operation S123). In this example, since it is assumed that all secondary transmission stations notify the actual use frequency and the actual transmission power, the actual use frequency and the actual transmission power of the secondary transmission station 20 that already uses the frequency of the primary system. Is stored in the wireless environment database 30 or the database information storage unit 503. Therefore, on the premise that each secondary transmitting station (20_1 to 20_4) already using the frequency uses the stored actual use frequency, the spectrum manager 50 uses the frequency for calculating the allowable transmission power as the actual use frequency. The allowable transmission power of the secondary transmission station that is the transmission station and overlaps the interference transmission area with the secondary transmission station 20_0 is determined. Here, it is assumed that secondary transmission stations 20_1 and 20_3 are selected.

The calculation method of the allowable transmission power is basically the same as that of the first embodiment in which the actual use frequency and the actual transmission power are not notified. However, for the n-th secondary transmitting station that is using the frequency, P (n, f _i ) = 0 is set in Equation (2) when the frequency f _i is not an available frequency. The difference is that (n, f _i ) = 0.

Further, allowable transmission power, provided the conditions for no more than the transmission power desired value to be described later _{(P Desired) (P (n} , f i) ≦ P Desired). However, this condition is not set for secondary transmission stations for which the desired value of transmission power is not set. Permitted transmission power satisfies the condition P (n, f _i) of the condition and the equation (2) relating to the desired value of the transmission power is searched as a combination of. By setting the conditions related to the desired value of transmission power, the secondary transmission station is prevented from allocating excess allowable transmission power exceeding the desired transmission power, and the allowable transmission power of other secondary transmission stations is increased accordingly. .

  Usually, there are innumerable combinations of allowable transmission power, but for example, the combination that maximizes the total communication capacity of secondary transmission stations, the combination of allowable transmission power considering fairness between secondary transmission stations, and the current actual transmission power The combination can be determined by an arbitrary policy of the allowable transmission power setting unit 504, such as a combination of allowable transmission powers with a smaller amount of deterioration compared to.

The desired transmission power value (P _Desired ) described above can be set as follows. When the spectrum manager 50 receives the actual use frequency and the actual transmission power determined by the secondary transmission station 20_0, the spectrum manager 50 compares the transmission power desired by the secondary transmission station 20_0 with the allowable transmission power. When the desired transmission power is lower than the allowable transmission power, the actual transmission power is set to a value lower than the allowable transmission power. At this time, the spectrum manager 50 holds the notified actual transmission power as a desired value of the transmission power of the secondary transmission station 20_0. On the other hand, when the desired transmission power of the secondary transmission station 20_0 is larger than the allowable transmission power, the actual transmission power is set to a value equal to the allowable transmission power. At this time, the secondary transmission station 20_0 does not set a desired value of transmission power. As another method, when the secondary transmission station 20_0 notifies the actual transmission power and the actual usage frequency, the desired value of the transmission power of the secondary transmission station 20_0 may also be notified to the spectrum manager.

  Next, the calculated allowable transmission power of each frequency of the secondary transmission station 20_0 is notified to the secondary transmission station 20_0 (operation S124). The secondary transmission station 20_0 determines the actual use frequency and the actual transmission power based on the allowable transmission power for each frequency (operation S125). The secondary transmitting station 20_0 notifies the spectrum manager 50 of the determined actual use frequency and actual transmission power (operation 126). Upon receiving the notification of the actual usage frequency and the actual transmission power, the spectrum manager 50 registers the notified actual usage frequency and the actual transmission power in the wireless environment database 30 (operation S127).

  Subsequently, the spectrum manager 50 compares the actual transmission power notified from the secondary transmission station 20_0 with the allowable transmission power at the actual use frequency, and allows the other secondary transmission stations (20_1 and 20_3) to be calculated. It is determined whether or not to recalculate the transmission power (operation 128). As a result of the comparison, if the two match, the actual transmission frequency notified from the secondary transmitting station 20_0 is used from the already calculated combinations of allowable transmission powers without recalculating the allowable transmission power. A combination of cases is selected, and this allowable transmission power information is notified to the other secondary transmission stations (20_1 and 20_3) (operation 129).

  On the other hand, the actual transmission power is smaller than the allowable transmission power, and the allowable transmission power calculated in the other secondary transmission stations (20_1 and 20_3) is less than the desired value of the transmission power or When there is a transmitting station in which the desired transmission power value is not set, the allowable transmission power is recalculated.

  The reason for recalculating the allowable transmission power is that when the secondary transmission station 20_0 uses an actual transmission power lower than the allowable transmission power, there is a margin for the limitation of the allowable interference power. This is because it can be assigned to other secondary transmitting stations that do not satisfy the desired value. In the recalculation of the permissible transmission power, the desired transmission power of the secondary transmission station 20_0 and the secondary transmission station having the permissible transmission power equal to the desired transmission power is fixed as the permissible transmission power, and the permissible transmission power is equal to the transmission power. The allowable transmission power of the secondary transmission station that does not satisfy the desired value is calculated again. The spectrum manager 50 notifies the calculated allowable transmission power information to the other secondary transmission stations (20_1 and 20_3) (operation 129).

  Subsequently, the spectrum manager 50 returns a confirmation notification for the notification of the actual usage frequency and the actual transmission power to the secondary transmission station 20_0 (operation S130), whereby the secondary transmission station 20_0 starts transmission. In addition, each secondary transmitting station (20_1 and 20_3) already using the frequency holds the notified allowable transmission power value as a new set value, and the actual usage frequency and the actual transmission power according to the change of the allowable transmission power. If it is necessary to change these, these are changed and transmission is continued (operations S131 and S132).

  As described above, the actual usable frequency and the actual transmission power are notified to the spectrum manager, and the allowable transmission power of the secondary transmitting station is determined using these information, so that the usable frequency can be used without performing the notification. Compared to the case where the allowable transmission power is determined, interference estimation based on a more accurate usage situation is possible. Specifically, when assuming the interference power of Equation (2), only secondary transmission stations that actually use each frequency can be considered, and there is a possibility that the frequency may be used (available frequency). However, secondary transmission stations that are not actually used can be excluded. As a result, it is not necessary to consider interference that does not actually exist, so that it is possible to allocate a larger allowable transmission power to the secondary transmission station and to share the same frequency with more secondary transmission stations.

  In addition, when calculating the allowable transmission power, the allowable transmission power of the secondary transmission station to which a small allowable transmission power is allocated can be increased by setting the allowable transmission power so as not to exceed the desired value of the transmission power of the secondary transmission station. Can be made.

  Furthermore, when the actual transmission power notified from the secondary transmission station is smaller than the allowable transmission power and the allowable transmission power of the other secondary transmission stations is less than the desired value, by recalculating the allowable transmission power, The allowable transmission power can be increased by allocating the interference margin generated for the limitation of the allowable interference power to other secondary transmission stations whose allowable transmission power does not satisfy the desired value.

  In addition, although the secondary transmission station demonstrated the example which notifies an actual utilization frequency and real transmission power with respect to a spectrum manager, it is not limited to this. For example, the secondary transmission station may notify the spectrum manager of a plurality of frequencies including the actual utilization frequency among the usable frequencies as frequencies that can be used.

  The secondary transmission station can also notify the spectrum manager of transmission power that is larger than the actual transmission power and smaller than the allowable transmission power. In this case, the secondary transmission station changes the actual use frequency and the actual transmission power within the notified frequency and transmission power range, and the spectrum manager changes the interference power of Expression (2) among the notified frequency and transmission power. Suppose. As a result, the secondary transmitting station can secure the flexibility of changing the actual use frequency and the actual transmission power within the notified frequency and transmission power range, and the spectrum manager can provide the frequency and transmission power with high possibility. The interference power can be estimated by limiting to the above.

  Here, the frequency use start request is assumed as the “notification regarding the change of the frequency use state”, but the same applies to the frequency use stop notification as described above. As other “notifications regarding changes in frequency usage status”, a request for changing transmission power and a request for changing frequency may be considered. The request for transmission power change is notified to the spectrum manager when it is desired to change the actual transmission power once determined by the secondary transmission station. For example, it corresponds to a case where the secondary transmission station increases transmission power for coverage expansion or a case where the secondary transmission station decreases transmission power for power saving.

  Similarly, the frequency change request is notified to the spectrum manager when it is desired to change the actual use frequency once determined by the secondary transmitting station. For example, it corresponds to a case where interference from another secondary system to the secondary system is increased at the actual use frequency of the secondary transmission station.

  Regardless of whether the request for a change in frequency usage is a request for a change in transmission power or a request for a change in frequency, the spectrum manager and the secondary transmitting station that issued the notification It is the same in that the allowable transmission power at each frequency is calculated for each of the other secondary transmission stations already using the frequency where the interference arrival areas overlap.

1.10) Effect According to the first embodiment described above, the spectrum manager uses the interference arrival area, which is the geographical interference reachable range of each secondary transmission station, to change the frequency usage situation. The other secondary transmission stations whose interference arrival areas do not overlap with each other are excluded from the calculation target of the allowable transmission power, and the allowable transmission power is calculated only for the secondary transmission stations whose interference arrival ranges overlap. As a result, for the range in which interference by the secondary transmitting station that changes the frequency usage status affects (that is, the interference increases or decreases), only the other secondary transmitting stations that are substantially interfering are allowed to have the allowable transmission power. Can be calculated. That is, unnecessary secondary transmission stations can be excluded from the calculation of the allowable transmission power, so that the processing amount can be reduced.

  Furthermore, if the overlapping interference coverage area between the secondary transmitting station that changes the frequency usage status and the other secondary transmitting station does not overlap with the primary system service area, the other secondary transmitting station calculates the allowable transmission power. Can be excluded from the target. As a result, only the other secondary transmission stations whose total interference value affects the interference with the primary reception station can be set as the calculation target of the allowable transmission power.

  In the first embodiment, as a reference for maintaining a predetermined reception quality at the primary receiving station, a reference for suppressing the interference power to be equal to or lower than the allowable interference power is used. However, the present invention can be applied in the same manner even when other criteria (keeping CIR and CINR above a predetermined value) are used. Also, the allowable transmission power can be set so that the degree of deterioration of the CIR or CINR of the primary receiving station caused by transmission at the secondary transmitting station is suppressed to a predetermined value or less.

  In the above description of the first embodiment, the system configuration shown in FIG. 2 is assumed. However, the present invention is not limited to this, and can be applied to the system configuration of the following embodiment.

2. Second Embodiment According to the second embodiment of the present invention, the spectrum manager as the frequency management device of the secondary system, like the spectrum manager 50 of the first embodiment, selects the secondary transmission station that is the target of calculation of allowable transmission power. In addition to the limiting function, it is possible to notify the calculated value of the allowable transmission power not only to the secondary transmission station under its own management but also to the secondary transmission stations managed by other spectrum managers of the same secondary system. Hereinafter, in order to simplify the description, a case where two spectrum managers in the secondary system have two secondary transmission stations under their management will be described as an example.

  As shown in FIG. 9, the radio system according to the second embodiment of the present invention includes a secondary transmitting station 20 (20_1 to 20_4), a spectrum manager 51 (51_1, 51_2), and a radio environment database 30. It is assumed that communication is established with a secondary transmission station managed by another spectrum manager. The spectrum manager 51_1 manages the secondary transmission stations 20_1 and 20_2, and the spectrum manager 51_2 manages the secondary transmission stations 20_3 and 20_4. Each spectrum manager receives a notification regarding a change in the frequency usage status from a managed secondary transmission station. And each spectrum manager overlaps the interference transmission area with the secondary transmission station which received the notification regarding the change of the frequency utilization status among the secondary transmission stations under management and the secondary transmission stations under the management of other spectrum managers. Secondary transmission stations are limited, and allowable transmission power is calculated and notified to them.

  As shown in FIG. 10, the spectrum manager 51 can manage the secondary transmitting station 20 for each geographical area. Here, the secondary transmission stations 20_1 and 20_2 are included in the management area A51_1 of the spectrum manager 51_1, and these secondary transmission stations are managed by the spectrum manager 51_1. Similarly, the other spectrum managers (51_2, 51_3, 51_4) also have a management area (A51_2, A51_3, A51_4) and secondary transmission stations to be managed (20_3 and 20_4, 20_5 and 20_6, 20_7 and 20_8) included in each area. ) Each. For example, each management area A51 corresponds to a prefecture unit or a country unit.

  As another management method, the spectrum manager to be managed can be determined uniquely for the secondary transmitting station. For example, when the spectrum manager managed by the manufacturer of the secondary transmitting station is defined, when the spectrum manager managed according to the provider providing the wireless service to the secondary transmitting station is defined, the radio system (LTE of the secondary transmitting station) , WiMAX, etc.), a spectrum manager to be managed may be determined. Furthermore, as another example, the spectrum manager may manage each frequency used by the secondary transmission station, which will be described in another embodiment.

3. Third Embodiment As shown in FIG. 11, the radio system according to the third embodiment of the present invention includes a secondary transmission station 20 (20_1 to 20_4), a spectrum manager 52 (52_1, 52_2), and a radio environment database 30. Each spectrum manager is communicably connected to a secondary transmission station under its own management, and spectrum managers 52_1 and 52_2 are communicably connected. Similar to the case of the second embodiment, the spectrum managers 52_1 and 52_2, in addition to the function of limiting the calculation target of the allowable transmission power, not only the secondary transmission station under its own management but also other spectrums of the same secondary system The allowable transmission power calculation value can be notified to the secondary transmission station managed by the manager via the other spectrum manager.

  In the system configuration shown in FIG. 11, when a certain spectrum manager 52 (for example, 52_1) calculates the allowable transmission power of another secondary transmission station 20 (for example, 20_3, 20_4) that is not managed by itself, the other secondary transmission station. 20 is notified of the allowable transmission power that is the calculation result to another spectrum manager 52 (for example, 52_2) whose management target is 20, and the other spectrum manager 52 transmits the allowable transmission power that is the calculation result to the secondary under the management. Notify the transmitting station (for example, 20_3, 20_4). Since the configuration and operation of the secondary transmission station 20 and the radio environment database 30 are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted. The spectrum manager 52 according to the present embodiment is basically the same as the spectrum manager 51 according to the second embodiment. However, when the allowable transmission power that is the calculation result is received from another spectrum manager, the secondary transmission station under its own management. The point of transferring to is different. Hereinafter, the configuration and operation of the spectrum manager 52 will be described using the spectrum manager 52_1 as an example.

  As shown in FIG. 12, the spectrum manager 52_1 is basically the same as the spectrum manager 50 of the first embodiment shown in FIG. 3, except that the network communication unit 521 has an interface to the other spectrum manager 52_2. Different. Further, as another different point, when the allowable transmission power related to the secondary transmission station under the management of the spectrum manager 52_1 calculated by the other spectrum manager 52_2 is received, this information is stored in the database information storage unit 523, and then the own device management is performed. The lower secondary transmission station 20 (20_1 or 20_2) is notified of the allowable transmission power. With this configuration, the spectrum manager 52_1 can grasp information on the managed secondary transmission stations 20_1 and 20_2. The configuration and operation of the spectrum manager 52_2 are the same.

4). Fourth Embodiment As shown in FIG. 13, the radio system according to the fourth embodiment of the present invention includes a secondary transmission station 20 (20_1 to 20_4) and a spectrum manager 53 (53_1, 53_2). The difference is that the radio environment database 30 is not provided outside the spectrum manager 53.

  FIG. 14 shows the configuration of the spectrum manager 53 in the system configuration of FIG. 13, but here, the configuration of the spectrum manager 53_1 is exemplified. As shown in FIG. 14, the spectrum manager 53_1 has a radio environment database 533 therein. That is, each of the plurality of spectrum managers 53 has a radio environment database 533. Therefore, each spectrum manager 53 has a function of synchronizing information stored in each wireless environment database 533 by communicating with each other through the network communication unit 531.

  By synchronizing the information stored in the wireless environment database 533 as described above, even if the system configuration does not include the wireless environment database 30, the system can be operated in the same manner as in the first to third embodiments described above. Can do.

5. Fifth Embodiment According to the fifth embodiment of the present invention, the spectrum manager manages secondary transmission stations for each frequency. Further, the allowable transmission power is calculated in consideration of the interference arrival frequency that is the interference arrival range in the frequency direction of the secondary transmission station. For the sake of clarity, only differences from the second embodiment will be described.

  In the present embodiment, the spectrum manager manages notifications regarding changes in the frequency usage status of secondary transmission stations (frequency usage start request, frequency usage stop, etc.) for each frequency. That is, for the spectrum manager, the secondary transmitting station that performs notification regarding the change of the frequency usage status at the management target frequency corresponds to the managed secondary transmitting station in the fifth embodiment. Hereinafter, an example in which the secondary transmission station transmits at frequencies f1 to f8 and is managed by the spectrum manager for each transmission frequency will be described.

  As shown in FIG. 15, the management targets of the spectrum manager 60_1 are the center frequencies f1 and f2, the management targets of the spectrum manager 60_2 are the center frequencies f3 and f4, the management targets of the spectrum manager 60_3 are the center frequencies f5 and f6, and the spectrum manager 60_4. The management objects are center frequencies f7 and f8. As shown in FIG. 15, the system configuration of the present embodiment has an interface for each spectrum manager 60 in which each secondary transmitting station manages different frequencies. With this configuration, each secondary transmission station can notify any spectrum manager 60 of a request to start using the frequency.

  In the present embodiment, it is assumed that the secondary signal also interferes with the primary receiving station that uses the adjacent frequency. FIG. 16 shows a state in which the secondary signals having the frequencies f3 and f7 as the center frequencies interfere with the adjacent frequencies. Interference with the primary reception station using the adjacent frequency is determined by the adjacent channel leakage power ratio leaking from the transmission frequency of the secondary transmission station to the adjacent frequency and the reception filter of the primary reception station centering on the adjacent frequency. Adjacent channel selectivity that partially captures signals in the frequency band occurs in combination.

  Here, since the adjacent frequencies interfere with each other, the secondary transmission station 20 that is the target of calculation of the allowable transmission power is limited by setting the management target of the spectrum manager 60 as a continuous frequency as in this embodiment. Can be limited to secondary transmission stations under the management of the spectrum manager. For example, depending on the frequency, adjacent frequencies for a plurality of channels on both sides may be managed by the same spectrum manager 60. In this case, a plurality of secondary transmission stations to be calculated can be managed by the same spectrum manager, and related information is aggregated in the same spectrum manager, thereby reducing the number of accesses to the radio environment database 30 for obtaining necessary information. Efficiency can be achieved.

  Next, a method for calculating the allowable transmission power using the interference arrival frequency when considering interference between adjacent frequencies will be described. In the present embodiment, the spectrum manager 60 that manages a predetermined frequency receives a notification issued from the secondary transmitting station 20 regarding the change in the frequency usage status for the frequency, and the interference reaching frequency and interference of the secondary transmitting station 20 Secondary transmission stations with overlapping arrival frequencies are limited as calculation targets, allowable transmission power is calculated, and each secondary transmission station is notified.

First, interference to adjacent frequencies is present even for remote frequencies. Therefore, when the secondary transmission station uses the maximum transmission power, a frequency range in which interference equal to or greater than a threshold value of interference power that is considered to be sufficiently small is estimated as an interference arrival range (interference arrival frequency) on the frequency axis. It is defined as Interference arrival frequency, if it is expressed as k channels of adjacent frequency (relative to the frequency f _i to f _{i-k ~f} i + _k), in the example shown in FIG. 16, consider the adjacent frequency interference one channel Therefore, k = 1.

Considering the allowable transmission power P when the zeroth secondary transmission station that reports the start request to use the frequency _{f i (0, f i)} . When interference with adjacent frequencies is considered, as shown in the following equation (3), the interference I (f _j , m) to the m-th primary receiving station using the frequency f _j is the allowable interference power I _max ( f _j , m) or less.

Here, α (f _j −f _i ) is a coefficient representing the degree of interference according to the frequency difference f _j −f _i , and is determined according to the above-mentioned adjacent channel leakage power ratio and adjacent channel selectivity. . When the frequency difference is 0, α (0) = 1, and as the frequency difference f _j −f _i increases, α (f _j −f _i ) decreases and becomes 0 when the frequency difference exceeds f _j −f _{j + k.} . Further, the expression (3) indicates that the frequency f _{i ′} is not an available frequency (or an actual used frequency when the actual used frequency is notified to the spectrum manager) for the n-th secondary transmitting station. , F _{i ′} ) = 0 (that is, the interference by the n-th secondary transmitting station is not considered). In order to protect the primary system, for all primary receiving stations (1 ≦ m ≦ M) that use the interference arrival frequencies f _{i−k to} f _{i + k} that affect the transmission of the frequency f _i of the 0th secondary transmitting station. It is necessary to satisfy the condition of equation (3). That is, since it is necessary to satisfy Expression (3) for I (f _i−k , m) to I (f _{i + k} , m), the secondary transmission station (interference arrival) that uses f _{i−2k to} f _{i + 2k} as a result. The secondary transmission stations having overlapping frequencies) are affected, and are subject to calculation of allowable transmission power. This condition is satisfied P (n, f _i) by searching for a combination of, can determine the allowable transmission power.

As the allowable transmission power of the n-th secondary transmission station (1 ≦ n ≦ N) that already uses the frequency, the allowable transmission power obtained as a combination and the allowable transmission power that has been used so far The smaller one is newly set as the allowable transmission power. By selecting the smaller allowable transmission power, the interference of the n-th secondary transmission station selected as the calculation target is affected, but the primary reception station (frequency f _i−2k ˜ (Primary receiving station using f _i−k−1 or f _{i + k + 1 to} f _{i + 2k} ) can be protected from interference.

  As described above, according to the fifth embodiment, only the secondary transmission stations where the interference arrival areas overlap each other and the interference arrival frequencies overlap each other with the secondary transmission station that performs notification related to the change of the frequency usage situation. Can be limited as a calculation target of the allowable transmission power. In other words, by using the interference arrival frequency, it is possible to reduce the number of secondary transmission stations that are unnecessary in calculating the allowable transmission power.

  In addition, when the spectrum manager receives a notification regarding the change in the frequency usage status of the secondary transmitting station, in addition to the secondary transmitting station that uses the managed frequency as the center frequency, if necessary, the frequency managed by another spectrum manager The secondary transmission station that uses this also calculates and notifies the allowable transmission power. Therefore, there is no redundant calculation process between different spectrum managers.

6). Other Embodiments According to the first to fifth embodiments described above, the number of secondary transmission stations to be calculated can be limited when calculating the allowable transmission power of the secondary transmission station, and the processing load is further increased. It is possible to eliminate the redundant calculation process between the spectrum managers while avoiding the concentration of the spectrum manager.

  Further, the primary system and the secondary system may be different RATs (Radio Access Technology) or the same RAT. Examples of different RATs include a combination of a TV broadcast system and a cellular system as described above. As an example of the same RAT, the case where the primary system is a macro cell and the secondary system is a femto cell installed therein can be cited.

  In the first to fifth embodiments described above, the spectrum manager and the radio environment database may be a system different from the secondary system that provides frequency management for a plurality of secondary systems, It may be a part of the secondary system. The spectrum manager and the radio environment database may be a system including a sensor station that monitors interference between radio systems. For example, by measuring the radio signal of the secondary transmitting station at the sensor station, the path loss from the secondary transmitting station to the surrounding interfered area is corrected, and using the corrected path loss, the interference arrival area and allowable transmission power are calculated. It can be performed.

  The spectrum manager in the first to fifth embodiments described above can also be embodied as predetermined hardware, for example, a circuit. Further, it can be configured to be controlled and operated by a computer circuit (not shown) (for example, a CPU (Central Processing Unit)) according to a control program. In this case, these control programs are stored in, for example, a storage medium (for example, a ROM (Read Only Memory) or a hard disk) or an external storage medium (for example, a removable medium or a removable disk). And read and executed by the computer circuit.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and applications are possible without departing from the gist of the present invention.

  The present invention can be applied to frequency usage management when a frequency allocated to a TV broadcasting system is used in a cellular system.

10 Primary transmitting station 11, 11_1 to 11_3 Primary receiving station 12 Primary system service area 20, 20_0 to 20_8 Secondary transmitting station IA20_0 to IA20_4 Interference area 30 Radio environment database 50, 51_1, 51_2, 52, 52_1, 52_2, 53, 53_1 , 53_2, 60_1 to 60_4 Spectrum manager
A51_1 to A51_4 Spectrum manager management areas 501, 521, 531 Network communication units 502, 522, 532 Frequency use reception units 503, 523 Database information storage unit 533 Wireless environment databases 504, 524, 534 Allowable transmission power setting unit

Claims (10)

A frequency management device that manages frequency use of a radio station in a radio system that shares a frequency allocated to another radio system,
A frequency usage receiving means for receiving a change notification of the frequency usage status from the first wireless station that changes the frequency usage status;
An allowable transmission power setting means for setting an allowable transmission power for a second wireless station whose interference coverage overlaps at least a part of the interference coverage of the first wireless station;
Have,
The allowable transmission power setting means is configured such that, in the second radio station having an interference reachable range that overlaps with the interference reachable range of the first radio station, an overlap range of the interference reachable range is a service of the other radio system. The frequency management apparatus, characterized in that it is limited to the second wireless station that overlaps at least a part of the range, and is set as the allowable transmission power . The frequency management apparatus according to claim 1, wherein the allowable transmission power is determined so that interference given to the other radio system does not exceed a predetermined threshold. The interference coverage, the frequency of Claim 1 or 2, characterized in that it comprises a spatial extent and / or frequency scope interference is estimated to be more than the predetermined threshold value by the transmitting radio station of the radio system Management device. The allowable transmission power setting means, when a frequency that causes the same frequency interference and / or adjacent frequency interference to the other radio system is included in the usable frequency and / or the actual usage frequency of the second radio station, The frequency management apparatus according to any one of claims 1 to 3 , wherein the second radio station is set as an allowable transmission power setting target. A frequency management method for managing frequency use of a radio station in a radio system sharing a frequency allocated to another radio system,
The frequency usage accepting unit accepts a frequency usage status change notification from the first wireless station that changes the frequency usage status,
The allowable transmission power setting means includes a second wireless station that overlaps at least a part of the interference reachable range of the first wireless station , and an overlapping range of the interference reachable range is that of the other wireless system. Limited to the second radio station that overlaps at least a part of the service range, the setting target of the allowable transmission power ,
A frequency management method characterized by the above. The frequency management method according to claim 5 , wherein the allowable transmission power is determined so that interference given to the other radio system does not exceed a predetermined threshold. The frequency according to claim 5 or 6 , wherein the interference reachable range includes a spatial range and / or a frequency range in which interference is estimated to be equal to or greater than a predetermined threshold due to transmission of a radio station of the radio system. Management method. When the allowable transmission power setting means includes a frequency that causes the same frequency interference and / or adjacent frequency interference to the other radio system as an available frequency and / or an actual usage frequency of the second radio station, frequency management method according to any one of claims 5-7, characterized in that the second radio station to the setting target of the allowable transmission power. A wireless system sharing a frequency assigned to another wireless system,
A plurality of radio stations sharing the frequency;
At least one frequency management device for managing frequency usage of the plurality of radio stations;
Have
When the frequency management device receives a notification regarding the change of the frequency usage status from the first radio station, the frequency management device may interfere with at least a part of the interference reachable range of the first radio station based on the notified change of the frequency status. Of the second radio stations with overlapping ranges, the overlapping range of the interference coverage is limited to the second radio station that overlaps at least a part of the service range of the other radio system, and the allowable transmission power To be set ,
A wireless system characterized by that. The wireless system according to claim 9 , wherein the allowable transmission power determined by the frequency management device is determined such that interference given to the other wireless system does not exceed a predetermined threshold.

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