JP5531622B2 - Wireless device, wireless communication system, apparatus, method and program used therefor - Google Patents

Description

  The present invention relates to a wireless device that recognizes a surrounding wireless environment, a wireless communication system, a spectrum sensing method, a wireless device control program, a frequency use information notification device, and a frequency use information notification program.

  In cognitive radio, which is a radio communication system that adaptively changes parameters used for radio communication according to the surrounding radio environment, the surrounding radio environment is recognized (a radio signal is detected), and the parameter is set according to the radio environment. Perform optimization. In particular, in a frequency band assigned to another radio communication system (hereinafter referred to as a primary system), the cognitive radio system shares and uses the frequency band as a secondary system, thereby improving frequency utilization efficiency.

  When the secondary system uses the frequency band in common with the primary system, the secondary system needs to prevent the existing service performed by the primary system from being affected. In the secondary system, in order to avoid interference with the primary system, use a frequency band that is not used temporally and spatially in the primary system, or communicate so that the amount of interference is less than or equal to that allowed by the primary system. There is a need to do. That is, the secondary system needs to accurately recognize the usage status of the frequency band by the primary system before using the frequency band.

  One example of a wireless communication system in which the secondary system uses a frequency band that is not used by the primary system is IEEE 802.22. IEEE 802.22 discusses standardization of a wireless regional area network (WRAN) system that is a secondary system that shares a frequency band (TV channel) allocated to a television broadcasting system that is a primary system. In this WRAN system, TV channel candidates that can be shared by the WRAN system are determined by using a geographic database. In the WRAN system, spectrum sensing is performed in order to recognize the channel usage status by the television broadcasting system.

  The aforementioned geographic database stores frequency usage information of the primary system. The frequency usage information stored in the geographic database includes the center frequency, frequency bandwidth, transmitter latitude / longitude information, transmission power, transmission antenna gain, and the like regarding the channel to which the license is assigned to the primary system. The secondary system acquires position information of a radio of the secondary system (hereinafter referred to as a secondary radio) using a global positioning system (GPS) or the like. Next, the secondary system accesses the geographic database and obtains stored frequency usage information to grasp the transmission status of the primary system. The primary system is not used around the secondary radio, and the primary system Candidate channels that are likely to be frequency shared with each other are determined.

  The spectrum sensing described above is a method for determining whether or not the channel used by the primary system can be shared at the position of the secondary radio, and the secondary radio is referred to as a primary system transmitter (hereinafter referred to as a primary transmitter). A surrounding wireless signal including a signal (hereinafter referred to as a primary signal) transmitted from the device is detected and analyzed. The secondary system analyzes a radio signal detected by the secondary radio by spectrum sensing and determines whether a primary signal exists around the secondary radio. In other words, it is determined whether or not the primary system is performing communication or broadcasting. Candidate channels and the like determined using a geographic database including frequency usage information can be used as the target of radio signal detection in spectrum sensing. In addition, spectrum sensing can estimate how much attenuation (propagation loss) occurs due to radio wave propagation between the primary transmitter and the secondary radio by detecting a radio signal including the primary signal. This estimation result of propagation loss is used to determine how much transmit power can be used by the secondary system within a range that does not affect the existing services of the primary system (hereinafter, this power is referred to as allowable transmit power). Is done.

  The specific signal processing method of spectrum sensing is roughly divided into a power detection method (energy detection: hereinafter referred to as a first signal processing method), which is determined by the magnitude of the received signal power obtained by time averaging, and a primary. There is a method (feature detection: hereinafter referred to as a second signal processing method) that uses a feature amount included in a signal for detection. As a second signal processing method, a method using the periodicity (cyclostationary) of the primary signal (see Patent Document 1) or a method using the periodicity included in the transmission signal or frame format (see Patent Document 2). For example, there is a method of preparing the same sequence as the pilot signal sequence in the received signal with the secondary radio unit and correlating with the received signal (see Non-Patent Document 1).

  As a requirement of the WRAN system regarding this spectrum sensing, IEEE 802.22 has a false detection probability when the reception power of an Advanced Television Systems Committee (ATSC) signal, which is a US television broadcasting standard, is −116 dBm or more at a bandwidth of 6 MHz. (Probability of misdetection) and false alarm probability (probability of false alarm) are each defined to be 0.1 or less.

  Here, the false detection probability means that the received frequency of the primary signal is greater than the reference power, but the searched frequency band is not used by the primary system and can be shared by the secondary system. It is the probability of judging. In addition, the false alarm probability is false if the primary system does not arrive in the searched frequency band and can be used in the secondary system, but the primary system exists and the secondary system cannot share the frequency. This is the probability of judging. The false detection of the primary signal leads to interference with the primary system, and the false alarm causes a decrease in frequency utilization efficiency.

  Also in the cognitive radio communication system other than the above-described WRAN system, it is necessary to protect the primary system from the interference of the secondary system and keep the frequency utilization efficiency of the used frequency band high as in the WRAN system. Therefore, the secondary system needs to set the false detection probability to a predetermined value or lower for a received signal with a level higher than the reference power, and set the false alarm probability to a predetermined value or lower for a received signal with a level sufficiently lower than the reference power. Have sex. Usually, in order to protect the existing services of the primary system with high priority, the requirements for spectrum sensing performed by the secondary system are strict, and extremely weak received signal level (for example, −116 dBm in 6 MHz bandwidth) is the reference power. Become. Therefore, in the secondary system, it is necessary to accurately determine whether or not frequency sharing is possible at the position of the secondary radio device with respect to the weak reception signal. In addition, when estimating the propagation loss between the primary transmitter and the secondary radio device by spectrum sensing, a weak received signal must be used for estimating the propagation loss as in the case of determining whether the frequency can be shared.

  Non-Patent Document 2 discloses a conventional technique in which a secondary system estimates a propagation loss between a primary transmitter and a secondary radio device by performing spectrum sensing using frequency usage information of the primary system. In Non-Patent Document 2, the Universal Mobile Telecommunications System (UMTS) of Frequency Division Duplex (FDD) is used as a primary system, the radio signal of the downlink channel is received, and the propagation loss is estimated by performing periodic stationary sensing. ing. Here, it is assumed that the center frequency, bandwidth, transmission power, and transmission antenna gain, which are frequency usage information related to the downlink channel, can be used in the secondary system. Estimating. In addition, a method for determining the allowable transmission power when the secondary system shares the frequency by using the estimated propagation loss is shown. The allowable transmission power uses a propagation loss estimation value, interference power from the secondary system that can be tolerated by the base station of the primary system (hereinafter referred to as allowable interference power), noise power, shadowing, and margin for correction of sensing error. Looking for. In the secondary system, communication is performed on the uplink channel of the primary system such that the amount of interference in the base station of the primary system is less than or equal to the allowable interference power by using transmission power that is equal to or lower than the allowable transmission power.

JP 2006-222665 A US2007092045

D. Cabric, S. M. Mishra, R.D. W. Brodersen, "Implementation issues in spectrum sensing for cognitive radios", the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers, November 2004 P. Marques, J. Bastos, A. Gameiro, "Opportunistic use of 3G uplink licensed bands", IEEE International Conference on Communication (ICC), May 2008

  As described above, in the secondary system, in order to satisfy the requirement to protect the high priority primary system, even when the reception level of the received signal is weak, whether the frequency sharing by the secondary system is possible, or It is necessary to estimate the propagation loss between the primary transmitter and the secondary radio. That is, high-accuracy spectrum sensing is required. However, in the prior art in Non-Patent Document 2, it is difficult to estimate the propagation loss with high accuracy for the following reason.

  The first reason is that the signal transmitted from the primary transmitter is affected by shadowing and fading in addition to the propagation loss caused by the distance attenuation in radio wave propagation between the primary transmitter and the secondary radio. . As described above, the reference power defined as the spectrum sensing requirement is usually set to a low value. Therefore, although the average reception level of the primary system signal in the secondary radio device is also lowered, the instantaneous reception level of the received signal may be further reduced by further adding instantaneous fluctuations in received power due to shadowing and fading. . At this time, the signal-to-noise ratio (SNR) at the time of signal reception in the secondary radio device that performs spectrum sensing is further deteriorated, and it is possible to determine whether frequency sharing is possible and to estimate propagation loss with high accuracy. It becomes difficult.

  The second reason is that, in the frequency band being used by the primary transmitter at the closest distance from the secondary radio, when another primary transmitter is also using the same frequency band, each secondary transmitter in the secondary system This is because the composite signal of the signal transmitted from is received.

  FIG. 1 is a diagram illustrating a primary transmitter 100 and a primary transmitter 101 that use the same frequency band, and a secondary radio 120 that performs spectrum sensing on the frequency band. The primary transmitter 100 and the primary transmitter 101 have a reference power area 50 and a reference power area 60, respectively. The secondary radio device 120 has a secondary system service area 30. As shown in FIG. 1, in the secondary radio device 120, when the secondary system service area 30 is outside the reference power area of the primary system, the frequency band may be shared with the primary system. In order to determine whether the power is outside the reference power area of the primary system, the secondary radio 120 performs spectrum sensing and confirms that the power of the received primary signal is lower than the reference power.

  However, since the primary transmitter 100 and the primary transmitter 101 use the same frequency band, the secondary radio unit 120 synthesizes and receives the primary signals transmitted from the primary transmitters. When the primary signal synthesized by the secondary radio 120 is received, the primary signal is received at a relatively large reception level compared to the case where a single primary signal is received. May be more than electric power.

  At this time, in the determination of whether or not the frequency can be shared by spectrum sensing, it is determined that the primary signal reaches the secondary radio with a reference power or higher, and the frequency band that can be shared is erroneously determined to be unshared. . That is, the false alarm probability is increased, and the frequency usage efficiency is lowered because the sharable frequency band cannot be effectively used in the secondary system. Further, when estimating the propagation loss by spectrum sensing, the reception level of the combined signal becomes high, and thus the propagation loss estimation value becomes smaller than the true value. That is, the estimation accuracy of the propagation loss is degraded. As a result, when the allowable transmission power is determined based on the propagation loss, only a transmission power smaller than the originally possible transmission power can be used.

  An object of the present invention is to provide a radio, a radio communication system, a spectrum sensing method, a radio control program, a frequency use information notifying device, and a frequency use information notifying program capable of estimating propagation loss with high accuracy. is there.

The radio device according to the present invention is a frequency band used for transmission by a first transmitter that performs transmission in the first frequency band with respect to the first frequency band that is a target of radio wave arrival status estimation. A second frequency band different from the one frequency band, or a third frequency band used for transmission by the second transmitter located in the vicinity of the first transmitter and different from the first frequency band. When at least one of the frequency bands is present, one or more frequency bands including at least one of the second or third frequency bands is selected as a selection candidate band, and a frequency band for detecting a radio signal from the selection candidate band a frequency band selection unit capable of selecting a, and a sensor unit for detecting a radio signal in the frequency band selected by the frequency band selection unit, a frequency band selection unit from among the selection candidates bands, each Based on the equivalent isotropically magnitude of radiation power of a radio signal transmitted by the frequency band, and selects a frequency band to detect a radio signal.

The radio communication system according to the present invention is a frequency band used for transmission by a first transmitter that performs transmission in the first frequency band with respect to the first frequency band to be estimated for radio wave arrival status. A second frequency band different from the first frequency band, or a frequency band used for transmission in a second transmitter located in the vicinity of the first transmitter and different from the first frequency band. When at least one of the three frequency bands exists, one or more frequency bands including at least one of the second or third frequency bands are selected candidate bands, and a frequency for detecting a radio signal from the selected candidate bands a frequency band selection unit capable of selecting a band, and a sensor unit for detecting a radio signal in the frequency band selected by the frequency band selection unit, a frequency band selection unit, the selection candidate band From, based on the size of the equivalent isotropic radiated power of the radio signal transmitted at each frequency band, and selects a frequency band to detect a radio signal.

A spectrum sensing method according to the present invention is a spectrum sensing method in a radio device, and is a first transmitter that performs transmission in a first frequency band with respect to a first frequency band that is a target of radio wave arrival status estimation. A second frequency band used for transmission and different from the first frequency band, or a frequency band used for transmission by a second transmitter located in the vicinity of the first transmitter. When at least one of the third frequency bands different from the first frequency band exists, one or more frequency bands including at least one of the second or third frequency bands are set as selection candidate bands, and the selection candidates from the band, based on the size of the equivalent isotropic radiated power of the radio signal transmitted at each frequency band, and selecting a frequency band to detect a radio signal, the selected frequency band And detecting the line signal.

A radio control program according to the present invention is a radio control program applied to a radio, and is transmitted to a computer in a first frequency band with respect to a first frequency band that is an object of radio wave arrival status estimation. Transmitted by a second transmitter located in the vicinity of the first transmitter or a second frequency band different from the first frequency band that is used for transmission by the first transmitter One or more frequency bands including at least one of the second and third frequency bands when there is at least one of the third frequency bands different from the first frequency band. and a selection candidate band from among the selection candidates band, based on the size of the equivalent isotropic radiated power of the radio signal transmitted at each frequency band, and selects a frequency band to detect a radio signal processing, and selection Characterized in that to execute a process for detecting a radio signal in the frequency band.

The frequency utilization information notification device according to the present invention is a frequency band used for transmission by a first transmitter that performs transmission in the first frequency band with respect to a first frequency band to be estimated for radio wave arrival status. A second frequency band different from the first frequency band, or a frequency band used for transmission in a second transmitter located in the vicinity of the first transmitter, When at least one of the third frequency bands different from the frequency band exists, one or more frequency bands including at least one of the second or third frequency bands are set as selection candidate bands, and the selection candidate bands A frequency band selection unit capable of selecting a frequency band for detecting a radio signal based on the magnitude of the equivalent isotropic radiant power of the radio signal transmitted in each frequency band, and the frequency band selection unit Yo Frequency wireless terminal including a wireless device and a sensor unit for detecting a radio signal to the other, are used in a wireless communication system that utilizes frequency band of estimation target radio wave arrival state at a selected frequency band Te Frequency usage information, which is information indicating the usage status of the band, at least the center frequency of the frequency band, the frequency bandwidth, the position information of the transmitter of the radio communication system, the transmission antenna height information of the radio communication system, the radio communication system Frequency utilization information including all or any of transmission power, transmission antenna gain of a wireless communication system, information indicating a propagation model, and standard reception antenna height is broadcast using a predetermined control channel.

The frequency utilization information notification program according to the present invention is used for transmission by a first transmitter that performs transmission in the first frequency band with respect to a first frequency band that is an object of estimation of radio wave arrival status. A second frequency band different from the first frequency band, or a frequency band used for transmission in a second transmitter located in the vicinity of the first transmitter, When at least one of the third frequency bands different from the first frequency band exists, one or more frequency bands including at least one of the second or third frequency bands are set as selection candidate bands, and the selection is performed. A frequency band selection unit capable of selecting a frequency band for detecting a radio signal based on the magnitude of the equivalent isotropic radiant power of the radio signal transmitted in each frequency band from the candidate bands and the previous band A wireless terminal including a wireless device and a sensor unit for detecting a radio signal in the frequency band selected by the frequency band selection unit to the other party, using a wireless communication system that utilizes frequency band of estimation target radio wave arrival state Frequency usage information, which is information indicating the usage status of the frequency band being used, at least the center frequency of the frequency band, the frequency bandwidth, the location information of the transmitter of the wireless communication system, the transmission antenna height information of the wireless communication system, It is characterized in that a process of broadcasting frequency utilization information including all or any of transmission power of a wireless communication system, transmission antenna gain of the wireless communication system, and information indicating a propagation model is performed using a predetermined control channel. .

  According to the present invention, propagation loss can be estimated with high accuracy.

It is explanatory drawing which shows the geographical positional relationship of the primary system and secondary system which show the subject in a prior art. It is explanatory drawing which shows the component of the primary system and secondary system in 1st Embodiment. 2 is a block diagram illustrating a configuration example of a secondary base station 200. FIG. It is explanatory drawing which shows the relationship between the distance from the example of a frequency utilization condition, and the received power in each radio | wireless machine, and a transmitter. 6 is an explanatory diagram illustrating an example of channel selection in a frequency band selection unit 2042. FIG. It is a block diagram which shows the structural example of the sensor part 2050 in the secondary base station 200. FIG. It is explanatory drawing which shows the relationship of the propagation loss between a primary system and a secondary system. It is a time-frequency diagram regarding transmission and reception of the secondary base station 200. 3 is a block diagram illustrating a configuration example of a secondary terminal 210. FIG. 4 is a flowchart showing a reception operation of a secondary base station 200. 4 is a flowchart showing a reception operation of a secondary base station 200. 4 is a flowchart showing a transmission operation of the secondary terminal 210. 4 is a flowchart showing a reception operation of a secondary terminal 210. It is explanatory drawing which shows the relationship between the primary system and secondary system in 2nd Embodiment. It is a block diagram which shows the structural example of the secondary base station 300 in 2nd Embodiment. 6 is an explanatory diagram illustrating an example of channel selection in a frequency selection unit 3042. FIG. 3 is a block diagram showing a configuration example of a sensor unit 3050 of the secondary base station 300. FIG. It is explanatory drawing which shows the relationship between the primary system and secondary system in 3rd Embodiment. It is a block diagram which shows the structural example of the secondary base station 400 in 3rd Embodiment. 6 is an explanatory diagram illustrating an example of channel selection in a frequency selection unit 4042. FIG. 10 is an explanatory diagram illustrating another example of channel selection in the frequency selection unit 4042. FIG. It is a block diagram showing a configuration example of a sensor unit 5050. It is explanatory drawing which shows the outline | summary of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

Embodiment 1. FIG.
First, a first embodiment will be described with reference to the drawings. FIG. 2 is an explanatory diagram illustrating the relationship between a primary system that is a frequency sharing target and a secondary system in the present invention that performs frequency sharing using spectrum sensing for the primary system. 2 shows a primary system transmitter (primary transmitter) 100, a primary system receiver (primary receiver) 110, a geographic database 150, a secondary system base station (secondary base station) 200, a secondary system A system terminal (secondary terminal) 210 is shown.

  The primary transmitter 100 is, for example, a transmitter that uses a frequency band that is a target of frequency sharing by the secondary radio of the present invention (in the example illustrated in FIG. 2, the secondary base station 200). The primary receiver 110 is a receiver that receives a primary signal from the primary system 100. The geographic database 150 stores frequency usage information indicating the frequency usage status of the primary system.

  The secondary base station 200 is an aspect of the secondary radio, recognizes the usage state of the frequency band around the secondary base station 200 by spectrum sensing, and transmits a signal by sharing the frequency if possible. It is a base station. The secondary terminal 210 is an aspect of a secondary wireless device and is a communication terminal that communicates with the secondary base station 200. In this example, the secondary terminal 210 can also receive a primary signal (radio wave detection) from the primary system 100 for spectrum sensing.

  In FIG. 2, the service areas of the primary system and the secondary system are shown as a primary system service area 10 and a secondary system service area 30, respectively. In addition, an area where it is necessary to suppress the false detection probability of the secondary base station 200 and the secondary terminal 210 related to the detection of the primary signal within a predetermined value is shown as the reference power area 50. In the region outside the reference power area 50, the secondary system needs to suppress the false alarm probability to a predetermined value or less.

  As shown in FIG. 2, the secondary service area 30 is outside the reference power area 50 so that communication in the secondary system does not interfere with the primary system. Thus, only when the secondary service area 30 is outside the reference power area 50, the secondary system performs frequency sharing with the primary system.

  The secondary base station 200 is connected to the geographic database 150 via a communication network so that frequency usage information regarding the primary system can be acquired. Access to the geographic database 150 may be via a wired network or a wireless network. In addition to directly accessing the geographic database 150, it may be acquired by receiving frequency usage information broadcasted by a broadcast system provided with a device accessible to the geographic database 150.

  Moreover, the secondary base station 200 and the secondary terminal 210 receive a primary signal, and determine by spectrum sensing that they are outside the reference power area. Or the secondary base station 200 and the secondary terminal 210 receive a primary signal, and estimate the propagation loss from the primary transmitter 100 by spectrum sensing.

  The secondary base station 200 instructs the secondary terminal 210 and other secondary terminals (not shown) of the frequency band (channel) for performing spectrum sensing and the transmission power. Here, the frequency band in which spectrum sensing is performed is a unit obtained by dividing a channel when the primary system for which the radio wave arrival state is estimated is an Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) system digital television broadcast. It may be a certain segment. In the secondary terminal 210, frequency sharing availability determination, propagation loss estimation, and reception power estimation are performed on the channel indicated by the secondary base station 200, and the transmission power indicated by the secondary base station 200 is used to transmit the channel with the secondary base station 200. Communicate. Here, the secondary base station 200 obtains an allowable transmission power at which interference with the primary receiver is equal to or lower than the allowable interference power, and sets the transmission power equal to or lower than the allowable transmission power as the transmission power of the secondary base station 200 or the secondary terminal 210. .

  Next, the configuration of the secondary base station 200 will be described using FIG. FIG. 3 is a block diagram illustrating a configuration example of the secondary base station 200. The secondary base station 200 shown in FIG. 3 includes an antenna 2001, a transmission / reception separation unit 2002, a transmission modulator 2010, a low noise amplifier 2031, an RF analog unit 2030, a sensor unit 2050, a reception demodulator 2020, a frequency A usage information acquisition unit 2041, a frequency band selection unit 2042, an allowable transmission power setting unit 2060, and a transmission control unit 2070 are provided.

  The antenna 2001 is an antenna used at the time of transmission / reception. The transmission / reception separating unit 2002 supplies the signal transmitted from the transmission modulator 2010 to the antenna 2001 when transmitting, and transmits the signal received by the antenna 2001 to the low noise amplifier 2031 when receiving.

  The transmission modulator 2010 uses the transmission power determined by the transmission control unit 2070 to encode and modulate a transmission bit sequence to generate a transmission signal and send it to the transmission / reception separation 2002. The transmission bit sequence is composed of data or control information generated by the transmission control unit 2070.

  The low noise amplifier 2031 amplifies the reception signal supplied from the transmission / reception separation 2002 and supplies the signal to the band pass filter 2032 in the RF analog unit 2030.

  The RF analog unit 2030 is supplied with an RF signal from the low noise amplifier 2031 and supplies a digital baseband signal to the reception demodulator 2020 or the sensor unit 2050. The RF analog unit 2030 includes a band pass filter 2032, a mixer 2033, a local oscillator 2034, a low pass filter 2035, and an analog / digital conversion unit 2036.

  First, the band pass filter 2032 sets the center frequency and bandwidth determined by the frequency band selection unit 2042 and performs filtering of the RF signal. The filtered signal is sent to the mixer 2033.

  The local oscillator 2034 sets the center frequency determined by the frequency band selection unit 2042 and sends a sine signal to the mixer 2033.

  The mixer 2033 multiplies the sine signal generated by the local oscillator 2034 and the signal supplied from the band pass filter 2032. This signal is sent to the low-pass filter 2035.

  The low-pass filter 2035 filters the signal sent from the mixer 2033 with the bandwidth determined by the frequency band selection unit 2042, thereby generating an in-phase component and a quadrature component of the baseband signal from the RF signal.

  The generated baseband signal is sampled by an analog-digital converter 2036 and converted from an analog signal to a digital signal. The generated digital signal is sent to the reception demodulator 2020 or the sensor unit 2050.

  The reception demodulator 2020 generates a transmission bit sequence sent from the secondary terminal by performing demodulation processing and decoding processing on the digital signal sent from the analog-digital converter 2036. Here, when the transmission bit sequence transmitted from the secondary terminal includes a determination result of whether or not frequency sharing is possible as control information and a propagation loss estimation value (or reception power estimation value), the information is used as an allowable transmission power setting unit. Send to 2060.

  The frequency usage information acquisition unit 2041 acquires the frequency usage information stored in the geographic database 150 through the communication network. Here, the frequency usage information is information about the usage status of the frequency band that is the frequency sharing target in the secondary system, and at least the center frequency of each channel, the frequency bandwidth, the position information of each primary transmitter (for example, Latitude / longitude information, transmission antenna height information), transmission power, and transmission antenna gain. Furthermore, the service area radius and the allowable interference power of the primary receiver may be included. These are used, for example, for transmission power control. Furthermore, an applicable propagation model and necessary parameters (standard reception antenna height of the primary receiver, etc.) corresponding to the model may be included. These are used for correction between frequency bands, for example. In the present embodiment, the center frequency of each channel, frequency bandwidth, latitude / longitude information of each primary transmitter, transmission antenna height information, transmission power, transmission antenna gain, service area radius, applicable propagation model, and primary receiver tolerance Including interference power, standard receiver antenna height of primary receiver. Such frequency use information is created in the frequency band selection unit 2042.

  The frequency band selection unit 2042 determines a channel for determining whether the frequency can be shared between the secondary base station 200 and the secondary terminal based on the frequency usage information acquired by the frequency usage information acquisition unit 2041. Among these, the channel for determining whether or not the secondary terminal can be shared is sent to the transmission control unit 2070. In addition, the frequency band selection unit 2042 sends frequency use information necessary for spectrum sensing of the secondary terminal to the transmission control unit 2070. In this example, the frequency usage information transmitted to the terminal is the center frequency of each channel, the frequency bandwidth, the latitude / longitude information of the primary transmitter, the transmission antenna height information, the transmission power, and the transmission antenna gain.

  Next, a channel determination method in the frequency band selection unit 2042 will be described. Here, the channel (that is, the first frequency band) that is the first target for estimating the radio wave arrival status in the secondary base station 200 is CH_0. The channel that is the target of radio wave arrival status estimation is a channel that is the target of reception power estimation or frequency sharing availability determination in the secondary system, and may be determined according to a predetermined method. The determination method of CH_0 may be arbitrary. For example, when determining whether or not frequency sharing is possible for all TV channels, the channels may be selected in order from the lowest frequency. Further, for example, sorting may be performed in ascending order by equivalent isotropic bi-polar power, and the power may be selected from those having the smallest power.

  The frequency band selection unit 2042 first selects a channel that is a selection candidate for the CH_0, using CH_0 and another channel used by the primary transmitter (using CH_0 to transmit a primary signal) ( That is, the second frequency band) and the channel (that is, the third frequency band) used by the primary transmitter adjacent to the primary transmitter using CH_0. For example, a primary transmitter that uses CH_0 is installed in the same manner on another primary transmitter installed on the same roof as the building on the roof, or on a broadcasting tower (radio station) on which the primary transmitter is installed Another primary transmitter becomes a primary transmitter in the above-mentioned close position, and a channel used by these transmitters becomes a selection candidate. More specifically, for example, using the frequency usage information acquired from the geographic database 150, the latitude / longitude of the primary transmitter using CH_0 is set at a latitude / longitude equal to or within a certain value and transmitted. Similarly, for the antenna height, a search is made for a primary transmitter that is within a certain value, and a channel used in the primary transmitter is selected as a candidate for selection.

  The frequency band selection unit 2042 selects a channel having the maximum equivalent isotropic radiant power, which is the product of the transmission power and the transmission antenna gain, from these selection candidate channels. The selected channel (referred to as CH_k) is a channel on which the secondary base station 200 actually performs spectrum sensing. The center frequency and bandwidth of this CH_k are sent to the band pass filter 2032. Further, the center frequency of CH_k is sent to the local oscillator 2034, and the bandwidth of CH_k is sent to the low-pass filter 2035. Further, the equivalent isotropic radiant power used in CH_k and the equivalent isotropic radiant power used in channel CH_0, which is a determination target of whether or not frequency sharing is possible, in secondary base station 200 are sent to sensor unit 2050.

  Further, frequency band selection section 2042 sends frequency use information related to CH_0 to allowable transmission power setting section 2060.

Hereinafter, a channel selection method in the frequency band selection unit 2042 will be described with reference to the drawings. FIG. 4 is an explanatory diagram showing an example of the frequency utilization situation and the relationship between the received power at each radio and the distance from the transmitter. FIG. 4 shows an example in which the primary transmitter 100 transmits a primary signal using CH_0 and CH_1. Here, it is assumed that the signals of CH_0 and CH_1 are transmitted from the same transmitter. Further, it is assumed that the equivalent isotropic radiant power P _{1 of} CH — ₀ <the equivalent isotropic radiant power P _{2 of} CH — ₁ from the frequency use information. A signal transmitted from the primary transmitter 100 is transmitted with an equivalent isotropic radiant power (for example, P ₁ or P ₂ ), and is attenuated and received as the distance from the primary transmitter 100 (PS) increases. That is, the received power at the receiver decreases as the distance from the primary transmitter 100 increases. At this time, as shown in the graph of FIG. 4, as the relationship between the propagation loss G ₂ path loss G ₁ and CH_1 of CH_0, signals transmitted from the same transmitter (or transmitters in the vicinity) is comparable It can be seen that the distance is attenuated.

  FIG. 5 is an explanatory diagram showing an example of channel selection in the frequency band selection unit 2042 in the frequency usage situation shown in FIG. FIG. 5A is an explanatory diagram illustrating an example of channel selection in relation to the equivalent isotropic radiant power, and FIG. 5B is an explanatory diagram illustrating an example of channel selection in a geographical relationship. . For example, in the case of the frequency use situation as shown in FIG. 4, as shown in FIG. 5, CH_0 having a smaller equivalent isotropic radiant power is set as the first radio wave arrival state estimation target (ie, the first frequency band). ), In order to determine whether or not the frequency sharing of CH_0 is possible, CH_1 having a larger equivalent isotropic radiant power in the first, second, or third frequency band may be set as a sensing target. Propagation loss estimation accuracy can be improved by using a channel with a large equivalent isotropic radiant power, and CH_0 received power estimation accuracy can be improved by using a highly accurate propagation loss estimation value. Because.

  Next, the configuration of the sensor unit 2050 will be described with reference to FIG. The sensor unit 2050 is a specific example using power detection as a spectrum sensing method. Similarly, in the following embodiments, power detection is used as an example, but the spectrum sensing technique to be used is not limited to this.

  6 includes a power detection unit 2051, a propagation loss estimation unit 2052, a desired channel received power estimation unit 2053, and a determination unit 2054.

  The baseband signal transmitted from the analog / digital converter 2036 is input to the power detection unit 2051. The power detection unit 2051 calculates an estimated value of the received power of the primary signal based on the input baseband signal. For example, the power detection unit 2051 calculates an addition average for the square value of each sample from the input baseband signal. Furthermore, the estimated value of the received power of the primary signal is obtained by subtracting the noise power at the secondary base station 200 from the added average value. In this example, the estimated value of the received power of the primary signal is calculated by the following equation (1).

Here, y (n) is the sample value of the CH_k baseband signal in the n-th sample, N is the number of samples used in the averaging, σ ² is the noise power in the secondary base station 200, and D _k is the primary signal reception. This is an estimate of power. Here, the baseband signal y (n) is a complex number having an equivalent low-frequency representation and having an in-phase component in the real part and an orthogonal component in the imaginary part. The noise power needs to be estimated by the secondary base station 200, but is not shown here. The received power estimation value of the CH_k primary signal obtained by Expression (1) is sent to the propagation loss estimation unit 2052.

  Propagation loss estimation unit 2052 uses CH_k based on the equivalent isotropic radiant power of CH_k sent from frequency band selection unit 2042 and the received power estimation value of the primary signal of CH_k sent from power detection unit 2051. The propagation loss between the primary transmitter and the secondary base station 200 to be estimated is estimated. The propagation loss estimation unit 2052 divides, for example, the equivalent isotropic radiant power of CH_k sent from the frequency band selection unit 2042 by the received power estimate value of the primary signal of CH_k sent from the power detection unit 2051, and a low noise amplifier By taking the product of the gain of 2030, the propagation loss between the primary transmitter using CH_k and the secondary base station 200 is estimated. In this example, the propagation loss is estimated (calculated) by the following equation (2).

Here, P _k represents the equivalent isotropic radiated power of CH_k, G _amp represents the gain of the low-noise amplifier 2031 (including the gain when there is automatic gain control), and L _k is a propagation loss. is there. The propagation loss is defined as the reciprocal of the propagation gain. Since the primary transmitter using CH_k and the primary transmitter using CH_0 are the same or close to each other, this propagation loss is the propagation loss between the primary transmitter using CH_0 and the secondary base station 200. Can be considered. The propagation loss thus obtained is sent to desired channel received power estimation section 2053 and allowable transmission power setting section 2060.

Desired channel received power estimating section 2053 estimates the received power of CH_0 based on the propagation loss sent from propagation loss estimating section 2052 and the equivalent isotropic radiated power of CH_0 sent from frequency band selecting section 2042. The desired channel received power estimation unit 2053, for example, sets the propagation loss sent from the propagation loss estimation unit 2052 and the equivalent isotropic radiant power of CH_0 sent from the frequency band selection unit 2042 to the following equation (3). By using this, the reception power estimation value P _{rx, 0} of CH_0 is calculated.

The CH_0 received power estimation value P _{rx, 0} obtained here is sent to the determination unit 2054. The determination unit 2054 determines whether or not frequency sharing is possible for CH_0 based on the reception power estimation value of CH_0 sent from the desired channel reception power estimation unit 2053. For example, the determination unit 2054 compares the received power estimation value of CH_0 sent from the desired channel received power estimation unit 2053 with a predetermined threshold, and when the received power estimation value is smaller than the threshold, the frequency sharing is possible. If the received power estimation value is higher than the threshold value, it may be determined that frequency sharing is not possible. This binary information (frequency sharing / non-sharing) for determining whether the frequency can be shared is sent to the allowable transmission power setting unit 2060. In addition to this, by comparing _Dk , which is the estimated received power value of the primary signal of CH_k, with a threshold value, whether to share the frequency of CH_k is determined and sent to the allowable transmission power setting unit 2060 together with the result of CH_0. May be. In addition, although the received power estimated value of CH_0 was calculated | required using Formula (3) from Formula (1) here, it is not limited to this form, It is one formula which put Formula (1) to Formula (3) together. The form to calculate may be sufficient.

  The allowable transmission power setting unit 2060 sets the allowable transmission power based on the binary information transmitted from the determination unit 2054 that indicates whether the frequency can be shared. For setting the allowable transmission power, various types of frequency use information regarding CH_0 sent from the frequency band selection unit 2042 is used. Further, the determination result of whether or not the frequency sharing is possible in the secondary terminal sent from the reception demodulator 2020 and the propagation loss estimated value (or received power estimated value) may be used. Here, when using the result of frequency sharing availability obtained by spectrum sensing at the secondary terminal, when the result of frequency sharing is 1 and the result of frequency sharing is 0, the secondary base station 200 The final determination result can be the logical sum or logical product of all the determination results including the determination result of whether frequency sharing is possible. In addition, when using the propagation loss estimated value and the received power estimated value obtained by spectrum sensing at the secondary terminal, it is also possible to use the average value of each as the final propagation loss estimated value and received power estimated value. is there. In the following, in order to simplify the description, the allowable transmission power is set using the determination result of the frequency sharing possibility obtained by the secondary base station 200 itself and the estimated propagation loss.

  First, when the frequency sharing is impossible from the result of the binary information indicating whether the frequency sharing is possible or not, the allowable transmission power is set to 0 [W].

Next, FIG. 7 shows the relationship of propagation loss between the primary system and the secondary system when frequency sharing is possible. FIG. 7 shows the primary transmitter 100, the primary receiver 110 located closest to the secondary system in the primary system service area 10, and the secondary base station 200. Further, as in FIG. 2, a primary system service area 10, a secondary system service area 30, and a reference power area 50 are shown. In addition, the propagation loss estimate from the secondary base station 200 until the primary receiver 110 and _{L SP,} the propagation loss estimate from the primary transmitter 100 to the secondary base station 200 is set to _{L PS.}

Propagation loss estimated value L _SP is the closest position from secondary base station 200 using the position of primary transmitter 100 and the service area radius (secondary base station 200 can acquire its own position information by GPS or the like). The service area end of the primary system (position of the primary receiver 110 in FIG. 7) is obtained, and the propagation loss between the position and the secondary base station is obtained based on the applied propagation model. Here, a propagation model such as the Okumura / Sakai model can be used as the applied propagation model. In this embodiment, the propagation model specified by the frequency usage information acquired from the geographic database 150 is used. For example, when using the Okumura / Kashiwa model, the secondary base station 200 calculated using the standard antenna height of the primary receiver 110, the center frequency, the antenna height of the secondary base station 200, and the position information indicated by the frequency specification information. And the distance from the service area edge of the primary system to calculate the propagation loss. Similarly, the propagation loss estimated value L _PS can also be obtained from the applied propagation model using the position information of the primary transmitter 100 and the position information of the secondary base station 200.

When the frequency sharing is possible, the allowable transmission power P _{S, allow} (however, including the transmission antenna gain of the secondary base station 200 is included so that the reception interference power at the primary receiver 110 does not exceed the allowable value (allowable interference power)). Is set to the equivalent isotropic radiant power. More specifically, the allowable transmission power may be calculated by the following equation (4).

Here _{, PS, allow} is the allowable interference power in the primary receiver (where the reception antenna gain of the primary receiver is included), and Γ is a margin considering shadowing and fading. However, all values in the equation (4) are values converted from true values to dBm or dB.

  In addition to setting the allowable transmission power according to the equation (4), for example, the propagation loss estimation value between the primary transmitter and the secondary base station 200 obtained by performing spectrum sensing in the propagation loss estimation unit 2052 is calculated. The allowable transmission power may be set using the method described in Non-Patent Document 2 described above. That is, you may obtain | require using the margin for propagation loss estimated value, allowable interference power, noise power, shadowing, and sensing error correction.

  The permissible transmission power determined in this way is sent to the transmission control unit 2070.

  The transmission control unit 2070 performs transmission power control within a range equal to or less than the allowable transmission power determined by the allowable transmission power setting unit 2060 in order to determine the power used for transmission in the secondary base station 200. In addition, the transmission power used for transmission at the secondary terminal 210 is also determined to be equal to or lower than the allowable transmission power, and is generated as control information. Also, scheduling information representing radio resources (channels, time slots, codes, etc.) used by each secondary terminal 210 when communicating with the secondary base station is generated.

  In addition, when spectrum sensing is also performed by the secondary terminal 210, sensing scheduling information (a radio resource and the secondary terminal) indicating radio resources (channel, time slot, code, etc. for spectrum sensing) that the secondary terminal 210 performs sensing. 210) is generated as control information.

  Also, the transmission control unit 2070 generates the frequency usage information sent from the frequency band selection unit 2042 as control information. In addition to these control information, any control information necessary for communication between the secondary systems is generated. The control information determined by the transmission control unit 2070 is sent to the transmission modulator 2010.

  FIG. 8 shows the transmission or reception period and spectrum of the channel CH_0 that is the frequency sharing target, the channel CH_k that is the target of spectrum sensing, and the secondary radio (generic name including secondary base station and secondary terminal) in the other channel CH_x. A transmission stop time (Quiet Period) for sensing is shown. FIG. 8 illustrates an example in which CH_0 and CH_k are synchronized with the transmission stop time, but CH_x is not synchronized with CH_0 and CH_k. In the transmission stop time, the secondary base station and the secondary terminal stop transmission, so that the secondary base station and the secondary terminal can receive the primary signal without unnecessary interference, thereby performing accurate spectrum sensing. It becomes possible.

  As already described, the frequency band selection unit 2042 uses a received signal of CH_k instead of CH_0 at a predetermined timing to perform spectrum sensing in order to determine whether or not frequency sharing is possible in the frequency sharing target channel CH_0. Perform estimation and frequency sharing availability. At this time, if the transmission stop time at CH_0 and the transmission stop time at CH_k are time-synchronized as shown in FIG. 8, spectrum sensing can be performed at a predetermined timing. However, spectrum sensing cannot be performed at the same timing as the transmission stop time on CH_0 in a channel that is not time-synchronized with the transmission stop time on CH_0, such as CH_x. Therefore, in the secondary system or the primary system, when the determination delay in spectrum sensing can be allowed, spectrum sensing is performed during the transmission stop time in CH_x, and when the determination delay cannot be allowed, the frequency band selection unit 2042 transmits Only channels that are synchronized in the stop time may be selected as candidates, and CH_x that is not synchronized in the transmission stop time may be excluded from the selection candidates.

  Next, the secondary terminal 210 will be described. FIG. 9 is an explanatory diagram illustrating a configuration example of the secondary terminal 210. The secondary terminal 210 shown in FIG. 9 includes an antenna 2101, a transmission / reception separation unit 2102, a transmission modulator 2110, a low noise amplifier 2131, an RF analog unit 2130, a sensor unit 2150, a reception demodulator 2120, a frequency band A selection unit 2142 and a transmission control unit 2170 are provided. The RF analog unit 2130 includes a band pass filter 2132, a mixer 2133, a local oscillator 2134, a low pass filter 2135, and an analog / digital conversion unit 2136. 3 is different from the secondary base station 200 shown in FIG. 3 in that the frequency use information acquisition unit 2041 and the allowable transmission power setting unit 2060 are not included. Hereinafter, the description of the components in the secondary terminal 210 showing the same operation as the components in the secondary base station 200 will be omitted.

  The reception demodulator 2120 performs demodulation and decoding of the data signal / control signal transmitted from the secondary base station 200. Here, the control signal includes transmission power used in the secondary terminal 210, scheduling information, sensing scheduling information, frequency use information, and other information necessary for communication. Reception demodulator 2120 sends transmission power, scheduling information, and frequency usage information to transmission control section 2170. Reception demodulator 2120 also sends sensing scheduling information and frequency usage information to frequency band selection section 2142.

  The frequency band selection unit 2142 determines, from the sensing scheduling information sent from the reception demodulator 2120, a channel for which the secondary terminal 210 determines whether frequency sharing is possible and a time slot for sensing. Here, the channel is assumed to be CH_1. Next, the frequency band selection unit 2142 receives the frequency use information (center frequency of each band, frequency bandwidth, latitude / longitude information of the primary transmitter, transmission antenna height information, transmission power, transmission) transmitted from the reception demodulator 2120. In the same manner as the frequency band selection unit 2042, based on the antenna gain), the equivalent or the like in the primary transmitter using CH_1 or another channel used in the primary transmitter in a position close to the primary transmitter. The channel (referred to as CH_m) having the maximum radiant power is selected as the spectrum sensing target band. The center frequency and frequency bandwidth related to the selected CH_m are sent to the band pass filter 2132, the local oscillator 2134, and the low pass filter 2135, and parameters are set so that the CH_m signal can be converted into a baseband signal. Is done. Further, the frequency use information regarding CH_1 and CH_m is sent to the sensor unit 2150.

  The sensor unit 2150 receives the CH_m baseband signal in the time slot specified by the sensing scheduling information, and performs CH_m reception power estimation and propagation loss estimation in the same manner as the sensor unit 2050. In addition, the sensor unit 2150 estimates the received power of CH_0 using this propagation loss estimated value and the ratio of the equivalent isotropic radiated power of CH_1 and CH_m. Furthermore, whether or not frequency sharing is possible is determined by comparing the received power estimation values of CH_1 and CH_m with a predetermined threshold value. The propagation loss estimation value and the determination result of whether or not frequency sharing is possible are sent to the transmission control unit 2170.

  Transmission control section 2170 performs transmission power control using the transmission power sent from reception demodulator 2120 and scheduling information, and determines radio resources used for transmission. Further, the propagation loss estimation value sent from the sensor unit 2150 and the determination result of whether or not frequency sharing is possible are generated as control information. If there is other information necessary for communication between the secondary systems, it is generated as control information. The control information generated by the transmission control unit 2170 is sent to the transmission modulator 2110, encoded and modulated, and transmitted.

  Next, the operation of this embodiment will be described. 10 and 11 are flowcharts showing an example of the operation of the secondary base station 200 of the present embodiment. FIG. 10 is a flowchart showing an example of an operation at the time of transmission of the secondary base station 200, and FIG. 11 is a flowchart showing an example of an operation at the time of reception of the secondary base station 200.

  First, the transmission operation will be described with reference to FIG. In the secondary base station 200, transmission is started at a predetermined timing. As shown in FIG. 10, prior to transmission of the data signal or control signal, first, the allowable transmission power in the frequency sharing target band set by the allowable transmission power setting unit 2060 is set in the transmission control unit 2070 (S101). ). The transmission control unit 2070 performs transmission power control at transmission power that is equal to or lower than the allowable transmission power (S102). The transmission control unit 2070 generates control information such as scheduling information and sensing scheduling information, performs prescribed encoding and modulation in the transmission modulator 2010, and generates an RF signal from the baseband signal by performing frequency conversion (S103). ). The generated RF signal is transmitted from the antenna 2001 via the transmission / reception separating unit 2002 (S104).

  Next, the reception operation will be described with reference to FIG. The secondary base station 200 starts reception at a predetermined timing. As shown in FIG. 11, the signal received by the antenna 2001 is amplified by the low noise amplifier 2031 via the transmission / reception separating unit 2002 (S201). The frequency band selection unit 2041 determines a frequency band to be subjected to spectrum sensing in the amplified signal (S202). The amplified signal is input to the RF analog unit 2030, and signal components other than the frequency band determined by the frequency band selection unit 2042 are filtered by the band pass filter 2032, and the base signal is output by the mixer 2033, the local oscillator 2034, and the low pass filter 2035. The signal is converted into a band signal and sampled by the analog-digital converter 2036 to generate a digital signal (S203).

  When the generated signal is a signal transmitted from another secondary radio (for example, the secondary terminal 210) and is a signal to be demodulated, the reception demodulator 2020 performs demodulation and decoding, and data Signals and control signals are converted into bit sequences (S204, S205). Here, when the demodulated / decoded bit sequence is a control signal and is a determination result of whether or not frequency sharing is possible in spectrum sensing performed by another secondary wireless device or a propagation loss estimated value (or a received power estimated value) Are input to the allowable transmission power setting unit 2060 and used for setting the allowable transmission power in step S207.

  If the baseband signal generated in step S203 is a spectrum sensing target signal, it is input to the sensor unit 2050, and the channel frequency usage information set by the frequency band selection unit 2042 is used to determine the spectrum sensing target channel. Estimation of propagation loss, estimation of received power of a channel for determining whether or not frequency sharing is possible, and determination of whether or not frequency sharing is possible are performed (S204, S206). The allowable transmission power is set using the frequency sharing availability determination result and the propagation loss estimation value in the secondary base station 200 and other secondary terminals (S207).

  In the above transmission operation and reception operation, transmission and reception are performed at a predetermined timing. However, the transmission / reception timing is performed at a predetermined timing as shown in FIG. 8 or a timing determined by the secondary base station 200, for example. May be.

  12 and 13 are flowcharts showing an example of the operation of the secondary terminal 210 of the present embodiment. FIG. 12 is a flowchart illustrating an example of an operation at the time of transmission of the secondary terminal 210, and FIG. 13 is a flowchart illustrating an example of an operation of the secondary terminal 210 at the time of reception.

  First, the transmission operation will be described with reference to FIG. In the secondary terminal 210, transmission is started at a predetermined timing. As shown in FIG. 12, prior to the transmission of the data signal or control signal, the transmission power designated by the secondary base station 200 is set (S301). Next, radio resources used by the secondary terminal 210 are set based on the scheduling information specified by the secondary base station 200 (S302). Transmission control section 2170 generates propagation loss estimation value, frequency sharing availability determination result, and other information necessary for communication in the secondary system as control information, and performs prescribed encoding and modulation in transmission modulator 2110. An RF signal is generated from the baseband signal by conversion (S303). The generated RF signal is transmitted from the antenna 2101 via the transmission / reception separating unit 2102.

  Next, the reception operation will be described with reference to FIG. The secondary terminal 210 starts reception at a predetermined timing. As shown in FIG. 13, the signal received by the antenna 2101 is amplified by the low noise amplifier 2131 via the transmission / reception separating unit 2102 (S401). The frequency band selection unit 2142 determines a channel for performing spectrum sensing in the amplified signal based on the frequency use information (S402). The amplified signal is input to the RF analog unit 2130, and signal components other than the channel determined by the frequency selection unit 2142 are filtered by the band pass filter 2132, and the baseband signal is output by the mixer 2133, the local oscillator 2134, and the low pass filter 2135. And is sampled by the analog-to-digital converter 2136 to generate a digital signal (S403).

  When the generated digital signal is a signal transmitted from the secondary base station 200 and is a signal to be demodulated, the reception demodulator 2120 demodulates and decodes the data signal and the bit sequence of the control signal. (S404, S405). Here, when the demodulated / decoded bit sequence is a control signal related to transmission control (for example, information indicating transmission power, scheduling information, or frequency use information), reception demodulator 2120 transmits the information. It inputs into the control part 2170, and uses it for the setting of the radio | wireless resource of step S302 shown in FIG. If the demodulated / decoded bit sequence is a control signal related to band setting (for example, sensing scheduling information or frequency use information), it is input to the frequency band selecting unit 2142 and used for band setting in step S402. In addition, what control signal is input to which processing unit may be determined in advance.

  If the digital signal generated in step S403 is a spectrum sensing target signal, it is input to the sensor unit 2150 and the channel frequency usage information set by the frequency band selection unit 2142 is used to propagate the spectrum sensing target channel. Loss estimation, channel received power estimation for determining frequency sharing availability, and frequency sharing availability determination are performed (S404, S406).

  As described above, in the present embodiment, a channel having higher transmission power than the channel to be determined as to whether frequency sharing is possible can have an equivalent radio wave propagation loss (that is, from the same transmitter or a nearby transmitter). ) If the signal is transmitted, the propagation loss is estimated by selecting the largest channel and performing spectrum sensing. For this reason, compared with the case where spectrum sensing is performed on CH_0 (that is, the first frequency band) that performs frequency sharing or not, and propagation loss estimation or frequency sharing determination is performed, the cognitive radio base station for performing spectrum sensing or The signal power to noise ratio (Signal to Noise Ratio: SNR) in the cognitive radio terminal can be improved.

  Moreover, if such a highly accurate propagation loss estimation value is used, the estimation accuracy of received power can be increased, and the determination accuracy of frequency sharing availability can be improved. Also, the transmission allowable power can be set with high accuracy. In addition, since the accuracy of frequency sharing determination is improved, the time required for spectrum sensing to meet the specified accuracy specified in system requirements is reduced when estimating propagation loss and determining frequency sharing. it can.

  Also, by using the propagation loss estimation value obtained by performing such high-accuracy spectrum sensing, the allowable transmission power at the cognitive radio base station or cognitive radio terminal can be set with higher accuracy, and the frequency sharing target It is possible to suppress excessive interference given to the receiver of the wireless communication system. Also, transmission power at the cognitive radio base station or the cognitive radio terminal can be increased until the interference given to the receiver of the radio communication system that is the frequency sharing target reaches a predetermined value. That is, an appropriate allowable transmission power can be set.

  Note that the sensor units 2050 and 2150 of the secondary base station 200 and the secondary terminal 210 described above are frequency bands selected by the frequency band selection units 2042 and 2142 instead of performing spectrum sensing on the channel for determining whether or not frequency sharing is possible. The spectrum sensing was performed for the channel, and the results were used to estimate the propagation loss of the channel, the received power estimation, and the frequency sharing possibility. It is possible to correct the loss difference.

For example, in the case of the secondary base station 200, CH_0 is the target channel for determining whether to share frequency, CH_k is the band selected by the frequency band selection unit 2042, and the propagation loss calculated from the applied propagation model in each channel is L. _{Let M, 0} , L _{M, k} . Further, when the actual propagation loss of CH_k estimated using the received signal of CH_k L _{k (Equation} 2), the propagation loss estimated value L _C at CH_0 obtained by correcting the propagation loss difference between the channels, the following formula (5).

  Here, β is a predetermined correction coefficient that satisfies 0 ≦ β ≦ 1.

  The secondary terminal 210 can perform the same propagation loss correction. In this case, it is necessary for the secondary terminal 210 to acquire parameters necessary for calculating the propagation loss difference from the applied propagation model. For example, when the secondary base station 200 notifies the parameters necessary for estimating the propagation loss difference, when the transmission control unit 2070 of the secondary base station 200 generates control information corresponding to the frequency usage information, each band In addition to the center frequency, frequency bandwidth, primary transmitter latitude / longitude information, transmit antenna height information, transmit power, transmit antenna gain, including information indicating the applicable propagation model and the standard receive antenna height of the primary receiver Control information is generated and transmitted to the secondary terminal 210. Or when there exists a system which alert | reports frequency utilization information, the secondary terminal 210 may receive and acquire the frequency utilization information alert | reported by this alerting | reporting system.

  Further, the correction of the propagation loss difference in the equation (5) can be performed with partial frequency use information.

For example, it is assumed that the applied propagation model is the Okumura / Sakai model. Propagation loss L _M when using the Okumura-Hata model is expressed by the following equation (6).

Here, f is a center frequency, d is a distance between transmitters and receivers, h _b is a transmission antenna height, a (h _m ) is a correction coefficient corresponding to a reception antenna height h _m , and log is a logarithm with a base of 10. is there. Using this equation (6), the propagation loss component caused by the center frequency difference between the frequency bands CH_0 and CH_k is the second term, and the propagation loss component caused by the transmission antenna height difference is the third term, the fifth term, It can be seen that the propagation loss component due to the transmission / reception distance difference is the fifth term. Therefore, the propagation correction in Expression (6) only needs to be performed for components for which different values are used for the transmission / reception parameters in CH_0 and CH_k.

  In this way, the propagation loss is estimated by correcting the propagation loss error between the first frequency band, which is the estimation target of the first radio wave arrival status, and the frequency band where spectrum sensing is actually performed, from the propagation model, and correcting it. The accuracy and accuracy of determining whether frequency sharing is possible can be further improved.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. FIG. 14 is an explanatory diagram illustrating a relationship between a primary system and a secondary system (cognitive radio system) in the second embodiment. As shown in FIG. 14, the cognitive radio system in the present embodiment includes a secondary base station 300 instead of the secondary base station 200, and includes a secondary terminal 310 instead of the secondary terminal 210. The base station 300 and the secondary terminal 310 according to the present embodiment simultaneously receive signals of a plurality of channels, and the sensor unit determines whether the frequency sharing is possible using the plurality of signals and estimates a propagation loss.

  FIG. 15 is a block diagram illustrating a configuration example of the secondary base station 300. The secondary base station 300 illustrated in FIG. 15 has M RF analog units 3030 (RF analog units 3030-1 to 3030-M) as compared to the secondary base station 200 in the first embodiment illustrated in FIG. The frequency band selection unit 3042 selects M frequency bands, and the sensor unit 3050 receives an M channel signal. Hereinafter, description of the same components as those of the first embodiment will be omitted.

  The RF analog units 3030-1 to 3030 -M receive different center frequencies and frequency bandwidths from the frequency band selection unit 3042. Each RF analog unit 3030 receives the RF signal sent from the low noise amplifier 3031 as an input, converts the signal of the center frequency and bandwidth specified by the frequency band selection unit 3042 into a baseband signal, and performs sampling. Generate a digital signal. When the digital signal generated by each RF analog unit 3030 is a signal transmitted from another secondary radio device, it is demodulated / decoded by the reception demodulator 3020, and is a signal for spectrum sensing. Is sent to the sensor unit 3050.

  The frequency band selection unit 3042 determines a channel for determining whether the secondary base station 300 and the secondary terminal 320 can share the frequency based on the frequency usage information acquired by the frequency usage information acquisition unit 3041. Among these, a channel for determining whether or not the other secondary radio device (here, the secondary terminal 320) can be shared is sent to the transmission control unit 3070 as sensing scheduling information.

  Next, a band determination method in the frequency band selection unit 3042 will be described. Here, let CH_0 be the first channel to be estimated for radio wave arrival status in the secondary base station 300. The frequency band selection unit 3042 selects CH_0 and another channel used by the primary transmitter using CH_0 and a channel used by the primary transmitter in a position close to the primary transmitter using CH_0. Select it. The method for selecting the adjacent primary transmitters is the same as in the first embodiment.

  Further, the frequency band selection unit 3042 sends frequency use information regarding CH_0 to the allowable transmission power setting unit 3060.

Hereinafter, a channel selection method in the frequency selection unit 3042 will be described with reference to the drawings. FIG. 16 is an explanatory diagram illustrating an example of channel selection in the frequency selection unit 3042. In FIG. 16A is an explanatory diagram illustrating an example of channel selection in relation to the equivalent isotropic radiant power, and FIG. 16B is an explanatory diagram illustrating an example of channel selection in a geographical relationship. . In this example, it is assumed that the CH_0, CH_1, and CH_2 signals are transmitted from the primary transmitter 100 from the frequency use information. At this time, when the equivalent isotropic radiation power P _{1 of} CH — ₀ <the equivalent isotropic radiation power P _{2 of} CH — ₁ <the equivalent isotropic radiation power P ₃ of CH — ₂ , for example, as shown in FIG. In order to determine whether or not the frequency sharing of CH_0 is possible with CH_0 having smaller power as the first radio wave arrival state estimation target (that is, the first frequency band), the first, second or third frequency band Of these, CH_2 and CH_1 may be selected in descending order of the equivalent isotropic radiant power. Note that the number of channels to be selected may be within M, which is the total number of RF analog units 3030.

  Next, the configuration of the sensor unit 3050 will be described with reference to FIG. As shown in FIG. 17, the sensor unit 3050 of the present embodiment includes M power detection units 3051 (power detection units 3051-1 to 3051 -M), a propagation loss estimation unit 3052, and a desired channel received power estimation unit. 3053 and a determination unit 3054. The CH_1 to CH_M baseband signals sent from the RF analog units 3030 are input to the power detection units 3051-1 to 3051 -M, respectively. Each power detection unit 3051 performs processing according to Expression (1) as in the first embodiment. That is, an average of the square value of each sample of the baseband signal is taken and the noise power is subtracted to obtain the estimated received power value of the primary signal in CH_1 to CH_M. The obtained received power estimation values of the M primary signals are sent to the propagation loss estimation unit 3052.

The propagation loss estimation unit 3052 uses the received power estimation value of the primary signal in CH_1 to CH_M sent from each received power estimation unit 3051 and the equivalent isotropic radiation power in CH_1 to CH_M sent from the frequency band selection unit 3042. Thus, the propagation loss in CH_0 is estimated. To estimate the propagation loss, first, the received power estimation value D _m (m = 1, 2,..., M) of each primary signal is used as the equivalent isotropic radiation power P _m (m = 1, 2,..., M). ) Is used to estimate the propagation gain (reciprocal of propagation loss) in each frequency band, and after weighted synthesis of these propagation gains, the value further divided by the gain G _amp of the low noise amplifier 3031 is further propagated at CH_0. and the estimated value _{G 0.} That is, the arithmetic processing according to the following equation (7) is performed.

Here, w _m (m = 1, 2,..., M) is a weight for obtaining the propagation gain in CH — 0 and the sum is 1. When combining the propagation gain in each frequency band as equal gain, w _m = 1 / M. The weight calculated so as to approximately minimize the mean square error between the propagation gain estimation value and the true propagation gain in Expression (7) is given by Expression (8) below.

The reciprocal of the propagation gain G _{0 in} CH — ₀ generated by weighting combining using these weights w _m is defined as propagation loss L ₀ (= 1 / G ₀ ).

In the above propagation loss estimation CH_0, equate propagation characteristics between CH_0 and CH_1～CH_M, was determined path loss _{L 0,} between channels using Equation (5) in the first embodiment It is also possible to correct the propagation loss difference.

  Further, assuming that each power detection unit 3051 can use an estimated value of noise power, the received power of the primary signal is calculated by subtracting the noise power from the received power, and the received power of the primary signal is used by the propagation loss estimation unit 3052. However, if there are channels with different equivalent isotropic radiant powers in CH_1 to CH_M, the propagation loss can be estimated using the following method that does not require noise power in advance.

  First, the CH_1 to CH_M baseband signals sent from the RF analog units 3031 are input to the power detection units 3051, respectively. Unlike the operation in the first embodiment (the operation described in Expression (9)), each power detection unit 3051 calculates the received power of the entire channel, not the received power of the primary signal. That is, an average is taken for the square value of each sample of the baseband signal. For example, the arithmetic processing according to the following equation (9) is performed.

The obtained M received power estimation values are sent to propagation loss estimation section 3052. The propagation loss estimation unit 3052 uses the received power in each channel of CH_1 to CH_M sent from each power detection unit 3051 and the equivalent isotropic radiant power in CH_1 to CH_M sent from the frequency band selection unit 3042. Estimate the propagation loss in CH_0. For estimating the propagation loss, the received power estimation value D ′ _m (m = 1, 2,..., M) of each channel is normalized with the equivalent isotropic radiation power, and the weighted and synthesized value is used as the propagation gain of CH_0. The estimated value G ′ is ₀ . For example, the arithmetic processing according to the following expression (10) is performed.

However, the weight w _m (m = 1, 2,..., M) in the equation (10) is different from the equation (8), and the noise power component in the estimated value G ′ ₀ of the combined propagation gain is canceled. Further, the weight is a sum of 1 calculated so as to approximately minimize the mean square error between the propagation gain estimated value and the true propagation gain. That is, the weight of the following formula (11) is used.

  Here, when there are channels with different equivalent isotropic radiant powers, that is, there are channels with different equivalent isotropic radiant powers in one channel CH_m and another channel CH_m ′ (m and m ′ are different positive integers). In this case, since the denominator of Expression (11) does not become 0, the weight of Expression (12) exists. In addition, in order to perform propagation loss estimation that does not require a noise power estimation value in advance using Equation (10) and Equation (11), the equivalent isotropic radiant power differs from that of other channels in the previous frequency band selection unit 3042. You may select the channel which performs spectrum sensing so that a channel may be included.

The reciprocal of the propagation gain G ′ ₀ at CH — ₀ generated by weighted combining using the weight w _m of Equation (11) is defined as a propagation loss L ₀ (= 1 / G ′ ₀ ).

  The propagation loss estimation unit 3052 calculates the propagation loss at CH_0 using Equation (7) and Equation (10), and sends it to the desired channel received power estimation unit 3053 and the allowable transmission power setting unit 3054.

The desired channel received power estimation unit 3053 uses the propagation loss sent from the propagation loss estimation unit 3052 and the equivalent isotropic radiant power P _{0 of} CH_0 sent from the frequency band selection unit 3042, and the following equation (12) To estimate the received power P _{rx, 0} of CH_0.

The CH_0 received power estimation value P _{rx, 0} obtained here is sent to the determination unit 3056. The determination unit 3056 operates in the same manner as the determination unit 2054 in the first embodiment, and sends binary information, which is a determination result of frequency sharing availability, to the allowable transmission power setting unit 3060.

  In the above description, the configuration of the secondary base station 300 has been described. Similarly, the secondary terminal 320 under the control of the secondary base station 300 also receives signals of a plurality of channels at the same time, and uses the plurality of signals at the sensor unit. It is possible to determine whether frequency sharing is possible and to estimate propagation loss. In such a case, also in the secondary terminal 320, M RF analog units 3130 (RF analog units 3130-1 to 3130-M) are provided, and the frequency band selection unit 3142 selects M frequency bands. Thus, the sensor unit 3150 may receive an M channel signal.

  As described above, according to the present embodiment, a propagation gain in each frequency band is calculated using a plurality of frequency bands having a large equivalent isotropic radiant power, and a value obtained by weighting and combining the propagation gains is used for frequency sharing. The propagation loss is estimated by taking the propagation gain of CH_0 to be determined and taking the reciprocal of the propagation gain. Therefore, the number of received signal samples that can be used for estimating the propagation loss can be increased as compared with the case where the propagation loss is estimated using only the first frequency band. As a result, it is possible to improve the averaging effect of the noise included in the received signal in the process of estimating the propagation loss. In addition, when the transmission antennas in the primary transmitter using each frequency band are separated from each other, each primary signal is subjected to fading independent from each other and received by the cognitive radio base station or the cognitive radio terminal. An effect is obtained. Therefore, the estimation accuracy of the propagation loss is improved, and the determination accuracy of frequency sharing availability is improved by using a more accurate propagation loss estimation value. In addition, when performing propagation loss estimation and determination as to whether or not frequency sharing is possible, it is possible to shorten the spectrum sensing time required to satisfy the predetermined accuracy defined by the system requirements and the like.

  Further, by selecting in advance a frequency band having a different equivalent isotropic radiant power in the frequency band selection unit, it is possible to estimate the propagation loss without requiring an estimated value of the noise power. As a result, the propagation loss can be estimated without being affected by the estimation error included in the noise power estimation value, and therefore, the propagation loss can be estimated with higher accuracy than when performing the propagation loss estimation using the noise power estimation value including the error. Loss estimation becomes possible.

Embodiment 3. FIG.
Next, a third embodiment of the present invention will be described. FIG. 18 is an explanatory diagram showing the relationship between the primary system and the secondary system (cognitive radio system) in the present embodiment. As shown in FIG. 18, the present embodiment assumes an environment in which there are different primary transmitters (in this example, primary transmitters 100 and 101) that share and use a channel for determining whether or not frequency sharing is possible. . FIG. 18 illustrates a primary transmitter 100 and a primary transmitter 101 that use the same frequency band (CH_0), and a secondary base station 400 that determines whether or not frequency sharing of the frequency band is possible. Further, the primary transmitter 100 and the primary transmitter 101 have a reference power area 50 and a reference power area 60, respectively, and the secondary base station 400 has a secondary system service area 30.

  In the secondary base station 400 or the secondary terminal 410 according to the present embodiment, different primary transmitters (in this example, primary transmitters 100 and 101) that share and use a channel for determining whether or not the frequency can be shared are each primary. A different channel not shared by the transmitter is selected and used for spectrum sensing.

  For example, as shown in FIG. 18, in the secondary base station 400, when the secondary system service area 30 is outside the reference power area of the primary system, the primary system and the frequency band CH_0 may be shared. However, when the secondary base station 400 receives a signal on CH_0 and determines propagation loss estimation or frequency sharing availability, the secondary base station 400 uses the combined signals of the primary transmitters 100 and 101 that share and use CH_0. Since it is received, the propagation loss estimated value becomes smaller than the original value. That is, the propagation gain estimation value becomes large. Alternatively, the determination result of whether or not the frequency sharing of CH_0 that is originally sharable is impossible. That is, the false alarm probability increases.

  In order to solve this problem, another channel CH_1 used in the primary transmitter 100 and another channel CH_2 used in the primary transmitter 101 are used to estimate propagation loss and determine whether frequency sharing is possible.

  FIG. 19 is a block diagram illustrating a configuration example of the secondary base station 400. The secondary base station 400 shown in FIG. 19 is different from the secondary base station 300 in the second embodiment shown in FIG. 15 in that a multiple transmitter frequency band selection unit 4042 is provided instead of the frequency band selection unit 3042. Further, the method for identifying the propagation loss estimated value in the sensor unit 4050 and the method for determining whether the frequency can be shared are different. Hereinafter, description of the same components as those in the second embodiment will be omitted.

  Based on the frequency usage information acquired by the frequency usage information acquisition unit 4041, the multi-transmitter frequency band selection unit 4042 determines a channel to be estimated for radio wave arrival status at the secondary base station 400 and the secondary terminal. Among these, a channel for determining whether or not the secondary terminal can be shared is sent to the transmission control unit 2070 as sensing scheduling information.

  Next, a band determination method in the multiple transmitter frequency band selection unit 4042 will be described. First, a primary transmitter that uses a channel CH_0 that is a target for estimation of radio wave arrival status is first obtained from frequency use information. Next, it is shared by primary transmitters within a predetermined distance among other channels used by the requested primary transmitter or another primary transmitter located in close proximity to the primary transmitter. Choose no channel. Here, the predetermined distance is determined in advance as a range in which a received signal affects the accuracy of propagation estimation.

  For example, when CH_0 is shared and used as shown in FIG. 18, first, primary transmitters 100 and 101 using CH_0 are obtained. Next, among other channels used by the primary transmitter 100 and a primary transmitter close to the primary transmitter 100 (not shown in FIG. 18), a channel not used by the primary transmitter 101 (for example, CH_1). ) Similarly, among the other channels used by the primary transmitter 101 and the primary transmitter close to the primary transmitter 101 (not shown in FIG. 18), channels that are not used by the primary transmitter 100 (for example, CH_2) is obtained.

  At this time, if there are a plurality of candidate channels, the frequency band with the maximum equivalent isotropic radiant power may be selected as in the first embodiment, or the same as in the second embodiment. A plurality of channels having a large equivalent isotropic radiation power may be selected.

  Next, the center frequency and bandwidth of the selected channels CH_1 and CH_2 are sent to the RF analog units 4031 to 4033. Also, the equivalent isotropic radiant power used in CH_1 and CH_2 and the equivalent isotropic radiant power of channel CH_0, which is a determination target for frequency sharing, are sent to sensor unit 4050, where CH_0 estimation of propagation loss and CH_0 received power are sent. Used to estimate Further, the frequency use information regarding CH_0 is sent to the allowable transmission power setting unit 4060.

  The sensor unit 4050 calculates the reception power of the primary signal for each of the channels CH_1 and CH_2 determined by the multi-transmitter frequency band selection unit 4042, as in the first embodiment, and propagates from the reception power. Estimate loss. Next, the sensor unit 4050 estimates the received power of the primary signal in CH_0 using the propagation loss estimated value obtained in channel CH_1 and the equivalent isotropic radiated power in CH_0, and similarly obtained in channel CH_2. The received power of the primary signal at CH_0 is estimated using the estimated propagation loss value and the equivalent isotropic radiant power at CH_0. The reception power of CH_0 estimated using the reception signals of channels CH_1 and CH_2 is compared with a predetermined threshold value, and a determination is made as to whether or not frequency sharing is possible on CH_0. Next, when the determination result of whether or not the frequency sharing corresponding to both the channels CH_1 and CH_2 is sharable, a final determination is made that the sharability is possible, and otherwise the sharability is impossible. The propagation loss estimation value and the final determination result regarding whether or not frequency sharing is possible are sent to the transmission control unit 4060.

Hereinafter, the method for selecting this channel will be described with reference to the drawings. FIG. 20 is an explanatory diagram illustrating an example of channel selection in the frequency selection unit 4042. FIG. 20 shows an example in which channel selection is performed in relation to equivalent isotropic radiant power. In this example, it is assumed that CH_0 and CH_1 signals are transmitted from the primary transmitter 100 from the frequency use information. Further, it is assumed that the signals of CH_0 and CH_2 are transmitted from the primary transmitter 101. At this time, the relationship between the equivalent isotropically radiated power _{P 2} of the equivalent isotropic radiated power _{P 1} and CH_1 of CH_0 in primary transmitter _100, a P 1 _{<P 2.} The relationship between the equivalent isotropic radiated power _{P 3} of EIRP _{P 1} and CH_2 of CH_0 in primary transmitter 101 _is a P 1 _{<P 3.} In such a case, even if ch0 having a smaller equivalent isotropic radiated power can be used as a shared frequency band in each primary transmitter, the secondary base station 400 receives a signal in ch0 and estimates propagation loss or When determining whether or not frequency sharing is possible, the combined signal of the primary transmitters 100 and 101 that use ch0 in common is received, and the propagation loss estimation value becomes smaller than the original value. That is, the propagation gain estimation value becomes large. For this reason, in this embodiment, the channel CH_1 or / and CH_2 that is not shared is selected as a channel to be sensed.

  Next, another operation example of the above-described frequency band selection method and frequency sharing availability determination method will be described. That is, the above-described multiple transmitter frequency band selection unit 4042 and sensor unit 4050 may operate as follows.

  The multi-transmitter frequency band selection unit 4042 determines a channel to be estimated for radio wave arrival status based on the frequency usage information acquired by the frequency usage information acquisition unit 4041. Among these, information regarding a channel for determining whether or not other secondary wireless devices can be shared is sent to the transmission control unit 2070 as sensing scheduling information.

In this example, the channel CH_0 shared and used here is also included in the selection candidates. FIG. 21 is an explanatory diagram illustrating another example of channel selection by the frequency selection unit 4042. In FIG. For example, in the example illustrated in FIG. 21, it is assumed that the CH_0 and CH_1 signals are transmitted from the primary transmitter 100 from the frequency use information. Further, it is assumed that the signal of CH_2 is transmitted from the primary transmitter 101. At this time, the relationship between the equivalent isotropically radiated power _{P 2} of the equivalent isotropic radiated power _{P 1} and CH_1 of CH_0 in primary transmitter _100, and was P 1 _{<P 2.} In such a situation, when CH_0 having a low equivalent isotropic radiant power is set as the first first radio wave arrival state estimation target (that is, the first frequency band), the first or second frequency band Of these, shared CH_0 and unshared CH_1 may be selected as selection candidates.

  The sensor unit 4050 receives the primary signal in the same manner as in the first embodiment for each of the channel CH_1 determined by the multi-transmitter frequency band selecting unit 4042 and the channel CH_0 that is the target of frequency sharing determination. Calculate power. Next, the propagation loss between the primary transmitter 101 and the secondary base station 400 is estimated using the received power of CH_1 and the equivalent isotropic radiant power of CH_1. The sensor unit 4050 uses the propagation loss estimation value obtained in this way and the equivalent isotropic radiant power in CH_0 of the primary transmitter 101 to use the secondary base station 400 of the primary signal transmitted on CH_0 of the primary transmitter 101. The received power at is estimated.

  Further, the sensor unit 4050 subtracts the received power estimated value of the primary signal transmitted by CH_0 of the primary transmitter 101 from the received power of the primary signal estimated using the channel CH_0, so that CH_0 of the primary transmitter 100 is obtained. The received power of the primary signal transmitted in is estimated. The received power of the primary signal transmitted in CH_0 of the primary transmitter 101 and the primary transmitter 100 obtained in this way is compared with a predetermined threshold value, and whether or not frequency sharing is possible is determined for each.

  Next, when the determination result of the frequency sharing possibility corresponding to the primary transmitter 101 and the primary transmitter 100 is sharable together, a final determination is made that the sharability is possible, and otherwise the sharability is not possible. When propagation loss from the primary transmitter 100 to the secondary base station 400 is necessary, it can be calculated by using the calculated received power of the primary transmitter 100 and the equivalent isotropic radiant power of the primary transmitter 100. The propagation loss estimation value and the final determination result regarding whether or not frequency sharing is possible are sent to the transmission control unit 4060.

  As described above, according to the present embodiment, radio signals are transmitted from a plurality of transmitters and combined and received at a cognitive radio base station and a cognitive radio terminal in the first frequency band that is the target of frequency sharing determination. In this case, erroneous reception power estimation due to the combined signal can be avoided by estimating reception power in the first frequency band by propagation loss estimation using the second frequency band. That is, the problem that the propagation loss estimation value becomes smaller than the original value due to the reception of the composite signal, that is, the problem that the propagation gain estimation value becomes large, or the CH_0 frequency sharing possibility that is originally sharable. It is possible to solve the problem that the determination result cannot be shared in frequency, that is, the problem that the false alarm probability increases. Therefore, it is possible to improve the estimation accuracy of propagation loss and the accuracy of determining whether or not frequency sharing is possible.

  Although the sensor unit in the cognitive radio base station or the cognitive radio terminal in all the embodiments of the present invention receives the digital baseband signal output from the RF analog unit, it outputs from the bandpass filter of the RF analog unit. The processed RF signal may be input to the sensor unit. In this case, the sensor unit performs power detection with respect to the RF signal and other techniques using the feature quantity of the primary signal, thereby determining whether the frequency can be shared and estimating the propagation loss.

  In the above-described embodiment, the configuration example of the sensor unit using power detection is shown as the spectrum sensing method. However, for example, the sensor unit may use a technique using the feature amount of the primary signal. FIG. 22 is an explanatory diagram illustrating another configuration example of the sensor unit. A sensor unit 5050 shown in FIG. 22 is a sensor unit that uses a spectrum sensing technique that utilizes the periodic steadiness of a primary signal. Cyclic stationary represents the property that the autocorrelation function of the signal is a periodic function. This property is seen in an OFDM (Orthogonal Frequency Division Multiplexing) signal or the like with a cyclic prefix inserted, and a periodic stationary signal has a periodic peak in the periodic autocorrelation value shown in the following equation (13). is there.

  Here, α is called a cyclic frequency. Also, y (n) is the received signal sample value, N is the number of samples used for averaging, Δ is the sampling time, and τ is the number of delayed samples for calculating the periodic autocorrelation value. Note that * represents a complex conjugate. The optimum values for the cyclic frequency and the number of delay samples differ depending on the signal format. In the case of an OFDM signal, the reciprocal of the OFDM symbol length including the cyclic prefix or an integer multiple of the reciprocal may be used as the cyclic frequency, and the number of samples corresponding to the effective symbol length of OFDM may be used as the number of delayed samples.

  The sensor unit 5050 shown in FIG. 22 performs propagation loss estimation using the above periodic continuity. This sensor unit 5050 is an example of a sensor unit serving as a substitute for the sensor unit 2050 included in the secondary base station 200 in the first embodiment. Below, description is abbreviate | omitted about the common structure of the sensor part 5050 and the sensor part 2050 of the secondary base station 200. FIG.

  In the sensor unit 5050, first, a baseband signal is input to the periodic autocorrelation generation unit 5051. The periodic autocorrelation generation unit 5051 generates a periodic autocorrelation value using the above equation (13). Further, the periodic autocorrelation generation unit 5051 generates a test statistic for the chi-square test using the generated periodic autocorrelation value. Here, this test statistic is characterized by a value that depends only on the number of samples used for averaging and the received SNR. The generated test statistic is input to the propagation loss estimation unit 5052.

  Propagation loss estimation unit 5052 receives test statistics from periodic autocorrelation generation unit 5051. The propagation loss estimation unit 5052 holds in advance a table of received SNR values corresponding to the test statistic and the number of averaged samples. Next, the received SNR is obtained by referring to the table from the input value of the test statistic and the averaged number of samples used in the periodic autocorrelation generation unit 5051. The received power of the primary signal is obtained by calculating the product of the received SNR and the noise power estimate obtained here (sum of the noise power estimate when the unit of the received SNR is dB). Further, using this primary signal received power and the equivalent isotropic radiated power of the received channel, the propagation loss is estimated in the same manner as in the above-described equation (2). The propagation loss estimation value is input to desired channel received power estimation section 2053. The subsequent processing is the same as the processing of the sensor unit 2050.

  In addition, although the example in the case where the secondary base station 200 in 1st Embodiment is provided was shown above, even if it is the case where the secondary base station or secondary terminal in other embodiment is provided, it respond | corresponds by the same structure. Is possible. That is, a periodic autocorrelation value generation unit may be provided instead of the power detection unit, and the propagation loss estimation unit may estimate the propagation loss based on the test statistic input from the periodic autocorrelation generation unit 5051.

  In each of the above embodiments, the example of performing base station communication between the secondary base station and the secondary terminal has been shown as the communication form of the cognitive radio system. However, the ad hoc communication between the secondary radios is not the configuration of the base station and the terminal. It is also applicable to. In such a case, it is only necessary to set the allowable transmission power for each radio device by providing the frequency use information acquisition unit and the allowable transmission power setting unit that the secondary base station has.

  Note that the cognitive radio base station in all the embodiments of the present invention acquires the frequency usage information from the geographic database using the frequency usage information acquisition means. However, if the frequency usage information can be acquired, the geographic database is unnecessary. is there. For example, the cognitive radio base station or the cognitive radio terminal may acquire the frequency use information using a common control channel that broadcasts the frequency use information to the cognitive radio base station or the cognitive radio terminal. Alternatively, frequency use information may be stored in advance in a memory provided in the cognitive radio terminal.

  Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the claims of the present invention.

  The outline of the present invention will be described below. FIG. 23 is a block diagram showing an outline of the present invention. As shown in FIG. 23, the wireless device 1 according to the present invention includes a frequency band selection unit 11 and a sensor unit 12.

  The frequency band selection unit 11 (for example, the frequency band selection units 2042, 2142, 3043, and 3142, the frequency band selection unit 4042 for multiple transmitters) is the target of estimating the radio wave arrival status among the frequency bands used in the wireless communication system. A second frequency band that is used for transmission by the first transmitter that transmits in the first frequency band and is different from the first frequency band, or When there is at least one third frequency band different from the first frequency band that is used for transmission by the second transmitter located in the vicinity of the first transmitter, Alternatively, it is possible to select one or more frequency bands including at least one of the third frequency bands as selection candidate bands, and to select a frequency band for detecting a radio signal from the selection candidate bands.

  The sensor unit 12 (for example, the sensor units 2050, 2150, 3050, 4050, 5050) detects a radio signal in the frequency band selected by the frequency band selection unit 11 as an example.

  The sensor unit 12 includes frequency use information that is information indicating a use status of each frequency band including a detection result of the radio signal in the selected frequency band and a frequency band that is a first frequency band and a selection candidate band. A propagation loss estimation unit (for example, propagation loss estimation unit 2052, 2152, 3052, 4052, 5052) for estimating the propagation loss of a radio signal transmitted from one transmitter in the first frequency band. May be.

  The frequency band selection unit 11 may select a frequency band for detecting a radio signal from the selection candidate bands based on the magnitude of the equivalent isotropic radiant power of the radio signal transmitted in each frequency band.

  The frequency band selection unit 11 may select a predetermined number of frequency bands as the frequency band for detecting the radio signal, from among the selection candidate bands that have a large equivalent isotropic radiant power of the transmitted radio signal.

  The frequency band selection unit 11 may select a plurality of second or third frequency bands that are not shared by transmitters within a predetermined distance from the selection candidate bands as frequency bands for detecting a radio signal. Good.

  The frequency band selection unit 11 wirelessly transmits the first frequency band and one or more second or third frequency bands included in the selection candidate band and not shared by transmitters within a predetermined distance. You may select as a frequency band which detects a signal.

  The propagation loss estimation unit may correct the estimated propagation estimation value by calculating, from the propagation model, a difference in propagation loss due to radio wave propagation between the frequency band selected by the frequency band selection unit and the first frequency band. .

  The propagation loss estimation unit estimates the propagation gain for each frequency band using the detection result of the radio signal in the selected predetermined number of frequency bands, and calculates the propagation gain from the propagation gain estimation value obtained by weighting and combining each propagation gain with a predetermined weight. Propagation loss may be estimated.

  The sensor unit 12 further includes a received power estimation unit (for example, a desired channel) that estimates received power in the first frequency band based on the propagation loss estimation value estimated by the propagation loss estimation unit and the frequency usage information. (Reception power estimation unit 2053, 2153, 3053, 4053, 5053) and determination of determining whether the first frequency band can be shared by comparing the reception power estimation value estimated by the reception power estimation unit with a predetermined threshold (For example, determination units 2054, 2154, 3054, 4054, and 5054) may be included.

  In addition to the above-described configuration, the wireless communication system according to the present invention is configured to transmit frequency usage information, which is information indicating the usage status of each frequency band including the first frequency band and the frequency band to be selected, to a predetermined frequency band. An informing device for informing using the control channel is provided.

  The spectrum sensing method according to the present invention is a spectrum sensing method in a wireless device, and performs transmission in a first frequency band with respect to a first frequency band that is a target of radio wave arrival status estimation. A second frequency band that is used for transmission by the transmitter and is different from the first frequency band, or a frequency band that is used for transmission by the second transmitter located in the vicinity of the first transmitter. And when at least one of the third frequency bands different from the first frequency band exists, one or more frequency bands including at least one of the second or third frequency bands are selected candidate bands, A frequency band for detecting a radio signal is selected from the selection candidate bands, and a radio signal in the selected frequency band is detected.

  In the spectrum sensing method, the frequency use is information indicating the use status of each frequency band including the detection result of the radio signal in the selected frequency band and the first frequency band and the frequency band to be the selection candidate band. Based on the information, the propagation loss of a radio signal transmitted from one transmitter in the first frequency band may be estimated.

  Further, the radio control program according to the present invention is a cognitive radio control program applied to a radio, and has a first frequency with respect to a first frequency band to be estimated for radio wave arrival status on a computer. A second transmission located in the vicinity of the first frequency band, or a second frequency band different from the first frequency band that is used for transmission by the first transmitter that performs transmission in the band One or more including at least one of the second or third frequency band when there is at least one third frequency band different from the first frequency band that is used for transmission in the machine The selection frequency band is used as the selection candidate band, and the process of selecting the frequency band for detecting the radio signal from the selection candidate band and the process of detecting the radio signal in the selected frequency band are executed. And characterized in that.

  The wireless device control program further includes information indicating the detection result of the wireless signal in the selected frequency band and the usage status of each frequency band including the first frequency band and the frequency band that is the selection candidate band. Based on the frequency usage information, the process of estimating the propagation loss of the radio signal transmitted from one transmitter in the first frequency band may be executed.

  The frequency usage information notification device according to the present invention is frequency usage information that is information indicating a usage status of a frequency band used in a radio communication system, and includes at least a center frequency of the frequency band, a frequency bandwidth, and radio communication. Frequency including all or any of the position information of the transmitter of the system, the transmission antenna height information of the wireless communication system, the transmission power of the wireless communication system, the transmission antenna gain of the wireless communication system, the information indicating the propagation model, and the standard reception antenna height The usage information is broadcast using a predetermined control channel.

  The frequency usage information notification device is information indicating the usage status of a frequency band used in a wireless communication system that uses a frequency band that is a target of estimation of the radio wave arrival status in order to estimate the radio wave arrival status. May be broadcast using a predetermined control channel.

  The frequency utilization information notification device is a frequency band used for transmission by a first transmitter that performs transmission in the first frequency band with respect to the first frequency band that is a target of radio wave arrival status estimation. A second frequency band different from the one frequency band, or a third frequency band used for transmission by the second transmitter located in the vicinity of the first transmitter and different from the first frequency band. When at least one of the frequency bands is present, one or more frequency bands including at least one of the second or third frequency bands is selected as a selection candidate band, and a frequency band for detecting a radio signal from the selection candidate band The radio wave arrival situation with a radio terminal including a radio device having a frequency band selection unit capable of selecting a radio frequency sensor and a sensor unit for detecting a radio signal in the frequency band selected by the frequency band selection unit The frequency usage information is information indicating usage of the frequency band used in the wireless communication system using a frequency band of estimation target, may be notified by using a predetermined control channel.

  Further, the frequency usage information notification program according to the present invention is a frequency usage information which is information indicating a usage status of a frequency band used in a wireless communication system, and includes at least a center frequency and a frequency bandwidth of the frequency band. Transmitter position information of radio communication system, transmit antenna height information of radio communication system, transmit power of radio communication system, transmit antenna gain of radio communication system, information indicating propagation model, and / or standard receive antenna height In this case, the frequency utilization information including is broadcasted using a predetermined control channel.

  (Additional remark 1) In addition, in a cognitive radio, the frequency band selection part 11 may select the frequency band which detects a radio signal by making several frequency band including a 1st frequency band into a selection candidate band.

  (Additional remark 2) Moreover, the frequency band selection part 11 may select the frequency band which is the maximum of equivalent isotropic radiant power among selection candidate bands.

  (Additional remark 3) Moreover, the determination part contained in the sensor part 12 may determine whether frequency sharing is possible for every transmitter of the radio | wireless communications system which shares and uses a 1st frequency band.

  (Additional remark 4) Moreover, the determination part contained in the sensor part 12 is shared by the transmitter which exists in the 2nd or 3rd frequency band within the predetermined distance from the received power in the 1st frequency band. By subtracting the received power in a non-frequency band, the received power at the first transmitter may be calculated to determine whether the frequency can be shared.

  (Additional remark 5) Moreover, the sensor part 12 contains the electric power detection part (for example, electric power detection part 2051,3051-1 to 3051-M) which performs electric power detection of a received signal, and a propagation loss part is detected by electric power detection. The propagation loss may be estimated based on the power value of the received signal.

  (Additional remark 6) Moreover, the sensor part 12 contains the transmission signal feature-value detection part (for example, period autocorrelation value generation part 5051) which detects the feature-value of a transmission signal, and a propagation loss part is a transmission signal feature-value detection part. The propagation loss may be estimated based on the feature amount of the transmission signal detected by the above.

  (Supplementary note 7) Further, the frequency utilization information includes the center frequency of each frequency band, the frequency bandwidth, the latitude and longitude information of the transmitter of the wireless communication system, the transmission antenna height information of the wireless communication system, the transmission power of the wireless communication system, and the wireless The transmission antenna gain of the communication system, the information indicating the propagation model, and the standard reception antenna height may be all or any one of them.

  (Additional remark 8) Moreover, the frequency utilization information acquisition part (for example, frequency utilization information acquisition part 2041,3041,4041) which acquires frequency utilization information via a communication network from the frequency utilization information storage device holding frequency utilization information is provided. You may have.

  (Additional remark 9) Moreover, you may acquire what is alert | reported by a common control channel as frequency utilization information as a radio signal.

  (Additional remark 10) Moreover, frequency utilization information may be previously memorize | stored in the memory | storage part of the radio | wireless machine.

  (Additional remark 11) Moreover, in a radio | wireless communications system, a radio base station may alert | report some or all of frequency utilization information to the radio | wireless terminal under control as control information.

  INDUSTRIAL APPLICABILITY The present invention can be suitably applied to an application for determining whether or not a frequency band can be used without affecting other wireless communication systems when using a frequency shared by a plurality of wireless communication systems. .

DESCRIPTION OF SYMBOLS 1 Radio | wireless machine 11 Frequency band selection part 12 Sensor part 10 Primary system service area 30 Secondary system service area 50, 60 Reference power area 100, 101 Primary transmitter 110 Primary receiver 150 Geographic database 120 Secondary radio | wireless machine 200, 300, 400 Secondary Base station 210 Secondary terminal 2001, 2011, 3001, 4001 Antenna 2002, 2102, 3002, 4002 Transmission / reception separation unit 2010, 2110, 3010, 4010 Transmitter modulator 2020, 2120, 3020, 4020 Receiver demodulator 2031, 1311, 3035, 4035 Low noise amplifier 2030, 2130, 3030, 4030 RF analog section 2032, 2132 Band pass filter 2033, 2133 MIKI -2034, 2134 Local oscillator 2035, 2135 Low pass filter 2036, 2136 Analog to digital converter 2041, 3041, 4041, 4041 Frequency utilization information acquisition unit 2042, 2142, 3042, 4042 Frequency band selection unit 2050, 2150, 3050, 4050 , 5050 Sensor unit 2051, 3051 Power detection unit 2052, 3052, 5052 Propagation loss estimation unit 2053, 3053, 5052 Desired channel received power estimation unit 2054, 3054, 5052 Determination unit 2060, 3060, 4060 Allowable transmission power setting unit 2070, 2170 , 3070, 4070 Transmission control unit 5051 Periodic autocorrelation value generation unit

Claims (17)

For the first frequency band to be estimated for radio wave arrival status, the first frequency band used for transmission in the first transmitter that performs transmission in the first frequency band, and the first frequency band and Is a different second frequency band, or a third frequency band that is used for transmission by a second transmitter located in the vicinity of the first transmitter and is different from the first frequency band One or more frequency bands including at least one of the second or third frequency bands as selection candidate bands, and a frequency band for detecting a radio signal from the selection candidate bands A frequency band selector that can be selected; and
A sensor unit for detecting a radio signal in the frequency band selected by the frequency band selection unit ,
The frequency band selection unit selects a frequency band for detecting a radio signal based on the magnitude of the equivalent isotropic radiant power of the radio signal transmitted in each frequency band from the selection candidate bands. Radio to do. The sensor part
Based on the detection result of the radio signal in the selected frequency band and the frequency usage information that is information indicating the usage status of each frequency band including the first frequency band and the frequency band that is the selection candidate band. The radio device according to claim 1, further comprising a propagation loss estimation unit that estimates a propagation loss of a radio signal transmitted from one transmitter in one frequency band. Frequency band selection unit, among the selection candidates band, a predetermined number of frequency bands from those EIRP large of a radio signal transmitted, according to claim 1 or claim selecting a frequency band to detect a radio signal Item 3. The wireless device according to Item 2 . The frequency band selection unit selects a plurality of second or third frequency bands that are not shared by transmitters within a predetermined distance from the selection candidate bands as frequency bands for detecting a radio signal. The wireless device according to any one of claims 1 to 3 . The frequency band selection unit transmits a first frequency band and one or more second or third frequency bands that are included in the selection candidate band and are not shared by transmitters within a predetermined distance to a radio signal. The radio device according to any one of claims 1 to 4 , wherein the radio device is selected as a frequency band for detecting. The propagation loss estimation unit calculates a difference in propagation loss due to radio wave propagation between the frequency band selected by the frequency band selection unit and the first frequency band from the propagation model, and corrects the estimated propagation estimation value. The radio described in 1. The propagation loss estimation unit estimates the propagation gain for each frequency band using the detection result of the radio signal in the selected predetermined number of frequency bands, and the propagation gain estimation value obtained by weighting and combining each of the propagation gains with a predetermined weight radio device according to claim 2 or claim 6 to estimate the propagation loss from. The sensor part
Based on the detection result of the radio signal in the selected frequency band and the frequency usage information that is information indicating the usage status of each frequency band including the first frequency band and the frequency band that is the selection candidate band. A propagation loss estimator that estimates the propagation loss of a radio signal transmitted from one transmitter in one frequency band;
A reception power estimation unit that estimates reception power in the first frequency band based on the propagation loss estimation value estimated by the propagation loss estimation unit and the frequency use information;
By comparing the received power estimation value estimated by the receiving power estimation unit with a predetermined threshold, of claim 7 sharing whether the first frequency band claims 1 comprising a determining unit The wireless device according to any one of the above. For the first frequency band to be estimated for radio wave arrival status, the first frequency band used for transmission in the first transmitter that performs transmission in the first frequency band, and the first frequency band and Is a different second frequency band, or a third frequency band that is used for transmission by a second transmitter located in the vicinity of the first transmitter and is different from the first frequency band One or more frequency bands including at least one of the second or third frequency bands as selection candidate bands, and a frequency band for detecting a radio signal from the selection candidate bands A frequency band selector that can be selected; and
A sensor unit for detecting a radio signal in the frequency band selected by the frequency band selection unit ,
The frequency band selection unit selects a frequency band for detecting a radio signal based on the magnitude of the equivalent isotropic radiant power of the radio signal transmitted in each frequency band from the selection candidate bands. Wireless communication system. The sensor part
Based on the detection result of the radio signal in the selected frequency band and the frequency usage information that is information indicating the usage status of each frequency band including the first frequency band and the frequency band that is the selection candidate band. The radio communication system according to claim 9 , further comprising a propagation loss estimation unit that estimates a propagation loss of a radio signal transmitted from one transmitter in one frequency band. The frequency usage information is information indicating the use state of each frequency band and a frequency band to be selected candidate band from the first frequency band, according to claim 9 or comprising an informing device for informing using a predetermined control channel The wireless communication system according to claim 10 . A spectrum sensing method for a radio,
For the first frequency band to be estimated for radio wave arrival status, the first frequency band used for transmission in the first transmitter that performs transmission in the first frequency band, and the first frequency band and Is a different second frequency band, or a third frequency band that is used for transmission by a second transmitter located in the vicinity of the first transmitter and is different from the first frequency band When at least one of the two or more frequency bands is present, one or more frequency bands including at least one of the second or third frequency bands are selected as candidate bands, and transmitted in each frequency band from among the candidate bands Based on the magnitude of the equivalent isotropic radiant power of the radio signal, select the frequency band to detect the radio signal,
A spectrum sensing method, comprising: detecting a radio signal in a selected frequency band. Based on the detection result of the radio signal in the selected frequency band and the frequency usage information that is information indicating the usage status of each frequency band including the first frequency band and the frequency band that is the selection candidate band. The spectrum sensing method according to claim 12 , wherein the propagation loss of a radio signal transmitted from one transmitter in one frequency band is estimated. A radio control program applied to a radio,
On the computer,
For the first frequency band to be estimated for radio wave arrival status, the first frequency band used for transmission in the first transmitter that performs transmission in the first frequency band, and the first frequency band and Is a different second frequency band, or a third frequency band that is used for transmission by a second transmitter located in the vicinity of the first transmitter and is different from the first frequency band When at least one of the two or more frequency bands is present, one or more frequency bands including at least one of the second or third frequency bands are selected as candidate bands, and transmitted in each frequency band from among the candidate bands based on the equivalent isotropically magnitude of the radiation power of the radio signal, processing for selecting a frequency band to detect a radio signal, and radio system for executing the processing for detecting the wireless signal in a selected frequency band Program. On the computer,
Based on the detection result of the radio signal in the selected frequency band and the frequency usage information that is information indicating the usage status of each frequency band including the first frequency band and the frequency band that is the selection candidate band. The wireless device control program according to claim 14 , wherein processing for estimating a propagation loss of a wireless signal transmitted from one transmitter in one frequency band is executed. For the first frequency band to be estimated for radio wave arrival status, the first frequency band used for transmission in the first transmitter that performs transmission in the first frequency band, and the first frequency band and Is a different second frequency band, or a third frequency band that is used for transmission by a second transmitter located in the vicinity of the first transmitter and is different from the first frequency band When at least one of the two or more frequency bands is present, one or more frequency bands including at least one of the second or third frequency bands are selected as candidate bands, and transmitted in each frequency band from among the candidate bands A frequency band selector capable of selecting a frequency band for detecting a radio signal based on the magnitude of the equivalent isotropic radiant power of the radio signal, and a radio signal in the frequency band selected by the frequency band selector. The counterpart wireless terminal including a wireless device and a sensor unit for detecting a is the information indicating a usage frequency band used in the wireless communication system utilizing frequency band of estimation target radio wave arrival state Frequency usage information, at least the center frequency of the frequency band, the frequency bandwidth, the position information of the transmitter of the wireless communication system, the transmission antenna height information of the wireless communication system, the transmission power of the wireless communication system, and the wireless communication A frequency usage information notifying apparatus characterized by notifying information indicating a transmission antenna gain of a system, information indicating a propagation model, and frequency usage information including all or any of standard reception antenna heights using a predetermined control channel. On the computer,
For the first frequency band to be estimated for radio wave arrival status, the first frequency band used for transmission in the first transmitter that performs transmission in the first frequency band, and the first frequency band and Is a different second frequency band, or a third frequency band that is used for transmission by a second transmitter located in the vicinity of the first transmitter and is different from the first frequency band When at least one of the two or more frequency bands is present, one or more frequency bands including at least one of the second or third frequency bands are selected as candidate bands, and transmitted in each frequency band from among the candidate bands A frequency band selector capable of selecting a frequency band for detecting a radio signal based on the magnitude of the equivalent isotropic radiant power of the radio signal, and a radio signal in the frequency band selected by the frequency band selector. The counterpart wireless terminal including a wireless device and a sensor unit for detecting a is the information indicating a usage frequency band used in the wireless communication system utilizing frequency band of estimation target radio wave arrival state Frequency usage information, at least the center frequency of the frequency band, the frequency bandwidth, the position information of the transmitter of the wireless communication system, the transmission antenna height information of the wireless communication system, the transmission power of the wireless communication system, and the wireless communication A frequency usage information broadcast program for executing processing for broadcasting frequency usage information including all or any of the transmission antenna gain, propagation model information, and standard reception antenna height of a system using a predetermined control channel.

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