JP2004228608A - System for preventing eavesdropping of radio wave, method for same, and wall member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for preventing eavesdropping of a radio wave and a method for the same wherein secrecy is remarkably enhanced. <P>SOLUTION: A reception antenna A with directivity toward the inside of a building is installed, and transmission antennas B1 and B2 with directivity toward the outside of the building are installed on an outer wall face of the building. The reception antenna A receives and processes one radio wave or more transmitted from a server 102 and a client 104 used inside the building and thereafter the transmission antennas emit the processed radio wave with the same output as that of the radio wave from the radio apparatuses and leaked from the building. Thus, the system gives interference to a radio apparatus of an external eavesdropper with respect to a wireless LAN to allow the external interceptor to make eavesdropping difficult without giving effect on the radio apparatuses in use in a room and giving disturbance to communication using other frequency by a portable telephone or the like. The reception antenna A and the transmission antennas B1 and B2 may be installed on a wall face or buried in the wall face. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radio wave interception prevention system, a radio wave interception prevention method, and a wall material, and more particularly, to preventing a communication radio wave of a wireless LAN wireless device used inside a building from being intercepted outside the building. The present invention relates to a radio wave interception prevention system, a radio wave interception prevention method, and a wall material.
[0002]
[Prior art]
In wireless communication performed inside a building, it is extremely important for security to prevent radio waves leaking out of the building from being intercepted.
[0003]
For example, when a wireless LAN is used in a room of each tenant in a commercial building, the content of the communication may be radiated outside through an opening such as a window or a wall due to the nature of radio waves. May be maliciously received for eavesdropping or the like.
[0004]
In order to cope with such a problem, a technique for protecting the confidentiality of a signal leaking to the outside of a building by, for example, a scrambling method is known.
[0005]
For example, in Patent Document 1, a scramble code having a length indicated by a code length is generated for each packet of data, data is scrambled by the generated scramble code, and scrambled data in which the scramble code is arranged at an embedding position is scrambled. A data communication which adds data to data and encrypts the data with a common key is disclosed.
[0006]
Patent Document 2 discloses a data transmission / reception device that performs communication by transmitting an interfering wave together with a digital modulation wave. According to this technique, when an interfering wave transmitted from an omnidirectional antenna is received together with a digital modulation wave from a partner side, the interfering wave component is added to the phase-inverted interfering wave to cancel and remove the interfering wave component.
[0007]
[Patent Document 1]
JP 2002-33728 A
[0008]
[Patent Document 2]
JP 2001-094536 A
[0009]
[Problems to be solved by the invention]
However, it is difficult to say that confidentiality of communication is sufficiently ensured only by the above-described technology for preventing interception using the scramble method. In other words, there is a problem that the conventional technology regarding the prevention of eavesdropping cannot be a means of defense against a malicious expert.
[0010]
Further, in the case of a wireless LAN that has been rapidly spreading in recent years, there has been a problem that the chances of being intercepted increase as the number of places where the wireless LAN wireless device is used increases.
[0011]
Further, when communication is performed by transmitting an interfering wave together with a digitally modulated wave, each radio must have a means for removing the interfering wave. For this reason, there has been a problem that the manufacturing cost is high.
[0012]
The present invention has been made in view of such a problem, and an object of the present invention is to provide a radio signal interception prevention system, a radio signal interception prevention method, and a wall material with significantly improved confidentiality. is there.
[0013]
[Means for Solving the Problems]
In order to achieve such an object, the invention according to claim 1 is a radio wave interception prevention system, which has directivity inside a building and transmits radio signals from a radio device used inside the building. A receiving antenna for receiving at least one radio wave, a transmitting antenna installed near the outer wall surface of the building and having directivity outside the building, and a radio wave received by the receiving antenna using scramble modulation. Processing means, and radiating means for radiating the radio wave processed by the processing means from the transmitting antenna with an output equivalent to the radio wave from the radio leaking from the building. .
[0014]
In the present invention, a directional receiving antenna is installed inside a building, and a directional transmitting antenna is installed outside the building on the outer wall surface of the building. Then, after receiving and processing one or more radio waves transmitted by the wireless LAN radio used in the building with the receiving antenna, the output is equivalent to the radio waves from the radio leaking from the building after being processed, thereby preventing interception. From the transmitting antenna as interference waves for
[0015]
As a result, interference can be made only to the wireless receiver of an outside eavesdropper on the wireless LAN without affecting the wireless device used indoors and without disturbing communication using other frequencies such as a mobile phone. Give to make interception difficult. The receiving antenna and the transmitting antenna may be installed on a wall surface or may be embedded in the wall surface. By making the output equal to the radio wave from the wireless device leaking from the building, it is not necessary to radiate the radio wave with a large amount of electric power to cause interference, and power saving can be realized.
[0016]
According to a second aspect of the present invention, in the radio signal interception prevention system according to the first aspect, a radiation output of the radio wave radiated from the transmission antenna is equal to or less than an output requiring a license stipulated by law. It is characterized by the following.
[0017]
This eliminates the need for procedures for testing compliance with regulations and standards set forth in the Radio Law in the manufacture and sale of transmitters for causing interference. As a result, such a system can be easily realized.
[0018]
According to a third aspect of the present invention, in the radio wave interception prevention system according to the first aspect, the processing means is a wireless LAN wireless device.
[0019]
According to a fourth aspect of the present invention, in the radio signal interception prevention system according to the third aspect, the wireless device for the wireless LAN includes a demodulating means for demodulating a radio wave received by the receiving antenna; And a modulating means for scrambling and modulating the radio wave demodulated by the.
[0020]
According to the present invention, a wireless device of a wireless LAN is used as a processing device, and after a received wave from the antenna is demodulated, scramble modulation is performed. Therefore, an existing wireless device for a wireless LAN can be used. As a result, the device can be realized economically.
[0021]
According to a fifth aspect of the present invention, in the radio wave eavesdropping prevention system of the first aspect, the processing means is a device adapted to software radio.
[0022]
According to a sixth aspect of the present invention, in the radio signal interception prevention system according to the fifth aspect, the device corresponding to the software radio transmits the radio wave received by the receiving antenna in the same demodulation method as the radio. And demodulation means for modulating the radio wave demodulated by the demodulation means by the same modulation scheme as that of the wireless device.
[0023]
In the present invention, software radio equipment is used as a processing device, and radiation is radiated from an antenna by the same modulation and demodulation method as that of a wireless device in a building. In this way, by configuring the processing apparatus with a programmable device, it is possible to realize an apparatus that can support an arbitrary method by downloading parameters corresponding to a method used indoors from a personal computer to the processing apparatus. More specifically, dedicated processing is applied to systems using different frequencies and modulation systems, such as IEEE 802.11b using a CDMA modulation system in the 2.4 GHz band and IEEE 802.11a using OFDM in the 5 GHz band. There is no need to prepare equipment.
[0024]
According to a seventh aspect of the present invention, in the system for preventing interception of a radio wave according to the first aspect, the processing means includes a receiving means for receiving the spread spectrum signal, and a receiving means for receiving the signal received by the receiving means. Detection means for performing quadrature detection, storage means for storing a signal demodulated by the quadrature detection for an arbitrary time length, and a signal stored by the storage means using a clock extracted by the quadrature detection. And a modulation means for performing modulation.
[0025]
In the present invention, the processing apparatus receives, for example, a signal that has been spread and emitted as a signal source and demodulates the spread signal at a symbol rate by primary demodulation by quadrature detection. Then, a demodulated signal, that is, a demodulated signal as spread (hereinafter, referred to as a “primary demodulated signal”) and a clock signal synchronized with the spread signal are extracted.
[0026]
Next, at least one cycle of the primary demodulated signal and a multiple of the cycle length are stored in a memory, modulated by the extracted synchronous clock, and radiated from the transmitting antenna. This cycle is changed randomly. Thereby, even if the external wireless receiving apparatus performs despreading in order to demodulate the intercepted spread spectrum signal, it becomes meaningless data repetition from the replica signal repeatedly transmitted at an integral multiple of the period of the spread signal. , The data of the original signal cannot be intercepted.
[0027]
According to an eighth aspect of the present invention, in the radio signal interception prevention system according to the first aspect, the processing unit includes a receiving unit that receives a spread spectrum signal, and a receiving unit that receives the signal received by the receiving unit. A detection unit for performing quadrature detection, and a signal demodulated by the quadrature detection are passed through a variable delay device that arbitrarily changes the amount of delay of the signal with time, and modulation is performed using a clock extracted by the quadrature detection. Modulation means.
[0028]
In the present invention, the processing apparatus receives a signal that is spread and emitted. Then, the signal after the quadrature detection is passed through a variable delay device whose delay amount changes randomly with time, and modulation is performed using a clock extracted by quadrature detection of the received signal. Accordingly, since the spread spectrum signal intercepted by the external wireless receiving device becomes meaningless data, the interception can be prevented.
[0029]
According to a ninth aspect of the present invention, in the radio wave interception prevention system according to the first aspect, the processing unit turns off a power supply when there is no radio wave received by the receiving antenna. I do.
[0030]
Thereby, power saving of the processing apparatus can be performed.
[0031]
According to a tenth aspect of the present invention, in the radio signal interception prevention system according to the first aspect, the reception antenna and the transmission antenna are array antennas having a band of 2 GHz to 5 GHz, and the transmission antenna is provided with the processing means. And radiates the radio wave processed in the same directivity as the leaked radio wave from the wireless device.
[0032]
In the present invention, a wideband array antenna capable of controlling the directivity in both the 2.4 GHz band and the 5 GHz band is used as the receiving antenna and the transmitting antenna. Then, the processed radio wave is radiated from the transmitting antenna with the same directivity as the leaked radio wave from the indoor wireless LAN radio. Thereby, an interference wave can be efficiently generated.
[0033]
According to an eleventh aspect of the present invention, in the radio signal interception prevention system according to the first aspect, the processing unit demodulates a radio wave received by the receiving antenna, and the demodulation unit demodulates the radio wave. A first processing device that includes a modulating unit that scramble-modulates a radio wave, and a second processing device that transmits a radio wave received by the reception antenna from the transmission antenna, wherein the first processing device and the second processing device The second processing device is characterized in that it can be switched by an external signal.
[0034]
In the present invention, as a processing device, a radio wave from a radio inside a building is received by a receiving antenna, and after performing scramble modulation, a first processing device that transmits from a transmission antenna, and a radio wave from a radio inside the building are transmitted. A second processing device for receiving by a receiving antenna and transmitting by a transmitting antenna is provided. Then, the first processing device and the second processing device are switched by an external signal. As a result, even if the wireless LAN access point is installed in a different room, the wireless LAN terminal can use the access point with good quality.
[0035]
According to a twelfth aspect of the present invention, in the radio signal interception prevention system according to the first aspect, the reception antenna or the transmission antenna is embedded in reinforced concrete.
[0036]
According to a thirteenth aspect of the present invention, in the radio signal interception prevention system according to the first aspect, the reception antenna or the transmission antenna is embedded in a PCa board.
[0037]
The invention according to claim 14 is the radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is formed as a curtain wall.
[0038]
According to a fifteenth aspect of the present invention, in the radio wave interception prevention system according to the first aspect, the reception antenna or the transmission antenna is embedded in a window sash.
[0039]
The invention according to claim 16 is the radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in a door frame.
[0040]
According to a seventeenth aspect of the present invention, in the method for preventing interception of a radio wave, at least one radio signal transmitted from a radio device used inside the building using a receiving antenna having directivity inside the building. One radio wave is received and processed using a processing device that performs scramble modulation, the radio wave received by the receiving antenna is processed, and the processed radio wave is installed near the outer wall surface of the building, and the outside of the building is And radiating from a transmitting antenna having directivity with an output equivalent to a radio wave from the wireless device leaking from the building.
[0041]
As a result, interference can be made only to the wireless receiver of an outside eavesdropper on the wireless LAN without affecting the wireless device used indoors and without disturbing communication using other frequencies such as a mobile phone. Give to make interception difficult. The receiving antenna and the transmitting antenna may be installed on a wall surface or may be embedded in the wall surface. By making the output equal to the radio wave from the wireless device leaking from the building, it is not necessary to radiate the radio wave with a large amount of electric power to cause interference, and power saving can be realized.
[0042]
The invention according to claim 18 is a wall material, which has directivity inside a building and receives at least one radio wave transmitted from a radio device used inside the building. An antenna, a transmitting antenna installed near the outer wall surface of the building and having directivity outside the building, processing means for processing radio waves received by the receiving antenna using scramble modulation, and the processing means And a radiating means for radiating the radio wave processed by the transmitting antenna with the same output as the radio wave from the wireless device leaking from the building.
[0043]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0044]
(1st Embodiment)
FIG. 1 is a diagram illustrating a configuration example of a radio wave eavesdropping prevention system according to the present invention. 1 includes a receiving antenna A, transmitting antennas B1 and B2, a processing device 200, a distributor 110, and a wireless LAN system 300.
[0045]
In the figure, a receiving antenna A is a directional antenna mounted on a wall, and transmitting antennas B1 and B2 are directional antennas embedded in a wall and installed as an array. The receiving antenna A receives a radio signal transmitted and received indoors. The received radio signal is processed by the processing device 200, amplified to a predetermined level, distributed by the distributor 110, and radiated from the transmitting antennas B1 and B2 to the outside of the building. The transmitting antennas B1 and B2 have gain only in the direction outside the building and do not radiate inside the building which is in the opposite direction.
[0046]
On the other hand, the wireless LAN system 300 includes a server 102 and a client 104 used as wireless LAN wireless devices. The server 102 and the client 104 are both personal computers that perform wireless communication conforming to IEEE 802.11a. Note that the server 102 and the client 104 are examples of a wireless device used inside a building, and a terminal such as a mobile phone or a PDA (Personal Digital Assistant) can also be used as the wireless device.
[0047]
FIG. 2 is a block diagram showing a configuration example when the processing apparatus according to the present embodiment is applied to a wireless device for wireless LAN. The processing apparatus 200 includes a reception RF unit 201, a frequency converter unit 202, a demodulation unit 204, a disturbance unit 206, a modulation unit 208, a frequency converter unit 209, a transmission RF unit 210, a level detection unit 220, a signal generator (SG) 203, And a power supply unit 230. The radio wave of the wireless LAN wireless device transmitted from the receiving antenna A is amplified by the receiving RF unit 201, frequency-converted by the signal from the signal generator 203 by the frequency converter 202, and then demodulated by the demodulation unit 204. . After the demodulated signal is subjected to a scramble operation in the disturbance unit 206, the signal enters the transmission RF unit 210 through the modulation unit 208 and the frequency converter unit 209. The amplification factor of the transmission RF unit 210 is variable and can be adjusted to a predetermined power. The adjusted signal is radiated from transmitting antennas B1 and B2.
[0048]
Thus, the processing apparatus of the present invention can be applied to an existing wireless LAN wireless device. As a result, the device can be realized economically.
[0049]
Next, a specific configuration of the disturbance unit 206 will be described. The disturbance unit 206 processes radio waves received by the receiving antenna using scramble modulation, and may have a configuration as shown in FIG. 3, for example. In the figure, the disturbance unit 206 has a pseudo-random signal generator 250 that generates a PN (Pseudo Noise) code. In this case, the disturbance unit 206 performs a scrambling operation using the output of the demodulation unit 204 and the signal obtained by modulating the output of the pseudo-random signal generator 250 by the modulation unit 207 using the clock obtained from the demodulation unit 204.
[0050]
Further, the disturbance unit 206 may be configured as shown in FIG. 4, for example. In the figure, the disturbance unit 206 includes a primary demodulation unit 251 and a storage / reproduction unit 252. The primary demodulation unit 251 receives the signal spread and emitted as a signal source, and performs demodulation at a symbol rate of the spread signal as primary demodulation by quadrature detection. The storage / reproducing unit 252 stores at least one period of the primary demodulated signal and a multiple of the period, and reproduces this.
[0051]
In this case, primary demodulation section 251 extracts a demodulated signal, that is, a primary demodulated signal, and a clock signal synchronized with the spread signal from the received signal. The storage / reproducing unit 252 stores a predetermined period of the primary demodulated signal, reproduces the same, and sends it to the modulating unit 253. The modulation unit 253 performs spread modulation on the reproduced primary demodulated signal using the extracted synchronous clock, and radiates it from the antennas B1 and B2. By changing this cycle at random, the external radio receiving apparatus cannot intercept the data of the original signal, and intercepts the replica signal repeatedly transmitted at an integral multiple of the cycle of the spread signal. Therefore, even if despreading is performed in order to demodulate the intercepted spread spectrum signal, meaningless repetition of data is obtained.
[0052]
Further, the disturbance unit 206 may be configured as shown in FIG. 5, for example. In the figure, a disturbance unit 206 includes a primary demodulation unit 261 and a variable delay unit 262 that randomly changes a signal delay amount with time. Here, the variable delay unit 262 delays the signal for a specific time (for example, 1 msec or the like) according to the signal length.
[0053]
The primary demodulation unit 261 receives the spectrum-spread and emitted signal, and performs primary demodulation by quadrature detection at the symbol rate of the spread signal in the primary demodulation unit 261 to synchronize with the primary demodulated signal and the spread signal. Extract the clock signal. Then, after passing the demodulated signal through the variable delay unit 262, the modulation unit 263 performs spread modulation using a clock extracted by quadrature detection of the received signal. By performing such processing, the spread spectrum signal intercepted by the external wireless reception device is processed as meaningless data, so that interception is not possible.
[0054]
Returning to FIG. 2 again, the level of the signal of the reception RF unit 201 is detected by the level detection unit 220. When the detected level is equal to or less than the specified value, the control unit (not shown) of the processing apparatus 200 turns off the power from the frequency converter unit 202 to the transmission RF unit 210. Here, in order to start up after the power is turned off, the reception RF unit 201 and the level detection unit 220 are operated constantly or intermittently at set time intervals. Then, when the level of the level detection unit 220 becomes equal to or higher than a predetermined value, the cut off power is turned on.
[0055]
FIG. 6 is a diagram illustrating an example of installation of transmission antennas. In the figure, it is assumed that the wireless LAN system is used on the second floor of the building 600. The ceiling and floor of the building 600 have a shield structure, and no radio waves enter from other floors in the vertical direction in the drawing. It is assumed that a signal wave may leak from the window 302 or the window 303 in the horizontal direction.
[0056]
Generally, the attenuation of a radio wave passing through a window is about several dB, and even when a special metal film is attached thereto, the shielding performance of the radio wave is about 30 dB (for example, Maeda and Kato, "Easy Wireless LAN", Ohm Co., 1993). Considering that the dynamic reception performance of radio waves is about 60 to 80 dB, the shielding effect in the building 600 is not sufficient. In general, radio waves leaking from a window are larger than radio waves leaking from a wall surface. Therefore, the transmitting antennas B1 and B2 are installed near the respective windows to emit signal waves with the same directivity as interference waves. With this configuration, it is possible to effectively prevent the radio wave interception by the interception receiver 301.
[0057]
Since the transmission data sent by the interference wave is disturbed and modulated with the same signal as the normal signal, the wireless receiver cannot separate and eliminate the interference wave, and Correct data cannot be retrieved and received.
[0058]
Note that the processing device 200 may be configured by a planar circuit. In this case, it can be used by attaching it to a film-like sheet and attaching it to a window.
[0059]
Further, the receiving antenna A or the transmitting antennas B1 and B2 can be configured as an antenna box.
[0060]
(2nd Embodiment)
FIG. 7 is a block diagram illustrating a configuration example when the processing apparatus according to the present embodiment is applied to a device compatible with software radio. As shown in the figure, the processing device 700 digitizes the signal output of the frequency converter unit 202 by the A / D converter 203. Thereafter, the demodulation unit 704, the disturbance unit 706, and the modulation unit 708 perform digital signal processing. That is, the demodulation unit 704, the disturbance unit 706, and the modulation unit 708 have the same functions as the demodulation unit 204, the disturbance unit 206, and the modulation unit 208 described in the above embodiment, but differ in that they perform digital signal processing. ing.
[0061]
The signal output from modulation section 208 is converted into an analog signal by A / D converter 240, and transmitted from transmission antennas B1 and B2 from frequency converter section 209 via transmission RF section 210. In this case, by using modulation and demodulation as digital processing, it is possible to cope with different modulation schemes.
[0062]
In this way, by configuring the processing apparatus with a programmable device, it is possible to realize an apparatus that can support an arbitrary method by downloading parameters corresponding to a method used indoors from a personal computer to the processing apparatus.
[0063]
(Third embodiment)
Next, referring to FIG. 8 to FIG. 12, a wall on which a receiving antenna or a transmitting antenna (hereinafter may be simply abbreviated as “antenna”) used in the processing device of the above-described radio wave interception prevention system is mounted. Embodiments of materials and the like will be described. FIG. 8 shows an example of a PCa (precast concrete) plate in which an antenna is embedded. PCa802 is obtained by driving concrete into only the lower end portion of a reinforcing bar assembled in a three-dimensional truss shape, and has a thickness x of about 150 to 200 mm. An antenna 804 having directivity in a predetermined direction is embedded in the PCa 802. The antenna 804 having directivity is realized by providing a reflector or the like. The antenna embedded in this way can be used as a receiving antenna or as a transmitting antenna. By using such a PCa board instead of a mold frame and using it as a wall board, it is possible to realize a building in which the radio wave interception prevention system according to the present invention is incorporated.
[0064]
FIG. 9 shows an example in which an antenna is mounted on a PCa board. In the example shown in the figure, a scraping 904 is provided on a PCa plate of about 3 m × 4 m, and an antenna box is installed in the scraping.
[0065]
The receiving antenna or the transmitting antenna may be formed as a curtain wall. FIG. 10 shows an example in which an antenna is mounted on a metal curtain wall. The curtain wall is a non-bearing wall composed of a large panel in which various metal members are combined. By cutting slots 1004 of a predetermined shape or arrangement on the metal surface 1002, an antenna having directivity can be obtained. . Here, the slot 1004 may be covered with a resin through which radio waves can pass.
[0066]
In the case of a glass curtain wall, a metal antenna 1106 can be printed on a glass surface 1104 as shown in FIG.
[0067]
FIG. 12 is a cross-sectional view showing a part of a window sash in which an antenna of a radio wave interception prevention system is incorporated. The window sash 1204 in which the glass 1206 is fitted is installed on the wall 1202, and is configured to be movable in the direction of the arrow. An antenna 1208 having directivity is incorporated in the window sash 1204. In this case, in consideration of weather resistance, a portion where the antenna 1208 is incorporated may be filled with Teflon (registered trademark) or the like. It goes without saying that an antenna can be installed in the door sash similarly.
[0068]
Further, the external antenna may be installed near the outer wall, and may be installed on the floor, ceiling, or inner wall.
[0069]
Although the preferred embodiments of the present invention have been described above, the present invention can be variously modified in addition to the above-described embodiments. However, as long as the modification is based on the technical idea described in the claims, the modification also falls within the technical scope of the present invention.
[0070]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a radio wave interception prevention system and a radio wave interception prevention method whose confidentiality is significantly improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of a radio wave eavesdropping prevention system according to the present invention.
FIG. 2 is a block diagram illustrating a configuration example of a processing apparatus according to an embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration example of a disturbance unit according to an embodiment of the present invention.
FIG. 4 is a block diagram illustrating a configuration example of a disturbance unit according to an embodiment of the present invention.
FIG. 5 is a block diagram illustrating a configuration example of a disturbance unit according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating an example of installation of a transmitting antenna according to an embodiment of the present invention.
FIG. 7 is a block diagram illustrating a configuration example of a processing apparatus according to an embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of a PCa board in which an antenna of a processing apparatus is embedded.
FIG. 9 is a diagram showing an example in which an antenna used in a processing apparatus according to an embodiment of the present invention is mounted on a PCa board.
FIG. 10 is a diagram showing an example in which an antenna used in a processing apparatus according to an embodiment of the present invention is mounted on a metal curtain wall.
FIG. 11 is a diagram showing an example in which the antenna used in the processing apparatus according to one embodiment of the present invention is mounted on a glass curtain wall.
FIG. 12 is a diagram illustrating an example in which an antenna used in a processing apparatus according to an embodiment of the present invention is mounted on a window sash.
[Explanation of symbols]
102 server
104 clients
110 distributor
200 processing equipment
201 Receive RF unit
202 Frequency converter
203 signal generator
204 demodulation unit
206 Disturber
207, 208 Modulation unit
209 Frequency converter
210 Transmission RF unit
220 level detector
230 power supply
232, 240 A / D converter
250 pseudo-random signal generator
251 Primary demodulation unit
252 storage unit
253 modulator
261 Primary demodulation unit
262 Variable delay device
263 Modulation unit
300 Wireless LAN system
302, 303 window
600 building
700 processing equipment
704 demodulation unit
706 Disturber
708 Modulation unit
802 PCa
804, 1106, 1208 antenna
902 PCa board
904 scraping part
1002 metal surface
1004 slots
1104 Glass surface
1202 wall
1204 window sash
1206 glass
A receiving antenna
B1, B2 transmitting antenna

Claims (18)

A receiving antenna having directivity inside the building and receiving at least one radio wave transmitted from a radio device used inside the building;
A transmission antenna installed near the outer wall surface of the building and having directivity outside the building,
Processing means for processing the radio waves received by the receiving antenna using scramble modulation,
A radiating unit for radiating the radio wave processed by the processing unit from the transmitting antenna with an output equivalent to that of the radio wave leaking from the building from the wireless device. The radio wave eavesdropping prevention system according to claim 1, wherein a radiation output of the radio wave radiated from the transmission antenna is equal to or less than an output requiring a license prescribed by law. The radio wave eavesdropping prevention system according to claim 1, wherein the processing means is a wireless device for a wireless LAN. The wireless LAN wireless device includes:
Demodulation means for demodulating radio waves received by the receiving antenna,
4. The radio wave interception prevention system according to claim 3, further comprising a modulation unit that scramble-modulates the radio wave demodulated by the demodulation unit. 2. The radio wave eavesdropping prevention system according to claim 1, wherein the processing unit is a device compatible with software radio. The device corresponding to the software defined radio,
Demodulation means for demodulating the radio wave received by the receiving antenna by the same demodulation method as the wireless device,
6. The radio wave interception prevention system according to claim 5, further comprising: a modulation unit that modulates the radio wave demodulated by the demodulation unit using the same modulation scheme as that of the wireless device. The processing means,
Receiving means for receiving the spread spectrum signal;
Detection means for performing quadrature detection of the signal received by the reception means,
Storage means for storing a signal demodulated by the quadrature detection for an arbitrary time length,
2. The radio wave interception prevention system according to claim 1, further comprising a modulation unit that modulates the signal stored by the storage unit using a clock extracted by the quadrature detection. The processing means,
Receiving means for receiving the spread spectrum signal;
Detection means for performing quadrature detection of the signal received by the reception means,
Modulating means for passing the signal demodulated by the quadrature detection through a variable delay device that arbitrarily changes the amount of delay of the signal with time, and performing modulation using a clock extracted by the quadrature detection. The radio wave eavesdropping prevention system according to claim 1. The radio wave interception prevention system according to claim 1, wherein the processing unit turns off a power supply when there is no radio wave received by the reception antenna. The receiving antenna and the transmitting antenna are array antennas having a band of 2 GHz to 5 GHz, and the transmitting antenna radiates a radio wave processed by the processing unit with the same directivity as a leaked radio wave from the wireless device. The radio wave eavesdropping prevention system according to claim 1. The processing means,
A first processing apparatus including demodulating means for demodulating a radio wave received by the receiving antenna, a modulating means for scrambling the radio wave demodulated by the demodulating means, and a transmitting antenna for transmitting the radio wave received by the receiving antenna. The radio wave interception according to claim 1, further comprising a second processing device for transmitting from the first processing device, wherein the first processing device and the second processing device can be switched by an external signal. Prevention system. The radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in reinforced concrete. The system according to claim 1, wherein the receiving antenna or the transmitting antenna is embedded in a PCa board. The radio wave interception prevention system according to claim 1, wherein the reception antenna or the transmission antenna is formed as a curtain wall. The radio wave eavesdropping prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in a window sash. The radio wave eavesdropping prevention system according to claim 1, wherein the reception antenna or the transmission antenna is embedded in a door frame. Using a receiving antenna having directivity inside the building, receiving at least one radio wave transmitted from a radio device used inside the building,
Using a processing device that performs scramble modulation, processes the radio wave received by the receiving antenna,
The processed radio wave is installed near the outer wall surface of the building, and is radiated from a transmitting antenna having directivity outside the building with an output equivalent to the radio wave from the wireless device leaking from the building. A method for preventing radio wave eavesdropping. A receiving antenna having directivity inside the building and receiving at least one radio wave transmitted from a radio device used inside the building, and being installed near an outer wall surface of the building and outside the building; A transmitting antenna having directivity, processing means for processing a radio wave received by the receiving antenna using scramble modulation, and a radio wave from the radio leaking from the building, the radio wave processed by the processing means. And a radiating means for radiating from the transmitting antenna with an output equivalent to that of the wall material.

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