JP5332727B2 - Wireless communication apparatus, wireless communication system, and communication control method - Google Patents

Description

  The present invention relates to a wireless communication apparatus, a wireless communication system, and a communication control method.

  With the development of wireless technology, there are many cases where the connection between information communication devices has changed from wired to wireless. For example, in a LAN (Local Area Network), information communication devices are mainly connected by Ethernet (registered trademark) represented by IEEE802.3. However, in recent years, information communication devices are often connected by a wireless LAN typified by IEEE802.11. The flow from wired connection to wireless connection extends not only to LAN but also to PAN (Personal Area Network).

  On the other hand, in wireless connection, it is difficult to control the transmission distance from the physical characteristics of radio waves. Due to the difficulty in controlling the transmission distance, interference between a plurality of wireless networks often becomes a problem in wireless connection. This interference is because the frequency band that can be used in wireless communication is limited, and thus it is unavoidable to operate on the same or adjacent channels between a plurality of wireless networks located at a short distance.

  In order to avoid interference caused by operating a plurality of wireless networks located in a short distance on the same or adjacent channels, a technique of controlling transmission power and controlling the reach of radio waves is generally employed.

  Further, although not intended to avoid interference, a wireless communication terminal that automatically sets an appropriate transmission power has been proposed (see, for example, Patent Document 1). According to the wireless communication terminal, the distance to the opposite device is obtained, and the transmission power converted based on the distance is controlled.

  In the method of controlling the reach of radio waves by controlling the transmission power converted according to the distance to the opposing device, the actual reach of radio waves cannot be accurately controlled. This is because the estimation accuracy of the distance to the opposite device varies depending on spatial parameters such as walls, windows, or partitions, and the relationship between the transmission power converted by the distance and the radio wave arrival distance cannot be calculated uniformly. .

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wireless communication apparatus, a wireless communication system, and a communication control method that can reduce interference between a plurality of wireless communication networks.

This wireless communication device
A wireless communication device for measuring radio field intensity,
A demodulator that demodulates a packet modulated in accordance with the first wireless communication method from another wireless communication device;
A radio field intensity measurement unit for measuring the radio field intensity of the packet demodulated by the demodulation unit;
A storage unit for registering wireless communication devices belonging to each wireless communication network;
A determination unit that determines whether or not the other wireless communication device is registered in the storage unit;
When it is determined by the determination unit that the other wireless communication device is registered , the radio field intensity measurement unit according to a second wireless communication method having a radio wave transmission distance different from the first wireless communication method. A modulator for modulating the measured radio field intensity;
A transmitter that wirelessly transmits the radio wave intensity modulated by the modulator to the other wireless communication device,
The transmission power is controlled based on the radio field intensity by the other wireless communication device.

This wireless communication system
A wireless communication system having at least a first wireless communication device and a second wireless communication device,
The first wireless communication device is:
A packet generator for generating packets;
A modulation unit that modulates the packet generated by the packet generation unit according to a first wireless communication method;
A transmitter that wirelessly transmits the packet modulated by the modulator to another wireless communication device;
In response to a second wireless communication system having a radio wave transmission distance different from that of the first wireless communication system, a response packet including a radio field intensity of the modulated packet measured by the second wireless communication device is demodulated. A demodulator;
An acquisition unit for acquiring the radio wave intensity included in the response packet demodulated by the demodulation unit;
A determination unit that determines whether the radio field intensity acquired by the acquisition unit is greater than a first radio field intensity set in the second wireless communication device;
A transmission power control unit that reduces transmission power when the radio field intensity acquired by the acquisition unit is greater than the first radio field intensity based on a determination result by the determination unit;
The second wireless communication device is:
A demodulator that demodulates a packet modulated in accordance with the first wireless communication method from the first wireless communication device;
A radio field intensity measurement unit for measuring the radio field intensity of the packet demodulated by the demodulation unit;
A storage unit for registering wireless communication devices belonging to each wireless communication network;
A determination unit that determines whether or not the other wireless communication device is registered in the storage unit;
A modulation unit that modulates the radio field intensity measured by the radio field intensity measurement unit according to the second radio communication method when the determination unit determines that the other radio communication device is registered ;
A transmission unit that wirelessly transmits the radio wave intensity modulated by the modulation unit to the first wireless communication device.

This communication control method
A communication control method in a wireless communication device for measuring radio field intensity,
A demodulation step of demodulating a packet modulated in accordance with the first wireless communication system from another wireless communication device;
A radio field intensity measuring step for measuring the radio field intensity of the packet demodulated by the demodulation step;
A determination step of determining whether or not the other wireless communication device is registered in a storage unit for registering a wireless communication device belonging to each wireless communication network;
If it is determined in the determination step that the other wireless communication device is registered, according to a second wireless communication method having a radio wave transmission distance different from that of the first wireless communication method, A modulation step for modulating the measured radio field intensity;
A transmission step of wirelessly transmitting the radio wave intensity modulated by the modulation step to the other wireless communication device,
The transmission power is controlled based on the radio field intensity by the other wireless communication device.

  According to the disclosed wireless communication apparatus, wireless communication system, and communication control method, it is possible to reduce interference between a plurality of wireless networks.

It is explanatory drawing which shows an example of the radio | wireless communication network according to a present Example. It is a functional block diagram which shows the radio | wireless communication apparatus according to a present Example. It is a functional block diagram which shows the radio | wireless communication apparatus according to a present Example. It is a sequence diagram which shows operation | movement of the radio | wireless communications system according to a present Example. It is a functional block diagram which shows the radio | wireless communication apparatus according to a present Example. It is a sequence diagram which shows operation | movement of the radio | wireless communications system according to a present Example. It is a functional block diagram which shows the radio | wireless communication apparatus according to a present Example.

Next, the form for implementing this invention is demonstrated, referring drawings based on the following Examples.
In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

(Wireless communication network)
FIG. 1 shows a wireless communication network according to this embodiment.

The wireless communication network includes a first wireless communication device 100 _n (100 ₁ , 100 ₂ , 100 ₃ , 100 ₄ , 100 ₅ ) (n is an integer satisfying n> 0) and a second wireless communication device 200. Have. As shown in FIG. 1, the first wireless communication device 100 _n may be mounted on an information communication device. Information communication devices include devices equipped with wireless communication functions such as printers and laptop computers. In FIG. 1, the wireless communication network A includes wireless communication devices 100 ₁ and 100 ₂ , and the wireless communication network B includes wireless communication devices 100 ₃ , 100 ₄ , and 100 ₅ . In FIG. 1, five wireless communication devices _100n are illustrated, but the number may be four or less, or may be six or more. In FIG. 1, two wireless communication networks A and B are illustrated, but the present invention can also be applied to three or more wireless communication networks. The second wireless communication apparatus 200 has a function of detecting radio wave intensity. There may be a plurality of second wireless communication devices 200.

The first wireless communication device 100 _n wirelessly transmits radio waves to the second wireless communication device 200 by the first wireless communication method. For example, the first wireless communication devices 100 _n belonging to the wireless communication networks A and B may transmit packets to the second wireless communication device 200 at different timings. The second wireless communication device 200 may be installed at an arbitrary position. In FIG. 1, the second wireless communication device 200 is installed at a position where the wireless communication networks A and B can communicate with each other, in other words, in the vicinity of the boundary between the wireless communication network A and the wireless communication network B. it may be included in, or may be included in the information communication device including a first wireless communication apparatus 100 _n. By arranging the second wireless communication device 200 in the vicinity of the boundary between the wireless communication network A and the wireless communication network B, radio waves transmitted from the first wireless communication device 100 _n belonging to the wireless communication network A can be transmitted. can reduce interference with the first wireless communication apparatus 100 _n belonging to B, conversely, radio waves transmitted from the first wireless communication apparatus 100 _n belonging to a wireless communication network B is first belonging to the wireless communication network a It can reduce interference with the wireless communication apparatus 100 _n. In other words, interference between wireless communication networks can be reduced. The first radio communication system 100 _n and the second radio communication system 200 constitute a radio communication system.

Further, the first wireless communication device 100 _n and the second wireless communication device 200 may have a relationship between the parent device and the child device. For example, the first wireless communication device _100n may be mounted on the parent device, and the second wireless communication device 200 may be mounted on the child device. Conversely, the first wireless communication device 100 _n may be mounted on the child device, and the second wireless communication device 200 may be mounted on the parent device.

The second wireless communication apparatus 200 measures the reception intensity of the radio wave transmitted by wireless by the first wireless communication apparatus 100 _n. The second wireless communication device 200 feeds back the radio wave intensity by wireless transmission to the first wireless communication device 100 _n using a second wireless communication method different from the first wireless communication method.

The first radio communication apparatus 100 _n is preset with a radio wave intensity (hereinafter referred to as a radio wave intensity target value) to be targeted in the receiving side, in other words, the second radio communication apparatus 200. The first radio communication device 100 _n controls the transmission power so that the radio wave intensity fed back by the second radio communication device 200 is equal to or less than the radio wave intensity target value. By controlling the transmission power so that the radio field intensity fed back by the second radio communication apparatus 200 is less than or equal to the radio field intensity target value, the spatial spread of the radio wave transmitted by the first radio communication apparatus 100 _n is increased. Be controlled. In other words, the transmission range of the radio waves of the first radio communication apparatus 100 _n is controlled. Since the spatial spread of the radio wave is controlled, interference between the wireless communication network including the first wireless communication device and another wireless communication network can be reduced. In other words, interference between the wireless communication network A and the wireless communication network B can be reduced. Further, it is possible to reduce the transmission power of the first wireless communication apparatus 100 _n. Also, since the spatial extent of the radio waves transmitted from the first wireless communication apparatus 100 _n is controlled, it is possible to reduce the risk of eavesdropping.

Further, the first wireless communication method and the second wireless communication method may be different in frequency band and / or data transmission rate used for radio wave transmission. The transmission distance can be varied by different frequency bands and / or data transmission speeds used for radio wave transmission. For example, the first wireless communication device _100n and the second wireless communication device 200 have a function of performing communication using both the first and second wireless communication methods. Specifically, the first wireless communication device 100 _n has a function of transmitting by the first wireless communication method and a function of receiving by the second wireless communication method. The second wireless communication device 200 has a function of receiving by the first wireless communication method and a function of transmitting by the second wireless communication method. In the present embodiment, as an example, a case where the first wireless communication device _100n and the second wireless communication device 200 can communicate with each other by two types of wireless communication methods will be described. Communication may be possible by a method.

  For example, the frequency band used for transmission of radio waves by the first wireless communication method may be higher than the frequency band used for transmission of radio waves by the second wireless communication method. Furthermore, the data transmission rate of the first wireless communication method may be higher than the data transmission rate of the second wireless communication method. The frequency band used for radio wave transmission by the first wireless communication method is set to a higher frequency band than the second wireless communication method, and the data transmission speed by the first wireless communication method is higher than that of the second wireless communication method. By setting the data transmission speed, the transmission distance by the second wireless communication method can be made longer than the transmission distance by the first wireless communication method. The second wireless communication apparatus 200 receives the feedback of the radio field intensity from the first wireless communication apparatus 100 by making the transmission distance by the second wireless communication system longer than the transmission distance by the first wireless communication system. Probability can be improved.

  For example, a communication method according to the standard included in the wireless PAN may be applied as the first wireless communication method, and a communication method according to the standard included in the wireless LAN may be applied as the second wireless communication method. Standards included in the wireless PAN include IEEE802.11a, IEEE802.11b, IEEE802.11g, and IEEE802.11n. Standards included in a wireless LAN include UWB (Ultra Wide Band), ZigBee, Bluetooth, and the like. For example, in UWB, the frequency band used for radio wave transmission is a high frequency band, the data transmission rate is a high data transmission rate, and the radio wave reach is shorter than IEEE802.11b / g. Therefore, UWB can be applied as the first wireless communication method, and IEEE802.11b / g can be applied as the second wireless communication method. IEEE802.11b / g indicates IEEE802.11b or IEEE802.11g. Other standards can also be applied as appropriate based on the frequency band used for transmission of radio waves and the reach of radio waves.

  UWB is a wireless communication system that transmits and receives data by spreading data over an extremely wide frequency band of about 1 GHz. In UWB, data transmitted in each frequency band is only as strong as noise. Therefore, interference with wireless communication devices using the same frequency band can be reduced, and power consumption is also low. UWB has a data transmission speed of about 40 Mbps and is faster than Bluetooth or wireless LAN (IEEE 802.11b). The transmission distance of radio waves by UWB is about 10 m when the data transmission speed is 100 Mbps, and about 3 m when the data transmission speed is 480 Mbps.

  IEEE 802.11b is also called “IEEE 802.11 High-Rate Direct Sequence”. IEEE 802.11b uses a frequency band called the 2.4 GHz ISM band (Industry Science Medical band) that can be handled without a license. IEEE 802.11b has a maximum data transmission rate of 11 Mbps. The transmission distance of radio waves by IEEE 802.11b is 100m.

  IEEE 802.11g was developed as a higher standard of IEEE 802.11b and uses a frequency band called ISM band of 2.4 GHz. IEEE 802.11g has a data transmission rate of 54 Mbps. The transmission distance of radio waves by IEEE 802.11g is 100m.

  Hereinafter, as an example, a case where UWB is applied as the first wireless communication method and IEEE802.11b or IEEE802.11g is applied as the second wireless communication method will be described. Other wireless communication methods may be applied.

(First wireless communication device)
FIG. 2 shows a functional block diagram of the first wireless communication device 100 _n according to the present embodiment.

The first wireless communication apparatus 100 _n includes antennas 102 and 108, RF (Radio Frequency) units 104 and 110, baseband modulation / demodulation units 106 and 112, protocol control unit 114, and RAM (Random Access Memory) 116. And a ROM (Read Only Memory) 118 and a CPU (Central Processing Unit) 120. The protocol control unit 114, the RAM 116, the ROM 118, and the CPU 120 are connected by a system bus 122. The protocol control unit 114 includes a baseband determination unit 1142 and a radio wave intensity acquisition unit 1144. The CPU 120 includes a radio wave intensity measurement packet frame generation unit 1202 and a transmission power setting unit 1204.

The CPU 120 generates a packet frame for measuring radio field intensity. The CPU 120 stores the packet frame in the RAM 116. For example, the radio wave intensity measurement packet frame generation unit 1202 generates a radio wave intensity measurement packet frame and stores the radio wave intensity measurement packet frame in the RAM 116. The data included in the packet frame may be random data. The random data may be known data in the second wireless communication apparatus 200. For example, the first wireless communication device 100 _n may randomly select from a plurality of pieces of data known in the second wireless communication device 200. By making the random data known data in the second wireless communication apparatus 200, the second wireless communication apparatus 200 includes the random data in the received packet, so that the packet is a packet for measuring radio field intensity. Can be determined. The radio field intensity measurement packet may be a normal packet including data. Hereinafter, for convenience of explanation, it is referred to as a radio wave intensity measurement packet.

  The protocol control unit 114 reads the packet frame stored in the RAM 116. Then, the protocol control unit 114 inputs the packet frame to the baseband modem unit 112.

  The baseband modulation / demodulation unit 112 modulates the packet frame input by the protocol control unit 114. The baseband modulation / demodulation unit 112 inputs the modulated packet frame to the RF unit 110. The baseband modulation / demodulation unit 112 performs modulation using a multiband orthogonal frequency division multiplexing (MB-OFDM) scheme. In the MB-OFDM system, the band of 3.1 to 10.6 GHz where UWB can be used is divided into 14 bands, 528 MHz is assigned to each band, and these are further grouped into five groups. Each band performs primary modulation by quadrature phase shift keying (QPSK) and uses OFDM modulation for secondary modulation. Furthermore, a frequency hopping spread spectrum method is applied.

  The RF unit 110 converts the modulation signal input from the baseband modulation / demodulation unit 112 into a radio signal, and transmits the radio signal via the antenna 108.

  The feedback signal (response packet) transmitted by the second wireless communication apparatus 200 is input to the RF unit 104 via the antenna 102. The RF unit 104 converts a radio signal into a modulation signal. The RF unit 104 inputs the modulated signal to the baseband modulation / demodulation unit 106.

  The baseband modulation / demodulation unit 106 converts the modulation signal input from the RF unit 104 into a baseband signal. The baseband modulation / demodulation unit 106 inputs a baseband signal to the protocol control unit 114. The modulation signal input to the baseband modulation / demodulation unit 106 is a signal modulated by a complementary code keying (CCK) method when the second wireless communication apparatus 200 transmits a feedback signal by the IEEE802.11b method. It is. In addition, the modulation signal input to the baseband modulation / demodulation unit 106 is obtained by orthogonal frequency division multiplexing (OFDM) when the second wireless communication apparatus 200 transmits a feedback signal by the IEEE802.11g method. It is a modulated signal. The baseband modulation / demodulation unit 106 converts the modulation signal modulated by the complementary code modulation method or the orthogonal frequency division multiplexing method into a baseband signal.

  The protocol control unit 114 determines whether or not the baseband signal input by the baseband modem unit 106 is normal. The protocol control unit 114 may determine that the baseband signal is normal when no error is detected using an error correction code included in the baseband signal. For example, the baseband signal determination unit 1142 determines whether or not the baseband signal input by the baseband modulation / demodulation unit 106 is normal. If it is determined that the baseband signal is normal, the baseband signal is acquired as a radio wave intensity acquisition unit 1144. To enter. The protocol control unit 114 acquires the radio field intensity from the normal baseband signal. The protocol control unit 114 inputs the radio wave intensity to the CPU 120. For example, the radio wave intensity acquisition unit 1144 acquires the radio wave intensity from the baseband signal input by the baseband signal determination unit 1142 and inputs the radio wave intensity to the CPU 120. In addition, the protocol control unit 114 may perform error correction on a baseband signal that is not determined to be normal, and acquire radio wave intensity.

  The CPU 120 compares the radio wave intensity input by the protocol control unit 114 with the radio wave intensity target value. The CPU 120 sets the transmission power to be reduced when the radio field intensity is larger than the radio field intensity target value. Further, the CPU 120 maintains the transmission power when the radio wave intensity is equal to or less than the radio wave intensity target value. The CPU 120 inputs the transmission power setting result to the protocol control unit 114. For example, the transmission power setting unit 1204 compares the radio wave intensity input by the protocol control unit 114 with the radio wave intensity target value, and sets the transmission power to be decreased when the radio wave intensity is larger than the radio wave intensity target value. .

  For example, the power control step may be set in advance. When the transmission power is decreased, the CPU 120 inputs a transmission power setting result including a command to decrease the transmission power by the transmission power corresponding to the power control step to the protocol control unit 114. Further, the CPU 120 inputs a transmission power setting result including a command to decrease only transmission power corresponding to a plurality of power control steps to the protocol control unit 114 according to the difference between the radio wave intensity and the radio wave intensity target value. May be.

  Further, the CPU 120 may increase the transmission power when the radio wave intensity is less than the radio wave intensity target value. When the transmission power is increased, the CPU 120 inputs a transmission power setting result including a command for increasing the transmission power by the transmission power corresponding to the power control step to the protocol control unit 114. Further, the CPU 120 inputs a transmission power setting result including a command to increase the transmission power corresponding to a plurality of power control steps to the protocol control unit 114 according to the difference between the radio wave intensity and the radio wave intensity target value. May be.

  The protocol control unit 114 notifies the RF unit 110 of a transmission power control signal including the transmission power set according to the transmission power setting result input by the CPU 120.

  The RF unit 110 controls the transmission power according to the transmission power notified by the protocol control unit 114.

  The RAM 116 temporarily stores the radio wave measurement packet frame generated by the CPU 120. The RAM 116 may be configured by SRAM (Static Random Access Memory).

  The ROM 118 stores a program for causing the CPU 120 to perform arithmetic processing. For example, the ROM 118 includes a program for generating a radio field intensity measurement packet for measuring the radio field intensity, a program for acquiring the radio field intensity included in the response packet, and a radio field intensity that the radio field intensity should be targeted at the receiving side. A program for determining whether or not it is greater than the target value, and a transmission power control program for reducing the transmission power when the acquired radio field intensity is greater than the radio field intensity target value based on a determination result by the determination program are installed in advance. ing. Other functions of the first wireless communication apparatus 100 may also be realized by the CPU 120 executing a program.

(Second wireless communication device)
FIG. 3 shows a functional block diagram of the second wireless communication apparatus 200 according to the present embodiment.

  The second wireless communication apparatus 200 includes antennas 202 and 208, RF units 204 and 210, baseband modulation / demodulation units 206 and 212, a protocol control unit 214, a CPU 218, and a storage unit 220. The protocol control unit 214, the CPU 218, and the storage unit 220 are connected by a system bus 216. The baseband modulation / demodulation unit 212 includes a reception intensity measurement unit 2122, and the protocol control unit 214 includes a response packet generation unit 2142.

  The radio signal carrying the packet frame for measuring the radio field intensity transmitted from the first radio communication apparatus 100 is input to the RF unit 210 via the antenna 208.

  The RF unit 210 converts the radio signal input from the antenna 208 into a modulation signal and inputs the modulation signal to the baseband modulation / demodulation unit 212.

  The baseband modulation / demodulation unit 212 converts the modulation signal input from the RF unit 210 into a baseband signal. The baseband modulation / demodulation unit 212 inputs a baseband signal to the protocol control unit 214. The modulation signal input to the baseband modulation / demodulation unit 212 is a modulation signal modulated by the multiband orthogonal frequency division multiplexing method. The baseband modulation / demodulation unit 212 converts a modulation signal modulated by the multiband orthogonal frequency division multiplexing method into a baseband signal.

  The baseband modulation / demodulation unit 212 measures the reception intensity (radio wave intensity) of the modulated signal. The baseband modulation / demodulation unit 212 may obtain a reception strength measurement result as a received signal strength indication (RSSI). In addition, the baseband modulation / demodulation unit 212 may obtain the measurement result of the reception intensity as an error vector amplitude (EVM). The baseband modulation / demodulation unit 212 inputs the reception intensity measurement result to the protocol control unit 214. For example, the reception strength measurement unit 2122 measures the reception strength of the modulated signal, and inputs the measurement result of the reception strength to the protocol control unit 214.

  The protocol control unit 214 generates a packet frame in which the reception intensity measurement result input from the baseband modulation / demodulation unit 212 is arranged in the packet payload. The protocol control unit 214 inputs the packet frame to the baseband modulation / demodulation unit 206. For example, the response packet generation unit 2142 generates a packet frame in which the reception strength measurement result input from the baseband modulation / demodulation unit 212 is arranged in the payload of the packet, and inputs the packet frame to the baseband modulation / demodulation unit 206.

  The baseband modem unit 206 modulates the packet frame input from the protocol control unit 214. The baseband modulation / demodulation unit 206 inputs the modulated packet frame to the RF unit 204. When the IEEE802.11b method is applied to the wireless communication apparatus 200, the baseband modulation / demodulation unit 206 performs modulation using a complementary code modulation method. Further, the baseband modulation / demodulation unit 206 performs modulation by an orthogonal frequency division multiplexing method when the IEEE802.11g method is applied to the wireless communication apparatus 200.

  The RF unit 204 converts the modulation signal input from the baseband modulation / demodulation unit 206 into a radio signal, and transmits the radio signal via the antenna 202.

  The storage unit 220 stores a program for causing the CPU 218 included in the second wireless communication apparatus 200 to perform arithmetic processing. For example, the storage unit 220 is preinstalled with a program for measuring the reception strength of the radio field strength measurement packet. Other functions of the second wireless communication apparatus 200 may also be realized by the CPU 218 executing a program.

(Communication control method)
FIG. 4 shows a communication control method between the first wireless communication apparatus 100 _n and the second wireless communication apparatus 200 according to the present embodiment.

The first wireless communication device 100 _n generates a packet for measuring radio field intensity (step S402). The CPU 120 generates a radio field intensity measurement packet and stores it in the RAM 116. The radio wave intensity measurement packet may be generated when communication is started between the first wireless communication device 100 _n and the second wireless communication device 200. By being generated when communication is started, interference between wireless communication networks caused by the communication can be reduced. In addition, the radio field intensity measurement packet may be periodically generated between the first wireless communication device 100 _n and the second wireless communication device 200. By periodically generating, interference between wireless communication networks after communication is started can be reduced.

The first wireless communication device 100 _n transmits the radio wave intensity measurement packet to the second wireless communication device 200 (step S404). The protocol control unit 114 reads the packet frame stored in the RAM 116 and inputs the packet frame to the baseband modulation / demodulation unit 112. The baseband modulation / demodulation unit 112 modulates the packet frame input from the protocol control unit 114 by multiband orthogonal frequency division multiplexing, and inputs the modulated signal to the RF unit 110. The RF unit 110 converts the modulation signal input from the baseband modulation / demodulation unit 112 into a radio signal, and transmits the radio signal via the antenna 108.

The second wireless communication apparatus 200 measures the reception strength of the first radio field intensity measurement packet transmitted by the wireless communication apparatus 100 _n (step S406). A radio signal carrying the radio field intensity measurement packet is input to the RF unit 210 via the antenna 208. The RF unit 210 converts the radio signal into a modulation signal and inputs the modulation signal to the baseband modulation / demodulation unit 212. The modulation signal is a modulation signal based on a multiband orthogonal frequency division multiplexing system. The baseband modulation / demodulation unit 212 converts the modulation signal input from the RF unit 210 into a baseband signal. The baseband modulation / demodulation unit 212 measures the reception intensity (radio wave intensity) of the modulated signal. The baseband modulation / demodulation unit 212 may obtain the reception intensity measurement result as RSSI or EVM. The baseband modulation / demodulation unit 212 inputs the reception intensity measurement result to the protocol control unit 214.

  The second wireless communication apparatus 200 generates a response packet including the radio wave intensity measured in step S406 (step S408). The protocol control unit 214 generates a packet frame in which the reception intensity measurement result input from the baseband modulation / demodulation unit 212 is arranged in the packet payload. The protocol control unit 214 inputs the packet frame to the baseband modulation / demodulation unit 206.

  The second wireless communication device 200 transmits a response packet (step S410). The baseband modem unit 206 modulates the packet frame input from the protocol control unit 214. For example, the baseband modulation / demodulation unit 206 performs modulation by the complementary code modulation method when the IEEE802.11b method is applied to the wireless communication apparatus 200, and the IEEE802.11g method is applied to the wireless communication device 200. Is modulated by an orthogonal frequency division multiplexing system. The baseband modulation / demodulation unit 206 inputs the modulated packet frame to the RF unit 204. The RF unit 204 converts the modulation signal input from the baseband modulation / demodulation unit 206 into a radio signal, and transmits the radio signal via the antenna 202.

The first wireless communication device 100 _n performs error detection of the response packet (step S412). The radio signal on which the response packet transmitted by the second radio communication apparatus 200 is placed is input to the RF unit 104 via the antenna 102. The RF unit 104 converts a radio signal into a modulation signal. The modulated signal is a signal modulated by the complementary code modulation method when the second wireless communication device 200 transmits a feedback signal by the IEEE802.11b method, and the second wireless communication device 200 has the IEEE802.11g method. When the feedback signal is transmitted by the method, the signal is modulated by the orthogonal frequency division multiplexing method. The RF unit 104 inputs the modulated signal to the baseband modulation / demodulation unit 106. The baseband modulation / demodulation unit 106 converts a signal modulated by the complementary code modulation method or the orthogonal frequency division multiplexing method into a baseband signal, and inputs the baseband signal to the protocol control unit 114. The protocol control unit 114 uses the error correction code included in the baseband signal to determine that the baseband signal is normal when no error is detected. In addition, the protocol control unit 114 may perform error correction on a baseband signal that is not determined to be normal, and acquire radio wave intensity.

The first wireless communication device 100 _n controls transmission power (step S414). The protocol control unit 114 acquires the radio wave intensity from the normal baseband signal and inputs the radio wave intensity to the CPU 120. The CPU 120 compares the radio wave intensity input by the protocol control unit 114 with the radio wave intensity target value, and sets the transmission power to be reduced when the radio wave intensity is larger than the radio wave intensity target value. Further, the CPU 120 sets the transmission power to be maintained when the radio field intensity is equal to or less than the radio field intensity target value. The CPU 120 inputs the transmission power setting result to the protocol control unit 114. The protocol control unit 114 notifies the RF unit 110 of the set transmission power according to the transmission power setting result input by the CPU 120. The RF unit 110 controls the transmission power according to the transmission power notified by the protocol control unit 114.

The first wireless communication device 100 _n may transmit a radio field intensity measurement packet to the second wireless communication device 200 every time transmission power is set. The transmission of the radio wave intensity measurement packet may be continued until the radio wave intensity becomes equal to or lower than the radio wave intensity target value.

Also, the first wireless communication device 100 _n may transmit the radio field intensity measurement packet to the second wireless communication device 200 with the transmission power maximized when the packet is first transmitted. Then, the first wireless communication device 100 _n may transmit the radio wave intensity measurement packet until the radio wave intensity becomes equal to or lower than the radio wave intensity target value.

For example, a case where a power control step is set will be described. The first wireless communication device 100 _n is set to reduce the transmission power by the power control step when the radio wave intensity is larger than the radio wave intensity target value. For example, when 1 dBm power is set to be reduced as the power control step, the 1 dBm transmission power is set to be reduced. However, even if the transmission power is reduced by the power control step, the radio wave intensity may not be lower than the radio wave intensity target value. By transmitting the radio field intensity measurement packet until the radio field intensity becomes equal to or lower than the radio field intensity target value, the radio field intensity at the receiving side, in other words, the second radio communication apparatus 200 can be reduced below the radio field intensity target value. Since the radio waves from the first wireless communication device 100 _n belonging to the network A can reduce the interference given to the first wireless communication device 100 _n belonging to the wireless communication network B, the interference between the plurality of wireless networks can be reduced.

(Modification)
The wireless communication network according to the present embodiment is the same as the wireless communication network described with reference to FIG. The first wireless communication apparatus 100 _n according to this embodiment will be described by the wireless communication apparatus shown in FIG.

(Second wireless communication device)
FIG. 5 shows a second wireless communication apparatus 200 according to the present embodiment. The second wireless communication apparatus 200 is different from the wireless communication apparatus shown in FIG. The protocol control unit 214 includes a wireless communication device registration unit 2144. In the wireless communication device registration unit 2144, for each wireless communication network, addresses of wireless communication devices belonging to the wireless communication network are registered. The address may include a media access control (MAC) address.

  The baseband modulation / demodulation unit 212 converts the modulation signal modulated by the multiband orthogonal frequency division multiplexing method into a baseband signal, and inputs the baseband signal to the protocol control unit 214. The wireless communication device registration unit 2144 acquires a transmission source address included in the radio wave intensity measurement packet based on the baseband signal input by the baseband modulation / demodulation unit 212. The wireless communication device registration unit 2144 determines whether the transmission source address is registered. When the transmission source address is registered, the wireless communication device registration unit 2144 generates a packet frame in which the reception intensity measurement result input by the baseband modulation / demodulation unit 212 is arranged in the packet payload. The protocol control unit 214 inputs the packet frame to the baseband modulation / demodulation unit 206. For example, when the transmission source address is registered, the response packet generation unit 2142 generates a packet frame in which the reception strength measurement result input by the baseband modulation / demodulation unit 212 is arranged in the packet payload, and the packet Is input to the baseband modem unit 206.

  When the transmission source address is not registered, the protocol control unit 214 discards the reception strength measurement result input by the baseband modulation / demodulation unit 212.

(Communication control method)
FIG. 6 shows a communication control method between the first wireless communication apparatus 100 _n and the second wireless communication apparatus 200 according to the present embodiment.

  Steps S602 to S606 and steps S610 to S616 are the same as steps S402 to S414 in the communication control method described with reference to FIG.

  In step S608, the second wireless communication apparatus 200 determines whether the transmission source address included in the radio field intensity measurement packet is registered. Based on the baseband signal input by the baseband modulation / demodulation unit 212, the wireless communication device registration unit 2144 acquires the transmission source address included in the radio field intensity measurement packet and determines whether the transmission source address is registered. To do.

  In step S610, when the transmission source address is registered, the second wireless communication apparatus 200 generates a response packet including the radio wave intensity measured in step S606. The protocol control unit 214 generates a packet frame in which the reception intensity measurement result input from the baseband modulation / demodulation unit 212 is arranged in the packet payload. The protocol control unit 214 inputs the packet frame to the baseband modulation / demodulation unit 206.

(Other variations)
The wireless communication network according to the present embodiment is the same as the wireless communication network described with reference to FIG.

(First wireless communication device)
FIG. 7 shows a first wireless communication device 100 _n according to the present embodiment. The first wireless communication device 100 _n according to the present embodiment is configured such that the operation display unit 124 is included in the wireless communication device described with reference to FIG.

  The second wireless communication apparatus 200 according to the present embodiment is described by the wireless communication apparatus shown in FIG.

The operation display unit 124 is a part that operates the wireless communication device 100 _n and includes an operation unit such as a numeric keypad. The operation display unit 124 allows the user to input a radio wave intensity target value to be targeted on the receiving side. The operation display unit 124 is a part that performs display, and includes display means such as a display.

  The CPU 120 compares the radio wave intensity input by the protocol control unit 114 with the radio wave intensity target value input by the operation display unit 124. The CPU 120 sets the transmission power to be reduced when the radio field intensity is larger than the radio field intensity target value. Further, the CPU 120 maintains the transmission power when the radio wave intensity is equal to or less than the radio wave intensity target value. The CPU 120 inputs the transmission power setting result to the protocol control unit 114. For example, the transmission power setting unit 1204 compares the radio wave intensity input by the protocol control unit 114 with the radio wave intensity target value input by the operation display unit 124. Set to reduce power.

  In the above-described embodiment, the case where the first and second wireless communication apparatuses have prerecorded programs for executing the functions of the wireless communication apparatuses has been described. However, the present invention is not limited to this, and the same functions are wirelessly transmitted from the network. You may download to a communication apparatus and you may install what stored the same function in the recording medium in the radio | wireless communication apparatus. The recording medium may take any form as long as it can store a program such as a CD-ROM and can be read by the wireless communication apparatus. Further, the function executed by a program installed in advance or a program obtained by downloading may be realized in cooperation with an operating system (OS) in the wireless communication apparatus.

  According to the present embodiment, it is determined whether the radio wave intensity included in the response packet of the radio wave intensity measurement packet is larger than the radio wave intensity target value to be targeted on the receiving side, and the radio wave intensity is larger than the radio wave intensity target value. In this case, by reducing the transmission power, it is possible to control the reception intensity (radio wave intensity) in another wireless communication apparatus. The other wireless communication device may be installed in an arbitrary place. In addition, when the radio wave intensity is larger than the radio wave intensity target value, the reach of the radio wave can be controlled by reducing the transmission power.

  According to the present embodiment, when other wireless communication devices are registered in the storage unit for registering wireless communication devices belonging to each wireless communication network, the measured reception strength is measured according to the second wireless communication method. By transmitting, transmission power can be controlled only for a wireless communication device that wants to control the reach of radio waves. Since transmission power can be controlled only for a wireless communication device that wants to control the reach of radio waves, a flexible network can be constructed.

  According to the present embodiment, by having the setting unit for setting the radio wave intensity target value, the user can set the radio wave intensity target value in another wireless communication apparatus installed in an arbitrary place. Since the user can set the radio wave intensity target value, the radio wave intensity target value in another wireless communication device can be changed according to the use environment.

  According to the present embodiment, the radio wave intensity measurement packet modulated according to the first radio communication system is demodulated from another radio communication apparatus, the reception intensity of the demodulated radio wave intensity measurement packet is measured, By modulating the reception intensity in accordance with the second wireless communication system having a radio wave transmission distance different from that of the first wireless communication system, interference between the radio field intensity measurement packet and the response packet can be prevented.

  According to the present embodiment, the transmission frequency band is different between the first wireless communication system and the second wireless communication system. Different transmission frequencies can reduce interference.

  According to the present embodiment, the first wireless communication system has a shorter radio wave transmission distance than the second wireless communication system, so that the second wireless communication apparatus receives the radio field intensity from the first wireless communication apparatus. The probability that a response packet to the measurement packet can be received can be improved.

  According to the present embodiment, the first wireless communication method is UWB and the second wireless communication method is IEEE802.11b or IEEE802.11g, so that the radio wave intensity measurement packet and the response packet to the radio wave measurement packet are transmitted. The transmission distance of radio waves can be made different.

  Each structure in the Example mentioned above can be combined suitably. Variations not directly mentioned in one embodiment are also applicable. For example, the transmission power setting unit may be included in the second wireless communication apparatus 200. When the second wireless communication apparatus 200 includes the transmission power setting unit, the following control may be performed. The second radio communication apparatus 200 compares the radio field intensity measured by the reception intensity measuring unit with the radio field intensity target value set in the second radio communication apparatus 200, and the radio field intensity is greater than the radio field intensity target value. When it is larger, it is determined that the transmission power is decreased. Then, second radio communication apparatus 200 determines that transmission power is maintained when the radio field intensity is equal to or less than the radio field intensity target value. When it is determined that the transmission power is to be decreased, the second wireless communication apparatus 200 notifies the first wireless communication apparatus 100 that the transmission power is to be decreased. The first wireless communication device 100 controls transmission power according to the notification from the second wireless communication device 200.

  For convenience of explanation, specific numerical examples will be described to facilitate understanding of the invention. However, unless otherwise specified, these numerical values are merely examples, and any appropriate value may be used.

  Although the present invention has been described above with reference to specific embodiments, each embodiment is merely an example, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, and the like. I will. For convenience of explanation, an apparatus according to an embodiment of the present invention has been described using a functional block diagram, but such an apparatus may be realized by hardware, software, or a combination thereof. The present invention is not limited to the above-described embodiments, and various variations, modifications, alternatives, substitutions, and the like are included without departing from the spirit of the present invention.

100 _n (100 ₁ , 100 ₂ , 100 ₃ , 100 ₄ , 100 ₅ ) Wireless communication device (first wireless communication device)
102, 108 Antenna 104, 110 RF unit 106, 112 Baseband modulation / demodulation unit 114 Protocol control unit 1142 Baseband signal determination unit 1144 Radio wave intensity acquisition unit 116 RAM
118 ROM
120 CPU
1202 Packet frame generation unit for measuring radio field strength 1204 Transmission power setting unit 122 System bus (SYSTEM BUS)
124 Operation display unit 200 Wireless communication device (second wireless communication device)
202, 208 Antenna 204, 210 RF unit 206, 212 Baseband modulation / demodulation unit 2122 Receive strength measurement unit 214 Protocol control unit 2142 Response packet generation unit 2144 Wireless communication device registration unit 216 System bus (SYSTEM BUS)
218 CPU
220 Storage unit

JP 2008-17302 A

Claims (6)

A wireless communication device for measuring radio field intensity,
A demodulator that demodulates a packet modulated in accordance with the first wireless communication method from another wireless communication device;
A radio field intensity measurement unit for measuring the radio field intensity of the packet demodulated by the demodulation unit;
A storage unit for registering wireless communication devices belonging to each wireless communication network;
A determination unit that determines whether or not the other wireless communication device is registered in the storage unit;
When it is determined by the determination unit that the other wireless communication device is registered , the radio field intensity measurement unit according to a second wireless communication method having a radio wave transmission distance different from the first wireless communication method. A modulator for modulating the measured radio field intensity;
A transmitter that wirelessly transmits the radio wave intensity modulated by the modulator to the other wireless communication device,
A wireless communication apparatus in which transmission power is controlled based on the radio field intensity of the other wireless communication apparatus. The wireless communication device according to claim 1 ,
The wireless communication apparatus, wherein the first wireless communication system and the second wireless communication system have different transmission frequency bands. The wireless communication device according to claim 1 or 2 ,
The wireless communication apparatus characterized in that the first wireless communication method has a shorter transmission distance of radio waves than the second wireless communication method. The wireless communication apparatus according to any one of claims 1 to 3 ,
The wireless communication apparatus in which the first wireless communication method is UWB and the second wireless communication method is IEEE802.11b or IEEE802.11g. A wireless communication system having at least a first wireless communication device and a second wireless communication device,
The first wireless communication device is:
A packet generator for generating packets;
A modulation unit that modulates the packet generated by the packet generation unit according to a first wireless communication method;
A transmitter that wirelessly transmits the packet modulated by the modulator to another wireless communication device;
In response to a second wireless communication system having a radio wave transmission distance different from that of the first wireless communication system, a response packet including a radio field intensity of the modulated packet measured by the second wireless communication device is demodulated. A demodulator;
An acquisition unit for acquiring the radio wave intensity included in the response packet demodulated by the demodulation unit;
A determination unit that determines whether the radio field intensity acquired by the acquisition unit is greater than a first radio field intensity set in the second wireless communication device;
A transmission power control unit that reduces transmission power when the radio field intensity acquired by the acquisition unit is greater than the first radio field intensity based on a determination result by the determination unit;
The second wireless communication device is:
A demodulator that demodulates a packet modulated in accordance with the first wireless communication method from the first wireless communication device;
A radio field intensity measurement unit for measuring the radio field intensity of the packet demodulated by the demodulation unit;
A storage unit for registering wireless communication devices belonging to each wireless communication network;
A determination unit that determines whether or not the other wireless communication device is registered in the storage unit;
A modulation unit that modulates the radio field intensity measured by the radio field intensity measurement unit according to the second radio communication method when the determination unit determines that the other radio communication device is registered ;
A wireless communication system comprising: a transmission unit that wirelessly transmits the radio wave intensity modulated by the modulation unit to the first wireless communication device. A communication control method in a wireless communication device for measuring radio field intensity,
A demodulation step of demodulating a packet modulated in accordance with the first wireless communication system from another wireless communication device;
A radio field intensity measuring step for measuring the radio field intensity of the packet demodulated by the demodulation step;
A determination step of determining whether or not the other wireless communication device is registered in a storage unit for registering a wireless communication device belonging to each wireless communication network;
If it is determined in the determination step that the other wireless communication device is registered, according to a second wireless communication method having a radio wave transmission distance different from that of the first wireless communication method, A modulation step for modulating the measured radio field intensity;
A transmission step of wirelessly transmitting the radio wave intensity modulated by the modulation step to the other wireless communication device,
A communication control method in which transmission power is controlled based on the radio field intensity by the other wireless communication device.

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