JP2006050216A - Wireless communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly maintain a reception characteristic of a receiver side independently of a wireless environment without excessively increasing the transmission power by controlling the transmission power of a transmitter. <P>SOLUTION: A wireless communication apparatus 1 making two-way communication with an opposed wireless communication apparatus includes a reception circuit 12, a transmission circuit 13, and a signal processing section 14 including: a level discrimination function 141 for discriminating a level of a received signal; a quality discrimination function 142 for discriminating the quality of the received signal; a read circuit 143 for reading a power control signal from the received signal; and a control signal attaching function 144 for attaching a transmission power control signal for a communication opposite party to a transmission signal. The apparatus 1 controls an antenna switching circuit 11 and a reception circuit 12 on the basis of a discrimination result of the level of the received signal and the received signal quality, generates the transmission power control signal for controlling the transmission power of the wireless communication apparatus of the communication opposite party and transmits the control signal to the wireless communication apparatus of the communication opposite party, and the wireless communication apparatus of the communication opposite party controls the transmission power of its transmission circuit 13 by the transmission power control signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless communication device, and more particularly to optimization of transmission power.

  With recent advances in digital signal processing technology, using digital data makes it possible to transmit large volumes of data compared to analog data, and further advances in digital modulation / demodulation technology allow data to be transmitted within a certain period of time. The transmission speed is also increasing in capacity.

  With the development of wireless communication technology, transmission / reception of still images or moving images is being realized even on mobile phones, and many wireless communication systems are also operating on wireless LANs having higher transmission speeds. There are IEEE802.11b that uses 2.4 GHz band radio waves and IEEE802.11a that uses 5 GHz band radio waves as wireless LAN standards, and IEEE802,11g that aims to further increase the transmission speed for 2.4 GHz radio waves. Standardization is ongoing. These wireless LAN standards have a transmission speed that enables relatively high-definition video transmission, and in addition to data transfer such as files used on PCs, they are incorporated into consumer devices that handle video, and wired cable It is conceivable to use it for the purpose of wireless transmission of video signals without requiring wiring.

  A major feature of wireless communication devices is that no cable transmission for signal transmission is required, so that it can be moved freely if a battery is installed, or can be used without a power source at the installation location. In this case, a reduction in power consumption of the wireless communication device is required to extend the life of the battery. Also, in applications where a battery is not used and connected to a household power line, reduction of power consumption is required as part of measures for environmental problems.

  Also, in wireless communication, the received power on the receiving side is not constant due to environmental changes. For example, if there is an obstruction that shields radio waves between wireless communication devices that are performing wireless communication, the received power on the receiving side is attenuated. However, the reception power in the reception circuit on the signal receiving side is reduced, and the reception quality is deteriorated. When necessary digital data is reproduced from a signal with degraded reception quality, there is a high probability that many errors will be included. As a result, the reception characteristics deteriorate or the communication distance is shortened in order to obtain equivalent reception characteristics. Problems such as the need to do so arise.

  In order to prevent this problem in the receiving circuit, an amplifier is provided at the first stage of the receiving circuit, and means for amplifying the received signal is taken. Since the amplifier generates noise, the S / N represented by the ratio between the signal power and the noise power deteriorates in the signal that has passed through the amplifier. For this reason, a means for amplifying received power while suppressing deterioration of S / N is used by using a low noise amplifier with little generated noise as the first stage amplifier of the receiving circuit. However, conversely, when the increase power is excessively large, it is conceivable that the reception signal is amplified more than necessary in the reception circuit of the reception-side wireless communication device, causing distortion. Even when necessary digital data is reproduced from a signal containing distortion, there is a high probability that many errors will be included. As a result, the reception characteristics deteriorate or the communication distance needs to be shortened to obtain equivalent reception characteristics. Problems such as occur.

  In the above-mentioned standards such as IEEE802.11a or IEEE802.11g, the OFDM technique is used for the digital modulation system. In the OFDM signal, the signal amplitude is not constant and the received signal power is excessively increased. Cheap. For this reason, distortion in the reception circuit is likely to occur, and management of transmission power on the transmission side or management of reception power on the reception side becomes very important. In the above-mentioned standard, the QAM modulation method in which information is also included in the amplitude component may be used as the digital modulation method. Since the amplitude of the reception signal is important, the reception characteristics are severely affected by the distortion generated in the reception signal. May deteriorate.

  In order to avoid such a problem, it is important to keep the received signal at an appropriate value. FIG. 5 shows a receiving circuit and a signal processing circuit part in a conventional wireless communication apparatus. In FIG. 5, the wireless communication apparatus includes a receiving circuit 12 and a signal processing circuit 14. The reception circuit 12 in the wireless communication apparatus includes a high frequency filter 121, a low noise amplifier 122, a variable attenuator 123, a mixer 124, a filter 125, a variable amplifier 126, and a local oscillator 37.

  In FIG. 5, a reception signal received by the wireless communication apparatus through an antenna (not shown) is input to the reception circuit 12. In the receiving circuit 12, the received signal is amplified by the low noise amplifier 122 via the high frequency filter 121 and supplied to the mixer 124 via the variable attenuator 123. In the mixer 124, the received signal is multiplied by the local oscillation signal output from the local oscillator 127 to convert the frequency to an intermediate frequency, and is output to the filter 125 as an intermediate frequency signal. The intermediate frequency signal from which unnecessary waves such as harmonics have been removed by the filter 125 is input to the signal processing circuit 14 via the variable amplifier 126 and output from the data input / output terminal 17 after predetermined signal processing.

  If the signal level of the intermediate frequency signal input to the signal processing circuit 14 deviates from a predetermined value, the reception operation characteristics in the signal processing circuit 14 deteriorate and an error occurs in the received data, so that the signal level of the intermediate frequency signal is constant. Need to keep on. The signal processing circuit 14 is provided with a detection circuit (not shown) that detects the signal level of the intermediate frequency signal input to the signal processing circuit 14, so that the signal level of the intermediate frequency signal is set to a desired value. The variable attenuator 123 and the variable amplifier 126 are feedback-controlled. That is, when the signal level of the received signal received by the antenna is weak, the attenuation amount of the variable attenuator 123 is reduced and the gain of the variable amplifier 126 is increased. Conversely, when the signal level received by the antenna is strong, feedback control is performed so that the level of the intermediate frequency signal becomes constant by increasing the attenuation amount of the variable attenuator 123 and decreasing the gain of the variable amplifier 126.

In this way, as a conventional example for maintaining reception characteristics regardless of fluctuations in received power in the circuit on the receiving side, the received signal power is determined, and the received power is determined in the receiving circuit based on the determination result. There is a receiving device that functions so as to correct, and is preferably operated even when a received signal is excessively large (see, for example, Patent Document 1).
JP 2002-94408 A

  The reason why the wireless communication device is required to reduce power consumption is as described above. A radio communication device is equipped with a high-frequency circuit for transmitting and receiving radio signals. The circuit portion that consumes the most power in this high-frequency circuit unit is a power amplifier circuit that generates transmission power of the transmission circuit. In managing power consumption, appropriately controlling the power of the power amplifier portion is expected to reduce the power consumption of the device.

  In addition, in order to maintain the reception characteristics suitably, there is a limit to the range of reception power that can be adjusted by means of adjusting the reception power in the reception circuit. However, the reception characteristics are deteriorated, and the probability that the digital data reproduced on the reception side includes an error increases. Furthermore, if the received power is too weak or too strong, the received signal cannot be reproduced. As a result, in a system that wirelessly transmits a video signal, problems such as block noise occur in the video.

  In addition, the influence of the distortion caused by the reception signal being amplified more than necessary has already been described, but it is difficult to grasp the distortion in the reception signal only by detecting the reception power, and it is also difficult to avoid the distortion. .

  In the conventional example shown in FIG. 5, when the received signal level is high, the attenuation amount of the variable attenuator 123 is increased by feedback control from the signal processing circuit 14, and the signal level of the received signal input to the mixer 124 is decreased. Decreases the level of the intermediate frequency signal. As a result, it is possible to prevent a saturation phenomenon in the mixer 124 that occurs when an excessive signal level is input to the mixer 124. However, considering the case where the received signal level received by the antenna is larger and the saturation phenomenon occurs in the low noise amplifier 122, even if the signal level is attenuated by the variable attenuator 123 in this case, the low noise amplifier 122 The generated saturation phenomenon cannot be removed, and deterioration of reception characteristics in the signal processing circuit 14 cannot be suppressed.

  In view of the above problems, the present invention can favorably maintain the reception characteristics on the receiver side regardless of the radio environment without excessively increasing the transmission power by controlling the transmission power of the transmitter. An object is to provide a wireless communication device. Furthermore, an object of the present invention is to provide a wireless communication apparatus that can appropriately suppress the power consumed by the transmission circuit and reduce the power consumption.

  In order to avoid such problems, it is important to keep the signal input to the receiver at an appropriate value. The receiving side determines the received power from the received signal and returns the result to the transmitting side for transmission. Form a feedback loop to keep the power at an appropriate value. That is, when the reception power of the reception signal in the reception circuit is larger than necessary, a control signal for instructing the transmission side to reduce the transmission power is superimposed on the transmission signal in the signal processing circuit from the transmission circuit. On the contrary, when the reception power in the reception circuit is smaller than necessary, the transmission side is instructed to increase the transmission power. On the side of receiving the control signal for giving this instruction, the transmission power is controlled by this control signal, and the transmission power is kept at an appropriate value. As a result, the transmission power does not increase or decrease more than necessary, and appropriate power is maintained.

  That is, in order to solve the above-described problem, the present invention provides a wireless communication system that performs bidirectional communication between a first wireless communication device and a second wireless communication device. A transmission circuit that transmits a signal, a reception circuit that receives a signal from the second wireless communication device, a control signal reading circuit that reads a transmission power control signal from the second wireless communication device, and a read transmission power control signal The second wireless communication apparatus has a function of controlling the output of the transmission circuit based on the transmission circuit for transmitting the signal, the reception circuit for receiving the signal from the first wireless communication apparatus, and the received signal. The first determination means for determining the reception level of the second, the second determination means for determining the quality of the received signal, and the determination results of the first and second determination means are the transmission power of the first wireless communication device. Need to change Creating a transmit power control signal when it is determined that to have a function of transmitting to the first wireless communication device.

  In the wireless communication system, the present invention is a means for transmitting a video signal input by the first wireless communication apparatus, and a means for the second wireless communication apparatus to receive the video signal and output it to a monitor. did.

  In order to solve the above-described problem, the present invention provides a wireless communication device that constitutes a wireless communication system that performs bidirectional communication with two wireless communication devices, in which the wireless communication device transmits a signal. A receiving circuit that receives a signal from a wireless communication device of a communication partner, a first determination unit that determines a reception level of the received signal, a second determination unit that determines the quality of the received signal, When the determination result of the first and second determination means determines that it is necessary to change the transmission power of the communication partner wireless communication device, a transmission power control signal is generated and transmitted to the communication partner wireless communication device. A function, a control signal reading circuit that reads a transmission power control signal from a wireless communication device of a communication partner, and a function of controlling the output of the transmission circuit based on the read transmission power control signal are provided.

Further, the present invention provides the above-described wireless communication apparatus, wherein the antenna performs a circuit switching operation so as to connect at least one antenna and a transmission circuit and the antenna at the time of transmission and connect the antenna and the reception circuit at the time of reception. The switching circuit, the first determining means and the second determining means, and the function of processing the signal input via the data input / output terminal during signal transmission into a form suitable for wireless communication and the signal received by the receiving circuit The signal processing circuit has a function to process the data and send data from the data input / output terminal. The signal processing circuit controls the antenna switching circuit and the receiving circuit based on the determination results of the first and second determination circuits. At the same time, a transmission signal power control signal is created and the signal processing circuit supplies the transmission signal power control signal to the signal supplied to the transmission circuit. And to transmit to the wireless communication device tatami communication partner.

  Further, according to the present invention, in the above wireless communication apparatus, the first determination means has a predetermined two-level reception level reference value and compares the reception signal level with the reception level reference value to make a ternary determination. I did it.

  According to the present invention, in the above wireless communication apparatus, when the received signal level is determined in advance and is not between two levels of received level reference values, the quality of the received signal is determined by the second determining means, and the received signal level is Outputs a transmission power control signal that increases the transmission level of the wireless communication device of the communication partner when the quality is inferior to the lower reception level reference value and lower than the reception level reference value with the higher reception signal level Outputs a transmission power control signal that reduces the transmission level of the wireless communication device of the communication partner when the quality is high and the quality is good, and when the quality is inferior to the reception level reference value of the higher reception signal level, the interference wave The detection is notified to the wireless communication device of the communication partner.

  By controlling the transmission power of the transmitter, the transmission power does not become excessively large, the reception characteristics on the receiver side can be suitably maintained regardless of the wireless environment, and the power consumed by the transmission circuit is appropriate. To reduce power consumption.

  A configuration of a wireless communication apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating a configuration of a wireless multi-device according to the present invention, and FIG. 2 is a diagram illustrating a system configuration when the wireless communication device according to the present invention is applied to a tuner unit and a display unit. FIG. 4 is a flowchart for explaining processing in the wireless communication apparatus.

  In FIG. 1, a wireless communication device 1 includes an antenna switching circuit 11, a receiving circuit 12, a transmitting circuit 13, a signal processing circuit 14, a first antenna 15, a second antenna 16, and data signal input / output. And a terminal 17. The signal processing circuit 14 includes a first determination circuit 141 that determines the reception level, a second determination circuit 142 that determines the quality of the reception signal, and a control signal reading circuit 143 that reads a power control signal added to the reception signal. And a control signal adding circuit 144 for adding a power control signal to the transmission signal.

  FIG. 2 shows a configuration of a wireless communication system using the wireless communication apparatus of the present invention. The wireless communication system of the present invention is configured by facing the first wireless communication device 1-t shown in FIG. 1 and the second wireless communication device 1-m. The first wireless communication device 1-t and the second wireless communication device 1-m have the same configuration and the same function. The first wireless communication device 1-t is a device that transmits a video signal from, for example, a television tuner, and the second wireless communication device 1-m receives a video signal from, for example, the first wireless communication device 1-t. It is a device that displays video on a monitor.

  Hereinafter, the operation of the wireless communication apparatus according to the present invention will be described in detail. In this operation, it is assumed that the first wireless communication device 1-t and the second wireless communication device 1-m exchange data by wireless communication as shown in FIG.

  A transmission power control method in this wireless communication system will be described with reference to FIG. In the transmission operation in the first wireless communication apparatus 1-t, data to be transmitted is input from the data signal input / output terminal 17 to the signal processing circuit 14 of the first wireless communication apparatus 1-t. As already described, IEEE802.11a has already been standardized or IEEE802.11g is being standardized as a wireless LAN standard capable of realizing a high-speed transmission speed necessary for realizing video transmission. The signal processing circuit 14 performs MAC (Media Access Control) processing for performing signal processing such as packet processing and addition of header information on the data supplied via the data input / output terminal 17 based on each standard. After the digital modulation processing is performed, OFDM processing is performed according to the IEEE802.11a standard or the IEEE802.11g standard. The signal thus generated as a signal based on the wireless LAN standard is still low in frequency and needs to be converted into a high-frequency signal suitable for wireless communication, and is supplied to the transmission circuit 13.

  In the case of the IEEE802.11a standard, the frequency is converted to the 5 GHz band, and in the case of the IEEE802.11g standard, the frequency is converted to the 2.4 GHz band, respectively. Amplified and sent from the second antenna 16 through the antenna switching circuit 11 into the air (S1). The transmission power of the transmission circuit 13 has a configuration in which the transmission power is controlled by a transmission circuit control signal supplied from the signal processing circuit 14.

  In the reception operation in the second wireless communication device 1-m, the reception signal received by the first antenna 15 or the second antenna 16 and input to the second wireless communication device 1-m is sent to the antenna switching circuit 11. And supplied to the receiving circuit 12. The antenna switching circuit 11 is controlled by a control signal output from the signal processing circuit 14. Although a detailed description of the configuration in the reception circuit 12 is omitted, an amplification circuit and an attenuation circuit for adjusting the power of the reception signal are included, and a signal input at a radio frequency such as 5 GHz or 2.4 GHz is signaled. A circuit for frequency conversion to a frequency suitable for the processing circuit 14 is included. However, the present invention is not limited to the configuration of the receiving circuit 12 shown in FIG. The reception signal whose reception power is adjusted to an appropriate value by the reception circuit 12 and whose frequency is converted is input to the signal processing circuit 14. In the signal processing circuit 14, the received signal is reproduced as a data signal from a signal based on a communication standard such as IEEE802.11a and output from the data signal input / output terminal 17.

  The second wireless communication device 1-m receives the signal from the first wireless communication device 1-t, and determines whether or not the transmission signal is an appropriate output (S2). The signal processing circuit 14 determines the level and quality of the signal from the receiving circuit 12 to determine whether or not the output level is an appropriate level. If the output level is not appropriate, the signal processing circuit 14 increases the transmission level or the transmission level. Is added by the control addition circuit 144, and a power control signal is transmitted to the first wireless communication apparatus 1-t via the transmission circuit 13 (S3).

  In the reception operation, the received signal is received by the first antenna 15 or the second antenna 16, and these two antennas are performing a diversity operation, and the first determination circuit 141 and the second determination circuit 142 It is determined by one or both of the determination circuits whether the reception characteristic is good when the signal is received by which antenna. As a determination method, the reception power in the reception circuit 12, the reception S / N or BER (bit error rate) evaluation result in the signal processing circuit 14, and the like are used. As a result of this determination, an antenna having a suitable reception characteristic is selected, and the operation of the antenna switching circuit 11 is controlled to connect the antenna that realizes the suitable reception characteristic and the reception circuit 12.

  The antenna switching circuit 11 also controls the connection state with the antennas 15 and 16 during transmission. That is, the transmission circuit 13 is connected to the second antenna 16 at the time of transmission, and one antenna whose reception characteristics are suitable as described above is connected to the reception circuit 12 at the time of reception. As a result, for example, a high power transmission signal output from the transmission circuit 13 at the time of transmission is erroneously input to the reception circuit 12, and an element in the reception circuit 12 is prevented from being destroyed by the high power signal. is there. Further, the transmission power output from the transmission circuit 13 is prevented from leaking into the reception circuit 12, or the transmission power is not supplied to both the first antenna 15 and the second antenna 16, and the transmission power is prevented. Can be efficiently supplied to the second antenna 16.

  The first wireless communication device 1-t that has received the signal from the second wireless communication device 1-m reads the power control signal from the received signal and controls the transmission power based on this signal (S4). The video signal is output with the generated power (S5).

  The flow of transmission power control based on the determination results of the first determination circuit and the second determination circuit, which is a feature of the present invention, will be described with reference to FIG. FIG. 4 is a flowchart showing an example of processing in this embodiment.

  At the start of wireless communication, the second wireless communication device 1 -m in FIG. 2 receives the wireless signal from the first wireless communication device 1 -t by the first antenna 15 and the second antenna 16. Since it is assumed that the received power is different between the case where the signal is received by the first antenna 15 and the case where the signal is received by the second antenna 16, an antenna which can obtain a larger received signal power is selected by the antenna switching circuit 11. (S21). Since the received signal power input to the signal processing circuit 14 needs to be kept constant for the normal operation of the signal processing circuit 14, feedback control is performed on the variable gain circuit in the receiving circuit (S22).

  When the second wireless communication device 1-m is in the reception state, the first determination circuit 141 in the signal processing circuit 14 always continues to evaluate the power of the reception signal in the reception circuit 12 (S23). This is because the wireless communication environment is not constant and may always change, and the wireless communication apparatus follows this environmental change. For example, when a radio wave shield such as a human body is blocked between two wireless communication devices in communication, the reception power of the reception-side wireless communication device (for example, the second wireless communication device 1-m) decreases. On the other hand, when there is no radio wave shielding object, the received power increases, so it is necessary to detect such fluctuations in the received power.

  In the received power determination in step S23, two reference values representing an upper limit and a lower limit at which the received power is determined to be appropriate are set in advance in the first determination circuit 141, and the result of determining the received power is the reference value. First, a binary determination is made as to whether it is out of range or within range, and the result is determined. If the received signal power is within the range of the reference value in the determination result of step S23, the power control ends (S24). If the received signal power is out of the range, the value is the lower limit of the reference value. It is determined whether it is below the upper limit value of the reference value (S25). As a result of the determination, if the power of the received signal is smaller than the lower limit reference value, the process proceeds to step S26. If the received signal power is greater than the upper limit reference value, the process proceeds to step S29.

  Step S <b> 26 is a step of determining the signal quality of the reception signal output from the reception circuit in the second determination circuit 142 in the signal processing circuit 14. Here, for example, the quality of the received signal is quantified by determining the S / N ratio of the received signal, and compared with a reference value preset in the second determination circuit 142 to determine whether the signal is larger or smaller. Do. If it is determined in step S26 that the signal quality is good, the received signal power is lower than the reference signal power, but it is comprehensively determined that the signal quality is good and there is no problem in the reception characteristics, and the process is terminated. (S27).

  If it is determined in step S26 that the signal quality is poor, the received signal power is below the reference value, and the signal quality is also poor. A possible cause of the poor signal quality is that the signal power is too small compared to noise power such as background noise and thermal noise existing in nature. For example, it is conceivable that the communication power is far away and the signal power attenuation in the air propagation is large. In order to avoid this, it is sufficient to increase the signal power. However, the gain of the variable amplifier in the receiving circuit 12 may be increased. However, the gain of the variable amplifier has a limit and cannot be amplified beyond the limit. Even if it is possible, if the signal power is excessively amplified in the receiving circuit 12, even the noise power input to the second wireless communication apparatus 1-m is amplified, so that the SN ratio is not improved, or It is also conceivable that the saturation phenomenon of the amplifier circuit occurs and does not improve the reception characteristics. Therefore, in order to cope with such a situation, it is necessary to increase the transmission power of the wireless communication device on the transmission side.

  That is, if it is determined in step S26 that the signal quality is poor, the signal processing circuit transmits a transmission power control signal for increasing the transmission power on the first wireless communication apparatus 1-t side in FIG. The transmission power control signal is superimposed on the signal generated by the second wireless communication apparatus 1-m and transmitted (S28).

  The first wireless communication device 1-t in FIG. 2 to which this transmission power control signal is transmitted separates this transmission power control signal in the control signal reading circuit 143 in the signal processing circuit 14, and generates a transmission circuit control signal. The transmission circuit 13 is controlled to increase the transmission power.

  Step S29 is also a step of determining the signal quality of the reception signal output from the reception circuit in the second determination circuit 142 in the signal processing circuit. Similarly to step S26, for example, the quality of the received signal is quantified by determining the S / N ratio of the received signal, and compared with a reference value preset in the second determining circuit 142. Perform value judgment. If it is determined in step S29 that the signal quality is good, the received signal power exceeds the reference signal power, but it is comprehensively determined that the signal quality is good and there is no problem in the reception characteristics. In this case, if there is no problem in the reception characteristics even if the reception power is slightly reduced, it is preferable to reduce the transmission power in order to reduce the transmission power consumption of the first wireless communication apparatus 1-t in FIG. Therefore, when it is determined in step S29 that the signal quality is good, the control signal adding circuit 144 in the signal processing circuit 14 performs transmission power control for reducing the transmission power of the second radio communication device 1-m in FIG. A signal is generated, and this transmission power control signal is superimposed on the signal transmitted by the second wireless communication device 1-m and transmitted (S30).

  In the first wireless communication apparatus 1-t in FIG. 2 to which this transmission power control signal is transmitted, the transmission power control signal is transmitted in the control signal reading circuit 143 in the signal processing circuit 14 in the first wireless communication apparatus 1-t. Are generated, a transmission circuit control signal is generated, and the transmission circuit 13 in the first wireless communication apparatus 1-t is controlled so as to reduce the transmission power.

  If it is determined in step S29 that the signal quality is poor, the received signal exceeds the reference signal power, but the signal quality is regarded as poor. When the signal power is small, it was considered that the noise power such as thermal noise was too large compared to the received power as a cause of the degradation of the S / N ratio. However, such noise power is generally low, and the received power is the standard. If it is possible to receive with more power than the value, it is not considered to be the cause of SN degradation. In this case, it is conceivable that an interference signal other than the desired received signal is received with strong power as a cause of SN degradation. In this case, since the reception power exceeds the reference value, further increasing the transmission power of the first wireless communication device 1-t in FIG. 2 consumes the first wireless communication device 1-t on the transmission side. It is not appropriate from the viewpoint of power, and the effect of improving the SN ratio is difficult even by amplification of signal power in the receiving circuit 12 of the second wireless communication device 1-m on the receiving side. Therefore, as the operation of the second wireless communication apparatus 1-m, an interference wave detection signal for informing that the interference wave has been detected is generated, and this interference wave detection signal is superimposed on the data signal output from the data signal input / output terminal 17. And output (S31).

  As an example of the use of this jamming wave detection signal, a product such as a consumer product equipped with the first wireless communication device 1-t displays a warning screen or the like when displaying the video when the jamming wave detection signal is received. It is conceivable to take measures such as changing the frequency channel to be used, changing the antenna installation position and use location, and investigating the interference wave and studying the reduction.

  As another means, in such a state, it is conceivable that the reception power of the disturbing wave becomes weaker than the desired wave even by switching the selection of the antenna switching circuit 11 to the antenna side where the reception power is weak. There is a possibility that the reception characteristics are improved by relatively improving the ratio of the interference wave to the desired wave power. Alternatively, when the quality deterioration is not the influence of the interference wave but the distortion due to the occurrence of the saturation phenomenon in the receiving circuit, the received power input to the receiving circuit 12 is weakened by switching the antenna, and the distortion is reduced. The effect that generation | occurrence | production is suppressed can also be expected.

  The case where the first wireless communication device 1-t is in the transmission state is not particularly shown in the flowchart, but in this case, the first wireless communication device 1-t is connected to the second wireless communication device 1- in FIG. Based on the signal transmitted to m, a transmission power control signal is transmitted from the second wireless communication apparatus 1-m. The control signal reading circuit 143 in the signal processing circuit 14 in the first wireless communication device 1-t generates a transmission circuit control signal from the transmission power control signal included in the reception signal, and the transmission power of the transmission circuit 13 is set according to the content. Control.

  As described above, by determining the signal power of the received signal, and further determining the signal quality, a signal for controlling the transmission power of the communication partner is generated, and the reception power is controlled by controlling the transmission power of the communication partner. It is possible to maintain suitable reception characteristics while maintaining the power consumption of the communication partner properly without being affected by the magnitude of power and without being affected by the magnitude of transmission power due to the distance. Become. Further, when the interference wave is large and no improvement is observed by the above-described control, it is possible to construct a mechanism for generating and outputting the interference wave detection signal and taking another countermeasure.

The block diagram explaining the outline | summary of a structure of the radio | wireless communication apparatus by this invention. The figure explaining the structure of the radio | wireless communications system concerning this invention. The figure explaining the aspect of the transmission power control in this invention. The flowchart figure which shows the process example in the signal processing circuit of the radio | wireless communication apparatus of this invention. The block diagram explaining the outline | summary of a structure of the conventional radio | wireless communication apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wireless communication apparatus 11 Antenna switching circuit 12 Reception circuit 121 High frequency filter 122 Low noise amplifier 123 Variable attenuator 124 Mixer 125 Filter 126 Variable amplifier 127 Local oscillation circuit 13 Transmission circuit 14 Signal processing circuit 141 First determination circuit 142 Second Determination circuit 143 Control signal reading circuit 144 Control signal addition circuit 15 First antenna 16 Second antenna 17 Data input / output terminal

Claims (6)

In a wireless communication system that performs bidirectional communication between a first wireless communication device and a second wireless communication device,
A first wireless communication device transmits a signal, a reception circuit that receives a signal from the second wireless communication device, and a control signal reading circuit that reads a transmission power control signal from the second wireless communication device And having a function of controlling the output of the transmission circuit based on the read transmission power control signal,
The second wireless communication device has received a transmission circuit for transmitting a signal, a reception circuit for receiving a signal from the first wireless communication device, a first determination means for determining a reception level of the received signal, and Transmission power control when it is determined that second determination means for determining signal quality and the determination results of the first and second determination means need to change the transmission power of the first wireless communication device A wireless communication system having a function of creating a signal and transmitting the signal to a first wireless communication apparatus.   2. The wireless communication system according to claim 1, wherein the first wireless communication device is a means for transmitting an input video signal, and the second wireless communication device is a means for receiving the video signal and outputting it to a monitor. Communications system. A wireless communication device constituting a wireless communication system for bidirectional communication with two wireless communication devices,
A wireless communication device that transmits a signal; a reception circuit that receives a signal from a wireless communication device of a communication partner; a first determination unit that determines a reception level of the received signal; and a quality of the received signal A transmission power control signal is generated when it is determined that the determination result of the second determination means and the determination results of the first and second determination means need to change the transmission power of the wireless communication apparatus of the communication partner And transmitting to the wireless communication device of the communication partner, a control signal reading circuit for reading the transmission power control signal from the wireless communication device of the communication partner, and controlling the output of the transmission circuit based on the read transmission power control signal A wireless communication device having a function.   4. The radio communication apparatus according to claim 3, wherein at least one antenna and an antenna switching circuit for performing a circuit switching operation so as to connect the transmitting circuit and the antenna at the time of transmission and to connect the antenna and the receiving circuit at the time of reception. The first determination means and the second determination means, the function of processing the data input via the data input / output terminal during signal transmission into a form suitable for wireless communication, and the signal received by the receiving circuit And a signal processing circuit having a function of transmitting data from the data input / output terminal, and the signal processing circuit controls the antenna switching circuit and the receiving circuit based on the determination results of the first and second determination circuits. The transmission signal power control signal is generated, and the transmission signal power control signal is superimposed on the signal supplied to the transmission circuit by the signal processing circuit in the signal processing circuit. Radio communication apparatus and transmits to the radio communication device Shin partner.   5. The wireless communication apparatus according to claim 3, wherein the first determination means has two predetermined reception level reference values and compares the reception signal level with the reception level reference value to obtain 3 A wireless communication apparatus for determining a value.   6. The radio communication apparatus according to claim 5, wherein when the received signal level is predetermined and not between the two-level received level reference values, the quality of the received signal is determined by the second determining means, and the received signal level is determined. Outputs a transmission power control signal that increases the transmission level of the wireless communication device of the communication partner when the quality is lower than the lower reception level reference value and the quality is inferior, and higher than the reception level reference value with the higher reception signal level Outputs a transmission power control signal that reduces the transmission level of the wireless communication device of the communication partner when the quality is high and the quality is good, and interferes when the quality is greater than the reception level reference value of the higher reception signal level A wireless communication device that notifies a wireless communication device of a communication partner of wave detection.

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