Radio equipment and radio communication system

Abstract

To provide radio equipment and a radio communication system capable of achieving radio transmission with stable communication quality while keeping communication speed constant even when communication environment is changed due to precipitation or the like.SOLUTION: An adaptive bandwidth control unit 17 of a radio equipment 1 that performs transmission and reception oppositely measures communication quality from a reception signal or calculates an attenuation amount from reception power, and changes a frequency bandwidth so as to keep a communication channel capacity constant based on the communication quality or the attenuation amount. A radio communication system performs communication using the radio equipment 1 as a transmission device and a reception device in an opposing direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a wireless communication system that transmits and receives data from one end of a communication path, and more particularly to a wireless device and a wireless communication system that can maintain a constant channel capacity to prevent a decrease in communication speed even when the communication environment changes, thereby achieving wireless transmission with stable communication quality. [Background technology]

[0002] [Prior Art] Conventionally, there are wireless systems in which one-to-one or one-to-N wireless devices face each other to transmit and receive signals. Such wireless systems are used for broadband transmission purposes as relay circuits or entrance circuits, and often use the quasi-millimeter wave band (3 GHz to 30 GHz) or millimeter wave band (30 GHz to 300 GHz).

[0003] Quasi-millimeter and millimeter wave bands make it easier to secure wide bandwidths, which is advantageous for long-distance, high-speed transmission. Also, because the wavelengths are short, it is possible to construct compact antennas with high directivity, and by radiating only along the intended propagation path, it is possible to increase frequency utilization efficiency.

[0004] However, these frequency bands are significantly affected by radio wave attenuation due to moisture, such as from rain or snow, and conventional wireless communication systems have introduced adaptive modulation techniques as a countermeasure to this problem. The adaptive modulation method prevents communication interruptions and maintains communication when communication quality deteriorates due to factors such as rain attenuation by switching to a modulation method that enables good transmission even when the line quality of the propagation path is low.

[0005] [Example of a conventional wireless communication system configuration: Figure 9] An example of the configuration of a conventional wireless communication system using an adaptive modulation method will be described with reference to Fig. 9. Fig. 9 is an explanatory diagram showing an example of the configuration of a conventional wireless communication system. As shown in Fig. 9, the conventional wireless communication system is a system in which wireless devices A and B communicate with each other in a line-of-sight manner. Note that, here, wireless devices A and B have the same configuration, and are denoted by the same reference numerals.

[0006] The configuration of a conventional wireless device will be described. As shown in FIG. 9, the conventional wireless device 7 includes an antenna 71, a transmitter 72, a receiver 73, a modulator 74, a demodulator 75, and an adaptive modulator . The antenna 71 is a directional antenna, and the antennas 71 of the wireless devices A and B face each other and perform point-to-point transmission and reception. The transmitter 72 up-converts the transmission signal into a radio signal and outputs it to the antenna 71 . The receiving unit 73 down-converts the radio signal received by the antenna 71 and outputs the result to the demodulating unit 75 .

[0007] The modulation section 74 modulates the transmission data using the modulation method instructed by the adaptive modulation section 76 and outputs the modulated data to the transmission section 72 . The demodulation unit 75 extracts and demodulates a desired wave from the signal input from the receiving unit 73 based on the modulation method instructed by the adaptive modulation unit 76, and outputs the demodulated signal to the adaptive modulation unit 76. The adaptive modulation unit 76 calculates communication quality from the received signal input from the demodulation unit 75, selects an appropriate modulation method based on the communication quality, and notifies the modulation unit 74 and demodulation unit 75 of the selected modulation method.

[0008] In the adaptive modulation method, when the communication quality is good, the modulation level is increased to increase the transmission speed, whereas when the communication quality is poor, the modulation level is decreased, prioritizing the continuation of communication over the transmission speed. This method is effective in preventing communication channel interruptions, but communication speeds will slow down when the communication environment is poor due to precipitation or other reasons.

[0009] For example, even if high-speed transmission with a communication channel capacity of 1 Gbps is performed using the 4096QAM (Quadrature Amplitude Modulation) modulation method on a sunny day, during heavy rain the modulation method is switched to QPSK (Quadrature Phase Shift Keying) to maintain communication. As a result, even if communication can be maintained, the communication speed will be significantly reduced to 150 Mbps.

[0010] Furthermore, in conventional wireless communication systems, communication is performed using an assigned channel (frequency band), and the bandwidth used for communication is fixed.

[0011] [Related Technology] As a related prior art, there is JP 2008-167500 A, “Transmission power control method and wireless access system” (Patent Document 1).

[0012] Patent document 1 describes that in a wireless access system, a base station device measures the reception level from a subscriber base station and transmits it to the subscriber base station, which then calculates the optimal transmission power and adjusts the transmission power. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] JP 2008-167500 A Summary of the Invention [Problem to be solved by the invention]

[0014] However, in conventional wireless communication systems, although the modulation method is changed in response to changes in the communication environment to continue communication, the communication speed is not maintained constant, and there is a problem in that high-speed transmission with stable communication quality cannot be performed.

[0015] Incidentally, Patent Document 1 does not describe a configuration for changing the frequency bandwidth in response to a change in the communication environment.

[0016] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a radio device and a radio communication system that can realize radio transmission with stable communication quality while maintaining a constant communication speed even if the communication environment changes due to precipitation, etc. [Means for solving the problem]

[0017] The present invention, which aims to solve the problems of the above-mentioned conventional example, is a radio device which transmits and receives signals in a mutually opposing manner, and is characterized in that it changes the frequency bandwidth in response to changes in the communication environment so as to keep the communication path capacity constant.

[0018] Furthermore, the present invention is characterized in that in the wireless device, the communication quality of the received signal is measured to determine a change in the communication environment.

[0019] Furthermore, the present invention is characterized in that in the wireless device, the amount of attenuation of radio waves in a transmission path is calculated from a change in the level of received power, and a change in the communication environment is judged.

[0020] Furthermore, in the radio device of the present invention, a maximum value of the frequency bandwidth is stored, and the frequency bandwidth is changed so as to maintain a constant channel capacity until the maximum value is reached, and when the frequency bandwidth reaches the maximum value, the modulation method is changed while maintaining the frequency bandwidth at the maximum value.

[0021] The present invention is also characterized in that a wireless communication system for transmitting and receiving data in a mutually opposite manner, in which the above-mentioned radio device is a first device, the first device transmits information on the communication quality of a received signal or information on the amount of radio wave attenuation to a second device, and the second device changes the frequency bandwidth so as to maintain a constant communication path capacity based on the information on the communication quality of the received signal or the information on the amount of radio wave attenuation received.

[0022] In addition, the present invention is characterized in that in the above-mentioned wireless communication system, the second device is the above-mentioned radio device, which transmits information on the communication quality of the received signal or information on the amount of radio wave attenuation to the first device, and the first device controls the transmission power in the frequency bandwidth based on the information on the communication quality of the received signal or the information on the amount of radio wave attenuation transmitted from the second device, and the second device controls the transmission power in the frequency bandwidth based on the information on the communication quality of the received signal or the information on the amount of radio wave attenuation transmitted from the first device. Effect of the Invention

[0023] According to the present invention, a radio device that transmits and receives signals in a mutually opposing manner is characterized in that it changes the frequency bandwidth in response to changes in the communication environment so as to keep the communication path capacity constant. Therefore, even if there are changes in the environment due to precipitation, etc., the communication speed can be maintained, and wireless transmission can be achieved with stable communication quality.

[0024] Furthermore, according to the present invention, the radio device stores the maximum value of the frequency bandwidth, and changes the frequency bandwidth so as to maintain the communication path capacity constant until the maximum value is reached, and when the frequency bandwidth reaches the maximum value, changes the modulation method while maintaining the frequency bandwidth at the maximum value. Therefore, if there is still a risk of communication being cut off even after the frequency bandwidth is widened to the maximum value, it is possible to maintain the communication state by switching to a modulation method that allows communication even with a lower line quality.

[0025] Furthermore, according to the present invention, there is provided a wireless communication system in which transmission and reception are performed in a mutually opposite manner, in which the above-mentioned wireless device is a first device, the first device transmits information on the communication quality of the received signal or information on the amount of attenuation of radio waves to a second device, and the second device changes the frequency bandwidth so as to maintain the communication path capacity constant based on the information on the communication quality of the received signal or the information on the amount of attenuation of radio waves received. Therefore, even if there is a change in the environment due to precipitation or the like, the communication speed can be maintained, and the functions of measuring the communication quality or the amount of attenuation and changing the frequency bandwidth can be shared between the transmitting device and the receiving device, thereby simplifying the configuration and processing of each wireless device. [Brief description of the drawings]

[0026] [Figure 1] FIG. 2 is an explanatory diagram showing the relationship between received power and channel capacity in a line-of-sight environment. [Diagram 2] FIG. 2 is an explanatory diagram showing an overview of frequency bandwidth control in the present radio device. [Diagram 3] FIG. 2 is an explanatory diagram showing the configuration of a first system. [Figure 4] FIG. 2 is an explanatory diagram showing a configuration example (1) of an adaptive bandwidth control unit. [Diagram 5] FIG. 13 is an explanatory diagram showing a configuration example (2) of an adaptive bandwidth control unit. [Figure 6] FIG. 2 is a schematic explanatory diagram of frequency bandwidth tables (1) and (2). [Figure 7] FIG. 11 is an explanatory diagram showing the configuration of a second system. [Figure 8] FIG. 13 is an explanatory diagram showing the configuration of a third system. [Figure 9] FIG. 1 is an explanatory diagram illustrating an example of the configuration of a conventional wireless communication system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. [Outline of the embodiment] A radio device according to an embodiment of the present invention (this radio device) is a radio device that transmits and receives signals in a mutually opposing manner, and changes the frequency bandwidth in accordance with the communication environment so as to maintain a constant communication speed even if the communication environment changes.Even if the communication environment deteriorates due to precipitation, etc., wireless transmission can be performed with stable communication quality while maintaining the communication speed.

[0028] Moreover, the wireless communication system according to the embodiment of the present invention (the present system) is a system that includes the present wireless devices as a transmitting device and a receiving device and performs line-of-sight communication with each other, and there are first to third systems as described later.

[0029] [Received power and channel capacity: Figure 1] Before describing the configuration of this system, the relationship between the received power and the channel capacity in a line-of-sight environment will be described with reference to Fig. 1. Fig. 1 is an explanatory diagram showing the relationship between the received power and the channel capacity in a line-of-sight environment. Figure 1 shows the relationship between received power and channel capacity for various frequency bandwidths. In this specification, the width of frequencies actually used for communication in communication bands such as the quasi-millimeter wave band (3 GHz to 30 GHz) and the millimeter wave band (30 GHz to 300 GHz) is referred to as the frequency bandwidth (used frequency bandwidth).

[0030] FIG. 1 shows the relationship between the received power and the channel capacity when the frequency bandwidth is 50 MHz, 100 MHz, 200 MHz, and 400 MHz. As shown in FIG. 1, when a specific channel capacity is to be ensured, the wider the frequency bandwidth, the smaller the required received power becomes. In addition, if the communication channel environment is good, it is possible to maintain a certain communication channel capacity even if the frequency bandwidth is narrow. Here, 50 MHz is the minimum unit of frequency bandwidth.

[0031] For example, if the desired communication capacity is 1 Gbps, when the frequency bandwidth is 50 MHz, a receiving power of -37 dBm or more is required. However, when the frequency bandwidth is 100 MHz, the required receiving power is -64 dBm, and the desired communication channel capacity can be secured even if the receiving power is 27 dBm lower than in the case of 50 MHz. In other words, if communication is possible with a frequency bandwidth of 50 MHz on a clear day, then if communication is performed with a frequency bandwidth of 100 MHz, it will be possible to maintain a communication channel capacity of 1 Gbps until radio wave attenuation due to precipitation, etc. reaches 27 dBm.

[0032] Similarly, when the frequency bandwidth is 200 MHz, the required receiving power is -76 dBm or more, and the communication path capacity can be maintained until the attenuation of the radio waves in the transmission path reaches 39 dBm compared to when the weather is fine. Furthermore, when the frequency bandwidth is set to 400 MHz, the required received power is -81 dBm or more, and communication can be performed at the same transmission speed while maintaining the same channel capacity until the attenuation reaches 44 dBm.

[0033] This radio and system takes advantage of this fact by adaptively controlling the frequency bandwidth in response to changes in communication quality due to changes in the communication environment, thereby keeping the communication path capacity constant even during rainfall.

[0034] [Overview of frequency bandwidth control in this radio: Figure 2] Next, an overview of frequency bandwidth control in this radio device will be described with reference to Fig. 2. Fig. 2 is an explanatory diagram showing an overview of frequency bandwidth control in this radio device. In this wireless device, under conditions where the maximum transmission power is fixed, the frequency bandwidth is controlled based on the deterioration of the communication environment due to weather, taking into account attenuation due to rainfall or snowfall.

[0035] As shown in Figure 2, there is no rain attenuation when the weather is clear or cloudy, so the frequency bandwidth is set to the minimum of 50 MHz, and is controlled to, for example, 100 MHz for normal rain, 200 MHz for heavy rain, and 400 MHz for torrential rain.

[0036] As the precipitation intensity increases, the rain attenuation also increases, so the frequency bandwidth is widened to compensate for this and maintain the communication channel capacity. This makes it possible to ensure a certain communication path capacity and maintain communication speed even if there is rain attenuation.

[0037] [Configuration of the first system: Figure 3] The first system in this system will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram showing the configuration of the first system. As shown in Fig. 3, the first system is one in which radio devices A and B having the same configuration communicate with each other wirelessly. Both radio devices A and B are the present radio devices, and in Fig. 3, radio devices A and B are given the same reference numerals.

[0038] As shown in FIG. 3, the radio 1 used as the radio A and the radio B of the first system includes an antenna 11, a transmitting unit 12, a modulating unit 14, a demodulating unit 15, and an adaptive bandwidth control unit 17. Of these, antenna 11 is similar to the conventional radio device shown in Figure 9, and the basic operations of transmitter 12, receiver 13, modulator 14 and demodulator 15 are similar to those of the conventional radio device shown in Figure 9. However, a feature of this radio device is that it performs processing based on the frequency bandwidth selected and notified by adaptive bandwidth control unit 17.

[0039] The adaptive bandwidth control unit 17 is a characteristic part of this radio device, and selects an appropriate frequency bandwidth in response to changes in the environment, and controls the frequency bandwidth in the transmission unit 12, reception unit 13, modulation unit 14, and demodulation unit 15. The adaptive bandwidth control unit 17 selects an appropriate frequency bandwidth based on the communication quality of the received signal input from the demodulation unit 15 or a change in the power level of the received signal. The adaptive bandwidth control unit 17 will be described later. In the first system, the radio device A and the radio device B each independently control the frequency bandwidth.

[0040] [Configuration example (1) of the adaptive bandwidth control unit 17: Figure 4] Next, a configuration example (1) of the adaptive bandwidth control unit 17 will be described with reference to Fig. 4. Fig. 4 is an explanatory diagram showing a configuration example (1) of the adaptive bandwidth control unit. As shown in FIG. 4, the adaptive bandwidth control unit 17 in the configuration example (1) is assumed to be an adaptive bandwidth control unit 17a.

[0041] The adaptive bandwidth control unit 17 a includes a communication quality measurement unit 171 and a bandwidth selection / switching control unit 172 . The communication quality measuring unit 171 measures the communication quality based on the input signal (desired wave signal) from the demodulation unit 15 and the noise level. The communication quality is evaluated by detecting the level of the desired signal and the level of the noise component, and using the ratio (such as the signal-to-noise ratio).

[0042] The bandwidth selection switching control unit 172 selects (selects) a frequency bandwidth corresponding to the communication quality measured by the communication quality measurement unit 171 from a plurality of frequency bandwidths stored in advance. Specifically, the bandwidth selection switching control unit 172 is provided with a frequency bandwidth table (1) in which communication quality and frequency bandwidth are associated in advance, as shown in FIG. 6(a) described later, and selects a frequency bandwidth based on the table.

[0043] [Configuration example (2) of the adaptive bandwidth control unit 17: Figure 5] Next, a configuration example (2) of the adaptive bandwidth control unit 17 will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram showing a configuration example (2) of the adaptive bandwidth control unit. As shown in FIG. 5, the adaptive bandwidth control unit 17 in the configuration example (2) is assumed to be an adaptive bandwidth control unit 17b.

[0044] As shown in FIG. 5, the adaptive bandwidth control unit 17b includes a received power measurement attenuation calculation unit 173 and a bandwidth selection switching control unit 174. The received power measurement and attenuation amount calculation unit 173 measures the received power of the received signal input from the demodulation unit 15, and calculates the amount of attenuation by comparing it with the received power in a clear sky in a good communication environment. When there is rain attenuation, the amount of attenuation becomes large.

[0045] The bandwidth selection switching control unit 174 selects a frequency bandwidth corresponding to the attenuation calculated by the received power measurement attenuation calculation unit 173 from a plurality of frequency bandwidths stored in advance. Specifically, the bandwidth selection switching control unit 174 is provided with a frequency bandwidth table (2) in which the amount of attenuation and the frequency bandwidth are previously associated with each other, as shown in FIG. 6(b) described later, and selects the frequency bandwidth based on the table.

[0046] [Frequency bandwidth table: Figure 6] The frequency bandwidth tables (1) and (2) will be described with reference to Fig. 6. Fig. 6 is a schematic explanatory diagram of the frequency bandwidth tables (1) and (2). As shown in FIG. 6(a), the frequency bandwidth table (1) stores communication qualities and corresponding frequency bandwidths in association with each other.

[0047] Specifically, the frequency bandwidth table (1) stores the frequency bandwidth required to maintain a desired communication channel capacity according to the communication quality, and a narrow frequency bandwidth is associated with good communication quality, and a wide frequency bandwidth is associated with poor communication quality.

[0048] Here, the frequency bandwidth is divided into four stages: 50 MHz, 100 MHz, 200 MHz, and 400 MHz, and a frequency bandwidth of 50 MHz corresponds to communication quality A or higher, 100 MHz to B or higher but less than A, 200 MHz to C or higher but less than B, and 400 MHz to communication quality less than C. A, B, and C are communication quality values ​​obtained by actual measurement or simulation.

[0049] Then, the bandwidth selection switching control unit 174 refers to the frequency table (1) and selects a frequency bandwidth corresponding to the stage (range) of communication quality that includes the communication quality measured by the communication quality measurement unit 171. 400 MHz is the upper limit of the available frequency bandwidth, and it is not possible to set a frequency bandwidth wider than this.

[0050] As shown in FIG. 6(b), the frequency bandwidth table (2) stores the amount of attenuation and the frequency bandwidth in association with each other. In the frequency bandwidth table (2), as shown in Fig. 1, the attenuation allowable for each frequency bandwidth is known in order to obtain a desired communication channel capacity, and the frequency bandwidth corresponding to the calculated attenuation is stored based on this. A small amount of attenuation is associated with a narrow frequency bandwidth, and a large amount of attenuation is associated with a wide frequency bandwidth.

[0051] In the example of Fig. 6(b), when the attenuation is less than P, the frequency bandwidth is 50 MHz, when it is equal to or greater than P but less than Q, it is 100 MHz, when it is equal to or greater than Q but less than R, it is 200 MHz, and when it is equal to or greater than R, it is 400 MHz. P, Q, and R are numerical values ​​of the attenuation obtained by actual measurement or simulation. In the frequency bandwidth table (2), the attenuation and the frequency bandwidth are associated with each other so that switching is performed at an attenuation smaller than the theoretical attenuation, with a margin larger than the allowable range shown in FIG. As shown in FIG. 1, in the case of a frequency bandwidth of 100 MHz, theoretically, a communication path capacity of 1 Gbps can be maintained up to -64 dBm, but in the frequency bandwidth table (2), it is stored so that switching occurs at, for example, -61 dBm.

[0052] When this system is started up, it starts operating at 50 MHz, which is the smallest unit of frequency bandwidth, and then selects an appropriate frequency bandwidth depending on the environment. Specifically, the adaptive bandwidth control unit 17 periodically measures the communication quality or calculates the amount of attenuation, selects an appropriate frequency bandwidth, and controls the frequency bandwidth of each unit.

[0053] This makes it possible to change the frequency bandwidth accordingly, even if the propagation path environment changes due to precipitation, etc., and to maintain the desired communication path capacity and continue communications with stable communication quality without reducing the communication speed. Furthermore, when the precipitation stops and the propagation path environment returns to a good state, the original frequency bandwidth can be quickly restored, thereby preventing the wasteful use of frequency resources.

[0054] Furthermore, the adaptive bandwidth control unit 17 of the radio device 1 may control the frequency bandwidth and the transmission power in response to changes in the communication environment. Specifically, the adaptive bandwidth control unit 17 has a table that stores communication quality or attenuation in association with transmission power, similar to the above-mentioned frequency bandwidth table, and selects appropriate transmission power based on the communication quality measured from the received signal or the calculated attenuation.

[0055] Furthermore, if communication quality does not improve even when communication is performed at the maximum selectable frequency bandwidth (400 MHz), the adaptive bandwidth control unit 17 of the radio device 1 performs adaptive modulation while maintaining the frequency bandwidth at its upper limit value. In other words, the adaptive bandwidth control unit 17 has the same function as the conventional adaptive modulation unit 76 shown in FIG. As a result, if there is a risk of communication being cut off even when the frequency bandwidth is widened to its upper limit due to rain attenuation, etc., the communication state can be maintained by switching to a slower modulation method.

[0056] In addition, in the first system, radio device A and radio device B perform the same processing and independently control the frequency bandwidth of their own devices, so that they can be configured using the same device and can be realized at low cost.

[0057] [Configuration of the second system: Figure 7] Next, the second system in this system will be described with reference to Fig. 7. Fig. 7 is an explanatory diagram showing the configuration of the second system. The second system has two opposing radio devices sharing the functions of measuring communication quality or calculating attenuation in the adaptive bandwidth control unit 17 of the radio device 1 in the first system, and selecting a frequency bandwidth based on the communication quality or attenuation.

[0058] In other words, in the second system, one of the radio devices communicating with the other measures (calculates) the communication quality or the amount of attenuation and notifies the other of the measured (calculated) communication quality or amount of attenuation, and the other radio device selects a frequency bandwidth based on the notified communication quality or amount of attenuation and controls each part of its own device, while notifying the other radio device of the selected frequency bandwidth, and the other radio device controls each part with the notified frequency bandwidth. In the following, an example will be described in which the frequency bandwidth is controlled based on the communication quality, but the same control is also performed in the case where the frequency bandwidth is controlled based on the amount of attenuation.

[0059] As shown in Fig. 7, in the second system, a wireless device A (wireless device 2) and a wireless device B (wireless device 3) communicate with each other. Note that the wireless device 2 corresponds to the first device recited in the claims, and the wireless device 3 corresponds to the second device recited in the claims. The wireless device 2 constituting the wireless device A includes an adaptive bandwidth control unit 27 that includes a communication quality measurement unit 271 and a bandwidth switching control unit 272. However, the adaptive bandwidth control unit 27 of the wireless device 2 does not include a function of selecting a frequency bandwidth based on communication quality. Here, the bandwidth switching control section 272 controls the frequency bandwidth of each section in the own device according to the notified value of the frequency bandwidth.

[0060] Moreover, the radio device 3 constituting the radio device B includes a bandwidth selection switching control unit 372 in the adaptive bandwidth control unit 37, but does not include a function for measuring communication quality from a received signal. The bandwidth selection / switching control unit 372 selects a frequency bandwidth based on information about communication quality, and notifies each unit in the device of the selected frequency bandwidth, thereby controlling the frequency bandwidth.

[0061] The operation of the second system will now be described. In the adaptive bandwidth control unit 27 of the wireless device 2 , when the communication quality measurement unit 271 measures the communication quality, the measurement value of the communication quality is transmitted to the wireless device 3 via the modulation unit 24 and the transmission unit 22 .

[0062] In radio device 3, when communication quality information is received from radio device 2 and the communication quality value is input to the adaptive bandwidth control unit 37 via the demodulation unit 35, the bandwidth selection switching control unit 372 selects a frequency bandwidth by referring to the frequency bandwidth table based on the communication quality value received from radio device 2. Then, the adaptive bandwidth control unit 37 of the wireless device 3 notifies the transmitting unit 32, the receiving unit 33, the modulating unit 34, and the demodulating unit 35 of the selected frequency bandwidth, thereby controlling the frequency bandwidth of each unit.

[0063] The adaptive bandwidth control unit 37 of the radio device 3 transmits information on the selected frequency bandwidth to the radio device 2 via the modulation unit 34 and the transmission unit 32. In the adaptive bandwidth control unit 27 of the wireless device 2, when frequency bandwidth information is input from the demodulation unit 25, the bandwidth switching control unit 272 controls the frequency bandwidth of the transmission unit 22, the reception unit 23, the modulation unit 24 and the demodulation unit 25. In this manner, the operation of the second system is carried out.

[0064] Before starting operation in the second system, the radio device 3 may notify the radio device 2 of the selected frequency bandwidth, and after receiving a response to the notification from the radio device 2, control may be performed in the selected frequency bandwidth, and the radio device 2 may also transition to control in the notified frequency band.

[0065] In the second system, the frequency bandwidth control function is shared between two opposing radio devices, which reduces the load on each radio device compared to the first system.

[0066] [Application example of the second system] In this embodiment, the wireless devices A and B share the functions. However, as an application example of the second system, one may be configured as the master and the other as the slave to simplify the control of the other. Specifically, instead of the bandwidth switching control unit 272 of the wireless device 2, a bandwidth selection switching control unit that also selects a frequency bandwidth is provided.

[0067] Then, the adaptive bandwidth control unit 271 of the wireless device 2 measures the communication quality and transmits the information to the wireless device 3, and also selects and holds the frequency bandwidth based on the communication quality. Based on the information on the communication quality received from the wireless device 2, the wireless device 3 selects a frequency bandwidth, controls each unit, and transmits a response signal indicating a reception confirmation to the wireless device 2. When wireless device 2 receives the response signal from wireless device 3, adaptive bandwidth control unit 27 controls the frequency bandwidth of each unit in the wireless device 2 with the frequency bandwidth it holds. This is how the second system application operates.

[0068] In the application example of the second system, the slave wireless device (here, wireless device 3) does not need to measure communication quality or calculate attenuation amount, and can be realized with a simple configuration.

[0069] [Third system: Figure 8] Next, a third system in this system will be described with reference to Fig. 8. Fig. 8 is an explanatory diagram showing the configuration of the third system. In the third system, wireless device B, which receives information on communication quality (or attenuation) from wireless device A, also measures the communication quality (or calculates the attenuation) from the received signal, and selects the frequency bandwidth taking into consideration both the received communication quality value and the communication quality measurement value that it has independently measured.

[0070] As shown in Fig. 8, in the third system, radio 4 constituting radio A and radio 5 constituting radio B have the same configuration and are equivalent to the configuration of radio 1 shown in Fig. 3, but their operations are partially different. Note that radio 4 corresponds to the first device recited in the claims, and radio 5 corresponds to the second device recited in the claims. The operation of the third system will be described with reference to FIG. In the third system, as in the second system, in radio device A (radio device 4), the adaptive bandwidth control unit 47 measures the communication quality of the received signal using the communication quality measurement unit 471, and notifies information about the measured communication quality to radio device B (radio device 5).

[0071] In the wireless device 5, the adaptive bandwidth control unit 57 stores the received communication quality value. Moreover, in the adaptive bandwidth control unit 57 of the wireless device 5, the communication quality measurement unit 571 measures the communication quality of the signal received from the wireless device 4 and stores it. The bandwidth selection and switching control unit 572 then compares the received communication quality value with the communication quality value measured by the device itself, and if the two are equivalent, selects a frequency bandwidth corresponding to the communication quality and notifies each unit in the device of the frequency bandwidth. Specifically, the bandwidth selection and switching control unit 572 determines that the two are equivalent when the difference between them is within a preset range.

[0072] In addition, in the wireless device 5, if the bandwidth selection switching control unit 572 determines that the received communication quality value is not equivalent to the communication quality value measured by the device itself, a malfunction of one of the devices is suspected, and an alarm is output to notify the system administrator.

[0073] Furthermore, the wireless device 5 may transmit the communication quality measured by itself to the wireless device 4. This enables the wireless device 4 to similarly detect device malfunctions. Furthermore, the wireless device 5 and the wireless device 4 may each be configured to control the transmission power based on the value of the communication quality or the amount of attenuation received from the other device.

[0074] In the third system, the wireless device 5 (and wireless device 4) can select a more appropriate frequency bandwidth by taking into consideration both the communication quality notified by the other party and the communication quality measured by the wireless device itself based on a received signal, and if there is a difference between the two communication qualities, an administrator is notified, making it possible to quickly detect equipment malfunctions, etc.

[0075] Before starting operation in the above-mentioned third system, the radio device 4 or the radio device 5 may notify the other radio device of the selected frequency bandwidth, and after receiving a response to the notification from the other radio device, may transition to control in the selected frequency bandwidth.

[0076] [Effects of the embodiment] According to this radio device and system, the adaptive bandwidth control unit 17 of the radio device 1 measures the communication quality or the amount of attenuation from the received signal and, based on that, changes the frequency bandwidth so as to keep the communication path capacity constant. This has the effect of enabling wireless transmission with stable communication quality while maintaining the communication speed without reducing the communication speed, even if the communication environment deteriorates due to precipitation, etc. [Industrial Applicability]

[0077] The present invention is suitable for a radio device and a radio communication system that can realize radio transmission with stable communication quality while maintaining a constant communication speed even if the communication environment changes due to precipitation or the like. [Explanation of symbols]

[0078] 1,2,3,4,5,7...radio device, 11,21,31,41,51,71...antenna, 12,22,32,42,52,72...transmitter, 13,23,33,43,53,73...receiver, 14,24,34,44,54,74...modulator, 15,25,35,45,55,75...demodulator, 76...adaptive modulator, 171,271,471,571...communication quality measurement unit, 172,174,372,472,572...bandwidth selection switching control unit, 173...received power measurement attenuation calculation unit, 272...bandwidth switching control unit

Claims

1. A wireless device that transmits and receives signals in a mutually opposite manner, A radio device that changes the frequency bandwidth in response to changes in the communication environment so as to maintain a constant communication path capacity.

2. 2. The wireless device according to claim 1, wherein the wireless device measures communication quality of a received signal to judge a change in the communication environment.

3. 2. The wireless device according to claim 1, wherein the attenuation of radio waves in a transmission path is calculated from a change in a level of received power to determine a change in a communication environment.

4. 4. A radio device according to claim 1, further comprising: a maximum value of a frequency bandwidth stored in a memory; a frequency bandwidth change unit that changes the frequency bandwidth so as to maintain a constant channel capacity until the maximum value is reached; and, when the frequency bandwidth reaches the maximum value, a modulation method is changed while maintaining the frequency bandwidth at the maximum value.

5. A wireless communication system for transmitting and receiving data in a mutually opposite manner, A radio device according to claim 2 or 3 is used as a first device, The first device transmits information on the communication quality of the received signal or information on the amount of attenuation of the radio wave to a second device; A wireless communication system, characterized in that the second device changes a frequency bandwidth so as to maintain a constant communication path capacity based on information on communication quality of a received signal or information on an amount of attenuation of radio waves.

6. The second device is a radio device according to claim 2 or 3, and transmits information on the communication quality of the received signal or information on the amount of attenuation of the radio wave to the first device; The first device controls a transmission power in a frequency bandwidth based on information on a communication quality of a received signal transmitted from the second device or information on an amount of attenuation of radio waves; The wireless communication system according to claim 5, characterized in that the second device controls the transmission power in a frequency bandwidth based on information on the communication quality of the received signal transmitted from the first device or information on the amount of radio wave attenuation.

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