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WO2024189797A1 - Radio relay system, radio relay device, radio relay method, and radio relay program - Google Patents

Radio relay system, radio relay device, radio relay method, and radio relay program Download PDF

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Publication number
WO2024189797A1
WO2024189797A1 PCT/JP2023/009942 JP2023009942W WO2024189797A1 WO 2024189797 A1 WO2024189797 A1 WO 2024189797A1 JP 2023009942 W JP2023009942 W JP 2023009942W WO 2024189797 A1 WO2024189797 A1 WO 2024189797A1
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WIPO (PCT)
Prior art keywords
modulation
transmitting
polarization
demodulation
transmitting device
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PCT/JP2023/009942
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French (fr)
Japanese (ja)
Inventor
一夫 大坂
利文 宮城
武 鬼沢
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日本電信電話株式会社
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Priority to PCT/JP2023/009942 priority Critical patent/WO2024189797A1/en
Publication of WO2024189797A1 publication Critical patent/WO2024189797A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes

Definitions

  • This disclosure relates to a wireless relay system, a wireless relay device, a wireless relay method, and a wireless relay program, and in particular to a wireless relay system, a wireless relay device, a wireless relay method, and a wireless relay program that are suitable for reducing the effects of quality degradation due to fading.
  • a method of relaying wireless signals uses multiple frequency channels to transmit large volumes of data.
  • wireless signals When wireless signals are propagated over long distances, or in environments where the propagation path of the wireless signals is over the ocean, the wireless signals may be affected by fading during the propagation process, causing significant degradation of the transmission characteristics.
  • SD Space Diversity
  • FIG. 1 is a diagram for explaining the outline of a wireless relay system using SD reception.
  • the system shown in FIG. 1 includes a transmitting device 10.
  • the transmitting device 10 includes a transmitting antenna 12.
  • FIG. 1 shows an example in which the transmitting device 10 transmits wireless signals using four channels #1 to #4.
  • all four channels #1 to #4 use the 64QAM (Quadrature Amplitude Modulation) modulation method to transmit radio signals using vertical polarization (hereinafter referred to as "V polarization").
  • V polarization vertical polarization
  • the receiving device 14 is installed at a location far away from the transmitting device 10.
  • the receiving device 14 is equipped with multiple antennas installed at different heights, in this example, three antennas 16, 18, and 20.
  • the antennas 16, 18, and 20 are typically composed of parabolic antennas with an aperture of 3 m to 4 m.
  • the effects of fading change depending on the state of the propagation path of the radio signal. For example, due to weather conditions, etc., conditions may be good around antenna 16, which is installed at the highest position, but conditions may be unsuitable for wireless communication around antenna 20, which is installed at the lowest position. Similarly, the opposite situation may occur depending on weather conditions, etc.
  • the receiving antennas 16, 18, 20 are installed at different heights, even if one of the antennas is affected by fading, the other antennas may be able to receive the radio signal well. For this reason, when the system shown in Figure 1 detects the effects of fading on any of the four channels #1 to #4, it switches the antenna that receives the signal of that channel to the antenna with the best conditions.
  • Figure 1 shows an example in which the antennas receiving the signals of channels #2 and #3 are switched when these channels are affected by fading. As a result, as shown in Figure 1, a rate of 400 Mbps is maintained for all channels #1 to #4 even after the effects of fading have occurred. In this way, SD reception technology can provide excellent resistance to fading.
  • the first objective of this disclosure is to provide a wireless relay system that achieves excellent resistance to fading without imposing a significant installation burden in order to solve the above problems.
  • the second objective of this disclosure is to provide a wireless relay device that achieves excellent resistance to fading without imposing a significant installation burden.
  • the third objective of this disclosure is to provide a wireless relay method that achieves excellent resistance to fading without imposing a significant installation burden.
  • the fourth objective of this disclosure is to provide a wireless relay program that achieves excellent resistance to fading without imposing a significant installation burden.
  • a first aspect is a wireless relay system including a transmitting device that transmits a wireless signal and a receiving device that receives the wireless signal from the transmitting device,
  • the transmitting device includes: Equipped with a transmitting antenna that supports both front and back polarization, a first modulation process for transmitting a modulated signal with a first multi-level number in the front polarization; A second modulation process of transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarization and the back polarization; a process of switching from the first modulation process to the second modulation process in response to a switching request from the receiving device; and a process of returning the second modulation process to the first modulation process in response to a return request from the receiving device,
  • the receiving device includes: a receiving antenna corresponding to the front polarized wave and the back polarized wave, a first demodulation process for demodulating a modulated signal by the first multi-level number transmitted
  • a third aspect is a wireless relay device that transmits a wireless signal to be relayed to a receiving device, comprising: Equipped with a transmitting antenna that supports both front and back polarization, a first modulation process for transmitting a modulated signal with a first multi-level number in the front polarization; A second modulation process of transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarization and the back polarization; a process of switching from the first modulation process to the second modulation process in response to a switching request from the receiving device; It is desirable to configure the modulation device to execute a process of restoring the second modulation process to the first modulation process upon receiving a restoration request from the receiving device.
  • a fourth aspect is a wireless relay method for relaying a wireless signal using a transmitting device and a receiving device that receives a wireless signal from the transmitting device, the method comprising: The transmitting device, performing a first modulation to transmit a modulated signal with a first multilevel number in a front polarization; performing a second modulation for transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarized wave and the back polarized wave; switching the first modulation to the second modulation in response to a switching request from the receiving device; restoring the second modulation to the first modulation upon receiving a restoration request from the receiving device; The receiving device, performing a first demodulation for demodulating a modulated signal by the first multilevel number transmitted by the front polarization; performing a second demodulation to demodulate the modulated signal by the second multi-level number transmitted by using both the front polarization and the back polarization; when an influence of fading exceeding a judgment
  • a fifth aspect is a wireless relay program for relaying a wireless signal received from a transmitting device to a receiving device, the program comprising:
  • the receiving device includes: A receiving antenna that supports front and back polarization; a processor;
  • the processor a first demodulation process for demodulating a modulated signal having a first multilevel number transmitted by the front polarization;
  • a second demodulation process for demodulating a modulated signal transmitted using both the front polarization and the back polarization, the modulated signal being modulated by a second multi-level number that is smaller than the first multi-level number;
  • a process of requesting the transmitting device to switch a first modulation process for transmitting a modulated signal with the first multi-level number in the front polarization to a second modulation process for transmitting a modulated signal with the second multi-level number in both the front polarization and the back polarization when an influence of fading exceeding a judgment criterion is found in the wireless signal received from the transmitting device,
  • a sixth aspect is a wireless relay program for causing a transmitting device to transmit a wireless signal to be relayed toward a receiving device, the program comprising:
  • the transmitting device includes: A transmitting antenna corresponding to front and back polarization; a processor;
  • the processor a first modulation process for transmitting a modulated signal with a first multi-level number in the front polarization;
  • the computer readable program be capable of executing the above-mentioned method.
  • FIG. 1 is a diagram for explaining an overview of a wireless relay system using SD reception.
  • FIG. 1 is a diagram for explaining an overview of a wireless relay system according to a first embodiment of the present disclosure.
  • FIG. 3 is a block diagram for explaining the configurations of the transmitting device and the receiving device shown in FIG. 2 .
  • a first configuration example regarding the installation of the transmitting device and the receiving device shown in FIG. 3 will be described.
  • a second configuration example regarding the installation of the transmitting device and the receiving device shown in FIG. 3 will be described.
  • 1 is a flowchart for explaining the flow of a series of processes performed by a receiving device in the first embodiment of the present disclosure.
  • 1 is a flowchart for explaining the flow of a series of processes performed by a transmitting device in the first embodiment of the present disclosure.
  • FIG. 2 is a diagram for explaining an overview of a wireless relay system according to the first embodiment of the present disclosure.
  • the system according to the present embodiment includes a transmitting device 30.
  • the transmitting device 30 includes a transmitting antenna 32.
  • Fig. 2 shows an example in which the transmitting device 30 transmits wireless signals using four channels #1 to #4.
  • Transmitting device 30 can use the 64QAM modulation method for each of the four channels #1 to #4.
  • V-polarized radio signals can be transmitted using channels #1 to #4.
  • the transmitting device 30 can transmit radio signals in parallel using both V polarization and its reverse polarization, i.e., horizontal polarization (hereinafter referred to as "H polarization”), which is a polarization orthogonal to the V polarization.
  • V polarization and its reverse polarization, i.e., horizontal polarization (hereinafter referred to as "H polarization”), which is a polarization orthogonal to the V polarization.
  • the required C/N Carrier to Noise
  • BER bit error rate
  • the transmitting device 30 of this embodiment transmits signals modulated with 64QAM in V polarization in all of channels #1 to #4.
  • this method is referred to as “64QAM-V modulation.”
  • the modulation method is switched to 16QAM in that channel, and transmission using both V polarization and H polarization begins.
  • this method is referred to as "16QAM-VH modulation.”
  • Figure 2 shows an example in which the effects of fading were observed in channel #2 and channel #3, and the transmission method for those channels was switched from 64QAM-V modulation to 16QAM-VH modulation. This switch increases the fading resistance of channels #2 and #3 by 5 dB, thereby reducing the effects of degradation due to fading.
  • the system of this embodiment includes a receiving device 34.
  • the receiving device 34 is installed at a location far away from the transmitting device 10.
  • the receiving device 14 includes an antenna 36.
  • the antenna 36 has the function of receiving both V-polarized waves and H-polarized waves.
  • the receiving device 34 analyzes the radio signals received by the antenna 36 and determines whether or not quality degradation due to fading has occurred for each of channels #1 to #4. If the result shows that there is no effect of fading for any of the channels, the receiving device 34 demodulates the received signals for all of channels #1 to #4 using a method compatible with 64QAM-V modulation. Hereinafter, this demodulation will be referred to as "64QAM-V demodulation.”
  • processing is performed to change the modulation method and transmission polarization for that channel. Specifically, information about the channel for which the effects of fading have been found is notified to the transmitting device 30, and at the same time, the radio signal decoding method is changed from 64QAM-V demodulation to a demodulation method compatible with 16QAM-VH modulation.
  • this demodulation is referred to as "16QAM-VH demodulation.”
  • the transmitting device 30 switches from the 64QAM-V modulation method to the 16QAM-VH modulation method. This allows the transmission method of the transmitting device 30 and the demodulation method of the receiving device 34 to be switched at a synchronized timing.
  • the receiving device 34 monitors the communication quality of the channel for which the demodulation method has been switched. Then, when the conditions for transmission and reception in 64QAM are restored, it sends a request to the transmitting device 30 to resume. At the same time, it reverts the radio signal decoding method from 16QAM-VH demodulation to 64QAM-V demodulation.
  • the transmitting device 30 In response to the reversion request, the transmitting device 30 reverts from the 16QAM-VH modulation method to the 64QAM-V modulation method. This allows the transmitting device 30 and the receiving device 34 to revert to the transmission method and demodulation method at synchronized timing.
  • Fig. 3 is a block diagram for explaining the configuration of the transmitting device 30 and the receiving device 34.
  • the transmitting device 30 includes a user interface (I/F) unit 40 that receives a user signal to be relayed.
  • the user I/F unit 40 performs processing for managing a connection with a transmission source of the user signal, etc.
  • the user I/F unit 40 provides the received user signal to the framing unit 42.
  • the framing unit 42 performs processes such as buffering, bit division, mapping, and packetization of the user signal.
  • the packets generated by the framing unit 42 are provided to the MOD unit 44.
  • the MOD unit 44 performs data modulation processing using a specified modulation method, as well as processing to change the modulation method to be used.
  • the MOD unit 44 also has a function for transmitting modulated data using V polarization and a function for transmitting using H polarization.
  • the modulation methods used by the MOD unit 44 are a 64QAM method and a 16QAM method. Specifically, the MOD unit 44 selectively executes processing corresponding to the above 64QAM-V modulation and processing corresponding to the above 16QAM-VH modulation.
  • the modulated data generated by the MOD unit 44 is provided to the RF unit 46.
  • the RF unit 46 performs transmit AMP (amplification) processing, filter processing, monitoring processing, etc.
  • the RF unit 46 also has a function compatible with V polarization and a function compatible with H polarization.
  • the transmit AMP and other processing is realized by the function compatible with V polarization.
  • the 16QAM-VH modulation method is used, the above processing is realized by both the function compatible with V polarization and the function compatible with H polarization.
  • the signal generated by the RF unit 46 is transmitted in the form of a wireless signal via the antenna 32. In this embodiment, this signal is transmitted on four channels #1 to #4 as described above.
  • the RF unit 46 also has a function compatible with V polarization and a function compatible with H polarization.
  • the transmitting device 30 further includes a monitoring control unit 48.
  • the monitoring control unit 48 transmits and receives control signals between the framing unit 42, the MOD unit 44, and the RF unit 46.
  • the monitoring control unit 48 also receives alarm signals from the MOD unit 44 and the RF unit 46.
  • the monitoring control unit 48 uses the above control signals to provide commands to each unit regarding switching between 64QAM-V demodulation and 16QAM-VH demodulation.
  • the receiving device 34 receives wireless signals transmitted on the four channels #1 to #4 via the antenna 36.
  • the signals received by the antenna 36 are provided to the RF unit 50.
  • the RF section 50 performs reception AMP (amplification) processing, AGC processing, C/N monitoring processing, etc. Specifically, the C/N monitoring processing monitors whether the C/N for each of channels #1 to #4 is equal to or greater than the required value of 26 dB for 64QAM.
  • the RF section 50 has a function to handle V polarization and a function to handle H polarization.
  • the RF unit 50 provides the received signal to the MOD unit 52.
  • the MOD unit 52 demodulates the data using a pre-specified method, changes the demodulation method, and monitors the BER.
  • the MOD unit 52 also has a function compatible with V polarization and a function compatible with H polarization.
  • the transmitting device 30 uses 64QAM-V modulation
  • the MOD unit 52 uses the function compatible with V polarization to perform the above processing using the 64QAM-V demodulation method.
  • the transmitting device 30 uses 16QAM-VH modulation
  • the MOD unit 52 uses both the function compatible with V polarization and the function compatible with H polarization to perform the above processing using the 16QAM-VH demodulation method.
  • the signal demodulated by the MOD unit 52 is provided to the deframing unit 54.
  • the deframing unit 54 processes the signal, such as buffering, bit combining, and demapping.
  • the signal processed by the deframing unit 54 is transmitted as a user signal to the destination device via the user I/F unit 56.
  • the receiving device 34 further includes a monitoring control unit 58.
  • the monitoring control unit 58 transmits and receives control signals between the RF unit 50, the MOD unit 52, and the deframing unit 54.
  • the monitoring control unit 58 also receives alarm signals from the RF unit 50 and the MOD unit 52.
  • the MOD unit 52 provides an alarm to the monitoring control unit 58 to notify the situation.
  • the monitoring control unit 58 issues a command to switch the demodulation method from 64QAM-V demodulation to 16QAM-VH demodulation by using a control signal directed to the RF unit 50, MOD unit 52, and deframing unit 54.
  • the monitoring control unit 48 of the transmitting device 30 requesting a switch from 64QAM-V modulation to 16QAM-VH modulation. This allows simultaneous switching of the modulation method and demodulation method in the transmitting device 30 and the receiving device 34.
  • the RF section 50 of the receiving device 34 notifies the monitoring and control section 58 of the situation when the required C/N for 64QAM, that is, a C/N of 26 dB, is recovered.
  • the monitoring and control section 58 issues a command to return the demodulation method from 16QAM-VH demodulation to 64QAM-V demodulation by means of a control signal directed to the RF section 50, MOD section 52, and deframing section 54.
  • it transmits a control signal to the monitoring and control section 48 of the transmitting device 30, requesting a return from 16QAM-VH modulation to 64QAM-V modulation. This allows the transmitting device 30 and the receiving device 34 to simultaneously return to the modulation and demodulation methods.
  • Transmitting device 30 and receiving device 34 each include a computer system along with dedicated hardware. These computer systems include a processor such as a CPU, and a memory device that stores the programs executed by the processor. The functions of transmitting device 30 described above are achieved by the processor included in transmitting device 30 executing the programs stored in transmitting device 30. Similarly, the functions of receiving device 34 described above are achieved by the processor included in receiving device 34 executing the programs stored in receiving device 34.
  • FIG. 4 shows a first example of the configuration regarding the installation of the transmitting device 30 and the receiving device 34.
  • both the transmitting device 30 and the receiving device 34 are fixedly installed. Therefore, as shown in FIG. 4, the control signal to be exchanged between the transmitting device 30 and the receiving device 34 may be transmitted via a wired path 60 that has been installed in advance.
  • FIG. 5 shows a second example configuration regarding the installation of the transmitting device 30 and the receiving device 34.
  • a transmitting/receiving antenna 62 and a receiving device 64 are installed on the transmitting device 30 side.
  • a transmitting/receiving antenna 66 and a transmitting device 68 are installed on the receiving device 34 side.
  • the control signal transmitted from the receiving device 34 to the transmitting device 30 is transmitted and received as a wireless signal, similar to the traffic line. As the data volume of the control signal is limited, it is possible to transmit it over a wireless channel with a narrower bandwidth than the traffic line.
  • Fig. 6 is a flow chart for explaining the flow of a series of processes performed by the receiving device 34 in this embodiment.
  • the routine shown in Fig. 6 is assumed to be started for each channel.
  • this routine is assumed to be started under a condition where the BER is normal, that is, under a condition where 64QAN-V demodulation is used as the demodulation method.
  • the C/N ratio of the channel is obtained by the function of the RF unit 50 (step 100).
  • the BER of the channel is detected by the function of the MOD unit 52. Then, it is determined whether the detected BER has deteriorated to a value that does not satisfy the desired communication quality (step 102).
  • BER degradation is determined by performing error bit detection using CRC bits on a wireless carrier basis.
  • the BER is calculated assuming that the wireless signal contains random bit errors and that all bit errors are detected as CRC errors.
  • the presence or absence of the effects of fading is determined by focusing on quality degradation due to BER, rather than quality degradation due to C/N. This makes it possible to detect degradation of wireless transmission quality, including waveform distortion due to fading.
  • step 104 If no degradation of the BER is found by the processing of step 102, the processing of step 100 above is executed again. As a result, the receiving device 34 continues to perform the 64QAM-V demodulation processing. On the other hand, if degradation of the BER is found, the following two processing operations are performed (step 104).
  • the transmitter 30 is requested to use a front polarized wave as well as a rear polarized wave orthogonal to the front polarized wave, and to change the modulation method to one using a low multi-level number. Specifically, the modulation method is requested to be changed from 64QAM-V to 16QAM-VH.
  • the demodulation method will be changed to one that corresponds to the changed modulation method. Specifically, the demodulation method will be changed from 64QAM-V demodulation to 16QAM-VH demodulation.
  • the modulation and demodulation methods of both the transmitting device 30 and the receiving device 34 are simultaneously switched to those compatible with reverse polarization and low multi-values.
  • resistance to fading is improved without a decrease in transmission rate.
  • the receiving device 34 monitors the C/N of the channel using the function of the RF section 50 (step 106).
  • the C/N is determined whether the newly detected C/N has recovered to a level that can withstand the use of 64QAM, specifically, whether it has recovered to 26 dB or more, which is the required C/N for 64QAM (step 108).
  • the C/N is measured on a wireless carrier basis, and it is determined whether the C/N has recovered.
  • step 106 If the C/N ratio is not recovered by the processing of step 108, the processing of step 106 is repeated. As a result, the receiving device 34 continues to perform the 16QAM-VH demodulation processing.
  • step 110 the following two processes are carried out (step 110).
  • the transmitting device 30 is requested to transmit a high-order modulation signal in front polarization. Specifically, a return from 16QAM-VH modulation to 64QAM-V modulation is requested.
  • the demodulation method will be changed to a method that corresponds to the modulation method after the return to normal operation. Specifically, the demodulation method will be changed from 16QAM-VH demodulation to 64QAM-V demodulation.
  • the receiving device 34 Since the C/N ratio has been restored, after the modulation strategy and demodulation method are restored, a good BER can be maintained by transmitting and receiving a high multi-level modulated signal with front polarization. After that, the receiving device 34 repeatedly executes the processes from step 100 onwards.
  • FIG. 7 is a flowchart for explaining the flow of a series of processes performed by the transmitting device 30 in this embodiment.
  • the routine shown in Fig. 7 is assumed to be started under normal BER conditions for each channel, similar to the routine shown in Fig. 6.
  • a method for transmitting a high-level modulation signal using front polarization is set. Specifically, the 64QAM-V modulation method is set (step 120).
  • step 122 it is determined whether or not a change in the modulation method has been requested from the receiving device 34 (step 122). If a change in the modulation method has not been requested, the processing of step 100 above is repeated. As a result, the transmitting device 30 continues to process 64QAM-V modulation.
  • the modulation method is changed to one that uses both the front and back polarizations and uses a lower modulation level (step 124). Specifically, the modulation is changed from 64QAM-V to 16QAM-VH. This distributes traffic to the back polarization and reduces the modulation level, improving resistance to fading while maintaining the transmission rate.
  • the transmitting device 30 determines whether or not a request to return to the modulation method has been received from the receiving device 34 (step 126). If the request to return is not received, the processing of step 124 is repeated. As a result, the transmitting device 30 continues to perform 16QAM-VH modulation processing.
  • step 1228 if it is determined that a request to restore the modulation method has been received from the receiving device 34, the modulation method compatible with high multi-values is restored and transmission using the reverse polarization is stopped (step 128). Specifically, a return is made from 16QAM-VH modulation to 64QAM-V modulation. Thereafter, the processing from step 120 onwards described above is repeatedly performed.
  • 64QAM is switched to 16QAM to increase resistance to fading, but the method of increasing resistance to fading is not limited to this.
  • resistance may be increased by lowering the modulation multi-level number by switching between 16PSK, 8PSK, QPSK, BPSK, etc.
  • resistance to fading may be increased by switching between a modulation method using QAM and a modulation method using PSK.
  • the modulation multi-level number may be switched to a combination that allows such a rate reduction.
  • the BER is detected by detecting error bits using CRC bits, but the method is not limited to this.
  • the BER may be detected using any known method.
  • the modulation multi-level number is reduced and the use of the reverse polarization is started, but the present disclosure is not limited to this. This switching may also be performed based on degradation of the C/N ratio.

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Abstract

A transmission device 30 executes 64 QAM-V modulation for transmitting a 64 QAM signal using V-polarized waves, 16 QAM-VH modulation for transmitting a 16 QAM signal using V-polarized waves and H-polarized waves, a process for switching the 64 QAM-V modulation to the 16 QAM-VH modulation upon receiving a switching request, and a process for restoring the 16 QAM-VH modulation to the 64 QAM-V modulation upon receiving a restoration request. A reception device 34 executes: 64 QAM-V demodulation for demodulating a 64 QAM signal transmitted using the V polarized waves; 16 QAM-VH demodulation for demodulating a 16 QAM signal transmitted using the V polarized waves and the H polarized waves; a process for transmitting the switching request to the transmitting device 30 and switching the 64 QAM-V demodulation to the 16 QAM-VH demodulation when the influence of fading is recognized in the received signal; and transmitting the restoration request to the transmitting device 30 and restoring the 16 QAM-VH demodulation to the 64 QAM-V demodulation when the influence of fading is eliminated.

Description

無線中継システム、無線中継装置、無線中継方法および無線中継用プログラムWireless relay system, wireless relay device, wireless relay method, and wireless relay program
　この開示は、無線中継システム、無線中継装置、無線中継方法および無線中継用プログラムに係り、特に、フェージングによる品質低下の影響を軽減するうえで好適な無線中継システム、無線中継装置、無線中継方法および無線中継用プログラムに関する。 This disclosure relates to a wireless relay system, a wireless relay device, a wireless relay method, and a wireless relay program, and in particular to a wireless relay system, a wireless relay device, a wireless relay method, and a wireless relay program that are suitable for reducing the effects of quality degradation due to fading.
　無線信号を中継する方式としては、複数の周波数チャネルを使用して大容量の伝送を行うものが知られている。無線信号の伝搬が長距離である場合や、無線信号の伝搬経路が海上であるような環境では、伝搬の過程で無線信号がフェージングの影響を受けて、伝送特性が著しく劣化することがある。このような劣化を回避するためのフェージング対策としては、例えば下記の非特許文献１に記載されているように、スペースダイバーシチ（SD：Space Diversity）受信の技術が知られている。 A method of relaying wireless signals is known that uses multiple frequency channels to transmit large volumes of data. When wireless signals are propagated over long distances, or in environments where the propagation path of the wireless signals is over the ocean, the wireless signals may be affected by fading during the propagation process, causing significant degradation of the transmission characteristics. As a fading countermeasure to avoid such degradation, Space Diversity (SD) reception technology is known, as described in the following non-patent document 1, for example.
　図１は、SD受信による無線中継システムの概要を説明するための図である。図１に示すシステムは、送信装置１０を備えている。送信装置１０は、送信アンテナ１２を備えている。図１には、送信装置１０が、４つのチャネル♯１～♯４を用いて無線信号を送信する例を示している。 FIG. 1 is a diagram for explaining the outline of a wireless relay system using SD reception. The system shown in FIG. 1 includes a transmitting device 10. The transmitting device 10 includes a transmitting antenna 12. FIG. 1 shows an example in which the transmitting device 10 transmits wireless signals using four channels #1 to #4.
　また、この例では、４つのチャネル♯１～♯４が、何れも６４QAM（Quadrature Amplitude Modulation）の変調方式を用いて、垂直偏波（以下、「V偏波」とする）により無線信号を送信する。これにより、通常時には、チャネル毎に４００Mbpsの送信レートが得られるものとする。従って、４つのチャネル♯１～♯４を合計すると、４００Mbps×４＝１．６Gbpsの送信レートが得られる。 In addition, in this example, all four channels #1 to #4 use the 64QAM (Quadrature Amplitude Modulation) modulation method to transmit radio signals using vertical polarization (hereinafter referred to as "V polarization"). As a result, under normal circumstances, a transmission rate of 400Mbps can be obtained for each channel. Therefore, the total transmission rate of the four channels #1 to #4 is 400Mbps x 4 = 1.6Gbps.
　受信装置１４は、送信装置１０から遠く離れた地点に設置されている。受信装置１４は、異なる高さに設置された複数のアンテナ、この例では三つのアンテナ１６，１８，２０を備えている。長距離を伝搬してくる無線信号を受信するために、アンテナ１６，１８，２０は、典型的には、３ｍ～４ｍの口径を持つパラボラアンテナで構成される。 The receiving device 14 is installed at a location far away from the transmitting device 10. The receiving device 14 is equipped with multiple antennas installed at different heights, in this example, three antennas 16, 18, and 20. In order to receive radio signals propagating over long distances, the antennas 16, 18, and 20 are typically composed of parabolic antennas with an aperture of 3 m to 4 m.
　フェージングの影響は、無線信号の伝搬経路の状態に応じて変化する。例えば、天候等の影響により、最も高い位置に設置されたアンテナ１６の周囲では良好な条件が整っているが、最も低い位置に設置されたアンテナ２０の周辺では、その条件が無線通信に適さないものとなることがある。同様に、天候等によっては、その逆の状態が生ずることもある。 The effects of fading change depending on the state of the propagation path of the radio signal. For example, due to weather conditions, etc., conditions may be good around antenna 16, which is installed at the highest position, but conditions may be unsuitable for wireless communication around antenna 20, which is installed at the lowest position. Similarly, the opposite situation may occur depending on weather conditions, etc.
　受信側の複数のアンテナ１６，１８，２０を異なる高さに設置しておけば、何れかのアンテナがフェージングの影響を受ける条件下でも、他のアンテナでは、無線信号を良好に受信できることがある。このため、図１に示すシステムは、４つのチャネル♯１～♯４の何れかでフェージングの影響が検知されたら、そのチャネルの信号を受信するアンテナを、条件の良いアンテナに切り替える。 If the receiving antennas 16, 18, 20 are installed at different heights, even if one of the antennas is affected by fading, the other antennas may be able to receive the radio signal well. For this reason, when the system shown in Figure 1 detects the effects of fading on any of the four channels #1 to #4, it switches the antenna that receives the signal of that channel to the antenna with the best conditions.
　図１は、♯２と♯３のチャネルがフェージングの影響を受けた場合に、それらのチャネルの信号を受信するアンテナを切り替えた例を示している。その結果、図１に示すように、フェージングの影響が生じた後も、チャネル♯１～♯４の全てで４００Mbpsのレートが維持されている。このように、SD受信の技術によれば、フェージングに対する優れた耐性を提供することができる。 Figure 1 shows an example in which the antennas receiving the signals of channels #2 and #3 are switched when these channels are affected by fading. As a result, as shown in Figure 1, a rate of 400 Mbps is maintained for all channels #1 to #4 even after the effects of fading have occurred. In this way, SD reception technology can provide excellent resistance to fading.
　しかしながら、SD受信の技術でフェージング耐性を得るためには、上記の通り、巨大なパラボラアンテナを高地に複数設置しなければならない。このようなアンテナは単体で1,000kgを超えることがある。また、高さを確保するために、アンテナは鉄塔等の上に設置することになる。このため、図１に示すようなシステムを構築するには、多大な設備構築費用が必要となる。また、その設置構築には長い工事期間を要するのが通常である。 However, to achieve fading resistance using SD reception technology, as mentioned above, multiple huge parabolic antennas must be installed at high altitudes. Each such antenna can weigh over 1,000 kg. Furthermore, to ensure the necessary height, the antennas are installed on top of steel towers or similar structures. For this reason, building a system such as that shown in Figure 1 requires a huge amount of equipment construction costs. Furthermore, it usually takes a long period of time for construction work to install and build the system.
　更に、アンテナは、単純に高さを変えて複数設置すればよいものではない。つまり、複数のアンテナの相関が巧く処理されていなければ、フェージングによる受信レベルの落ち込みがアンテナの切り替えにより改善できない事態が生じ得る。このため、SD受信の技術に依拠する場合には、フェージングの影響が補償できるように、複数のアンテナのそれぞれの位置を精度よく設計することも必要となる。 Furthermore, it is not enough to simply install multiple antennas at different heights. In other words, if the correlation between multiple antennas is not handled properly, a situation may arise where a drop in reception level caused by fading cannot be improved by switching antennas. For this reason, when relying on SD reception technology, it is also necessary to precisely design the position of each of the multiple antennas so that the effects of fading can be compensated for.
　本開示は、上記の課題を解決するため、多大な設置負担を発生させることなくフェージングに対する優れた耐性を実現する無線中継システムを提供することを第１の目的とする。 The first objective of this disclosure is to provide a wireless relay system that achieves excellent resistance to fading without imposing a significant installation burden in order to solve the above problems.
　また、本開示は、多大な設置負担を発生させることなくフェージングに対する優れた耐性を実現する無線中継装置を提供することを第２の目的とする。 The second objective of this disclosure is to provide a wireless relay device that achieves excellent resistance to fading without imposing a significant installation burden.
　また、本開示は、多大な設置負担を発生させることなくフェージングに対する優れた耐性を実現するための無線中継方法を提供することを第３の目的とする。 The third objective of this disclosure is to provide a wireless relay method that achieves excellent resistance to fading without imposing a significant installation burden.
　また、本開示は、多大な設置負担を発生させることなくフェージングに対する優れた耐性を実現するための無線中継用プログラムを提供することを第４の目的とする。 The fourth objective of this disclosure is to provide a wireless relay program that achieves excellent resistance to fading without imposing a significant installation burden.
　第１の態様は、上記の目的を達成するため、無線信号を送信する送信装置と、前記送信装置から無線信号を受信する受信装置とを含む無線中継システムであって、
　前記送信装置は、
　表偏波と裏偏波に対応する送信アンテナを備え、
　前記表偏波で第一多値数による変調信号を送信する第一変調処理と、
　前記表偏波および前記裏偏波の双方を用いて、前記第一多値数より少ない第二多値数による変調信号を送信する第二変調処理と、
　前記受信装置からの切り替え要請を受けて前記第一変調処理を前記第二変調処理に切り替える処理と、
　前記受信装置からの復帰要請を受けて前記第二変調処理を前記第一変調処理に復帰させる処理と、を実行するように構成され、
　前記受信装置は、
　前記表偏波と前記裏偏波に対応する受信アンテナを備え、
　前記表偏波で送信されてくる前記第一多値数による変調信号を復調する第一復調処理と、
　前記表偏波および前記裏偏波の双方を用いて送信されてくる前記第二多値数による変調信号を復調する第二復調処理と、
　前記送信装置から受信した前記無線信号に、判断基準を超えるフェージングの影響が認められた場合に、前記送信装置に向けて前記切り替え要請を送信すると共に、前記第一復調処理を前記第二復調処理に切り替える処理と、
　前記フェージングの影響が解消されたと認められた場合に、前記送信装置に向けて前記復帰要請を送信すると共に、前記第二復調処理を前記第一復調処理に復帰させる処理と、を実行するように構成されることが望ましい。 In order to achieve the above object, a first aspect is a wireless relay system including a transmitting device that transmits a wireless signal and a receiving device that receives the wireless signal from the transmitting device,
The transmitting device includes:
Equipped with a transmitting antenna that supports both front and back polarization,
a first modulation process for transmitting a modulated signal with a first multi-level number in the front polarization;
A second modulation process of transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarization and the back polarization;
a process of switching from the first modulation process to the second modulation process in response to a switching request from the receiving device;
and a process of returning the second modulation process to the first modulation process in response to a return request from the receiving device,
The receiving device includes:
a receiving antenna corresponding to the front polarized wave and the back polarized wave,
a first demodulation process for demodulating a modulated signal by the first multi-level number transmitted by the front polarization;
a second demodulation process for demodulating a modulated signal by the second multi-level number transmitted using both the front polarization and the back polarization;
a process of transmitting the switching request to the transmitting device and switching the first demodulation process to the second demodulation process when an influence of fading exceeding a judgment criterion is recognized in the wireless signal received from the transmitting device;
It is desirable to be configured to execute a process of transmitting the return request to the transmitting device and returning the second demodulation process to the first demodulation process when it is determined that the effect of fading has been resolved.
　また、第２の態様は、送信装置から受信した無線信号を中継する無線中継装置であって、
　表偏波と裏偏波に対応する受信アンテナを備え、
　前記表偏波で送信されてくる第一多値数による変調信号を復調する第一復調処理と、
　前記表偏波および前記裏偏波の双方を用いて送信されてくる、前記第一多値数より少ない第二多値数による変調信号を復調する第二復調処理と、
　前記送信装置から受信した前記無線信号に、判断基準を超えるフェージングの影響が認められた場合に、前記送信装置に向けて、前記表偏波で前記第一多値数による変調信号を送信する第一変調処理を、前記表偏波および前記裏偏波の双方で前記第二多値数による変調信号を送信する第二変調処理に切り替えることを要請すると共に、前記第一復調処理を前記第二復調処理に切り替える処理と、
　前記フェージングの影響が解消されたと認められた場合に、前記送信装置に向けて前記第二変調処理を前記第一変調処理に復帰させることを要請すると共に、前記第二復調処理を前記第一復調処理に復帰させる処理と、
　を実行するように構成されることが望ましい。 A second aspect is a wireless relay device that relays a wireless signal received from a transmitting device,
Equipped with a receiving antenna that supports both front and back polarization,
a first demodulation process for demodulating a modulated signal having a first multilevel number transmitted by the front polarization;
a second demodulation process for demodulating a modulated signal transmitted using both the front polarization and the back polarization, the modulated signal being modulated by a second multi-level number that is smaller than the first multi-level number;
a process of requesting the transmitting device to switch a first modulation process for transmitting a modulated signal with the first multi-level number in the front polarization to a second modulation process for transmitting a modulated signal with the second multi-level number in both the front polarization and the back polarization when an influence of fading exceeding a judgment criterion is found in the wireless signal received from the transmitting device, and switching the first demodulation process to the second demodulation process;
a process of requesting the transmitting device to return from the second modulation process to the first modulation process and returning from the second demodulation process to the first demodulation process when it is determined that the influence of the fading has been eliminated;
It is preferable that the method is configured to execute the following steps:
　また、第３の態様は、中継の対象である無線信号を受信装置に向けて送信する無線中継装置であって、
　表偏波と裏偏波に対応する送信アンテナを備え、
　前記表偏波で第一多値数による変調信号を送信する第一変調処理と、
　前記表偏波および前記裏偏波の双方を用いて、前記第一多値数より少ない第二多値数による変調信号を送信する第二変調処理と、
　前記受信装置からの切り替え要請を受けて前記第一変調処理を前記第二変調処理に切り替える処理と、
　前記受信装置からの復帰要請を受けて前記第二変調処理を前記第一変調処理に復帰させる処理と、を実行するように構成されることが望ましい。 A third aspect is a wireless relay device that transmits a wireless signal to be relayed to a receiving device, comprising:
Equipped with a transmitting antenna that supports both front and back polarization,
a first modulation process for transmitting a modulated signal with a first multi-level number in the front polarization;
A second modulation process of transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarization and the back polarization;
a process of switching from the first modulation process to the second modulation process in response to a switching request from the receiving device;
It is desirable to configure the modulation device to execute a process of restoring the second modulation process to the first modulation process upon receiving a restoration request from the receiving device.
　また、第４の態様は、送信装置と、当該送信装置から無線信号を受信する受信装置とを用いて前記無線信号を中継するための無線中継方法であって、
　前記送信装置が、
　表偏波で第一多値数による変調信号を送信する第一変調を実行することと、
　前記表偏波および裏偏波の双方を用いて、前記第一多値数より少ない第二多値数による変調信号を送信する第二変調を実行することと、
　前記受信装置からの切り替え要請を受けて前記第一変調を前記第二変調に切り替えることと、
　前記受信装置からの復帰要請を受けて前記第二変調を前記第一変調に復帰させることと、
　前記受信装置が、
　前記表偏波で送信されてくる前記第一多値数による変調信号を復調する第一復調を実行することと、
　前記表偏波および前記裏偏波の双方を用いて送信されてくる前記第二多値数による変調信号を復調する第二復調を実行することと、
　前記送信装置から受信した前記無線信号に、判断基準を超えるフェージングの影響が認められた場合に、前記送信装置に向けて前記切り替え要請を送信すると共に、前記第一復調を前記第二復調に切り替えることと、
　前記フェージングの影響が解消されたと認められた場合に、前記送信装置に向けて前記復帰要請を送信すると共に、前記第二復調を前記第一復調に復帰させることと、
　を含むことが望ましい。 A fourth aspect is a wireless relay method for relaying a wireless signal using a transmitting device and a receiving device that receives a wireless signal from the transmitting device, the method comprising:
The transmitting device,
performing a first modulation to transmit a modulated signal with a first multilevel number in a front polarization;
performing a second modulation for transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarized wave and the back polarized wave;
switching the first modulation to the second modulation in response to a switching request from the receiving device;
restoring the second modulation to the first modulation upon receiving a restoration request from the receiving device;
The receiving device,
performing a first demodulation for demodulating a modulated signal by the first multilevel number transmitted by the front polarization;
performing a second demodulation to demodulate the modulated signal by the second multi-level number transmitted by using both the front polarization and the back polarization;
when an influence of fading exceeding a judgment criterion is found in the wireless signal received from the transmitting device, transmitting the switching request to the transmitting device and switching the first demodulation to the second demodulation;
when it is determined that the effect of the fading has been eliminated, transmitting the restoration request to the transmitting device and restoring the second demodulation to the first demodulation;
It is preferable that the present invention includes the following:
　また、第５の態様は、送信装置から受信した無線信号を受信装置に中継させるための無線中継用プログラムであって、
　前記受信装置は、
　表偏波と裏偏波に対応する受信アンテナと、
　プロセッサと、を備え、
　前記プロセッサに、
　前記表偏波で送信されてくる第一多値数による変調信号を復調する第一復調処理と、
　前記表偏波および前記裏偏波の双方を用いて送信されてくる、前記第一多値数より少ない第二多値数による変調信号を復調する第二復調処理と、
　前記送信装置から受信した前記無線信号に、判断基準を超えるフェージングの影響が認められた場合に、前記送信装置に向けて、前記表偏波で前記第一多値数による変調信号を送信する第一変調処理を、前記表偏波および前記裏偏波の双方で前記第二多値数による変調信号を送信する第二変調処理に切り替えることを要請すると共に、前記第一復調処理を前記第二復調処理に切り替える処理と、
　前記フェージングの影響が解消されたと認められた場合に、前記送信装置に向けて前記第二変調処理を前記第一変調処理に復帰させることを要請すると共に、前記第二復調処理を前記第一復調処理に復帰させる処理と、
　を実行させるコンピュータ読み取り可能なプログラムを含むことが望ましい。 A fifth aspect is a wireless relay program for relaying a wireless signal received from a transmitting device to a receiving device, the program comprising:
The receiving device includes:
A receiving antenna that supports front and back polarization;
a processor;
The processor,
a first demodulation process for demodulating a modulated signal having a first multilevel number transmitted by the front polarization;
a second demodulation process for demodulating a modulated signal transmitted using both the front polarization and the back polarization, the modulated signal being modulated by a second multi-level number that is smaller than the first multi-level number;
a process of requesting the transmitting device to switch a first modulation process for transmitting a modulated signal with the first multi-level number in the front polarization to a second modulation process for transmitting a modulated signal with the second multi-level number in both the front polarization and the back polarization when an influence of fading exceeding a judgment criterion is found in the wireless signal received from the transmitting device, and switching the first demodulation process to the second demodulation process;
a process of requesting the transmitting device to return from the second modulation process to the first modulation process and returning from the second demodulation process to the first demodulation process when it is determined that the influence of the fading has been eliminated;
It is preferable that the computer readable program be capable of executing the above-mentioned method.
　また、第６の態様は、中継の対象である無線信号を受信装置に向けて送信装置に送信させるための無線中継用プログラムであって、
　前記送信装置は、
　表偏波と裏偏波に対応する送信アンテナと、
　プロセッサと、を備え、
　前記プロセッサに、
　前記表偏波で第一多値数による変調信号を送信する第一変調処理と、
　前記表偏波および前記裏偏波の双方を用いて、前記第一多値数より少ない第二多値数による変調信号を送信する第二変調処理と、
　前記受信装置からの切り替え要請を受けて前記第一変調処理を前記第二変調処理に切り替える処理と、
　前記受信装置からの復帰要請を受けて前記第二変調処理を前記第一変調処理に復帰させる処理と、
　を実行させるコンピュータ読み取り可能なプログラムを含むことが望ましい。 A sixth aspect is a wireless relay program for causing a transmitting device to transmit a wireless signal to be relayed toward a receiving device, the program comprising:
The transmitting device includes:
A transmitting antenna corresponding to front and back polarization;
a processor;
The processor,
a first modulation process for transmitting a modulated signal with a first multi-level number in the front polarization;
A second modulation process of transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarization and the back polarization;
a process of switching from the first modulation process to the second modulation process in response to a switching request from the receiving device;
a process of returning the second modulation process to the first modulation process in response to a return request from the receiving device;
It is preferable that the computer readable program be capable of executing the above-mentioned method.
　第１乃至第４の態様によれば、多大な設置負担を発生させることなくフェージングに対する優れた耐性を実現することができる。 According to the first to fourth aspects, it is possible to achieve excellent resistance to fading without incurring a significant installation burden.
SD受信による無線中継システムの概要を説明するための図である。FIG. 1 is a diagram for explaining an overview of a wireless relay system using SD reception. 本開示の実施の形態１の無線中継システムの概要を説明するための図である。FIG. 1 is a diagram for explaining an overview of a wireless relay system according to a first embodiment of the present disclosure. 図２に示す送信装置および受信装置の構成を説明するためのブロック図である。FIG. 3 is a block diagram for explaining the configurations of the transmitting device and the receiving device shown in FIG. 2 . 図３に示す送信装置と受信装置の設置に関する第一の構成例を示す。A first configuration example regarding the installation of the transmitting device and the receiving device shown in FIG. 3 will be described. 図３に示す送信装置と受信装置の設置に関する第二の構成例を示す。A second configuration example regarding the installation of the transmitting device and the receiving device shown in FIG. 3 will be described. 本開示の実施の形態１において、受信装置が実施する一連の処理の流れを説明するためのフローチャートである。1 is a flowchart for explaining the flow of a series of processes performed by a receiving device in the first embodiment of the present disclosure. 本開示の実施の形態１において、送信装置が実施する一連の処理の流れを説明するためのフローチャートである。1 is a flowchart for explaining the flow of a series of processes performed by a transmitting device in the first embodiment of the present disclosure.
実施の形態１．
［実施の形態１の概要］
　図２は、本開示の実施の形態１の無線中継システムの概要を説明するための図である。本実施形態のシステムは、送信装置３０を備えている。送信装置３０は、送信アンテナ３２を備えている。図２には、送信装置３０が、４つのチャネル♯１～♯４を用いて無線信号を送信する例を示している。 Embodiment 1.
[Outline of First Embodiment]
Fig. 2 is a diagram for explaining an overview of a wireless relay system according to the first embodiment of the present disclosure. The system according to the present embodiment includes a transmitting device 30. The transmitting device 30 includes a transmitting antenna 32. Fig. 2 shows an example in which the transmitting device 30 transmits wireless signals using four channels #1 to #4.
　送信装置３０は、４つのチャネル♯１～♯４にそれぞれにおいて、６４QAMの変調方式を用いることができる。また、６４QAMの変調方式を用いる場合、それらのチャネル♯１～♯４を用いて、V偏波の無線信号を送信することができる。この場合、チャネル毎に４００Mbpsの送信レートを得ることができ、４つのチャネル♯１～♯４を合計して４００Mbps×４＝１．６Gbpsの送信レートが得られるものとする。 Transmitting device 30 can use the 64QAM modulation method for each of the four channels #1 to #4. When using the 64QAM modulation method, V-polarized radio signals can be transmitted using channels #1 to #4. In this case, a transmission rate of 400Mbps can be obtained for each channel, and a total transmission rate of 400Mbps x 4 = 1.6Gbps can be obtained for the four channels #1 to #4.
　本実施形態の送信装置３０は、チャネル♯１～♯４のそれぞれにおいて、変調多値数を変化させることができる。具体的には、チャネル♯１～♯４のそれぞれにおいて、６４QAMの変調方式を、１６QAMの変調方式に切り替えることができる。 The transmitting device 30 of this embodiment can change the modulation multi-level number in each of channels #1 to #4. Specifically, in each of channels #1 to #4, the modulation method of 64QAM can be switched to the modulation method of 16QAM.
　また、送信装置３０は、１６QAMの変調方式を用いるチャネルでは、無線信号を、V偏波と、その裏偏波、つまりV偏波と直交する偏波である水平偏波（以下、「H偏波」とする）の双方で並列に送信することができる。 In addition, in a channel using the 16QAM modulation method, the transmitting device 30 can transmit radio signals in parallel using both V polarization and its reverse polarization, i.e., horizontal polarization (hereinafter referred to as "H polarization"), which is a polarization orthogonal to the V polarization.
　無線信号を中継する場合において、規定のビットエラー率（BER）を確保するための所要C/N（Carrier to Noise）は、変調方式の多値数が大きいほど大きな値となる。例えば、６４QAMの所要C/N＝２６dBであるのに対して、１６QAMの所要C/N＝２１dBとなる。したがって、変調方式を６４QAMから１６QAMに変更すると、フェージングに対する耐性を５dB高めることができる。 When relaying wireless signals, the required C/N (Carrier to Noise) to ensure a specified bit error rate (BER) increases as the number of modulation levels increases. For example, the required C/N for 64QAM is 26dB, while the required C/N for 16QAM is 21dB. Therefore, changing the modulation method from 64QAM to 16QAM can increase resistance to fading by 5dB.
　また、６４QAMによれば、６ビットの信号が生成される。これに対して、１６QAMでは４ビットの信号が生成される。そして、V偏波の４ビットとH偏波の４ビットを合わせると、８ビットの信号が生成できる。このため、１６QAMの信号をV偏波とH偏波の双方で送信すると、６４QAMの信号をV偏波で送信する場合と同等以上の送信レートを確保することができる。 In addition, with 64QAM, a 6-bit signal is generated. In contrast, with 16QAM, a 4-bit signal is generated. And by combining the 4 bits of V polarization and the 4 bits of H polarization, an 8-bit signal can be generated. For this reason, when a 16QAM signal is transmitted using both V polarization and H polarization, a transmission rate equal to or greater than that achieved when a 64QAM signal is transmitted using V polarization can be ensured.
　図２に示すように、本実施形態の送信装置３０は、チャネル♯１～♯４の何れにもフェージングの影響が表れていない場合は、チャネル♯１～♯４の全てにおいて、６４QAMで変調した信号をV偏波で送信する。以下、この手法を「６４QAM-V変調」と称する。そして、何れかのチャネルでフェージングの影響が認められたら、そのチャネルでは、変調方式を１６QAMに切り替えてV偏波とH偏波の双方を使った送信を開始する。以下、この手法を「１６QAM-VH変調」と称する。 As shown in FIG. 2, in the case where the effects of fading are not observed in any of channels #1 to #4, the transmitting device 30 of this embodiment transmits signals modulated with 64QAM in V polarization in all of channels #1 to #4. Hereinafter, this method is referred to as "64QAM-V modulation." Then, if the effects of fading are observed in any of the channels, the modulation method is switched to 16QAM in that channel, and transmission using both V polarization and H polarization begins. Hereinafter, this method is referred to as "16QAM-VH modulation."
　図２は、チャネル♯２とチャネル♯３でフェージングの影響が認められた結果、それらのチャネルの送信方式が６４QAM-V変調から１６QAM-VH変調に切り替えられた例を示している。この切り替えにより、チャネル♯２、♯３のフェージング耐性が５dB上昇するため、フェージングによる劣化の影響を小さくすることができる。 Figure 2 shows an example in which the effects of fading were observed in channel #2 and channel #3, and the transmission method for those channels was switched from 64QAM-V modulation to 16QAM-VH modulation. This switch increases the fading resistance of channels #2 and #3 by 5 dB, thereby reducing the effects of degradation due to fading.
　また、切り替え前は、４つのチャネル♯１～♯４のそれぞれが４００Mbpsを担うことにより４００Mbps×４＝１．６Gbpsのレートが確保されている。切り替え後は、♯２と♯３のV偏波およびH偏波に、実質的に２００Mbps以上のレートをそれぞれ担わせることができる。これにより、４つのチャネルの合計では、次式の通り、少なくとも切り替え前と同等の送信レートを維持することができる。
（４００Mbps×２）＋（２００Mbps×４）＝１．６Gbps Also, before the switchover, each of the four channels #1 to #4 carries 400 Mbps, ensuring a rate of 400 Mbps x 4 = 1.6 Gbps. After the switchover, the V-polarized and H-polarized waves of #2 and #3 can each carry a rate of substantially more than 200 Mbps. This allows the total of the four channels to maintain a transmission rate at least equal to that before the switchover, as shown in the following formula.
(400Mbps x 2) + (200Mbps x 4) = 1.6Gbps
　本実施形態のシステムは受信装置３４を備えている。受信装置３４は、送信装置１０から遠く離れた地点に設置されている。受信装置１４は、アンテナ３６を備えている。アンテナ３６は、V偏波とH偏波の双方を受信する機能を有している。 The system of this embodiment includes a receiving device 34. The receiving device 34 is installed at a location far away from the transmitting device 10. The receiving device 14 includes an antenna 36. The antenna 36 has the function of receiving both V-polarized waves and H-polarized waves.
　受信装置３４は、アンテナ３６が受信した無線信号を解析して、チャネル♯１～♯４のそれぞれについて、フェージングによる品質劣化が生じているか否かを判断する。その結果、何れのチャネルについてもフェージングの影響が認められなければ、チャネル♯１～♯４の全てについて、受信信号を、６４QAM-V変調に対応する手法で復調する。以下、この復調を「６４QAM-V復調」と称す。 The receiving device 34 analyzes the radio signals received by the antenna 36 and determines whether or not quality degradation due to fading has occurred for each of channels #1 to #4. If the result shows that there is no effect of fading for any of the channels, the receiving device 34 demodulates the received signals for all of channels #1 to #4 using a method compatible with 64QAM-V modulation. Hereinafter, this demodulation will be referred to as "64QAM-V demodulation."
　他方、何れかのチャネルについてフェージングにより品質劣化が認められたら、そのチャネルについて、変調方式と送信偏波を変更するための処理を行う。具体的には、フェージングの影響が認められたチャネルの情報を送信装置３０に通知すると同時に、無線信号の復号方式を、６４QAM-V復調から、１６QAM-VH変調に対応する復調方式に変更する。以下、この復調を「１６QAM-VH復調」と称す。 On the other hand, if quality degradation due to fading is found for any of the channels, processing is performed to change the modulation method and transmission polarization for that channel. Specifically, information about the channel for which the effects of fading have been found is notified to the transmitting device 30, and at the same time, the radio signal decoding method is changed from 64QAM-V demodulation to a demodulation method compatible with 16QAM-VH modulation. Hereinafter, this demodulation is referred to as "16QAM-VH demodulation."
　送信装置３０は、上記の通知を受けて、６４QAM-V変調の手法を、１６QAM-VH変調の手法に切り替える。これにより、送信装置３０の送信方式と受信装置３４の復調方式が同期したタイミングで切り替えられる。 In response to the notification, the transmitting device 30 switches from the 64QAM-V modulation method to the 16QAM-VH modulation method. This allows the transmission method of the transmitting device 30 and the demodulation method of the receiving device 34 to be switched at a synchronized timing.
　受信装置３４は、復調の方式を切り替えたチャネルについて、通信品質を監視する。そして、６４QAMでの送受信が可能な条件が回復したら、送信装置３０に復帰要請を送信する。同時に、無線信号の復号方式を、１６QAM-VH復調から、６４QAM-V復調に復帰させる。 The receiving device 34 monitors the communication quality of the channel for which the demodulation method has been switched. Then, when the conditions for transmission and reception in 64QAM are restored, it sends a request to the transmitting device 30 to resume. At the same time, it reverts the radio signal decoding method from 16QAM-VH demodulation to 64QAM-V demodulation.
　送信装置３０は、上記の復帰要請を受けて、１６QAM-VH変調の手法を、６４QAM-V変調の手法に復帰させる。これにより、送信装置３０と受信装置３４は、同期したタイミングで送信方式と復調方式を復帰させることができる。 In response to the reversion request, the transmitting device 30 reverts from the 16QAM-VH modulation method to the 64QAM-V modulation method. This allows the transmitting device 30 and the receiving device 34 to revert to the transmission method and demodulation method at synchronized timing.
［送信装置および受信装置の構成］
　図３は、送信装置３０および受信装置３４の構成を説明するためのブロック図である。図３に示すように、送信装置３０は、中継するべきユーザ信号を受け付けるユーザインターフェース（I/F）部４０を備えている。ユーザI/F部４０では、ユーザ信号の送信元との接続を管理するための処理等が行われる。 [Configuration of transmitting device and receiving device]
Fig. 3 is a block diagram for explaining the configuration of the transmitting device 30 and the receiving device 34. As shown in Fig. 3, the transmitting device 30 includes a user interface (I/F) unit 40 that receives a user signal to be relayed. The user I/F unit 40 performs processing for managing a connection with a transmission source of the user signal, etc.
　ユーザI/F部４０は、受け付けたユーザ信号をフレーミング部４２に提供する。フレーミング部４２は、ユーザ信号のバッファリング、ビット分割、マッピング、パケット化等の処理を行う。フレーミング部４２で生成されたパケットはMOD部４４に提供される。 The user I/F unit 40 provides the received user signal to the framing unit 42. The framing unit 42 performs processes such as buffering, bit division, mapping, and packetization of the user signal. The packets generated by the framing unit 42 are provided to the MOD unit 44.
　MOD部４４では、指定された変調方式によるデータ変調処理、並びに使用する変調方式を変更する処理が行われる。また、MOD部４４は、変調データをV偏波で送信するための機能とH偏波で送信する機能とを有している。本実施形態では、MOD部４４が用いる変調方式として、６４QAMによる方式と、１６QAMによる方式とが準備されている。MOD部４４は、具体的には、上記の６４QAM-V変調に対応する処理と、上記の１６QAM-VH変調に対応する処理とを選択的に実行する。 The MOD unit 44 performs data modulation processing using a specified modulation method, as well as processing to change the modulation method to be used. The MOD unit 44 also has a function for transmitting modulated data using V polarization and a function for transmitting using H polarization. In this embodiment, the modulation methods used by the MOD unit 44 are a 64QAM method and a 16QAM method. Specifically, the MOD unit 44 selectively executes processing corresponding to the above 64QAM-V modulation and processing corresponding to the above 16QAM-VH modulation.
　MOD部４４で生成された変調データは、RF部４６に提供される。RF部４６では、送信AMP（増幅）処理、フィルタ処理、監視処理等が実施される。RF部４６にも、V偏波に対応する機能とH偏波に対応する機能が備わっている。６４QAM-V変調の手法が用いられる場合は、V偏波に対応する機能により送信AMP等の処理が実現される。１６QAM-VH変調の手法が用いられる場合は、V偏波に対応する機能並びにH偏波に対応する機能の双方により上記の処理が実現される。 The modulated data generated by the MOD unit 44 is provided to the RF unit 46. The RF unit 46 performs transmit AMP (amplification) processing, filter processing, monitoring processing, etc. The RF unit 46 also has a function compatible with V polarization and a function compatible with H polarization. When the 64QAM-V modulation method is used, the transmit AMP and other processing is realized by the function compatible with V polarization. When the 16QAM-VH modulation method is used, the above processing is realized by both the function compatible with V polarization and the function compatible with H polarization.
　RF部４６で生成された信号は、アンテナ３２を介して無線信号の形態で送信される。本実施形態では、この信号は、上記の通り４つのチャネル♯１～♯４で送信される。RF部４６にも、V偏波に対応する機能とH偏波に対応する機能とが備わっている。 The signal generated by the RF unit 46 is transmitted in the form of a wireless signal via the antenna 32. In this embodiment, this signal is transmitted on four channels #1 to #4 as described above. The RF unit 46 also has a function compatible with V polarization and a function compatible with H polarization.
　送信装置３０は、更に、監視制御部４８を備えている。監視制御部４８は、フレーミング部４２、MOD部４４およびRF部４６との間で、それぞれ制御信号を授受する。また、監視制御部４８は、MOD部４４およびRF部４６から、それぞれ警報信号を受け取る。本実施形態において、監視制御部４８は、上記の制御信号を用いて６４QAM-V復調と１６QAM-VH復調との切り換えに関する指令を各部に提供する。 The transmitting device 30 further includes a monitoring control unit 48. The monitoring control unit 48 transmits and receives control signals between the framing unit 42, the MOD unit 44, and the RF unit 46. The monitoring control unit 48 also receives alarm signals from the MOD unit 44 and the RF unit 46. In this embodiment, the monitoring control unit 48 uses the above control signals to provide commands to each unit regarding switching between 64QAM-V demodulation and 16QAM-VH demodulation.
　受信装置３４は、アンテナ３６により、４つのチャネル♯１～♯４で送信されてくる無線信号を受信する。アンテナ３６によって受信された信号は、RF部５０に提供される。 The receiving device 34 receives wireless signals transmitted on the four channels #1 to #4 via the antenna 36. The signals received by the antenna 36 are provided to the RF unit 50.
　RF部５０では、受信AMP（増幅）処理、AGC処理、並びにC/N監視処理等が行われる。C/N監視処理では、具体的には、チャネル♯１～♯４のそれぞれについて、C/Nが、６４QAMの所要値２６ｄB以上であるかが監視される。RF部５０には、V偏波に対応する機能とH偏波に対応する機能とが備わっている。 The RF section 50 performs reception AMP (amplification) processing, AGC processing, C/N monitoring processing, etc. Specifically, the C/N monitoring processing monitors whether the C/N for each of channels #1 to #4 is equal to or greater than the required value of 26 dB for 64QAM. The RF section 50 has a function to handle V polarization and a function to handle H polarization.
　RF部５０は、受信した信号をMOD部５２に提供する。MOD部５２は、予め指定された方式でのデータ復調、復調方式を変更する処理、並びにBER監視の処理が行われる。MOD部５２にも、V偏波に対応する機能とH偏波に対応する機能が備わっている。送信装置３０が６４QAM-V変調を用いる場合、MOD部５２は、V偏波に対応する機能を用いて、６４QAM-V復調の手法で上記の処理を行う。また、送信装置３０が１６QAM-VH変調を用いる場合は、V偏波に対応する機能とH偏波に対応する機能の双方を使って、１６QAM－VH復調の手法で上記の処理を行う。 The RF unit 50 provides the received signal to the MOD unit 52. The MOD unit 52 demodulates the data using a pre-specified method, changes the demodulation method, and monitors the BER. The MOD unit 52 also has a function compatible with V polarization and a function compatible with H polarization. When the transmitting device 30 uses 64QAM-V modulation, the MOD unit 52 uses the function compatible with V polarization to perform the above processing using the 64QAM-V demodulation method. When the transmitting device 30 uses 16QAM-VH modulation, the MOD unit 52 uses both the function compatible with V polarization and the function compatible with H polarization to perform the above processing using the 16QAM-VH demodulation method.
　MOD部５２によって復調された信号は、デフレーミング部５４に提供される。デフレーミング部５４は、その信号に対して、バッファリング、ビット結合、デマッピング等の処理を施す。デフレーミング部５４によって処理された信号は、ユーザI/F部５６を介して、ユーザ信号として送信先の機器に向けて発信される。 The signal demodulated by the MOD unit 52 is provided to the deframing unit 54. The deframing unit 54 processes the signal, such as buffering, bit combining, and demapping. The signal processed by the deframing unit 54 is transmitted as a user signal to the destination device via the user I/F unit 56.
　受信装置３４は、更に、監視制御部５８を備えている。監視制御部５８は、RF部５０、MOD部５２およびデフレーミング部５４との間で、それぞれ制御信号を授受する。また、監視制御部５８は、RF部５０およびMOD部５２から、それぞれ警報信号を受け取る。 The receiving device 34 further includes a monitoring control unit 58. The monitoring control unit 58 transmits and receives control signals between the RF unit 50, the MOD unit 52, and the deframing unit 54. The monitoring control unit 58 also receives alarm signals from the RF unit 50 and the MOD unit 52.
　本実施形態において、MOD部５２は、チャネル♯１～♯４の何れかについて、所望のBERが得られていない場合に、その状況を知らせる警報を監視制御部５８に提供する。監視制御部５８は、この警報を受けると、RF部５０、MOD部５２およびデフレーミング部５４に向けた制御信号により、復調方式を６４QAM-V復調から１６QAM－VH復調に切り替える指令を発する。同時に、送信装置３０の監視制御部４８に、６４QAM-V変調から１６QAM－VH変調への切り替えを要請する制御信号を送信する。これにより、送信装置３０と受信装置３４において、変調方式および復調方式の同時切り替えが実現される。 In this embodiment, if the desired BER is not obtained for any of channels #1 to #4, the MOD unit 52 provides an alarm to the monitoring control unit 58 to notify the situation. When the monitoring control unit 58 receives this alarm, it issues a command to switch the demodulation method from 64QAM-V demodulation to 16QAM-VH demodulation by using a control signal directed to the RF unit 50, MOD unit 52, and deframing unit 54. At the same time, it sends a control signal to the monitoring control unit 48 of the transmitting device 30 requesting a switch from 64QAM-V modulation to 16QAM-VH modulation. This allows simultaneous switching of the modulation method and demodulation method in the transmitting device 30 and the receiving device 34.
　また、受信装置３４のRF部５０は、１６QAM-VH復調が用いられている場合に、６４QAMの所要C/N、つまり２６ｄBのC/Nが回復したら、その状況を監視制御部５８に通知する。監視制御部５８は、上記の通知を受けると、RF部５０、MOD部５２およびデフレーミング部５４に向けた制御信号により、復調方式を１６QAM－VH復調から６４QAM-V復調に復帰させる指令を発する。同時に、送信装置３０の監視制御部４８に、１６QAM－VH変調から６４QAM-V変調への復帰を要請する制御信号を送信する。これにより、送信装置３０と受信装置３４において、変調方式および復調方式の同時復帰が実現される。 In addition, when 16QAM-VH demodulation is being used, the RF section 50 of the receiving device 34 notifies the monitoring and control section 58 of the situation when the required C/N for 64QAM, that is, a C/N of 26 dB, is recovered. Upon receiving the above notification, the monitoring and control section 58 issues a command to return the demodulation method from 16QAM-VH demodulation to 64QAM-V demodulation by means of a control signal directed to the RF section 50, MOD section 52, and deframing section 54. At the same time, it transmits a control signal to the monitoring and control section 48 of the transmitting device 30, requesting a return from 16QAM-VH modulation to 64QAM-V modulation. This allows the transmitting device 30 and the receiving device 34 to simultaneously return to the modulation and demodulation methods.
　送信装置３０および受信装置３４は、それぞれ、専用のハードウェアと共にコンピュータシステムを備えている。それらのコンピュータシステムには、CPU等のプロセッサと、当該プロセッサにおいて実行されるプログラムを格納したメモリ装置とが含まれている。上述した送信装置３０の機能は、送信装置３０が備えるプロセッサが、送信装置３０に格納されているプログラムを実行することで達成される。同様に、上述した受信装置３４の機能は、受信装置３４が備えるプロセッサが、受信装置３４に格納されているプログラムを実行することで達成される。 Transmitting device 30 and receiving device 34 each include a computer system along with dedicated hardware. These computer systems include a processor such as a CPU, and a memory device that stores the programs executed by the processor. The functions of transmitting device 30 described above are achieved by the processor included in transmitting device 30 executing the programs stored in transmitting device 30. Similarly, the functions of receiving device 34 described above are achieved by the processor included in receiving device 34 executing the programs stored in receiving device 34.
　図４は、送信装置３０と受信装置３４の設置に関する第一の構成例を示す。本実施形態が想定する固定マイクロ波方式では、送信装置３０と受信装置３４が何れも固定設置される。このため、図４に示すように、送信装置３０と受信装置３４の間で授受するべき制御信号は、予め設置した有線の経路６０で送信することとしてもよい。 FIG. 4 shows a first example of the configuration regarding the installation of the transmitting device 30 and the receiving device 34. In the fixed microwave method assumed in this embodiment, both the transmitting device 30 and the receiving device 34 are fixedly installed. Therefore, as shown in FIG. 4, the control signal to be exchanged between the transmitting device 30 and the receiving device 34 may be transmitted via a wired path 60 that has been installed in advance.
　図５は、送信装置３０と受信装置３４の設置に関する第二の構成例を示す。第二の構成例では、図５に示す通り、送信装置３０の側に送受アンテナ６２と受信装置６４が設置される。また、受信装置３４の側には、送受アンテナ６６と送信装置６８が設置される。この構成では、受信装置３４から送信装置３０に送信する制御信号は、トラフィック回線と同様に無線信号で授受する。制御信号はデータ量が限られているため、トラフィック回線より細い帯域の無線チャネルで伝送することが可能である。 FIG. 5 shows a second example configuration regarding the installation of the transmitting device 30 and the receiving device 34. In the second example configuration, as shown in FIG. 5, a transmitting/receiving antenna 62 and a receiving device 64 are installed on the transmitting device 30 side. Also, a transmitting/receiving antenna 66 and a transmitting device 68 are installed on the receiving device 34 side. In this configuration, the control signal transmitted from the receiving device 34 to the transmitting device 30 is transmitted and received as a wireless signal, similar to the traffic line. As the data volume of the control signal is limited, it is possible to transmit it over a wireless channel with a narrower bandwidth than the traffic line.
［受信装置における一連の処理］
　図６は、本実施形態において、受信装置３４が実施する一連の処理の流れを説明するためのフローチャートである。図６に示すルーチンは、チャネル毎に起動されるものとする。また、このルーチンは、BERが正常な状況下、つまり、復調方式として６４QAN-V復調がもちいられている状況下で開始されるものとする。 [Series of processes in the receiving device]
Fig. 6 is a flow chart for explaining the flow of a series of processes performed by the receiving device 34 in this embodiment. The routine shown in Fig. 6 is assumed to be started for each channel. In addition, this routine is assumed to be started under a condition where the BER is normal, that is, under a condition where 64QAN-V demodulation is used as the demodulation method.
　ここでは、先ず。RF部５０の機能により、当該チャネルのC/Nが取得される（ステップ１００）。 First, the C/N ratio of the channel is obtained by the function of the RF unit 50 (step 100).
　次に、MOD部５２の機能により、当該チャネルのBERが検知される。そして、検知されたBERが、所望の通信品質を満たし得ない値に劣化しているか否かが判別される（ステップ１０２）。 Next, the BER of the channel is detected by the function of the MOD unit 52. Then, it is determined whether the detected BER has deteriorated to a value that does not satisfy the desired communication quality (step 102).
　BERの劣化は、具体的には、無線キャリア単位でCRCビットによる誤りビット検出を行うことにより判断する。ここでは、無線信号にランダムなビット誤りが含まれ、すべてのビット誤りがCRCエラーとして検出されると仮定してBERを算出する。そして、あらかじめ設定しておいたBERの閾値（例えばBER=1E-6）以上となったときにBERの劣化を判断する。本実施形態では、C/Nによる品質劣化ではなく、BERによる品質劣化に着目してフェージングの影響有無を判断する。これにより、フェージングによる波形歪みを含めた無線伝送品質の劣化を検出することが可能となる。 Specifically, BER degradation is determined by performing error bit detection using CRC bits on a wireless carrier basis. Here, the BER is calculated assuming that the wireless signal contains random bit errors and that all bit errors are detected as CRC errors. BER degradation is then determined when the BER exceeds a preset threshold value (e.g., BER=1E-6). In this embodiment, the presence or absence of the effects of fading is determined by focusing on quality degradation due to BER, rather than quality degradation due to C/N. This makes it possible to detect degradation of wireless transmission quality, including waveform distortion due to fading.
　本ステップ１０２の処理によりBERの劣化が認められなければ、上記ステップ１００の処理が再び実行される。その結果、受信装置３４では、６４QAM-V復調の処理が継続して実施される。一方、BERの劣化が認められた場合は、下記の二つの処理が実施される（ステップ１０４）。 If no degradation of the BER is found by the processing of step 102, the processing of step 100 above is executed again. As a result, the receiving device 34 continues to perform the 64QAM-V demodulation processing. On the other hand, if degradation of the BER is found, the following two processing operations are performed (step 104).
（１）送信装置３０に、表偏波と共に、表偏波と直交する裏偏波を用い、かつ、低多値数を用いる変調方式への変更が要請される。具体的には、６４QAM-V変調から１６QAM-VH変調への変更が要請される。
　（２）変更後の変調方式に対応する復調方式への変更が実施される。具体的には、復調方式が、６４QAM-V復調から１６QAM-VH復調に変更される。 (1) The transmitter 30 is requested to use a front polarized wave as well as a rear polarized wave orthogonal to the front polarized wave, and to change the modulation method to one using a low multi-level number. Specifically, the modulation method is requested to be changed from 64QAM-V to 16QAM-VH.
(2) The demodulation method will be changed to one that corresponds to the changed modulation method. Specifically, the demodulation method will be changed from 64QAM-V demodulation to 16QAM-VH demodulation.
　これにより、送信装置３０および受信装置３４の双方で、変調方式及び復調方式が、同時に、裏偏波、低多値数対応のものに切り替えられる。その結果、送信レートの低下を伴うことなく、フェージングに対する耐性が高められる。 As a result, the modulation and demodulation methods of both the transmitting device 30 and the receiving device 34 are simultaneously switched to those compatible with reverse polarization and low multi-values. As a result, resistance to fading is improved without a decrease in transmission rate.
　以後、受信装置３４は、RF部５０の機能により、当該チャネルのC/Nを監視する（ステップ１０６）。 After this, the receiving device 34 monitors the C/N of the channel using the function of the RF section 50 (step 106).
　また、新たに検出したC/Nが、６４QAMの使用に耐える程度に回復したか、具体的には、６４QAMの所要C/Nである２６ｄB以上に回復したか否かが判別される（ステップ１０８）。ここでは、無線伝送品質の改善を検出するため、無線キャリア単位でC/Nを測定し、C/Nが回復したか否かを判断する。具体的には、外来波干渉、環境雑音、内部雑音、反射波を含めたノイズ成分Nとキャリア成分Cの受信電界強度を測定してC/Nを算出する。そして、あらかじめ設定しておいたC/Nの閾値（６４QAMの所要C/N＝２６dB@BER=1E-6）以上の値を一定時間継続した場合にC/Nが改善したと判断する。 Furthermore, it is determined whether the newly detected C/N has recovered to a level that can withstand the use of 64QAM, specifically, whether it has recovered to 26 dB or more, which is the required C/N for 64QAM (step 108). Here, in order to detect improvements in wireless transmission quality, the C/N is measured on a wireless carrier basis, and it is determined whether the C/N has recovered. Specifically, the C/N is calculated by measuring the received electric field strength of the noise component N, which includes external wave interference, environmental noise, internal noise, and reflected waves, and the carrier component C. Then, if the C/N value remains above a preset C/N threshold (required C/N for 64QAM = 26 dB@BER = 1E-6) for a certain period of time, it is determined that the C/N has improved.
　本ステップ１０８の処理によりC/Nの回復が認められない場合は、上記ステップ１０６の処理が繰り返し実行される。その結果、受信装置３４では、１６QAM-VH復調の処理が継続して実施される。 If the C/N ratio is not recovered by the processing of step 108, the processing of step 106 is repeated. As a result, the receiving device 34 continues to perform the 16QAM-VH demodulation processing.
　一方、C/Nの回復が認められた場合は、下記の二つの処理が実施される（ステップ１１０）。
　（１）送信装置３０に、表偏波で高多値数の変調信号を送信することが要請される。具体的には、１６QAM-VH変調から６４QAM-V変調への復帰が要請される。
　（２）復帰後の変調方式に対応する復調方式への変更が実施される。具体的には、復調方式が、１６QAM-VH復調から６４QAM-V復調に変更される。 On the other hand, if recovery of the C/N ratio is confirmed, the following two processes are carried out (step 110).
(1) The transmitting device 30 is requested to transmit a high-order modulation signal in front polarization. Specifically, a return from 16QAM-VH modulation to 64QAM-V modulation is requested.
(2) The demodulation method will be changed to a method that corresponds to the modulation method after the return to normal operation. Specifically, the demodulation method will be changed from 16QAM-VH demodulation to 64QAM-V demodulation.
　C/Nが復帰しているため、変調方針および復調方式の復帰後は、表偏波で高多値数の変調信号を送受する手法で良好なBERを維持することができる。以後、受信装置３４では、上記ステップ１００以降の処理が繰り返し実行される。 Since the C/N ratio has been restored, after the modulation strategy and demodulation method are restored, a good BER can be maintained by transmitting and receiving a high multi-level modulated signal with front polarization. After that, the receiving device 34 repeatedly executes the processes from step 100 onwards.
［送信装置における一連の処理］
　図７は、本実施形態において、送信装置３０が実施する一連の処理の流れを説明するためのフローチャートである。図７に示すルーチンは、図６に示すルーチンと同様に、チャネル毎に、BERが正常な状況下で開始されるものとする。 [Series of processes in the transmitting device]
Fig. 7 is a flowchart for explaining the flow of a series of processes performed by the transmitting device 30 in this embodiment. The routine shown in Fig. 7 is assumed to be started under normal BER conditions for each channel, similar to the routine shown in Fig. 6.
　ここでは、先ず。表偏波で高多値数の変調信号を送信する手法が設定される。具体的には、６４QAM-V変調の方式が設定される（ステップ１２０）。 First, a method for transmitting a high-level modulation signal using front polarization is set. Specifically, the 64QAM-V modulation method is set (step 120).
　次に、受信装置３４から、変調方式の変更が要請されたか否かが判別される（ステップ１２２）。変調方式の変更が要請されていなければ、上記ステップ１００の処理が繰り返される。その結果、送信装置３０では、６４QAM-V変調の処理が継続して実施される。 Next, it is determined whether or not a change in the modulation method has been requested from the receiving device 34 (step 122). If a change in the modulation method has not been requested, the processing of step 100 above is repeated. As a result, the transmitting device 30 continues to process 64QAM-V modulation.
　一方、変調方式の変更要請が認められた場合は、表偏波と共に裏偏波を用い、かつ、低多値数を用いる変調方式への変更が実施される（ステップ１２４）。具体的には、６４QAM-V変調から１６QAM-VH変調への変更が実施される。これにより、裏偏波へのトラヒックの分散が図られ、かつ、変調の多値数が低減されて、送信レートを確保したままフェージングに対する耐性が高められる。 On the other hand, if the request to change the modulation method is approved, the modulation method is changed to one that uses both the front and back polarizations and uses a lower modulation level (step 124). Specifically, the modulation is changed from 64QAM-V to 16QAM-VH. This distributes traffic to the back polarization and reduces the modulation level, improving resistance to fading while maintaining the transmission rate.
　以後、送信装置３０は、受信装置３４から、変調方式の復帰が要請されたか否かを判別する（ステップ１２６）。そして、復帰要請の受信が認められない場合は、上記ステップ１２４の処理が繰り返される。その結果、送信装置３０では、１６QAM-VH変調の処理が継続して実施される。 Then, the transmitting device 30 determines whether or not a request to return to the modulation method has been received from the receiving device 34 (step 126). If the request to return is not received, the processing of step 124 is repeated. As a result, the transmitting device 30 continues to perform 16QAM-VH modulation processing.
　一方、受信装置３４から変調方式の復帰要請を受けたと認められた場合は、高多値数対応の変調方式を復帰させ、かつ、裏偏波による送信が停止される（ステップ１２８）。具体的には、１６QAM-VH変調から６４QAM-V変調への復帰が実施される。以後、上述したステップ１２０以降の処理が繰り返し実施される。 On the other hand, if it is determined that a request to restore the modulation method has been received from the receiving device 34, the modulation method compatible with high multi-values is restored and transmission using the reverse polarization is stopped (step 128). Specifically, a return is made from 16QAM-VH modulation to 64QAM-V modulation. Thereafter, the processing from step 120 onwards described above is repeatedly performed.
　以上の処理によれば、受信装置３４側に単一のアンテナ３６（または送受アンテナ６６６）を設けるだけで、送信レートを犠牲にすることなくフェージングに対する耐性を高めることができる。このため、本実施形態によれば、多大な設置負担を発生させることなくフェージングに対する優れた耐性を実現する無線中継システムを実現することができる。 According to the above process, simply providing a single antenna 36 (or a transmitting/receiving antenna 666) on the receiving device 34 side can increase resistance to fading without sacrificing the transmission rate. Therefore, according to this embodiment, it is possible to realize a wireless relay system that achieves excellent resistance to fading without incurring a large installation burden.
［実施の形態１の変形例］
　ところで、上述した実施の形態１では、無線信号をFDD（Frequency Division Duplex）の方式で送受する例を示しているが、本開示はこれに限定されるものではない。裏偏波と低い変調多値数を用いてフェージング耐性を高める手法は、TDD（Time Division Duplex）の方式と組み合わせて用いてもよい。 [Modification of the first embodiment]
Incidentally, in the above-mentioned first embodiment, an example is shown in which a wireless signal is transmitted and received by the FDD (Frequency Division Duplex) method, but the present disclosure is not limited to this. The method of increasing fading resistance by using reverse polarization and a low modulation multi-level number may be used in combination with the TDD (Time Division Duplex) method.
　また、上述した実施の形態１では、６４QAMを１６QAMに切り替えてフェージングに対する耐性を高めることとしているが、フェージングに対する耐性を高める手法はこれに限定されるものではない。例えば、１６PSK、８PSK、QPSK、BPSK等の切り替えにより変調多値数を下げることでその耐性を高めることとしてもよい。更には、QAMによる変調方式と、PSKによる変調方式との間で切り替えを行ってフェージング耐性を高めることとしてもよい。 In addition, in the above-mentioned embodiment 1, 64QAM is switched to 16QAM to increase resistance to fading, but the method of increasing resistance to fading is not limited to this. For example, resistance may be increased by lowering the modulation multi-level number by switching between 16PSK, 8PSK, QPSK, BPSK, etc. Furthermore, resistance to fading may be increased by switching between a modulation method using QAM and a modulation method using PSK.
　また、上述した実施の形態１では、フェージングの影響が生じたチャネルにおいて、表偏波と裏偏波の双方を用いることで、劣化前の送信レートを維持することとしているが、送信レートの維持は必須条件ではない。ある程度のレート低下が認められる環境下では、そのようなレート低下を許容する組み合わせで変調多値数を切り替えることとしてもよい。 In addition, in the above-mentioned embodiment 1, in a channel affected by fading, the transmission rate before degradation is maintained by using both the front polarization and the back polarization, but maintaining the transmission rate is not a mandatory condition. In an environment where a certain degree of rate reduction is recognized, the modulation multi-level number may be switched to a combination that allows such a rate reduction.
　また、上述した実施の形態１では、BERの検出を、CRCビットによる誤りビット検出により行うこととしているが、その手法もこれに限定されるものではない。BERは、周知の如何なる手法を検出することとしてもよい。 In the above-mentioned first embodiment, the BER is detected by detecting error bits using CRC bits, but the method is not limited to this. The BER may be detected using any known method.
　また、上述した実施の形態１では、フェージングによる波形歪みを含めた品質劣化を検出する観点から、BERの劣化が認められた場合に変調多値数を下げて裏偏波の使用を開始することとしているが、本開示はこれに限定されるものではない。この切り替えは、C/Nの劣化に基づいて実施することとしてもよい。 In addition, in the above-mentioned first embodiment, from the viewpoint of detecting quality degradation including waveform distortion due to fading, if degradation of the BER is detected, the modulation multi-level number is reduced and the use of the reverse polarization is started, but the present disclosure is not limited to this. This switching may also be performed based on degradation of the C/N ratio.
３０　送信装置
３２、３６　アンテナ
３４　受信装置
４４、５２　MOD部
４６、５０　RF部
４８、５８　監視制御部 30 Transmitting device 32, 36 Antenna 34 Receiving device 44, 52 MOD section 46, 50 RF section 48, 58 Monitoring and control section

Claims (8)

  1. 　無線信号を送信する送信装置と、前記送信装置から無線信号を受信する受信装置とを含む無線中継システムであって、
    　前記送信装置は、
    　表偏波と裏偏波に対応する送信アンテナを備え、
    　前記表偏波で第一多値数による変調信号を送信する第一変調処理と、
    　前記表偏波および前記裏偏波の双方を用いて、前記第一多値数より少ない第二多値数による変調信号を送信する第二変調処理と、
    　前記受信装置からの切り替え要請を受けて前記第一変調処理を前記第二変調処理に切り替える処理と、
    　前記受信装置からの復帰要請を受けて前記第二変調処理を前記第一変調処理に復帰させる処理と、を実行するように構成され、
    　前記受信装置は、
    　前記表偏波と前記裏偏波に対応する受信アンテナを備え、
    　前記表偏波で送信されてくる前記第一多値数による変調信号を復調する第一復調処理と、
    　前記表偏波および前記裏偏波の双方を用いて送信されてくる前記第二多値数による変調信号を復調する第二復調処理と、
    　前記送信装置から受信した前記無線信号に、判断基準を超えるフェージングの影響が認められた場合に、前記送信装置に向けて前記切り替え要請を送信すると共に、前記第一復調処理を前記第二復調処理に切り替える処理と、
    　前記フェージングの影響が解消されたと認められた場合に、前記送信装置に向けて前記復帰要請を送信すると共に、前記第二復調処理を前記第一復調処理に復帰させる処理と、を実行するように構成された無線中継システム。     A wireless relay system including a transmitting device that transmits a wireless signal and a receiving device that receives the wireless signal from the transmitting device,
    The transmitting device includes:
    Equipped with a transmitting antenna that supports both front and back polarization,
    a first modulation process for transmitting a modulated signal with a first multi-level number in the front polarization;
    A second modulation process of transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarization and the back polarization;
    a process of switching from the first modulation process to the second modulation process in response to a switching request from the receiving device;
    and a process of returning the second modulation process to the first modulation process in response to a return request from the receiving device,
    The receiving device includes:
    a receiving antenna corresponding to the front polarized wave and the back polarized wave,
    a first demodulation process for demodulating a modulated signal by the first multi-level number transmitted by the front polarization;
    a second demodulation process for demodulating a modulated signal by the second multi-level number transmitted using both the front polarization and the back polarization;
    a process of transmitting the switching request to the transmitting device and switching the first demodulation process to the second demodulation process when an influence of fading exceeding a judgment criterion is recognized in the wireless signal received from the transmitting device;
    A wireless relay system configured to execute a process of transmitting the return request to the transmitting device and returning the second demodulation process to the first demodulation process when it is determined that the effect of fading has been resolved.
  2. 　前記受信装置は、
    　前記送信装置から受信した前記無線信号のBERを監視する処理と、
    　前記送信装置から受信した前記無線信号のC/Nを監視する処理と、を更に実行し、
    　前記フェージングの影響が認められるか否かを、前記BERおよび前記C/Nの少なくとも一方に基づいて判断し、
    　前記フェージングの影響が解消されたか否かを、前記C/Nに基づいて判断するように構成されている請求項１に記載の無線中継システム。     The receiving device includes:
    monitoring a BER of the wireless signal received from the transmitting device;
    and monitoring the C/N of the wireless signal received from the transmitting device.
    determining whether or not the effect of fading is recognized based on at least one of the BER and the C/N;
    2. The wireless relay system according to claim 1, further comprising a step of judging whether the effect of fading has been eliminated based on the C/N ratio.
  3. 　前記送信装置と前記受信装置は、複数のチャネルで前記無線信号を送受し、
    　前記第一変調処理と前記第二変調処理との切り替えおよび復帰、並びに前記第一復調処理と前記第二復調処理との切り替えおよび復帰は、前記チャネルのそれぞれについて実行される請求項１または２に記載の無線中継システム。     The transmitting device and the receiving device transmit and receive the wireless signals through a plurality of channels;
    3. The wireless relay system according to claim 1, wherein the switching and returning between the first modulation processing and the second modulation processing, and the switching and returning between the first demodulation processing and the second demodulation processing are performed for each of the channels.
  4. 　送信装置から受信した無線信号を中継する無線中継装置であって、
    　表偏波と裏偏波に対応する受信アンテナを備え、
    　前記表偏波で送信されてくる第一多値数による変調信号を復調する第一復調処理と、
    　前記表偏波および前記裏偏波の双方を用いて送信されてくる、前記第一多値数より少ない第二多値数による変調信号を復調する第二復調処理と、
    　前記送信装置から受信した前記無線信号に、判断基準を超えるフェージングの影響が認められた場合に、前記送信装置に向けて、前記表偏波で前記第一多値数による変調信号を送信する第一変調処理を、前記表偏波および前記裏偏波の双方で前記第二多値数による変調信号を送信する第二変調処理に切り替えることを要請すると共に、前記第一復調処理を前記第二復調処理に切り替える処理と、
    　前記フェージングの影響が解消されたと認められた場合に、前記送信装置に向けて前記第二変調処理を前記第一変調処理に復帰させることを要請すると共に、前記第二復調処理を前記第一復調処理に復帰させる処理と、
    　を実行するように構成された無線中継装置。     A wireless relay device that relays a wireless signal received from a transmitting device,
    Equipped with a receiving antenna that supports both front and back polarization,
    a first demodulation process for demodulating a modulated signal having a first multilevel number transmitted by the front polarization;
    a second demodulation process for demodulating a modulated signal transmitted using both the front polarization and the back polarization, the modulated signal being modulated by a second multi-level number that is smaller than the first multi-level number;
    a process of requesting the transmitting device to switch a first modulation process for transmitting a modulated signal with the first multi-level number in the front polarization to a second modulation process for transmitting a modulated signal with the second multi-level number in both the front polarization and the back polarization when an influence of fading exceeding a judgment criterion is found in the wireless signal received from the transmitting device, and switching the first demodulation process to the second demodulation process;
    a process of requesting the transmitting device to return from the second modulation process to the first modulation process and returning from the second demodulation process to the first demodulation process when it is determined that the influence of the fading has been eliminated;
    A wireless relay device configured to perform the steps of:
  5. 　中継の対象である無線信号を受信装置に向けて送信する無線中継装置であって、
    　表偏波と裏偏波に対応する送信アンテナを備え、
    　前記表偏波で第一多値数による変調信号を送信する第一変調処理と、
    　前記表偏波および前記裏偏波の双方を用いて、前記第一多値数より少ない第二多値数による変調信号を送信する第二変調処理と、
    　前記受信装置からの切り替え要請を受けて前記第一変調処理を前記第二変調処理に切り替える処理と、
    　前記受信装置からの復帰要請を受けて前記第二変調処理を前記第一変調処理に復帰させる処理と、を実行するように構成された無線中継装置。     A wireless relay device that transmits a wireless signal to be relayed to a receiving device,
    Equipped with a transmitting antenna that supports both front and back polarization,
    a first modulation process for transmitting a modulated signal with a first multi-level number in the front polarization;
    A second modulation process of transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarization and the back polarization;
    a process of switching from the first modulation process to the second modulation process in response to a switching request from the receiving device;
    and a process of restoring the second modulation process to the first modulation process upon receiving a restoration request from the receiving device.
  6. 　送信装置と、当該送信装置から無線信号を受信する受信装置とを用いて前記無線信号を中継するための無線中継方法であって、
    　前記送信装置が、
    　表偏波で第一多値数による変調信号を送信する第一変調を実行することと、
    　前記表偏波および裏偏波の双方を用いて、前記第一多値数より少ない第二多値数による変調信号を送信する第二変調を実行することと、
    　前記受信装置からの切り替え要請を受けて前記第一変調を前記第二変調に切り替えることと、
    　前記受信装置からの復帰要請を受けて前記第二変調を前記第一変調に復帰させることと、
    　前記受信装置が、
    　前記表偏波で送信されてくる前記第一多値数による変調信号を復調する第一復調を実行することと、
    　前記表偏波および前記裏偏波の双方を用いて送信されてくる前記第二多値数による変調信号を復調する第二復調を実行することと、
    　前記送信装置から受信した前記無線信号に、判断基準を超えるフェージングの影響が認められた場合に、前記送信装置に向けて前記切り替え要請を送信すると共に、前記第一復調を前記第二復調に切り替えることと、
    　前記フェージングの影響が解消されたと認められた場合に、前記送信装置に向けて前記復帰要請を送信すると共に、前記第二復調を前記第一復調に復帰させることと、
    　を含む無線中継方法。     1. A wireless relay method for relaying a wireless signal using a transmitting device and a receiving device that receives a wireless signal from the transmitting device, comprising:
    The transmitting device,
    performing a first modulation to transmit a modulated signal with a first multilevel number in a front polarization;
    performing a second modulation for transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarized wave and the back polarized wave;
    switching the first modulation to the second modulation in response to a switching request from the receiving device;
    restoring the second modulation to the first modulation upon receiving a restoration request from the receiving device;
    The receiving device,
    performing a first demodulation for demodulating a modulated signal by the first multilevel number transmitted by the front polarization;
    performing a second demodulation to demodulate the modulated signal by the second multi-level number transmitted by using both the front polarization and the back polarization;
    when an influence of fading exceeding a judgment criterion is found in the wireless signal received from the transmitting device, transmitting the switching request to the transmitting device and switching the first demodulation to the second demodulation;
    when it is determined that the effect of the fading has been eliminated, transmitting the restoration request to the transmitting device and restoring the second demodulation to the first demodulation;
    A wireless relay method comprising:
  7. 　送信装置から受信した無線信号を受信装置に中継させるための無線中継用プログラムであって、
    　前記受信装置は、
    　表偏波と裏偏波に対応する受信アンテナと、
    　プロセッサと、を備え、
    　前記プロセッサに、
    　前記表偏波で送信されてくる第一多値数による変調信号を復調する第一復調処理と、
    　前記表偏波および前記裏偏波の双方を用いて送信されてくる、前記第一多値数より少ない第二多値数による変調信号を復調する第二復調処理と、
    　前記送信装置から受信した前記無線信号に、判断基準を超えるフェージングの影響が認められた場合に、前記送信装置に向けて、前記表偏波で前記第一多値数による変調信号を送信する第一変調処理を、前記表偏波および前記裏偏波の双方で前記第二多値数による変調信号を送信する第二変調処理に切り替えることを要請すると共に、前記第一復調処理を前記第二復調処理に切り替える処理と、
    　前記フェージングの影響が解消されたと認められた場合に、前記送信装置に向けて前記第二変調処理を前記第一変調処理に復帰させることを要請すると共に、前記第二復調処理を前記第一復調処理に復帰させる処理と、
    　を実行させるコンピュータ読み取り可能なプログラムを含む無線中継用プログラム。     A wireless relay program for relaying a wireless signal received from a transmitting device to a receiving device,
    The receiving device includes:
    A receiving antenna that supports front and back polarization;
    a processor;
    The processor,
    a first demodulation process for demodulating a modulated signal having a first multilevel number transmitted by the front polarization;
    a second demodulation process for demodulating a modulated signal transmitted using both the front polarization and the back polarization, the modulated signal being modulated by a second multi-level number that is smaller than the first multi-level number;
    a process of requesting the transmitting device to switch a first modulation process for transmitting a modulated signal with the first multi-level number in the front polarization to a second modulation process for transmitting a modulated signal with the second multi-level number in both the front polarization and the back polarization when an influence of fading exceeding a judgment criterion is found in the wireless signal received from the transmitting device, and switching the first demodulation process to the second demodulation process;
    a process of requesting the transmitting device to return from the second modulation process to the first modulation process and returning from the second demodulation process to the first demodulation process when it is determined that the influence of the fading has been eliminated;
    A radio relay program comprising a computer readable program for causing a radio relay program to execute the above steps.
  8. 　中継の対象である無線信号を受信装置に向けて送信装置に送信させるための無線中継用プログラムであって、
    　前記送信装置は、
    　表偏波と裏偏波に対応する送信アンテナと、
    　プロセッサと、を備え、
    　前記プロセッサに、
    　前記表偏波で第一多値数による変調信号を送信する第一変調処理と、
    　前記表偏波および前記裏偏波の双方を用いて、前記第一多値数より少ない第二多値数による変調信号を送信する第二変調処理と、
    　前記受信装置からの切り替え要請を受けて前記第一変調処理を前記第二変調処理に切り替える処理と、
    　前記受信装置からの復帰要請を受けて前記第二変調処理を前記第一変調処理に復帰させる処理と、
    　を実行させるコンピュータ読み取り可能なプログラムを含む無線中継用プログラム。
    　     A wireless relay program for causing a transmitting device to transmit a wireless signal to be relayed toward a receiving device,
    The transmitting device includes:
    A transmitting antenna corresponding to front and back polarization;
    a processor;
    The processor,
    a first modulation process for transmitting a modulated signal with a first multi-level number in the front polarization;
    A second modulation process of transmitting a modulated signal with a second multi-level number that is smaller than the first multi-level number by using both the front polarization and the back polarization;
    a process of switching from the first modulation process to the second modulation process in response to a switching request from the receiving device;
    a process of returning the second modulation process to the first modulation process in response to a return request from the receiving device;
    A radio relay program comprising a computer readable program for causing a radio relay program to execute the above steps.
PCT/JP2023/009942 2023-03-14 2023-03-14 Radio relay system, radio relay device, radio relay method, and radio relay program WO2024189797A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013005585A1 (en) * 2011-07-01 2013-01-10 日本電気株式会社 Cross-polar interference cancellation system, wireless station device, wireless communication method
WO2014020796A1 (en) * 2012-08-03 2014-02-06 日本電気株式会社 Wireless communication system and control method therefor
JP2017038310A (en) * 2015-08-12 2017-02-16 日本電信電話株式会社 Radio line allocation method and radio line allocation device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013005585A1 (en) * 2011-07-01 2013-01-10 日本電気株式会社 Cross-polar interference cancellation system, wireless station device, wireless communication method
WO2014020796A1 (en) * 2012-08-03 2014-02-06 日本電気株式会社 Wireless communication system and control method therefor
JP2017038310A (en) * 2015-08-12 2017-02-16 日本電信電話株式会社 Radio line allocation method and radio line allocation device

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