Relay radio device and radio relay method

Abstract

The present disclosure relates to a relaying radio device and a radio relaying method for relaying a carrier transmitted from a host radio station with a radio signal, and has a purpose of providing the relaying radio device and radio relaying method wherein the carrier signal satisfies a required C / N and the BER does not degrade even in the case of occurrence of a power loss of the carrier due to a feeding line. The present disclosure is a relaying radio device for relaying a carrier transmitted from a host radio station with a radio signal, said relaying radio device being configured to execute: modulation scheme conversion processing of converting the modulation scheme of the carrier to a modulation scheme having a lower multi-level number; and bandwidth conversion processing of expanding the frequency band of the carrier such that the transfer amount of the carrier is the same before and after the modulation scheme conversion processing.

Description

[Technical Field]

[0001] The present disclosure relates to a relay radio device and a radio relay method for relaying a carrier wave transmitted as a radio signal from a higher-level radio station. [Background technology]

[0002] In relay radio equipment that relays carrier waves transmitted as radio signals from a higher-level radio station, the antenna installed on a steel tower and the radio equipment installed indoors are often far apart. As a result, losses in the power feeder line connecting the two (hereinafter referred to as "power feeder loss") tend to increase. One way to deal with power feeder loss is to install an amplifier inside the radio equipment. This can amplify the received signal level that is attenuated by power feeder loss.

[0003] On the other hand, Non-Patent Document 1 discloses a method of placing a low noise amplifier (LNA) as a preamplifier immediately adjacent to the antenna in a communication receiver, which makes it possible to amplify a weak desired signal to a predetermined reception level. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "Knowledge Base 4 Groups, Part 1, Chapter 11, Receivers" (Kenji Ito, Institute of Electronics, Information and Communication Engineers, Ver.1 / 2010.11.9) Summary of the Invention [Problem to be solved by the invention]

[0005] However, because amplifiers amplify not only the power level of the desired signal contained in the carrier wave but also the noise power level at the same time, no matter where the amplifier is placed within the relay radio equipment, it is not possible to expect an improvement in the C / N (carrier-to-noise ratio).As a result, if the feeder loss is large, the carrier signal does not meet the required C / N, causing a degradation in the BER (Bit Error Rate).

[0006] In order to solve the above-mentioned problems, the first object of the present disclosure is to provide a relay radio device in which the carrier signal satisfies the required C / N ratio and the BER does not degrade even when there is power loss of the carrier wave due to the power feed line.

[0007] A second object of the present disclosure is to provide a wireless relay method in which a carrier signal satisfies a required C / N ratio and the BER does not deteriorate even when there is a power loss of the carrier due to a feeder line. [Means for solving the problem]

[0008] A first aspect of the present disclosure is a relay radio device that relays a carrier wave transmitted as a radio signal from an upper radio station, the relay radio device comprising: a modulation method conversion process for converting the modulation method of the carrier wave into a modulation method with a lower multi-value; a bandwidth conversion process for expanding the frequency band of the carrier wave so that the transmission capacity of the carrier wave is equal before and after the modulation method conversion process; Preferably, the system is configured to perform the following:

[0009] A second aspect of the present disclosure is a wireless relay method for relaying a carrier wave transmitted as a wireless signal from an upper wireless station, the method comprising: a modulation method conversion process for converting the modulation method of the carrier wave into a modulation method with a lower multi-value; a bandwidth conversion process for expanding the frequency band of the carrier wave so that the transmission capacity of the carrier wave is equal before and after the modulation method conversion process; It is preferable to perform the following. [Effects of the Invention]

[0010] According to the first and second aspects of the present disclosure, it is possible to provide a radio relay device and a radio relay method in which the carrier signal satisfies the required C / N ratio and the BER does not deteriorate even when there is a power loss of the carrier due to the power feed line. [Brief explanation of the drawings]

[0011] [Figure 1] 10 is a schematic diagram illustrating a conventional relay wireless device and a modulation method of a carrier wave received by the relay wireless device according to a comparative example of the present disclosure. FIG. [Figure 2] 10 is a schematic diagram illustrating a conventional relay radio device including an LNA as a pre-amplifier, and a modulation method of a carrier wave received by the relay radio device, according to a comparative example of the present disclosure. FIG. [Figure 3] 10A and 10B are schematic diagrams illustrating configuration examples of a higher-level station, a relay wireless device, and a lower-level station according to a comparative example of the present disclosure, and a modulation method of a carrier wave relayed by the relay wireless device. [Figure 4] FIG. 10 is a schematic diagram illustrating an example of a functional configuration of a conventional relay wireless device according to a comparative example of the present disclosure. [Figure 5] 1 is a schematic diagram illustrating a relay radio device and a modulation method of a carrier wave received by the relay radio device according to a first embodiment of the present disclosure. [Figure 6] 2 is a diagram illustrating an example of a functional configuration of a relay wireless device according to a first embodiment of the present disclosure. FIG. [Figure 7] FIG. 10 is a schematic diagram illustrating a relay radio device including an LNA and a carrier modulation method according to a second embodiment of the present disclosure. [Figure 8] FIG. 10 is a diagram illustrating an example of a functional configuration of a relay wireless device according to a second embodiment of the disclosure. [Figure 9] 11 is a schematic diagram illustrating an example of the configuration of a higher-level station, a relay radio device, and a lower-level station according to a third embodiment of the present disclosure, and a modulation method of a carrier wave relayed by the relay radio device. FIG. [Figure 10] FIG. 2 is a diagram illustrating an example of a functional configuration of a transmitting device that performs wireless communication with a relay wireless device. [Figure 11] FIG. 11 is a schematic diagram illustrating an example of a functional configuration of a relay wireless device according to a third embodiment of the present disclosure. [Figure 12]FIG. 10 is a schematic diagram illustrating an example of the configuration of a higher-level station, a relay radio device, and a lower-level station according to a fourth embodiment of the present disclosure, and a modulation method for a carrier wave relayed by the relay radio device. [Figure 13] 13 is a flowchart of a process performed by a relay wireless device according to a fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Comparative Example First, a comparative example will be described. Fig. 1 is a schematic diagram showing a conventional relay radio device and a modulation method of a carrier wave received by the relay radio device according to a comparative example of the present disclosure.

[0013] 1, a relay radio device 100 relays a carrier wave 140 transmitted as a radio signal from a higher-level radio station (hereinafter referred to as a higher-level station). An antenna 110 of the relay radio device 100 receives the carrier wave 140 transmitted from the higher-level station and reaching the relay radio device 100. The carrier wave 140 received by the antenna 110 passes through a feeder line 120 and is sent to a radio device 130.

[0014] The radio device 130 is a receiver that performs demodulation and error correction coding on the carrier wave 140 received by the antenna 110 and transmitted via the feeder line 120. Furthermore, the radio device 130 transmits the demodulated and error correction coded signal to a terminal.

[0015] The carrier wave 140 occupies a certain range of frequency band, but the occupied frequency band is not limited. The modulation method of the carrier wave 140 is, for example, 64QAM (Quadrature Amplitude Modulation). Here, panel P11 in Figure 1 shows the frequency characteristics of the power of the carrier wave 140 when received by the antenna. Also, the C / N of the carrier wave here is assumed to be A.

[0016] Although only one carrier wave 140 is shown in panel P11, the wireless transmission method may be multi-carrier transmission that includes multiple carrier waves 140. Alternatively, as in panel P11, the wireless transmission method may be single-carrier transmission that includes only one carrier wave 140. This point is assumed to be common to the comparative examples and embodiments that follow.

[0017] When carrier wave 140 passes through feed line 120, a feed line loss L occurs. Panel P12 of FIG. 1 shows the frequency characteristics of the power of carrier wave 140 after passing through feed line 120. After passing through feed line 120, the power of carrier wave 140 decreases by the amount of feed line loss L. Therefore, the C / N after passing through feed line 120 is expressed as (C / N=AL).

[0018] In wireless communication, the C / N at which the BER becomes a specified value is calculated for each modulation method. For example, in the case of 64QAM, the required C / N is 24.2 dB. If the C / N of the carrier 140 input to the wireless device 130 does not satisfy this required C / N, the BER will deteriorate.

[0019] Therefore, even if the C / N (=A) is equal to or greater than the required C / N when receiving through antenna 110 (panel P11), if the feeder loss L is large and the C / N (=AL) after passing through feeder 120 is lower than the required C / N (panel P12), BER degradation occurs.

[0020] In the prior art, an amplifier is placed within the radio device 130, but even if the signal of the carrier wave 140 (panel P12) after passing through the power supply line 120 is amplified, the amplifier itself does not have the effect of improving the C / N ratio, so degradation of the BER is unavoidable.

[0021] As described above, in the conventional relay radio device 100, the degradation of the BER due to the feed line loss of the carrier wave 140 was unavoidable.

[0022] 2 is a schematic diagram showing a conventional relay radio device having an LNA as a pre-amplifier and the modulation method of the carrier wave received by the relay radio device according to a comparative example of the present disclosure. The relay radio device 200 is similar to the relay radio device 100 in FIG. 1, but an LNA 210 with good internal noise characteristics is installed as a pre-amplifier immediately adjacent to the antenna 110. The LNA 210 is used when the antenna 110 receives weak radio waves, such as in satellite communications.

[0023] 2, panels P21 and P22 respectively show the frequency characteristics of the power of the carrier wave 140 when received by the antenna 110 and after amplification by the LNA 210. The weak carrier wave signal when received by the antenna 110 is amplified by the LNA 210. By amplifying the signal of the carrier wave 140 in the immediate vicinity of the antenna 110 in this way, it is possible to prevent the noise power generated within the feeder line 120 from being amplified.

[0024] However, even if a front-stage amplifier is installed close to antenna 110 as in Fig. 2, the amplifier itself has no effect on improving the C / N ratio, and therefore, if a large feed line loss L occurs, the C / N ratio will deteriorate. Therefore, in this case as well, as in Fig. 1, carrier wave 140 input to radio device 130 does not satisfy the required C / N ratio, and deterioration of the BER is unavoidable (panel P23 in Fig. 2).

[0025] FIG. 3 is a schematic diagram showing an example of the configuration of an upper station, a relay radio device, and a lower radio station (hereinafter referred to as a lower station) according to a comparative example of the present disclosure, and a modulation method of a carrier wave relayed by the relay radio device.

[0026] The relay radio device 300 relays signals between upper and lower radio stations. The relay radio device 300 receives a carrier wave 140 transmitted from an antenna 310 of a transmitting device 301, which is an upper station, using a receiving antenna 320. The relay radio device 300 then transmits the carrier wave 140 to a radio device 340 via a power feeder 330. The radio device 340 amplifies the received carrier wave 140, demodulates it once, and then modulates it again. The re-modulated carrier wave 140 is then transmitted to a transmitting antenna 360 via a power feeder 350.

[0027] The lower level stations are the relay radio devices 100 and 200 that receive the carrier wave 140 transmitted from the relay radio device 300. The functions of the relay radio devices 100 and 200 are the same as those explained in Figures 1 and 2, so explanations will be omitted.

[0028] In Fig. 3, panel P31 shows the power frequency characteristics of carrier 140 after passing through feeder line 330. As with panel P11 in Fig. 1, the C / N ratio of the carrier is reduced by the amount of feeder line loss L. Panel P32 shows the frequency characteristics of carrier 140 power at transmitting antenna 360. Here too, a reduction in C / N occurs due to feeder line 350.

[0029] Furthermore, carrier wave 140 transmitted from transmitting antenna 360 is affected by fading while propagating through the wireless section. Therefore, the power of carrier wave 140 at radio device 130 of relay radio devices 100 and 200 that receives carrier wave 140 is reduced not only by feed line loss L due to feed line 120 but also by propagation loss L0 of carrier wave 140 in the wireless section (panel P33).

[0030] Therefore, even if the C / N ratio of the carrier 140 at the transmitting antenna 360 of the relay radio device 300 is equal to or greater than the required C / N ratio (panel P32), if the propagation loss L0 is large, the required C / N ratio cannot be met at the relay radio devices 100 and 200 (panel P33). This results in BER degradation. Note that the longer the wireless section, the greater the propagation loss L0. Therefore, the effect of BER degradation is particularly noticeable when the relay radio device 300 and the relay radio devices 100 and 200 are far apart.

[0031] 3, the case where the upper station is the transmitting device 301 has been described. However, the upper station may be any wireless station having a wireless transmitting function, such as a wireless base station or a wireless relay station. Similarly, the lower station does not have to be the relay wireless device 100 or 200, but may be any wireless station having a wireless receiving function, such as a wireless base station or a wireless relay station. This point is also common to the comparative examples and embodiments that follow.

[0032] 4 is a schematic diagram showing an example of the functional configuration of a conventional relay radio device according to a comparative example of the present disclosure. In FIG. 4, a receiving antenna 320 receives a carrier wave 140 and transmits it to a radio device 340 via a power feeder 330. The radio device 340 demodulates, corrects errors in, and remodulates the received carrier wave 140. The radio device 340 includes an RF receiving processor 370, a DEM unit 380, a MOD unit 390, an RF transmitting processor 400, and a monitoring controller 410.

[0033] The RF reception processing unit 370 processes radio frequency (RF) signals input from the receiving antenna 320. The RF reception processing unit 370 includes a reception AMP unit 371, an AGC (Automatic Gain Control) unit 372, and a C / N detection unit 373. The reception AMP unit 371 amplifies the received radio frequency signals. The AGC unit 372 automatically corrects the reception gain according to the level of the received signal. The C / N detection unit 373 detects the C / N of the input carrier wave 140.

[0034] The DEM unit 380 is a unit that performs demodulation and error correction, and monitors and controls the BER for the signal input from the RF reception processing unit 370. The DEM unit 380 has a waveform equalization unit 381, a signal demodulation unit 382, ​​an error correction unit 383, and a BER monitoring unit 384. The waveform equalization unit 381 is a unit that equalizes the waveform of the received signal to a desired waveform. The signal demodulation unit 382 is a unit that demodulates the waveform of the received signal. The error correction unit 383 is a unit that performs error correction decoding. The BER monitoring unit 384 is a unit that monitors whether or not degradation of the BER has occurred based on the modulation method of the input carrier wave.

[0035] The MOD unit 390 is a unit that re-modulates the signal input from the DEM unit 380. The MOD unit 390 includes a waveform shaping unit 391, an FEC (Forward Error Correction) encoding unit 392, and a signal modulation unit 393. The waveform shaping unit 391 is a unit that shapes the waveform of the signal. The FEC encoding unit 392 is a unit that assigns an error correction code to the signal. The signal modulation unit 393 is a unit that performs re-modulation.

[0036] The RF transmission processing unit 400 is a unit that performs transmission processing on the transmission signal input from the MOD unit 390. The RF transmission processing unit 400 includes a transmission AMP unit 401 and a filter unit 402. The transmission AMP unit 401 amplifies the transmission signal. The filter unit 402 removes unnecessary frequency components from the transmission signal.

[0037] The monitoring control unit 410 monitors the RF reception processing unit 370, the DEM unit 380, the MOD unit 390, and the RF transmission processing unit 400. It also receives an alarm and performs control when a predetermined process cannot be executed in each unit. It also controls each unit when there is a problem such as power interference with other wireless stations and it is necessary to urgently stop the processing of the own station.

[0038] The transmitting antenna 360 transmits the carrier wave 140 transmitted from the RF transmission processing unit 400 via the feeder line 350 to the lower-level station as a radio signal.

[0039] In this way, the conventional relay radio device 300 demodulates the received carrier wave 140 once, re-modulates it, and then transmits it to the downstream station. The demodulation and re-modulation require a large radio device 340, and due to maintenance and other issues, the radio device 340 has to be installed indoors. This results in a large distance between the antenna and the radio device 340, and significant power line loss occurs in the power lines 330 and 340 connecting the two.

[0040] As explained above with reference to Figures 1 to 4, in the conventional relay radio devices 100, 200, and 300, when the feeder line loss and propagation loss are large, the C / N of the carrier wave does not satisfy the required C / N, resulting in BER degradation.

[0041] Embodiment 1 5 is a schematic diagram illustrating a relay radio device and a modulation method of a carrier wave received by the relay radio device according to the first embodiment of the present disclosure. The relay radio device 500 further includes a modulation conversion device 510 immediately after the antenna 110 in the configuration example of the relay radio device 100 in FIG. 1 described as a comparative example.

[0042] Modulation conversion device 510 converts the modulation method of carrier wave 140 received by antenna 110 from 64QAM to QPSK (Quarter Phase Shift Keying), which has a smaller number of modulation levels. 64QAM can carry 6 bits of information per modulation (per symbol) using 64 symbols, whereas QPSK can only carry 2 bits using 4 values. Therefore, modulation conversion device 510 expands the frequency band of carrier wave 140 by a factor of three, ensuring the same transmission capacity after conversion to QPSK as before (panel P52 in FIG. 5).

[0043] Furthermore, modulation conversion device 510 transmits carrier wave 140, which has been modulated and converted and has an expanded frequency band, to radio device 130 via feeder line 120. There are no restrictions imposed by the Radio Law inside the waveguide or coaxial cable that constitutes feeder line 120, so the modulation method and bandwidth can be freely set.

[0044] Here, when receiving a wireless signal, the C / N required for the received signal to meet a specified BER is calculated as the required C / N. The lower the modulation level, the smaller the required C / N. In the case of QPSK, the required C / N is 11.2 dB, which is lower than the required C / N (= 24.2 dB) for 64QAM.

[0045] In the present disclosure, the modulation conversion device 510 converts the modulation scheme to one with a lower modulation level, thereby lowering the required C / N ratio in the radio device 130. By the amount of the reduction in the required C / N ratio, a degradation margin of 13 dB or more can be provided for the C / N ratio of the carrier 140. This makes it possible to produce an improvement effect in the BER.

[0046] 6 is a diagram illustrating an example of the functional configuration of a relay radio device according to the first embodiment of the present disclosure. An antenna 110 transmits a received carrier wave 140 to a modulation conversion device 510. An RF reception processing unit 370 in the modulation conversion device 510 is similar to the RF reception processing unit 370 in the conventional technology shown in FIG. 4, and therefore a description thereof will be omitted.

[0047] The modulation conversion unit 530 is a unit that performs modulation conversion and frequency bandwidth change on the RF signal amplified by the RF reception processing unit 370. The modulation conversion unit 530 includes a modulation method conversion unit 531 and a bandwidth conversion unit 532. The modulation conversion unit 530 is a unit that performs conversion from 64QAM to QPSK on the carrier wave 140. The bandwidth conversion unit 532 is a unit that expands the frequency bandwidth by three times.

[0048] The modulation method monitoring control unit 540 is a unit that monitors the RF reception processing unit 370 and the modulation conversion unit 530. If a predetermined process cannot be executed in each monitored unit, the unit receives an alarm and performs control.

[0049] Radio device 130 is a part that demodulates the carrier wave that has been modulated and converted by modulation conversion device 510 and input via feeder line 120, and transmits the user signal to the terminal. DEM unit 550 in radio device 130 is similar to DEM unit 380 in the prior art. However, BER monitoring unit 554 monitors BER degradation based on the required C / N (=11.2 dB) of QPSK.

[0050] The deframing unit 560 includes a buffering unit 561 that temporarily buffers transmitted and received signals. The user interface unit 570 includes a connection unit 571 that sends user signals to the terminal.

[0051] The monitoring control unit 580 is a unit that monitors and controls the DEM unit 550 and the deframing unit 560. If the DEM unit 550 is unable to execute a predetermined process, the monitoring control unit 580 receives an alarm and performs control.

[0052] In this way, relay radio device 500 performs modulation conversion and bandwidth expansion in modulation conversion device 510. Carrier wave 140 converted from 64QAM to QPSK is demodulated in radio device 130, and BER degradation is monitored based on the required C / N (=11.2 dB) of QPSK.

[0053] As described above, in the relay radio device 500 of this embodiment, the modulation conversion device 510 installed immediately after reception by the antenna 110 converts the carrier wave 140 into a modulation scheme with a smaller number of modulation levels and expands the bandwidth. This makes it possible to reduce the required C / N and improve the BER while ensuring the transmission capacity of the carrier wave 140.

[0054] It should be noted that either the processing performed by the modulation method conversion unit 531 or the processing performed by the bandwidth conversion unit 532 described in this embodiment may be executed first. This point is also common to the following embodiments.

[0055] Embodiment 2 7 is a schematic diagram illustrating a relay radio apparatus including an LNA and a carrier modulation method according to the second embodiment of the present disclosure. The relay radio apparatus 600 is similar to the relay radio apparatus 500 in FIG. 5, but further includes an LNA 210. The LNA 210 is placed in close proximity to the antenna 110 and modulates a weak carrier. wave Preamplify the signal.

[0056] In this way, by further adding the LNA 210, in addition to the effect of the first embodiment, it is possible to obtain a weak carrier wave This allows the signal to be pre-amplified.

[0057] 8 is a diagram illustrating an example of a functional configuration of a relay radio device according to the second embodiment of the present disclosure. In the relay radio device 600 of FIG. 8, an LNA 210 is added immediately adjacent to the antenna 110 in addition to the example of the functional configuration of FIG.

[0058] In this way, the relay radio device 600 of this embodiment can be provided with a pre-amplification function by the LNA 210.

[0059] Embodiment 3 FIG. 9 is a schematic diagram illustrating an example of the configuration of a higher-level station, a relay radio device, and a lower-level station according to the third embodiment of the present disclosure, and a modulation method of a carrier wave relayed by the relay radio device.

[0060] 3 described as a comparative example, the relay radio apparatus 700 includes the receiving antenna 320, the transmitting antenna 360, and a radio device 710. The radio device 710 includes a modulation conversion unit 530.

[0061] The carrier wave received by the receiving antenna 320 of the relay radio device 700 is transmitted to the radio device 710 via the power feeder 720. The radio device 710 modulates and converts the frequency band of the received carrier wave 140. The modulated and converted carrier wave 140 is then transmitted to the transmitting antenna 360 via the power feeder 730.

[0062] 9, the details of the transmitting device 301, which is the upper station, will be described later. The relay radio devices 500 and 600, which are the lower stations, are the same as those in FIGS. 5 and 7, and therefore their explanations will be omitted.

[0063] Panel P91 in Figure 9 shows the frequency characteristics of the power of the carrier wave 140 at the receiving antenna 320. Here, a carrier wave modulated by 64QAM is received. Panel P92 shows that the radio device 710 converts the 64QAM signal into QPSK, expanding the frequency band three times. From the transmitting antenna 360, the carrier wave 140 modulated by QPSK is transmitted (panel P93).

[0064] 3, the power loss of the carrier 140 in the radio device 130 of the relay radio device 500, 600 includes the feeder loss L due to the feeder line 120 and the propagation loss L0 (panel P94). However, as explained in the first and second embodiments, changing the modulation scheme to QPSK reduces the required C / N ratio, and there is a degradation margin of 13 dB or more in the C / N ratio of the carrier 140. This can produce the effect of improving BER degradation even when a large propagation loss L0 occurs in the wireless section.

[0065] 10 is a diagram showing an example of the functional configuration of a transmitting device that performs wireless communication with a relay wireless device. The transmitting device 301, which is a host station, includes an antenna 310 and a wireless device 740.

[0066] The user interface unit 750 of the wireless device 740 includes a connection unit 751 that receives a user signal transmitted from a terminal. The framing unit 760 includes a buffering unit 761 that temporarily stores a signal transmitted from the user interface unit 750. The functions of the MOD unit 390 and the RF transmission processing unit 400 are the same as those described in FIG. 4, and therefore a description thereof will be omitted.

[0067] The monitoring and control unit 770 is a unit that monitors and controls the framing unit 760, the MOD unit 390, and the RF transmission processing unit 400. It also receives an alarm and performs control when the MOD unit 390 and the RF transmission processing unit 400 are unable to execute predetermined processing. It also controls each unit when there is a problem such as power interference with other wireless stations and it is necessary to urgently stop processing at the local station.

[0068] The transmitting antenna 360 transmits the carrier wave 140 transmitted from the RF transmission processing unit 400 via the feeder line 730 to the relay radio device 700 .

[0069] As described above, the transmitting device 301 of this embodiment receives a user signal, encodes and modulates it, and then transmits the carrier wave 140 from the transmitting antenna.

[0070] 11 is a schematic diagram illustrating an example of a functional configuration of a relay radio device according to a third embodiment of the present disclosure. Similar to the conventional relay radio device 300 of FIG. 4 described as a comparative example, the relay radio device 700 includes a receiving antenna 320, a transmitting antenna 360, and a radio device 710. The radio device 710 includes an RF receiving processing unit 370, a modulation conversion unit 530, an RF transmitting processing unit 400, and a monitoring control unit 780. The functions of the RF receiving processing unit 370 and the RF transmitting processing unit 400 are the same as those in FIG. 4, and therefore their description will be omitted. Furthermore, the function of the modulation conversion unit 530 is the same as that in FIG. 6, and therefore their description will be omitted.

[0071] The monitoring control unit 780 is a unit that monitors and controls the RF reception processing unit 370, modulation conversion unit 530, and RF transmission processing unit 400. It also receives an alarm and performs control when a predetermined process cannot be executed in each unit. It also controls each unit when there is a problem such as power interference with other wireless stations and it is necessary to urgently stop the processing of the local station.

[0072] As described above, the relay radio device 700 of this embodiment converts the received carrier wave 140 into a modulation scheme with a smaller number of modulation levels and expands the frequency bandwidth. This makes it possible to reduce the required C / N and improve the BER while ensuring the transmission capacity of the carrier wave 140 that the relay radio device 700 transmits as a radio signal to a lower-level station.

[0073] Furthermore, the relay radio device 700 of this embodiment does not need to perform demodulation and re-modulation as the relay radio device 300 of the prior art does, so it is possible to provide a radio device 710 that is smaller in size than the prior art.

[0074] The miniaturization of the wireless device 710 brings about a new advantage in that the wireless device 710 can now be installed outdoors, whereas in conventional technology it was necessary to install it indoors. That is, the distance between the wireless device 710 and the receiving antenna 320 and the transmitting antenna 360 can be shortened, and the feeder lines 330 and 340 connecting them can also be shortened. As a result, the effect of suppressing feeder line loss is produced.

[0075] [Variations] In the radio relay device 700, the LNA 210 may be arranged in close proximity to the receiving antenna 320 to provide a pre-amplification function.

[0076] Embodiment 4 FIG. 12 is a schematic diagram illustrating an example of the configuration of a higher-level station, a relay radio device, and a lower-level station according to the fourth embodiment of the present disclosure, and a modulation method of a carrier wave relayed by the relay radio device.

[0077] Similar to the relay radio apparatus 700 of the third embodiment, the relay radio apparatus 800 includes the receiving antenna 320, the transmitting antenna 360, and a radio apparatus 810. The radio apparatus 810 includes a modulation conversion unit 530.

[0078] 12, the radio relay device 810 detects a time change in the propagation environment of the carrier 140 by detecting a time change in the communication quality of the wireless communication. For example, the C / N ratio of the signal received by the receiving antenna 320 is used as the communication quality. Furthermore, the radio device 810 converts the modulation method according to the communication quality. In addition, the frequency band is expanded or narrowed in conjunction with the modulation conversion to ensure the transmission capacity of the carrier 140.

[0079] 12(a) shows the function of the relay radio device 800 when communication quality is degraded. In this case, the radio device 810 of the relay radio device 800 converts the modulation method of the carrier wave 140 from the current 64QAM to 16QAM, which has a lower modulation level. Furthermore, the frequency bandwidth is expanded, and the same transmission capacity as before the conversion is ensured for the carrier wave after the modulation conversion (panel P121).

[0080] Here, in the case of 16QAM, the required C / N is 18.1 dB, which is lower than the required C / N (=24.2 dB) for 64QAM. Therefore, a C / N degradation margin of 6.1 dB can be provided for the carrier 140 received by the relay radio devices 500 and 600, which are downstream stations.

[0081] 12(b) shows the function of the relay radio device 800 when the communication quality is further deteriorated than that of the wireless communication in (a) due to rain attenuation or interference waves. In this case, the radio device 810 converts the modulation method of the carrier wave 140 to QPSK, which has an even lower modulation level than the current 16QAM. Also, the bandwidth is expanded to ensure transmission capacity (panel P124).

[0082] By converting the modulation method to a lower order, it is possible to provide a margin for C / N degradation in the lower-level relay stations 500 and 600. Therefore, even if the propagation loss from the relay station 800 to the lower-level station is double that in case (a), it is possible to achieve the effect of improving BER degradation by the margin (panel P126).

[0083] As described above, the relay radio device 800 of this embodiment performs modulation conversion and frequency band expansion or contraction according to communication quality. Conventionally, a technique for adaptively changing the modulation scheme according to communication quality has been used, but the bandwidth is fixed, so the transmission capacity fluctuates with modulation conversion. In this respect, the present disclosure allows relaying to a lower station while maintaining the transmission capacity at the upper station.

[0084] The relay radio device 800 of this embodiment is particularly suitable for medical, aviation, and military applications. As mentioned above, in conventional technologies, the transmission capacity fluctuates due to adaptive modulation. While this does not pose a problem in best-effort data communications such as IP (Internet Protocol) communications, it does pose a problem in medical, aviation, and military applications where transmission capacity must be guaranteed.

[0085] 13 is a flowchart of processing performed by a relay radio device according to the fourth embodiment of the present disclosure. First, the relay radio device 800 starts processing (step S131). Next, the C / N of the signal received by the receiving antenna is acquired (step S132). Next, the acquired C / N is compared with the C / N acquired last time to determine whether there has been a change (step S133). If it is determined that there has been no change in the C / N, this means that there has been no change in the propagation environment of the carrier 140. Therefore, the modulation multi-level number and the frequency bandwidth are held (step S134). After processing step S134, the process proceeds to step S132 to continue communication.

[0086] On the other hand, if it is determined in step S133 that there has been a change in the C / N, a process is further performed to determine whether or not the C / N has deteriorated (step S135). If the C / N has not deteriorated, this means that the C / N has improved and the propagation environment has improved. Therefore, in this case, the modulation method conversion unit 531 in the modulation conversion unit 530 performs a process to increase the modulation multi-level number (step S136). Furthermore, the bandwidth conversion unit 532 performs a process to narrow the frequency bandwidth (step S137). After processing step S137, the process proceeds to step S132 to continue communication.

[0087] On the other hand, if the C / N ratio is found to be degraded in step S135, this means that the propagation environment has deteriorated. In this case, the modulation method conversion unit 531 performs a process to reduce the modulation multi-level number (step S138). Furthermore, the bandwidth conversion unit 532 performs a process to expand the frequency bandwidth (step S139). After processing step S139, the process proceeds to step S132 to continue communication.

[0088] As explained above using the flowchart, the relay radio device 800 of this embodiment detects the change in C / N over time and continuously controls the modulation level and bandwidth in response to the change. This not only enables adaptive control of the modulation scheme in response to the change in communication quality over time as in the prior art, but also makes it possible to relay to the lower station while maintaining the transmission capacity at the upper station.

[0089] As described above, the present disclosure can provide a relay radio apparatus and a radio relay method that satisfy a required C / N ratio and do not degrade the BER of a received signal even when there is power loss of a carrier wave due to a feeder line.

[0090] [Variations] In the first to third embodiments of the present disclosure, the relay radio devices 500, 600, and 700 are described as including a modulation conversion unit 530 and performing modulation conversion from 64QAM to QPSK. However, the modulation schemes shown here are merely examples and do not limit the technical scope of the present disclosure. The modulation conversion unit 530 included in the relay radio devices 500, 600, and 700 only needs to perform conversion to a modulation scheme with a smaller number of multi-level values, and can select a suitable modulation scheme depending on the usage environment.

[0091] Similarly, in the fourth embodiment of the present disclosure, it has been described that the relay radio device 800 includes the modulation conversion unit 530 and performs modulation conversion in accordance with changes in communication quality over time. However, the modulation method may be different from the one exemplified in the fourth embodiment, and a suitable modulation method may be selected in accordance with the communication quality.

[0092] In the fourth embodiment of the present disclosure, it has been described that the relay radio device 800 detects a time change in the C / N ratio. However, it may also detect a time change in other communication quality. For example, it may be the signal-to-interference-plus-noise power ratio C / (N+I), where I is the interference power. It is also possible to detect a time change by monitoring the BER or the amount of rainfall on the transmission path. In particular, for radio waves with a frequency of 10 GHz or higher, the influence of rain attenuation is significant, so monitoring the amount of rainfall is effective. It is also possible to detect a time change using ACK frames and NACK frames.

[0093] In addition, the communication quality does not have to be measured by the relay radio device 800. For example, the communication quality may be measured by an upper station or a lower station and notified to the relay radio device 800.

[0094] The present disclosure is applicable not only to microwave bands but also to all frequency bands, and is not limited to fixed microwave relay applications, but also to mobile backhaul, wireless access, wireless LAN, simple wireless, weak wireless, drone control, and the like.

[0095] In the present disclosure, the processes performed by the relay radio devices 500, 600, 700, and 800 may be executed by a program using a computer equipped with a CPU and memory and storing a program in the memory. Alternatively, the processes may be executed by a program using an integrated circuit such as an FPGA (Field Programmable Gate Array). The program may be provided by being recorded on a storage medium or via a network.

[0096] [Correspondence to terms in claims] The processing performed by the modulation method converter 531 included in the relay radio devices 500, 600, and 700 described in the first to third embodiments of the present disclosure is called modulation method conversion processing. Furthermore, the processing performed by the bandwidth converter 532 is called bandwidth conversion processing.

[0097] Furthermore, the processing performed by the signal demodulation unit 552 and the error correction unit 553 included in the relay radio devices 500 and 600 described in the first and second embodiments of the present disclosure is referred to as demodulation and decoding processing.

[0098] Furthermore, the process performed by the modulation method conversion unit 531 when the relay radio device 800 detects an improvement in communication quality, as described in the fourth embodiment of the present disclosure, is called a multi-level number raising process. The multi-level number raising process is the process of step S136. [Explanation of symbols]

[0099] 100, 200, 300, 500, 600, 700, 800 Repeater Radio Equipment 110, 310 antenna 120, 330, 350, 720, 730 feed line 130, 340, 710, 740, 810 radio equipment 140 Carrier Wave 210 LNA 301 Transmitting Device 320 receiving antenna 360 transmitting antenna 370 RF receiving processing unit 371 Receiving AMP section 372 AGC Department 373 C / N detector 380, 550 DEM section 381, 551 Waveform equalization section 382, 552 signal demodulation section 383, 553 Error Correction Unit 384, 554 BER Monitoring Department 390 MOD section 391 Waveform shaping section 392 FEC encoder 393 Signal Modulation Section 400 RF transmission processing unit 401 Transmission AMP section 402 Filter section 410, 580, 770, 780 Monitoring and control unit 510 Modulation conversion device 530 Modulation conversion unit 531 Modulation method conversion unit 532 Bandwidth Conversion Unit 540 Modulation method monitoring control section 560 Deframing Department 561, 761 Buffering section 570, 750 User interface section 571, 751 Connection 760 Framing Section

Claims

1. receiving a carrier wave having a first modulation method and a first frequency band as a radio signal from a higher-level radio station; a modulation method conversion process for converting the modulation method of the carrier wave into a second modulation method having a lower multi-level number than the first modulation method; a bandwidth conversion process of expanding the frequency band of the carrier wave to a second frequency band wider than the first frequency band so that the transmission capacity before and after the modulation format conversion process is equal; a demodulation and decoding process for demodulating and error correcting the carrier wave having the second modulation method and the second frequency band obtained by the modulation method conversion process and the bandwidth conversion process; a relay radio device configured to perform the steps of:

2. A relay radio device as described in claim 1, configured to perform a transmission process to transmit the carrier wave processed by the demodulation and decoding process to a lower radio station.

3. A relay radio device as described in Claim 2, wherein the carrier wave transmitted in the transmission process has the second modulation method and the second frequency band.

4. further comprising a low noise amplifier; 3. The radio relay device according to claim 1, wherein the low noise amplifier performs pre-amplification of a carrier wave having the first modulation method and the first frequency band transmitted from the upper radio station.

5. further executing a process of detecting a change over time in communication quality of the wireless communication performed by the wireless communication device itself; If the communication quality has improved, a modulation level raising process for converting the modulation method of the carrier wave transmitted from the higher-level radio station into a third modulation method having a higher modulation level than the first modulation method; a reduction process of reducing the frequency band of the carrier wave to a third frequency band narrower than the first frequency band so that the transmission capacity before and after the multi-level number raising process is equal; a process of transmitting a carrier wave having the third modulation method and the third frequency band obtained by the multi-level number raising process and the reduction process to the lower radio station as a radio signal using the third modulation method and the third frequency band; Run If the communication quality is degraded, the modulation format conversion process; the bandwidth conversion process; the demodulation and decoding process; the transmission process; 4. The relay radio device according to claim 3, wherein the relay radio device executes the following.

6. By the relay radio device, receiving a carrier wave having a first modulation method and a first frequency band as a radio signal from a higher-level radio station; a modulation method conversion process for converting the modulation method of the carrier wave into a second modulation method having a lower multi-level number than the first modulation method; a bandwidth conversion process of expanding the frequency band of the carrier wave to a second frequency band wider than the first frequency band so that the transmission capacity before and after the modulation format conversion process is equal; a demodulation and decoding process for demodulating and error correcting the carrier wave having the second modulation method and the second frequency band obtained by the modulation method conversion process and the bandwidth conversion process; A wireless relay method comprising:

7. The relay radio device:

7. The wireless relay method according to claim 6, further comprising: executing a transmission process of transmitting the carrier wave processed by the demodulation and decoding process to a downstream wireless station.

8. A wireless relay method as described in Claim 7, wherein the carrier wave transmitted in the transmission process has the second modulation method and the second frequency band.

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