Relay device

Abstract

This relay device comprises: a reception unit that receives a transmission signal transmitted by at least one terminal device; a band division unit that generates a plurality of divisional signals by performing band division on the transmission signal received by the reception unit; a compression unit that generates a plurality of compression signals by compressing sections, in the plurality of divisional signals generated by the band division unit, having amplitudes less than a predetermined threshold value; and a transmission unit that transmits the plurality of compression signals generated by the compression unit to a base station device.

Description

relay device

[0001] The present invention relates to a relay device.

[0002] Conventionally, studies have been conducted on a satellite IoT platform that uses low-orbit satellites to collect sensor data from a large number of IoT (Internet of Things) terminals using various LPWA (Low Power Wide Area) methods located anywhere on the Earth, including areas that are difficult to cover with terrestrial communication networks (see Non-Patent Document 1).

[0003] In addition, in order to communicate with multiple communication methods and multiple terminals, a system configuration is being considered in which multiple receiving antennas are installed on a low-orbit satellite, the received waveform data of each receiving antenna sampled by a waveform sampling unit on the satellite is transmitted to the ground, and receiving beam control is performed by offline signal processing on the ground (see Non-Patent Document 2).

[0004] In addition, flexible wireless systems are being considered in which radio waves on which a wide variety of radio signals are superimposed are received at a flexible access point and the received radio wave data is processed collectively on a radio signal processing platform on a network (see non-patent document 3).

[0005] J. Chu, X. Chen, C. Zhong and Z. Zhang, "Robust Design for NOMA-Based Multibeam LEO Satellite Internet of Things", IEEE Internet of Things Journal, vol. 8, no. 3, pp. 1959-1970, 2021.F. Yamashita, D. Goto, Y. Kojima, M. Matsui, K. Itokawa, K. Yoshizawa, K. Sakamoto, Y. Fujino, C. Kato, and M. Nakadai, “920-MHz IoT platform via LEO satellite employing feeder-link MIMO technology,” Proc. 2020 International Conference on Emerging Technologies for Communications (ICETC2020), A1-2, Dec. 2020.D. Lee, T. Yamada, H. Shiba, Y. Yamaguchi, and K. Ueda, “Combined Nyquist and Compressed Sampling Method for Radio Wave Data Compression of a Heterogeneous Network System,” IEICE Transactions on Communications, Vol. E93.B, Issue. 12, pp.3238-3247, Dec. 2010.

[0006] In a satellite IoT platform, when low-earth orbit satellites receive signals from IoT terminals using radio waves in the 920 MHz band, which is widely used for terrestrial communications, a huge amount of data must be processed to convert the waveforms of the wideband received signals into digital data. This increases the cost of transmitting data from low-earth orbit satellites to terrestrial base station equipment using feeder links.

[0007] When receiving signals from low-earth orbit satellites, the Doppler fluctuation can cause the signal to be buried in noise. Furthermore, because the Doppler fluctuation that affects the received signal varies depending on the IoT device that transmits the signal, even if a low-earth orbit satellite uniformly performs despreading on the received waveform, it may not be able to decode the original signal. On the other hand, if despreading is performed on the received waveform for each IoT device, a huge amount of calculation is required to perform the synchronization process, making it difficult for low-earth orbit satellites with limited computing resources to perform such calculations. In other words, it is not easy to use existing waveform data transmission technology using compressed sensing in a satellite IoT platform.

[0008] An object of the present invention is to provide a technique that can realize transmission with a high compression rate and good error resilience even in a communication environment where the signal-to-noise ratio is low due to the influence of Doppler fluctuations.

[0009] One aspect of the present invention is a relay device comprising: a receiving unit that receives a transmission signal transmitted by at least one terminal device; a band dividing unit that generates a plurality of divided signals by performing band dividing on the transmission signal received by the receiving unit; a compression unit that generates a plurality of compressed signals by compressing sections of the plurality of divided signals generated by the band dividing unit where the amplitude is less than a predetermined threshold; and a transmitting unit that transmits the plurality of compressed signals generated by the compression unit to a base station device.

[0010] According to the present invention, even in a communication environment where the signal-to-noise ratio is low due to the influence of Doppler fluctuations, transmission with a high compression rate and good error tolerance can be achieved.

[0011] FIG. 1 is a schematic configuration diagram of a wireless communication system according to an embodiment of the present invention; FIG. 2 is a sequence diagram showing processing of the wireless communication system according to an embodiment of the present invention; FIG. 3 is a diagram showing an example of a signal generated in the wireless communication system according to an embodiment of the present invention; FIG. 4 is a diagram showing an example of a signal generated in the wireless communication system according to an embodiment of the present invention; FIG. 5 is a diagram showing an example of a signal generated in the wireless communication system according to an embodiment of the present invention; FIG. 6 is a diagram showing an example of a signal generated in the wireless communication system according to an embodiment of the present invention; FIG. 7 is a flowchart showing processing of a compression unit of a relay device according to an embodiment of the present invention; and FIG. 8 is a flowchart showing processing of a compressed signal restoration unit of a base station device according to an embodiment of the present invention.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] 1 is a schematic diagram of a wireless communication system 100 according to an embodiment of the present invention. In the wireless communication system 100, a terminal device 10 includes a relay device 20 and a base station device 30. The terminal device 10 is an electronic device, such as a smartphone, that can be carried around by people living on the ground and used to store data and perform communications. The terminal device 10 includes a terminal device control unit 11, a terminal device storage unit 12, and a terminal device transmission unit 13.

[0014] The terminal device control unit 11 includes a CPU (Central Processing Unit) and controls each unit of the terminal device 10. The terminal device storage unit 12 includes semiconductor memories such as RAM (Random Access Memory) and ROM (Read Only Memory). The terminal device storage unit 12 stores data to be transmitted from the terminal device 10 to the base station device 30 and various data necessary for the operation of the terminal device 10, and reads and writes the data based on the control of the terminal device control unit 11. The terminal device transmission unit 13 includes a transmission antenna and, based on the control of the terminal device control unit 11, reads data to be transmitted from the terminal device 10 to the base station device 30 from the terminal device storage unit 12 and transmits the data to the relay device 20 via wireless communication.

[0015] Although only one terminal device 10 is shown in FIG. 1, the number of terminal devices 10 in the wireless communication system 100 is not limited to one, as long as it is at least one or more.

[0016] Relay device 20 is mounted on a low-earth orbit satellite that flies between 200 km and 1000 km above the ground. Relay device 20 receives data transmitted from terminal device 10, performs predetermined processing, and then transmits the data to base station device 30. Relay device 20 includes a relay device control unit 21, a relay device storage unit 22, a relay device receiving unit 23 (also referred to as a receiving unit), a band dividing unit 24, a compression unit 25, and a relay device transmitting unit 26 (also referred to as a transmitting unit).

[0017] The relay device control unit 21 includes a CPU and controls each unit of the relay device 20. The relay device storage unit 22 includes semiconductor memory such as RAM and ROM. The relay device storage unit 22 stores data to be relayed from the terminal device 10 to the base station device 30 and various data necessary for the operation of the relay device 20, and reads and writes the data under the control of the relay device control unit 21.

[0018] The relay device receiving unit 23 is connected to the band dividing unit 24. The relay device receiving unit 23 has multiple receiving antennas, receives data transmitted from at least one terminal device 10, and outputs the data to the band dividing unit 24. The band dividing unit 24 is connected to the relay device receiving unit 23 and the compressor 25. The band dividing unit 24 has an AD (Analog to Digital) converter 241, an FFT (Fast Fourier Transform) processor 242, and a band dividing filter unit 243. In the band dividing unit 24, the data output from the relay device receiving unit 23 is subjected to AD conversion processing by the AD converter 241, FFT processing by the FFT processor 242, and division into multiple narrowband signals by the band dividing filter unit 243, and then output to the compressor 25.

[0019] The compressor 25 is connected to the band dividing unit 24 and the relay device transmitting unit 26. The compressor 25 includes a zero substitution unit 251 and a compressed sensing unit 252. In the compressor 25, the zero substitution unit 251 divides the plurality of narrowband signals divided by the band dividing unit 24 into a plurality of subintervals, and replaces all sampled values ​​in subintervals in which the median amplitude in each subinterval is less than a predetermined threshold value with zero. In the compressor 25, the compressed sensing unit 252 performs compressed sensing on the signal replaced with zeros by the zero substitution unit 251, and then outputs the signal to the relay device transmitting unit 26.

[0020] The relay device transmitter 26 is connected to the compressor 25. The relay device transmitter 26 has a plurality of transmission antennas and transmits the data output from the compressor 25 to the base station device 30 using wireless communication such as MIMO (Multiple-Input Multiple-Output).

[0021] The base station device 30 includes a base station device control unit 31, a base station device storage unit 32, a base station device receiving unit 33, a compressed signal restoration unit 34, a band synthesis unit 35, and a signal processing unit 36. The base station device control unit 31 includes a CPU and controls each unit of the base station device 30.

[0022] The base station device storage unit 32 includes semiconductor memory such as RAM and ROM. The base station device storage unit 32 stores data that the base station device 30 receives from the relay device 20 and various data necessary for the operation of the base station device 30. The base station device storage unit 32 reads and writes the data under the control of the base station device control unit 31.

[0023] The base station device receiving unit 33 is connected to the compressed signal restoring unit 34. The base station device receiving unit 33 receives data transmitted from the relay device 20 via wireless communication and outputs the data to the compressed signal restoring unit 34. The compressed signal restoring unit 34 is connected to the base station device receiving unit 33 and the band combining unit 35. The compressed signal restoring unit 34 restores each divided narrowband signal, which is the signal output from the base station device receiving unit 33, and outputs the restored signal to the band combining unit 35.

[0024] The band synthesis unit 35 is connected to the compressed signal restoration unit 34 and the signal processing unit 36. The band synthesis unit 35 synthesizes restored waveform data of all the divided narrowband signals output from the compressed signal restoration unit 34 and outputs the synthesized data to the signal processing unit 36. The signal processing unit 36 ​​is connected to the band synthesis unit 35 and the base station device storage unit 32. The signal processing unit 36 ​​performs demodulation processing, decoding processing, etc. on the signal output from the band synthesis unit 35 and stores the processed signal in the base station device storage unit 32 under the control of the base station device control unit 31.

[0025] 2 is a sequence diagram showing processing of the wireless communication system 100 according to an embodiment of the present invention. First, the terminal device transmitter 13 of the terminal device 10 reads a signal (data) to be transmitted from the terminal device 10 to the base station device 30 from the terminal device storage unit 12, and transmits the signal to the relay device 20 (step S101 in FIG. 2). Note that a signal W11 shown in FIG. 3 (the horizontal axis represents time, and the vertical axis represents amplitude) is an example of a signal transmitted by the terminal device transmitter 13.

[0026] In step S101 , a case where one terminal device 10 transmits a signal to the relay device 20 is illustrated, but a plurality of terminal devices 10 may transmit signals to the relay device 20 .

[0027] In step S101 of Fig. 2, the signal transmitted by the terminal device transmitter 13 of the terminal device 10 is received by the relay device receiver 23 of the relay device 20 (step S102 of Fig. 2). Note that signal W12 shown in Fig. 3 (the horizontal axis represents time and the vertical axis represents amplitude) is an example of a signal received by the relay device receiver 23. Signal W12 includes signals received by the relay device 20 from many terminal devices 10. Therefore, signal W12 includes many signals in addition to signal W11, and the range in which signal W12 exists is wider than that of signal W11.

[0028] The signal received in step S102 of Fig. 2 is subjected to AD conversion processing by the AD conversion unit 241 of the band splitting unit 24 of the repeater device 20 (step S103 of Fig. 2). Next, the signal that has been AD converted in step S103 of Fig. 2 is subjected to FFT processing by the FFT processing unit 242 of the band splitting unit 24 of the repeater device 20 (step S104 of Fig. 2).

[0029] Next, the signal that underwent FFT processing in step S104 of FIG. 2 is divided into multiple narrowband signals by the band-splitting filter unit 243 of the band splitting unit 24 of the relay device 20 (step S105 of FIG. 2). Note that signal W13 shown in FIG. 3 (horizontal axis: frequency (Hz), vertical axis: power / frequency (dB / Hz)) is an example of one narrowband signal divided by the band-splitting filter unit 243. The band splitting unit 24 generates multiple split signals so that the bandwidths of the multiple split signals are the same and so that the number of multiple split signals is a predetermined number. By performing such processing, it is possible to prevent the desired signal from being buried in noise.

[0030] In this embodiment, a case will be described in which the band-splitting filter unit 243 splits the signal that has been subjected to the FFT process in step S104 into four narrowband signals W14 as shown in Fig. 3 (i.e., the number of divisions is four). By the band-splitting filter unit 243 splitting the signal into four narrowband signals, the signal output by the FFT processing unit 242 is split into four signals: signal W1311 in Fig. 4 (horizontal axis: frequency (Hz), vertical axis: power / frequency (dB / Hz)), signal W1321 in Fig. 5 (horizontal axis: frequency (Hz), vertical axis: power / frequency (dB / Hz)), signal W1331 in Fig. 6 (horizontal axis: frequency (Hz), vertical axis: power / frequency (dB / Hz)), and signal W1341 in Fig. 7 (horizontal axis: frequency (Hz), vertical axis: power / frequency (dB / Hz)).

[0031] Note that, here, a case will be described in which the signal that has undergone FFT processing in step S104 of Fig. 2 is band-divided into four narrowband signals by the band-division filter unit 243, but the number of divisions is not limited to 4. For example, the number of divisions of the signal that has undergone FFT processing in step S104 of Fig. 2 may be increased by one at a time, and the number of divisions that allows the desired signal to be clearly distinguished from noise in the time domain may be used.

[0032] Note that signal W1311 in Figure 4 (horizontal axis is frequency (Hz), vertical axis is power / frequency (dB / Hz)), signal W1321 in Figure 5 (horizontal axis is frequency (Hz), vertical axis is power / frequency (dB / Hz)), signal W1331 in Figure 6 (horizontal axis is frequency (Hz), vertical axis is power / frequency (dB / Hz)), and signal W1341 in Figure 7 (horizontal axis is frequency (Hz), vertical axis is power / frequency (dB / Hz)) correspond to signal W1312 in Figure 4 (horizontal axis is time, vertical axis is amplitude), signal W1322 in Figure 5 (horizontal axis is time, vertical axis is amplitude), signal W1332 in Figure 6 (horizontal axis is time, vertical axis is amplitude), and signal W1342 in Figure 7 (horizontal axis is time, vertical axis is amplitude).

[0033] In step S105 of Fig. 2, the zero replacement unit 251 of the compressor 25 of the repeater device 20 sets a plurality of subintervals for each of the narrowband signals divided into a plurality of narrowband signals (step S106 of Fig. 2). For example, the zero replacement unit 251 sets a plurality of subintervals for each of the signal W1312 of Fig. 4, the signal W1322 of Fig. 5, the signal W1332 of Fig. 6, and the signal W1342 of Fig. 7, dividing the width of the horizontal axis into 50 equal parts. Then, in step S106 of Fig. 2, the zero replacement unit 251 of the compressor 25 of the repeater device 20 performs compression processing on each of the narrowband signals for which a plurality of subintervals has been set, thereby generating a plurality of compressed signals, as shown by signal W15 in Fig. 3.

[0034] Specifically, the zero replacement unit 251 divides each of the multiple split signals generated by the band splitting unit 24 into multiple subintervals, and replaces the amplitude of any subinterval whose evaluation value (e.g., amplitude) is less than a predetermined threshold with zero, thereby generating multiple compressed signals (step S107 in FIG. 2). This makes it possible to generate highly sparse compressed signals without losing information about the interval in which the desired signal exists.

[0035] The zero replacement unit 251 generates multiple compressed signals by replacing with zero the amplitude of the median of the values ​​constituting each of the multiple subintervals, where the amplitude of the median of the values ​​constituting each of the multiple subintervals is less than a predetermined threshold. By performing such processing, it is not necessary to check all of the values ​​constituting each of the multiple subintervals, thereby reducing the processing load on the relay device 20. Note that the predetermined threshold may be determined based on a signal received by the relay device 20, or may be determined based on a signal previously received by the relay device 20 before the relay device 20 starts the relaying process.

[0036] By performing the processing of step S107 in FIG. 2, signal W1312 in FIG. 4 (horizontal axis is time, vertical axis is amplitude), signal W1322 in FIG. 5 (horizontal axis is time, vertical axis is amplitude), signal W1332 in FIG. 6 (horizontal axis is time, vertical axis is amplitude), and signal W1342 in FIG. 7 (horizontal axis is time, vertical axis is amplitude) are converted into signal W1313 in FIG. 4 (horizontal axis is time, vertical axis is amplitude), signal W1323 in FIG. 5 (horizontal axis is time, vertical axis is amplitude), signal W1333 in FIG. 6 (horizontal axis is time, vertical axis is amplitude), and signal W1343 in FIG. 7 (horizontal axis is time, vertical axis is amplitude).

[0037] The compressed sensing unit 252 of the compressor 25 of the relay device 20 performs compressed sensing on the signal that has been subjected to zero substitution in step S107 of Fig. 2 (step S108 of Fig. 2). Then, the relay device transmitter 26 of the relay device 20 transmits the signal that has been subjected to compressed sensing in step S108 of Fig. 2 to the base station device 30 (step S109 of Fig. 2).

[0038] The signal transmitted by the relay device transmitter 26 in step S109 of Fig. 2 is received by the base station device receiver 33 of the base station device 30 (step S110 of Fig. 2). The signal received by the base station device receiver 33 in step S110 of Fig. 2 is restored into each of the plurality of narrowband signals by the compressed signal restorer 34 of the base station device 30 (step S111 of Fig. 2). As a result, the compressed signal restorer 34 of the base station device 30 also generates a plurality of signals W16 (Fig. 3) similar to the plurality of signals W15 (Fig. 3) generated by the zero substitution unit 251 of the compressor 25 of the relay device 20.

[0039] The multiple signals acquired by the compressed signal restoration unit 34 in step S111 of Fig. 2 are combined by the band combining unit 35 of the base station device 30 (step S112 of Fig. 2). As a result, the multiple signals W16 in Fig. 3 are combined into a single signal W17. Note that in signal W17 in Fig. 3, the waveforms with darker shading indicate the signals combined by the band combining unit 35, and the waveforms with lighter shading indicate signal W12 superimposed thereon for reference. The signal combined by the band combining unit 35 in step S112 of Fig. 2 is demodulated and decoded by the signal processing unit 36 ​​of the base station device 30, and is recorded in the base station device storage unit 32.

[0040] 8 is a flowchart showing the process of the compression unit 25 of the relay device 20 according to the embodiment of the present invention. First, the zero substitution unit 251 of the compression unit 25 performs the following operation: Ｄ is set to 1 (step S201 in FIG. 8) and stored in the relay device storage unit 22.

[0041] Next, the zero substitution unit 251 selects n of the D divided signals (D is an integer equal to or greater than 1) generated by the band division unit 24. Ｄ For the divided signal, the compressed sensing unit 252 replaces a subinterval in which the signal strength is less than a predetermined threshold with zeros (step S202 in FIG. 8 ). Next, the compressed sensing unit 252 generates an observation matrix based on the divided signals generated by the band dividing unit 24 (step S203 in FIG. 8 ). Information about the observation matrix generated in step S203 is notified to the base station device 30 via the relay device transmission unit 26. The observation matrix generated in step S203 is used by the compression unit 25 of the relay device 20 and the compressed signal restoration unit 34 of the base station device 30.

[0042] Next, the compressed sensing unit 252 compresses the waveform data of the divided signal generated by zero substitution in the time domain based on the observation matrix generated in step S203 (step S204 in FIG. 8). Specifically, the compressed sensing unit 252 compresses the waveform data of the divided signal n Ｄ By multiplying the matrix representing the above from the left, the waveform data of the signal generated in step S202 is compressed in the time domain.

[0043] Next, the compressed sensing unit 252 calculates the variable n Ｄis the number of divisions N Ｄ It is determined whether the number of divisions N is equal to or greater than the number of divisions N (step S205 in FIG. 8). Ｄ is the number of divided signals generated by the band dividing unit 24, and here, the number of divisions N Ｄ is 4. Variable n Ｄ is the number of divisions N Ｄ If so, the compressed sensing unit 252 ends the process of the flowchart shown in FIG. Ｄ is the number of divisions N Ｄ If not, the compressed sensing unit 252 Ｄ The value of n Ｄ The value is updated to +1 (step S206 in FIG. 8), and stored in the relay device storage unit 22, and then the process of step S202 is performed again.

[0044] 9 is a flowchart showing the process of the compressed signal restoration unit 34 of the base station device 30 according to the embodiment of the present invention. First, the compressed signal restoration unit 34 performs the process of Ｄ The value of is set to 1 (step S301 in FIG. 9) and stored in the base station device storage unit 32.

[0045] Next, the compressed signal restoration unit 34 uses the observation matrix generated in step S203 of FIG. 8 and notified by the relay device 20 to calculate n Ｄ The compressed waveform data of the th divided signal is restored (step S302 in FIG. 9).

[0046] Next, the compressed signal restoration unit 34 calculates the variable n Ｄ is the number of divisions N Ｄ It is determined whether the variable n is equal to or greater than the threshold (step S303 in FIG. 9). Ｄ is the number of divisions N Ｄ If so, the compressed signal restoration unit 34 sends the band synthesis unit 35 Ｄ The restored waveform data of all the divided signals are synthesized (i.e., added) in the time domain (step S304 in FIG. 9). Ｄ is the number of divisions N Ｄ If not, the compressed signal restoration unit 34 sets the variable n Ｄ The value of n ＤThe value is updated to +1 (step S305 in FIG. 8), and stored in the base station device storage unit 32, and then the process of step S302 is performed again.

[0047] In this embodiment, as shown in Figures 4 to 7, it was confirmed that demodulation is possible while achieving a high compression rate of approximately one-third by performing band division and compressed transmission, even in a communication environment with a low signal-to-noise ratio. A DBPSK (Differentially Encoded Binary Phase Shift Keying) modulated signal with a frequency sparsity of 25% without Doppler fluctuation was divided into four bands. In a propagation environment with a compressed transmission SNR (Signal-to-Noise Ratio) of 8 dB in a 100 Hz width before Doppler fluctuation and a Doppler fluctuation of -290 Hz / s, the compression rate required for perfect decoding (BER = 0) was approximately one-third. Other main parameters were a sample rate of 800 sps, a symbol rate of 100 sps, a number of samples of 3904 (equivalent to 4.87 seconds), and a threshold value of 0.5 for the median amplitude over a subinterval (80 samples).

[0048] According to the above-described embodiment, even in a communication environment with a low signal-to-noise ratio due to the influence of Doppler fluctuations, such as communication between a terminal device 10 and a base station device 30 located on the ground and a relay device 20, it is possible to achieve transmission with a high compression rate and good error tolerance.

[0049] Although the present embodiment has been described with reference to a case where amplitude determination is performed in the time domain, amplitude determination may also be performed in the frequency domain. Specifically, the frequency spectra of the respective subintervals may be compared, and if it is determined that there is no difference, multiple frequency spectra may be replaced with zero.

[0050] At least some of the functions of the terminal device 10, relay device 20, and base station device 30 in the above-described embodiments may be implemented by a computer. In this case, a program for implementing this function may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" as used herein includes hardware such as an operating system (OS) and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, read-only memories (ROMs), and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or telephone lines, or devices that store programs for a fixed period of time, such as volatile memory within the computer system serving as the server or client. The program may be designed to implement some of the above-described functions, or may be capable of implementing the above-described functions in combination with programs already stored in the computer system, or may be implemented using a programmable logic device such as an FPGA.

[0051] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0052] The present invention can be applied to relay devices and the like that need to achieve transmission with a high compression rate and good error tolerance even in a communication environment where the signal-to-noise ratio is low due to the influence of Doppler fluctuations.

[0053] DESCRIPTION OF SYMBOLS 10... Terminal device, 11... Terminal device control unit, 12... Terminal device storage unit, 13... Terminal device transmission unit, 20... Relay device, 21... Relay device control unit, 22... Relay device storage unit, 23... Relay device reception unit, 24... Band division unit, 25... Compression unit, 26... Relay device transmission unit, 30... Base station device, 31... Base station device control unit, 32... Base station device storage unit, 33... Base station device reception unit, 34... Compressed signal restoration unit, 35... Band synthesis unit, 36... Signal processing unit, 100... Wireless communication system, 241... AD conversion unit, 242... FFT processing unit, 243... Band division filter unit, 251... Zero substitution unit, 252... Compressed sensing unit

Claims

1. A relay device comprising: a receiving unit that receives a transmission signal transmitted by at least one terminal device; a band dividing unit that generates a plurality of divided signals by dividing the band of the transmission signal received by the receiving unit; a compression unit that generates a plurality of compressed signals by compressing sections of the plurality of divided signals generated by the band dividing unit where the amplitude is less than a predetermined threshold; and a transmission unit that transmits the plurality of compressed signals generated by the compression unit to a base station device.

2. The repeater device according to claim 1, wherein the band division unit generates the plurality of split signals so that the bandwidths of the plurality of split signals are the same and the number of the plurality of split signals is a predetermined number of splits.

3. The repeater device described in claim 1, wherein the compression unit divides the multiple split signals generated by the band splitting unit into multiple sub-intervals, and generates the multiple compressed signals by replacing the amplitude of any sub-interval among the multiple sub-intervals whose evaluation value is less than a predetermined threshold with zero.

4. The relay device according to claim 3, wherein the compression unit generates the plurality of compressed signals by replacing the amplitude of a subsection whose median amplitude is less than the predetermined threshold value with zero for each of the plurality of subsections.

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