Receiving device, transmission / reception system, signal processing method, and signal processing program

Abstract

To provide a receiving device, a transmitting / receiving system, a signal processing method, and a signal processing program capable of achieving both reduction in peak power and reduction in a transmission rate.SOLUTION: A receiving device includes a receiving processing unit (410A) that receives a transmission signal from a transmission device that performs precoding processing and clipping processing on the transmission signal and simultaneously outputs a plurality of transmission signals within the same frequency band, a signal separation unit (420A) that separates the received data set from the transmission signal by performing inverse transformation of the precoding processing on the transmission signal, and a transmission signal estimation unit (440A) that estimates a signal distortion component and a noise component due to clipping processing and interference components between transmission signals on the basis of the received data set and gain information on the transmission path through which the transmission signals are transmitted, and estimates a transmission data set by removing the estimated signal distortion component, the interference component, and the noise component from the received data set.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a receiving apparatus, a transmission / reception system, a signal processing method, and a signal processing program.

Background Art

[0002] In recent years, in a line-of-sight (LOS) communication system that performs communication using a high-frequency band of microwaves or millimeter waves or higher, as the demand for mobile communication infrastructure increases, an increase in transmission capacity is required. As a technology for realizing an increase in transmission capacity, a MIMO (Multi-Input Multi-Output) transmission technology using a plurality of transmission antennas and reception antennas is known. Further, in the MIMO transmission technology, an OAM-MIMO transmission technology that realizes an increase in capacity by multiplexing a large number of signals by utilizing the orbital angular momentum (OAM) of electromagnetic waves has attracted attention.

[0003] For example, Non-Patent Document 1 discloses a technique for realizing OAM-MIMO transmission by using a transmission antenna and a reception antenna in which a plurality of antenna elements are arranged on concentric circles. In Non-Patent Document 1, by performing precoding processing on the signals transmitted through the plurality of antenna elements arranged on each concentric circle, the signals are multiplexed by utilizing the OAM transmission mode of electromagnetic waves, thereby realizing multiplex transmission similar to OAM transmission. On the receiving apparatus side, by applying the inverse conversion of the precoding processing performed on the transmitting apparatus side, signals can be received without interference from the signals propagated by the antenna elements on the concentric circles.

[0004] In MIMO transmission technology including OAM transmission, it is expected to significantly improve the frequency utilization efficiency by combining with multi-value QAM (Quadrature Amplitude Modulation) or polarization multiplexing technology, etc., and realize large-capacity communication. One of the issues for this purpose is to reduce the peak power of each transmission signal output from a plurality of antenna elements.

[0005] In MIMO transmission, in order to efficiently use the transmission path, it is common to perform precoding processing on the transmission signal. For example, in the above-mentioned OAM-MIMO transmission, the precoding processing realized by inverse discrete Fourier transform is performed on the signal before inputting the signal to the antenna. Such precoding processing is essential for transmitting the signal without interference through the antenna elements on the concentric circle. On the other hand, due to the combination of a plurality of signals by the precoding processing, it causes an increase in the ratio of peak power to average power (hereinafter sometimes referred to as "PAPR"). The increase in PAPR causes a decrease in the utilization efficiency of the power amplifier (power amp) associated with the transmitting antenna, so it is required to reduce PAPR.

[0006] As a technique for the purpose of reducing PAPR, for example, Patent Document 1 discloses a method of performing phase rotation processing in the pre-step of precoding processing in MIMO transmission. Also, Patent Document 2 discloses a method of performing phase rotation processing in the pre-step of precoding processing realized by inverse discrete Fourier transform for OAM-MIMO transmission.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Patent Document

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, in order to realize the PAPR reduction effect by applying the phase rotation processing disclosed in Patent Documents 1 and 2, it is necessary to prepare many phase rotation patterns and select the phase rotation pattern with the smallest peak power from these phase rotation patterns. Further, when restoring the transmitted data on the receiving device side, the information on the phase rotation performed on the transmitting device side is required. Therefore, in addition to the data originally transmitted from the transmitting device, it is necessary to transmit the information on the phase rotation performed on the transmitting device side. Thus, in Patent Documents 1 and 2, there are problems such as the complication of system operation and the reduction of the transmission rate due to the transmission of redundant information.

[0010] The present invention has been made to solve the above problems, and an object thereof is to provide a receiving device, a transmission / reception system, a signal processing method, and a signal processing program capable of achieving both reduction of peak power and reduction of transmission rate.

Means for Solving the Problems

[0011] The receiving device of the present invention performs clipping processing to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing precoding processing on two or more integer numbers of transmission data sets, and outputs a plurality of the transmission signals within the same frequency band. A receiving processing unit that receives the transmission signal from a transmission device that outputs the signals simultaneously or substantially simultaneously, and by performing inverse conversion of the precoding processing on the received transmission signal, separates the same number of received data sets as the transmission data sets from the transmission signal. A signal separation unit, and based on the received data sets and gain information regarding the transmission path through which the transmission signal is transmitted, estimates a signal distortion component and a noise component due to the clipping processing and an interference component between the transmission signals, and estimates the estimated signal distortion component, the noise component, and the interference component. A transmission signal estimation unit that estimates the transmission data set by removing the components from the received data set, is provided.

[0012] The transmission-reception system of the present invention performs clipping processing to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing precoding processing on two or more integer numbers of transmission data sets, and outputs a plurality of the transmission signals within the same frequency band. A receiving processing unit that receives the transmission signal from a transmission device that outputs the signals simultaneously or substantially simultaneously, and by performing inverse conversion of the precoding processing on the received transmission signal, separates the same number of received data sets as the transmission data sets from the transmission signal. A signal separation unit, and based on the received data sets and gain information regarding the transmission path through which the transmission signal is transmitted, estimates a signal distortion component and a noise component due to the clipping processing and an interference component between the transmission signals, and estimates the estimated signal distortion component, the noise component, and the interference component. A transmission signal estimation unit that estimates the transmission data set by removing the components from the received data set, and a receiving device including the transmission signal estimation unit, and the transmission device are provided.

[0013] The signal processing method of the present invention performs clipping processing to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing precoding processing on two or more integer numbers of transmission data sets, and receives the transmission signal from a transmission device that outputs a plurality of the transmission signals simultaneously or substantially simultaneously within the same frequency band, and performs inverse conversion of the precoding processing on the received transmission signal to separate the same number of received data sets as the transmission data sets from the transmission signal, and based on the received data sets and gain information regarding the transmission path through which the transmission signal is transmitted, estimates a signal distortion component and a noise component due to the clipping processing and an interference component between the transmission signals, and estimates the transmission data sets by removing the estimated signal distortion component, the noise component, and the interference component from the received data sets.

[0014] The signal processing program of the present invention causes a processor to perform: receiving a transmission signal from a transmission device that performs clipping processing to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing precoding processing on two or more integer numbers of transmission data sets and outputs a plurality of the transmission signals simultaneously or substantially simultaneously within the same frequency band; performing inverse conversion of the precoding processing on the received transmission signal to separate the same number of received data sets as the transmission data sets from the transmission signal; estimating a signal distortion component and a noise component due to the clipping processing and an interference component between the transmission signals based on the received data sets and gain information regarding the transmission path through which the transmission signal is transmitted; and estimating the transmission data sets by removing the estimated signal distortion component, the noise component, and the interference component from the received data sets.

Advantages of the Invention

[0015] According to the present invention, it is possible to provide a receiving device, a transmission / reception system, a signal processing method, and a signal processing program that can achieve both reduction of peak power and reduction of transmission rate. Note that, instead of or together with the above effect, other effects may be achieved by the present invention.

Brief Description of Drawings

[0016]

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BEST MODE FOR CARRYING OUT THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, for elements that can be similarly described, duplicate descriptions may be omitted by attaching the same or corresponding reference numerals.

[0018] Each of the embodiments described below is merely an example of a configuration capable of realizing the present invention. Each of the following embodiments can be appropriately modified or changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Not all combinations of elements included in each of the following embodiments are essential for realizing the present invention, and some of the elements can be appropriately omitted. Therefore, the scope of the present invention is not limited by the configurations described in the following embodiments. As long as there is no contradiction, a configuration combining a plurality of configurations described in the embodiments can also be adopted.

[0019] The description will be made in the following order. 1. Outline of Embodiments of the Present Invention 2. First Embodiment 2.1. Operation Mode of Transmission / Reception System 2.2. Hardware Configuration of Signal Processing Apparatus 2.3. Functional Configuration of Transmission Apparatus 2.4. Functional Configuration of Reception Apparatus 2.5. Flow of Processing in Transmission Apparatus 2.6. Flow of Processing in Reception Apparatus 2.7. Flow of Processing for Estimating Transmission Data Set 2.8. Peak Power Reduction Effect 3. Second Embodiment 4. Other Embodiments

[0020] <1. Outline of Embodiments of the Present Invention> First, the outline of the embodiments of the present invention will be described.

[0021] (1) Technical problem In recent years, in a line-of-sight (LOS) communication system that communicates using a high-frequency band of microwaves or millimeter waves or higher, as the demand for mobile communication infrastructure increases, a larger transmission capacity is required. As a technology to achieve a larger transmission capacity, MIMO (Multi-Input Multi-Output) transmission technology using a plurality of transmission antennas and reception antennas is known. In addition, in MIMO transmission technology, an OAM-MIMO transmission technology that realizes a larger capacity by multiplexing a large number of signals by utilizing the orbital angular momentum (OAM) of electromagnetic waves has attracted attention.

[0022] For example, a technique for realizing OAM-MIMO transmission by using a transmission antenna and a reception antenna in which a plurality of antenna elements are arranged on concentric circles is disclosed. In Non-Patent Document 1, by performing precoding processing on the signals transmitted through the plurality of antenna elements arranged on each concentric circle, the OAM transmission mode of electromagnetic waves is utilized to multiplex the signals, thereby realizing multiplex transmission similar to OAM transmission. On the receiving device side, by applying the inverse conversion of the precoding processing performed on the transmitting device side, signals can be received without interference for the signals propagated by the antenna elements on the concentric circles.

[0023] In MIMO transmission technology including OAM transmission, it is expected to significantly improve the frequency utilization efficiency by combining with multi-value QAM (Quadrature Amplitude Modulation) or polarization multiplexing technology or the like, and to realize a larger communication capacity. One of the problems for this is to reduce the peak power of each transmission signal output from a plurality of antenna elements.

[0024] In MIMO transmission, in order to efficiently utilize the transmission path, it is common to perform precoding processing on the transmission signal. For example, in the above-described OAM-MIMO transmission, after performing precoding processing realized by inverse discrete Fourier transform on the signal, the signal is input to the antenna. Such precoding processing is essential for transmitting the signal without interference through the antenna elements on the concentric circles. On the other hand, due to the precoding processing, a plurality of signals are combined, which causes an increase in the ratio of peak power to average power (Peak to Average Power Ratio: hereinafter sometimes referred to as "PAPR"). The increase in PAPR causes a decrease in the utilization efficiency of the power amplifier (power amp) associated with the transmission antenna, so it is required to reduce PAPR.

[0025] As a technique for reducing PAPR, for example, in MIMO transmission, a method of performing phase rotation processing in the pre-step of precoding processing is disclosed. Also, for example, regarding OAM-MIMO transmission, a method of performing phase rotation processing in the pre-step of precoding processing realized by inverse discrete Fourier transform is disclosed.

[0026] However, in order to realize the PAPR reduction effect by applying the phase rotation processing in the above-described technique, it is necessary to prepare many phase rotation patterns and select the phase rotation pattern with the smallest peak power from these phase rotation patterns. Furthermore, when restoring the transmission data on the receiving device side, the information on the phase rotation performed on the transmitting device side is required. Therefore, in addition to the data originally transmitted from the transmitting device, it is necessary to transmit the information on the phase rotation performed on the transmitting device side. Thus, in the above-described technique, there are problems such as the complication of system operation and the reduction of the transmission rate due to the transmission of redundant information.

[0027] In view of the above circumstances, an object of the present invention is to provide a receiving device, a transmission / reception system, a signal processing method, and a signal processing program capable of achieving both reduction of peak power and reduction of transmission rate.

[0028] (2) Technical features In an embodiment of the present invention, for example, a receiving device performs clipping processing to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing precoding processing on two or more integer numbers of transmission data sets, and outputs a plurality of the transmission signals within the same frequency band. A reception processing unit that receives the transmission signal from a transmission device that outputs the signal simultaneously or substantially simultaneously, and performs inverse conversion of the precoding processing on the received transmission signal, thereby separating the same number of reception data sets as the transmission data sets from the transmission signal. A signal separation unit, and based on the received data set and gain information regarding a transmission path through which the transmission signal is transmitted, estimates a signal distortion component and a noise component due to the clipping processing and an interference component between the transmission signals, and estimates the estimated signal distortion component, the noise component, and the interference component. A transmission signal estimation unit that estimates the transmission data set by removing the component from the received data set.

[0029] Thereby, it becomes possible to provide a receiving device capable of achieving both reduction of peak power and reduction of transmission rate. Note that the above-described technical features are a specific example of an embodiment of the present invention, and naturally, the embodiments of the present invention are not limited to the above-described technical features.

[0030] <2. First Embodiment> <2.1. Operation Mode of Transmission / Reception System> First, with reference to FIG. 1, the operation mode of a transmission / reception system 1000 according to the first embodiment of the present invention will be described. FIG. 1 is a diagram showing the operation mode of the transmission / reception system 1000 according to the first embodiment. The transmission / reception system 1000 includes a transmission device 1, a transmission antenna unit 2, a reception antenna unit 3, and a reception device 4.

[0031] The transmitting device 1 inputs the signal to be transmitted into the transmitting antenna unit 2. The transmitting device 1 performs precoding processing and clipping processing on the signal to be transmitted, and inputs the signal after the precoding processing and the clipping processing into the transmitting antenna unit 2. The precoding processing is a process performed for the purpose of suppressing interference between signals when transmitting signals via antenna elements arranged in a concentric circle shape. Also, the clipping processing is a process performed for the purpose of suppressing the power for amplifying the signal to be transmitted by deleting the amplitude equal to or greater than a predetermined threshold value. Details of the precoding processing and the clipping processing performed by the transmitting device 1 will be described later.

[0032] The transmitting antenna unit 2 is configured such that antenna elements 21, 22, 23, 24, 25, 26, 27, and 28 are arranged in a concentric circle shape. The transmitting device 1 inputs signals to each of the antenna elements 21, 22, 23, 24, 25, 26, 27, and 28. The antenna elements 21, 22, 23, 24, 25, 26, 27, and 28 each radiate the signal input from the transmitting device 1 into space. The antenna elements 21, 22, 23, 24, 25, 26, 27, and 28 can each radiate the signal input from the transmitting device 1 simultaneously or substantially simultaneously. Note that the number of antenna elements included in the transmitting antenna unit 2 may be other than the number shown in FIG. 1.

[0033] The receiving antenna unit 3 is configured such that antenna elements 31, 32, 33, 34, 35, 36, 37, and 38 are arranged in a concentric circle shape. The signals received by the antenna elements 31, 32, 33, 34, 35, 36, 37, and 38 are input into the receiving device 4. Note that the number of antenna elements included in the receiving antenna unit 3 may be other than the number shown in FIG. 1.

[0034] The receiving device 4 performs a process corresponding to the inverse conversion of the precoding process performed by the transmitting device 1 on the signals received by the antenna elements 31, 32, 33, 34, 35, 36, 37, and 38. Further, the receiving device 4 estimates the signal transmitted from the transmitting device 1 based on the signal after the inverse conversion and the gain information of the transmission path through which the signal is transmitted, and outputs the estimated signal.

[0035] As shown in FIG. 1, the transmission / reception system 1000 corresponds to an OAM-MIMO transmission system, which is an example of a MIMO transmission system having eight antenna elements evenly arranged on a circle on both the transmission side and the reception side.

[0036] In MIMO transmission, in order to efficiently utilize the transmission path, it is common to perform precoding processing on the signal to be transmitted. On the other hand, due to the precoding processing, by synthesizing a plurality of signals, the ratio (PAPR) of the peak power to the average power increases. The increase in PAPR causes a decrease in the utilization efficiency of the power amplifier associated with the transmitting antenna, so it is required to reduce PAPR.

[0037] Conventionally, for the purpose of reducing PAPR, a method of performing phase rotation on the transmission side has been tried. In such a method, in addition to the signal transmitted from the transmitting device, it is necessary to transmit the information of the phase rotation performed on the transmitting device side, so there are problems such as the complication of system operation and the decrease in the transmission rate due to the transmission of redundant information.

[0038] In response to such problems, in this embodiment, a transmission / reception system capable of achieving both reduction of peak power and reduction of transmission rate will be described.

[0039] <2.2. Hardware Configuration of Signal Processing Device> Subsequently, the hardware configuration of signal processing devices such as the transmitting device 1 and the receiving device 4 according to this embodiment will be described. FIG. 2 is a block diagram showing the hardware configuration of the signal processing device.

[0040] The signal processing device has a CPU (Central Processing Unit) 51, a ROM (Read Only Memory) 52, a RAM (Random Access Memory) 53, a storage medium 54, and an interface (I / F) 55, which are interconnected via a bus 56. In addition to what is shown in FIG. 2, the signal processing device may include input devices such as a keyboard and a mouse, or display devices such as a display.

[0041] The CPU 51 is an arithmetic means that controls the operation of the entire signal processing device. The RAM 53 is a volatile storage medium that enables high-speed reading and writing of information and is used as a work area when the CPU 51 processes information. The ROM 52 is a non-volatile read-only storage medium in which programs such as firmware are stored. The storage medium 54 is a non-volatile storage medium such as an HDD (Hard Disk Drive) that enables reading and writing of information, and stores an OS, various control programs, application programs, etc. The I / F 55 connects and controls the bus 56 and various hardware.

[0042] In such a hardware configuration, according to the program stored in the ROM 52 of the transmission device 1 or the program loaded from the storage medium 54 of the transmission device 1 to the RAM 53 of the transmission device 1, the CPU 51 of the transmission device 1 performs calculations, whereby the software control unit of the transmission device 1 is configured. Then, a functional block that realizes the functions of the transmission device 1 (see FIG. 3) is configured by combining the software control unit configured as described above with the hardware.

[0043] Also, in such a hardware configuration, the CPU 51 of the receiving device 4 performs calculations according to the program stored in the ROM 52 of the receiving device 4 or the program loaded from the storage medium 54 of the receiving device 4 into the RAM 53 of the receiving device 4, thereby configuring the software control unit of the receiving device 4. Then, a functional block that realizes the functions of the receiving device 4 (see FIGS. 4 to 6) is configured by combining the software control unit configured as described above with the hardware.

[0044] <2.3. Functional Configuration of Transmission Device> Subsequently, with reference to FIGS. 3 and 4, the functional configuration of the transmission device 1 will be described. FIG. 3 is a functional block diagram showing the functional configuration of the transmission device 1 according to the first embodiment. FIG. 4 is a functional block diagram showing the functional configuration of the clipping processing unit 150 of the transmission device 1.

[0045] The transmission device 1 includes a serial-parallel conversion processing unit 110, bit signal conversion processing units 120-1, 120-2, ···, 120-N, filter processing units 130-1, 130-2, ···, 130-N, a pre-coding processing unit 140, clipping processing units 150-1, 150-2, ···, 150-N, and transmission processing units 160-1, 160-2, ···, 160-N. Note that the numerical value N of the bit signal conversion processing unit 120-N, the filter processing unit 130-N, the clipping processing unit 150-N, and the transmission processing unit 160-N is a positive integer. FIG. 3 shows the functional configuration of the transmission device 1 when N is a positive integer greater than or equal to 3.

[0046] The serial-parallel conversion processing unit 110 performs a conversion to rearrange a single bit sequence input to the serial-parallel conversion processing unit 110 into the same number of sequences as a preset numerical value N, and outputs N bit sequences. The serial-parallel conversion processing unit 110 inputs the bit sequences one by one to each of the bit signal conversion processing units 120-1, 120-2, ···, 120-N. In the following description, it is assumed that the numerical value N is the same as the number of antenna elements of the transmission antenna unit 2 and the reception antenna unit 3 (8), but the number of rearranged bit sequences does not have to be the same as the number of antenna elements of the transmission antenna unit 2. Each of the N bit sequences output by the serial-parallel conversion processing unit 110 is an example of the transmission data set of the present embodiment.

[0047] The bit signal conversion processing units 120-1, 120-2, ···, 120-N convert the input bit sequences into complex signals. In the following description, when it is not necessary to distinguish the bit signal conversion processing units 120-1, 120-2, ···, 120-N, they are described as "bit signal conversion processing unit 120". The bit signal conversion processing unit 120 is realized by an error correction code encoding circuit for encoding the bit sequence and, when using the Quadratic Amplitude Modulation (QAM) method, a circuit for converting the bit sequence into QAM signal points.

[0048] The bit signal conversion processing unit 120-1 inputs the complex signal to the filter processing unit 130-1. The bit signal conversion processing unit 120-2 inputs the complex signal to the filter processing unit 130-2. The bit signal conversion processing unit 120-N inputs the complex signal to the filter processing unit 130-N.

[0049] The filter processing units 130-1, 130-2, ···, 130-N perform waveform shaping filter processing to convert a complex signal into a transmission signal having a predetermined frequency band, and input it to the precoding processing unit 140. In the following description, when it is not necessary to distinguish the filter processing units 130-1, 130-2, ···, 130-N, they are described as "filter processing unit 130". The filter processing unit 130 performs waveform shaping filter processing by, for example, a Root Raised Cosine (RRC) filter.

[0050] The precoding processing unit 140 performs precoding processing to synthesize N signal sequences, the same number as the number of data sets output by the serial-parallel conversion processing unit 110, and outputs N signals that are the same as the antenna elements of the transmission antenna unit 2. The precoding processing unit 140 inputs each element included in the signal after the precoding processing to each of the clipping processing units 150-1, 150-2, ···, 150-N one by one.

[0051] The clipping processing units 150-1, 150-2, ···, 150-N each have an absolute value phase separation processing unit 151, a comparison processing unit 152, and an absolute value phase synthesis processing unit 153 (see FIG. 4). In the following description, when it is not necessary to distinguish the clipping processing units 150-1, 150-2, ···, 150-N, they are described as "clipping processing unit 150". The clipping processing unit 150 performs clipping processing to delete the excess amplitude when the amplitude value of the signal input to the clipping processing unit 150 is larger than a preset value, and outputs a transmission signal.

[0052] The absolute value phase separation processing unit 151 separates the transmission signal input to the clipping processing unit 150 into an absolute value component and a phase component. Then, the absolute value phase separation processing unit 151 inputs the absolute value S corresponding to the absolute value component separated from the transmission signal to the comparison processing unit 152, and inputs the phase angle θ corresponding to the phase component separated from the transmission signal to the absolute value phase synthesis processing unit 153.

[0053] The comparison processing unit 152 compares the absolute value S input from the absolute value phase separation processing unit 151 with a preset numerical value A (A is a positive real number), and inputs the smaller one of the absolute value S and the numerical value A as the output value S' to the absolute value phase synthesis processing unit 153.

[0054] Based on the declination θ input from the absolute value phase separation processing unit 151 and the output value S' of the comparison processing unit 152, the absolute value phase synthesis processing unit 153 performs a conversion opposite to that of the absolute value phase separation processing unit 151, and outputs a complex numerical value as the transmission signal, where the absolute value is S' and the declination is θ.

[0055] The clipping processing unit 150-1 inputs the transmission signal to the transmission processing unit 160-1. The clipping processing unit 150-2 inputs the transmission signal to the transmission processing unit 160-2. The clipping processing unit 150-N inputs the transmission signal to the transmission processing unit 160-N.

[0056] The transmission processing units 160-1, 160-2, ···, 160-N include a circuit that converts a baseband signal into a high-frequency radio signal, a power amplifier (PA) that amplifies signal power, etc., and input the transmission signal to the transmission antenna unit 2 as an electromagnetic wave. The transmission processing unit 160-1 inputs the transmission signal to the antenna element 21 (see FIG. 1). The transmission processing unit 160-2 inputs the transmission signal to the antenna element 22 (see FIG. 1). The transmission processing unit 160-N inputs the transmission signal to the antenna element 28 (see FIG. 1), for example. In the following description, when there is no need to distinguish the transmission processing units 160-1, 160-2, ···, 160-N, they are described as "transmission processing unit 160". The antenna elements 21, 22, ···, 28 radiate electromagnetic waves into space.

[0057] <2.4. Functional Configuration of the Receiver> Next, with reference to FIGS. 5 to 7, the functional configuration of the receiving apparatus 4 will be described. FIG. 5 is a functional block diagram showing the functional configuration of the receiving apparatus 4 according to the first embodiment. FIG. 6 is a functional block diagram showing the functional configuration of the transmission signal estimation unit 440 included in the receiving apparatus 4. FIG. 7 is a functional block diagram showing the detailed functional configuration of the transmission signal estimation unit 440.

[0058] The receiving apparatus 4 includes receiving processing units 410-1, 410-2, ···, 410-N, a signal separation processing unit 420, filter processing units 430-1, 430-2, ···, 430-N, a transmission signal estimation unit 440, bit signal conversion processing units 450-1, 450-2, ···, 450-N, and a serial-parallel conversion processing unit 460. Note that the numerical value N of the receiving processing unit 410-N, the filter processing unit 430-N, and the bit signal conversion processing unit 450-N is a positive integer. FIG. 4 shows the functional configuration of the receiving apparatus 4 when N is a positive integer of N≥3.

[0059] Electromagnetic waves received by the antenna element 31 are input to the receiving processing unit 410-1. Electromagnetic waves received by the antenna element 32 are input to the receiving processing unit 410-2. Electromagnetic waves received by the antenna element 38 are input to the receiving processing unit 410-N. The receiving processing units 410-1, 410-2, ···, 410-N convert the received electromagnetic waves into received signals. In the following description, when it is not necessary to distinguish the receiving processing units 410-1, 410-2, ···, 410-N, they will be described as "receiving processing unit 410". Also, in the receiving apparatus 4, although the numerical value N is assumed to be the same as the number of antenna elements (8) of the transmission antenna unit 2 and the receiving antenna unit 3, the numerical value N does not have to be the same as the number of antenna elements of the receiving antenna unit 3.

[0060] The signal separation processing unit 420 performs a process corresponding to the inverse conversion of the precoding process performed by the precoding processing unit 140 on the signal received from the reception antenna unit 3, and outputs reception signals equal in number (N) to the antenna elements of the reception antenna unit 3. The signal separation processing unit 420 inputs the reception signals one by one to each of the filter processing units 430-1, 430-2, ···, 430-N. Each of the reception signals output by the signal separation processing unit 420 is an example of the reception data set of the present embodiment. Also, the signal separation processing unit 420 is an example of the signal separation unit of the present embodiment.

[0061] The filter processing units 430-1, 430-2, ···, 430-N are matching filters such as root-raised cosine filters, and perform filter processing to maximize the signal-to-noise power ratio of the reception signals received from the signal separation processing unit 420. In the following description, when it is not necessary to distinguish the filter processing units 430-1, 430-2, ···, 430-N, they are described as "filter processing unit 430". The filter processing unit 430 inputs the reception signals subjected to the filter processing to the transmission signal estimation unit 440.

[0062] The transmission signal estimation unit 440 removes the distortion of the signal caused by the clipping process in the transmission device 1 and the interference of the signal generated when transmitting the signal from the transmission device 1 to the reception device 4 from the reception signals received from the filter processing unit 430. The transmission signal estimation unit 440 inputs, one by one, the data set corresponding to the reception signals after removing the signal distortion and the interference components to each of the bit signal conversion processing units 450-1, 450-2, ···, 450-N.

[0063] As shown in FIG. 5, the transmission signal estimation unit 440 includes estimation signal output units 441-1, 441-2, ···, 441-N, estimation signal output units 443-1, 443-2, ···, 443-N, and estimation signal output units 446-1, 446-2, ···, 446-N. Note that the numerical value N of the estimation signal output units 441-N, 443-N, and 446-N is a positive integer. FIG. 6 shows the configuration of the transmission signal estimation unit 440 when N is a positive integer greater than or equal to 3. Further, the transmission signal estimation unit 440 includes correction signal output units 442 and 444. In the following description, when there is no need to distinguish the estimation signal output units 441-1, 441-2, ···, 441-N, they are described as "estimation signal output unit 441". In the following description, when there is no need to distinguish the estimation signal output units 443-1, 443-2, ···, 443-N, they are described as "estimation signal output unit 443". In the following description, when there is no need to distinguish the estimation signal output units 446-1, 446-2, ···, 446-N, they are described as "estimation signal output unit 446".

[0064] The estimation signal output unit 441 includes an estimation information calculation unit 4411 and an estimation information conversion unit 4412, and outputs an estimated value of the transmission signal. The estimation signal output unit 443 includes an estimation information calculation unit 4431 and an estimation information conversion unit 4432, and outputs an estimated value of the transmission signal. The estimation signal output unit 446 includes an estimation information calculation unit 4461 and an estimation information conversion unit 4462, and outputs an estimated value of the transmission signal. The correction signal output unit 442 includes a difference processing unit 4421, an interference signal calculation unit 4422, and a correction signal calculation unit 4423, and outputs a correction signal for correcting the received signal. The correction signal output unit 444 includes a difference processing unit 4441, an interference signal calculation unit 4442, and a correction signal calculation unit 4443, and outputs a correction signal for correcting the received signal. Details of the elements included in the transmission signal estimation unit 440 will be described later.

[0065] The bit signal conversion processing units 450-1, 450-2, ···, 450-N convert the received signal into N received bit sequences by performing the inverse conversion of the processing performed by the bit signal conversion processing unit 120. In the following description, when it is not necessary to distinguish the bit signal conversion processing units 450-1, 450-2, ···, 450-N, they are described as "bit signal conversion processing unit 450". The bit signal conversion processing unit 450 is realized by a decoding circuit for error correction codes for decoding the received signal and, when using the QAM method, a circuit for converting the received signal from QAM signal points into a bit sequence. The bit sequences output by the bit signal conversion processing units 450-1, 450-2, ···, 450-N are input to the serial-parallel conversion processing unit 460.

[0066] The serial-parallel conversion processing unit 460 rearranges the N bit sequences into a single bit sequence and outputs it. That is, the serial-parallel conversion processing unit 460 performs the inverse conversion of the serial-parallel conversion processing unit 110 on the input data set.

[0067] In the transmission-reception system 1000 of the present embodiment, signal transmission and reception are performed by the elements as described above.

[0068] <2.5. Flow of Processing in the Transmission Device> Subsequently, the flow of processing in the transmission device 1 will be described with reference to FIG. 8. FIG. 8 is a flowchart showing the flow of processing in the transmission device 1. In the present embodiment, when indicating a character with a hat, "(hat)" is described after the character. Also, in the present embodiment, when indicating a character with a tilde, "(tilde)" is described after the character.

[0069] The information consisting of a single bit sequence input to the transmission device 1 is input to the serial-to-parallel conversion processing unit 110. In step S11, the serial-to-parallel conversion processing unit 110 rearranges the single bit sequence into N bit sequences. The serial-to-parallel conversion processing unit 110 inputs each of the bit sequences included in the N bit sequences to each of the bit signal conversion processing units 120-1, 120-2, ···, 120-N one by one.

[0070] In step S12, the bit signal conversion processing unit 120 converts the bit sequence received from the serial-to-parallel conversion processing unit 110 into a complex signal by performing error correction coding processing and conversion processing to QAM signal points. The bit signal conversion processing unit 120 inputs the complex signal to the filter processing unit 130.

[0071] In step S13, the filter processing unit 130 converts the complex signal received from the bit signal conversion processing unit 120 into a

Number

[0072] In step S14, the precoding processing unit 140 performs the operation shown in (Equation 1) on the data set x which is a vector,

Number

Number

[0073] In addition, in (Equation 1),

Number

Number

[0074] The precoding processing unit 140 is a data set that is a vector

Number

[0075] In step S15, the clipping processing unit 150 performs a clipping process on the elements of the data set s that is a vector received from the precoding processing unit 140. In the following description, the elements of the data set s that is a vector received from the precoding processing unit 140 may be simply described as "element s".

[0076] The clipping process performed by the clipping processing unit 150 on the element s received from the precoding processing unit 140 will be described. The element s received from the precoding processing unit 140 is first input to the absolute value phase separation processing unit 151 in the clipping processing unit 150.

[0077] The absolute value phase separation processing unit 151 separates the element s into an absolute value component and a phase component. If the absolute value of the element s represented as a complex number is S and the argument is θ, then the element

Number

[0078] Subsequently, the comparison processing unit 152 compares the absolute value S received from the absolute value phase separation processing unit 151 with a numerical value A (A is a positive real value) corresponding to a predetermined threshold. Then, the comparison processing unit 152 outputs, as an output value S´, the smaller one of the absolute value S and the numerical value A to the absolute value phase synthesis processing unit 153. Note that when the absolute value S = the numerical value A, the comparison processing unit 152 outputs the numerical value A = the output value S´ to the absolute value phase synthesis processing unit 153.

[0079] That is, with respect to the absolute value S received from the absolute value phase separation processing unit 151, the comparison processing unit 152

Number

[0080] Based on the argument θ received from the absolute value phase separation processing unit 151 and the output value S´ received from the comparison processing unit 152, the absolute value phase synthesis processing unit 153 performs an inverse conversion to that of the absolute value phase separation processing unit 151, and outputs a complex numerical value whose absolute value is S´ and whose argument is θ

Number

[0081] That is, when the absolute value S of the element s received from the pre-coding processing unit 140 is greater than or equal to a predetermined threshold (numerical value A), the clipping processing unit 150 replaces only the absolute value with the numerical value A and outputs it without changing the phase. On the other hand, when the absolute value of the element s received from the pre-coding processing unit 140 is smaller than the predetermined threshold (numerical value A), the clipping processing unit 150 outputs the absolute value S of the element s without replacing it with the numerical value A. By doing so, in the transmission device 1, it is possible to output a transmission signal after deleting an amplitude greater than or equal to a predetermined threshold (for example, numerical value A). The clipping processing unit 150 inputs the clipped elements (S0, S1, ···, S N-1 ) one by one to the transmission processing units 160-1, 160-2, ···, 160-N.

[0082] In step S16, the transmission processing unit 160 performs a conversion process from a baseband signal to a radio signal and an amplification process by a power amplifier on the element s received from the clipping processing unit 150, and inputs it as a transmission signal to the transmission antenna unit 2. The antenna elements 21, 22, ···, 28 of the transmission antenna unit 2 radiate the transmission signal received from the transmission processing unit 160 into space as electromagnetic waves.

[0083] <2.6. Flow of Processing in the Receiver> Subsequently, the flow of processing in the receiver 4 will be described with reference to FIG. 9. FIG. 9 is a flowchart showing the flow of processing in the receiver 4.

[0084] The antenna elements 31, 32, ···, 38 receive the signal radiated from the transmission antenna unit 2, that is, the transmission signal of the transmission device 1, and input it to the receiver 4. The signal received by the antenna element 31 is input to the reception processing unit 410-1, for example. Also, the signal received by the antenna element 32 is input to the reception processing unit 410-2, for example. Also, the signal received by the antenna element 38 is input to the reception processing unit 410-N, for example.

[0085] The reception processing unit 410 converts the signal received from the reception antenna unit 3 from a radio signal to a baseband signal and inputs it to the signal separation processing unit 420. Here, the baseband signal input to the signal separation processing unit 420 by the reception processing unit 410 is the data set

Number

[0086] In step S21, the signal separation processing unit 420 separates the signal synthesized in the transmission device 1 from the data set s which is a vector by performing a conversion reverse to the pre-coding process. Specifically, the signal separation processing unit 420 calculates the data set s which is a vector as in (Equation 3)

Number

Mathematics

Mathematics

Mathematics

Mathematics

Mathematics

Mathematics

[0087] In step S22, the filter processing unit 430 performs filter processing to maximize the signal-to-noise power ratio for the element x' received from the signal separation processing unit 420. The filter processing unit 430 inputs the data set y corresponding to the element x' after the filter processing to the transmission signal estimation unit 440.

[0088] <2.7. Flow of the process of estimating the transmission data set> In step S23, the transmission signal estimation unit 440 estimates the transmission data set. Here, with reference to FIGS. 10 and 11, the flow of the process of estimating the transmission data set will be described. FIG. 10 is a flowchart showing the flow of the process of calculating the estimated value of the transmission data set. FIG. 11 is a flowchart showing the flow of the process of calculating the correction value of the received data set. Note that the flowcharts shown in FIGS. 10 and 11 correspond to the steps performed in step S23 of FIG. 9.

[0089] In step S31, the estimated signal output unit 441 receives the data set y received from the filter processing unit 430, the correction signal y (err) , and the transmission path gain h. Note that the transmission path gain h corresponds to gain information regarding the transmission path between the transmission device 1 and the reception device 4, and may be information stored in the reception device 4 in advance. Also, in the estimated signal output unit 441, the correction signal y (err) is assumed to be 0. The estimated signal output unit 441 is an example of the first estimated signal output unit of the present embodiment.

[0090] In step S32, the estimation information calculation unit 4411 calculates an estimated data set x (tilde) based on the data set y received from the filter processing unit 430, the correction signal y (err) , and the transmission path gain h (Equation 5). The estimation information calculation unit 4411 is an example of the first estimation information calculation unit of the present embodiment. Also, the estimated data set x (tilde) calculated by the estimation information calculation unit 4411 is an example of the first estimation information of the present embodiment. [Equation] In (Equation 5), [Equation] represents the complex conjugate of the transmission path gain h. Also, in (Equation 5), [Equation] represents the absolute value of the transmission line gain h. In addition, in (Equation 5), ρ is a parameter that can be arbitrarily set within the range of positive real numbers, and is a value determined based on a value considered to be optimal through learning using the backpropagation method. ρ, which is a parameter that can be arbitrarily set within the range of positive real numbers, is an example of the first parameter of this embodiment.

[0091] In step S33, the estimated information conversion unit 4412 converts the estimated data set x (tilde) into a parameterized nonlinear function ψ τ and a parameterized nonlinear function p θ Composite function with

number

number

[0092] Parameterized nonlinear function ψ τ An example of this is shown in (Equation 6).

number

[0093] In (Equation 6), Q is a set of signal points determined depending on the modulation scheme set in the bit signal conversion processing unit 120, and can be determined as Q={-3,-1,+1,+3} when the modulation scheme of the bit signal conversion processing unit 120 is 16QAM, for example. ReLU(x) is a function that is often used in deep neural networks, which compares x with 0 and outputs the larger one.

[0094] τ in (Equation 6) q(q is an element of the signal point set Q) is a parameter that can be arbitrarily set as a non-zero real value, and is a value determined based on a value considered to be optimal through learning using the error backpropagation method. τ, which is a parameter that can be arbitrarily set as a non-zero real value q is an example of the second parameter of this embodiment.

[0095] Subsequently, a specific example of the non-linear function p with parameters θ is shown in (Equation 7).

Equation

Equation

[0096] In step S34, the estimated signal output unit 441 outputs the data set x (hat) as an estimated value of the transmission signal. The estimated data set x (hat) output by the estimated signal output unit 441 is an example of the first estimated value of this embodiment. Also, the estimated information conversion unit 4412 is an example of the first estimated information conversion unit of this embodiment.

[0097] In this way, the estimated signal output unit 441 corrects the estimated data set x (tilde) calculated by (Equation 5) using the non-linear function ψ τ with learning parameters and the non-linear function p θ and then outputs the data set x (hat).

[0098] The data sets x(hat) output from the estimated signal output units 441-1, 441-2, ···, 441-N, when represented as vectors, are the data sets

Number

[0099] Subsequently, the flow of processing in the correction signal output unit 442 will be described with reference to FIG. 11. In step S41, the correction signal output unit 442 receives the data set x(hat) which is a vector, and N 2 transmission path gains h i,j (where i and j are each integers between 0 and N-1). Note that among the N 2 transmission path gains h i,j the N pieces of information where i = j

Number

[0100] In step S42, the difference processing unit 4421 performs the operation of (Equation 8),

Number

Number

[0101] Note that in (Equation 8), the matrix

Number

Number

Number

[0102] Also, in step S42, the interference signal calculation unit 4422 uses the difference signal x (c) calculated by (Equation 8), and N 2 transmission path gains h i,j to form an N×N matrix with (i,j) components

Number

Number

Number

[0103] Subsequently, in step S43, the correction signal calculation unit 4423 [Number] performs the operation of [Number] and calculates the correction signal (err) The correction signal y, which is the vector calculated by the correction signal calculation unit 4423,

[0104] In (Equation 10), [Number] is a parameter that can be arbitrarily set and is set to an optimal value through learning using the error backpropagation method. The correction signal calculation unit 4423 outputs the correction signal y, which is the vector obtained by (Equation 10). (err)

[0105] As described above, the correction signal y used by the estimated signal output unit 441 (err) is [Number] That is, in other words, the estimated signal output unit 441 can calculate the estimated data set x (tilde) based on the data set y received from the filter processing unit 430 and the transmission path gain h, and obtain the estimated data set x (hat) by converting the estimated data set x (tilde).

[0106] The estimated signal output unit 443 uses the correction signal y output by the correction signal output unit 442 (err)10 is performed based on a data set y, which is an output signal of the filter processing unit 430, and a transmission path gain h. Then, the estimated signal output unit 443 outputs the estimated data set x (hat) to the correction signal output unit 444.

[0107] In other words, the estimated signal output unit 443 multiplies the output signal y of the filter processing unit 430 by the correction signal y output by the correction signal output unit 442 using (Equation 5). (err) and outputs an estimated data set x (hat) based on a signal (first sum signal) obtained by adding the above and the transmission path gain h. The estimated signal output unit 443 is an example of a second estimated signal output unit of this embodiment, and the estimated data set x (hat) output from the estimated signal output unit 443 is an example of a second estimated value of this embodiment. Moreover, the estimated information calculation unit 4431 is an example of a second estimated information calculation unit of this embodiment. Furthermore, the estimated data set x (tilde) calculated by the estimated information calculation unit 4431 is an example of the second estimated information of this embodiment. Furthermore, the estimated information conversion unit 4432 is an example of a second estimated information conversion unit of this embodiment.

[0108] The correction signal output unit 444 receives the estimated data set x (hat) from the estimated signal output unit 443 and N2 transmission line gains h i,j (i, j are integers between 0 and N-1) based on the correction signal y (err) The correction signal output unit 444 is an example of a second correction signal output unit of the present embodiment, and outputs the correction signal y (err) is an example of the second correction signal in this embodiment.

[0109] The difference processing unit 4441 included in the correction signal output unit 444 is an example of the second difference processing unit of this embodiment, and the difference data set x (c) is an example of the second difference data set of this embodiment. Furthermore, the interference signal calculation unit 4442 is an example of the second interference signal calculation unit of this embodiment, and the interference signal calculation unit 4442 calculates the interference signal y(c) is an example of the second interference signal in this embodiment. Further, the correction signal calculation unit 4443 is an example of the second correction signal calculation unit in this embodiment.

[0110] Note that in the transmission signal estimation unit 440, the k-th estimation signal output unit (for example, the estimation signal output unit 446), which is a positive integer of 2 or more, receives the correction signal y output from the (k - 1)-th correction signal output unit (for example, the correction signal output unit 444). (err) is input. The k-th estimation signal output unit (for example, the estimation signal output unit 446) performs a series of processes shown in the flowchart of FIG. 10 based on the correction signal y output from the (k - 1)-th correction signal output unit (for example, the correction signal output unit 444), the output signal y of the filter processing unit 430, and the transmission path gain h. Then, the k-th estimation signal output unit (for example, the estimation signal output unit 446) outputs the estimated data set x (hat). (err) That is, the estimation signal output unit 446 outputs the estimated data set x (hat) based on the signal (second addition signal) obtained by adding the correction signal y output from the correction signal output unit 444 to the output signal y of the filter processing unit 430 and the transmission path gain h. The estimation signal output unit 446 is an example of the third estimation signal output unit in this embodiment, and the estimated data set x (hat) output from the estimation signal output unit 446 is an example of the third estimated value in this embodiment. Further, the estimation information calculation unit 4461 is an example of the third estimation information calculation unit in this embodiment. Furthermore, the estimated data set x (tilde) calculated by the estimation information calculation unit 4461 is an example of the third estimation information in this embodiment. Further, the estimation information conversion unit 4462 is an example of the third estimation information conversion unit in this embodiment.

[0111] That is, the estimation signal output unit 446 outputs the estimated data set x (hat) based on the transmission path gain h and the signal (second addition signal) obtained by adding the correction signal y output from the correction signal output unit 444 to the output signal y of the filter processing unit 430. The estimation signal output unit 446 is an example of the third estimation signal output unit in this embodiment, and the estimated data set x (hat) output from the estimation signal output unit 446 is an example of the third estimated value in this embodiment. Also, the estimation information calculation unit 4461 is an example of the third estimation information calculation unit in this embodiment. Furthermore, the estimated data set x (tilde) calculated by the estimation information calculation unit 4461 is an example of the third estimation information in this embodiment. Further, the estimation information conversion unit 4462 is an example of the third estimation information conversion unit in this embodiment. (err) In this embodiment, assuming that the estimated data set x (hat) of the k-th estimation signal output unit (for example, the estimation signal output unit 446) is output from the transmission signal estimation unit 440, the description will continue by returning to FIG. 9.

[0112] In this embodiment, assuming that the estimated data set x (hat) of the k-th estimation signal output unit (for example, the estimation signal output unit 446) is output from the transmission signal estimation unit 440, the description will continue by returning to FIG. 9.

[0113] In step S24, the bit signal conversion processing unit 450 converts the estimated data set x (hat) received from the transmission signal estimation unit 440 into N received bit sequences by performing the inverse conversion of the processing performed by the bit signal conversion processing unit 120.

[0114] In step S25, the serial-to-parallel conversion processing unit 460 rearranges the N bit sequences into a single bit sequence and outputs it.

[0115] As described above, in the transmission / reception system 1000 of the present embodiment, when transmitting a signal from the transmission device 1 to the reception device 4, pre-coding processing and clipping processing are performed on the signal to be transmitted. Further, in the reception device 4, even without information regarding the processing performed on the signal transmitted by the transmission device 1, the signal transmitted from the transmission device 1 can be estimated. Therefore, when transmitting a signal from the transmission device, it is not necessary to transmit redundant information.

[0116] <2.8. Peak power reduction effect> Subsequently, the peak power reduction effect in the transmission / reception system 1000 of the present embodiment will be described using a specific example. FIG. 12 is a diagram showing the comparison result between the transmission bit sequence input to the transmission device 1 and the reception bit sequence output by the reception device 4 in the transmission / reception system 1000. FIG. 12 shows a graph of the bit error rate (BER) calculated by comparing the transmission bit sequence input to the transmission device 1 and the reception bit sequence output by the reception device 4.

[0117] Assuming that the modulation method in the bit signal conversion processing unit 120 of the transmission device 1 is 16QAM and the waveform shaping filter in the filter processing unit 130 is an RRC filter with a roll-off factor of 0.1, the ratio of the transmission signal output by the transmission device 1 to the average signal power is at most 10 dB or more. When the maximum amplitude value A is set to 1.6 times the effective value by the clipping processing unit 150, the PAPR can be reduced to approximately 4 dB (≒20×log101.6). However, on the other hand, approximately 10% of the transmission signals will be affected by the distortion due to the clipping processing.

[0118] In FIG. 12, the BER of the received signal after the processing by the estimated signal output unit 441, correction signal output unit 442, estimated signal output unit 443, correction signal output unit 444, and estimated signal output unit 446 for the transmission signal received by the receiving device 4 is shown. Note that the parameter ρ, parameter τ q and the parameters θ0, θ1, ···, θ m are parameters obtained as a result of learning by the error backpropagation method, assuming random sample data, a batch size of 8192 symbols, and 10000 epochs, respectively.

[0119] The horizontal axis of the graph in FIG. 12 represents the signal-to-noise ratio (SNR) for an additive Gaussian noise communication channel, and the vertical axis represents the BER. Also, in FIG. 12, the BER characteristics of the receiving device 4 according to the present embodiment are indicated by black triangular markers, and the BER characteristics of a conventional receiving device as a reference example that does not include an element corresponding to the transmission signal estimation unit 440 are indicated by black circular markers.

[0120] As shown in FIG. 12, the receiving device of the reference example is affected by the limitation of signal components of 1.6 times or more of the effective value due to the clipping processing in the transmission device, and the amount of decrease in BER with respect to the increase in SNR is small. On the other hand, in the receiving device 4 of the present embodiment, the BER decreases with respect to the increase in SNR, and it can be observed that the influence of the clipping processing in the transmission device 1 is less compared to the reference example.

[0121] As shown in FIG. 12, in the transmission / reception system 1000 of the present embodiment, even when a signal is transmitted after performing clipping processing, the PAPR of the transmitted signal can be reduced without significantly degrading the communication quality. As described above, in the receiving device 4, since the signal transmitted from the transmitting device 1 can be estimated even without information regarding the processing performed on the signal transmitted by the transmitting device 1, it is not necessary to transmit redundant information when transmitting a signal from the transmitting device. Therefore, in the present embodiment, in a transmission / reception system such as MIMO transmission, it is possible to achieve both reduction of peak power and reduction of transmission rate.

[0122] <3. Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. 13 and 14. The above-described first embodiment is a specific embodiment, while the second embodiment is a more generalized embodiment. According to the following second embodiment, the same technical effects as those of the first embodiment are achieved.

[0123] FIG. 13 is a block diagram illustrating a schematic configuration of a receiving device 4A according to a second embodiment of the present invention. The receiving device 4A includes a reception processing unit 410A, a signal separation unit 420A, and a transmission signal estimation unit 440A.

[0124] The reception processing unit 410A performs clipping processing to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing precoding processing on two or more integral numbers of transmission data sets, and receives a transmission signal from a transmission device (for example, the transmission device 1A in FIG. 14) that outputs the transmission signal simultaneously or substantially simultaneously within the same frequency band.

[0125] The signal separation unit 420A separates the same number of reception data sets as the transmission data sets from the received transmission signal by performing inverse conversion of the precoding processing on the received transmission signal.

[0126] The transmission signal estimation unit 440A estimates a signal distortion component and a noise component due to clipping processing and an interference component between transmission signals based on a received data set and gain information regarding a transmission path through which the transmission signals are transmitted, and estimates a transmission data set by removing the estimated signal distortion component, noise component, and interference component from the received data set.

[0127] FIG. 14 is a block diagram illustrating a schematic configuration of a transmission / reception system 1000A according to a second embodiment of the present invention. The transmission / reception system 1000A includes a transmission device 1A and a reception device 4A.

[0128] - Relationship with the First Embodiment As an example, the reception device 4A according to the second embodiment may execute the operations of the reception device 4 according to the first embodiment. In the above case, the description of the first embodiment is also applicable to the second embodiment. Note that the second embodiment is not limited to the above example.

[0129] <4. Other Embodiments> Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. It will be understood by those skilled in the art that these embodiments are merely illustrative and that various modifications can be made without departing from the scope and spirit of the present invention.

[0130] For example, the steps in the processes described in this specification do not necessarily have to be executed in time series in the order described in the flowchart. For example, the steps in the process may be executed in an order different from the order described as a flowchart, or may be executed in parallel. Also, some of the steps in the process may be deleted, and additional steps may be added to the process.

[0131] In addition, a device including the components of the receiving device 4 described in this specification (for example, components corresponding to the receiving processing unit 410, the signal separation processing unit 420, and the transmission signal estimation unit 440) may be provided. Further, a method including the processing of the above components may be provided, and a program for causing a processor to execute the processing of the above components may be provided. Also, a non-transitory computer readable medium recording the program may be provided. Naturally, such a device, module, method, program, and non-transitory computer readable medium are also included in the present invention.

[0132] Some or all of the above embodiments may be described as follows in the appended claims, but are not limited thereto.

[0133] (Appended Claim 1) A receiving processing unit that receives a transmission signal from a transmission device that performs clipping processing to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing precoding processing on two or more integer numbers of transmission data sets, and outputs the plurality of transmission signals within the same frequency band simultaneously or substantially simultaneously; A signal separation unit that separates the same number of received data sets as the transmission data sets from the transmission signal by performing an inverse conversion of the precoding processing on the received transmission signal; Based on the received data set and gain information regarding the transmission path through which the transmission signal is transmitted, a transmission signal estimation unit that estimates a signal distortion component and a noise component due to the clipping processing and an interference component between the transmission signals, and removes the estimated signal distortion component, the noise component, and the interference component from the received data set to estimate the transmission data set; and A receiving device.

[0134] (Appended Claim 2) The transmission signal estimation unit A first estimation signal output unit that outputs a first estimated value of the transmission data based on the received data set and the gain information; Estimate a first difference data set indicating the signal distortion component and the noise component based on the first estimated value and the gain information, estimate a first interference signal indicating the interference component based on the first difference data set and the gain information, and output a first correction signal for correcting the received data set based on the first difference data set and the first interference signal. A first correction signal output unit; Based on the first addition signal obtained by adding the first correction signal to the received data set and the gain information, a second estimated signal output unit that outputs a second estimated value of the transmission data set; Estimate a second difference data set indicating the signal distortion component and the noise component based on the second estimated value and the gain information, estimate a second interference signal indicating the interference component based on the second difference data set and the gain information, and output a second correction signal for correcting the received data set based on the second difference data set and the second interference signal. A second correction signal output unit; Based on the second addition signal obtained by adding the second correction signal to the received data set and the gain information, a third estimated signal output unit that outputs a third estimated value of the transmission data set; Comprising The receiving device according to Supplementary Note 1.

[0135] (Supplementary Note 3) The first estimated signal output unit A first estimated information calculation unit that calculates first estimated information regarding the transmission signal based on the received data set, the gain information, and a first parameter that is a positive real number; A first estimated information conversion unit that converts the first estimated information into the first estimated value by a second parameter that is a non-zero real number and a third parameter that is a polynomial of a positive integer order; The second estimated signal output unit A second estimated information calculation unit that calculates second estimated information regarding the transmission signal based on the first correction signal, the gain information, and the first parameter; a second estimated information conversion unit that converts the second estimated information into the second estimated value based on the second parameter and the third parameter; The third estimated signal output unit a third estimated information calculation unit that calculates third estimated information regarding the transmission signal based on the second correction signal, the gain information, and the first parameter; a third estimated information conversion unit that converts the third estimated information into the third estimated value based on the second parameter and the third parameter; The receiving device according to Supplementary Note 2.

[0136] (Supplementary Note 4) The second parameter and the third parameter are parameters determined by learning using the error backpropagation method. The receiving device according to Supplementary Note 3.

[0137] (Supplementary Note 5) The first correction signal output unit after performing the precoding process and the clipping process on the first estimated value, a first difference processing unit that calculates the first difference data set based on an element obtained by separating a signal component synthesized with the first estimated value in the precoding process and the first estimated value; a first interference signal calculation unit that calculates the first interference signal based on the first difference data set and the gain information; a first correction signal calculation unit that calculates the first correction signal based on the first estimated value, the first interference signal, and the gain information; The second correction signal output unit after performing the precoding process and the clipping process on the second estimated value, a second difference processing unit that calculates the second difference data set based on an element obtained by separating a signal component synthesized with the second estimated value in the precoding process and the second estimated value; A second interference signal calculation unit that calculates the second interference signal based on the second difference data set and the gain information; A second correction signal calculation unit that calculates the second correction signal based on the second estimated value, the second interference signal, and the gain information; The receiving apparatus according to any one of Appendices 2 to 4.

[0138] (Appendix 6) The threshold value is a predetermined numerical value, The clipping process is A process of replacing the amplitude of the signal with the numerical value without changing the phase when the amplitude of the signal exceeds the numerical value. The receiving apparatus according to any one of Appendices 1 to 5.

[0139] (Appendix 7) Comprising an antenna unit in which a plurality of antenna elements are arranged concentrically, The reception processing unit receives the transmission signal via the antenna unit. The receiving apparatus according to any one of Appendices 1 to 6.

[0140] (Appendix 8) The receiving apparatus according to any one of Appendices 1 to 6, And the transmission apparatus. A transmission-reception system.

[0141] (Appendix 9) Performing a clipping process to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing precoding processing on two or more integer numbers of transmission data sets, and receiving the transmission signal from a transmission apparatus that outputs the plurality of transmission signals simultaneously or substantially simultaneously within the same frequency band; Separating the same number of received data sets as the transmission data sets from the transmission signal by performing an inverse conversion of the precoding process on the received transmission signal; Based on the received data set and gain information regarding the transmission path over which the transmission signal is transmitted, estimating a signal distortion component and a noise component due to the clipping process and an interference component between the transmission signals, and estimating the transmission data set by removing the estimated signal distortion component, noise component, and interference component from the received data set. Signal processing method.

[0142] (Appendix 10) Receiving the transmission signal from a transmission device that outputs a plurality of the transmission signals simultaneously or substantially simultaneously within the same frequency band by performing a clipping process for removing an amplitude equal to or greater than a threshold value on the transmission signal generated by performing precoding processing on two or more integer numbers of transmission data sets. Separating the same number of received data sets as the transmission data sets from the transmission signal by performing inverse conversion of the precoding process on the received transmission signal. Based on the received data set and gain information regarding the transmission path over which the transmission signal is transmitted, estimating a signal distortion component and a noise component due to the clipping process and an interference component between the transmission signals, and causing a processor to estimate the transmission data set by removing the estimated signal distortion component, noise component, and interference component from the received data set. Signal processing program.

Industrial Applicability

[0143] Provided are a receiving device, a transmission / reception system, a signal processing method, and a signal processing program capable of achieving both reduction of peak power and reduction of transmission rate.

Explanation of Signs

[0144] 1, 1A Transmission device 2 Transmission antenna unit 3 Reception antenna unit 4, 4A Receiving device 110 Serial-parallel conversion processing unit 120-bit signal conversion processing unit 130 filter processing unit 140 pre-coding processing unit 150 clipping processing unit 151 absolute value and phase separation processing unit 152 comparison processing unit 153 absolute value and phase combination processing unit 160 transmission processing unit 410, 410A reception processing unit 420 signal separation processing unit 420A signal separation unit 430 filter processing unit 440, 440A transmission signal estimation unit 441 estimated signal output unit 442 correction signal output unit 443 estimated signal output unit 444 correction signal output unit 446 estimated signal output unit 450 bit signal conversion processing unit 460 serial-to-parallel conversion processing unit 1000, 1000A transmission and reception system 4411 estimated information calculation unit 4412 estimated information conversion unit 4421 difference processing unit 4422 interference signal calculation unit 4423 correction signal calculation unit 4431 estimated information calculation unit 4432 estimated information conversion unit 4441 difference processing unit 4442 interference signal calculation unit 4443 correction signal calculation unit 4461 estimated information calculation unit 4462 estimated information conversion unit

Claims

1. A receiving processing unit that receives a transmission signal from a transmission device that performs clipping processing to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing precoding processing on two or more integer numbers of transmission data sets and outputs the plurality of transmission signals simultaneously or substantially simultaneously within the same frequency band; A signal separation unit that separates the same number of received data sets as the transmission data sets from the transmission signal by performing inverse conversion of the precoding processing on the received transmission signal; Based on the received data set and gain information regarding a transmission path through which the transmission signal is transmitted, a transmission signal estimator that estimates a signal distortion component and a noise component due to the clipping processing and an interference component between the transmission signals, and removes the estimated signal distortion component, noise component, and interference component from the received data set to estimate the transmission data set; A receiving apparatus.

2. The transmission signal estimator includes: A first estimated signal output unit that outputs a first estimated value of the transmission data set based on the received data set and the gain information; Estimate a first difference data set indicating the signal distortion component and the noise component based on the first estimated value and the gain information, estimate a first interference signal indicating the interference component based on the first difference data set and the gain information, and output a first correction signal for correcting the received data set based on the first difference data set and the first interference signal. A first correction signal output unit; A first addition signal obtained by adding the first correction signal to the received data set, and a second estimated signal output unit that outputs a second estimated value of the transmission data set based on the first addition signal and the gain information; Estimate a second difference data set indicating the signal distortion component and the noise component based on the second estimated value and the gain information, estimate a second interference signal indicating the interference component based on the second difference data set and the gain information, and output a second correction signal for correcting the received data set based on the second difference data set and the second interference signal. A second correction signal output unit; A second addition signal obtained by adding the second correction signal to the received data set, and a third estimated signal output unit that outputs a third estimated value of the transmission data set based on the second addition signal and the gain information; The receiving apparatus according to claim 1, comprising: The receiving apparatus according to claim 1.

3. The first estimated signal output unit includes: A first estimated information calculation unit that calculates first estimated information regarding the transmission signal based on the received data set, the gain information, and a first parameter that is a positive real number; A first estimated information conversion unit that converts the first estimated information into the first estimated value by a second parameter that is a non-zero real number and a third parameter that is a polynomial with a positive integer degree; The second estimated signal output unit includes: A second estimated information calculation unit that calculates second estimated information regarding the transmission signal based on the first correction signal, the gain information, and the first parameter; A second estimated information conversion unit that converts the second estimated information into the second estimated value by the second parameter and the third parameter; The third estimated signal output unit includes: A third estimated information calculation unit that calculates third estimated information regarding the transmission signal based on the second correction signal, the gain information, and the first parameter; A third estimated information conversion unit that converts the third estimated information into the third estimated value by the second parameter and the third parameter; The receiving device according to claim 2.

4. The second parameter and the third parameter are: Parameters determined by learning using the error backpropagation method. The receiving device according to claim 3.

5. The first correction signal output unit includes: A first difference processing unit that calculates the first difference data set based on an element obtained by separating a signal component synthesized with the first estimated value in the precoding process and the first estimated value after performing the precoding process and the clipping process on the first estimated value; A first interference signal calculation unit that calculates the first interference signal based on the first difference data set and the gain information; A first correction signal calculation unit that calculates the first correction signal based on the first estimated value, the first interference signal, and the gain information; The second correction signal output unit includes: A second difference processing unit that calculates the second difference data set based on an element obtained by separating a signal component synthesized with the second estimated value in the precoding process and the second estimated value after performing the precoding process and the clipping process on the second estimated value; A second interference signal calculation unit that calculates the second interference signal based on the second difference data set and the gain information; A second correction signal calculation unit that calculates the second correction signal based on the second estimated value, the second interference signal, and the gain information. The receiving apparatus according to any one of claims 2 to 4.

6. The threshold value is a predetermined numerical value. The clipping process is as follows. When the amplitude of the signal exceeds the numerical value, it is a process of replacing the amplitude of the signal with the numerical value without changing the phase. The receiving apparatus according to any one of claims 1 to 5.

7. The receiving apparatus according to any one of claims 1 to 6, And the transmitting apparatus. A transmission / reception system.

8. Receiving the transmission signal from a transmission apparatus that performs a clipping process to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing a precoding process on two or more integer numbers of transmission data sets and outputs the plurality of transmission signals simultaneously or substantially simultaneously within the same frequency band; Separating the same number of received data sets as the transmission data sets from the transmission signal by performing an inverse conversion of the precoding process on the received transmission signal; Estimating a signal distortion component and a noise component due to the clipping process and an interference component between the transmission signals based on the received data sets and gain information regarding a transmission path through which the transmission signal is transmitted, and removing the estimated signal distortion component, noise component, and interference component from the received data sets to estimate the transmission data sets. A signal processing method.

9. Receiving the transmission signal from a transmission apparatus that performs a clipping process to remove an amplitude equal to or greater than a threshold value on a transmission signal generated by performing a precoding process on two or more integer numbers of transmission data sets and outputs the plurality of transmission signals simultaneously or substantially simultaneously within the same frequency band; Separating the same number of received data sets as the transmission data sets from the transmission signal by performing an inverse conversion of the precoding process on the received transmission signal; Based on the received data set and gain information regarding the transmission path over which the transmission signal is transmitted, estimate the signal distortion component and noise component due to the clipping process and the interference component between the transmission signals, and remove the estimated signal distortion component, noise component, and interference component from the received data set, thereby estimating the transmission data set, and cause a processor to execute the above. Signal processing program.

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