JP7605326B2 - Radio access network device, radio communication device, method, and recording medium - Google Patents

Description

The present disclosure relates to a radio access network device, a wireless communication device, a method, and a recording medium.

In the field of wireless communication, the development of technology to achieve high-speed communication is progressing in order to cope with the increase in traffic. Usually, to achieve high-speed communication, wireless communication devices need to be equipped with high-speed and high-precision digital-to-analog converters (DACs). However, there is an issue that such devices consume a lot of power.

To solve this problem, delta-sigma modulation may be used (see, for example, Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2). Delta-sigma modulation is a process that converts an analog signal as an input signal into a quantized signal (a pulse train). Delta-sigma modulation can reduce the resolution requirements of the DAC (even down to 1 bit in some cases). This can reduce the power consumption of the wireless communication device.

On the other hand, in wireless communication devices, a configuration is known in which multiple functions of a radio access network device are divided into two physically separated communication devices. For example, a base station is divided into a base band unit (BBU) and a remote unit (RU). The RU may be called an RRU (Remote Radio Unit), RRH (Remote Radio Head), or RAU (Remote Antenna Unit). The BBU and RU are connected via a communication path (e.g., optical fiber). In this configuration, RoF (Radio over Fiber) technology is used for transmitting signals between the BBU and RU.

Recently, systems using delta-sigma modulation and RoF technology have been considered (see, for example, Non-Patent Document 3). In the following, in such a system, a pulse train output by delta-sigma modulation is transmitted from the BBU to the RU via an optical fiber. In this case, the RU restores the pulse train to the original analog signal before delta-sigma modulation, for example, through an analog band-pass filter (BPF). Since the RU does not need to have a DAC, the power consumption of the RU can be reduced.

WO 2016/103981

T. Maehata, S. Kameda, and N. Suematsu, “1-bit feedforward distortion compensation technology for bandpass delta-sigma modulation,” IEICE Trans. Commun. , vol. E99-B, no. 5, pp. 1087-1092, May 2016 A. Frappe, A. Flament, B. Stefanelli, A. Kaiser, and A. Cathelin, “An all-digital RF signal generator using high-speed SD modulators,” IEEE Journal of Solid-State Circuits, vol. 44, no. 10, pp. 2722-2732, Oct. 2009 H. Li et al. , “Real-Time 100-GS/s Sigma-Delta Modulator for All-Digital Radio-over-Fiber Transmission,” J. Lightw. Technol. vol. 38, no. 2, pp. 386-393, Jul. 2019.

As described in Non-Patent Document 1, it is known that in a configuration using delta-sigma modulation, a phenomenon called spectrum leakage occurs due to distortion occurring in the waveform. Here, spectrum leakage is a phenomenon in which signal components occur in bands surrounding the desired frequency band (i.e., bands other than the desired frequency band). The quality of the signal output from the RU decreases due to spectrum leakage. In order to suppress the above distortion, it is necessary to exchange appropriate information between two communication devices (in this example, the BBU and the RU).

The present disclosure provides techniques for sending or receiving information to improve transmission between two communication devices.

In one or more embodiments, a first radio access network device that performs processing related to a first physical layer is provided. The first radio access network device includes an acquisition unit that acquires information related to transmission between the first radio access network device and a second radio access network device that performs processing related to a second physical layer higher than the first physical layer, and a transmission unit that transmits the information related to the transmission to the second radio access network device.

In one or more embodiments, a second radio access network device is provided that performs processing related to a second physical layer higher than a first physical layer. The second radio access network device includes a first radio access network device that performs processing related to the first physical layer, a receiver that receives information related to transmission between the second radio access network device and the first radio access network device, and a processor that performs processing related to communication with the first radio access network device using the information related to the transmission.

In one or more embodiments, a wireless communication device is provided. The wireless communication device includes a first radio access network device that performs processing related to a first physical layer, and a second radio access network device that performs processing related to a second physical layer higher than the first physical layer. The first radio access network device acquires information related to a transmission between the first radio access network device and the second radio access network device, and transmits the information related to the transmission to the second radio access network device. The second radio access network device receives the information related to the transmission, and uses the information related to the transmission to perform processing related to communication with the first radio access network device.

In one or more embodiments, a method is provided in a first radio access network device that performs processing related to a first physical layer. The method includes obtaining information related to a transmission between the first radio access network device and a second radio access network device that performs processing related to a second physical layer higher than the first physical layer, and transmitting the information related to the transmission to the second radio access network device.

In one or more embodiments, a method is provided in a second radio access network device that performs processing related to a second physical layer higher than a first physical layer. The method includes receiving information related to a transmission between a first radio access network device that performs processing related to the first physical layer and the second radio access network device, and performing processing related to communication with the first radio access network device using the information related to the transmission.

In one or more embodiments, a non-transitory computer-readable recording medium is provided. The non-transitory recording medium has recorded thereon a program that causes a processor to execute the following operations: acquiring information about a transmission between a first radio access network device that performs processing related to a first physical layer and a second radio access network device that performs processing related to a second physical layer higher than the first physical layer; and transmitting the information about the transmission to the second radio access network device.

In one or more embodiments, a non-transitory computer-readable recording medium is provided. The non-transitory recording medium has recorded thereon a program that causes a processor to execute the following operations: receiving information about a transmission between a first radio access network device that performs processing related to a first physical layer and a second radio access network device that performs processing related to a second physical layer higher than the first physical layer; and performing processing related to communication with the first radio access network device using the information about the transmission.

According to the above configuration, it is possible to transmit or receive information for improving transmission between two devices (a first radio access network device and a second radio access network device). Other problems, configurations, and effects will become clear from the description of the following embodiments.

1 is a diagram showing a schematic configuration of a wireless communication device according to a first embodiment. FIG. 2 is a diagram illustrating a configuration of a delta-sigma modulation section according to the first embodiment. FIG. 2 is a diagram illustrating a configuration of a neural network processing unit according to the first embodiment. FIG. 2 is a diagram illustrating a configuration of a neural network learning unit according to the first embodiment. FIG. 2 is a diagram illustrating a configuration of a modulation section according to the first embodiment. FIG. 2 is a diagram illustrating a flow of constructing a transmission model according to the first embodiment. 4 is a flowchart showing a flow of processing performed by the delta-sigma modulation device according to the first embodiment. 1 is a diagram illustrating an example of a specific configuration of a wireless communication device according to a first embodiment. FIG. 2 is a diagram illustrating a hardware configuration of a first device according to the first embodiment. FIG. 2 is a diagram illustrating a hardware configuration of a second device according to the first embodiment. 4 is a sequence diagram showing a processing flow of the wireless communication device according to the first embodiment. FIG. FIG. 13 is a diagram showing a configuration of a delta-sigma modulation section according to a modified example. FIG. 13 is a diagram showing the configuration of a first neural network according to a modified example. FIG. 13 is a diagram showing a configuration of a first neural network according to a modified example. 13 is a flowchart showing a flow of processing performed by a delta-sigma modulation device according to a modified example. FIG. 13 is a diagram showing a configuration of a neural network learning unit according to a modified example. FIG. 11 is a diagram illustrating a configuration of a wireless communication device according to a second embodiment. FIG. 11 is a sequence diagram showing a processing flow of the wireless communication device according to the second embodiment. FIG. 11 is a sequence diagram showing a processing flow of a wireless communication device according to a modified example. FIG. 11 is a sequence diagram showing a processing flow of a wireless communication device according to a modified example. FIG. 11 is a sequence diagram showing a processing flow of a wireless communication device according to a modified example. FIG. 11 is a sequence diagram showing a processing flow of a wireless communication device according to a modified example. FIG. 13 is a diagram illustrating a configuration of a wireless communication device according to a modified example. FIG. 13 is a diagram illustrating a configuration of a wireless communication device according to a modified example. FIG. 13 is a diagram showing the configuration of a wireless communication device according to a third embodiment. FIG. 13 is a diagram showing the configuration of a wireless communication device according to a fourth embodiment. FIG. 13 is a sequence diagram showing a processing flow of a wireless communication device according to the fourth embodiment. FIG. 11 is a sequence diagram showing a processing flow of a wireless communication device according to a modified example. FIG. 11 is a sequence diagram showing a processing flow of a wireless communication device according to a modified example. FIG. 11 is a sequence diagram showing a processing flow of a wireless communication device according to a modified example. FIG. 13 is a diagram illustrating a configuration of a wireless communication device according to a modified example. FIG. 13 is a diagram illustrating a configuration of a wireless communication device according to a modified example. FIG. 13 is a diagram illustrating a configuration of a wireless communication device according to a fifth embodiment. A diagram showing the configuration of a first radio access network device according to a fifth embodiment. A diagram showing the configuration of a second radio access network device according to the fifth embodiment. 13 is a flowchart showing a processing flow of the first radio access network device according to the fifth embodiment. 13 is a flowchart showing a processing flow of a second radio access network device according to the fifth embodiment. 1 is an example of a system using delta-sigma modulation and RoF technology. 1 is an example of a system using delta-sigma modulation and RoF technology.

One or more embodiments will be described below with reference to the accompanying drawings. In this specification and drawings, elements that can be described in the same way are designated by the same reference numerals to avoid redundant description.

The explanation will be given in the following order:
1. Overview of the embodiment 2. First embodiment 2-1. Schematic configuration of the wireless communication device 2-2. Configuration of the delta-sigma modulation section 2-3. Configuration of the neural network processing section 2-4. Overview of the configuration of the neural network learning section 2-5. Configuration of the communication path 2-6. Configuration of the bandpass filter 2-7. Configuration of the modulation section 2-8. Specific configuration of the neural network learning section 2-9. Processing flow of the delta-sigma modulation device 2-10. Specific configuration example of the wireless communication device 2-11. Configuration of the first device 2-12. Configuration of the second device 2-13. Processing flow of the wireless communication device 2-14. Modification 3. Second embodiment 3-1. Schematic configuration of the wireless communication device 3-2. Configuration of the first device 3-3. Configuration of the second device 3-4. Overview of the processing flow of the wireless communication device 3-5. Processing flow of the wireless communication device 3-6. Modification 4. Third embodiment 4-1. Schematic configuration of a wireless communication device 4-2. Configuration of the first device 4-3. Configuration of the second device 5. Fourth embodiment 5-1. Schematic configuration of a wireless communication device 5-2. Configuration of the first device 5-3. Configuration of the second device 5-4. Processing flow of the wireless communication device 5-5. Modification 6. Fifth embodiment 6-1. Configuration of the wireless communication device 6-2. Processing flow of the wireless communication device 6-3. Modification

<<1. Overview of the embodiment>>
A brief summary of one or more embodiments is provided below.

(1) Technical Issues Fig. 38 shows an example of a system using delta-sigma modulation and RoF technology. This system includes a first device 3710 and a second device 3720. The first device 3710 and the second device 3720 are connected via an optical fiber 3730.

The first device 3710 includes an O/E converter (Optic-Electric converter) 3711, a bandpass filter (BPF) 3712, an amplifier 3713, and an antenna 3714. The second device 3720 includes a delta-sigma modulator 3721 and an E/O converter (Electric-Optic converter) 3722.

The analog signal 3741 as an input signal is converted into a quantized signal (pulse train) 3742 through the delta sigma modulation unit 3721. Note that this delta sigma modulation unit 3721 has a typical configuration of one input and one output, and the quantized signal (pulse train) is fed back inside the delta sigma modulation unit 3721. The pulse train 3742 is converted into an optical signal through the E/O conversion unit 3722. The optical signal is transmitted on the optical fiber 3730. Then, the optical signal is converted into an electrical signal 3743 through the O/E conversion unit 3711. The electrical signal 3743 is converted into the original analog signal 3745 before delta sigma modulation through the BPF 3712. The analog signal 3745 is amplified using the amplifier 3713. The amplified analog signal is output from the antenna 3714.

In the system of Figure 38, ideal delta-sigma modulation is performed. No distortion occurs in the pulse train 3742 during the transmission process of the pulse train 3742. As a result, no spectrum leakage occurs.

Figure 39 is an example of a system using delta-sigma modulation and RoF technology. In this system, distortion occurs in pulse train 3742 during the transmission process of pulse train 3742. For example, distortion occurs when an optical signal passes through optical fiber 3730. This type of distortion is called "optical transmission distortion." Pulse train 3810 represents a state in which optical transmission distortion has occurred.

Furthermore, distortion also occurs when there is a large power reflection between the O/E conversion unit 3711 and the BPF 3712. Such distortion is referred to as "electrical transmission distortion." The pulse train 3820 represents a state in which electrical transmission distortion has occurred. Hereinafter, optical transmission distortion and electrical transmission distortion are collectively referred to as "transmission distortion."

As a result, the transmission distortion affects the frequency components of the analog signal 3830 output through the BPF 3712. Specifically, the above-mentioned spectrum leak occurs. This causes the signal-to-noise ratio (S/N) of the analog signal 3830 to deteriorate. Thus, there is a problem in that the signal quality deteriorates due to the transmission distortion.

To solve the above problems, a configuration is required for transmitting or receiving appropriate information to improve transmission between two devices (a first device 3710 and a second device 3720).

(2) Technical Features In one or more embodiments, the wireless communication device includes a first radio access network device and a second radio access network device. The first radio access network device is a device that performs processing related to a first physical layer. The second radio access network device is a device that performs processing related to a second physical layer that is higher than the first physical layer. Here, the first and second physical layers may be considered to be included in a first layer (lowest layer) among multiple layers that constitute a communication protocol implemented in the first radio access network device and the second radio access network device.

The first radio access network device includes an acquisition unit that acquires information regarding transmission between the first radio access network device and the second radio access network device, and a transmission unit that transmits the information regarding the transmission to the second radio access network device.

The second radio access network device has a receiving unit that receives information regarding the transmission, and a processing unit that uses the information regarding the transmission to perform processing related to communication with the first radio access network device.

The above configuration has the following effects: The first radio access network device transmits (feeds back) information regarding the transmission to the second radio access network device. The second radio access network device can use the information regarding the transmission to improve the transmission between the two devices (the first radio access network device and the second radio access network device).

<<2. First embodiment>>
Next, a first embodiment and a modification thereof will be described with reference to FIGS.

<2-1. General configuration of wireless communication device>
1 is a diagram showing a schematic configuration of a wireless communication device 100. The wireless communication device 100 is a device that complies with the technical specifications of 3GPP (Third Generation Partnership Project). Specifically, the wireless communication device 100 may be a device that complies with the technical specifications of 5G (5th Generation). Of course, the wireless communication device 100 is not limited to this example.

The wireless communication device 100 includes a delta-sigma modulation device 110 and a transmission path 120. The wireless communication device 100 converts a signal output by the delta-sigma modulation device 110 into a wireless signal via the transmission path 120, and transmits the wireless signal to the terminal device 190.

The delta-sigma modulation device 110 includes a delta-sigma modulation unit 111, a neural network processing unit 112, and a neural network learning unit 113. Hereinafter, the neural network processing unit 112 is referred to as the "NN processing unit 112." The neural network learning unit 113 is referred to as the "NN learning unit 113."

The transmission path 120 includes a communication path 130 and a transmitter 140. The communication path 130 connects the delta-sigma modulator 111 and the transmitter 140. The transmitter 140 includes an antenna 141, a bandpass filter (BPF) 142, an amplifier 143, and a modulator 144.

The delta-sigma modulation unit 111 performs delta-sigma modulation on an analog signal as an external input signal, and outputs a quantized signal (1-bit pulse train). The quantized signal is transmitted to the BPF 142 via the communication path 130. The BPF 142 performs bandpass processing (hereinafter referred to as "BPF processing") on the quantized signal, which passes only a desired frequency band. The quantized signal is converted to an analog signal through the BPF 142. That is, the quantized signal is restored to the original analog signal before delta-sigma modulation. The amplifier 143 amplifies the analog signal. The antenna 141 outputs the amplified analog signal. In this way, the transmission unit 140 has the function of transmitting a signal to the terminal device 190.

The amplified analog signal is also output to the modulation unit 144. The modulation unit 144 performs a modulation process on the analog signal and outputs the modulated analog signal to the NN learning unit 113. In this way, the transmission unit 140 also has the function of transmitting (i.e., feeding back) a signal generated through the transmission process of the quantized signal output by the delta-sigma modulation unit 111 to the delta-sigma modulation device 110.

Hereinafter, the analog signal input to the delta-sigma modulation unit 111 is referred to as the "first signal". Furthermore, the quantized signal output by the delta-sigma modulation unit 111 is referred to as the "second signal". Furthermore, the signal generated through the transmission process of the second signal and fed back to the NN learning unit 113 is referred to as the "third signal". In other words, the third signal is a signal generated in the process in which the second signal is transmitted on the transmission path 120. The third signal may include information about the transmission distortion that occurs in the transmission path 120. Therefore, the third signal is used to feed back information about the transmission distortion that occurs in the transmission path 120.

The NN processing unit 112 includes a first neural network 300 that operates according to predetermined parameters (see FIG. 3). Hereinafter, the first neural network 300 is referred to as the "first NN 300." The parameters of the first NN 300 are referred to as the "first parameters."

The NN learning unit 113 receives the second signal and the third signal as input signals. The NN learning unit 113 calculates a first parameter using the second signal and the third signal. The NN learning unit 113 transmits the calculated first parameter to the NN processing unit 112.

The NN processing unit 112 receives a first parameter from the NN learning unit 113. The NN processing unit 112 updates the first parameter of the first NN 300 to the received first parameter (i.e., the first parameter calculated by the NN learning unit 113).

The NN processing unit 112 receives the second signal as an input signal. Using the second signal, the NN processing unit 112 outputs an approximation (analog signal) of a signal generated through at least a part of the transmission process of the second signal through the first NN 300. Hereinafter, this approximation is referred to as the "fourth signal." Using the fourth signal, the NN processing unit 112 can feed back information about the transmission distortion that occurs in the transmission process of the second signal to the delta-sigma modulation unit 111.

The delta-sigma modulation unit 111 receives a first signal and a fourth signal as input signals. The delta-sigma modulation unit 111 performs delta-sigma modulation on the first signal using the fourth signal to output a second signal.

In general, the one-input, one-output configuration described in FIG. 38 (i.e., the delta-sigma modulation unit 3721 in which the quantized signal is directly fed back inside) is referred to as delta-sigma modulation. In contrast, in one or more embodiments of the present disclosure, the second signal is not directly fed back as the fourth signal, and the second signal and the fourth signal are separated by interposing the NN processing unit 112 between them. The delta-sigma modulation unit 111 is configured to receive two signals, the first signal and the fourth signal, as input signals and output the second signal, that is, a two-input, one-output configuration. In one or more embodiments of the present disclosure, for convenience, such a two-input, one-output configuration is defined as delta-sigma modulation. The NN processing unit 112 performs a feedback function. One or more embodiments are characterized in that the first parameter in the NN processing unit 112 is updated by the NN learning unit 113.

<2-2. Configuration of delta-sigma modulation section>
There are two types of devices that implement the delta-sigma modulation unit 111: a band-pass type (see Non-Patent Document 1) and a low-pass type (see Non-Patent Document 2). The delta-sigma modulation unit 111 in this example is a band-pass type device, and is implemented with reference to Non-Patent Document 1.

Figure 2 is a diagram showing an example of the configuration of the delta-sigma modulation unit 111. The delta-sigma modulation unit 111 includes an upconverter 210, a loop filter 220, and a quantizer 230.

The first signal is a baseband signal and includes an in-phase component signal (hereinafter referred to as the "I signal") and a quadrature component signal (hereinafter referred to as the "Q signal").

The upconverter 210 is a two-input, one-output component. The upconverter 210 receives an I signal and a Q signal as input signals. The upconverter 210 upconverts the first signal (I signal and Q signal) to a desired frequency (target frequency) f0.

The upconverter 210 includes a first multiplier 211a, a second multiplier 211b, and an adder 212. The first multiplier 211a multiplies the I signal by cosωt and outputs the multiplication result to the adder 212. The second multiplier 211b multiplies the Q signal by -sinωt and outputs the multiplication result to the adder 212. Here, "cos()" is a cosine function, and "sin()" is a sine function (same below). Furthermore, ω = 2 × π × f0.

The adder 212 adds the multiplication result of the first multiplier 211a and the multiplication result of the second multiplier 211b and outputs the addition result.

The loop filter 220 is a two-input, one-output element. The loop filter 220 receives the output of the upconverter 210 and the fourth signal as input signals. The loop filter 220 performs processing to suppress transmission distortion contained in the feedback component (i.e., the fourth signal) of the input signal.

The loop filter 220 comprises a first adder 221a, a second adder 221b, and a transfer function processing unit 222.

The first adder 221a adds the output of the upconverter 210 (the output of the adder 212) and the fourth signal, and outputs the addition result to the transfer function processing unit 222. Here, the output of the first adder 221a is the difference between the output of the upconverter 210 and the fourth signal. In other words, the output of the first adder 221a may include a component of transmission distortion that occurs in the transmission process of the second signal.

The transfer function processing unit 222 applies a transfer function to the output of the first adder 221a to output a component for suppressing (or canceling) at least a portion of the transmission distortion occurring in the transmission process (transmission path 120) of the second signal. The transfer function is a function that determines the characteristics of the delta-sigma modulation in this example, and is determined based on the desired signal transfer function and noise transfer function, etc.

The second adder 221b adds the output of the upconverter 210 and the output of the transfer function processing unit 222, and outputs the addition result to the quantizer 230.

In this way, the loop filter 220 uses the output of the upconverter 210 and the fourth signal to output a signal (analog signal) that includes components for suppressing at least a portion of the transmission distortion that occurs during the transmission process of the second signal.

The quantizer 230 is a 1-bit quantizer. The quantizer 230 quantizes the output of the loop filter 220 (the output of the second adder 221b) with 1 bit and outputs a second signal (a 1-bit pulse train).

In this way, the delta-sigma modulation unit 111 uses the fourth signal to calculate a component for suppressing at least a portion of the transmission distortion that occurs during the transmission process of the second signal, and reflects the component in the second signal.

In another example, the second adder 221b may be omitted in the loop filter 220. In this case, the output of the transfer function processing unit 222 is input to the quantizer 230. The output of the transfer function processing unit 222 includes the output of the upconverter 210 and a component for suppressing at least a portion of the transmission distortion occurring in the transmission process of the second signal.

<2-3. Configuration of Neural Network Processing Unit>
3 is a diagram showing an example of the configuration of the NN processing unit 112. The NN processing unit 112 includes a first NN 300. The first NN 300 receives the second signal as an input signal, and outputs a fourth signal.

In this example, the fourth signal is an approximation (estimate) of a signal generated in the process in which the second signal passes through a portion of the transmission path 120. More specifically, the fourth signal is an approximation (estimate) of a signal generated in the process in which the second signal passes through the communication path 130, the BPF 142, and the amplifier 143. In other words, the fourth signal is an approximation (estimate) of a radio signal output from the antenna 141.

Therefore, the fourth signal includes at least a partial approximation of the transmission distortion that occurs during the transmission process of the second signal. Specifically, the fourth signal includes at least a partial approximation of the transmission distortion that occurs during the process of the second signal passing through the communication path 130, the BPF 142, and the amplifier 143.

The first NN 300 operates according to a first parameter. The first parameter includes, for example, a weight and a bias. For example, if a function f in the following formula (1) is an activation function in a neural network, x is an input, w is a weight, and b is a bias.
f(wx+b)...(1)

The first NN 300 comprises an input layer 310, an intermediate layer 320, and an output layer 330. The intermediate layer 320 has one layer.

The input layer 310 includes a node 310a to which the current value of the second signal is input. The input layer 310 further includes a node 310b to which the past value of the second signal is input. Note that "D" represents a delay. The output layer 330 is a linear layer that does not have an activation function. The first parameter is reflected in the intermediate layer 320. The output layer 330 outputs the sum of the outputs of the multiple nodes in the intermediate layer 320 as a fourth signal.

The configuration of the first NN300 is not limited to the configuration of FIG. 3. Various commonly used neural networks may be applied to this embodiment. For example, the intermediate layer 320 of the first NN300 may have multiple layers. That is, a multi-layer neural network may be adopted as the first NN300.

The NN processing unit 112 receives a first parameter from the NN learning unit 113. The NN processing unit 112 updates the first parameter of the first NN 300 to the received first parameter. That is, the NN processing unit 112 updates the first parameter according to the state of the transmission path 120. Therefore, the NN processing unit 112 can reflect at least a portion of the transmission distortion occurring in the current state of the transmission path 120 in the fourth signal.

<2-4. Overview of the configuration of the neural network learning unit>
4 is a diagram showing an example of the configuration of the NN learning section 113. The NN learning section 113 includes a transmission model 410, an error calculation section 420, and a parameter calculation section 430.

The transmission model 410 is a component that models at least a part of the transmission process of the second signal. In this example, the transmission model 410 is a component that models the transmission path 120. The transmission model 410 uses the second signal to output an approximation (estimate) of the third signal.

The transmission model 410 includes a second neural network 600 that operates according to predetermined parameters (see FIG. 6). Hereinafter, the second neural network 600 is referred to as the "second NN 600." The parameters of the second NN 600 are referred to as the "second parameters." The second parameters, like the first parameters, include weights and biases.

The error calculation unit 420 receives the output of the transmission model 410 (approximation of the third signal) and the third signal (in this example, the output of the modulation unit 144) as input signals. The error calculation unit 420 calculates the error (difference) between the output of the transmission model 410 and the third signal. Hereinafter, this error is referred to as the "approximation error." The error calculation unit 420 outputs the approximation error to the parameter calculation unit 430.

The parameter calculation unit 430 calculates a first parameter and a second parameter using the approximation error. The parameter calculation unit 430 transmits the calculated first parameter to the NN processing unit 112. Furthermore, the parameter calculation unit 430 updates the second parameter of the second NN 600 to the calculated second parameter.

In this way, the NN learning unit 113 learns the current state of the transmission path 120 using the second signal and the third signal. That is, the NN learning unit 113 calculates the first parameter and the second parameter according to the current state of the transmission path 120. The NN learning unit 113 can reflect at least a part of the transmission distortion occurring in the current state of the transmission path 120 in the first NN 300 and the second NN 600.

2-5. Configuration of communication paths
The communication path 130 includes one or both of an electrical transmission line (eg, a metal line) that transmits an electrical signal and an optical transmission line (eg, an optical fiber) that transmits an optical signal.

In addition, the communication path 130 may include one or a combination of an E/O conversion unit that converts an electrical signal into an optical signal, an O/E conversion unit that converts an optical signal into an electrical signal, a bandpass filter, and a frequency conversion unit.

<2-6. Bandpass filter configuration>
The BPF 142 performs BPF processing on the output of the communication path 130. Here, the desired frequency band is the band from f0-fα to f0+fα, where fα is an arbitrary frequency.

The BPF 142 may be configured by analog elements. The BPF 142 may be an LC filter or an RLC filter. The LC filter is a filter configured based on a combination of an inductor (L) and a capacitor (C). The RLC filter is a filter configured based on a combination of a resistor (R), an inductor (L), and a capacitor (C).

2-7. Modulation section configuration
5 is a diagram showing an example of the configuration of the modulation section 144. The modulation section 144 down-converts the output of the amplifier 143 by a direct conversion method, and outputs the down-converted signal as a third signal.

The modulation unit 144 comprises a first modulation unit 500a and a second modulation unit 500b.

The first modulation unit 500a includes a first multiplier 510a, a first low-pass filter (LPF) 520a, and a first A/D converter (ADC) 530a.

The first multiplier 510a multiplies the output of the amplifier 143 by cosωt and outputs the multiplication result to the first LPF 520a. Here, ω = 2 × π × f0. The first LPF 520a performs low-pass filtering on the output of the first multiplier 510a and outputs the result to the first ADC 530a. The first ADC 530a converts the output of the first LPF 520a into a digital signal, thereby outputting a digital I signal.

The second modulation unit 500b includes a second multiplier 510b, a second low-pass filter (LPF) 520b, and a second A/D converter (ADC) 530b.

The second multiplier 510b multiplies the output of the amplifier 143 by -sinωt and outputs the multiplication result to the second LPF 520b. The second LPF 520b performs low-pass filtering on the output of the second multiplier 510b and outputs the result to the second ADC 530b. The second ADC 530b converts the output of the second LPF 520b into a digital signal, thereby outputting a digital Q signal.

Therefore, the third signal includes a digital I signal and a digital Q signal. The third signal is input to the NN learning unit 113.

2-8. Specific configuration of neural network learning unit
Next, a specific configuration of the NN learning unit 113 will be described. First, a configuration of the transmission model 410 will be described. FIG.

As shown in the upper part of FIG. 6, the transmission path 120 includes the communication path 130, the BPF 142, the amplifier 143, and the modulation section 144. Here, it is assumed that the amplifier 143 does not have strong nonlinearity, that is, the amplifier 143 has strong linearity. Since the BPF 142 also has linearity, the position of the BPF 142 and the position of the amplifier 143 can be swapped as shown in the middle part of FIG. 6. That is, the configuration of the transmission path 120 in the upper part can be approximated by the transmission path 120' in the middle part. This allows the communication path 130 and the amplifier 143 to be modeled together.

The communication path 130 and the amplifier 143 are collectively modeled by the second NN 600. The second NN 600 outputs an approximation (estimate) of a signal generated through a part of the transmission process of the second signal. Specifically, the second NN 600 outputs an approximation of a signal generated in the process of the second signal passing through the communication path 130 and the amplifier 143.

The BPF 142 is modeled by a digital filter 610. The digital filter 610 may be, for example, a finite impulse response (FIR) filter.

The modulation unit 144 is modeled by a digital downconverter 620. The digital downconverter 620 has the same functions/properties as the modulation unit 144. Therefore, the digital downconverter 620 downconverts the output of the digital filter 610 to output a digital I signal and a digital Q signal.

Next, we will explain the approximation error calculated by the error calculation unit 420. The approximation error represents the error between the approximation value of the third signal (the output of the transmission model 410) and the actual third signal (the output of the modulation unit 144).

At the time when the wireless communication device 100 is started, the information on the transmission distortion occurring in the transmission path 120 is not reflected in the second NN 600, so the transmission model 410 outputs the second signal as it is. On the other hand, the actual third signal includes the transmission distortion occurring in the transmission process of the second signal. When the magnitude of the transmission distortion (hereinafter referred to as the "distortion amount") increases, the approximation error increases. If the approximation error is large, this means that the information on the transmission distortion currently occurring in the transmission path 120 cannot be reflected in the first NN 300 and the second NN 600, and therefore the transmission distortion cannot be suppressed. On the other hand, even after the information on the transmission distortion occurring in the transmission path 120 is reflected in the second NN 600, the distortion amount changes over time. Therefore, if the approximation error is large, this also means that the difference (error) between the distortion amount included in the output of the transmission model 410 and the distortion amount included in the actual third signal is large. Therefore, the approximation error is a value related to the distortion amount occurring in the transmission process of the second signal.

If the approximation error is small, this means that the output of the transmission model 410 is close to the actual third signal. In other words, this means that information about the transmission distortion currently occurring in the transmission path 120 can be reflected in the first NN 300 and the second NN 600, and therefore the transmission distortion can be suppressed.

The error calculation unit 420 calculates a first difference, which is the difference between the I signal output by the transmission model 410 and the I signal included in the third signal. Since the I signal is a real component, the first difference is a real component. Furthermore, the error calculation unit 420 calculates a second difference, which is the difference between the Q signal output by the transmission model 410 and the Q signal included in the third signal. Since the Q signal is an imaginary component, the second difference is an imaginary component.

The error calculation unit 420 calculates an approximation error based on the first difference and the second difference. For example, the approximation error may be a complex number represented by the first difference, which is a real component, and the second difference, which is an imaginary component. According to another example, the approximation error may be the greater of the absolute value of the first difference and the absolute value of the second difference. The approximation error may be calculated by one of the known calculation methods, as long as it represents the error between the output of the transmission model 410 and the actual third signal.

The parameter calculation unit 430 calculates the first parameter and the second parameter using the approximation error and the internal parameters of the transmission model 410. The internal parameters of the transmission model 410 may include the second parameter of the second NN 600 and the output value of at least one node in the second NN 600. In another example, the internal parameters of the transmission model 410 may further include the filter coefficient of the digital filter 610 and the sine wave and the cosine wave in the digital down converter 620. The parameter calculation unit 430 calculates the first parameter and the second parameter so that the approximation error is small. For example, the parameter calculation unit 430 calculates the first parameter and the second parameter so that at least one of the absolute value of the first difference and the absolute value of the second difference is small.

<2-9. Processing flow of the delta-sigma modulation device>
Next, the flow of processing by the delta-sigma modulation device 110 will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of the flow of processing by the delta-sigma modulation device 110.

When the wireless communication device 100 is started (or the wireless communication device 100 is reset), the delta-sigma modulation unit 111 performs delta-sigma modulation on a first signal as an external input signal, and outputs a second signal (701).

The NN learning unit 113 calculates the first parameter and the second parameter using the second signal and the third signal (702). The NN learning unit 113 transmits the calculated first parameter to the NN processing unit 112.

The NN processing unit 112 updates the first parameter of the first NN 300 to the first parameter calculated by the NN learning unit 113. Furthermore, the NN learning unit 113 updates the second parameter of the second NN 600 in the transmission model 410 to the second parameter calculated above (703).

The NN processing unit 112 uses the second signal to output a fourth signal through the first NN 300 (704).

The delta-sigma modulation unit 111 performs delta-sigma modulation on the first signal using the fourth signal to output a second signal (705).

Then, steps 702 to 705 are repeated.

The above configuration has the following effects. The delta-sigma modulation device 110 receives information on the transmission distortion occurring in the transmission process (transmission path 120) of the second signal as a third signal that is fed back. The delta-sigma modulation device 110 calculates an approximation error using the second signal and the third signal, and calculates a first parameter and a second parameter using the approximation error. The delta-sigma modulation device 110 updates the first parameter of the first NN 300 to the calculated first parameter, and updates the second parameter of the second NN 600 to the calculated second parameter. As a result, information on the transmission distortion occurring in the transmission path 120 is reflected in the first NN 300 and the second NN 600. The delta-sigma modulation device 110 performs delta-sigma modulation on the first signal using the fourth signal (the output of the first NN 300). This enables the delta-sigma modulation device 110 to perform noise shaping, which passes the signal component of the target frequency f0 and shifts noise near the frequency f0 out of the band.

The delta-sigma modulation device 110 can suppress the transmission distortion that occurs during the transmission process of the second signal by the feedback processing described above. Therefore, the delta-sigma modulation device 110 can suppress the spectrum leak. The delta-sigma modulation device 110 can transmit a high-quality signal.

<2-10. Specific configuration example of wireless communication device>
Next, a specific configuration of a wireless communication device will be described with reference to Figures 8 to 10. Figure 8 shows an example of a specific configuration of a wireless communication device 800. Components that have already been described are given the same reference numerals and detailed descriptions thereof will be omitted.

The wireless communication device 800 is a node of a radio access network (RAN). In this example, the wireless communication device 800 is a base station. The wireless communication device 800 performs wireless communication with a terminal device 190 located within its coverage area.

The wireless communication device 800 includes multiple devices (or multiple nodes). Specifically, the wireless communication device 800 includes a first device 810 and a second device 820. The first device 810 is a node of a wireless access network and may be referred to as a "first wireless access network device." The second device 820 is a node of a wireless access network and may be referred to as a "second wireless access network device."

The first device 810 performs processing related to the first physical layer. In this example, the processing related to the first physical layer includes BPF processing and amplification processing.

The second device 820 performs processing related to a second physical layer that is higher than the first physical layer. In this example, the processing related to the second physical layer includes delta-sigma modulation. The first and second physical layers may be considered to be included in the first layer (lowest layer) of multiple layers that constitute the communication protocol implemented in the first device 810 and the second device 820.

The first device 810 and the second device 820 are connected via a first communication path 131. The second device 820 transmits a second signal to the first device 810 via the first communication path 131.

The first device 810 and the second device 820 are connected via a second communication path 132. The first device 810 transmits information related to the transmission between the first device 810 and the second device 820 to the second device 820 via the second communication path 132. Hereinafter, the information related to the transmission is referred to as "transmission-related information."

In this example, the transmission-related information is information related to the transmission of a second signal transmitted from the second device 820 to the first device 810. Specifically, the transmission-related information is a third signal (i.e., the output of the modulation unit 144) generated in the transmission process of the second signal. The third signal includes information related to the transmission distortion that occurred in the transmission process of the second signal.

<2-11. Configuration of the first device>
The first device 810 includes an antenna 141, a BPF 142, an amplifier 143, a modulator 144, and an information transmitter 145. The information transmitter 145 controls communication with the second device 820 via the second communication path 132. Specifically, the information transmitter 145 controls transmission of transmission-related information.

Figure 9 is a diagram showing an example of the hardware configuration of the first device 810. The first device 810 includes a communication interface 910, a memory unit 920, and a processing unit 930.

The communication interface 910 is an interface for communication with other devices. The communication interface 910 includes an antenna 141 for wireless communication. Furthermore, the communication interface 910 includes a connection terminal, a connection circuit, etc. for communicating with the second device 820 via the first communication path 131. The communication interface 910 includes a connection terminal, a connection circuit, etc. for communicating with the second device 820 via the second communication path 132.

The storage unit 920 includes a volatile memory and a non-volatile memory. The volatile memory may include, for example, a random access memory (RAM). The non-volatile memory may include, for example, one or more of a read only memory (ROM), a hard disk drive (HDD), and a solid state drive (SSD). The non-volatile memory stores program code (instructions) for realizing one or more functions of the first device 810.

The processing unit 930 includes one or more processors. The one or more processors may include, for example, one or more of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), and a microcontroller. The processing unit 930 realizes one or more functions of the first device 810 by executing program code (instructions) stored in the memory unit 920.

The processing unit 930 may include one or more analog elements and/or analog circuits. The processing unit 930 may realize one or more functions of the first device 810 using one or more analog elements and/or analog circuits. In this specification, the expression "A and/or B" should be interpreted as "A or B" or "A and B".

<2-12. Configuration of the second device>
The second device 820 includes a delta-sigma modulation unit 111 , a NN processing unit 112 , and a NN learning unit 113 .

Figure 10 is a diagram showing an example of the hardware configuration of the second device 820. The second device 820 includes a communication interface 1010, a memory unit 1020, and a processing unit 1030.

The communication interface 1010 is an interface for communication with other devices. The communication interface 1010 includes a connection terminal, a connection circuit, etc. for communicating with the first device 810 via the first communication path 131. The communication interface 1010 includes a connection terminal, a connection circuit, etc. for communicating with the first device 810 via the second communication path 132.

In addition, the communication interface 1010 may include a connection terminal, a connection circuit, etc. for communicating with a node (not shown) of the core network. Furthermore, the communication interface 1010 may include an antenna for wireless communication with the first device 810.

The storage unit 1020 includes a volatile memory and a non-volatile memory. The volatile memory may include, for example, a RAM. The non-volatile memory may include, for example, one or more of a ROM, a HDD, and an SSD. The non-volatile memory stores program code (instructions) for realizing one or more functions of the second device 820.

The processing unit 1030 includes one or more processors. The one or more processors may include, for example, one or more of a CPU, an MPU, and a microcontroller. The processing unit 1030 executes program code (instructions) stored in the memory unit 1020 to realize one or more functions of the second device 820.

The processing unit 1030 may include one or more analog elements and/or analog circuits. The processing unit 1030 may implement one or more functions of the second device 820 using one or more analog elements and/or analog circuits.

<2-13. Processing flow of wireless communication device>
Next, a processing flow of the wireless communication device 800 will be described with reference to Fig. 11. Fig. 11 is a sequence diagram showing an example of a processing flow of the wireless communication device 800.

The second device 820 executes the process of step 701 in FIG. 7 (1101). Thus, the second device 820 transmits a second signal to the first device 810.

The first device 810 receives the second signal. Then, the first device 810 (in this example, the information transmitting unit 145) transmits the transmission-related information (in this example, the third signal) to the second device 820 (1102).

The second device 820 receives the transmission-related information and performs processing of steps 702 to 704 in FIG. 7 (1103).

The second device 820 executes the process of step 705 in FIG. 7 (1104). Therefore, the second device 820 transmits a second signal to the first device 810. Thereafter, the processes of steps 1102 to 1104 are repeatedly executed.

In addition, the information transmitting unit 145 of the first device 810 may transmit the transmission-related information to the second device 820 according to a predetermined rule. The information transmitting unit 145 may transmit the transmission-related information to the second device 820 periodically (i.e., at a predetermined time interval). The information transmitting unit 145 may transmit the transmission-related information to the second device 820 non-periodically.

The above configuration has the following effects. The first device 810 can feed back the transmission-related information to the second device 820. The second device 820 can receive the transmission-related information and perform appropriate processing for the transmission distortion occurring in the transmission process of the second signal. For example, the second device 820 updates the first parameter of the first NN 300 using the transmission-related information. This allows the second device 820 to transmit to the first device 810 a second signal including a component that suppresses the transmission distortion. Therefore, the transmission between the two devices (the first device 810 and the second device 820) can be improved.

<2-14. Modifications>
The technology according to the present disclosure is not limited to the above-described embodiments.

(1) First Modification The delta-sigma modulation section 111 may be a low-pass type device. Fig. 12 is a diagram showing an example of the configuration of the delta-sigma modulation section 111. Hereinafter, the I signal included in the first signal is referred to as a "first I signal". The Q signal included in the first signal is referred to as a "first Q signal".

The delta-sigma modulation unit 111 comprises a downconverter 1210, a first loop filter 1220, a second loop filter 1230, a first quantizer 1240, a second quantizer 1250, and an upconverter 1260.

The downconverter 1210 has a first multiplier 1211a and a second multiplier 1211b.

The first multiplier 1211a multiplies the fourth signal by cosωt to generate an I component of the fourth signal. Here, ω=2×π×f0. Hereinafter, the I component generated from the fourth signal is referred to as the "second I signal." The first multiplier 1211a outputs the second I signal to the first loop filter 1220.

The second multiplier 1211b multiplies the fourth signal by -sinωt to generate the Q component of the fourth signal. Hereinafter, the Q component generated from the fourth signal is referred to as the "second Q signal." The second multiplier 1211b outputs the second Q signal to the second loop filter 1230.

Thus, the downconverter 1210 downconverts the fourth signal to a second I signal and a second Q signal.

Note that if the signal sampling rate is set to 1/4 of the target frequency f0, i.e., f0/4, an example cosωt signal would be [1, 0, -1, 0, 1, ...], and an example -sinωt signal sequence would be [0, -1, 0, 1, 0, ...]. The symbol "/" here represents division. This simplifies the multiplication process described above. This modification may include such processing.

The first loop filter 1220 performs processing to suppress the transmission distortion contained in the feedback component (i.e., the second I signal). Specifically, the first loop filter 1220 uses the first I signal and the second I signal to output a signal including a first component for suppressing at least a portion of the transmission distortion occurring in the transmission process of the second signal (i.e., the transmission path 120).

The first loop filter 1220 comprises a first adder 1221a, a second adder 1221b, and a transfer function processing unit 1222.

The first adder 1221a adds the first I signal and the second I signal. The first adder 1221a outputs the addition result to the transfer function processing unit 1222. Here, the output of the first adder 1221a is the difference between the first I signal and the second I signal. In other words, the output of the first adder 1221a includes a part of the transmission distortion component that occurs in the transmission process of the second signal.

The transfer function processing unit 1222 applies a transfer function to the output of the first adder 1221a to output a first component for suppressing at least a portion of the transmission distortion occurring in the transmission path 120. The transfer function is a function that determines the characteristics of the delta-sigma modulation in this example, and is determined based on a desired signal transfer function and a noise transfer function, etc.

The second adder 1221b adds the first I signal to the output of the transfer function processing unit 1222 and outputs the addition result to the first quantizer 1240.

The first quantizer 1240 is a 1-bit quantizer. The first quantizer 1240 quantizes the output of the second adder 1221b with 1 bit and outputs the first quantized signal to the upconverter 1260.

The second loop filter 1230 performs processing to suppress the transmission distortion contained in the feedback component (i.e., the second Q signal). Specifically, the second loop filter 1230 uses the first Q signal and the second Q signal to output a signal including a second component for suppressing at least a portion of the transmission distortion occurring in the transmission process of the second signal (i.e., the transmission path 120).

The second loop filter 1230 has a first adder 1231a, a second adder 1231b, and a transfer function processing unit 1232.

The first adder 1231a adds the first Q signal and the second Q signal. The first adder 1231a outputs the addition result to the transfer function processing unit 1232. Here, the output of the first adder 1231a is the difference between the first Q signal and the second Q signal. In other words, the output of the first adder 1231a includes a part of the transmission distortion component that occurs in the transmission process of the second signal.

The transfer function processing unit 1232 applies a transfer function to the output of the first adder 1231a to output a second component for suppressing at least a portion of the transmission distortion occurring in the transmission path 120. The transfer function is a function that determines the characteristics of the delta-sigma modulation in this example, and is determined based on the desired signal transfer function and noise transfer function.

The second adder 1231b adds the first Q signal to the output of the transfer function processing unit 1232 and outputs the addition result to the second quantizer 1250.

The second quantizer 1250 is a 1-bit quantizer. The second quantizer 1250 quantizes the output of the second adder 1231b with 1 bit and outputs the second quantized signal to the upconverter 1260.

The upconverter 1260 is a two-input, one-output component. The upconverter 1260 includes a first multiplier 1261a, a second multiplier 1261b, and an adder 1262.

The first multiplier 1261a multiplies the first quantized signal by cosωt and outputs the multiplication result to the adder 1262.

The second multiplier 1261b multiplies the second quantized signal by -sinωt and outputs the multiplication result to the adder 1262.

The adder 1262 adds the output of the first multiplier 1261a and the output of the second multiplier 1261b to output a second signal. In this way, the upconverter 1260 upconverts the first quantized signal and the second quantized signal to output a second signal.

Note that, if the signal sampling rate is set to 1/4 of the desired frequency f0, i.e., f0/4, the signal sequence of cosωt is [1, 0, -1, 0, 1, ...], and the signal sequence of -sinωt is [0, -1, 0, 1, 0, ...]. The symbol "/" here represents division. This simplifies the above multiplication process. Furthermore, since the output of the first quantizer 1240 and the output of the second quantizer 1250 are binarized signal examples (i.e., either 1 or -1), the output of the adder 1262 is also a binarized signal example. The quantization of the signal is not impaired by the processing of the upconverter 1260. This modification may include such processing.

The above configuration has the following effects. The fourth signal (output of the first NN 300) is fed back to the first loop filter 1220 and the second loop filter 1230 via the downconverter 1210. This allows the delta-sigma modulation unit 111 to perform noise shaping, passing the signal component of the target frequency f0 and shifting noise near the frequency f0 out of band.

In addition, the second adder 1221b may be omitted in the first loop filter 1220. In this case, the output of the transfer function processing unit 1222 is input to the first quantizer 1240. The transfer function in the transfer function processing unit 1222 is set so that the output of the transfer function processing unit 1222 includes the first I signal and the above-mentioned first component.

In the second loop filter 1230, the second adder 1231b may be omitted. In this case, the output of the transfer function processing unit 1232 is input to the second quantizer 1250. The transfer function in the transfer function processing unit 1232 is set so that the output of the transfer function processing unit 1232 includes the first Q signal and the above-mentioned second component.

(2) Second Modification The first NN 300 may be configured to output an approximation of a signal generated through a portion of the transmission path 120. As an example, the first NN 300 outputs an approximation of a signal generated through a process in which the second signal passes through the communication path 130. With this configuration, at least a portion of the transmission distortion occurring in the transmission path 120 can be suppressed.

(3) Third Modification The first NN 300 is not limited to the above example. FIG. 13 is a diagram showing an example of the configuration of the first NN 300.

The input layer 310 may include nodes 310c and 310d to which the result of a logical operation of two nodes in the input layer 310 is input. For example, the logical operation may include logical AND and exclusive OR (XOR). The input layer 310 may include a node to which a logical operation between a first result of the logical operation of the two nodes and a second result of the logical operation of the two nodes is input. That is, the input layer 310 may include a node to which the result of a logical operation of two or more nodes in the input layer 310 is input.

The above configuration has the following effects. The first NN 300 can efficiently generate nonlinear distortion such as intersymbol interference that occurs in the process in which the second signal passes through the transmission path 120. The accuracy of the fourth signal output by the first NN 300 is improved.

14 is a diagram showing an example of the configuration of the first NN 300. The node 310a may have an output line (connection line) through which the current value of the second signal is output to the output layer 330 without passing through the intermediate layer 320.

The above configuration has the following effects. Since the current value of the second signal does not pass through the intermediate layer 320, no weight is applied to the current value of the second signal. The first NN 300 can efficiently reflect the residual with the current input value in the fourth signal. The accuracy of the fourth signal output by the first NN 300 is improved.

The first NN 300 may be a combination of the above-mentioned configurations. The input layer 310 includes at least a node to which the current value of the second signal is input. The input layer 310 may further include at least one of a node to which a past value of the second signal is input, a node to which the result of a logical operation of two or more nodes in the input layer 310 is input, and a node having an output line through which the current value of the second signal is output to the output layer 330 without passing through the intermediate layer 320. Furthermore, the first NN 300 may include various known structures.

(4) Fourth Modification The process flow of the delta-sigma modulation device 110 is not limited to the above-mentioned example. Fig. 15 is a flowchart showing an example of the process flow of the delta-sigma modulation device 110. The flowchart in Fig. 15 is a flowchart in which step 1501 is added to the flowchart in Fig. 7.

After step 701, the NN learning unit 113 determines whether a predetermined first condition is satisfied (1501). If the first condition is satisfied, the delta-sigma modulation device 110 executes the process of step 702 and the process of step 703. Thus, the first parameter of the first NN 300 and the second parameter of the second NN 600 are updated.

If the first condition is not satisfied, the delta-sigma modulation device 110 does not execute the process of step 702 and the process of step 703. That is, the first parameter of the first NN 300 and the second parameter of the second NN 600 are not updated.

The first condition is a condition that the approximation error is greater than a predetermined first magnitude. Specifically, when the approximation error is the greater of the absolute value of the first difference and the absolute value of the second difference, the first condition may be a condition that the approximation error is greater than a predetermined first threshold Th1. When the approximation error is expressed by a complex number, the first condition may be a condition regarding the absolute value of the complex number (i.e., the distance from the origin on the complex plane). The first condition may be a condition that the absolute value of the approximation error (the distance from the origin) is greater than a predetermined first distance threshold. In another example, the first condition may include a condition for the first difference and a condition for the second difference. For example, when the absolute value of the first difference exceeds a predetermined first real component threshold and/or the absolute value of the second difference exceeds a predetermined first imaginary component threshold, the NN learning unit 113 may determine that the first condition is satisfied.

The state of the transmission path 120 changes from moment to moment. By using the first condition as described above, the delta-sigma modulation device 110 can update the first parameter of the first NN 300 and the second parameter of the second NN 600 according to the current state of the transmission path 120.

As described above, if the approximation error is large, this means that the output of the transmission model 410 (the approximation of the third signal) is far from the actual third signal. That is, this means that the accuracy of the output of the transmission model 410 is low, and the accuracy of the fourth signal output by the first NN 300 is also low. Therefore, there is a high need to reflect the current state of the transmission path 120 (especially information on the transmission distortion) in the first NN 300 and the second NN 600. Therefore, when the first condition is satisfied, the NN learning unit 113 judges "Yes" in step 1501. Then, the delta-sigma modulation device 110 executes the process of step 702 and the process of step 703.

On the other hand, if the approximation error is small, this means that the output of the transmission model 410 is close to the actual third signal. Therefore, there is little need to update the first parameter of the first NN 300 and the second parameter of the second NN 600. Therefore, the NN learning unit 113 judges "No" in step 1501. Then, the delta-sigma modulation device 110 proceeds to step 704.

The above configuration has the following effects. The delta-sigma modulation device 110 executes the processes of steps 702 and 703 only when there is a high need to reflect the current state of the transmission path 120 in the first NN 300 and the second NN 600. Since the delta-sigma modulation device 110 does not execute the processes of steps 702 and 703 in unnecessary situations, the processing load on the delta-sigma modulation device 110 can be reduced.

After the first condition is satisfied, the delta-sigma modulation device 110 may repeatedly execute the processes of steps 702 and 703 until a predetermined second condition is satisfied. Specifically, the parameter calculation unit 430 continues the process of calculating the first parameter and the second parameter until the second condition is satisfied. The parameter calculation unit 430 continues the process of updating the second parameter of the second NN 600 until the second condition is satisfied. The NN processing unit 112 continues the process of updating the first parameter of the first NN 300 until the second condition is satisfied.

The second condition is a condition that the approximation error is smaller than a predetermined second magnitude. The second magnitude is smaller than the above-mentioned first magnitude. Specifically, when the approximation error is the larger of the absolute value of the first difference and the absolute value of the second difference, the second condition may be a condition that the approximation error is smaller than a predetermined second threshold Th2. The second threshold Th2 is smaller than the first threshold Th1. When the approximation error is expressed by a complex number, the second condition may be a condition regarding the absolute value of the complex number (i.e., the distance from the origin on the complex plane). The second condition may be a condition that the absolute value of the approximation error (the distance from the origin) is smaller than a predetermined second distance threshold. The second distance threshold is smaller than the first distance threshold. In another example, the second condition may include a condition for the first difference and a condition for the second difference. For example, when the absolute value of the first difference is below a predetermined second real component threshold and/or the absolute value of the second difference is below a predetermined second imaginary component threshold, the NN learning unit 113 may determine that the second condition is satisfied. For example, the second real component threshold is smaller than the first real component threshold. The second imaginary component threshold is smaller than the first imaginary component threshold.

(5) Fifth Modification The configuration of the NN learning unit 113 is not limited to the above example. Fig. 16 is a diagram showing an example of the configuration of the NN learning unit 113.

The NN learning unit 113 further includes a delay adjustment unit 1610 and a gain adjustment unit 1620.

The delay adjustment unit 1610 receives the second signal as an input signal. The delay adjustment unit 1610 delays the second signal so that the timing at which the output of the transmission model 410 is input to the error calculation unit 420 is synchronized with the timing at which the third signal is input to the error calculation unit 420.

The gain adjustment unit 1620 receives the third signal as an input signal. The gain adjustment unit 1620 multiplies the third signal by a gain. Specifically, the gain adjustment unit 1620 regards the third signal as a complex number and multiplies each of the I signal and the Q signal included in the third signal by a complex gain.

The delay value in the delay adjustment unit 1610 and the complex gain in the gain adjustment unit 1620 are set so that the approximation error, which is the output of the error calculation unit 420, is minimized.

(6) Sixth Modification The modulator 144 may down-convert the output of the amplifier 143 by a superheterodyne system and output an IF signal.

(7) Seventh Modification The modulation unit 144 in the transmission path 120 may be omitted. In this configuration, the digital down-converter 620 in the transmission model 410 is omitted. The error calculation unit 420 calculates an approximation error between the output of the transmission model 410 and a third signal (in this example, the output of the amplifier 143).

(8) Eighth Modification The configuration of the transmission model 410 is not limited to the above example. The configuration of the transmission model 410 may be appropriately changed according to the configuration of the delta-sigma modulation device 110 and the configuration of the transmission path 120. For example, a commonly used digital distortion compensation technique may be applied to the first signal (I signal and Q signal). The configuration of the transmission model 410 may be changed accordingly.

The second NN 600 may be a neural network that models the entire transmission path 120.

If the modulation unit 144 has a configuration that downconverts the output of the amplifier 143 using a superheterodyne method, the transmission model 410 may include a corresponding component. The transmission model 410 may include a component that outputs an IF signal from the output of the digital filter 610 using a superheterodyne method.

Amplifier 143 may not be modeled as a second NN 600, but may be modeled separately. In another example, modeling of amplifier 143 may be omitted.

The second NN 600 may be a component that models a part of the transmission path 120. For example, the second NN 600 may be a neural network that outputs the same signal (fourth signal) as the first NN 300. That is, the second NN 600 may output an approximation of a signal generated by the second signal passing through the communication path 130, the BPF 142, and the amplifier 143.

The second NN 600 may have the same structure as the first NN 300. The second NN 600 includes an input layer, at least one hidden layer, and an output layer. The input layer includes at least a node to which the current value of the second signal is input. The input layer may further include at least one of a node to which a past value of the second signal is input, a node to which a result of a logical operation of two or more nodes in the input layer is input, and a node having an output line through which the current value of the second signal is output to the output layer without passing through the hidden layer.

<<3. Second embodiment>>
Next, a second embodiment and its modified examples will be described with reference to Fig. 17 to Fig. 24. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description of those components will be omitted.

<3-1. General configuration of wireless communication device>
17 is a diagram showing the configuration of a wireless communication device 1700. The wireless communication device 1700 includes a first device 810 and a second device 820.

The first communication path 131 includes an optical fiber 131a. The first communication path 131 includes an E/O conversion unit 131b at the end of the optical fiber 131a on the side of the second device 820. The E/O conversion unit 131b converts an electrical signal into an optical signal. Furthermore, the first communication path 131 includes an O/E conversion unit 131c at the end of the optical fiber 131a on the side of the first device 810. The O/E conversion unit 131c converts the optical signal into an electrical signal.

The second communication path 132 includes an optical fiber 132a. The second communication path 132 includes an E/O conversion unit 132b at an end of the optical fiber 132a that faces the second device 820. Furthermore, the second communication path 132 includes an O/E conversion unit 132c at an end of the optical fiber 132a that faces the first device 810.

<3-2. Configuration of the first device>
The first device 810 includes an antenna 141, a BPF 142, an amplifier 143, a modulator 144, and an information transmitter 145. The information transmitter 145 transmits transmission-related information to the second device 820 via the second communication path 132. The transmission-related information in this example is a third signal (output of the modulator 144) as in the first embodiment.

<3-3. Configuration of the second device>
The second device 820 includes a delta-sigma modulation unit 111, an NN processing unit 112, an NN learning unit 113, and an instruction transmission unit 114. The delta-sigma modulation unit 111 transmits a second signal to the first device 810 via a first communication path 131. The instruction transmission unit 114 transmits instruction signals (an initial instruction signal, a first instruction signal, and a second instruction signal) described below to the first device 810 via the first communication path 131.

<3-4. Overview of Processing Flow of Wireless Communication Device>
Next, an overview of the process flow of the wireless communication device 1700 will be described. Specifically, the process flow of the first device 810 transmitting transmission-related information to the second device 820 will be described.

The instruction transmission unit 114 determines whether a condition regarding the amount of distortion that occurred during the transmission process of the second signal is satisfied. For example, the condition is the above-mentioned first condition regarding the approximation error. If the first condition is satisfied, the instruction transmission unit 114 transmits a first instruction signal to the first device 810.

In this example, the first instruction signal is a signal that instructs the first device 810 to transmit transmission-related information to the second device 820. The first instruction signal includes information about the number of times Nk that the first device 810 transmits the transmission-related information to the second device 820. Nk is an integer equal to or greater than 1. The information transmitting unit 145 transmits the transmission-related information to the second device 820 in response to the first instruction signal.

The instruction transmission unit 114 determines whether the above-mentioned second condition regarding the approximation error is satisfied. If the second condition is satisfied, the instruction transmission unit 114 transmits a second instruction signal to the first device 810.

In this example, the second instruction signal is a signal that instructs the first device 810 to stop transmitting the transmission-related information to the second device 820. The information transmitting unit 145 stops transmitting the transmission-related information in response to the second instruction signal.

<3-5. Processing flow of wireless communication device>
Next, a processing flow of wireless communication device 1700 will be described with reference to Fig. 18. Fig. 18 is a sequence diagram showing an example of a processing flow of wireless communication device 1700.

The instruction transmission unit 114 transmits an initial instruction signal to the first device 810 via the first communication path 131 (1801). The initial instruction signal is an instruction signal for causing the first device 810 to transmit the transmission-related information to the second device 820 only once.

The delta-sigma modulation unit 111 transmits the second signal to the first device 810 via the first communication path 131 (1802). The information transmission unit 145 transmits the transmission-related information (in this example, the third signal) to the second device 820 via the second communication path 132 (1803).

The second device 820 receives the transmission-related information. The second device 820 (i.e., the NN processing unit 112 and the NN learning unit 113) executes the processing of steps 702 and 703 in FIG. 7 (1804). Hereinafter, the series of processing of steps 702 and 703 is collectively referred to as the "learning processing." The NN learning unit 113 transmits the approximation error calculated in the processing of step 702 to the instruction transmission unit 114.

The instruction transmission unit 114 uses the approximation error to determine whether the first condition is satisfied. In this example, the instruction transmission unit 114 determines that the first condition is satisfied (1805). Therefore, the instruction transmission unit 114 transmits a first instruction signal to the first device 810 via the first communication path 131 (1806).

The delta-sigma modulation unit 111 transmits the second signal to the first device 810 via the first communication path 131 (1807).

In response to the first instruction signal, the information transmitting unit 145 transmits the transmission-related information to the second device 820 via the second communication path 132 (1808). This is the first transmission of the transmission-related information based on the time when the first device 810 received the first instruction signal.

The second device 820 executes a learning process (1809). Each time the second device 820 executes the learning process, the instruction sending unit 114 determines whether the second condition is satisfied.

The transmission of the second signal, the transmission-related information, and the learning process are repeated. This causes the approximation error to gradually decrease.

The delta-sigma modulation unit 111 then transmits the second signal to the first device 810 via the first communication path 131 (1810).

The information transmitting unit 145 transmits the transmission-related information to the second device 820 via the second communication path 132 (1811). This is the Nj-th transmission of the transmission-related information, based on the time when the first device 810 received the first instruction signal. Note that Nj<Nk.

The second device 820 executes a learning process (1812). The instruction sending unit 114 determines that the second condition is satisfied (1813). Therefore, the instruction sending unit 114 sends a second instruction signal to the first device 810 via the first communication path 131 (1814). In response to the second instruction signal, the information sending unit 145 stops sending the transmission-related information.

Thereafter, the instruction sending unit 114 sends an initial instruction signal to the first device 810 via the first communication path 131 every time a predetermined waiting time Tw elapses (1815).

Note that when the information transmitting unit 145 transmits the transmission-related information Nk times after the first device 810 receives the first instruction signal, the information transmitting unit 145 stops transmitting the transmission-related information. When a predetermined waiting time Tw has elapsed since the first device 810 received the transmission-related information Nk times, the instruction transmitting unit 114 transmits an initial instruction signal to the first device 810.

In another example, the second instruction signal may further include information on the waiting time Tw. In this configuration, the information transmitting unit 145 transmits the transmission-related information to the second device 820 each time the waiting time Tw elapses. The instruction transmitting unit 114 determines whether the first condition is satisfied each time the transmission-related information is received. If the first condition is satisfied, the instruction transmitting unit 114 transmits the first instruction signal to the first device 810.

The above configuration has the following effects. When the first condition is satisfied (i.e., when the approximation error is large), this means that the current state of the transmission path 120 (particularly, information on the transmission distortion) cannot be reflected in the first NN 300 and the second NN 600, and therefore the transmission distortion cannot be suppressed. In such a situation, the first device 810 feeds back the transmission-related information to the second device 820. The second device 820 can perform a learning process using the transmission-related information to update the first parameter of the first NN 300 and the second parameter of the second NN 600. This makes it possible to suppress the transmission distortion that occurs in the transmission process of the second signal. Furthermore, it is possible to realize a distributed MIMO (Multiple Input Multiple Output) system that increases the number of simultaneous connections and the transmission capacity.

<3-6. Modifications>
The technology according to the present disclosure is not limited to the above-described embodiments.

(1) First Modification The first indication signal is not limited to the above example. The first indication signal may include information about a period Tp during which the first device 810 transmits transmission-related information to the second device 820. In response to the first indication signal, the information transmitting unit 145 transmits the transmission-related information to the second device 820 every time the period Tp elapses.

The period Tp may be k1 times the learning period, where k1 is an integer equal to or greater than 1. The learning period is the period required from the time the second device 820 receives the transmission-related information until the second device 820 updates the first parameter of the first NN 300 and the second parameter of the second NN 600.

The period Tp may be defined by a frame, a subframe, or a slot defined in 3GPP. A frame is defined by multiple subframes. A subframe is defined by one or more slots. The period Tp may be defined as "k2 times a frame". Here, k2 is an integer equal to or greater than 1. As an example, one frame is 10 ms (milliseconds). The period Tp may be defined as "k3 times a subframe". Here, k3 is an integer equal to or greater than 1. As an example, one subframe is 1 ms. The period Tp may be defined as "k4 times a slot". Here, k4 is an integer equal to or greater than 1.

Figure 19 is a sequence diagram showing an example of the processing flow of the wireless communication device 1700.

The instruction transmission unit 114 transmits a first instruction signal to the first device 810 (1901). The delta-sigma modulation unit 111 transmits a second signal to the first device 810 (1902). The information transmission unit 145 transmits transmission-related information (in this example, the third signal) to the second device 820 (1903). The second device 820 executes a learning process (1904). Thereafter, the delta-sigma modulation unit 111 repeatedly transmits the second signal to the first device 810 (1905).

A period Tp has elapsed since the information transmitting unit 145 executed the process of step 1903. The information transmitting unit 145 transmits the transmission-related information to the second device 820 (1906). The second device 820 executes a learning process (1907). Thereafter, the information transmitting unit 145 transmits the transmission-related information to the second device 820 each time the period Tp elapses (1908).

The above configuration has the following effects. The first device 810 periodically feeds back transmission-related information to the second device 820. The second device 820 periodically executes a learning process using the transmission-related information to update the first parameter of the first NN 300 and the second parameter of the second NN 600. This makes it possible to suppress transmission distortion that occurs during the transmission process of the second signal.

(2) Second Modification When a condition related to transmission between the first device 810 and the second device 820 is satisfied, the information transmitting unit 145 may transmit the transmission-related information to the second device 820. For example, the information transmitting unit 145 may estimate the amount of distortion generated in the transmission process of the second signal based on the second signal. The information transmitting unit 145 determines whether or not a third condition related to the amount of distortion is satisfied. The third condition is that the amount of distortion is greater than a predetermined magnitude. When the third condition is satisfied, the information transmitting unit 145 transmits the transmission-related information to the second device 820.

The amount of distortion may be estimated as follows. The information transmission unit 145 performs Fourier transform processing or the like on the second signal to analyze the frequency components of the second signal. When the amount of distortion generated during the transmission process of the second signal is large, the frequency components of the second signal that are outside the desired frequency band described above (the band from f0-fα to f0+fα) are large. Taking this into consideration, the information transmission unit 145 calculates the signal power of the band outside the desired frequency band.

The third condition may be a condition that the signal power of the band outside the desired frequency band is greater than a third threshold value Th3. If the signal power of the band outside the desired frequency band is greater, the information transmission unit 145 may determine that the amount of distortion is greater than a predetermined magnitude.

The signal to be subjected to the Fourier transform process may be any of the signals 1701 to 1703 shown in FIG.
A signal 1701 after passing through the first communication path 131 and before passing through the BPF 142
Signal 1702 after passing through BPF 142 and before passing through amplifier 143
Signal 1703 after passing through amplifier 143

Figure 20 is a sequence diagram showing an example of the processing flow of the wireless communication device 1700.

The delta-sigma modulation unit 111 transmits the second signal to the first device 810 (2001). The information transmission unit 145 estimates the amount of distortion as described above and determines whether the third condition is satisfied (2002). In this example, the information transmission unit 135 determines that the third condition is satisfied (2003). Therefore, the information transmission unit 145 transmits the transmission-related information to the second device 820 (2004). The second device 820 executes a learning process (2005). Thereafter, the delta-sigma modulation unit 111 repeatedly transmits the second signal to the first device 810 (2006).

After that, a first time Ta elapses from the point when the information transmitting unit 145 executes the processing of step 2002. The information transmitting unit 145 estimates the amount of distortion as described above, and determines whether or not the third condition is satisfied (2007). In this manner, the information transmitting unit 145 estimates the amount of distortion each time the first time Ta elapses. If the third condition is satisfied, the information transmitting unit 145 transmits the transmission-related information to the second device 820. On the other hand, if the third condition is not satisfied, the information transmitting unit 145 does not transmit the transmission-related information to the second device 820.

The above configuration has the following effects. When the third condition is met (i.e., when the amount of distortion is relatively large), the first device 810 feeds back the transmission-related information to the second device 820. The first device 810 can feed back the transmission-related information to the second device 820 in an appropriate situation without a first instruction signal from the second device 820.

In another example, the information transmission unit 145 may estimate the amount of distortion each time the first device 810 receives the second signal.

(3) Third Modification The process shown in Fig. 18 may be combined with the process shown in Fig. 19. Fig. 21 is a sequence diagram showing an example of the flow of processing by wireless communication device 1700.

Steps 2101 to 2107 in Figure 21 are the same process as steps 1901 to 1907 in Figure 19. Therefore, detailed explanations of these steps are omitted. The information transmitting unit 145 transmits transmission-related information to the second device 820 each time the period Tp elapses in response to a first instruction signal (2101) including information about the period Tp.

Each time the second device 820 executes a learning process, the instruction sending unit 114 determines whether the first condition is met.

After the second device 820 executes the learning process in step 2107, the instruction sending unit 114 determines that the first condition is satisfied (2108). The instruction sending unit 114 sends a first instruction signal including information about the number of times Nk to the first device 810 (2109).

Steps 2110 to 2117 in Figure 21 are the same process as steps 1807 to 1814 in Figure 18. Therefore, detailed explanations of these steps will be omitted. Note that in steps 2110 to 2117, the time interval at which the first device 810 transmits transmission-related information to the second device 820 is smaller than the period Tp.

After the instruction transmission unit 114 transmits the second instruction signal in step 2117, the instruction transmission unit 114 transmits a first instruction signal including information about the period Tp to the first device 810. In response to this, the information transmission unit 145 transmits transmission-related information to the second device 820 each time the period Tp elapses.

The above configuration has the following effects. When the first condition is met (i.e., when the approximation error is large), the first device 810 feeds back the transmission-related information to the second device 820 in a relatively short period. The second device 820 can quickly reflect the current state of the transmission path 120 in the first NN 300 and the second NN 600. On the other hand, when the second condition is met (i.e., when the approximation error is small), there is little need to update the first parameter of the first NN 300 and the second parameter of the second NN 600. In such a situation, the first device 810 feeds back the transmission-related information to the second device 820 in a relatively long period Tp. The processing load in the second device 820 can be reduced.

(4) Fourth Modification The process shown in Fig. 18 may be combined with the process shown in Fig. 20. Fig. 22 is a sequence diagram showing an example of the flow of processing by the wireless communication device 1700.

Steps 2201 to 2205 in Figure 22 are the same process as steps 2001 to 2005 in Figure 20. Therefore, detailed explanations of these steps will be omitted.

Each time the second device 820 executes a learning process, the instruction sending unit 114 determines whether the first condition is met.

After the second device 820 executes the learning process in step 2205, the instruction sending unit 114 determines that the first condition is satisfied (2206). The instruction sending unit 114 sends a first instruction signal including information about the number of times Nk to the first device 810 (2207).

Steps 2208 to 2215 in FIG. 22 are the same process as steps 1807 to 1814 in FIG. 18. Therefore, detailed explanations of these steps will be omitted. In steps 2208 to 2215, each time the second device 820 transmits a second signal to the first device 810, the first device 810 transmits transmission-related information to the second device 820. Therefore, the time interval at which the first device 810 transmits the transmission-related information to the second device 820 is relatively short.

After the instruction transmission unit 114 transmits the second instruction signal in step 2215, the delta-sigma modulation unit 111 transmits the second signal to the first device 810 (2216). The information transmission unit 145 estimates the amount of distortion as described above and determines whether the third condition is satisfied (2217).

Each time the first device 810 receives the second signal, the information transmitting unit 145 estimates the amount of distortion and determines whether the third condition is satisfied. If the third condition is satisfied, the information transmitting unit 145 transmits the transmission-related information to the second device 820. In this case, as described above, the instruction transmitting unit 114 determines whether the first condition is satisfied.

On the other hand, if the third condition is not met, the information sending unit 145 does not send the transmission-related information to the second device 820.

The above configuration has the following effects. In the first stage, the first device 810 feeds back the transmission-related information to the second device 820 only when the third condition is satisfied (i.e., when the amount of distortion is relatively large). The second device 820 executes a learning process and determines whether the first condition is satisfied or not only when the first device 810 has fed back the transmission-related information. The processing load on the second device 820 can be reduced.

Next, in the second stage, when the first condition is satisfied (i.e., when the approximation error is large), the second device 820 instructs the first device 810 to feed back transmission-related information to the second device 820 at a relatively short period. In the second stage, the second device 820 can reflect the current state of the transmission path 120 (particularly, information on transmission distortion) to the first NN 300 and the second NN 600 at a relatively short period.

(5) Fifth Modification The first device 810 and the second device 820 may be connected by one communication path (e.g., one optical fiber). The second signal may be transmitted via the optical fiber, and the transmission-related information may be transmitted via the same optical fiber.

For example, the first device 810 and the second device 820 may be configured to communicate with each other using wavelength division multiplexing, a well-known technique for transmitting optical signals of different wavelengths over a single optical fiber.

The first device 810 and the second device 820 may be configured to communicate with each other using a polarization multiplexing communication method. Polarization multiplexing communication is a well-known technology that transmits horizontally polarized waves oscillating in the horizontal direction and vertically polarized waves oscillating in the vertical direction over a single optical fiber.

The first device 810 and the second device 820 may be configured to communicate with each other using a time-division multiplexing technique. Time-division multiplexing is a well-known technique for transmitting multiple signals sequentially over a single optical fiber such that the signals do not overlap on the time axis.

The optical fiber may be a multicore fiber having multiple cores. In this case, the first device 810 and the second device 820 may be configured to communicate with each other using a spatial multiplexing technique. Spatial multiplexing is a well-known technique that transmits a different signal for each core.

(6) Sixth Modification Fig. 23 is a diagram showing the configuration of a wireless communication device 2300. The wireless communication device 2300 includes a first device 810 and a second device 820. The wireless communication device 2300 has a configuration for outputting N types of signals, where N is an integer equal to or greater than 2.

Specifically, the first device 810 includes a plurality of antennas 141-1 to 141-N, a plurality of BPFs 142-1 to 142-N, and a plurality of amplifiers 143-1 to 143-N.

The second device 820 includes a plurality of delta-sigma modulation units 111-1 to 111-N. Furthermore, the first device 810 and the second device 820 are connected via a plurality of first communication paths 131-1 to 131-N. The plurality of delta-sigma modulation units 111-1 to 111-N are respectively connected to a plurality of antennas 141-1 to 141-N via a plurality of first communication paths 131-1 to 131-N. For example, the delta-sigma modulation unit 111-N is connected to the antenna 141-N via the first communication path 131-N, a BPF 142-N, and an amplifier 143-N.

The first device 810 includes a switch 146. The switch 146 can switch the signal to be output to the modulation unit 144. With this configuration, the first device 810 can feed back transmission-related information (the third signal in this example) to the second device 820 for each of the N types of second signals. This makes it possible to suppress transmission distortion that occurs in the transmission process of each of the N types of second signals.

(7) Seventh Modification Fig. 24 is a diagram showing the configuration of a wireless communication device 2400. The wireless communication device 2400 includes a first device 810 and a second device 820. The wireless communication device 2400 includes a transmission function and a reception function.

Hereinafter, the link through which a signal is transmitted from the second device 820 via the first device 810 to the terminal device 190 may be referred to as the "downlink." A signal transmitted on the downlink may be referred to as the "downlink signal."

On the other hand, the link in which a signal is transmitted from the terminal device 190 via the first device 810 to the second device 820 may be referred to as the "uplink." A signal transmitted on the uplink may be referred to as an "uplink signal."

The second device 820 transmits a downlink signal to the first device 810 via the first communication path 131. The first device 810 transmits an uplink signal to the second device 820 via the second communication path 132.

The first device 810 includes an antenna switch 147. The antenna switch 147 includes a first terminal 147a connected to the amplifier 143, a second terminal 147b connected to the antenna 141, and a third terminal 147c connected to a low noise amplifier (LNA) 148.

The antenna switch 147 can operate in three modes: transmit mode, receive mode, and feedback mode.

In the transmission mode, the first terminal 147a and the second terminal 147b are connected. Therefore, the downlink signal is output from the antenna 141.

In the reception mode, the second terminal 147b and the third terminal 147c are connected. Thus, the uplink signal is transmitted to the second device 820 via the LNA 148, the modulation unit 144, the information transmission unit 145, and the second communication path 132. The second device 820 performs a predetermined process on the uplink signal using a reception function not shown.

In the feedback mode, the first terminal 147a and the third terminal 147c are connected. Thus, the downlink signal is sent to the information transmitting unit 145 via the LNA 148 and the modulation unit 144. The information transmitting unit 145 transmits the transmission-related information to the second device 820 via the second communication path 132 at a predetermined timing. The transmission-related information in this example is information about the downlink signal to be transmitted from the first device 810 to the terminal device 190. Specifically, the transmission-related information is a signal (i.e., a third signal) obtained by frequency converting (down-converting) the downlink signal through the modulation unit 144.

In such a configuration, the wireless communication device 2400 may transmit downlink signals and receive uplink signals using a Time Division Duplex (TDD) method. TDD is a method of alternately transmitting uplink signals and downlink signals in different slots. The above slots are sometimes referred to as "time slots."

When the wireless communication device 2400 operates in the TDD mode, the instruction transmission unit 114 operates as follows. In the case of an uplink slot, the second communication path 132 is used for transmitting an uplink signal, but the first communication path 131 is not used. Therefore, the instruction transmission unit 114 transmits a first instruction signal to the first device 810 via the first communication path 131 in the uplink slot. The instruction transmission unit 114 transmits a second instruction signal to the first device 810 via the first communication path 131 in the uplink slot.

Furthermore, the information transmitting unit 145 operates as follows: In the case of a downlink slot, the first communication path 131 is used for transmitting a downlink signal, but the second communication path 132 is not used. Therefore, the information transmitting unit 145 transmits transmission-related information to the second device 820 via the second communication path 132 in the downlink slot.

<<4. Third embodiment>>
Next, a third embodiment will be described with reference to Fig. 25. In the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and detailed description of these components will be omitted.

<4-1. General configuration of wireless communication device>
25 is a diagram showing a configuration of a wireless communication device 2500. The wireless communication device 2500 includes a first device 810 and a second device 820. The first device 810 and the second device 820 are connected via a first communication path 131.

<4-2. Configuration of the first device>
The first device 810 includes an antenna 141, a BPF 142, an amplifier 143, an antenna 150, a frequency conversion unit 151, a second modulation unit 152, and a third modulation unit 153. The third modulation unit 153 has the same configuration as the modulation unit 144. The third modulation unit 153 processes the analog signal (corresponding to the downlink signal) amplified by the amplifier 143 as described above, and outputs a third signal (including an I signal and a Q signal).

The second modulation unit 152 receives the output of the third modulation unit 153. The second modulation unit 152 performs signal modulation processing on the output of the third modulation unit 153. A general modulation method may be used as the signal modulation processing. For example, single carrier modulation or OFDM (Orthogonal Frequency Division Multiplexing) may be used as the signal modulation processing. The frequency conversion unit 151 receives the output of the second modulation unit 152. The frequency conversion unit 151 upconverts the output of the second modulation unit 152. In this case, the frequency conversion unit 151 upconverts the output of the second modulation unit 152 to a frequency f1 different from the frequency f0. The output of the frequency conversion unit 151 is transmitted via the antenna 150.

<4-3. Configuration of the second device>
The second device 820 includes a delta-sigma modulation unit 111, an NN processing unit 112, an NN learning unit 113, an antenna 115, a demodulation unit 117, and a modulation unit 144. The second device 820 receives a signal output from an antenna 150 of the first device 810 via the antenna 115. The modulation unit 144 processes the received signal as described above. The demodulation unit 117 demodulates the output of the modulation unit 144. The demodulation method of the demodulation unit 117 corresponds to the modulation method of the second modulation unit 152. The demodulation unit 117 outputs the demodulated third signal (including an I signal and a Q signal) to the NN learning unit 113.

The above configuration has the following effects. The first device 810 can feed back transmission-related information to the second device 820 via spatial transmission. The transmission-related information in this example is information regarding a downlink signal to be transmitted from the first device 810 to the terminal device 190. Therefore, the second device 820 can update the first parameter of the first NN 300 and the second parameter of the second NN 600 using the transmission-related information. This makes it possible to suppress transmission distortion that occurs during the transmission process of the second signal.

<<5. Fourth embodiment>>
Next, a fourth embodiment and its modified examples will be described with reference to Fig. 26 to Fig. 32. Note that in the fourth embodiment, the same components as those in the first to third embodiments are denoted by the same reference numerals, and detailed description of those components will be omitted.

<5-1. General configuration of wireless communication device>
26 is a diagram showing a configuration of a wireless communication device 2600. The wireless communication device 2600 includes a first device 810 and a second device 820. The first device 810 and the second device 820 are connected via a first communication path 131. Furthermore, the first device 810 and the second device 820 are connected via a second communication path 132.

<5-2. Configuration of the first device>
The first device 810 includes an antenna 141 , a BPF 142 , an amplifier 143 , a modulation unit 144 , an information transmission unit 145 , a digital restoration unit 149 , and a NN learning unit 113 .

The digital restoration unit 149 receives the output of the first communication path 131. The digital restoration unit 149 converts the output of the first communication path 131 into a 1-bit digital signal. At this time, the transmission distortion contained in the output of the first communication path 131 is shaped and a digital signal is output. This restores the original second signal output by the delta-sigma modulation unit 111. In this way, the digital restoration unit 149 generates a restored signal of the second signal from the third signal (in this example, a signal generated through a process in which the second signal passes through the first communication path 131). Hereinafter, such a restored signal of the second signal may be referred to as a "fifth signal".

The NN learning unit 113 calculates the first parameter of the first NN 300 and the second parameter of the second NN 600 using the fifth signal (the restored second signal) and the third signal output by the modulation unit 144 (i.e., the third signal generated by the process in which the second signal passes through the first communication path 131, the BPF 142, the amplifier 143, and the modulation unit 144). The NN learning unit 113 updates the second parameter of the second NN 600 to the calculated second parameter. Furthermore, the NN learning unit 113 outputs the calculated first parameter to the information transmission unit 145. The information transmission unit 145 transmits the first parameter to the second device 820 via the second communication path 132. Therefore, the transmission-related information in this example is the first parameter. The first parameter is information used to output an approximation of a signal generated in the transmission process of the second signal in the first NN 300. Therefore, the first parameter is information about the transmission between the first device 810 and the second device 820. In other words, since the first parameter is also used to output an approximation of the transmission distortion occurring in the transmission process of the second signal, it can also be said that the first parameter is information about the transmission distortion.

<5-3. Configuration of the second device>
The second device 820 includes a delta-sigma modulation unit 111, a NN processing unit 112, and an instruction transmission unit 114. The delta-sigma modulation unit 111 transmits a second signal to the first device 810 via the first communication path 131. The instruction transmission unit 114 transmits a first instruction signal to the first device 810 via the first communication path 131. The instruction transmission unit 114 transmits the second instruction signal to the first device 810 via the first communication path 131. The NN processing unit 112 receives a first parameter via the second communication path 132. The NN processing unit 112 updates the first parameter of the first NN 300 to the received first parameter.

<5-4. Processing flow of wireless communication device>
Next, a processing flow of the wireless communication device 2600 will be described with reference to Fig. 27. Fig. 27 is a sequence diagram showing an example of a processing flow of the wireless communication device 2600.

When the wireless communication device 2600 is started (or the wireless communication device 2600 is reset), the instruction transmission unit 114 transmits a first instruction signal to the first device 810 (2701). In this example, the first instruction signal includes information about the number of times Nk.

The delta-sigma modulation unit 111 transmits the second signal to the first device 810 (2702). The NN learning unit 113 calculates the first parameter and the second parameter (2703). The NN learning unit 113 updates the second parameter of the second NN 600 to the calculated second parameter.

The information transmitting unit 145 transmits the transmission-related information (in this example, the first parameter) to the second device 820 (2704). This is the first transmission of the transmission-related information based on the time when the first device 810 received the first instruction signal. The second device 820 receives the transmission-related information. The NN processing unit 112 updates the first parameter of the first NN 300 to the received first parameter.

In addition, each time the NN learning unit 113 calculates the first parameter and the second parameter, the information transmission unit 145 determines whether the second condition is satisfied or not.

Thereafter, the transmission of the second signal, the calculation of the first and second parameters, and the transmission of the transmission-related information are repeatedly performed. This causes the approximation error to gradually decrease.

The delta-sigma modulation unit 111 transmits the second signal to the first device 810 (2705). The NN learning unit 113 calculates the first parameter and the second parameter (2706).

The information transmitting unit 145 transmits the transmission-related information to the second device 820 (2707). This is the Nj-th transmission of the transmission-related information, based on the time when the first device 810 received the first instruction signal. Note that Nj<Nk.

At this point, the information transmitting unit 145 determines that the second condition is met (2708). The information transmitting unit 145 transmits a notification to the second device 820 (2709). This notification is for informing the second device 820 that the second condition is met. In response to this notification, the instruction transmitting unit 114 transmits a second instruction signal to the first device 810 (2710). This causes the information transmitting unit 145 to stop transmitting the transmission-related information.

Then, after the waiting time Tw has elapsed, the instruction sending unit 114 sends a first instruction signal including information about the number Nk to the first device 810 (2711).

The above configuration has the following effects. The first device 810 repeatedly feeds back the transmission-related information (first parameter) to the second device 820 until the second condition is met. The second device 820 can update the first parameter of the first NN 300 using the transmission-related information. This makes it possible to suppress transmission distortion that occurs in the transmission process of the second signal. Furthermore, it is possible to realize a distributed MIMO system that increases the number of simultaneous connections and transmission capacity.

<5-5. Modified Examples>
The technology according to the present disclosure is not limited to the above-described embodiments.

(1) First Modification FIG. 28 is a sequence diagram showing an example of a processing flow of the wireless communication device 2600.

When the wireless communication device 2600 is started (or the wireless communication device 2600 is reset), the instruction transmission unit 114 transmits a first instruction signal to the first device 810 (2801). The first signal includes information about the period Tp. The period Tp may be defined by the learning period, as described above. Furthermore, the period Tp may be defined by a frame, a subframe, or a slot, as described above.

The delta-sigma modulation unit 111 transmits the second signal to the first device 810 (2802). The NN learning unit 113 calculates the first parameter and the second parameter (2803). The NN learning unit 113 updates the second parameter of the second NN 600 to the calculated second parameter.

The information transmitting unit 145 transmits the transmission-related information (in this example, the first parameter) to the second device 820 (2804). The second device 820 receives the transmission-related information. The NN processing unit 112 updates the first parameter of the first NN 300 to the received first parameter.

The delta-sigma modulation unit 111 then repeatedly transmits the second signal to the first device 810 (2805).

A period Tp has elapsed since the NN learning unit 113 executed the process of step 2803. The NN learning unit 113 calculates the first parameter and the second parameter (2806). The information transmission unit 145 transmits the transmission-related information to the second device 820 (2807).

The above configuration has the following effects. The first device 810 periodically feeds back transmission-related information (first parameters) to the second device 820. The second device 820 can periodically update the first parameters of the first NN 300 using the transmission-related information.

In addition, each time the first device 810 receives the second signal, the NN learning unit 113 may calculate the first parameter and the second parameter. The information transmitting unit 145 may transmit the transmission-related information to the second device 820 each time the period Tp elapses.

(2) Second Modification FIG. 29 is a sequence diagram showing an example of a processing flow of the wireless communication device 2600.

When the wireless communication device 2600 is started (or the wireless communication device 2600 is reset), the delta-sigma modulation unit 111 transmits a second signal to the first device 810 (2901). The NN learning unit 113 calculates a first parameter and a second parameter (2902). The NN learning unit 113 outputs an approximation error to the information transmission unit 145. The information transmission unit 145 uses the approximation error to determine whether or not the first condition is satisfied. In this example, the information transmission unit 145 determines that the first condition is satisfied (2903). In this case, the information transmission unit 145 transmits transmission-related information (in this example, the first parameter) to the second device 820 (2904).

After that, the delta-sigma modulation unit 111 repeatedly transmits the second signal to the first device 810 (2905). The NN learning unit 113 calculates the first parameter and the second parameter (2906). Then, each time the NN learning unit 113 calculates the first parameter and the second parameter, the information transmission unit 145 determines whether or not the first condition is satisfied. If the first condition is satisfied, the information transmission unit 145 transmits the transmission-related information to the second device 820. On the other hand, if the first condition is not satisfied, the information transmission unit 145 does not transmit the transmission-related information to the second device 820.

The above configuration has the following effects: When the first condition is met (i.e., when the approximation error is large), the first device 810 can transmit transmission-related information (first parameters) to the second device 820.

(3) Third Modification The process shown in Fig. 27 may be combined with the process shown in Fig. 28. Fig. 30 is a sequence diagram showing an example of the flow of processing by the wireless communication device 2600.

Steps 3001 to 3009 in Figure 30 are the same process as steps 2701 to 2709 in Figure 27. Therefore, detailed explanations of these steps will be omitted. Note that in steps 3001 to 3009, the time interval at which the first device 810 transmits transmission-related information to the second device 820 is smaller than the period Tp.

When the instruction transmission unit 114 receives the notification in step 3009, the instruction transmission unit 114 transmits a first instruction signal including the period Tp to the first device 810 (3010). Steps 3011 to 3016 in FIG. 30 are the same process as steps 2802 to 2807 in FIG. 28. Therefore, detailed descriptions of these steps are omitted.

The above configuration has the following effects. The first device 810 first transmits transmission-related information (first parameters) to the second device 820 at a relatively short period. The second device 820 can quickly reflect the state of the transmission path 120 in the first NN 300. On the other hand, when the second condition is satisfied (i.e., when the approximation error is small), there is little need to update the first parameters of the first NN 300. In such a situation, the first device 810 feeds back the transmission-related information to the second device 820 at a relatively long period Tp.

Note that the process shown in FIG. 29 may be combined with the sequence in FIG. 30. For example, the information transmitting unit 145 may determine whether or not the first condition is satisfied in the middle of the period Tp (i.e., between steps 3012 and 3015). If the first condition is satisfied, the information transmitting unit 145 transmits the transmission-related information to the second device 820. On the other hand, if the first condition is not satisfied, the information transmitting unit 145 does not transmit the transmission-related information to the second device 820. According to this configuration, even in the middle of the period Tp, if the approximation error becomes large, the first device 810 can feed back the transmission-related information to the second device 820.

(4) Fourth Modification The wireless communication device 2600 may have the configuration of the seventh modification of the second embodiment. That is, the wireless communication device 2600 may operate in a TDD mode. In this configuration, the instruction transmission unit 114 operates as follows. The instruction transmission unit 114 transmits a first instruction signal to the first device 810 via the first communication path 131 in an uplink slot. The instruction transmission unit 114 transmits a second instruction signal to the first device 810 via the first communication path 131 in an uplink slot.

Furthermore, the information transmitting unit 145 operates as follows: The information transmitting unit 145 transmits transmission-related information to the second device 820 via the second communication path 132 in a downlink slot.

(5) Fifth Modification Fig. 31 is a diagram showing the configuration of a wireless communication device 2601. The components of the wireless communication device 2601 are the same as the components of the wireless communication device 2600 in Fig. 26.

The output of the first communication path 131 is directly input to the digital restoration unit 149. The fifth signal (the restored second signal) output by the digital restoration unit 149 is input to the BPF 142. The fifth signal passes through the BPF 142, the amplifier 143 and the modulation unit 144 and is input to the NN learning unit 113. Therefore, the NN learning unit 113 calculates the first parameter and the second parameter using the "fifth signal" and the "third signal generated through the process of the fifth signal passing through the BPF 142, the amplifier 143 and the modulation unit 144."

In addition, the first device 810 and the second device 820 in this example may operate according to any of the sequences shown in Figures 27 to 30.

32 is a diagram showing the configuration of a wireless communication device 3100. The wireless communication device 3100 includes a first device 810 and a second device 820. The first device 810 and the second device 820 are connected via a first communication path 131.

The first device 810 comprises an antenna 141, a BPF 142, an amplifier 143, a modulation unit 144, an information transmission unit 145, a digital restoration unit 149, an NN learning unit 113, an antenna 150, a frequency conversion unit 151, and a second modulation unit 152.

The second device 820 includes a delta-sigma modulation unit 111, an NN processing unit 112, an instruction transmission unit 114, an antenna 115, a modulation unit 116, and a demodulation unit 117.

In this example, the first device 810 transmits transmission-related information (first parameters) to the second device 820 via the antenna 150. The second device 820 receives the transmission-related information via the antenna 115. The operation of the first device 810 and the operation of the second device 820 will be described below.

The second modulation unit 152 receives the output (first parameter) of the NN learning unit 113. The second modulation unit 152 performs signal modulation processing on the output of the NN learning unit 113. A general modulation method may be used as the signal modulation processing. For example, single carrier modulation or OFDM may be used as the signal modulation processing. The frequency conversion unit 151 receives the output of the second modulation unit 152. The frequency conversion unit 151 upconverts the output of the second modulation unit 152. In this case, the frequency conversion unit 151 upconverts the output of the second modulation unit 152 to a frequency f1 different from the frequency f0. The information transmission unit 145 receives the output of the frequency conversion unit 151. The information transmission unit 145 transmits transmission-related information via the antenna 150. The transmission-related information in this example is the output of the frequency conversion unit 151 and is the first parameter.

The second device 820 receives the signal output from the antenna 150 via the antenna 115. The modulation unit 116 down-converts the received signal and outputs an I signal and a Q signal. The demodulation unit 117 demodulates the I signal and the Q signal to the original digital value (first parameter). The demodulation method of the demodulation unit 117 corresponds to the modulation method of the second modulation unit 152.

The demodulation unit 117 outputs the first parameter to the NN processing unit 112. The NN processing unit 112 receives the first parameter. The NN processing unit 112 updates the first parameter of the first NN 300 to the received first parameter.

In addition, the first device 810 and the second device 820 may operate according to any of the sequences shown in Figures 27 to 30.

<<6. Fifth embodiment>>
Next, a fifth embodiment will be described with reference to Figures 33 to 37. The above-described first to fourth embodiments are specific embodiments, but the fifth embodiment is a more generalized embodiment.

<6-1. Configuration of wireless communication device>
33 is a diagram showing the configuration of a wireless communication device 3200. The wireless communication device 3200 includes a first radio access network device 3210 and a second radio access network device 3220. Hereinafter, the first radio access network device 3210 will be referred to as the "first device 3210," and the second radio access network device 3220 will be referred to as the "second device 3220."

The first device 3210 is a device that performs processing related to a first physical layer. The second device 3220 is a device that performs processing related to a second physical layer that is higher than the first physical layer.

Figure 34 is a diagram showing the configuration of the first device 3210. The first device 3210 includes an acquisition unit 3211 and a transmission unit 3212. The acquisition unit 3211 acquires information related to the transmission between the first device 3210 and the second device 3220. Hereinafter, the information related to the transmission between the first device 3210 and the second device 3220 is simply referred to as "transmission-related information". The transmission unit 3212 transmits the transmission-related information to the second device 3220.

The components 3211-3212 of the first device 3210 may be implemented by one or more processors and a memory. The one or more processors may include, for example, one or more of a CPU, an MPU, and a microcontroller. The memory may include a volatile memory and a non-volatile memory. The memory may store program code (instructions). The one or more processors may realize the functions of the first device 3210 by executing the program code stored in the memory.

In addition, the first device 3210 may operate in the same manner as the first device 810 described above.

Figure 35 is a diagram showing the configuration of the second device 3220. The second device 3220 includes a receiving unit 3221 and a processing unit 3222. The receiving unit 3221 receives transmission-related information from the first device 3210. The processing unit 3222 uses the transmission-related information to perform processing related to communication with the first device 3210.

The components 3221-3222 of the second device 3220 may be implemented by one or more processors and a memory. The one or more processors may include, for example, one or more of a CPU, an MPU, and a microcontroller. The memory may include a volatile memory and a non-volatile memory. The memory may store program code (instructions). The one or more processors may realize the functions of the second device 3220 by executing the program code stored in the memory.

In addition, the second device 3220 may operate in the same manner as the second device 820 described above.

<6-2. Processing flow of wireless communication device>
36 is a flowchart showing the flow of processing of the first device 3210. The acquisition unit 3211 acquires transmission related information (3501). The transmission unit 3212 transmits the transmission related information to the second device 3220 (3502).

Figure 37 is a flowchart showing the flow of processing of the second device 3220. The receiving unit 3221 receives transmission-related information from the first device 3210 (3601). The processing unit 3222 uses the transmission-related information to perform processing related to communication with the first device 3210 (3602).

According to the above configuration, transmission between the first device 3210 and the second device 3220 can be improved by exchanging transmission-related information between the first device 3210 and the second device 3220.

<6-3. Modified Examples>
The technology according to the present disclosure is not limited to the above-described embodiments.

The transmission-related information may be information generated during the transmission process of a signal transmitted from the second device 3220 to the first device 3210.

The first device 3210 may be configured to transmit the signal transmitted from the second device 3220 to the first device 3210 as a downlink signal to a terminal device (not shown). In this configuration, for example, the transmission-related information may be information regarding the downlink signal to be transmitted from the first device 3210 to the terminal device. The transmission-related information may be a signal obtained by frequency-converting the above-mentioned downlink signal.

The transmission-related information may include information regarding distortion that occurred during the transmission process of the signal transmitted from the second device 3220 to the first device 3210.

The transmission-related information may be parameters of a neural network that outputs an approximation of a signal generated through at least a part of a transmission process of a signal transmitted from the second device 3220 to the first device 3210. For example, the transmission-related information may be parameters of the first NN 300 in the above-described embodiment.

The transmitting unit 3212 may control the transmission of the transmission-related information in response to an instruction signal transmitted from the second device 3220. For example, the instruction signal may include the first instruction signal and the second instruction signal in the above-described embodiment.

The transmitting unit 3212 may transmit the transmission-related information to the second device 3220 when a predetermined condition related to the transmission between the first device 3210 and the second device 3220 is satisfied. The predetermined condition may be a condition related to the amount of distortion generated in the transmission process of the signal transmitted from the second device 3220 to the first device 3210. The above-mentioned predetermined condition may be the first condition in the above-mentioned embodiment. The predetermined condition may be the third condition in the above-mentioned embodiment.

The first device 3210 and the second device 3220 may be configured to operate in a TDD mode. In this case, the transmitter 3212 may transmit transmission-related information to the second device 3220 in a downlink slot.

The second device 3220 may further include a transmitting unit that transmits an instruction signal regarding the transmission of the transmission-related information to the first device 3210. For example, the instruction signal may include the first instruction signal and the second instruction signal in the above-mentioned embodiment.

The transmitting unit of the second device 3220 may transmit an instruction signal to the first device 3210 when a predetermined condition regarding transmission between the first device 3210 and the second device 3220 is satisfied. The above-mentioned predetermined condition may include the first condition and the second condition in the above-mentioned embodiment.

The first device 3210 and the second device 3220 may be configured to operate in a TDD mode. In this case, the transmitter of the second device 3220 may transmit an instruction signal to the first device 3210 in an uplink slot.

The process related to the communication with the first device 3210 may include delta-sigma modulation. The processing unit 3222 may perform delta-sigma modulation using the transmission-related information. The processing unit 3222 may transmit a signal output by the delta-sigma modulation to the first device 3210.

The processing related to the first physical layer may include one or more of a filtering process, an amplification process, and a frequency conversion process. The processing related to the first physical layer is not limited to this example.

The processing related to the second physical layer may include a modulation process. The modulation process may include delta-sigma modulation. The processing related to the second physical layer may be other processing as long as it is a higher level processing than the processing related to the first physical layer.

The first device 3210 and the second device 3220 may comply with 3GPP technical specifications and also with O-RAN (Open RAN) Alliance technical specifications.

Note that the above-described embodiments and modifications are merely examples, and the scope of the technical idea of this disclosure is not limited to the above-described configurations. Other aspects conceivable within the scope of the technical idea of this disclosure are also included in the scope of this disclosure.

The above-described embodiments and modifications may be applied to systems other than RoF systems using digital sigma modulation. For example, the above-described embodiments and modifications may be applied to analog RoF systems. Analog RoF systems are known systems that convert analog signals into optical signals and transmit the optical signals over optical fibers.

The processing steps shown in a flowchart or sequence diagram do not necessarily have to be performed in the order shown. The processing steps may be performed in an order different from that shown, and two or more processing steps may be performed in parallel. In addition, some processing steps may be deleted and additional processing steps may be added.

The arrows in the drawings are only an example showing the direction of signal (data) flow from one component to another and do not exclude bidirectional communication between the two components.

In this specification, "transmitting X to Y" is not limited to directly transmitting X to Y, but includes indirectly transmitting X to Y (i.e., X is transmitted to another node and X is transmitted from the other node to Y). Similarly, "receiving X from Y" is not limited to directly receiving X from Y, but includes indirectly receiving X from Y (i.e., X is transmitted from Y to another node and X is received from the other node). Thus, a repeater may be disposed between the first device 810 and the second device 820. The repeater may relay the transmission of the second signal and/or the transmission-related information.

The functions of the devices described in this specification may be realized by software, hardware, or a combination of software and hardware. The program code (instructions) constituting the software may be stored, for example, in a computer-readable recording medium inside or outside each device, and may be loaded into memory at run time and executed by a processor. Also, a non-transitory computer-readable medium on which the program code is recorded may be provided.

Some or all of the above embodiments and variations may be described as follows, but are not limited to the following notes:

(Appendix 1)
A first radio access network device for performing processing related to a first physical layer,
an acquisition unit that acquires information regarding transmission between the first radio access network device and a second radio access network device that performs processing related to a second physical layer higher than the first physical layer;
a transmitter for transmitting the information regarding the transmission to the second radio access network device;
A first radio access network device comprising:

(Appendix 2)
The first radio access network device described in Supplementary Note 1, wherein the information regarding the transmission is information generated during the transmission process of a signal transmitted from the second radio access network device to the first radio access network device.

(Appendix 3)
The first radio access network device according to claim 2, wherein the information regarding the transmission is information regarding a downlink signal to be transmitted from the first radio access network device to a terminal device.

(Appendix 4)
The first radio access network device described in Supplementary Note 3, wherein the information regarding the transmission is a signal obtained by frequency converting the downlink signal.

(Appendix 5)
The first radio access network device according to claim 2, wherein the information regarding the transmission includes information regarding distortion occurring during the transmission process.

(Appendix 6)
The first radio access network device described in Supplementary Note 1, wherein the information regarding the transmission is a parameter of a neural network that outputs an approximation of a signal generated through at least a portion of the transmission process of the signal transmitted from the second radio access network device to the first radio access network device.

(Appendix 7)
The first radio access network device according to claim 1, wherein the transmitting unit controls the transmission of the information regarding the transmission in response to an instruction signal transmitted from the second radio access network device.

(Appendix 8)
The first radio access network device of claim 7, wherein the instruction signal includes a first instruction signal instructing the first radio access network device to transmit the information regarding the transmission to the second radio access network device.

(Appendix 9)
9. The first radio access network device of claim 8, wherein the first indication signal includes information about a number of times the first radio access network device transmits the information regarding the transmission to the second radio access network device.

(Appendix 10)
The first radio access network device of claim 8, wherein the first instruction signal includes information about a periodicity at which the first radio access network device transmits the information regarding the transmission to the second radio access network device.

(Appendix 11)
11. The first radio access network device of claim 10, wherein the period is defined by a frame, a subframe or a slot.

(Appendix 12)
The first radio access network device described in Supplementary Note 10, wherein the period is defined by a learning period of a neural network that outputs an approximation of a signal generated through at least a portion of a transmission process of a signal transmitted from the second radio access network device to the first radio access network device.

(Appendix 13)
The first radio access network device of claim 7, wherein the instruction signal includes a second instruction signal instructing the first radio access network device to stop sending the information regarding the transmission to the second radio access network device.

(Appendix 14)
The first radio access network device according to claim 1, wherein the transmitting unit transmits the information regarding the transmission to the second radio access network device when a predetermined condition regarding the transmission is satisfied.

(Appendix 15)
The first radio access network device described in Supplementary Note 14, wherein the specified condition is a condition related to an amount of distortion occurring during a transmission process of a signal transmitted from the second radio access network device to the first radio access network device.

(Appendix 16)
The first radio access network device and the second radio access network device are configured to operate in a Time Division Duplex (TDD) mode;
The first radio access network device according to any one of Supplementary Notes 1 to 15, wherein the transmitting unit transmits the information regarding the transmission to the second radio access network device in a downlink slot.

(Appendix 17)
A second radio access network device that performs processing related to a second physical layer higher than the first physical layer,
a receiving unit that receives information regarding transmission between a first radio access network device that performs processing related to the first physical layer and the second radio access network device;
a processing unit that performs processing related to communication with the first radio access network device using the information related to the transmission;
A second radio access network device comprising:

(Appendix 18)
The second radio access network device of claim 17, wherein the information regarding the transmission is information generated during the transmission process of a signal transmitted from the second radio access network device to the first radio access network device.

(Appendix 19)
19. The second radio access network device of claim 18, wherein the information regarding the transmission is information regarding a downlink signal to be transmitted from the first radio access network device to a terminal device.

(Appendix 20)
20. The second radio access network device according to claim 19, wherein the information regarding the transmission is a signal obtained by frequency-converting the downlink signal.

(Appendix 21)
19. The second radio access network device of claim 18, wherein the information regarding the transmission includes information regarding distortion occurring during the transmission process.

(Appendix 22)
The second radio access network device of claim 17, wherein the information regarding the transmission is a parameter of a neural network that outputs an approximation of a signal generated through at least a portion of a transmission process of a signal transmitted from the second radio access network device to the first radio access network device.

(Appendix 23)
18. The second radio access network device of claim 17, further comprising: a transmitter configured to transmit an instruction signal regarding transmission of the information regarding the transmission to the first radio access network device.

(Appendix 24)
the transmitting unit transmits the instruction signal to the first radio access network device when a predetermined condition regarding the transmission is satisfied.
24. The second radio access network device of claim 23.

(Appendix 25)
the predetermined condition is a condition regarding an amount of distortion occurring in a transmission process of a signal transmitted from the second radio access network device to the first radio access network device;
24. The second radio access network device of claim 23.

(Appendix 26)
24. The second radio access network device of claim 23, wherein the instruction signal includes a first instruction signal instructing the first radio access network device to transmit the information regarding the transmission to the second radio access network device.

(Appendix 27)
27. The second radio access network device of claim 26, wherein the first indication signal includes information about a number of times the first radio access network device transmits the information regarding the transmission to the second radio access network device.

(Appendix 28)
27. The second radio access network device of claim 26, wherein the first indication signal includes information about a periodicity at which the first radio access network device transmits the information regarding the transmission to the second radio access network device.

(Appendix 29)
29. The second radio access network device of claim 28, wherein the periodicity is defined by a frame, a subframe or a slot.

(Appendix 30)
The second radio access network device of claim 28, wherein the period is defined by a learning period of a neural network that outputs an approximation of a signal generated through at least a portion of a transmission process of a signal transmitted from the second radio access network device to the first radio access network device.

(Appendix 31)
24. The second radio access network device of claim 23, wherein the instruction signal includes a second instruction signal instructing the first radio access network device to stop sending the information regarding the transmission to the second radio access network device.

(Appendix 32)
The first radio access network device and the second radio access network device are configured to operate in a Time Division Duplex (TDD) mode;
The second radio access network device according to any one of Supplementary Notes 23 to 31, wherein the transmitter transmits the instruction signal to the first radio access network device in an uplink slot.

(Appendix 33)
33. The second radio access network device of any one of Supplementary Notes 17 to 32, wherein the processing relating to the communication with the first radio access network device includes delta-sigma modulation.

(Appendix 34)
The second radio access network device described in Supplementary Note 33, wherein the processing unit transmits the signal output by the delta-sigma modulation to the first radio access network device.

(Appendix 35)
A first radio access network device that performs processing related to a first physical layer;
A second radio access network device that performs processing related to a second physical layer that is higher than the first physical layer;
Equipped with
The first radio access network device,
Obtaining information regarding transmissions between the first radio access network device and the second radio access network device;
sending the information regarding the transmission to the second radio access network device;
The second radio access network device,
receiving the information regarding the transmission;
using the information regarding the transmission to perform a process related to communication with the first radio access network device;
Wireless communication device.

(Appendix 36)
A method in a first radio access network device for performing processing related to a first physical layer, comprising:
Obtaining information regarding transmission between the first radio access network device and a second radio access network device that performs processing related to a second physical layer higher than the first physical layer;
transmitting the information regarding the transmission to the second radio access network device;
The method includes:

(Appendix 37)
A method in a second radio access network device for processing a second physical layer higher than a first physical layer, comprising:
receiving information regarding transmission between a first radio access network device performing processing related to the first physical layer and the second radio access network device;
performing a process relating to communication with the first radio access network device using the information relating to the transmission;
The method includes:

(Appendix 38)
Obtaining information regarding transmission between a first radio access network device that processes a first physical layer and a second radio access network device that processes a second physical layer higher than the first physical layer;
transmitting the information regarding the transmission to the second radio access network device;
A non-transitory computer-readable recording medium having recorded thereon a program for causing a processor to execute the above.

(Appendix 39)
Receiving information regarding transmission between a first radio access network device that processes a first physical layer and a second radio access network device that processes a second physical layer higher than the first physical layer;
performing a process relating to communication with the first radio access network device using the information relating to the transmission;
A non-transitory computer-readable recording medium having recorded thereon a program for causing a processor to execute the above.

Appropriate information can be sent or received to improve transmission between two communication devices.

110: Delta sigma modulation device 111: Delta sigma modulation section 112: Neural network processing section 113: Neural network learning section 810: First device 820: Second device 3210: First radio access network device 3220: Second radio access network device

Claims (10)

A first radio access network device for performing processing related to a first physical layer,
a receiving means for receiving a second signal from a second radio access network device performing processing related to a second physical layer higher than the first physical layer via a transmission path, the second signal being a signal converted from a first signal through the processing related to the second physical layer, and being fed back within the second radio access network device;
an acquisition means for acquiring information regarding the transmission of the second signal ;
a transmitting means for transmitting the information on the transmission to the second radio access network device, the conversion of the first signal to the second signal being based on the fed back second signal and the information on the transmission;
A first radio access network device comprising: The first radio access network device of claim 1 , wherein the information regarding the transmission includes information generated in the course of transmitting the second signal. The first radio access network device according to claim 2 , wherein the information regarding the transmission further includes information regarding a downlink signal to be transmitted from the first radio access network device to a terminal device. The first radio access network device according to claim 3 , wherein the information regarding the transmission further includes a signal obtained by frequency converting the downlink signal. The first radio access network device according to claim 2 , wherein the information regarding the transmission further comprises information regarding distortion caused during the transmission process. The first radio access network device of claim 1 , wherein the information regarding the transmission includes parameters of a neural network that outputs an approximation of a signal generated through at least a portion of a transmission process of the second signal. The first radio access network device according to claim 1, wherein the transmitting means controls the transmission of the information regarding the transmission in response to an instruction signal transmitted from the second radio access network device. The first radio access network device according to claim 1, wherein the transmitting means transmits the information regarding the transmission to the second radio access network device when a predetermined condition regarding the transmission is satisfied. A second radio access network device that performs processing related to a second physical layer higher than the first physical layer,
a conversion means for converting a first signal into a second signal;
feedback means for feeding back the second signal to the conversion means;
a transmitting means for transmitting the second signal to a first radio access network device that performs processing related to the first physical layer via a transmission path ;
receiving means for receiving information relating to the transmission of the second signal from the first radio access network device ;
a processing means for performing processing related to communication with the first radio access network device using the information related to the transmission and the fed back second signal ;
A second radio access network device comprising: In a first radio access network device that performs processing related to a first physical layer,
receiving a second signal from a second radio access network device that performs processing related to a second physical layer higher than the first physical layer via a transmission path, the second signal being a signal converted from the first signal through the processing related to the second physical layer and being fed back within the second radio access network device;
obtaining information relating to a transmission of the second signal ;
transmitting the information regarding the transmission to the second radio access network device , where the conversion from the first signal to the second signal is based on the fed back second signal and the information regarding the transmission ;
A program that causes a processor to execute the following:

Images