Wireless communication system, wireless communication method, and receiving device

Abstract

In a wireless communication system according to an embodiment, a receiver device demodulates a signal on the basis of a training signal transmitted by a transmitter device that performs single-carrier multi-level modulation. The transmitter device transmits, to the receiver device, the training signal in such a manner that the amplitude on a constellation includes a plurality of different signal points. The receiver device comprises: an estimation unit that, on the basis of characteristic information indicating an input / output characteristic including a nonlinear region of an amplification unit disposed in the transmitter device for amplifying signals to be transmitted, estimates the signal points included in the training signal when it is assumed that the input / output characteristic even in the nonlinear region of the amplification unit is linear; an equalization unit that initially equalizes the received signal; a correction unit that, on the basis of the signal points estimated by the estimation unit, corrects the signal initially equalized by the equalization unit; a likelihood calculating unit that calculates a likelihood of the signal corrected by the correction unit with respect to the constellation before the amplification unit amplifies the signal; and a demodulation unit that demodulates the signal on the basis of the likelihood calculated by the likelihood calculating unit.

Description

[Technical field]

[0001] The present invention relates to a wireless communication system, a wireless communication method, and a receiving device. [Background technology]

[0002] Conventionally, in wireless communication systems that use single-carrier multi-level modulation, it is common to estimate the communication channel using a known signal such as BPSK (binary phase-shift keying), and then perform demodulation by inversely calculating the complex value of the estimated result.

[0003] Furthermore, when a transmitting device transmits a signal using a nonlinear region of an amplifier, it is known to handle phase transitions using multiple concentric pilot signals (see, for example, Patent Document 1).

[0004] However, when nonlinearity exists in the amplification characteristics of the amplifier in the transmitting device, it is necessary to correct a signal point with a large amplitude to a smaller amplitude value than the channel estimate when amplified with linear amplification characteristics (for example, see Non-Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-59889 A [Non-patent literature]

[0006] [Non-Patent Document 1] MOHAMED IBNKAHLA, et al., "High-Speed ​​Satellite Mobile Communications: Technologies and Challenges", PROCEEDINGS OF THE IEEE, VOL. 92, NO. 2, FEBRUARY 2004, p.312-339 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a wireless communication system, a wireless communication method, and a receiving device that can accurately demodulate a signal even if a transmitting device performing single-carrier multi-level modulation transmits a signal amplified using a nonlinear region. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a wireless communication system in which a receiving device demodulates a signal based on a training signal transmitted by a transmitting device that performs single carrier multi-level modulation. The transmitting device transmits the training signal to the receiving device so as to include a plurality of signal points with different amplitudes on a constellation. The receiving device includes an estimating unit that estimates signal points included in the training signal based on characteristic information indicating input / output characteristics including a nonlinear region of an amplifying unit that is provided in the transmitting device and amplifies a signal to be transmitted, assuming that the input / output characteristics in the nonlinear region of the amplifying unit are also linear, an equalizing unit that initially equalizes the received signal, and an equalizing unit that performs a demodulation process based on the signal points estimated by the estimating unit. , by multiplying the ratio of the nonlinear input-output characteristic to the linear input-output characteristic. The present invention is characterized in that it has a correction unit that corrects the signal initially equalized by the equalization unit, a likelihood calculation unit that calculates the likelihood of the signal corrected by the correction unit with respect to a constellation before the amplification unit amplifies the signal, and a demodulation unit that demodulates the signal based on the likelihood calculated by the likelihood calculation unit.

[0009] Moreover, a wireless communication method according to one aspect of the present invention is a wireless communication method in which a receiving device demodulates a signal based on a training signal transmitted by a transmitting device that performs single-carrier multi-level modulation, the method comprising: a transmitting step in which the transmitting device transmits the training signal to the receiving device so that the training signal includes a plurality of signal points having different amplitudes on a constellation; an estimating step in which the receiving device estimates signal points included in the training signal based on characteristic information indicating input / output characteristics including a nonlinear region of an amplifier unit that is provided in the transmitting device and amplifies a signal to be transmitted, assuming that the input / output characteristics in the nonlinear region of the amplifier unit are also linear; an equalization step in which the receiving device initially equalizes the received signal; and , by multiplying the ratio of the nonlinear input-output characteristic to the linear input-output characteristic. The method includes a correction process for correcting the signal initially equalized by the equalization process, a likelihood calculation process in which the receiving device calculates the likelihood of the signal corrected by the correction process with respect to a constellation before the amplifier unit amplifies the signal, and a demodulation process in which the receiving device demodulates the signal based on the likelihood calculated by the likelihood calculation process.

[0010] Furthermore, a receiving device according to one aspect of the present invention is a receiving device that demodulates a signal based on a training signal transmitted by a transmitting device that performs single carrier multi-level modulation, the receiving device comprising: an estimating unit that estimates signal points included in the training signal transmitted by the transmitting device so as to include a plurality of signal points with different amplitudes on a constellation based on characteristic information indicating input / output characteristics including a nonlinear region of an amplifier that is provided in the transmitting device and amplifies the signal to be transmitted, assuming that the input / output characteristics in the nonlinear region of the amplifier are also linear; an equalizing unit that initially equalizes the received signal; and , by multiplying the ratio of the nonlinear input-output characteristic to the linear input-output characteristic. The present invention is characterized in that it has a correction unit that corrects the signal initially equalized by the equalization unit, a likelihood calculation unit that calculates the likelihood of the signal corrected by the correction unit with respect to a constellation before the amplification unit amplifies the signal, and a demodulation unit that demodulates the signal based on the likelihood calculated by the likelihood calculation unit. Effect of the Invention

[0011] According to the present invention, even if a transmitting device that performs single-carrier multilevel modulation transmits a signal that has been amplified using a nonlinear region, the signal can be demodulated with high accuracy. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of a wireless communication system according to an embodiment. [Diagram 2] FIG. 11 is a functional block diagram illustrating functions of a transmitting device of a comparative example. [Diagram 3] 1A is a graph illustrating the input / output characteristics of the amplifier unit, FIG. 1B is a diagram illustrating a constellation of a transmission signal before the amplifier unit amplifies the transmission signal, and FIG. 1C is a diagram illustrating a constellation of a transmission signal after the amplifier unit amplifies the transmission signal using a nonlinear region. [Figure 4] 4 is a graph illustrating more specifically the input / output characteristics of the amplifier section. [Diagram 5] 1A is a diagram illustrating an example of phase transition correspondence in 16APSK, and FIG. 1B is a diagram illustrating an example of phase transition correspondence in 32APSK. [Figure 6] FIG. 2 is a functional block diagram illustrating functions of a transmitting device according to an embodiment. [Figure 7] 1A is a diagram illustrating a first training signal for a first inner circumference generated by the training signal generating unit, FIG. 1B is a diagram illustrating a second training signal for a second inner circumference generated by the training signal generating unit, and FIG. 1C is a diagram illustrating a third training signal for an outermost circumference generated by the training signal generating unit. [Figure 8] 13 is a diagram showing another example of a training signal generated by the training signal generating section. FIG. [Figure 9] FIG. 2 is a functional block diagram illustrating functions of a receiving device according to an embodiment. [Figure 10] 1A is a diagram showing signal points initially equalized by an equalization unit, FIG. 1B is a diagram showing an example of a third channel estimate identified by an identification unit, and FIG. 1C is a diagram showing an example of a constellation corrected by a correction unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An embodiment of a wireless communication system will be described below with reference to the drawings. Fig. 1 is a diagram showing a configuration example of a wireless communication system 1 according to an embodiment. The wireless communication system 1 is configured such that a transmitting device 2 that performs single carrier multilevel modulation transmits a signal amplified using a nonlinear region, and a receiving device 4 receives and demodulates the signal.

[0014] In addition, the transmitting device 2 transmits a training signal for calculating channel information (e.g., CSI: Channel State Information) to the receiving device 4. The receiving device 4 calculates the channel information using the received training signal, and transmits the calculated channel information to the transmitting device 2.

[0015] The communication path information may or may not be known to the transmitting device 2. The transmitting device 2 and the receiving device 4 may each have the same functions to transmit and receive data.

[0016] Here, in order to facilitate understanding of the configuration of the wireless communication system 1 according to an embodiment, a configuration example of a transmission device 2a of a comparative example will be described first. Fig. 2 is a functional block diagram illustrating functions of the transmission device 2a of the comparative example.

[0017] As shown in FIG. 2, a transmitting device 2a of the comparative example includes an information bit generating section 20, a modulating section 21, a D / A converting section 22, an amplifying section 23, and an antenna 24.

[0018] The information bit generator 20 generates information bits to be transmitted to the receiving device 4, and outputs the information bits to the modulator 21. The information bit generator 20 may also have an error correction coding function and an interleaving function.

[0019] The modulation unit 21 modulates the information bits generated by the information bit generation unit 20 into a data signal by, for example, a single carrier multi-level modulation method, and outputs the data signal to the D / A conversion unit 22. The single carrier multi-level modulation method used by the modulation unit 21 includes, for example, quadrature amplitude modulation (64QAM, 256QAM).

[0020] The D / A conversion section 22 converts the data signal digitally modulated by the modulation section 21 into an analog signal, and outputs the analog signal to the amplification section 23 .

[0021] The amplifier 23 amplifies the analog signal converted by the D / A converter 22 and emits the amplified signal via the antenna 24 .

[0022] Fig. 3 is a diagram illustrating the amplification characteristics of the amplifier 23. Fig. 3(a) is a graph illustrating the input / output characteristics (amplification characteristics) of the amplifier 23. Fig. 3(b) is a diagram illustrating the constellation of the transmission signal before it is amplified by the amplifier 23. Fig. 3(c) is a diagram illustrating the constellation of the transmission signal after it is amplified by the amplifier 23 using the nonlinear region as well.

[0023] As shown in FIG. 3(a), the amplifier 23 has a linear region where the amplifier amplifies and outputs the input in proportion to the input, and a nonlinear region where the amplifier nonlinearly amplifies an excessively large input.

[0024] As shown in Fig. 3(b), no distortion occurs in the constellation of the transmission signal before it is amplified by the amplifier 23. Similarly, no distortion occurs in the constellation of the transmission signal when the amplifier 23 amplifies the transmission signal using only the linear region. In Fig. 5, the first inner circumference of the constellation is indicated as A, the second inner circumference is indicated as B, and the outermost circumference is indicated as C.

[0025] On the other hand, as shown in Fig. 3(c), when the amplifier 23 amplifies the transmission signal using the nonlinear region as well, distortion (reduction in amplitude) occurs in the constellation. Note that Fig. 3(c) shows a case where the first and second inner signal points are amplified in the linear region of the amplifier 23, and the outermost signal point is amplified in the nonlinear region of the amplifier 23.

[0026] Fig. 4 is a graph more specifically illustrating the input / output characteristics of the amplifier 23. In Fig. 4, A shows the input / output characteristics of an ideal amplifier that can linearly amplify input power from small to large. B shows an example of the input / output characteristics of the amplifier 23. C is a graph showing the phase transition of the amplifier 23.

[0027] 5A and 5B are diagrams illustrating phase transitions in the amplifier 23 according to the conventional technology. Fig. 5(a) is a diagram illustrating phase transitions in 16APSK (Amplitude and Phase Shift Keying). Fig. 5(b) is a diagram illustrating phase transitions in 32APSK.

[0028] As shown in Figure 5(a), in a constellation (inner periphery A1, outermost periphery B1) containing the IQ coordinates of ideal signal points with two different radii (amplitudes), conventionally, phase transitions are compensated for by transmitting one or more ideal signal points P as pilot signals (known signals) for the amplitude level of the inner periphery A1.

[0029] Also, as shown in FIG. 5(b), in a constellation (first inner circumference A2, second inner circumference B2, outermost circumference C2) including IQ coordinates of ideal signal points with three different radii (amplitudes), phase transitions are conventionally compensated by transmitting one or more ideal signal points P as pilot signals for each of the amplitude levels of the first inner circumference A2 and the second inner circumference B2.

[0030] In this way, conventionally, in order to compensate for the different phase characteristics for each constellation amplitude, one pilot signal was placed for each signal point with a different radius, making it possible for the receiving device to compensate for the phase transition of the signal points and perform demodulation.

[0031] In the single-carrier multilevel modulation method, it is expected that the SNR can be improved by increasing the average transmission power to an allowable value. On the other hand, if excessive transmission power is input to the amplifier 23, the amplitude of the peak signal, etc., becomes small due to saturation. Then, if equalization is performed using a channel response estimated by a training signal in the linear domain (e.g., BPSK), a detection error occurs in the peak signal, etc. For this reason, communication is generally performed with a sufficiently low transmission power (small amplitude) that does not cause distortion in the peak signal.

[0032] Thus, conventionally, even if the amplitude of a signal point changes due to the input / output characteristics of an amplifier, the signal point cannot be compensated for, and accurate demodulation cannot be performed.

[0033] Therefore, in one embodiment of the wireless communication system 1, the transmitting device 2 transmits a training signal to the receiving device 4 so that the training signal includes multiple signal points with different amplitudes on a constellation, and the receiving device 4 performs demodulation based on the training signal, thereby enabling accurate demodulation.

[0034] Fig. 6 is a functional block diagram illustrating functions of the transmitting device 2 according to an embodiment. In the transmitting device 2 shown in Fig. 6, the same reference numerals are used for the configurations that are substantially the same as those of the transmitting device 2a shown in Fig. 2.

[0035] As shown in FIG. 6, the transmitting device 2 according to one embodiment includes an information bit generating unit 20, a modulating unit 21, a D / A converting unit 22, an amplifying unit 23, an antenna 24, a characteristic data generating unit 25, and a training signal generating unit .

[0036] The characteristic data conversion section 25 converts the input / output characteristics of the amplifier section 23 into data, generates characteristic information indicating the input / output characteristics of the amplifier section 23 , and outputs the information bit generation section 20 .

[0037] Therefore, the information bit generator 20 includes characteristic information indicating the input / output characteristics of the amplifier 23 in the information bits it generates.

[0038] The training signal generating section 26 generates training signals of a plurality of radius (amplitude) patterns according to the constellation, and adds the training signals to the signal output from the modulating section 21 to the D / A converting section 22 .

[0039] Fig. 7 is a diagram illustrating training signals generated by the training signal generating unit 26 for the constellation shown in Fig. 3, for example. Fig. 7(a) is a diagram illustrating a first training signal for the first inner circumference A generated by the training signal generating unit 26. Fig. 7(b) is a diagram illustrating a second training signal for the second inner circumference B generated by the training signal generating unit 26. Fig. 7(c) is a diagram illustrating a third training signal for the outermost circumference C generated by the training signal generating unit 26.

[0040] As shown in Figures 7(a) to (c), the training signal generating unit 26 generates three types of training signals for the constellation shown in Figure 3, for example. Here, the training signals shown in Figures 7(a) to (c) are some of the signal points when it is assumed that the input / output characteristics in the nonlinear region of the amplifying unit 23 are also linear, for example.

[0041] In this way, the training signal includes signal points with different amplitude numbers on the constellation before the amplifier 23 amplifies the signal.

[0042] The three types of training signals shown in Figures 7(a) to (c) are then transmitted to the receiving device 4 and used to calculate a signal that is deemed to have been amplified by an ideal amplifier that can linearly amplify from small input power to large input power.

[0043] Fig. 8 is a diagram showing another example of the training signal generated by the training signal generating unit 26. As shown in Fig. 8, the training signal generated by the training signal generating unit 26 may include one signal point selected for each region on a predetermined constellation including a plurality of signal points.

[0044] In other words, for a constellation with a large number of signal points, the number of signal points included in the training signal can be reduced by selecting a signal point that is representative of the multiple signal points.

[0045] 9 is a functional block diagram illustrating functions of the receiving device 4 according to an embodiment. As shown in FIG. 9, the receiving device 4 according to an embodiment includes an amplifier 40, an A / D converter 41, an estimator 42, a memory 43, an equalizer 44, an identifier 45, a corrector 46, a likelihood calculator 47, a demodulator 48, an information bit detector 49, and an antenna 50.

[0046] The amplifier 40 amplifies the analog signal received by the receiver 4 via the antenna 50 and outputs the amplified signal to the A / D converter 41 .

[0047] The A / D conversion unit 41 converts the analog signal amplified by the amplification unit 40 into a digital signal, and outputs it to the estimation unit 42 and the equalization unit 44. For example, the A / D conversion unit 41 converts a training signal including characteristic information indicating the input / output characteristics of the amplification unit 23 provided in the transmission device 2 into a digital signal, and outputs it to the estimation unit 42. In addition, the A / D conversion unit 41 converts a data signal corresponding to information bits to be transmitted by the reception device 4 from the transmission device 2 into a digital signal, and outputs it to the equalization unit 44.

[0048] The training signal converted into a digital signal by the A / D conversion unit 41 is transmitted when the transmitting device 2 and the receiving device 4 start communication.

[0049] The estimation unit 42 estimates a communication channel (for example, the first communication channel estimated value to the third communication channel estimated value shown in FIG. 7) based on the training signal input from the A / D conversion unit 41. That is, based on characteristic information indicating input / output characteristics including a nonlinear region of the amplification unit 23 that is provided in the transmission device 2 and amplifies a signal to be transmitted, the estimation unit 42 estimates a signal point included in the training signal on the assumption that the input / output characteristics in the nonlinear region of the amplification unit 23 are also linear.

[0050] The memory unit 43 stores the communication path estimated by the estimation unit 42, and outputs it in response to an accelerator from the identification unit 45. In other words, the receiving device 4 can share characteristic information indicating the input / output characteristics of the amplifier unit 23 with the transmitting device 2.

[0051] The equalization unit 44 performs initial equalization on the data signal input from the A / D conversion unit 41 and outputs the result to an identification unit 45 and a correction unit 46 .

[0052] The identification unit 45 identifies signal values ​​that require correction in the data signal initially equalized by the equalization unit 44 based on the communication channels stored in the memory unit 43 (for example, the first communication channel estimated value to the third communication channel estimated value shown in FIG. 7), and outputs the identified signal values ​​to the correction unit 46.

[0053] The correction unit 46 corrects the signal value initially equalized by the equalization unit 44 based on the signal value identified by the identification unit 45, and outputs a signal including the corrected constellation to the likelihood calculation unit 47. For example, the correction unit 46 performs the correction by multiplying the signal value initially equalized by the equalization unit 44 by the ratio between the nonlinear input / output characteristic and the linear input / output characteristic.

[0054] Fig. 10 is a diagram illustrating a process in which the correction unit 46 corrects the signal value initially equalized by the equalization unit 44. Fig. 10(a) is a diagram illustrating signal points initially equalized by the equalization unit 44. Fig. 10(b) is a diagram illustrating a third communication channel estimation value identified by the identification unit 45. Fig. 10(c) is a diagram illustrating a constellation corrected by the correction unit 46.

[0055] As shown in FIG. 10, in response to a constellation (a) distorted by the input / output characteristics of the amplifier 23, the correction unit 46 outputs a corrected constellation (c) to the likelihood calculation unit 47 based on signal points (b) included in the training signal on the assumption that the input / output characteristics in the nonlinear region of the amplifier 23 are also linear.

[0056] The likelihood calculation unit 47 calculates the likelihood of the signal corrected by the correction unit 46 for the constellation before the signal is amplified by the amplifier 23 of the transmission device 2, and outputs the calculated likelihood to the demodulation unit .

[0057] The demodulation unit 48 demodulates the signal based on the likelihood calculated by the likelihood calculation unit 47 , and outputs the demodulated signal to an information bit detection unit 49 .

[0058] The information bit detection unit 49 detects information bits from the signal demodulated by the demodulation unit 48. Therefore, the receiving device 4 according to the embodiment corrects the signal initially equalized by the equalization unit 44 and demodulates the signal based on the likelihood calculated by the likelihood calculation unit 47, so that even if the transmitting device 2 performing single carrier multi-level modulation transmits a signal amplified using a nonlinear region, the signal can be demodulated with high accuracy.

[0059] In this way, the receiver 4 can perform likelihood calculations based on a non-distorted constellation before the Euclidean distance between each signal point is narrowed, and can demodulate the signal with high accuracy.

[0060] Note that each unit constituting the transmitting device 2 and the receiving device 4 in the above-described embodiment may be partially or entirely configured by hardware, or may be configured by causing a processor to execute a program.

[0061] Furthermore, when each part constituting the transmitting device 2 and the receiving device 4 is constituted in part or in whole by having a processor execute a program, the program may be recorded on a recording medium and supplied, or may be supplied via a network. [Explanation of symbols]

[0062] 1 wireless communication system, 2, 2a transmitting device, 4 receiving device, 20 information bit generating section, 21 modulation section, 22 D / A conversion section, 23 amplifier section, 24 antenna, 25 characteristic data generating section, 26 training signal generating section, 40 amplifier section, 41 A / D conversion section, 42 estimation section, 43 storage section, 44 equalization section, 45 identification section, 46 correction section, 47 likelihood calculation section, 48 demodulation section, 49 information bit detection section, 50 antenna

Claims

1. In a wireless communication system in which a receiving device demodulates a signal based on a training signal transmitted by a transmitting device that performs single carrier multilevel modulation, The transmitting device Transmitting the training signal to the receiving device so as to include a plurality of signal points having different amplitudes on a constellation; The receiving device includes: an estimation unit that estimates a signal point included in the training signal based on characteristic information indicating input / output characteristics including a nonlinear region of an amplifier unit that is provided in the transmitting device and amplifies a signal to be transmitted, assuming that the input / output characteristics in the nonlinear region of the amplifier unit are also linear; an equalization unit that performs initial equalization on a received signal; a correction unit that corrects the signal initially equalized by the equalization unit by multiplying a ratio between a nonlinear input / output characteristic and a linear input / output characteristic based on the signal point estimated by the estimation unit; a likelihood calculation unit that calculates the likelihood of a signal corrected by the correction unit with respect to a constellation before the signal is amplified by the amplification unit; a demodulation unit that demodulates a signal based on the likelihood calculated by the likelihood calculation unit; A wireless communication system comprising:

2. The receiving device includes: receiving the characteristic information from the transmitting device; 2. The wireless communication system according to claim 1,

3. The training signal is The signal constellation before the amplifier amplifies the signal includes signal points of different amplitudes.

3. The wireless communication system according to claim 1 or 2.

4. The training signal is Including one selected signal point for each region on a predetermined constellation including a plurality of signal points.

4. The wireless communication system according to claim 1, wherein:

5. A wireless communication method in which a receiving device demodulates a signal based on a training signal transmitted by a transmitting device that performs single carrier multilevel modulation, a transmitting step of transmitting the training signal to the receiving device so as to include a plurality of signal points on a constellation with different amplitudes; an estimation step in which the receiving device estimates a signal point included in the training signal on the assumption that the input / output characteristics in the nonlinear region of an amplifier unit that is provided in the transmitting device and amplifies a signal to be transmitted are also linear, based on characteristic information indicating input / output characteristics including a nonlinear region of the amplifier unit; an equalization step in which the receiving device initially equalizes a received signal; a correction step in which the receiving device corrects the signal initially equalized in the equalization step by multiplying a ratio between a nonlinear input / output characteristic and a linear input / output characteristic based on the signal point estimated in the estimation step; a likelihood calculation step in which the receiving device calculates a likelihood of a signal corrected by the correction step with respect to a constellation before the signal is amplified by the amplifier; a demodulation step in which the receiving device demodulates a signal based on the likelihood calculated in the likelihood calculation step; 13. A wireless communication method comprising:

6. A receiving device that demodulates a signal based on a training signal transmitted by a transmitting device that performs single carrier multilevel modulation, an estimation unit that estimates signal points included in the training signal transmitted by the transmitting device so as to include a plurality of signal points having different amplitudes on a constellation, based on characteristic information indicating input / output characteristics including a nonlinear region of an amplifier unit that is provided in the transmitting device and amplifies a signal to be transmitted, and assuming that the input / output characteristics in the nonlinear region of the amplifier unit are also linear; an equalization unit that performs initial equalization on a received signal; a correction unit that corrects the signal initially equalized by the equalization unit by multiplying a ratio between a nonlinear input / output characteristic and a linear input / output characteristic based on the signal point estimated by the estimation unit; a likelihood calculation unit that calculates the likelihood of a signal corrected by the correction unit with respect to a constellation before the signal is amplified by the amplification unit; a demodulation unit that demodulates a signal based on the likelihood calculated by the likelihood calculation unit; A receiving device comprising:

7. The estimation unit is Estimating a signal point based on the characteristic information transmitted by the transmitting device.

7. The receiving device according to claim 6,

8. The training signal is The signal constellation before the amplifier amplifies the signal includes signal points of different amplitudes.

8. The receiving device according to claim 6 or 7,

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