Transmitter and transmission method

Abstract

To improve the performance of radio communication.SOLUTION: The transmitter includes a processing circuit that uses one of the transmission signals mapped to the symmetric frequency resources with respect to the center frequency to perform correction processing on the other of the transmission signals mapped to the symmetric frequency resources, and a quadrature modulator that performs quadrature modulation on the transmission signal after the correction processing.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a transmitter and a transmission method. [Background technology]

[0002] Cellular wireless communications, including 5G NR (New Radio access technology), are currently underway. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] “PROPOSAL FOR A USER-CENTRIC RAN ARCHITECTURE TOWARDS BEYOND 5G”, IEICE Technical Report, vol. 121, no. 189, SAT2021-43, pp. 4-10, October 2021. Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is room for improvement in how wireless communication performance can be improved.

[0005] Non-limiting embodiments of the present disclosure contribute to providing a transmitter and a transmission method that can improve the performance of wireless communications. [Means for solving the problem]

[0006] A transmitter according to one embodiment of the present disclosure includes a processing circuit that uses one of transmission signals that are mapped to frequency resources symmetrical with respect to a center frequency to perform correction processing on the other of transmission signals that are mapped to the symmetric frequency resources, and a quadrature modulator that quadrature-modulates the transmission signal after the correction processing.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0008] According to an embodiment of the present disclosure, the performance of wireless communication can be improved.

[0009] Further advantages and benefits of certain aspects of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features. [Brief explanation of the drawings]

[0010] [Figure 1] A diagram showing an example of the configuration of a transmitter [Figure 2] A diagram showing an example of the configuration of a transmitter [Figure 3] A diagram showing an example of the configuration of a transmitter [Figure 4] FIG. 1 shows an example of the configuration of a part of a transmitter. [Figure 5] A diagram showing an example of the configuration of a transmitter [Figure 6] A diagram showing an example of the configuration of a correction circuit. [Figure 7] A diagram showing an example of the configuration of a correction circuit. [Figure 8] A diagram showing an example of the configuration of a correction circuit. [Figure 9] A diagram showing an example of the configuration of a transmitter [Figure 10] A diagram showing an example of the configuration of a transmitter [Figure 11] A diagram showing an example of the configuration of a transmitter DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] Microwave and millimeter wave band radio waves are used in cellular wireless communications including 5G NR. In 6G systems (sixth generation mobile communication systems), the use of terahertz (or sub-terahertz) band radio waves above 100 GHz is also being considered. For example, Non-Patent Document 1 proposes a system that uses terahertz waves for communication near terminals.

[0013] In the terahertz band, wireless devices are expected to transmit and receive wireless signals using a wide RF (Radio Frequency) frequency bandwidth.

[0014] A quadrature modulator may be used in a transmitter of a wireless device. FIG. 1 shows an example of a circuit configuration of a transmitter. In the example of FIG. 1, transmission data is processed in a digital signal processing unit (also referred to as a digital signal processing block), undergoes digital-to-analog conversion (DA conversion), and is output as analog signals of an in-phase component (also referred to as an I signal or I component) and a quadrature phase component (also referred to as a Q signal or Q component). The quadrature modulator modulates the I and Q analog signals using a carrier signal (e.g., carrier frequency f0) input from a local oscillator, thereby outputting an RF transmission signal centered on carrier frequency f0.

[0015] As mentioned above, the I and Q inputs to the quadrature modulator are analog signals. In the analog signal domain, for example, as shown in Figure 2, an amplitude offset or a timing offset (delay difference) may occur between the I and Q signals due to differences in amplifier gain or wiring length. Hereinafter, these will be referred to as "I / Q offset."

[0016] When an I / Q offset exists, as shown in Figure 2, an image signal appears in the output signal of the quadrature modulator at a frequency component that is symmetrical with respect to the carrier frequency f0 as viewed from the desired signal. The image signal acts as an interference component, degrading the quality of the transmitted signal (e.g., SINR: Signal to Interference and Noise Ratio). For example, in wideband transmission, the I / Q offset can have frequency characteristics, and so the image signal can also have frequency characteristics.

[0017] In one non-limiting embodiment of the present disclosure, a method for suppressing an image signal caused by an I / Q offset in a quadrature modulator of a transmitter performing wideband transmission will be described. For example, as shown in FIG. 3, the transmitter suppresses the image signal by pre-correcting the transmission signal in a digital signal processing unit. For example, the transmitter pairs frequency resources (e.g., subcarriers) symmetrical with respect to a center frequency (e.g., carrier frequency f0), and corrects the transmission signal of each frequency using signals mapped to the paired frequency resources. This suppresses the image signal and improves signal quality (e.g., SINR).

[0018] [Communication System Overview] A communication system according to an embodiment of the present disclosure may include a plurality of radio devices (e.g., communication devices). The radio device may include, for example, at least one of a transmitter 100 that transmits a signal and a receiver that receives a signal. The radio device may be, for example, a base station (or a gNB, an access point) or a terminal (or a mobile station, a user terminal, a UE (User Equipment), or a STA (Station)). The radio device (e.g., the transmitter 100) may perform, for example, downlink data transmission, uplink data transmission, or data transmission between terminals (e.g., sidelink data transmission).

[0019] Fig. 4 is a block diagram showing an example of the configuration of a portion of transmitter 100. In transmitter 100 shown in Fig. 4, a signal processing unit (e.g., corresponding to a processing circuit) uses one of the transmission signals mapped to frequency resources symmetrical with respect to a center frequency to perform correction processing on the other of the signals mapped to the symmetric frequency resources. A quadrature modulator quadrature-modulates the transmission signal after correction processing.

[0020] [Transmitter configuration example] FIG. 5 is a block diagram showing an example of the configuration of transmitter 100 in the wireless device according to this embodiment.

[0021] The transmitter 100 shown in FIG. 5 may include a digital signal processing unit 101, a quadrature modulator 102, and an antenna 103 (for example, a transmitting antenna).

[0022] The digital signal processing unit 101 performs digital signal processing on the transmission data. For example, the digital signal processing unit 101 may perform an Inverse Fast Fourier Transform (IFFT) process (not shown) on a signal mapped to a frequency resource (e.g., a subcarrier).

[0023] The digital signal processing unit 101 may include, for example, a modulation signal generating unit 111, a correction circuit 112, a real part extracting unit 113, an imaginary part extracting unit 114, and a digital / analog converter (D / A converter) 115.

[0024] The modulation signal generation unit 111 performs signal processing on input data to generate, for example, a modulation signal (hereinafter represented by "s") that is mapped to a subcarrier of frequency (+ω) and a modulation signal (hereinafter represented by "s'") that is mapped to a subcarrier of frequency (-ω). The modulation signal generation unit 111 outputs the generated signals to the correction circuit 112. Here, the frequency +ω and the frequency -ω are, for example, frequencies symmetrical with respect to the center frequency f0 (for example, a pair of frequency resources).

[0025] The correction circuit 112 performs a correction process on the modulated signals s and s' input from the modulated signal generation unit 111. For example, the correction circuit 112 corrects the modulated signals s and s' so that the image signal is suppressed. The correction circuit 112 outputs the corrected signals to the real part extraction unit 113 and the imaginary part extraction unit 114. An example of the correction process in the correction circuit 112 will be described later.

[0026] Real part extraction unit 113 extracts the real part (e.g., I component) of the signal input from correction circuit 112 and outputs it to I-side D / A converter 115-1. Imaginary part extraction unit 114 extracts the imaginary part (e.g., Q component) of the signal input from correction circuit 112 and outputs it to Q-side D / A converter 115-2.

[0027] The I-side and Q-side D / A converters 115 convert the signals (digital signals) input from the real part extraction unit 113 or the imaginary part extraction unit 114 into analog signals and output them to analog signal domains corresponding to the I-side and Q-side of the quadrature modulator 102.

[0028] The digital signal processing unit 101 has been described above.

[0029] The quadrature modulator 102 quadrature-modulates the signals input to the I and Q sides to generate a transmission signal, which is output to the antenna 103 .

[0030] Antenna 103 radiates the transmission signal input from quadrature modulator 102 toward another wireless device (for example, a receiver).

[0031] [Transmitter 100 operation example] Next, a description will be given of an example of the operation of the above-mentioned transmitter 100 (for example, the correction circuit 112). The correction circuit 112 performs correction processing based on, for example, an I / Q offset (for example, an amplitude offset or a timing offset) between the I component and the Q component of the transmission signal.

[0032] <Example 1> In operation example 1, the correction circuit 112 suppresses the image signal by generating a component that cancels the I / Q offset using modulated signals that are mapped to each frequency resource (a pair of frequency resources, e.g., subcarriers) of frequencies +ω and −ω.

[0033] For example, the correction circuit 112 may correct the IFFT input signals corresponding to the subcarriers of frequencies +ω and −ω using the modulated signal s corresponding to the subcarriers of frequency +ω and the modulated signal s' corresponding to the subcarriers of frequency −ω, which are input from the modulated signal generation unit 111. For example, the correction circuit 112 may generate the IFFT input signals as shown in the following equations (1) and (2), respectively.

number

number

[0034] where V R indicates the correction value for the amplitude offset (the value obtained by dividing the amplitude of the I signal by the amplitude of the Q signal; amplitude ratio) between the I signal and the Q signal in the analog section (analog signal domain), and τ indicates the correction value for the timing offset (the amount of delay of the I signal relative to the Q signal) between the I signal and the Q signal in the analog section.

[0035] The IFFT output signal is output from the correction circuit 112. The IFFT output signal (corrected transmission signal) includes a component that cancels out the I / Q offset.

[0036] By the above correction, the I / Q offset occurring in the subcarriers of frequencies +ω and −ω in the analog section is cancelled out, so that the image signal can be suppressed.

[0037] Fig. 6 shows an example of the circuit configuration of correction circuit 112 in operation example 1. In Fig. 6, s represents a modulated signal mapped to a subcarrier with a frequency of +ω, and s' represents a modulated signal mapped to a subcarrier with a frequency of −ω.

[0038] 7 shows another example of the circuit configuration of the correction circuit 112 in the operation example 1. In the configuration example shown in FIG. 7, the number of multipliers with a high calculation load is reduced (for example, minimized) compared to FIG. 6. Also, in FIG. 7, for example, the correction value V R If we set is 1, instead of the multiplier, e +jωτ Since a phase rotator that performs phase rotation of the above formula can be used, the calculation load can be further reduced.

[0039] The correction circuit 112 shown in FIG. 6 or FIG. 7 provides the IFFT input signals shown in equations (1) and (2).

[0040] As an example, the procedure for deriving the above-mentioned IFFT input values ​​will be described below.

[0041] When the quadrature modulator 102 modulates the subcarrier of frequency +ω with modulation vector a, the modulated signal is expressed as x(t)=ae +jωt The real part Re[x(t)] and the imaginary part Im[x(t)] of the modulated signal x(t) are respectively expressed by the following equation (3).

number

[0042] Here, the I / Q offset is the time delay τ of the real part Re[x(t)] and the amplitude ratio between the real part and the imaginary part is V R Then, the real part of the modulated signal x(t) is

number

number

[0043] Similarly, when the quadrature modulator 102 modulates the subcarrier of frequency −ω with modulation vector b, the modulated signal is expressed as y(t)=be -jωt The I / Q offset is the time delay τ of the real part Re[y(t)] of the modulated signal y(t), and the amplitude ratio between the real part and the imaginary part is V R Then, the modulated signal y^(t) output from the quadrature modulator 102 is expressed by the following equation (5).

number

[0044] Therefore, the transmission signal output from quadrature modulator 102, in which subcarriers of frequencies +ω and −ω are modulated with modulation vector a and modulation vector b, respectively, is expressed by the following equation (6).

number

[0045] On the other hand, in the subcarrier of frequency +ω to which the modulated signal s is mapped, the transmission signal without image signal and I / Q offset is expressed by the following equation (7).

number

[0046] Therefore, from equations (6) and (7), by solving the simultaneous equations expressed by the following equation (8), it is possible to obtain coefficient a of the IFFT input signal corresponding to the subcarrier of frequency +ω and coefficient b of the IFFT input signal corresponding to the subcarrier of frequency −ω, in order to remove the image signal from the subcarrier of frequency +ω.

number

[0047] Taking the complex conjugate of equation (8-2) gives the following equation (9).

number

[0048] b shown in equation (9) * Substituting this into equation (8-1) gives the following equation (10).

number

[0049] Furthermore, when a shown in equation (10) is substituted into the complex conjugate of equation (8-1), the following equation (11) is obtained.

number

[0050] From the above, in order to remove the image signal from the subcarrier of frequency +ω to which the modulated signal s is mapped, the coefficient a of the IFFT input signal corresponding to the subcarrier of frequency +ω (e.g., a1s shown in FIG. 6) and the coefficient b of the IFFT input signal corresponding to the subcarrier of frequency −ω (e.g., b1s shown in FIG. 6) are * (corresponding to) is obtained by the following equations (12) and (13).

number

number

[0051] Similarly, in the subcarrier of frequency −ω to which the modulated signal s′ is mapped, the transmission signal without image signal and I / Q offset is expressed by the following equation (14).

number

[0052] Therefore, from equations (6) and (14), by solving the simultaneous equations in the following equation (15), coefficient a of the IFFT input signal corresponding to the subcarrier of frequency +ω and coefficient b of the IFFT input signal corresponding to the subcarrier of frequency −ω can be obtained to remove the image signal from the subcarrier of frequency −ω.

number

[0053] By solving equation (15), the coefficient a of the IFFT input signal corresponding to the subcarrier of frequency +ω (for example, a2s' shown in FIG. 6) is obtained to remove the image signal from the subcarrier of frequency −ω to which the modulated signal s' is mapped. * ) and the coefficient b of the IFFT input signal corresponding to the subcarrier of frequency −ω (for example, corresponding to b2s′ shown in FIG. 6) are obtained by the following equations (16) and (17).

number

number

[0054] For example, the IFFT input signal (modulated signal after correction) corresponding to the subcarrier of frequency +ω is obtained by equations (12) and (16), and the IFFT input signal (modulated signal after correction) corresponding to the subcarrier of frequency −ω is obtained by equations (13) and (17).

[0055] When the transmitter 100 performs quadrature modulation on the modulated signal after the above correction in the quadrature modulator 102, it is possible to extract signals from the subcarriers of frequencies +ω and −ω in which the image signal components of the paired frequencies (−ω and +ω) are cancelled, as shown in, for example, equations (7) and (14). Furthermore, as shown in, for example, equations (7) and (14), in the extracted signals, distortions (for example, amplitude and timing offset components) in the desired signals s and s' of each frequency (+ω and −ω) can also be suppressed.

[0056] In this way, in Operation Example 1, by performing correction to suppress the image signals in the modulated signals s and s', it is possible to obtain a transmission signal that is free of image signals and I / Q offsets, as shown in Equations (7) and (14). Furthermore, in Operation Example 1, in addition to the image signals, distortions in the desired signals s and s' (for example, amplitude and timing offset components) can also be suppressed.

[0057] <Example 2> In operation example 2, the correction circuit 112 suppresses the image signal by subtracting the image signal component caused by the I / Q offset from the modulated signal mapped to each frequency resource (a pair of frequency resources, e.g., subcarriers) of frequencies +ω and −ω.

[0058] For example, the correction circuit 112 may correct the IFFT input signals corresponding to the subcarriers of frequencies +ω and −ω using the modulated signal s corresponding to the subcarriers of frequency +ω and the modulated signal s' corresponding to the subcarriers of frequency −ω, which are input from the modulated signal generation unit 111. For example, the correction circuit 112 may generate the IFFT input signals as shown in the following equations (18) and (19), respectively.

number

number

[0059] where V R indicates the correction value for the amplitude offset (the value obtained by dividing the amplitude of the I signal by the amplitude of the Q signal; amplitude ratio) between the I signal and the Q signal in the analog section (analog signal domain), and τ indicates the correction value for the timing offset (the amount of delay of the I signal relative to the Q signal) between the I signal and the Q signal in the analog section.

[0060] The IFFT output signal is output from the correction circuit 112. The IFFT output signal (corrected transmission signal) is a signal from which an image signal component that may occur in the analog section has been subtracted.

[0061] As a result of the above correction, the expected image signal components are subtracted in advance from the corrected modulated signal in digital signal processing, so that even if image signal components occur in the subcarriers of frequencies +ω and −ω in the analog section, the image signals can be suppressed.

[0062] Fig. 8 shows an example of the circuit configuration of the correction circuit 112 in Operation Example 2. In Fig. 8, s represents a modulated signal mapped to a subcarrier with a frequency of +ω, and s' represents a modulated signal mapped to a subcarrier with a frequency of −ω.

[0063] The correction circuit 112 shown in FIG. 8 provides the IFFT input signals shown in equations (18) and (19).

[0064] As an example, the procedure for deriving the above-mentioned IFFT input values ​​will be described below.

[0065] As in the first operational example, when quadrature modulator 102 modulates subcarriers of frequencies +ω and −ω with modulation vectors a and b, respectively, the transmission signal output from quadrature modulator 102 is expressed by the following equation (20).

number

[0066] Here, in order to remove the image signal from the subcarrier of frequency +ω to which the modulated signal s is mapped, e -jωt All we need to do is to give values ​​of a and b such that the term is 0. For example, if we set a = s, we get the following equation (21).

number

[0067] From equation (21), the coefficient a of the IFFT input signal corresponding to the subcarrier of frequency +ω and the coefficient b of the IFFT input signal corresponding to the subcarrier of frequency −ω (for example, b1s shown in FIG. 8) are used to remove the image signal from the subcarrier of frequency +ω to which the modulated signal s is mapped. * (corresponding to) is obtained by the following equation (22).

number

[0068] Similarly, to remove the image signal from the subcarrier of frequency -ω to which the modulated signal s' is mapped, e +jωt All we need to do is to give values ​​of a and b such that the term is 0. For example, if we set b=s', we get the following equation (23).

number

[0069] From equation (23), the coefficient a of the IFFT input signal corresponding to the subcarrier of frequency +ω (for example, a2s' shown in FIG. 8) is used to remove the image signal from the subcarrier of frequency −ω to which the modulated signal s' is mapped. * (corresponding to the subcarrier of frequency −ω), and the coefficient b of the IFFT input signal corresponding to the subcarrier of frequency −ω is obtained by equation (24).

number

[0070] In the transmitter 100, when the modulated signal after the above correction is quadrature-modulated in the quadrature modulator 102, for example, the subcarrier with frequency +ω is converted into e -jωt The component of the term (image signal component) can be suppressed and a signal can be extracted from the subcarrier of frequency -ω, e +jωt It is possible to extract a signal in which the component of the term (image signal component) is suppressed.

[0071] In this way, in the second operational example, by performing correction to subtract the image signal components from the modulated signals s and s', it is possible to obtain a transmission signal in which the image signal is suppressed.

[0072] An example of the operation of the transmitter 100 has been described above.

[0073] In this embodiment, the transmitter 100 uses one of the transmission signals mapped to symmetric frequency resources (frequencies +ω and −ω) with respect to the center frequency f0 to perform correction processing on the other of the transmission signals mapped to the symmetric frequency resources, and performs quadrature modulation on the corrected transmission signal. In this way, the transmitter 100 pre-corrects the transmission signal (modulated signal) in the digital signal processing unit 101 (digital signal domain) so as to reduce the influence of image signals caused by I / Q offsets that may occur in the analog section (for example, the analog signal domain), thereby suppressing image signals that occur in the analog section (for example, image signals that appear in frequency components symmetric with respect to the center frequency f0), thereby improving signal quality (or error rate characteristics).

[0074] Therefore, according to this embodiment, it is possible to improve the performance of wireless communication.

[0075] [Other examples of operation] In each of the above operation examples, the I / Q amplitude offset V R , and the correction value of the timing offset τ (correction value of the I / Q offset) may be determined, for example, by directly measuring the hardware. For example, the timing offset τ may be measured using a TDR (Time Domain Reflectometry) method or the like. Alternatively, the correction value of the I / Q offset may be estimated using information on the circuit design, the board design, or the like.

[0076] ​Alternatively, the I / Q offset correction value may be determined by a wireless device (for example, the transmitter 100). FIG. 9 shows another example configuration of the transmitter 100. In the transmitter 100 shown in FIG. 9, the digital signal processing unit 101a may include an analog / digital converter (A / D converter) 121 and a control unit 122 in addition to the configuration of the digital signal processing unit 101 shown in FIG. 5. In the digital signal processing unit 101a, for example, an analog I / Q signal at the input portion of the quadrature modulator 102 may be measured and input to the control unit 122 via the A / D converter 121. The control unit 122 determines each correction value (for example, V R and τ) may be determined and output to correction circuit 112. In this case, the layout may be such that the wiring length between A / D converter 121 and the input portion of quadrature modulator 102 is as short as possible. This reduces the influence of amplitude and timing offsets due to the wiring between A / D converter 121 and the input portion of quadrature modulator 102, allowing the I / Q offset in quadrature modulator 102 to be measured with high accuracy. Alternatively, the input of quadrature modulator 102 may be branched, input to a frequency converter or envelope detector (not shown), down-converted to a lower frequency (or DC), and the down-converted signal may be input to A / D converter 121. This reduces loss due to wiring before input to A / D converter 121, allowing the I / Q offset in quadrature modulator 102 to be measured with high accuracy.

[0077] Alternatively, the I / Q offset correction value may be determined based on a measurement of the image signal. For example, a measurement instrument (e.g., which may or may not be included in the wireless device) may determine the I / Q offset correction value V R The image signal may be measured while varying and τ, and the correction value may be calibrated so that the power of the image signal is minimized.

[0078] In this case, the radio device may include a function for measuring the image signal. FIG. 10 shows another example of the configuration of the transmitter 100. The transmitter 100 shown in FIG. 10 includes a frequency converter or envelope detector 104 in addition to the configuration shown in FIG. 5. Furthermore, the digital signal processing unit 101b may include an analog-to-digital converter (A / D converter) 131 and a control unit 132 in addition to the configuration of the digital signal processing unit 101 shown in FIG. 5. The frequency converter or envelope detector 104 performs frequency conversion or envelope detection on the output of the quadrature modulator 102 to down-convert it to a baseband frequency band (or direct current), and outputs it to the digital signal processing unit 101b. The down-converted signal may be input to the control unit 132 via the A / D converter 131. The control unit 132 calculates each correction value (for example, V R and τ) may be determined and output to the correction circuit 112.

[0079] Alternatively, the image signal measuring device may be external to the wireless device. Feedback regarding the measurement value may be transmitted from the image signal measuring device to the wireless device (for example, transmitter 100). FIG. 11 shows another exemplary configuration of transmitter 100. Transmitter 100 shown in FIG. 11 includes a receiving antenna 105 and a receiving unit 106 in addition to the configuration shown in FIG. 5. Digital signal processing unit 101b may include an analog / digital converter (A / D converter) 131 and a control unit 132 in addition to the configuration of digital signal processing unit 101 shown in FIG. 5. The receiving unit 106 receives feedback information regarding the measurement value of the image signal, which is included in the signal received via receiving antenna 105, and outputs the feedback information to digital signal processing unit 101b. The feedback information may be input to control unit 132 via A / D converter 131. Based on the input feedback information regarding the measurement value, control unit 132 calculates each correction value (for example, V R and τ) may be determined and output to the correction circuit 112.

[0080] The feedback information from the measuring device may be transmitted by a radio signal. The radio signal may be transmitted in a manner conforming to 3GPP NR, for example, using control signals in NR (such as L1 control signals, Medium Access Control (MAC), and Radio Resource Control (RRC)).

[0081] Furthermore, when measuring the image signal, the wireless device may transmit a signal (test signal) of a subcarrier corresponding to a specific frequency +ω, and may not transmit any other signals. In this case, the measuring device may determine the magnitude of the image signal by measuring the subcarriers corresponding to frequency +ω and frequency −ω. Alternatively, for example, the measuring device may instruct the wireless device in advance to transmit the test signal. This instruction may be made using a wireless signal or a 3GPP NR-compliant signal, similar to the feedback information described above.

[0082] Alternatively, for example, a wireless device may transmit a signal modulated with data, and the measuring device may estimate or determine the magnitude of the image signal based on the quality of the received signal (e.g., indicators such as SINR, BER (Bit Error Rate), BLER (Block Error Rate), and PER (Packet Error Rate)).

[0083] The measurement and determination of the I / Q offset correction value and the measurement of the image signal may be performed once when the wireless device is shipped from the factory or when it is first started up, or may be performed every time the wireless device is started up, or may be performed periodically during operation. For example, by periodically changing the correction value, transmitter 100 can appropriately suppress the image signal even if the I / Q offset changes over time due to temperature characteristics, deterioration of internal device components, etc.

[0084] Furthermore, in the correction using the determined I / Q offset correction value, the transmitter 100 may adjust either the amplitude or the timing first, and then adjust the other. Alternatively, the transmitter 100 may adjust either the amplitude or the timing.

[0085] <I / Q offset compensation with frequency characteristics> The correction value used for correcting the I / Q offset described above (for example, V R Parameters such as V and τ may be set for each frequency (e.g., frequency resource). R It may also be a function such as (ω) and τ(ω) in which the frequency ω is a variable.

[0086] For example, when the transmission frequency band is wide and the frequency characteristics of the actual I / Q offset tend to fluctuate significantly, the image signal can be suppressed by setting a correction value according to the frequency characteristics of the I / Q offset.

[0087] Furthermore, the transmitter 100 may determine the frequency granularity, which is the unit for performing the correction process, depending on the magnitude of the change in the frequency direction of the I / Q offset (for example, the amount of change). For example, the frequency granularity for performing the correction process may be set to be smaller as the amount of change in the frequency direction of the I / Q offset increases.

[0088] For example, when the amount of change in the I / Q offset is large (for example, equal to or greater than a threshold), the frequency granularity of the correction may be set to be small. For example, when the amount of change in the I / Q offset is large, the frequency granularity of the correction may be set to be in units of subcarriers. This allows the I / Q offset to be compensated for with high accuracy.

[0089] On the other hand, for example, when the amount of change in the I / Q offset is small (for example, when it is less than a threshold), the frequency granularity of the correction may be set to be large. For example, when the amount of change in the I / Q offset is small, the frequency granularity of the correction may be in units of multiple subcarriers, RB (Resource Block), or multiple RBs. This makes it possible to reduce the amount of calculation required for the correction.

[0090] Furthermore, the control signal used for the feedback may include, for example, information related to at least one of the magnitude of the image signal, the power ratio between the desired signal and the image signal (e.g., IMRR (Image Rejection Ratio)), I / Q amplitude offset, I / Q timing offset, and received signal quality (e.g., indices such as SINR, BER, BLER, and PER), or other information related to the image signal. Furthermore, these pieces of information may be notified using different fields for each frequency unit. The frequency unit may be, for example, a subcarrier unit, a unit of multiple subcarriers, an RB unit, or a unit of multiple RBs. Furthermore, the size of the frequency unit may be set according to the magnitude (amount of change) of the I / Q offset in the frequency direction. For example, if the amount of change in the I / Q offset is large (e.g., equal to or greater than a threshold), the size of the frequency unit may be set small. This allows information related to the image signal to be fed back with high accuracy. On the other hand, for example, if the amount of change in the I / Q offset is small (e.g., less than a threshold), the size of the frequency unit may be set large. This allows the overhead of the control signal to be reduced.

[0091] Additionally, the control signal used for the feedback may include information (e.g., index) about frequency resources (e.g., subcarrier, subcarrier group, RB, or RB group index) that satisfy at least one of characteristics such as "large image signal," "small IMRR," "large I / Q offset," or "poor quality of received signal," or other characteristics related to the image signal. This allows the wireless device to identify frequency resources affected by the image signal, make appropriate corrections, and reduce the overhead of the control signal.

[0092] <Other> Regarding the I / Q amplitude offset correction value, V RThe value of may be set to be greater than 1 or less than 1. For example, the amplitude offset may be corrected both when the amplitude of the I signal is greater than that of the Q signal and when it is smaller than that of the Q signal.

[0093] Also, V R The value of may be 1. That is, the transmitter 100 may have a circuit configuration that corrects the I / Q timing offset but does not correct the I / Q amplitude offset.

[0094] For the I / Q timing offset correction value, the value of τ can be either positive or negative, e.g., the timing offset can be corrected both when the I signal is lagging and when it is leading compared to the Q signal.

[0095] Also, the value of τ may be 0. In other words, transmitter 100 may have a circuit configuration that corrects I / Q amplitude offsets but does not correct I / Q timing offsets.

[0096] The embodiments of the present disclosure have been described above.

[0097] Although the microwave band, millimeter wave band, and terahertz band (or sub-terahertz band) have been described as examples of radio frequency bands, the present invention is not limited to these, and the frequency bands used for transmission or reception may be other frequency bands or combinations of these frequency bands.

[0098] Furthermore, the notation "··· part" in the above-described embodiments may be replaced with other notations such as "··· circuitry," "··· device," "··· unit," or "··· module."

[0099] (control signal) In the above embodiment, the control signal may be a PDCCH that transmits DCI of the physical layer, or may be a higher layer signal (for example, MAC or RRC). Also, the above data signal may include a higher layer signal.

[0100] (base station) In the above-described embodiments, the base station may be a TRP (Transmission Reception Point), a cluster head, an access point, an RRH (Remote Radio Head), an eNodeB (eNB), a gNodeB (gNB), a BS (Base Station), a BTS (Base Transceiver Station), a parent device, a gateway, etc. In addition, in sidelink communication, a terminal may act in place of a base station.

[0101] (uplink / downlink) Although the above embodiment has been described taking the downlink as an example, it can also be applied to the uplink PUSCH. For example, the PDCCH in the above operation example may be a PUCCH.

[0102] (Data channel / Control channel) In the above embodiments, the PDSCH or PUSCH resources may be allocated by the PDCCH or may be resources configured by a higher layer signal.

[0103] (reference signal) In the above embodiments, the reference signal (RS) is a signal known to both the base station and the mobile station, and may also be called an RS (Reference Signal) or a pilot signal. The reference signal may be a DMRS, a CSI-RS (Channel State Information - Reference Signal), a TRS (Tracking Reference Signal), a PTRS (Phase Tracking Reference Signal), an SRS (Sounding Reference Signal), or a CRS (Cell-specific Reference Signal).

[0104] (time interval) In the above embodiments, the unit of time resource is not limited to one or a combination of slots and symbols, but may be, for example, a time resource unit such as a frame, a superframe, a subframe, a slot, a time slot subslot, a minislot, or a symbol, an OFDM (Orthogonal Frequency Division Multiplexing) symbol, or an SC-FDMA (Single Carrier-Frequency Division Multiplexing) symbol, or another time resource unit. Furthermore, the number of symbols included in one slot is not limited to the number of symbols exemplified in the above embodiments, and may be another number of symbols.

[0105] (Applicable to side links) The above-described embodiment may also be applied to communication using a sidelink used for V2X (Vehicle to Everything) or terminal-to-terminal communication. In this case, the PDCCH may be a PSCCH (Physical Sidelink Control Channel), the PUSCH / PDSCH may be a PSSCH (Physical Sidelink Shared Channel), and the PUCCH may be a PSFCH (Physical Sidelink Feedback Channel).

[0106] (licensed band / unlicensed band) The above-described embodiments may also be applied to communications in licensed and unlicensed spectrum (unlicensed spectrum, shared spectrum). In the case of unlicensed spectrum, a channel access procedure (Listen Before Talk (LBT), carrier sense, Channel Clear Assessment (CCA)) may be performed before each signal transmission.

[0107] The present disclosure can be realized by software, hardware, or software linked to hardware. Each functional block used in the description of the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit, and each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may be called an IC, system LSI, super LSI, or ultra LSI.

[0108] The integrated circuit method is not limited to LSI, but may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0109] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology can be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility.

[0110] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a wireless transceiver and processing / control circuitry. The wireless transceiver may include a receiver and a transmitter, or both functions. The wireless transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0111] Communications equipment is not limited to portable or mobile equipment, but also includes non-portable or fixed equipment, devices, and systems of any kind, such as smart home devices (such as appliances, lighting equipment, smart meters or metering devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0112] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0113] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0114] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0115] A transmitter according to one embodiment of the present disclosure includes a processing circuit that uses one of transmission signals that are mapped to frequency resources symmetrical with respect to a center frequency to perform correction processing on the other of transmission signals that are mapped to the symmetric frequency resources, and a quadrature modulator that quadrature-modulates the transmission signal after the correction processing.

[0116] In one embodiment of the present disclosure, the processing circuit performs the correction process based on at least one of an amplitude and timing offset between an in-phase component and a quadrature-phase component of the transmit signal.

[0117] In one embodiment of the present disclosure, the processing circuit generates a component that cancels the offset using transmission signals that are respectively mapped to the symmetric frequency resources.

[0118] In one embodiment of the present disclosure, the processing circuit subtracts image signal components caused by the offset from the transmission signals respectively mapped to the symmetric frequency resources.

[0119] In an embodiment of the present disclosure, the processing circuit sets parameters used in the correction process for each frequency resource.

[0120] In one embodiment of the present disclosure, the processing circuit determines a frequency granularity, which is a unit for performing the correction process, according to an amount of change in the offset in the frequency domain.

[0121] In one embodiment of the present disclosure, the greater the amount of change, the smaller the frequency granularity.

[0122] In one embodiment of the present disclosure, a transmitter uses one of the transmission signals mapped to frequency resources symmetrical with respect to a center frequency to perform correction processing on the other of the transmission signals mapped to the symmetric frequency resources, and orthogonally modulates the transmission signal after the correction processing. [Industrial Applicability]

[0123] One aspect of the present disclosure is useful in wireless communication systems. [Explanation of symbols]

[0124] 100 Transmitters 101, 101a, 101b Digital signal processing unit 102 Quadrature Modulator 103 Antenna 104 Frequency converter or envelope detector 105 Receiving Antenna 106 Receiving unit 111 Modulation signal generator 112 Correction circuit 113 Real part extraction 114 Imaginary part extraction part 115 Digital / Analog Converter 121,131 Analog / Digital Converter 122,132 Control unit

Claims

1. a processing circuit that uses one of the transmission signals mapped to symmetric frequency resources with respect to a center frequency to perform correction processing on the other of the transmission signals mapped to the symmetric frequency resources; a quadrature modulator that quadrature-modulates the transmission signal after the correction processing; A transmitter comprising:

2. the processing circuit performs the correction process based on at least one of an amplitude and a timing offset between an in-phase component and a quadrature-phase component of the transmission signal. The transmitter of claim 1 .

3. the processing circuit generates a component that cancels the offset using transmission signals that are respectively mapped to the symmetric frequency resources.

3. The transmitter of claim 2.

4. The processing circuit subtracts image signal components caused by the offset from the transmission signals respectively mapped to the symmetric frequency resources.

3. The transmitter of claim 2.

5. the processing circuit sets parameters used in the correction process for each frequency resource. The transmitter of claim 1 .

6. the processing circuit determines a frequency granularity, which is a unit for performing the correction process, in accordance with a change amount of the offset in the frequency domain.

3. The transmitter of claim 2.

7. The greater the amount of change, the smaller the frequency granularity.

7. The transmitter of claim 6.

8. The transmitter is using one of the transmission signals mapped to frequency resources symmetric with respect to a center frequency to perform a correction process on the other of the transmission signals mapped to the symmetric frequency resources; quadrature-modulating the transmission signal after the correction processing; Sending method.

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