Vector decomposer, optical wireless transmission system, communication device, and vector decomposition method

Abstract

To enable generation of one set of out-phasing signals with a simple configuration.SOLUTION: A vector decomposer includes a phase rotation signal generator that generates first and second phase rotation signals whose phases are rotated by 90° in positive and negative directions, respectively, for an input signal, and a combiner that combines the input signal and the first phase rotation signal to generate a first out-phasing signal, and combines the input signal and the second phase rotation signal to generate a second out-phasing signal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a vector resolver, an optical wireless transmission system, a communication device, and a vector decomposition method.

Background Art

[0002] In the access network of a mobile network, an optical wireless transmission system using an optical fiber is arranged as a system for separately supplying radio waves at low cost to a weak electric field area such as an underground shopping mall or inside a building where radio waves from an outdoor base station are difficult to reach. The optical wireless transmission system is also called a Radio over Fiber (RoF) system. The optical wireless transmission system includes a master unit and one or more slave units arranged in a weak electric field area. The master unit and the slave units are connected to each other via an optical fiber. In the optical wireless transmission system, the master unit is also called a radio unit, and the slave unit is also called a distributed antenna unit.

[0003] As optical wireless transmission systems, a Digital RoF (DRoF) system and an Analog RoF (ARoF) system are known. In the digital RoF system, the master unit converts a baseband signal from a parallel signal to a serial signal. The baseband signal converted to a serial signal is converted from an electrical signal to an optical signal using an E / O (Electrical signal / Optical signal) converter and transmitted to the slave unit via an optical fiber. The transmitted optical signal is converted from an optical signal to an electrical signal using an O / E (Optical signal / Electrical signal) converter.

[0004] The slave unit converts the transmitted baseband signal from a serial signal to a parallel signal. Also, the slave unit uses a digital-to-analog converter (DAC) to convert the baseband signal converted to a parallel signal from a digital signal to an analog signal. Further, the slave unit uses a mixer circuit to convert the baseband signal converted to an analog signal to a high-frequency signal. The high-frequency signal is supplied to the antenna via an amplifier and a band-pass filter, and the antenna radiates the high-frequency signal into the low-voltage area.

[0005] On the other hand, in an analog RoF system, the master unit uses a DAC to convert a digital baseband signal to an analog signal, and uses a mixer circuit to convert the baseband signal converted to an analog signal to a high-frequency signal. The high-frequency signal is converted from an electrical signal to an optical signal using an E / O converter and is transmitted to the slave unit via an optical fiber. The transmitted high-frequency signal is converted from an optical signal to an electrical signal using an O / E converter. In the slave unit, the high-frequency signal is supplied to the antenna via an amplifier such as a power amplifier and a band-pass filter, and the antenna radiates the high-frequency signal into the low-voltage area.

[0006] When comparing the digital RoF system and the analog RoF system, the digital RoF system requires each slave unit to have a serial-to-parallel (S / P) converter that converts a serial signal to a parallel signal. Also, each slave unit needs to be equipped with a DAC corresponding to a broadband signal. For this reason, the power consumption in each slave unit is large and the cost is high. In contrast, since the analog RoF system does not require a DAC in the slave unit, the power consumption is low and the size can be small. On the other hand, in the analog RoF system, in order to avoid signal degradation due to distortion, an optical transceiver including a high-cost E / O converter and O / E converter with excellent linearity is required.

[0007] As a RoF system that can use a low-cost optical transceiver, a RoF system using 1-bit outphasing modulation is known. As a related technology, Patent Document 1 discloses an optical wireless transmission system using an outphasing signal. In the optical wireless transmission system described in Patent Document 1, a transmission device corresponding to the master unit generates a set of outphasing signals and quadrature-modulates the outphasing signals at an intermediate frequency. The set of quadrature-modulated outphasing signals is converted from an electrical signal to an optical signal by an E / O converter. The optical signal is transmitted to the slave unit using an optical fiber and is converted from an optical signal to an electrical signal by an O / E converter arranged on the slave unit side. The slave unit synthesizes a set of outphasing signals, converts the synthesized signal into a high-frequency signal, and radiates the high-frequency signal from an antenna.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] In the optical wireless transmission system described in Patent Document 1, the optical fiber transmits an optical signal represented as a pulse waveform. Since the pulse waveform has two values, high and low, an inexpensive general-purpose digital optical module can be used for the E / O converter and the O / E converter. In the optical wireless transmission system described in Patent Document 1, instead of an expensive dedicated analog optical module required by the analog RoF method, an inexpensive general-purpose digital optical module can be adopted, and cost reduction can be achieved.

[0010] However, in Patent Document 1, signal transmission from the slave unit to the master unit is not considered. When considering signal transmission from the slave unit to the master unit, the following steps need to be carried out in order to convert the radio frequency signal received by the antenna into an outphasing signal. (1) Convert the signal received from the antenna into a digital signal using an analog-to-digital converter (ADC). (2) Generate a set of outphasing signals from the digital signal using a digital-to-digital outphasing modulator. (3) Convert the set of outphasing signals into an analog signal using a DAC.

[0011] In the optical wireless transmission system described in Patent Document 1, in order for the slave unit to transmit a signal to the master unit, the slave unit needs to have an ADC and a DAC in addition to the digital outphasing modulator. Generally, the ADC and the DAC consume a large amount of power. For this reason, it is difficult to reduce the power consumption of the slave unit. Also, when the slave unit has an ADC and a DAC, the configuration of the slave unit becomes complicated and it is difficult to miniaturize the slave unit.

[0012] One of the objects of the present disclosure is to provide a vector decomposer, an optical wireless transmission system, a wireless communication device, and a vector decomposition method capable of generating a set of outphasing signals with a simple configuration.

Means for Solving the Problems

[0013] The vector decomposer according to the first aspect of the present disclosure includes a phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are rotated 90° in the positive and negative directions, respectively, with respect to an input signal, and a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal.

[0014] The optical wireless transmission system according to the second aspect of the present disclosure includes a master unit and a slave unit connected to the master unit via an optical transmission line. The slave unit includes an antenna, and a phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are rotated by 90° in the positive and negative directions, respectively, with respect to an input signal that is a reception signal received using the antenna, and a vector decomposer having a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal, and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal. The master unit includes a synthesizer that synthesizes the first outphasing signal and the second outphasing signal received from the slave unit via the optical transmission line and reproduces a signal corresponding to the reception signal, an analog-to-digital converter that converts the reproduced signal from an analog signal to a digital signal, and a signal processing circuit that performs signal processing on the signal converted to the digital signal.

[0015] The communication device according to the third aspect of the present disclosure includes a phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are rotated by 90° in the positive and negative directions, respectively, with respect to an input signal that is a transmission signal, a vector decomposer having a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal, and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal, first and second amplifiers that amplify the first outphasing signal and the second outphasing signal, respectively, and a synthesizer that synthesizes the amplified first outphasing signal and the amplified second outphasing signal.

[0016] The vector decomposition method according to the fourth aspect of the present disclosure generates, for an input signal, a first phase-rotated signal and a second phase-rotated signal whose phases are rotated by 90° in the positive and negative directions, respectively, synthesizes the input signal and the first phase-rotated signal to generate a first outphasing signal, and synthesizes the input signal and the second phase-rotated signal to generate a second outphasing signal.

Effect of the Invention

[0017] The vector decomposer, optical wireless transmission system, communication device, and vector decomposition method according to the present disclosure can generate a set of outphasing signals with a simple configuration.

Brief Description of the Drawings

[0018]

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Embodiments for Carrying Out the Invention

[0019] Prior to the description of the embodiments of the present disclosure, the outline of the present disclosure will be described. FIG. 1 shows a schematic configuration example of an optical wireless transmission system according to the present disclosure. The optical wireless transmission system 10 includes a master unit 20 and a slave unit 30. The master unit 20 and the slave unit 30 are mutually connected via an optical transmission line. The slave unit 30 includes an antenna 31 and a vector decomposer 32. The vector decomposer 32 includes a phase rotation signal generator 33 and a synthesizer 34.

[0020] In the slave unit 30, the received signal received by the antenna 31 is input to the vector decomposer 32. The phase rotation signal generator 33 generates a first phase rotation signal and a second phase rotation signal whose phases are rotated by 90° in the positive and negative directions, respectively, with respect to the input signal which is the received signal. The synthesizer 34 synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal S1. Also, the synthesizer 34 synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal S2.

[0021] The master unit 20 includes a synthesizer 21, an ADC 22, and a signal processing circuit 23. The master unit 20 receives the first outphasing signal S1 and the second outphasing signal S2 from the slave unit 30 via an optical transmission line. The synthesizer 21 synthesizes the first outphasing signal S1 and the second outphasing signal S2 to reproduce a signal corresponding to the received signal. The ADC 22 converts the reproduced received signal from an analog signal to a digital signal. The signal processing circuit 23 performs signal processing on the received signal converted to a digital signal.

[0022] In the present disclosure, in the present embodiment, the vector decomposer 32 generates first and second phase rotation signals having a 90° phase difference in the positive and negative directions with respect to the input signal. Further, the vector decomposer 32 synthesizes the input signal with the first phase rotation signal and the second phase rotation signal, respectively, to generate a set of outphasing signals. The signal obtained by synthesizing the set of outphasing signals generated by the vector decomposer 32 has phase information and amplitude information corresponding to the phase information and amplitude information of the input signal. By using such a vector decomposer 32, the slave unit 30 can decompose the received signal into a set of outphasing signals while remaining an analog signal. For this reason, the slave unit 30 may not have an ADC, and can generate outphasing signals with a simple configuration. Also, the optical wireless transmission system 10 can transmit and receive signals in an outphasing manner from the slave unit 30 to the master unit 20 while using the slave unit 30 having a simple configuration.

[0023] FIG. 2 is a block diagram showing a schematic configuration example of a communication device according to the present disclosure. In this example, the communication device 40 includes a vector decomposer 41, a first amplifier 42, a second amplifier 43, and a synthesizer 44. The configuration of the vector decomposer 41 is the same as that of the vector decomposer 32 shown in FIG. 1. In this configuration, the vector decomposer 41 generates a first outphasing signal S1 and a second outphasing signal S2 from the transmission signal.

[0024] The first amplifier 42 amplifies the first outphasing signal S1. The second amplifier 43 amplifies the second outphasing signal S2. The synthesizer 44 synthesizes the amplified first outphasing signal S1 and the amplified second outphasing signal S2. The synthesized signal corresponds to the amplified transmission signal. The synthesized signal output by the synthesizer 44 is radiated by, for example, an antenna.

[0025] In the communication device 40 shown in FIG. 2, a transmission signal can be amplified by an outphasing method using a vector decomposer 41 having a simple configuration. Also, in the communication device 40 shown in FIG. 2, by using the vector decomposer 41, the first outphasing signal S1 and the second outphasing signal S2 can be generated without converting the input analog signal into a digital signal. Therefore, in the configuration shown in FIG. 2, a DAC is not required between the first amplifier 42 and the second amplifier 43 and the vector decomposer 41 in the communication device 40. Also, an ADC is not required in the front stage of the vector decomposer 41. For this reason, the configuration of the communication device 40 can be simplified.

[0026] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the following description and drawings are appropriately omitted and simplified for clarity of explanation. Also, in each drawing, the same elements and similar elements are denoted by the same reference numerals, and duplicate explanations are omitted as necessary.

[0027] The first embodiment will be described. FIG. 3 shows a configuration example of a first optical wireless transmission system according to the present disclosure. The optical wireless transmission system 100 shown in FIG. 3 includes a master unit 110 and a slave unit 150. The master unit 110 is a network device disposed, for example, in a concentration station. The slave unit 150 is a network device disposed, for example, in a weak electric field area. In the present embodiment, the optical wireless transmission system 100 is a system in which an optical signal is transmitted between the master unit 110 and the slave unit 150 in a 1-bit outphasing method. Note that in FIG. 3, only one slave unit 150 is illustrated, but the number of slave units 150 is not limited to one. The optical wireless transmission system 100 may have a plurality of slave units 150 for one master unit 110. The master unit 110 corresponds to the master unit 20 shown in FIG. 1. The slave unit 150 corresponds to the slave unit 30 shown in FIG. 1.

[0028] The master unit 110 includes a digital baseband unit (DBB: Digital Base Band) 111, a digital outphasing modulator 112, DACs 113a and 113b, rectangularizers 114a and 114b, a synthesizer 121, a band-pass filter 122, and an ADC 123. The digital baseband unit 111 performs baseband signal processing in the master unit 110. The digital baseband unit 111 generates a digital baseband signal in signal transmission. The digital baseband unit 111 outputs the I component (in-phase component) / Q component (orthogonal component) of the digital baseband signal to the digital outphasing modulator 112. The digital baseband unit 111 can be implemented using hardware such as a digital signal processor (DSP).

[0029] The digital outphasing modulator 112 generates a set of outphasing signals S 1t and S 2tGenerate. The digital outphasing modulator 112 includes a digital signal processing circuit and a quadrature modulator. The digital outphasing modulator 112 converts the I component / Q component of the digital baseband signal into an outphasing signal pair of a predetermined frequency. The digital outphasing modulator 112 can be implemented using hardware such as, for example, a digital signal processor (DSP).

[0030] Figure 4 shows S 1t (t), S 2t (t), and the vector diagram of S org (t). The digital outphasing modulator 112 converts the original signal vector S org that is amplitude - modulated and phase - modulated into a pair of outphasing signal vectors S 1t and S 2t that have a constant amplitude and only phase modulation. In the following description, it is assumed that the maximum value of the amplitude of the signal vector S org is A max = 2.

[0031] The outphasing signals S 1t (t) and S 2t (t) at each time t are expressed by the following formula using the I(t) and Q(t) that are wireless orthogonal baseband signals. TIFF2025099209000002.tif5683In the above formula, fc represents the carrier frequency, and A max represents the maximum value of the amplitude A(t). When A max = 2, the amplitudes of the outphasing signals S 1t (t) and S 2t (t) are 1. The signal S c of the original carrier frequency f org (t) can be reproduced by synthesizing S 1t (t) and S 2t (t). That is, the following formula 5 holds. TIFF2025099209000003.tif5110

[0032] DACs 113a and 113b each convert outphasing signals S 1t and S 2t from digital signals to analog signals. Rectifiers 114a and 114b each convert the outphasing signals S 1t and S 2t that have been converted to analog signals into rectangular wave signals with a pulse waveform. Rectifiers 114a and 114b each compare the outphasing signals S 1t and S 2t with an amplitude zero value, and based on the comparison result, rectangularize the outphasing signals S 1t and S 2t .

[0033] As shown in the above formulas (1) and (2), the outphasing signal is a sine wave signal with a constant amplitude. By rectangularizing the outphasing signal through zero value comparison, rectifiers 114a and 114b can convert the outphasing signal into a pulse waveform without losing information. The pulse waveform corresponds to a waveform in which harmonic components of the outphasing signal itself are added to the outphasing signal. This means that the outphasing signal can be regenerated from the rectangularized signal by using a filter that removes harmonics.

[0034] The wavelength division multiplexing (WDM) E / O converter 131 (hereinafter also simply referred to as the E / O converter) converts the rectangularized outphasing signals S 1t and S 2t from electrical signals to optical signals. At this time, the E / O converter 131 converts the outphasing signals S 1t and S 2t into optical signals with different wavelengths. The optical fiber 132 is an optical transmission path, and transmits the outphasing signals S 1t and S 2t that have been converted to optical signals to the slave unit 150. The wavelength division multiplexing O / E converter 133 (hereinafter also simply referred to as the O / E converter) converts the transmitted outphasing signals S 1t and S 2tConvert it from an optical signal to an electrical signal.

[0035] The slave unit 150 includes a transmission unit 151, a reception unit 152, a transmission / reception switching circuit 153, and an antenna 154. In the slave unit 150, the outphasing signals S 1t and S 2t that have been converted into electrical signals by the O / E converter 133 are input to the transmission unit 151. The transmission unit 151 includes a synthesizer 161, a band-pass filter 162, and an amplifier 163. The synthesizer 161 synthesizes the outphasing signals S 1t and S 2t to reproduce a radio frequency signal corresponding to the signal S org . The synthesizer 161 outputs the reproduced radio frequency signal to the band-pass filter 162.

[0036] The band-pass filter 162 outputs a signal of a predetermined frequency component among the reproduced radio frequency signals to the amplifier 163. The band-pass filter 162 removes, for example, harmonic components generated due to rectification among the frequency components included in the reproduced radio frequency signal. The amplifier 163 amplifies the input radio frequency signal to a desired power. The amplifier 163 supplies the radio frequency signal to the antenna 154 via the transmission / reception switching circuit 153. The antenna 154 radiates the radio frequency signal, for example, to a low-voltage area.

[0037] Note that the digital outphasing modulator 112 may generate an outphasing signal at an intermediate frequency. In that case, in the transmission unit 151, the intermediate frequency signal reproduced by the synthesizer 161 may be up-converted to a radio frequency signal.

[0038] The antenna 154 receives radio frequency signals transmitted by wireless communication devices such as user equipment existing in a low-voltage area. The radio frequency signal received by the antenna 154 is also called a received signal. The high-frequency radio frequency signal received by the antenna 154 is input to the reception unit 152 via the transmission / reception switching circuit 153. The antenna 154 corresponds to the antenna 31 shown in FIG. 1.

[0039] The receiving unit 152 includes an amplifier 171, an analog vector decomposer 172, and rectifiers 173a and 173b. The amplifier 171 amplifies a weak radio frequency signal. The amplifier 171 outputs the amplified radio frequency signal to the analog vector decomposer 172. The analog vector decomposer 172 generates a set of outphasing signals from the input radio frequency signal. In the present embodiment, the analog vector decomposer 172 performs outphasing modulation on the radio frequency signal input as an analog signal without converting it into a digital signal, and generates a set of outphasing signals S1 and S2.

[0040] FIG. 5 shows the input signal S in to the analog vector decomposer 172 and the generated outphasing signals S1 and S2. The outphasing signals S1 and S2 are signals with a constant amplitude regardless of the magnitude of the input S in . The vector sum of the outphasing signals S1 and S2 corresponds to twice the amplitude of the input signal S in in terms of amplitude. The phase of the vector sum of the outphasing signals S1 and S2 is the same as the phase of the input signal S in . Note that since the input signal S in corresponds to the value obtained by multiplying the aforementioned signal S org by 0.5, the following relational expression holds from Equation (5). TIFF2025099209000004.tif6152

[0041] The vector angles of the outphasing signals S1 and S2 with respect to the input signal S in are θ and -θ shown in Equation (3), respectively. This vector angle becomes smaller as the amplitude of S in is larger, that is, as A(t) is larger. FIG. 5 shows a set of specific values of S in and θ at representative points.

[0042] Figure 6 shows a configuration example of the analog vector decomposer 172. The analog vector decomposer 172 includes a phase rotator 181, an amplitude adjuster 182, an inversion signal generator 183, and synthesizers 184 and 185. Note that the operation of the analog vector decomposer 172 corresponds to an analog vector decomposition method. The analog vector decomposer 172 corresponds to the vector decomposer 32 shown in FIG. 1.

[0043] The phase rotator 181 generates a signal S in whose phase is advanced by 90° with respect to the input signal S 90 . The amplitude adjuster 182 adjusts the amplitude of the signal S 90 to a desired value and generates a signal S op90 . The inversion signal generator 183 generates a signal -S op90 with its sign inverted with respect to S op90 . The inversion signal generator 183 may generate the signal -S op90 with its sign inverted, for example, by differentializing a signal line. Alternatively, the inversion signal generator 183 may generate the signal -S op90 with its sign inverted by using an inversion circuit. The signal S 90 and the signal S op90 are also called the first phase rotation signals. The signal -S 90 and the signal -S op90 are also called the second phase rotation signals. The phase rotator 181 and the inversion signal generator 183 correspond to the phase rotation signal generator 33 shown in FIG. 1.

[0044] The synthesizer 184 vectorially synthesizes the input signal S in and the signal S op90 . The synthesizer 184 outputs, as an outphasing signal S1, the signal obtained by vectorially synthesizing the input signal S in and the signal S op90 . The synthesizer 185 vectorially synthesizes the input signal S in and the signal -S op90 . The synthesizer 185 vectorially synthesizes the input signal S in and the signal -S op90The signal obtained by vectorially synthesizing the above is output as an outphasing signal S2. The outphasing signal S1 is also called the first outphasing signal. The outphasing signal S2 is also called the second outphasing signal. The synthesizers 184 and 185 correspond to the synthesizer 34 shown in FIG. 1.

[0045] Note that in the above, the analog vector decomposer 172 generates a signal S in whose phase is advanced by 90° with respect to the input signal S 90 in the phase rotator 181, and the amplitude of the signal S 90の is adjusted in the amplitude adjuster 182. However, the present embodiment is not limited to this. The order of the phase rotator 181 and the amplitude adjuster 182 may be reversed. That is, the analog vector decomposer 172 may adjust the amplitude of the input signal S in in the amplitude adjuster 182, and then generate, in the phase rotator 181, a signal whose phase is advanced by 90° from the input signal with the adjusted amplitude, that is, a signal S in with respect to the input signal S

[0046] FIG. 7 shows the generation process of the outphasing signal in the analog vector decomposer 172. The phase rotator 181 generates, from the input signal S in a signal having a 90° phase difference from the input signal S in , that is, a signal S 90 which is an orthogonal signal. The signal S 90 is also called the first phase rotation signal. The amplitude adjuster 182 adjusts the signal S in according to the amplitude of the input signal S 90 . The amplitude adjuster 182 adjusts the amplitude of the signal S op90 so that the amplitude of the outphasing signal generated by vectorially synthesizing the input signal and the signal S 90 after amplitude adjustment becomes a predetermined amplitude, for example, "1". Specifically, the amplitude adjuster 182 adjusts the amplitude of the signal S op90 so that the amplitude value of the output signal S 90 becomes the value represented by the following formula. TIFF2025099209000005.tif657

[0047] The synthesizer 184 vector-synthesizes the input signal S in and the signal S op90 The synthesizer 185 vector-synthesizes the input signal S in and the signal -S op90 Since the input signal S in and the signal S op90 are orthogonal to each other, the absolute value of the vector signal after vector synthesis is equal to the sum of the squares of the input signal S in and the signal S op90 and is equal to 1. Similarly, since the input signal S in and the signal -S op90 are orthogonal to each other, the absolute value of the vector signal after vector synthesis is equal to the sum of the squares of the input signal S in and the signal -S op90 and is equal to 1. If the phase difference between the signal after vector synthesis of the input signal S in and the signal S op90 and the input signal S in is θ, then the phase difference between the signal after vector synthesis of the input signal S in and the signal -S op90 and the input signal S in is -θ. As is clear from FIG. 7, the following equation also holds. TIFF2025099209000006.tif547

[0048] The signal obtained by vector-synthesizing the output signal of the synthesizer 184 and the output signal of the synthesizer 185 is the signal obtained by vector-synthesizing S in ×2, S op90 and -S op90 and is equal to S in ×2. This indicates that the signals output from the synthesizers 184 and 185 are signals equivalent to the outphasing signals S 1t and S 2t shown in equations (1) and (2), respectively. Also, the phase difference θ between the signal obtained by vector-synthesizing the input signal S in and the signal S op90 and the input signal S in is the same as θ shown in equations (1) and (2).

[0049] FIG. 8 shows the relationship between the input signal S in and the outphasing signals S1 and S2. In FIG. 8, as a representative example, for each case where the back-off values of the amplitude of the input signal S in are 20 dB, 6 dB, 3 dB, and 1.25 dB, the specific amplitude values of S op90 are described together with the vector diagram.

[0050] FIG. 9 shows a configuration example of the amplitude adjuster 182. The amplitude adjuster 182 includes a square-law device 191, a limiter 192, a differentiator 193, and a square-root device 194. Here, the signal S 90 input to the amplitude adjuster is assumed to be represented by Acos(ωt + φ) with ω = 2πfc. The square-law device 191 squares the amplitude of the input signal and outputs it. That is, the square-law device 191 amplifies the amplitude of the input signal S 90 to the square of A. The limiter 192 saturates the input signal and outputs a signal with an amplitude of "1". The square-law device 191 realizes a constant amplitude of 1.

[0051] The differentiator 193 outputs the difference between the output signal of the square-law device 191 and the output signal of the limiter 192. The differentiator 193 includes a differential circuit. The differential circuit outputs a differential signal between the output signal of the square-law device 191 input to one of the differential input terminals and the output signal of the limiter 192 input to the other differential input terminal. The amplitude of the differential signal output by the differentiator 193 is 1 - A 2 . Here, it is assumed that A ≤ 1. The differentiator 193 outputs the differential signal to the square-root device 194.

[0052] The square-root device 194 takes the square root of the amplitude of the signal input from the differentiator 193 and outputs it. The square-root device 194 outputs the signal with the amplitude squared as the signal S op90 with the amplitude adjusted. The amplitude of the signal output by the square-root device 194 is (1 - A 2 ) 1 / 2 . The input signal S in to the analog vector resolver 172 and the signal S 90Since the amplitudes are equal, the signal S with adjusted amplitude op90 satisfies the relationship shown in Equation (7) with respect to the input signal S in .

[0053] FIG. 10 shows a configuration example of the amplitude squarer 191. The amplitude squarer 191 includes an amplitude detector 201 and a gain variable amplifier 202. The amplitude detector 201 detects the amplitude A of the input signal. The amplitude detector 201 can be realized using, for example, a diode detection circuit. The amplitude detector 201 outputs the detected amplitude A to the gain variable amplifier 202 as a gain control signal. The gain variable amplifier 202 amplifies the input signal at an amplification rate according to the gain control signal. The gain variable amplifier 202 amplifies the signal such that the amplitude of the output signal is proportional to the square of the detected amplitude A. The proportionality constant can be adjusted as a circuit constant, and in this embodiment, the proportionality constant is set to 1.

[0054] FIG. 11 shows a configuration example of the amplitude 0.5 power calculator 194. The amplitude 0.5 power calculator 194 includes an amplitude detector 211 and a gain variable I-V converter 212. The amplitude detector 211 detects the amplitude A of the input signal. The amplitude detector 211 can be realized using, for example, a diode detection circuit. The amplitude detector 211 outputs a control signal corresponding to the magnitude of the detected amplitude A to the gain variable I-V converter 212. The gain variable I-V converter 212 changes the amplitude of the output signal according to the control signal input from the amplitude detector 211.

[0055] FIG. 12 shows a configuration example of the gain-variable I-V converter 212. The gain-variable I-V converter 212 includes a current source 215, an inductor 216, a field effect transistor (FET) 217, and capacitors 218 and 219. As the FET 217, a transistor such as a MOS (Metal Oxide Semiconductor) FET is used, for example. The FET 217 is diode-connected and connected to the current source 215 via the inductor 216. The gate terminal and the drain terminal of the FET 217 are short-circuited, and the output signal of the differentiator 193 (see FIG. 9) is input to the drain terminal of the FET 217 via the capacitor 218. The gain-variable I-V converter 212 outputs a signal whose amplitude is squared to 0.5 from the drain terminal of the FET 217 via the capacitor 219.

[0056] In the gain-variable I-V converter 212, the current (Iin) of the output signal of the differentiator 193 is input to the drain terminal of the diode-connected FET, and the voltage Vout appearing at the same terminal is output as the output signal. For the FET 217, the following relational expression holds between the drain current Id and the gate voltage Vg. TIFF2025099209000007.tif667 Here, k is a constant, and Vth is the threshold voltage of the FET 217. By differentiating Vg with respect to Id, the I-V conversion gain Gcon is obtained. TIFF2025099209000008.tif671 The above equation means that the conversion gain of the gain-variable I-V converter 212 is proportional to the -0.5 power of Id.

[0057] In the amplitude square root multiplier 194 shown in FIG. 12, the DC component of the current Id output from the current source 215 is controlled according to the amplitude A detected by the amplitude detector 211 (see FIG. 11). By doing so, the I-V conversion gain can be made proportional to the -0.5 power of the amplitude A. The amplitude value of the output of the amplitude square root multiplier 194 is proportional to the product of the amplitude A of the input signal and the I-V conversion gain. That is, the amplitude value of the output of the amplitude square root multiplier 194 is proportional to the 0.5 power of the amplitude A. The proportionality constant can be adjusted as a circuit constant. In the present embodiment, the proportionality constant is set to 1.

[0058] FIG. 13 shows a configuration example of the phase rotator 181. The phase rotator 181 includes a quadrature demodulator 221, a low-pass filter 222, and a quadrature modulator 223. The quadrature demodulator 221 includes mixer circuits corresponding to the I component and the Q component, and quadrature demodulates the input signal S in . The low-pass filter 222 passes the low-frequency components of the demodulated I-component signal I(t) and Q-component signal Q(t), respectively. The quadrature modulator 223 includes mixer circuits corresponding to the I component and the Q component, and a synthesizer that synthesizes the outputs of the mixer circuits, and quadrature modulates the I-component signal I(t) and the Q-component signal Q(t). The phase difference between the local signal used in the quadrature demodulator 221 and the local signal used in the quadrature modulator 223 is 90°. With this configuration, the phase rotator 181 can output a signal having a 90° phase difference from the input signal.

[0059] FIG. 14 shows another configuration example of the phase rotator 181. In this example, the phase rotator 181 is configured as an RC polyphase filter 225 including a resistor R and a capacitor C. The RC polyphase filter 225 can output signals having phase differences of 0°, 90°, 180°, and 270° with respect to the input signal, respectively. The phase rotator 181 outputs a signal having a 90° phase difference from the input signal among the four signals. In the configuration of the analog vector decomposer 172 shown in FIG. 6, the input signal S is input to the synthesizers 184 and 185 inIt is branched and input. When the RC polyphase filter 225 is used for the phase rotators 181, signals with a phase difference of 0° among the output signals of the RC polyphase filter 225 may be input to the synthesizers 184 and 185.

[0060] Returning to FIG. 3, the rectangularizers 173a and 173b rectangularize the outphasing signals S1 and S2 output from the analog vector decomposer 172, respectively. The method of rectangularization in the rectangularizers 173a and 173b may be the same as the method of rectangularization in the rectangularizers 114a and 114b of the master unit 110.

[0061] The wavelength division E / O converter 135 converts the rectangularized outphasing signals S1 and S2 output from the rectangularizers 173a and 173b from an electrical signal to an optical signal. At this time, the E / O converter 135 converts the outphasing signals S1 and S2 into optical signals with different wavelengths. The optical fiber 136 transmits the outphasing signals S1 and S2 converted into optical signals to the master unit 110. The wavelength division multiplexed O / E converter 137 converts the outphasing signals S1 and S2 from an optical signal to an electrical signal.

[0062] In the master unit 110, the synthesizer 121 synthesizes the outphasing signals S1 and S2 and reproduces a signal corresponding to the received signal input to the analog vector decomposer 172. The synthesizer 121 corresponds to the synthesizer 21 shown in FIG. 1.

[0063] The band - pass filter 122 outputs a signal of a predetermined frequency component among the input reproduced received signals, that is, radio - frequency signals, to the ADC 123. The band - pass filter 162 removes, for example, harmonic components generated due to rectification among the frequency components included in the reproduced radio - frequency signal. The ADC 123 converts the radio - frequency signal from an analog signal to a digital signal. The ADC 123 outputs the radio - frequency signal converted into a digital signal to the digital base - band unit 111. The ADC 123 corresponds to the ADC 22 shown in FIG. 1. The digital base - band unit 111 corresponds to the signal processing circuit 23 shown in FIG. 1.

[0064] In the present embodiment, the analog vector resolver 172 generates a set of out - phasing signals S1 and S2 from the received signal which is an analog signal. The analog vector resolver 172 can generate a set of out - phasing signals S1 and S2 without converting the received signal which is an analog signal into a digital signal. Since the analog vector resolver 172 can convert the received signal into a set of out - phasing signals S1 and S2 while keeping the received signal as an analog signal, it is not necessary to convert the received signal into a digital signal along with the conversion into the out - phasing signals. Therefore, the analog vector resolver 172 can convert the received signal into a set of out - phasing signals S1 and S2 with a simple configuration.

[0065] In the present embodiment, the slave unit 150 generates an out - phasing signal in the receiving unit 152 by using the analog vector resolver 172. Therefore, the slave unit 150 does not need to have an ADC that converts the received signal into a digital signal and a DAC that converts the generated out - phasing signal into an analog signal. Accordingly, the present embodiment can simplify the configuration of the slave unit 150 compared with the case where the received signal is converted into a digital signal, the out - phasing signal is generated by digital signal processing, and the generated out - phasing signal is converted into an analog signal. In the present embodiment, the slave unit 150 does not require an ADC and a DAC that consume a large amount of power. Therefore, the present embodiment enables miniaturization and power saving of the receiving unit 152.

[0066] Next, a second embodiment will be described. FIG. 15 shows another configuration example of the analog vector decomposer according to the present disclosure. The analog vector decomposer 172a shown in FIG. 15 can be used in place of the analog vector decomposer 172 in the receiving unit 152 of the slave unit 150 shown in FIG. 3. The analog vector decomposer 172a shown in FIG. 15 includes a phase rotator 181, an inversion signal generator 183, synthesizers 184 and 185, an amplitude fixer 186, and limiters 187 and 188.

[0067] The phase rotator 181 generates a signal S in whose phase is advanced by 90° with respect to the input signal S 90 . The amplitude fixer 186 sets the amplitude of the signal S 90 to a predetermined amplitude and generates S’ op90 whose amplitude is fixed to the predetermined amplitude. The amplitude fixer 186 includes, for example, a limiter 192 shown in FIG. 9 and a gain variable amplifier 202 shown in FIG. 10. In the amplitude fixer 186, the limiter and the gain variable amplifier are connected in series. The limiter amplifies the input signal S in to the saturation state to set the amplitude of the input signal S in to 1. The amplification factor of the gain variable amplifier is set to B, and the amplitude of the input signal S in with an amplitude of 1 is set to B. With such a configuration, the amplitude fixer 186 can fix the amplitude of the output S’ op90 to B regardless of the magnitude of the amplitude of the input signal S in .

[0068] The inversion signal generator 183 generates a signal -S’ op90 obtained by inverting the sign of the signal S’ op90 with a fixed amplitude. The inversion signal generator 183 may generate the sign-inverted signal -S’ op90 by, for example, differentiating the signal line. Alternatively, the inversion signal generator 183 may generate the sign-inverted signal -S’ op90 using an inversion circuit.

[0069] The synthesizer 184 combines the input signal S in and the signal S’op90 perform vector synthesis with. The limiter 187 receives the input signal S in and the signal S’ op90 to perform vector synthesis, and amplifies the synthesized signal until its amplitude saturates to generate a pseudo outphasing signal S’1 with an amplitude of 1. The synthesizer 185 performs vector synthesis on the input signal S in and the signal -S op90 to perform vector synthesis. The limiter 188 receives the input signal S in and the signal -S’ op90 to perform vector synthesis, and amplifies the synthesized signal until its amplitude saturates to generate a pseudo outphasing signal S’2 with an amplitude of 1. Note that in this embodiment, the order of the phase rotator 181 and the amplitude fixer 186 may be interchanged.

[0070] FIG. 16 shows the operation of the analog vector decomposer 172a in a vector diagram. The amplitude fixer 186 outputs a signal S’ in that has a 90° phase difference from the input signal S and a constant amplitude. op90 The amplitude of the signal S’ op90 is constant and does not depend on the amplitude of the input signal S in . In the example of FIG. 16, |S’ op90 | = 0.5. The synthesizer 184 performs vector synthesis on the input signal S in and the signal S’ op90 . The limiter 187 sets the amplitude of the output signal of the synthesizer 184 to “1” to generate a pseudo outphasing signal S’1. The synthesizer 185 performs vector synthesis on the input signal S in and the signal -S’ op90 . The limiter 188 sets the amplitude of the output signal of the synthesizer 185 to “1” to generate a pseudo outphasing signal S’2. FIG. 16 shows the pseudo outphasing signals S’1 and S’2 for some representative input signals S in with different amplitudes.

[0071] Here, in this embodiment, the synthesized signal S’ in obtained by synthesizing the pseudo outphasing signals S’1 and S’2 does not match the input signal S in except for specific cases. The synthesized signal S’in Assuming that the phase angle between the pseudo outphasing signal S’1 is θ’, considering that the amplitude of the pseudo outphasing signal S’1 is 1, the following equation holds. TIFF2025099209000009.tif568 Also, θ’ is equal to the phase angle between the composite signal of the input signal S in and S’ op90 and the input signal S in Therefore, the following equation holds. TIFF2025099209000010.tif567

[0072] From the above equations (11) and (12), the following equation holds. TIFF2025099209000011.tif1394 Also, from the above equations (11) and (12), the following equation (13-2) holds. TIFF2025099209000012.tif597 Here, |S’ op90 | is the amplitude of the output signal of the amplitude fixer 186 and is arbitrarily set.

[0073] Regarding the above equation (13-1) as a function f of |S in | and the equation (13-2) as a function g of |S’ in |, g is the inverse function of f, and g·f(x)=x holds. Note that for the input signal S in and the composite signal S’ in , the phases are equal and only the amplitudes are different. Considering this point, from the equations (13-1) and (13-2), the following relationship holds. TIFF2025099209000013.tif1990

[0074] FIG. 17 shows a configuration example of the digital baseband unit 111 included in the master unit 110. In FIG. 17, the bandpass filter 122 shown in FIG. 3 is not shown. In this example, the digital baseband unit 111 has a correction circuit (first correction circuit) 124. In the master unit 110, the synthesizer 121 synthesizes the pseudo outphasing signals S’1 and S’2 to generate a composite signal S’ in .

[0075] ADC123 converts the composite signal S’ in from an analog signal to a digital signal. The correction circuit 124 receives the composite signal S’ in converted into a digital signal. The correction circuit 124 corrects the composite signal S’ in based on the composite signal S’ op90 and the fixed amplitude |S’ in | set by the amplitude fixer 186, and reproduces the input signal S in . The correction circuit 124 executes, for example, the operation of the above formula (14-2) to generate the input signal S in from the composite signal S’ in .

[0076] Note that the fixed amplitude |S’ op90 | is equal to the set value B of the output amplitude of the amplitude fixer 186 included in the analog vector decomposer 172a. The input signal S in of the analog vector decomposer 172a is subjected to the conversion of the formula (14-1) by the analog vector decomposer 172a and then subjected to the conversion of the formula (14-2) by the correction circuit 124. The input signal S in undergoes the conversion of the formulas (13-1) and (13-2) with respect to the amplitude. Since both formulas are in an inverse function relationship, the output amplitude of the correction circuit 124 is equal to the amplitude of the input signal S in . Considering that the phase information is not affected by the conversion action in each block and is preserved, the output of the correction circuit 124 means reproducing the input signal S in .

[0077] FIG. 18 shows the input / output characteristics of the correction circuit 124. In FIG. 18, the horizontal axis represents the magnitude, i.e., the amplitude, of the composite signal S’ in . The vertical axis represents the amplitude of the input signal S in . In FIG. 18, for the four values of 0.25, 0.5, 0.75, and 1 as the value of |S’ op90 |, the S’ in -S in curves are shown.

[0078] Note that the correction circuit 124 does not necessarily have to perform the calculation of Equation (14-2) exactly. The correction circuit 124 performs the calculation using an equation that approximates the curve shown in FIG. 18 according to the value of |S’ op90 |, and may reproduce the input signal S in . In this case, the calculation can be simplified while maintaining the accuracy of the reproduced input signal. When the signal accuracy required for the reproduced input signal is low, the correction circuit 124 does not have to perform the calculation for correction. In other words, when the signal accuracy required for the reproduced input signal is low, the digital baseband unit 111 may not have a correction circuit.

[0079] In the present embodiment, in the analog vector decomposer 172a, the amplitude fixer 186 sets the amplitude of the signal S’ op90 to a constant amplitude regardless of the amplitude of the input signal. In the present embodiment, the analog vector decomposer 172a does not have to adjust the amplitude of the signal S’ op90 according to the amplitude of the input signal, and the implementation of the analog vector decomposer 172a becomes easier compared to the first embodiment in which amplitude adjustment is performed. The digital baseband unit 111 of the master unit 110 has a correction circuit 124. The amplitude of the signal obtained by vector-synthesizing the pseudo outphasing signals generated by the analog vector decomposer 172a does not match the amplitude of the input signal. In the correction circuit 124, the amplitude of the input signal can be reproduced by correcting the signal vector-synthesized using the inverse function of the input-output function of the analog vector decomposer 172a.

[0080] Subsequently, a third embodiment will be described. FIG. 19 shows a configuration example of a second optical wireless transmission system according to the present disclosure. In the optical wireless transmission system 100a shown in FIG. 19, the transmission unit of the master unit 110a has an analog vector decomposer 127. An analog vector decomposer having the same configuration as the analog vector decomposer 172 described in the first embodiment is used for the analog vector decomposer 127. Alternatively, an analog vector decomposer having the same configuration as the analog vector decomposer 172a described in the second embodiment may be used for the analog vector decomposer 127.

[0081] In this embodiment, the digital baseband unit 111 has a function of quadrature modulating a baseband signal. When transmitting a signal, the digital baseband unit 111 outputs the quadrature modulated baseband signal to the DAC 126. The DAC 126 converts the input quadrature modulation signal from a digital signal to an analog signal. The analog vector decomposer 127 generates a set of outphasing signals S1 and S2 from the quadrature modulation signal converted into an analog signal by the DAC 126. The signal input to the analog vector decomposer 127 is also called a transmission signal. The generation of the outphasing signals S1 and S2 may be the same as the generation of the outphasing signals S1 and S2 in the analog vector decomposer 172 disposed in the receiving unit 152 of the slave unit 150.

[0082] The rectifiers 114a and 114b convert the outphasing signals S1 and S2 output from the analog vector decomposer 127 into rectangular wave signals of pulse waveforms. The outphasing signals S1 and S2 are transmitted to the slave unit 150 via the wavelength division multiplexing E / O converter 131, the optical fiber 132, and the wavelength division multiplexing O / E converter 133. The operation of the transmitting unit 151 in the slave unit 150 and the operations of the master unit 110 and the slave unit 150 when receiving a radio frequency signal may be the same as the operations described in the first embodiment or the operations described in the second embodiment.

[0083] In this embodiment, the master unit 110 uses the analog vector decomposer 127 to convert the transmission signal into a set of outphasing signals S1 and S2. Compared with the first embodiment, in the configuration shown in FIG. 3, in order to convert each of the set of outphasing signals S1 and S2 into an analog signal, the master unit 110 has two DACs 113a and 113b in the transmitting unit. In contrast, in this embodiment, the master unit 110 only needs to have one DAC 126 for converting the transmission signal into an analog signal. Therefore, in this embodiment, the number of DACs in the master unit 110 can be reduced from two to one.

[0084] In addition, in the master unit 110, when an analog vector decomposer similar to the analog vector decomposer 172a (see FIG. 15) is used, as described above, the composite signal obtained by vector synthesizing the pseudo outphasing signals generally does not match the input signal S in When an analog vector decomposer having the same configuration as the analog vector decomposer 172a (see FIG. 15) is used, the digital baseband unit 111 may have a correction circuit (second correction circuit) that corrects the transmitted signal.

[0085] FIG. 20 shows a configuration example of a part of the transmission unit of the master unit 110. In this example, an analog vector decomposer similar to the analog vector decomposer 172a is used for the analog vector decomposer 127. The analog vector decomposer 127 generates the pseudo outphasing signals S'1 and S'2 described in the second embodiment.

[0086] The digital baseband unit 111 has a correction circuit 125. The correction circuit 125 corrects the amplitude of the transmission signal input to the analog vector decomposer 172 according to the amplitude of the transmission signal and a predetermined amplitude. The correction circuit 125 corrects the digital baseband signal so that, for example, the amplitude of the signal obtained by vector synthesizing the pseudo outphasing signals S'1 and S'2 is the same as the amplitude of the transmission signal. Specifically, the correction circuit 125 uses the function g shown in Equation (13-2) to correct the input signal S in to the signal S'' in The corrected signal S'' in is input to the analog vector decomposer 127 via the DAC 126.

[0087] Note that the amplitude of the signal S in input to the correction circuit 125 is converted by the function g of Equation (13-2) in the correction circuit 125 and then undergoes conversion by the function f of Equation (13-1) in the analog vector decomposer 127. Therefore, the amplitude of the signal obtained by synthesizing the pseudo outphasing signals S'1 and S'2 output by the analog vector decomposer 127 is f·g(|S inbecomes (|). As described above, since f and g are in an inverse function relationship, in the signal obtained by synthesizing the pseudo outphasing signals S’1 and S’2, the amplitude of the original S in is reproduced.

[0088] In each of the above embodiments, an example in which the analog vector decomposer is used in an optical wireless transmission system has been described. However, the present disclosure is not limited thereto. The outphasing signals S1 and S2 do not necessarily need to be transmitted using an optical fiber. The analog vector decomposer can be used in a circuit that converts a signal vector that has been amplitude-modulated and phase-modulated in the analog domain into a set of outphasing signals that have a constant amplitude and only phase modulation.

[0089] FIG. 21 shows an example in which the analog vector decomposer is applied to a wireless communication device. In this example, the wireless communication device 300 includes a digital baseband unit 301, a DAC 303, an analog vector decomposer 304, amplifiers 305 and 306, a synthesizer 307, and an antenna 308. The wireless communication device 300 corresponds to the communication device 40 shown in FIG. 2.

[0090] The digital baseband unit 301 generates a digital baseband signal. The DAC 303 converts the quadrature-modulated baseband signal from a digital signal to an analog signal. The digital baseband unit 301 corresponds to the digital baseband unit 111 shown in FIG. 19. The DAC 303 corresponds to the DAC 126 shown in FIG. 19.

[0091] The analog vector decomposer 304 converts the signal input from the DAC 303 into a set of outphasing signals S1 and S2. As the analog vector decomposer 304, an analog vector decomposer having the same configuration as the analog vector decomposer 172 described in the first embodiment can be used. Alternatively, as the analog vector decomposer 304, an analog vector decomposer having the same configuration as the analog vector decomposer 172a described in the second embodiment may be used. The analog vector decomposer 304 corresponds to the vector decomposer 41 shown in FIG. 2. Further, the analog vector decomposer 304 corresponds to the analog vector decomposer 127 shown in FIG. 19.

[0092] Amplifiers 305 and 306 are power amplifiers. Amplifiers 305 and 306 amplify the outphasing signals S1 and S2. The synthesizer 307 synthesizes the amplified outphasing signals S1 and S2. The signal synthesized by the synthesizer 307 is a signal in which the input signal of the analog vector decomposer 304 is reproduced. The antenna 308 radiates the synthesized signal. Amplifiers 305 and 306 correspond to the first amplifier 42 and the second amplifier 43 shown in FIG. 2. The synthesizer 307 corresponds to the synthesizer 44 shown in FIG. 2.

[0093] When an analog vector decomposer having the same configuration as the analog vector decomposer 172a described in the second embodiment is used as the analog vector decomposer 304, the digital baseband unit 301 preferably has a correction circuit 302. The correction circuit 302 corrects the digital baseband signal so that the amplitude of the signal synthesized by the synthesizer 307 becomes the same as the amplitude when the outphasing signals S1 and S2 are synthesized. By doing so, the signal accuracy can be improved.

[0094] FIG. 22 shows the hardware configuration of the DSP that can be used for the digital baseband unit 111. The DSP 500 has one or more processors 501 and one or more memories 502. In the DSP 500, one or more processors 501 read a program stored in one or more memories 502 and execute processing according to the read program, thereby performing baseband signal processing.

[0095] The above program includes a set of instructions (or software code) for causing the processor to perform one or more functions described in the embodiments when loaded into the processor. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, a computer-readable medium or a tangible storage medium includes random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD), or other memory technologies, CD (compact disc)-ROM, digital versatile disc (DVD), Blu-ray (registered trademark) disc, or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may be transmitted on a transitory computer-readable medium or a communication medium. By way of example and not limitation, a transitory computer-readable medium or a communication medium includes electrical, optical, acoustic, or other forms of propagated signals.

[0096] Although the present disclosure has been described with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Each embodiment can be combined with other embodiments as appropriate.

[0097] The figures are merely illustrative for explaining one or more embodiments. Each figure may be associated with not only one specific embodiment but also one or more other embodiments. As can be understood by those skilled in the art, various features or steps described with reference to any one figure can be combined with features or steps shown in one or more other figures to create, for example, embodiments that are not explicitly illustrated or described. Not all of the features or steps shown in any one figure for explaining exemplary embodiments are necessarily essential, and some features or steps may be omitted. The order of the steps described in any figure may be changed as appropriate.

[0098] Some or all of the above embodiments may be described as follows, but are not limited thereto.

[0099] [Appendix 1] A phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are rotated by 90° in the positive and negative directions respectively with respect to an input signal, A vector decomposer having a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal, and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal.

[0100] [Appendix 2] The phase rotation signal generator includes a phase rotator that generates the first phase rotation signal by rotating the phase of the input signal by 90°, and an inversion signal generator that generates the second phase rotation signal by inverting the sign of the first phase rotation signal. The vector decomposer according to Appendix 1.

[0101] [Appendix 3] The vector decomposer according to Appendix 2, further having an amplitude adjuster that adjusts the amplitude of the first phase rotation signal input to the inversion signal generator according to the amplitude of the input signal.

[0102] [Appendix 4] The vector resolver according to appended note 2, further comprising an amplitude fixer for setting the amplitude of the first phase rotation signal input to the inversion signal generator to a predetermined amplitude.

[0103] [Appended note 5] A master unit, and a slave unit connected to the master unit via an optical transmission line, wherein the slave unit has an antenna, and a vector resolver having a phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are rotated 90° in the positive and negative directions, respectively, with respect to an input signal that is a received signal received using the antenna, and a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal, wherein the master unit has a synthesizer that synthesizes the first outphasing signal and the second outphasing signal received from the slave unit via the optical transmission line and reproduces a signal corresponding to the received signal, an analog-to-digital converter that converts the reproduced signal from an analog signal to a digital signal, and a signal processing circuit that performs signal processing on the signal converted to the digital signal, an optical wireless transmission system.

[0104] [Appended note 6] The optical wireless transmission system according to appended note 5, wherein the phase rotation signal generator includes a phase rotator that generates the first phase rotation signal by rotating the phase of the input signal by 90°, and an inversion signal generator that generates the second phase rotation signal by inverting the sign of the first phase rotation signal.

[0105] [Appended note 7] The optical wireless transmission system according to appended note 6, wherein the slave unit further includes an amplitude adjuster that adjusts the amplitude of the first phase rotation signal input to the inversion signal generator according to the amplitude of the input signal.

[0106] [Appendix 8] The slave unit further includes an amplitude fixer that sets the amplitude of the first phase rotation signal input to the inversion signal generator to a predetermined amplitude, for the optical wireless transmission system according to Appendix 6.

[0107] [Appendix 9] The signal processing circuit includes a first correction circuit that corrects the amplitude of the signal corresponding to the reproduced received signal according to the amplitude of the signal corresponding to the reproduced received signal and the predetermined amplitude, for the optical wireless transmission system according to Appendix 8.

[0108] [Appendix 10] The master unit further includes a vector decomposer having a phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are rotated 90° in the positive and negative directions, respectively, with respect to the input signal which is the transmission signal, and a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal, and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal. The slave unit further includes a synthesizer that synthesizes the first outphasing signal and the second outphasing signal received from the master unit via the optical transmission path and reproduces a signal corresponding to the transmission signal, for the optical wireless transmission system according to any one of Appendices 5 to 9.

[0109] [Appendix 11] The phase rotation signal generator of the master unit includes a phase rotator that generates the first phase rotation signal by rotating the phase of the transmission signal which is the input signal by 90°, and an inversion signal generator that generates the second phase rotation signal by inverting the sign of the first phase rotation signal, for the optical wireless transmission system according to Appendix 10.

[0110] [Appendix 12] The master unit further includes an amplitude adjuster that adjusts the amplitude of the first phase rotation signal input to the inversion signal generator according to the amplitude of the input signal, for the optical wireless transmission system according to Appendix 11.

[0111] [Appendix 13] The master device is the optical wireless transmission system according to Appendix 11, further comprising an amplitude fixer that sets the amplitude of the first phase rotation signal input to the inversion signal generator to a predetermined amplitude.

[0112] [Appendix 14] The signal processing circuit is the optical wireless transmission system according to Appendix 13, further comprising a second correction circuit that corrects the amplitude of the transmission signal input to the vector decomposer according to the amplitude of the transmission signal and the predetermined amplitude.

[0113] [Appendix 15] A vector decomposer having a phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are rotated 90° in the positive and negative directions, respectively, with respect to an input signal that is a transmission signal, and a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal; A first amplifier and a second amplifier that amplify the first outphasing signal and the second outphasing signal, respectively; A communication device comprising a synthesizer that synthesizes the amplified first outphasing signal and the amplified second outphasing signal.

[0114] [Appendix 16] The phase rotation signal generator is the communication device according to Appendix 15, including a phase rotator that generates the first phase rotation signal by rotating the phase of the transmission signal that is the input signal by 90°, and an inversion signal generator that generates the second phase rotation signal by inverting the sign of the first phase rotation signal.

[0115] [Appendix 17] The communication device according to Appendix 16, further comprising an amplitude adjuster that adjusts the amplitude of the first phase rotation signal input to the inversion signal generator according to the amplitude of the input signal.

[0116] [Appendix 18] The communication device according to Appendix 16, further comprising an amplitude fixer for setting the amplitude of the first phase rotation signal input to the inversion signal generator to a predetermined amplitude.

[0117] [Appendix 19] The communication device according to Appendix 18, further comprising a signal processing circuit including a correction circuit for correcting the amplitude of the transmission signal input to the vector decomposer according to the amplitude of the transmission signal and the predetermined amplitude.

[0118] [Appendix 20] Generating a first phase rotation signal and a second phase rotation signal whose phases are rotated 90° in the positive and negative directions, respectively, with respect to an input signal, A vector decomposition method including synthesizing the input signal and the first phase rotation signal to generate a first outphasing signal, and synthesizing the input signal and the second phase rotation signal to generate a second outphasing signal.

[0119] Some or all of the elements (e.g., configurations and functions) described in Appendices 2 to 4 that are subordinate to Appendix 1 may be subordinate to Appendix 20 in the same subordinate relationship as Appendices 2 to 4. Some or all of the elements described in any appendix may be applied to various hardware, software, recording means for recording software, systems, and methods.

Explanation of Reference Numerals

[0120] 10: Optical wireless transmission system 20: Master unit 21: Combiner 22: ADC 23: Signal processing circuit 30: Slave unit 31: Antenna 32: Vector decomposer 33: Phase rotation signal generator 34: Combiner 40: Communication device 41: Vector decomposer 42: First amplifier 43: Second amplifier 44: Combiner 100: Optical wireless transmission system 110: Master unit 111: Digital baseband section 112: Digital outphasing modulator 113a, 113b: DAC 114a, 114b: Rectifier 121: Combiner 122: Band-pass filter 123: ADC 124: Correction circuit 126: DAC 127: Analog vector decomposer 131, 135: WDM E / O converter 132, 136: Optical fiber 133, 137: WDM O / E converter 150: Slave unit 151: Transmitter section 152: Receiver section 153: Transmit / receive switch circuit 154: Antenna 161: Combiner 162: Band-pass filter 163: Amplifier 171: Amplifier 172: Analog vector decomposer 173a, 173b: Rectifier 181: Phase rotator 182: Amplitude adjuster 183: Inversion signal generator 184, 185: Combiner 186: Amplitude fixer 187, 188: Limiter 191: Amplitude squarer 192: Limiter 193: Differentiator 194: Amplitude 0.5 power multiplier 201: Amplitude detector 202: Gain variable amplifier 211: Amplitude detector 212: Gain variable I-V converter 215: Current source 216: Inductor 217: FET 218, 219: Capacitor 221: Quadrature demodulator 222: Low-pass filter 223: Quadrature modulator 225: RC polyphase filter 300: Wireless communication device 301: Digital baseband section 302: Correction circuit 303: DAC 304: Analog vector resolver 305, 306: Amplifier 307: Synthesizer 308: Antenna 500: DSP 501: Processor 502: Memory

Claims

1. A phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are rotated by 90° in the positive and negative directions, respectively, with respect to an input signal; A vector decomposer having a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal, and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal.

2. The phase rotation signal generator includes a phase rotator that generates the first phase rotation signal by rotating the phase of the input signal by 90°, and an inversion signal generator that generates the second phase rotation signal by inverting the sign of the first phase rotation signal. The vector decomposer according to claim 1, further comprising an amplitude adjuster that adjusts the amplitude of the first phase rotation signal input to the inversion signal generator according to the amplitude of the input signal.

3. The vector decomposer according to claim 2, further comprising an amplitude fixer that sets the amplitude of the first phase rotation signal input to the inversion signal generator to a predetermined amplitude.

4. A master unit; A slave unit connected to the master unit via an optical transmission line, The slave unit includes: An antenna, A phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are rotated by 90° in the positive and negative directions, respectively, with respect to an input signal that is a reception signal received using the antenna, and a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal, and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal, and has a vector decomposer. The master unit includes: A synthesizer that synthesizes the first outphasing signal and the second outphasing signal received from the slave unit via the optical transmission line and reproduces a signal corresponding to the reception signal; An analog-to-digital converter that converts the reproduced signal from an analog signal to a digital signal; An optical wireless transmission system having a signal processing circuit that performs signal processing on the signal converted to the digital signal.

5. The optical wireless transmission system according to claim 4, wherein the signal processing circuit has a first correction circuit that corrects the amplitude of the signal corresponding to the reproduced reception signal according to the amplitude of the signal corresponding to the reproduced reception signal and a predetermined amplitude.

6. The master device further includes a vector decomposer having a phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are each rotated 90° in the positive and negative directions with respect to an input signal that is a transmission signal, and a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal. The slave device further includes a synthesizer that synthesizes the first outphasing signal and the second outphasing signal received from the master device via the optical transmission path and reproduces a signal corresponding to the transmission signal. The optical wireless transmission system according to claim 4 or 5.

7. The signal processing circuit has a second correction circuit that corrects the amplitude of the transmission signal input to the vector decomposer according to the amplitude of the transmission signal and a predetermined amplitude. The optical wireless transmission system according to claim 6.

8. A phase rotation signal generator that generates a first phase rotation signal and a second phase rotation signal whose phases are each rotated 90° in the positive and negative directions with respect to an input signal that is a transmission signal, and a synthesizer that synthesizes the input signal and the first phase rotation signal to generate a first outphasing signal and synthesizes the input signal and the second phase rotation signal to generate a second outphasing signal, and a vector decomposer having the same. First and second amplifiers that amplify the first outphasing signal and the second outphasing signal, respectively. A communication device including a synthesizer that synthesizes the amplified first outphasing signal and the amplified second outphasing signal.

9. The communication device according to claim 8, further including a signal processing circuit including a correction circuit that corrects the amplitude of the transmission signal input to the vector decomposer according to the amplitude of the transmission signal and a predetermined amplitude.

10. Generating a first phase rotation signal and a second phase rotation signal whose phases are each rotated 90° with respect to an input signal. A vector decomposition method including synthesizing the input signal and the first phase rotation signal to generate a first outphasing signal and synthesizing the input signal and the second phase rotation signal to generate a second outphasing signal.

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