Radio apparatus and signal processing method

Abstract

To reduce the cost of a radio device used for radio communication.SOLUTION: A switching signal generation unit configured to generate a switching signal for transmission or reception in accordance with a predetermined transmission time period and reception time period, and configured to switch between a modulation mode for performing processing for generating a modulated high-frequency signal and a non-modulation mode for performing processing for generating a non-modulated high-frequency signal in accordance with a type of the switching signal generated by the switching signal generation unit; A wireless device comprising: a mode switching unit that generates either a modulated high-frequency signal or a non-modulated high-frequency signal; and a switch that outputs the modulated high-frequency signal to a path used as a transmission signal when a switching signal for transmission is obtained, and outputs the non-modulated high-frequency signal to a path used as a local oscillation signal when a switching signal for reception is obtained.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radio device and a signal processing method. [Background technology]

[0002] Conventionally, systems that use the terahertz band as a carrier wave have been studied in order to increase the capacity of wireless communication systems. There are several methods for generating terahertz waves, and Non-Patent Document 1 proposes a method based on optical beats. FIG. 18 is a diagram showing an example of a conventional wireless communication system S. In the wireless communication system S, terahertz waves are generated based on optical beats. The wireless communication system S includes a transmitter 1 and a receiver 2.

[0003] The transmitter 1 generates a terahertz signal based on an externally input transmission code sequence and transmits the generated terahertz signal wirelessly into free space via an antenna. The receiver 2 identifies and outputs a reception code sequence based on a reception signal received via the antenna. The transmitter 1 includes a DSP 11, a DAC 12, a light source unit 13, a bias power supply 14, an IQ modulator 15, an optical coupler 16, a photodiode 17, and an antenna 18.

[0004] The DSP 11 is a digital signal processor that generates a discrete modulated signal based on the transmission code sequence input to the transmitter 1. The DAC 12 is a digital-to-analog converter that converts the modulated signal generated by the DSP 11 into an analog signal. The DAC 12 outputs the analog signal to the IQ modulator 15. The light source unit 13 outputs two continuous light beams having different wavelengths λ1 and λ2. The light source unit 13 outputs the continuous light beam with wavelength λ1 to the IQ modulator 15 and outputs the continuous light beam with wavelength λ2 to the optical coupler 16. The bias power supply 14 applies a bias voltage (DC bias) to the IQ modulator 15. The IQ modulator 15 is driven by the applied bias voltage and generates a modulated optical signal with wavelength λ1 by modulating the continuous light beam with wavelength λ1 with an analog signal. The IQ modulator 15 outputs the generated modulated optical signal with wavelength λ1 to the optical coupler 16.

[0005] The optical coupler 16 multiplexes the continuous light of wavelength λ2 output from the light source unit 13 with the modulated optical signal of wavelength λ1. The multiplexed signal multiplexed by the optical coupler 16 is input to the photodiode 17. The photodiode 17 is a device that converts light into electricity. When two lights of different wavelengths (for example, λ1 and λ2) are input to the photodiode 17 at the same time, the frequency difference F between the two lights of different wavelengths that are input is IF It is known that an electrical signal having a carrier of λ1 and λ2 is output. Therefore, the frequency difference F between the wavelengths λ1 and λ2 of the two continuous light beams output from the light source unit 13 is IF A terahertz signal can be generated by setting the wavelength of the light beam to terahertz. This method of generating a signal of the desired frequency by receiving light of two different wavelengths with photodiode 17 is called the optical beat method. The terahertz signal generated by photodiode 17 is radiated as a wireless signal (radio wave) by antenna 18.

[0006] The receiver 2 includes an antenna 21, a branching unit 22, a local oscillator signal generating unit 23, a branching unit 24, a delay unit 25, a first mixer 26, a second mixer 27, an ADC 28, and a DSP 29. The antenna 21 receives a radio signal emitted from the transmitter 1 and converts it into an electrical signal. The electrical signal obtained by the antenna 21 is branched into two paths by the branching unit 22 and input to the first mixer 26 and the second mixer 27. The local oscillator signal generating unit 23 generates a signal having a frequency F IF The local oscillator signal generated by the local oscillator signal generating unit 23 is IF The local oscillator signal is branched into two paths by a branching unit 24 and input to a delay unit 25 and a second mixer 27 .

[0007] The delay unit 25 delays the input frequency F IF For example, the delay circuit 25 delays the input frequency F IF The first mixer 26 mixes the electrical signal branched by the branching unit 22 with a frequency F IFThe second mixer 27 down-converts the electrical signal corresponding to the received signal to baseband by multiplying it by the local oscillator signal of frequency F. This results in a signal of I component. IF The electric signal corresponding to the received signal is down-converted to baseband by multiplying the I component signal obtained by the first mixer 26 and the Q component signal obtained by the second mixer 27. This results in a Q component signal. The ADC 28 is an analog-to-digital converter that samples and converts the I component signal obtained by the first mixer 26 and the Q component signal obtained by the second mixer 27 into digital signals. The ADC 28 outputs the I component digital signal and the Q component digital signal to the DSP 29. The DSP 29 is a digital signal processing unit that performs processes such as waveform distortion compensation and threshold value judgment on the I component digital signal and the Q component digital signal. The DSP 29 outputs the received code sequence obtained by the digital signal processing.

[0008] When communicating transceivers have the same transmission frequency, simultaneous signal transmission by the communicating transceivers causes interference, resulting in degradation of reception characteristics. To avoid such interference, a TDD (Time Division Duplex) system has been proposed, in which transmission and reception are divided into time slots and the communicating transceivers transmit at different times (see, for example, Non-Patent Document 2). Figure 19 is a diagram showing an example of the configuration of a wireless communication system using the TDD system. Figure 19 shows an example in which transceiver 3 and transceiver 4 are communicating using the TDD system.

[0009] The transceiver 3 includes a transmitter 31, a receiver 32, a switch 33, and an antenna 34. The transceiver 4 includes a transmitter 41, a receiver 42, a switch 43, and an antenna 44. Since the transceivers 3 and 4 have the same configuration, the transceiver 3 will be described as an example. The transmitter 31 transmits transmission data during the transceiver 3's transmission time period (the time slot indicating transmission). The receiver 32 receives transmission data sent from the transceiver 4 during the transceiver 3's reception time period (the time slot indicating reception). The switch 33 switches the connection between the transmitter 31 and the receiver 32 for each time slot. The antenna 34 transmits and receives radio signals. By using such a TDD system, communication is possible while suppressing degradation of reception characteristics.

[0010] Combining the optical beat and TDD systems described above enables communication using terahertz waves while suppressing degradation of reception characteristics. FIGS. 20 and 21 are diagrams illustrating an example configuration of a wireless communication system Sa using the optical beat and TDD systems. FIG. 20 shows the transceiver 3 in transmission mode, and FIG. 21 shows the transceiver 3 in reception mode. The wireless communication system Sa includes the transceiver 3 and the transceiver 4. Since the transceiver 4 has the same configuration as the transceiver 3, the transceiver 3 will be described below. The transceiver 3 includes a transmitter 1, a receiver 2, a switching signal generator 5, a switch 6, and an antenna 7. The transmitter 1 includes a DSP 11, a DAC 12, a light source 13, a bias power supply 14, an IQ modulator 15, an optical coupler 16, and a photodiode 17. The functional units of the transmitter 1 have been described in FIG. 18 and are therefore omitted here. The receiver 2 includes a branching unit 22, a local oscillator signal generating unit 23, a branching unit 24, a delay unit 25, a first mixer 26, a second mixer 27, an ADC 28, and a DSP 29. The functional units included in the receiver 2 have been described in FIG. 18 and will not be described here.

[0011] The switching signal generator 5 generates a transmission switching signal during the transmission time period of the transceiver 3, and outputs the generated transmission switching signal to the switch 6. The transmission switching signal is a signal for switching the connection of the antenna 7 to the transmitter 1. The switching signal generator 5 also generates a reception switching signal during the reception time period of the transceiver 3, and outputs the generated reception switching signal to the switch 6. The reception switching signal is a signal for switching the connection of the antenna 7 to the receiver 2. The switch 6 switches the connection of the antenna 7 in accordance with the switching signal output from the switching signal generator 5. For example, when a transmission switching signal is received, the switch 6 connects the antenna 7 to the photodiode 17 provided in the transmitter 1, as shown in FIG. 20. As a result, the frequency F generated by the photodiode 17 based on the optical beat method is IF The transmission signal is radiated to the outside via the switch 6 and the antenna 7.

[0012] For example, when a receiving switching signal is received, the switch 6 connects the antenna 7 to the branching unit 22 of the receiver 2 as shown in FIG. 21. This allows the received code sequence to be identified based on the received signal received by the antenna 7. Note that in order to obtain a baseband signal from the received signal, the frequency of the local oscillator signal is changed to the carrier frequency (F IF ) must match. [Prior art documents] [Non-patent literature]

[0013] [Non-Patent Document 1] T. Nagatsuma, G. Ducournau and CC Renaud, “Advances in terahertz communicaions accelerated by photonics,” Nat. Photonics, Vol. 10, No.6, May 2016, pp. 371-379. [Non-patent document 2] Yoshio Kunisawa, and Takahiro Hayashi, “Evaluation of TDD timing detection error using UL and DL received signals in the relay device”, IEICE Communications Express, Vol.12, No.12, 591-594, 2023. Summary of the Invention [Problem to be solved by the invention]

[0014] However, in the configurations shown in FIGS. 20 and 21, a common frequency F IF Despite the use of terahertz waves, separate components are required for the transmitter and receiver. This increases the number of components that make up the transceiver. As a result, there is a problem in that the cost of the transceiver increases. Note that this problem is not limited to transceivers, but is common to all wireless devices used for communication using terahertz waves.

[0015] In view of the above circumstances, an object of the present invention is to provide a technique that can reduce the cost of wireless devices used for wireless communication. [Means for solving the problem]

[0016] One aspect of the present invention is a wireless device comprising: a switching signal generation unit that generates a switching signal for transmission or reception according to a predetermined transmission time period and a reception time period; a mode switching unit that switches between a modulation mode that performs processing to generate a modulated high-frequency signal and an unmodulated mode that performs processing to generate an unmodulated high-frequency signal according to the type of switching signal generated by the switching signal generation unit, thereby generating either a modulated high-frequency signal or an unmodulated high-frequency signal; and a switch that outputs the modulated high-frequency signal to a path that uses the modulated high-frequency signal as a transmission signal when a switching signal for transmission is obtained, and outputs the unmodulated high-frequency signal to a path that uses the local oscillator signal when a switching signal for reception is obtained.

[0017] One aspect of the present invention is a signal processing method that generates a switching signal for transmission or reception according to predetermined transmission time zones and reception time zones, switches between a modulation mode in which processing is performed to generate a modulated high-frequency signal and an unmodulated mode in which processing is performed to generate an unmodulated high-frequency signal according to the type of the switching signal, and generates either a modulated high-frequency signal or an unmodulated high-frequency signal, and when a switching signal for transmission is obtained, outputs the modulated high-frequency signal to a path that uses it as a transmission signal, and when a switching signal for reception is obtained, outputs the unmodulated high-frequency signal to a path that uses it as a local oscillator signal. [Effects of the Invention]

[0018] The present invention makes it possible to reduce the cost of wireless devices used for wireless communication. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram illustrating a basic configuration of a wireless communication system according to the present invention. [Figure 2] 1 is a diagram illustrating a basic configuration of a wireless communication system according to the present invention. [Figure 3] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to a first embodiment. [Figure 4]1 is a diagram illustrating an example of the configuration of a wireless communication system according to a first embodiment. [Figure 5] FIG. 4 is a diagram showing a processing flow of a transceiver in the first embodiment. [Figure 6] FIG. 4 is a diagram showing a processing flow of a transceiver in the first embodiment. [Figure 7] FIG. 10 is a diagram illustrating an example of the configuration of a wireless communication system according to a second embodiment. [Figure 8] FIG. 10 is a diagram illustrating an example of the configuration of a wireless communication system according to a second embodiment. [Figure 9] FIG. 10 is a diagram illustrating an example of the configuration of a wireless communication system according to a third embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of the configuration of a wireless communication system according to a third embodiment. [Figure 11] FIG. 10 is a diagram illustrating an example of the configuration of a wireless communication system according to a fourth embodiment. [Figure 12] FIG. 10 is a diagram illustrating an example of the configuration of a wireless communication system according to a fourth embodiment. [Figure 13] FIG. 10 is a diagram illustrating an example of the configuration of a wireless communication system according to a fifth embodiment. [Figure 14] FIG. 10 is a diagram illustrating an example of the configuration of a wireless communication system according to a fifth embodiment. [Figure 15] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system according to a sixth embodiment. [Figure 16] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system according to a sixth embodiment. [Figure 17] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system according to a seventh embodiment. [Figure 18] FIG. 1 is a diagram illustrating an example of a conventional wireless communication system. [Figure 19] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system using a TDD system. [Figure 20] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system using an optical beat method and a TDD method. [Figure 21] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system using an optical beat method and a TDD method. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] (Basic configuration) Before describing a specific configuration of the present invention, the basic configuration of the present invention will be described. Figures 1 and 2 are diagrams illustrating the basic configuration of a wireless communication system 100 according to the present invention. The wireless communication system 100 includes a transceiver 200 and a transceiver 300. Figure 1 shows the transceiver 200 transmitting, and Figure 2 shows the transceiver 200 receiving. Although Figures 1 and 2 show a configuration in which the wireless communication system 100 includes one transceiver 200 and one transceiver 300, the wireless communication system 100 may include multiple transceivers 200 and multiple transceivers 300. In the following description, the direction from the transceiver 200 toward the transceiver 300 is referred to as the downlink direction, and the direction from the transceiver 300 toward the transceiver 200 is referred to as the uplink direction.

[0022] The transceiver 200 generates a high-frequency signal (a terahertz wave signal) using a predetermined method and uses the generated high-frequency signal both during transmission and reception. For example, the transceiver 200 uses the generated high-frequency signal as a transmission signal during transmission and as a local oscillator signal during reception. The transceiver 200 may generate the high-frequency signal based on an optical beat method or an electrical circuit. The transceiver 200 includes a switching signal generator 201, a mode switch 202, a first switch 203, a second switch 204, a branching unit 205, a branching unit 206, a first mixer 207, a delay unit 208, a second mixer 209, an ADC 210, a DSP 211, and an antenna 212. The transceiver 300 may have a configuration similar to that of the transceiver 200, or may have the configuration of a general transceiver that communicates using the TDD method.

[0023] Switching signal generation unit 201 generates a switching signal for switching the operation of transceiver 200. For example, switching signal generation unit 201 generates a first switching signal during a transmission time period of transceiver 200, and outputs the generated first switching signal to mode switching unit 202, first switch 203, and second switch 204. The first switching signal is a signal for switching mode switching unit 202, first switch 203, and second switch 204 for transmission operation. Switching to transmission operation means switching the operation and connection destination of some functional units included in transceiver 200 so that transceiver 200 can transmit a signal.

[0024] Switching signal generation unit 201 generates a second switching signal, for example, during a reception time period of transceiver 200, and outputs the generated second switching signal to mode switching unit 202, first switch 203, and second switch 204. The second switching signal is a signal for switching mode switching unit 202, first switch 203, and second switch 204 for reception operation. Switching for reception operation means switching the operation and connection destination of some functional units included in transceiver 200 so that transceiver 200 can receive signals.

[0025] The above-mentioned transmission time zone and reception time zone are "uplink" and "downlink" time zones defined for each time slot by the TDD system. Here, in transceiver 200, the time zone in which the time slot is "uplink" corresponds to the reception time zone, and the time zone in which the time slot is "downlink" corresponds to the transmission time zone. On the other hand, in transceiver 300, the time zone in which the time slot is "uplink" corresponds to the transmission time zone, and the time zone in which the time slot is "downlink" corresponds to the reception time zone.

[0026] The mode switching unit 202 switches the operation mode between the modulation mode and the unmodulation mode in response to the switching signal output from the switching signal generating unit 201. The modulation mode is a mode in which processing is performed to generate a modulated high-frequency signal (hereinafter referred to as a "modulated high-frequency signal"). The unmodulation mode is a mode in which processing is performed to generate an unmodulated high-frequency signal (hereinafter referred to as an "unmodulated high-frequency signal"). The modulated high-frequency signal is used as a transmission signal, and the unmodulated high-frequency signal is used as a local oscillator signal.

[0027] When the mode switching unit 202 receives a first switching signal from the switching signal generating unit 201, the mode switching unit 202 performs processing to generate a modulated high-frequency signal, thereby generating a modulated high-frequency signal. Details of the processing to generate a modulated high-frequency signal will be described later. The mode switching unit 202 outputs the generated modulated high-frequency signal to the first switch 203. When the mode switching unit 202 receives a second switching signal from the switching signal generating unit 201, the mode switching unit 202 performs processing to generate an unmodulated high-frequency signal, thereby generating an unmodulated high-frequency signal. Details of the processing to generate an unmodulated high-frequency signal will also be described later. The mode switching unit 202 outputs the generated unmodulated high-frequency signal to the first switch 203. In this way, the mode switching unit 202 generates a high-frequency signal to be used as a transmission signal during a transmission time period of the transceiver 200, and generates a high-frequency signal to be used as a local oscillator signal during a reception time period of the transceiver 200. The mode switching unit 202 may generate a high-frequency signal using a predetermined method (for example, a method using an optical beat method or a method using an electrical circuit).

[0028] First switch 203 switches the connection destination in accordance with the switching signal output from switching signal generation unit 201. For example, when first switch 203 receives the first switching signal from switching signal generation unit 201, first switch 203 connects mode switching unit 202 and second switch 204 as shown in FIG. 1. As a result, first switch 203 outputs the modulated high-frequency signal output from mode switching unit 202 to second switch 204. For example, when first switch 203 receives the second switching signal from switching signal generation unit 201, first switch 203 connects mode switching unit 202 and branching unit 205 as shown in FIG. 2. As a result, first switch 203 outputs the unmodulated high-frequency signal output from mode switching unit 202 to branching unit 205.

[0029] The second switch 204 switches the connection destination in accordance with the switching signal output from the switching signal generation unit 201. For example, when the second switch 204 receives a first switching signal from the switching signal generation unit 201, the second switch 204 connects the first switch 203 to the antenna 212 as shown in FIG. 1. As a result, the second switch 204 outputs the modulated high-frequency signal output from the first switch 203 to the antenna 212. For example, when the second switch 204 receives a second switching signal from the switching signal generation unit 201, the second switch 204 connects the branching unit 206 to the antenna 212 as shown in FIG. 2. As a result, the second switch 204 outputs the signal received via the antenna 212 to the branching unit 206.

[0030] Branching unit 205 is connected to first switch 203, first mixer 207, and delay unit 208. Branching unit 205 branches the unmodulated high-frequency signal input via first switch 203 into two paths and outputs the two paths to first mixer 207 and delay unit 208.

[0031] Branching unit 206 is connected to second switch 204, first mixer 207, and second mixer 209. Branching unit 206 branches the received signal input via second switch 204 into two paths and outputs the two paths to first mixer 207 and second mixer 209.

[0032] First mixer 207 down-converts the received signal to baseband by multiplying the unmodulated high-frequency signal branched by branching unit 205 with the received signal branched by branching unit 206. In this way, first mixer 207 uses the unmodulated high-frequency signal as a local oscillator signal.

[0033] Delay unit 208 provides a predetermined delay to the unmodulated high frequency signal branched by branch unit 205. For example, delay unit 208 provides a delay so as to shift the phase of the unmodulated high frequency signal by 90 degrees.

[0034] The second mixer 209 down-converts the received signal to baseband by multiplying the unmodulated high-frequency signal delayed by the delay unit 208 by the received signal branched by the branching unit 206. In this way, the second mixer 209 uses the unmodulated high-frequency signal as a local oscillator signal.

[0035] The ADC 210 is an analog-to-digital converter that samples and converts into digital signals the signal obtained by the first mixer 207 and the signal obtained by the second mixer 27. The ADC 210 outputs the digital signal of the I component and the digital signal of the Q component to the DSP 211.

[0036] The DSP 211 is a digital signal processing unit that performs processes such as compensation for waveform distortion and threshold determination on the I-component digital signal and the Q-component digital signal output from the ADC 210. The DSP 211 outputs a received code sequence obtained by digital signal processing.

[0037] The antenna 212 emits the modulated high-frequency signal output from the second switch 204 into free space as a radio wave. The antenna 212 receives the radio wave transmitted from the transceiver 300. The antenna 212 outputs a received signal (electrical signal) corresponding to the received radio wave to the branching unit 206.

[0038] As described above, in transceiver 200, when switching signal generator 201 outputs a first switching signal to mode switcher 202, first switch 203, and second switch 204, the modulated high-frequency signal is radiated to the outside as a transmission signal via first switch 203, second switch 204, and antenna 212. Also, in transceiver 200, when switching signal generator 201 outputs a second switching signal to mode switcher 202, first switch 203, and second switch 204, the unmodulated high-frequency signal is used as a local oscillator signal via first switch 203 and branching unit 205, etc. In this way, in the present invention, the process of generating a modulated or unmodulated high-frequency signal (device operation) and the destinations of switches such as first switch 203 and second switch 204 are switched simultaneously in response to a switching signal output for each time slot determined by the TDD system. This allows a high-frequency signal generated based on a signal obtained from a single signal source to be used for generating a transmission signal during transmission and a local oscillator signal during reception. This reduces the cost of the transceiver. Below, a process for generating a modulated high-frequency signal and a process for generating an unmodulated high-frequency signal will be described using several embodiments based on the basic configuration.

[0039] (First embodiment) In the first embodiment, assuming the use of an optical beat system, a configuration will be described in which the bias of an IQ modulator is switched between transmission and reception.

[0040] 3 and 4 are diagrams showing an example of the configuration of a wireless communication system 100a according to the first embodiment. The wireless communication system 100a includes a transceiver 200a and a transceiver 300a. FIG. 3 shows the transceiver 200a transmitting, and FIG. 4 shows the transceiver 200a receiving. Note that while FIGS. 3 and 4 show a configuration in which the wireless communication system 100a includes one transceiver 200a and one transceiver 300a, the wireless communication system 100a may include multiple transceivers 200a and multiple transceivers 300a.

[0041] The transceiver 200a includes a switching signal generator 201, a mode switcher 202a, a first switch 203, a second switch 204, a branching unit 205, a branching unit 206, a first mixer 207, a delay unit 208, a second mixer 209, an ADC 210, a DSP 211, an antenna 212, a light source unit 213, an optical coupler 214, a photodiode 215, a DSP 216, a DAC 217, a bias power supply 218, and an IQ modulator 219. The transceiver 300a may have the same configuration as the transceiver 200a, or may have the configuration of a general transceiver that communicates in a TDD system. The transceiver 200a is one aspect of a wireless device.

[0042] Transceiver 200a differs in configuration from transceiver 200 in that it includes mode switching unit 202a instead of mode switching unit 202, and in that it newly includes light source unit 213, optical coupler 214, and photodiode 215. The rest of the configuration of transceiver 200a is the same as that of transceiver 200. The following description will focus on the differences from transceiver 200.

[0043] The light source unit 213 outputs two continuous light beams having different wavelengths λ1 and λ2. For example, the wavelengths λ1 and λ2 have a frequency difference F IF The continuous light having a wavelength λ1 output from the light source unit 213 is input to the mode switching unit 202a, and the continuous light having a wavelength λ2 is input to the optical coupler 214.

[0044] The mode switching unit 202a switches the operation mode between the modulation mode and the non-modulation mode in response to the switching signal output from the switching signal generation unit 201. The mode switching unit 202a is composed of a DSP 216, a DAC 217, a bias power supply 218, and an IQ modulator 219.

[0045] 3(a) shows the configuration of the IQ modulator 219. The IQ modulator 219 receives an I component signal, a Q component signal, and a bias voltage V DC It has three electrode terminals to which a bias voltage V DCThe change in the output light intensity of the IQ modulator 219 with respect to the voltage applied to the electrode terminal to which the bias voltage V DC The output light intensity changes periodically in response to the change in . At this time, the point where the output light is extinguished is called the null point, and the voltage at the null point is V0.

[0046] When the transceiver 200a operates in modulation mode, it is necessary to generate a transmission signal by modulating continuous light of wavelength λ1 in order to generate a modulated high-frequency signal in the photodiode 215. Therefore, the mode switching unit 202a adjusts the bias voltage V DC is set to V0, and a modulation signal for the transmission code sequence is applied via the electrode terminal for applying the I component signal and the electrode terminal for applying the Q component signal. This makes it possible to generate a transmission signal by modulating continuous light with wavelength λ1. In the first embodiment, this process is for generating a modulated high-frequency signal.

[0047] When the transceiver 200a operates in the unmodulated mode, it is necessary to input the continuous light of wavelength λ1 to the photodiode 215 without modulating it to generate an unmodulated local oscillator signal. Therefore, when the mode switching unit 202a receives the second switching signal from the switching signal generating unit 201, it stops applying the modulated signal from the DSP 216 to the IQ modulator 219. However, when the bias voltage V DC If the bias voltage V remains at V0, the light is quenched and continuous light of wavelength λ1 is not output from the IQ modulator 219. Therefore, the mode switching unit 202a changes the bias voltage V DC to a value other than V0. In the first embodiment, this processing is processing for generating an unmodulated high frequency signal.

[0048] The DSP 216 operates in accordance with the switching signal output from the switching signal generation unit 201. For example, when the DSP 216 receives a first switching signal from the switching signal generation unit 201, the DSP 216 generates a discrete modulated signal based on the transmission code sequence input to the transceiver 200a and outputs the generated signal to the DAC 217. On the other hand, when the DSP 216 receives a second switching signal from the switching signal generation unit 201, the DSP 216 does not output a modulated signal.

[0049] The DAC 217 is a digital-to-analog converter that converts the modulated signal output from the DSP 216 into an analog signal. The DAC 217 outputs the analog signal to the IQ modulator 219. For example, the DAC 217 applies the I component modulated signal to an electrode terminal of the IQ modulator 219 that applies the I component signal, and applies the Q component modulated signal to an electrode terminal of the IQ modulator 219 that applies the Q component signal.

[0050] The bias power supply 218 generates a bias voltage V that varies depending on the switching signal output from the switching signal generating unit 201. DC to the IQ modulator 219. For example, when the first switching signal is received from the switching signal generation unit 201, the bias power supply 218 applies the bias voltage V0 (V DC= V0) to the IQ modulator 219. For example, when a second switching signal is received from the switching signal generation unit 201, the bias power supply 218 applies a value other than the bias voltage V0 (V DC ≠V0) is applied to the IQ modulator 219.

[0051] The IQ modulator 219 is driven by an applied bias voltage V DC When a bias voltage V0 is applied to the IQ modulator 219, the IQ modulator 219 generates a modulated optical signal of wavelength λ1 by modulating the input continuous light of wavelength λ1 based on the I component modulation signal and the Q component modulation signal. The IQ modulator 219 outputs the generated modulated optical signal of wavelength λ1 to the optical coupler 214. When a bias voltage other than V0 is applied to the IQ modulator 219, the IQ modulator 219 outputs the input continuous light of wavelength λ1 to the optical coupler 214 without modulating it. In other words, the IQ modulator 219 outputs unmodulated continuous light of wavelength λ1 to the optical coupler 214.

[0052] The optical coupler 214 multiplexes the continuous light having a wavelength λ2 output from the light source unit 213 and the light having a wavelength λ1 output from the IQ modulator 219. When the mode switching unit 202a operates in the modulation mode, the optical coupler 214 receives as input the modulated optical signal having a wavelength λ1 output from the IQ modulator 219 and the continuous light having a wavelength λ2 output from the light source unit 213. In this case, the optical coupler 214 multiplexes the input modulated optical signal having a wavelength λ1 and the continuous light having a wavelength λ2. The optical coupler 214 outputs the multiplexed optical signal to the photodiode 215. When the mode switching unit 202a operates in the unmodulated mode, the optical coupler 214 receives as input the unmodulated continuous light having a wavelength λ1 output from the IQ modulator 219 and the continuous light having a wavelength λ2 output from the light source unit 213. In this case, the optical coupler 214 combines the input continuous light with wavelength λ1 and the input continuous light with wavelength λ2, and outputs the combined optical signal to the photodiode 215.

[0053] The photodiode 215 detects the frequency difference F between two lights of different wavelengths contained in the combined optical signal output from the optical coupler 214. IF The photodiode 215 generates a high frequency signal having a carrier of frequency F as shown in FIG. 3 based on the modulated optical signal of wavelength λ1 and the continuous light of wavelength λ2 contained in the combined optical signal output from the optical coupler 214, for example. IF That is, the photodiode 215 generates a modulated high frequency signal having a frequency F IF The modulated high frequency signal generated by the photodiode 215 is input to the first switch 203.

[0054] The photodiode 215 detects a frequency F as shown in FIG. 4 based on the continuous light (unmodulated light) with wavelength λ1 and the continuous light with wavelength λ2 contained in the combined optical signal output from the optical coupler 214, for example. IF The photodiode 215 outputs the generated high frequency signal to the first switch 203. That is, the photodiode 215 generates an unmodulated high frequency signal having a frequency F IFThe unmodulated high frequency signal generated by the photodiode 215 is input to the first switch 203.

[0055] During the transmission time period of transceiver 200a, first switch 203 connects photodiode 215 and second switch 204, as shown in Fig. 3. As a result, the modulated high-frequency signal generated by photodiode 215 is input to second switch 204. Also, during the transmission time period of transceiver 200a, second switch 204 connects first switch 203 and antenna 212, as shown in Fig. 3. As a result, the modulated high-frequency signal input to second switch 204 is input to antenna 212.

[0056] During the reception time period of transceiver 200a, first switch 203 connects photodiode 215 to branching unit 205, as shown in Fig. 4. As a result, the unmodulated high-frequency signal generated by photodiode 215 is input to branching unit 205. Furthermore, during the reception time period of transceiver 200a, second switch 204 connects branching unit 206 to antenna 212, as shown in Fig. 4. As a result, the received signal received by antenna 212 and input to second switch 204 is input to branching unit 206.

[0057] 5 and 6 are diagrams showing the processing flow of the transceiver 200a in the first embodiment. Fig. 5 explains the processing flow when the transceiver 200a transmits, and Fig. 6 explains the processing flow when the transceiver 200a receives. First, the explanation will be given using Fig. 5.

[0058] The switching signal generation unit 201 outputs a first switching signal to the mode switching unit 202a, the first switch 203, and the second switch 204 during the transmission time period of the transceiver 200a (step S101). The mode switching unit 202a switches to the modulation mode based on the first switching signal output from the switching signal generation unit 201 (step S102). The first switch 203 and the second switch 204 switch their connection based on the first switching signal output from the switching signal generation unit 201 (step S103). Specifically, the first switch 203 switches the connection so that the photodiode 215 and the second switch 204 are connected. The second switch 204 switches the connection so that the first switch 203 and the antenna 212 are connected.

[0059] The light source unit 213 outputs two continuous light beams having different wavelengths λ1 and λ2 (step S104). The continuous light beam with wavelength λ1 output from the light source unit 213 is input to the mode switching unit 202a. The continuous light beam with wavelength λ2 output from the light source unit 213 is input to the optical coupler 214. The mode switching unit 202a generates a modulated high-frequency signal with wavelength λ1 based on the input continuous light beam with wavelength λ1. The mode switching unit 202a outputs the generated modulated high-frequency signal with wavelength λ1 to the photodiode 215. The photodiode 215 generates a modulated high-frequency signal based on a beat method using the continuous light beam with wavelength λ2 output from the light source unit 213 and the modulated high-frequency signal with wavelength λ1 output from the mode switching unit 202a (step S105). In this way, the photodiode 215 generates a modulated high-frequency signal as a transmission signal. The modulated high frequency signal generated by the photodiode 215 is input to the antenna 212 via the first switch 203 and the second switch 204. The antenna 212 emits the input modulated high frequency signal as a radio wave (step S106).

[0060] Next, a description will be given with reference to Fig. 6. The switching signal generation unit 201 outputs a second switching signal to the mode switching unit 202a, the first switch 203, and the second switch 204 during the reception time period of the transceiver 200a (step S201). The mode switching unit 202a switches to the unmodulated mode based on the second switching signal output from the switching signal generation unit 201 (step S202). The first switch 203 and the second switch 204 switch their connections based on the second switching signal output from the switching signal generation unit 201 (step S203). Specifically, the first switch 203 switches the connection so that the photodiode 215 and the branch unit 205 are connected. The second switch 204 switches the connection so that the branch unit 206 and the antenna 212 are connected.

[0061] The light source unit 213 outputs two continuous light beams having different wavelengths λ1 and λ2 (step S204). The continuous light beam with wavelength λ1 output from the light source unit 213 is input to the mode switching unit 202a. The continuous light beam with wavelength λ2 output from the light source unit 213 is input to the optical coupler 214. The mode switching unit 202a generates an unmodulated signal with wavelength λ1 based on the input continuous light beam with wavelength λ1. The mode switching unit 202a outputs the generated unmodulated signal with wavelength λ1 to the photodiode 215. The photodiode 215 generates an unmodulated high-frequency signal based on a beat method using the continuous light beam with wavelength λ2 output from the light source unit 213 and the unmodulated signal with wavelength λ1 output from the mode switching unit 202a (step S205). In this way, the photodiode 215 generates an unmodulated high-frequency signal as a local oscillator signal. The unmodulated high frequency signal generated by the photodiode 215 is input to the branching unit 205 via the first switch 203 .

[0062] The antenna 212 receives radio waves transmitted from outside (step S206). The antenna 212 outputs the received radio waves as a received electrical signal to the branching unit 206. After that, the transceiver 200a performs a receiving process (step S207).

[0063] According to the wireless communication system 100 configured as described above, the transceiver 200a includes a switching signal generation unit 201 that generates a first switching signal or a second switching signal in accordance with a transmission time zone and a reception time zone that are predetermined by TDD timing, a mode switching unit 202a that switches between a modulation mode and an unmodulated mode in accordance with the type of switching signal generated by the switching signal generation unit 201, and generates either a modulated high-frequency signal or an unmodulated high-frequency signal, and a first switch 203 and a second switch 204 that, when the first switching signal is received, output the modulated high-frequency signal to a path that uses the signal as a transmission signal, and, when the second switching signal is received, output the unmodulated high-frequency signal to a path that uses the signal as a local oscillator signal.

[0064] In this way, transceiver 200a switches the output destination of the modulated high-frequency signal and the unmodulated high-frequency signal depending on the operating mode. Therefore, a high-frequency signal generated based on the output from a single signal source can be used as a transmission signal during transmission and as a local oscillator signal during reception. In other words, transceiver 200a can share a single signal source (light source unit 213). This eliminates the need for transceiver 200a to have components that generate high-frequency signals for transmission and reception, respectively. This makes it possible to reduce the cost of wireless devices used for wireless communication.

[0065] (Second embodiment) In the second embodiment, a configuration will be described in which the function of the mode switching unit is realized using an optical switch.

[0066] 7 and 8 are diagrams showing an example of the configuration of a wireless communication system 100b according to the second embodiment. The wireless communication system 100b includes a transceiver 200b and a transceiver 300b. FIG. 7 shows the transceiver 200b transmitting, and FIG. 8 shows the transceiver 200b receiving. Note that although FIGS. 7 and 8 show a configuration in which the wireless communication system 100b includes one transceiver 200b and one transceiver 300b, the wireless communication system 100b may include multiple transceivers 200b and multiple transceivers 300b.

[0067] The transceiver 200b includes a switching signal generator 201, a mode switcher 202b, a first switch 203, a second switch 204, a branching unit 205, a branching unit 206, a first mixer 207, a delay unit 208, a second mixer 209, an ADC 210, a DSP 211, an antenna 212, a light source unit 213, an optical coupler 214, a photodiode 215, a DSP 216, a DAC 217, a bias power supply 218, and an IQ modulator 219. The transceiver 300b may have the same configuration as the transceiver 200b, or may have the configuration of a general transceiver that communicates in a TDD system. The transceiver 200b is one aspect of a wireless device.

[0068] The transceiver 200b differs in configuration from the transceiver 200a in that it includes a mode switching unit 202b instead of the mode switching unit 202a. The rest of the configuration of the transceiver 200b is the same as that of the transceiver 200a. The following description will focus on the differences from the transceiver 200a.

[0069] The mode switching unit 202b switches the operation mode between the modulation mode and the non-modulation mode in response to the switching signal output from the switching signal generation unit 201. The mode switching unit 202b is composed of a DSP 216, a DAC 217, a bias power supply 218, an IQ modulator 219, a first optical switch 220, and a second optical switch 221. The first optical switch 220 is provided at the input end and connected to the light source unit 213. The second optical switch 221 is provided at the output end and connected to the optical coupler 214.

[0070] When the transceiver 200b operates in modulation mode, it is necessary to generate a transmission signal by modulating continuous light of wavelength λ1 in order to generate a modulated high-frequency signal in the photodiode 215. Therefore, the mode switching unit 202b adjusts the bias voltage V DCto V0, and applies a modulation signal for the transmission code sequence via an electrode terminal for applying an I component signal and an electrode terminal for applying a Q component signal. Furthermore, the mode switching unit 202b switches the connection relationship of the first optical switch 220 so that the output of the first optical switch 220 is input to the IQ modulator 219, as shown in FIG. 7. For example, the mode switching unit 202b switches the connection relationship of the first optical switch 220 so that the light source unit 213 and the IQ modulator 219 are connected. As a result, the mode switching unit 202b modulates the input continuous light of wavelength λ1. Furthermore, the mode switching unit 202b switches the connection relationship of the second optical switch 221 so that the output of the IQ modulator 219 is input to the photodiode 215, as shown in FIG. 7. For example, the mode switching unit 202b switches the connection relationship of the second optical switch 221 so that the IQ modulator 219 and the second optical switch 221 are connected. As a result, the output of the IQ modulator 219 is input to the photodiode 215 via the optical coupler 214, and a modulated high-frequency signal is generated. In the second embodiment, this processing is processing for generating a modulated high-frequency signal.

[0071] When transceiver 200b operates in the unmodulated mode, it is necessary to input continuous light having wavelength λ1 to photodiode 215 without modulating it to generate an unmodulated local oscillator signal. Therefore, when mode switching unit 202b receives a second switching signal from switching signal generator 201, mode switching unit 202b switches the connection of first optical switch 220 so that the output of first optical switch 220 is directly input to second optical switch 221 without passing through IQ modulator 219, as shown in FIG. 8. For example, mode switching unit 202b switches the connection of first optical switch 220 so that the light source unit 213 and second optical switch 221 are connected. Furthermore, mode switching unit 202b switches the connection of second optical switch 221 so that the output of first optical switch 220 is input to photodiode 215, as shown in FIG. 8. For example, mode switching unit 202b switches the connection of second optical switch 221 so that the output of first optical switch 220 is connected to photodiode 215. As a result, the mode switching unit 202b inputs the continuous light of wavelength λ1 in an unmodulated state to the photodiode 215. Then, an unmodulated high-frequency signal is generated in the photodiode 215. In the second embodiment, this process is a process for generating an unmodulated high-frequency signal.

[0072] The first optical switch 220 has one or more first ports and a plurality of second ports. The first optical switch 220 outputs light input from the first port from one of a plurality of second ports. A light source unit 213 is connected to one or more first ports of the first optical switch 220, and an IQ modulator 219 and a second optical switch 221 are connected to a plurality of second ports of the first optical switch 220. The first optical switch 220 switches the connection relationship between the ports in response to a switching signal output from the switching signal generation unit 201.

[0073] For example, when a first switching signal is received from the switching signal generation unit 201, the first optical switch 220 connects the first port to which the light source unit 213 is connected and the second port to which the IQ modulator 219 is connected. As a result, the continuous light of wavelength λ1 output from the light source unit 213 is input to the IQ modulator 219. As a result, the continuous light of wavelength λ1 is modulated in the IQ modulator 219. For example, when a second switching signal is received from the switching signal generation unit 201, the first optical switch 220 connects the first port to which the light source unit 213 is connected and the second port to which the second optical switch 221 is connected. As a result, the continuous light of wavelength λ1 output from the light source unit 213 is input to the second optical switch 221. In other words, the continuous light of wavelength λ1 output from the light source unit 213 is input to the second optical switch 221 without being modulated.

[0074] The second optical switch 221 has a plurality of first ports and one or more second ports. The second optical switch 221 outputs light input from the first port from the second port. An IQ modulator 219 and a light source unit 213 are connected to the plurality of first ports of the second optical switch 221, and an optical coupler 214 is connected to one or more second ports of the second optical switch 221. The second optical switch 221 switches the connection relationship between the ports in response to a switching signal output from the switching signal generation unit 201.

[0075] For example, when the second optical switch 221 receives a first switching signal from the switching signal generator 201, it connects the first port connected to the IQ modulator 219 with the second port connected to the optical coupler 214. As a result, continuous light with wavelength λ1 modulated by the IQ modulator 219 (modulated optical signal with wavelength λ1) is input to the optical coupler 214. As a result, as shown in FIG. 7, a signal with frequency F IFWhen the second optical switch 221 receives the second switching signal from the switching signal generating unit 201, for example, the second optical switch 221 connects the first port connected to the first optical switch 220 with the second port connected to the optical coupler 214. As a result, the continuous light with wavelength λ1 output from the light source unit 213 is input to the optical coupler 214 without being modulated. As a result, as shown in FIG. 8, a modulated high frequency signal with frequency F IF An unmodulated high frequency signal having the following is generated.

[0076] The processing of the functional units other than the mode switching unit 202b included in the transceiver 200b is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0077] In the wireless communication system 100b configured as described above, the transceiver 200b includes a first optical switch 220 and a second optical switch 221 that switch between outputting a continuous light beam with wavelength λ1 to a path that modulates the continuous light beam with wavelength λ1 and outputting a continuous light beam with wavelength λ1 to a path that does not modulate the continuous light beam, depending on the operating mode. This allows a single signal source to be shared to generate modulated and unmodulated high-frequency signals. This reduces the cost of wireless devices used for wireless communication.

[0078] (Third embodiment) In the third embodiment, a configuration will be described in which two systems are provided, one for generating a modulated high-frequency signal and the other for generating an unmodulated high-frequency signal, and the modulated high-frequency signal and the unmodulated high-frequency signal are switched using a switch.

[0079] 9 and 10 are diagrams showing an example of the configuration of a wireless communication system 100c according to the third embodiment. The wireless communication system 100c includes a transceiver 200c and a transceiver 300c. Fig. 9 shows the transceiver 200c transmitting, and Fig. 10 shows the transceiver 200c receiving. Although Figs. 9 and 10 show a configuration in which the wireless communication system 100c includes one transceiver 200c and one transceiver 300c, the wireless communication system 100c may include multiple transceivers 200c and multiple transceivers 300c.

[0080] Transceiver 200c includes switching signal generation unit 201, mode switching unit 202c, first switch 203, second switch 204, branching unit 205, branching unit 206, first mixer 207, delay unit 208, second mixer 209, ADC 210, DSP 211, and antenna 212. Note that transceiver 300c may have the same configuration as transceiver 200c, or may have the configuration of a general transceiver that communicates in TDD mode. Transceiver 200c is one aspect of a wireless device.

[0081] The transceiver 200c differs from the transceivers 200a and 200b in the configuration related to the mode switching unit 202c. The other configurations of the transceiver 200c are similar to those of the transceivers 200a and 200b. The following description will focus on the differences between the transceivers 200a and 200b and the transceiver 200c.

[0082] The mode switching unit 202c switches the operation mode between the modulation mode and the non-modulation mode in response to the switching signal output from the switching signal generation unit 201. The mode switching unit 202c is composed of a light source unit 213, a DSP 216, a DAC 217, a bias power supply 218, an IQ modulator 219, a first optical coupler 222, a second optical coupler 223, a first photodiode 224, a second photodiode 225, and a third switch 226.

[0083] The light source unit 213 outputs four continuous light beams having different wavelengths λ1, λ2, λ3, and λ4. For example, the continuous light beams having wavelengths λ1 and λ2 are used to generate a modulated high-frequency signal, and the continuous light beams having wavelengths λ3 and λ4 are used to generate an unmodulated high-frequency signal. Therefore, the light source unit 213 outputs two continuous light beams having wavelengths λ1 and λ2 when the mode switching unit 202c operates in the modulation mode, and outputs two continuous light beams having wavelengths λ3 and λ4 when the mode switching unit 202c operates in the unmodulation mode. The continuous light beam having wavelength λ1 output by the light source unit 213 is input to the IQ modulator 219, and the continuous light beam having wavelength λ2 is input to the first optical coupler 222. The first optical coupler 222 multiplexes the continuous light beam having wavelength λ2 output from the light source unit 213 with the modulated optical signal having wavelength λ1 output from the IQ modulator 219. The first optical coupler 222 outputs the combined optical signal to the first photodiode 224 .

[0084] Furthermore, the continuous light of wavelength λ3 and the continuous light of wavelength λ4 output from light source unit 213 are input to second optical coupler 223. Second optical coupler 223 multiplexes the continuous light of wavelength λ3 and the continuous light of wavelength λ4 output from light source unit 213. Second optical coupler 223 outputs the multiplexed optical signal to second photodiode 225. The frequency of the signal generated by the first photodiode 224 is the frequency difference between the wavelengths λ1 and λ2. The frequency of the signal generated by the second photodiode 225 is the frequency difference between the wavelengths λ3 and λ4. Therefore, when the frequencies of the transmission signal and the local oscillator signal are the same, the wavelengths λ1 to λ4 should be set so that the frequency differences between the wavelengths λ1 and λ2 and the wavelengths λ3 and λ4 are the same.

[0085] When the transceiver 200c operates in the modulation mode, it is necessary to generate a transmission signal by modulating continuous light of wavelength λ1 in order to generate a modulated high-frequency signal in the first photodiode 224. Therefore, the mode switching unit 202c adjusts the bias voltage V DCis set to V0, and a modulation signal for the transmission code sequence is applied via the electrode terminal for applying the I component signal and the electrode terminal for applying the Q component signal. This causes the mode switching unit 202c to modulate the input continuous light of wavelength λ1. The output of the IQ modulator 219 is then input to the first photodiode 224 via the first optical coupler 222, generating a modulated high-frequency signal. Furthermore, as shown in FIG. 9 , the mode switching unit 202c switches the connection of the third switch 226 so that the output of the first photodiode 224 is input to the first switch 203. For example, the mode switching unit 202c switches the connection of the third switch 226 so that the first photodiode 224 and the first switch 203 are connected. This causes the modulated high-frequency signal generated by the first photodiode 224 to be output to the first switch 203. As a result, the modulated high-frequency signal can be transmitted as a transmission signal via the antenna 212, as in the first and second embodiments. In the third embodiment, this process is for generating a modulated high-frequency signal.

[0086] When the transceiver 200c operates in the unmodulated mode, it is necessary to generate an unmodulated local oscillator signal. Therefore, when the mode switching unit 202c receives a second switching signal from the switching signal generating unit 201, the mode switching unit 202c switches the connection of the third switch 226 so that the output of the second photodiode 225 is input to the first switch 203, as shown in FIG. 10 . For example, the mode switching unit 202c switches the connection of the third switch 226 so that the second photodiode 225 and the first switch 203 are connected. As a result, the unmodulated high-frequency signal generated by the second photodiode 225 is output to the first switch 203. As a result, the unmodulated high-frequency signal can be used as a local oscillator signal, as in the first and second embodiments. In the third embodiment, this process is for generating an unmodulated high-frequency signal.

[0087] The first photodiode 224 generates a modulated high-frequency signal based on the combined optical signal output from the first optical coupler 222. The first photodiode 224 outputs the generated modulated high-frequency signal to the third switch 226. The second photodiode 225 generates an unmodulated high-frequency signal based on the combined optical signal output from the second optical coupler 223. The second photodiode 225 outputs the generated unmodulated high-frequency signal to the third switch 226.

[0088] The third switch 226 switches the connection destination in response to the switching signal output from the switching signal generation unit 201. For example, when the third switch 226 receives a first switching signal from the switching signal generation unit 201, the third switch 226 connects the first photodiode 224 and the first switch 203 as shown in FIG. 9. As a result, the third switch 226 outputs the modulated high-frequency signal output from the first photodiode 224 to the first switch 203. For example, when the third switch 226 receives a second switching signal from the switching signal generation unit 201, the third switch 226 connects the second photodiode 225 and the first switch 203 as shown in FIG. 10. As a result, the third switch 226 outputs the unmodulated high-frequency signal output from the second photodiode 225 to the first switch 203.

[0089] The processing of the functional units other than the mode switching unit 202c included in the transceiver 200c is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0090] In the wireless communication system 100c configured as described above, the transceiver 200c includes a first photodiode 224 for generating a modulated high-frequency signal, a second photodiode 225 for generating an unmodulated high-frequency signal, and a third switch 226 for switching the output source depending on the operating mode. This allows a single signal source to be shared to generate the modulated high-frequency signal and the unmodulated high-frequency signal. This reduces the cost of the wireless device used for wireless communication.

[0091] (Fourth embodiment) In the fourth embodiment, a configuration will be described in which the operation mode is switched between the modulation mode and the non-modulation mode based on a signal processing unit (DSP) that performs signal processing on a transmission signal sequence.

[0092] 11 and 12 are diagrams showing an example of the configuration of a wireless communication system 100d according to the fourth embodiment. The wireless communication system 100d includes a transceiver 200d and a transceiver 300d. Fig. 11 shows the transceiver 200d in transmission mode, and Fig. 12 shows the transceiver 200d in reception mode. Note that although Figs. 11 and 12 show a configuration in which the wireless communication system 100d includes one transceiver 200d and one transceiver 300d, the wireless communication system 100d may include multiple transceivers 200d and multiple transceivers 300d.

[0093] The transceiver 200d includes a switching signal generator 201, a first switch 203, a second switch 204, a branching unit 205, a branching unit 206, a first mixer 207, a delay unit 208, a second mixer 209, an ADC 210, a DSP 211, an antenna 212, a light source unit 213, an optical coupler 214, a photodiode 215, a DSP 216d, a DAC 217, a bias power supply 218, an IQ modulator 219, a first RF driver amplifier 227, and a second RF driver amplifier 228. The transceiver 300d may have the same configuration as the transceiver 200d, or may have the configuration of a general transceiver that communicates using the TDD system. The transceiver 200d is one aspect of a wireless device.

[0094] Transceiver 200d differs from transceiver 200a in that DSP 216d realizes the function of switching the operation mode between the modulation mode and the unmodulation mode in response to a switching signal output from switching signal generator 201, and in that transceiver 200d is newly equipped with first RF driver amplifier 227 and second RF driver amplifier 228. The rest of the configuration of transceiver 200d is similar to that of transceiver 200a. The following description will focus on the differences from transceiver 200a.

[0095] The DSP 216d switches the operation mode between the modulation mode and the non-modulation mode in response to the switching signal output from the switching signal generator 201. When the transceiver 200d operates in the modulation mode, it is necessary to generate a transmission signal by modulating continuous light with a wavelength λ1. Therefore, the DSP 216d adjusts the bias voltage V of the IQ modulator 219. DC is set to V0, and a modulation signal for the transmission code sequence is applied via the electrode terminal for applying the I component signal and the electrode terminal for applying the Q component signal. This makes it possible to generate a transmission signal by modulating continuous light with wavelength λ1. In the fourth embodiment, this process is a process for generating a modulated high-frequency signal. Thus, the process for generating a modulated high-frequency signal in the fourth embodiment is the same as that in the first embodiment.

[0096] When the transceiver 200d operates in unmodulated mode, the DSP 216d generates unmodulated light by varying the modulation signals for the I and Q components it generates. Details are explained below. Figure 11(a) shows a constellation of modulated optical signals. Here, we show an example of QPSK (Quadrature Phase Shift Keying), a four-level modulation method. The IQ modulator 219 can assume any state on the IQ plane by combining the voltage values ​​of the modulation signals applied to the I and Q terminals. In the case of QPSK, this results in one of four points. As shown in Figure 11(a), a point on the first quadrant of the IQ plane is designated A. On the IQ plane, the distance r from the origin represents the optical intensity, and the angle θ represents the optical phase.

[0097] Based on the above background knowledge, we will consider a method for generating unmodulated light. The modulation signal voltages at the I and Q terminals of the IQ modulator 219 for state A are I A , Q A Here, the IQ modulator 219 is always set to I A , Q AIf a voltage of 1 / 2 V is continuously applied, state A is maintained regardless of time. In this case, the distance r and angle θ are constant over time, so the intensity and phase of the light do not change and unmodulated light can be generated. To achieve this, a constant voltage (I A , Q A ), i.e., a DC signal must be applied.

[0098] However, the first RF driver amplifier 227 and the second RF driver amplifier 228, which are arranged when the voltage output from the DAC 217 is insufficient, do not pass DC components, and as a result, it is expected that a constant voltage cannot be applied to the I terminal and the Q terminal of the IQ modulator 219. The first RF driver amplifier 227 is an amplifier that amplifies the I component modulated signal. The second RF driver amplifier 228 is an amplifier that amplifies the Q component modulated signal. To solve this problem, it is effective to generate the I component modulated signal and the Q component modulated signal so as to impart phase rotation so as to rotate on the IQ plane at a constant speed (frequency Δf) while maintaining the radius r ((C) of FIG. 12). That is, the DSP 216d generates the I component modulated signal and the Q component modulated signal so as to impart phase rotation so as to rotate on the IQ plane at a constant speed (frequency Δf) while maintaining the radius r. In this case, the phase rotation of the light becomes faster by the frequency Δf with respect to the reference wavelength λ1, and as a result, the frequency of the signal (unmodulated high frequency signal) output by the photodiode 215 becomes F IF +Δf. An unmodulated high-frequency signal can be generated by setting the frequency Δf higher than the DC cutoff frequencies of the first RF driver amplifier 227 and the second RF driver amplifier 228 within the range permitted by the DSP 211. In the fourth embodiment, this processing is processing for generating an unmodulated high-frequency signal.

[0099] In the wireless communication system 100d configured as described above, when the transceiver 200d operates in modulation mode, it generates a modulated high-frequency signal using the method described in the first embodiment. When the transceiver 200d operates in unmodulated mode, the I-component modulation signal and the Q-component modulation signal generated by the DSP 216d are changed (for example, by applying a phase rotation so that they rotate on the IQ plane at a constant speed (frequency Δf) while maintaining the radius r). This allows unmodulated light to be generated without changing the optical intensity and phase of the modulated optical signal with wavelength λ1 generated by the IQ modulator 219. This allows modulated high-frequency signals and unmodulated high-frequency signals to be generated using a single shared signal source. This reduces the cost of wireless devices used for wireless communication.

[0100] (Fifth embodiment) In the first to fourth embodiments, a configuration has been shown in which the light source and the antenna are installed in the same device (for example, a device in the same housing). In contrast to this, in recent years, a configuration has been proposed in which a signal processing configuration (signal processing unit) and an antenna configuration (antenna unit) are functionally separated, and the signal processing unit and the antenna unit are connected by an optical transmission path, as in analog RoF (Radio-over-Fiber). Therefore, in the fifth embodiment, a case will be described in which the present invention is applied to a configuration in which the signal processing unit and the antenna unit are functionally separated.

[0101] Figures 13 and 14 are diagrams showing an example of the configuration of a wireless communication system 100e according to the fifth embodiment. The wireless communication system 100e includes a wireless device 250e and a transceiver 300e. Figure 13 shows the wireless device 250e transmitting, and Figure 14 shows the wireless device 250e receiving. Note that although Figures 13 and 14 show a configuration in which the wireless communication system 100e includes one wireless device 250e and one transceiver 300e, the wireless communication system 100e may include multiple wireless devices 250e and multiple transceivers 300e.

[0102] As shown in FIGS. 13 and 14, the radio device 250e includes a signal processing unit 305 and an antenna unit 400. In this manner, the radio device 250e has a configuration in which the signal processing function and the wireless communication function are separated. The signal processing unit 305 and the antenna unit 400 are connected by an optical transmission path 340. The optical transmission path is, for example, an optical fiber. The optical transmission path may include one or more optical amplifiers for amplifying the optical signal. The antenna unit 400 is installed in a location different from the location where the signal processing unit 305 is installed. A single signal processing unit 305 may be connected to multiple antenna units 400. The transceiver 300e may have the same configuration as any of the transceivers 200 to 200d, or may have the configuration of a general transceiver that communicates using the TDD method. The transceiver 200e is one aspect of a radio device.

[0103] The signal processing unit 305 includes a mode switching unit 202, a light source unit 213, a wavelength multiplexer / demultiplexer 310, and an optical receiving unit 320. The mode switching unit 202 is a functional unit that performs processing similar to that of the first embodiment, for example. The wavelength multiplexer / demultiplexer 310 multiplexes or demultiplexes input optical signals according to their wavelengths. The optical receiving unit 320 receives the optical signals demultiplexed by the wavelength multiplexer / demultiplexer 310.

[0104] The antenna unit 400 includes a switching signal generating unit 201e, a first switch 203, a second switch 204, a branching unit 205, a branching unit 206, a first mixer 207, a delay unit 208, a second mixer 209, an antenna 212, a photodiode 215, a wavelength multiplexer / demultiplexer 410, an LD 420, and an IQ modulator 430.

[0105] As in the first embodiment, the mode switching unit 202, the first switch 203, and the second switch 204 can appropriately operate by switching their operation and connection relationship based on a switching signal transmitted by the switching signal generation unit 201e. However, in the fifth embodiment, the mode switching unit 202 is provided in a different position from the first switch 203 and the second switch 204. In this case, if the switching signal generation unit 201e transmits switching signals to the mode switching unit 202, the first switch 203, and the second switch 204 simultaneously, there will be a large difference in the arrival timing of the switching signals. For example, the switching signal generation unit 201e is provided in the same functional unit (e.g., the antenna unit 400) as the first switch 203 and the second switch 204, while the mode switching unit 202 is provided in the signal processing unit 305. Therefore, it is expected that the timing at which the switching signal arrives at the mode switching unit 202 will be later than the timing at which the switching signal arrives at the first switch 203 and the second switch 204.

[0106] To avoid such problems, it is effective for the switching signal generation unit 201 to adjust the transmission time slots of the switching signals transmitted to the mode switching unit 202, the first switch 203, and the second switch 204. Therefore, the switching signal generation unit 201e includes a scheduling information acquisition unit 2011 and a transmission timing adjustment unit 2012. The scheduling information acquisition unit 2011 acquires information (time slot information) indicating uplink and downlink transmission times of TDD. The scheduling information acquisition unit 2011 generates switching signals to be transmitted to the mode switching unit 202, the first switch 203, and the second switch 204, based on the acquired information indicating the transmission times. For example, since the downlink time slot is a time slot during which the radio device 250e transmits, the scheduling information acquisition unit 2011 generates a first switching signal. Since the uplink time slot is a time slot during which the radio device 250e receives, the scheduling information acquisition unit 2011 generates a second switching signal.

[0107] The transmission timing adjustment unit 2012 controls the transmission timing of the switching signal so that the operation can be switched at appropriate timing in each of the mode switching unit 202, first switch 203, and second switch 204, which are destinations of the switching signal. For example, the transmission timing adjustment unit 2012 adjusts the transmission timing by imparting an appropriate delay to the transmission timing of the switching signal. In the examples shown in FIGS. 13 and 14, the distance between the mode switching unit 202 and the switching signal generation unit 201e is longer than that between the first switch 203 and the second switch 204. Therefore, the transmission timing adjustment unit 2012 transmits the switching signal to the mode switching unit 202 first, and imparts a delay to the switching signals to be transmitted to the first switch 203 and the second switch 204, thereby delaying the transmission timing. The delay provided by transmission timing adjustment unit 2012 may be determined according to the ratio of the transmission time between switching signal generation unit 201e and mode switching unit 202, the transmission time between switching signal generation unit 201e and first switch 203, and the transmission time between switching signal generation unit 201e and second switch 204, or may be determined by some other method. The processing of transmission timing adjustment unit 2012 is to adjust the transmission timing of the switching signal so that the switching signal arrives at mode switching unit 202, first switch 203, and second switch 204 at approximately the same timing, and mode switching and connection relationship switching are performed simultaneously.

[0108] The LD 420 is a light source for upstream communication. Therefore, the LD 420 operates during the reception time period of the radio device 250e. The LD 420 outputs light of wavelength λ3, for example. The IQ modulator 430 modulates the light of wavelength λ3 output from the LD 420 using the signal obtained by the first mixer 207 and the signal obtained by the second mixer 209. As a result, the IQ modulator 430 generates a modulated optical signal of wavelength λ3. The IQ modulator 430 outputs the generated modulated optical signal of wavelength λ3 to the wavelength multiplexer / demultiplexer 410. The wavelength multiplexer / demultiplexer 410 multiplexes or demultiplexes the input optical signals. The modulated optical signal of wavelength λ3 transmitted from the antenna unit 400 is demultiplexed by the wavelength multiplexer / demultiplexer 310 of the signal processing unit 305 and received by the optical receiving unit 320. The optical receiving unit 320 decodes the received code sequence based on the received modulated optical signal of wavelength λ3.

[0109] For downstream communication, the same processing as in the first embodiment is performed.

[0110] According to the wireless communication system 100e configured as above, even in a configuration in which the signal processing function and the wireless communication function are separated, it is possible to obtain the same effects as those of the first embodiment.

[0111] (Variation) In the above-described embodiment, the mode switching unit 202 has the same functions as the mode switching unit 202a in the first embodiment. However, the mode switching unit 202 may have a configuration corresponding to the mode switching units shown in the second to fourth embodiments. For example, the mode switching unit 202 may be the mode switching unit 202b in the second embodiment. For example, the mode switching unit 202 may have a partial configuration shown in the mode switching unit 202c in the third embodiment (e.g., excluding the first optical coupler 222, the second optical coupler 223, the first photodiode 224, the second photodiode 225, and the third switch 226). In this case, the antenna unit 400 includes the first optical coupler 222, the second optical coupler 223, the first photodiode 224, the second photodiode 225, and the third switch 226.

[0112] (Sixth embodiment) In the fifth embodiment, a configuration was shown in which a light source arranged in the antenna unit is used as the wavelength λ3 for upstream communication. Furthermore, in the modulation during upstream communication, the frequencies of the received signal and the local oscillator signal match, and the output of the mixer becomes a baseband signal. On the other hand, in a typical analog RoF, an intermediate frequency (IF) signal is used as the modulation signal, rather than a baseband signal. Therefore, in the sixth embodiment, a configuration in which an intermediate frequency signal is used as the modulation signal will be described.

[0113] Figures 15 and 16 are diagrams showing an example of the configuration of a wireless communication system 100f according to the sixth embodiment. The wireless communication system 100f includes a wireless device 250f and a transceiver 300f. Figure 15 shows the wireless device 250f transmitting, and Figure 16 shows the wireless device 250f receiving. Note that although Figures 15 and 16 show a configuration in which the wireless communication system 100f includes one wireless device 250f and one transceiver 300f, the wireless communication system 100f may include multiple wireless devices 250f and multiple transceivers 300f.

[0114] As shown in FIGS. 15 and 16 , the radio device 250f includes a signal processing unit 305 and an antenna unit 400f. In this manner, the radio device 250f has a configuration in which the signal processing function and the wireless communication function are separated. The signal processing unit 305 and the antenna unit 400f are connected by multiple optical transmission paths 350 and 360. The optical transmission path 350 is a transmission path used for downstream communication from the signal processing unit 305. The optical transmission path 360 is a transmission path used for upstream communication from the antenna unit 400f. The antenna unit 400f is installed in a location different from the location where the signal processing unit 305 is installed. Note that multiple antenna units 400f may be connected to one signal processing unit 305. Note that the transceiver 300f may have a configuration similar to any of the transceivers 200 to 200d, or may have the configuration of a general transceiver that communicates using the TDD method.

[0115] The functional units included in the signal processing unit 305 are the same as those in the fifth embodiment. The processing of the signal processing unit 305 differs from that in the fifth embodiment in that the light source unit 213 outputs three continuous light beams having different wavelengths λ1, λ2, and λ3. The continuous light beams having wavelengths λ1, λ2, and λ3 output from the light source unit 213 are multiplexed by the wavelength multiplexer / demultiplexer 310 to generate a multiplexed signal. The wavelength multiplexer / demultiplexer 310 outputs the generated multiplexed signal to the antenna unit 400f via the optical transmission path 350.

[0116] The antenna unit 400f includes a switching signal generating unit 201e, a first switch 203, a second switch 204, a branching unit 205, a branching unit 206, a first mixer 207, a delay unit 208, a second mixer 209, an antenna 212, a photodiode 215, a wavelength multiplexer / demultiplexer 410, a mixer 440, a polarization controller 450, and an MZ modulator 460.

[0117] The wavelength multiplexer / demultiplexer 410 multiplexes or demultiplexes the input optical signals. For example, the wavelength multiplexer / demultiplexer 410 demultiplexes a multiplexed signal (e.g., a multiplexed signal of continuous light with wavelengths λ1, λ2, and λ3) transmitted from the signal processing unit 305 according to wavelength. The wavelength multiplexer / demultiplexer 410 outputs the continuous light with wavelengths λ1 and λ2 to the photodiode 215, and outputs the continuous light with wavelength λ3 to the polarization controller 450.

[0118] The mixer 440 receives the unmodulated high frequency signal (local oscillator signal) output from the first switch 203 and the received signal received by the antenna 212. The mixer 440 multiplies the input unmodulated high frequency signal (local oscillator signal) by the received signal, thereby down-converting the electrical signal corresponding to the received signal to an intermediate frequency. In order to generate an intermediate frequency signal, the frequency F of the received signal is IF For the frequency of the local oscillator signal, F' IF Here, the frequency F explained in the first embodiment needs to be shifted by IF is the intermediate frequency (carrier frequency) of the radio signal transmitted by the antenna 212, while F' IF is the intermediate frequency of the optical signal in the upstream optical transmission. As a method for shifting the frequency, the DSP 216d may be used as described in the fourth embodiment, or the wavelength λ1 or λ2 may be shifted in the light source unit 213.

[0119] The polarization controller 450 controls the polarization of the input optical signal. For example, the polarization controller 450 aligns the polarization of the continuous light with wavelength λ3 demultiplexed by the wavelength division multiplexer / demultiplexer 410 with the polarization axis of the MZ modulator 460.

[0120] The MZ modulator 460 intensity-modulates the continuous light of wavelength λ3 using the continuous light of wavelength λ3 whose polarization has been adjusted by the polarization controller 450 and the intermediate frequency signal (IF signal) output from the mixer 440. The MZ modulator 460 is a Mach-Zehnder modulator. The MZ modulator 460 transmits the modulated optical signal of wavelength λ3 generated by intensity modulation to the signal processing unit 305 via the optical transmission path 360. The modulated optical signal of wavelength λ3 is then received by the optical receiving unit 320 included in the signal processing unit 305. The optical receiving unit 320 decodes the received code sequence based on the received modulated optical signal of wavelength λ3.

[0121] According to the wireless communication system 100f configured as above, even in a configuration in which an intermediate frequency signal is used as a modulated signal, it is possible to obtain the same effects as those of the fifth embodiment.

[0122] (Variation 1) The wireless communication system 100f may be modified in the same manner as the wireless communication system 100e.

[0123] (Variation 2) In the above-described embodiment, a configuration has been shown in which intensity modulation is performed using continuous light with wavelength λ3 whose polarization has been adjusted by the polarization controller 450 and an intermediate frequency signal (IF signal) output from the mixer 440. However, the antenna unit 400f shown in this embodiment may modulate both intensity and phase. In this case, the antenna unit 400f may include an IQ modulator instead of the MZ modulator 460.

[0124] (Seventh embodiment) In the above-described embodiments, a configuration in which a high-frequency signal is generated using an optical beat method has been described. In contrast, in the seventh embodiment, a configuration in which a high-frequency signal is generated using a method using an electric circuit will be described. FIG. 17 is a diagram showing an example configuration of a wireless communication system 100g in the seventh embodiment. The wireless communication system 100g includes a transceiver 200g and a transceiver 300g. FIG. 17 shows the transceiver 200g during transmission. Note that, although FIG. 17 shows a configuration in which the wireless communication system 100g includes one transceiver 200g and one transceiver 300g, the wireless communication system 100g may include multiple transceivers 200g and multiple transceivers 300g.

[0125] Transceiver 200g includes switching signal generation unit 201, mode switching unit 202g, first switch 203, second switch 204, branching unit 205, branching unit 206, first mixer 207, delay unit 208, second mixer 209, ADC 210, DSP 211, and antenna 212. Note that transceiver 300g may have the same configuration as transceiver 200g, or may have the configuration of a general transceiver that communicates in the TDD system.

[0126] The mode switching unit 202g switches the operation mode between the modulation mode and the non-modulation mode in response to the switching signal output from the switching signal generation unit 201. The mode switching unit 202g is composed of a DSP 216, a DAC 217, a high-frequency signal generation IC 230, and a modulator 231.

[0127] The high-frequency signal generating IC 230 is an integrated circuit that generates a high-frequency signal such as a terahertz wave and outputs the generated high-frequency signal. The high-frequency signal generating IC 230 outputs the generated high-frequency signal to the modulator 231.

[0128] When the transceiver 200g operates in the modulation mode, the DAC 217 applies a modulation signal based on the transmission code sequence generated by the DSP 216 to the modulator 231. This processing is processing for generating a modulated high-frequency signal in the modified example. When the transceiver 200g operates in the unmodulated mode, the DAC 217 does not apply a modulation signal based on the transmission code sequence generated by the DSP 216 to the modulator 231. This processing is processing for generating an unmodulated high-frequency signal in the modified example.

[0129] As described above, when the transceiver 200g operates in the modulation mode, the high-frequency signal output from the high-frequency signal generating IC 230 and the modulated signal output from the DAC 217 are input to the modulator 231. Therefore, the modulator 231 generates a modulated high-frequency signal based on the input high-frequency signal and the modulated signal. On the other hand, when the transceiver 200g operates in the unmodulated mode, no modulated signal is applied from the DAC 217, and only the high-frequency signal output from the high-frequency signal generating IC 230 is input to the modulator 231. Therefore, the modulator 231 outputs the input high-frequency signal as an unmodulated unmodulated signal.

[0130] When the transceiver 200g operates in the modulation mode, the modulated high-frequency signal output from the modulator 231 is input to the antenna 212 via the first switch 203 and the second switch 204. When the transceiver 200g operates in the non-modulation mode, the non-high-frequency signal output from the modulator 231 is input to the branching unit 205 via the first switch 203. As a result, the non-high-frequency signal output from the modulator 231 is used as a local oscillator signal.

[0131] In the wireless communication system 100g configured as described above, even in a configuration in which a high-frequency signal is generated in an electrical circuit, the high-frequency signal output from a single signal source can be used as a transmission signal during transmission and as a local oscillator signal during reception. In other words, the transceiver 200g can share a single signal source (high-frequency signal generating IC 230). This eliminates the need for the transceiver 200g to have separate components for generating high-frequency signals for transmission and reception. This reduces the cost of the wireless device used for wireless communication.

[0132] (Variation) In the above-described embodiment, the mode switching unit 202g and the antenna 212 are installed in the same device (for example, in a device in the same housing). However, the mode switching unit 202g and the antenna 212 may be provided in different devices to form a wireless device. In such a configuration, the wireless device is made up of a signal processing unit and an antenna unit, and the signal processing unit and the antenna unit are connected using a wired electrical circuit. The signal processing unit includes at least the mode switching unit 202g, the ADC 210, and the DSP 211. The antenna unit includes at least the switching signal generating unit 201, the first switch 203, the second switch 204, the branching unit 205, the branching unit 206, the first mixer 207, the delay unit 208, the second mixer 209, and the antenna 212. In this case, the switching signal generating unit 201 may be provided with a scheduling information acquiring unit 2011 and a transmission timing adjusting unit 2012, as described in FIG. 13, so that the timing of mode switching can be adjusted between the signal processing unit and the antenna unit.

[0133] In each of the above-described embodiments, some or all of the functional units of the transceivers 200, 200a, 200b, 200c, 200d, and 200g and the wireless devices 250e and 250f are implemented as software by one or more processors, such as a central processing unit (CPU), executing a program stored in a storage device having a non-volatile storage medium (non-transitory storage medium) and a memory. The program may be recorded on a computer-readable non-transitory storage medium. Examples of computer-readable non-transitory storage media include portable media such as flexible disks, magneto-optical disks, read-only memories (ROMs), and compact disc-ROMs (CD-ROMs), and storage devices such as hard disks built into computer systems.

[0134] Some or all of the functional units of the transceivers 200, 200a, 200b, 200c, 200d, and 200g and the wireless devices 250e and 250f may be realized using hardware including electronic circuits (electronic circuits or circuitry) using, for example, an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0135] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention. [Explanation of symbols]

[0136] 100, 100a, 100b, 100c, 100d, 100f...wireless communication system, 200, 200a, 200b, 200c, 200d, 200g, 300, 300a, 300b, 300c, 300d, 300f, 300g...transceiver, 201, 201e...switching signal generation unit, 202, 202a, 202b, 202c...mode switching unit, 203...first switch, 204...second switch, 205, 206...branching unit, 207...first mixer, 208...delay unit, 209...second mixer, 210...ADC, 211...DSP, 212...antenna, 213...light source unit, 214...optical coupler 215...photodiode, 216, 216d...DSP, 217...DAC, 218...bias power supply, 219...IQ modulator, 220...first optical switch, 221...second optical switch, 222...first optical coupler, 223...second optical coupler, 224...first photodiode, 225...second photodiode, 226...third switch, 227...first RF driver amplifier, 228...second RF driver amplifier, 230...high frequency signal generating IC, 231...modulator, 250e, 250f...radio device, 305...signal processing unit, 310...wavelength multiplexer / demultiplexer, 320...optical receiving unit, 400...antenna unit, 410...wavelength multiplexer / demultiplexer, 420...LD, 430...IQ modulator, 440...mixer, 450...Polarization controller, 460...MZ modulator, 2011...Scheduling information acquisition unit, 2012...Transmission timing adjustment unit

Claims

1. a switching signal generating unit that generates a switching signal for transmission or reception according to a predetermined transmission time zone and a predetermined reception time zone; a mode switching unit that switches between a modulation mode in which processing for generating a modulated high-frequency signal is performed and a non-modulation mode in which processing for generating an unmodulated high-frequency signal is performed according to the type of the switching signal generated by the switching signal generating unit, thereby generating either a modulated high-frequency signal or an unmodulated high-frequency signal; a switch that outputs a modulated high frequency signal to a path that uses the modulated high frequency signal as a transmission signal when a transmission switching signal is received, and outputs an unmodulated high frequency signal to a path that uses the unmodulated high frequency signal as a local oscillator signal when a reception switching signal is received; A wireless device comprising:

2. The mode switching unit When operating in the modulation mode, a modulated signal output from a signal processing unit that performs signal processing on data to be transmitted and a bias voltage that extinguishes the first modulator are applied to the first modulator to generate the modulated high-frequency signal; When operating in the unmodulated mode, the modulated signal is not output to the first modulator, and a bias voltage that does not cause the first modulator to extinguish is applied to the first modulator to generate an unmodulated high frequency signal. Or, When operating in the modulation mode, a modulated signal output from a signal processing unit that performs signal processing on data to be transmitted and a high-frequency signal output from a high-frequency signal generating device that generates a signal in a high-frequency band are modulated by a second modulator, and the modulated high-frequency signal is output; When operating in the unmodulated mode, the unmodulated high frequency signal is output by not outputting the modulated signal to the second modulator.

10. The wireless device of claim 1.

3. The mode switching unit a first optical switch that outputs light of a specific wavelength output from a light source to a modulator or to a path that does not pass through the modulator; a second optical switch that outputs the output of the modulator or the first optical switch to the switch; The first optical switch When operating in the modulation mode, light of a specific wavelength output from the light source is output to the modulator; The second optical switch is When operating in the modulation mode, outputting the output of the modulator to the switch; The first optical switch When operating in the non-modulation mode, light of a specific wavelength output from the light source is output to a path that does not pass through the modulator; The second optical switch is When operating in the non-modulation mode, an output of the first optical switch is output to the switch.

10. The wireless device of claim 1.

4. The mode switching unit When operating in the unmodulated mode, an I-component modulation signal and a Q-component modulation signal are generated to impart a phase rotation so as to rotate at a constant speed on an IQ plane, and the unmodulated high-frequency signal is generated by applying the generated I-component modulation signal and the Q-component modulation signal to a modulator.

10. The wireless device of claim 1.

5. The mode switching unit a signal processing unit having a signal processing function in a configuration in which a signal processing function and a wireless communication function are separated, The switching signal generation unit and the switch The antenna unit having the wireless communication function is provided 5. A wireless device according to any one of claims 1 to 4.

6. The switching signal generation unit a transmission timing adjustment unit that controls a timing at which the switching signal is transmitted to the mode switching unit and the switch; the transmission timing adjustment unit controls the timing of transmitting the switching signal so that the switching signal arrives at the mode switching unit and the switch at the same timing.

6. The wireless device of claim 5.

7. The antenna unit is a mixer that generates an intermediate frequency signal based on an externally received signal and the local oscillator signal; and a modulator that performs modulation using the intermediate frequency signal.

6. The wireless device of claim 5.

8. generating a switching signal for transmission or reception according to a predetermined transmission time zone and a predetermined reception time zone; switching between a modulation mode in which processing for generating a modulated high-frequency signal is performed and a non-modulation mode in which processing for generating an unmodulated high-frequency signal is performed according to the type of the switching signal, thereby generating either a modulated high-frequency signal or an unmodulated high-frequency signal; When a switching signal for transmission is obtained, the modulated high frequency signal is output to a path that is used as a transmission signal, A signal processing method in which, when a switching signal for reception is obtained, an unmodulated high frequency signal is output to a path that is used as a local oscillator signal.

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