Wireless communication method

Abstract

The present invention provides a wireless communication method for a wireless communication system that comprises an accomodation station device and a base station device that performs beamforming under the control of the accommodation station device. The accommodation station device generates an optical modulated signal by controlling any combination of optical wavelength, frequency, or optical polarization or a plurality of frequencies or optical wavelengths to modulate the intensity of an optical signal on the basis of a transmission signal to be transmitted. The accommodation station device transmits the optical modulated signal to the base station device over an optical transmission line to perform beamforming control of the base station device. The optical modulated signal is transmitted after dispersion compensation has been performed at an electrical or optical area of the accommodation station device, or dispersion compensation is performed on the optical modulated signal along the optical transmission line. The base station device inputs an electrical signal based on the optical modulated signal on which the dispersion compensation has been performed into a beamforming circuit that has a plurality of input ports and thereby performs beamforming in a direction that corresponds to the input port into which the electrical signal has been inputted.　

Description

[Technical field]

[0001] The present invention relates to a wireless communication method. [Background technology]

[0002] Conventionally, wireless communication using the millimeter wave band, which allows high-speed transmission, has been attracting attention. However, when using the millimeter wave band, there is a problem that propagation loss is large and long-distance transmission is difficult. Although the RoF (Radio over Fiber) system enables long-distance transmission of RF signals (Radio Frequency signals) in the millimeter wave band, the coverage area of ​​the antenna unit is an issue. One solution to this problem is beamforming using an array antenna. As a beamforming technology using the RoF system or optical technology, the technology described in Patent Document 1 or Non-Patent Document 1 has been proposed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4246724 [Non-patent literature]

[0004] [Non-Patent Document 1] Dennis TK Tong, Ming C. Wu, “A Novel Multiwavelength Optically Controlled Phased Array Antenna with a Programmable Dispersion Matrix”, IEEE Photonics Technology Letters, June 1996, VOL.8, NO.6, p.812-814. Summary of the Invention [Problem to be solved by the invention]

[0005] 23 is a diagram for explaining an overview of a wireless communication system 100 in Patent Document 1. The wireless communication system 100 includes a station device 200 and a base station device 300. The station device 200 and the base station device 300 are connected via an optical fiber 400. The station device 200 modulates a plurality of optical signals having a specific wavelength interval output from a multi-wavelength tunable light source 201 using an optical modulator 202, and transmits the modulated optical signals to the base station device 300. At this time, when the optical fiber 400 transmits optical modulated signals of a plurality of wavelengths, a delay difference that differs for each wavelength occurs due to the effect of chromatic dispersion.

[0006] The base station device 300 splits the optical modulated signal transmitted from the exchange device 200 into wavelengths using the optical splitter 301, and converts the split signals into electrical signals using O / Es 302-1 to 302-p (p is an integer equal to or greater than 1). The electrical signals are fed to the antennas 303-1 to 303-p, but delay differences occur between the electrical signals due to delay differences caused by chromatic dispersion that occurs when the electrical signals are transmitted through the optical fiber 400, and directivity is formed when the electrical signals are radiated as radio waves. Therefore, the beam direction can be controlled by controlling the wavelength of the optical signal output by the multi-wavelength tunable light source 201.

[0007] However, depending on the beam direction, the optical fiber length, and the frequency of the RF signal, it may be necessary to make the wavelength interval of the optical signal extremely large or small. In the former case, the wavelength band to be used becomes wide, and the wavelength utilization efficiency may decrease. On the other hand, in the latter case, it becomes difficult to control the multi-wavelength tunable light source 201.

[0008] In addition, in the technology of Patent Document 1, the optical wavelength is dynamically controlled to dynamically control the beam direction, so the demultiplexing mechanism of the optical demultiplexer 301 provided in the base station device 300 must also be dynamically controlled. This requires control of the base station device 300, which limits the simplification of the base station device 300. Furthermore, in the technology of Patent Document 1, optical fiber distance information is required for wavelength adjustment to adjust the delay difference between each optical signal. In general, the length of the optical fiber 400 between the exchange device 200 and the base station device 300 is often unknown, or even if it is known, the exact length is not known. Therefore, it is considered that the scope of application of the technology of Patent Document 1 is limited.

[0009] FIG. 24 is a diagram for explaining the technology described in Non-Patent Document 1. The device shown in FIG. 24 includes a multi-wavelength tunable light source 501, an optical modulator 502, a PDM (Programmable Dispersion Matrix) 503, an optical demultiplexer 504, O / Es 505-1 to 505-p, and antennas 506-1 to 506-p. FIG. 25 is a diagram showing a configuration example of a conventional PDM 503. As shown in FIG. 25, the PDM 503 includes a plurality of optical switches 511-1 to 511-q (q is an integer of 2 or more) and a plurality of delay units 512-1 to 512-q. In the technology described in Non-Patent Document 1, different optical wavelengths are fixedly associated with each antenna, unlike the technology in Patent Document 1. In addition, the PDM 503 controls the dispersion value, controls the delay difference for each optical wavelength, and controls the beam direction.

[0010] In the technology described in Non-Patent Document 1, the optical wavelength is fixed, so the wavelength utilization efficiency is better than that of Patent Document 1. In addition, the optical demultiplexing is also fixed, so there is no need to control the optical demultiplexer. However, it is believed that high precision is required in the design and manufacture of the PDM for controlling dispersion, and there is a risk that the equipment will become larger and more expensive.

[0011] Moreover, the technology described in Non-Patent Document 1 does not mention application to RoF. When applying RoF to the technology described in Non-Patent Document 1 for long-distance optical fiber transmission, it is necessary to consider the effect of chromatic dispersion during optical fiber transmission in addition to dispersion control by PDM. Furthermore, both the technologies in Patent Document 1 and Non-Patent Document 1 only mention beamforming of the transmitting antenna, and do not mention beamforming of the receiving antenna. Furthermore, in the conventional configuration, there is no mention of beam width control, and further, it is difficult to control not only the phase but also the amplitude of the signal fed to each antenna element, making it difficult to remotely control the width of the beam sent from the base station device.

[0012] In view of the above circumstances, an object of the present invention is to provide a technique capable of controlling the beam and beam width of a transmitting and receiving antenna without the need for control of a base station device and distance information of optical fibers. [Means for solving the problem]

[0013] One aspect of the present invention is a wireless communication method in a wireless communication system including a station device and a base station device that performs beam forming in accordance with the control of the station device, in which the station device controls any combination of optical wavelengths, frequencies, or optical polarization, or multiple frequencies or multiple optical wavelengths, to intensity-modulate an optical signal based on a transmission signal to be transmitted, thereby generating an optical modulated signal, and transmits the generated optical modulated signal to the base station device via an optical transmission path to perform beamforming control of the base station device, and transmits the optical modulated signal after dispersion compensation has been performed in the electrical domain or optical domain in the station device, or performs dispersion compensation on the optical modulated signal on the optical transmission path, and the base station device inputs an electrical signal based on the optical modulated signal that has been dispersion compensated to a beam forming circuit having multiple input ports, thereby performing beam forming in a direction according to the input port to which the electrical signal is input. Effect of the Invention

[0014] According to the present invention, it is possible to control the beam and beam width of a transmitting / receiving antenna without the need for control of a base station device or distance information of an optical fiber. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to a first embodiment. [Diagram 2] 4 is a sequence diagram showing a processing flow of the wireless communication system in the first embodiment. FIG. [Diagram 3] FIG. 11 is a diagram illustrating an example of the configuration of a wireless communication system according to a second embodiment. [Figure 4] FIG. 11 is a sequence diagram showing a processing flow of the wireless communication system in the second embodiment. [Diagram 5] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system according to a third embodiment. [Figure 6] FIG. 11 is a sequence diagram showing a processing flow of a wireless communication system in the third embodiment. [Figure 7] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system according to a fourth embodiment. [Figure 8] FIG. 13 is a sequence diagram showing a processing flow of a wireless communication system in the fourth embodiment. [Figure 9] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system according to a fifth embodiment. [Figure 10] FIG. 13 is a sequence diagram showing a processing flow of a wireless communication system in the fifth embodiment. [Figure 11] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system according to a modified example of the fifth embodiment. [Figure 12] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system according to a sixth embodiment. [Figure 13] FIG. 13 is a sequence diagram showing a processing flow of a wireless communication system in the sixth embodiment. [Figure 14] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system in a seventh embodiment. [Figure 15]FIG. 13 is a sequence diagram showing a processing flow of a wireless communication system in the seventh embodiment. [Figure 16] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system in an eighth embodiment. [Figure 17] FIG. 23 is a sequence diagram showing a processing flow of a wireless communication system in the eighth embodiment. [Figure 18] FIG. 13 is a diagram illustrating an example of the configuration of a wireless communication system in a ninth embodiment. [Figure 19] FIG. 13 is a sequence diagram showing a processing flow of a wireless communication system in a ninth embodiment. [Figure 20] FIG. 23 is a diagram illustrating an example of the configuration of a wireless communication system in a tenth embodiment. [Figure 21] FIG. 23 is a sequence diagram showing a processing flow of a wireless communication system in a tenth embodiment. [Figure 22] FIG. 23 is a diagram illustrating an example of the configuration of a wireless communication system in a modified example of the tenth embodiment. [Diagram 23] FIG. 1 is a diagram for explaining an overview of a wireless communication system in Patent Document 1. [Figure 24] FIG. 1 is a diagram for explaining the technology described in Non-Patent Document 1. [Diagram 25] FIG. 1 is a diagram illustrating an example of the configuration of a conventional PDM. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (overview) In the present invention, in a system including an exchange device and a base station device connected by an optical transmission line, the base station device is provided with a Butler matrix as a beam forming circuit. The exchange device performs chromatic dispersion compensation, or chromatic dispersion compensation and polarization mode dispersion compensation, so that an RF signal (Radio Frequency signal) is input in phase to each input port of the Butler matrix. Furthermore, the exchange device remotely controls the beam and beam width of the base station device by switching any combination of optical wavelength, frequency, or optical polarization, or multiple frequencies or multiple optical wavelengths. This makes it possible to control the beam and beam width of the transmitting and receiving antennas without the need for control of the base station device and distance information of the optical fiber. A specific configuration will be described below using an embodiment as an example.

[0017] (First embodiment) FIG. 1 is a diagram showing a configuration example of a wireless communication system 1 in the first embodiment. The wireless communication system 1 includes a accommodating station device 10 and a base station device 20. The accommodating station device 10 and the base station device 20 are connected via an optical transmission path 30. The optical transmission path 30 is, for example, an optical fiber. The optical transmission path 30 may be one or more single-core fibers or may be a multi-core fiber having one or more cores. In the following description, the direction from the accommodating station device 10 to the base station device 20 is referred to as the downlink direction, and the direction from the base station device 20 to the accommodating station device 10 is referred to as the uplink direction.

[0018] 1 shows a case where there is one base station device 20, but the wireless communication system 1 may include multiple base station devices 20. In this case, the corresponding station device 10 and the multiple base station devices 20 may be connected by a passive optical network (PON). When the corresponding station device 10 and the multiple base station devices 20 are connected by a PON, an optical splitter (branching section) is provided between the corresponding station device 10 and the multiple base station devices 20. The optical splitter branches an optical signal output from the corresponding station device 10 and outputs the branched optical signal to the base station device 20. The passive optical network is, for example, a WDM-PON (Wavelength Division Multiplexing - Passive Optical Network) or a TDM-PON (Time Division Multiplexing - Passive Optical Network).

[0019] The exchange device 10 remotely controls the beam of the base station device 20 by switching the optical wavelength of the transmission signal. The exchange device 10 remotely controls the beam of the base station device 20 by using analog RoF technology. Note that the transmission signal in the first embodiment is an RF signal.

[0020] The base station device 20 radiates the signal transmitted from the exchange device 10 by radio.

[0021] Next, a specific configuration of the exchange device 10 and the base station device 20 will be described. The exchange device 10 includes a control unit 11, an optical modulation unit 12, and a chromatic dispersion compensation unit 13.

[0022] The control unit 11 selects an optical wavelength according to a direction in which a beam is to be formed in the base station device 20. For example, the control unit 11 selects an applicable optical wavelength λ as an optical wavelength to be used in the optical modulation unit 12. T1 ,…,λ Tn Select one of the combinations.

[0023] The optical modulation unit 12 modulates a transmission signal in the RF band with a plurality of selected optical wavelengths λ Tj In this way, the optical modulation unit 12 modulates the intensity of each of the optical signals having a plurality of optical wavelengths λ Tj The optical modulated signals generated by the optical modulation unit 12 are wavelength division multiplexed (WDM) by an optical multiplexer (not shown) to generate wavelength division multiplexed signals.

[0024] The chromatic dispersion compensation unit 13 performs chromatic dispersion compensation for wavelength division multiplexing. By performing chromatic dispersion compensation in the chromatic dispersion compensation unit 13, it becomes possible to input an RF signal in phase to each input port of the Butler matrix. Here, a configuration in which chromatic dispersion compensation is performed in the optical domain is shown, but chromatic dispersion compensation may be performed in the electrical domain, and the same applies in the following explanation.

[0025] The base station device 20 includes an optical demultiplexer 21, a plurality of O / Es 22, a beam forming circuit 23, and a plurality of antennas 24-1 to 24-N.

[0026] The optical demultiplexer 21 demultiplexes the optical modulated signal received via the optical transmission line 30 according to wavelength. For example, the optical demultiplexer 21 is an arrayed waveguide grating (AWG). The optical modulated signals demultiplexed by the optical demultiplexer 21 are input to each O / E 22.

[0027] The O / E 22 is an opto-electrical conversion unit that converts the optically modulated signal output from the optical demultiplexer 21 into an electrical signal.

[0028] The beam forming circuit 23 is n (n∈Z + )) input ports and N output ports, where N is an integer equal to or greater than 1. The beam forming circuit 23 is, for example, a Butler matrix (see, for example, Reference 1).

[0029] (Reference 1: Wei Hong, Zhi Hao Jiang, Chao Yu, Jianyi Zhou, Peng Chen, Zhiqiang Yu, Hui Zhang, Binqi Yang, Xingdong Pang, Mei Jiang, Yujian Cheng, Mustafa K. Taher Al-Nuaimi, Yan Zhang, Jixin Chen, and Shiwen He, “Multibeam antenna technologies for 5G wireless communications”, IEEE Transactions on Antennas and Propagation, 65(12), 6231-6249 (2017).)

[0030] When an RF signal is input to one input port of the Butler matrix that is the beam forming circuit 23, RF signals with equal amplitude and linearly inclined phases are output from all output ports. The phase inclination differs depending on the input port. Beam forming is possible by providing antennas 24-1 to 24-N at the output ports. Beam switching is possible by switching the port through which the RF signal is input, and the formed beams are orthogonal to each other.

[0031] By inputting the same RF signal in phase to multiple input ports of the Butler matrix, which is the beam forming circuit 23, it becomes possible to form a sector beam by combining adjacent orthogonal beams. In other words, it is also possible to switch the sector beam by switching the combination of input ports.

[0032] The N O / Es 22 are connected to input ports of the beam forming circuit 23. The N antennas 24 are connected to output ports of the beam forming circuit 23. The N input ports of the beam forming circuit 23 receive in-phase electrical signals output from the N O / Es 22.

[0033] FIG. 2 is a sequence diagram showing a processing flow of the wireless communication system 1 in the first embodiment. The control unit 11 selects a plurality of optical wavelengths according to a direction in which a beam is to be formed in the base station device 20 (step S101). For example, the control unit 11 selects optical wavelengths λ T1 ,…,λ Tn Among them, multiple optical wavelengths λ Tj The control unit 11 selects the selected optical wavelengths λ Tj The optical modulator 12 is controlled so as to modulate the optical intensity of the optical signal.

[0034] The optical modulation unit 12 modulates the transmission signal with a plurality of optical wavelengths λ designated by the control unit 11. Tj The optical signals are intensity-modulated (step S102). As a result, the optical modulation unit 12 modulates the intensity of the selected optical wavelength λ Tj The plurality of optical modulated signals generated by the optical modulation unit 12 are wavelength division multiplexed by an optical multiplexer (not shown) to generate a wavelength division multiplexed signal.

[0035] The chromatic dispersion compensating unit 13 performs chromatic dispersion compensation on the wavelength division multiplexing (step S103), and outputs the wavelength division multiplexing that has been subjected to chromatic dispersion compensation to the optical transmission line 30 (step S104).

[0036] The wavelength division multiplexed signal sent to the optical transmission line 30 is input to the base station device 20. The optical demultiplexer 21 of the base station device 20 demultiplexes the input wavelength division multiplexed signal according to the wavelength (step S105). The output ports of the optical demultiplexer 21 are connected to O / Es 22 in a number corresponding to the number of wavelengths. Therefore, the optical modulated signals demultiplexed by the optical demultiplexer 21 for each wavelength are output to the O / Es 22 connected to the output ports corresponding to the wavelengths.

[0037] The O / E 22 converts the input optical modulated signal into an electrical signal (step S106). Through this process, the optical modulated signal is converted into an electrical signal. The O / E 22 outputs the converted electrical signal to the beam forming circuit 23. The beam forming circuit 23 forms a beam in a direction corresponding to the input port to which the electrical signal is input. Since chromatic dispersion compensation is performed, an in-phase RF signal is input to the input port of the beam forming circuit 23. As a result, a wireless signal is emitted from the antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input. The antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input radiates a wireless signal corresponding to the input electrical signal (step S107).

[0038] According to the wireless communication system 1 configured as above, by switching the optical wavelength of the transmission signal in the exchange device 10, the direction of the transmission beam can be remotely switched. Furthermore, the exchange device 10 performs chromatic dispersion compensation and transmits the signal to the base station device 20. This makes it possible to suppress the influence of chromatic dispersion occurring in the optical transmission path 30. Since the influence of chromatic dispersion can be suppressed, signals transmitted from the exchange device 10 at the same timing can be input in phase to the beam forming circuit 23 provided in the base station device 20. As a result, the width of the beam transmitted from the base station device 20 can be controlled. Therefore, it becomes possible to control the beam and beam width of the transmitting and receiving antennas without the need for control of the base station device and distance information of the optical fiber.

[0039] In the wireless communication system 1, the transmission beam can be switched by switching the combination of optical wavelengths of the transmission signal of the exchange device 10. Furthermore, in the wireless communication system 1, multiple beams can be formed by wavelength division multiplexing using multiple combinations of optical wavelengths simultaneously.

[0040] Second Embodiment The second embodiment differs from the first embodiment in that the exchange device controls the frequency of a transmission signal to remotely control beam forming of a base station device. The second embodiment will be described focusing on the differences from the first embodiment.

[0041] The exchange device 10a remotely controls the beam of the base station device 20a by switching the frequency of the transmission signal. Note that the transmission signal in the second embodiment may be a BB signal (Base Band signal), an IF signal (Intermediate Frequency signal), or an RF signal.

[0042] The exchange device 10a includes a control unit 11a, an optical modulation unit 12a, a chromatic dispersion compensation unit 13, and a frequency conversion unit . The control unit 11a selects a frequency according to a direction in which a beam is to be formed in the base station device 20a. For example, the control unit 11a selects N frequencies f T1 ,…,f TN Select one of the combinations.

[0043] The frequency converter 14 converts the input transmission signal into a plurality of frequencies f designated by the controller 11a. Ti Here, i is an integer between 1 and N.

[0044] The optical modulation unit 12a modulates each frequency f Ti The optical modulation unit 12a uses the transmission signal to intensity-modulate each optical signal of a certain wavelength. In this way, the optical modulation unit 12a generates a plurality of optical modulated signals. The optical modulation unit 12a subcarrier-multiplexes the plurality of optical modulated signals.

[0045] The base station device 20a includes an O / E 22, a splitter 25, a plurality of frequency conversion units 26-1 to 26-N, a beam forming circuit 23, and a plurality of antennas 24-1 to 24-N.

[0046] The demultiplexer 25 demultiplexes the electrical signal extracted by the O / E 22 (for example, a subcarrier multiplexed electrical signal) according to frequency.

[0047] The frequency conversion units 26-1 to 26-N convert the frequency of the input electrical signal into a frequency in the RF band.

[0048] Frequency conversion units 26-1 to 26-N are connected to input ports of the beam forming circuit 23. Antennas 24-1 to 24-N are connected to output ports of the beam forming circuit 23. Electric signals output from the O / E 22 are input in phase to the N input ports of the beam forming circuit 23.

[0049] FIG. 4 is a sequence diagram showing a process flow of the wireless communication system 1a in the second embodiment. The control unit 11a selects a number of frequencies according to the direction in which the base station device 20a is to form a beam (step S201). For example, the control unit 11a selects N frequencies f T1 ,…,f TN Among these, several frequencies f Ti The control unit 11a selects the frequency of the transmission signal from the selected multiple frequencies f Ti The frequency converter 14 is controlled so as to convert the signal into each of the frequencies.

[0050] The frequency converter 14 converts the input transmission signal into each frequency f designated by the controller 11a. Ti (step S202). The frequency converter 14 converts each frequency f Ti The optical modulation unit 12a converts the frequency f Ti The optical modulation unit 12a uses each of the transmission signals to intensity-modulate an optical signal of a certain wavelength (step S203). As a result, the optical modulation unit 12a generates a plurality of optical modulated signals. The optical modulation unit 12a subcarrier-multiplexes the generated plurality of optical modulated signals to generate a subcarrier multiplexed signal. The optical modulation unit 12a outputs the generated subcarrier multiplexed signal to the chromatic dispersion compensation unit 13.

[0051] The chromatic dispersion compensator 13 performs chromatic dispersion compensation on the subcarrier multiplexed signal (step S204), and transmits the subcarrier multiplexed signal after the chromatic dispersion compensation process to the optical transmission line 30 (step S205).

[0052] The subcarrier multiplexed signal transmitted to the optical transmission path 30 is input to the base station device 20a. The O / E 22 of the base station device 20a converts the input subcarrier multiplexed signal into an electrical signal (step S206). The O / E 22 outputs the electrical signal to the demultiplexer 25. The electrical signal output to the demultiplexer 25 is demultiplexed according to frequency (step S207).

[0053] A plurality of frequency conversion units 26-1 to 26-N are connected to the output ports of the demultiplexer 25. For example, T1 The output port of the splitter 25 corresponding to the frequency f is connected to the frequency converter 26-1. Ti The frequency converter 26-i is connected to the output port of the duplexer 25 corresponding to the frequency f TN The frequency converter 26-N is connected to the output port of the splitter 25 corresponding to the frequency f. Therefore, the electrical signals split by frequency by the splitter 25 are output to the frequency converter 26 connected to the output port corresponding to the frequency. Ti It is assumed that the electrical signal is split by splitter 25 and input to frequency converter 26-i.

[0054] The frequency conversion unit 26-i converts the frequency of the input electrical signal into an RF band frequency (step S208). The frequency conversion unit 26-i outputs the RF band electrical signal to the beam forming circuit 23. The beam forming circuit 23 forms a beam in a direction corresponding to the input port to which the electrical signal is input. Since chromatic dispersion compensation is performed, an in-phase RF signal is input to the input port of the beam forming circuit 23. As a result, a radio signal is emitted from the antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input. The antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input radiates a radio signal corresponding to the input electrical signal (step S209).

[0055] According to the wireless communication system 1a configured as above, by switching the frequency of the transmission signal in the corresponding station device 10a, the direction of the transmission beam can be remotely switched. Furthermore, the corresponding station device 10a performs chromatic dispersion compensation and transmits the signal to the base station device 20a. This makes it possible to suppress the influence of chromatic dispersion occurring in the optical transmission line 30. Since the influence of chromatic dispersion can be suppressed, signals transmitted from the corresponding station device 10a at the same timing can be input in phase to the beam forming circuit 23 provided in the base station device 20a. As a result, the width of the beam transmitted from the base station device 20a can be controlled. Therefore, it becomes possible to control the beam and beam width of the transmitting and receiving antennas without the need for control of the base station device and distance information of the optical fiber.

[0056] Furthermore, in the wireless communication system 1a, by allocating frequencies to the beam forming circuit 23, control of the base station device 20a and optical fiber distance information are not required, and the base station device 20a can be simplified.

[0057] In the wireless communication system 1, the transmission beam can be switched by switching the combination of the frequencies of the transmission signals of the exchange device 10a. Furthermore, in the wireless communication system 1a, multiple beams can be formed by simultaneously using a combination of multiple frequencies to perform subcarrier multiplexing.

[0058] (Modification of the second embodiment) The exchange device 10a may be configured to perform subcarrier multiplexing (SCM) by simultaneously using a plurality of frequencies, thereby forming multiple beams in the base station device 20a.

[0059] (Third embodiment) The third embodiment differs from the first embodiment in that the exchange device controls the optical wavelength and frequency to remotely control the beam forming of the base station device. The third embodiment will be described focusing on the differences from the first embodiment.

[0060] 5 is a diagram showing a configuration example of a wireless communication system 1b according to the third embodiment. The wireless communication system 1b includes a terminating station 10b and a base station 20b. The terminating station 10b and the base station 20b are connected to each other via an optical transmission path 30.

[0061] The exchange device 10b remotely controls the beam of the base station device 20b by switching the frequency and optical wavelength of the transmission signal. Note that the transmission signal in the third embodiment may be a BB signal, an IF signal, or an RF signal.

[0062] The exchange device 10b includes a control unit 11b, an optical modulation unit 12b, a chromatic dispersion compensation unit 13, and a frequency conversion unit .

[0063] The control unit 11b selects a frequency and an optical wavelength according to a direction in which a beam is to be formed in the base station device 20b. For example, the control unit 11b selects an applicable optical wavelength λ as an optical wavelength to be used in the optical modulation unit 12b. T1 ,…,λ Tn For example, the control unit 11b selects one or more of the optical wavelengths λ Tj Applicable frequency f j T1 ,…,f j Tmj Select one or more of the following: m is an integer of 1 or more; j is an integer of 1 or more.

[0064] The frequency converter 14 converts the input transmission signal into a frequency f designated by the controller 11b. j Ti Convert to.

[0065] The optical modulation unit 12b modulates the frequency f j Ti Using the signal, a certain wavelength λ designated by the control unit 11b is Tj As a result, the optical modulation unit 12b modulates the intensity of the optical signal of wavelength λ Tj The optical modulation signal is generated.

[0066] The base station device 20b includes an optical splitter 21, a plurality of O / Es 22, a plurality of splitters 25, a plurality of frequency converters 26, a beam forming circuit 23, and a plurality of antennas 24-1 to 24-N. Although not shown in FIG. 5 for the sake of simplicity, the O / Es 22 and splitters 25 are connected to an optical wavelength λ T The frequency converter 26 must be provided for the optical wavelength λ Tj The number of frequencies used by m j It is necessary to be prepared for this.

[0067] A frequency conversion unit 26 is connected to an input port of the beam forming circuit 23. N antennas 24 are connected to output ports of the beam forming circuit 23. Electric signals output from the frequency conversion unit 26 are input in phase to the N input ports of the beam forming circuit 23.

[0068] FIG. 6 is a sequence diagram showing a process flow of a wireless communication system 1b in the third embodiment. The control unit 11b selects a frequency and an optical wavelength according to a direction in which a beam is to be formed in the base station device 20b (step S301). For example, the control unit 11b selects a frequency f j T1 ,…,f j Tmj One frequency f j Ti Furthermore, the control unit 11b selects the optical wavelength λ T1 ,…,λ Tn One of the optical wavelengths λ Tj The control unit 11b selects the selected frequency f j Ti Further, the control unit 11b controls the frequency conversion unit 14 so as to convert the frequency of the selected optical wavelength λ Tj The optical modulator 12b is controlled so as to modulate the light intensity with the

[0069] The frequency converter 14 converts the input transmission signal into a frequency f designated by the controller 11b. j Ti (Step S302). The frequency converter 14b converts the frequency f jTi The optical modulator 12b outputs the transmission signal of the optical wavelength λ designated by the control unit 11b. Tj With respect to the frequency f j Ti The optical modulation unit 12b performs intensity modulation using the transmission signal of the optical wavelength λ Tj The optical modulation unit 12b outputs the generated optical modulation signal to the chromatic dispersion compensation unit 13.

[0070] The chromatic dispersion compensator 13 performs chromatic dispersion compensation on the optical modulated signal (step S304), and transmits the optical modulated signal after the chromatic dispersion compensation process to the optical transmission line 30 (step S305).

[0071] The optically modulated signal transmitted to the optical transmission line 30 is input to the base station device 20b. The optical demultiplexer 21 of the base station device 20b demultiplexes the input optical wavelength λ Tj The optical modulated signal is demultiplexed (step S306). The O / E 22 is connected to the output port of the optical demultiplexer 21 according to the number of optical wavelengths. Therefore, the optical modulated signal demultiplexed by the optical demultiplexer 21 for each wavelength is output to the O / E 22 connected to the output port corresponding to the wavelength. In FIG. 6, Tj Assume that the optical modulated signal is demultiplexed by the optical demultiplexer 21 and input to the O / E 22.

[0072] The O / E 22 converts the input optical modulated signal into an electrical signal (step S307). j Ti The O / E22 is converted into an electrical signal of frequency f j Ti The electrical signal of frequency f j Ti The electrical signal is demultiplexed according to frequency (step S308). The electrical signals demultiplexed by the demultiplexer 25 are input to the frequency conversion unit .

[0073] The frequency conversion unit 26 converts the frequency of the input electrical signal into an RF band frequency (step S309). The frequency conversion unit 26 outputs the RF band electrical signal to the beam forming circuit 23. The beam forming circuit 23 forms a beam in a direction corresponding to the input port to which the electrical signal is input. Since chromatic dispersion compensation is performed, an in-phase RF signal is input to the input port of the beam forming circuit 23. As a result, a radio signal is emitted from the antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input. The antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input radiates a radio signal corresponding to the input electrical signal (step S310).

[0074] According to the wireless communication system 1b configured as above, by switching the combination of the optical wavelength and frequency of the transmission signal in the corresponding station device 10b, the direction of the transmission beam can be remotely switched. Furthermore, the corresponding station device 10b performs chromatic dispersion compensation and transmits the signal to the base station device 20b. This makes it possible to suppress the influence of chromatic dispersion occurring in the optical transmission line 30. Since the influence of chromatic dispersion can be suppressed, signals transmitted from the corresponding station device 10b at the same timing can be input in phase to the beam forming circuit 23 provided in the base station device 20b. As a result, the width of the beam transmitted from the base station device 20b can be controlled. Therefore, it becomes possible to control the beam and beam width of the transmitting and receiving antennas without the need for control of the base station device and distance information of the optical fiber.

[0075] (Modification of the third embodiment) The exchange device 10b may be configured to simultaneously use a plurality of optical wavelengths and a plurality of frequencies to perform subcarrier multiplexing and wavelength division multiplexing, thereby forming multiple beams in the base station device 20b.

[0076] (Fourth embodiment) The fourth embodiment differs from the first embodiment in that the exchange device controls the optical polarization and frequency of the transmission signal to remotely control the beam forming of the base station device. The fourth embodiment will be described focusing on the differences from the first embodiment.

[0077] 7 is a diagram showing a configuration example of a wireless communication system 1c according to the fourth embodiment. The wireless communication system 1c includes a terminating station 10c and a base station 20c. The terminating station 10c and the base station 20c are connected to each other via an optical transmission path 30.

[0078] The exchange device 10c remotely controls the beam of the base station device 20c by switching the optical polarization and frequency of the transmission signal. Note that the transmission signal in the fourth embodiment may be a BB signal, an IF signal, or an RF signal.

[0079] The exchange device 10c includes a control unit 11c, an optical modulation unit 12c, a frequency conversion unit 14, and a chromatic dispersion / polarization mode dispersion compensation unit 15.

[0080] The control unit 11c selects a frequency and optical polarization according to the direction in which a beam is to be formed in the base station device 20c. For example, the control unit 11c selects one or more of the applicable optical polarizations X and Y as the optical polarization to be used in the optical modulation unit 12c. Here, X and Y represent horizontal polarization and vertical polarization, respectively. For example, the control unit 11c selects a frequency f applicable to the optical polarization k (k is X or Y). k T1 ,…,f k Tmk Select one or more of the following.

[0081] The frequency converter 14 converts the input transmission signal into a frequency f designated by the controller 11c. k Ti Convert to.

[0082] The optical modulation unit 12c has a frequency f k TiUsing this signal, the optical signal of a certain optical polarization k designated by the control unit 11c is intensity-modulated, whereby the optical modulation unit 12c generates an optical modulated signal of the optical polarization k.

[0083] The chromatic dispersion / polarization mode dispersion compensator 15 compensates for chromatic dispersion and polarization mode dispersion on the optical modulated signal of optical polarization k. By performing chromatic dispersion compensation and polarization mode dispersion in the chromatic dispersion / polarization mode dispersion compensator 15, it becomes possible to input an RF signal in phase to each input port of the Butler matrix. Here, a configuration in which chromatic dispersion compensation and polarization mode dispersion are performed in the optical domain is shown, but chromatic dispersion compensation and polarization mode dispersion may be performed in the electrical domain, and the same applies in the following explanation.

[0084] The base station device 20c includes a polarization splitter 27, a plurality of O / Es 22-X, 21-Y, a plurality of demultiplexers 25, a plurality of frequency converters 26, a beam forming circuit 23, and a plurality of antennas 24-1 to 24-N. Although not shown in FIG. 7 for the sake of simplicity, the O / Es 22 and demultiplexers 25 must be provided in the same number as the number of optical polarizations (e.g., 2), and the frequency converter 26 must be provided in the same number as the number m of frequencies used by the optical polarization X. X and the number of frequencies used by the optical polarization Y, m Y The total number of (m X +m Y It is necessary to have only one such device.

[0085] The polarization splitter 27 splits the optically modulated signal received via the optical transmission line 30 into k polarized optical components.

[0086] A plurality of frequency conversion units 26 are connected to input ports of the beam forming circuit 23. N antennas 24 are connected to output ports of the beam forming circuit 23. Electric signals output from the plurality of frequency conversion units 26 are input in phase to the N input ports of the beam forming circuit 23.

[0087] FIG. 8 is a sequence diagram showing a process flow of the wireless communication system 1c in the fourth embodiment. The control unit 11c selects a frequency and an optical polarization according to a direction in which a beam is to be formed in the base station device 20c (step S401). For example, the control unit 11c selects a frequency f X T1 ,…,f X Tmj One frequency f X Ti Furthermore, the control unit 11c selects one of the polarized lights, X, from the polarized lights k. The control unit 11c selects the selected frequency f X Ti The control unit 11c controls the frequency conversion unit 14 to perform frequency conversion on the selected optical signal of the optical polarization X. Furthermore, the control unit 11c controls the optical modulation unit 12c to perform optical intensity modulation on the selected optical signal of the optical polarization X.

[0088] The frequency converter 14 converts the input transmission signal into a frequency f designated by the controller 11c. X Ti (Step S402). The frequency converter 14c converts the frequency f X Ti The optical modulation unit 12c converts the optical signal of the optical polarization X designated by the control unit 11c into a signal of the frequency f X Ti The optical modulator 12c performs intensity modulation using the transmission signal of the optical polarization X (step S403). As a result, the optical modulator 12c generates an optical modulated signal of the optical polarization X. The optical modulator 12c outputs the generated optical modulated signal to the chromatic dispersion / polarization mode dispersion compensator 15.

[0089] The chromatic dispersion / polarization mode dispersion compensator 15 performs chromatic dispersion and polarization mode dispersion compensation on the optical modulated signal (step S404). The chromatic dispersion / polarization mode dispersion compensator 15 sends the optical modulated signal after the dispersion compensation process to the optical transmission line 30 (step S405).

[0090] The optical modulated signal sent to the optical transmission line 30 is input to the base station device 20c. The polarization separation unit 27 of the base station device 20c separates the optical polarization k component of the input optical modulated signal of the optical polarization X (step S406). The O / E 22-X, 21-Y are connected to the output port of the polarization separation unit 27 according to the number of polarizations. Therefore, the optical modulated signal separated by the polarization separation unit 27 is output to the O / E 22-X, 21-Y connected to the output port according to the optical polarization component. In FIG. 8, it is assumed that the optical modulated signal of the optical polarization X is separated by the polarization separation unit 27 and input to the O / E 22-X.

[0091] The O / E 22-X converts the input optical modulated signal into an electrical signal (step S407). Through this process, the optical modulated signal is converted into an electrical signal having a frequency f X Ti The O / E22-X converts the signal into an electrical signal of frequency f X Ti The electrical signal of frequency f X Ti The electrical signal is demultiplexed according to frequency (step S408). The electrical signals demultiplexed by the demultiplexer 25 are input to the frequency conversion unit .

[0092] The frequency conversion unit 26 converts the frequency of the input electrical signal into an RF band frequency (step S409). The frequency conversion unit 26 outputs the RF band electrical signal to the beam forming circuit 23. The beam forming circuit 23 forms a beam in a direction corresponding to the input port to which the electrical signal is input. Since chromatic dispersion compensation and polarization mode dispersion are performed, an in-phase RF signal is input to the input port of the beam forming circuit 23. As a result, a radio signal is emitted from the antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input. The antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input radiates a radio signal corresponding to the input electrical signal (step S410).

[0093] According to the wireless communication system 1c configured as above, by switching the combination of optical polarization and frequency of the transmission signal in the corresponding station device 10c, the direction of the transmission beam can be remotely switched. Furthermore, the corresponding station device 10c performs chromatic dispersion compensation and transmits the signal to the base station device 20c. This makes it possible to suppress the influence of chromatic dispersion occurring in the optical transmission line 30. Since the influence of chromatic dispersion can be suppressed, signals transmitted from the corresponding station device 10c at the same timing can be input in phase to the beam forming circuit 23 provided in the base station device 20c. As a result, the width of the beam transmitted from the base station device 20c can be controlled. Therefore, it becomes possible to control the beam and beam width of the transmitting and receiving antennas without the need for control of the base station device and distance information of the optical fiber.

[0094] (Modification of the fourth embodiment) The exchange device 10c may be configured to perform subcarrier multiplexing and polarization division multiplexing (PDM) by simultaneously using a plurality of optical polarizations and a plurality of frequencies, thereby forming multiple beams in the base station device 20c.

[0095] Fifth embodiment The fifth embodiment differs from the first embodiment in that the exchange device controls the optical wavelength and optical polarization of a transmission signal to remotely control beam forming of the base station device. The fifth embodiment will be described focusing on the differences from the first embodiment.

[0096] 9 is a diagram showing a configuration example of a wireless communication system 1d in the fifth embodiment. The wireless communication system 1d includes a terminating station 10d and a base station 20d. The terminating station 10d and the base station 20d are connected to each other via an optical transmission path 30.

[0097] The exchange device 10d remotely controls the beam of the base station device 20d by switching the optical wavelength and optical polarization of the transmission signal. Note that the transmission signal in the fifth embodiment is an RF signal.

[0098] The exchange device 10d includes a control unit 11d, an optical modulation unit 12d, and a chromatic dispersion / polarization mode dispersion compensator 15.

[0099] The control unit 11d selects an optical wavelength and optical polarization according to the direction in which a beam is to be formed in the base station device 20d. For example, the control unit 11d selects one or more of the applicable optical polarizations X and Y as the optical polarization to be used in the optical modulation unit 12d. For example, the control unit 11d selects an applicable optical wavelength λ T1 ,…,λ Tn Select one or more of the following.

[0100] The optical modulation unit 12d converts the RF transmission signal into an optical signal having a certain optical wavelength λ Tj The optical modulation unit 12d performs intensity modulation using an optical signal of optical polarization k, which is an optical wavelength λ Tj The optical modulation signal of the optical polarization k is generated.

[0101] The base station device 20d includes an optical splitter 21, a plurality of polarization splitters 27, a plurality of O / Es 22, a beam forming circuit 23, and a plurality of antennas 24-1 to 24-N. Although not shown in FIG. 9 for the sake of simplicity, the polarization splitter 27 is a splitter for an optical wavelength λ T The number of O / Es must be n, and the O / E22 is the optical wavelength λ Tj must be provided for each of the optical polarizations to be used (for example, 2).

[0102] A plurality of O / Es 22 are connected to input ports of the beam forming circuit 23. N antennas 24 are connected to output ports of the beam forming circuit 23. Electric signals output from the plurality of O / Es 22 are input in phase to the N input ports of the beam forming circuit 23.

[0103] FIG. 10 is a sequence diagram showing a process flow of the wireless communication system 1d in the fifth embodiment. The control unit 11d selects an optical polarization and an optical wavelength according to a direction in which a beam is to be formed in the base station device 20d (step S501). For example, the control unit 11d selects an optical wavelength λ T1 ,…,λ Tn One of the optical wavelengths λ Tj Furthermore, the control unit 11d selects one of the polarized lights k, that is, the polarized light X. The control unit 11d then selects the selected optical wavelength λ Tj The optical modulator 12d is controlled so as to modulate the optical intensity of the optical signal of the optical polarization X.

[0104] The optical modulator 12d modulates the transmission signal with an optical wavelength λ Tj The optical modulation unit 12d performs intensity modulation using an optical signal of the optical polarization X having an optical wavelength λ Tj The optical modulator 12d outputs the generated optical modulated signal to the chromatic dispersion / polarization mode dispersion compensator 15.

[0105] The chromatic dispersion / polarization mode dispersion compensator 15 performs chromatic dispersion and polarization mode dispersion compensation on the optical modulated signal (step S503). The chromatic dispersion / polarization mode dispersion compensator 15 sends the optical modulated signal after the dispersion compensation process to the optical transmission line 30 (step S504).

[0106] The optically modulated signal sent to the optical transmission line 30 is input to the base station device 20d. The optical demultiplexer 21 of the base station device 20d demultiplexes the input optically modulated signal according to the wavelength (step S505). A polarization separation unit 27 is connected to the output port of the optical demultiplexer 21 according to the number of wavelengths. Therefore, the optically modulated signal demultiplexed by the optical demultiplexer 21 is output to the polarization separation unit 27 connected to the output port according to the wavelength. In FIG. 10, Tj The optical modulated signal is split by the optical splitter 21 into optical wavelengths λ Tj The signal is input to the polarization separator 27 connected to an output port corresponding to the signal.

[0107] The polarization separation unit 27 separates the optical polarization k component of the optical modulated signal of the optical polarization X (step S506). An O / E 22 is connected to the output port of the polarization separation unit 27 according to the number of optical polarizations. Therefore, the optical modulated signal separated by the polarization separation unit 27 is output to the O / E 22 connected to the output port according to the optical polarization component. In FIG. 10, it is assumed that the optical modulated signal of the optical polarization X is separated by the polarization separation unit 27 and input to the O / E 22 connected to the output port of the optical polarization X.

[0108] The O / E 22 converts the input optical modulated signal into an electrical signal (step S507). Through this process, the optical modulated signal is converted into an electrical signal. The O / E 22 outputs the converted electrical signal to the beam forming circuit 23. The beam forming circuit 23 forms a beam in a direction corresponding to the input port to which the electrical signal is input. Since chromatic dispersion compensation and polarization mode dispersion have been performed, an in-phase RF signal is input to the input port of the beam forming circuit 23. As a result, a wireless signal is emitted from the antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input. The antenna 24 connected to the output port corresponding to the input port to which the electrical signal is input radiates a wireless signal corresponding to the input electrical signal (step S508).

[0109] According to the wireless communication system 1d configured as above, by switching the combination of the optical wavelength and the optical polarization of the transmission signal in the corresponding station device 10d, the direction of the transmission beam can be remotely switched. Furthermore, the corresponding station device 10d performs chromatic dispersion compensation and transmits the signal to the base station device 20d. This makes it possible to suppress the influence of chromatic dispersion occurring in the optical transmission line 30. Since the influence of chromatic dispersion can be suppressed, the signals transmitted from the corresponding station device 10d at the same timing can be input in phase to the beam forming circuit 23 provided in the base station device 20d. As a result, the width of the beam transmitted from the base station device 20d can be controlled. Therefore, it becomes possible to control the beam and the beam width of the transmitting and receiving antennas without the need for the control of the base station device and the distance information of the optical fiber.

[0110] (Modification of the fifth embodiment) The exchange device 10d may be configured to perform wavelength division multiplexing and polarization division multiplexing by simultaneously using a plurality of optical polarizations and a plurality of optical wavelengths, thereby forming multiple beams in the base station device 20d.

[0111] The accommodating station device 10d and the base station device 20d shown in Fig. 9 may be configured as shown in Fig. 11. Fig. 11 is a diagram showing a configuration example of a wireless communication system 1e in a modified example of the fifth embodiment. The wireless communication system 1e includes an accommodating station device 10e and a base station device 20e. The accommodating station device 10e and the base station device 20e are connected via an optical transmission path 30.

[0112] Compared to the exchange device 10d, the exchange device 10e does not include a chromatic dispersion / polarization mode dispersion compensator 15. The chromatic dispersion / polarization mode dispersion compensator 15 is provided on the optical transmission line 30 between the exchange device 10e and the base station device 20e.

[0113] The base station device 20e includes a polarization splitter 27, an optical demultiplexer 21, a plurality of O / Es 22, a beam forming circuit 23, and a plurality of antennas 24-1 to 24-N. Although not shown in FIG. 11 for the sake of simplicity, the number of optical demultiplexers 21 must be the same as the number of optical polarizations (for example, 2), and the number of O / Es 22 must be the number m of frequencies used by the optical polarization X. X and the number of frequencies used by the optical polarization Y, m Y The total number of (m X +m Y It is necessary to have only one such device.

[0114] A plurality of O / Es 22 are connected to input ports of the beam forming circuit 23. N antennas 24 are connected to output ports of the beam forming circuit 23. Electric signals output from the plurality of O / Es 22 are input in phase to the N input ports of the beam forming circuit 23.

[0115] In the base station device 20e shown in FIG. 9, the optical modulated signal received via the optical transmission path 30 is demultiplexed and then the optical polarization k component is separated, whereas in the base station device 20e, the optical modulated signal received via the optical transmission path 30 is demultiplexed and then the optical polarization k component is separated.

[0116] Alternatively, the exchange device 10e may be configured to perform wavelength division multiplexing and polarization division multiplexing by simultaneously using a plurality of optical polarizations and a plurality of optical wavelengths, thereby forming multiple beams in the base station device 20e.

[0117] Sixth embodiment In the first to fifth embodiments, the configuration of downstream signal transmission has been described. In the sixth embodiment, the configuration of upstream signal transmission will be described. In the sixth embodiment, the configuration of wavelength multiplexing in a base station device and transmitting a signal to an exchange device will be described.

[0118] 12 is a diagram showing a configuration example of a wireless communication system 1f in the sixth embodiment. The wireless communication system 1f includes a terminating station 10f and a base station 20f. The terminating station 10f and the base station 20f are connected to each other via an optical transmission path 30.

[0119] The base station device 20f includes a plurality of antennas 31-1 to 31-N, a beam forming circuit 32, a plurality of optical modulation sections 33-1 to 33-N, and an optical multiplexer .

[0120] The antennas 31-1 to 31-N receive radio signals transmitted from an external device. The external device is, for example, a radio device with which the base station device 20f communicates. The antennas 31-1 to 31-N convert the received radio signals into electrical signals and output them to the beam forming circuit 32.

[0121] The beam forming circuit 32 has N input ports and N output ports, similar to the beam forming circuit 23 in the first embodiment. The input ports of the beam forming circuit 32 are connected to optical modulation units 33-1 to 33-N. The output ports of the beam forming circuit 32 are connected to antennas 31-1 to 31-N. N frequency f T1 ,…, f TN have a one-to-one correspondence with the N input ports and N receiving beams of the beam forming circuit 23. The beam forming circuit 32 receives the electrical signals output from the antennas 31-1 to 31-N from its output ports, and outputs the signals to the optical modulation sections 33-1 to 33-N connected to the input ports.

[0122] The optical modulation sections 33-1 to 33-N intensity-modulate an optical signal of a certain wavelength using the electrical signal output from the beam forming circuit 32. In this way, the optical modulation section 33 generates an optical modulated signal.

[0123] The optical multiplexer 34 multiplexes and wavelength-division-multiplexes the optically modulated signals output from the optical modulation units 33-1 to 33-N, thereby generating a wavelength-multiplexed signal.

[0124] The exchange device 10f includes a chromatic dispersion compensator 41, an optical demultiplexer 42, a plurality of O / Es 43, and an output unit 44.

[0125] The chromatic dispersion compensator 41 performs chromatic dispersion compensation on the wavelength multiplexed signal received via the optical transmission line 30 .

[0126] The optical demultiplexer 42 demultiplexes, according to wavelength, the wavelength multiplexed signal that has been subjected to chromatic dispersion compensation by the chromatic dispersion compensator 41. For example, the optical demultiplexer 42 is an AWG. The optical signals demultiplexed by the optical demultiplexer 42 for each wavelength are input to the O / E 43.

[0127] The O / E 43 is an opto-electrical conversion unit that converts the optical signals demultiplexed by the optical demultiplexer 42 into electrical signals.

[0128] The output section 44 receives the input wavelength λ R1 ,…,λRm For example, the output section 44 demodulates the electrical signal corresponding to the input wavelength λ R1 ,…,λ Rm One of the electrical signals corresponding to the input frequency f may be selected and demodulated. This is equivalent to selecting one beam out of N reception beams. The output unit 44 can also form multiple beams by selecting multiple wavelengths and using them simultaneously. The output unit 44 outputs the input frequency f R1 ,…,f Rm After demodulating a plurality of the electrical signals, multiple input multiple output (MIMO) signal processing may be performed.

[0129] FIG. 13 is a sequence diagram showing a process flow of the wireless communication system 1f in the sixth embodiment. The antenna 31 receives a radio signal transmitted from an external device (step S601). The antenna 31 converts the received radio signal into an electrical signal and outputs it to the beam forming circuit 32. The beam forming circuit 32 outputs the electrical signal to the optical modulation unit 33 connected to an input port corresponding to the output port to which the electrical signal is input. In Fig. 13, for example, it is assumed that the electrical signal is output from input port i of the beam forming circuit 32.

[0130] The optical modulation unit 33-i connected to the input port i of the beam forming circuit 32 uses the electrical signal output from the beam forming circuit 32 to intensity-modulate an optical signal of a certain wavelength (step S602). As a result, the optical modulation unit 33-i generates an optical modulated signal. The optical modulation unit 33-i outputs the generated optical modulated signal to the optical multiplexer 34. The optical multiplexer 34 multiplexes the optical modulated signals output from each optical modulation unit 33 and performs wavelength division multiplexing (step S603). As a result, the optical multiplexer 34 generates a wavelength multiplexed signal. The optical multiplexer 34 sends the generated wavelength multiplexed signal to the exchange device 10f via the optical transmission path 30 (step S604).

[0131] The wavelength multiplexed signal sent to the optical transmission line 30 is input to the exchange device 10f. The wavelength dispersion compensator 41 of the exchange device 10f performs wavelength dispersion compensation on the input wavelength multiplexed signal (step S605). The wavelength dispersion compensator 41 outputs the wavelength multiplexed signal after wavelength dispersion compensation to the optical demultiplexer 42. The optical demultiplexer 42 demultiplexes the input wavelength multiplexed signal according to the wavelength (step S606). As a result, the wavelength multiplexed signal is output to the corresponding O / E 43. The optical demultiplexer 42 is connected to the number of O / Es 43 corresponding to the number of wavelengths. The O / E 43 converts the optical modulated signal demultiplexed by the optical demultiplexer 42 into an electrical signal (step S607). The O / E 43 outputs the electrical signal to the output unit 44. The output unit 44 demodulates the input electrical signal (step S608).

[0132] According to the wireless communication system 1f configured as above, it is possible to obtain the same effects as those of the first embodiment in the uplink direction.

[0133] Seventh embodiment The seventh embodiment differs from the sixth embodiment in that a base station device multiplexes signals on subcarriers and transmits the signals to an exchange device. The seventh embodiment will be described focusing on the differences from the sixth embodiment.

[0134] 14 is a diagram showing a configuration example of a wireless communication system 1g in the seventh embodiment. The wireless communication system 1g includes a terminating station 10g and a base station 20g. The terminating station 10g and the base station 20g are connected to each other via an optical transmission path 30.

[0135] The base station device 20g includes a plurality of antennas 31-1 to 31-N, a beam forming circuit 32, a plurality of frequency conversion sections 35-1 to 35-N, a multiplexer 36, and an optical modulation section 33.

[0136] The frequency conversion units 35-1 to 35-N convert the frequency of the input electrical signal. As a result, the electrical signal input to the frequency conversion units 35-1 to 35-N has a frequency f Ri is converted to

[0137] The multiplexer 36 multiplexes the electrical signals output from the frequency conversion units 35-1 to 35-N.

[0138] The optical modulation unit 33 performs intensity modulation and subcarrier multiplexing of an optical signal of a certain wavelength using the electrical signal multiplexed by the multiplexer 36. In this way, the optical modulation unit 33 generates a multiplexed signal.

[0139] The exchange device 10g includes a chromatic dispersion compensator 41, an O / E 43, a demultiplexer 45, and an output unit .

[0140] The splitter 45 splits the electrical signal output by the O / E 43 according to the frequency. For example, the splitter 45 splits the electrical signal into two signals at a frequency f R1 ,…,f Rm The electrical signal is split into two parts.

[0141] FIG. 15 is a sequence diagram showing a process flow of the wireless communication system 1g in the seventh embodiment. The antenna 31 receives a radio signal transmitted from an external device (step S701). The antenna 31 converts the received radio signal into an electrical signal and outputs it to the beam forming circuit 32. The beam forming circuit 32 outputs the electrical signal to the frequency conversion unit 35 connected to an input port corresponding to the output port to which the electrical signal is input. In FIG. 15, for example, it is assumed that the electrical signal is output from input port i of the beam forming circuit 32.

[0142] The frequency converter 35 connected to the input port i of the beam forming circuit 32 converts the frequency of the electrical signal output from the beam forming circuit 32 (step S702). As a result, the frequency of the electrical signal is converted to a frequency f Ri The frequency converter 35 converts the frequency f Ri The multiplexer 36 multiplexes the electrical signals output from the frequency conversion units 35 (step S703). The multiplexer 36 multiplexes the electrical signals output from the frequency conversion units 35 (step S703). The electrical signal multiplexed by the multiplexer 36 is output to the optical modulation unit 33.

[0143] The optical modulation unit 33 uses the electrical signal multiplexed by the multiplexer 36 to intensity-modulate and subcarrier-multiplex an optical signal of a certain wavelength (step S704). As a result, the optical modulation unit 33 generates a multiplexed signal. The optical modulation unit 33 transmits the generated multiplexed signal to the exchange device 10g via the optical transmission path 30 (step S705).

[0144] The multiplexed signal sent to the optical transmission line 30 is input to the exchange device 10g. The chromatic dispersion compensator 41 of the exchange device 10g performs chromatic dispersion compensation on the input wavelength multiplexed signal (step S706). The chromatic dispersion compensator 41 outputs the wavelength multiplexed signal after chromatic dispersion compensation to the O / E 43. The O / E 43 converts the input multiplexed signal into an electrical signal (step S707). By this process, the multiplexed signal is converted into an electrical signal having a frequency f Ri The O / E43 converts the signal into an electrical signal of frequency f Ri The electrical signal of frequency f Ri The electrical signal is split according to frequency (step S708). Ri The electrical signal of the input frequency f Ri The electrical signal is demodulated (step S709).

[0145] According to the wireless communication system 1g configured as above, it is possible to obtain the same effects as those of the second embodiment in the uplink direction.

[0146] Eighth embodiment The eighth embodiment differs from the sixth embodiment in that a base station device performs subcarrier multiplexing and wavelength division multiplexing to transmit a signal to an exchange device. The eighth embodiment will be described focusing on the differences from the sixth embodiment.

[0147] 16 is a diagram showing a configuration example of a wireless communication system 1h in the eighth embodiment. The wireless communication system 1h includes a station device 10h and a base station device 20h. The station device 10h and the base station device 20h are connected via an optical transmission path 30.

[0148] The base station device 20h includes a plurality of antennas 31-1 to 31-N, a beam forming circuit 32, a plurality of frequency conversion units 35, a plurality of multiplexers 36, a plurality of optical modulation units 33, and an optical multiplexer 34. Although not shown in FIG. 16 for the sake of simplicity, the multiplexer 36 and the optical modulation unit 33 are connected to an optical wavelength λ R The frequency converter 35 must be provided for the optical wavelength λ Rj The number of frequencies used by m j It is necessary to be prepared for this.

[0149] The optical multiplexer 34 multiplexes and wavelength division multiplexes the signals that have been subcarrier multiplexed by the optical modulation units 33. In this way, the optical multiplexer 34 generates a wavelength multiplexed signal.

[0150] The exchange device 10h includes a chromatic dispersion compensator 41, an optical demultiplexer 42, a plurality of O / Es 43, a plurality of demultiplexers 45, and an output unit 44. Although not shown in FIG. 16 for the sake of simplicity, the O / Es 43 and the demultiplexers 45 are chromatic dispersion compensators 41, 42, 43, and 45. R It is necessary to provide n, the number of which is equal to the number of

[0151] FIG. 17 is a sequence diagram showing a process flow of a wireless communication system 1h in the eighth embodiment. The antenna 31 receives a radio signal transmitted from an external device (step S801). The antenna 31 converts the received radio signal into an electrical signal and outputs it to the beam forming circuit 32. The beam forming circuit 32 outputs the electrical signal to the frequency conversion unit 35 connected to an input port corresponding to the output port to which the electrical signal is input.

[0152] The frequency converters 35 convert the electrical signals output from the input ports into optical signals having a wavelength of λ Rj The frequency f j Ri (step S802). The frequency converter 35 converts the frequency f j RiThe multiplexer 36 multiplexes the electrical signals output from the frequency conversion units 35 (step S803). The multiplexer 36 multiplexes the electrical signals output from the frequency conversion units 35 (step S803). The electrical signal multiplexed by the multiplexer 36 is output to the optical modulation unit 33.

[0153] The optical modulation unit 33 uses the electrical signal multiplexed by the multiplexer 36 to intensity-modulate an optical signal of a certain wavelength and perform subcarrier multiplexing (step S804). As a result, the optical modulation unit 33 generates a multiplexed signal. The optical modulation unit 33 outputs the generated multiplexed signal to the optical multiplexer 34. The optical multiplexer 34 multiplexes the multiplexed signals generated by the optical modulation units 33 and performs wavelength division multiplexing (step S805). As a result, the optical multiplexer 34 generates a wavelength multiplexed signal. The optical multiplexer 34 sends the generated wavelength multiplexed signal to the exchange device 10h via the optical transmission path 30 (step S806).

[0154] The wavelength multiplexed signal transmitted to the optical transmission line 30 is input to the exchange device 10h. The wavelength dispersion compensator 41 of the exchange device 10h performs wavelength dispersion compensation on the input wavelength multiplexed signal (step S807). The wavelength dispersion compensator 41 outputs the wavelength multiplexed signal after wavelength dispersion compensation to the optical demultiplexer 42. The optical demultiplexer 42 demultiplexes the input wavelength multiplexed signal according to the wavelength (step S808). As a result, the wavelength multiplexed signal is divided into optical wavelengths λ Rj The optical demultiplexer 42 is connected to the O / E 43 in a number corresponding to the number of wavelengths. Rj The optical modulation signal of the wavelength λ is converted into an electrical signal (step S809). Rj The optical modulated signal has a frequency of f j Ri The O / E43 converts the signal into an electrical signal of frequency f j Ri The electrical signal is output to the splitter 45.

[0155] The frequency f output to the splitter 45 j Ri The electrical signal is split according to frequency (step S810).j Ri The electrical signal of the input frequency f j Ri For example, the output unit 44 demodulates the electrical signal of the optical wavelength λ Rj and frequency f j Ri Σ n j=1 m j One of the combinations can be selected for demodulation. This is called Σ n j=1 m j This is equivalent to selecting one beam out of the received beams. The output unit 44 can also form multiple beams by selecting and simultaneously using multiple frequencies and multiple optical wavelengths. The output unit 44 outputs the input frequency f j R1 ,…,f j Rm The multiple electrical signals may be demodulated and then subjected to MIMO signal processing.

[0156] According to the wireless communication system 1h configured as above, it is possible to obtain the same effects as those of the third embodiment in the uplink direction.

[0157] Ninth embodiment The ninth embodiment differs from the sixth embodiment in that a base station device performs subcarrier multiplexing and polarization division multiplexing to transmit a signal to an exchange device. The ninth embodiment will be described focusing on the differences from the sixth embodiment.

[0158] 18 is a diagram showing a configuration example of a wireless communication system 1i in the ninth embodiment. The wireless communication system 1i includes an exchange station 10i and a base station 20i. The exchange station 10i and the base station 20i are connected to each other via an optical transmission path 30.

[0159] The base station device 20i includes a plurality of antennas 31-1 to 31-N, a beam forming circuit 32, a plurality of frequency conversion units 35, a plurality of multiplexers 36, a plurality of optical modulation units 33, and a polarization multiplexing unit 37. Although not shown in FIG. 18 for the sake of simplicity, the optical modulation units 33 and multiplexers 36 must be provided in the same number as the number of optical polarizations (e.g., 2), and the frequency conversion unit 35 must be provided in the same number as the number m of frequencies used by the optical polarization X. X and the number of frequencies used by the optical polarization Y, m Y The total number of (m X +m Y It is necessary to provide only one such device.

[0160] The polarization multiplexer 37 multiplexes and polarization division multiplexes the signals that have been subcarrier multiplexed by the multiple optical modulators 33. In this way, the polarization multiplexer 37 generates a polarization multiplexed signal.

[0161] The exchange device 10i includes a chromatic dispersion / polarization mode dispersion compensator 46, a polarization splitter 47, a plurality of O / Es 43-X and 43-Y, a plurality of demultiplexers 45, and an output unit 44. Although not shown in Fig. 18 for the sake of simplicity, the number of O / Es 43 and demultiplexers 45 needs to be the same as the number of optical polarizations (for example, 2).

[0162] The chromatic dispersion / polarization mode dispersion compensator 46 compensates for chromatic dispersion and polarization mode dispersion of the modulated optical signal of the optical polarization k.

[0163] The polarization splitter 47 splits the optical polarization k component of the polarization multiplexed signal for which chromatic dispersion and polarization mode dispersion have been compensated for by the chromatic dispersion / polarization mode dispersion compensator 46 .

[0164] FIG. 19 is a sequence diagram showing a process flow of the wireless communication system 1i in the ninth embodiment. The antenna 31 receives a radio signal transmitted from an external device (step S901). The antenna 31 converts the received radio signal into an electrical signal and outputs it to the beam forming circuit 32. The beam forming circuit 32 outputs the electrical signal to the frequency conversion unit 35 connected to an input port corresponding to the output port to which the electrical signal is input.

[0165] The frequency converters 35 convert the electrical signals output from the input ports into signals of a frequency f k Ri (step S902). The frequency conversion unit 35 converts f k Ri The multiplexer 36 multiplexes the electrical signals output from the frequency conversion units 35 (step S903). The multiplexer 36 multiplexes the electrical signals output from the frequency conversion units 35 (step S903). The electrical signal multiplexed by the multiplexer 36 is output to the optical modulation unit 33.

[0166] The optical modulation unit 33 uses the electrical signal multiplexed by the multiplexer 36 to intensity-modulate and subcarrier-multiplex the optical signal of the optical polarization k (step S904). As a result, the optical modulation unit 33 generates a multiplexed signal. The optical modulation unit 33 outputs the generated multiplexed signal to the polarization multiplexing unit 37. The polarization multiplexing unit 37 multiplexes the multiplexed signals generated by the optical modulation units 33 and performs polarization division multiplexing (step S905). As a result, the polarization multiplexing unit 37 generates a polarization multiplexed signal. The polarization multiplexing unit 37 sends the generated polarization multiplexed signal to the exchange device 10i via the optical transmission path 30 (step S906).

[0167] The polarization multiplexed signal sent to the optical transmission line 30 is input to the exchange device 10i. The chromatic dispersion / polarization mode dispersion compensator 46 performs chromatic dispersion and polarization mode dispersion compensation on the input polarization multiplexed signal (step S907). The chromatic dispersion / polarization mode dispersion compensator 46 outputs the polarization multiplexed signal after dispersion compensation processing to the polarization separator 47. The polarization separator 47 separates the optical polarization k of the input polarization multiplexed signal (step S908). As a result, the polarization multiplexed signal becomes an optical modulated signal of optical polarization k, which is output to the corresponding O / E 43. The O / E 43 converts the optical modulated signal of optical polarization k separated by the polarization separator 47 into an electrical signal (step S909). As a result of this processing, the optical modulated signal of optical polarization k is converted into an electrical signal of frequency f k Ri The O / E43 converts the signal into an electrical signal of frequency f k Ri The electrical signal is output to the splitter 45.

[0168] The frequency f output to the splitter 45 k Ri The electrical signal is split according to frequency (step S910). k Ri The electrical signal of the input frequency f k Ri For example, the output unit 44 demodulates the electrical signal of the optical polarization k and the frequency f k Ri (m X +m Y ) combinations, one of which may be selected for demodulation. X +m Y ) of received beams. The output unit 44 can also form multiple beams by selecting and simultaneously using multiple frequencies and multiple optical polarizations. The output unit 44 outputs the input frequency f k R1 ,…,f k Rm The multiple electrical signals may be demodulated and then subjected to MIMO signal processing.

[0169] According to the wireless communication system 1i configured as above, it is possible to obtain the same effects as those of the fourth embodiment in the uplink direction.

[0170] (Tenth embodiment) The tenth embodiment differs from the fifth embodiment in that a base station device performs wavelength division multiplexing and polarization division multiplexing to transmit a signal to an exchange device. The tenth embodiment will be described focusing on the differences from the fifth embodiment.

[0171] 20 is a diagram showing a configuration example of a wireless communication system 1j according to the tenth embodiment. The wireless communication system 1j includes an exchange device 10j and a base station device 20j. The exchange device 10j and the base station device 20j are connected to each other via an optical transmission path 30.

[0172] The base station device 20j includes a plurality of antennas 31-1 to 31-N, a beam forming circuit 32, a plurality of optical modulation units 33, a plurality of polarization multiplexing units 37, and an optical multiplexer 34. Although not shown in FIG. 20 for the sake of simplicity, the polarization multiplexing unit 37 is a unit for receiving an optical signal having an optical wavelength λ R The optical modulation unit 33 must be provided with a light wavelength λ Rj must be provided for each polarization to be used (e.g., 2).

[0173] The polarization multiplexer 37 multiplexes and polarization division multiplexes the signals that have been subcarrier multiplexed by the multiple optical modulators 33. In this way, the polarization multiplexer 37 generates a polarization multiplexed signal.

[0174] The optical multiplexer 34 multiplexes and wavelength division multiplexes the signals that have been polarization division multiplexed by the polarization multiplexer 37. In this way, the optical multiplexer 34 generates a wavelength multiplexed signal.

[0175] The exchange device 10j includes a chromatic dispersion / polarization mode dispersion compensator 46, an optical demultiplexer 42, a plurality of polarization splitters 47, a plurality of O / Es 43, and an output unit 44. Although not shown in FIG. 16 for the sake of simplicity, the polarization splitter 47 is an optical wavelength λ RThe O / E43 must be equipped with the same number of optical wavelengths as the number of optical fibers, n. Rj must be provided for each of the optical polarizations to be used (for example, 2).

[0176] FIG. 21 is a sequence diagram showing a process flow of a wireless communication system 1j in the tenth embodiment. The antenna 31 receives a radio signal transmitted from an external device (step S1001). The antenna 31 converts the received radio signal into an electrical signal and outputs it to the beam forming circuit 32. The beam forming circuit 32 outputs the electrical signal to the optical modulation unit 33 connected to an input port corresponding to the output port to which the electrical signal is input.

[0177] The optical modulation units 33 each convert the electrical signal output from the input port into an optical signal having an optical wavelength of λ Rj The optical modulator 33 outputs the modulated optical signal of the optical polarization k to the polarization multiplexer 37 (step S1002).

[0178] The polarization multiplexer 37 multiplexes the optically modulated signals generated by the optical modulators 33 and performs polarization division multiplexing (step S1003). As a result, the polarization multiplexer 37 generates a polarization multiplexed signal. The polarization multiplexer 37 outputs the generated polarization multiplexed signal to the optical multiplexer 34. The optical multiplexer 34 multiplexes the polarization multiplexed signals output from the polarization multiplexers 37 and performs wavelength division multiplexing (step S1004). As a result, the optical multiplexer 34 generates a wavelength multiplexed signal. The optical multiplexer 34 transmits the generated wavelength multiplexed signal to the exchange device 10g via the optical transmission path 30 (step S1005).

[0179] The wavelength multiplexed signal transmitted to the optical transmission line 30 is input to the exchange device 10h. The chromatic dispersion / polarization mode dispersion compensator 46 of the exchange device 10h performs chromatic dispersion and polarization mode dispersion compensation on the input wavelength multiplexed signal (step S1006). The chromatic dispersion / polarization mode dispersion compensator 46 outputs the wavelength multiplexed signal after dispersion compensation processing to the optical demultiplexer 42. The optical demultiplexer 42 demultiplexes the input wavelength multiplexed signal according to the wavelength (step S1007). As a result, the wavelength multiplexed signal is divided into optical wavelengths λRj The optical modulation signal is output to the corresponding polarization splitter 47. The polarization splitter 47 splits the input optical wavelength λ Rj The optical polarization k of the optical modulated signal is separated (step S1008). Rj The optical modulated signal of the optical polarization k becomes an optical modulated signal of the optical polarization k, and is output to the corresponding O / E 43. The O / E 43 converts the optical modulated signal of the optical polarization k separated by the polarization separation unit 47 into an electric signal (step S1009). Through this process, the optical modulated signal of the optical polarization k is converted into an electric signal. The O / E 43 outputs the electric signal to the output unit 44.

[0180] The output unit 44 demodulates the input electrical signal (step S1010). For example, the output unit 44 demodulates the optical wavelength λ Rj The output unit 44 may select one of 2n combinations of k and k optical polarizations and demodulate it. This is equivalent to selecting one beam out of 2n reception beams. Note that the output unit 44 can also form multiple beams by selecting and simultaneously using multiple optical wavelengths and multiple optical polarizations. The output unit 44 may perform MIMO signal processing after demodulating multiple input electrical signals.

[0181] According to the wireless communication system 1j configured as above, it is possible to obtain the same effects as those of the fifth embodiment in the uplink direction.

[0182] (Modification of the tenth embodiment) The accommodating station device 10j and the base station device 20j shown in Fig. 20 may be configured as shown in Fig. 22. Fig. 20 is a diagram showing a configuration example of a wireless communication system 1k in a modified example of the tenth embodiment. The wireless communication system 1k includes the accommodating station device 10k and the base station device 20k. The accommodating station device 10k and the base station device 20k are connected via an optical transmission path 30.

[0183] The base station device 20k includes a plurality of antennas 31-1 to 31-N, a beam forming circuit 32, a plurality of optical modulation units 33, a plurality of optical multiplexers 34, and a polarization multiplexing unit 37. Although not shown in FIG. 22 for the sake of simplicity, the number of optical multiplexers 34 must be equal to the number of polarized waves (for example, 2), and the number of optical modulation units 33 must be equal to the number m of frequencies used by the optical polarization X. X and the number of frequencies used by the optical polarization Y, m Y The total number of (m X +m Y It is necessary to have only one such device.

[0184] The exchange device 10k includes a polarization splitter 47, a plurality of optical demultiplexers 42, a plurality of O / Es 43, and an output unit 44. Although not shown in FIG. 22 for the sake of simplicity, the optical demultiplexer 42 is a demultiplexer for an optical wavelength λ R The O / E43 must be equipped with the same number of optical wavelengths as the number of optical fibers, n. Rj The number of compensators must be the same as the number of optical polarizations (e.g., 2) used by the corresponding station device 10. Thus, compared to the corresponding station device 10j, the corresponding station device 10k does not include a chromatic dispersion / polarization mode dispersion compensator 46. The chromatic dispersion / polarization mode dispersion compensator 46 is provided on the optical transmission path 30 between the corresponding station device 10k and the base station device 20k.

[0185] 22, the base station device 20j performs wavelength division multiplexing after polarization division multiplexing, whereas the base station device 20k performs polarization division multiplexing after wavelength division multiplexing. In the exchange device 10k, the optical polarization k component of the polarization multiplexed signal received via the optical transmission line 30 is separated by the polarization separator 47, and then separated according to wavelength by the optical demultiplexer 42.

[0186] (Modifications of the first to tenth embodiments) The configurations in the first to fifth embodiments may be combined with the configurations in the sixth to tenth embodiments. For example, the first embodiment may be combined with the sixth embodiment. In this case, the corresponding station device 10 and the corresponding station device 10f are combined as the corresponding station device, and the base station device 20 and the base station device 20f are combined as the base station device. For example, the second embodiment may be combined with the seventh embodiment. For example, the third embodiment may be combined with the eighth embodiment. For example, the fourth embodiment may be combined with the ninth embodiment. For example, the fifth embodiment may be combined with the tenth embodiment.

[0187] In the first to tenth embodiments, the configurations are shown in which only the wavelength is controlled, only the frequency is controlled, the frequency and optical wavelength are controlled, the frequency and optical polarization are controlled, and the optical polarization and optical wavelength are controlled. In the first to tenth embodiments, the configuration may be configured to control all of the optical polarization, optical wavelength, and frequency. In the case of such a configuration, for example, in the case of downstream transmission, the configuration shown in the first embodiment (wavelength control) and the configuration shown in the fourth embodiment (frequency and optical polarization control) may be combined to control all of the optical polarization, optical wavelength, and frequency. In the case of upstream transmission, for example, the configuration shown in the sixth embodiment (wavelength control) and the configuration shown in the ninth embodiment (frequency and optical polarization control) may be combined to control all of the optical polarization, optical wavelength, and frequency.

[0188] Some of the functional units of the exchange devices 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h, 10i, 10j, and 10k and the base station devices 20, 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 10j, and 10k in the above-mentioned embodiments may be realized by a computer. In this case, a program for realizing this function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to realize the function. Note that the "computer system" referred to here includes hardware such as an OS and peripheral devices.

[0189] In addition, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include those that dynamically hold a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, and those that hold a program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or client in such a case. Furthermore, the above program may be one that realizes part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already recorded in the computer system, or may be one that is realized using a programmable logic device such as an FPGA.

[0190] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Industrial Applicability]

[0191] The present invention is applicable to a wireless communication system that performs analog RoF transmission. [Explanation of symbols]

[0192] 10, 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h, 10i, 10j, 10k...accommodating station device, 11, 11a, 11b, 11c, 11d...control unit, 12, 12a, 12b, 12c, 12d...optical modulation unit, 13...chromatic dispersion compensation unit, 14...frequency conversion unit, 15...chromatic dispersion / polarization mode dispersion compensation unit, 20, 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 20k...base station device, 21...optical splitter, 22...O / E, 23...beam forming circuit, 24-1 to 254-N, 31-1 to 31-N...antenna, 25...splitter, 26-1 to 26-N... frequency conversion section, 27... polarization splitting section, 32... beam forming circuit, 33... optical modulation section, 34... optical multiplexer, 35... frequency conversion section, 36... multiplexer, 37... polarization multiplexing section, 41... chromatic dispersion compensation section, 42... optical splitter, 43... O / E, 44... output section, 45... splitter, 46... chromatic dispersion / polarization mode dispersion compensation section, 47... polarization splitter

Claims

1. A wireless communication method in a wireless communication system including a station device and a base station device that performs beam forming under control of the station device, the exchange device controls any combination of optical wavelength, frequency, or optical polarization, or a plurality of frequencies or a plurality of optical wavelengths, to intensity-modulate an optical signal based on a transmission signal to be transmitted, and transmits the generated optical modulated signal to the base station device via an optical transmission path, thereby performing beamforming control of the base station device; The optical modulated signal is transmitted after dispersion compensation is performed in an electrical domain or an optical domain in the exchange device, or the optical modulated signal is subjected to the dispersion compensation on the optical transmission line; the base station device inputs an electrical signal based on the optical modulated signal that has been subjected to the dispersion compensation to a beam forming circuit having a plurality of input ports, thereby forming a beam in a direction corresponding to the input port to which the electrical signal is input; the exchange device converts the frequency of the transmission signal by controlling a combination of the optical wavelength and the frequency, and transmits the generated optical modulated signal by intensity-modulating the optical signal of the controlled optical wavelength based on the transmission signal having the converted frequency to the base station device, thereby performing beamforming control of the base station device; A wireless communication method in which the base station device demultiplexes the optical modulated signal that has been subjected to chromatic dispersion compensation according to wavelength, converts the optical modulated signals demultiplexed for each wavelength into electrical signals, and demultiplexes the electrical signals according to frequency, thereby inputting the electrical signals to the beam forming circuit to form a beam.

2. A wireless communication method in a wireless communication system including a station device and a base station device that performs beam forming under control of the station device, the exchange device controls any combination of optical wavelength, frequency, or optical polarization, or a plurality of frequencies or a plurality of optical wavelengths, to intensity-modulate an optical signal based on a transmission signal to be transmitted, and transmits the generated optical modulated signal to the base station device via an optical transmission path, thereby performing beamforming control of the base station device; The optical modulated signal is transmitted after dispersion compensation is performed in an electrical domain or an optical domain in the exchange device, or the optical modulated signal is subjected to the dispersion compensation on the optical transmission line; the base station device inputs an electrical signal based on the optical modulated signal that has been subjected to the dispersion compensation to a beam forming circuit having a plurality of input ports, thereby forming a beam in a direction corresponding to the input port to which the electrical signal is input; the exchange device converts the frequency of the transmission signal by controlling a combination of the optical polarization and the frequency, and transmits the generated optical modulated signal to the base station device by intensity-modulating the optical signal of the controlled optical polarization based on the transmission signal having the converted frequency, thereby performing beamforming control of the base station device; A wireless communication method in which the base station device separates optical polarization components of the optically modulated signal that has been subjected to chromatic dispersion compensation and polarization mode dispersion, converts the optically modulated signals separated for each optical polarization component into electrical signals, and inputs the electrical signals to the beam forming circuit to form a beam by branching the electrical signals according to frequency.

3. A wireless communication method in a wireless communication system including a station device and a base station device that performs beam forming under control of the station device, the exchange device controls any combination of optical wavelength, frequency, or optical polarization, or a plurality of frequencies or a plurality of optical wavelengths, to intensity-modulate an optical signal based on a transmission signal to be transmitted, and transmits the generated optical modulated signal to the base station device via an optical transmission path, thereby performing beamforming control of the base station device; The optical modulated signal is transmitted after dispersion compensation is performed in an electrical domain or an optical domain in the exchange device, or the optical modulated signal is subjected to the dispersion compensation on the optical transmission line; the base station device inputs an electrical signal based on the optical modulated signal that has been subjected to the dispersion compensation to a beam forming circuit having a plurality of input ports, thereby forming a beam in a direction corresponding to the input port to which the electrical signal is input; the exchange device controls a combination of the optical polarization and the optical wavelength, and uses the transmission signal to intensity-modulate an optical signal of the optical polarization having the controlled optical wavelength, and transmits the generated optical modulated signal to the base station device, thereby performing beamforming control of the base station device; A wireless communication method, in which the base station device demultiplexes the optically modulated signal that has been subjected to chromatic dispersion compensation and polarization mode dispersion according to wavelength, and then separates the optical polarization components of the optically modulated signal that have been demultiplexed for each wavelength, or demultiplexes the optically modulated signal that has been separated for each optical polarization component after separating the optical polarization components of the optically modulated signal according to wavelength, converts the optically modulated signal into an electrical signal, and then inputs it to the beam forming circuit to form a beam.

4. A wireless communication method in a wireless communication system including a station device and a base station device that performs beam forming under control of the station device, the exchange device controls any combination of optical wavelength, frequency, or optical polarization, or a plurality of frequencies or a plurality of optical wavelengths, to intensity-modulate an optical signal based on a transmission signal to be transmitted, and transmits the generated optical modulated signal to the base station device via an optical transmission path, thereby performing beamforming control of the base station device; The optical modulated signal is transmitted after dispersion compensation is performed in an electrical domain or an optical domain in the exchange device, or the optical modulated signal is subjected to the dispersion compensation on the optical transmission line; the base station device inputs an electrical signal based on the optical modulated signal that has been subjected to the dispersion compensation to a beam forming circuit having a plurality of input ports, thereby forming a beam in a direction corresponding to the input port to which the electrical signal is input; the exchange device converts the frequency of the transmission signal by controlling a combination of the optical polarization, the frequency, and the optical wavelength, and transmits the generated optical modulated signal to the base station device by intensity-modulating the optical signal of the optical polarization having the controlled optical wavelength based on the transmission signal having the converted frequency, thereby performing beamforming control of the base station device; A wireless communication method, in which the base station device inputs the electrical signal obtained based on the optical modulated signal that has been subjected to chromatic dispersion compensation and polarization mode dispersion to the beam forming circuit, thereby performing beam forming.

5. A wireless communication method in a wireless communication system including a station device and a base station device that performs beam forming under control of the station device, the exchange device controls any combination of optical wavelength, frequency, or optical polarization, or a plurality of frequencies or a plurality of optical wavelengths, to intensity-modulate an optical signal based on a transmission signal to be transmitted, and transmits the generated optical modulated signal to the base station device via an optical transmission path, thereby performing beamforming control of the base station device; The optical modulated signal is transmitted after dispersion compensation is performed in an electrical domain or an optical domain in the exchange device, or the optical modulated signal is subjected to the dispersion compensation on the optical transmission line; the base station device inputs an electrical signal based on the optical modulated signal that has been subjected to the dispersion compensation to a beam forming circuit having a plurality of input ports, thereby forming a beam in a direction corresponding to the input port to which the electrical signal is input; the base station device converts a radio signal transmitted from an external device into an electrical signal, inputs the electrical signal to an output port of the beam forming circuit, outputs the electrical signal from the input port of the beam forming circuit corresponding to the output port, and transmits an optical signal obtained by intensity-modulating an optical signal using the electrical signal to the exchange device; The optical communication device performs dispersion compensation in an electrical domain or an optical domain, or performs dispersion compensation on the optical modulated signal on the optical transmission line; The station device demodulates the optical signal transmitted from the base station device.

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