CN119856442A - Analog RoF system, master station device, slave station device, and optical communication method - Google Patents

Abstract

The present invention relates to an analog RoF system, comprising: a master station device; and a slave station device, which transmits and receives wireless signals via an antenna, the master station device generates control information used in controlling the transmission and reception of the wireless signal, and transmits an optical signal including a first digital signal and an analog master signal to the slave station device via an optical fiber, the first digital signal including the generated control information, the slave station device obtains the control information from the first digital signal included in the optical signal received from the master station device via the optical fiber, and performs switching processing of the transmission and reception of the wireless signal via the antenna based on the obtained control information.

Description

Analog RoF system, master station device, slave station device, and optical communication method

Technical Field

The present invention relates to an analog RoF (Radio over Fiber) system, a master station apparatus, a slave station apparatus, and an optical communication method.

The present application claims priority from japanese patent application publication No. 2022-166626 filed 10/18 of 2022, and the disclosure of which is incorporated herein in its entirety.

Background

Patent document 1 (japanese patent application laid-open publication No. 2016-158062) discloses a communication device as follows. Specifically, the communication device includes a packet reception unit that receives a packet in which a divided continuous signal is stored, a signal holding unit that receives and holds a received continuous signal that is a continuous signal stored in a packet received by the packet reception unit, a transmission timing control unit that instructs the signal holding unit to output the received continuous signal when the packet reception unit receives a packet different from a packet subsequent to a packet received immediately before, at a timing determined based on a time stamp inserted in a header of the packet received immediately before, and instructs the signal holding unit to output the received continuous signal when the packet reception unit receives a packet subsequent to a packet received immediately before, at a timing determined in advance based on a size of the divided continuous signal, and a continuous signal transmission unit that transmits the continuous signal output from the signal holding unit to a continuous signal transmission network.

Further, patent document 2 (japanese patent application laid-open No. 2007-166278) discloses a wireless communication system as follows. Specifically, the radio communication system is composed of a master station device, a slave station device, a network connecting the master station device and the slave station device, and a radio terminal, wherein the master station device includes a radio modulation circuit for modulating data, a radio demodulation circuit for demodulating data, and a processing unit for packetizing a digital radio signal input from the radio modulation circuit and transmitting the digital radio signal to the network, and receiving a data packet from the network, converting the received data packet into a digital radio signal and transmitting the digital radio signal to the radio demodulation circuit, the slave station device includes a radio transmission circuit for transmitting a radio signal to the radio terminal, a radio reception circuit for receiving a radio signal from the radio terminal, and a processing unit for packetizing a digital radio signal input from the radio reception circuit and transmitting the digital radio signal to the network, and receiving a data packet from the network, extracting a digital radio signal from the received data packet and transmitting the digital radio signal to the radio transmission circuit, and synchronizing the time and clock times of the master station device and the slave station device, and adding a radio signal to the clock frequency of the master station device, and transmitting the digital radio signal to the clock frequency.

Prior art literature

Patent literature

Patent document 1, japanese patent laid-open publication 2016-158062;

Patent document 2, japanese patent application laid-open No. 2007-166278.

Disclosure of Invention

The analog RoF system includes a master station device that transmits and receives a radio signal via an antenna, and a slave station device that generates control information used for controlling transmission and reception of the radio signal, transmits an optical signal including a first digital signal including the generated control information and an analog master signal to the slave station device via an optical fiber, acquires the control information from the first digital signal included in the optical signal received from the master station device via the optical fiber, and performs switching processing between transmission and reception of the radio signal via the antenna based on the acquired control information.

The master station device includes a control information generation unit that generates control information used for controlling transmission and reception of a radio signal by a slave station device via an antenna, and a transmission unit that transmits an optical signal including a digital signal and an analog master signal to the slave station device via an optical fiber, wherein the digital signal includes the control information generated by the control information generation unit.

A slave station device includes a wireless transmitting/receiving unit that transmits/receives a wireless signal via an antenna, a receiving unit that receives an optical signal including a digital signal and an analog main signal from a master station device via an optical fiber, the digital signal including control information, an acquisition unit that acquires the control information from the digital signal included in the optical signal received by the receiving unit, and a control unit that performs switching processing between transmission operation and reception operation of the wireless transmitting/receiving unit via the antenna based on the control information acquired by the acquisition unit.

An optical communication method in an analog RoF system having a master station device and a slave station device that transmits/receives a radio signal via an antenna, the optical communication method including a step of generating control information used for controlling transmission/reception of the radio signal by the master station device, a step of transmitting an optical signal including a first digital signal and an analog master signal to the slave station device via an optical fiber, the first digital signal including the generated control information, and a step of acquiring the control information from the first digital signal included in the optical signal received from the master station device via the optical fiber by the slave station device, and performing a switching process between transmission operation and reception operation of the radio signal via the antenna based on the acquired control information.

The present invention can be realized not only as a master station device having such a characteristic processing section but also as an optical communication method in which the characteristic processing is a step, or as a program for causing a computer to execute the step. In addition, one embodiment of the present invention can be implemented as a semiconductor integrated circuit in which a part or all of the master station device is implemented.

Further, one embodiment of the present invention can be realized not only as a slave device having such a characteristic processing section but also as an optical communication method in which the characteristic processing is a step, or as a program for causing a computer to execute the step. In addition, one embodiment of the present invention can be implemented as a semiconductor integrated circuit in which a part or all of the slave station apparatus is implemented.

Drawings

Fig. 1 is a diagram showing a configuration of an analog RoF system according to a first embodiment of the present invention.

Fig. 2 is a diagram showing an example of a timing chart of a communication frame in the mobile radio communication system.

Fig. 3 is a diagram showing a configuration of a master station device according to a first embodiment of the present invention.

Fig. 4 is a diagram showing a configuration of a slave station apparatus according to a first embodiment of the present invention.

Fig. 5 is a diagram showing an example of a TDD signal transmitted from a base station apparatus according to the first embodiment of the present invention.

Fig. 6 is a diagram showing an example of a TDD signal generated by a TDD processing unit in a slave device according to the first embodiment of the present invention.

Fig. 7 is a diagram showing an example of a communication sequence of an analog RoF system according to the first embodiment of the present invention.

Fig. 8 is a diagram showing a configuration of an analog RoF system according to a second embodiment of the present invention.

Fig. 9 is a diagram showing a configuration of a master station device according to a second embodiment of the present invention.

Fig. 10 is a diagram showing an example of a correspondence table held in the information storage unit in the master station device according to the second embodiment of the present invention.

Fig. 11 is a diagram showing a configuration of a secondary station apparatus according to a second embodiment of the present invention.

Fig. 12 is a diagram showing a configuration of an analog RoF system according to a third embodiment of the present invention.

Fig. 13 is a diagram showing a configuration of a master station device according to a third embodiment of the present invention.

Fig. 14 is a diagram showing a configuration of a slave station apparatus according to a third embodiment of the present invention.

Fig. 15 is a diagram showing an example of a communication sequence of an analog RoF system according to the third embodiment of the present invention.

Detailed Description

Conventionally, a technique for improving communication performance of an optical communication system has been developed.

[ Problem to be solved by the invention ]

A technique is desired which exceeds the techniques described in patent documents 1 and 2 and which can realize TDD (Time Division Duplex:time division duplex) with a simple structure in an analog RoF system having a master station device and a slave station device.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an analog RoF system, a master station apparatus, a slave station apparatus, and an optical communication method, which can realize TDD with a simple configuration in an analog RoF system having a master station apparatus and a slave station apparatus.

[ Effect of the invention ]

According to the present invention, TDD can be realized with a simple structure in an analog RoF system having a master station apparatus and a slave station apparatus.

Description of embodiments of the invention

First, the contents of the embodiments of the present invention are listed and described.

(1) An analog RoF system according to an embodiment of the present invention includes a master station device that transmits and receives a radio signal via an antenna, and a slave station device that generates control information used for controlling transmission and reception of the radio signal, transmits an optical signal including a first digital signal including the generated control information and an analog master signal to the slave station device via an optical fiber, acquires the control information from the first digital signal included in the optical signal received from the master station device via the optical fiber, and performs switching processing between transmission and reception of the radio signal via the antenna based on the acquired control information.

In this way, the master station apparatus transmits the downstream optical signal including the first digital signal and the master signal to the slave station apparatus via the optical fiber, and the slave station apparatus acquires control information from the first digital signal included in the downstream optical signal and performs switching processing of transmission and reception of the wireless signal. Accordingly, in an analog RoF system having a master device and a slave device, TDD can be realized with a simple structure.

(2) In the above (1), the master station apparatus may be connected between a base station apparatus and the slave station apparatus, and the master station apparatus may receive a pattern signal indicating an uplink communication period and a downlink communication period in TDD from the base station apparatus, and generate the control information based on the received pattern signal.

With this configuration, the master station device can generate control information by a simple process, and the slave station device can perform a process of switching transmission and reception in synchronization with the uplink communication period and the downlink communication period set in the base station device. In addition, when the base station apparatus changes the downlink communication period and the uplink communication period, the control information reflecting the change content is transmitted from the master station apparatus to the slave station apparatus, and thus the switching process in the slave station apparatus can be changed, and the change of the downlink communication period and the uplink communication period can be flexibly handled.

(3) In the above (2), the master station device may generate a switching pattern of the transmission/reception operation of the radio signal based on the pattern signal, and generate the control information including the generated switching pattern and a start timing of the switching process using the switching pattern.

With this configuration, for example, the start timing of the transmission delay of the control information between the master station device and the slave station device can be set, and stable switching processing can be performed in the slave station device.

(4) In the above (2), the master station apparatus and the slave station apparatus may hold correspondence information indicating a correspondence between the type of the pattern signal and identification information of the pattern signal, and the master station apparatus may acquire the identification information corresponding to the pattern signal received from the base station apparatus with reference to the correspondence information, and generate the control information including the acquired identification information and a start timing of the handover process using the identification information.

With this configuration, the secondary station device can be notified of the uplink communication period and the downlink communication period set in the base station device with a simple configuration, as compared with a configuration in which control information including a switching mode of transmission/reception operation of a radio signal is transmitted from the primary station device to the secondary station device.

(5) In the above (3) or (4), the analog RoF system may have a plurality of the slave station apparatuses, and the master station apparatus may generate the control information including the different start timing for each of the slave station apparatuses.

With this configuration, for example, since the start timing can be set in consideration of different processing delays for each slave station apparatus, interference of wireless signals transmitted from the respective slave station apparatuses via the antennas can be suppressed.

(6) In any one of the above (3) to (5), the slave station apparatus may correct the start timing included in the control information, and start the switching process based on the control information at the corrected start timing.

With this configuration, the slave station apparatus can perform stable switching processing based on the start timing corrected to be more accurate based on the actual transmission delay or the like of the control information received by the slave station apparatus.

(7) In any one of the above (1) to (6), the slave device may receive pattern information indicating an uplink communication period and a downlink communication period in TDD from a device other than the master device outside the slave device, generate a second digital signal including the received pattern information, transmit an optical signal including the generated second digital signal and an analog master signal to the master device via the optical fiber, and the master device may acquire the pattern information from the second digital signal included in the optical signal received from the slave device via the optical fiber, and generate the control information reflecting the content of the acquired pattern information.

With such a configuration, when the downlink communication period and the uplink communication period in TDD employed in the mobile wireless communication system are changed according to, for example, the communication status of the mobile communication terminal, the change of the downlink communication period and the uplink communication period can be flexibly handled.

(8) The master station device according to an embodiment of the present invention includes a control information generation unit that generates control information used for controlling a slave station device to transmit and receive a radio signal via an antenna, and a transmission unit that transmits an optical signal including a digital signal and an analog master signal to the slave station device via an optical fiber, the digital signal including the control information generated by the control information generation unit.

In this way, the downstream optical signal including the digital signal including the control information and the main signal is transmitted to the slave station apparatus via the optical fiber, and thus, the slave station apparatus can perform the switching process of the transmission and reception without performing detailed arithmetic processing or the like for determining the switching timing of the transmission and reception of the wireless signal. Accordingly, in an analog RoF system having a master device and a slave device, TDD can be realized with a simple structure.

(9) The secondary station device according to an embodiment of the present invention includes a wireless transmitting/receiving unit that transmits/receives a wireless signal via an antenna, a receiving unit that receives an optical signal including a digital signal and an analog main signal from a primary station device via an optical fiber, the digital signal including control information, an acquiring unit that acquires the control information from the digital signal included in the optical signal received by the receiving unit, and a control unit that performs switching processing between transmission operation and reception operation of the wireless transmitting/receiving unit via the antenna based on the control information acquired by the acquiring unit.

In this way, by the configuration in which control information is acquired from the digital signal included in the optical signal to perform switching processing of transmission and reception of the wireless signal, the switching processing of transmission and reception can be performed without performing detailed arithmetic processing or the like for determining switching timing of transmission and reception of the wireless signal. Accordingly, in an analog RoF system having a master device and a slave device, TDD can be realized with a simple structure.

(10) The communication method according to an embodiment of the present invention is an optical communication method in an analog RoF system including a master station device and a slave station device that transmits/receives a radio signal via an antenna, and includes a step of generating control information used for controlling transmission/reception of the radio signal by the master station device, a step of transmitting an optical signal including a first digital signal and an analog master signal to the slave station device via an optical fiber, the first digital signal including the generated control information, and a step of acquiring the control information from the first digital signal included in the optical signal received from the master station device via the optical fiber by the slave station device, and performing switching processing between transmission/reception of the radio signal via the antenna based on the acquired control information.

In this way, the master station apparatus transmits the downstream optical signal including the first digital signal and the master signal to the slave station apparatus via the optical fiber, and the slave station apparatus acquires control information from the first digital signal included in the downstream optical signal and performs switching processing of transmission and reception of the wireless signal. Accordingly, in an analog RoF system having a master device and a slave device, TDD can be realized with a simple structure.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or corresponding portions in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated. At least some of the embodiments described below may be arbitrarily combined.

< First embodiment >

[ Structure and basic work ]

Fig. 1 is a diagram showing a configuration of an analog RoF system according to a first embodiment of the present invention. Referring to fig. 1, an analog RoF system 301 has a master station apparatus 101 and a plurality of slave station apparatuses 201. In fig. 1, one slave station apparatus 201 is representatively illustrated. The master station apparatus 101 and the slave station apparatus 201 are connected to each other via an optical fiber 191. The master station apparatus 101 is connected between the base station apparatus 111 and the slave station apparatus 201. The master station apparatus 101 and the plurality of slave station apparatuses 201 may be connected to each other via an optical fiber 191 and an optical coupler. The analog RoF system 301 may have one slave station apparatus 201.

The master station apparatus 101 and the slave station apparatus 201 transmit and receive optical signals including communication data generated in the base station apparatus 111 via the optical fiber 191. Hereinafter, the optical signal transmitted from the master station apparatus 101 to the slave station apparatus 201 is also referred to as a downstream optical signal, and the optical signal transmitted from the slave station apparatus 201 to the master station apparatus 101 is also referred to as an upstream optical signal.

The analog RoF system 301 is used for a mobile wireless communication system employing TDD. For example, the analog RoF system 301 is used for mobile forwarding (Mobile Fronthaul) and local 5G in a fifth-generation mobile communication system (hereinafter also referred to as 5G) employing TDD.

Fig. 2 is a diagram showing an example of a timing chart of a communication frame of the mobile radio communication system. Referring to fig. 2, in TDD, a communication frame F composed of 10 subframes sf#0 to sf#9 is repeated. Each subframe SF includes two slots S. For example, the period of one communication frame F is 10 ms, the period of one subframe SF is 1 ms, and the period of one slot S is 0.5 ms.

The time slot S is allocated any one of an uplink communication time slot US constituting an uplink communication period UP in TDD, a downlink communication time slot DS constituting a downlink communication period DP in TDD, and a special time slot SS as a switching period of the uplink communication period UP and the downlink communication period DP. The uplink communication period UP and the downlink communication period DP are alternately repeated.

In the example shown in fig. 2, the downlink communication slots DS are allocated to slots s#0, s#1 in the subframe sf#0 and slots s#2, s#3 in the subframe sf#1. The special slot SS is allocated to the first slot s#4 in the subframe sf#2. The uplink communication slot US is allocated to the second slot s#5 in the subframe sf#2, the slots s#6, s#7 in the subframe sf#3, and the first slot s#8 in the subframe sf#4. The special slot SS is allocated to the second slot s#9 in the subframe sf#4. The downlink communication slots DS are allocated to slots s#10, s#11 in the subframe sf#5 and slots s#12, s#13 in the subframe sf#6. The special slot SS is allocated to the first slot s#14 in the subframe sf#7. The uplink communication slot US is allocated to the second slot s#15 in the subframe sf#7, the slots s#16, s#17 in the subframe sf#8, and the first slot s#18 in the subframe sf#9. The special slot SS is allocated to the second slot s#19 in the subframe sf#9.

In the analog RoF system 301, the slave station apparatus 201 transmits communication data to the master station apparatus 101 in the uplink communication period UP, and the master station apparatus 101 transmits communication data to the slave station apparatus 201 in the downlink communication period DP.

More specifically, the master station apparatus 101 receives an analog signal modulated by OFDM (Orthogonal Frequency Division Multiplexing: orthogonal frequency division multiplexing) including communication data from the base station apparatus 111. The master station apparatus 101 generates an IF (INTERMEDIATE FREQUENCY: intermediate frequency) signal Fa by frequency-converting the received analog signal. The IF signal Fa is an example of a main signal. The master station apparatus 101 transmits a downlink optical signal including the generated IF signal Fa to the slave station apparatus 201 via the optical fiber 191 in the downlink communication period DP.

The slave station apparatus 201 transmits and receives an RF (Radio Frequency) signal via the switch apparatus 151 and the antenna 161. More specifically, the slave station apparatus 201 receives a downstream optical signal from the master station apparatus 101 via the optical fiber 191. Then, the slave station apparatus 201 acquires the IF signal Fa from the received downstream optical signal, and transmits an RF signal of millimeter wave band based on the acquired IF signal Fa via the switching apparatus 151 and the antenna 161.

The slave station apparatus 201 receives an RF signal of a millimeter wave band, which is OFDM-modulated and contains communication data, from a mobile communication terminal, not shown, via the antenna 161 and the switch 151, and frequency-converts the received RF signal to generate an IF signal Fb. The slave station apparatus 201 transmits an uplink optical signal including the generated IF signal Fb to the master station apparatus 101 via the optical fiber 191 in the uplink communication period UP.

The master device 101 receives an upstream optical signal from the slave device 201 via the optical fiber 191. The master station apparatus 101 acquires the IF signal Fb from the received uplink optical signal, and transmits a signal based on the acquired IF signal Fb to the base station apparatus 111.

The slave station apparatus 201 transmits a TDD signal Std2 for controlling the state of the switching apparatus 151 to the switching apparatus 151. The switching device 151 switches between a transmission state in which the antenna 161 is connected to a transmission circuit of the RF signal in the slave station device 201 and a reception state in which the antenna 161 is connected to a reception circuit of the RF signal in the slave station device 201, based on the TDD signal Std2 received from the slave station device 201.

Fig. 3 is a diagram showing a configuration of a master station device according to a first embodiment of the present invention. Referring to fig. 3, the master device 101 includes a synchronization processing unit 11, a TDD processing unit 12, a frame processing unit 13, a frequency conversion unit 14, a multiplexing unit 15, a separation unit 16, an optical modulation unit 17, an optical demodulation unit 18, and an optical coupler CP1. The TDD processing unit 12 is an example of a control information generating unit. The optical modulation unit 17 is an example of a transmission unit.

The synchronization processing unit 11 receives a reference clock from an external or internal oscillator of the master device 101, for example, and generates a local clock CL1 that divides or multiplies the received reference clock. The synchronization processing unit 11 counts at the timing of the generated local clock CL1, and holds the count value. Each unit in the master device 101 operates based on the local clock CL1.

The synchronization processing unit 11 receives a reference signal from the base station apparatus 111. For example, the synchronization processing unit 11 receives a clock signal, a GNSS (Global Navigation SATELLITE SYSTEM: global navigation satellite system) signal, or a master clock (GRANDMASTER CLOCK) signal as a reference signal from the base station apparatus 111. The synchronization processing unit 11 performs base station synchronization processing for synchronizing the count value of the local clock CL1 with the base station apparatus 111 based on the received reference signal. For example, when the wiring between the base station apparatus 111 and the master station apparatus 101 is short, the synchronization processing section 11 performs base station synchronization processing based on the reference signal, regardless of the transmission delay of the reference signal between the base station apparatus 111 and the master station apparatus 101.

The frame processing unit 13 generates an ethernet (registered trademark) frame addressed to the slave station apparatus 201, in which information to be transmitted to the slave station apparatus 201 is stored in the payload. The frame processing unit 13 outputs a digital signal Da including the generated ethernet frame to the multiplexing unit 15.

The frequency conversion unit 14 receives an OFDM-modulated analog signal including communication data from the base station apparatus 111. The frequency conversion unit 14 may be configured to receive an analog signal in the RF band or may be configured to receive an analog signal in the baseband. The frequency conversion unit 14 generates an IF signal Fa by up-converting or down-converting the received analog signal, and outputs the generated IF signal Fa to the multiplexing unit 15.

The multiplexing unit 15 frequency-multiplexes the digital signal Da received from the frame processing unit 13 and the IF signal Fa received from the frequency conversion unit 14. The multiplexing unit 15 generates an electrical signal obtained by frequency-multiplexing the digital signal Da and the IF signal Fa, and outputs the electrical signal to the optical modulation unit 17.

The optical modulation unit 17 receives the electrical signal from the multiplexing unit 15, and generates a downstream optical signal of wavelength λ1 obtained by modulating the received electrical signal. The optical modulation section 17 outputs the downstream optical signal to the optical fiber 191 via the optical coupler CP1 in the downstream communication period DP.

As described above, by generating the digital signal Da and the IF signal Fa in different units and transmitting the downstream optical signal including the generated digital signal Da and the generated IF signal Fa to the slave station apparatus 201, it is possible to suppress a decrease in the signal quality of the IF signal Fa and a propagation delay of the IF signal Fa.

The master station apparatus 101 may be configured to receive the IF signal Fa from the base station apparatus 111 and transmit a downlink optical signal including the received IF signal Fa to the slave station apparatus 201 via the optical fiber 191. More specifically, the master station device 101 may be configured without the frequency conversion unit 14. In this case, the multiplexing unit 15 receives the IF signal Fa from the base station apparatus 111, and frequency multiplexes the digital signal Da received from the frame processing unit 13 and the IF signal Fa received from the base station apparatus 111.

Fig. 4 is a diagram showing a configuration of a slave station apparatus according to a first embodiment of the present invention. Referring to fig. 4, the slave station apparatus 201 includes a synchronization processing unit 21, a TDD processing unit 22, a frame processing unit 23, an RF transmitting/receiving unit 24, a separating unit 25, a multiplexing unit 26, an optical demodulating unit 27, an optical modulating unit 28, and an optical coupler CP2. The RF transceiver 24 is an example of a wireless transceiver. The RF transceiver 24 includes a receiving circuit, not shown, that receives an RF signal and a transmitting circuit, not shown, that transmits an RF signal. The optical demodulation unit 27 is an example of a receiving unit. The frame processing unit 23 is an example of the acquisition unit. The TDD processing unit 22 is an example of a control unit.

The synchronization processing unit 21 receives a reference clock from an external or internal oscillator of the slave station apparatus 201, for example, and generates a local clock CL2 that divides or multiplies the received reference clock. The synchronization processing unit 21 counts at the timing of the generated local clock CL2, and holds the count value. Each unit in the slave station apparatus 201 operates based on the local clock CL2. The frequency of the local clock CL2 is set equal to the local clock CL1 of the master station apparatus 101.

The optical demodulation unit 27 receives the downstream optical signal from the master station device 101 via the optical fiber 191 and the optical coupler CP2, and generates an electrical signal based on the received downstream optical signal. More specifically, the optical demodulation unit 27 generates an electrical signal having a level corresponding to the intensity of the received downlink optical signal, and outputs the electrical signal to the separation unit 25.

The separation unit 25 receives the electric signal from the optical demodulation unit 27, separates the IF signal Fa and the digital signal Da included in the received electric signal, outputs the IF signal Fa to the RF transmission/reception unit 24, and outputs the digital signal Da to the frame processing unit 23. For example, the separating unit 25 is a duplexer composed of an HPF (HIGH PASS FILTER: high pass filter) and an LPF. The separation unit 25 outputs a frequency component equal to or higher than the frequency Fx of the electric signal received from the optical demodulation unit 27 as the IF signal Fa to the RF transmission/reception unit 24, and outputs a frequency component smaller than the frequency Fx as the digital signal Da to the frame processing unit 23. Here, the frequency Fx is smaller than the center frequency of the IF signal Fa.

For example, the RF transceiver 24 amplifies the IF signal Fa received from the splitter 25. The RF transceiver 24 generates an RF signal by up-converting the amplified IF signal Fa, and outputs the generated RF signal to the antenna 161 via the switching device 151.

The frame processing unit 23 receives the digital signal Da from the separating unit 25, and acquires an ethernet frame from the received digital signal Da. When the destination MAC address included in the acquired ethernet frame does not match the MAC address of the slave station apparatus 201, the frame processing unit 23 discards the ethernet frame. On the other hand, when the destination MAC address included in the acquired ethernet frame matches the MAC address of the slave station apparatus 201, the frame processing section 23 acquires information from the payload of the ethernet frame.

The frame processing unit 23 generates an ethernet frame addressed to the master station device 101, in which information to be transmitted to the master station device 101 is stored in a payload. The frame processing unit 23 outputs the digital signal Db including the generated ethernet frame to the multiplexing unit 26.

The RF transceiver 24 receives an analog signal of an OFDM-modulated RF band including communication data from a mobile communication terminal, not shown, via the antenna 161 and the switching device 151. The RF transceiver 24 generates an IF signal Fb by down-converting the received analog signal, and outputs the generated IF signal Fb to the multiplexer 26.

The multiplexing unit 26 frequency-multiplexes the digital signal Db received from the frame processing unit 23 and the IF signal Fb received from the RF transmitting/receiving unit 24. The multiplexing unit 26 generates an electrical signal obtained by frequency-multiplexing the digital signal Db and the IF signal Fb, and outputs the electrical signal to the optical modulation unit 28.

The optical modulator 28 transmits an upstream optical signal including the digital signal Db and the IF signal Fb to the master station device 101 via the optical fiber 191. More specifically, the optical modulation unit 28 receives the electrical signal from the multiplexing unit 26, and generates an upstream optical signal of wavelength λ2 obtained by modulating the received electrical signal. The optical modulation section 28 outputs the uplink optical signal to the optical fiber 191 via the optical coupler CP2 in the uplink communication period UP.

Referring again to fig. 3, the optical demodulation unit 18 in the master device 101 receives an uplink optical signal from the slave device 201 via the optical fiber 191 and the optical coupler CP1, and generates an electrical signal based on the received uplink optical signal. More specifically, the optical demodulation unit 18 generates an electrical signal having a level corresponding to the intensity of the received uplink optical signal, and outputs the electrical signal to the separation unit 16.

The separation unit 16 receives the electric signal from the optical demodulation unit 18, separates the IF signal Fb and the digital signal Db included in the received electric signal, outputs the IF signal Fb to the frequency conversion unit 14, and outputs the digital signal Db to the frame processing unit 13. For example, the separating section 16 is a duplexer constituted by an HPF and an LPF. The separation unit 16 outputs a frequency component equal to or higher than the frequency Fy in the electric signal received from the optical demodulation unit 18 as the IF signal Fb to the frequency conversion unit 14, and outputs a frequency component smaller than the frequency Fy as the digital signal Db to the frame processing unit 13. Here, the frequency Fy is smaller than the center frequency of the IF signal Fb.

For example, the frequency conversion unit 14 generates an RF signal by up-converting the IF signal Fb received from the separation unit 16, and transmits the generated RF signal to the base station apparatus 111. Or the frequency conversion unit 14 generates a baseband signal by down-converting the IF signal Fb received from the separation unit 16, and transmits the generated baseband signal to the base station apparatus 111. As described above, the master station device 101 may be configured without the frequency conversion unit 14. In this case, the separation unit 16 transmits the IF signal Fb to the base station apparatus 111.

The frame processing unit 13 receives the digital signal Db from the separating unit 16, acquires an ethernet frame from the received digital signal Db, and acquires information from the payload of the ethernet frame.

(Inter-station synchronous processing)

The synchronization processing unit 11 in the master station apparatus 101 and the synchronization processing unit 21 in the slave station apparatus 201 perform inter-station synchronization processing for synchronizing the count value of the local clock CL1 of the master station apparatus 101 with the count value of the local clock CL2 of the slave station apparatus 201 at synchronization processing timings in a predetermined cycle, for example.

More specifically, the synchronization processing unit 11 acquires the current count value of the local clock CL1 in the inter-station synchronization process, generates count information indicating the acquired count value, and outputs the count information to the frame processing unit 13.

The frame processing unit 13 receives the count information from the synchronization processing unit 11, generates an ethernet frame addressed to the slave station apparatus 201 in which the received count information is stored in the payload, and outputs the digital signal Da1 including the generated ethernet frame to the multiplexing unit 15. The digital signal Da1 outputted from the frame processing unit 13 to the multiplexing unit 15 is frequency-multiplexed with the IF signal Fa by the multiplexing unit 15, and is included in the downstream optical signal by the optical modulation unit 17, and is transmitted to the slave station apparatus 201.

Referring again to fig. 4, the frame processing unit 23 in the slave station apparatus 201 loops back the count information generated in the master station apparatus 101 in the inter-station synchronization process. More specifically, the frame processing unit 23 acquires an ethernet frame from the digital signal Da1 received from the separation unit 25, and acquires count information from the payload of the ethernet frame. The frame processing unit 23 generates an ethernet frame addressed to the master station device 101 in which the acquired count information is stored in the payload, and outputs the digital signal Db1 including the generated ethernet frame to the multiplexing unit 26. The digital signal Db1 outputted from the frame processing unit 23 to the multiplexing unit 26 is frequency-multiplexed with the IF signal Fb by the multiplexing unit 26, and is included in the upstream optical signal by the optical modulation unit 28, and is transmitted to the master device 101.

Referring again to fig. 3, the frame processing unit 13 in the master station apparatus 101 receives the digital signal Db1 from the separating unit 25, acquires an ethernet frame from the received digital signal Db1, and acquires count information from the payload of the ethernet frame. The frame processing unit 13 outputs the acquired count information to the synchronization processing unit 11.

The synchronization processing unit 11 receives the count information from the frame processing unit 13, and calculates the difference between the count value indicated by the count information and the current count value of the local clock CL1 as RTT (Round Trip Time) of the count information. The synchronization processing unit 11 calculates 1/2 of RTT as the transmission delay time DT between the master station device 101 and the slave station device 201.

When calculating the transmission delay time DT, the synchronization processing unit 11 acquires the current count value of the local clock CL1, and generates synchronization information including a synchronization time ST1, the synchronization time ST1 being a value obtained by adding the transmission delay time DT to the acquired count value. The synchronization processing unit 11 outputs the generated synchronization information to the frame processing unit 13.

The frame processing unit 13 receives the synchronization information from the synchronization processing unit 11, generates an ethernet frame addressed to the slave station apparatus 201 in which the received synchronization information is stored in the payload, and outputs the digital signal Da2 including the generated ethernet frame to the multiplexing unit 15. The digital signal Da2 outputted from the frame processing unit 13 to the multiplexing unit 15 is frequency-multiplexed with the IF signal Fa by the multiplexing unit 15, and is included in the downstream optical signal by the optical modulation unit 17, and is transmitted to the slave station apparatus 201.

Referring again to fig. 4, the frame processing unit 23 in the slave station apparatus 201 acquires an ethernet frame from the digital signal Da2 received from the slave station unit 25, and acquires synchronization information from the payload of the ethernet frame. The frame processing unit 23 outputs the acquired synchronization information to the synchronization processing unit 21.

The synchronization processing unit 21 receives the synchronization information from the frame processing unit 23, and updates the count value of the local clock CL2 based on the received synchronization information. That is, the synchronization processing unit 21 sets the count value of the local clock CL2 to the synchronization time ST1 included in the synchronization information. Thereby, the count value of the local clock CL2 of the slave station apparatus 201 is synchronized with the count value of the local clock CL2 of the master station apparatus 101.

The synchronization processing unit 11 in the master station apparatus 101 and the synchronization processing unit 21 in the slave station apparatus 201 may be configured to synchronize the count value of the local clock CL1 and the count value of the local clock CL2 according to IEEE 1588.

(Switching treatment)

Referring again to fig. 1, the master station apparatus 101 generates control information used for controlling the transmission and reception operation of the RF signal, and transmits a downstream optical signal including the digital signal Da3 and the IF signal Fa including the generated control information to the slave station apparatus 201 via the optical fiber 191.

The slave station apparatus 201 acquires control information from the digital signal Da3 included in the downlink optical signal received from the master station apparatus 101 via the optical fiber 191, and performs switching processing for switching between transmission operation and reception operation of the RF signal via the antenna 161 based on the acquired control information.

Fig. 5 is a diagram showing an example of a TDD signal transmitted from a base station apparatus according to the first embodiment of the present invention. Referring to fig. 5, the base station apparatus 111 continuously transmits a TDD signal Std1 of a rectangular wave indicating an uplink communication period UP and a downlink communication period DP in TDD to the master station apparatus 101. The TDD signal Std1 is an example of a mode signal.

As an example, the TDD signal Std1 is set to a high level in the downlink communication slot DS and to a low level in the uplink communication slot US. For example, the TDD signal Std1 transitions from a high level to a low level at the timing of switching from the downlink communication slot DS to the special slot SS, and transitions from a low level to a high level at the timing of switching from the special slot SS to the downlink communication slot DS.

The TDD processing unit 12 in the master station apparatus 101 receives the TDD signal Std1 from the base station apparatus 111, and generates control information based on the received TDD signal Std 1. As an example, the TDD processing unit 12 generates control information at a generation timing according to a predetermined generation period Cy. For example, the length of the generation period Cy is 10 milliseconds corresponding to one period of the communication frame F. The length of the generation period Cy may be a length corresponding to a plurality of periods of the communication frame F.

For example, the TDD processing section 12 determines a transition time tr, which is a timing when the TDD signal Std1 transitions from a low level to a high level, and a transition time tf, which is a timing when the TDD signal Std1 transitions from a high level to a low level.

More specifically, when detecting that the TDD signal Std1 transitions from the low level to the high level, the TDD processing unit 12 acquires the current count value of the local clock CL1 held by the synchronization processing unit 11 as the first transition time tr, that is, the transition time tr1. Next, when detecting that the TDD signal Std1 transitions from the high level to the low level, the TDD processing unit 12 acquires the current count value of the local clock CL1 held by the synchronization processing unit 11 as the first transition time tf, that is, the transition time tf1. Next, when detecting that the TDD signal Std1 transitions from the low level to the high level, the TDD processing unit 12 acquires the current count value of the local clock CL1 held by the synchronization processing unit 11 as a transition time tr2, which is the second transition time tr. Next, when detecting that the TDD signal Std1 transitions from the high level to the low level, the TDD processing unit 12 acquires the current count value of the local clock CL1 held by the synchronization processing unit 11 as a second transition time tf, that is, a transition time tf2. The TDD processing unit 12 may acquire absolute time instead of the count value as the transition times tr and tf.

Then, the TDD processing unit 12 generates a switching pattern of the transmission/reception operation of the RF signal via the antenna 161 in the slave station apparatus 201 including the transition times tr1, tf1, tr2, tf2 determined in the previous 10 milliseconds.

When the switching mode is generated, the TDD processing unit 12 sets the start timing ts of the switching process using the switching mode. As an example, the TDD processing unit 12 sets a time obtained by adding the transition time tr1, which is the earliest time among the transition times tr1, tf1, tr2, tf2, and the margin time Tm of a predetermined length, as the start timing ts. The margin time Tm is, for example, 10 milliseconds corresponding to one cycle of the communication frame F.

Referring again to fig. 3, the tdd processing unit 12 generates a switching pattern and a set start timing ts at a generation timing based on the generation period Cy, and generates control information including the generated switching pattern and start timing ts. For example, the TDD processing unit 12 generates control information including different start timings ts for each slave station apparatus 201. More specifically, the TDD processing unit 12 sets a start timing ts added to the margin time Tm of a different length for each slave station apparatus 201. The TDD processing section 12 outputs the generated control information to the frame processing section 13.

The frame processing unit 13 receives the control information from the TDD processing unit 12, generates an ethernet frame addressed to the slave station apparatus 201 in which the received control information is stored in the payload, and outputs the digital signal Da3 including the generated ethernet frame to the multiplexing unit 15.

The multiplexing unit 15 frequency-multiplexes the digital signal Da3 received from the frame processing unit 13 and the IF signal Fa received from the frequency conversion unit 14. The multiplexing unit 15 generates an electrical signal obtained by frequency-multiplexing the digital signal Da3 and the IF signal Fa, and outputs the electrical signal to the optical modulation unit 17.

The optical modulation unit 17 transmits a downstream optical signal including the digital signal Da3 and the IF signal Fa to the slave station apparatus 201 via the optical fiber 191. More specifically, the optical modulation unit 17 receives the electrical signal from the multiplexing unit 15, and generates a downstream optical signal obtained by modulating the received electrical signal. The optical modulation section 17 outputs the downstream optical signal to the optical fiber 191 via the optical coupler CP1 in the downstream communication period DP.

Referring again to fig. 4, the optical demodulation section 27 in the slave station apparatus 201 receives a downstream optical signal including the digital signal Da3 and the IF signal Fa from the master station apparatus 101 via the optical fiber 191. The optical demodulation unit 27 generates an electrical signal having a level corresponding to the intensity of the received downstream optical signal, and outputs the electrical signal to the separation unit 25.

The separation unit 25 receives the electric signal from the optical demodulation unit 27, separates the IF signal Fa and the digital signal Da3 included in the received electric signal, outputs the IF signal Fa to the RF transmission/reception unit 24, and outputs the digital signal Da3 to the frame processing unit 23.

The frame processing unit 23 acquires control information from the digital signal Da3 included in the downstream optical signal received by the optical modulation unit 17. More specifically, the frame processing unit 23 receives the digital signal Da3 from the separating unit 25, acquires an ethernet frame from the received digital signal Da3, and acquires control information from the payload of the ethernet frame. The frame processing unit 23 outputs the acquired control information to the TDD processing unit 22.

The TDD processing unit 22 performs switching processing of the RF transmitting/receiving unit 24 to perform transmission and reception of the RF signal based on the control information acquired by the frame processing unit 23.

Fig. 6 is a diagram showing an example of a TDD signal generated by a TDD processing unit in a slave device according to the first embodiment of the present invention. Referring to fig. 6, the TDD processing unit 22 receives control information from the frame processing unit 23, generates a TDD signal Std2 based on a switching pattern included in the received control information, and transmits the generated TDD signal Std2 to the switching device 151 at a start timing ts included in the control information.

Here, the length of the optical fiber 191 connecting the master station apparatus 101 and the slave station apparatus 201 is, for example, about 30km, and a propagation delay corresponding to the length of the optical fiber 191 may occur between the master station apparatus 101 and the slave station apparatus 201. By setting the time obtained by adding the transition time tr1 and the margin time Tm to the start time ts in the master station apparatus 101, the slave station apparatus 201 can receive control information before the set start time ts, and can transmit the TDD signal Std2 to the switching apparatus 151 at the start time ts.

The switching device 151 connects the antenna 161 to the transmission circuit in the RF transmitting/receiving unit 24 during a period in which the TDD signal Std2 received from the slave station device 201 is at a high level, and connects the antenna 161 to the reception circuit in the RF transmitting/receiving unit 24 during a period in which the TDD signal Std2 received from the slave station device 201 is at a low level.

The TDD processing unit 22 may be configured to correct the start timing ts included in the control information and start switching processing based on the control information at the corrected start timing tsx. More specifically, the TDD processing section 22 determines the start timing tsx by adding the delay time required for processing the control information to the start timing ts, and transmits the generated TDD signal Std2 to the switching device 151 at the determined start timing tsx.

[ Workflow of work ]

Each device in the simulated RoF system according to the embodiment of the present invention includes a computer including a memory, and an arithmetic processing unit such as a CPU in the computer reads and executes a program including part or all of each step of the following flowcharts and sequences from the memory. The programs of these plural devices can be installed from the outside. The programs of the plurality of devices are distributed in a state of being stored in a recording medium or via a communication line.

Fig. 7 is a diagram showing an example of a communication sequence in the analog RoF system according to the first embodiment of the present invention.

Referring to fig. 7, first, the master station apparatus 101 performs a base station synchronization process of synchronizing the count value of the local clock CL1 with the base station apparatus 111 (step S11).

Next, the master station apparatus 101 and the slave station apparatus 201 perform inter-station synchronization processing for synchronizing the count value of the local clock CL1 in the master station apparatus 101 with the count value of the local clock CL2 in the slave station apparatus 201 at synchronization processing timings in a predetermined cycle (step S12).

Next, the master station apparatus 101 determines transition times tr1 and tr2, which are timings at which the TDD signal Std1 received from the base station apparatus 111 transitions from a low level to a high level, and transition times tf1 and tf2, which are timings at which the TDD signal Std1 transitions from a high level to a low level, and generates control information including a switching pattern including the transition times tr1, tf1, tr2, tf2 and a start timing ts (step S13).

Next, the master station apparatus 101 generates an ethernet frame addressed to the slave station apparatus 201 in which the generated control information is stored in the payload, and generates a digital signal Da3 including the generated ethernet frame (step S14).

Next, the master station apparatus 101 frequency multiplexes the digital signal Da3 and the IF signal Fa, and transmits a downstream optical signal including the digital signal Da3 and the IF signal Fa to the slave station apparatus 201 via the optical fiber 191 (step S15).

Next, the slave station apparatus 201 receives the downstream optical signal from the master station apparatus 101 via the optical fiber 191, and acquires the digital signal Ds3 from the received downstream optical signal (step S16).

Next, the slave station apparatus 201 acquires control information from the digital signal Ds3 (step S17).

Next, the slave station apparatus 201 performs a switching process based on the acquired control information. More specifically, the slave station device 201 generates the TDD signal Std2 based on the switching pattern included in the control information, and transmits the TDD signal Std2 to the switching device 151 at the start timing ts included in the control information (step S18).

In the analog RoF system 301 according to the first embodiment of the present invention, the slave station apparatus 201 is configured to transmit and receive RF signals via the switch apparatus 151 and the antenna 161, but the present invention is not limited thereto. The slave station apparatus 201 may have a configuration including a switching apparatus 151.

However, in the analog RoF system 301 having the master station apparatus 101 and the slave station apparatus 201, a technique capable of realizing TDD with a simple structure is desired.

For example, in a mobile radio communication system employing TDD, in order to suppress radio interference, it is desirable to control the transmission timing of an RF signal with high accuracy.

Further, for example, in a mobile wireless communication system using a millimeter wave band, since the coverage area of the antenna 161 is small, it is necessary to provide more secondary station apparatuses 201 and antennas 161 at high density. Therefore, in order to realize a mobile wireless communication system using a millimeter wave band with a low cost and simple structure, it is desirable to simplify the structure of the secondary station apparatus 201.

In contrast, in the analog RoF system 301 according to the first embodiment of the present invention, the master station apparatus 101 generates control information used for controlling the transmission/reception operation of the RF signal, and transmits a downstream optical signal including the digital signal Ds3 and the IF signal Fa including the generated control information to the slave station apparatus 201 via the optical fiber 191. The slave station apparatus 201 acquires control information from the digital signal Ds3 included in the downstream optical signal received from the master station apparatus 101 via the optical fiber 191, and performs switching processing between transmission operation and reception operation of the RF signal via the antenna 161 based on the acquired control information.

As described above, the master station apparatus 101 transmits the downstream optical signal including the digital signal Ds3 and the IF signal Fa to the slave station apparatus 201 via the optical fiber 191, the slave station apparatus 201 acquires control information from the digital signal Ds3 included in the downstream optical signal, and performs switching processing of transmission operation and reception operation of the RF signal via the antenna 161 based on the acquired control information, and according to this configuration, it is possible to transmit control information from the master station apparatus 101 to the slave station apparatus 201 via the optical fiber 191 and perform switching processing of transmission/reception operation of the slave station apparatus 201. Accordingly, in the analog RoF system 301 having the master station apparatus 101 and the slave station apparatus 201, TDD can be realized with a simple structure.

Further, by changing the content of the control information generated in the master station apparatus 101, the content of the switching process of the transmission/reception operation in the slave station apparatus 201 can be flexibly changed.

Next, other embodiments of the present invention will be described with reference to the drawings. The same or corresponding portions in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

< Second embodiment >

In comparison with the analog RoF system 301 of the first embodiment, the present embodiment relates to an analog RoF system 302 that transmits control information including a configuration number indicating the type of TDD signal Std 1. Except for what is described below, the analog RoF system 301 of the first embodiment is the same.

Fig. 8 is a diagram showing a configuration of an analog RoF system according to a second embodiment of the present invention. Referring to fig. 8, in contrast to the analog RoF system 301 shown in fig. 1, the analog RoF system 302 has the master station apparatus 102 instead of the master station apparatus 101, and has the slave station apparatus 202 instead of the slave station apparatus 201.

Fig. 9 is a diagram showing a configuration of a master station device according to a second embodiment of the present invention. Referring to fig. 9, compared with the master device 101 shown in fig. 3, the master device 102 includes a TDD processing unit 32 in place of the TDD processing unit 12 and an information storage unit 31.

Fig. 10 is a diagram showing an example of a correspondence table held in the information storage unit in the master station device according to the second embodiment of the present invention. Referring to fig. 10, the information storage unit 31 holds a correspondence table TB1, and the correspondence table TB1 indicates a correspondence relationship between the allocation pattern PT of the slot S in the communication frame F and the arrangement number as the identification information of the TDD signal Std 1. The correspondence table TB1 is an example of correspondence information. The pattern of the slot S in the communication frame F indicates the kind of the TDD signal Std 1.

The correspondence table TB1 shows an allocation pattern PT in which the TDD signal Std1 having the configuration number "C1" corresponds to 4 downlink communication slots DS and 4 uplink communication slots US alternately repeated across the special slot SS. Further, the correspondence table TB1 shows that the TDD signal Std1 having the configuration number "C2" corresponds to an allocation pattern PT in which 9 downlink communication slots DS and 9 uplink communication slots US are alternately repeated across the special slot SS. Further, the correspondence table TB1 shows that the TDD signal Std1 of which configuration number is "C3" corresponds to an allocation pattern PT in which 4 downlink communication slots DS and 2 uplink communication slots US are alternately repeated across the special slot SS. Further, the correspondence table TB1 shows that the TDD signal Std1 of the configuration number "C4" corresponds to an allocation pattern PT in which 4 uplink communication slots US and 2 downlink communication slots DS are alternately repeated across the special slot SS. The correspondence table TB1 shows that the TDD signal Std1 with the configuration number "C11" corresponds to the allocation pattern PT in which the slots s#3 to s#5 are changed from the downlink communication slot DS to the uplink communication slot US in the allocation pattern PT of the TDD signal Std1 with the configuration number "C2".

The correspondence table TB1 held in the information storage unit 3 may be updated by a control device not shown. When the correspondence table TB1 in the information storage unit 31 is updated, the master device 102 transmits the updated correspondence table TB1 to the slave device 202.

When acquiring transition times tr and tf of a TDD signal Std1 received from a base station apparatus 111, the TDD processing unit 32 performs generation of a switching pattern including the acquired transition times tr and tf and setting of a start timing ts.

Further, the TDD processing unit 32 refers to the correspondence table TB1 in the information storage unit 31, and acquires the configuration number corresponding to the TDD signal Std1 received from the base station apparatus 111. More specifically, the TDD processing unit 32 acquires the configuration number corresponding to the type of the TDD signal Std1 indicated by the acquired transition times tr and tf.

Then, the TDD processing unit 32 generates control information including the switching pattern, the start timing ts, and the acquired configuration number, and outputs the generated control information to the frame processing unit 13.

The frame processing unit 13 receives the control information from the TDD processing unit 32, generates an ethernet frame addressed to the slave station apparatus 201 in which the received control information is stored in the payload, and outputs the digital signal Da4 including the generated ethernet frame to the multiplexing unit 15.

The multiplexing unit 15 frequency-multiplexes the digital signal Da4 received from the frame processing unit 13 and the IF signal Fa received from the frequency conversion unit 14. The multiplexing unit 15 generates an electrical signal obtained by frequency-multiplexing the digital signal Da4 and the IF signal Fa, and outputs the electrical signal to the optical modulation unit 17.

The optical modulation unit 17 transmits a downstream optical signal including the digital signal Da4 and the IF signal Fa to the slave station device 202 via the optical fiber 191. More specifically, the optical modulation unit 17 receives the electrical signal from the multiplexing unit 15, and generates a downstream optical signal obtained by modulating the received electrical signal. The optical modulation section 17 outputs the downstream optical signal to the optical fiber 191 via the optical coupler CP1 in the downstream communication period DP.

Fig. 11 is a diagram showing a configuration of a secondary station apparatus according to a second embodiment of the present invention. Referring to fig. 11, compared with the slave station apparatus 201 shown in fig. 4, the slave station apparatus 202 includes the TDD processing unit 42 in place of the TDD processing unit 22 and also includes the information storage unit 41.

The information storage unit 41 holds the correspondence table TB1, as in the information storage unit 31 of the master device 102.

The optical demodulation unit 27 receives the downstream optical signal including the digital signal Da4 and the IF signal Fa from the master station apparatus 101 via the optical fiber 191, generates an electrical signal having a level corresponding to the intensity of the received downstream optical signal, and outputs the electrical signal to the separation unit 25.

The separation unit 25 receives the electric signal from the optical demodulation unit 27, separates the IF signal Fa and the digital signal Da4 included in the received electric signal, outputs the IF signal Fa to the RF transmission/reception unit 24, and outputs the digital signal Da4 to the frame processing unit 23.

The frame processing unit 23 receives the digital signal Da4 from the separating unit 25, acquires an ethernet frame from the received digital signal Da4, and acquires control information from the payload of the ethernet frame. The frame processing unit 23 outputs the acquired control information to the TDD processing unit 42.

The TDD processing unit 42 receives the control information from the frame processing unit 23, and acquires the configuration number from the received control information. The TDD processing unit 42 refers to the correspondence table TB1 in the information storage unit 41, and acquires the allocation pattern PT corresponding to the acquired configuration number. The TDD processing unit 42 generates a TDD signal Std2 based on the acquired allocation pattern PT, and transmits the generated TDD signal Std2 to the switching device 151 at a start timing ts included in the control information.

The TDD processing unit 42 may be configured to correct the start timing ts included in the control information and start switching processing based on the control information at the corrected start timing tsx. For example, the TDD processing unit 42 corrects the start timing ts included in the control information received from the frame processing unit 23 based on the acquired allocation pattern PT. More specifically, when the difference between the transition times tr and tf included in the control information and the transition times tr and tf estimated from the acquired allocation pattern PT is equal to or greater than a predetermined value, the TDD processing unit 42 corrects the start timing ts included in the control information so that the difference becomes smaller.

For example, the TDD processing unit 42 may be configured to perform error correction of the TDD signal Std2 generated based on the switching mode based on the acquired allocation mode PT, or may be configured to perform distortion correction of the duty ratio of the generated TDD signal Std 2.

In the analog RoF system 302 according to the second embodiment of the present invention, the TDD processing unit 32 in the master device 102 is configured to acquire the configuration number corresponding to the TDD signal Std1 received from the base station device 111, but the present invention is not limited thereto. The TDD processing unit 32 may be configured to receive notification of the configuration number from the base station apparatus 111. In this case, the TDD processing unit 32 generates control information including the notified configuration number, and outputs the control information to the frame processing unit 23. In this case, the TDD processing unit 32 may not receive the TDD signal Std1 from the base station apparatus 111.

Next, other embodiments of the present invention will be described with reference to the drawings. The same or corresponding portions in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

< Third embodiment >

In contrast to the analog RoF system 302 of the second embodiment, the present embodiment relates to an analog RoF system 303 that generates control information based on mode information received from the management device 171 in the mobile wireless communication system. Except for what is described below, the simulated RoF system 302 of the second embodiment is identical.

Fig. 12 is a diagram showing a configuration of an analog RoF system according to a third embodiment of the present invention. Referring to fig. 12, in contrast to the analog RoF system 302 shown in fig. 8, the analog RoF system 303 has the master station apparatus 103 instead of the master station apparatus 102, and has the slave station apparatus 203 instead of the slave station apparatus 202.

The secondary station apparatus 203 receives mode information indicating an uplink communication period UP and a downlink communication period DP in TDD from an apparatus other than the primary station apparatus 103 outside the secondary station apparatus 203. For example, the slave station apparatus 203 receives the mode information from the management apparatus 171 in the mobile wireless communication system.

More specifically, in order to increase the link speed of uplink communication according to the communication status of a mobile communication terminal in a mobile radio communication system, for example, the management device 171 may change a part of the downlink communication period DP in TDD to the uplink communication period UP in some of the slave station devices 203. When a part of the downlink communication period DP is changed to the uplink communication period UP, the management device 171 generates pattern information including a configuration number corresponding to the allocation pattern PT indicating the time slot S of the changed uplink communication period UP and downlink communication period DP. The management device 171 generates a frame addressed to the slave station device 203 in which the generated pattern information is stored, and transmits an RF signal including the generated frame. In order to increase the link speed of the downlink communication, the management device 171 may change a part of the uplink communication period UP to the downlink communication period DP, and generate pattern information including a configuration number corresponding to the allocation pattern PT of the slot S indicating the changed uplink communication period UP and downlink communication period DP. The management device 171 may be configured to transmit a frame including the mode information to the slave station device 203 via the wired transmission line.

Fig. 13 is a diagram showing a configuration of a master station device according to a third embodiment of the present invention. Referring to fig. 13, compared with the master device 102 shown in fig. 9, the master device 103 has a TDD processing unit 52 instead of the TDD processing unit 32.

Fig. 14 is a diagram showing a configuration of a slave station apparatus according to a third embodiment of the present invention. Referring to fig. 14, the slave station apparatus 203 has a TDD processing section 62 instead of the TDD processing section 42, as compared with the slave station apparatus 202 shown in fig. 11.

The TDD processing unit 62 receives an RF signal including mode information from the management apparatus 171 via the antenna 161 and the switching apparatus 151. The TDD processing section 62 acquires pattern information from the received RF signal, and outputs the acquired pattern information to the frame processing section 23.

The frame processing unit 23 receives the pattern information from the TDD processing unit 62, generates an ethernet frame addressed to the master station device 103 in which the received pattern information is stored in the payload, and outputs the digital signal Db2 including the generated ethernet frame to the multiplexing unit 26. The digital signal Db2 is an example of the second digital signal. The digital signal Db2 output from the frame processing unit 23 to the multiplexing unit 26 is frequency-multiplexed with the IF signal Fb by the multiplexing unit 26, and is included in the upstream optical signal by the optical modulation unit 28, and is transmitted to the master device 103.

Referring again to fig. 13, the master station apparatus 103 acquires pattern information from the digital signal Db2 included in the uplink optical signal received from the slave station apparatus 203, and generates control information reflecting the content of the acquired pattern information.

More specifically, the frame processing unit 13 in the master station device 103 receives the digital signal Db2 from the separation unit 25, acquires an ethernet frame from the received digital signal Db2, and acquires pattern information from the payload of the ethernet frame. The frame processing unit 13 outputs the acquired mode information to the TDD processing unit 52.

The TDD processing unit 52 receives the mode information from the frame processing unit 13, and acquires the configuration number from the received mode information. The TDD processing unit 52 refers to the correspondence table TB1 in the information storage unit 31, and acquires the allocation pattern PT corresponding to the acquired configuration number. The TDD processing section 52 generates control information reflecting the acquired allocation pattern PT.

Referring again to fig. 10, for example, when the TDD processing unit 52 receives the mode information including the configuration number "C11" from the frame processing unit 13, it acquires the allocation mode PT corresponding to the configuration number "C11" and determines whether or not the acquired allocation mode PT is in a quasi-synchronous state with respect to the TDD signal Std1 received from the base station apparatus 111.

Specifically, when the acquired allocation pattern PT corresponds to an allocation pattern in which a part of the period of the high level in the TDD signal Std1 is changed to the low level, the TDD processing unit 52 determines that the acquired allocation pattern PT is in a quasi-synchronous state with respect to the TDD signal Std1, generates control information including the configuration number "C11" and the start timing ts, and outputs the generated control information to the frame processing unit 13.

On the other hand, when the TDD processing unit 52 determines that the acquired allocation pattern PT is not in the quasi-synchronous state with respect to the TDD signal Std1, it does not generate control information including the configuration number "C11".

The frame processing unit 13 receives the control information from the TDD processing unit 52, generates an ethernet frame addressed to the slave station device 203 in which the received control information is stored in the payload, and outputs the digital signal Da3 including the generated ethernet frame to the multiplexing unit 15. The digital signal Da1 output from the frame processing unit 13 to the multiplexing unit 15 is frequency-multiplexed with the IF signal Fa by the multiplexing unit 15, and is included in the downstream optical signal by the optical modulation unit 17, and is transmitted to the slave station device 203.

Fig. 15 is a diagram showing an example of a communication sequence in an analog RoF system according to the third embodiment of the present invention. Referring to fig. 15, the master station apparatus 103 and the slave station apparatus 203 perform the same processing as in steps S11 to S18 shown in fig. 7, and the processing is performed as in steps S21 to S28.

Next, the slave station apparatus 203 receives the mode information from the management apparatus 171 in the mobile wireless communication system (step S29).

Next, the slave station device 203 generates an ethernet frame addressed to the master station device 103, in which the received pattern information is stored in the payload, frequency multiplexes the digital signal Db2 and the IF signal Fb including the generated ethernet frame, and transmits an uplink optical signal including the digital signal Db2 and the IF signal Fb to the master station device 103 via the optical fiber 191 (step S30).

Next, the master station device 103 generates control information reflecting the content of the mode information received from the slave station device 203 (step S31).

Next, the master station device 103 generates an ethernet frame addressed to the slave station device 203 in which the generated control information is stored in the payload, and generates a digital signal Da3 including the generated ethernet frame (step S32).

Next, the master station apparatus 103 frequency multiplexes the digital signal Da3 and the IF signal Fa, and transmits a downstream optical signal including the digital signal Da3 and the IF signal Fa to the slave station apparatus 203 via the optical fiber 191 (step S33).

Next, the slave station apparatus 203 receives the downstream optical signal from the master station apparatus 103 via the optical fiber 191, and acquires the digital signal Ds3 from the received downstream optical signal (step S34).

Next, the slave station apparatus 203 acquires control information from the digital signal Ds3 (step S35).

Next, the slave station apparatus 203 performs a switching process based on the acquired control information. More specifically, the slave station device 203 generates the TDD signal Std2 based on the switching pattern included in the control information, and transmits the TDD signal Std2 to the switching device 151 at the start timing ts included in the control information (step S36).

In the analog RoF system 303 according to the third embodiment of the present invention, the TDD processing unit 52 in the master device 103 generates control information including the configuration number when the allocation pattern PT corresponding to the configuration number included in the pattern information is in a quasi-synchronous state with respect to the TDD signal Std1, but the present invention is not limited thereto. The TDD processing unit 52 may generate a switching pattern including transition times tr and tf based on the allocation pattern PT corresponding to the configuration number included in the pattern information and the TDD signal Std1, and generate control information including the generated switching pattern. In this case, the TDD processing unit 52 may generate a new switching pattern according to the change in the length of the slot S.

The processes (functions) of the above embodiments are implemented by a processing circuit (Circuitry) including one or more processors. The processing circuit may be constituted by an integrated circuit or the like in which one or more memories, various analog circuits, various digital circuits, and the like are combined in addition to the one or more processors. The one or more memories store programs (instructions) that cause the one or more processors to execute the processes. The one or more processors may execute the processes according to the programs read from the one or more memories, or may execute the processes according to logic circuits designed in advance to execute the processes. The processors may be various processors suitable for controlling a computer, such as a CPU (Central Processing Unit: central processing unit), GPU (Graphics Processing Unit: graphics Processor), DSP (DIGITAL SIGNAL Processor: digital signal Processor), FPGA (Field Programmable GATE ARRAY: field programmable gate array), and ASIC (Application SPECIFIC INTEGRATED Circuit). Further, the plurality of processors physically separated may cooperate with each other to execute the respective processes. For example, the processors respectively mounted on a plurality of physically separated computers may cooperate with each other through a network such as a LAN (Local Area Network: local area network), a WAN (Wide Area Network: wide area network), and the Internet to execute the respective processes. The program may be installed in the Memory from an external server device or the like through the network, or may be stored in a recording medium such as a CD-ROM (Compact Disc Read Only Memory: compact disc read Only Memory), a DVD-ROM (DIGITAL VERSATILE DISK READ Only Memory: digital versatile disc read Only Memory), or a semiconductor Memory, and may be installed in the Memory from the recording medium.

The above embodiments should be considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

The above description includes the features noted below.

[ Additional note 1]

An analog RoF system, having:

Master station apparatus, and

A slave station device which transmits and receives a radio signal via an antenna,

The master station device generates control information used for controlling the transmission/reception operation of the radio signal, transmits an optical signal including a first digital signal and an analog master signal to the slave station device via an optical fiber, the first digital signal including the generated control information,

The secondary station apparatus acquires the control information from the first digital signal included in the optical signal received from the primary station apparatus via the optical fiber, performs switching processing of transmission operation and reception operation of the wireless signal via the antenna based on the acquired control information,

The master station device and the slave station device perform inter-station synchronization processing for synchronizing a count value of a local clock of the master station device with a count value of a local clock of the slave station device at a timing in a predetermined cycle.

Description of the reference numerals

11, A synchronization processing part;

12. 32, 52:tdd processing part;

A frame processing unit;

14, a frequency conversion part;

15, a multiplexing part;

16, a separating part;

17, a light modulation part;

18, a light demodulation part;

A synchronization processing unit 21;

22. 42, 62:tdd processing part;

a frame processing unit 23;

24, an RF transceiver;

25, a separating part;

a multiplexing unit 26;

27, a light demodulation part;

a light modulation unit 28;

31, an information storage unit;

an information storage unit 41;

101. 102, 103, a master station device;

111, a base station apparatus;

151, switching device;

161 an antenna;

171, a management device;

191, optical fiber;

201. 202, 203 slave station means;

301. 302, 303, analog RoF system;

CP1, CP2: optocouplers;

TB1, correspondence table.

Claims (10)

1. An analog RoF (Radio over Fiber) system having:

Master station apparatus, and

A slave station device which transmits and receives a radio signal via an antenna,

The master station device generates control information used for controlling the transmission/reception operation of the radio signal, transmits an optical signal including a first digital signal and an analog master signal to the slave station device via an optical fiber, the first digital signal including the generated control information,

The slave station apparatus acquires the control information from the first digital signal included in the optical signal received from the master station apparatus via the optical fiber, and performs a process of switching between transmission operation and reception operation of the wireless signal via the antenna based on the acquired control information.

2. The simulated RoF system of claim 1, wherein,

The master station means is connected between base station means and the slave station means,

The master station apparatus receives a pattern signal indicating an uplink communication period and a downlink communication period in TDD (Time Division Duplex ) from the base station apparatus, and generates the control information based on the received pattern signal.

3. The simulated RoF system of claim 2, wherein,

The master station device generates a switching pattern of the transmission/reception operation of the radio signal based on the pattern signal, and generates the control information including the generated switching pattern and a start timing of the switching process using the switching pattern.

4. The simulated RoF system of claim 2, wherein,

The master station apparatus and the slave station apparatus hold correspondence information indicating a correspondence between the type of the pattern signal and identification information of the pattern signal,

The master station device acquires the identification information corresponding to the mode signal received from the base station device with reference to the correspondence information, and generates the control information including the acquired identification information and the start timing of the switching process using the identification information.

5. The simulated RoF system of claim 3 or claim 4, wherein,

The analog RoF system has a plurality of the secondary station apparatuses,

The master station apparatus generates the control information including the different start timing for each of the slave station apparatuses.

6. The simulated RoF system of any one of claim 3 to claim 5, wherein,

The slave station device corrects the start timing included in the control information, and starts the switching process based on the control information at the corrected start timing.

7. The simulated RoF system of any one of claim 1 to claim 6, wherein,

The secondary station apparatus receives mode information indicating an uplink communication period and a downlink communication period in TDD from an apparatus other than the primary station apparatus outside the secondary station apparatus, generates a second digital signal including the received mode information, transmits an optical signal including the generated second digital signal and an analog primary signal to the primary station apparatus via the optical fiber,

The master station apparatus acquires the pattern information from the second digital signal included in the optical signal received from the slave station apparatus via the optical fiber, and generates the control information reflecting the content of the acquired pattern information.

8. A master station device, comprising:

a control information generation unit for generating control information used for controlling the transmission/reception operation of the wireless signal by the slave station device via the antenna, and

And a transmitting unit that transmits an optical signal including a digital signal and an analog master signal to the slave station apparatus via an optical fiber, the digital signal including the control information generated by the control information generating unit.

9. A slave station apparatus, having:

a wireless transmitting/receiving unit that transmits/receives wireless signals via an antenna;

a receiving unit that receives an optical signal including a digital signal and an analog main signal from a master station device via an optical fiber, the digital signal including control information;

An acquisition unit that acquires the control information from the digital signal included in the optical signal received by the reception unit, and

And a control unit that performs switching processing between transmission operation and reception operation of the wireless signal by the wireless transmitting/receiving unit via the antenna, based on the control information acquired by the acquisition unit.

10. An optical communication method in an analog RoF system having a master station device and a slave station device that transmits and receives a wireless signal via an antenna, the optical communication method comprising:

A step of generating control information used for controlling the transmission/reception operation of the radio signal by the master station apparatus, and transmitting an optical signal including a first digital signal and an analog master signal to the slave station apparatus via an optical fiber, wherein the first digital signal includes the generated control information, and

And a step in which the slave station apparatus acquires the control information from the first digital signal included in the optical signal received from the master station apparatus via the optical fiber, and performs a process of switching between transmission operation and reception operation of the wireless signal via the antenna based on the acquired control information.