Transmission system and transmission method

Abstract

A transmission system comprising one or more first communication devices each of which transmits / receives a wireless signal to / from a wireless terminal device, one or more second communication devices each of which transmits / receives an optical signal to / from a first communication device, and one or more transfer devices each of which transfers the optical signal between a first communication device and second communication device. Each first communication device performs conversion between the wireless signal transmitted to or received from a wireless terminal device and an optical signal with a wavelength corresponding to the physical characteristics of a wireless section over which the wireless signal is transmitted. Each transfer device receives the input of an optical signal between a first communication device and second communication device and transfers the input optical signal to a first communication device, second communication device, or transfer device serving as a transfer destination corresponding to the wavelength of the optical signal. Each second communication device transmits to or receives from a first communication device an optical signal which has been transferred by one or more transfer devices and which has a wavelength corresponding to a wireless section to be processed by the second communication device.

Description

Technical Field

[0001] The present invention relates to a transmission system and a transmission method.

Background Art

[0002] As a technology for efficiently accommodating a wireless system, research on analog RoF (Radio-over-Fiber) technology that directly converts a wireless signal into an optical signal and transmits it through an optical fiber has been underway (see, for example, Non-Patent Document 1). For example, in a wireless LAN (Local Area Network), there is a technology for constructing a network that maps an SSID (Service Set Identifier), which is an identifier for a wireless section, to a VLAN (Virtual Local Area Network) and is logically segmented into a wireless section and a wired section (see, for example, Non-Patent Document 2).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The segments created by mapping SSIDs and VLANs, and the resulting connections between wireless and wired sections, are logical segments, not physical segments. This leads to problems such as processing delays in logical Layer 2 switching when an intermediate Layer 2 switch is present, and security concerns compared to physical segments.

[0005] In view of the above circumstances, the present invention aims to provide a transmission system and a transmission method that can reduce signal transmission delay while improving security in a network including wireless and wired sections. [Means for solving the problem]

[0006] One aspect of the present invention is a transmission system comprising: one or more first communication devices that transmit and receive wireless signals with a wireless terminal device; one or more second communication devices that transmit and receive optical signals with the first communication device; and one or more transfer devices that transfer optical signals between the first communication device and the second communication device, wherein the first communication device converts wireless signals transmitted and received with the wireless terminal device into optical signals with wavelengths corresponding to the physical characteristics of the wireless section transmitted by the wireless signals; the transfer devices input optical signals between the first communication device and the second communication device, and transfer the input optical signals to the first communication device, the second communication device, or other transfer devices corresponding to the wavelength of the optical signals; and the second communication device transmits and receives optical signals with the first communication device that have been transferred by one or more transfer devices and that correspond to the wireless section to be processed by the device itself.

[0007] One aspect of the present invention is a transmission method in a transmission system comprising a wireless terminal device and one or more first communication devices that transmit and receive wireless signals, one or more second communication devices that transmit and receive optical signals with the first communication devices, and one or more transfer devices that transfer optical signals between the first communication devices and the second communication devices, the transmission method comprising: the first communication device converting a wireless signal transmitted and received with the wireless terminal device into an optical signal with a wavelength corresponding to the physical characteristics of the wireless section transmitted by the wireless signal; the transfer device inputting the optical signal between the first communication device and the second communication device and transferring the input optical signal to the first communication device, the second communication device, or another transfer device to which the optical signal is to be transferred according to its wavelength; and the second communication device transmitting and receiving the optical signal with the first communication device, which has been transferred by one or more transfer devices and corresponds to the wireless section to be processed by the device itself. [Effects of the Invention]

[0008] The present invention makes it possible to reduce signal transmission delay while improving security in a network that includes both wireless and wired sections. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example configuration of a transmission system according to an embodiment of the present invention. [Figure 2] This figure shows the identifier for the wireless section according to the same embodiment. [Figure 3] This figure shows the identifier for the wireless section according to the same embodiment. [Figure 4] This is a functional block diagram of the first and second wireless base stations according to the same embodiment. [Figure 5] This figure shows the function of the gateway according to the same embodiment. [Figure 6] This figure shows signal transfer in the transmission system according to the same embodiment. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings. The transmission system of this embodiment maps wireless signals and optical signals in the wired section to each other through physical conversion and segmentation. Therefore, signal processing that causes delays when logical processing is performed, and switching and other processes that are performed by accumulating in a buffer are eliminated. Thus, processing delays can be reduced. Furthermore, the transmission system of this embodiment can transfer signals without performing logical processing. Security is improved because there are no intermediate devices that perform logical processing.

[0011] Figure 1 shows an example configuration of a transmission system 1 according to an embodiment of the present invention. The transmission system 1 is an analog RoF (Radio-over-Fiber) transmission system. The transmission system 1 includes a wireless terminal 2, a first wireless base station 3, a second wireless base station 4, and a gateway 5. For example, the first wireless base station 3 is an outpost station, and the second wireless base station 4 is an aggregation station.

[0012] The first radio base station 3 transmits and receives radio signals with the radio terminal 2. The first radio base station 3 is also connected to the gateway 5 via an optical fiber 6. The first radio base station 3 has the function of converting the RF (Radio Frequency) radio signal received from the radio terminal 2 into an optical signal while keeping it as an analog signal. The first radio base station 3 converts the radio signal received from the radio terminal 2 into an optical signal with a wavelength corresponding to the identifier of the radio section to which the radio signal is transmitted, and transmits the converted optical signal to the second radio base station 4 via the gateway 5. The identifier of the radio section is a physical characteristic of the radio section. The first radio base station 3 also converts the optical signal input from the second radio base station 4 via the optical fiber 6 into an analog radio signal, and transmits the converted radio signal to the radio terminal 2 using the radio section with an identifier corresponding to the wavelength of the optical signal.

[0013] The second radio base station 4 is connected to the gateway 5 via the optical transmission path 7. The second radio base station 4 performs modulation and demodulation of radio signals and access control using digital processing. A second radio base station 4 is determined to perform processing for each radio section. The second radio base station 4 receives the optical signal output by the first radio base station 3 via one or more gateways 5 and converts the received optical signal into an electrical signal. The second radio base station 4 demodulates the radio signal as an electrical signal using digital processing. The second radio base station 4 also generates a radio signal by modulating the signal to be transmitted to the radio terminal 2 using digital processing. The second radio base station 4 converts the generated radio signal into an optical signal with a wavelength corresponding to the radio section used by the destination radio terminal 2, and outputs the converted optical signal to the first radio base station 3 via the gateway 5.

[0014] Gateway 5 receives an optical signal and outputs the received optical signal to an output destination corresponding to the wavelength of the received optical signal. Specifically, Gateway 5 receives an optical signal output by the first radio base station 3, and selects whether to drop (branch) the input optical signal to the second radio base station 4 connected to its own device, or to forward it to another Gateway 5 connected via optical fiber 6, according to its wavelength, and performs the selected process. Gateway 5 also receives an optical signal output by the second radio base station 4, and selects whether to forward the input optical signal to the first radio base station 3 connected to its own device, or to another Gateway 5, according to its wavelength, and forwards the optical signal to the selected destination.

[0015] Figure 1 shows an example in which the first radio base station 3 transmits and receives an optical signal with a wavelength determined according to the identifier of the radio section to the second radio base station 4 via gateway 5. The three gateways 5 connected in a ring shape via optical fiber 6 are denoted as gateways 5a, 5b, and 5c. The first radio base station 3 and the second radio base station 4 connected to gateway 5a are denoted as first radio base station 3a and second radio base station 4a, respectively. The second radio base station 4 connected to gateway 5b is denoted as second radio base station 4b. The first radio base station 3 and the second radio base station 4 connected to gateway 5c are denoted as first radio base station 3c and second radio base station 4c, respectively. In addition, the three radio terminals 2 that communicate wirelessly with the first radio base station 3a are denoted as radio terminals 2a-1 to 2a-3, and the radio terminal 2 that communicates wirelessly with the first radio base station 3c is denoted as radio terminal 2c.

[0016] This section describes signal transfer in uplink communication from wireless terminal 2 to the second wireless base station 4. The first wireless base station 3a receives the uplink wireless signal and converts the received wireless signal into an optical signal with a wavelength corresponding to the wireless section identifier. Alternatively, the first wireless base station 3a selects the second wireless base station 4 based on the wireless section identifier and converts the signal into an optical signal with a wavelength corresponding to the selected second wireless base station 4. The first wireless base station 3a converts the wireless signal received from wireless terminal 2a-1 into an optical signal with wavelength α, the wireless signal received from wireless terminal 2a-2 into an optical signal with wavelength β, and the wireless signal received from wireless terminal 2a-3 into an optical signal with wavelength γ. The first wireless base station 3a outputs these optical signals with wavelengths α, β, and γ to the optical fiber 6 between itself and gateway 5a.

[0017] Gateway 5a receives optical signals of wavelengths α, β, and γ output by the first wireless base station 3a via optical fiber 6. Gateway 5a drops the optical signal of wavelength α to the second wireless base station 4a, which is the output destination corresponding to wavelength α. Gateway 5a also outputs the optical signal of wavelength β to the optical fiber 6 between it and gateway 5b, which is the output destination corresponding to wavelength β, and outputs the optical signal of wavelength γ to the optical fiber 6 between it and gateway 5c, which is the output destination corresponding to wavelength γ.

[0018] The second radio base station 4a converts the optical signal of wavelength α dropped by the gateway 5a into an electrical signal, and performs predetermined digital processing on the radio signal from the radio terminal 2a-1 converted into the electrical signal.

[0019] The gateway 5b drops the optical signal of wavelength β transferred from the gateway 5a to the second radio base station 4b at the output destination corresponding to wavelength β. The second radio base station 4b converts the optical signal of wavelength β dropped by the gateway 5b into an electrical signal, and performs predetermined digital processing on the radio signal from the radio terminal 2a-2 converted into the electrical signal.

[0020] The gateway 5c drops the optical signal of wavelength γ transferred from the gateway 5a to the second radio base station 4c at the output destination corresponding to wavelength γ. The second radio base station 4c converts the optical signal of wavelength γ dropped by the gateway 5c into an electrical signal, and performs predetermined digital processing on the radio signal from the radio terminal 2a-3 converted into the electrical signal.

[0021] The signal transfer in the downlink communication from the second radio base station 4 to the radio terminal 2 is reverse to the above uplink communication. That is, the second radio base station 4a converts the radio signal destined for the radio terminal 2a-1 into an optical signal of wavelength α corresponding to the radio section used by the radio terminal 2a-1 or the local station, and outputs the converted optical signal to the gateway 5a. The gateway 5a outputs the optical signal of wavelength α input from the second radio base station 4a to the optical fiber 6 between the first radio base station 3a at the output destination corresponding to wavelength α. The first radio base station 3a converts the optical signal of wavelength α into a radio signal, and wirelessly transmits the converted radio signal to the radio terminal 2a-1 using the radio section corresponding to wavelength α.

[0022] The second radio base station 4b converts the radio signal destined for the radio terminal 2a-2 into an optical signal of wavelength β corresponding to the radio section used by the radio terminal 2a-2 or its own station, and outputs the converted optical signal to gateway 5b. Gateway 5b outputs the optical signal of wavelength β input from the second radio base station 4b to the optical fiber 6 between it and gateway 5a, which is the output destination corresponding to wavelength β. Gateway 5a outputs the optical signal of wavelength β input from the second radio base station 4b to the optical fiber 6 between it and the first radio base station 3a, which is the output destination corresponding to wavelength β. The first radio base station 3a converts the optical signal of wavelength β into a radio signal and wirelessly transmits the converted radio signal to the radio terminal 2a-2 using the radio section corresponding to wavelength β.

[0023] The second radio base station 4c converts the radio signal destined for the radio terminal 2a-3 into an optical signal of wavelength γ corresponding to the radio section used by the radio terminal 2a-3 or its own station, and outputs the converted optical signal to gateway 5c. Gateway 5c outputs the optical signal of wavelength γ received from the second radio base station 4c into the optical fiber 6 between it and gateway 5a, which is the output destination corresponding to wavelength γ. Gateway 5a outputs the optical signal of wavelength γ received from the second radio base station 4c into the optical fiber 6 between it and the first radio base station 3a, which is the output destination corresponding to wavelength γ. The first radio base station 3a converts the optical signal of wavelength γ into a radio signal and wirelessly transmits the converted radio signal to the radio terminal 2a-3 using the radio section corresponding to wavelength γ.

[0024] As described above, the analog RoF transmission system converts radio signals into optical signals and transmits them from the first radio base station to the second radio base station via a gateway. The analog RoF transmission system determines the wavelength for transmitting the optical signal through the optical fiber using an identifier for the radio section, and determines the gateway to which the optical signal will be transferred according to the determined wavelength.

[0025] Furthermore, different wavelengths may be used for the upstream and downstream signals between the same device. When the same wavelength is used for the upstream and downstream signals between the same device, different optical fibers 6 and optical transmission lines 7 may be used for the upstream and downstream signals, and the upstream and downstream signals may be transmitted in time division multiplexing.

[0026] Figures 2 and 3 show identifiers for radio sections. Figure 2 shows an example where the frequency of the radio section is used as the identifier for the radio section. The first radio base station 3a determines which of the second radio base stations 4a, 4b, or 4c is the destination of the radio signal, based on the frequency of the uplink radio signal received from the radio terminal 2. The first radio base station 3a converts the received radio signal into an optical signal with a wavelength corresponding to the determined destination. The second radio base station 4 converts the downlink radio signal into an optical signal with a wavelength corresponding to the frequency used to transmit that radio signal.

[0027] Figure 3 shows an example where time is used as an identifier for the radio section. The first radio base station 3a determines which of the second radio base stations 4a, 4b, or 4c is the destination of the uplink radio signal received from the radio terminal 2, based on the time it was received. The first radio base station 3a converts the received radio signal into an optical signal of the wavelength corresponding to the determined destination. The reception timing, such as the slot in which the radio signal was received, may be used as the reception time of the radio signal. The second radio base station 4 converts the downlink radio signal into an optical signal of the wavelength corresponding to the time the radio signal was transmitted. The transmission timing, such as the slot in which the radio signal is transmitted, may be used as the transmission time of the radio signal.

[0028] Furthermore, the identifier for a wireless section may be any physical characteristic that allows the wireless section to be identified, not limited to frequency or time.

[0029] Figure 4 is a functional block diagram of the first radio base station 3 and the second radio base station 4. The first radio base station 3 and the second radio base station 4 are connected via a gateway 5 and an optical fiber 6, but the gateway 5 is omitted in Figure 4.

[0030] The first wireless base station 3 comprises an antenna 31, a front end 32, and a TRx33. The antenna 31 transmits and receives wireless signals with the wireless terminal 2. The front end 32 performs processing on the wireless signal as an electrical signal, such as bandwidth limiting, frequency conversion, and power amplification.

[0031] TRx33 performs E / O conversion, converting the wireless signal, which has been processed as an electrical signal by the front-end 32, into an optical signal, and outputs the converted optical signal to the optical fiber 6. TRx33 converts the wireless signal into an optical signal with a wavelength corresponding to the wireless section identifier notified by the front-end 32. TRx33 also receives the downstream optical signal transmitted through the optical fiber 6 and performs O / E conversion, converting the input optical signal into a wireless signal as an electrical signal. TRx33 outputs the converted wireless signal and the wavelength information of the optical signal to the front-end 32. The front-end 32 processes the wireless signal input from TRx33, such as bandwidth limiting, frequency conversion, and power amplification, so that it is transmitted using the wireless section corresponding to the wavelength of the optical signal, and then transmits it wirelessly from the antenna 31.

[0032] The second wireless base station 4 comprises a TRx41 and a digital signal processing unit 42. The TRx41 performs O / E conversion, converting the uplink optical signal into a wireless signal as an electrical signal, and outputs the converted wireless signal to the digital signal processing unit 42. The TRx41 also performs E / O conversion, converting the downlink electrical signal into an optical signal, and outputs the converted optical signal to the gateway 5.

[0033] The digital signal processing unit 42 comprises a wireless signal processing unit 43 and a wireless access control unit 44. The wireless signal processing unit 43 modulates and demodulates wireless signals using digital signal processing. The wireless access control unit 44 performs logical access control of wireless signals using digital signal processing.

[0034] Figure 5 is an illustrative diagram showing the function of Gateway 5. Gateway 5 has the function of changing the transfer destination according to the wavelength. As a method of configuring Gateway 5, for example, it is possible to use a Photonic GW as shown in Reference 1.

[0035] (Reference 1) Tomoaki Yoshida, "Photonic Gateway and Optical Access Technology Supporting APN", NTT Technical Journal, February 2021 issue, Internet <URL: https: / / journal.ntt.co.jp / article / 10379>

[0036] The gateway 5 has a plurality of first input / output units 51, a plurality of second input / output units 52, and a setting unit 53. The first input / output units 51 and the second input / output units 52 are each connected to an optical fiber 6 or optical transmission line 7. The plurality of first input / output units 51 may be connected to the same optical fiber 6 or optical transmission line 7, and the plurality of second input / output units 52 may be connected to the same optical fiber 6 or optical transmission line 7. In that case, a wavelength multiplexer / demultiplexer may be provided between the optical fiber 6 or optical transmission line 7 and the plurality of first input / output units 51 or the plurality of second input / output units 52.

[0037] The gateway 5 outputs optical signals input from the first input / output unit 51 from one of the second input / output units 52 corresponding to the wavelength of the optical signal, and outputs optical signals input from the second input / output unit 52 from one of the first input / output units 51 corresponding to the wavelength of the optical signal, according to the configured transfer path. The setting unit 53 sets the connection between the first input / output unit 51 and the second input / output unit 52 and the wavelength of the optical signal used for that connection in the first input / output unit and the second input / output unit 52. By changing this setting, the transfer destination of the optical signal according to the wavelength can be changed. Note that the setting unit 53 may be provided in other devices connected to the gateway 5.

[0038] Using the configurations shown in Figures 4 and 5, we will explain the process when the wireless terminal 2a-2 shown in Figure 1 transmits and receives wireless signals.

[0039] The front end 32 of the first radio base station 3a performs processing such as bandwidth limiting, frequency conversion, and power amplification on the uplink radio signal from the radio terminal 2a-2 received by the antenna 31. The front end 32 outputs the processed radio signal and information about the radio section identifier of the radio signal to TRx33. TRx33 converts the electrical signal input from the front end 32 into an optical signal of wavelength β according to the radio section identifier. TRx33 outputs the converted optical signal to the optical fiber 6. Alternatively, instead of outputting information about the radio section identifier, the front end 32 may instruct TRx33 to convert to wavelength β corresponding to the radio section identifier. Alternatively, the front end 32 may select the second radio base station 4b according to the radio section identifier and instruct TRx33 to convert to wavelength β corresponding to the selected second radio base station 4b.

[0040] The first input / output unit 51 of gateway 5a receives the optical signal from the first wireless base station 3a transmitted through the optical fiber 6. The first input / output unit 51 outputs the input optical signal to the second input / output unit 52 according to the wavelength β. The second input / output unit 52 outputs the optical signal received from the first input / output unit 51 to the optical fiber 6 between it and gateway 5b.

[0041] The first input / output unit 51 of gateway 5b receives the optical signal from gateway 5a transmitted through the optical fiber 6. The first input / output unit 51 outputs the input optical signal to the second input / output unit 52 according to the wavelength β. The second input / output unit 52 drops the optical signal input from the first input / output unit 51 to the second radio base station 4b. The TRx 41 of the second radio base station 4b converts the optical signal dropped by gateway 5b into a radio signal as an electrical signal. The radio signal processing unit 43 demodulates the radio signal.

[0042] Furthermore, the radio signal processing unit 43 of the second radio base station 4b generates a downlink radio signal destined for the radio terminal 2a-2. The radio signal processing unit 43 obtains the radio section identifier of the radio terminal 2a-2 from the radio access control unit 44 and outputs the generated radio signal and the radio section identifier to TRx41. TRx41 converts the radio signal input from the radio signal processing unit 43 from an electrical signal to an optical signal of wavelength β according to the radio section identifier. Alternatively, instead of outputting the radio section identifier, the radio signal processing unit 43 may instruct TRx33 to convert to wavelength β corresponding to the radio section identifier. Alternatively, TRx41 may convert the radio signal to an optical signal of wavelength β corresponding to its own station. TRx41 outputs the converted optical signal to gateway 5b.

[0043] The second input / output unit 52 of gateway 5b receives an optical signal from the second wireless base station 4a. The second input / output unit 52 outputs the input optical signal to the first input / output unit 51 according to the wavelength β. The first input / output unit 51 outputs the optical signal received from the second input / output unit 52 to the optical fiber 6 between it and gateway 5a.

[0044] The second input / output unit 52 of gateway 5a receives the optical signal from gateway 5b transmitted through the optical fiber 6. The second input / output unit 52 outputs the input optical signal to the first input / output unit 51 according to the wavelength β. The first input / output unit 51 outputs the optical signal input from the second input / output unit 52 to the optical fiber 6 between it and the first wireless base station 3a.

[0045] The TRx33 of the first wireless base station 3a converts the optical signal from gateway 5a, transmitted through the optical fiber 6, into a wireless signal as an electrical signal. The TRx33 outputs the converted wireless signal and information about the wavelength β of the optical signal to the front end 32. The front end 32 processes the wireless signal input from the TRx33, performing bandwidth limiting, frequency conversion, power amplification, etc., to use the wireless section corresponding to wavelength β, and then transmits it wirelessly from antenna 31. Wireless terminals 2a-2 receive the wireless signal.

[0046] Figure 6 shows the signal transfer in the transmission system 1 after the configuration change. In Figure 6, the network connection configuration is changed so that the connection destination of the second radio base station 4b is changed from gateway 5b to gateway 5c. In this case, the setting unit 53 of gateway 5a sets the connection destination of the first input / output unit 51, which inputs and outputs an optical signal of wavelength β to the optical fiber 6 between it and the first radio base station 3a, from the second input / output unit 52, which inputs and outputs an optical signal of wavelength β to the optical fiber 6 between it and gateway 5b, to the second input / output unit 52, which inputs and outputs an optical signal of wavelength β to the optical fiber 6 between it and gateway 5c. In addition, the setting unit 53 of gateway 5c changes the settings so that the first input / output unit 51, which inputs and outputs an optical signal of wavelength β to the optical fiber 6 between it and gateway 5b, and the second input / output unit 52, which inputs and outputs an optical signal of wavelength β to the optical transmission path 7 between it and the second radio base station 4b are connected.

[0047] In this way, the setting unit 53 of each gateway 5 sets the correspondence between the wavelength of the optical signal and the transmission destination in the gateway 5 so that the second wireless base station 4 can select a gateway 5 that drops the optical signal of the wavelength corresponding to the wireless section to be processed.

[0048] The first radio base station 3a operates in the same manner as in Figure 1, converting the uplink radio signal received from the radio terminal 2a-2 into an optical signal of wavelength β and transmitting it to gateway 5a. The first input / output unit 51 of gateway 5a outputs the optical signal input from the first radio base station 3a to gateway 5c via a second input / output unit 52 corresponding to wavelength β. The first input / output unit 51 of gateway 5c drops the optical signal input from gateway 5a to the second radio base station 4b via a second input / output unit 52 corresponding to wavelength β. The second radio base station 4b converts the optical signal of wavelength β dropped by gateway 5c into an electrical signal and demodulates the radio signal from radio terminal 2a-2 that has been converted into an electrical signal.

[0049] The second radio base station 4b converts the downlink radio signal destined for the radio terminal 2a-2 into an optical signal of wavelength β and outputs the converted optical signal to gateway 5c. The second input / output unit 52 of gateway 5c outputs the optical signal input from the second radio base station 4b to gateway 5a via the first input / output unit 51 corresponding to wavelength β. The second input / output unit 52 of gateway 5a transfers the optical signal of wavelength β input from gateway 5c to the first radio base station 3a via the first input / output unit 51 corresponding to wavelength β. The first radio base station 3a converts the optical signal of wavelength β into a radio signal, as before the network connection configuration change, and transmits the converted radio signal to radio terminal 2a-2 via the radio section corresponding to wavelength β.

[0050] As described above, the transmission system 1 of this embodiment can select a gateway 5 that splits the optical signal to a second radio base station that converts the optical signal into an electrical signal in order to modulate and demodulate the digital signal, based on the identifier of the radio section. Furthermore, it is possible to change the gateway 5 that drops the radio signal transmitted and received by radio terminal 2a-2 without affecting the transmission of the radio signals transmitted and received by radio terminals 2a-1 and 2a-3.

[0051] According to the communication system of the embodiment described above, it is possible to construct a network that is physically segmented into wireless and wired sections. Therefore, the communication system of this embodiment can reduce processing delays and improve security compared to a logically segmented network.

[0052] According to the embodiment described above, the transmission system comprises one or more first communication devices that transmit and receive radio signals with a wireless terminal device, one or more second communication devices that transmit and receive optical signals with the first communication devices, and one or more transfer devices that transfer optical signals between the first communication devices and the second communication devices. For example, the first communication device corresponds to the first wireless base station 3 in the embodiment, the second communication device corresponds to the second wireless base station 4 in the embodiment, and the transfer device corresponds to the gateway 5 in the embodiment. The first communication device converts the radio signal transmitted and received with the wireless terminal device to an optical signal with a wavelength corresponding to the physical characteristics of the radio section transmitted by the radio signal. The transfer device receives the optical signal between the first communication device and the second communication device and transfers the input optical signal to the first communication device, the second communication device, or another transfer device corresponding to the wavelength of the optical signal. The second communication device transmits and receives an optical signal with the first communication device that has been transferred by one or more transfer devices and has a wavelength corresponding to the radio section that it is processing.

[0053] The transmission system may have a setting unit that sets the correspondence between wavelength and destination in the transfer device, so that the transfer device can be selected to drop an optical signal of a wavelength corresponding to the wireless section to be processed by the second communication device. In addition, the physical characteristics of the wireless section may be the frequency of the wireless signal, or the timing of the reception or transmission of the wireless signal.

[0054] While embodiments of this invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these embodiments and include designs and the like that do not depart from the spirit of this invention. [Explanation of Symbols]

[0055] 1. Transmission System 2a-1~2a-3, 2c wireless terminals 3, 3a, 3c First wireless base station 4, 4a, 4b, 4c Second wireless base station 5, 5a, 5b, 5c Gateways 6 Optical Fiber 7 Optical transmission path 31 Antenna 32 Front End 33 TRx 41 TRx 42 Digital signal processing unit 43 Wireless signal processing unit 44 Wireless Access Control Unit 51 First input / output section 52 Second input / output section 53 Settings Section

Claims

1. A wireless terminal device and one or more first communication devices that transmit and receive wireless signals, The first communication device and one or more second communication devices that transmit and receive optical signals, A transmission system comprising one or more transfer devices for transferring optical signals between the first communication device and the second communication device, The first communication device determines a second communication device to which the radio signal received from the wireless terminal device is transmitted according to the physical characteristics of the radio section, converts the received radio signal into an optical signal of a wavelength corresponding to the determined destination, and outputs it to the transfer device; and converts the optical signal received from the transfer device into a radio signal and transmits it to the wireless terminal device via a radio section corresponding to the wavelength of the received optical signal. The transfer device receives the optical signal between the first communication device and the second communication device, and transfers the input optical signal to the first communication device, the second communication device, or another transfer device, according to the wavelength of the optical signal. The second communication device transmits signals via one or more of the transfer devices and transmits and receives optical signals of the wavelength corresponding to the wireless section to be processed with the first communication device. Transmission system.

2. The transfer device has a setting unit for setting the correspondence between wavelength and transfer destination, so that the transfer device can be selected to drop optical signals of a wavelength corresponding to the wireless section to be processed by the second communication device. The transmission system according to claim 1.

3. The aforementioned feature quantity is the frequency of the wireless signal. The transmission system according to claim 1 or claim 2.

4. The aforementioned feature quantity is the timing of receiving or transmitting the wireless signal. The transmission system according to claim 1 or claim 2.

5. A wireless terminal device and one or more first communication devices that transmit and receive wireless signals, The first communication device and one or more second communication devices that transmit and receive optical signals, A transmission method in a transmission system comprising one or more transfer devices for transferring optical signals between the first communication device and the second communication device, The first communication device performs the following steps: determine a second communication device to which the radio signal received from the wireless terminal device is transmitted according to the physical characteristics of the wireless section, convert the received radio signal into an optical signal of a wavelength corresponding to the determined destination and output it to the transfer device; and convert the optical signal received from the transfer device into a radio signal and transmit it to the wireless terminal device via a wireless section corresponding to the wavelength of the received optical signal. The transfer device inputs an optical signal between the first communication device and the second communication device, and transfers the input optical signal to the first communication device, the second communication device, or another transfer device, according to the wavelength of the optical signal. The second communication device transmits data via one or more transfer devices, and the device transmits and receives an optical signal of the wavelength corresponding to the wireless section to be processed with the first communication device. A transmission method having

6. A wireless terminal device and one or more first communication devices that transmit and receive wireless signals, The first communication device and one or more second communication devices that transmit and receive optical signals, A transmission system comprising one or more transfer devices for transferring optical signals between the first communication device and the second communication device, The first communication device converts a radio signal transmitted and received with a wireless terminal device into an optical signal with a wavelength corresponding to the physical characteristics of the radio section transmitted by the radio signal. The transfer device receives the optical signal between the first communication device and the second communication device, and transfers the input optical signal to the first communication device, the second communication device, or another transfer device, according to the wavelength of the optical signal. The second communication device transmits data via one or more of the transfer devices and transmits and receives optical signals of the wavelength corresponding to the wireless section to be processed with the first communication device. The aforementioned feature quantity is the timing of receiving or transmitting the wireless signal. Transmission system.

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