JP2014014027A - Optical transceiver device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish a common wireless/wired (optical) high-speed communication technique in WDM-PON with reduced ONU cost to economically achieve a broadband ubiquitous network.SOLUTION: Each of a wired colorless ONU 101 and a wireless colorless ONU 102 includes: an O/E 13 for converting downlink signal light modulated by a frequency of a millimeter wave band into an electric signal; a common circuit 12 for converting the electric signal from the O/E 13 into a baseband signal to demodulate the downlink signal, and for transmitting uplink signal light modulated by an uplink signal; and a MUX/DMX 15 for demultiplexing downlink signal light input from an external terminal to output to the O/E 13, and for outputting the uplink signal light input from the common circuit 12 from an external terminal.

Description

  The present invention relates to optical and wireless transmission / reception technologies in a broadband access system.

  The speed of optical access systems has been remarkably increased, and in the past five years, the speed and bandwidth have increased by a factor of 100. Giga-class broadband services are now available in the GE-PON (Gigabit Ethernet (registered trademark) -Passive Optical Network) system. Provided economically with commercial introduction. In 2009, standardization of 10GE-PON was completed, and the next-generation PON for speeding up and widening beyond 10G is currently being implemented by Institute of Electrical and Electronics Engineers (FSAN) and Full Service Access (FSAN) Network etc. Discussed in a standards body. On the other hand, with regard to speeding up of wireless communication, a wireless LAN exceeding 100 Mbps is realized according to the IEEE 802.11n standard. Further, in the third generation mobile phone, a high speed downlink packet access (HSDPA) service of 7.2 Mbps is provided, and a LTE (Long Term Evolution) data communication service exceeding 10 Mbps is provided at the end of 2010. Furthermore, standardization and technology development for 4G are being promoted, and there are increasing expectations for the realization of next-generation high-speed services that exceed the giga class.

  In the future, wireless and wired to access large-capacity information such as 3D high-definition video and rich content without stress using new mobile terminals such as tablet PCs and smartphones and cloud computing, regardless of time and place. Broadband and ubiquitous networks that make use of (Hikari) are expected to play an important role.

  The next-generation PON technology approach for speeding up and widening beyond 10G includes the time division multiplexing (TDM: Time Division Multiplexing) method that performs user multiplexing on the time axis, which is a conventional extension technology, and the wavelength axis. There is a wavelength division multiplexing (WDM) system that performs user multiplexing, and the latter is called WDM-PON (Wavelength Division Multiplexing-Passive Optical Network).

  8 and 9 are configuration diagrams of the WDM-PON. FIG. 8 and FIG. 9 show the case where the splitter that connects a plurality of ONUs (Optical Network Units) 91 and OLTs (Optical Line Terminals) 92 is a wavelength splitter 93 and a power splitter 94, respectively. The ONU 91 includes a Tx (Transmitter) 82 that transmits a signal from a UNI (User Network Interface), an Rx (Receiver) 83 that receives a signal from the OLT 92, and a MUX / MUX / WUX that functions as a wavelength demultiplexing circuit for upstream and downstream signals. A DMX (Multiplexer / Demultiplexer) 81. The OLT 92 includes a plurality of different wavelengths in addition to a Tx 82 that transmits a signal from an SNI (Service Node Interface), an Rx 83 that receives a signal from the ONU 91, and a MUX / DMX 81 that functions as a wavelength demultiplexing circuit for upstream and downstream signals. MUX / DMX84T functioning as an upstream signal wavelength demultiplexing circuit and a MUX / DMX84R functioning as a wavelength demultiplexing circuit for a plurality of downstream signals of different wavelengths.

  Since the physical topology of WDM-PON is passive double star, the optical fiber that is the transmission path is shared by multiple users, but since different wavelengths are assigned to each user, the logical topology is single star. It has become. For this reason, it is possible to set and change the service independently for each user without affecting other users while sharing the transmission path with the user. For this reason, wireless and wired services can be set for each wavelength, and it has been attracting attention as a promising technology for constructing a broadband ubiquitous network exceeding the gigaclass utilizing the wireless and wired (light) described above.

  In WDM-PON, since a wavelength is fixedly assigned to each ONU, it is necessary to prepare ONUs having different transmission wavelengths for each user, and user convenience and maintenance operability are lacking. For this reason, in order to realize an “easy-to-use” ONU without being aware of the wavelength, it is necessary to make the ONU a single product and set the ONU transmission wavelength from the OLT side. This technology is called ONU's colorless technology.

  The colorless technology can be broadly divided into a self-light-emitting method and a wavelength supply method (see, for example, Non-Patent Document 1). As shown in FIG. 10, the former is equipped with a light source having wavelength selectivity on the ONU 91 itself. The transmission wavelength of each ONU 91 is set from the OLT 92 side at the time of opening. In the latter, as shown in FIG. 11, an optical modulator and an optical amplifier are mounted on the ONU 91, and upstream signal light is generated by modulating continuous light supplied from the light source on the OLT 92 side to each ONU. .

  Up until now, wireless and wired (optical) broadband technologies have progressed independently. However, in WDM-PON, a common high-speed communication technology for wireless and wired (optical) has been developed. By realizing the technology, it will be possible to economically realize a broadband ubiquitous network by producing a mass production effect. The present invention proposes a common high-speed communication technique for wireless and wired (light) in the self-luminous system.

The following proposals have been made as a fusion technology of wireless and wired (optical).
FIG. 12 is a configuration diagram of 10 Gbps transmission using 125 GHz band radio (for example, see Non-Patent Document 2). A radio frequency of 125 GHz is generated as a beat signal by extracting two continuous lights having different optical frequencies from an optical frequency comb generator 71 (Optical MMW signal generator) 71 using an optical filter.
FIG. 13 shows an example in which RoF (Radio on Fiber) technology is applied to OADM (Optical Add-Drop Multiplexer) (see, for example, Non-Patent Document 3). The light from each LD, which is a WDM light source, is directly modulated at different millimeter-wave band RF frequencies f _{1 to} f _N to perform FM modulation on the continuous light, and signals _{1 to data N} are superimposed on each continuous light by external modulation. After that, they are multiplexed by the WDM filter, FM-IM converted by the Mach-Zehnder filter, and transmitted to the node set for each wavelength using the OADM ring network. After receiving light by PD (Photo Diode), a desired beat frequency is extracted by BPF (Band-pass Filter) from each beat signal of the RF frequency component subjected to IM conversion, and transmitted as a radio signal.

K. Iwatuki, J. et al. Kani, H .; Suzuki, and M.M. Fujiwara, “Access and Metro Networks based on WDM Technologies”, IEEE J. et al. Lightwave Technol. , Vol. 22, no. 11, pp. 2623-2630 (2004) A. Hirata, et. al, “120-GHz-Band Millimeter-Wave Photonic Wireless Link for 10-Gb / s Data Transmission”, IEEE Trans. Microwave Theory and Tech. , Vol. 54, no. 5, pp. 1937-1944 (2006) A. M.M. J. et al. Koonen, et al. , “Perspectives of Radio over Fiber Technologies”, OFC / NFOEC 2008, OThP3 (2008) M.M. Fujiwara, et al, “Optical carrier supplied modular flattened optical multicarrier generation based on sinusoidal amplification and phase. J. et al. Lightwave Technol. , Vol. 21, no. 11, pp 2705-2714 (2003) T.A. Nagatsuma, “Continuous-wave terhertz spectroscopy system based on photodiodes”, PIERS Online, Vol. 6, no. 4, pp. 390-394 (2010)

  As shown in FIG. 12 and FIG. 13, since the configuration differs between wireless and wired (light), in the WDM-PON when accommodating wireless and wired (light), it is wireless or wired (light). The specifications of ONU differ depending on For this reason, it is difficult for the ONU used for WDM-PON when accommodating wireless and wired (light) to be economically produced by mass production.

  Therefore, the present invention aims to reduce the cost of ONUs by establishing a common high-speed communication technology in wireless and wired (optical) in WDM-PON, and to economically realize a broadband ubiquitous network. .

  An optical transceiver according to the present invention includes a photoelectric conversion circuit that converts a downstream signal light modulated at a millimeter-wave band frequency into an electrical signal, and converts the electrical signal from the photoelectric conversion circuit into a baseband signal for downstream transmission. The common circuit that demodulates the signal and transmits the upstream signal light modulated by the upstream signal, and the downstream signal light that is input from the external terminal are demultiplexed and output to the photoelectric conversion circuit. A wavelength demultiplexing circuit for outputting the input upstream signal light from the external terminal.

  In the optical transmission / reception apparatus according to the present invention, the electrical signal from the photoelectric conversion circuit is converted into a radio signal and transmitted, and further includes an antenna for receiving the radio signal, and the common circuit receives the radio signal received by the antenna. May be converted into a baseband signal to demodulate the downlink signal.

  In the optical transceiver of the present invention, the common circuit includes an optical frequency comb generation circuit that outputs continuous light having two or more wavelengths, and a wavelength separation circuit that separates the continuous light from the optical frequency comb generation circuit for each wavelength. An optical modulation circuit that generates upstream signal light by modulating at least one of the lights separated by the wavelength separation circuit with an upstream signal, and the upstream signal light from the light modulation circuit and the wavelength separation circuit A frequency that can combine a wavelength multiplexing circuit that combines one of the light and the light separated by the wavelength separation circuit, and convert an electrical signal from the photoelectric conversion circuit into a baseband signal A local light generation circuit that generates local light, a baseband conversion circuit that converts an electric signal from the photoelectric conversion circuit into a baseband signal using local light from the local light generation circuit, and A signal processing circuit for demodulating a baseband signal from the baseband converter circuit may comprise a.

  In the optical transmission / reception apparatus according to the present invention, an electrical signal from the photoelectric conversion circuit is converted into a radio signal and transmitted, and an antenna for receiving the radio signal is further provided, and the local light generation circuit further includes the wavelength separation Two of the lights separated by the circuit are combined to generate local light having a frequency capable of converting a radio signal received by the antenna into a baseband signal, and the baseband conversion circuit further includes the antenna The radio signal received may be converted into a baseband signal.

  According to the present invention, the present invention establishes a common high-speed communication technology in wireless and wired (optical) in WDM-PON, thereby reducing the cost of ONU and economically realizing a broadband ubiquitous network. Can do.

An example of the structure of the WDM-PON which accommodated the radio | wireless and the wire (light) in this embodiment is shown. The 1st example of the common part of WDM-PON is shown. An example of the signal in a common circuit is shown. The 2nd example of the common part of WDM-PON is shown. An example of wavelength arrangement is shown. 1 shows a first example of a baseband conversion circuit. 2 shows a second example of a baseband conversion circuit. The 1st example of a structure of WDM-PON is shown. The 2nd example of a structure of WDM-PON is shown. The 1st example of WDM-PON using a colorless ONU is shown. The 2nd example of WDM-PON using a colorless ONU is shown. An example of 10 Gbps transmission with 125 GHz band radio is shown. An example of the access network using RoF is shown.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

  In the communication system according to the present embodiment, the optical transmitters of the optical transceivers mounted on the OLT and the ONU each part of a plurality of optical carriers generated from an optical frequency comb (see, for example, Non-Patent Document 4). An RF signal is generated by modulation, and these are wavelength-multiplexed and transmitted. On the other hand, the optical receiving unit of the optical transceiver mounted on the OLT or ONU selects any two optical carriers from a plurality of optical carriers generated from the optical frequency comb and combines them to obtain a beat signal. Is used to convert the transmitted RF signal into a baseband signal, which is demodulated by digital signal processing.

  FIG. 1 is a configuration diagram of a WDM-PON including an optical transmission / reception apparatus according to this embodiment. The ONU 101 is a wired colorless ONU, and the ONU 102 is a wireless colorless ONU. The OLT 103, the ONU 101, and the ONU 102 include a common circuit 12. As described above, since the OLT 103, the ONU 101, and the ONU 102 include a common part (details will be described later in FIG. 2), the communication system according to the present embodiment can share components.

  The wired colorless ONU 101 and the wireless colorless ONU 102 are an O / E 13 that is a photoelectric converter, a MUX / DMX 15 that is a wavelength demultiplexing circuit for upstream or downstream signals of different wavelengths, and a wavelength tunable filter 14. (Not required when the splitter disposed outside the facility is a wavelength splitter) and S / P11 which is a parallel-serial conversion circuit. In addition to these, the wireless colorless ONU 102 includes an antenna 17. Downstream signal light from the splitter 104 is input to the external terminal of the MUX / DMX 15, and upstream signal light is output from the external terminal of the MUX / DMX 15 toward the splitter 104. In this configuration, the only difference between wireless and wired (light) is the presence / absence of the antenna 17, and a common optical transmitter / receiver can be used for wireless and wired (light). .

  FIG. 2 is an example of the configuration of the common circuit 12. The common circuit 12 includes an optical frequency comb generation circuit 41, an AWG (Arrayed Waveguide Grating) 42 as an optical filter, an optical modulation circuit 43, an optical multiplexing circuit 44, an optical multiplexing circuit 45 as a local light generation circuit, A baseband conversion circuit 46 and a signal processing circuit 47 are provided.

  For the transmission part, a plurality of optical carriers and one optical carrier are assigned to the AWG 42 from the optical carriers (see FIG. 3A) generated by the optical frequency comb generation circuit 41 (see, for example, Non-Patent Document 4). The former is modulated by the optical modulation circuit 43, and a plurality of modulated optical carriers and one optical carrier are multiplexed by the optical multiplexing circuit 44 to generate upstream signal light (see FIG. 3B). ).

  By setting the frequency interval f of the optical carrier equal to the symbol rate of the modulation signal of the optical modulation circuit 43, an OFDM signal can be created as upstream signal light. On the other hand, when the symbol rate of the modulation signal of the optical modulation circuit 43 is smaller than the frequency interval f of the optical carrier, the upstream signal light becomes a WDM signal. The configuration of the common circuit 12 in that case is shown in FIG.

  Downstream signal light guided from the transmission optical fiber through the MUX / DMX 15 and the wavelength tunable filter 14 (in the case of ONU) is converted into an optical OFDM signal by the O / E 13 and then wired. In the case of the less ONU 101, it is guided to the common circuit 12. Here, the O / E 13 is, for example, a UTC-PD (Uni-Traveling-Carrier Photodiode). In the case of the wireless colorless ONU 102, the RF OFDM signal is guided to the antenna 17 and transmitted to the space. The RF OFDM signal received by the antenna 17 is guided to the common circuit 12.

  The RF OFDM signal guided to the common circuit 12 is guided to the baseband conversion circuit 46, and in the case of wired, is output through the S / P11. In the case of radio, the output and input of S / P 11 are directly connected and input to the common circuit 12.

  The baseband conversion circuit 46 multiplexes two optical carriers (FIG. 3C) whose frequency is mf (m is a positive number) away from the optical carrier (frequency interval f) generated from the optical frequency comb generation circuit 41. By using the optical beat signal of the frequency mf obtained as a local signal LO, the RF OFDM signal is beat down to a baseband OFDM signal, and this is subjected to discrete Fourier transform (DFT: Discrete Fourier Transform) in the signal processing circuit 47. Is demodulated by digital signal processing.

  FIG. 5 shows an example of the wavelength arrangement of upstream signal light and downstream signal light in WDM-PON. By using a wavelength tunable light source as the seed light source of the optical frequency comb generating circuit 41, the common circuit 12 is made colorless, and a wavelength arrangement that can separate the upstream signal light and the downstream signal light by the MUX / DMX 15 is realized.

  FIG. 6 is a configuration example of the baseband conversion circuit 46. In FIG. 6, an optical beat signal that is the local signal light LO is converted into a beat signal having a frequency mf by a PD (Photo Diode) that is an optoelectric converter, and then an RF OFDM signal is converted into a baseband OFDM signal using a mixer 462. Beat down. In FIG. 7, the baseband OFDM signal can be obtained by simultaneously implementing the functions of the PD 461 and the mixer 462 using the UTC-PD 463 (see, for example, Non-Patent Document 5).

  The present invention can be applied to the information communication industry.

11: S / P
12: Common circuit 13: O / E
14: Wavelength tunable filters 15, 15T, 15R: MUX / DMX
16: E / O
17: Antenna 41: Optical frequency comb generation circuit 42, 48: AWG
43: Optical modulation circuit 44, 45: Optical coupler 46: Baseband conversion circuit 461: PD
462: Mixer 463: UTC-PD
47: Digital signal processing circuit 61: LD
62: Optical modulator 63: Wavelength multiplexing device 64: OADM control unit 65: MZI (Mach-Zehnder interferometer)
66: OADM (Optical add-drop multiplexer)
67: PD (Photo Diode)
68: BPF
69: Amplifier 71: Optical frequency comb 72: Baseband amplifier 73: Optical modulation circuit 74: Amplifier circuit 75 with PD, 76: Antenna 77: Reception circuit 78: Baseband amplifiers 81, 84, 84R, 84T: MUX / DMX
82: Tx
83: Rx
85: Tx / Rx
86: Light source 88: E / O
91: ONU
92: OLT
93: Wavelength splitter 94: Power splitter 95: OLT
101: Colorless ONU (wired)
102: Colorless ONU (wireless)
103: OLT
104: Splitter

Claims (4)

A photoelectric conversion circuit that converts downstream signal light modulated at a millimeter-wave frequency into an electrical signal;
A common circuit for demodulating a downstream signal by converting an electrical signal from the photoelectric conversion circuit into a baseband signal, and transmitting upstream signal light modulated by the upstream signal;
Demultiplexing the downstream signal light input from the external terminal and outputting it to the photoelectric conversion circuit, and the wavelength demultiplexing circuit for outputting the upstream signal light input from the common circuit from the external terminal;
An optical transceiver comprising: An electrical signal from the photoelectric conversion circuit is converted into a radio signal and transmitted, and further includes an antenna that receives the radio signal,
The optical transceiver according to claim 1, wherein the common circuit demodulates a downlink signal by converting a radio signal received by the antenna into a baseband signal. The common circuit is:
An optical frequency comb generating circuit that outputs continuous light of two or more wavelengths;
A wavelength separation circuit for separating continuous light from the optical frequency comb generation circuit for each wavelength;
An optical modulation circuit that generates upstream signal light by modulating at least one of the lights separated by the wavelength separation circuit with an upstream signal;
A wavelength multiplexing circuit that combines one of the upstream signal light from the light modulation circuit and the light separated by the wavelength separation circuit;
A local light generation circuit that combines two of the lights separated by the wavelength separation circuit and generates local light having a frequency capable of converting an electric signal from the photoelectric conversion circuit into a baseband signal;
A baseband conversion circuit that converts an electrical signal from the photoelectric conversion circuit into a baseband signal using local light from the local light generation circuit;
A signal processing circuit for demodulating a baseband signal from the baseband conversion circuit;
The optical transmission / reception apparatus according to claim 1, comprising: An electrical signal from the photoelectric conversion circuit is converted into a radio signal and transmitted, and further includes an antenna that receives the radio signal,
The local light generation circuit further combines two of the lights separated by the wavelength separation circuit to generate local light having a frequency capable of converting a radio signal received by the antenna into a baseband signal. ,
The optical transmission / reception apparatus according to claim 3, wherein the baseband conversion circuit further converts a radio signal received by the antenna into a baseband signal.

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