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WO2018014565A1 - 用于发送和接收数据的方法及设备 - Google Patents

用于发送和接收数据的方法及设备 Download PDF

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Publication number
WO2018014565A1
WO2018014565A1 PCT/CN2017/076493 CN2017076493W WO2018014565A1 WO 2018014565 A1 WO2018014565 A1 WO 2018014565A1 CN 2017076493 W CN2017076493 W CN 2017076493W WO 2018014565 A1 WO2018014565 A1 WO 2018014565A1
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WIPO (PCT)
Prior art keywords
data
optical
laser
optical signal
signal
Prior art date
Application number
PCT/CN2017/076493
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English (en)
French (fr)
Inventor
高震森
Original Assignee
上海诺基亚贝尔股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 上海诺基亚贝尔股份有限公司 filed Critical 上海诺基亚贝尔股份有限公司
Priority to US16/319,418 priority Critical patent/US11128377B2/en
Priority to EP17830209.7A priority patent/EP3490175B1/en
Publication of WO2018014565A1 publication Critical patent/WO2018014565A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/27—Arrangements for networking
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/27—Arrangements for networking
    • H04B10/272—Star-type networks or tree-type networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/5167—Duo-binary; Alternative mark inversion; Phase shaped binary transmission
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/58—Compensation for non-linear transmitter output
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/03—WDM arrangements
    • H04J14/0305—WDM arrangements in end terminals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q11/0067—Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring

Definitions

  • Embodiments of the present disclosure relate to the field of optical communications, and more particularly to methods and apparatus for transmitting and receiving data implemented at an Optical Line Terminal (OLT) and an Optical Network Unit (ONU).
  • OLT Optical Line Terminal
  • ONU Optical Network Unit
  • N-PON2 Next Generation Passive Optical Network
  • TWDM-PON Time Division and Wavelength Division Multiplexed Passive Optical Network
  • NG-EPON Next Generation Ethernet Passive Optical Network
  • IEEE 802.3 Institute of Electrical and Electronics Engineers
  • embodiments of the present disclosure provide methods and apparatus for transmitting and receiving data implemented at an OLT and an ONU.
  • embodiments of the present disclosure provide a method for transmitting data implemented at an OLT.
  • the method includes encoding, at an OLT, data to be transmitted on a plurality of wavelength channels, and providing the encoded data to a corresponding laser as a modulation input to cause the laser to generate light representing the data a signal; multiplexing the optical signal; and equalizing the multiplexed optical signal for transmission over the optical transmission link lose.
  • inventions of the present disclosure also provide an apparatus for transmitting data implemented at an OLT.
  • the apparatus includes an encoder configured to encode data to be transmitted on a plurality of wavelength channels, and a signal generator configured to provide the encoded data to a corresponding laser as a modulation input to Causing the laser to generate an optical signal representative of the data; a multiplexer configured to multiplex the optical signal; and an equalizer configured to equalize the multiplexed optical signal for passage of light Transmission link transmission.
  • embodiments of the present disclosure provide a method implemented at an OLT for receiving data.
  • the method includes: at an OLT, equalizing an optical signal received from an optical transmission link; demultiplexing the equalized optical signal; converting the demultiplexed optical signal into an electrical signal; and the electrical signal Decoding and determining the data.
  • embodiments of the present disclosure also provide an apparatus implemented at an OLT for receiving data.
  • the apparatus includes an equalizer configured to equalize an optical signal received from an optical transmission link, a demultiplexer configured to demultiplex the equalized optical signal, and a photoelectric converter configured And for converting the demultiplexed optical signal into an electrical signal; and a decoder configured to decode the electrical signal to determine the data.
  • embodiments of the present disclosure provide a method for transmitting data implemented at an ONU.
  • the method includes: encoding, at an ONU, data to be transmitted; providing the encoded data to a laser as a modulation input to cause the laser to generate an optical signal representative of the data; and performing the optical signal Multiplexing for transmission over an optical transmission link.
  • inventions of the present disclosure also provide an apparatus for transmitting data implemented at an ONU.
  • the apparatus includes an encoder configured to encode data to be transmitted, and a signal generator configured to provide the encoded data to a laser as a modulation input to cause the laser to generate the representation data And an multiplexer configured to multiplex the optical signal for transmission over the optical transmission link.
  • embodiments of the present disclosure provide a method implemented at an ONU for receiving data.
  • the method includes: at an ONU, light received from an optical transmission link The signal is demultiplexed; an optical signal corresponding to the particular wavelength channel is selected from the demultiplexed optical signals; the selected optical signal is converted to an electrical signal; and the electrical signal is decoded to determine the data.
  • inventions of the present disclosure also provide an apparatus for receiving data implemented at an ONU.
  • the apparatus includes a demultiplexer configured to demultiplex an optical signal received from an optical transmission link, and a selector configured to select a corresponding wavelength channel from the demultiplexed optical signal An optical signal, configured to convert the selected optical signal into an electrical signal; and a decoder configured to decode the electrical signal to determine the data.
  • an NG-EPON system supporting a transmission rate of 100 Gb/s and above can be realized with low system cost and complexity.
  • FIG. 1 shows a schematic diagram of a network system in which embodiments of the present disclosure may be implemented
  • FIG. 2 shows a flowchart of a method for transmitting data implemented at an OLT, in accordance with an embodiment of the present disclosure
  • FIG. 3 illustrates a flow diagram of a method for receiving data implemented at an ONU in accordance with an embodiment of the present disclosure
  • FIG. 4 illustrates a flow diagram of a method for transmitting data implemented at an ONU, in accordance with an embodiment of the disclosure
  • FIG. 5 illustrates a flow diagram of a method for receiving data implemented at an OLT, in accordance with an embodiment of the present disclosure
  • FIG. 6 shows a schematic structural block diagram of an apparatus for transmitting data implemented at an OLT according to an embodiment of the present disclosure
  • FIG. 7 illustrates a schematic structural block diagram of an apparatus for receiving data implemented at an ONU according to an embodiment of the present disclosure
  • FIG. 8 shows a schematic structural block diagram of an apparatus for transmitting data implemented at an ONU according to an embodiment of the present disclosure
  • FIG. 9 shows a schematic structural block diagram of an apparatus for receiving data implemented at an OLT according to an embodiment of the present disclosure
  • FIG. 10 shows a schematic diagram of an exemplary implementation of an NG-EPON system in accordance with an embodiment of the present disclosure
  • FIG. 11 shows a schematic diagram of a cyclic AWG response, MZI, and spectral distribution of downstream and upstream wavelengths in accordance with an embodiment of the present disclosure
  • FIG. 12 shows a frequency spectrum diagram of a wavelength channel before and after equalization in accordance with an embodiment of the present disclosure
  • FIG. 13 shows a waveform diagram of a data signal of a particular wavelength channel in accordance with an embodiment of the present disclosure
  • FIG. 14 shows a schematic diagram of a corresponding eye diagram of a data signal for a particular wavelength channel, in accordance with an embodiment of the disclosure.
  • FIG. 1 shows a schematic diagram of a network system 100 in which embodiments of the present disclosure may be implemented.
  • system 100 access network
  • the OLT 110 can receive data to be transmitted from the core network, and modulate the data to be transmitted through a plurality of wavelength channels (for example, four wavelength channels are shown in the figure) onto the optical signal, and modulate The subsequent corresponding optical signals are multiplexed at the multiplexer (MUX), and then the downstream and upstream optical signals are wavelength division multiplexed at the wavelength division multiplexer/demultiplexer (WDM) to pass
  • the optical transmission link is sent to the ONU side.
  • the optical transmission link can include fiber optic line 130 and split/combiner 140.
  • the optical signal via the WDM is transmitted from the OLT side to the ONU side through the optical fiber line 130, and distributed to the respective ONU1-ONUn 120 through the splitter/combiner 140.
  • the ONU1-ONUn 120 each selects an optical signal of a specific wavelength and acquires data therefrom, and transmits the acquired data to a user terminal in the premises network.
  • the ONU1-ONUn 120 can each receive data to be transmitted from the premises network, modulate the data to be transmitted to an optical signal of a specific wavelength, and perform WDM for the uplink and downlink optical signals to pass through the optical transmission chain.
  • the road is sent to the OLT side.
  • the WDM optical signal can be combined with the optical signals of other ONUs through the splitter/combiner 140 for transmission to the OLT side through the optical fiber line 130.
  • the OLT 110 then retrieves the data from the received optical signal and transmits it to the core network for processing.
  • advanced optical modulation formats such as dual binary, quad-level pulse amplitude modulation (PAM-4) are also proposed for NG-EPON in some known schemes because these advanced optical modulation formats facilitate Mitigating the bandwidth requirements of electronic and optical components of NG-EPON.
  • PAM-4 quad-level pulse amplitude modulation
  • high-speed external modulation of 10 Gb/s or more is also used to generate a 25 Gb/s bit rate signal per wavelength channel.
  • DSP complex digital signal processing
  • FFE equalization algorithms
  • LMS equalization algorithms
  • LMS equalization algorithms
  • the basic idea of the present invention is to apply a direct modulation laser (DML) to the uplink or downlink transmission of data instead of an externally modulated laser.
  • DML direct modulation laser
  • embodiments of the present disclosure accordingly provide methods for transmitting and receiving data implemented at the OLT and ONU, respectively.
  • FIG. 2 shows a flow diagram of a method 200 for transmitting data implemented at an OLT, in accordance with an embodiment of the disclosure.
  • the method 200 can be implemented at the OLT 110 shown in FIG.
  • step 210 data to be transmitted on multiple wavelength channels is programmed. code.
  • This step can be implemented at any of the transmitters 1-4 at the OLT 110 shown in FIG.
  • data to be transmitted is transmitted using 4 wavelength channels, each of which achieves a transmission rate of 25 Gb/s.
  • embodiments of the present disclosure are not limited thereto, but may be applied to other suitable numbers of wavelength channels and other suitable transmission rates.
  • the data to be transmitted may be non-return to zero (NRZ) data.
  • the data to be transmitted may be encoded by any suitable encoding to make it suitable for transmission.
  • the data to be transmitted may be double binary coded.
  • the data to be transmitted can be converted to a duobinary format by electrical filtering, such as low pass filtering, of the data to be transmitted. Thereby, the receiver bandwidth of the ONU can be greatly saved.
  • electrical filtering such as low pass filtering
  • the data to be transmitted may be encoded using a four-level pulse amplitude modulation (PAM-4) approach.
  • PAM-4 pulse amplitude modulation
  • the encoded data is provided to a corresponding laser as a modulation input to cause the laser to generate an optical signal representative of the data.
  • This step can also be implemented at any of the transmitters 1-4 at the OLT 110 shown in FIG.
  • the laser can be any suitable laser known in the art or developed in the future.
  • the laser can be a broadband laser.
  • the laser can be a narrowband laser.
  • a low speed laser with a 3 dB bandwidth of 2.5 GHz or 10 GHz In the case of such a narrowband laser, a lower cost of the system can be achieved.
  • embodiments of the present disclosure are not limited thereto, and that lasers having any suitable 3 dB bandwidth known in the art or developed in the future may be employed.
  • a fixed wavelength laser can be used on the OLT side.
  • the wavelength of each laser needs to be accurately fabricated to independently generate the downstream wavelength aligned with the passband of the multiplexer component.
  • a wavelength tunable laser can be used.
  • a wavelength tunable laser with a heater which can have a small wavelength tuning range of 3 nm.
  • AVGs cyclic array wave Guide gratings
  • the bias current of the laser may be selected to be 3 to 5 times the threshold current of the laser, and the modulation current of the laser is selected to be slightly higher than the threshold current of the laser.
  • the selection of the bias current and the modulation current of the laser is not limited to the above embodiment, and those skilled in the art can adopt any other suitable manner as needed.
  • the laser in the case where the encoded data is supplied to the corresponding laser as a modulation input, by adjusting the bias current and the modulation current of the laser, the laser can directly generate an optical signal representing the data without the need for an external modulation method. That also requires an additional light modulator module. Therefore, system complexity can be reduced and system costs can be reduced accordingly.
  • the generated optical signals are multiplexed.
  • the step may include multiplexing the optical signal between the plurality of wavelength channels and wavelength division multiplexing between the uplink and the downlink, as shown in FIG. 1 at the OLT 110
  • the multiplexer (MUX) and the wavelength division multiplexing/demultiplexer (WDM) are shown.
  • the optical signal may be subjected to the aforementioned cyclic AWG multiplexing, and the optical signals multiplexed by the cyclic arrayed waveguide grating are wavelength division multiplexed.
  • the optical signal multiplexed by the cyclic arrayed waveguide grating may be amplified and wavelength-multiplexed by the amplified optical signal if the transmission power is not required.
  • the processing of these multiplexing is well known to those skilled in the art and will not be described again here to avoid obscuring the present invention.
  • the multiplexed optical signals are equalized for transmission over the optical transmission link.
  • the optical signal is generated by direct modulation.
  • the transmission performance of optical signals produced by direct modulation may not be ideal, resulting in distortion of the optical signal after transmission on a single mode fiber.
  • the multiplexed light may be prior to downstream transmission (eg, prior to fiber optic line 130 shown in FIG. 1) in accordance with embodiments of the present disclosure.
  • the signal is equalized for transmission over the optical transmission link.
  • optical equalizer based on a simple MZI can be implemented.
  • multiple downstream and upstream can be placed at the central office.
  • High-speed wavelength channels perform optical equalization and signal recovery intensively.
  • the cost of the optical equalizer is shared by all ONUs, so the cost per ONU can be kept very low while supporting high bit rate signal transmissions of up to 25 Gb/s without resorting to high speed and expensive external modulation.
  • EDC electronic dispersion compensation
  • the spectral response of the MZI can be designed such that its free spectral range is half of the wavelength channel spacing.
  • the free spectral range can be chosen to be 50 GHz. This makes it possible to perform equalization and recovery of optical signals more efficiently.
  • the wavelengths of the downstream and upstream signals are no longer accurately aligned to the peak frequency of each passband of the interferometer, but have a frequency red shift relative to these wavelength channels.
  • the frequency redshift can be selected to be one-third of the spectral range of the interferometer in order to efficiently perform multi-channel duplex optical equalization.
  • the equalized optical signal can then be transmitted over the optical transmission link.
  • an optical signal is transmitted from the OLT side to the ONU side via an optical transmission link including the optical fiber line 130 and the splitter/combiner 140 as shown in FIG.
  • FIG. 3 illustrates a method 300 for receiving data implemented at an ONU in accordance with an embodiment of the disclosure.
  • the method 300 can be implemented at any of the ONUs 1-ONUn 120 shown in FIG. 1, for example, at any of the receivers 1-n.
  • the optical signal received from the optical transmission link is demultiplexed.
  • This step can be implemented at a wavelength division multiplexing/demultiplexer (WDM) in the ONU1-ONUn 120 shown in FIG. 1.
  • WDM wavelength division multiplexing/demultiplexer
  • the ONU1-ONUn 120 can receive the multiplexed and equalized optical signal transmitted from the OLT 110 from the optical splitter 140 on the optical transmission link and demultiplex the optical signal.
  • this step can be implemented by a tunable filter.
  • a tunable filter is used to select the desired wavelength channel to be detected.
  • a small amount of wavelength tuning of the tunable filter is required to cover the four downstream wavelengths.
  • wavelength-tunable DML on the OLT side it is necessary to increase the wavelength tuning range of the tunable filter to effectively cover the four downstream wavelengths. It should be understood that the embodiments of the present disclosure do not limit this.
  • the selected optical signal is converted to an electrical signal.
  • This step can be carried out by means of a photodetector. The processing of this step is well known in the art and will not be repeated here, so as not to obscure the present invention.
  • the electrical signal is decoded to determine the data.
  • This step may be a decoding process corresponding to the encoding process described above in connection with step 210 shown in FIG. 2.
  • the electrical signal may be low pass filtered and the low pass filtered electrical signal decoded to determine the data.
  • the cutoff frequency of the low pass filter can be selected to be 0.25-0.3 times the bit rate.
  • the low signal can be achieved on the ONU side by introducing an additional low-pass filter or specifically designing a photodetector and a transimpedance amplifier (TIA) response. Filter processing. Thereby, the performance of the recovered signal can be further improved.
  • TIA transimpedance amplifier
  • the electrical equalization processing of the electrical signal and the related DSP processing are not required as in the prior art, and thus the receiver structure on the ONU side is greatly simplified. Increased cost effectiveness. In addition, the signal recovery performance can be easily improved by additional low-pass filtering.
  • FIG. 4 illustrates a method 400 for transmitting data implemented at an ONU in accordance with an embodiment of the disclosure.
  • the method can be implemented at any of the transmitters 1-n at the ONU1-ONUn 120 shown in FIG.
  • the data to be transmitted is encoded.
  • the processing of this step 410 is similar to the processing of step 210 shown in FIG. 2 above, and details are not described herein again.
  • the encoded data is provided to a laser as a modulation input to cause the laser
  • the device produces an optical signal representative of the data.
  • the processing of this step 420 is similar to the processing of step 220 shown in FIG. 2 above, and details are not described herein again.
  • the optical signals are multiplexed for transmission over the optical transmission link.
  • This step 430 can be implemented by a wavelength division multiplexing/demultiplexer (WDM) in the ONU1-ONUn 120 shown in FIG. 1 to perform wavelength division multiplexing on the uplink and downlink optical signals, and then via splitting/closing.
  • the optical device 140 is combined with the optical signals of other ONUs for transmission on the optical fiber line 130 to the OLT 110 side.
  • WDM wavelength division multiplexing/demultiplexer
  • the laser in a method 400 for transmitting data implemented at an ONU, is directly modulated by an electrical modulation signal such that the laser directly produces an optical signal representative of the data without the need for additional as in the external modulation method.
  • Light modulator module Therefore, the transmitter structure on the ONU side can be greatly simplified and the cost is reduced, thereby facilitating large-scale deployment of NG-EPON in the future while reducing the cost and complexity of the entire system.
  • FIG. 5 illustrates a method 500 for receiving data implemented at an OLT in accordance with an embodiment of the present disclosure.
  • the method 500 can be implemented at the OLT 110 shown in FIG. 1, for example, at any of the receivers 1-4.
  • the optical signals received from the optical transmission link are equalized.
  • the optical signal received by the OLT 110 from an optical transmission link, such as fiber optic line 130 is generated by direct modulation of the ONU side.
  • the optical signal produced by direct modulation is distorted after transmission on a single mode fiber.
  • the optical signal may be optically equalized after receiving the optical signal upstream to facilitate recovery of the optical signal after transmission through the direct modulated laser and the single mode fiber. It should be understood that this can be implemented using any suitable optical equalizer known in the art or developed in the future.
  • an optical equalizer based on a simple MZI can be implemented.
  • optical equalization and signal recovery can be performed centrally on the downstream and upstream multiple high speed wavelength channels at the central office.
  • the processing of this step 510 is similar to the step 240 described above in connection with FIG. Processing, no more details here.
  • the equalized optical signal is demultiplexed.
  • the step may include performing wave decomposition multiplexing between uplink and downlink on the equalized optical signal and demultiplexing between the plurality of wavelength channels, which may be as shown in FIG. Implemented at the Wavelength Division Multiplexing/Demultiplexer (WDM) and Demultiplexer (DEMUX) in the OLT 110.
  • WDM Wavelength Division Multiplexing/Demultiplexer
  • DEMUX Demultiplexer
  • the demultiplexing process of step 520 may correspond to the multiplexing process of step 230 previously described in connection with FIG.
  • the optical signal can be cyclically AWG demultiplexed.
  • the optically demultiplexed optical signal may be pre-amplified and the optically demultiplexed optical signal may be cyclically AWG demultiplexed if the transmission power is not required.
  • the processing of these demultiplexing is well known to those skilled in the art and will not be described here in order to avoid obscuring the present invention.
  • the demultiplexed optical signal is converted to an electrical signal for each wavelength channel.
  • This step can be carried out by means of a photodetector. The processing of this step is well known in the art and will not be repeated here, so as not to obscure the present invention.
  • the electrical signal is decoded to determine the data.
  • This step may be a decoding process corresponding to the encoding process described above in connection with step 310 shown in FIG.
  • the electrical signal may be low pass filtered and the low pass filtered electrical signal decoded to determine the data.
  • the cutoff frequency of the low pass filter can be selected to be 0.25-0.3 times the bit rate.
  • a low-pass filtering process on the optical signal can be achieved by introducing an additional low-pass filter or specifically designing the photodetector and the TIA response on the ONU side. Thereby, the performance of the recovered signal can be further improved.
  • optical equalization in the method 500 for receiving data implemented at the OLT, can be performed collectively on the OLT side for downlink and uplink signals without separately setting optical equalization at respective receivers on the OLT side.
  • Modules which reduce the complexity of the receiver structure.
  • this can also eliminate the need to provide an equalization module on the ONU side, thereby simplifying the structure of the ONU side transmitter and improving cost effectiveness.
  • the signal recovery performance can be easily improved by additional low-pass filtering.
  • this inventions may also provide corresponding devices implemented at the OLT and ONU. The details will be described below with reference to FIGS. 6 to 9.
  • FIG. 6 shows a schematic structural block diagram of an apparatus 600 for transmitting data implemented at an OLT according to an embodiment of the present disclosure. It should be understood that device 600 can be implemented on, for example, OLT 110 as shown in FIG. As shown in FIG. 6, device 600 can include an encoder 610, a signal generator 620, a multiplexer 630, and an equalizer 640.
  • Encoder 610 can be configured to encode data to be transmitted over multiple wavelength channels. In one embodiment, encoder 610 can be configured to double binary encode data by low pass filtering of the data.
  • Signal generator 620 can be configured to provide encoded data to a respective laser as a modulation input to cause the laser to generate an optical signal representative of the data.
  • the laser can be any suitable laser known in the art or developed in the future.
  • the laser can be a narrowband laser.
  • the bias current of the laser can be selected to be 3 to 5 times the threshold current of the laser, and the modulation current of the laser can be selected to be slightly higher than the threshold current of the laser.
  • Multiplexer 630 can be configured to multiplex optical signals.
  • multiplexer 630 can include (not shown): a first multiplexer configured to cyclically AWG multiplex optical signals; and a second multiplexer configured to The optical signals multiplexed by the cyclic AWG are wavelength division multiplexed.
  • device 600 may also include an amplifier (not shown) configured to amplify the optical signals multiplexed by the cyclic AWG.
  • the second multiplexer can be configured to wavelength division multiplex the amplified optical signal.
  • Equalizer 640 can be configured to equalize the multiplexed optical signals for transmission over the optical transmission link.
  • FIG. 7 shows a schematic structural block diagram of an apparatus 700 for receiving data implemented at an ONU, in accordance with an embodiment of the present disclosure. It should be understood that device 700 can be implemented on any of ONU1-ONUn 120, such as shown in FIG.
  • device 700 can include a demultiplexer 710, a selector 720, a photoelectric converter 730, and a decoder 740.
  • Demultiplexer 710 can be configured to transmit from the light The optical signal received by the transmission link is demultiplexed.
  • the selector 720 can be configured to select an optical signal corresponding to a particular wavelength channel from the demultiplexed optical signals.
  • the optoelectronic converter 730 can be configured to convert the selected optical signal into an electrical signal.
  • the decoder 740 can be configured to decode the electrical signals to determine the data.
  • device 700 may also include a (not shown) filter configured to low pass filter the electrical signal.
  • decoder 740 can be configured to decode the low pass filtered electrical signal to determine the data.
  • FIG. 8 shows a schematic structural block diagram of an apparatus 800 for transmitting data implemented at an ONU, in accordance with an embodiment of the present disclosure. It should be understood that device 800 can be implemented on any of ONU1-ONUn 120, such as shown in FIG.
  • device 800 can include an encoder 810, a signal generator 820, and a multiplexer 830.
  • Encoder 810 can be configured to encode the data to be transmitted.
  • encoder 810 can be configured to double binary encode the data by low pass filtering the data.
  • Signal generator 820 can be configured to provide encoded data to the laser as a modulation input to cause the laser to generate an optical signal representative of the data.
  • the laser can be any suitable laser known in the art or developed in the future.
  • the laser can be a narrowband laser.
  • the bias current of the laser can be selected to be 3 to 5 times the threshold current of the laser, and the modulation current of the laser can be selected to be slightly higher than the threshold current of the laser.
  • Multiplexer 830 can be configured to multiplex optical signals for transmission over an optical transmission link.
  • FIG. 9 shows a schematic structural block diagram of an apparatus 900 for receiving data implemented at an OLT, in accordance with an embodiment of the present disclosure. It should be understood that device 900 can be implemented on, for example, OLT 110 as shown in FIG.
  • device 900 can include equalizer 910, demultiplexer 920, optoelectronic converter 930, and decoder 940.
  • Equalizer 910 can be configured to equalize optical signals received from the optical transmission link.
  • Demultiplexer 920 can be configured to demultiplex the equalized optical signals.
  • the optoelectronic converter 930 can be configured to convert the demultiplexed optical signal into an electrical signal.
  • Decoder 940 can be configured to decode electrical signals To determine the data.
  • device 900 may also include a (not shown) filter configured to low pass filter the electrical signal.
  • decoder 940 can be configured to decode the low pass filtered electrical signal.
  • each of the elements or units recited in device 600, device 700, device 800, and device 900, respectively, can be configured to implement the methods 200, 300, 400 described above with reference to Figures 2, 3, 4, and 5. And the corresponding steps in 500.
  • the operations and features of device 600, device 700, device 800, and device 900, and the elements or units contained therein, correspond to the operations and features described above in connection with Figures 2 through 5, and have the same effect, the specific details are not Let me repeat.
  • the elements, or units included in device 600, device 700, device 800, and device 900 can be implemented in a variety of manners, including hardware, firmware, software, or any combination thereof. In one embodiment, some or all of the elements, or devices in device 600, device 700, device 800, and device 900 may be implemented, at least in part, by one or more hardware devices or modules.
  • exemplary types of hardware logic components include Field Programmable Gate Array (FPGA), Application Specific Integrated Circuit (ASIC), Application Specific Standard (ASSP), System on Chip (SOC), Complex Programmable Logic Device (CPLD), and so on.
  • FPGA Field Programmable Gate Array
  • ASIC Application Specific Integrated Circuit
  • ASSP Application Specific Standard
  • SOC System on Chip
  • CPLD Complex Programmable Logic Device
  • one or more units may be implemented using software and/or firmware, such as machine-executable instructions stored on a storage medium.
  • certain units or modules may include sub-units or sub-modules.
  • an amplifier can include multiple amplifiers that perform the same or different functions, and the like.
  • these subunits or submodules are not shown in the figures.
  • FIG. 10 shows a schematic diagram of an exemplary implementation of an NG-EPON system 1000 in accordance with an embodiment of the disclosure.
  • the long channel transmits data to be transmitted, in which 25 Gb/s NRZ data is transmitted per wavelength channel, thereby achieving a polymerization symmetric capacity of 100 Gb/s.
  • 10(a) shows the entire system architecture of the NG-EPON system 1000 according to an embodiment of the present disclosure
  • FIG. 10(b) shows an exemplary implementation of the transmitter in the architecture
  • FIG. 10(c) shows the An exemplary implementation of a receiver in an architecture.
  • the system 1000 includes an OLT 1010, n ONUs 1020 1 - 1020 n (n is a positive integer), and an optical transmission link 1030.
  • the OLT 1010 includes four transmitters 1011 1 - 1011 4 , four receivers 1012 1 - 1012 4 , a cyclic AWG multiplexer 1013 , a cyclic AWG demultiplexer 1014 , a boost amplifier 1015 , a preamplifier 1016 , and a wavelength division A multiplexer/demultiplexer 1017 and an MZI-based equalizer 1018.
  • Each of the ONUs 1020 1 - 1020 n includes a transmitter 1021, a tunable filter 1022, a receiver 1023, and a wavelength division multiplexing/demultiplexer 1024.
  • Optical transmission link 1030 includes fiber optic line 1031 and beam splitter/combiner 1032.
  • the transmitters 1011 1 - 1011 4 and 1021 in Fig. 10(a) can have the same structure, only the structure of the transmitter 1021 is shown in Fig. 10(b), which will be described as an example.
  • the transmitter 1021 may include a low pass filter 1021-1, a bias current source 1021-2, and a 2.5G tunable DML 1021-3.
  • the receivers 1012 1 - 1012 4 and 1023 in Fig. 10 (a) can have the same structure, only the structure of the receiver 1023 is shown in Fig. 10 (c), which will be described as an example.
  • the receiver 1023 may include a photoelectric converter 1023-1, a low pass filter 1023-2, and a double binary decoder 1023-3.
  • each of the transmitters 1011 1 - 1011 4 at OLT 1010 performs a double binary encoding of the data to be transmitted and inputs the encoded data into a 2.5G tunable DML to produce light representing the data.
  • the signal is shown as ⁇ 1d - ⁇ 4d .
  • the cyclic AWG multiplexer 1013 cyclically AWG multiplexes the optical signals of the respective wavelength channels and amplifies them by the boosting amplifier 1015.
  • the upstream and downstream signals are wavelength division multiplexed via a wavelength division multiplexer/demultiplexer 1017 and equalized via the MZI based equalizer 1018 for transmission over the optical transmission link 1030.
  • the wavelength division multiplexer/demultiplexer 1024 demultiplexes the received optical signal and selects light for, for example, the wavelength channel ⁇ 1d via the tunable filter 1022
  • the signal is then input to the receiver 1023.
  • the optical signal is converted into an electrical signal by the photoelectric converter 1023-1, and the electrical signal is low-pass filtered by the low pass filter 1023-2, and then duobinary by the binary binary decoder 1023-3 Decode to determine the corresponding data.
  • the transmitter 1021 double-binds the data to be transmitted, and inputs the encoded data into 2.5.
  • G can tune the DML to produce an optical signal representative of the data, as indicated by ⁇ 1u .
  • the upstream and downstream signals are wavelength division multiplexed via a wavelength division multiplexer/demultiplexer 1024 for transmission over the optical transmission link 1030.
  • the received optical signal is equalized via the MZI-based equalizer 1018, the equalized optical signal is demultiplexed via the wavelength division multiplexing/demultiplexer 1017, and amplified by the preamplifier 1016.
  • the processing is performed and demultiplexed via the cyclic AWG demultiplexer 1014, and then input to the respective receivers 1012 1 - 1012 4 to decode the corresponding data in a manner similar to the receiver 1023 described above.
  • FIG. 11 shows a schematic 1100 of a cyclic AWG response, MZI, and spectral distribution of downstream and upstream wavelengths in accordance with an embodiment of the present disclosure.
  • (a) is for a DML with a fixed wavelength and (b) is for a case with a wavelength tunable DML.
  • the wavelengths of the downstream and upstream signals are no longer accurately aligned to the peak frequency of each passband of the interferometer, but have a frequency red shift relative to these wavelength channels.
  • the frequency redshift can be selected to be one-third of the spectral range of the interferometer in order to efficiently perform multi-channel duplex optical equalization.
  • the laser wavelength need not be adjusted to ⁇ 3u via wide-range wavelength tuning, Rather, it can be directly tuned into ⁇ 7u by heating with a relatively small amount of wavelength change so that it can be finally output from port 3 of the cyclic AWG to perform demultiplexing.
  • cyclic AWG multiplexing can also be applied for downstream and upstream signals. As can be seen from Fig.
  • the wavelength can be tuned to ⁇ 6d instead of ⁇ 2d , so it can also be mitigated. Wavelength tuning range.
  • FIG. 12 shows a frequency spectrum diagram 1200 of a wavelength channel before MZI and after MZI, in accordance with an embodiment of the disclosure.
  • four wavelength channels of 193.387 THz ( ⁇ 1u ), 193.487 THz ( ⁇ 2u ), 193.687 THz ( ⁇ 4u ), and 193.987 THz ( ⁇ 7u ) were used, as shown in Fig. 12(a).
  • These four wavelengths are generated by 2.5 GHz DML and modulated by 25 Gb/s dual binary data.
  • the bias current can be set to 80 mA and the modulation current can be set to 25 mA. In this case, there is no need to use any optical amplifier to compensate for the losses.
  • optical equalization is first performed using an MZI having a 50 GHz free spectral range (FSR).
  • FSR free spectral range
  • the peak wavelength of each passband of the interferometer is blue shifted by 17 GHz with respect to four channels.
  • all four channels are simultaneously reshaped, as shown in Figure 12(b). It can be seen that the spectrum of each channel is slightly cut off due to optical equalization. Due to this spectral reshaping, the distorted upstream 25Gb/s duobinary signal is regenerated.
  • FIG. 13 shows a waveform diagram 1300 of a data signal for a particular wavelength channel ⁇ 4u in accordance with an embodiment of the present disclosure.
  • 13(a) shows the waveform of the original double binary data
  • FIG. 13(b) shows the waveform after the transmission through the 20 km single mode fiber
  • FIG. 13(b) shows the waveform recovered after the optical equalization.
  • the severely distorted double binary data signal after the transmission of the 20 km single mode fiber is successfully recovered after optical equalization.
  • Figure 14 shows a schematic 1400 of a corresponding eye diagram of a data signal for a particular wavelength channel ⁇ 4u , in accordance with an embodiment of the present disclosure.
  • Figure 14 (a) shows an eye diagram with respect to the recovered signal without the use of an MZI based optical equalizer, where the eye diagram is fully closed and no double binary data is detected.
  • Figure 14 (b) shows an eye diagram of a signal after equalization with an optical equalizer and filtered via a 12.5 GHz low pass filter, wherein the eye pattern of the recovered signal is flared except that the upper portion is not fully flared.
  • Figure 14 (c) shows an eye diagram of a signal after equalization with an optical equalizer and filtered via a 6.75 GHz low pass filter, where the eye pattern of the recovered signal is fully open. It can be seen that by designing the photodetector and the TIA response to achieve a low pass filtering operation to present a cutoff frequency of 0.25-0.3 times the bit rate, the performance of the recovered signal can be ensured.
  • the various example embodiments of the present disclosure can be implemented in hardware or special purpose circuits, software, logic, or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which can be executed by a controller, microprocessor or other computing device.
  • firmware or software which can be executed by a controller, microprocessor or other computing device.
  • embodiments of the present disclosure may be described in the context of machine-executable instructions, such as in a program module that is executed in a device on a real or virtual processor of a target.
  • program modules include routines, programs, libraries, objects, classes, components, data structures, and the like that perform particular tasks or implement particular abstract data structures.
  • the functionality of the program modules may be combined or divided between the described program modules.
  • Machine-executable instructions for program modules can be executed within a local or distributed device. In a distributed device, program modules can be located in both local and remote storage media.
  • Computer program code for implementing the methods of the present disclosure can be written in one or more programming languages.
  • the computer program code can be provided to a general purpose computer, a special purpose computer or a processor of other programmable data processing apparatus such that the program code, when executed by a computer or other programmable data processing apparatus, causes a flowchart and/or block diagram.
  • the functions/operations specified in are implemented.
  • the program code can execute entirely on the computer, partly on the computer, as a stand-alone software package, partly on the computer and partly on the remote computer or entirely on the remote computer or server.
  • a machine-readable medium can be any tangible medium that contains or stores a program for or relating to an instruction execution system, apparatus, or device.
  • the machine readable medium can be a machine readable signal medium or a machine readable storage medium.
  • a machine-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More detailed examples of machine readable storage media include electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read only memory (ROM), erasable programmable read only Memory (EPROM or flash memory), optical storage device, magnetic storage device, or any suitable combination thereof.

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Abstract

本公开的实施例涉及用于发送和接收数据的方法及设备。用于发送数据的方法包括：在光线路终端处，对在多个波长通道上待发送的数据进行编码；将经编码的数据提供给相应的激光器作为调制输入，以使激光器产生表示数据的光信号；对光信号进行复用；以及对经复用的光信号进行均衡以便通过光传输链路传输。用于接收数据的方法包括：在光网络单元处，对从光传输链路接收的光信号进行解复用；从经解复用的光信号中选择与特定波长通道对应的光信号；将选择的光信号转换成电信号；以及对电信号进行解码以确定数据。根据本公开实施例的方案，可以使得在系统成本和复杂度较低的情况下实现支持100Gb/s及以上传输速率的NG-EPON系统。

Description

用于发送和接收数据的方法及设备 技术领域
本公开的实施例涉及光通信领域，更具体地涉及在光线路终端(OLT)和光网络单元(ONU)处实施的用于发送和接收数据的方法及设备。
背景技术
当前已经标准化的下一代无源光网络(NG-PON2)采用基于时分和波分复用的无源光网络(TWDM-PON)技术，其中利用四个波长支持40Gb/s的传输速率，每个波长支持10Gb/s的传输速率。在诸如高清视频、云计算之类的接入带宽应用的不断推动下，对宽带带宽的需求持续增长。在这种情况下，在未来的接入网络中需要将数据速率提升到每波长10Gb/s以上。
近来，电气和电子工程师协会(IEEE)802.3标准中的下一代以太网无源光网络(NG-EPON)备受业内关注，因为其旨在为终端用户的不能满足的带宽需求提供成本有效的方案。目前，作为用于NG-EPON的一种选择方案，标准工作组的讨论集中于各自具有25Gb/s传输速率的4个波长通道，以实现100Gb/s传输速率的NG-EPON。
发明内容
总体上，本公开的实施例提供在OLT和ONU处实施的用于发送和接收数据的方法及设备。
在一个方面，本公开的实施例提供一种在OLT处实施的用于发送数据的方法。该方法包括：在OLT处，对在多个波长通道上待发送的数据进行编码；将经编码的所述数据提供给相应的激光器作为调制输入，以使所述激光器产生表示所述数据的光信号；对所述光信号进行复用；以及对经复用的光信号进行均衡以便通过光传输链路传 输。
在此方面，本公开的实施例还提供一种在OLT处实施的用于发送数据的设备。该设备包括：编码器，被配置用于对在多个波长通道上待发送的数据进行编码；信号产生器，被配置用于将经编码的所述数据提供给相应的激光器作为调制输入，以使所述激光器产生表示所述数据的光信号；复用器，被配置用于对所述光信号进行复用；以及均衡器，被配置用于对经复用的光信号进行均衡以便通过光传输链路传输。
在另一方面，本公开的实施例提供一种在OLT处实施的用于接收数据的方法。该方法包括：在OLT处，对从光传输链路接收的光信号进行均衡；对经均衡的光信号进行解复用；将经解复用的光信号转换成电信号；对所述电信号进行解码以及以确定所述数据。
在此方面，本公开的实施例还提供一种在OLT处实施的用于接收数据的设备。该设备包括：均衡器，被配置用于对从光传输链路接收的光信号进行均衡；解复用器，被配置用于对经均衡的光信号进行解复用；光电转换器，被配置用于将经解复用的光信号转换成电信号；以及解码器，被配置用于对所述电信号进行解码以确定所述数据。
在另一方面，本公开的实施例提供一种在ONU处实施的用于发送数据的方法。该方法包括：在ONU处，对待发送的数据进行编码；将经编码的所述数据提供给激光器作为调制输入，以使所述激光器产生表示所述数据的光信号；以及对所述光信号进行复用以便通过光传输链路传输。
在此方面，本公开的实施例还提供一种在ONU处实施的用于发送数据的设备。该设备包括：编码器，被配置用于对待发送的数据进行编码；信号产生器，被配置用于将经编码的所述数据提供给激光器作为调制输入，以使所述激光器产生表示所述数据的光信号；以及复用器，被配置用于对所述光信号进行复用以便通过光传输链路传输。
在另一方面，本公开的实施例提供一种在ONU处实施的用于接收数据的方法。该方法包括：在ONU处，对从光传输链路接收的光 信号进行解复用；从经解复用的光信号中选择与特定波长通道对应的光信号；将选择的光信号转换成电信号；以及对所述电信号进行解码以确定所述数据。
在此方面，本公开的实施例还提供一种在ONU处实施的用于接收数据的设备。该设备包括：解复用器，被配置用于对从光传输链路接收的光信号进行解复用；选择器，被配置用于从经解复用的光信号中选择与特定波长通道对应的光信号；光电转换器，被配置用于将选择的光信号转换成电信号；以及解码器，被配置用于对所述的电信号进行解码以确定所述数据。
根据本公开实施例的方案，能够实现诸多有益的技术效果。例如，可以使得在系统成本和复杂度较低的情况下实现支持100Gb/s及以上传输速率的NG-EPON系统。
应当理解，发明内容部分中所描述的内容并非旨在限定本公开实施例的关键或重要特征，亦非用于限制本公开的范围。本公开的其它特征将通过以下的描述变得容易理解。
附图说明
结合附图并参考以下详细说明，本公开各实施例的上述和其他特征、优点及方面将变得更加明显。在附图中，相同或相似的附图标记表示相同或相似的元素，其中：
图1示出了本公开实施例可在其中实施的网络系统的示意图；
图2示出了根据本公开实施例的在OLT处实施的用于发送数据的方法的流程图；
图3示出了根据本公开实施例的在ONU处实施的用于接收数据的方法的流程图；
图4示出了根据本公开实施例的在ONU处实施的用于发送数据的方法的流程图；
图5示出了根据本公开实施例的在OLT处实施的用于接收数据的方法的流程图；
图6示出了根据本公开实施例的在OLT处实施的用于发送数据的设备的示意结构框图；
图7示出了根据本公开实施例的在ONU处实施的用于接收数据的设备的示意结构框图；
图8示出了根据本公开实施例的在ONU处实施的用于发送数据的设备的示意结构框图；
图9示出了根据本公开实施例的在OLT处实施的用于接收数据的设备的示意结构框图；
图10示出了根据本公开实施例的NG-EPON系统的示例性实现的示意图；
图11示出了根据本公开实施例的循环AWG响应、MZI以及下行和上行波长的频谱分布的示意图；
图12示出了根据本公开实施例的在均衡之前和在均衡之后的波长通道的频谱示意图；
图13示出了根据本公开实施例的特定波长通道的数据信号的波形示意图；以及
图14示出了根据本公开实施例的特定波长通道的数据信号的对应眼图的示意图。
具体实施方式
下面将参照附图更详细地描述本公开的实施例。虽然附图中示出了本公开的一些实施例，然而应当理解的是，本公开可以通过各种形式来实现，而且不应该被解释为限于这里阐述的实施例，相反提供这些实施例是为了更加透彻和完整地理解本公开。应当理解的是，本公开的附图及实施例仅用于示例性作用，并非用于限制本公开的保护范围。
在此使用的术语“包括”及其变形是开放性包括，即“包括但不限于”。术语“基于”是“至少部分地基于”。术语“一个实施例”表示“至少一个实施例”；术语“另一实施例”表示“至少一个另外的实施例”。其 他术语的相关定义将在下文描述中给出。
下面首先结合图1描述NG-EPON的基本架构。图1示出了本公开实施例可在其中实施的网络系统100的示意图。如图1所示，系统100(接入网)可以包括OLT 110、ONU1-ONUn(n为正整数)120、光纤线路130和分光/合光器140。在下行方向上，OLT 110可以接收来自核心网的待发送的数据，将待发送的数据通过多个波长通道(作为示例，在图中示出4个波长通道)调制到光信号上，并将调制后的相应光信号在多路复用器(MUX)处进行多路复用，然后将下行和上行的光信号在波分复用/解复用器(WDM)处进行波分复用以通过光传输链路发送到ONU侧。如图所示，光传输链路可以包括光纤线路130和分光/合光器140。经WDM的光信号通过光纤线路130从OLT侧被传送到ONU侧，并通过分光/合光器140分发到各个ONU1-ONUn 120。ONU1-ONUn 120各自选择特定波长的光信号并从中获取数据，并将获取到的数据传送给驻地网中的用户终端。在上行方向上，ONU1-ONUn 120各自可以接收来自驻地网的待发送的数据，将待发送的数据调制到特定波长的光信号上，并将上行和下行的光信号进行WDM以通过光传输链路发送到OLT侧。具体地，经WDM的光信号可以通过分光/合光器140与其它ONU的光信号合并到一起，以便通过光纤线路130传送到OLT侧。OLT 110然后从接收到的光信号中获取数据并传送给核心网进行处理。
在上述系统100的架构下，如前面提到的，IEEE 802.3标准工作组的讨论集中于各自具有25Gb/s传输速率的4个波长通道，以实现100Gb/s传输速率的NG-EPON。然而，在25Gb/s的传输速率下，使用商用的光学组件开发成本有效的光学收发器是一项极具挑战性的任务，特别是对于在ONU侧的上行方向尤为如此。在传统的吉比特无源光网络(GPON)/以太网无源光网络(EPON)中，ONU发射机是不可调谐的并且比特速率被限制为2.5Gb/s。因此不可能直接将GPON/EPON发射机用于NG-EPON。即使在TWDM-PON系统中，尽管ONU发射机是可调谐的，但其最大比特速率仍被限制为10Gb/s， 从而也不适用于NG-EPON。直观上而言，可以将高速的马赫-曾德(Mach-Zehnder)调制器(MZM)或电吸收调制器(EML)的外调制方法用于NG-EPON，但这些技术特别是在25Gb/s的数据速率下操作时是偏振敏感的或者是相当昂贵的，导致它们对于接入网应用不是成本有效的。此外，当用于接入网中的上行和下行的传输速率提高至25Gb/s时，引发的对应接收机和电子处理组件的成本也比低比特速率情况下明显增加。
另一方面，在一些已知的方案中还提出将诸如双二进制、四电平脉幅调制(PAM-4)之类的先进光学调制格式用于NG-EPON，因为这些先进光学调制格式有利于缓和NG-EPON的电子和光学组件的带宽要求。然而，在这些现有方案中，同样都是基于10Gb/s或以上的高速外调制来产生每波长通道25Gb/s比特速率信号。相应地，同样必须引入复杂的数字信号处理(DSP)和均衡算法(FFE、LMS或MLSE等)来补偿由于诸如光电检测器、外调制器和电放大器之类的电子或光学组件的不足带宽导致的信号降级。对于上行方向，由于ONU对成本非常敏感，使用昂贵的高速外调制方法和复杂的DSP使得ONU成本特别高，这会限制NG-EPON在将来的大规模部署。对于下行方向，尽管OLT成本可以由所有ONU分担，但在OLT侧使用4个并行的昂贵的25Gb/s高速发射机仍会增加系统成本和复杂度。
鉴于上述现有技术中的问题，本发明的基本构思就在于，代替外调制激光器，将直接调制激光器(DML)应用于数据的上行或下行发送。在DML的情况下，只需要向激光器提供电调制信号作为调制输入，而无需额外的光调制器之类的组件。由此可以显著降低系统成本和复杂度。基于该构思，本公开实施例相应地提供分别在OLT和ONU处实施的用于发送和接收数据的方法。下面结合图2-图5详细描述若干示例实现。
图2示出了根据本公开实施例的在OLT处实施的用于发送数据的方法200的流程图。该方法200可以在图1所示的OLT 110处实施。如图2所示，在步骤210，对在多个波长通道上待发送的数据进行编 码。该步骤可以在图1所示的OLT 110处的发射机1-4中的任意发射机处实施。作为示例，在本公开的实施例中，利用4个波长通道传输待发送的数据，其中每个波长通道实现25Gb/s的传输速率。但本公开实施例并不限于此，而是可以适用于其它合适数量的波长通道和其它合适的传输速率。
这里，待发送的数据可以为非归零(NRZ)数据。根据本公开的实施例，可以通过任意合适的编码方式来对待发送的数据进行编码，以使其适用于传输。在一个实施例中，可以对待发送的数据进行双二进制编码。例如，可以通过对待发送的数据进行电滤波，例如低通滤波，来将待发送的数据转化成双二进制格式。由此，可以大大节省ONU的接收机带宽。当然，本公开实施例并不限于此，而是可以采用本领域已知或未来开发的任意合适的编码方式。例如，在其它实施例中，可以采用四电平脉幅调制(PAM-4)方式来对待发送的数据进行编码。
在步骤220，将经编码的数据提供给相应的激光器作为调制输入，以使激光器产生表示数据的光信号。该步骤同样可以在图1所示的OLT 110处的发射机1-4中的任意发射机处实施。
根据本公开的实施例，激光器可以为本领域已知或未来开发的任意合适的激光器。在一个实施例中，激光器可以是宽带激光器。例如，3dB带宽为25GHz的高速激光器。在备选实施例中，激光器可以是窄带激光器。例如，3dB带宽为2.5GHz或10GHz的低速激光器。在这种窄带激光器的情况下，能够实现系统的更低成本。应理解到，本公开实施例并不限于此，而是可以采用本领域已知或未来开发的具有任意合适3dB带宽的激光器。
在其它实施例中，可以使用固定波长的激光器。在这种情况下，在OLT侧，每个激光器的波长都需要被精确地制造以独立地生成与多路复用组件的通带对准的下行波长。在备选实施例中，可以使用波长可调谐的激光器。例如具有加热器的波长可调谐激光器，其可以具有3nm的小波长调谐范围。在这种情况下，通过后续引入循环阵列波 导光栅(AWG)用于多路复用，可以大大缓和所需的波长制造精度，从而可以降低成本。
根据本公开的实施例，可以将激光器的偏置电流选择为激光器的阈值电流的3倍至5倍，并且将激光器的调制电流选择为略高于激光器的阈值电流。当然，激光器的偏置电流和调制电流的选取并不限于上述实施例，本领域技术人员可以根据需要采用任何合适的其它方式。由此，在将经编码的数据提供给相应的激光器作为调制输入的情况下，通过调整激光器的偏置电流和调制电流，可以使激光器直接产生表示数据的光信号，而无需像外调制方法中那样还需要额外的光调制器模块。因此，可以降低系统复杂度和相应降低系统成本。
在步骤230，对产生的光信号进行复用。根据本公开的实施例，该步骤可以包括对光信号进行多个波长通道之间的多路复用以及上行和下行之间的波分复用，如图1所示的OLT 110处的多路复用器(MUX)和波分复用/解复用器(WDM)所示。在一个实施例中，可以对光信号进行前面提及的循环AWG复用，并且对经循环阵列波导光栅复用的光信号进行波分复用。根据本公开的实施例，在传输功率达不到要求的情况下，可以放大所述经循环阵列波导光栅复用的光信号并对经放大的光信号进行波分复用。这些复用的处理是本领域技术人员熟知的，这里不再赘述，以免混淆本发明。
在步骤240，对经复用的光信号进行均衡以便通过光传输链路传输。如上所述，通过直接调制方式产生光信号。然而，直接调制产生的光信号的传输性能可能不够理想，导致在单模光纤上的传输之后光信号会失真。为了便于恢复在经过直接调制激光器和单模光纤传输之后的光信号，根据本公开的实施例，可以在下行发送之前(例如在图1所示的光纤线路130之前)，对经复用的光信号进行均衡以便通过光传输链路传输。
应理解到，可以采用本领域已知或未来开发的任意合适的光学均衡器来实施。例如，在一个实施例中，可以采用基于简单的MZI的光学均衡器来实施。以此方式，可以在中央局处对下行和上行的多个 高速波长通道集中地执行光学均衡和信号恢复。光学均衡器的成本由所有ONU分担，所以每个ONU的成本可以维持为非常低，同时可以支持高达25Gb/s的高比特速率信号传输，而无需借助于高速且昂贵的外调制。此外，也无需使用任何额外的光学色散补偿模块或电子色散补偿(EDC)。另外，也使得在接收侧(ONU侧)无需设置复杂的电均衡和DSP处理模块，使得接收侧的结构大大简化，成本降低。
根据本公开的一个实施例，可以将MZI的频谱响应设计为使得其自由频谱范围为波长通道间隔的一半。例如，对于下行和上行信号的100GHz通道间隔，可以将自由频谱范围选择为50GHz。这样可以更有效地执行均衡和光信号的恢复。在这种情况下，下行和上行信号的波长都不再精确地对准到干涉仪的每个通带的峰值频率，而是相对于这些波长通道具有频率红移。在一个实施例中，可以将频率红移选择为干涉仪的频谱范围的三分之一，以便于有效地执行多通道双工光学均衡。
继而，经均衡的光信号可以被通过光传输链路传输。例如，经由如图1所示的包括光纤线路130和分光/合光器140的光传输链路，将光信号从OLT侧发送到ONU侧。
至此描述了根据本公开实施例的在OLT处实施的用于发送数据的方法。相应地，本公开实施例还提供在ONU处实施的用于接收数据的方法。下面结合图3进行更详细说明。图3示出了根据本公开实施例的在ONU处实施的用于接收数据的方法300。该方法300可以在图1所示的ONU1-ONUn 120中的任意ONU处实施，例如可以在接收机1-n中的任意接收机处实施。
如图3所示，在步骤310，对从光传输链路接收的光信号进行解复用。该步骤可以在图1所示的ONU1-ONUn 120中的波分复用/解复用器(WDM)处实施。例如，ONU1-ONUn 120可以从光传输链路上的分光器140接收从OLT 110传送的经复用和均衡后的光信号，并对该光信号进行解复用。
在步骤320，从经解复用的光信号中选择与特定波长通道对应的 光信号。根据本公开的实施例，该步骤可以通过可调谐滤波器来实施。使用可调谐滤波器来选择期望检测到波长通道。在OLT侧使用固定波长的DML的情况下，需要对可调谐滤波器进行少量波长调谐来覆盖4个下行波长。而在OLT侧使用波长可调谐的DML的情况下，需要增加可调谐滤波器的波长调谐范围以便有效地覆盖4个下行波长。应理解到，本公开实施例对此并不作任何限制。
在步骤330，将选择的光信号转换成电信号。该步骤可以通过光电检测器实施。该步骤的处理在本领域中是熟知的，这里不再赘述，以免混淆本发明。
在步骤340，对电信号进行解码以确定数据。该步骤可以是与前面结合图2所示的步骤210中所述的编码处理相对应的解码处理。根据本公开的一个实施例，可以对电信号进行低通滤波，并对经低通滤波的电信号进行解码以确定数据。在一个实施例中，可以将低通滤波器的截止频率选择为比特速率的0.25-0.3倍。在这种情况下，针对经直接调制产生的光信号，在ONU侧通过引入额外的低通滤波器或者特别地设计光电探测器和跨阻放大器(TIA)响应，可以实现对该光信号的低通滤波处理。由此，可以进一步改善所恢复的信号的性能。
根据本公开的实施例，在ONU处实施的用于接收数据的方法300中，无需像现有方案中那样进行电信号的电均衡处理以及相关的DSP处理，因此ONU侧的接收机结构大大简化，提高了成本有效性。另外，通过额外的低通滤波处理，即可简单地实现信号恢复性能的改善。
上面结合图2和图3描述了根据本公开实施例的在下行方向上的数据收发方法。相应地，本公开实施例还提供在上行方向上的数据收发方法。下面结合图4和图5进行更详细说明。图4示出了根据本公开实施例的在ONU处实施的用于发送数据的方法400。该方法可在图1所示的ONU1-ONUn 120处的发射机1-n中的任意发射机处实施。
如图4所示，在步骤410，对待发送的数据进行编码。该步骤410的处理类似于前面结合图2所示的步骤210的处理，这里不再赘述。在步骤420，将经编码的数据提供给激光器作为调制输入，以使激光 器产生表示数据的光信号。该步骤420的处理类似于前面结合图2所示的步骤220的处理，这里不再赘述。在步骤430，对光信号进行复用以便通过光传输链路传输。该步骤430可以通过图1所示的ONU1-ONUn 120中的波分复用/解复用器(WDM)来实施，以对上行和下行的光信号进行波分复用，继而经由分光/合光器140与其它ONU的光信号合并在一起以在光纤线路130上传送到OLT 110侧。
根据本公开的实施例，在ONU处实施的用于发送数据的方法400中，通过电调制信号直接调制激光器，使得激光器直接产生表示数据的光信号，而无需像外调制方法中那样还需要额外的光调制器模块。因此，ONU侧的发射机结构可以大大简化且成本降低，从而可以便于NG-EPON在未来的大规模部署，同时降低整个系统的成本和复杂度。
至此描述了根据本公开实施例的在ONU处实施的用于发送数据的方法。相应地，本公开实施例还提供在OLT处实施的用于接收数据的方法。下面结合图5进行更详细描述。图5示出了根据本公开实施例的在OLT处实施的用于接收数据的方法500。该方法500可以在图1所示的OLT 110处实施，例如可以在接收机1-4中的任意接收机处实施。
如图5所示，在步骤510，对从光传输链路接收的光信号进行均衡。根据本公开的实施例，OLT 110从光传输链路例如光纤线路130接收的光信号是ONU侧经过直接调制方式产生的。如前面对图2的步骤240的描述中提及的，直接调制产生的光信号在单模光纤上的传输之后光信号会失真。根据本公开的实施例，可以在上行接收到光信号之后，就对光信号进行光学均衡，以便于恢复在经过直接调制激光器和单模光纤传输之后的光信号。应理解到，可以采用本领域已知或未来开发的任意合适的光学均衡器来实施。例如，在一个实施例中，可以采用基于简单的MZI的光学均衡器来实施。以此方式，可以在中央局处对下行和上行的多个高速波长通道集中地执行光学均衡和信号恢复。该步骤510的处理类似于前面结合图2描述的步骤240的 处理，这里不再赘述。
在步骤520，对经均衡的光信号进行解复用。根据本公开的实施例，该步骤可以包括对经均衡的光信号进行上行和下行之间的波分解复用以及多个波长通道之间的多路解复用，该步骤可以在图1所示的OLT 110中的波分复用/解复用器(WDM)以及多路解复用器(DEMUX)处实施。该步骤520的解复用处理可以与前面结合图2所述的步骤230的复用处理相对应。例如，在一个实施例中，可以对光信号进行循环AWG解复用。根据本公开的实施例，在传输功率达不到要求的情况下，可以预放大经波分解复用的光信号并对经波分解复用的光信号进行循环AWG解复用。这些解复用的处理是本领域技术人员熟知的，这里不再赘述，以免混淆本发明。
在步骤530，针对各个波长通道，将解复用的光信号转换成电信号。该步骤可以通过光电检测器实施。该步骤的处理在本领域中是熟知的，这里不再赘述，以免混淆本发明。
在步骤540，对电信号进行解码以确定数据。该步骤可以是与前面结合图3所示的步骤310中所述的编码处理相对应的解码处理。根据本公开的一个实施例，可以对电信号进行低通滤波，并对经低通滤波的电信号进行解码以确定数据。在一个实施例中，可以将低通滤波器的截止频率选择为比特速率的0.25-0.3倍。在这种情况下，针对经直接调制产生的光信号，在ONU侧通过引入额外的低通滤波器或者特别地设计光电探测器和TIA响应，可以实现对该光信号的低通滤波处理。由此，可以进一步改善所恢复的信号的性能。
根据本公开的实施例，在OLT处实施的用于接收数据的方法500中，可在OLT侧对下行和上行信号集中地执行光学均衡，而无需在OLT侧的各个接收机处分别设置光学均衡模块，从而使得接收机结构复杂度降低。另外，这样也可以使得在ONU侧无需设置均衡模块，从而ONU侧发射机结构简化，提高了成本有效性。另外，通过额外的低通滤波处理，即可简单地实现信号恢复性能的改善。
与上面描述的用于发送和接收数据的方法200-500相对应地，本 公开的实施例还可以提供在OLT和ONU处实施的相应设备。下面结合图6至图9进行详细说明。
图6示出了根据本公开实施例的在OLT处实施的用于发送数据的设备600的示意结构框图。应理解到，设备600可以实现在例如图1中所示的OLT 110上。如图6所示，设备600可以包括编码器610、信号产生器620、复用器630和均衡器640。
编码器610可以被配置用于对在多个波长通道上待发送的数据进行编码。在一个实施例中，编码器610可以被配置用于通过对数据的低通滤波来对数据进行双二进制编码。
信号产生器620可以被配置用于将经编码的数据提供给相应的激光器作为调制输入以使激光器产生表示数据的光信号。根据本公开的实施例，激光器可以为本领域已知或未来开发的任意合适的激光器。在一个实施例中，激光器可以为窄带激光器。在一个实施例中，激光器的偏置电流可以被选择为该激光器的阈值电流的3倍至5倍，并且激光器的调制电流可以被选择为略高于该激光器的阈值电流。
复用器630可以被配置用于对光信号进行复用。在一个实施例中，复用器630可以包括(未示出)：第一复用器，被配置用于对光信号进行循环AWG复用；以及第二复用器，被配置用于对经循环AWG复用的光信号进行波分复用。在一个实施例中，设备600还可以包括(未示出)放大器，该放大器被配置用于放大经循环AWG复用的光信号。在这种情况下，第二复用器可以被配置用于对经放大的光信号进行波分复用。
均衡器640可以被配置用于对经复用的光信号进行均衡以便通过光传输链路传输。
图7示出了根据本公开实施例的在ONU处实施的用于接收数据的设备700的示意结构框图。应理解到，设备700可以实现在例如图1中所示的ONU1-ONUn 120中的任意ONU上。
如图7所示，设备700可以包括解复用器710、选择器720、光电转换器730和解码器740。解复用器710可以被配置用于对从光传 输链路接收的光信号进行解复用。选择器720可以被配置用于从经解复用的光信号中选择与特定波长通道对应的光信号。光电转换器730可以被配置用于将选择的光信号转换成电信号。解码器740可以被配置用于对电信号进行解码以确定数据。
在一个实施例中，设备700还可以包括(未示出)滤波器，该滤波器被配置用于对电信号进行低通滤波。在这种情况下，解码器740可以被配置用于对经低通滤波的电信号进行解码以确定数据。
图8示出了根据本公开实施例的在ONU处实施的用于发送数据的设备800的示意结构框图。应理解到，设备800可以实现在例如图1中所示的ONU1-ONUn 120中的任意ONU上。
如图8所示，设备800可以包括编码器810、信号产生器820和复用器830。编码器810可以被配置用于对待发送的数据进行编码。在一个实施例中，编码器810可以被配置用于通过对数据的低通滤波来对所述数据进行双二进制编码。信号产生器820可以被配置用于将经编码的数据提供给激光器作为调制输入，以使激光器产生表示数据的光信号。根据本公开的实施例，激光器可以为本领域已知或未来开发的任意合适的激光器。在一个实施例中，激光器可以为窄带激光器。在一个实施例中，激光器的偏置电流可以被选择为该激光器的阈值电流的3倍至5倍，并且激光器的调制电流可以被选择为略高于该激光器的阈值电流。复用器830可以被配置用于对光信号进行复用以便通过光传输链路传输。
图9示出了根据本公开实施例的在OLT处实施的用于接收数据的设备900的示意结构框图。应理解到，设备900可以实现在例如图1中所示的OLT 110上。
如图9所示，设备900可以包括均衡器910、解复用器920、光电转换器930和解码器940。均衡器910可以被配置用于对从光传输链路接收的光信号进行均衡。解复用器920可以被配置用于对经均衡的光信号进行解复用。光电转换器930可以被配置用于将经解复用的光信号转换成电信号。解码器940可以被配置用于对电信号进行解码 以确定数据。
在一个实施例中，设备900还可以包括(未示出)滤波器，该滤波器被配置用于对电信号进行低通滤波。在这种情况下，解码器940可以被配置用于对经低通滤波的电信号进行解码。
应当理解，设备600、设备700、设备800和设备900中记载的每个元件或单元分别可被配置为实现上文参考图2、图3、图4和图5描述的方法200、300、400和500中的相应步骤。而且，设备600、设备700、设备800和设备900及其中包含的元件或单元的操作和特征都对应于上文结合图2至图5描述的操作和特征，并且具有同样的效果，具体细节不再赘述。
设备600、设备700、设备800和设备900中所包括的元件或单元可以利用各种方式来实现，包括硬件、固件、软件或其任意组合。在一个实施例中，设备600、设备700、设备800和设备900中的部分或者全部元件或单元可以至少部分地由一个或多个硬件设备或者模块来实现。作为示例而非限制，可以使用的示范类型的硬件逻辑组件包括现场可编程门阵列(FPGA)、专用集成电路(ASIC)、专用标准品(ASSP)、片上系统(SOC)、复杂可编程逻辑器件(CPLD)，等等。备选地，一个或多个单元可以使用软件和/或固件来实现，例如存储在存储介质上的机器可执行指令。
此外，还应理解，在上述设备中，某些单元或者模块可以包括子单元或者子模块。例如，一个放大器可以包括多个执行相同或不同功能的放大器，等等。为了清晰简洁起见，这些子单元或者子模块未在图中示出。
以上结合图2至图9对根据本公开实施例的分别在OLT和ONU处实施的用于发送和接收数据的方法和设备进行了描述。为便于理解，下面结合图10描述一种具体场景，应理解到，其仅为示例说明，并不用于进行任何限制。
图10示出了根据本公开实施例的NG-EPON系统1000的示例性实现的示意图。在本系统1000中，在上行和下行方向上利用四个波 长通道传送待发送的数据，其中每波长通道传输25Gb/s NRZ数据，从而实现100Gb/s的聚合对称容量。其中图10(a)示出根据本公开实施例的NG-EPON系统1000的整个系统架构，图10(b)示出该架构中的发射机的示例性实现，图10(c)示出该架构中的接收机的示例性实现。
如图10(a)所示，系统1000包括OLT 1010、n个ONU 10201-1020n(n为正整数)以及光传输链路1030。OLT 1010包括4个发射机10111-10114、4个接收机10121-10124、循环AWG复用器1013、循环AWG解复用器1014、升压放大器1015、前置放大器1016、波分复用/解复用器1017和基于MZI的均衡器1018。ONU 10201-1020n中的每一个都包括发射机1021、可调谐滤波器1022、接收机1023和波分复用/解复用器1024。光传输链路1030包括光纤线路1031和分光/合光器1032。
由于图10(a)中的发射机10111-10114和1021可以具有相同结构，因此在图10(b)中仅示出发射机1021的结构，以此为例进行说明。如图10(b)所示，发射机1021可以包括低通滤波器1021-1、偏置电流源1021-2和2.5G可调谐DML 1021-3。类似地，由于图10(a)中的接收机10121-10124和1023可以具有相同结构，因此在图10(c)中仅示出接收机1023的结构，以此为例进行说明。如图10(c)所示，接收机1023可以包括光电转换器1023-1、低通滤波器1023-2和双二进制解码器1023-3。
在上述系统1000中的下行方向上，OLT 1010处的各发射机10111-10114对待发送的数据进行双二进制编码，并将经编码的数据输入2.5G可调谐DML以产生表示该数据的光信号，如λ1d-λ4d所示。循环AWG复用器1013对各波长通道的光信号进行循环AWG复用，并由升压放大器1015对其放大。继而，上行和下行信号经由波分复用/解复用器1017进行波分复用，并经由基于MZI的均衡器1018进行均衡以在光传输链路1030上传输。在ONU 10201-1020n中的各ONU处，波分复用/解复用器1024对接收到的光信号进行解复用，并 经由可调谐滤波器1022选择针对例如波长通道λ1d的光信号，继而输入给接收机1023。在接收机1023中，由光电转换器1023-1将光信号转换成电信号，并由低通滤波器1023-2对电信号进行低通滤波，然后由双二进制解码器1023-3进行双二进制解码以确定对应数据。
在上述系统1000中的上行方向上，在ONU 10201-1020n中的各ONU处，以ONU 10201为例，发射机1021对待发送的数据进行双二进制编码，并将经编码的数据输入2.5G可调谐DML以产生表示该数据的光信号，如λ1u所示。经由波分复用/解复用器1024将上行和下行信号波分复用，以在光传输链路1030上传输。在OLT 1010处，经由基于MZI的均衡器1018对接收到的光信号进行均衡，经由波分复用/解复用器1017对经均衡的光信号进行解复用，经前置放大器1016进行放大处理，并经由循环AWG解复用器1014进行解复用，继而输入给各自接收机10121-10124以类似上述接收机1023的方式解码相应数据。
发明人对本公开实施例的性能进行了定量地验证，充分证明了其有益的技术效果。下面结合图11-图14进行详细说明。特别地，下面给出的实验数据是针对系统1000而获得的。但是本公开的其他实施例同样可以实现这些有益的效果。
图11示出了根据本公开实施例的循环AWG响应、MZI以及下行和上行波长的频谱分布的示意图1100。在示意图1100中，(a)是针对具有固定波长的DML的情况，(b)是针对具有波长可调谐的DML的情况。在(a)和(b)这两种情况下，下行和上行信号的波长都不再精确地对准到干涉仪的每个通带的峰值频率，而是相对于这些波长通道具有频率红移。在一个实施例中，可以将频率红移选择为干涉仪的频谱范围的三分之一，以便于有效地执行多通道双工光学均衡。
如前面提及的，通过在OLT侧引入循环AWG，也可以实现多路复用/解复用使得将DML的波长调谐范围大大缓和为3nm。与MZI不同，下行和上行波长应与AWG通道的传输峰值对准。如图11(a) 所示，对于具有固定波长的DML的情况，4个发射机的下行波长被适当地制造以具有从对应通带的峰值频率的频率偏移。在这种情况下，对于下行可以不应用循环AWG。关于上行信号，由于针对每个ONU采用可调谐DML，所以可以应用循环AWG来缓和波长调谐范围。
作为示例，对于具有在λ5u和λ6u之间的初始波长的ONU3而言，为了将其波长调整到目标通道3(Ch3)中，激光器波长无需经由大范围波长调谐被调整到λ3u中，而是可以通过加热来以相当少量的波长改变而直接调谐到λ7u中，使得可以最终从循环AWG的端口3输出以执行多路解复用。类似地，对于其中在OLT和ONU处都具有波长可调谐发射机的图11(b)，也可以针对下行和上行信号应用循环AWG复用。如从图4(b)可见，对于OLT侧，如果针对通道2(Ch2)的初始波长定位在λ5d和λ6d之间，则可以将波长调谐到λ6d而不是λ2d，所以也可以缓和波长调谐范围。
图12示出了根据本公开实施例的在MZI之前和MZI之后的波长通道的频谱示意图1200。在本例中，使用分别为193.387THz(λ1u)、193.487THz(λ2u)、193.687THz(λ4u)和193.987THz(λ7u)四个波长通道，如图12(a)所示。这四个波长由2.5GHz DML产生并由25Gb/s双二进制数据调制。假设激光器的阈值电流为21mA，偏置电流可以设置为80mA，且调制电流可以设置为25mA。在这种情况下，无需使用任何光放大器来补偿损耗。在经过20km单模光纤的传输之后，首先利用具有50GHz自由光谱范围(FSR)的MZI执行光学均衡。干涉仪的每个通带的峰值波长相对于四个通道被蓝移17GHz。在均衡之后，所有四个通道被同时重整形，如图12(b)所示。可见每个通道的频谱由于光学均衡而被略切除。由于该频谱重整形，失真的上行25Gb/s双二进制信号被再生。
图13示出了根据本公开实施例的特定波长通道λ4u的数据信号的波形示意图1300。其中，图13(a)示出原始双二进制数据的波形，图13(b)示出在经过20km单模光纤的传输之后的波形，图13(b) 示出在光学均衡之后被恢复的波形。可见，在经过20km单模光纤的传输之后的严重失真的双二进制数据信号经过光学均衡后被成功恢复。
图14示出了根据本公开实施例的特定波长通道λ4u的数据信号的对应眼图的示意图1400。图14(a)示出在未使用基于MZI的光学均衡器的情况下关于所恢复的信号的眼图，其中眼图是完全闭合的并且没有检测到双二进制数据。图14(b)示出在采用光学均衡器均衡并且经由12.5GHz低通滤波器滤波后的信号的眼图，其中除了上部没有完全张开之外，所恢复的信号的眼图是张开的。图14(c)示出在采用光学均衡器均衡并且经由6.75GHz低通滤波器滤波后的信号的眼图，其中所恢复的信号的眼图是完全张开的。由此可见，通过设计光电检测器和TIA响应来实现低通滤波操作以呈现作为比特速率的0.25-0.3倍的截止频率，可以确保所恢复的信号的性能。
至此已经结合各种实施例对本发明进行了详细说明。一般而言，本公开的各种示例实施例可以在硬件或专用电路、软件、逻辑，或其任何组合中实施。某些方面可以在硬件中实施，而其他方面可以在可以由控制器、微处理器或其他计算设备执行的固件或软件中实施。当本公开的实施例的各方面被图示或描述为框图、流程图或使用某些其他图形表示时，将理解此处描述的方框、装置、系统、技术或方法可以作为非限制性的示例在硬件、软件、固件、专用电路或逻辑、通用硬件或控制器或其他计算设备，或其某些组合中实施。
作为示例，本公开的实施例可以在机器可执行指令的上下文中被描述，机器可执行指令诸如包括在目标的真实或者虚拟处理器上的器件中执行的程序模块中。一般而言，程序模块包括例程、程序、库、对象、类、组件、数据结构等，其执行特定的任务或者实现特定的抽象数据结构。在各实施例中，程序模块的功能可以在所描述的程序模块之间合并或者分割。用于程序模块的机器可执行指令可以在本地或者分布式设备内执行。在分布式设备中，程序模块可以位于本地和远程存储介质二者中。
用于实现本公开的方法的计算机程序代码可以用一种或多种编程语言编写。这些计算机程序代码可以提供给通用计算机、专用计算机或其他可编程的数据处理装置的处理器，使得程序代码在被计算机或其他可编程的数据处理装置执行的时候，引起在流程图和/或框图中规定的功能/操作被实施。程序代码可以完全在计算机上、部分在计算机上、作为独立的软件包、部分在计算机上且部分在远程计算机上或完全在远程计算机或服务器上执行。
在本公开的上下文中，机器可读介质可以是包含或存储用于或有关于指令执行系统、装置或设备的程序的任何有形介质。机器可读介质可以是机器可读信号介质或机器可读存储介质。机器可读介质可以包括但不限于电子的、磁的、光学的、电磁的、红外的或半导体系统、装置或设备，或其任意合适的组合。机器可读存储介质的更详细示例包括带有一根或多根导线的电气连接、便携式计算机磁盘、硬盘、随机存储存取器(RAM)、只读存储器(ROM)、可擦除可编程只读存储器(EPROM或闪存)、光存储设备、磁存储设备，或其任意合适的组合。
另外，尽管操作以特定顺序被描绘，但这并不应该理解为要求此类操作以示出的特定顺序或以相继顺序完成，或者执行所有图示的操作以获取期望结果。在某些情况下，多任务或并行处理会是有益的。同样地，尽管上述讨论包含了某些特定的实施细节，但这并不应解释为限制任何发明或权利要求的范围，而应解释为对可以针对特定发明的特定实施例的描述。本说明书中在分开的实施例的上下文中描述的某些特征也可以整合实施在单个实施例中。反之，在单个实施例的上下文中描述的各种特征也可以分离地在多个实施例或在任意合适的子组合中实施。
尽管已经以特定于结构特征和/或方法动作的语言描述了主题，但是应当理解，所附权利要求中限定的主题并不限于上文描述的特定特征或动作。相反，上文描述的特定特征和动作是作为实现权利要求的示例形式而被公开的。

Claims (28)

  1. 一种用于发送数据的方法，包括：
    在光线路终端处，对在多个波长通道上待发送的数据进行编码；
    将经编码的所述数据提供给相应的激光器作为调制输入，以使所述激光器产生表示所述数据的光信号；
    对所述光信号进行复用；以及
    对经复用的光信号进行均衡以便通过光传输链路传输。
  2. 根据权利要求1所述的方法，其中对所述数据进行编码包括：
    通过对所述数据的低通滤波来对所述数据进行双二进制编码。
  3. 根据权利要求1所述的方法，其中所述激光器为窄带激光器。
  4. 根据权利要求3所述的方法，其中所述激光器的偏置电流被选择为所述激光器的阈值电流的3倍至5倍，并且所述激光器的调制电流被选择为略高于所述阈值电流。
  5. 根据权利要求1所述的方法，其中对所述光信号进行复用包括：
    对所述光信号进行循环阵列波导光栅复用；以及
    对经循环阵列波导光栅复用的光信号进行波分复用。
  6. 根据权利要求5所述的方法，其中对经循环阵列波导光栅复用的光信号进行波分复用包括：
    放大所述经循环阵列波导光栅复用的光信号；以及
    对经放大的光信号进行波分复用。
  7. 一种用于接收数据的方法，包括：
    在光网络单元处，对从光传输链路接收的光信号进行解复用；
    从经解复用的光信号中选择与特定波长通道对应的光信号；
    将选择的光信号转换成电信号；以及
    对所述电信号进行解码以确定所述数据。
  8. 根据权利要求7所述的方法，其中对所述电信号进行解码包括：
    对所述电信号进行低通滤波；以及
    对经低通滤波的电信号进行解码。
  9. 一种用于发送数据的方法，包括：
    在光网络单元处，对待发送的数据进行编码；
    将经编码的所述数据提供给激光器作为调制输入，以使所述激光器产生表示所述数据的光信号；以及
    对所述光信号进行复用以便通过光传输链路传输。
  10. 根据权利要求9所述的方法，其中对所述数据进行编码包括：
    通过对所述数据的低通滤波来对所述数据进行双二进制编码。
  11. 根据权利要求9所述的方法，其中所述激光器为窄带激光器。
  12. 根据权利要求11所述的方法，其中所述激光器的偏置电流被选择为所述激光器的阈值电流的3倍至5倍，并且所述激光器的调制电流被选择为略高于所述阈值电流。
  13. 一种用于接收数据的方法，包括：
    在光线路终端处，对从光传输链路接收的光信号进行均衡；
    对经均衡的光信号进行解复用；
    将经解复用的光信号转换成电信号；以及
    对所述电信号进行解码以确定所述数据。
  14. 根据权利要求13所述的方法，其中对所述电信号进行解码包括：
    对所述电信号进行低通滤波；以及
    对经低通滤波的电信号进行解码。
  15. 一种在光线路终端处实施的用于发送数据的设备，包括：
    编码器，被配置用于对在多个波长通道上待发送的数据进行编码；
    信号产生器，被配置用于将经编码的所述数据提供给相应的激光器作为调制输入，以使所述激光器产生表示所述数据的光信号；
    复用器，被配置用于对所述光信号进行复用；以及
    均衡器，被配置用于对经复用的光信号进行均衡以便通过光传输 链路传输。
  16. 根据权利要求15所述的设备，其中所述编码器被配置用于通过对所述数据的低通滤波来对所述数据进行双二进制编码。
  17. 根据权利要求15所述的设备，其中所述激光器为窄带激光器。
  18. 根据权利要求17所述的设备，其中所述激光器的偏置电流被选择为所述激光器的阈值电流的3倍至5倍，并且所述激光器的调制电流被选择为略高于所述阈值电流。
  19. 根据权利要求15所述的设备，其中所述复用器包括：
    第一复用器，被配置用于对所述光信号进行循环阵列波导光栅复用；以及
    第二复用器，被配置用于对经循环阵列波导光栅复用的光信号进行波分复用。
  20. 根据权利要求19所述的设备，还包括：放大器，被配置用于放大所述经循环阵列波导光栅复用的光信号，并且
    其中所述第二波分复用器被配置用于对经放大的光信号进行波分复用。
  21. 一种在光网络单元处实施的用于接收数据的设备，包括：
    解复用器，被配置用于对从光传输链路接收的光信号进行解复用；
    选择器，被配置用于从经解复用的光信号中选择与特定波长通道对应的光信号；
    光电转换器，被配置用于将选择的光信号转换成电信号；以及
    解码器，被配置用于对所述电信号进行解码以确定所述数据。
  22. 根据权利要求21所述的设备，还包括：滤波器，被配置用于对所述电信号进行低通滤波，并且
    其中所述解码器被配置用于对经低通滤波的电信号进行解码以确定所述数据。
  23. 一种在光网络单元处实施的用于发送数据的设备，包括：
    编码器，被配置用于对待发送的数据进行编码；
    信号产生器，被配置用于将经编码的所述数据提供给激光器作为调制输入，以使所述激光器产生表示所述数据的光信号；以及
    复用器，被配置用于对所述光信号进行复用以便通过光传输链路传输。
  24. 根据权利要求23所述的设备，其中所述编码器被配置用于通过对所述数据的低通滤波来对所述数据进行双二进制编码。
  25. 根据权利要求23所述的设备，其中所述激光器为窄带激光器。
  26. 根据权利要求25所述的设备，其中所述激光器的偏置电流被选择为所述激光器的阈值电流的3倍至5倍，并且所述激光器的调制电流被选择为略高于所述阈值电流。
  27. 一种在光线路终端处实施的用于接收数据的设备，包括：
    均衡器，被配置用于对从光传输链路接收的光信号进行均衡；
    解复用器，被配置用于对经均衡的光信号进行解复用；
    光电转换器，被配置用于将经解复用的光信号转换成电信号；以及
    解码器，被配置用于对所述电信号进行解码以确定所述数据。
  28. 根据权利要求27所述的设备，还包括：滤波器，被配置用于对所述电信号进行低通滤波，并且
    其中所述解码器被配置用于对经低通滤波的电信号进行解码。
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