WO2011063728A1 - 无源光纤网络的信号处理方法、设备和系统 - Google Patents
无源光纤网络的信号处理方法、设备和系统 Download PDFInfo
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- WO2011063728A1 WO2011063728A1 PCT/CN2010/078942 CN2010078942W WO2011063728A1 WO 2011063728 A1 WO2011063728 A1 WO 2011063728A1 CN 2010078942 W CN2010078942 W CN 2010078942W WO 2011063728 A1 WO2011063728 A1 WO 2011063728A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
- H04L27/20—Modulator circuits; Transmitter circuits
- H04L27/2096—Arrangements for directly or externally modulating an optical carrier
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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
- H04B10/272—Star-type networks or tree-type networks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
- H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
- H04J14/0245—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for downstream transmission, e.g. optical line terminal [OLT] to ONU
- H04J14/0246—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for downstream transmission, e.g. optical line terminal [OLT] to ONU using one wavelength per ONU
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
- H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
- H04J14/0249—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU
- H04J14/025—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
- H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
- H04J14/0249—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU
- H04J14/0252—Sharing one wavelength for at least a group of ONUs, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0254—Optical medium access
- H04J14/0261—Optical medium access at the optical multiplex section layer
- H04J14/0265—Multiplex arrangements in bidirectional systems, e.g. interleaved allocation of wavelengths or allocation of wavelength groups
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0278—WDM optical network architectures
- H04J14/0282—WDM tree architectures
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2697—Multicarrier modulation systems in combination with other modulation techniques
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/0001—Arrangements for dividing the transmission path
- H04L5/0003—Two-dimensional division
- H04L5/0005—Time-frequency
- H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0298—Wavelength-division multiplex systems with sub-carrier multiplexing [SCM]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
- H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
- H04J2014/0253—Allocation of downstream wavelengths for upstream transmission
Definitions
- the embodiments of the present invention relate to the field of communications technologies, and in particular, to a signal processing method, device, and system for a passive optical network.
- FIG. 1 is a schematic structural diagram of an existing PON network. As shown in FIG. 1 , the PON network is composed of an optical line terminal (Optical Line Terminal, OLT for short), a passive optical distribution network (ODN), and multiple It consists of an Optical Network Unit (ONU).
- OLT optical Line Terminal
- ODN passive optical distribution network
- ONU Optical Network Unit
- PON has the advantages of optical fiber resource sharing, OLT port sharing, saving machine room investment, high equipment security, fast network construction speed, and low comprehensive network construction cost.
- PON technology is also evolving, from Passive Optical Network (APON) adopting Asynchronous Transfer Mode (abbreviation: ATM), and broadband passive optical network ( Broadband Passive Optical Network (BPON) evolved to Ethernet Passive Optical Network (EPON), Gigabit-Capable PON (GPON), wavelength division multiplexing (Wavelength Division Multiplexing, WDM for short) PON,
- APON Passive Optical Network
- BPON Broadband Passive Optical Network
- EPON Ethernet Passive Optical Network
- GPON Gigabit-Capable PON
- WDM Wavelength Division Multiplexing
- the transmission distance of PON is far more than 20Km, which is above 10Om, which can expand the coverage of PON, make OLT more concentrated, reduce the construction of central office (CO), and reduce the operation and maintenance of the entire access network.
- Cost all-optical technology can be used to achieve long-distance transmission of PON, because all-optical technology has better transparency and power consumption than photoelectric light (Optical-Electrical-Optical, abbreviation: OEO)
- OEO optical-Electrical-Optical, abbreviation: OEO
- the power consumption of the technology is low; the larger the split ratio of the PON, the better, and the more users that can be carried, the better.
- the current GPON split ratio is 1:32/64, and operators hope that the split ratio of PON can be increased to 1:256-1:1024.
- DeutscheInstitut DT hopes to use WDM-PON to achieve passive transmission above 50Km, can carry more than 1000 users, and provide each user with access bandwidth of up to IGbps, but the existing WDM PON does not reach this skills requirement.
- a WDM PON network may include multiple ONUs, one remote node (Re: RN) and one OLT2, and the remote node is passive.
- the WDM splitter and the WDM combiner are also included, and the OLT 2 also includes a WDM splitter and a WDM combiner.
- the working principle of WDM-PON is: OLT2 has multiple light sources that generate different wavelengths, for example: it can be a broadband light source generated by a filter, or can be generated by a separate color light source.
- the OLT2 modulates the service signal to the optical signal of different wavelengths, and transmits it to the downlink direction through the WDM combiner in the OLT2; and separates the optical signals of different wavelengths from the received optical signal by the WDM splitter of the RN5. , sent to different 0NU1, ONU1 recovers the business signal through photoelectric conversion.
- each ONU1 modulates the service signal to an optical signal of a different wavelength, and combines the WDM combiner in the RN5 to the single optical fiber 7 to transmit to the OLT, and then the OLT2 is separated by the WDM splitter. Each wavelength is converted into an electrical signal by the optical receiver (PD_1 to PD_n) to recover the service signal.
- WDM PON The advantage of WDM PON is that the optical signal is continuous, there is no need for the OLT to have a burst receiver, and the ONU does not need a burst transmitter. At the same time, each ONU has a single wavelength, which is highly confidential and suitable for large customer dedicated applications.
- the inventors have at least found that the existing WDM PON technology has at least the following problems in the process of implementing the present invention:
- WDM PON The number of wavelengths separated by WDM PON is limited. For example, there are currently 40 wavelengths available for C-band in WDM PON, which is difficult to increase. Each user is assigned an independent wavelength, and the number of users is limited. Because of WDM PON Each ONU has a unique wavelength, and the wavelength sharing is poor. Even if the wavelength of an ONU is not used, it cannot be used by other ONUs, resulting in waste of resources.
- FIG. 3 is a structural diagram of a conventional PON of a WDM and a TDM.
- TDMA Time Division Multiple Access
- multiple GPON downlink signals are modulated to the color wavelength by the OLT2 transmitter (LD_1 to LD_n), and after being combined by the WDM combiner, they are sent downstream to the remote node RN5, RN5.
- RN5 It is a passive node, but includes not only a WDM splitter and a WDM combiner, but also a power splitter (POWER SPLITER).
- the WDM splitter in the RN5 wavelength-separates the received optical signal to obtain a single-wavelength optical signal.
- the ONU1 may include a Reflective Semiconductor Optical Amplifier (RSOA), and the seed light source of the ONU1 may be a color light source transmitted by the transmitter of the OLT 2.
- RSOA Reflective Semiconductor Optical Amplifier
- the RSOA can remodulate the ONU1 and then superimpose it through the power splitter and WDM combiner, such as Arrayed Waveguide Grating (AWG), and then send it to the receiver of the OLT (PD1 to PDn).
- WDM combiner such as Arrayed Waveguide Grating (AWG)
- the WDM and TDM hybrid PON is TDMA+WDMA in the uplink direction. Its performance depends mainly on the inherent performance of TDMA. For example: logical distance, physical distance, etc., the transmission distance of WDM and TDM mixed PON is completely dependent on the adopted Physical transmission distance of TDM PON; Due to the burst frame structure of uplink TDMA, optical power compensation in the uplink direction is difficult to achieve, whether it is an Erbium-doped Optical Fiber Amplifier (EDFA) or a semiconductor optical amplifier ( Semiconductor Optical Amplifier (SOA) is difficult to implement and cannot be transmitted over long distances. In addition, TDMA is adopted for a single wavelength. In the uplink direction, the receiving end of the OLT needs a burst transmitter, and the ONU also needs to have a burst transmitter, and the network construction cost is high.
- EDFA Erbium-doped Optical Fiber Amplifier
- SOA Semiconductor Optical Amp
- Embodiments of the present invention provide a signal processing method, device, and system for a passive optical network, which can improve transmission distance and reduce network construction cost.
- the embodiment of the invention provides a signal processing method for a passive optical network, which includes:
- the multiplexed frequency division multiplexing modulation method is used to modulate the service signal after the baseband coding process to The allocated orthogonal frequency division multiple access subcarriers;
- the embodiment of the invention further provides a signal processing method for a passive optical network, comprising: performing analog-to-digital conversion on the received superposed optical domain orthogonal frequency division multiple access signal;
- An embodiment of the present invention further provides an optical network unit, including:
- An encoding module configured to perform baseband encoding processing on the received service signal
- An orthogonal frequency division multiplexing modulation module configured to modulate a signal after baseband coding processing onto an allocated orthogonal frequency division multiple access subcarrier by using a modulation method of orthogonal frequency division multiplexing
- a digital-to-analog conversion module configured to perform digital-to-analog conversion on the modulated orthogonal frequency division multiple access subcarriers to obtain an electrical domain orthogonal frequency division multiple access signal
- An optical modulation module configured to modulate the electrical domain orthogonal frequency division multiple access signal onto an uplink optical signal to obtain an optical domain orthogonal frequency division multiple access signal
- a sending module configured to send the optical domain orthogonal frequency division multiple access signal.
- the embodiment of the invention further provides an optical line terminal, including:
- An analog-to-digital conversion module configured to perform analog-to-digital conversion on the received superposed orthogonal frequency division multiple access signal
- an orthogonal frequency division multiplexing demodulation module configured to perform orthogonal frequency division on the signal after analog-to-digital conversion Demodulation
- the baseband decoding module is configured to perform a baseband decoding process on the signal after the orthogonal frequency division multiplexing demodulation, to obtain a service signal.
- An embodiment of the present invention further provides a passive optical network system, including: an optical line terminal, a remote node, and one or more optical network units;
- the optical network unit is configured to perform baseband coding processing on the received service signal; and modulate the signal after the baseband coding process into the allocated orthogonal frequency division multiple access subcarrier by using an orthogonal frequency division multiplexing modulation mode Up; performing digital-to-analog conversion on the modulated orthogonal frequency division multiple access subcarriers to obtain an electrical domain orthogonal frequency Dividing the multiple access signal; modulating the electrical domain orthogonal frequency division multiple access signal onto the uplink optical signal to obtain an optical domain orthogonal frequency division multiple access signal; and transmitting the optical domain orthogonal frequency division multiple access signal;
- the remote node is configured to superimpose the optical frequency orthogonal frequency division multiple access signals of the same wavelength transmitted by the received optical network units by using the power splitter, and then superimpose the superposed signals by the wavelength division multiplexing combiner
- the optical domain orthogonal frequency division multiple access signal is combined into a multi-wavelength optical signal and sent to the optical line terminal;
- the optical line terminal is configured to separate the received multi-wavelength optical signals to obtain optical signals of different wavelengths, where the optical signals of different wavelengths carry superposed optical domain orthogonal frequency division multiple access signals;
- the domain orthogonal frequency division multiple access signals are subjected to analog-to-digital conversion, orthogonal frequency division multiplexing demodulation, and baseband decoding processing, respectively, to obtain a service signal.
- a signal processing method, device, and system for a passive optical network provided by an embodiment of the present invention, modulating a received service signal onto an allocated orthogonal frequency division multiple access subcarrier, and modulating the orthogonal frequency division multiple access
- the electrical domain orthogonal frequency division multiple access signal obtained by digital-to-analog conversion of the sub-carrier is modulated onto the uplink optical signal, and then the continuous multi-wavelength optical signal can be obtained by superimposing the combined wave by the remote node, and the optical power compensation of the continuous signal is simple, and Supports long-distance transmission; and continuous signal transmission and reception equipment is less expensive than burst signals, thereby reducing network construction costs.
- FIG. 1 is a schematic structural diagram of an existing PON network
- FIG. 2 is a network architecture diagram of an existing WDM PON
- FIG. 3 is a schematic diagram of a frequency domain of an existing OFDM system according to an embodiment of the present invention
- FIG. 5 is a schematic diagram of another frequency domain of an OFDM system according to an embodiment of the present invention
- FIG. 7a is a schematic structural diagram of an application in an embodiment of a passive optical network system according to the present invention
- FIG. 7b is a schematic structural diagram of another application in an embodiment of a passive optical network system according to the present invention
- FIG. 9 is a schematic structural view of an embodiment of an optical line terminal according to the present invention
- 10 is a flowchart of a first embodiment of a signal processing method for a passive optical network according to the present invention
- FIG. 11 is a flowchart of a second embodiment of a signal processing method for a passive optical network according to the present invention
- FIG. 12b is a schematic diagram of a method for superimposing OFDMA subcarriers on the same wavelength in a third embodiment of a signal processing method for a passive optical network according to the present invention.
- Orthogonal Frequency Division Multiplexing (OFDM) technology is part of Frequency Division Multiplexing (FDM) technology, which is a kind of frequency between adjacent frequencies in a single channel.
- FDM Frequency Division Multiplexing
- subcarriers may have overlapping portions in order to maximize the efficiency of the spectrum.
- overlapping adjacent channels interfere with each other, but in OFDM systems, subcarriers are precisely orthogonal, allowing for overlap without interference. Therefore, the OFDM system can maximize the efficiency of the spectrum without causing adjacent channel interference.
- FIG. 4 is a schematic diagram of a frequency domain of an OFDM system according to an embodiment of the present invention.
- each of the individual channels C may include seven subcarriers S.
- the transmission rate of the channel increases as the channel bandwidth increases, and the OFDM system allows higher data throughput than the conventional FDM system.
- Subcarrier overlap in an OFDM communication system can make more efficient use of spectrum resources. Since the power maximum point of each subcarrier directly corresponds to the minimum point of adjacent channel power, these subcarriers may partially overlap without interfering with each other.
- FIG. 5 is a schematic diagram of another frequency domain of an OFDM system according to an embodiment of the present invention. As shown in FIG.
- each subcarrier of an OFDM system is represented by different peak points, and the peak point of each subcarrier directly corresponds to other channels. Zero crossing.
- Modern OFDM systems use digital signal processing technology. The generation and reception of each subcarrier are performed by digital signal processing algorithms. Inverse Fast Fourier Transform (IFFT) / Fast Fourier Crypt (Fast Fourier) Transform, referred to as FFT), simplifies the structure of the system. In order to improve the spectrum utilization, the spectrums on each subcarrier overlap each other, but these spectra satisfy the orthogonality throughout the symbol period, thereby ensuring that the receiving end can recover the signal without distortion.
- IFFT Inverse Fast Fourier Transform
- FFT Fast Fourier Crypt
- the OFDM modulation process is also an IFFT or Inverse Discrete Fourier Transform (IDFT) operation process, and the OFDM demodulation process is also an FFT or discrete Fourier.
- IDFT Inverse Discrete Fourier Transform
- DFT Discrete Fourier Transform
- the passive optical network system includes: an optical line terminal 61, a remote node 62, and one or more optical network units 63; 63, configured to perform baseband encoding processing on the received service signal; modulate the baseband encoding process onto the allocated orthogonal frequency division multiple access subcarrier by using an orthogonal frequency division multiplexing modulation method; The Orthogonal Frequency Division Multiple Access subcarriers are subjected to digital-to-analog conversion to obtain an electrical domain orthogonal frequency division multiple access signal; and the electrical domain orthogonal frequency division multiple access signal is modulated onto the uplink optical signal to obtain an optical domain orthogonality. a frequency division multiple access signal; transmitting the optical domain orthogonal frequency division multiple access signal;
- the remote node 62 is configured to superimpose the received optical domain orthogonal frequency division multiple access signals of the same wavelength transmitted by the respective optical network units by using the power splitter, and then superimposing the superposed light by the wavelength division multiplexing combiner
- the domain orthogonal frequency division multiple access signal is combined into a multi-wavelength optical signal and sent to the optical line terminal 61;
- the optical line terminal 61 is configured to separate the received multi-wavelength optical signals to obtain optical signals of different wavelengths, where the optical signals of different wavelengths carry the superposed optical domain orthogonal frequency division multiple access signals;
- the orthogonal frequency division multiple access signals are subjected to analog-to-digital conversion, orthogonal frequency division multiplexing demodulation, and baseband decoding processing, respectively, to obtain a service signal.
- the optical line terminal 61 is further configured to perform baseband coding processing, orthogonal frequency division multiplexing modulation, and modulation on the allocated orthogonal frequency division multiple access subcarriers on the received service signal; Performing digital-to-analog conversion on the frequency-division-multi-access subcarrier to obtain an electrical domain orthogonal frequency division multiple access signal, and modulating the electrical domain orthogonal frequency division multiple access signal onto the downlink optical signal to obtain optical domain orthogonal frequency division multiple access Signaling; combining optical wavelength orthogonal frequency division multiple access signals of different wavelengths into multi-wavelength optical signals and transmitting to the remote node 62;
- the remote node 62 is further configured to separate the received multi-wavelength optical signal into optical signals of different wavelengths by using a wavelength division multiplexing combiner, where the optical signals of different wavelengths carry optical domain orthogonal frequency division multiple access.
- a signal the orthogonal frequency division multiple access signal is sent to each optical network unit 63 by a power splitter; the optical network unit 63 is further configured to receive the optical domain orthogonal frequency division multiple access signal sent by the remote node 62,
- the optical domain orthogonal frequency division multiple access signal is subjected to analog-to-digital conversion, orthogonal frequency division multiplexing demodulation, and baseband decoding processing, respectively, to obtain a service signal.
- the signal is in an uplink direction from the optical network unit to the optical line terminal, and the signal is in a downlink direction from the optical path terminal to the optical network unit.
- FIG. 7a is a schematic structural diagram of an application in an embodiment of a passive optical network system according to the present invention.
- an optical network unit 63 receives the same.
- the service signals such as Fast Ethernet (FE) or Gigabit Ethernet (GE) signals are used in Multiple Quadrature Amplitude Modulation (MIM).
- FE Fast Ethernet
- GE Gigabit Ethernet
- MIM Multiple Quadrature Amplitude Modulation
- the service signal can be modulated onto the allocated (Orthogonal Frequency Division Multiple Access, OFDMA) subcarrier; then the OFDMA subcarrier is digitally modulated (Digital) /Analog, abbreviation: D/A) After conversion, it is modulated onto the optical signal by a semiconductor optical amplifier (RSOA).
- OFDMA Orthogonal Frequency Division Multiple Access
- the optical network unit 63 transmits the OFDMA signal to the remote node 62, superimposing the OFDMA signals of the plurality of optical line terminals 63 into one OFDMA frame through a power splitter 623 in the remote node 62, and then the waves in the remote node 62
- the division multiplexing combiner 622 can also combine the OFDMA frames of the plurality of power splitters into a multi-wavelength optical signal and transmit the signals to the optical line terminal 61.
- the optical line terminal 61 can separate the multi-wavelength signal into optical signals of different wavelengths through the WDM combiner, and then independently receive the corresponding signals through the respective receivers (PD_1 to PD_n).
- the optical signal of the wavelength; then the optical signal of different wavelengths is subjected to A/D conversion, FFT operation (OFDM demodulation) and MQAM decoding (baseband decoding) processing, and a service signal can be obtained.
- the uplink direction of the signal transmitted by the optical network unit ONU to the optical line terminal OLT adopts the OFDMA format, and in the downlink direction where the signal is sent by the OLT to the ONU, the OFDMA format can also be adopted, as shown in FIG. 7a, in the passive optical network.
- the optical line terminal 61 may perform MQAM coding and OFDM modulation (using IFFT operation) on the service signal to improve dispersion tolerance and improve bandwidth utilization, and modulate the service signal to the allocated signal.
- the transmitter On the OFDMA subcarrier, then the D/A conversion of the electrical signal on the OFDMA subcarrier is performed, and then modulated onto the optical signal; the transmitter (LD_1 to LD_n) transmits the optical signal to the WDM combiner, and the WDM combiner will Optical signals of different wavelengths are combined into a multi-wavelength optical signal.
- the multi-wavelength optical signal is then transmitted to the remote node 62 in the optical line termination.
- the wavelength separation multiplexer 621 of the remote node 62 separates the multi-wavelength signal into optical signals of different wavelengths, and the power of the remote node 62 is separated.
- the 623 separates the OFDMA frames carried on the optical signals of different wavelengths into the optical domain OFDMA signals of the same wavelength, and then the power splitter 623 can transmit the optical domain OFDMA signals of the same wavelength to the respective optical network units 63.
- the optical network unit 63 After receiving the optical domain OFDMA signal by the receiver PD, the optical network unit 63 performs A/D conversion, FFT operation, and MQAM decoding processing on the optical domain OFDMA signal, and then obtains a service signal. For example: When the downlink optical signal is a 10G GPON or EPON signal, the OLT first converts the bit rate into a character rate through MQAM encoding and IFFT operations.
- the lOGbps data rate is converted to 2.5 by 16QAM encoding.
- the character rate of GHz can be transmitted at a rate of 10 Gbps using a 2.5 GHz optical modulator (LD_1 to LD_n), reducing the requirement of the optical modulator speed and overcoming the dispersion effect at 10 G speed.
- each ONU receiver PD After receiving the optical signal, each ONU receiver PD converts the optical signal into a 2.5 GHz OFDM electrical signal, and then recovers the GPON or EPON downlink format through A/D conversion, FFT operation, MQAM decoding, and the like.
- the service signal sent to the ONU is filtered, for example: a data packet, and sent to the user terminal in a format such as FE or GE.
- the OLT may first allocate downlink orthogonal frequency division multiple access subcarriers according to traffic of the service signal, for example: OLT according to FE
- the traffic of the /GE port or the Virtual Local Area Network (VLAN) traffic allocates subcarriers in the downlink OFDMA frame to the ONU.
- the OLT modulates the FE/GE signal or the VLAN into the allocated OFDMA subcarriers by performing packet adaptation, MQAM coding, IFFT operation, D/A conversion, etc., to form a complete downlink OFDMA.
- the frame is transmitted to each ONU by the RN, and each ONU performs demodulation on the OFDMA subcarrier to recover the service signal in the FE/GE format.
- the Dynamic Bandwidth Allocation (DBA) module of the OLT may further allocate downlink orthogonal frequency division multiple access subcarriers to the OLT according to the traffic of the service signal and the service type. For example: When the OLT has Layer 3 monitoring capability, the DBA in the downstream direction OLT can allocate bandwidth according to the service type and traffic, and can define downlink OFDMA subcarriers with broadcast and multicast functions, and layer 3 multicast data streams. It is mapped to the corresponding anchor subcarrier, and the ONU having the authority in the same multicast group can receive and demodulate the service signal.
- DBA Dynamic Bandwidth Allocation
- the DBA allocates OFDMA subcarriers to the ONU according to the service type, which ensures that the high priority service preferentially uses the OFDMA subcarrier, which is more suitable for the transmission of real-time services such as video. Therefore, when the ONU has the layer 3 monitoring capability, the bandwidth allocation request may be generated according to the traffic of the port, and the bandwidth allocation request may be generated according to the service type and the traffic, for example, a voice over IP (VOICE OVER IP, VoIP for short) service, Real-time services such as video calls can directly generate high-priority bandwidth allocation requests to ensure timely delivery of real-time services.
- VOICE OVER IP Voice over IP
- FIG. 7b is a schematic structural diagram of another application in the embodiment of the passive optical network system according to the present invention.
- the uplink direction is used by the optical network unit 63 to transmit signals to the optical line terminal 61.
- the format of the OFDMA, but in the downlink direction in which the signal is transmitted from the optical line terminal 61 to the optical network unit 63, the signal processing method for the passive optical network may also adopt the format of GPON or EPON.
- the private line is provided to the large customer.
- the optical line terminal OLT directly modulates the GE or 10GE signal to the color wavelength, that is, the multi-wavelength optical signal, and sends it to the optical network unit ONU.
- the ONU monopolizes the color wavelength to ensure large The security and confidentiality requirements of the customer's leased line;
- the OLT can directly use the downstream format of the existing WDM and TDM hybrid PON to modulate to the color wavelength.
- the OLT directly passes the downlink format of at least one GPON, GEPON or 10GEPON through the light.
- the modulators (LD_1 to LD_n) are modulated to different color wavelengths.
- the OLT passes the wavelength division multiplexing combiner. For example: AWG combines 32 different color wavelengths and sends them to the ONU in the downstream direction. After the optical signal arrives at the RN, the WDM in the RN A splitter such as: AWG can filter out the 32 wavelengths.
- the number of power splitters can be set according to the number of common customers. If all the customers are ordinary users, the remote node 62, that is, the RN, can set the corresponding power splitter according to each wavelength; The ONU is not directly passed through the power splitter, and a large customer can use a single 0.
- the advantage of using the GPON or EPON format in the downlink direction is that the leased line service is transparent, compatible with the existing GPON and EPON downlink formats, and rationally utilizing logic design resources.
- the downlink capacity can also be expanded by wavelength. For each additional wavelength, Does not affect the operation of other wavelengths. Since the PON system is a continuous signal in the downlink direction, there is no technical problem in optical power compensation, and the EDFA can perform optical power compensation on the continuous signal to realize long-distance transmission.
- the OFDM modulation is applied to the service signal, and the multi-wavelength optical signal transmitted by the ONU in the uplink direction or the continuous signal transmitted by the OLT in the downlink direction is used, so that the uplink of the ONU is not required.
- the transmitting device does not need the uplink burst receiving device of the OLT, which can reduce the network construction cost; the continuous signal optical power compensation is easy to implement, and the long-distance transmission can be realized; and the power splitter in the RN can satisfy the ONU that needs to access the network.
- the number of the uplink optical signals reflected by the RSOA can make the uplink optical signals of all ONUs in the same group connected by one power splitter consistent, preventing the upstream OLT from receiving the beat noise.
- FIG. 8 is a schematic structural diagram of an embodiment of an optical network unit according to the present invention.
- the optical network unit includes: an encoding module 81, an orthogonal frequency division multiplexing modulation module 82, a digital-to-analog conversion module 83, and an optical modulation module 84. And sending module 85.
- the coding module 81 is configured to perform baseband coding processing on the received service signal, and the orthogonal frequency division multiplexing modulation module 82 is configured to modulate the signal after the baseband coding process by using a modulation method of orthogonal frequency division multiplexing. To the allocated orthogonal frequency division multiple access subcarriers;
- the digital-to-analog conversion module 83 is configured to perform digital-to-analog conversion on the modulated orthogonal frequency division multiple access subcarriers to obtain an electrical domain orthogonal frequency division multiple access signal;
- the optical modulation module 84 is configured to modulate the electrical domain orthogonal frequency division multiple access signal onto the uplink optical signal to obtain an optical domain orthogonal frequency division multiple access signal;
- the transmitting module 85 is configured to send the optical domain orthogonal frequency division multiple access signal.
- the optical modulation module 84 may be specifically configured to: generate an uplink optical signal by reflection according to the received downlink optical signal; and modulate the electrical domain orthogonal frequency division multiple access signal to the uplink optical signal to obtain an optical domain. Orthogonal frequency division multiple access signals.
- the optical network unit may further include:
- the receiving module 86 is configured to receive uplink bandwidth indication information, where the uplink bandwidth indication information includes the number and number of the allocated orthogonal frequency division multiple access subcarriers.
- the encoding module 81 may perform baseband encoding processing on the service signal, for example: using MQAM coding, orthogonal frequency
- the sub-multiplex modulation module 82 performs orthogonal frequency division multiplexing modulation on the baseband encoded service signal, for example: using an IFFT operation to modulate the baseband encoded processing service signal to the allocated orthogonal frequency division multiple access OFDMA subcarriers on.
- the number and number of allocated OFDMA subcarriers may be obtained from the received uplink payment indication information sent by the OLT.
- the optical modulation module 84 After the digital-to-analog conversion module 83 performs D/A conversion on the modulated OFDMA subcarrier, the optical modulation module 84 generates an uplink optical signal by using the downlink optical signal sent by the OLT according to the OLT. No., and the electrical signal on the OFDMA subcarrier is modulated onto the optical signal to obtain an optical domain OFDMA signal.
- the transmitting module of the optical network unit may send the optical domain OFDMA signal to the remote node, and superimpose the optical domain OFDMA signals of the same wavelength transmitted by the multiple optical network units by using one power splitter of the remote node,
- the superposed optical domain OFDMA signal can be an OFDMA frame, and the WDM combiner in the remote node combines the superposed optical domain OFDMA signals of the multiple power splitters into one multi-wavelength optical signal and sends the optical signal to the optical line. terminal.
- the orthogonal frequency division multiplexing modulation module may modulate the encoded service signal to the allocated orthogonal frequency division multiple access.
- the digital-to-analog conversion module performs analog-to-digital conversion on the modulated orthogonal frequency division multiple access subcarrier, and then modulates it onto the optical signal by the optical modulation module, and then sends it to the RN through the transmitting module, and superimposes the multiplexed wave through the RN.
- a continuous multi-wavelength optical signal can be obtained, and the optical power compensation method of the continuous multi-wavelength optical signal is simple, and can support long-distance transmission; and the transmission and reception equipment of the continuous signal is lower in cost than the burst signal, thereby reducing network construction. cost.
- FIG. 9 is a schematic structural diagram of an embodiment of an optical line terminal according to the present invention.
- the optical line terminal includes: an analog-to-digital conversion module 91, an orthogonal frequency division multiplexing demodulation module 92, and a baseband decoding module 93.
- the analog-to-digital conversion module 91 is configured to perform analog-to-digital conversion on the received superposed orthogonal frequency division multiple access signal;
- An orthogonal frequency division multiplexing demodulation module 92 configured to perform orthogonal frequency division multiplexing demodulation on the signal after the analog-to-digital conversion
- the baseband decoding module 93 is configured to perform a baseband decoding process on the signal after the orthogonal frequency division multiplexing demodulation, to obtain a service signal.
- the wavelength division multiplexing splitter can separate the multi-wavelength signal into overlapping orthogonals of different wavelengths.
- the frequency division multiple access signal is separately received by each of the receivers to independently superimpose the orthogonal frequency division multiple access signals of each wavelength, and then the analog to digital conversion module 91 performs the received superposed orthogonal frequency division multiple access signals.
- the orthogonal frequency division multiplexing demodulation module 92 performs orthogonal frequency division multiplexing demodulation on the analog-to-digital converted signal, for example: FFT operation; the baseband decoding module 93 demodulates the orthogonal frequency division multiplexing
- the signal is subjected to baseband decoding, for example: MQAM decoding processing, and a traffic signal can be obtained.
- the optical line terminal may further include: a bandwidth allocation module 94 and a sending module 95.
- the bandwidth allocation module 94 is configured to use the optical network according to the traffic and/or service type of the service signal.
- the element allocates an uplink orthogonal frequency division multiple access subcarrier;
- the sending module 95 is configured to send uplink bandwidth indication information to the optical network unit, where the uplink bandwidth indication information includes the number and number of the orthogonal frequency division multiple access subcarriers.
- the bandwidth allocation module 94 may allocate orthogonal frequency division multiple access subcarriers to the optical network unit according to the traffic and/or service type of the service signal, and may carry the bearer through the sending module 95.
- the number of allocated OFDMA subcarriers and the numbered uplink bandwidth indication information are sent to the corresponding optical network unit.
- the optical line terminal separates the received multi-wavelength optical signals to obtain superposed orthogonal frequency division multiple access signals of different wavelengths, and then performs analog-to-digital conversion and orthogonalization on the superposed orthogonal frequency division multiple access signals.
- the service signal can be obtained; since the multi-wavelength optical signal in this embodiment is a continuous signal formed by the multiplexing of orthogonal frequency division multiple access signals, the optical power compensation is performed, and the support is far. Distance transmission; continuous signal transmission and reception equipment is less expensive than burst signals, thereby reducing network construction costs.
- the signal processing method of the passive optical network includes:
- Step 101 Perform baseband coding processing on the received service signal.
- Step 102 modulate the service signal after the baseband coding process into the allocated orthogonal frequency division multiple access subcarriers by using an orthogonal frequency division multiplexing modulation mode.
- Step 103 Perform digital-to-analog conversion on the modulated orthogonal frequency division multiple access subcarriers to obtain an electrical domain orthogonal frequency division multiple access signal.
- Step 104 modulate the electrical domain orthogonal frequency division multiple access signal onto an uplink optical signal to obtain an optical domain orthogonal frequency division multiple access signal.
- Step 105 Send the optical domain orthogonal frequency division multiple access signal.
- the passive optical network system may include: an optical line terminal OLT, a remote node RN, and one or more optical network units ONU, wherein the remote node may include a WDM splitter, a WDM combiner, and a power Separator, etc.
- the signal processing method of the passive optical network can be applied in the uplink direction (from ONU to OLT) or in the downlink direction (from OLT to ONU).
- the signal processing method of the passive optical network may further include the following steps: receiving uplink bandwidth indication information, where the uplink bandwidth indication information includes the number and number of the allocated orthogonal frequency division multiple access subcarriers.
- the OLT may allocate orthogonal frequency division multiple access subcarriers to the optical network unit according to the traffic and/or service type of the service signal, and allocate the allocated orthogonal frequency divisions by using the uplink bandwidth indication information.
- the number and number of subcarriers are sent to the ONU. If the ONU receives the service signal, for example, the FE signal GE signal, etc., the service signal may be subjected to baseband encoding processing, for example: using MQAM encoding processing.
- the ONU performs orthogonal frequency division multiplexing modulation on the service signal after the baseband coding process.
- the service signal after the baseband coding process is modulated onto the allocated orthogonal frequency division multiple access OFDMA subcarrier by using an IFFT operation.
- the ONU may perform D/A conversion on the OFDMA carrying the service signal to obtain an electrical domain OFDMA signal; and then modulate the electrical domain OFDMA signal onto the optical signal to obtain an optical domain OFDMA signal.
- step 104 may specifically include:
- a reflective semiconductor optical amplifier (RSOA) is used to reflect an uplink optical signal according to the received downlink optical signal, and then the electrical domain OFDMA signal on the OFDMA subcarrier is modulated onto the reflected upstream optical signal to form a The optical domain OFDMA signal; the transmitter in the ONU can transmit the modulated optical domain OFDMA signal to the RN for combining.
- RSOA reflective semiconductor optical amplifier
- the method further includes: superposing the optical domain orthogonal frequency division multiple access signal by a power splitter of the remote node, where the power splitter is configured to receive at least one channel and the optical domain orthogonal frequency division The optical signals having the same wavelength of the multiple access signals are transmitted, and the superposed optical domain orthogonal frequency division multiple access signals are transmitted.
- Each of the power splitters in the RN can connect a plurality of transmitted ONUs having the same wavelength, and the plurality of ONUs having the same wavelength can be transmitted as one group.
- the power splitter receives the optical domain OFDMA signals of the same wavelength transmitted by the respective ONUs in the connected group, the received optical domain OFDMA signals are superimposed, and then the WDM combiner in the RN sets the different power splitters.
- the superposed optical domain OFDMA signals are combined into a continuous multi-wavelength optical signal.
- the wavelengths of the optical domain OFDMA signals superimposed by different power splitters may be different.
- the RN may perform optical power compensation on the multi-wavelength optical signal by using an optical compensation device such as an active amplifier before transmitting the multi-wavelength optical signal to realize long-distance transmission.
- an optical compensation device such as an active amplifier
- the ONU modulates the received service signal onto the allocated orthogonal frequency division multiple access subcarrier, and modulates the electrical signal on the orthogonal frequency division multiple access subcarrier to the reflected uplink optical signal, and passes the RN.
- a continuous multi-wavelength optical signal can be obtained, and the continuous multi-wavelength optical signal can be easily and easily compensated for optical power, thereby supporting long-distance transmission; the transmitting and receiving equipment of the continuous signal is lower in cost than the burst signal. Thereby reducing the network construction cost.
- FIG. 11 is a flowchart of a second embodiment of a signal processing method for a passive optical network according to the present invention. As shown in FIG. 11, the signal processing method of the passive optical network includes:
- Step 201 Perform analog-to-digital conversion on the received superposed optical domain orthogonal frequency division multiple access signal.
- Step 202 Perform orthogonal frequency division multiplexing demodulation on the analog-to-digital converted signal.
- Step 203 Perform baseband decoding processing on the signal after orthogonal frequency division multiplexing demodulation, and obtain a service signal.
- the OLT may include multiple receivers, and the WDM splitter of the OLT may receive
- the multi-wavelength optical signal transmitted by the RN is separated into superposed optical domain orthogonal frequency division multiple access signals of different wavelengths.
- Each of the receivers may respectively receive the superposed optical domain OFDMA signal; then perform analog-to-digital (A/D) conversion on the superposed optical domain OFDMA signal, and then perform orthogonal frequency division multiplexing (OFDM) demodulation, for example: using FFT
- OFDM orthogonal frequency division multiplexing
- the calculation is performed by the baseband decoding process. For example, after the MQAM decoding operation, the service signal transmitted by the ONU can be recovered.
- the OLT separates the received multi-wavelength optical signals to obtain a superposed optical domain OFDMA signal, and then performs superposed analog-to-digital conversion, orthogonal frequency division multiplexing demodulation, and baseband decoding processing on the superposed optical domain OFDMA, respectively, to obtain a service.
- Signal Since the multi-wavelength optical signal is a continuous signal formed by the multiplexing of orthogonal frequency division multiple access frames, the optical power compensation is simple to implement and can support long-distance transmission; compared with the burst signal, the continuous signal transmitting and receiving equipment has low cost. Thereby reducing the network construction cost.
- the uplink direction of the signal sent by the ONU to the OLT, and the signal processing method of the passive optical network may include:
- Step 301 Each ONU performs a baseband coding process, such as an MQAM coding process, on an input service signal, such as an FE or a GE signal.
- a baseband coding process such as an MQAM coding process
- Step 302 The ONU performs an IFFT operation on the baseband coded service signal to implement OFDM modulation, and modulates the baseband coded service signal to each allocated OFDMA subcarrier.
- the OLT may adopt an OFDMA subcarrier based dynamic.
- the bandwidth allocation (Dynamic Bandwidth Allocation, DBA) algorithm allocates bandwidth to the ONU, thereby improving the upper bandwidth. Bandwidth utilization of the line.
- the ONU can monitor the traffic of the uplink customer's service signal, and when the bandwidth is about to be insufficient, send an uplink bandwidth allocation request to the OLT to apply for a bandwidth request to the OLT; the OLT can request the uplink bandwidth allocation of all the ONUs.
- DBA Dynamic Bandwidth Allocation
- the bandwidth allocation of the ONUs is uniformly performed according to the traffic or at the same time according to the traffic and the service priority.
- the uplink bandwidth allocation of all ONUs of one wavelength can be in the OFDMA mode.
- Each ONU allocates bandwidth according to the OFDMA subcarriers. Different ONUs can allocate one or more different OFDMA subcarriers, and the ONUs share one common unit by OFDMA subcarriers.
- the OLT then sends an uplink bandwidth indication information to the ONU, indicating how many uplink OFDMA subcarriers and subcarriers can be used by the ONU.
- the ONU can map the service signal to the allocated according to the received uplink bandwidth indication information.
- the MQAM mapping and the IFFT operation are performed on the allocated subcarriers, and the subcarriers in other locations are zero-filled.
- These OFDMA subcarriers are equivalent to time slots, and each OFDMA subcarrier represents a minimum bandwidth allocation unit.
- multiple ONUs can share the same wavelength through OFDMA subcarriers, thereby improving the ability to share wavelengths.
- Step 303 The ONU performs D/A conversion on the OFDMA subcarrier carrying the service signal to obtain the electrical domain OFDMA signal, and then modulates the electrical domain OFDMA signal to the optical signal of a certain wavelength through the RSOA to form the optical domain OFDMA signal;
- Step 304 The power splitter in the RN superimposes the optical domain OFDMA signals of the same wavelength transmitted by the connected ONUs to form a complete uplink OFDMA frame.
- the ONU can be modulated by means of reflecting the uplink optical signal.
- the electrical domain OFDMA signal is modulated by the RSOA to the optical signal of a certain wavelength, specifically: the uplink optical signal of the ONU is received by the downlink optical signal received by the ONU.
- the seed light source is amplified by reflection, etc., and then the amplified light source is modulated and sent to the OLT.
- each power splitter is connected to the same ONU as a group. For example, there are 32 ONUs of wavelength A, which are the first group; the other 32 ONUs of wavelength B are the second group; Different wavelengths can be divided into 32 groups.
- the same group of ONUs allocates OFDMA subcarriers by OFDMA to achieve wavelength sharing, specifically: assigning different numbers and different numbers of OFDMA subcarriers to different ONUs in the same group, and electrical domains on the same group of OFDMA subcarriers
- the OFDMA signal is converted to an optical domain OFDMA signal of the same wavelength, and then the OFA signals of the same optical domain are superimposed by a power splitter.
- An ONU may be allocated to one or more OFDMA subcarriers in the uplink direction, and the OFDMA subcarriers of all connected ONUs are in the frequency domain and time by a power splitter at one wavelength.
- the inter-domain is superimposed as an OFDMA frame.
- FIG. 12b is a schematic diagram of a method for superimposing OFDMA subcarriers on the same wavelength in a third embodiment of a signal processing method for a passive optical network according to the present invention.
- ONU_1 is allocated to OFDMA subcarrier A
- ONU_2 is allocated to OFDMA subcarrier B
- the ONU_3 is allocated to the OFDMA subcarrier C and the OFDMA subcarrier D.
- the OFDMA subcarriers A, B, C, and D to which all ONUs are allocated may be superimposed into one OFDMA frame.
- the reason why the ONUs are grouped according to the wavelength is as follows: Assume that the number of ONUs is 1024. If each ONU is only allocated one subcarrier, the fineness of bandwidth allocation is poor, which is not conducive to efficient use of bandwidth; The number of subcarriers allocated by the ONU can be greater than one. H does not allocate 32 subcarriers for each ONU. The ONU needs to implement 32 1024 points when performing IFFT operations. The more points, the more difficult it is to implement digital processing and hardware implementation of IFFT operations. .
- the OFDMA frame is repeated in time, the distance of each ONU is different, and the time offset of the OFDMA frame may be generated when the power splitter is superimposed. If the time offset exceeds the guard interval between the OFDMA frames, the OLT A reception error may occur, so the OLT can measure the distance or relative time offset of each ONU individually for each wavelength group, which is the ranging process. Each ONU can send delay compensation according to the result of the ranging, so that the differential distance delay between the ONUs is smaller than the guard interval of the OFDMA frame, so that the OLT can receive correctly.
- the ranging process is specifically as follows: First, the OLT issues a windowing instruction; subsequently, the ONU in the working state stops transmitting data, and fills "0" in the assigned subcarrier position in the OFDMA frame, and the newly entered ONU follows the following line.
- the value in the time counter is used as the downlink time reference, and the OFDMA join request frame is sent to the OLT. If the OLT receives the OFDMA join request frame sent by the newly entered ONU, the time offset value of the newly entered ONU is calculated, and the time offset is calculated.
- the ONU sends the OFU frame to the OLT after adding the time offset value to the downlink time reference.
- Step 305 The WDM combiner in the RN may combine the optical signals of different wavelengths superimposed by the respective power splitters to obtain a multi-wavelength optical signal, and then the RN transmits the multi-wavelength optical signal to the OLT direction;
- optical signals of different wavelengths carrying the respective OFDMA frames superimposed by the power splitter are independent of each other, and the uplink OFDMA frames of different wavelengths of each power splitter are combined by the WDM combiner in the RN to form multi-wavelength light.
- Step 306 After the OLT performs wavelength separation on the multi-wavelength optical signal by the WDM splitter at the receiving end, the receiver in the OLT independently receives the optical signal for each wavelength.
- the OLT can filter out optical signals of different wavelengths through the WDM splitter at the receiving end and send them to different receivers, for example: optical receivers. Since the uplink OFDMA signals of each ONU are time-continuous signals, the OLT can use Continuous optical receiver reception. Also, each ONU can use a continuous laser transmitter in the upstream direction without any shutdown.
- the upstream wavelengths of the same group of ONUs are locked to the same seed source, so that the upstream wavelengths of the same group of ONUs can be kept strictly consistent, and the same group is all passed through the power splitter.
- the ONU optical domain OFDMA signal is superimposed as an uplink OFDMA frame, it is sent to the OLT, and the OLT receiver does not generate beat noise.
- the uplink optical signals of a group of ONUs can be strictly consistent, for example: using the RSOA to reflect and amplify the received downlink color light in the ONU, wherein the downlink color light can be received by each ONU.
- the downlink optical signal that is currently modulated to carry the data sent by the OLT may also be another downlink optical signal that the OLT specifically sends to the ONU.
- the downlink color light that is preferably used is the current received by each ONU.
- the modulated downstream optical signal carrying the data transmitted by the OLT After receiving the downlink optical signal, the ONU reflects and amplifies the downlink optical signal by using the RSOA to form an uplink optical signal; and then converts the uplink IOFDM-processed electrical domain OFDMA signal to the uplink optical signal to implement the electrical signal to the optical signal. Signal conversion, this process is the process of remodulation, which is the process of reflecting and amplifying the downstream optical signal and then performing electro-optic modulation.
- the ONU's upstream laser can use RSOA, FP-LD (Fabry-Perot semiconductor laser diode) laser, or other lasers.
- the upstream optical signal of the ONU is not limited to being received and received.
- the downlink optical signals are the same, but the uplink optical signals between the 0NUs in the same group are the same, which can ensure that the receiver of the corresponding OLT in the group does not generate beat noise.
- Step 307 The OLT performs an A/D conversion, an FFT demodulation, and an MQAM decoding operation on the optical signal according to the group, and recovers the service signal.
- the signal processing method of the passive optical network in this embodiment is adopted, and the access bandwidth of each ONU is large, even reaching 1 Gbps, and the specific analysis is as follows:
- the ONU may be extended to the network according to the wavelength, for example: if each wavelength can carry 32 ONUs, 32 wavelengths may have 1024 ONUs; if each wavelength can have 64 ONUs, suppose C With a maximum of 40 wavelengths, a total of 2560 ONUs can be used.
- the ONU adopts OFDM modulation and MQAM coding before optical modulation, which can improve bandwidth utilization.
- Each ONU realizes sharing of uplink optical signals by OFDMA, and the OFDMA frames of each ONU are repeated by time, in the same Over time, the format of the OFDMA frame includes a prefix part and an OFDM IFFT data part; the superposed OFDMA signal is a continuous signal in time; and the TDMA mode PON directly processes the service signal to the transmitting laser after being processed by the TDM frame.
- the signal obtained by superposition by the power splitter is the same burst signal as the upstream direction of the GPON.
- the ONU does not need to have an uplink burst sending capability, and only needs to be generally The continuous transmission capability of the ONU; the transmission laser of the ONU does not need to be turned off and on, and is always on; therefore, there is no need to set an expensive burst receiver in the OLT, and a general continuous receiver such as an optical receiver can be used. Thereby reducing the cost of network construction.
- the present embodiment adds an electric processing process such as IFFT and D/A conversion, it can be realized based on mature integrated circuit technology, and the hardware cost is not high.
- the transmission distance is limited by the physical distance of the GPON itself.
- factors affecting the physical distance include difficulty in compensating for the burst signal optical power.
- the problem is that, in the all-optical region, the time constant of the EDFA is much larger than the frame length of the GPON, and it is almost impossible to completely respond to burst signals of different levels, so it is very difficult to perform power compensation operation in the optical domain.
- the optical power compensation of the continuous signal of the OFDMA can be performed at the OLT and the RN by using an EDFA or the like, such as setting a bidirectional optical amplifier in the RN.
- the transmission distance can be greatly increased to achieve long-distance transmission.
- the ONU output is O DBm
- the RN consumes 4DB.
- the budget can also pass 10Km, a total distance of 20Km.
- OLT preset (PRE-AMP) EDFA OLT preset
- the sensitivity of the OLT can be increased to -40DB, which can realize the transmission above lOOKm between RN and OLT, plus the optical power compensation on the RN. From the ONU to the OLT, all-optical transmission above 1 lOKm can be achieved.
- the output of the OLT downstream optical amplifier is + 20DB.
- the RN After reaching the RN at 80Km, there is still - 12DB, which can be boosted to + 12DB after being compensated by the downlink amplifier in the RN; and remaining + 7DB after the AWG is depleted by 5DB.
- the remaining - 8DB after the transfer of lOKm to the ONU, the loss of 4DB remains - 12DB, assuming that the receiving sensitivity of the ONU is - 18DB, the total power budget has more surplus.
- the above power compensation for the RN is guaranteed. Sum calculation, if you consider the maximum output power, there is still a large power margin. Therefore, in this embodiment, optical power compensation is performed on the continuous signal, and long-distance transmission of more than 10 OKm can be realized.
- bandwidth allocation is performed for the ONU according to the OFDMA subcarrier, which is based on bandwidth allocation in the frequency domain.
- the dynamic bandwidth allocation of the ONU in the uplink frame on the uplink frame is based on time. Bandwidth allocation for the domain.
- the OFDMA frame is sent as a continuous signal in the uplink direction, and the uplink burst transmitting device of the ONU is not required, and the uplink burst receiving device of the OLT is not needed, which can reduce the network construction cost; Power compensation is relatively easy to implement, enabling long-distance transmission.
- transmissions above 10Omm provide the possibility of CO upshifting.
- the direction is grouped according to different wavelengths, which is beneficial to the expansion of the number of ONUs in the system.
- the foregoing program may be stored in a computer readable storage medium, and the program is executed when executed.
- the foregoing steps include the steps of the foregoing method embodiments; and the foregoing storage medium includes: a medium that can store program codes, such as a ROM, a RAM, a magnetic disk, or an optical disk.
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Description
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AU2010324303A AU2010324303A1 (en) | 2009-11-24 | 2010-11-22 | Method, device and system for signal processing in passive optical network |
EP10832635A EP2495892A4 (en) | 2009-11-24 | 2010-11-22 | METHOD, DEVICE AND SIGNAL PROCESSING SYSTEM IN PASSIVE OPTICAL NETWORKS |
US13/476,684 US20120230693A1 (en) | 2009-11-24 | 2012-05-21 | Signal processing method, device, and system in a passive optical network |
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US20120230693A1 (en) | 2012-09-13 |
EP2495892A4 (en) | 2012-10-24 |
EP2495892A1 (en) | 2012-09-05 |
CN102075478A (zh) | 2011-05-25 |
AU2010324303A1 (en) | 2012-06-21 |
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