CN103109476A - Passive optical communication method, system, and optical line terminal - Google Patents

Passive optical communication method, system, and optical line terminal Download PDF

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Publication number
CN103109476A
CN103109476A CN2012800015364A CN201280001536A CN103109476A CN 103109476 A CN103109476 A CN 103109476A CN 2012800015364 A CN2012800015364 A CN 2012800015364A CN 201280001536 A CN201280001536 A CN 201280001536A CN 103109476 A CN103109476 A CN 103109476A
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optical
network unit
optical network
sent
ofdm modulation
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CN2012800015364A
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CN103109476B (en
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彭桂开
周雷
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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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
    • 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
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2587—Arrangements specific to fibre transmission using a single light source for multiple stations
    • 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
    • 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
    • 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
    • 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

Abstract

The invention provides a passive optical communication method, a system, and an optical line terminal. The system comprises an OLT, an ODN, and an ONU. The OLT can be used to generate the wide band light and the downstream light. The downstream light can be used to send the downstream signal generated by the downstream data of the orthogonal frequency division multiplexing to at least one optical network unit. The ODN can be used to divide the wide band light into at least one optical wave corresponding to at least one optical network unit, and can be used to send at least one optical wave and the downstream signal to the at least one corresponding optical network unit correspondingly. At least one optical network unit can be used to receive the downstream signal, and the downstream data can be acquired by the orthogonal frequency division multiplexing of the downstream signal. The upstream data, which are waiting to be sent to the optical line terminal, after the orthogonal frequency division multiplexing can be used to carry the upstream signal generated by the optical wave received by the optical distribution network, and the upstream signal can be sent to the optical distribution network. According to the invention, each ONU can work in different transmission wave lengths with low costs.

Description

EPON communication means and system, optical line terminal
Technical field
The present invention relates to passive optical network technique, relate in particular to a kind of EPON communication means and system, optical line terminal.
Background technology
(Passive Optical Network is called for short: PON) because the networking cost is lower, be subject to attracting attention of industry as a kind of cost-effective technological means in the optical access network field EPON.Current, introduced OFDM (Orthogonal Frequency DivisionMultiplexing at optical communication field, be called for short: OFDM) technology, OFDM multiplexing passive optical network (Orthogonal Frequency Division Multiplexing Access PassiveOptical Network, abbreviation: OFDMA-PON) based on OFDM have been proposed.Be a kind of differentiation innovation in optical communication technique field introducing OFDM technology, the OFDM technology can be used as the availability of frequency spectrum and the channel capacity that modulation technique improves channel on the one hand, effectively to anti-multipath and effect of dispersion; Can utilize on the other hand subcarrier to realize efficient OFDMA access, thereby realize multi-user and multiple services allocated bandwidth flexibly.Different subcarriers both can be distributed to different users, also can distribute to different classs of business.These characteristics of OFDM technology make it be particularly suitable for using in PON.
In the framework of OFDMA-PON, generally include an optical line terminal (Optical Line Terminal who is positioned at local side, be called for short: OLT) with a plurality of optical network unit (OpticalNetwork Unit that are positioned at user side, be called for short: ONU), pass through Optical Distribution Network (OpticalDistribution Network between OLT and ONU, be called for short: ODN) connect, in EPON, ODN is based on optical splitter optical splitter Splitter and realizes.
In the OFDMA-PON of prior art, carry out transfer of data between OLT and ONU and all adopt data modulation based on OFDM.For example, at data sending terminal, high-speed serial data is first become the low-speed parallel data, and then parallel data is mapped to a plurality of modulating vectors, then (Inverse Fast Fourier Transform is called for short: IFFT) to carry out inverse fast Fourier transform; (CyclicPrefix, be called for short: CP), (Digital Analog Conversion is called for short: DAC), produce continuous ofdm signal and send to channel to do at last parallel serial conversion and digital-to-analogue conversion to add Cyclic Prefix after conversion.The processing of carrying out process contrary to the above at receiving terminal obtains initial serial data.wherein, up direction between OLT and ONU, it is the transfer of data that multiple spot arrives a bit, receiving terminal at OLT only has a photodetector (PhotoDetector, be called for short: PD), this PD receives the upward signal light from all ONU, the PD that incides OLT when two bundles or the two above light waves of bundle of ONU can produce optical beat interference (OpticalBeat Interference when upper, be called for short: OBI), particularly when the centre wavelength of described light wave is identical or close, optical beat disturbs will produce direct current or low-frequency component, cause the interference to follow-up data OFDM modulation.Therefore, must allow each ONU be operated in different emission wavelengths, to eliminate or to reduce above-mentioned OBI problem.
Mainly containing at present following several mode is used for making the operation wavelength of each ONU different: a kind of mode is, is provided for respectively launching the transmitter of this ONU corresponding wavelength in each ONU, and cost is higher; Another kind of mode is, a kind of transmitter of all ONU, but the wavelength of this transmitter is tunable, for example, can tuning 32 emission wavelengths, but this tunable transmitter cost costliness is not suitable for using in Access Network; Another mode is, increase separately a laser at OLT, be used for sending the light wave of a up wavelength, this light wave is shared the upstream data that is used for carrying separately for each ONU, but in this mode, the optical modulations that ONU must adopt carrier wave to suppress when doing up modulation, original light wave spectral line is curbed, and need to carry out coherent reception at the OLT end, the upstream data that sends to recover ONU, complex technology, cost are also very expensive.
Summary of the invention
The invention provides a kind of EPON communication means and system, optical line terminal, realize that with lower cost each ONU is operated in different emission wavelengths.
A first aspect of the present invention is to provide a kind of passive optical network communication system, comprising: optical line terminal, Optical Distribution Network and at least one optical network unit, and described optical line terminal is connected with described at least one optical network unit by Optical Distribution Network;
Described optical line terminal, for generation of the wide spectrum optical with first wavelength and descending light with second wave length, form downstream signal by the described descending light carrying downlink data through OFDM modulation to described at least one optical network unit to be sent, and described wide spectrum optical and downstream signal are sent to described Optical Distribution Network; And, be used for receiving the upward signal that described at least one optical network unit sends, and described upward signal is passed through the OFDM demodulation, obtain respectively upstream data corresponding to described at least one optical network unit;
Described Optical Distribution Network, be used for and be divided at least one corresponding with at least one optical network unit respectively light wave from the wide spectrum optical that described optical line terminal receives, and described at least one light wave and described downstream signal are sent to respectively corresponding described at least one optical network unit; And, be used for being undertaken being sent to described optical line terminal after multiplexing by the upward signal that described at least one optical network unit is sent;
Described at least one optical network unit is used for receiving described downstream signal, and described downstream signal is carried out the OFDM demodulation obtains the downlink data corresponding with described optical network unit; And, the upstream data through OFDM modulation to described optical line terminal to be sent is carried on from the described light wave of described Optical Distribution Network reception, form upward signal, and described upward signal is sent to described Optical Distribution Network.
In conjunction with first aspect, in the possible implementation of the first, described optical line terminal specifically comprises: wide spectrum light source and the first OFDM modulation module; Described wide spectrum light source is for generation of the described wide spectrum optical with first wavelength;
Described the first OFDM modulation module is used for the downlink data to described at least one optical network unit to be sent is carried out OFDM modulation; And, be used for the upward signal that at least one optical network unit that receives sends is carried out the OFDM demodulation, obtain respectively upstream data corresponding to described at least one optical network unit.
In conjunction with the possible implementation of the first of first aspect, in the possible implementation of the second, described optical line terminal also comprises: the first transmitter module and first wave division multiplexer;
Described the first transmitter module is used for that described the first OFDM modulation module is carried out downlink data after OFDM modulation and is carried on described descending light and forms downstream signal;
Described first wave division multiplexer is used for described downstream signal and described wide spectrum optical are carried out being sent to described Optical Distribution Network after multiplexing;
Described Optical Distribution Network also comprises: the Second Wave division multiplexer;
Described Second Wave division multiplexer is used for described downstream signal and described wide spectrum optical are carried out demultiplexing, so that the described wide spectrum optical of described Optical Distribution Network after to demultiplexing cut apart.
In conjunction with first aspect, in the third possible implementation, described Optical Distribution Network specifically comprises: array waveguide grating; Described array waveguide grating is used for the wide spectrum optical that described optical line terminal sends is divided at least one light wave corresponding with at least one optical network unit; And, be used for carrying out multiplexing to the upward signal that described at least one optical network unit sends.
In conjunction with the possible implementation of the second of first aspect, in the 4th kind of possible implementation, described Optical Distribution Network also comprises: optical splitter;
Described optical splitter, be used for the downstream signal after described Second Wave division multiplexer demultiplexing, be divided at least one corresponding with at least one optical network unit respectively downstream signal, and described at least one downstream signal correspondence is broadcast to described at least one optical network unit.
In conjunction with the possible implementation of the second of first aspect, in the 5th kind of possible implementation, described the first OFDM modulation module comprises a plurality of the first OFDM modulation transmitting elements, and the quantity of described the first transmitter module is a plurality of; Described first an OFDM modulation transmitting element and first transmitter module form a transmitter unit, and the quantity of described transmitter unit equates with the quantity of described a plurality of optical network units;
A plurality of described transmitter units are used for sending a plurality of downstream signals that carry respectively the downlink data corresponding with described optical network unit, and described downstream signal has the second wave length corresponding with described optical network unit.
A second aspect of the present invention provides a kind of optical line terminal, comprising: wide spectrum light source, the first OFDM modulation module and signal emission module;
Described wide spectrum light source is for generation of the described wide spectrum optical with first wavelength;
Described the first OFDM modulation module is used for the downlink data to described at least one optical network unit to be sent is carried out OFDM modulation; And, be used for and will carry out the OFDM demodulation from the upward signal that at least one optical network unit receives, obtain respectively upstream data corresponding to described at least one optical network unit;
Signal emission module for generation of the descending light with second wave length, and forms downstream signal by the described descending light carrying downlink data through OFDM modulation to described at least one optical network unit to be sent; And described downstream signal and described wide spectrum optical are carried out being sent to described Optical Distribution Network after multiplexing, be sent to respectively at least one optical network unit so that described Optical Distribution Network is divided at least one light wave with described wide spectrum optical, and make described optical network unit by described light wave carrying upstream data.
In conjunction with second aspect, in the possible implementation of the first, described the first OFDM modulation module comprises a plurality of the first OFDM modulation transmitting elements, and the quantity of described the first transmitter module is a plurality of; Described first an OFDM modulation transmitting element and first transmitter module form a transmitter unit, and the quantity of described transmitter unit equates with the quantity of a plurality of optical network units;
A plurality of described transmitter units are used for sending a plurality of downstream signals that carry respectively the downlink data corresponding with described optical network unit, and described downstream signal has the second wave length corresponding with described optical network unit.
In conjunction with second aspect, in the possible implementation of the second, described the first OFDM modulation module comprises first an OFDM modulation transmitting element, and first transmitter module; Described first an OFDM modulation transmitting element and first transmitter module connect to form a transmitter unit; Described transmitter unit after being used for the downlink data to described at least one optical network unit to be sent is carried out OFDM modulation, all being carried on described descending light with second wave length and forming downstream signal.
A third aspect of the present invention provides a kind of EPON communication means, comprising:
The descending light that generation has the wide spectrum optical of the first wavelength and has second wave length;
Treat the downlink data that is sent to described at least one optical network unit and carry out OFDM modulation, and the described Deta bearer after modulating forms downstream signal at described descending light;
Described wide spectrum optical and downstream signal are sent to Optical Distribution Network, be sent to respectively at least one optical network unit so that described Optical Distribution Network is divided at least one light wave with described wide spectrum optical, and make described optical network unit by described light wave carrying upstream data;
Receive the upward signal that described at least one optical network unit sends, and described upward signal is passed through the OFDM demodulation, obtain respectively upstream data corresponding to described at least one optical network unit.
In conjunction with the third aspect, in the possible implementation of the first, described generation has the descending light of second wave length, comprising: produce at least one descending light, described at least one descending light has respectively the wavelength corresponding with described at least one optical network unit;
The described downlink data that is sent to described at least one optical network unit for the treatment of carries out OFDM modulation, and the described Deta bearer after modulating comprises at described descending light formation downstream signal:
Treat respectively the downlink data that is sent to described at least one optical network unit and carry out OFDM modulation, and the described data after modulating are carried on respectively at least one descending light corresponding with described optical network unit, form a plurality of downstream signals corresponding with described at least one optical network unit.
A fourth aspect of the present invention is to provide a kind of EPON communication means, comprising:
Receive downstream signal and light wave that optical line terminal sends, described downstream signal carries the downlink data through OFDM modulation that described optical line terminal sends, described downlink data is carried on the descending light with second wave length, and described light wave is to cut apart by the wide spectrum optical with first wavelength that described optical line terminal is produced to obtain;
Described downstream signal is carried out the OFDM demodulation, obtain described downlink data; And the upstream data to described optical line terminal to be sent is carried on described light wave, form upward signal, be sent to described optical line terminal.
EPON communication means provided by the invention and system, the technique effect of optical line terminal is: only a wide spectrum light source need to be set in OLT, and match with AWG in ODN, the wide spectrum optical that this wide spectrum light source is produced by AWG is divided into a plurality of light waves and injects each ONU and get final product, be equivalent to only arrange a wide spectrum light source and an AWG, the cost of this wide spectrum light source and AWG is low, so in each ONU, transmitter is set than of the prior art, all cost is low perhaps to adopt expensive tunable transmitter, and, adopt the compound mode of above-mentioned wide spectrum light source and AWG to realize that the wavelength of each ONU is different, implementation method is very simple, adopt optical modulations and the OLT end that carrier wave suppresses to carry out coherent reception than ONU of the prior art, simple, more easily implement, so cost is also lower.
Description of drawings
Fig. 1 is the structural representation of passive optical network communication system one embodiment of the present invention;
Fig. 2 is the structural representation of another embodiment of passive optical network communication system of the present invention;
Fig. 3 is the structural representation of the another embodiment of passive optical network communication system of the present invention;
Fig. 4 is the structural representation of optical line terminal embodiment of the present invention;
Fig. 5 is the schematic flow sheet of EPON communication means one embodiment of the present invention;
Fig. 6 is the schematic flow sheet of another embodiment of EPON communication means of the present invention;
Fig. 7 is the schematic flow sheet of the another embodiment of EPON communication means of the present invention.
Embodiment
Embodiment one
Fig. 1 is the structural representation of passive optical network communication system one embodiment of the present invention, as shown in Figure 1, the passive optical network communication system of the present embodiment comprises: OLT11, ODN12 and a plurality of ONU13, the quantity of this ONU13 also can be one in concrete enforcement, just the present embodiment is for the different implementation method of the wavelength that each ONU is described, describes take at least two as example.
Wherein, OLT11, for generation of the wide spectrum optical with first wavelength and descending light with second wave length, form downstream signal by the described descending light carrying downlink data through OFDM modulation to described at least one optical network unit to be sent, and described wide spectrum optical and downstream signal are sent to described Optical Distribution Network; And, be used for receiving the upward signal that described at least one optical network unit sends, and described upward signal is passed through the OFDM demodulation, obtain respectively upstream data corresponding to described at least one optical network unit;
For example, can comprise in OLT11: an OFDM modulation module 111 and (broadband light source is called for short: BLS) 112 for generation of the wide spectrum light source of wide spectrum optical.This wide spectrum light source 112 can be for example, and (Light Emitting Diode is called for short: LED), (Superluminescent Light Emitting Diodes is called for short: the multiple device such as SLD) the superradiation light-emitting diode Light-Emitting Diode; The wavelength of this wide spectrum light source 112 can be called the first wavelength; The one OFDM modulation module 111 can be used for the upward signal of a plurality of ONU that receive is carried out demodulation, obtains respectively upstream data corresponding to these a plurality of ONU.The present embodiment adopts 111 pairs of data of an OFDM modulation module to carry out demodulation or the modulation of OFDM mode, can improve the availability of frequency spectrum.
Described ODN12, be used for and be divided at least one corresponding with at least one optical network unit respectively light wave from the wide spectrum optical that described optical line terminal receives, and described at least one light wave and described downstream signal are sent to respectively corresponding described at least one optical network unit; And, be used for being undertaken being sent to described optical line terminal after multiplexing by the upward signal that described at least one optical network unit is sent;
For example, can comprise in described ODN12: array waveguide grating (Arrayed WaveguideGrating, be called for short: AWG) 121, this AWG121 can be used for being divided into from the wide spectrum optical that OLT receives corresponding with a plurality of ONU respectively a plurality of light waves, the wavelength of described a plurality of light waves is different, and described a plurality of light waves are sent to respectively described a plurality of ONU; Can also be sent to OLT after multiplexing to the upward signal of a plurality of ONU transmissions.
Described ONU13 is used for receiving described downstream signal, and described downstream signal is carried out the OFDM demodulation obtains the downlink data corresponding with described optical network unit; And, the upstream data through OFDM modulation to described optical line terminal to be sent is carried on from the described light wave of described Optical Distribution Network reception, form upward signal, and described upward signal is sent to described Optical Distribution Network;
For example, described ONU13 can comprise: the 2nd OFDM modulation module 131 and transmitter module 132; The 2nd OFDM modulation module 131 can be used for the upstream data of ONU is carried out the OFDM modulation, transmitter module 132 is used for that the upstream data after the OFDM modulation is carried on the described light wave that receives from ODN and forms upward signal, and this upward signal is sent to described ODN.
The operation principle of the passive optical network communication system of the present embodiment is as follows: be operated in different wavelength in order to realize each ONU, the present embodiment is provided with wide spectrum light source 112 in OLT11, the wide spectrum optical that this wide spectrum light source 112 is produced is sent to ODN, by the AWG121 in ODN, this wide spectrum optical is divided into the mutually different light wave of a plurality of wavelength, and should be sent to a plurality of ONU by a plurality of light waves; Follow-up ONU is when carrying out uplink, the wavelength that upward signal is corresponding is exactly the wavelength of the light wave that receives in advance of this ONU, thereby when making uplink, the wavelength of the upward signal of each ONU is also different, just can not produce OBI, solved the optical beat interference problem, an OFDM modulation module 111 in OLT can carry out demodulation to the upward signal of a plurality of ONU of receiving, obtains respectively upstream data corresponding to these a plurality of ONU.
Need to prove, the passive optical network communication system of the present embodiment only shows the included part of module of this passive optical network communication system, for example in Fig. 1, array waveguide grating, wide spectrum light source etc., but in concrete enforcement, it will be understood by those skilled in the art that the each several part in this system, for example OLT, ODN, ONU, it is not limited to and only comprises the module shown in Fig. 1, such as, can also comprise optical splitter (splitter) etc. in ODN.
in the described passive optical network communication system of the present embodiment, only a wide spectrum light source need to be set in OLT, and match with AWG in ODN, the wide spectrum optical that this wide spectrum light source is produced by AWG is divided into a plurality of light waves and injects each ONU and get final product, be equivalent to only arrange a wide spectrum light source and an AWG, the cost of this wide spectrum light source and AWG is low, so in each ONU, transmitter is set than of the prior art, all cost is low perhaps to adopt expensive tunable transmitter, and, adopt the compound mode of above-mentioned wide spectrum light source and AWG to realize that the wavelength of each ONU is different, implementation method is very simple, adopt optical modulations and the OLT end that carrier wave suppresses to carry out coherent reception than ONU of the prior art, simple, more easily implement, so cost is also lower.
Below by embodiment two and embodiment three, two kinds of optional system configurations are described respectively:
Embodiment two
Fig. 2 is the structural representation of another embodiment of passive optical network communication system of the present invention, and the present embodiment is on the basis of structure shown in Figure 1, to the further refinement of the structure of passive optical network communication system.
As shown in Figure 2, the OLT11 of this system also comprises: transmitter module (Optical Transmitter, show with Optical Tx in Fig. 2) 113 (can be called the first transmitter module) and the first receiver module (Optical Receiver shows with Optical Rx in Fig. 2) 114.Wherein, transmitter module 113 can produce the descending light with second wave length, and the downlink data after OFDM modulation is carried on this descending light forms downstream signal, downlink data after described OFDM modulation is the signal of telecommunication, light signal and be carried on the downstream signal that forms on descending light, so this transmitter module 113 is the equal of to carry out opto-electronic conversion, after being converted to light signal, the signal of telecommunication could transmit at trunk optical fiber.The first receiver module 114 is used for receiving the upward signal of a plurality of ONU, the upward signal that is ONU will be received by this first receiver module 114 after entering OLT, by this first receiver module 114, upward signal is sent to an OFDM modulation module 111 and carries out demodulation acquisition upstream data.
An OFDM modulation module 111 in described OLT11, specifically can comprise: an OFDM modulation sending unit (OFDM Transmitter, show with OFDM Tx in Fig. 2) the 115 and the one OFDM modulation receiving element (OFDM Receiver shows with OFDM Rx in Fig. 2) 116; Wherein, an OFDM modulation sending unit 115 is carried out the OFDM modulation for the downlink data that will be sent to a plurality of ONU, and the downlink data after the OFDM modulation is sent to transmitter module 113; The one OFDM modulation receiving element 116 is used for the upward signal of each ONU of the first receiver module 114 receptions is carried out the OFDM demodulation, obtains respectively upstream data corresponding to each ONU.
Wherein, the method for above-mentioned OFDM modulation and OFDM demodulation is to adopt the conventional data modulation based on OFDM.For example, when OLT11 will send downlink data to ONU, the one OFDM modulation sending unit can first be converted to the low-speed parallel data with the downlink data of high speed serialization, then parallel data is mapped to a plurality of modulating vectors, carry out again inverse fast Fourier transform, add CP after conversion, do at last parallel serial conversion and digital-to-analogue conversion, can obtain the downlink data after OFDM modulates.Subsequent transmission module 113 is carried on the downlink data after this OFDM modulation on descending light and forms downstream signal, realizes that the signal of telecommunication to the conversion of light signal, is sent to trunk optical fiber and transmits.When OLT11 receives the upward signal of ONU transmission, after the first receiver module carries out opto-electronic conversion, the one OFDM modulation receiving element can first be made analog-to-digital conversion and serial to parallel conversion to upward signal, generation time sample value sequence, remake fast Fourier transform after removing again CP, the vector sequence of conversion gained is made suitable Digital Signal Processing, comprise channel equalization, forward error correction etc., carry out again demodulation, mapping produces parallel data, is reduced into parallel serial conversion the upstream data that serial data namely obtains ONU at last.
Also comprise in described OLT11: first wave division multiplexer 117 and circulator (Circuit) 118; Wherein, first wave division multiplexer 117 is used for downstream signal and wide spectrum optical are carried out multiplexing, and the wave band of downstream signal and wide spectrum optical is different, is L-band as descending signal, and wide spectrum optical is C-band; Circulator 118 is used for the downstream signal after multiplexing and wide spectrum optical are sent to ODN.Described circulator 118 is applicable to the flow direction of control signal, and the signal that enters this circulator 118 can only advance for example according to the direction of arrow shown in Fig. 2 according to a direction; For example, enter from: first wave division multiplexer 117 the port F output that the downstream signal of circulator 118 can only be along the direction of arrow from trunk optical fiber, downstream signal is in trunk optical fiber 14 transmission; The upward signal of the ONU that receives from the port F of trunk optical fiber 14 also can only transfer to the first receiver module 114 downwards along the direction of arrow.
Also comprise in described ODN12: Second Wave division multiplexer 122 and optical splitter 123.Wherein, Second Wave division multiplexer 122 is used for downstream signal and wide spectrum optical demultiplexing, is about to downstream signal and separates with wide spectrum optical, and wide spectrum optical is sent to AWG121; Optical splitter 123 is used for downstream signal and is broadcast to a plurality of ONU, specifically with the downstream signal after described Second Wave division multiplexer 122 demultiplexings, be divided at least one corresponding with at least one optical network unit respectively downstream signal, these a plurality of downstream signals that are divided into are actually the signal of the downlink data that carries respectively corresponding ONU, and described at least one downstream signal correspondence is broadcast at least one ONU, the downstream signal correspondence that is about to carry the downlink data of certain ONU is sent to this ONU.Also comprise in this ODN12: wavelength division multiplexer 124, the multiplexed optical wave after being used for processing with optical splitter 123 by AWG121 is sent to ONU13 with being in the same place.
Also comprise in described ONU13: the second receiver module (Optical Receiver) 133 can receive the downstream signal of optical splitter 123 broadcast transmissions, and this downstream signal is sent to the 2nd OFDM modulation module 131 carries out the OFDM demodulation.The 2nd OFDM modulation module 131 in this ONU13 specifically can comprise: the 2nd OFDM modulation sending unit (OFDM Transmitter) the 134 and the 2nd OFDM modulation receiving element (OFDM Receiver) 135.Wherein, the 2nd OFDM modulation sending unit 134 is used for the upstream data of ONU is carried out the OFDM modulation, and the described upstream data after the OFDM modulation is sent to transmitter module 132 (can be called the second transmitter module); The 2nd OFDM modulation receiving element 135 is used for the downstream signal that the second receiver module 133 receives is carried out the OFDM demodulation, obtains the downlink data corresponding with this ONU.Concrete OFDM modulation and the method for OFDM demodulation are identical with the processing of OLT, repeat no more.
In the present embodiment, transmitter module 132 in ONU13 can be reflection type modulator (ReflectiveModulator, be called for short: R-Mod), this reflection type modulator is for example, reflective semiconductor amplifier (Reflective Semiconductor Optical Amplifier, be called for short: RSOA) or reflective electricity cause the Absorption modulation device (Reflective Electro-Absorption Modulator be called for short: REAM) etc.adopt the advantage of this reflection type modulator to be: each ONU does not need to be defined as the up light wave that must launch specific wavelength, do not limit the emission wavelength of ONU, this transmitter module 132 can be under the effect of the light wave of certain wavelength of correspondence that above-mentioned AWG injects, be described certain wavelength with the wavelength locking of up light wave, be transmitter module 132 be according to the light wave that injects in advance with the wavelength locking of up light wave for wavelength corresponding to this ONU, the mode that this ONU itself does not limit emission wavelength can be called the decolorizable of ONU, ONU is decolorizable to be made when carrying out the deployment of each ONU, do not limited by the wavelength correspondence, make ONU dispose more flexible.
As shown in Figure 2, the ONU13 of the present embodiment can have a plurality of, such as the first ONU, the 2nd ONU, ONU3 etc., only shows the structure of an ONU in Fig. 2, and the structure of other ONU such as the 2nd ONU, ONU3 is identical with an ONU, not shown.
The below is from the workflow of downlink transfer and uplink both direction, and the operation principle of the passive optical network communication system of the present embodiment is described, and wherein, the wavelength of uplink and downlink signal is different, and the downstream signal wavelength is made as λ d, and suppose that 32 ONU are arranged, the wide range light wavelength that wide spectrum light source sends is made as λ u, the upstream signal wavelengths corresponding with 32 ONU respectively that is divided into by AWG is made as λ u1, λ u2..., λ u32
Downlink transfer:
At first, OFDM Transmitter115 in OLT11 carries out the OFDM modulation to the downlink data that will be sent to each ONU, downlink data after modulation is the signal of telecommunication, after being sent to OpticalTransmitter113, Optical Transmitter113 is converted to light signal with this signal of telecommunication, downlink data after specifically modulating is carried on descending light and forms downstream signal, and the wavelength of this downstream signal is λ d
Then, (this wide range light wavelength is λ to the wide spectrum optical that sends of this downstream signal and BLS112 u) multiplexing by first wave division multiplexer 117 together, then enter trunk optical fiber 14 through circulator 118.The ODN12 of trunk optical fiber 14 hops, the downstream signal that above-mentioned process is multiplexing and wide spectrum optical are by Second Wave division multiplexer 122 demultiplexings, and wide spectrum optical is divided into the light wave of 32 separation by AWG121, and its wavelength is respectively λ u1, λ u2..., λ u32, then the reflection type modulator that is injected into respectively 32 ONU is in transmitter module 132, for example, wavelength is λ u1Light wave be injected in the reflection type modulator of an ONU, make the locking each ONU upstream signal wavelengths be respectively λ u1, λ u2..., λ u32, the upward signal of each ONU will be carried on respectively on the light wave of these 32 injection lockings.
Simultaneously, entered in optical splitter (splitter) 123 by the downstream signal that obtains after Second Wave division multiplexer 122 demultiplexings, be broadcast to all ONU by optical splitter 123 again, specifically by wavelength division multiplexer 124, the broadcasting multiplex after AWG121 and optical splitter 123 processing is sent to ONU together afterwards.After the Optical Receiver133 of ONU receives this downstream signal, this downstream signal is carried out opto-electronic conversion, light signal is converted to the signal of telecommunication, and this signal of telecommunication is sent into OFDM Receiver135.OFDMReceiver135 carries out to downstream signal the data that the OFDM demodulation filters out subchannel corresponding to this ONU.From the above, the down direction of this system adopts the mode of TDM+OFDM.
Uplink:
At first, the OFDM Transmitter134 in ONU13 carries out the OFDM modulation with above-mentioned data, and the upstream data after the OFDM modulation is sent to transmitter module (R-Mod) 132.Transmitter module 132 is carried on described upstream data on the light wave that injects in advance and forms upward signal, and the wavelength of this upward signal is the optical wavelength that injects, and for example, the upward signal that the transmitter module 132 of an ONU sends is that wavelength is λ u1On light wave.
Then, up 32 upward signal light waves that each ONU sends are multiplexing by the AWG121 in ODN12, then enter in OLT11 through Second Wave division multiplexer 122, trunk optical fiber 14.The Optical Receiver114 that incides in OLT through the circulator 118 in OLT11 (namely is equivalent to photodetector (Photo Detector is called for short: PD)).This Optical Receiver114 only has one in OLT, it receives the upward signal from all ONU; Wavelength X due to these 32 ONU u1, λ u2..., λ u32Different, do not disturb OBI so can not produce optical beat on Optical Receiver114.Optical Receiver114 carries out opto-electronic conversion to upward signal, and light signal is converted to the signal of telecommunication.
Then, the upward signal of electrical signal form enters in the OFDM Receiver116 of OLT and carries out demodulation, recovers the data in subchannel corresponding to each ONU, and namely up direction adopts the mode of WDM+OFDMA.
Wherein, in the description of the workflow of above-mentioned downlink transfer and uplink, described OFDM modulation or demodulation techniques are such:
OFDM is a kind of multi-carrier modulation technology, its basic thought is channel distribution to be become the subchannel of many quadratures in frequency domain, use a subcarrier to modulate on every sub-channels, subcarrier can adopt Quadrature Phase Shift Keying (Quadrature Phase Shift Keying, be called for short: QPSK), quadrature amplitude modulation (Quadrature Amplitude Modulation, be called for short: QAM) etc. high order modulation improves power system capacity, and each subcarrier parallel transmission, this parallel transmission technology can be with distribution of flows at a high speed to several subcarrier low speed transmissions.OFDM is that with respect to the difference of general multi-carrier transmission its allows subcarrier spectrum to overlap, as long as satisfy mutually orthogonal between subcarrier, can separate data-signal from the subcarrier of aliasing.Because OFDM allows the subcarrier spectrum aliasing, its spectrum efficiency improves greatly, thereby is a kind of efficient modulation system.
Current OFDM sending and receiving mechanism all is based on fast Fourier transform, and (Fast FourierTransform, be called for short: FFT), (Digital Signal Processing, be called for short: DSP) chip is realized with Digital Signal Processing.At transmitting terminal, serial data is at a high speed first become the parallel data of low speed, and then parallel data is mapped to a plurality of modulating vectors, then carries out the multiple spot inverse fast Fourier transform.Add CP after conversion, do at last parallel serial conversion and digital-to-analogue conversion, produce continuous ofdm signal and send to channel.At receiving terminal, first do to received signal analog-to-digital conversion (Analog Digital Conversion, be called for short: ADC) and serial to parallel conversion, generation time sample value sequence, then remake multiple spot fast Fourier transform (FFT) after removing CP.The vector sequence of conversion gained is made suitable Digital Signal Processing, comprise channel equalization, forward error correction etc., then carry out demodulation, mapping produces parallel data, is reduced into serial data with parallel serial conversion at last.
Embodiment three
Fig. 3 is the structural representation of the another embodiment of passive optical network communication system of the present invention, the present embodiment provides again a kind of optional passive optical network communication system structure, the difference of the system configuration in this structure and embodiment two is, the one OFDM modulation module of the present embodiment comprises a plurality of OFDM modulation sending unit OFDM Tx, and the quantity of described the first transmitter module Optical Tx is also a plurality of; An OFDM Tx and an Optical Tx form a transmitter unit, and the quantity of described transmitter unit equates with the quantity of described a plurality of optical network unit ONU.A plurality of described transmitter unit of the present embodiment is used for sending a plurality of downstream signals that carry respectively the downlink data corresponding with ONU, and described downstream signal has the second wave length corresponding with described optical network unit.
As shown in Figure 3, in the OLT of the present embodiment, OFDM Tx and Optical Tx have respectively a plurality of, specifically comprise a plurality of OFDM Tx and the Optical Tx that equate with ONU quantity.For example, if the quantity of ONU has 32, the quantity of this OFDM Tx and Optical Tx also has respectively 32.Each OFDM Tx and transmitter unit corresponding to Optical Tx are used for the downlink data of corresponding one of them ONU is carried out the OFDM modulation, and are carried on the descending light with wavelength corresponding with this ONU, for example the λ in Fig. 3 d1, λ d2Deng, these λ d1, λ d2Deng can all being called second wave length.
The OLT of the present embodiment also comprises: array waveguide grating AWG is sent to described first wave division multiplexer 117 for after a plurality of described downstream signals are multiplexing.
When downlink transfer, in the signal that described 32 OFDM Tx and Optical Tx produce, the wavelength of the light signal of each Optical Tx output is different, for example, and λ d1, λ d2..., λ d32, the light signal of these 32 Optical Tx outputs is the different ONU of correspondence respectively.After will be multiplexing through the AWG in OLT, export the downstream signal after multiplexing, signal wavelength is λ d, this wavelength is λ dDownstream signal and the wide spectrum optical that sends of BLS (this wide range light wavelength is λ u) multiplexing by first wave division multiplexer 117 together, then enter trunk optical fiber 14 through circulator 118.
In ODN12, can not comprise optical splitter (splitter) in the ODN12 of the present embodiment, by AWG121, downstream signal and the wide spectrum optical of above-mentioned trunk optical fiber 14 are cut apart; Concrete is, AWG121 is divided into wide spectrum optical the light wave of 32 separation, and its wavelength is respectively λ u1, λ u2..., λ u32And be the downstream signal that corresponding in OLT 32 OFDM Tx and Optical Tx produce with the downstream signal demultiplexing, each downstream signal after described demultiplexing is together with the wide spectrum optical after cutting apart, and the reflection type modulator that is injected into respectively 32 ONU is in transmitter module 132.For example, wavelength is λ u1Light wave be injected in the reflection type modulator of an ONU, make the locking each ONU upstream signal wavelengths be respectively λ u1, λ u2..., λ u32, the upward signal of each ONU will be carried on respectively on the light wave of these 32 injection lockings.
When uplink, each ONU is carried on upstream data on the light wave that injects in advance and forms upward signal, and up 32 the upward signal light waves that send are multiplexing by the AWG121 in ODN12, enter in OLT11 through trunk optical fiber 14.Circulator 118 in process OLT11 incides the OpticalReceiver114 in OLT, and this Optical Receiver114 only has one in OLT, and it receives the upward signal from all ONU; Wavelength X due to these 32 ONU u1, λ u2..., λ u32Different, do not disturb OBI so can not produce optical beat on Optical Receiver114.Optical Receiver114 carries out opto-electronic conversion to upward signal, and light signal is converted to the signal of telecommunication.The upward signal of electrical signal form enters in the OFDM Receiver116 of OLT and carries out demodulation, recovers the data in subchannel corresponding to each ONU.
Embodiment four
Fig. 4 is the structural representation of optical line terminal embodiment of the present invention, and as shown in Figure 4, this optical line terminal OLT can comprise: wide spectrum light source 41, the first OFDM modulation module 42 and signal emission module 43; Wherein,
Described wide spectrum light source 41 is for generation of the described wide spectrum optical with first wavelength;
Described the first OFDM modulation module 42 is used for the downlink data to described at least one optical network unit to be sent is carried out OFDM modulation; And, be used for and will carry out the OFDM demodulation from the upward signal that at least one optical network unit receives, obtain respectively upstream data corresponding to described at least one optical network unit;
Signal emission module 43 for generation of the descending light with second wave length, and forms downstream signal by the described descending light carrying downlink data through OFDM modulation to described at least one optical network unit to be sent; And described downstream signal and described wide spectrum optical are carried out being sent to described Optical Distribution Network after multiplexing, be sent to respectively at least one optical network unit so that described Optical Distribution Network is divided at least one light wave with described wide spectrum optical, and make described optical network unit by described light wave carrying upstream data.
Optionally, this signal emission module 43 can comprise: the first transmitter module and first wave division multiplexer; The structure of this first transmitter module and first wave division multiplexer can be referring to system embodiment;
Described the first transmitter module for generation of the descending light with second wave length, and forms downstream signal by the described descending light carrying downlink data through OFDM modulation to described at least one optical network unit to be sent;
Described first wave division multiplexer, be used for described downstream signal and described wide spectrum optical are carried out being sent to described Optical Distribution Network after multiplexing, be sent to respectively at least one optical network unit so that described Optical Distribution Network is divided at least one light wave with described wide spectrum optical, and make described optical network unit by described light wave carrying upstream data.
Further, can be referring in system embodiment shown in Figure 3, described the first OFDM modulation module comprises a plurality of the first OFDM modulation transmitting elements, the quantity of described the first transmitter module is a plurality of; Described first an OFDM modulation transmitting element and first transmitter module form a transmitter unit, and the quantity of described transmitter unit equates with the quantity of a plurality of optical network units; A plurality of described transmitter units are used for sending a plurality of downstream signals that carry respectively the downlink data corresponding with described optical network unit, and described downstream signal has the second wave length corresponding with described optical network unit.
Further, can be referring in system embodiment shown in Figure 2, described the first OFDM modulation module comprises first an OFDM modulation transmitting element, and first transmitter module; Described first an OFDM modulation transmitting element and first transmitter module connect to form a transmitter unit;
Described transmitter unit after being used for the downlink data to described at least one optical network unit to be sent is carried out OFDM modulation, all being carried on described descending light with second wave length and forming downstream signal.
The optical line terminal of the present embodiment, by being set, wide spectrum light source produces wide spectrum optical, can be so that optical distribution network can produce the light wave corresponding with ONU by cutting apart this wide spectrum optical, and then make light wave is injected into ONU as the carrying light wave of ONU upstream data, thereby the cost of ONU can be reduced.
Embodiment five
Fig. 5 is the schematic flow sheet of EPON communication means one embodiment of the present invention, and the method is that OLT carries out, and the present embodiment only makes a brief description the method, specifically can be in conjunction with referring to the principle explanation in system embodiment; As shown in Figure 5, the method can comprise:
501, produce the descending light that has the wide spectrum optical of the first wavelength and have second wave length;
502, treat the downlink data that is sent to described at least one optical network unit and carry out OFDM modulation, and the described Deta bearer after modulating forms downstream signal at described descending light;
503, described wide spectrum optical and downstream signal are sent to Optical Distribution Network, be sent to respectively at least one optical network unit so that described Optical Distribution Network is divided at least one light wave with described wide spectrum optical, and make described optical network unit by described light wave carrying upstream data;
504, receive the upward signal that described at least one optical network unit sends, and described upward signal is passed through the OFDM demodulation, obtain respectively upstream data corresponding to described at least one optical network unit.
Further, described generation has the descending light of second wave length, comprising: produce at least one descending light, described at least one descending light has respectively the wavelength corresponding with described at least one optical network unit;
The described downlink data that is sent to described at least one optical network unit for the treatment of carries out OFDM modulation, and the described Deta bearer after modulating comprises at described descending light formation downstream signal:
Treat respectively the downlink data that is sent to described at least one optical network unit and carry out OFDM modulation, and the described data after modulating are carried on respectively at least one descending light corresponding with described optical network unit, form a plurality of downstream signals corresponding with described at least one optical network unit.
Embodiment six
Fig. 6 is the schematic flow sheet of another embodiment of EPON communication means of the present invention, and the method is that ONU carries out, and the present embodiment only makes a brief description the method, specifically can be in conjunction with referring to the principle explanation in system embodiment; As shown in Figure 6, the method can comprise:
601, receive downstream signal and the light wave that optical line terminal sends;
Described downstream signal carries the downlink data through OFDM modulation that described optical line terminal sends, described downlink data is carried on the descending light with second wave length, and described light wave is to cut apart by the wide spectrum optical with first wavelength that described optical line terminal is produced to obtain;
602, described downstream signal is carried out the OFDM demodulation, obtain described downlink data;
603, the upstream data to described optical line terminal to be sent is carried on described light wave, forms upward signal, be sent to described optical line terminal.
The EPON communication means of the present embodiment, ONU cuts apart by the wide spectrum optical that receives the optical line terminal generation light wave that obtains, and is simple with respect to existing techniques in realizing as the light wave of carrying upstream data, reduced the cost of ONU.
Embodiment seven
Fig. 7 is the schematic flow sheet of the another embodiment of EPON communication means of the present invention, and the present embodiment is mainly that angle from system is to this EPON communication means simple declaration.As shown in Figure 7, comprising:
701, the wide spectrum light source in optical line terminal OLT produces the descending light that has the wide spectrum optical of the first wavelength and have second wave length, described OLT forms downstream signal by the described descending light carrying downlink data through OFDM modulation to described at least one optical network unit to be sent, and described wide spectrum optical and downstream signal are sent to Optical Distribution Network ODN;
702, the array waveguide grating AWG in described ODN is divided into corresponding with a plurality of optical network unit ONU respectively a plurality of light waves with described wide spectrum optical, the wavelength of described a plurality of light waves is different, and described a plurality of light waves and described downstream signal are sent to respectively described a plurality of ONU;
703, described ONU carries out the OFDM demodulation to the downstream signal that receives and obtains the downlink data corresponding with described optical network unit; And the upstream data that will be sent to OLT is carried out the OFDM modulation, and the upstream data after the OFDM modulation is carried on from the described light wave of described ODN reception, form upward signal, described upward signal is sent to described ODN;
704, the upward signal that described a plurality of ONU sent by described AWG of described ODN is sent to described OLT after multiplexing;
705, OLT carries out the OFDM demodulation by the upward signal to described a plurality of ONU of receiving, obtains respectively upstream data corresponding to described a plurality of ONU.
One of ordinary skill in the art will appreciate that: all or part of step that realizes above-mentioned each embodiment of the method can be completed by the hardware that program command is correlated with.Aforesaid program can be stored in a computer read/write memory medium.This program is carried out the step that comprises above-mentioned each embodiment of the method when carrying out; And aforesaid storage medium comprises: the various media that can be program code stored such as ROM, RAM, magnetic disc or CD.
It should be noted that at last: above each embodiment is not intended to limit only in order to technical scheme of the present invention to be described; Although with reference to aforementioned each embodiment, the present invention is had been described in detail, those of ordinary skill in the art is to be understood that: it still can be modified to the technical scheme that aforementioned each embodiment puts down in writing, and perhaps some or all of technical characterictic wherein is equal to replacement; And these modifications or replacement do not make the essence of appropriate technical solution break away from the scope of various embodiments of the present invention technical scheme.

Claims (12)

1. a passive optical network communication system, is characterized in that, comprising: optical line terminal, Optical Distribution Network and at least one optical network unit, and described optical line terminal is connected with described at least one optical network unit by Optical Distribution Network;
Described optical line terminal, for generation of the wide spectrum optical with first wavelength and descending light with second wave length, form downstream signal by the described descending light carrying downlink data through OFDM modulation to described at least one optical network unit to be sent, and described wide spectrum optical and downstream signal are sent to described Optical Distribution Network; And, be used for receiving the upward signal that described at least one optical network unit sends, and described upward signal is passed through the OFDM demodulation, obtain respectively upstream data corresponding to described at least one optical network unit;
Described Optical Distribution Network, be used for and be divided at least one corresponding with at least one optical network unit respectively light wave from the wide spectrum optical that described optical line terminal receives, and described at least one light wave and described downstream signal are sent to respectively corresponding described at least one optical network unit; And, be used for being undertaken being sent to described optical line terminal after multiplexing by the upward signal that described at least one optical network unit is sent;
Described at least one optical network unit is used for receiving described downstream signal, and described downstream signal is carried out the OFDM demodulation obtains the downlink data corresponding with described optical network unit; And, the upstream data through OFDM modulation to described optical line terminal to be sent is carried on from the described light wave of described Optical Distribution Network reception, form upward signal, and described upward signal is sent to described Optical Distribution Network.
2. passive optical network communication system according to claim 1, is characterized in that, described optical line terminal specifically comprises: wide spectrum light source and the first OFDM modulation module;
Described wide spectrum light source is for generation of the described wide spectrum optical with first wavelength;
Described the first OFDM modulation module is used for the downlink data to described at least one optical network unit to be sent is carried out OFDM modulation; And, be used for the upward signal that at least one optical network unit that receives sends is carried out the OFDM demodulation, obtain respectively upstream data corresponding to described at least one optical network unit.
3. passive optical network communication system according to claim 2, is characterized in that, described optical line terminal also comprises: the first transmitter module and first wave division multiplexer;
Described the first transmitter module is used for that described the first OFDM modulation module is carried out downlink data after OFDM modulation and is carried on described descending light and forms downstream signal;
Described first wave division multiplexer is used for described downstream signal and described wide spectrum optical are carried out being sent to described Optical Distribution Network after multiplexing;
Described Optical Distribution Network also comprises: the Second Wave division multiplexer;
Described Second Wave division multiplexer is used for described downstream signal and described wide spectrum optical are carried out demultiplexing, so that the described wide spectrum optical of described Optical Distribution Network after to demultiplexing cut apart.
4. passive optical network communication system according to claim 1, is characterized in that, described Optical Distribution Network specifically comprises: array waveguide grating;
Described array waveguide grating is used for the wide spectrum optical that described optical line terminal sends is divided at least one light wave corresponding with at least one optical network unit; And, be used for carrying out multiplexing to the upward signal that described at least one optical network unit sends.
5. passive optical network communication system according to claim 3, is characterized in that, described Optical Distribution Network also comprises: optical splitter;
Described optical splitter, be used for the downstream signal after described Second Wave division multiplexer demultiplexing, be divided at least one corresponding with at least one optical network unit respectively downstream signal, and described at least one downstream signal correspondence is broadcast to described at least one optical network unit.
6. passive optical network communication system according to claim 3, is characterized in that, described the first OFDM modulation module comprises a plurality of the first OFDM modulation transmitting elements, and the quantity of described the first transmitter module is a plurality of; Described first an OFDM modulation transmitting element and first transmitter module form a transmitter unit, and the quantity of described transmitter unit equates with the quantity of described a plurality of optical network units;
A plurality of described transmitter units are used for sending a plurality of downstream signals that carry respectively the downlink data corresponding with described optical network unit, and described downstream signal has the second wave length corresponding with described optical network unit.
7. an optical line terminal, is characterized in that, comprising: wide spectrum light source, the first OFDM modulation module and signal emission module;
Described wide spectrum light source is for generation of the described wide spectrum optical with first wavelength;
Described the first OFDM modulation module is used for the downlink data to described at least one optical network unit to be sent is carried out OFDM modulation; And, be used for and will carry out the OFDM demodulation from the upward signal that at least one optical network unit receives, obtain respectively upstream data corresponding to described at least one optical network unit;
Signal emission module for generation of the descending light with second wave length, and forms downstream signal by the described descending light carrying downlink data through OFDM modulation to described at least one optical network unit to be sent; And described downstream signal and described wide spectrum optical are carried out being sent to described Optical Distribution Network after multiplexing, be sent to respectively at least one optical network unit so that described Optical Distribution Network is divided at least one light wave with described wide spectrum optical, and make described optical network unit by described light wave carrying upstream data.
8. optical line terminal according to claim 7, is characterized in that, described the first OFDM modulation module comprises a plurality of the first OFDM modulation transmitting elements, and the quantity of described the first transmitter module is a plurality of; Described first an OFDM modulation transmitting element and first transmitter module form a transmitter unit, and the quantity of described transmitter unit equates with the quantity of a plurality of optical network units;
A plurality of described transmitter units are used for sending a plurality of downstream signals that carry respectively the downlink data corresponding with described optical network unit, and described downstream signal has the second wave length corresponding with described optical network unit.
9. optical line terminal according to claim 7, is characterized in that, described the first OFDM modulation module comprises first an OFDM modulation transmitting element, and first transmitter module; Described first an OFDM modulation transmitting element and first transmitter module connect to form a transmitter unit;
Described transmitter unit after being used for the downlink data to described at least one optical network unit to be sent is carried out OFDM modulation, all being carried on described descending light with second wave length and forming downstream signal.
10. an EPON communication means, is characterized in that, comprising:
The descending light that generation has the wide spectrum optical of the first wavelength and has second wave length;
Treat the downlink data that is sent to described at least one optical network unit and carry out OFDM modulation, and the described Deta bearer after modulating forms downstream signal at described descending light;
Described wide spectrum optical and downstream signal are sent to Optical Distribution Network, be sent to respectively at least one optical network unit so that described Optical Distribution Network is divided at least one light wave with described wide spectrum optical, and make described optical network unit by described light wave carrying upstream data;
Receive the upward signal that described at least one optical network unit sends, and described upward signal is passed through the OFDM demodulation, obtain respectively upstream data corresponding to described at least one optical network unit.
11. method according to claim 10 is characterized in that, described generation has the descending light of second wave length, comprising: produce at least one descending light, described at least one descending light has respectively the wavelength corresponding with described at least one optical network unit;
The described downlink data that is sent to described at least one optical network unit for the treatment of carries out OFDM modulation, and the described Deta bearer after modulating comprises at described descending light formation downstream signal:
Treat respectively the downlink data that is sent to described at least one optical network unit and carry out OFDM modulation, and the described data after modulating are carried on respectively at least one descending light corresponding with described optical network unit, form a plurality of downstream signals corresponding with described at least one optical network unit.
12. an EPON communication means is characterized in that, comprising:
Receive downstream signal and light wave that optical line terminal sends, described downstream signal carries the downlink data through OFDM modulation that described optical line terminal sends, described downlink data is carried on the descending light with second wave length, and described light wave is to cut apart by the wide spectrum optical with first wavelength that described optical line terminal is produced to obtain;
Described downstream signal is carried out the OFDM demodulation, obtain described downlink data; And the upstream data to described optical line terminal to be sent is carried on described light wave, form upward signal, be sent to described optical line terminal.
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