CN106100737A

CN106100737A - For the method and apparatus sending signal in point-to-point configuration

Info

Publication number: CN106100737A
Application number: CN201610533456.3A
Authority: CN
Inventors: E.戈特瓦尔德; S.斯莫洛尔茨
Original assignee: Xiaoyang Network Co Ltd
Current assignee: Xiaoyang Network Co Ltd; Xieon Networks SARL
Priority date: 2008-12-30
Filing date: 2008-12-30
Publication date: 2016-11-09
Anticipated expiration: 2028-12-30
Also published as: CN106100737B

Abstract

The present invention relates to the method and apparatus for sending signal in point-to-point configuration.Bi-direction data signal is exchanged between center cell and multiple network terminal.The modulator unit (MOD_OLT) of described center cell is by data signal (DS1-DS10) modulation to subcarrier (ω₁-ω₁₀On), generate two optics single sideband singals (LSB) and (USB), and utilize the carrier signal (CW, CWI) through 180 ° of phase shifts to combine two sideband signals.Described optical network unit selects the upward signal that its downstream signal being associated and generation are associated.The frequency of described downstream signal and upward signal be selected such that reflection will not with optical network unit at signals selected disturb, and will not with center cell at received by upward signal disturb.

Description

For the method and apparatus sending signal in point-to-point configuration

The application be national applications number be the divisional application of the application for a patent for invention of 200880132856.7, this patent of invention Filing date in the December, 2008 of application 30 days, invention entitled " for send in point-to-point configuration signal method and Device ".

Technical field

The present invention relates to a kind of method and apparatus (arrangement) for sending signal in point-to-point configuration.

Background technology

Point-to-multipoint delivery network (such as passive optical network (PON)) includes center cell (OLT) and passes through optical fiber The optical network unit (ONU) connected.Usually used as time diversity multiplex (TDM) on the down direction from OLT to ONU Signal sends data signal, and usually used as the burst of time multiplexing on the up direction from ONU to OLT Send data signal.Time division multiplexing on down direction sends to send with the burst mode on up direction needs complexity Time management, and burst mode send cause lower data rate.

Katsuimi Takano, N. Hanzawa, S. Tanji and K. Nakagawa are at " Experimental Demonstration of Optically Phase-Shifted SSB Modulation with Fiber-Based Optical Hubert Transformers", National Fiber Optic Engineers Conference, OSA Technical Digest Series (CD) (Optical Society of America, 2007) , paper JThA48 is described.

Summary of the invention

Therefore, it is an object of the present invention to provide one for utilizing high data with rational cost in the two directions Speed carries out the point-to-point configuration of bi-directional data transmission.

According to the present invention, it is provided that a kind of for sending out between center cell and multiple NE in point-to-point configuration The method sending data signal, wherein has following steps: first group of signal is modulated first group of pair and carries in described center cell On ripple；Institute's modulating subcarrier signal in combination (combine) first group；Second group of signal is modulated to second group of subcarrier On；Combine the institute's modulating subcarrier signal in second group；Generate the lower single-side belt including optical carrier and first group of downstream signal Optical signalling；Generate the upper single-side belt optical signalling (USB) including identical optical carrier and second group of downstream signal；By two Single-side belt (sideband) signal is combined into transmission signal, wherein obtains 180 ° of phase contrasts of their optical carrier signal；Will Described transmission signal is sent to NE；And select in optical network unit and demodulate the downstream signal being associated.

Such modulation reduces implementation cost, and by the combination of single sideband singal with suppressed optical carrier Improve frequency spectrum and power efficiency.

Preferably, described optical network unit generates optics upward signal, and its optical carrier is assigned to received Downstream signal.

It is also advantageous that, the continuous wave light source in described optical network unit is tuned, in order to be associated Downstream signal carries out coherent demodulation and selection, and to determine the carrier frequency of upward signal.

Identical CW frequency is used in ONU to be demodulated the received downstream signal being associated and quilt As the carrier frequency of ONU upward signal, and generated optics upward signal can be readily recognized at OLT.

Advantageously use subcarrier phase or phase contrast modulation, this is because in high receiver sensitivity and ONU The simplicity that upward signal generates.

Described method is suitable to bi-directional data and sends, and wherein sends downstream signal and upward signal by single fiber, and The frequency of downstream signal and the carrier wave of upward signal are selected such that respectively downstream signal and upward signal are being converted into electricity After subband signal (electrical subband signal), reflected signal will not disturb with described signal.

It is improved further in the case of described method is below: the subcarrier of downstream signal and the subcarrier of upward signal Being selected such that after converting the signal into subband signal, the harmonic frequency of described subcarrier signal will not be with other Signal disturbs.

These features avoid the infringement caused due to reflection and harmonic distortion, and allow to carry out height on single fiber Qualitative data sends.

Also provide for one for passing through single fiber between center cell and multiple NE in point-to-point configuration Sending the preferred embodiment of signal, include: first group of subband manipulator in the modulating unit of OLT transmitter, data are believed by it Number modulation is on first group of electricity subcarrier；First combiner, its institute's modulating subcarrier signal is combined into the first subband；Second group Subband manipulator, it is by data signal modulation to second group electricity subcarrier；Second combiner, its institute's modulating subcarrier signal It is combined into the second subband；First single side-band modulator, it receives described first subband and for modulated optical carrier wave and generates First single sideband singal；Second single side-band modulator, its receive described second subband for modulate described optical carrier and Generate the second single sideband singal；Delay element, it generates 180 ° of phase shifts between the carrier wave of described single sideband singal；And addition Device (adder), two single sideband singals are combined into transmission signal by it.

Generation including the single sideband singal of multiple subcarrier signals decreases the workload of technical elements.Additionally, pass through Generate and combine two single sideband singals and in the case of there is no any optical filter eliminate optical carrier reduce into This.

Technical limitations according to blender (hybrid), it may be necessary to apply multiple blender so that for each data Signal individually performs Hilbert conversion, and applies other combiner to combine the equiphase component of described data signal.

Describe other favorable characteristics of described method and apparatus in the dependent claims.

Accompanying drawing explanation

The example of the description present invention including currently preferred embodiment with reference to the accompanying drawings, wherein:

Fig. 1 shows the simplified block diagram of PON system；

Fig. 2 shows the simplification embodiment of the OLT transmitter according to the present invention；

Fig. 3 shows the second embodiment of OLT transmitter；

Fig. 4 shows an embodiment of the generation of the subcarrier in OLT transmitter and modulated signal；

Fig. 5 shows the simplification diagram of optical modulator；

Fig. 6 shows the OLT optical modulation unit of improvement；

Fig. 7 shows the frequency diagram sent by the bi-directional data of single fiber；

Fig. 8 shows the simplification embodiment of ONU transceiver；

Fig. 9 shows the sub-bands of frequencies figure in the electrical domain (electrical domain) of different ONU；

Figure 10 shows the simplification embodiment of OLT transceiver；

Figure 11 shows the sub-bands of frequencies figure in the electrical domain of OLT；And

Figure 12 shows an embodiment of advanced person (advanced) OLT.

Detailed description of the invention

Fig. 1 shows the passive optical network PON of an example as point-to-point configuration.Center cell OLT(optics Line terminal) it is directly connected to multiple optical network unit ONU1-ONU10 or is attached thereto by Metropolitan Area Network (MAN) MN.Each ONU It is connected to common optical fiber FI by deconcentrator (line-splitter) LSP.For the bi-directional data between OLT and each ONT Transmission generally uses one or two optical fiber FI.Each ONU passes through OLT and communicates with each other.

Fig. 2 shows the modulating unit MOD_OLT of OLT transmitter, and it includes subcarrier modulator (such as phase-modulator PM1-PM10), continuous wave source LA and two single side-band modulators SSM_L and SSM_U.First group of data signal DS1-DS5 It is modulated onto subcarrier ω₁、ω₃、…、ω₉On.Combine institute's modulating subcarrier by power divider or wavelength division multiplexer COL to believe Number DB1, DB3 ..., DB9, and obtained lower subcarrier band (lower subcarrier-band) SBL is fed to One single side-band modulator SSM_L.Second group of data signal DS6-DS10 is modulated onto subcarrier ω₂、ω₄、…、ω₁₀On.Logical Cross combiner COU and combine institute modulating subcarrier signal DB2, DB4 ..., DB10, and upper subcarrier band SBU is fed to the Two single side-band modulators SSM_U.

Optical carrier signal CW(carrier frequency f is generated by continuous wave source (laser instrument) LA_C) and be fed to two Single side-band modulator.Optics single side-band modulator SSM_L generates different single sideband singals with SSM_U, i.e. includes that odd number pair carries The lower sideband signal LSB of ripple signal and the upper side band signal USB including even sub-carriers signal.One sideband signals is (such as USB) 180 ° of (phase shift) the most described carrier signal are postponed by (tunable) delay line or phase shifter TD.Subsequently in adder Two sidebands are combined into double-side band by (power divider) AD and send signal DST.It is important that the carrier wave of two sideband signals Having the phase contrast of 180 ° between CW and CWI, carrier power is reduced to be substantially zero by this.

Fig. 3 shows second embodiment of the modulating unit MOD2_OLT utilizing each subcarrier blender H1, H3 .... Illustrate only the device for generating lower sideband LSB.Convert according to Hilbert, from institute modulating subcarrier signal DB1-DB9 Derive and there is modulated signal component SBL_0 ° of 90 ° of phase shifts and SBL_90 °.By two other combiner COM11 and COM12 group Close all modulated signals with same phase component.Obtained subband signal component SBL_0 ° and the SBL_90 ° of lower pair of representative Carrier frequency band SBL.Two obtained modulated signal components SBL_0 ° and SBL_90 ° all by as modulated signal SBL_0 ° and SBL_90 ° is fed to the first single side-band modulator SSM-L for modulation carrier signal CW.

Described single side-band modulator has Mach-Zehnder interferometer structure.Such as obtained by different bias voltages Obtain the necessary phase contrast between the optical carrier signal in the upper and lower branch of described single side-band modulator.

Subband SBU on generating in identical device, and it is added into lower subband by adder AD.

Of course, it is possible to application generates all common methods of single sideband singal.About the present invention, it is important that by identical Continuous wave light source (mainly lasing light emitter) provides the optical carrier of two single side-band modulators, and adds the phase contrast of 180 °. Its result is to eliminate optical carrier, so that signal energy is only contained in the portions of the spectrum of carry information, and for For having the general modulation of relatively low modulation index, most of energy will be comprised in carrier wave.

Fig. 4 shows for generating electricity subcarrier and another OLT modulating unit MOD3_OLT of modulated signal.First by Data signal DS1-DS10 is modulated from common electrical subcarrier signal ω by manipulator PM1-PM10_ECEach subcarrier derived On.Subsequently institute's modulation signal feeds to other manipulator M1-M10(frequency mixer, multiplier or frequency converter), and By applying different conversion signal ω_CO1-10It is changed.Subcarrier signal DB1-is exported from wave filter FI1-FI10 DB10.Combiner COL and COU combines each subcarrier signal as previously mentioned.Blender HL and HU receives each subcarrier band, and And export modulated signal I through phase shift, Q according to Hilbert conversion.

Fig. 5 shows the simplification embodiment of optical modulator, and it has the first separator receiving continuous wave signal CW (splitter) SP1, electrical modulation signal u1, u2 two optical branchings BR1, the BR2 controlled, and the institute of combination Liang Ge branch Second separator SP2(combiner of modulated optical signal).

Inferior division BR2 includes for carrying out correct phase-adjusted delay line DL.Also by applying different biased electrical Pressure obtains the phase shift of time delay.

Derive in general form now by the function of SBL_0 ° and the SBL_90 ° single side-band modulator driven.Index (index) k refers to the signal of single-side belt.Wherein m-modulation index (for N=10, about < 0.06), ω-base band angular frequency, s- Modulated signal (symbol), the t-time:

The modulated signal obtained in top set BR1 is:

(1)

Inferior division BR2 is:

(2).

The electric field of the continuous glistening light of waves carrying out self-excitation light source is following (for simplicity by amplitude set to 1):

(3).

Therefore obtain in top set BR1:

(4)

And obtain in branch 2:

(5)

θ=90 ° are obtained:

(6).

Utilize following addition theorem:

We are accurately obtained in branch 1:

(9)

, and by small signal approximation (m < < 1):

(10).

Inferior division BR2 is accurately obtained:

(11),

And by small signal approximation (m < < 1):

(12).

The superposition (small signal approximation) of field causes:

(13)

ByWith

, obtain:

(14).

Therefore we are in upper angular frequency_c+ω_kPlace obtains having modulation s_kThe phase-modulated wave of (t).Carrier wave is, and institute's modulating part of E field is:

(15).

In the case of θ=270 °, we are at lower corner frequency ω_c-ω_kPlace obtains having modulation s_kThe phase-modulated wave of (t).

Fig. 6 shows the OLT modem devices MOA_OLT including two single side-band modulators SSM_L and SSM_U.

Electricity subcarrier band SBL, SBU are broken down into two signals through 90 ° of phase shifts, itself and modulated signal u1, u2 It is consistent.

Here, top set includes delay line TD, and it causes the carrier phase of between single sideband singal 180 °.

Power control member PC1 and delay control PHC and are inserted in top set.Inferior division includes that the second power controls unit Part PC2.Each optical modulator SSM_L and SSM_U include correcting electrode CE1, the CE2 added, and each receive self-regulated System controls correction signal SC1 and SC2 of (not shown).Described correction signal can also be added in modulated signal.

According to (9) and (11), it describe accurately does not has the signal in the case of small signal approximation to generate, and output signal has There are 2 times and the distortion of more high order.Can correct these distortions in the first approximation, this is from being used for approximation (10) by application (12) more high order extension (higher order expansion) the sufficient correction signal derived of small signal approximation and Realize.

(16).

Fig. 7 shows the frequency diagram of the optical signalling bi-directionally sent by single fiber.For example, for descending and/or Upward signal can apply phase place or phase contrast phase-modulation.The optics downstream signal D1-D10 of descending transmission signal DST carries The information of subcarrier signal DB1-DB10.In this embodiment, the most only send 10 signals, and at up direction 10 signal U1-U10 of upper transmission.According to Fig. 2, the downstream signal D1 of lower subband, D3 ... carry odd-numbered 1,3 ..., 9, and The downstream signal D2 of upper side band, D4 ... carry even-numbered 2,4 ..., 10.Upper part shows "UpWavelength-division multiplexSend out The number of delivering letters" the upward signal U1-U10 being associated of UST.In order to allow to be easily identified and for technical reasons, they It is arranged near the down channel being associated, it will be explained below.The optical carrier frequency of descending transmission signal DST f_COptical carrier frequency f with upward signal_ONU1-f_ONU10Show the frequency relation of described signal.Reflected signal is by horizontal line Represent.

Select special channel separation (frequency distance between adjacent channel) n Δ (n=3,4) for two reasons.First It it is the infringement in order to avoid causing due to reflection.Next to that cause in order to avoid the harmonic wave due to the carrier wave of electronic band signal Infringement (Fig. 9, Figure 11).The frequency distance of downstream signal D1 and D2 and upward signal U1 and U2 is 4 Δs.It is also possible that 6 Δ、8Δ、….Every other channel be adjacent the spacing of channel (such as CH4 and CH6) be 3 Δs (and 6 Δs, 9 Δs, 12 Δ ...), wherein minimum delta=(1.2-1.5) BW(BW-sends signal DST bandwidth).If channel separation is more than minimum spacing 3 Δ, 4 Δs, then can accept the higher frequency tolerance limit of channel.

Fig. 8 shows the block diagram of ONU transceiver RX_ONT, and it includes the balance cross polarization for coherent demodulation (polarisation) diversity receiver CRX, tunable laser TL(continuous wave light source) and ONU transmitter TX_ONU.? Hamacher, M., Heidrich H., Kruger, U., Stenzel, R., Bauer, J.G., Albrecht, H.'s “Coherent receiver front-end module including a polarization diversity waveguide OIC and a high-speed InGaAs twin-dual p-i-n photodiode OEIC both Based on InP ", IEEE Photonics Technology Letters 4 (1992), Nr.11, S.1234-7; ISSN:1041-1135 describes described coherent receiver.

Described cross polarization diversity receiver CRX_ONU is by will be independent of reception signal and the laser signal ω of polarization_ONU Descending transmission signal DST is changed in superposition.Received transmission signal is converted into downlink electrical subband DSB.Laser frequency quilt Be tuned to preset frequency, such as f_ONU1.Subsequently specific downstream signal (such as D1) is converted into its frequency logical corresponding to band (bandpath) electronic signal of frequency.Described downstream electrical signals is selected by wave filter and identifying unit FD, and other signals and Component is then blocked.

The modulation for optics upward signal (such as U1) and amplification is performed in ONU transmitter TX_ONU.By identical Tunable laser signal ω_ONU1(respectively about all of ONU: carrier frequency f_ONU1-f_ONU10) be fed to optical modulator MO with As carrier signal, it is modulated by upstream data. signals US1.By separator LSP(Fig. 1) by up for the optics of each ONU letter Number it is combined into up transmission signal UST.

Control unit CON_ONU controls tunable laser TL.Therefore, it can by via controlling what bus CB received ONU is adapted to each down channel by control information.Laser frequency can be higher or lower than signals selected optical carrier frequency Rate.It is likely in both cases with transmitter, the identical laser signal divided by separator SP is used for receptor.

Fig. 9 shows four electronic band frequency spectrums of ONU1-ONU4.Spectrum intensity is depicted as frequencies/channels spacing f/ Δ Function.About an ONU 1(upper left), received descending transmission signal DST is converted into descending subband DSS1(telecommunications Number frequency spectrum；Upper left).The labelling D1-D10 of downstream signal is also used for the electronic band signal during ONU receives.It is being converted into electronics After band signal, the first optics downstream signal D1 corresponding to the first subband down channel CHD1 and is selected by band filter BP Select；The every other downstream signal of two sidebands and the reflecting part RU1-RU10 of upward signal U1-U10 are by described band Pass filter blocks.Other of Fig. 9 diagrammatically show the electronic band frequency spectrum of descending subband DSS2-DSS4.These different frequency spectrums It is by utilizing different frequencies f_ONU2-f_ONU10Change the downstream signal received in ONU2-ONU4 and obtain (figure 6).Here, selected signal is always assigned to identical descending sub-band channel CHD1.In every other ONU, institute The downstream signal received is converted into similar subband signal.For the sake of clarity, before illustrate only in these illustrate 10 channels (corresponding to the numeral of f/ Δ).

Figure 10 shows the simplification embodiment of the OLT including receptor RX_OLT and transmitter TX_OLT.Up transmission is believed The received upward signal U1-U10 of number UST is also converted into up electricity by balance cross polarization diversity receiver CRX_ONT Subband signal USS.Optics OLT carrier signal CW is also used for this conversion.Subsequently in processing unit PU (such as with telecommunications Wave filter is passed through after number mixing) separate up electronic band signal U1-U10, and it is fed to single digit receiver RX1-RX10 is to regain upstream data. signals US1-US10.

OLT transmitter TX_OLT consists essentially of the modulating unit and amplifier having been noted above.

Figure 11 shows the electric frequency spectrum of the upward signal received by the OLT after being converted into up electronic band USS. The labelling U1-U10 of upward signal is also used for the signal of telecommunication of OLT subband.All reflecting part RD1-RD10 of downstream signal Falling at each up subband signal USS(, it corresponds to U1-U10) between.Such as filtered by the different RX-BP of described processing unit Ripple device separate sub-band channel CHU1,3,4,6 ..., the up subband signal USS received in CHU15.

Figure 12 shows an embodiment of the OLT_A of advanced networks.Owing to the channel number of every CW is for physical cause And be restricted, multiple transmitter TX1_OLT-TX32_OLT(is set the most in the olt and each generates double-side band transmission Signal DST1-DST32).Combined each output signal DST1-DST32 by wavelength division multiplexer MUX and pass through circulator (circulator) CI sends.

From the upgoing wave division multiplex signal UST1-UST32 received by circulator CI output, and demultiplexed by wavelength-division It is de-multiplexed into into subcarrier multiplexing with device (wavelength division demultiplexer) DMUX and sends signal UST1-UST32.In OLT receptor RX_OLT1-RX_OLT32, these are sent each in the middle of signal to be concerned with Demodulation, and convert thereof into up electronic band (USS in such as Figure 11).It is subsequently isolated each upward signal and respectively by it Export or be sent to another ONU.

The invention is not restricted to the details of principle described above.It is intended that the scope of the present invention be defined by the claims appended hereto, And therefore the present invention should comprise to fall being changed and revising in the range of the equivalents of claims.Particularly at energy In the case of enough obtaining high speed processor with reasonable prices, analog data can be substituted with Digital data processing and process.

Reference

OLT-center cell (optical line terminals)

ONU-optical line units

MN-Metropolitan Area Network (MAN)

FI-optical fiber

LSP-separator

MOD_OLT-modulating unit

DS1, DS2 ...-first, second data signal

PM1, PM2 ...-first, second phase-modulator

DB1, DB2 ...-first, second subcarrier signal

ω₁, ω₂...-subcarrier

CO1, CO2-first, second combiner

Subcarrier band under SBL-

The upper subcarrier band of SBU-

LA-continuous wave light source/laser instrument

The continuous glistening light of waves/the carrier signal of CW-

CWI-is through the carrier signal of anti-phase (inverted)/phase shift

ω_CThe angular frequency of-CW

LSB-lower sideband

USB-upper side band

AD-adder

DL-time delay

DST-(double-side band) descending transmission signal

MOD2_OLT-the second modulating unit

H1, H2 ...-first, second blender (Hilbert wave filter)

COM11, COM12 ...-other combiner

SBL_0 °, SBL_90 °-through the subcarrier band of phase shift

MOD3_OLT-the 3rd modulating unit

ω_EC-common electrical carrier signal

ω_CO1-10-conversion signal

FI1-FI10 the first-the ten wave filter

DB1-DB10 subcarrier signal (SBL+SBU)

U1-the first modulated signal

U2-the second modulated signal

BR1-top set

BR2-inferior division

SP1, SP2-first, second separator

DL-delay line

E1 (t) the-the first electric field

E2 (t) the-the second electric field

∑ E-field summation

MD-carrier delay line

MOA_OLT-OLT modulating device

HL-the first blender (Hilbert wave filter)

HU-the second blender (Hilbert wave filter)

CE1-the first correcting electrode

CE2-the second correcting electrode

PC1, PC2-first, second power control member

PHC-phase controlling

SPC-CW separator

SC1, SC2-first, second correction signal

D1, D2 ...-first, second downstream signal

U1-U10 first, second upward signal

D1-D10 downstream signal

DST-descending transmission signal

UST-up transmission signal

RX_ONU-ONU receptor

TX_ONU-ONU transmitter

FD-wave filter and identifying unit

TL-tunable laser

ω_ONU-optics ONU carrier wave

f_ONU-ONU optical carrier frequency

SPL-laser signal separator

CON_ONU-ONU control unit

CB-controls bus

U1, U2-first, second up (data) signal

The reflection of RU1-the first up channel

The reflection of RU2-the second up channel

DSS1-DSS4 downlink sub-channels ONU1-ONU4

RX_OLT-OLT cross polarization diversity receiver

PD-processes and identifying unit

TX_OLT-OLT transmitter

PU-receptor processing unit

RX1-RX10-digit receiver

LA-CW source

The up subband of USS-(signal)

CW1-CW32 1-32.CW source

TX1-TX32 1-32. transmitter

RX1-RX32 1-32. receptor

MUX-wavelength division multiplexer

DMUX-Wave decomposing multiplexer

CI-circulator

DST1-DST32 1-32 descending transmission signal

Claims

1. the method bidirectionally sending multiple optical signalling via single fiber,

Plurality of optics downstream signal (D1-D10) sends and multiple optics upward signal (U1-in the downstream direction U10) send in the upstream direction,

Wherein, the frequency difference between two contiguous downstream signals (D1, D2) in described downstream signal is 2 n Δ, wherein n=2,3,4 ..., and

Frequency difference between every other adjacent downstream signal is 3 k Δ, wherein k=1,2,3 ....

Method the most according to claim 1, wherein, Δ is equal to 1.2-1.5 times of the bandwidth of downstream transmission signals (D1-D10).

3. the interchannel that the down channel (D1-D10) that according to the method for claim 1 or 2, wherein, utilizes be associated is identical Away from sending upward signal (U1-U10).

4., according to the method for aforementioned claim any one, wherein send optics downstream signal (D1-from optical line terminals D10) to multiple optical network units, and wherein said optics upward signal (U1-U10) is sent out from the plurality of NE Deliver to described optical line terminals.

Method the most according to claim 4, the most each optical network unit uses the same laser separated by separator Signal is to send its corresponding upward signal (U1-U10) and receiving corresponding downstream signal (D1-D10).