CN106533643B - The method and system that optical modulator bandwidth is adjusted - Google Patents
The method and system that optical modulator bandwidth is adjusted Download PDFInfo
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- CN106533643B CN106533643B CN201510586674.9A CN201510586674A CN106533643B CN 106533643 B CN106533643 B CN 106533643B CN 201510586674 A CN201510586674 A CN 201510586674A CN 106533643 B CN106533643 B CN 106533643B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/003—Arrangements for allocating sub-channels of the transmission path
- H04L5/0058—Allocation criteria
- H04L5/006—Quality of the received signal, e.g. BER, SNR, water filling
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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
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
- H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
- H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
- H04B10/0795—Performance monitoring; Measurement of transmission parameters
- H04B10/07953—Monitoring or measuring OSNR, BER or Q
Abstract
The invention discloses the method and system being adjusted to optical modulator bandwidth, wherein, this method comprises: test transmitting terminal determine optical modulator using bandwidth, it is arranged and meets and electric signal modulation can be carried out to each subcarrier using all subcarriers of the orthogonal frequency division multiplex OFDM electric signal of amount of bandwidth；OFDM electric signal after carrying out electric signal modulation treatment is sent to optical modulator by test transmitting terminal, then is transferred to test receiving end by optical fiber；Test receiving end carries out demodulation process to the OFDM optical signal received, each subcarrier of treated OFDM electric signal is subjected to bit error rate detection respectively, judge whether to meet bit error rate requirement, if be unsatisfactory for, the adjustment distribution of power bit then is carried out to corresponding subcarrier, returns and executes the step of OFDM electric signal after carrying out electric signal modulation treatment is sent to optical modulator by the test transmitting terminal.The present invention program can be extended the bandwidth of optical modulator, improve bandwidth utilization efficiency.
Description
Technical field
The present invention relates to optical communication techniques, more particularly to the method and system that optical modulator bandwidth is adjusted.
Background technique
In optical communication technique, in transmitting terminal, electric signal is modulated into optical signal by optical modulator, is transferred to reception by optical fiber
End, the optical signal that receiving end receives need to meet bit error rate requirement.Under the premise of meeting bit error rate requirement, the band of optical modulator
Wide utilization rate is higher, then service efficiency is higher.
Currently, what is transmitted by optical modulator is mostly single-carrier signal, the characteristics of according to single-carrier signal, to optical modulator
The extension of bandwidth availability ratio is restricted, and light modulation bandwidth cannot be made to reach biggish utilization efficiency.Below with passive optical network
It is specifically described for the use of optical modulator in (PON, Passive Optical Network).
Access net is the bridge that user enters Metropolitan Area Network (MAN) and backbone network, is the information transfer channel " last one kilometer ".Nothing
Source optical-fiber network is considered as the key technology for solving access net bottleneck.Because passive optical network is that optical transport is real using passive device
The Optical Access Network of existing point-to-multipoint, high reliablity, price is low, convenient for installation and maintenance.But transmission bandwidth still restricts letter
The paces for ceasing high speed development, how to effectively utilize bandwidth is always the target that scientific research person pursues.Modulation bandwidth 10GHz at present
Optical modulator based on MZI is the commercial devices in access net system, is modulated using the optical modulator to single-carrier signal
Transmission, within modulation bandwidth 10GHz, the frequency response decaying of optical modulator is very slow, however if signal frequency is more than
The modulation bandwidth of 10GHz, frequency response exponentially decay, it is, being considered as the optical modulator bandwidth other than 10GHz
It is unserviceable.
To sum up, in existing scheme, transmission is modulated to single-carrier signal by optical modulator, to optical modulator bandwidth benefit
It is restricted with the extension of rate, light modulation bandwidth cannot be made to reach biggish utilization efficiency.
Summary of the invention
The present invention provides the method that a kind of pair of optical modulator bandwidth is adjusted, this method can be to the band of optical modulator
Width is extended, and improves bandwidth utilization efficiency.
The present invention provides the system that a kind of pair of optical modulator bandwidth is adjusted, which can be to the band of optical modulator
Width is extended, and improves bandwidth utilization efficiency.
The method that a kind of pair of optical modulator bandwidth is adjusted, this method comprises:
Test transmitting terminal determine optical modulator using bandwidth；
It tests transmitting terminal setting and meets orthogonal frequency division multiplexing (OFDM, the Orthogonal that can utilize amount of bandwidth
Frequency Division Multiplexing) electric signal all subcarriers, to each subcarrier carry out electric signal modulation,
The electric signal modulation includes carrying out the distribution of power bit, and the modulation format and transmission power of each subcarrier is arranged；
OFDM electric signal after carrying out electric signal modulation treatment is sent to optical modulator by test transmitting terminal, will be via light tune
The modulated OFDM optical signal of device processed is transferred to test receiving end by optical fiber；
Test receiving end carries out demodulation process to the OFDM optical signal that receives, by each son of treated OFDM electric signal
Carrier wave carries out bit error rate detection respectively, judges whether to meet bit error rate requirement, if conditions are not met, then carrying out function to corresponding subcarrier
The adjustment distribution of rate bit returns to the execution test transmitting terminal and is sent to the OFDM electric signal after carrying out electric signal modulation treatment
The step of optical modulator；If it is satisfied, then the corresponding power bit distribution of currently each subcarrier, which is determined as meeting, can utilize band
The distribution information that width requires.
The system that a kind of pair of optical modulator bandwidth is adjusted, the system include test transmitting terminal and test receiving end, institute
Stating test transmitting terminal includes optical modulator；
The test transmitting terminal, determine optical modulator using bandwidth；The OFDM for meeting and can utilizing amount of bandwidth is set
All subcarriers of electric signal carry out electric signal modulation to each subcarrier, and the signal modulation includes carrying out the distribution of power bit,
The modulation format and transmission power of each subcarrier are set；OFDM electric signal after progress electric signal modulation treatment is sent to light tune
Device processed will be transferred to test receiving end by optical fiber via the OFDM optical signal after light modulator modulates；It is also used to receive and
Information is distributed from the adjustment of the test receiving end, carries out the adjustment point of power bit to each subcarrier according to adjustment distribution information
Match；
The test receiving end carries out demodulation process to the OFDM optical signal that receives, will treated OFDM electric signal
Each subcarrier carry out bit error rate detection respectively, judge whether to meet bit error rate requirement, if conditions are not met, then to corresponding subcarrier
The adjustment distribution of power bit is carried out, adjustment distribution information is sent to the test transmitting terminal；If it is satisfied, then will current each son
The corresponding power bit distribution of carrier wave is determined as meeting the distribution information that can utilize bandwidth requirement.
From above scheme as can be seen that in the present invention, test transmitting terminal determine optical modulator using bandwidth after, setting
Electric signal modulation, the telecommunications can be carried out to each subcarrier using all subcarriers of the OFDM electric signal of amount of bandwidth by meeting
Number modulation include carry out the distribution of power bit, the modulation format and transmission power of each subcarrier are set；Transmitting terminal is tested via light
OFDM optical signal after modulators modulate is transferred to test receiving end by optical fiber；Test receiving end is believed by the OFDM light received
Number demodulation process is carried out, each subcarrier of treated OFDM electric signal is subjected to bit error rate detection respectively, judges whether to meet
Bit error rate requirement returns to the execution test and sends if conditions are not met, then carrying out the adjustment distribution of power bit to corresponding subcarrier
End will be allocated that treated the step of electric signal is sent to optical modulator；If it is satisfied, then current each subcarrier is corresponded to
Power bit distribution be determined as meet can utilize bandwidth requirement distribution information.Using the present invention program, optical modulator is used
There is the ofdm signal of multiple subcarriers in transmission, and provide the concrete scheme for determining each sub-carrier power bit distribution, lead to
It crosses to each subcarrier flexible allocation power bit, to meet bit error rate requirement, also, under the premise of meeting bit error rate requirement,
Optical modulator bandwidth is extended as much as possible, and then improves bandwidth utilization efficiency.
Detailed description of the invention
Fig. 1 is the method schematic flow chart that the present invention is adjusted optical modulator bandwidth；
Fig. 2 is frequency response-power relation schematic diagram of the single carrier of light modulator modulates；
Fig. 3 is the method flow diagram example that the present invention is adjusted optical modulator bandwidth；
Fig. 4 is the system structure diagram that the present invention is adjusted optical modulator bandwidth；
Fig. 5 is the ber curve schematic diagram of corresponding different signal-to-noise ratio for different modulating format；
Fig. 6 is that the present invention carries out the ideal characterisitics effect picture example after power bit is assigned；
Fig. 7 is the spectrum waveform schematic diagram that present invention OFDM finally determining after adaptively debugging emits signal；
Fig. 8 is that the present invention carries out the actual characteristic effect picture example after power bit is assigned；
Fig. 9 is the planisphere and bit error rate schematic diagram example that various pieces subcarrier demodulation in receiving end of the present invention goes out.
Specific embodiment
To make the objectives, technical solutions, and advantages of the present invention clearer, below with reference to embodiment and attached drawing, to this
Invention is further described.
In existing scheme, transmission is modulated to single-carrier signal by optical modulator, to optical modulator bandwidth availability ratio
Extension it is restricted, light modulation bandwidth cannot be made to reach biggish utilization efficiency.In order to solve the technical problem, the present invention is combined
Optical modulator is used for transmission ofdm signal by the characteristic of ofdm signal；Subcarrier can be neatly distributed when transmitting ofdm signal
Power and modulation format, frequency range lower for frequency response can distribute the modulation lattice of higher power and lower-order
Formula to reach the required bit error rate, and then extends optical modulator bandwidth.
Referring to Fig. 1, the method schematic flow chart that optical modulator bandwidth is adjusted for the present invention comprising following step
It is rapid:
Step 101, test transmitting terminal determine optical modulator using bandwidth.
This is using bandwidth workable for the reality that bandwidth is optical modulator.
It is equally illustrated with the optical modulator in background technique based on MZI, when transmitting single carrier in existing scheme
Bandwidth be 10GHz.Optical modulator based on MZI is limited with bandwidth, within the modulation bandwidth of optical modulator, frequency response
It is relatively flat, decay very slow；Other than modulation bandwidth, frequency response exponentially decays.It referring to fig. 2, is light modulator modulates
The frequency response (Frequency) of single carrier-power (Power) relation schematic diagram, in figure, ordinate power (Power) is to connect
Receiving end receives reception power when carrier signal, and ordinate has also corresponded to the frequency response decaying of carrier signal；Abscissa frequency
The frequency for the single carrier that (Frequency) is indicated through light modulator modulates is responded, it is current that abscissa has also corresponded to optical modulator
Application bandwidth.As seen from Figure 2, within modulation bandwidth 10GHz, the frequency response decaying of optical modulator is very slow, in 10GHz
Frequency response decays quickly other than bandwidth.For single-carrier signal, the bandwidth applications of optical modulator 10GHz.
And ofdm signal is made of the adjustable mutually orthogonal subcarrier of quantity, the modulation format and power of each subcarrier
Distribution is mutually indepedent.Therefore, if it is frequency response compared with the subcarrier of the low-frequency range distribution modulation format of lower-order and higher
Transmission power, it is possible to reach required bit error rate requirement, to improve the utilization rate of modulator bandwidth.
The present invention utilizes this characteristic of ofdm signal, and the bandwidth usage of the optical modulator of existing 10GHz is arrived
16GHz, to effectively improve transmission rate.Specifically, the present invention is guaranteeing wanting for the bit error rate using the scheme of automatic adjusument
It asks down highland as far as possible to improve rate, and has been bandwidth 16GHz, rate 88.8Gbit/s, the DD-OFDM for transmitting 20-km SSMF
System experimentation demonstrates the solution of the present invention.
It is 16GHz using bandwidth it is, being directed to the example, which is greater than application bandwidth when single carrier transmission.
Step 102, the setting of test transmitting terminal meets the institute that can utilize the orthogonal frequency division multiplex OFDM electric signal of amount of bandwidth
There is subcarrier, electric signal modulation is carried out to each subcarrier, the electric signal modulation includes carrying out the distribution of power bit, and each son is arranged
The modulation format and transmission power of carrier wave.
Know using all subcarriers that after amount of bandwidth, can determine OFDM electric signal.Specifically, due to each
The bandwidth of subcarrier is it has been determined that generally identical value, then knows using after amount of bandwidth, it may be determined that bandwidth can be utilized out by meeting
The number of all subcarriers of size, and then determine to constitute the subcarrier of ofdm signal.
Then, electric signal modulation is carried out to each subcarrier, electric signal modulation is before optical modulator input carrier signal
Basic step, including: carry out the distribution of power bit, the modulation format and transmission power of each subcarrier are set.
Step 103, the OFDM electric signal after carrying out electric signal modulation treatment is sent to optical modulator by test transmitting terminal, will
Test receiving end is transferred to by optical fiber via the OFDM optical signal after light modulator modulates.
Received OFDM electric signal is modulated to optical signal by optical modulator.
Step 104, test receiving end carries out demodulation process to the OFDM optical signal that receives, will treated OFDM telecommunications
Number each subcarrier carry out bit error rate detection respectively, judge whether to meet bit error rate requirement, if conditions are not met, then to corresponding sub- load
Wave carries out the adjustment distribution of power bit, returns to step 103；If it is satisfied, then by the currently corresponding power ratio of each subcarrier
Spy's distribution is determined as meeting the distribution information that can utilize bandwidth requirement.
After receiving OFDM optical signal, demodulation process is carried out to it, is the basic operation of receiving end, including by optical signal
Be converted to electric signal.
Bit error rate detection is carried out to each subcarrier, currently existing scheme realization can be used, specifically, binding test transmitting terminal hair
The original OFDM optical signal sent, is compared with the OFDM optical signal after demodulation, calculates the bit error rate.Whether judge each subcarrier
Meet bit error rate requirement, if conditions are not met, then carrying out the adjustment distribution of power bit to corresponding subcarrier, return to step 103,
To recycle transport stream signal journey above-mentioned, until meeting bit error rate requirement；If it is satisfied, then current each subcarrier is corresponded to
The distribution of power bit be determined as meeting and the distribution Information application can then be arrived using the distribution information of bandwidth requirement
In actual light modulator modulates transmitting scene.
In the present invention, test transmitting terminal determine optical modulator using bandwidth after, setting meet can utilize amount of bandwidth
OFDM electric signal all subcarriers, electric signal modulation is carried out to each subcarrier, electric signal modulation includes carrying out power
Bit distribution, is arranged the modulation format and transmission power of each subcarrier；Transmitting terminal is tested via the OFDM after light modulator modulates
Optical signal is transferred to test receiving end by optical fiber；Test receiving end carries out demodulation process to the OFDM optical signal received, will
Each subcarrier of treated OFDM electric signal carries out bit error rate detection respectively, judges whether to meet bit error rate requirement, if not
Meet, then the adjustment distribution of power bit is carried out to corresponding subcarrier, return, which executes the test transmitting terminal, will be allocated processing
The step of electric signal afterwards is sent to optical modulator；If it is satisfied, then will currently distribute really the corresponding power bit of each subcarrier
It is set to the distribution information for meeting and can utilizing bandwidth requirement.Using the present invention program, optical modulator is used for transmission with multiple sons
The ofdm signal of carrier wave, and the concrete scheme for determining each sub-carrier power bit distribution is provided, by flexible to each subcarrier
Distribution power bit extends light tune to meet bit error rate requirement, also, under the premise of meeting bit error rate requirement as much as possible
Device bandwidth processed, and then improve bandwidth utilization efficiency.
In the process of Fig. 1, the modulation format and transmission power of each subcarrier is arranged in step 102 test transmitting terminal, such as in advance
The modulation format of all subcarriers first is set as most high-order, transmission power may be configured as identical value, this is one specific
The initial setting up of implementation, modulation format and transmission power can determine as needed.
It correspondingly, will be to corresponding son in step 104 when test receiving end, which tests out the subcarrier bit error rate, to be unsatisfactory for requiring
Carrier wave carries out the adjustment distribution of power bit, and the bit error rate can all be reduced by increasing transmission power and reducing modulation format；It specifically, can be only
Transmission power is adjusted, only modulation format can also be debugged, it is also possible that simultaneously to transmission power and modulation format
It is adjusted.Citing is illustrated, and can reduce the modulation format of corresponding subcarrier, for example, modulation format is reduced level-one；It can also
To increase the transmission power of corresponding subcarrier, for example, transmission power is increased level-one；It is also possible that reducing the tune of corresponding subcarrier
Format processed, and increase the transmission power of corresponding subcarrier.
Below by the process of Fig. 3, the method being adjusted to the present invention to optical modulator bandwidth is illustrated,
The following steps are included:
Step 301, test transmitting terminal determine optical modulator using bandwidth, 16GHz.
Step 302, the setting of test transmitting terminal meets the institute that can utilize the orthogonal frequency division multiplex OFDM electric signal of amount of bandwidth
There is subcarrier.
Step 303, test transmitting terminal carries out electric signal modulation, the electric signal modulation to each subcarrier of OFDM electric signal
Including carrying out the distribution of power bit, set identical for the transmission power of each subcarrier, and all by the modulation format of each subcarrier
It is set as most higher order modulation formats.
Step 304, the OFDM electric signal after carrying out electric signal modulation treatment is sent to optical modulator by test transmitting terminal, will
Test receiving end is transferred to by optical fiber via the OFDM optical signal after light modulator modulates.
Step 305, test receiving end carries out demodulation process to the OFDM optical signal that receives, will treated OFDM telecommunications
Number each subcarrier carry out bit error rate detection respectively.
Step 306, test receiving end judges whether each subcarrier meets bit error rate requirement, if conditions are not met, then will be corresponding
The modulation format of subcarrier reduces level-one, and transmission power is increased level-one, returns to step 304；If it is satisfied, then will work as
The corresponding power bit distribution of preceding each subcarrier is determined as meeting the distribution information that can utilize bandwidth requirement.
Referring to fig. 4, system optical modulator bandwidth being adjusted for the present invention, which is characterized in that the system includes surveying
Transmitting terminal and test receiving end are tried, the test transmitting terminal includes optical modulator；
The test transmitting terminal, determine optical modulator using bandwidth；The OFDM for meeting and can utilizing amount of bandwidth is set
All subcarriers of electric signal carry out electric signal modulation to each subcarrier, and the signal modulation includes carrying out the distribution of power bit,
The modulation format and transmission power of each subcarrier are set；OFDM electric signal after progress electric signal modulation treatment is sent to light tune
Device processed will be transferred to test receiving end by optical fiber via the OFDM optical signal after light modulator modulates；It is also used to receive and
Information is distributed from the adjustment of the test receiving end, carries out the adjustment point of power bit to each subcarrier according to adjustment distribution information
Match；
The test receiving end carries out demodulation process to the OFDM optical signal that receives, will treated OFDM electric signal
Each subcarrier carry out bit error rate detection respectively, judge whether to meet bit error rate requirement, if conditions are not met, then to corresponding subcarrier
The adjustment distribution of power bit is carried out, adjustment distribution information is sent to the test transmitting terminal；If it is satisfied, then will current each son
The corresponding power bit distribution of carrier wave is determined as meeting the distribution information that can utilize bandwidth requirement.
It tests transmitting terminal and electric signal modulation is carried out to each subcarrier, specifically may include following processing: carrying out power bit point
Match, IFFT processing, IF Modulation, digital to analogy conversion process, etc..
Test receiving end carries out demodulation process to the OFDM optical signal received, specifically may include following processing: photoelectricity turns
Change processing, analog to digital conversion process, intermediate frequency demodulation processing, FFT processing, binary bit sequence demodulation process, etc..
Preferably, the test transmitting terminal includes base band OFDM signal generation module, IF Modulation module, random waveform hair
Raw device (AWG, Arbitrary Waveform Generator) and optical modulator, the base band OFDM signal generation module include
Modulates baseband signals module and Fourier transformation IFFT module, test receiving end includes amplifier, photodetector, real-time oscillography
Device, intermediate frequency demodulation module, base band OFDM signal demodulation module and error code detection module, the base band OFDM signal demodulation module packet
Include modulation demodulation module and inverse Fourier transform FFT module；
The modulates baseband signals module, determine optical modulator using bandwidth, setting, which meets, can utilize amount of bandwidth
OFDM electric signal all subcarriers, to each subcarrier carry out the distribution of power bit, be arranged each subcarrier modulation format and
Transmission power；OFDM electric signal after allocation processing is sent to the IFFT module；
The IFFT module receives the OFDM electric signal from the modulates baseband signals module, by the OFDM electricity of frequency domain
Signal generates the OFDM electric signal of time domain by Fourier transformation, and transformed OFDM electric signal is sent to IF Modulation mould
Block；
The IF Modulation module receives the OFDM electric signal from the IFFT module, after carrying out IF Modulation processing,
It is sent to the AWG；
The AWG receives the OFDM electric signal from the IF Modulation module, and OFDM electric signal is carried out number and arrives mould
The conversion of quasi- signal, is sent to the optical modulator for the analog signal after conversion；
OFDM electric signal from the AWG is converted to OFDM optical signal, OFDM optical signal is led to by the optical modulator
It crosses optical fiber and is transferred to the amplifier；
The amplifier receives OFDM optical signal by optical fiber, after amplifying to optical signal, is sent to the photoelectricity and visits
Survey device；
The photodetector carries out photoelectric conversion to OFDM optical signal, the OFDM electric signal after conversion is sent to institute
State real-time oscilloscope；
The real-time oscilloscope carries out the conversion of analog to digital signal to OFDM electric signal, by the OFDM electricity after conversion
Signal is sent to the if demodulator；
The intermediate frequency demodulation module receives the OFDM electric signal from the real-time oscilloscope, carries out intermediate frequency demodulation, will solve
OFDM electric signal after tune is sent to the FFT module；
The FFT module receives the OFDM electric signal from the intermediate frequency demodulation module, carries out inverse Fourier transform, will
Transformed OFDM electric signal is sent to the modulation demodulation module；
The modulation demodulation module receives the OFDM electric signal from the FFT module, is demodulated, obtained
The binary bit sequence of each subcarrier of OFDM electric signal, is sent to the error code detection module；
The error code detection module carries out bit error rate detection to each subcarrier of OFDM electric signal respectively, judges whether full
Sufficient bit error rate requirement sends adjustment distribution information if conditions are not met, then carrying out the adjustment distribution of power bit to corresponding subcarrier
To the modulates baseband signals module；If it is satisfied, then the corresponding power bit distribution of currently each subcarrier is determined as meeting
Using the distribution information of bandwidth requirement；
The modulates baseband signals module receives the adjustment from the error code detection module and distributes information, according to adjustment
It distributes information and the distribution of power bit is carried out to each subcarrier, the modulation format and transmission power of each subcarrier are set；By adjustment point
With treated, OFDM electric signal is sent to the IFFT module.
IF Modulation module carries out IF Modulation processing to OFDM electric signal, and IF Modulation processing is Conventional processing steps,
Specifically include the intermediate frequency ofdm signal that the base band OFDM signal of plural number is converted to real number.
Intermediate frequency demodulation module carries out intermediate frequency demodulation processing to OFDM electric signal, and intermediate frequency demodulation processing is Conventional processing steps,
Specifically include the base band OFDM signal that the intermediate frequency ofdm signal of real number is restored to plural number.
Modulation demodulation module demodulates OFDM electric signal, obtains 0101 sequence of each subcarrier, that is,
Binary bit sequence.
The amplifier can be specially to mix bait image intensifer.
Preferably, the test transmitting terminal, when the modulation format of each subcarrier is arranged, specifically, by all subcarriers
Modulation format is set as most high-order.
Preferably, the test receiving end specifically, reduces when carrying out the adjustment distribution of power bit to corresponding subcarrier
The modulation format of corresponding subcarrier.
Preferably, the test receiving end specifically, increases when carrying out the adjustment distribution of power bit to corresponding subcarrier
The transmission power of corresponding subcarrier.
Preferably, the test receiving end specifically, reduces when carrying out the adjustment distribution of power bit to corresponding subcarrier
The modulation format of corresponding subcarrier, and increase the transmission power of corresponding subcarrier.
Optical modulator of the present invention can be specially the optical modulator based on ZMI.
Fig. 5 indicates to be directed to different modulating format, the bit error rate (BER) curve of corresponding different signal-to-noise ratio (Eb/No), abscissa
Eb/No is signal-to-noise ratio, and ordinate is the bit error rate.It is assumed that bit error rate requirement is 10-3, in order to improve system to the maximum extent
Transmission rate (namely improves the bandwidth of optical modulator) as far as possible, this example is directed to the channel selection of different signal-to-noise ratio from Fig. 5
Different modulation formats meets maximum transmission rate, it is, the modulation format to each subcarrier is adaptively adjusted
It is whole, to determine the modulation format for meeting peak transfer rate.Modulation format in figure includes 4QAM to 128QAM more.
Fig. 6, which gives, carries out the ideal characterisitics effect picture after power bit is assigned, and abscissa indicates transmitted signal
Frequency, ordinate indicates signal-to-noise ratio, and ordinate also illustrates schematically frequency response；It is shown in figure, each subcarrier is carried out
After the distribution of power bit, for the different frequency range of signal transmission, the sub-carrier selection higher order modulation formats of high frequency, low frequency
Sub-carrier selection low-order-modulated format, also, the corresponding signal-to-noise ratio of high frequency modulated format subcarrier and frequency response are higher, and it is low
The corresponding signal-to-noise ratio of contrast format subcarrier and frequency response are lower.
The ofdm signal bandwidth modulated in specific test of the invention is 16GHz, and IFFT length is 2048,2 times of over-samplings,
Subcarrier number is 1310, is transmitted by 20km standard single-mode fiber, power and bit allocation scheme through the invention, altogether
Using 11 kinds of modulation formats, the subcarrier number distribution of different modulating format from low to high is followed successively by 128QAM:
569,64QAM:131,48QAM:95,32QAM:148,24QAM:60；16QAM:118；12QAM:80,8QAM:26；6QAM:21,
4QAM:31,2QAM:31.The spectrum waveform of OFDM finally determining transmitting signal is shown in Fig. 7, always after adaptively debugging
Rate is 88.8Gbit/s.Fig. 8, which gives, carries out the actual characteristic effect picture after power bit is assigned, and abscissa indicates institute
The frequency of signal, i.e. carrier frequency are transmitted, ordinate indicates signal-to-noise ratio；It shows in figure and is accordingly adjusted under the test each frequency range in receiving end
The signal-to-noise ratio of the subcarrier of format processed.Compared with Fig. 6, the two is similar, that is to say, has reached ideal characterisitics effect.Fig. 9
The planisphere and the bit error rate gone out for receiving end various pieces subcarrier demodulation.Various pieces subcarrier after finally debugging
The bit error rate has all reached 10-3(numerical value below each planisphere is the corresponding bit error rate, such as 9.99e-04 is below
0.000999), meet system requirements.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Within mind and principle, any modification, equivalent substitution, improvement and etc. done be should be included within the scope of the present invention.
Claims (12)
1. the method that a kind of pair of optical modulator bandwidth is adjusted, which is characterized in that this method comprises:
Test transmitting terminal determine optical modulator using bandwidth；Described using bandwidth includes bandwidth other than modulation bandwidth；
It tests transmitting terminal setting and meets all subcarriers that can utilize the orthogonal frequency division multiplex OFDM electric signal of amount of bandwidth, to each
Subcarrier carries out electric signal modulation, and the electric signal modulation includes carrying out the distribution of power bit, and the modulation lattice of each subcarrier are arranged
Formula and transmission power；
OFDM electric signal after carrying out electric signal modulation treatment is sent to optical modulator by test transmitting terminal, will be via optical modulator
Modulated OFDM optical signal is transferred to test receiving end by optical fiber；
Test receiving end carries out demodulation process to the OFDM optical signal that receives, by each subcarrier of treated OFDM electric signal
Bit error rate detection is carried out respectively, judges whether to meet bit error rate requirement, if conditions are not met, then carrying out power ratio to corresponding subcarrier
Spy's adjustment distribution returns to the execution test transmitting terminal for the OFDM electric signal after carrying out electric signal modulation treatment and is sent to light tune
The step of device processed；If it is satisfied, then the corresponding power bit distribution of currently each subcarrier to be determined as meeting and can be wanted using bandwidth
The distribution information asked.
2. the method as described in claim 1, which is characterized in that the modulation format of each subcarrier of setting includes: will be all
The modulation format of subcarrier is set as most high-order.
3. method according to claim 1 or 2, which is characterized in that described to carry out the adjustment point of power bit to corresponding subcarrier
With including:
Reduce the modulation format of corresponding subcarrier.
4. method as claimed in claim 3, which is characterized in that the modulation format for reducing corresponding subcarrier includes:
The modulation format of corresponding subcarrier is reduced into level-one.
5. the method as described in claim 1, which is characterized in that described to carry out power bit adjustment distribution packet to corresponding subcarrier
It includes: increasing the transmission power of corresponding subcarrier.
6. the method as described in claim 1, which is characterized in that described to carry out power bit adjustment distribution packet to corresponding subcarrier
It includes: reducing the modulation format of corresponding subcarrier, and increase the transmission power of corresponding subcarrier.
7. the system that a kind of pair of optical modulator bandwidth is adjusted, which is characterized in that the system includes test transmitting terminal and test
Receiving end, the test transmitting terminal includes optical modulator；
The test transmitting terminal, determine optical modulator using bandwidth；Described using bandwidth includes other than modulation bandwidth
Bandwidth；It is arranged and meets and electric signal modulation can be carried out to each subcarrier using all subcarriers of the OFDM electric signal of amount of bandwidth,
The signal modulation includes carrying out the distribution of power bit, and the modulation format and transmission power of each subcarrier is arranged；It will carry out telecommunications
OFDM electric signal after number modulation treatment is sent to optical modulator, will pass through light via the OFDM optical signal after light modulator modulates
Fibre is transferred to test receiving end；It is also used to be distributed to receive and distribute information from the adjustment of the test receiving end according to adjustment
The adjustment that information carries out power bit to each subcarrier distributes；
The test receiving end carries out demodulation process to the OFDM optical signal that receives, by each of treated OFDM electric signal
Subcarrier carries out bit error rate detection respectively, judges whether to meet bit error rate requirement, if conditions are not met, then carrying out to corresponding subcarrier
Adjustment distribution information is sent to the test transmitting terminal by the adjustment distribution of power bit；If it is satisfied, then will current each subcarrier
Corresponding power bit distribution is determined as meeting the distribution information that can utilize bandwidth requirement.
8. system as claimed in claim 7, which is characterized in that the test transmitting terminal includes that base band OFDM signal generates mould
Block, IF Modulation module, arbitrary waveform generator AWG and optical modulator, the base band OFDM signal generation module includes base band
Signal modulation module and Fourier transformation IFFT module, test receiving end include amplifier, photodetector, real-time oscilloscope,
Intermediate frequency demodulation module, base band OFDM signal demodulation module and error code detection module, the base band OFDM signal demodulation module include
Modulation demodulation module and inverse Fourier transform FFT module；
The modulates baseband signals module, determine optical modulator using bandwidth, setting meets can be using amount of bandwidth
All subcarriers of OFDM electric signal carry out the distribution of power bit to each subcarrier, the modulation format and hair of each subcarrier are arranged
Penetrate power；OFDM electric signal after allocation processing is sent to the IFFT module；
The IFFT module receives the OFDM electric signal from the modulates baseband signals module, by the OFDM electric signal of frequency domain
The OFDM electric signal that time domain is generated by Fourier transformation, is sent to IF Modulation module for transformed OFDM electric signal；
The IF Modulation module receives the OFDM electric signal from the IFFT module, after carrying out IF Modulation processing, sends
To the AWG；
The AWG receives the OFDM electric signal from the IF Modulation module, and OFDM electric signal is carried out digital to analogy letter
Number conversion, the analog signal after conversion is sent to the optical modulator；
OFDM electric signal from the AWG module is converted to OFDM optical signal, OFDM optical signal is led to by the optical modulator
It crosses optical fiber and is transferred to the amplifier；
The amplifier receives OFDM optical signal by optical fiber, after amplifying to optical signal, is sent to the photodetection
Device；
The photodetector carries out photoelectric conversion to OFDM optical signal, the OFDM electric signal after conversion is sent to the reality
When oscillograph；
The real-time oscilloscope carries out the conversion of analog to digital signal to OFDM electric signal, by the OFDM electric signal after conversion
It is sent to the if demodulator；
The intermediate frequency demodulation module receives the OFDM electric signal from the real-time oscilloscope, intermediate frequency demodulation is carried out, after demodulation
OFDM electric signal be sent to the FFT module；
The FFT module receives the OFDM electric signal from the intermediate frequency demodulation module, carries out inverse Fourier transform, will convert
OFDM electric signal afterwards is sent to the modulation demodulation module；
The modulation demodulation module receives the OFDM electric signal from the FFT module, is demodulated, and obtains OFDM electricity
The binary bit sequence of each subcarrier of signal, is sent to the error code detection module；
The error code detection module carries out bit error rate detection to each subcarrier of OFDM electric signal respectively, judges whether to meet and miss
Adjustment distribution information is sent to institute if conditions are not met, then carrying out the adjustment distribution of power bit to corresponding subcarrier by code rate requirement
State modulates baseband signals module；It can benefit if it is satisfied, then the corresponding power bit distribution of currently each subcarrier is determined as satisfaction
With the distribution information of bandwidth requirement；
The modulates baseband signals module receives the adjustment from the error code detection module and distributes information, distributed according to adjustment
Information carries out the distribution of power bit to each subcarrier, and the modulation format and transmission power of each subcarrier is arranged；At adjustment distribution
OFDM electric signal after reason is sent to the IFFT module.
9. system as claimed in claim 7, which is characterized in that the modulation format of each subcarrier is arranged in the test transmitting terminal
When, specifically, the modulation format of all subcarriers is set as most high-order.
10. system as claimed in claim 7, which is characterized in that the test receiving end carries out power ratio to corresponding subcarrier
When spy's adjustment distribution, specifically, the modulation format of corresponding subcarrier is reduced.
11. system as claimed in claim 7, which is characterized in that the test receiving end carries out power ratio to corresponding subcarrier
When spy's adjustment distribution, specifically, increase the transmission power of corresponding subcarrier.
12. system as claimed in claim 7, which is characterized in that the test receiving end carries out power ratio to corresponding subcarrier
When spy's adjustment distribution, specifically, the modulation format of corresponding subcarrier is reduced, and increase the transmission power of corresponding subcarrier.
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