CN105049124B - Double hairs suitable for DDO-OFDM are the same as collecting/transmitting system and its transmitting terminal - Google Patents
Double hairs suitable for DDO-OFDM are the same as collecting/transmitting system and its transmitting terminal Download PDFInfo
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- CN105049124B CN105049124B CN201510456963.7A CN201510456963A CN105049124B CN 105049124 B CN105049124 B CN 105049124B CN 201510456963 A CN201510456963 A CN 201510456963A CN 105049124 B CN105049124 B CN 105049124B
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Abstract
The present invention, which provides a kind of receiving terminal, can obtain double hairs suitable for DDO OFDM of smaller decline with collecting/transmitting system and its transmitting terminal.The light carrier that transmitting terminal light carrier of the present invention generates unit output is two beam different center frequency laser, the photodetector of receiving terminal receives the electric signal of the optical signal output two-way different frequency of two-way different center frequency simultaneously, and digital signal processor realizes that power fading is complementary by being superimposed the two paths of signals that photodetector exports.The present invention modulates identical ofdm signal in transmitting terminal dual wavelength, is then transmitted in same root optical fiber, receiving terminal carries out opto-electronic conversion with photodetector.Since the decline of signal power is related to optical carrier wavelength, therefore, the different centre wavelength modulated signals received emergent power at different frequency point declines, so that complementation is realized in respective decline position after superposition, to the total transmission performance of lifting system, frequency selective fading caused by dispersion is effectively antagonized.
Description
Technical field
The present invention relates to optical communication techniques, more particularly to the frequency selective fading of signal is received in fibre-optic transmission system (FOTS)
Compensation technique.
Background technology
In general, the fibre core of the single mode optical fiber used in optical fiber telecommunications system is relatively thin (9/125), transmission band
Width, capacity are big, and transmission range is longer.With the increasing of transmission range, the dispersion of accumulation can cause symbol delay so as to cause frequency
Rate Selective intensity.Multimode fibre fibre core is thick (50/125 or 62.5/125), and multiple patterns is allowed to be transmitted in a fiber, but
It is the transmission range and bandwidth that intermode dispersion limits multimode fibre, and chromatic dispersion in multimode fibre and intermode dispersion are same
Sample can cause symbol to be delayed, and then lead to frequency selective fading.Orthogonal frequency division multiplex OFDM technology have excellent resisting chromatic dispersion and
Frequency selective fading ability.
Current fibre-optic transmission system (FOTS) proposes the various fibre-optic transmission system (FOTS)s based on OFDM modulation techniques.Wherein, it is based on straight
The orthogonal frequency division multiplexing DDO-OFDM systems for connecing detection light, have the advantages that structure design is simple, at low cost, make it have more
Wide application field has especially shown expected effect in terms of short distance single mode fiber link and multimode fibre transmission.
In traditional Linear Mapping DDO-OFDM systems, the signal spectrum of transmitter output end is the OFDM frequencies of double-side band
The additional light carrier of linearly duplication of spectrum, the double-sideband signal transmitted in a fiber at this time can equally bring chromatic dispersion problem.Through
The power of double sideband modulation signal is the cosine function of optical carrier wavelength, dispersion, transmission range etc. after direct detection.As light carries
The position of the change of wave wavelength, dispersion, transmission range etc., signal power decline point also changes correspondingly, and causes the choosing of different frequency
Selecting property declines, as shown in Figure 1.
In order to improve system transmission performance, existing method is that dispersion compensation is added, such as high dispersion compensating fiber technology, Zhou
It sings and optical fiber grating dispersion compensation technique, dispersion compensating filter and front/rear sets dispersion compensation technology etc..These modes both increased
System overall cost, also increases the insertion loss of system, or increase the technical sophistication degree of system.In short distance and low
Generally dispersion compensation technology is not used in cost transport system.
Invention content
The technical problem to be solved by the invention is to provide a kind of receiving terminals can obtain the reception signal of smaller decline
DDO-OFDM transmitting terminals and double comprising the transmitting terminal send out collecting/transmitting system same.
The present invention to solve above-mentioned technical problem the technical scheme adopted is that suitable for DDO-OFDM transmitting terminal, packet
It includes OFDM signal and generates unit, optical modulator, light carrier generation unit, the ofdm signal generates unit
Output end is connected with the modulated signal input terminal of light I/Q modulators, and light carrier generates the output end and light I/Q modulators of unit
Carrier signal input terminal is connected, and the modulated signal output end of light I/Q modulators is connected with optical fiber；
It is characterized in that, the light carrier that the light carrier generates unit output is two beam different center frequency laser.
Double suitable for DDO-OFDM send out collecting/transmitting system same, including above-mentioned transmitting terminal, receiving terminal, optical fiber, and transmitting terminal is logical
Optical fiber is crossed with receiving terminal to be connected；Receiving terminal includes photodetector, digital signal processor, the input terminal and light of photodetector
Fibre is connected, and the output end of photodetector is connected with digital signal processor input terminal, and photodetector believes the light received
Number carry out direct detection；
The photodetector of the receiving terminal receives the optical signal output two-way different frequencies of two-way different center frequency simultaneously
The electric signal of rate, digital signal processor realize that power fading is complementary by being superimposed the two paths of signals that photodetector exports.
The present invention modulates identical ofdm signal in transmitting terminal dual wavelength, is then transmitted in same root optical fiber,
Receiving terminal carries out opto-electronic conversion with photodetector.Since the decline of signal power is related to optical carrier wavelength, it receives
Different centre wavelength modulated signals at different frequency point emergent power decline so that respective decline position realization after superposition
Complementation effectively antagonizes frequency selective fading caused by dispersion to the total transmission performance of lifting system.
The invention has the advantages that compared with existing DDO-OFDM systems, do not increase Digital Signal Processing additionally
Under DSP complexities, it is not necessarily to dispersion compensation module, realizes the performance boost of frequency selective fading lower channel, so that it is guaranteed that receiving
Signaling protein14-3-3 quality.
Description of the drawings
Fig. 1 is existing Single wavelength modulating system received signal power distribution map.
Fig. 2 is invention Transmission system transmitting terminal signal spectrum figure.
Fig. 3 is Transmission system received signal power distribution map of the present invention.
Fig. 4 (a), (b) are the system block diagram of two kinds of different form of light source in embodiment.
Specific implementation mode
It is of the invention double to send out collecting/transmitting system same, including transmitting terminal, receiving terminal, optical fiber, transmitting terminal pass through optical fiber and receiving terminal
It is connected；
Transmitting terminal includes that OFDM signal generates unit, light orthogonal I/Q modulators, light carrier generation in the same direction
Unit, the output end that the ofdm signal generates unit are connected with the modulated signal input terminal of light I/Q modulators, and light carrier generates
The output end of unit is connected with the carrier signal input terminal of light I/Q modulators, the modulated signal output end and light of light I/Q modulators
Fibre is connected；The light carrier that light carrier generates unit output is two beam different center frequency laser, and the frequency interval of 2 wavelength lasers can
With according to actual test to the priori of frequency selective fading be configured.
Receiving terminal includes photodetector, and photodetector is connected with optical fiber, and photodetector is to the optical signal that receives
Carry out direct detection.
In dual wavelength modulation transmission system of the present invention, to modulate phase with the optical wavelength at the intervals about 100GHz in transmitting terminal
For same ofdm signal, then modulated signal spectrum in same optical fiber as shown in Fig. 2, be transmitted, in receiving terminal
Directly opto-electronic conversion is carried out with photodetector.At this point it is possible to system is regarded as to the superposition of the signal after two single-carrier modulateds,
Due to optical carrier wavelength difference so that modulated signal is differed in the decline point of high band, in respective decline after superposition
Complementation is realized on position, to promote overall performance, the results are shown in Figure 3.Due to dispersion, the signal on different carrier waves can be undergone
Different time delays can do corresponding compensation deals in the DSP of receiver.And modulated using OFDM, it will make this compensation
Processing becomes a kind of special circumstances as Multipath Transmission, becomes simpler.
In order to realize that following two forms can be used in the transmitting terminal of dual wavelength modulation：
Scheme one：
As shown in Fig. 4 (a), it includes 2 single-mode lasers, couplers that light carrier, which generates unit, 2 single-mode lasers it is defeated
Outlet is connected with the input terminal of coupler, the laser of the different center frequency of 2 single-mode lasers output.Here single-mode laser
Device is using adjustable single mode band isolation laser device.
As light source, output laser frequency differs about 100GHz, exports laser rays two adjustable single mode band isolation laser devices
Width is relatively narrow；
The laser that two adjustable single modes are exported with isolation laser device is coupled through three-dB coupler；
The laser of three-dB coupler output is connected with light I/Q modulator, and the radiofrequency signal of light I/Q modulator is Waveguide array light
The OFDM radiofrequency signals of grid AWG outputs；
The modulated signal exported from light I/Q modulator enters single mode/multimode fibre SMF/MMF and is transmitted；
The other end of single mode/multimode fibre is connected with photoelectric detector, is directly detected；
Photoelectric detector output end is connected with digital signal processor, completes the transfer functions such as demodulation, the judgement of signal.
Scheme two：
As shown in Fig. 4 (b), it is two-frequency laser that light carrier, which generates unit,.
Currently, two-frequency laser is widely used in the technical fields such as millimeter wave and optical interference measurement.It is common double
Frequency laser is the He-Ne lasers based on longitudinal Zeeman effect, and frequency difference is less than 3MHz, is called small frequency difference, and birefringence is double
Frequency laser frequency difference is more than 40MHz, is called large frequency-difference.Compared with He-Ne lasers, Nd: the gain bandwidth one of YAG laser
As be 150GHz~180GHz, become research hotspot, and various countries' researcher has proposed a variety of double frequency Nd in succession:
YAG laser research approach.It is arrived in addition, existing distributed feedback double-bus network double frequency semiconductor laser can get tens GHz
The very-large frequency difference of GHz up to a hundred, and frequency difference is tunable, and this makes it possible two-frequency laser applied to fiber optic communication.
Use very-large frequency difference two-frequency laser as light source, two-frequency laser exports the laser of two beam frequency interval number 100GHz
As light carrier, two beam laser linewidths of output are relatively narrow；
Two-frequency laser is connected with light I/Q modulator, and the radiofrequency signal of light I/Q modulator is the ofdm signal of AWG outputs；
The modulated signal exported from light I/Q modulator enters single mode/multimode fibre and is transmitted；
The other end of single mode/multimode fibre is connected with photoelectric detector, is directly detected；
Photoelectric detector output end is connected with digital signal processor, completes the transfer functions such as demodulation, the judgement of signal.
Claims (8)
1. suitable for the transmitting terminal of DDO-OFDM, including OFDM signal generates unit, optical modulator, light carrier
Unit is generated, the output end that the ofdm signal generates unit is connected with the modulated signal input terminal of optical modulator, light carrier production
The output end of raw unit is connected with the carrier signal input terminal of optical modulator, modulated signal output end and the optical fiber phase of optical modulator
Even；
It is characterized in that, the light carrier that the light carrier generates unit output is two beam different center frequency laser；
Two beam different center frequency laser light carriers that the optical modulator is exported with light carrier-generation unit are modulated from OFDM
The same ofdm signal of signal generation unit output.
2. being suitable for the transmitting terminal of DDO-OFDM as described in claim 1, which is characterized in that it is double that the light carrier, which generates unit,
Frequency laser.
3. being suitable for the transmitting terminal of DDO-OFDM as described in claim 1, which is characterized in that the light carrier generates unit and includes
2 single-mode lasers, couplers, the output end of 2 single-mode lasers are connected with the input terminal of coupler, 2 single-mode lasers
The laser of the different center frequency of output.
4. being suitable for the transmitting terminal of DDO-OFDM as claimed in claim 3, which is characterized in that the single-mode laser is adjustable list
Mould band isolation laser device.
5. double suitable for DDO-OFDM send out collecting/transmitting system same, including transmitting terminal, receiving terminal, optical fiber, transmitting terminal pass through optical fiber
It is connected with receiving terminal；
The transmitting terminal includes that OFDM signal generates unit, optical modulator, light carrier generation unit, described
The output end that ofdm signal generates unit is connected with the modulated signal input terminal of optical modulator, and light carrier generates the output end of unit
It is connected with the carrier signal input terminal of optical modulator, the modulated signal output end of optical modulator is connected with optical fiber；
Receiving terminal includes photodetector, digital signal processor, and the input terminal of photodetector is connected with optical fiber, photodetection
The output end of device is connected with the output end of digital signal processor, and photodetector directly visits the optical signal received
It surveys；
It is characterized in that, the light carrier that the light carrier generates unit output is two beam different center frequency laser；
Two beam different center frequency laser light carriers that the optical modulator is exported with light carrier-generation unit are modulated from OFDM
The same ofdm signal of signal generation unit output；
The photodetector of the receiving terminal receives the optical signal output two-way different frequency of two-way different center frequency simultaneously
Electric signal, digital signal processor realize that power fading is complementary by being superimposed the two paths of signals that photodetector exports.
6. sending out collecting/transmitting system same suitable for the double of DDO-OFDM as claimed in claim 5, which is characterized in that the light carrier produces
Raw unit is two-frequency laser.
7. sending out collecting/transmitting system same suitable for the double of DDO-OFDM as claimed in claim 5, which is characterized in that the light carrier produces
Raw unit includes 2 single-mode lasers, couplers, and the output end of 2 single-mode lasers is connected with the input terminal of coupler, 2
The laser of the different center frequency of single-mode laser output.
8. sending out collecting/transmitting system same suitable for the double of DDO-OFDM as claimed in claim 7, which is characterized in that the single-mode laser
Device is adjustable single mode band isolation laser device.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510456963.7A CN105049124B (en) | 2015-07-30 | 2015-07-30 | Double hairs suitable for DDO-OFDM are the same as collecting/transmitting system and its transmitting terminal |
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| CN201510456963.7A CN105049124B (en) | 2015-07-30 | 2015-07-30 | Double hairs suitable for DDO-OFDM are the same as collecting/transmitting system and its transmitting terminal |
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| CN105049124A CN105049124A (en) | 2015-11-11 |
| CN105049124B true CN105049124B (en) | 2018-08-21 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106788735B (en) * | 2016-12-12 | 2019-03-05 | 南京理工大学 | Tunable true delay experimental provision and method based on discrete chirped fiber grating |
| CN113162724A (en) * | 2020-01-23 | 2021-07-23 | 中国移动通信有限公司研究院 | Optical signal transmission method, device and equipment |
| CN111342899B (en) * | 2020-03-23 | 2022-09-06 | 电子科技大学 | Optical fiber conjugate phase-stable transmission method |
| CN114296033B (en) * | 2021-12-23 | 2024-02-27 | 中国电子科技集团公司第十四研究所 | Light-operated receiving beam forming method and device |
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| CN102033053A (en) * | 2010-11-12 | 2011-04-27 | 浙江理工大学 | Method and device for measuring refractive index of air based on laser synthetic wavelength interferometry |
| CN102223340A (en) * | 2011-06-20 | 2011-10-19 | 电子科技大学 | Terabit transmission rate coherent light orthogonal frequency division multiplexing (OFDM) system based on optical comb |
| CN102611504A (en) * | 2012-03-24 | 2012-07-25 | 云南大学 | Method for improving radio over fiber link performance |
| CN103560828A (en) * | 2013-11-08 | 2014-02-05 | 武汉邮电科学研究院 | Optical OFDM multichannel direct detection method and device of wavelength division multiplexing system |
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2015
- 2015-07-30 CN CN201510456963.7A patent/CN105049124B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102033053A (en) * | 2010-11-12 | 2011-04-27 | 浙江理工大学 | Method and device for measuring refractive index of air based on laser synthetic wavelength interferometry |
| CN102223340A (en) * | 2011-06-20 | 2011-10-19 | 电子科技大学 | Terabit transmission rate coherent light orthogonal frequency division multiplexing (OFDM) system based on optical comb |
| CN102611504A (en) * | 2012-03-24 | 2012-07-25 | 云南大学 | Method for improving radio over fiber link performance |
| CN103560828A (en) * | 2013-11-08 | 2014-02-05 | 武汉邮电科学研究院 | Optical OFDM multichannel direct detection method and device of wavelength division multiplexing system |
Non-Patent Citations (1)
| Title |
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| Transmission of 100-Gb/s DDO-OFDM/OQAM over 320-km SSMF with a single photodiode;Xuebing Zhang,Zhaohui Li,Chao Li,Ming Luo,Haibo Li,Cai Li,Qi Yan;《Optical Express》;20140513;第22卷(第10期);第5页及附图3 * |
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