CN101719811A - System and method for optimizing property of radio over fiber down transmission link - Google Patents
System and method for optimizing property of radio over fiber down transmission link Download PDFInfo
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Abstract
The invention discloses a system for optimizing the property of a radio over fiber down transmission link, comprising a center station, a down fiber transmission link (3) and a base station, wherein the center station comprises a base band data signal (2) and a light carrying radio-frequency signal generation subsystem (1); the base station comprises a photoelectric detector (4) and an optical filter (5); and the center station carries out data transmission is conducted between the center station and the base station through the down fiber transmission link (3). The invention also discloses a method for optimizing the property of the radio over fiber down transmission link. The invention solves the problem of the property optimization of a system in a frequency modulate data modulating way under certain radio-frequency subcarrier frequency, reduces the power oscillation of the RoF (Radio Over Fiber) base station and the oscillation amplitude of the eye-opening penalty oscillation of a user receiving end, also prolongs the oscillation period and further improves the transmission property of the system and increases the capacity of the system.
Description
Technical field
(Radio-over-fiber, RoF) communication system technical field relate in particular to a kind of system and method for optimizing property of radio over fiber down transmission link to the present invention relates to optical fiber radio.
Background technology
The breakthrough of the development of high-speed high capacity optical fiber telecommunications system and all optical network key technology makes next generation mobile communication system develop into a kind of wire communication gradually and radio communication combines together, fixed communication and mobile communication are interconnected communication system.Optical fiber radio combines the mobile portability of low-loss, high bandwidth and the radio communication of optical fiber communication simultaneously as a kind of novel broadband access method, becomes one of key technology in the wide-band mobile communication system design of the 4th generation.
In the RoF system, central station (Central station, CS) light of Chan Shenging carries radiofrequency signal and is transmitted through the fiber to base station (Base station, BS), the base station is taken off radiofrequency signal and is sent to WLAN (wireless local area network) so that mobile phone users receives, thereby has realized utilizing light carrier to come the purpose of transmitting radio frequency signal.Because the generation of light-carried wireless signal, exchange and control all concentrate on central station, opto-electronic conversion is only realized in the base station, thereby cost and complex equipment has all been concentrated on central site, and a plurality of telepoint base stations can be shared these equipment, have reduced the power consumption and the cost of base station.
In addition, a plurality of antenna for base station are dispersed in the sub-district but not concentrate on the central authorities of sub-district, make base station transmitting power can be radiated each position, sub-district more equably, thereby the more efficiently base station power that utilized, and because portable terminal can reduce the required transmitting power of portable terminal greatly more near antenna for base station.
In sum, utilize optical fiber as the transmission link in the broadband access network, have low-loss, high bandwidth and prevent characteristics such as electromagnetic interference, the RoF technology has wide application prospect in fields such as following wireless broadband communication, satellite communication and intelligent transportation systems.
What carry on the light carrier in the RoF system is analogue microwave signal, compares with traditional digital fiber transmission link, and the RoF system has all proposed more harsh requirement to the performance of optical fiber link transmission characteristic and optical device.Along with data pass the increase of code check and the increase of radio frequency subcarrier frequency, optical fiber dispersion and nonlinear effect are more and more serious to the influence that light carries radio-frequency (RF) data signal.GVD (Group Velocity Dispersion) not only causes conventional double-side band (Double side band, DSB) periodic swinging of signal base station transmitting power (its power oscillation cycle and radio frequency subcarrier frequency square be inversely proportional to), and unite with nonlinear effect and to produce signal spectrum along the periodicity continuation of optical axis and the local video stretching at each radio frequency frequency multiplication place.Therefore, reasonably design the modulation system of RoF signal or carry out dispersion non-linearity effect compensating link, significant for the raising and the dilatation of RoF system transmissions performance.
There are some researches show monolateral band (Single side band, SSB) or light carrier suppress that (Opticalcarrier suppression, OCS) modulation system can be used to reduce above-mentioned power oscillation problem.Based on Fiber Bragg Grating FBG (Fiber Bragg grating, FBG) or the array fiber waveguide (Arraywaveguide, optical filter AWG) and both arms external modulator all can be used for producing SSB and OCS signal.Optical phase conjugation (Optical phase conjunction, thus OPC) can realize that the spectrum counter-rotating is used for fiber transmission link and carries out dispersion compensation.But above-mentioned solution be at amplitude modulation (Amplitude modulation, AM) signal proposes, the multipath fading in the RoF wireless transmission process will cause that the additional amplitude modulation of AM causes distorted signals.(Frequency modulation, FM) mode all is being better than AM aspect anti-multipath decline and the interference to frequency modulation, has been widely used in the system such as broadcasting.But the frequency modulation of optical frequencies is because higher frequency is difficult to realization, Recent study is found to go into the monocycle oscillation effect that semiconductor laser produces based on light beam, can produce from laser output radio frequency subcarrier frequency and inject the FM signal that light intensity changes with main laser, and can directly produce the RoF signal of SSB, need not the assistance of optical filter or modulator.
Further studies show that, when carrying out the digital signal transmission with this system, because RoF system user receiving terminal eye aperture cost is relevant with the radio frequency subcarrier frequency cycle of oscillation, 0,1 yard of FM signal has different radio frequency subcarriers and has different cycles of oscillation, cause the eye aperture cost vibration of FM signal user receiving terminal to worsen, thereby the design of the modulation format of system perfecting is the raising of RoF system transmissions performance and the subject matter that increase needed to be resolved hurrily of channel capacity.
Summary of the invention
(1) technical problem that will solve
The present invention is directed to above-mentioned situation, a kind of system and method for optimizing property of radio over fiber down transmission link is provided, adopt negative level precoding mode, solved under certain radio frequency subcarrier frequency, system function optimization problem when using the frequcny modulation data modulation system, reduced the amplitude of oscillation of the eye aperture cost vibration of RoF base station place's power oscillation and user's receiving terminal, prolonged above-mentioned cycle of oscillation simultaneously, further improved the system transmissions performance and increased power system capacity.
(2) technical scheme
In order to achieve the above object, the present invention adopts following technical scheme:
A kind of system that optimizes property of radio over fiber down transmission link, this system comprises: carry radiofrequency signal by base-band data signal 2 and light and produce central station, downlink optical fiber transmission link 3 that subsystem 1 constitutes and the base station that is made of photoelectric detector 4 and optical filter 5, central station carries out transfer of data by downlink optical fiber transmission link 3 and base station.
In the such scheme, in described central station, 2 pairs of light of base-band data signal carry radiofrequency signal generation subsystem 1 and carry out frequency modulation, utilize the monocycle vibration Nonlinear Dynamic performance of semiconductor laser, carry radiofrequency signal generation subsystem 1 by light and obtain frequency-modulation optical fiber radio downlink transmission signal, the descending transmission signal of this optical fiber radio transfers to the base station through described downlink optical fiber transmission link 3.
In the such scheme, in described base station, from the descending transmission signal of this optical fiber radio, take off radio frequency by photoelectric detector 4 and carry data-signal, and after optical filter 5 is removed sideband noise, be sent to wireless network.
In the such scheme, described light carries radiofrequency signal generation subsystem 1 and comprises main laser 7, plane mirror 8, external modulator 9, Faraday rotator and half-wave plate polarization state control device 11, polarizing beam splitter 10 and from laser 12, main laser 7 emitting lasers are after plane mirror 8 reflections, be modulated on the emergent light of main laser 7 by external modulator 9 by base-band data signal 2, through light modulated through polarizing beam splitter 10, incide behind Faraday rotator and the half-wave plate polarization state control device 11 from laser 12 to encourage from laser 12, after being energized from laser 12 shoot lasers, pass to the base station through downlink optical fiber transmission link 3.
In the such scheme, described main laser 7 and be distribution as unimodal formula feedback laser from laser 12.
In the such scheme, described central station adopts light to carry radiofrequency signal and produces subsystem 1, goes into by the outer light beam through the main laser of data-modulated, produces the monocycle vibration nonlinear state from laser, and produces monolateral subcarrier signal.
In the such scheme, photoelectric detector 4 is adopted in described base station, takes the radio frequency subcarrier, after connect an optical filter 5, the outer sideband noise of filtered signal through the differential delivery module of holding concurrently, can demodulate former data-signal again.
A kind of method of optimizing property of radio over fiber down transmission link, this method comprises:
In central station, 2 pairs of light of base-band data signal carry radiofrequency signal generation subsystem 1 and carry out frequency modulation, utilize the Nonlinear Dynamic performance of semiconductor laser, carry radiofrequency signal generation subsystem 1 by light and obtain frequency-modulation optical fiber radio downlink transmission signal, the descending transmission signal of this optical fiber radio transfers to the base station through described downlink optical fiber transmission link 3;
In the base station, from the descending transmission signal of this optical fiber radio, take off radio frequency by photoelectric detector 4 and carry data-signal, and after filter 5 is removed sideband noise, be sent to wireless network;
User terminal receives this radio frequency from wireless network and carries data-signal, adopts differential delivery circuit 6 to demodulate base-band data signal 2.
In the such scheme, 2 pairs of light of described base-band data signal carry radiofrequency signal and produce subsystem 1 and carry out frequency modulation and adopt double-side band DSB, monolateral band SSB and light carrier to suppress a kind of among the OCS.
In the such scheme, the flow process that described central station produces frequency-modulation optical fiber radio downlink transmission signal is: at first data to be sent are carried out the negative level precoding, load on the main laser through external modulator afterwards, this signal is gone into from laser by outer light beam, inspire monocycle oscillatory regime from laser, produce the frequency-modulation optical fiber radio downlink and send signal, this frequency-modulation optical fiber radio downlink sends signal and locates through Optical Fiber Transmission to base station, obtains data to be sent through photodetector and optical filter again.
(3) beneficial effect
1, utilizes the system and method for optimization property of radio over fiber down transmission link provided by the invention, adopt negative level precoding mode, solved under certain radio frequency subcarrier frequency, system function optimization problem when using the frequcny modulation data modulation system, reduced the amplitude of oscillation of the eye aperture cost vibration of RoF base station place's power oscillation and user's receiving terminal, prolonged above-mentioned cycle of oscillation simultaneously, further improved the system transmissions performance and increased power system capacity.
2, utilize the system and method for optimization property of radio over fiber down transmission link provided by the invention, can realize the complete optimal design of RoF system modulation signal guaranteeing further to optimize user's receiving terminal data performance under the situation that systematic function is improved.
Description of drawings
Fig. 1 is frequency modulation RoF transport stream signal journey figure of the present invention;
Fig. 2 is that frequency modulation RoF signal produces schematic diagram;
Fig. 3 is amplitude modulation and place, a FM signal base station Power penalty after the precoding of employing negative level;
Fig. 4 is amplitude modulation and a FM signal user receiving terminal eye aperture cost after the precoding of employing negative level.
Among the figure,
1 modulating light is carried radiofrequency signal and is produced subsystem
2 base-band data signals
3 downlink transmission optical fiber
4 photodetectors
5 optical filters
6 differential delivery circuit
7 main lasers
8 plane mirrors
9 external modulators
10 polarizing beam splitters
11 Faraday rotators and half-wave plate
12 from laser
Embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.
Go into the monocycle oscillation effect that semiconductor laser technology produces based on light beam, can produce light and carry the radio frequency subcarrier frequency with injecting the frequency modulation RoF signal that light intensity changes, light intensity is injected in suitable selection also will produce monolateral band SSB signal, compare with the amplitude modulation double-side-band DSB RoF signal that conventional method produces, the radio-frequency power vibration of place, the base station of SSB signal is less, thereby and FM signal have the ability of stronger anti-fiber nonlinear effect owing to have constant modulated wave envelope.But FM signal since 0,1 yard have different radio frequency subcarriers and make receiving terminal eye aperture cost vibration more frequent, for this reason, the present invention proposes a kind of negative level method for precoding, increased the cycle of oscillation of eye aperture cost, prolong the transmission range between base station and the central station, further improved the message capacity of RoF system.
A typical R oF system is made up of central station CS, fiber transmission link and base station BS.For simplifying the BS design, the data that CS will come from backbone transport networks directly change light into and carry radiofrequency signal, after fiber transmission link transmission to BS, BS carries radiofrequency signal to light to carry out opto-electronic conversion and obtains carrying loaded data on the radiofrequency signal at light, then these data is sent in the WLAN (wireless local area network) so that the user receives.The area coverage of each BS is by the decision of radiofrequency signal power, and the service area of CS is not only relevant with through-put power, also depends on the Optical Fiber Transmission distance.
The system of optimization property of radio over fiber down transmission link provided by the invention as shown in Figure 1, this system comprises: carry radiofrequency signal by base-band data signal 2 and light and produce central station, downlink optical fiber transmission link 3 that subsystem 1 constitutes and the base station that is made of photoelectric detector 4 and optical filter 5, central station carries out transfer of data by downlink optical fiber transmission link 3 and base station.In central station, 2 pairs of light of base-band data signal carry radiofrequency signal generation subsystem 1 and carry out frequency modulation, utilize the monocycle vibration Nonlinear Dynamic performance of semiconductor laser, carry radiofrequency signal generation subsystem 1 by light and obtain frequency-modulation optical fiber radio downlink transmission signal, the descending transmission signal of this optical fiber radio transfers to the base station through described downlink optical fiber transmission link 3.In the base station, from the descending transmission signal of this optical fiber radio, take off radio frequency by photoelectric detector 4 and carry data-signal, and after optical filter 5 is removed sideband noise, be sent to wireless network.User terminal receives this radio frequency from wireless network and carries data-signal, adopts differential delivery circuit 6 to demodulate base-band data signal 2.
As shown in Figure 2, described light carries radiofrequency signal generation subsystem 1 and comprises main laser 7, plane mirror 8, external modulator 9, Faraday rotator and half-wave plate polarization state control device 11, polarizing beam splitter 10 and from laser 12, main laser 7 emitting lasers are after plane mirror 8 reflections, be modulated on the emergent light of main laser 7 by external modulator 9 by base-band data signal 2, through light modulated through polarizing beam splitter 10, incide behind Faraday rotator and the half-wave plate polarization state control device 11 from laser 12 to encourage from laser 12, after being energized from laser 12 shoot lasers, pass to the base station through downlink optical fiber transmission link 3.Wherein, main laser 7 and be distribution as unimodal formula feedback laser from laser 12.Central station adopts light to carry radiofrequency signal and produces subsystem 1, goes into by the outer light beam through the main laser of data-modulated, produces the monocycle vibration nonlinear state from laser, and produces monolateral subcarrier signal.Photoelectric detector 4 is adopted in the base station, takes the radio frequency subcarrier, after connect an optical filter 5, the outer sideband noise of filtered signal through the differential delivery module of holding concurrently, can demodulate former data-signal again.
In the system that the present invention proposes, light carries radiofrequency signal generation subsystem 1 and has adopted light beam as shown in Figure 2 to go into semiconductor laser technology, main laser (Master Laser, ML) 7 and from laser (Slave Laser, SL) 12 be distribution as unimodal formula feedback (Distributed feedback, DFB) laser.The main laser emitting laser is after plane mirror 8 reflections, be modulated on the main laser emergent light by external modulator 9 by base-band data signal 2, this light modulated is through polarizing beam splitter (Polarizing beam splitter, PBS) 10, Faraday rotator (Faraday rotator, FR) and half-wave plate (Half-wave plate, HWP) incide from laser after the polarization state control system 11, being sent to the downlink optical fiber transmission link 3 from laser emitting light after being energized passes to the base station.
Adopt above-mentioned light beam to go into the semiconductor laser system at central station, by go into the monocycle vibration nonlinear state that can produce through the outer light beam of the main laser of data-modulated from laser, and in very large range show good frequency modulation characteristic, under the injection intensity and off-resonance frequency of suitable main laser, also will directly produce monolateral subcarrier signal.
The above-mentioned frequency modulation single sideband singal that is adopted, the advantage of the conventional amplitude modulation of comparing shows as:
1), the subcarrier single sideband modulated signal can effectively suppress place, base station transmitting power that optical fiber dispersion the causes oscillatory occurences with the Optical Fiber Transmission distance, reduces attenuating effect (fading effect);
2), as being widely used in FM signal in the wireless broadcast communication, have the characteristic of anti-multipath decline;
3) thereby, owing to have constant modulated wave envelope and have stronger anti-from fiber nonlinear effect abilities such as phase modulated;
4) even to conventional double-sideband signal, total transmitting power is located still less than amplitude-modulated signal in the FM signal base station.
Base station place adopts a photoelectric detector PD, takes the radio frequency subcarrier, after connect an optical filter, the outer sideband noise of filtered signal through the differential delivery module of holding concurrently, can demodulate former data-signal again.
The present invention has carried out the negative level precoding to described data-signal, and its reason is:
1) even also can to take place under the phase modulated effect with the radio frequency subcarrier frequency at optical fiber be the periodic spectral continuation in cycle to single sideband singal, produce the another one sideband at the another side of light carrier, promptly produce the class double-sideband signal;
2), in the RoF system, double-side band light carries radiofrequency signal because the existence of light carrier both sides high-frequency radio frequency subcarrier, the optical fiber GVD (Group Velocity Dispersion) produces identical frequency spectrum phase shift to these two symmetrical sidebands, after the opto-electronic conversion of base station, will obtain one with the signal power of Optical Fiber Transmission, square being inversely proportional to of this cycle of oscillation and optical fiber dispersion value and radio frequency carrier frequency apart from periodic swinging.Thereby 0,1 yard has different radio frequency subcarrier frequencies and has different cycles of oscillation under the FM signal, causes user's receiving terminal eye aperture cost to increase, and the eye closing time is elongated.
The present invention has carried out the negative level precoding to described data-signal, it is advantageous that:
1), negative level coding can reduce the radio frequency subcarrier frequency of 0 yard and 1 yard, thereby increase its base station place's power oscillation cycle;
2), the negative level size of 0 yard of suitable selection and 1 yard, can optimize the vibration of user's receiving terminal eye aperture cost, reduce its amplitude of oscillation, elongate its cycle of oscillation.
Below in conjunction with system performance verification and accompanying drawing, the present invention is specified.
The flow process that central station produces frequency-modulation optical fiber radio downlink transmission signal is: at first data to be sent are carried out the negative level precoding, load on the main laser ML through external modulator afterwards, this signal is gone into from laser SL by outer light beam, inspire the monocycle oscillatory regime of SL, produce frequency modulation RoF and send signal, obtain data to be sent through photodetector, optical filter and FM demodulator again through Optical Fiber Transmission to place, base station.
Radio frequency sub-carrier modulation mode can adopt double-side band DSB, monolateral band SSB and light carrier to suppress a kind of among the OCS respectively, in order to prove the system optimization performance of the relative amplitude-modulated signal of FM signal, be example with above-mentioned three kinds of sub-carrier modulation respectively, under amplitude modulation AM and modulating FM data-modulated mode, the transmission performance of each modulated wave in the RoF system compares, and comprises base station place's Power penalty and the analysis of user's receiving terminal eye aperture cost.It is that the Gaussian pulse of-1.2 units represents 1 that the negative level precoding process can adopt peak value, peak value represents 0 for the Gaussian pulse of-1.0 units, to length is that 27-1 pseudo-random data signal D (t) carries out precoding, then for each modulated subcarrier signal under the AM, it sends signal can represent that as the formula (1) the data-modulated degree of depth is m
D
And for each signal of FM, instantaneous angular frequency ω (t)=ω
RF[1+m
DD (t)], after the modulation of radio frequency subcarrier to light carrier, the signal expression that obtains each modulated wave is as follows again:
At this moment, the data-modulated degree of depth is:
In formula (1), (2), P
0For sending the total peak power of signal, m
RFBe the radio frequency subcarrier modulation depth, D (t) is a data-signal to be sent, ω
cAnd ω
RFBe respectively light carrier and radio-frequency carrier angular frequency.As getting that G.652 single mode standard fiber (Single mode fiber:SMF) 1.55um operation window is as light carrier, 30GHz is a radio-frequency carrier.Fig. 4 has provided under this coded system, m
D=1.0 amplitude modulation and m
fThe Power penalty of DSB, SSB and OCS is with the situation of change of Optical Fiber Transmission distance during=6.0 frequency modulation.As can be seen from this figure, in the Optical Fiber Transmission distance of 50km, place, the base station Power penalty of conventional amplitude modulation DSB signal has experienced 6 cycles of oscillation, the full swing amplitude reaches 25dB, and the cycle of oscillation of frequency modulation DSB signal is less than 3, the full swing amplitude only is 5dB, owing to have identical radio frequency subcarrier frequency, also reduce the cycle of oscillation of corresponding SSB and OCS under the mode of frequency regulation.
Fig. 5 (a) and (b) subgraph has provided respectively under the above-mentioned precoding mode, and 0,1 signal normalization mean amplitude of tide of amplitude modulation and FM signal and eye aperture cost are with the variation tendency of Optical Fiber Transmission distance.In like manner, 0,1 yard amplitude of amplitude-modulated signal is identical cycle of oscillation, and the FM signal difference is longer than 0 yard 1 yard cycle of oscillation, thereby the DSB eye aperture cost period of change of gained also reduces.The linear negative growth of the EOP of SSB in the amplitude-modulated signal 50km, mode of frequency regulation is periodic swinging down, the eye aperture cost of amplitude modulation and frequency modulation OCS is all smaller.
Above-described specific embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the above only is specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any modification of being made, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. system that optimizes property of radio over fiber down transmission link, it is characterized in that, this system comprises: carry central station, the downlink optical fiber transmission link (3) of radiofrequency signal generation subsystem (1) formation and the base station that is made of photoelectric detector (4) and optical filter (5) by base-band data signal (2) and light, central station carries out transfer of data by downlink optical fiber transmission link (3) and base station.
2. the system of optimization property of radio over fiber down transmission link according to claim 1, it is characterized in that, in described central station, base-band data signal (2) carries radiofrequency signal generation subsystem (1) to light and carries out frequency modulation, utilize the monocycle vibration Nonlinear Dynamic performance of semiconductor laser, carry radiofrequency signal generation subsystem (1) by light and obtain frequency-modulation optical fiber radio downlink transmission signal, the descending transmission signal of this optical fiber radio transfers to the base station through described downlink optical fiber transmission link (3).
3. the system of optimization property of radio over fiber down transmission link according to claim 2, it is characterized in that, in described base station, from the descending transmission signal of this optical fiber radio, take off radio frequency by photoelectric detector (4) and carry data-signal, and after optical filter (5) is removed sideband noise, be sent to wireless network.
4. the system of optimization property of radio over fiber down transmission link according to claim 1, it is characterized in that, described light carries radiofrequency signal generation subsystem (1) and comprises main laser (7), plane mirror (8), external modulator (9), Faraday rotator and half-wave plate polarization state control device (11), polarizing beam splitter (10) and from laser (12), main laser (7) emitting laser is after plane mirror (8) reflection, be modulated on the emergent light of main laser (7) by external modulator (9) by base-band data signal (2), through light modulated through polarizing beam splitter (10), incide behind Faraday rotator and the half-wave plate polarization state control device (11) from laser (12) to encourage from laser (12), after being energized from laser (12) shoot laser, pass to the base station through downlink optical fiber transmission link (3).
5. the system of optimization property of radio over fiber down transmission link according to claim 4 is characterized in that, described main laser (7) and be distribution as unimodal formula feedback laser from laser (12).
6. the system of optimization property of radio over fiber down transmission link according to claim 1, it is characterized in that, described central station adopts light to carry radiofrequency signal and produces subsystem (1), go into by outer light beam through the main laser of data-modulated, generation is from monocycle of laser vibration nonlinear state, and produces monolateral subcarrier signal.
7. the system of optimization property of radio over fiber down transmission link according to claim 1, it is characterized in that, photoelectric detector (4) is adopted in described base station, take the radio frequency subcarrier, after connect an optical filter (5), the outer sideband noise of filtered signal through the differential delivery module of holding concurrently, can demodulate former data-signal again.
8. a method of optimizing property of radio over fiber down transmission link is characterized in that, this method comprises:
In central station, base-band data signal carries radiofrequency signal generation subsystem to light and carries out frequency modulation, utilize the Nonlinear Dynamic performance of semiconductor laser, carry radiofrequency signal generation subsystem by light and obtain frequency-modulation optical fiber radio downlink transmission signal, the descending transmission signal of this optical fiber radio transfers to the base station through described downlink optical fiber transmission link;
In the base station, from the descending transmission signal of this optical fiber radio, take off radio frequency by photoelectric detector and carry data-signal, and after filter is removed sideband noise, be sent to wireless network;
User terminal receives this radio frequency from wireless network and carries data-signal, adopts differential delivery circuit to demodulate base-band data signal.
9. the method for optimization property of radio over fiber down transmission link according to claim 8, it is characterized in that described base-band data signal carries radiofrequency signal to light and produces subsystem and carry out frequency modulation and adopt double-side band DSB, monolateral band SSB and light carrier to suppress a kind of among the OCS.
10. the method for optimization property of radio over fiber down transmission link according to claim 8 is characterized in that, the flow process that described central station produces frequency-modulation optical fiber radio downlink transmission signal is:
At first data to be sent are carried out the negative level precoding, load on the main laser through external modulator afterwards, this signal is gone into from laser by outer light beam, inspire monocycle oscillatory regime from laser, produce the frequency-modulation optical fiber radio downlink and send signal, this frequency-modulation optical fiber radio downlink sends signal and locates through Optical Fiber Transmission to base station, obtains data to be sent through photodetector and optical filter again.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103018928A (en) * | 2012-12-27 | 2013-04-03 | 中国科学院半导体研究所 | Tunable microwave photonic filter based on photoinjection semiconductor laser system |
| TWI501570B (en) * | 2013-11-01 | 2015-09-21 | Univ Nat Cheng Kung | Optical Signal Conversion Device And Method Using Period-One Nonlinear Dynamics Of Semiconductor Lasers |
| CN111193542A (en) * | 2020-01-06 | 2020-05-22 | 浙江大学 | System and method for analyzing performance parameter values of radio frequency over optical carrier link |
-
2009
- 2009-12-02 CN CN200910241694A patent/CN101719811A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103018928A (en) * | 2012-12-27 | 2013-04-03 | 中国科学院半导体研究所 | Tunable microwave photonic filter based on photoinjection semiconductor laser system |
| CN103018928B (en) * | 2012-12-27 | 2014-12-03 | 中国科学院半导体研究所 | Tunable microwave photonic filter based on photoinjection semiconductor laser system |
| TWI501570B (en) * | 2013-11-01 | 2015-09-21 | Univ Nat Cheng Kung | Optical Signal Conversion Device And Method Using Period-One Nonlinear Dynamics Of Semiconductor Lasers |
| CN111193542A (en) * | 2020-01-06 | 2020-05-22 | 浙江大学 | System and method for analyzing performance parameter values of radio frequency over optical carrier link |
| CN111193542B (en) * | 2020-01-06 | 2021-03-19 | 浙江大学 | System and method for analyzing performance parameter values of radio frequency over optical carrier link |
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Application publication date: 20100602 |