CN117595934A - Employing pre-emphasis and HDB 3 Coded high-speed MIMO-WDM-FSO communication system and communication method - Google Patents

Employing pre-emphasis and HDB 3 Coded high-speed MIMO-WDM-FSO communication system and communication method Download PDF

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Publication number
CN117595934A
CN117595934A CN202311652147.4A CN202311652147A CN117595934A CN 117595934 A CN117595934 A CN 117595934A CN 202311652147 A CN202311652147 A CN 202311652147A CN 117595934 A CN117595934 A CN 117595934A
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signals
hdb
signal
optical
fso
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邵宇丰
袁杰
王安蓉
刘栓凡
左仁杰
李彦霖
李冲
陈鹏
柳海楠
杨林婕
胡文光
陈超
李文臣
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Chongqing Three Gorges University
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Chongqing Three Gorges University
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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
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • 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
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)

Abstract

The invention discloses a method for applying pre-emphasis and HDB 3 Coded high-speed MIMO-WDM-FSO communication system and communication method, transmitting end of the system adopts polarization multiplexing (PDM) technology to form MIMO working mode, and the system is combined with three-order high-density bipolar (HDB) 3 ) The code generators are combined to produce an HDB 3 Encoded polarization multiplexed non-return to zero (PDM-NRZ) signals. The eight-channel wavelength division multiplexed composite signal is transmitted in a 1km 2 x 2MIMO-FSO channel at a 1Tbit/s transmission rate. In order to improve the transmission quality and the receiving performance of the high-speed wireless optical signal, a carrier-suppressed double-sideband (CS-DSB) modulation mode and a pre-emphasis (PE) mode are also adopted to respectively modulate and pre-process the signal. The invention is suitable for transmission in severe weather environment with medium concentration fog. Under the weather attenuation of 40dB/km, the received optical signal of the CS-DSB modulated system has an optical signal to noise ratio of 42.17dB and a received optical power of 8.37dBm, and the system after pre-emphasis treatment has a received error rate of 10 ‑14 . At the limit of 3.8X10 of the error rate of forward error correction ‑3 The system can guarantee reliable transmission of 1.38km at the maximum under the limit of the system.

Description

Employing pre-emphasis and HDB 3 Coded high-speed MIMO-WDM-FSO communication system and communication method
Technical Field
The invention belongs to the field of optical access systems in optical communication networks, and particularly relates to a method for utilizing pre-emphasis and HDB 3 The coded high-speed MIMO-WDM-FSO communication system is used for improving the transmission capacity of the FSO system and improving the communication performance of the FSO system in a severe environment.
Background
With the increasing demand for large data network services, conventional optical fiber communications cannot meet all applications. In the era of globalization of digital economy, the full coverage of broadband access networks has been a trend. Free space optical communication (FSO) systems are an important component of broadband telecommunication networks to achieve full coverage, focusing on areas where optical fibers are not easily laid and mobile base stations cannot be installed. The FSO system can be perfectly complementary with the traditional communication system, and can often exert excellent advantages when being applied to severe environments such as complex terrains, remote mountain areas and the like. FSO has great development potential due to the characteristics of quick link deployment, no spectrum license, strong electromagnetic interference resistance, high bandwidth and the like. When the optical fiber link is damaged by natural disasters, the optical fiber link can be used for emergency communication to ensure smooth rescue. The method is also suitable for temporary communication in cities, and high-speed transmission of information is realized in areas where fiber channel cannot be laid. However, FSO is also obviously susceptible to severe weather and atmospheric turbulence, resulting in shorter transmission distances and is particularly unsuitable for high-speed signal transmission. The performance of the free space optical communication system is also urgently required to be enhanced to ensure the reliable transmission of high-speed signals, and a WDM technology for greatly improving the transmission capacity, a MIMO technology for improving the frequency spectrum utilization rate and a PDM technology suitable for stable signal transmission are generally combined with an FSO system so as to improve the communication performance of the high-speed signals in severe weather environments. CS-DSB techniques that are effective against atmospheric attenuation and pre-emphasis techniques that improve the quality of the received signal are used to further optimize the system performance.
Disclosure of Invention
The invention designs a method for adopting pre-emphasis and HDB to solve the problems that high-speed optical signals need to be transmitted and the performance of effectively receiving the optical signals is ensured because the optical fiber lines cannot be laid under partial special topography conditions of the high-speed signals 3 A coded high-speed MIMO-WDM-FSO communication system adapts wireless optical signals for reliable transmission in harsh environments.
The system scheme adopts PDM technology and CS-DSB modulation mode to generate 128Gbit/sHDB at transmitting end 3 After the coded PDM-NRZ signal passes through an eight-channel wavelength division multiplexer with a frequency interval of 100GHz, the synthesized signal is transmitted through a 1km 2X 2MIMO-FSO channel and a SISO-FSO channel at a rate of 1TGbit/s, and a receiver demodulates the signal in a direct detection mode. In addition, the performance of the system after pre-emphasis was studied when the frequency interval of the wavelength division multiplexing device was 200 GHz. The transmission and receiving performance of wireless optical signals in the system under different schemes are testedThe test results show that: the CS-DSB modulation HDB provided by the invention 3 The encoded PDM-NRZ signal has higher receiving quality after being transmitted in a 2X 2MIMO-WDM-FSO system, and the receiving performance of the system is further improved after the signal is pre-emphasized, so that the system is more suitable for being transmitted in severe weather environment with medium-concentration fog. Under the weather attenuation of 40dB/km, the received optical signal of the CS-DSB modulated system has an optical signal to noise ratio of 42.17dB and a received optical power of 8.37dBm, and the system after pre-emphasis treatment has a received error rate of 10 -14 . At the limit of 3.8X10 of the error rate of forward error correction -3 The system can guarantee reliable transmission of 1.38km at the maximum under the limit of the system. The scheme of the invention ensures the communication performance of the high-speed optical signal after being transmitted in severe weather environment, and provides a better alternative scheme, which is technically feasible.
The technical scheme adopted by the invention is as follows: employing pre-emphasis and HDB 3 The coded high-speed MIMO-WDM-FSO communication system comprises a wavelength division multiplexing transmitter, a transmission link and a wavelength division demultiplexing receiver which are connected in sequence;
the wavelength division multiplexing transmitter comprises a transmitter and a wavelength division multiplexer, wherein the wavelength division multiplexer synthesizes modulation signals of a plurality of transmitters into 1-path optical signals;
the transmitter comprises a continuous wave laser, a first polarization beam splitter, a polarization beam combiner and two HDBs 3 The continuous wave laser sends a continuous wave laser signal to be divided into two linearly polarized light beams C1 and C2 with orthogonal polarization property after passing through a polarization controller and a first polarization beam splitter, the two linearly polarized light beams C1 and C2 are respectively sent to one ends of the two double-arm Mach-Zehnder modulators, and data D1 is input into the HDB 3 The generator is further generated into HDB through a multi-system pulse generator 3 The encoded electrical signal is then pre-emphasized with a finite length unit impulse response filter, the pre-processed signal is sent to the other end of the dual arm Mach-Zehnder modulator and then modulated with the received linearly polarized light beam C1 to produce a signal with HDB 3 Electrically encoded optical NRZ signal, asThe other path of optical NRZ signal is generated by the physical data D2, and the two paths of optical NRZ signals are synthesized into one path of light beam with the property of orthogonal polarization state by the polarization beam combiner, namely the modulation signal of the transmitter, carrying the HDB 3 An encoded PDM-NRZ optical signal;
the transmission link comprises a splitter, an FSO channel and an adder, wherein the splitter sends optical signals output by the wavelength division multiplexer into different FSO channels, and the signals transmitted by the FSO channels are input into the wavelength division multiplexer after passing through the optical adder;
the wave-division multiplexing receiver comprises a wave-division multiplexer and a receiver, wherein the wave-division multiplexer demodulates the received signals and sends the demodulated signals to the receiver respectively;
the receiver comprises a second polarization beam splitter, two PIN photoelectric detectors, two electric amplifiers for amplifying, two low-pass filters and two 3R regenerators, wherein received signals are restored to electric signals by the PIN photoelectric detectors after the orthogonal polarization states of the received signals are relieved by the second polarization beam splitter, and the electric signals are sent to the 3R regenerators for restoring original signals after being amplified by the electric amplifiers and filtered by the low-pass filters after being demodulated.
Further, the continuous wave lasers form a continuous wave laser array to respectively emit 8 continuous wave laser signals with different wavelengths, and the continuous wave laser signals are processed by a transmitter and then respectively enter 8 wavelength division multiplexing channels of a wavelength division multiplexer.
Further, a negative electric gain and a zero bias voltage are applied to the double arm Mach-Zehnder modulator to enable the HDB to be realized 3 The encoded PDM-NRZ signal is transmitted in a carrier suppressed double sideband modulation.
Further, the transmission link includes a first erbium-doped fiber amplifier and a second erbium-doped fiber amplifier, which are respectively disposed before the splitter and after the optical adder, to compensate the optical signal, so as to form a 2×2MIMO-FSO channel with symmetrical amplification gain.
The invention also provides a method for using pre-emphasis and HDB 3 A method of coded high-speed MIMO-WDM-FSO communication comprising the steps of:
the continuous wave laser sends continuous wave laser signals to pass throughAfter the polarization controller and the first polarization beam splitter, the polarization controller and the first polarization beam splitter are divided into two linearly polarized light beams C1 and C2 with orthogonal polarization property, the linearly polarized light beams C1 and C2 are respectively sent into one ends of two double-arm Mach-Zehnder modulators, and data D1 is input into HDB 3 The generator is further generated into HDB through a multi-system pulse generator 3 The encoded electrical signal is then pre-emphasized with a finite length unit impulse response filter, the pre-processed signal is sent to the other end of the dual arm Mach-Zehnder modulator and then modulated with the received linearly polarized light beam C1 to produce a signal with HDB 3 The electrically encoded optical NRZ signal and the homonymous data D2 generate another optical NRZ signal, the polarization beam combiner synthesizes the two optical NRZ signals into one light beam with orthogonal polarization state property, and the light beam carries HDB 3 An encoded PDM-NRZ optical signal; the multiplexing PDM-NRZ optical signals are modulated by a wavelength division multiplexer to be synthesized into 1 path of optical signals;
then sending the optical signals into different FSO channels through a splitter, and inputting the signals after channel transmission into a wave-division multiplexer through an optical adder;
the wave-division multiplexing device demodulates the received signals and sends the signals to the second polarization beam splitter to remove the orthogonal polarization state, and then the signals are restored to electric signals by the PIN photoelectric detector, and the electric signals are amplified by the electric amplifier and filtered by the low-pass filter after demodulation and then sent to the 3R regenerator to restore the original signals.
Specifically, the continuous wave laser forms a continuous wave laser array to respectively emit 8 continuous wave laser signals with different wavelengths, and the continuous wave laser signals respectively enter 8 wavelength division multiplexing channels of the wavelength division multiplexer.
In the transmitter of the invention, HDB is realized by applying negative electric gain and zero bias voltage to the double-arm MZM 3 The encoded PDM-NRZ signal is transmitted in a carrier suppressed double sideband modulation without the need for additional opto-electronic devices.
The invention enables HDB 3 The coded electric signal is pre-emphasized by a first-order low-pass finite length unit impulse response filter, so that the quality of the received signal of the system is effectively improved.
The 2 x 2MIMO atmosphere channel and the SISO atmosphere channel adopt the same symmetrical compensation mode before optical signal transmission and before optical signal reception to carry out attenuation compensation on the signals, and the amplification gain of the 2 x 2MIMO channel is not increased additionally.
After the high-speed wireless optical signal is transmitted in a free space channel, the receiving performance of the high-speed wireless optical signal in a system is tested; compared with the transmission of high-speed optical signals in a single channel, the MIMO optical signal transmission method can receive wireless optical signals with lower signal-to-noise ratio (OSNR) of the received optical signals after the MIMO optical signal transmission method is applied under the condition of the same receiving error rate, and the optical signal strength after the signal transmission in the mode is higher than that of a signal (-2.92 dBm) in a single-input single-output (SISO) mode>-6.83 dBm). For HDB with and without CS-DSB modulation in MIMO-WDM-FSO system under 40dB/km of air attenuation (basically corresponding to medium foggy day environment) 3 The performance of the encoded PDM-NRZ signal after transmission was tested separately. The system OSNR and the received light power after the CS-DSB modulation signal is transmitted are 42.17dB and 8.37dBm, compared with the traditional signal which is not modulated by CS-DSB, the system OSNR and the received light power are respectively improved by 10dB and 11.3dB, and the receiving eye diagram generated by the modulation mode is clearer after the signal is transmitted. After pre-emphasis is adopted on the electric signal before modulation, the OSNR and the received light power of the system are respectively reduced by 1.18dB and 1.49dB, and the received error rate can reach 10 -14 And the error rate performance is improved. After the wireless optical signals are transmitted in the WDM-FSO system of the MIMO scheme, the CS-DSB MIMO scheme and the pre-emphasis CS-DSB MIMO scheme, the transmission distance limits of the communication quality can be respectively 1.12km, 1.37km and 1.38km, which are all higher than the transmission distance of the wireless optical signals of 1.1km of the SISO scheme. This also verifies that the communication system designed herein is suitable for efficient and reliable communication in medium-fog environments. Therefore, the system scheme has a certain potential value in the future high-speed wireless communication field.
Drawings
FIG. 1 is a block diagram of an FSO system according to the present invention;
FIG. 2 is a spectrum diagram of the MIMO scheme signals before and after transmission of the FSO channel in the present invention;
FIG. 3 is a graph showing the relationship between the signal-to-noise ratio and the bit error rate of the received optical signal in the MIMO scheme;
FIG. 4 is a graph showing the relationship between the received light power and the error rate of the MIMO scheme according to the present invention;
FIG. 5 is a graph showing the spectrum of CS-DSB MIMO scheme signals before and after transmission of FSO channels in the present invention;
FIG. 6 is a graph of OSNR versus bit error rate for the CS-DSB MIMO scheme of the present invention;
FIG. 7 is a graph showing the relation between the received light power and the error rate of the CS-DSB MIMO scheme in the present invention;
FIG. 8 shows the HDB of the present invention 3 Waveform comparison diagrams before and after pre-emphasis of the electric signals;
FIG. 9 is a graph of OSNR versus bit error rate for a pre-emphasis CS-DSB MIMO scheme in accordance with the present invention;
FIG. 10 is a graph of received optical power versus bit error rate for a pre-emphasis CS-DSB MIMO scheme according to the present invention;
FIG. 11 is a graph showing the relationship between transmission distance and bit error rate according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and specifically described below with reference to the accompanying drawings in the embodiments of the present invention. The described embodiments are only a few embodiments of the present invention.
FIG. 1 is a block diagram of an FSO system of the present invention. The invention comprises a Continuous Wave (CW) laser array, a wavelength division multiplexer, a first polarization beam splitter, a polarization beam combiner, and two HDBs 3 The device comprises a generator, two multi-system pulse generators, two finite length unit impulse response (FIR) filters, two double-arm Mach-Zehnder modulators (MZM), a free space optical communication device, a wave decomposition multiplexer, a second polarization beam splitter and two PIN photodetectors. A continuous wave laser array is adopted to send continuous wave laser signals to each wavelength division multiplexing channel, and one path of optical signals is divided into two linearly polarized light beams with orthogonal polarization property after passing through a polarization controller and a first polarization beam splitter. HDB (high density B) 3 The pseudo random sequence generator (PBRS) generates random binary sequence into 64Gbit/s HDB by the generator and the multi-system pulse generator (MPG) 3 An encoded electrical signal; and pre-emphasis the signal with a first order low pass FIR filter. Transmitting the preprocessed signals to the double armsOne end of the MZM is CS-DSB modulated with a linearly polarized optical signal from the other end to produce a signal having HDB 3 An electrically encoded optical NRZ signal. The polarization beam combiner combines the two modulated signals into one beam with orthogonal polarization state property to carry 128Gbit/s HDB 3 Encoded PDM-NRZ optical signal. After the optical signal is compensated by the erbium-doped fiber amplifier, the optical signal is sent to different FSO channels by using a splitter. After the signals transmitted in the MIMO-FSO channel pass through the optical adder, another erbium-doped fiber amplifier is used again for compensation to form a 2 x 2MIMO-FSO channel with symmetrical amplification gain. The 8-channel WDM device synthesizes the modulation signals of each transmitter into 1-channel 1TGbit/s optical signals, the signals after transmission are respectively sent into a receiver after passing through a wave-division multiplexer, the received optical signals are respectively restored into electric signals by a PIN photoelectric detector after the orthogonal polarization state of the received optical signals is released by a second polarization beam splitter, and the electric signals are respectively sent into a 3R regenerator to restore original signals after being demodulated, amplified by an electric amplifier and filtered by a low-pass filter. And then sent to a bit error rate analyzer for observation. The two paths of signals have extremely close independent receiving performance after demodulation processing.
The aperture values of the transceiver lenses in the laser transmitter and the receiver are 5cm and 20cm respectively, the beam divergence is 0.5mrad, and the space transmission distance is 1km. The gain of the erbium-doped fiber amplifier is 20dB, and 4dB noise is amplified. In practical transmission, the problem of increased alignment error of the receiving end of the system is caused by a multiple-input multiple-output mode, so that 5dB of extra attenuation loss is increased, and the extra attenuation in the transmission of a single FSO link is 1dB; an attenuation average of 40dB/km was used to equate to medium concentration fog weather conditions. Since the middle channel after WDM will be interfered by the adjacent channels and the reception performance will be slightly degraded, we choose the middle channel with the center frequency 193.1THz as the main test object. The increase in the frequency spacing of the wavelength division multiplexer reduces the OSNR, received optical power and bit error rate of the system, so that the overall value is reduced in the pre-emphasis scheme.
In fig. 2, the diagrams (a) and (b) are spectral diagrams before and after transmission of the optical signal after wavelength division multiplexing in the MIMO-FSO channel of 1km. The center frequency of each channel is not shifted, but the energy is reduced by the atmospheric attenuation.
FIG. 3 is HDB respectively 3 Graph of logarithmic bit error rate versus OSNR after optical signal transmission in SISO and 2 x 2MIMO links. The bit error rate of the WDM-FSO system as a whole decreases with increasing OSNR, the latter having a lower bit error rate at the same received optical signal-to-noise ratio compared to the SISO scheme and the MIMO scheme. And a 3bit period eye diagram after transmission in a medium dense fog environment is provided, and under the same attenuation, the eye diagram opening of the receiving eye diagram of the MIMO scheme is higher.
FIG. 4 is HDB respectively 3 The relation diagram of the error rate and the received optical power of the optical signals after being transmitted in the SISO and MIMO links is that the error rate is reduced along with the increase of the received optical power, and the MIMO scheme only needs lower received optical power under the condition of the same error rate. At an attenuation of 40dB/km, the SISO scheme receives optical power at-6.83 dBm, while the MIMO scheme receives optical power at-2.92 dBm.
In fig. 5, the graphs (a) and (b) are spectral diagrams before and after transmission of the CS-DSB optical signal after wavelength division multiplexing in a 2×2MIMO-FSO channel of 1km. Compared with a scheme without CS-DSB modulation, the method can clearly observe that the attenuation amplitude of the spectrum energy after transmission is obviously reduced, and the maximum optical power of the spectrum before transmission is also improved.
Fig. 6 is a graph of error rate versus OSNR after transmission of an optical signal in a MIMO link using CS-DSB modulation and when not in use. The MIMO scheme needs a lower OSNR to achieve the same BER, but this is due to the fact that when the double sideband spectrum carries information transmission, the OSNR of the FSO system is greatly improved. At medium dense fog with the same attenuation, the OSNR of the system can reach 42.17dB with CS-DSB modulation, whereas the OSNR without CS-DSB modulation is only 31.17dB.
Fig. 7 is a graph of bit error rate versus received optical power after transmission of an optical signal in a MIMO link using CS-DSB modulation and when not in use. Since the CS-DSB scheme increases the energy of the optical signal passing through the FSO link, the received optical power is increased by about 11.3dB, which indicates that a richer link margin can be obtained in the communication system. At an attenuation of 40dB/km, the CS-DSB MIMO scheme has a logarithmic bit error rate of-7.13, which is lower than-6.79 of the MIMO scheme.
FIG. 8 is HDB 3 Waveform comparison diagrams before and after signal pre-emphasis. The pre-processed signal waveform further improves the reception quality of the system.
Fig. 9 is a graph of OSNR versus bit error rate for a system before and after pre-emphasis. The OSNR of the system after pre-emphasis is 36.61dB, the OSNR when not in use is only 37.79dB, and the OSNR is reduced by 1.18dB.
Fig. 10 is a graph of received light power versus bit error rate for a system using pre-emphasis. The received optical power of the system after pre-emphasis was 2.92dBm, and the received optical power when not in use was 4.41dBm, which was reduced by 1.49dB. The pre-emphasis signal can make the error rate of the system reach 10 -14 About 3 orders of magnitude improvement, although the use of pre-emphasis may result in a slight drop in the OSNR and received optical power of the system.
Fig. 11 is a graph of the reception error rate versus transmission distance for different schemes. The use of HDB was tested separately without reaching the limit of the forward error correction bit error rate (logarithmic bit error rate is-2.42) 3 The transmission limits of the encoded PDM-NRZ signal in SISO scheme, MIMO scheme, CS-DSB MIMO scheme and pre-emphasis CS-DSB MIMO scheme are 1.1km, 1.12km, 1.37km and 1.38km, respectively. Therefore, on the premise of not greatly increasing the complexity and the power consumption of the system, the system scheme designed herein improves the conditions of serious attenuation, poor receiving performance, lower transmission distance and the like of a transmission signal of a high-speed FSO system in a severe environment.

Claims (6)

1. Employing pre-emphasis and HDB 3 A coded high-speed MIMO-WDM-FSO communication system characterized by: the device comprises a wavelength division multiplexing transmitter, a transmission link and a wavelength division multiplexing receiver which are connected in sequence;
the wavelength division multiplexing transmitter comprises a transmitter and a wavelength division multiplexer, wherein the wavelength division multiplexer synthesizes modulation signals of a plurality of transmitters into 1-path optical signals;
the transmitter comprises a continuous wave laser, a first polarization beam splitter, a polarization beam combiner and two HDBs 3 The continuous wave laser sends a continuous wave laser signal to be divided into two linearly polarized light beams C1 and C2 with orthogonal polarization property after passing through a polarization controller and a first polarization beam splitter, the two linearly polarized light beams C1 and C2 are respectively sent to one ends of the two double-arm Mach-Zehnder modulators, and data D1 is input into the HDB 3 The generator is further generated into HDB through a multi-system pulse generator 3 The encoded electrical signal is then pre-emphasized with a finite length unit impulse response filter, the pre-processed signal is sent to the other end of the dual arm Mach-Zehnder modulator and then modulated with the received linearly polarized light beam C1 to produce a signal with HDB 3 The electrically encoded optical NRZ signal and the homonymous data D2 generate another optical NRZ signal, the polarization beam combiner synthesizes the two optical NRZ signals into one light beam with orthogonal polarization state property, namely a modulation signal of a transmitter, and carries HDB 3 An encoded PDM-NRZ optical signal;
the transmission link comprises a splitter, an FSO channel and an adder, wherein the splitter sends optical signals output by the wavelength division multiplexer into different FSO channels, and the signals transmitted by the FSO channels are input into the wavelength division multiplexer after passing through the optical adder;
the wave-division multiplexing receiver comprises a wave-division multiplexer and a receiver, wherein the wave-division multiplexer demodulates the received signals and sends the demodulated signals to the receiver respectively;
the receiver comprises a second polarization beam splitter, two PIN photoelectric detectors, two electric amplifiers for amplifying, two low-pass filters and two 3R regenerators, wherein received signals are restored to electric signals by the PIN photoelectric detectors after the orthogonal polarization states of the received signals are relieved by the second polarization beam splitter, and the electric signals are sent to the 3R regenerators for restoring original signals after being amplified by the electric amplifiers and filtered by the low-pass filters after being demodulated.
2. The method of claim 1 employing pre-emphasis and HDB 3 A coded high-speed MIMO-WDM-FSO communication system characterized by: the continuous wave laser forms a continuous wave laserThe array transmits 8 continuous wave laser signals with different wavelengths respectively, and the continuous wave laser signals are processed by the transmitter and then enter 8 wavelength division multiplexing channels of the wavelength division multiplexer respectively.
3. The use of pre-emphasis and HDB according to claim 1 or 2 3 A coded high-speed MIMO-WDM-FSO communication system characterized by: applying negative electric gain and zero bias voltage to the double-arm Mach-Zehnder modulator to enable HDB 3 The encoded PDM-NRZ signal is transmitted in a carrier suppressed double sideband modulation.
4. The use of pre-emphasis and HDB according to claim 1 or 2 3 A coded high-speed MIMO-WDM-FSO communication system characterized by: the transmission link comprises a first erbium-doped fiber amplifier and a second erbium-doped fiber amplifier which are respectively arranged before the splitter and after the optical adder, and the optical signals are compensated to form a 2X 2MIMO-FSO channel with symmetrical amplification gain.
5. Employing pre-emphasis and HDB 3 A method of coded high-speed MIMO-WDM-FSO communication comprising the steps of:
after passing through a polarization controller and a first polarization beam splitter, a continuous wave laser signal sent by a continuous wave laser is divided into two linearly polarized light beams C1 and C2 with orthogonal polarization properties, the two linearly polarized light beams are respectively sent to one ends of two double-arm Mach-Zehnder modulators, and data D1 is input into an HDB 3 The generator is further generated into HDB through a multi-system pulse generator 3 The encoded electrical signal is then pre-emphasized with a finite length unit impulse response filter, the pre-processed signal is sent to the other end of the dual arm Mach-Zehnder modulator and then modulated with the received linearly polarized light beam C1 to produce a signal with HDB 3 The electrically encoded optical NRZ signal and the homonymous data D2 generate another optical NRZ signal, the polarization beam combiner synthesizes the two optical NRZ signals into one light beam with orthogonal polarization state property, and the light beam carries HDB 3 An encoded PDM-NRZ optical signal; the multipath PDM-NRZ optical signal is subjected to wavelength divisionThe multiplexer modulates and synthesizes the optical signals into 1 path of optical signals;
then sending the optical signals into different FSO channels through a splitter, and inputting the signals after channel transmission into a wave-division multiplexer through an optical adder;
the wave-division multiplexing device demodulates the received signals and sends the signals to the second polarization beam splitter to remove the orthogonal polarization state, and then the signals are restored to electric signals by the PIN photoelectric detector, and the electric signals are amplified by the electric amplifier and filtered by the low-pass filter after demodulation and then sent to the 3R regenerator to restore the original signals.
6. The method of claim 5 employing pre-emphasis and HDB 3 The encoded high-speed MIMO-WDM-FSO communication method is characterized in that: the continuous wave laser forms a continuous wave laser array which respectively transmits 8 continuous wave laser signals with different wavelengths and respectively enters 8 wavelength division multiplexing channels of the wavelength division multiplexer.
CN202311652147.4A 2023-12-04 2023-12-04 Employing pre-emphasis and HDB 3 Coded high-speed MIMO-WDM-FSO communication system and communication method Pending CN117595934A (en)

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