A signal processing method, a transmitting end, a receiving end and a storage medium

Abstract

The application provides a signal processing method, a transmitting end, a receiving end and a storage medium. The method comprises the following steps: obtaining a first digital signal of the transmitting end and a second digital signal of the transmitting end; performing transmitting end digital signal processing on the first digital signal and the second digital signal respectively, and correspondingly obtaining a first electrical signal of the transmitting end and a second electrical signal of the transmitting end, wherein the first electrical signal of the transmitting end and the second electrical signal of the transmitting end are asymmetric twin single sideband electrical signals with auxiliary carriers; performing electro-optical modulation based on the first electrical signal of the transmitting end and the second electrical signal of the transmitting end to obtain a transmission optical signal; and transmitting the transmission optical signal to the receiving end. The application can improve the usage rate of the spectrum and reduce the influence of dispersion and symbol time shift effects.

Description

Technical Field

[0001] This invention relates to optical communication transmission technology, and more particularly to a signal processing method, a transmitter, a receiver, and a storage medium. Background Technology

[0002] With the development of communication technology, optical communication transmission technology is being used in more and more scenarios. In application scenarios such as short-to-medium distance optical access networks and metropolitan area networks, optical communication transmission technology has important research significance and economic value due to its low cost and high speed.

[0003] In optical communication transmission technology, optical double-sideband signals are commonly used. An optical double-sideband signal consists of a central optical carrier and two symmetrical first-order sidebands. Since the two symmetrical sideband signals carry the same signal, the spectrum utilization is low, and it is affected by dispersion and symbol time shift effects during transmission. Summary of the Invention

[0004] The present invention aims to provide a signal processing method, a transmitter, a receiver, and a storage medium that can add auxiliary carriers to both sides of an asymmetric twin single-sideband signal for transmission, thereby improving the utilization of the spectrum and reducing the effects of dispersion and symbol time shift.

[0005] The technical solution of this invention is implemented as follows: This invention provides a signal processing method, the method comprising: Acquire a first digital signal and a second digital signal from the transmitting end; the first digital signal and the second digital signal from the transmitting end contain information to be transmitted; The first digital signal and the second digital signal are respectively processed by the transmitting end digital signal processing to obtain the transmitting end first electrical signal and the transmitting end second electrical signal; the transmitting end first electrical signal and the transmitting end second electrical signal are asymmetric twin single-sideband electrical signals with auxiliary carriers; Electro-optic modulation is performed based on the first electrical signal and the second electrical signal of the transmitting end to obtain the transmitted optical signal; The transmitted optical signal is transmitted to the receiving end.

[0006] In the above scheme, after performing transmittance digital signal processing on the first digital signal and the second digital signal respectively to obtain the transmittance first electrical signal and the transmittance second electrical signal, and before performing electro-optic modulation based on the transmittance first electrical signal and the transmittance second electrical signal to obtain the transmitted optical signal, the method further includes: The first electrical signal and the second electrical signal from the transmitting end are amplified respectively to increase their power.

[0007] In the above scheme, the step of performing electro-optic modulation based on the first electrical signal and the second electrical signal of the transmitting end to obtain the transmitted optical signal includes: Obtain the center optical carrier; The transmitted optical signal is obtained by electro-optic modulation based on the central optical carrier, the first electrical signal of the transmitting end, and the second electrical signal of the transmitting end.

[0008] In the above scheme, after performing electro-optic modulation based on the first electrical signal and the second electrical signal of the transmitting end to obtain the transmitted optical signal, and before transmitting the transmitted optical signal to the receiving end, the method further includes: The transmitted optical signal is amplified to increase its power.

[0009] In the above scheme, the first digital signal and the second digital signal of the transmitting end are respectively processed by the transmitting end digital signal processing to obtain the first electrical signal and the second electrical signal of the transmitting end, including: Based on the first digital signal and the second digital signal of the transmitting end, the left-side band signal and the right-side band signal of the transmitting end are obtained respectively. Auxiliary carriers are added to the left-side band signal and the right-side band signal of the transmitting end respectively to obtain the first electrical signal and the second electrical signal of the transmitting end.

[0010] In the above scheme, obtaining the left-side band signal and the right-side band signal of the transmitter based on the first digital signal and the second digital signal of the transmitter respectively includes: The first digital signal and the second digital signal of the transmitting end are respectively subjected to QAM (Quadrature Amplitude Modulation) mapping to obtain the first mapped signal and the second mapped signal of the transmitting end. The first mapped signal and the second mapped signal of the transmitting end are upsampled respectively to obtain the first sampled signal and the second sampled signal of the transmitting end. The first sampled signal and the second sampled signal of the transmitting end are respectively subjected to root raised cosine low-pass filtering to obtain the first baseband signal and the second baseband signal of the transmitting end. The first baseband signal and the second baseband signal of the transmitting end are converted to the upper left and the upper right respectively to obtain the upper left frequency-converted baseband signal and the upper right frequency-converted baseband signal. The upper left and upper right frequency-converted baseband signals are subjected to Hilbert transforms respectively to obtain the left-side band signal and the right-side band signal of the transmitting end.

[0011] In the above scheme, before performing left-upward and right-upward frequency conversion on the first baseband signal and the second baseband signal of the transmitting end, respectively, to obtain the left-upward frequency-converted baseband signal and the right-upward frequency-converted baseband signal, the method further includes: Based on the bandwidth of the transmitting device, the upper left and upper right conversion frequencies are determined.

[0012] In the above scheme, the step of converting the first baseband signal and the second baseband signal of the transmitting end to the upper left and the upper right respectively, to obtain the upper left-converted baseband signal and the upper right-converted baseband signal, includes: The upper-left-converted complex sine wave signal is mixed with the first baseband signal of the transmitting end to obtain the upper-left-converted baseband signal; wherein, the upper-left-converted complex sine wave signal is the complex sine wave signal corresponding to the upper-left-converted frequency; and... The upper right-converted complex sine wave signal is mixed with the second baseband signal of the transmitting end to obtain the upper right-converted baseband signal; wherein, the upper right-converted complex sine wave signal is the complex sine wave signal corresponding to the upper right-converted frequency.

[0013] In the above scheme, before adding auxiliary carriers to the left-side band signal and the right-side band signal of the transmitting end respectively to obtain the first electrical signal and the second electrical signal of the transmitting end, the method further includes: Based on the power of the signal on the left side of the transmitter and the power of the signal on the right side of the transmitter, the auxiliary carrier power of the left side and the auxiliary carrier power of the right side are determined respectively. Based on the bandwidth of the photodetector at the receiving end and the edge slope of the optical filter at the receiving end, the auxiliary carrier frequencies of the left band and the right band are determined respectively. The left-side auxiliary carrier is determined based on the left-side auxiliary carrier power and the left-side auxiliary carrier frequency; and the right-side auxiliary carrier is determined based on the right-side auxiliary carrier power and the right-side auxiliary carrier frequency.

[0014] In the above scheme, adding auxiliary carriers to the left-side band signal and the right-side band signal of the transmitting end respectively to obtain the first electrical signal and the second electrical signal of the transmitting end includes: The left-side auxiliary carrier and the right-side auxiliary carrier are respectively added to the left-side signal and the right-side signal of the transmitting end, thereby obtaining the first electrical signal and the second electrical signal of the transmitting end.

[0015] In the above scheme, the step of adding the left-side auxiliary carrier and the right-side auxiliary carrier to the left-side signal and the right-side signal of the transmitting end, respectively, to obtain the first electrical signal and the second electrical signal of the transmitting end, includes: Adding the complex signal expression corresponding to the left-side band signal of the transmitting end to the complex signal expression corresponding to the left-side band auxiliary carrier yields the complex signal expression corresponding to the first electrical signal of the transmitting end, thereby obtaining the first electrical signal of the transmitting end; and The complex signal expression corresponding to the right-side carrier signal of the transmitting end is added to the complex signal expression corresponding to the right-side auxiliary carrier to obtain the complex signal expression corresponding to the second electrical signal of the transmitting end, thereby obtaining the second electrical signal of the transmitting end.

[0016] In the above scheme, the step of performing electro-optic modulation based on the central optical carrier, the first electrical signal from the transmitting end, and the second electrical signal from the transmitting end to obtain the transmitted optical signal includes: The first electrical signal and the second electrical signal from the transmitting end are summed to obtain the superimposed electrical signal to be modulated. The real and imaginary components of the superimposed electrical signal to be modulated are obtained and used as the I-path driving signal and the Q-path driving signal, respectively; the I-path driving signal and the Q-path driving signal are orthogonal to each other; Under carrier suppression modulation, the transmitted optical signal is obtained by electro-optic modulation based on the center optical carrier, the I-path driving signal, and the Q-path driving signal.

[0017] This invention also provides a signal processing method, comprising: Receive and transmit optical signals; The transmitted optical signal is divided into a first optical signal at the receiving end and a second optical signal at the receiving end; the first optical signal at the receiving end and the second optical signal at the receiving end contain the same content as the transmitted optical signal; The first optical signal and the second optical signal at the receiving end are respectively subjected to left-side band signal filtering and right-side band signal filtering to obtain the right-side band optical signal and the left-side band optical signal at the receiving end; the right-side band optical signal at the receiving end includes a right-side band auxiliary carrier, and the left-side band optical signal at the receiving end includes a left-side band auxiliary carrier. The light signal on the left side of the receiver and the light signal on the right side of the receiver are converted into photoelectric signals respectively to obtain the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver. The charged signal on the left side of the receiving end and the charged signal on the right side of the receiving end are processed by receiving end digital signal processing to obtain the first digital signal and the second digital signal of the receiving end; the first digital signal and the second digital signal of the receiving end contain the information to be transmitted.

[0018] In the above scheme, after performing photoelectric conversion on the light-bearing signal on the left side of the receiver and the light-bearing signal on the right side of the receiver to obtain the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver, and before performing digital signal processing on the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver to obtain the first digital signal and the second digital signal of the receiver, the method further includes: The charged signals on the left and right sides of the receiving end are amplified respectively, thereby increasing the power of the charged signals on the left and right sides of the receiving end.

[0019] In the above scheme, the step of performing receiving-end digital signal processing on the charged signal on the left side of the receiving end and the charged signal on the right side of the receiving end respectively to obtain the receiving end first digital signal and the receiving end second digital signal includes: The charged signal on the left side of the receiver and the charged signal on the right side of the receiver are resampled respectively to obtain the first sampled signal and the second sampled signal of the receiver. The first sampled signal and the second sampled signal at the receiving end are respectively down-converted to the left and down-converted to the right to obtain the down-converted baseband signal and the down-converted baseband signal respectively. The lower left and lower right frequency conversion baseband signals are respectively subjected to root raised cosine low-pass filtering at the receiving end to obtain the first baseband signal and the second baseband signal at the receiving end. Channel equalization is performed on the first baseband signal and the second baseband signal of the receiving end respectively to obtain the first channel equalization signal and the second channel equalization signal. QAM demapping is performed on the first channel equalization signal and the second channel equalization signal respectively to obtain the first digital signal and the second digital signal of the receiving end.

[0020] In the above scheme, the step of performing channel equalization on the first baseband signal and the second baseband signal at the receiving end to obtain a first channel equalization signal and a second channel equalization signal respectively includes: The first baseband signal and the second baseband signal at the receiving end are respectively subjected to cascaded multimode algorithm equalization to obtain the first channel equalization signal and the second channel equalization signal.

[0021] In the above scheme, before receiving the transmitted optical signal, the method further includes: Obtain the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal.

[0022] In the above scheme, before performing left-side band signal filtering and right-side band signal filtering on the first optical signal and the second optical signal at the receiving end, respectively, to obtain the right-side band optical signal and the left-side band optical signal at the receiving end, the method further includes: Based on the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal, the passband bandwidth and passband center frequency are set.

[0023] In the above scheme, the step of filtering out the left-side band signal and the right-side band signal of the first optical signal and the second optical signal of the receiving end respectively, to obtain the right-side band optical signal and the left-side band optical signal of the receiving end, includes: Based on the passband bandwidth and the passband center frequency, the first optical signal and the second optical signal at the receiving end are respectively subjected to left-side band signal filtering and right-side band signal filtering to obtain the right-side band optical signal and the left-side band optical signal at the receiving end.

[0024] In the above scheme, the sideband signal frequency includes: the left sideband signal frequency and the right sideband signal frequency; the auxiliary carrier frequency includes: the left sideband auxiliary carrier frequency and the right sideband auxiliary carrier frequency; Before performing left-downconversion and right-downconversion on the first sampled signal and the second sampled signal at the receiving end, respectively, to obtain the left-downconverted baseband signal and the right-downconverted baseband signal, the method further includes: Subtracting the left-side band signal frequency from the left-side band auxiliary carrier frequency yields the lower-left conversion frequency; and, Subtracting the right-side band signal frequency from the right-side band auxiliary carrier frequency yields the right-side lower-conversion frequency.

[0025] In the above scheme, the step of performing left-downward and right-downward frequency conversion on the first sampling signal and the second sampling signal of the receiving end, respectively, to obtain the left-downward frequency-converted baseband signal and the right-downward frequency-converted baseband signal, includes: The left-lower frequency-converted complex sine wave signal is mixed with the first sampled signal at the receiving end to obtain the left-lower frequency-converted baseband signal; wherein, the left-lower frequency-converted complex sine wave signal is the complex sine wave signal corresponding to the left-lower frequency conversion frequency; and... The right-lower frequency conversion complex sine wave signal is mixed with the second sampling signal of the receiving end to obtain the right-lower frequency conversion baseband signal; wherein, the right-lower frequency conversion complex sine wave signal is the complex sine wave signal corresponding to the right-lower frequency conversion frequency.

[0026] In the above scheme, the step of performing root-raised cosine low-pass filtering on the lower left and lower right frequency-converted baseband signals respectively to obtain the first baseband signal and the second baseband signal at the receiving end includes: Based on the roll-off factor, the lower left and lower right frequency conversion baseband signals are respectively subjected to root-raised cosine low-pass filtering at the receiving end to obtain the first baseband signal and the second baseband signal at the receiving end.

[0027] In the above scheme, before receiving the transmitted optical signal, the method further includes: Obtain the QAM mapping modulation format corresponding to the transmitted optical signal; The step of performing QAM demapping on the first channel equalization signal and the second channel equalization signal respectively to obtain the first digital signal and the second digital signal at the receiving end includes: Based on the QAM mapping modulation format, QAM demapping is performed on the first channel equalization signal and the second channel equalization signal respectively to obtain the first digital signal and the second digital signal of the receiving end.

[0028] This invention also provides a transmitter, comprising: Transmitter memory and transmitter processor; The transmitter memory is used to store executable instructions; The transmitter processor is configured to execute executable instructions stored in the transmitter memory to acquire a first digital signal and a second digital signal from the transmitter; the first digital signal and the second digital signal from the transmitter contain information to be transmitted; the first digital signal and the second digital signal are respectively processed by the transmitter to obtain a first electrical signal and a second electrical signal from the transmitter; the first electrical signal and the second electrical signal from the transmitter are asymmetric twin single-sideband electrical signals with an auxiliary carrier. An electro-optic modulator is used to perform electro-optic modulation based on the first electrical signal and the second electrical signal of the transmitting end to obtain a transmitted optical signal; An optical signal transmitter is used to transmit the transmitted optical signal to the receiving end.

[0029] In the above scheme, the transmitting end further includes: A transmitting-end electrical signal amplifier is used to amplify the transmitting-end first electrical signal and the transmitting-end second electrical signal respectively, thereby amplifying the power of the transmitting-end first electrical signal and the transmitting-end second electrical signal.

[0030] In the above scheme, the electro-optic modulator is also used to acquire the center optical carrier; and to perform electro-optic modulation based on the center optical carrier, the first electrical signal of the transmitting end and the second electrical signal of the transmitting end to obtain the transmitted optical signal.

[0031] In the above scheme, the transmitting end further includes: The transmitting optical signal amplifier is used to amplify the transmitted optical signal and increase its power.

[0032] This invention also provides a receiving end, comprising: An optical signal receiver is used to receive transmitted optical signals. An optical coupler is used to split the transmitted optical signal into a first optical signal at the receiving end and a second optical signal at the receiving end; the first optical signal at the receiving end and the second optical signal at the receiving end contain the same content as the transmitted optical signal; An optical bandpass filter is used to filter out the left band signal and the right band signal respectively from the first optical signal and the second optical signal at the receiving end, thereby obtaining a right band optical signal and a left band optical signal at the receiving end; the right band optical signal at the receiving end includes a right band auxiliary carrier, and the left band optical signal at the receiving end includes a left band auxiliary carrier. A photodetector is used to perform photoelectric conversion on the light signal on the left side of the receiver and the light signal on the right side of the receiver, respectively, to obtain the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver. Receiver memory and receiver processor; The receiver memory is used to store executable instructions; The receiving end processor is used to execute executable instructions stored in the receiving end memory, and to perform receiving end digital signal processing on the receiving end left-side charged signal and the receiving end right-side charged signal respectively, to obtain the receiving end first digital signal and the receiving end second digital signal; the receiving end first digital signal and the receiving end second digital signal contain information to be transmitted.

[0033] In the above scheme, the receiving end further includes: The receiving end electrical signal amplifier is used to amplify the electrical signal on the left side of the receiving end and the electrical signal on the right side of the receiving end, respectively, and amplify the power of the electrical signal on the left side of the receiving end and the electrical signal on the right side of the receiving end.

[0034] This invention also provides a storage medium storing executable instructions for implementing the signal processing method described above when executed by a transmitter processor or a receiver processor.

[0035] Therefore, the embodiments of the present invention provide a signal processing method, a transmitter, a receiver, and a storage medium. After acquiring a first digital signal and a second digital signal from the transmitter, the method performs transmitter digital signal processing on the first and second digital signals respectively to obtain a first electrical signal and a second electrical signal from the transmitter. The first and second electrical signals are asymmetric twin single-sideband electrical signals with auxiliary carriers. Then, electro-optic modulation is performed based on the first and second electrical signals to obtain a transmission optical signal. This transmission optical signal is an asymmetric twin single-sideband optical signal with an auxiliary carrier and a suppressed center optical carrier. Finally, the transmission optical signal is transmitted to the receiver. By adding auxiliary carriers to both sides of the asymmetric twin single-sideband signal before transmission, the spectrum utilization is improved, and the effects of dispersion and symbol time shift are reduced. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a system architecture for a signal processing method provided in an embodiment of the present invention; Figure 2 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 1 ; Figure 3 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 2 ; Figure 4 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 3 ; Figure 5 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 4 ; Figure 6 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 5 ; Figure 7 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 6 ; Figure 8 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 7 ; Figure 9 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 8 ; Figure 10 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 9 ; Figure 11 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 10 ; Figure 12 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 10 one; Figure 13 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 10 two; Figure 14 A flowchart of a signal processing method provided in an embodiment of the present invention. Figure 10 three; Figure 15 A schematic diagram of a transmitter structure provided in an embodiment of the present invention; Figure 16 This is a schematic diagram of a receiving end provided in an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The described embodiments should not be regarded as limitations on the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0039] If similar descriptions such as "first / second" appear in the invention document, the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of the invention described herein can be implemented in an order other than that illustrated or described herein.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the invention.

[0041] In optical communication transmission technology, if double-sideband modulation is used, the radio frequency power will periodically attenuate and the symbol time shift effect will be severe due to fiber dispersion during transmission. The symbol time shift effect caused by dispersion means that the baseband signals modulated onto the optical carrier and its sidebands at the same time will arrive at the receiver at different times due to fiber dispersion, thus losing synchronization. This will cause the demodulated symbols at the receiver to become narrower or even disappear, which will seriously degrade the performance of the entire optical communication system when the transmission fiber distance is long.

[0042] Single-sideband (SSB) modulation can effectively reduce the power attenuation and symbol time shift effects caused by dispersion, while also improving spectrum utilization. However, SSB modulation only occupies one side of the transmitter's bandwidth. To fully utilize the transmitter's bandwidth, another independent SSB signal can be modulated on the other side of the transmitter's sideband to form an asymmetric, independent twin SSB signal for optical transmission.

[0043] In related technologies, asymmetric twin single-sideband systems mainly employ the setting of guard intervals to eliminate crosstalk between the two sidebands, for example: In related scheme 1, an independent asymmetric twin sideband signal is formed at the transmitting end using a coupler; however, the method for generating the asymmetric twin single sideband signal is relatively complex and costly, and at the same time, it places high demands on the performance of the photodetector at the receiving end.

[0044] In related scheme 2, three external cavity lasers and two sets of I / Q modulators are used at the transmitting end; it also has the problems of complex system structure and algorithm, high cost, and high requirements for the performance of photodetector at the receiving end.

[0045] Figure 1 This is a schematic diagram of an optional architecture of the signal processing method provided in an embodiment of the present invention, such as... Figure 1 As shown, the transmitter 01 includes: a transmitter DSP (Digital Signal Processing) device 011, a transmitter EA (Electric Amplifier) ​​012, an External Cavity Laser (ECL) 013, an I / Q Modulator 014, and an Erbium Doped Fiber Amplifier (EDFA) 015. Wherein: The transmitter DSP device 011 performs transmitter digital signal processing via offline software, converting the acquired first and second digital signals into a transmitter first electrical signal and a transmitter second electrical signal. These transmitter first and second electrical signals are asymmetric twin single-sideband electrical signals with an auxiliary carrier. The transmitter DSP device 011 can perform steps such as QAM mapping, upsampling, root-raised cosine low-pass filtering, upconversion, Hilbert transform, and adding an auxiliary carrier.

[0046] The first and second electrical signals from the transmitting end are amplified by the transmitting end amplifier 012 and then used as the I-path and Q-path drive RF signal inputs of the I / Q modulator 014. The I / Q modulator 014 is set to its minimum bias voltage and operates in carrier-suppressed modulation mode. Simultaneously, the external cavity laser 013 provides a stable laser source for the I / Q modulator 014 as the center optical carrier. The I / Q modulator 014 performs electro-optic modulation in carrier-suppressed modulation mode and outputs a transmission optical signal, which is an asymmetric twin single-sideband optical signal with an auxiliary carrier whose center optical carrier is suppressed. After being amplified by the erbium-doped fiber amplifier 015, the transmission optical signal enters the standard single-mode fiber (SSMF) 03 for transmission.

[0047] Receiver 02 includes: an optical coupler (OC) 021, an optical band-pass filter (OBPF) 022, a photoelectric detector (PD) 023, a receiver amplifier 024, and a receiver DSP device 025. Wherein: After receiving the transmitted optical signal through the standard single-mode fiber 03, the optical coupler 021 splits the transmitted optical signal into two identical optical signals, namely the first optical signal of the receiver and the second optical signal of the receiver, and passes them into the optical bandpass filter 022.

[0048] The optical bandpass filter 022 performs left-sideband signal filtering and right-sideband signal filtering on the first and second optical signals received from the receiving end, respectively, to remove redundant center carrier and sideband signals, obtaining single-sideband optical signals for the left and right sidebands. These single-sideband optical signals are then converted into electrical signals by the photodetector 023, resulting in the corresponding single-sideband electrical signals for the left and right sidebands.

[0049] The single-sideband electrical signals of the left and right sidebands are amplified by the receiver amplifier 024 and then fed into the receiver DSP device 025 for offline digital signal processing. The single-sideband electrical signals of the left and right sidebands are then demodulated after algorithmic compensation. The receiver DSP device 025 can perform steps such as resampling, down-conversion, root-raised cosine low-pass filtering, channel equalization, and QAM demapping.

[0050] Understandably, both transmitter 01 and receiver 02 can perform their respective digital signal processing procedures through offline software. This reduces the system's structural complexity and achieves functional integration. Furthermore, transmitter 01 can utilize only one I / Q modulator and one external cavity laser, effectively reducing costs.

[0051] Figure 2 This is an optional flowchart illustrating a signal processing method provided in an embodiment of the present invention, which will be combined with... Figure 2 The steps shown are explained.

[0052] S101. Obtain the first digital signal and the second digital signal from the transmitting end; the first digital signal and the second digital signal from the transmitting end contain the information to be transmitted.

[0053] In this embodiment of the invention, the transmitting end can acquire a first digital signal and a second digital signal from the transmitting end. The first digital signal and the second digital signal from the transmitting end contain the information to be transmitted.

[0054] In this embodiment of the invention, the first digital signal and the second digital signal from the transmitting end can be two binary data streams, and the information to be transmitted is the content represented by these two binary data streams. For example, when the first digital signal and the second digital signal from the transmitting end are binary data streams of multiple emails, the information to be transmitted is the content of these emails.

[0055] S102. Perform transmitting-end digital signal processing on the first digital signal and the second digital signal respectively to obtain the transmitting-end first electrical signal and the transmitting-end second electrical signal; the transmitting-end first electrical signal and the transmitting-end second electrical signal are asymmetric twin single-sideband electrical signals with auxiliary carriers.

[0056] In this embodiment of the invention, the transmitting end can perform transmitting end digital signal processing on the acquired first digital signal and second digital signal respectively to obtain a transmitting end first electrical signal and a transmitting end second electrical signal. The transmitting end first electrical signal and the transmitting end second electrical signal are asymmetric twin single-sideband electrical signals with an auxiliary carrier.

[0057] In this embodiment of the invention, digital signal processing at the transmitting end may include the following steps: Step 1: QAM Mapping. The transmitter can perform QAM mapping on the first and second digital signals, respectively, to obtain the first and second mapped signals. QAM mapping is a type of vector modulation, and its use improves spectral efficiency.

[0058] Step 2: Upsampling. The transmitter can upsample the first mapped signal and the second mapped signal, respectively, to obtain the first sampled signal and the second sampled signal. Upsampling converts a discrete digital signal into a continuous analog signal.

[0059] Step 3: Transmitter root-raised cosine low-pass filtering. The transmitter can perform root-raised cosine low-pass filtering on the first and second sampled signals respectively to obtain the first and second baseband signals.

[0060] Step 4: Up-conversion. The transmitter can determine the upper left and upper right conversion frequencies based on the preset transmitter device bandwidth. Then, the upper left conversion complex sine wave signal corresponding to the upper left conversion frequency is mixed with the transmitter's first baseband signal to obtain the upper left conversion baseband signal. And, the upper right conversion complex sine wave signal corresponding to the upper right conversion frequency is mixed with the transmitter's second baseband signal to obtain the upper right conversion baseband signal.

[0061] Here, left and right represent the relative zero frequency position. The transmitter can perform left-up frequency conversion on either the first baseband signal or the second baseband signal, and right-up frequency conversion on the other to obtain an equivalent result, which is not restricted here.

[0062] Step 5: Hilbert Transform. The transmitter can perform Hilbert transforms on the upper left and upper right frequency-converted baseband signals respectively, obtaining the transmitter's left-side and right-side baseband signals. Through the Hilbert transform, the transmitter can convert the upper left and upper right frequency-converted baseband signals, which are real-part signals, into corresponding complex signals.

[0063] Step Six: Add Auxiliary Carriers. First, the transmitter can determine the power of the left-side auxiliary carrier and the power of the right-side auxiliary carrier based on the power of the signal in the left-side band and the right-side band, respectively. Then, based on the preset bandwidth of the receiver's photodetector and the preset edge slope of the receiver's optical filter, the frequencies of the left-side auxiliary carrier and the right-side auxiliary carrier can be determined. In other words, the power and frequency of the auxiliary carriers are adjustable. The frequencies of the left-side and right-side auxiliary carriers can be equal or unequal; this is not restricted here.

[0064] Then, the transmitter can determine the left-side auxiliary carrier based on the left-side auxiliary carrier power and the left-side auxiliary carrier frequency; and determine the right-side auxiliary carrier based on the right-side auxiliary carrier power and the right-side auxiliary carrier frequency.

[0065] Finally, the transmitter can add the left-side auxiliary carrier and the right-side auxiliary carrier to the transmitter's left-side signal and right-side signal respectively, thus obtaining the transmitter's first electrical signal and second electrical signal, thereby completing the transmitter's digital signal processing.

[0066] In this embodiment of the invention, if the frequency of the left-side auxiliary carrier and the frequency of the right-side auxiliary carrier are equal, the process of adding the left-side auxiliary carrier to the left-side signal of the transmitter can be expressed as equation (1), and the process of adding the right-side auxiliary carrier to the right-side signal of the transmitter can be expressed as equation (2). (1) (2) In equations (1) and (2) above, and These represent the first electrical signal and the second electrical signal transmitted from the transmitting end, respectively. and These represent the amplitudes of the signal bands on the left and right sides of the transmitter, respectively. and These represent the phases of the transmitter with signal on the left and the transmitter with signal on the right, respectively. and These represent the top left and top right frequency conversion frequencies, respectively. and These represent the left side of the transmitter and the right side of the transmitter after up-conversion, respectively. and These represent the frequency with the auxiliary carrier on the left and the amplitude with the auxiliary carrier on the right, respectively. This indicates the frequencies with auxiliary carriers on the left and right. and These represent left-side auxiliary carrier and right-side auxiliary carrier, respectively.

[0067] Understandably, integrating digital signal processing at the transmitter can effectively reduce costs.

[0068] Simultaneously, adding auxiliary carriers to both sides of the asymmetric twin single-sideband signal can improve spectrum utilization and reduce the effects of dispersion and symbol time shift. Furthermore, both the power and frequency of the auxiliary carriers can be set; thus, on the one hand, by adjusting the power of the auxiliary carriers to match the power of the corresponding single-sideband signal, the sensitivity of the photodetector at the receiving end can be improved; on the other hand, by adjusting the frequency of the auxiliary carriers, the frequency difference between the auxiliary carriers and the sideband signal can be flexibly adjusted, thereby reducing the bandwidth requirements of the photodetector at the receiving end and also reducing the left / right downconversion frequency.

[0069] S103. Electro-optic modulation is performed based on the first electrical signal and the second electrical signal of the transmitting end to obtain the transmitted optical signal.

[0070] In this embodiment of the invention, after obtaining the first electrical signal and the second electrical signal, the transmitting end can perform electro-optic modulation based on the first electrical signal and the second electrical signal to obtain a transmitted optical signal. The transmitted optical signal is an asymmetric twin single-sideband optical signal with an auxiliary carrier and a suppressed central optical carrier.

[0071] In this embodiment of the invention, the transmitting end can obtain the center optical carrier from an external cavity laser (ECL).

[0072] Meanwhile, the transmitting end can sum the first electrical signal and the second electrical signal of the transmitting end to obtain the superimposed electrical signal to be modulated, as shown in the following formula (3): (3) In the above formula (3), This indicates that the electrical signal to be modulated is superimposed. and These represent the first electrical signal and the second electrical signal from the transmitting end, respectively.

[0073] The transmitter can acquire the superimposed electrical signal to be modulated. The real and imaginary components are used as the I-path and Q-path drive signals, respectively, where the I-path and Q-path drive signals are orthogonal. Due to the first electrical signal at the transmitting end... and the second electrical signal from the transmitting end Both are complex signals; therefore, the superimposed electrical signals to be modulated... As and The sum of these is also a complex signal, which includes both real and imaginary components.

[0074] Finally, the transmitting end can use an I / Q modulator to perform electro-optic modulation based on the center optical carrier, the I-path drive signal, and the Q-path drive signal in carrier suppression modulation mode to obtain the transmitted optical signal. The carrier suppression modulation mode can be achieved by setting the bias voltage of the I / Q modulator.

[0075] It is understandable that electro-optic modulation under carrier suppression modulation can produce a transmitted optical signal with the center optical carrier suppressed, thereby improving the power efficiency of the transmitted optical signal.

[0076] S104. Transmit optical signals to the receiving end.

[0077] In this embodiment of the invention, after receiving the transmitted optical signal, the transmitting end can transmit the transmitted optical signal to the receiving end through an optical fiber.

[0078] Understandably, by performing digital signal processing on the two digital signals at the transmitting end, adding an auxiliary carrier, and then performing electro-optic modulation under carrier suppression, an asymmetric twin single-sideband signal with an auxiliary carrier and a suppressed center optical carrier is obtained for transmission. This improves the utilization of the spectrum and reduces the effects of dispersion and symbol time shift; at the same time, it improves the power efficiency of the transmitted optical signal.

[0079] In some embodiments of the present invention, Figure 2 The diagram showing S102 after and S103 before also includes Figure 3 S105, shown below, will be explained in conjunction with each step.

[0080] S105. Amplify the first electrical signal and the second electrical signal at the transmitting end respectively, and amplify the power of the first electrical signal and the second electrical signal at the transmitting end.

[0081] In this embodiment of the invention, before performing electro-optic modulation based on the first electrical signal and the second electrical signal of the transmitting end, the transmitting end can amplify the first electrical signal and the second electrical signal of the transmitting end respectively, so as to amplify the power of the first electrical signal and the second electrical signal of the transmitting end, so that the electro-optic modulation can be performed more smoothly.

[0082] In some embodiments of the present invention, it can be achieved through... Figure 4 The above is achieved by S1031-S1032 shown. Figure 2 S103, shown below, will be explained in conjunction with each step.

[0083] S1031. Obtain the center optical carrier.

[0084] In this embodiment of the invention, the transmitting end can obtain the center optical carrier from the external cavity laser for electro-optic modulation.

[0085] S1032. Electro-optic modulation is performed based on the central optical carrier, the first electrical signal from the transmitting end, and the second electrical signal from the transmitting end to obtain the transmitted optical signal.

[0086] In this embodiment of the invention, after acquiring the center optical carrier, the transmitting end can perform electro-optic modulation based on the center optical carrier, the first electrical signal from the transmitting end, and the second electrical signal from the transmitting end, under carrier suppression modulation state, to obtain a transmitted optical signal. The transmitted optical signal is obtained by suppressing the center optical carrier. In some embodiments of the present invention, Figure 2 The diagram showing S103 after S103 and S104 before S104 also includes Figure 5 S106, shown below, will be explained in conjunction with each step.

[0087] S106. Amplify the transmitted optical signal to increase its power.

[0088] In this embodiment of the invention, before transmitting the optical signal to the receiver, the transmitting end can amplify the optical signal to increase its power in order to compensate for the loss of the optical signal during transmission.

[0089] In some embodiments of the present invention, it can be achieved through... Figure 6 The shown S201~S202 implement Figure 2 S102, shown below, will be explained in conjunction with each step.

[0090] S201. Based on the first digital signal and the second digital signal of the transmitting end, respectively, the left-side band signal and the right-side band signal of the transmitting end are obtained.

[0091] In this embodiment of the invention, the transmitting end can perform QAM mapping, upsampling, root-raised cosine low-pass filtering, upconversion, and Hilbert transform based on the first digital signal and the second digital signal of the transmitting end, respectively, to obtain the left-side band signal and the right-side band signal of the transmitting end.

[0092] S202. Add auxiliary carriers to the left-side signal and the right-side signal of the transmitter respectively to obtain the first electrical signal and the second electrical signal of the transmitter.

[0093] In this embodiment of the invention, after determining the left-side auxiliary carrier and the right-side auxiliary carrier, the transmitting end can add the left-side auxiliary carrier and the right-side auxiliary carrier to the transmitting end's left-side signal and the transmitting end's right-side signal, respectively, thereby obtaining the transmitting end's first electrical signal and the transmitting end's second electrical signal. The power and frequency of the auxiliary carriers are adjustable.

[0094] In some embodiments of the present invention, it can be achieved through... Figure 7 The shown S301~S305 implement Figure 6 The step S201 shown will be explained in conjunction with each step.

[0095] S301. Perform QAM mapping on the first digital signal and the second digital signal of the transmitting end respectively to obtain the first mapped signal and the second mapped signal of the transmitting end.

[0096] In this embodiment of the invention, the transmitting end can perform QAM mapping on the first digital signal and the second digital signal, respectively, to obtain the first mapped signal and the second mapped signal. QAM mapping is a type of vector modulation, and its use can improve spectral efficiency.

[0097] S302. Upsample the first mapped signal and the second mapped signal of the transmitter respectively to obtain the first sampled signal and the second sampled signal of the transmitter.

[0098] In this embodiment of the invention, the transmitting end can upsample the first mapped signal and the second mapped signal to obtain the first sampled signal and the second sampled signal, respectively. Upsampling converts a discrete digital signal into a continuous analog signal.

[0099] S303. Perform root-raised cosine low-pass filtering on the first sampled signal and the second sampled signal of the transmitter to obtain the first baseband signal and the second baseband signal of the transmitter.

[0100] In this embodiment of the invention, the transmitting end can perform root-raised cosine low-pass filtering on the first sampling signal and the second sampling signal of the transmitting end respectively to obtain the first baseband signal and the second baseband signal of the transmitting end.

[0101] S304. The first baseband signal and the second baseband signal of the transmitting end are converted to the upper left and the upper right respectively, to obtain the upper left and upper right frequency-converted baseband signals.

[0102] In this embodiment of the invention, the transmitting end can determine the upper left conversion frequency and the upper right conversion frequency respectively; then, based on the upper left conversion frequency and the upper right conversion frequency, the first baseband signal and the second baseband signal of the transmitting end are converted to the upper left and the upper right respectively, so as to obtain the upper left conversion baseband signal and the upper right conversion baseband signal.

[0103] Here, left and right represent the relative zero frequency position. The transmitter can perform left-up frequency conversion on either the first baseband signal or the second baseband signal, and right-up frequency conversion on the other to obtain an equivalent result, which is not restricted here.

[0104] S305. Perform Hilbert transform on the upper left and upper right frequency conversion baseband signals respectively to obtain the left side band signal and the right side band signal of the transmitter.

[0105] In this embodiment of the invention, the transmitting end can perform Hilbert transform on the upper left and upper right frequency conversion baseband signals respectively, transforming the upper left and upper right frequency conversion baseband signals, which are real part signals, into corresponding complex signals, thereby obtaining the transmitting end left band signal and the transmitting end right band signal.

[0106] In some embodiments of the present invention, Figure 7 Before S304 shown, there is also S3041, which will be explained in conjunction with each step.

[0107] S3041. Based on the bandwidth of the transmitting device, determine the upper left and upper right conversion frequencies.

[0108] In this embodiment of the invention, the transmitter can determine the upper left and upper right conversion frequencies based on the preset transmitter device bandwidth, so as to convert the first baseband signal and the second baseband signal of the transmitter to the upper left and upper right respectively.

[0109] In some embodiments of the present invention, this can be achieved through S3042. Figure 7 S304, shown below, will be explained in conjunction with each step.

[0110] S3042. Mix the upper left-converted complex sine wave signal with the first baseband signal of the transmitting end to obtain the upper left-converted baseband signal; wherein, the upper left-converted complex sine wave signal is the complex sine wave signal corresponding to the upper left-converted frequency; and mix the upper right-converted complex sine wave signal with the second baseband signal of the transmitting end to obtain the upper right-converted baseband signal; wherein, the upper right-converted complex sine wave signal is the complex sine wave signal corresponding to the upper right-converted frequency.

[0111] In this embodiment of the invention, the transmitting end can mix the upper left-converted complex sine wave signal corresponding to the upper left-converted frequency with the first baseband signal of the transmitting end to obtain the upper left-converted baseband signal, thereby completing the upper left-converted frequency; at the same time, the upper right-converted complex sine wave signal corresponding to the upper right-converted frequency is mixed with the second baseband signal of the transmitting end to obtain the upper right-converted baseband signal, thereby completing the upper right-converted frequency.

[0112] In some embodiments of the present invention, Figure 6 Before S202 shown, it also includes Figure 8 S2021 to S2023 shown will be explained in conjunction with each step.

[0113] S2021. Based on the power of the signal on the left side of the transmitter and the power of the signal on the right side of the transmitter, determine the auxiliary carrier power of the left side and the auxiliary carrier power of the right side respectively.

[0114] In this embodiment of the invention, after obtaining the left-side and right-side signals, the transmitting end can determine the power of the left-side auxiliary carrier and the power of the right-side auxiliary carrier based on the power of the left-side and right-side signals, respectively. The closer the power of the left / right-side auxiliary carrier is to the power of the left / right-side signals of the transmitting end, the better the effect of adding the auxiliary carrier.

[0115] S2022. Based on the bandwidth of the photodetector at the receiving end and the edge slope of the optical filter at the receiving end, determine the auxiliary carrier frequency of the left band and the auxiliary carrier frequency of the right band respectively.

[0116] In this embodiment of the invention, the transmitting end can reserve a protection interval based on the preset edge slope of the receiving end optical filter; then, based on the preset bandwidth of the receiving end photodetector, a suitable left-side auxiliary carrier frequency and right-side auxiliary carrier frequency are determined.

[0117] S2023. Determine the left-side auxiliary carrier based on the left-side auxiliary carrier power and the left-side auxiliary carrier frequency; and determine the right-side auxiliary carrier based on the right-side auxiliary carrier power and the right-side auxiliary carrier frequency.

[0118] In this embodiment of the invention, after determining the power and frequency of the left / right band auxiliary carrier, the transmitting end can determine the left band auxiliary carrier based on the power and frequency of the left band auxiliary carrier; at the same time, it can determine the right band auxiliary carrier based on the power and frequency of the right band auxiliary carrier.

[0119] In some embodiments of the present invention, it can be achieved through... Figure 8 The implementation shown in S2024 Figure 6 The step S202 shown will be explained in conjunction with each step.

[0120] S2024. Add the left-side auxiliary carrier and the right-side auxiliary carrier to the left-side signal and the right-side signal of the transmitter, respectively, to obtain the first electrical signal and the second electrical signal of the transmitter.

[0121] In this embodiment of the invention, the transmitting end can add the left-side auxiliary carrier and the right-side auxiliary carrier to the left-side signal and the right-side signal of the transmitting end, respectively, so as to obtain the first electrical signal and the second electrical signal of the transmitting end.

[0122] In some embodiments of the present invention, it can be implemented via S2025~S2026. Figure 8S2024, shown below, will be explained in conjunction with each step.

[0123] S2025. Add the complex signal expression corresponding to the signal on the left side of the transmitter to the complex signal expression corresponding to the auxiliary carrier on the left side to obtain the complex signal expression corresponding to the first electrical signal of the transmitter, thereby obtaining the first electrical signal of the transmitter.

[0124] In this embodiment of the invention, as shown in the above formula (1), the transmitting end can add the complex signal expression corresponding to the signal on the left side of the transmitting end to the complex signal expression corresponding to the auxiliary carrier on the left side of the transmitting end to obtain the complex signal expression corresponding to the first electrical signal of the transmitting end, thereby obtaining the first electrical signal of the transmitting end.

[0125] S2026. Add the complex signal expression corresponding to the right-side carrier signal of the transmitter to the complex signal expression corresponding to the auxiliary carrier on the right side to obtain the complex signal expression corresponding to the second electrical signal of the transmitter, thereby obtaining the second electrical signal of the transmitter.

[0126] In this embodiment of the invention, as shown in equation (2) above, the transmitting end can add the complex signal expression corresponding to the signal on the right side of the transmitting end to the complex signal expression corresponding to the auxiliary carrier on the right side to obtain the complex signal expression corresponding to the second electrical signal of the transmitting end, thereby obtaining the second electrical signal of the transmitting end.

[0127] In some embodiments of the present invention, the above can be achieved through S1033-S1035. Figure 4 S1032, shown below, will be explained in conjunction with each step.

[0128] S1033. Summing the first electrical signal and the second electrical signal at the transmitting end yields the superimposed electrical signal to be modulated.

[0129] In this embodiment of the invention, as shown in the above formula (3), the transmitting end can sum the first electrical signal and the second electrical signal of the transmitting end to obtain the superimposed electrical signal to be modulated.

[0130] S1034. Obtain the real and imaginary components of the superimposed electrical signal to be modulated, and use them as the I-path driving signal and the Q-path driving signal, respectively; the I-path driving signal and the Q-path driving signal are orthogonal to each other.

[0131] In this embodiment of the invention, after acquiring the superimposed electrical signal to be modulated, the transmitting end can acquire the real and imaginary components of the superimposed electrical signal to be modulated, which are used as the I-path driving signal and Q-path driving signal of the I / Q modulator, respectively. The I-path driving signal and the Q-path driving signal are orthogonal to each other.

[0132] S1035. Under carrier suppression modulation, electro-optic modulation is performed based on the center optical carrier, the I-path driving signal and the Q-path driving signal to obtain the transmitted optical signal.

[0133] In this embodiment of the invention, the transmitting end can use an I / Q modulator to perform electro-optic modulation based on the center optical carrier, the I-path driving signal, and the Q-path driving signal in carrier suppression modulation state to obtain the transmitted optical signal. The carrier suppression modulation state can be achieved by setting the bias voltage of the I / Q modulator.

[0134] Figure 9 This is an optional flowchart illustrating a signal processing method provided in an embodiment of the present invention, which will be combined with... Figure 9 The steps shown are explained.

[0135] S401, Receive and transmit optical signals.

[0136] In this embodiment of the invention, the receiving end can receive the transmitted optical signal via an optical fiber. The transmitted optical signal can be sent by the transmitting end; by processing the transmitted optical signal, the information to be transmitted contained therein can be obtained, thereby realizing the transmission of information.

[0137] S402, the transmitted optical signal is divided into a first optical signal at the receiving end and a second optical signal at the receiving end; the first optical signal at the receiving end and the second optical signal at the receiving end contain the same content as the transmitted optical signal.

[0138] In this embodiment of the invention, after receiving the transmitted optical signal, the receiving end can divide the transmitted optical signal into a first optical signal and a second optical signal. The first and second optical signals contain the same content as the transmitted optical signal; that is, the first and second optical signals are copies of the transmitted optical signal.

[0139] S403. Left-side band signal filtering and right-side band signal filtering are performed on the first optical signal and the second optical signal at the receiving end, respectively, to obtain the right-side band optical signal and the left-side band optical signal at the receiving end. The right-side band optical signal at the receiving end includes the right-side band auxiliary carrier, and the left-side band optical signal at the receiving end includes the left-side band auxiliary carrier.

[0140] In this embodiment of the invention, after receiving the first optical signal and the second optical signal, the receiving end can filter out the left-side band signal of the first optical signal to obtain the right-side band optical signal, wherein the right-side band optical signal includes the right-side auxiliary carrier; at the same time, the receiving end can filter out the right-side band signal of the second optical signal to obtain the left-side band optical signal, wherein the left-side band optical signal includes the left-side auxiliary carrier.

[0141] In this embodiment of the invention, the receiving end can obtain the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal in advance; then, based on the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal, the passband center frequency and passband bandwidth of the sideband optical signal filtering unit are set to perform left-side band signal filtering and right-side band signal filtering.

[0142] In this embodiment of the invention, the sideband signal frequency includes: the left sideband signal frequency and the right sideband signal frequency; the auxiliary carrier frequency includes: the left sideband auxiliary carrier frequency and the right sideband auxiliary carrier frequency.

[0143] The receiver can set the passband bandwidth and passband center frequency corresponding to the left-side band signal filtering based on the right-side band signal frequency and the right-side band auxiliary carrier frequency. The bandwidth corresponding to the left-side band signal filtering should include the right-side band signal frequency and the right-side band auxiliary carrier frequency, while excluding frequencies of other signals in the transmitted optical signal. In this way, after left-side band signal filtering, the receiver retains the right-side band optical signal including the right-side band auxiliary carrier.

[0144] Accordingly, the receiver can set the passband bandwidth and passband center frequency corresponding to the right-band signal filtering based on the left-band signal frequency and the left-band auxiliary carrier frequency. The bandwidth corresponding to the right-band signal filtering should include the left-band signal frequency and the left-band auxiliary carrier frequency, while excluding the frequencies of other signals in the transmitted optical signal. In this way, after right-band signal filtering, the receiver retains the left-band optical signal containing the left-band auxiliary carrier.

[0145] S404. Perform photoelectric conversion on the light signal on the left side of the receiver and the light signal on the right side of the receiver respectively to obtain the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver.

[0146] In this embodiment of the invention, after the receiving end obtains the optical signal on the left side of the receiving end and the optical signal on the right side of the receiving end, it can perform photoelectric conversion on the optical signal on the left side of the receiving end and the optical signal on the right side of the receiving end respectively, converting the optical signal into an electrical signal, thereby obtaining the electrical signal on the left side of the receiving end and the electrical signal on the right side of the receiving end.

[0147] In this embodiment of the invention, the receiving end can perform photoelectric conversion on the optical signal of the left band based on the left band auxiliary carrier frequency to obtain the electrical signal of the left band. Correspondingly, the receiving end can perform photoelectric conversion on the optical signal of the right band based on the right band auxiliary carrier frequency to obtain the electrical signal of the right band.

[0148] Understandably, since the auxiliary carrier power and frequency at the transmitting end can be set, the sensitivity of the photodetector used for photoelectric conversion at the receiving end is improved, and the bandwidth requirement of the photodetector is reduced, thereby improving the performance of the receiving end.

[0149] S405. Perform receiving end digital signal processing on the left-side charged signal and the right-side charged signal of the receiving end respectively to obtain the receiving end first digital signal and the receiving end second digital signal; the receiving end first digital signal and the receiving end second digital signal contain the information to be transmitted.

[0150] In this embodiment of the invention, the receiving end can perform receiving end digital signal processing on the charged signal on the left side of the receiving end and the charged signal on the right side of the receiving end respectively, to obtain a first receiving end digital signal and a second receiving end digital signal. The first receiving end digital signal and the second receiving end digital signal contain the information to be transmitted.

[0151] In this embodiment of the invention, the digital signal processing at the receiving end may include the following steps: Step 1: Resampling. The receiver can resample the charged signal on the left and the charged signal on the right, respectively, to obtain the first sampled signal and the second sampled signal.

[0152] Step 2: Down-conversion. The receiver can obtain the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal in advance. The sideband signal frequency includes the left sideband signal frequency and the right sideband signal frequency; the auxiliary carrier frequency includes the left sideband auxiliary carrier frequency and the right sideband auxiliary carrier frequency.

[0153] Then, the receiver can use the difference between the left-side band signal frequency and the left-side band auxiliary carrier frequency as the lower-left conversion frequency. For example, if the left-side band signal frequency is... The frequency of the auxiliary carrier on the left is Then the frequency of the lower left inverter is Then, the left-down-converted complex sine wave signal corresponding to the left-down-converted frequency is mixed with the first sampled signal at the receiving end to obtain the left-down-converted baseband signal, thus completing the left-down-conversion.

[0154] Accordingly, the difference between the right-side signal frequency and the right-side auxiliary carrier frequency is taken as the right-side down-conversion frequency. For example, if the right-side signal frequency is... The frequency of the auxiliary carrier on the right is The frequency of the lower right inverter is Then, the right-down frequency conversion complex sine wave signal corresponding to the right-down frequency conversion is mixed with the second sampling signal at the receiving end to obtain the right-down frequency conversion baseband signal, thus completing the right-down frequency conversion.

[0155] Step 3: Root-raised cosine low-pass filtering at the receiver. The receiver can perform root-raised cosine low-pass filtering on the lower left and lower right frequency-converted baseband signals respectively, based on the roll-off factor, to obtain the first and second baseband signals at the receiver. The roll-off factor can be selected as 0.01. Root-raised cosine low-pass filtering at the receiver can eliminate residual sideband crosstalk and improve the signal-to-noise ratio.

[0156] Step 4: Channel Equalization. The receiver can perform channel equalization on the first baseband signal and the second baseband signal, respectively, to obtain the first channel equalized signal and the second channel equalized signal. Channel equalization can be achieved using a cascaded multi-mode algorithm, which can eliminate interference caused by the channel during transmission.

[0157] Step 5: QAM Demapping. The receiver can obtain the modulation format of the QAM mapping corresponding to the transmitted optical signal in advance; then, using the same modulation format as the QAM mapping, QAM demapping is performed on the first channel equalization signal and the second channel equalization signal respectively, thus obtaining the receiver's first digital signal and receiver's second digital signal, thereby completing the receiver's digital signal processing.

[0158] Understandably, integrated digital signal processing at the receiver can effectively reduce costs. Furthermore, since both the power and frequency of the auxiliary carrier at the transmitter can be set, the frequency difference between the auxiliary carrier and the sideband signal can be flexibly adjusted by regulating the auxiliary carrier's frequency, thereby reducing the left / right downconversion frequency.

[0159] In some embodiments of the present invention, Figure 9 The diagram showing S404 after and S405 before also includes Figure 10 S406, shown below, will be explained in conjunction with each step.

[0160] S406. Amplify the power of the charged signal on the left and the charged signal on the right of the receiver respectively.

[0161] In this embodiment of the invention, before performing digital signal processing on the left and right charged signals of the receiving end, the receiving end can amplify the left and right charged signals of the receiving end respectively to increase their power, so that the digital signal processing at the receiving end can proceed more smoothly.

[0162] In some embodiments of the present invention, it can be achieved through... Figure 11 The shown S501~S505 implement Figure 9 The S405 shown will be explained in conjunction with each step.

[0163] S501. Resample the charged signal on the left side of the receiver and the charged signal on the right side of the receiver respectively to obtain the first sampled signal and the second sampled signal of the receiver.

[0164] In this embodiment of the invention, the receiving end can resample the charged signal on the left side of the receiving end and the charged signal on the right side of the receiving end respectively to obtain the first sampled signal and the second sampled signal of the receiving end.

[0165] S502. The first sampled signal and the second sampled signal at the receiving end are converted to the left and right respectively to obtain the left-down-converted baseband signal and the right-down-converted baseband signal.

[0166] In this embodiment of the invention, the receiving end can determine the lower left conversion frequency and the lower right conversion frequency; then, the lower left conversion complex sine wave signal corresponding to the lower left conversion frequency is mixed with the first sampling signal of the receiving end to obtain the lower left conversion baseband signal, thereby completing the lower left conversion; at the same time, the lower right conversion complex sine wave signal corresponding to the lower right conversion frequency is mixed with the second sampling signal of the receiving end to obtain the lower right conversion baseband signal, thereby completing the lower right conversion.

[0167] S503. Perform root-raised cosine low-pass filtering on the lower left and lower right frequency-converted baseband signals respectively to obtain the first baseband signal and the second baseband signal at the receiving end.

[0168] In this embodiment of the invention, the receiving end can perform root-raised cosine low-pass filtering on the lower left and lower right frequency-converted baseband signals respectively, resulting in the receiving end first baseband signal and the receiving end second baseband signal. The receiving end root-raised cosine low-pass filtering can eliminate residual sideband crosstalk and improve the signal-to-noise ratio.

[0169] S504. Channel equalization is performed on the first baseband signal and the second baseband signal at the receiving end respectively to obtain the first channel equalization signal and the second channel equalization signal.

[0170] In this embodiment of the invention, the receiving end can perform channel equalization on the first baseband signal and the second baseband signal of the receiving end respectively to obtain the first channel equalization signal and the second channel equalization signal.

[0171] S505. Perform QAM demapping on the first channel equalization signal and the second channel equalization signal respectively to obtain the first digital signal and the second digital signal at the receiving end.

[0172] In this embodiment of the invention, the receiving end can perform QAM demapping on the first channel equalization signal and the second channel equalization signal respectively to obtain the receiving end first digital signal and the receiving end second digital signal, thereby completing the receiving end digital signal processing.

[0173] Understandably, after the receiving end couples the transmitted optical signal into two identical optical signals, it filters out the single-sideband signal from each signal and then uses digital signal processing at the receiving end to extract the digital signal containing the information to be transmitted. This completes the transmission of asymmetric twin single-sideband optical signals with an auxiliary carrier, thereby improving spectrum utilization and reducing the effects of dispersion and symbol time shift.

[0174] In some embodiments of the present invention, this can be achieved through S5041. Figure 11 The S504 shown will be explained in conjunction with each step.

[0175] S5041. Perform cascaded multimode algorithm equalization on the first baseband signal and the second baseband signal at the receiving end respectively to obtain the first channel equalized signal and the second channel equalized signal.

[0176] In this embodiment of the invention, the receiving end can perform cascaded multi-mode algorithm equalization on the first baseband signal and the second baseband signal of the receiving end respectively to eliminate interference caused by the channel during transmission, and obtain the first channel equalization signal and the second channel equalization signal accordingly.

[0177] In some embodiments of the present invention, Figure 9 The step S401 shown also includes step S506, which will be explained in conjunction with each step.

[0178] S506. Obtain the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal.

[0179] In this embodiment of the invention, after determining the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal, the transmitting end can synchronize them to the receiving end. The receiving end obtains the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal and can use them as parameters for digital signal processing at the receiving end.

[0180] In some embodiments of the present invention, Figure 9 Before S403 shown, there is also S4031, which will be explained in conjunction with each step.

[0181] S4031. Based on the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal, set the passband bandwidth and passband center frequency.

[0182] In this embodiment of the invention, after the receiving end obtains the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal, it can set the passband center frequency and passband bandwidth of the sideband optical signal filtering unit based on the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal to perform left-side band signal filtering and right-side band signal filtering.

[0183] Specifically, the bandwidth corresponding to left-side band signal filtering should include the right-side band signal frequency and the right-side band auxiliary carrier frequency, while excluding the frequencies of other signals in the transmitted optical signal. Similarly, the bandwidth corresponding to right-side band signal filtering should include the left-side band signal frequency and the left-side band auxiliary carrier frequency, while excluding the frequencies of other signals in the transmitted optical signal.

[0184] In some embodiments of the present invention, this can be achieved through S4032. Figure 9 The S403 shown will be explained in conjunction with each step.

[0185] S4032. Based on the passband bandwidth and passband center frequency, the left-side band signal is filtered out and the right-side band signal is filtered out for the first optical signal and the second optical signal at the receiving end, respectively, to obtain the right-side band optical signal and the left-side band optical signal at the receiving end.

[0186] In this embodiment of the invention, after the passband bandwidth and passband center frequency are set, the receiving end can perform left-side band signal filtering and right-side band signal filtering on the first optical signal and the second optical signal of the receiving end, respectively, based on the passband bandwidth and passband center frequency, to obtain the right-side band optical signal and the left-side band optical signal of the receiving end.

[0187] In this process, the first optical signal at the receiving end, after being filtered out of the left-side band signal, retains the right-side band optical signal containing the right-side band auxiliary carrier. Similarly, the second optical signal at the receiving end, after being filtered out of the right-side band signal, retains the left-side band optical signal containing the left-side band auxiliary carrier.

[0188] In some embodiments of the present invention, the sideband signal frequency includes: a left sideband signal frequency and a right sideband signal frequency; the auxiliary carrier frequency includes: a left sideband auxiliary carrier frequency and a right sideband auxiliary carrier frequency; in Figure 11 Before S502 shown, there is also S5021, which will be explained in conjunction with each step.

[0189] S5021. Subtract the left-side band signal frequency from the left-side band auxiliary carrier frequency to obtain the left-side lower frequency conversion; and subtract the right-side band signal frequency from the right-side band auxiliary carrier frequency to obtain the right-side lower frequency conversion.

[0190] In this embodiment of the invention, after acquiring the sideband signal frequency and the auxiliary carrier frequency, the receiving end can subtract the left-sideband signal frequency from the left-sideband auxiliary carrier frequency to obtain the left-lower conversion frequency. For example, if the left-sideband signal frequency is... The frequency of the auxiliary carrier on the left is Then the frequency of the lower left inverter is Furthermore, subtracting the right-side band signal frequency from the right-side band auxiliary carrier frequency yields the right-lower conversion frequency. For example, if the right-side band signal frequency is... The frequency of the auxiliary carrier on the right is The frequency of the lower right inverter is .

[0191] In some embodiments of the present invention, this can be achieved through S5022. Figure 11 The S502 shown will be explained in conjunction with each step.

[0192] S5022. Mix the left-lower frequency-converted complex sine wave signal with the first sampling signal at the receiving end to obtain the left-lower frequency-converted baseband signal; wherein, the left-lower frequency-converted complex sine wave signal is the complex sine wave signal corresponding to the left-lower frequency conversion frequency; and mix the right-lower frequency-converted complex sine wave signal with the second sampling signal at the receiving end to obtain the right-lower frequency-converted baseband signal; wherein, the right-lower frequency-converted complex sine wave signal is the complex sine wave signal corresponding to the right-lower frequency conversion frequency.

[0193] In this embodiment of the invention, after determining the lower left and lower right conversion frequencies, the receiving end can mix the lower left conversion complex sine wave signal corresponding to the lower left conversion frequency with the first sampling signal of the receiving end to obtain the lower left conversion baseband signal, thereby completing the lower left conversion; at the same time, the lower right conversion complex sine wave signal corresponding to the lower right conversion frequency is mixed with the second sampling signal of the receiving end to obtain the lower right conversion baseband signal, thereby completing the lower right conversion.

[0194] In some embodiments of the present invention, this can be achieved through S5031. Figure 11 The S503 shown will be explained in conjunction with each step.

[0195] S5031. Based on the roll-off coefficient, the lower left and lower right frequency conversion baseband signals are subjected to root raised cosine low-pass filtering at the receiving end to obtain the first baseband signal and the second baseband signal at the receiving end.

[0196] In this embodiment of the invention, the receiving end can perform root-raised cosine low-pass filtering on the lower left and lower right frequency-converted baseband signals based on the roll-off factor, respectively, to obtain the first baseband signal and the second baseband signal at the receiving end. The roll-off factor can be selected as 0.01. Root-raised cosine low-pass filtering at the receiving end can eliminate residual sideband crosstalk and improve the signal-to-noise ratio.

[0197] In some embodiments of the present invention, Figure 9 The illustrated S401 is preceded by S507, which can be implemented via S5051. Figure 11 The S505 shown will be explained in conjunction with each step.

[0198] S507. Obtain the QAM mapping modulation format corresponding to the transmitted optical signal.

[0199] In this embodiment of the invention, after determining the QAM mapping modulation format corresponding to the transmitted optical signal, the transmitting end can synchronize it to the receiving end. The receiving end obtains the QAM mapping modulation format corresponding to the transmitted optical signal and can use it as a parameter for QAM demapping.

[0200] S5051. Based on the QAM mapping modulation format, QAM demapping is performed on the first channel equalization signal and the second channel equalization signal respectively to obtain the first digital signal and the second digital signal at the receiving end.

[0201] In this embodiment of the invention, the receiving end can use the same modulation format as QAM mapping to perform QAM demapping on the first channel equalization signal and the second channel equalization signal respectively, thereby obtaining the receiving end first digital signal and the receiving end second digital signal.

[0202] Figure 12 This is an optional flowchart illustrating a signal processing method provided in an embodiment of the present invention, which will be combined with... Figure 12 The steps shown are explained.

[0203] S601, the transmitter performs QAM mapping, upsampling and root-raised cosine low-pass filtering on the first digital signal and the second digital signal respectively to obtain the transmitter's first baseband signal and the transmitter's second baseband signal.

[0204] In embodiments of the present invention, such as Figure 13 As shown, after acquiring the two binary data streams, the first digital signal and the second digital signal, the transmitter can perform QAM mapping (i.e., S701), upsampling (i.e., S702), and root raised cosine low-pass filtering (i.e., S703) to obtain the analog first baseband signal and the second baseband signal of the transmitter.

[0205] S602. The transmitter performs left-up frequency conversion and right-up frequency conversion on the first baseband signal and the second baseband signal respectively, and performs Hilbert transformation to obtain the left-side band signal and the right-side band signal.

[0206] In this embodiment of the invention, the transmitting end can determine the upper left and upper right conversion frequencies based on the bandwidth of the transmitting end device. Here, the left and right directions refer to the position relative to zero frequency, and the two sidebands moving left or right are equivalent. Furthermore, as... Figure 13 As shown, the transmitter can perform left-up conversion and right-up conversion on the first baseband signal and the second baseband signal, respectively, based on the left-up conversion frequency and the right-up conversion frequency (i.e., S704). Then, a Hilbert transform is performed on the up-converted signals (i.e., S705) to obtain the left-side band signal and the right-side band signal of the transmitter.

[0207] S603, The transmitter adds auxiliary carriers to the left-side signal and the right-side signal of the transmitter respectively, thereby obtaining the first electrical signal and the second electrical signal of the transmitter.

[0208] In this embodiment of the invention, the transmitting end can determine the matching auxiliary carrier power based on the power of the left / right sideband signals of the transmitting end; simultaneously, considering the edge slope of the optical filter to reserve a guard interval, a suitable auxiliary carrier frequency is selected based on the bandwidth of the photodetector. Then, the transmitting end can add the auxiliary carrier corresponding to the determined power and frequency to the left / right sideband signals of the transmitting end, thereby obtaining a first electrical signal and a second electrical signal from the transmitting end. The first and second electrical signals from the transmitting end are asymmetric twin single-sideband electrical signals with auxiliary carriers.

[0209] S604. The transmitter performs photoelectric modulation on the first electrical signal and the second electrical signal to obtain the transmitted optical signal.

[0210] In embodiments of the present invention, such as Figure 13 As shown, the transmitting end can extract the real and imaginary parts of the first electrical signal from the transmitting end to obtain I. L and Q L And by taking the real and imaginary parts of the second electrical signal from the transmitting end, we obtain I. R and Q R ; will I L and I R Merge to get I, then Q L and Q R The I and Q signals are then combined to obtain Q; subsequently, I and Q are used as the I-path and Q-path drive signals of the I / Q modulator, respectively.

[0211] The transmitter can set the bias voltage of the I / Q modulator to make it work in carrier suppression modulation state. After photoelectric modulation, it outputs a transmission optical signal, which is an asymmetric twin single-sideband optical signal with an auxiliary carrier whose central optical carrier is suppressed.

[0212] S605 The receiving end performs optical bandpass filtering based on the transmitted optical signal and performs photoelectric conversion to obtain the charged signal on the left side of the receiving end and the charged signal on the right side of the receiving end.

[0213] In this embodiment of the invention, the receiving end can use two sets of optical bandpass filters and photodetectors for separate reception. The receiving end can split the transmitted optical signal into two identical optical signals and then perform optical bandpass filtering on each, obtaining a left-side optical signal and a right-side optical signal. Since the center frequency and passband bandwidth of each set of optical bandpass filters are set differently, the left-side optical signal retains the left-side signal and the corresponding auxiliary carrier signal, while the right-side optical signal retains the right-side signal and the corresponding auxiliary carrier signal.

[0214] Then, the receiving end can use a photodetector to perform photoelectric conversion on the light signal on the left side of the receiving end and the light signal on the right side of the receiving end, respectively, to obtain the electrical signal on the left side of the receiving end and the electrical signal on the right side of the receiving end.

[0215] S606. The receiving end performs digital signal processing on the left and right charged signals of the receiving end respectively to obtain the first digital signal and the second digital signal of the receiving end.

[0216] In embodiments of the present invention, such as Figure 14 As shown, the receiver can first resample the charged signals on the left and right sides of the receiver (i.e., S707); then, it can downconvert the resampled signals to the left and to the right (i.e., S708), where the downconversion frequency is the difference between the sideband signal frequency and the corresponding auxiliary carrier frequency; then, it can perform root-raised cosine low-pass filtering on the downconverted baseband signal (i.e., S709), using the root-raised cosine low-pass filter to filter out redundant sideband signals; then, it can perform channel equalization on the low-pass filtered signals using a cascaded multimode algorithm (i.e., S710); finally, it can demodulate the binary sequence, i.e., the first digital signal and the second digital signal of the receiver, through QAM demapping (i.e., S711).

[0217] Understandably, adding auxiliary carriers to both sides of an asymmetric twin single-sideband signal can improve spectrum utilization and reduce the effects of dispersion and symbol time shift. Furthermore, both the power and frequency of the auxiliary carriers can be set; thus, on the one hand, by adjusting the power of the auxiliary carriers to match the corresponding single-sideband signal power, the sensitivity of the photodetector at the receiving end can be improved; on the other hand, by adjusting the frequency of the auxiliary carriers, the frequency difference between the auxiliary carriers and the sideband signal can be flexibly adjusted, thereby reducing the bandwidth requirements of the photodetector at the receiving end and also reducing the left / right down-conversion frequency.

[0218] Furthermore, both the transmitter and receiver can perform the corresponding digital signal processing through offline software, thus reducing the system's structural complexity and achieving functional integration. Additionally, the transmitter can utilize only one I / Q modulator and one external cavity laser, effectively reducing costs.

[0219] Figure 15 This is a schematic diagram of an optional structure of the transmitter provided in an embodiment of the present invention. For example... Figure 15 As shown, this embodiment of the invention also provides a transmitter 800, including: a transmitter processor 801, a transmitter memory 802, an electro-optic modulator 803, and an optical signal transmitter 804, wherein: The transmitter processor 801 is configured to execute executable instructions stored in the transmitter memory 802 to obtain a first digital signal and a second digital signal from the transmitter; the first digital signal and the second digital signal from the transmitter contain information to be transmitted; the first digital signal and the second digital signal are processed by the transmitter digital signal processing to obtain a first electrical signal and a second electrical signal from the transmitter; the first electrical signal and the second electrical signal from the transmitter are asymmetric twin single-sideband electrical signals with an auxiliary carrier. The transmitter memory 802 is configured to store instructions and applications executable by the transmitter processor 801; The electro-optic modulator 803 is used to perform electro-optic modulation based on the first electrical signal and the second electrical signal at the transmitting end to obtain the transmitted optical signal; The optical signal transmitter 804 is used to transmit optical signals to the receiving end.

[0220] It should be noted that the transmitter processor 801 and transmitter memory 802 can be applied to the transmitter DSP device 011; the electro-optic modulation unit 806 can be an I / Q modulator 014.

[0221] In some embodiments of the present invention, the transmitter 800 further includes: The transmitting end electrical signal amplifier 805 is used to amplify the first transmitting end electrical signal and the second transmitting end electrical signal respectively, thereby amplifying the power of the first transmitting end electrical signal and the second transmitting end electrical signal.

[0222] It should be noted that the transmitting end electrical signal amplifier 805 can be the transmitting end electrical amplifier 012.

[0223] In some embodiments of the present invention, the electro-optic modulator 803 is further used to acquire a central optical carrier; and to perform electro-optic modulation based on the central optical carrier, the first electrical signal of the transmitting end, and the second electrical signal of the transmitting end to obtain a transmitted optical signal.

[0224] In some embodiments of the present invention, the transmitter 800 further includes: The transmitting optical signal amplifier 806 is used to amplify the transmitted optical signal and increase its power.

[0225] It should be noted that the transmitting optical signal amplifier 806 can be an erbium-doped fiber amplifier 015.

[0226] In some embodiments of the present invention, the transmitter processor 801 is further configured to obtain a transmitter left-side band signal and a transmitter right-side band signal based on the transmitter first digital signal and the transmitter second digital signal, respectively; and to add auxiliary carriers to the transmitter left-side band signal and the transmitter right-side band signal, respectively, to obtain a transmitter first electrical signal and a transmitter second electrical signal.

[0227] In some embodiments of the present invention, the transmitter processor 801 is further configured to perform QAM mapping on the transmitter first digital signal and the transmitter second digital signal respectively, to obtain the transmitter first mapped signal and the transmitter second mapped signal; to upsample the transmitter first mapped signal and the transmitter second mapped signal respectively, to obtain the transmitter first sampled signal and the transmitter second sampled signal respectively; to perform transmitter root raised cosine low-pass filtering on the transmitter first sampled signal and the transmitter second sampled signal respectively, to obtain the transmitter first baseband signal and the transmitter second baseband signal respectively; to perform left-up frequency conversion and right-up frequency conversion on the transmitter first baseband signal and the transmitter second baseband signal respectively, to obtain left-up frequency conversion baseband signal and right-up frequency conversion baseband signal respectively; and to perform Hilbert transform on the left-up frequency conversion baseband signal and the right-up frequency conversion baseband signal respectively, to obtain the transmitter left-side band signal and the transmitter right-side band signal respectively.

[0228] In some embodiments of the present invention, the transmitter processor 801 is further configured to determine the upper left conversion frequency and the upper right conversion frequency based on the bandwidth of the transmitter device; mix the upper left conversion complex sine wave signal with the transmitter's first baseband signal to obtain an upper left conversion baseband signal; wherein the upper left conversion complex sine wave signal is a complex sine wave signal corresponding to the upper left conversion frequency; and mix the upper right conversion complex sine wave signal with the transmitter's second baseband signal to obtain an upper right conversion baseband signal; wherein the upper right conversion complex sine wave signal is a complex sine wave signal corresponding to the upper right conversion frequency.

[0229] In some embodiments of the present invention, the transmitter processor 801 is further configured to: determine the left-side auxiliary carrier power and the right-side auxiliary carrier power respectively based on the power of the left-side signal and the power of the right-side signal; determine the left-side auxiliary carrier frequency and the right-side auxiliary carrier frequency respectively based on the bandwidth of the receiver photodetector and the edge slope of the receiver optical filter; determine the left-side auxiliary carrier according to the left-side auxiliary carrier power and the left-side auxiliary carrier frequency; and determine the right-side auxiliary carrier according to the right-side auxiliary carrier power and the right-side auxiliary carrier frequency; and add the left-side auxiliary carrier and the right-side auxiliary carrier to the left-side signal and the right-side signal respectively, thereby obtaining the first electrical signal and the second electrical signal of the transmitter.

[0230] In some embodiments of the present invention, the transmitter processor 801 is further configured to add the complex signal expression corresponding to the left-side signal of the transmitter to the complex signal expression corresponding to the auxiliary carrier of the left-side signal to obtain the complex signal expression corresponding to the first electrical signal of the transmitter, thereby obtaining the first electrical signal of the transmitter; and to add the complex signal expression corresponding to the right-side signal of the transmitter to the complex signal expression corresponding to the auxiliary carrier of the right-side signal to obtain the complex signal expression corresponding to the second electrical signal of the transmitter, thereby obtaining the second electrical signal of the transmitter.

[0231] In some embodiments of the present invention, the electro-optic modulator 803 is further configured to sum the first electrical signal and the second electrical signal at the transmitting end to obtain a superimposed electrical signal to be modulated; to obtain the real and imaginary components of the superimposed electrical signal to be modulated, which are respectively used as I-path driving signals and Q-path driving signals; the I-path driving signals and Q-path driving signals are orthogonal to each other; and to perform electro-optic modulation based on the center optical carrier, the I-path driving signals and the Q-path driving signals under carrier suppression modulation state to obtain a transmission optical signal.

[0232] Figure 16 This is a schematic diagram of an optional structure of the receiving end provided in an embodiment of the present invention. For example... Figure 16 As shown, this embodiment of the invention also provides a receiver 900, including: an optical signal receiver 901, an optical coupler 902, an optical bandpass filter 903, a photodetector 904, a receiver processor 905, and a receiver memory 906, wherein: Optical signal receiver 901, used to receive transmitted optical signals; Optical coupler 902 is used to split the transmitted optical signal into a first optical signal at the receiving end and a second optical signal at the receiving end; the first optical signal at the receiving end and the second optical signal at the receiving end contain the same content as the transmitted optical signal; The optical bandpass filter 903 is used to filter out the left band signal and the right band signal of the first optical signal and the second optical signal at the receiving end, respectively, to obtain the right band optical signal and the left band optical signal at the receiving end. The right band optical signal at the receiving end includes the right band auxiliary carrier, and the left band optical signal at the receiving end includes the left band auxiliary carrier. The photodetector 904 is used to perform photoelectric conversion on the light signal on the left side of the receiver and the light signal on the right side of the receiver respectively, so as to obtain the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver. The receiver processor 905 is configured to execute executable instructions stored in the receiver memory 906 to perform receiver digital signal processing on the receiver left-side and receiver right-side charged signals respectively, thereby obtaining a receiver first digital signal and a receiver second digital signal; the receiver first digital signal and the receiver second digital signal contain the information to be transmitted; The receiver memory 906 is configured to store instructions and applications executable by the receiver processor 905.

[0233] It should be noted that the optical coupler 902 can be an optical coupler 021; the optical bandpass filter 903 can be an optical bandpass filter 022; the photodetector 904 can be a photodetector 023; and the receiver processor 905 and the receiver memory 906 can be applied to the receiver DSP device 025.

[0234] In some embodiments of the present invention, the receiving end 900 further includes: The receiver-side electrical signal amplifier 907 is used to amplify the electrical signals on the left and right sides of the receiver, respectively, and to amplify the power of the electrical signals on the left and right sides of the receiver.

[0235] It should be noted that the receiving end electrical signal amplifier 907 can be the receiving end electrical amplifier 024.

[0236] In some embodiments of the present invention, the receiver processor 905 is further configured to resample the charged signal on the left side of the receiver and the charged signal on the right side of the receiver, respectively, to obtain a first sampled signal and a second sampled signal at the receiver; to perform down-conversion to the left and down-conversion to the right on the first sampled signal and the second sampled signal at the receiver, respectively, to obtain a down-converted baseband signal on the left and a down-converted baseband signal on the right; to perform root-raised cosine low-pass filtering on the down-converted baseband signal on the left and the down-converted baseband signal on the right, respectively, to obtain a first baseband signal and a second baseband signal at the receiver; to perform channel equalization on the first baseband signal and the second baseband signal at the receiver, respectively, to obtain a first channel equalized signal and a second channel equalized signal; and to perform QAM demapping on the first channel equalized signal and the second equalized signal at the receiver, respectively, to obtain a first digital signal and a second digital signal at the receiver.

[0237] In some embodiments of the present invention, the receiver processor 905 is further configured to perform cascaded multimode algorithm equalization on the receiver first baseband signal and the receiver second baseband signal respectively, to obtain the first channel equalization signal and the second channel equalization signal.

[0238] In some embodiments of the present invention, the receiving end 900 further includes: The information interaction device 908 is used to acquire the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal.

[0239] In some embodiments of the present invention, the optical bandpass filter 903 is further configured to set the passband bandwidth and passband center frequency based on the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal; and to perform left-side band signal filtering and right-side band signal filtering on the first optical signal and the second optical signal at the receiving end, respectively, based on the passband bandwidth and passband center frequency, to obtain the right-side band optical signal and the left-side band optical signal at the receiving end.

[0240] In some embodiments of the present invention, the sideband signal frequency includes: the left sideband signal frequency and the right sideband signal frequency; the auxiliary carrier frequency includes: the left sideband auxiliary carrier frequency and the right sideband auxiliary carrier frequency. The receiver processor 905 is further configured to subtract the left-side band signal frequency from the left-side band auxiliary carrier frequency to obtain the left-side lower-conversion frequency; and to subtract the right-side band signal frequency from the right-side band auxiliary carrier frequency to obtain the right-side lower-conversion frequency; to mix the left-side lower-conversion complex sine wave signal with the receiver's first sampling signal to obtain the left-side lower-conversion baseband signal; wherein the left-side lower-conversion complex sine wave signal is the complex sine wave signal corresponding to the left-side lower-conversion frequency; and to mix the right-side lower-conversion complex sine wave signal with the receiver's second sampling signal to obtain the right-side lower-conversion baseband signal; wherein the right-side lower-conversion complex sine wave signal is the complex sine wave signal corresponding to the right-side lower-conversion frequency.

[0241] In some embodiments of the present invention, the receiver processor 905 is further configured to perform receiver root raised cosine low-pass filtering on the lower left and lower right frequency conversion baseband signals based on the roll-off coefficient, respectively, to obtain the receiver first baseband signal and the receiver second baseband signal.

[0242] In some embodiments of the present invention, the information interaction device 908 is further configured to acquire the QAM mapping modulation format corresponding to the transmitted optical signal; The receiver processor 905 is also used to perform QAM demapping on the first channel equalization signal and the second channel equalization signal based on the QAM mapping modulation format, so as to obtain the receiver first digital signal and the receiver second digital signal.

[0243] It should be noted that, in the embodiments of the present invention, if the above-described signal processing method is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiments of the present invention, or the part that contributes to related technologies, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause the transmitting processor 801 or the receiving processor 905 to execute all or part of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a magnetic disk, or an optical disk. Thus, the embodiments of the present invention are not limited to any specific hardware and software combination.

[0244] Correspondingly, embodiments of the present invention provide a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps in the methods corresponding to the transmitting end or receiving end described above.

[0245] It should be noted that the descriptions of the storage medium and device embodiments above are similar to those of the method embodiments above, and have similar beneficial effects. For technical details not disclosed in the storage medium and device embodiments of the present invention, please refer to the descriptions of the method embodiments of the present invention for understanding.

[0246] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0247] In the several embodiments provided by this invention, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0248] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units. They may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs.

[0249] In addition, in the various embodiments of the present invention, each functional unit can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0250] The above description is merely an embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A signal processing method, characterized in that, include: Acquire a first digital signal and a second digital signal from the transmitting end; the first digital signal and the second digital signal from the transmitting end contain information to be transmitted; The first digital signal and the second digital signal are respectively processed by the transmitting end digital signal processing to obtain the transmitting end first electrical signal and the transmitting end second electrical signal; the transmitting end first electrical signal and the transmitting end second electrical signal are asymmetric twin single-sideband electrical signals with auxiliary carriers; wherein, the power of the auxiliary carrier is determined based on the power of the corresponding single-sideband electrical signal; the frequency of the auxiliary carrier is determined based on the preset receiving end photodetector bandwidth and the preset receiving end optical filter edge slope; Electro-optic modulation is performed based on the first electrical signal and the second electrical signal of the transmitting end to obtain the transmitted optical signal; The transmitted optical signal is transmitted to the receiving end.

2. The signal processing method according to claim 1, characterized in that, After performing transmit-end digital signal processing on the first digital signal and the second digital signal respectively to obtain the corresponding transmit-end first electrical signal and transmit-end second electrical signal, before performing electro-optic modulation based on the transmit-end first electrical signal and transmit-end second electrical signal to obtain the transmitted optical signal, the method further includes: The first electrical signal and the second electrical signal from the transmitting end are amplified respectively to increase their power.

3. The signal processing method according to claim 1 or 2, characterized in that, The process of obtaining the transmitted optical signal by electro-optic modulation based on the first electrical signal and the second electrical signal of the transmitting end includes: Obtain the center optical carrier; The transmitted optical signal is obtained by electro-optic modulation based on the central optical carrier, the first electrical signal of the transmitting end, and the second electrical signal of the transmitting end.

4. The signal processing method according to claim 1, characterized in that, After obtaining the transmitted optical signal by electro-optic modulation based on the first electrical signal and the second electrical signal of the transmitting end, and before transmitting the transmitted optical signal to the receiving end, the method further includes: The transmitted optical signal is amplified to increase its power.

5. The signal processing method according to claim 1, characterized in that, The first digital signal and the second digital signal from the transmitting end are processed by transmitting end digital signal processing to obtain the first electrical signal and the second electrical signal from the transmitting end, respectively, including: Based on the first digital signal and the second digital signal of the transmitting end, the left-side band signal and the right-side band signal of the transmitting end are obtained respectively. Auxiliary carriers are added to the left-side band signal and the right-side band signal of the transmitting end respectively to obtain the first electrical signal and the second electrical signal of the transmitting end.

6. The signal processing method according to claim 5, characterized in that, The step of obtaining the left-side band signal and the right-side band signal of the transmitter based on the first digital signal and the second digital signal of the transmitter, respectively, includes: The first digital signal and the second digital signal of the transmitting end are respectively subjected to quadrature amplitude modulation (QAM) mapping to obtain the first mapped signal and the second mapped signal of the transmitting end. The first mapped signal and the second mapped signal of the transmitting end are upsampled respectively to obtain the first sampled signal and the second sampled signal of the transmitting end. The first sampled signal and the second sampled signal of the transmitting end are respectively subjected to root raised cosine low-pass filtering to obtain the first baseband signal and the second baseband signal of the transmitting end. The first baseband signal and the second baseband signal of the transmitting end are converted to the upper left and the upper right respectively to obtain the upper left frequency-converted baseband signal and the upper right frequency-converted baseband signal. The upper left and upper right frequency-converted baseband signals are subjected to Hilbert transforms respectively to obtain the left-side band signal and the right-side band signal of the transmitting end.

7. The signal processing method according to claim 6, characterized in that, Before performing left-upward and right-upward frequency conversion on the first baseband signal and the second baseband signal of the transmitting end, respectively, to obtain the left-upward frequency-converted baseband signal and the right-upward frequency-converted baseband signal, the method further includes: Based on the bandwidth of the transmitting device, the upper left and upper right conversion frequencies are determined.

8. The signal processing method according to claim 7, characterized in that, The step of converting the first baseband signal and the second baseband signal of the transmitting end to the upper left and upper right respectively, to obtain the upper left-converted baseband signal and the upper right-converted baseband signal, includes: The upper-left-converted complex sine wave signal is mixed with the first baseband signal of the transmitting end to obtain the upper-left-converted baseband signal; wherein, the upper-left-converted complex sine wave signal is the complex sine wave signal corresponding to the upper-left-converted frequency; and... The upper right-converted complex sine wave signal is mixed with the second baseband signal of the transmitting end to obtain the upper right-converted baseband signal; wherein, the upper right-converted complex sine wave signal is the complex sine wave signal corresponding to the upper right-converted frequency.

9. The signal processing method according to claim 5, characterized in that, Before adding auxiliary carriers to the left-side band signal and the right-side band signal of the transmitting end respectively to obtain the first electrical signal and the second electrical signal of the transmitting end, the method further includes: Based on the power of the signal on the left side of the transmitter and the power of the signal on the right side of the transmitter, the auxiliary carrier power of the left side and the auxiliary carrier power of the right side are determined respectively. Based on the bandwidth of the photodetector at the receiving end and the edge slope of the optical filter at the receiving end, the auxiliary carrier frequencies of the left band and the right band are determined respectively. The left-side auxiliary carrier is determined based on the left-side auxiliary carrier power and the left-side auxiliary carrier frequency; and the right-side auxiliary carrier is determined based on the right-side auxiliary carrier power and the right-side auxiliary carrier frequency.

10. The signal processing method according to claim 9, characterized in that, The step of adding auxiliary carriers to the left-side band signal and the right-side band signal of the transmitting end respectively to obtain the first electrical signal and the second electrical signal of the transmitting end includes: The left-side auxiliary carrier and the right-side auxiliary carrier are respectively added to the left-side signal and the right-side signal of the transmitting end, thereby obtaining the first electrical signal and the second electrical signal of the transmitting end.

11. The signal processing method according to claim 10, characterized in that, The step of adding the left-side auxiliary carrier and the right-side auxiliary carrier to the left-side signal and the right-side signal of the transmitting end, respectively, to obtain the first electrical signal and the second electrical signal of the transmitting end, includes: Adding the complex signal expression corresponding to the left-side band signal of the transmitting end to the complex signal expression corresponding to the left-side band auxiliary carrier yields the complex signal expression corresponding to the first electrical signal of the transmitting end, thereby obtaining the first electrical signal of the transmitting end; and The complex signal expression corresponding to the right-side carrier signal of the transmitting end is added to the complex signal expression corresponding to the right-side auxiliary carrier to obtain the complex signal expression corresponding to the second electrical signal of the transmitting end, thereby obtaining the second electrical signal of the transmitting end.

12. The signal processing method according to claim 3, characterized in that, The process of obtaining the transmitted optical signal by electro-optic modulation based on the central optical carrier, the first electrical signal from the transmitting end, and the second electrical signal from the transmitting end includes: The first electrical signal and the second electrical signal from the transmitting end are summed to obtain the superimposed electrical signal to be modulated. The real and imaginary components of the superimposed electrical signal to be modulated are obtained and used as the I-path driving signal and the Q-path driving signal, respectively; the I-path driving signal and the Q-path driving signal are orthogonal to each other; Under carrier suppression modulation, the transmitted optical signal is obtained by electro-optic modulation based on the center optical carrier, the I-path driving signal, and the Q-path driving signal.

13. A signal processing method, characterized in that, include: Receive and transmit optical signals; The transmitted optical signal is divided into a first optical signal at the receiving end and a second optical signal at the receiving end; the first optical signal at the receiving end and the second optical signal at the receiving end contain the same content as the transmitted optical signal; The first optical signal and the second optical signal at the receiving end are respectively subjected to left-side band signal filtering and right-side band signal filtering to obtain a right-side band optical signal and a left-side band optical signal at the receiving end; the right-side band optical signal at the receiving end includes a right-side band auxiliary carrier, and the left-side band optical signal at the receiving end includes a left-side band auxiliary carrier; wherein, the frequency of the right-side band auxiliary carrier and the frequency of the left-side band auxiliary carrier are determined based on a preset receiving end photodetector bandwidth and a preset receiving end optical filter edge slope; The optical signal on the left side of the receiver and the optical signal on the right side of the receiver are converted into photoelectric signals to obtain the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver. The power of the right side with auxiliary carrier and the power of the left side with auxiliary carrier are determined based on the power of the corresponding single-sided electrical signal. The charged signal on the left side of the receiving end and the charged signal on the right side of the receiving end are processed by receiving end digital signal processing to obtain the first digital signal and the second digital signal of the receiving end; the first digital signal and the second digital signal of the receiving end contain the information to be transmitted.

14. The signal processing method according to claim 13, characterized in that, After performing photoelectric conversion on the optical signal on the left side of the receiver and the optical signal on the right side of the receiver to obtain the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver, respectively, and before performing digital signal processing on the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver to obtain the first digital signal and the second digital signal of the receiver, the method further includes: The charged signals on the left and right sides of the receiving end are amplified respectively, thereby increasing the power of the charged signals on the left and right sides of the receiving end.

15. The signal processing method according to claim 13 or 14, characterized in that, The step of performing receiver-side digital signal processing on the charged signal on the left side of the receiver and the charged signal on the right side of the receiver to obtain a first receiver-side digital signal and a second receiver-side digital signal includes: The charged signal on the left side of the receiver and the charged signal on the right side of the receiver are resampled respectively to obtain the first sampled signal and the second sampled signal of the receiver. The first sampled signal and the second sampled signal at the receiving end are respectively down-converted to the left and down-converted to the right to obtain the down-converted baseband signal and the down-converted baseband signal respectively. The lower left and lower right frequency conversion baseband signals are respectively subjected to root raised cosine low-pass filtering at the receiving end to obtain the first baseband signal and the second baseband signal at the receiving end. Channel equalization is performed on the first baseband signal and the second baseband signal of the receiving end respectively to obtain the first channel equalization signal and the second channel equalization signal. The first channel equalization signal and the second channel equalization signal are respectively subjected to quadrature amplitude modulation (QAM) demapping to obtain the first digital signal and the second digital signal of the receiving end.

16. The signal processing method according to claim 15, characterized in that, The step of performing channel equalization on the first baseband signal and the second baseband signal at the receiving end respectively to obtain a first channel equalization signal and a second channel equalization signal includes: The first baseband signal and the second baseband signal at the receiving end are respectively subjected to cascaded multimode algorithm equalization to obtain the first channel equalization signal and the second channel equalization signal.

17. The signal processing method according to claim 15, characterized in that, Before receiving the transmitted optical signal, the method further includes: Obtain the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal.

18. The signal processing method according to claim 17, characterized in that, Before performing left-side band signal filtering and right-side band signal filtering on the first optical signal and the second optical signal at the receiving end, respectively, to obtain the right-side band optical signal and the left-side band optical signal at the receiving end, the method further includes: Based on the sideband signal frequency and auxiliary carrier frequency corresponding to the transmitted optical signal, the passband bandwidth and passband center frequency are set.

19. The signal processing method according to claim 18, characterized in that, The step of filtering out the left-side band signal and the right-side band signal of the first optical signal and the second optical signal of the receiving end, respectively, to obtain the right-side band optical signal and the left-side band optical signal of the receiving end, includes: Based on the passband bandwidth and the passband center frequency, the first optical signal and the second optical signal at the receiving end are respectively subjected to left-side band signal filtering and right-side band signal filtering to obtain the right-side band optical signal and the left-side band optical signal at the receiving end.

20. The signal processing method according to claim 17, characterized in that, The sideband signal frequencies include: left sideband signal frequencies and right sideband signal frequencies; the auxiliary carrier frequencies include: left sideband auxiliary carrier frequencies and right sideband auxiliary carrier frequencies. Before performing left-downconversion and right-downconversion on the first sampled signal and the second sampled signal at the receiving end, respectively, to obtain the left-downconverted baseband signal and the right-downconverted baseband signal, the method further includes: Subtracting the left-side band signal frequency from the left-side band auxiliary carrier frequency yields the lower-left conversion frequency; and, Subtracting the right-side band signal frequency from the right-side band auxiliary carrier frequency yields the right-side lower-conversion frequency.

21. The signal processing method according to claim 20, characterized in that, The step of performing left-down conversion and right-down conversion on the first sampled signal and the second sampled signal at the receiving end, respectively, to obtain the left-down-converted baseband signal and the right-down-converted baseband signal, includes: The left-lower frequency-converted complex sine wave signal is mixed with the first sampled signal at the receiving end to obtain the left-lower frequency-converted baseband signal; wherein, the left-lower frequency-converted complex sine wave signal is the complex sine wave signal corresponding to the left-lower frequency conversion frequency; and... The right-lower frequency conversion complex sine wave signal is mixed with the second sampling signal of the receiving end to obtain the right-lower frequency conversion baseband signal; wherein, the right-lower frequency conversion complex sine wave signal is the complex sine wave signal corresponding to the right-lower frequency conversion frequency.

22. The signal processing method according to claim 15, characterized in that, The step of performing root-raised cosine low-pass filtering on the lower left and lower right frequency-converted baseband signals at the receiving end to obtain the first baseband signal and the second baseband signal at the receiving end includes: Based on the roll-off factor, the lower left and lower right frequency conversion baseband signals are respectively subjected to root-raised cosine low-pass filtering at the receiving end to obtain the first baseband signal and the second baseband signal at the receiving end.

23. The signal processing method according to claim 15, characterized in that, Before receiving the transmitted optical signal, the method further includes: Obtain the QAM mapping modulation format corresponding to the transmitted optical signal; The step of performing QAM demapping on the first channel equalization signal and the second channel equalization signal respectively to obtain the first digital signal and the second digital signal at the receiving end includes: Based on the QAM mapping modulation format, QAM demapping is performed on the first channel equalization signal and the second channel equalization signal respectively to obtain the first digital signal and the second digital signal of the receiving end.

24. A transmitting terminal, characterized in that, include: Transmitter memory and transmitter processor; The transmitter memory is used to store executable instructions; The transmitter processor is configured to execute executable instructions stored in the transmitter memory to acquire a first digital signal and a second digital signal from the transmitter; the first digital signal and the second digital signal from the transmitter contain information to be transmitted; the first digital signal and the second digital signal are respectively processed by the transmitter to obtain a first electrical signal and a second electrical signal from the transmitter; the first electrical signal and the second electrical signal from the transmitter are asymmetric twin single-sideband signals with an auxiliary carrier; wherein, the power of the auxiliary carrier is determined based on the power of the corresponding single-sideband signal; the frequency of the auxiliary carrier is determined based on a preset receiver photodetector bandwidth and a preset receiver optical filter edge slope; An electro-optic modulator is used to perform electro-optic modulation based on the first electrical signal and the second electrical signal of the transmitting end to obtain a transmitted optical signal; An optical signal transmitter is used to transmit the transmitted optical signal to the receiving end.

25. The transmitting end according to claim 24, characterized in that, The transmitter also includes: A transmitting-end electrical signal amplifier is used to amplify the transmitting-end first electrical signal and the transmitting-end second electrical signal respectively, thereby amplifying the power of the transmitting-end first electrical signal and the transmitting-end second electrical signal.

26. The transmitting end according to claim 24, characterized in that, The electro-optic modulator is also used to acquire a central optical carrier; and to perform electro-optic modulation based on the central optical carrier, the first electrical signal of the transmitting end, and the second electrical signal of the transmitting end to obtain the transmitted optical signal.

27. The transmitting end according to any one of claims 24 to 26, characterized in that, The transmitter also includes: The transmitting optical signal amplifier is used to amplify the transmitted optical signal and increase its power.

28. A receiving end, characterized in that, include: An optical signal receiver is used to receive transmitted optical signals. An optical coupler is used to split the transmitted optical signal into a first optical signal at the receiving end and a second optical signal at the receiving end. The first optical signal and the second optical signal at the receiving end contain the same content as the transmitted optical signal; An optical bandpass filter is used to filter out left-side band signals and right-side band signals from the first optical signal and the second optical signal at the receiving end, respectively, to obtain a right-side band optical signal and a left-side band optical signal at the receiving end. The right-side band optical signal at the receiving end includes a right-side auxiliary carrier, and the left-side band optical signal at the receiving end includes a left-side auxiliary carrier. The frequencies of the right-side auxiliary carrier and the left-side auxiliary carrier are determined based on a preset bandwidth of the photodetector at the receiving end and a preset edge slope of the optical filter at the receiving end. A photodetector is used to perform photoelectric conversion on the optical signal on the left side of the receiver and the optical signal on the right side of the receiver, respectively, to obtain the electrical signal on the left side of the receiver and the electrical signal on the right side of the receiver; wherein, the power of the auxiliary carrier on the right side and the power of the auxiliary carrier on the left side are determined based on the power of the corresponding single-sided electrical signal. Receiver memory and receiver processor; The receiver memory is used to store executable instructions; The receiving end processor is used to execute executable instructions stored in the receiving end memory, and to perform receiving end digital signal processing on the receiving end left-side charged signal and the receiving end right-side charged signal respectively, to obtain the receiving end first digital signal and the receiving end second digital signal; the receiving end first digital signal and the receiving end second digital signal contain information to be transmitted.

29. The receiving end according to claim 28, characterized in that, The receiving end also includes: The receiving end electrical signal amplifier is used to amplify the electrical signal on the left side of the receiving end and the electrical signal on the right side of the receiving end, respectively, and amplify the power of the electrical signal on the left side of the receiving end and the electrical signal on the right side of the receiving end.

30. A storage medium, characterized in that, It stores executable instructions for causing the transmitter processor or receiver processor to execute, thereby implementing the method according to any one of claims 1 to 12 or any one of claims 13 to 23.

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