Downlink data transmission method, device and system for laser fiber power supply application

Abstract

The invention provides a downlink data transmission method, device and system for laser fiber power supply application, and the method comprises the steps: carrying out the differential coding of downlink data to be transmitted through a transmitting end, and obtaining a data bit sequence; mapping the data bit sequence into a modulation symbol sequence by adopting a single-carrier phase modulation mode; performing digital-to-analog conversion on the modulation symbol sequence to obtain an analog signal; and outputting downlink energy and downlink data through an energy optical fiber according to the analog signal. According to the invention, the signal frequency spectrum is moved to be far away from the direct current frequency through differential coding and single carrier phase modulation, so that the interference of direct current laser energy on signal detection is minimized, the signal-to-noise ratio is improved, the inter-symbol interference is reduced, and a receiving end is ensured to have enough signal-to-noise ratio to reliably detect data.

Description

Technical Field

[0001] The present invention relates to the technical field of laser fiber power supply for power equipment status monitoring, and particularly to a downlink data transmission method, device and system for laser fiber power supply applications. Background Art

[0002] PoF (Power Over Fiber) is the preferred solution for powering sensing nodes installed outdoors and on the high-voltage side. The reasons for choosing laser fiber power supply instead of traditional power supplies include requirements for electrical isolation, lightning / spark protection, electromagnetic interference immunity, weight reduction, corrosion resistance, etc. In addition to powering the sensing nodes, a data link also needs to be provided between the sensing nodes and the control center located on the low-voltage side. Downlink data (from the control center to the sensing nodes) is used to configure and control remote sensing nodes. Uplink data is used to upload sensing data.

[0003] The complexity and power consumption of the downlink largely depend on the modulation scheme adopted. The most commonly used downlink data modulation scheme is PAM (Puls Amplitude Modulation). PAM signals are usually used as line codes for short-distance wired data communication, which are easy to modulate and demodulate. Although its PSD (Power Spectral Density) has no DC component, the strong DC laser energy present at the receiver after photovoltaic conversion will seriously affect the reception of the baseband PAM signal.

[0004] Therefore, it is necessary to reduce the laser DC component to a sufficiently low level through a high-pass filter to ensure that there is sufficient signal-to-noise ratio for reliable data detection. However, a realizable and economical high-pass filter has a cut-off frequency that cannot be too small and a slope that cannot be too steep. Therefore, it will inevitably filter out the low-frequency components of the baseband signal at the same time, resulting in signal-to-noise ratio deterioration and inter-symbol interference, affecting the reliability of receiving and detecting data at the receiving end. Summary of the Invention

[0005] In order to overcome the defects in the above-mentioned traditional data transmission method, such as signal-to-noise ratio deterioration and inter-symbol interference, which affect the reliability of receiving and detecting data at the receiving end, in a first aspect, the present invention provides a downlink data transmission method for laser fiber power supply applications, including:

[0006] Performing differential coding on the downlink data to be transmitted to obtain a data bit sequence;

[0007] Adopting a single-carrier phase modulation method to map the data bit sequence into a modulation symbol sequence;

[0008] Performing digital-to-analog conversion on the modulation symbol sequence to obtain an analog signal;

[0009] Output the downstream energy and the downstream data through the energy optical fiber according to the analog signal.

[0010] Optionally, the method of using single - carrier phase modulation to map the data bit sequence into a modulation symbol sequence includes:

[0011] Using single - carrier phase modulation, map the data bit sequence into a modulation symbol sequence at a set symbol rate.

[0012] Optionally, the method of performing digital - to - analog conversion on the modulation symbol sequence to obtain an analog signal includes:

[0013] Oversample the modulation symbol sequence to obtain an oversampled signal;

[0014] Perform up - conversion processing and digital - to - analog conversion on the oversampled signal to obtain an analog signal.

[0015] Optionally, the method of oversampling the modulation symbol sequence to obtain an oversampled signal includes:

[0016] According to the oversampling factor, oversample the modulation symbol sequence at a set oversampling frequency to obtain an oversampled signal;

[0017] Wherein, the oversampling factor is the ratio of the set oversampling frequency to the set symbol rate, and the set oversampling frequency is higher than the Nyquist rate.

[0018] Optionally, after using single - carrier phase modulation to map the data bit sequence into a modulation symbol sequence, it further includes:

[0019] According to the initial phase of the modulation symbol sequence, determine the square - wave sequence corresponding to the initial phase by looking up a table;

[0020] Within each full cycle of the sine wave of the modulation symbol sequence, use the square waves with alternating polarities in the square - wave sequence to replace the sine wave of the modulation symbol sequence, and keep the initial phase of the modulation symbol sequence unchanged.

[0021] Optionally, the ratio of the carrier frequency of the modulation symbol sequence after square - wave substitution to the set symbol rate is an integer multiple of a set coefficient, and the number of square waves with alternating polarities in the square - wave sequence is related to the ratio.

[0022] Optionally, the method of performing up - conversion processing and digital - to - analog conversion on the oversampled signal to obtain an analog signal includes:

[0023] Up - convert the oversampled signal to the carrier frequency to obtain a digital phase - modulation signal;

[0024] Perform digital-to-analog conversion on the digital phase modulation signal at the digital-to-analog conversion frequency to obtain an analog signal;

[0025] The digital-to-analog conversion frequency is 4n times the carrier frequency, where n is a positive integer, and the digital-to-analog conversion frequency is an integer multiple of the set oversampling frequency.

[0026] In a second aspect, the present invention also provides a communication device, including:

[0027] An encoding and modulation module for performing differential encoding on the downlink data to be transmitted to obtain a data bit sequence; using a single-carrier phase modulation method to map the data bit sequence into a modulation symbol sequence;

[0028] A digital-to-analog conversion module for performing digital-to-analog conversion on the modulation symbol sequence to obtain an analog signal;

[0029] A driving laser for outputting downlink energy and the downlink data through an energy optical fiber according to the analog signal.

[0030] Optionally, the encoding and modulation module is specifically configured to map the data bit sequence into a modulation symbol sequence at a set symbol rate using a single-carrier phase modulation method.

[0031] Optionally, the digital-to-analog conversion module includes an oversampling unit and a mixing digital-to-analog conversion unit;

[0032] The oversampling unit is used to oversample the modulation symbol sequence to obtain an oversampled signal;

[0033] The mixing digital-to-analog conversion unit is used to perform up-conversion processing and digital-to-analog conversion on the oversampled signal to obtain an analog signal.

[0034] Optionally, the oversampling unit is specifically configured to oversample the modulation symbol sequence at a set oversampling frequency according to an oversampling factor to obtain an oversampled signal; where the oversampling factor is the ratio of the set oversampling frequency to the set symbol rate, and the set oversampling frequency is higher than the Nyquist rate.

[0035] Optionally, it further includes:

[0036] A look-up table module for determining a square wave sequence corresponding to the initial phase by looking up a table according to the initial phase of the modulation symbol sequence; within each full cycle of the sine wave of the modulation symbol sequence, using the square waves with alternating polarities in the square wave sequence to replace the sine wave of the modulation symbol sequence while keeping the initial phase of the modulation symbol sequence unchanged.

[0037] Optionally, the ratio of the carrier frequency of the modulation symbol sequence after square wave substitution to the set symbol rate is an integer multiple of a set coefficient, and the number of square waves with alternating polarities in the square wave sequence is related to the ratio.

[0038] Optionally, the hybrid frequency digital-to-analog conversion unit is specifically configured to up-convert the oversampled signal to a carrier frequency to obtain a digital phase modulation signal; perform digital-to-analog conversion on the digital phase modulation signal at a digital-to-analog conversion frequency to obtain an analog signal; the digital-to-analog conversion frequency is 4n times the carrier frequency, where n is a positive integer, and the digital-to-analog conversion frequency is an integer multiple of the set oversampling frequency.

[0039] In a third aspect, the present invention further provides a downlink data transmission method for laser fiber power supply applications, which is characterized by including:

[0040] Perform high-pass filtering and analog-to-digital conversion on the received analog signal to obtain digital samples; the analog signal is obtained by the transmitting end performing differential encoding on the downlink data to be transmitted to obtain a data bit sequence, using a single-carrier phase modulation method to map the data bit sequence to a modulation symbol sequence, and then performing digital-to-analog conversion on the modulation symbol sequence.

[0041] Perform down-conversion processing and low-pass filtering on the digital samples to obtain a complex baseband signal.

[0042] Extract signal samples from the complex baseband signal.

[0043] Perform symbol decision and differential decoding on the signal samples to obtain downlink data.

[0044] Optionally, the performing down-conversion processing and low-pass filtering on the digital samples to obtain a complex baseband signal includes:

[0045] Perform down-conversion processing on the digital samples to obtain complex baseband samples.

[0046] Perform low-pass filtering on the complex baseband samples to obtain a complex baseband signal with in-phase I and quadrature Q components.

[0047] Optionally, the complex baseband samples satisfy the following formula:

[0048] y(l) = r(l) * e jln*π / 2

[0049] where y(l) is the complex baseband sample, r(l) is the digital sample, l is the sample index, and j is the imaginary unit.

[0050] Optionally, the extracting signal samples from the complex baseband signal includes:

[0051] Extract signal samples from the complex baseband signal at equal intervals; the value of the equal interval is the ratio of the analog-to-digital conversion frequency to the set oversampling frequency.

[0052] Optionally, the signal samples satisfy the following formula:

[0053] x(k,α) = x(kT + α / N1 T)

[0054] Wherein, the x and the x(k,α) are signal samples, k is a symbol interval index, T is a symbol interval, α is an oversampling sample index within the symbol interval, α = 0, 1, …, N1 - 1, and N1 is an oversampling factor.

[0055] Optionally, the performing symbol decision and differential decoding on the signal samples to obtain downlink data includes:

[0056] Performing a fourth-power operation on the signal samples to obtain a result of the power operation;

[0057] Grouping the result of the power operation according to the oversampling sample index of the signal samples within the symbol interval to obtain N1 groups;

[0058] Calculating the variance of each group according to different oversampling sample indices and determining the group with the minimum variance;

[0059] Determining a symbol timing estimation value according to the oversampling sample index corresponding to the group with the minimum variance;

[0060] Performing symbol decision and differential decoding on the signal samples according to the symbol timing estimation value to obtain downlink data.

[0061] Optionally, the number N1 of the groups is greater than or equal to 7.

[0062] In a fourth aspect, the present invention further provides a communication device, including:

[0063] A filtering and conversion module, configured to perform high-pass filtering processing and analog-to-digital conversion on a received analog signal to obtain digital samples; the analog signal is obtained by the transmitting end performing differential encoding on downlink data to be transmitted to obtain a data bit sequence, using a single-carrier phase modulation method to map the data bit sequence into a modulation symbol sequence, and then performing digital-to-analog conversion on the modulation symbol sequence;

[0064] A down-conversion processing module, configured to perform down-conversion processing and low-pass filtering on the digital samples to obtain a complex baseband signal;

[0065] A decimation module, configured to decimate signal samples from the complex baseband signal;

[0066] A decision and decoding module, configured to perform symbol decision and differential decoding on the signal samples to obtain downlink data.

[0067] Optionally, the down-conversion processing module includes a down-conversion unit and a low-pass filtering unit;

[0068] A down-conversion unit, configured to perform down-conversion processing on digital samples to obtain complex baseband samples;

[0069] A low-pass filtering unit, configured to perform low-pass filtering on the complex baseband samples to obtain a complex baseband signal having in-phase I and quadrature Q components.

[0070] Optionally, the complex baseband samples satisfy the following formula:

[0071] y(l) = r(l) * e jln*π / 2

[0072] where y(l) are the complex baseband samples, r(l) are the digital samples, l is the sample index, and j is the imaginary unit.

[0073] Optionally, a decimation module, specifically configured to extract signal samples at equal intervals in the complex baseband signal; the value of the equal interval is the ratio of the analog-to-digital conversion frequency to the set oversampling frequency.

[0074] Optionally, the signal samples satisfy the following formula:

[0075] x(k,α) = x(kT + α / N1 T)

[0076] where x and x(k,α) are the signal samples, k is the symbol interval index, T is the symbol interval, α is the oversampling sample index within the symbol interval, α = 0, 1,..., N1 - 1, and N1 is the oversampling factor.

[0077] Optionally, a decision decoding module, specifically configured to perform a fourth-power operation on the signal samples to obtain a power operation result; group the power operation results according to the oversampling sample index of the signal samples within the symbol interval to obtain multiple groups; calculate the variance of each group according to different oversampling sample indices and determine the group with the minimum variance; determine the symbol timing estimate according to the oversampling sample index corresponding to the group with the minimum variance; perform symbol decision and differential decoding on the signal samples according to the symbol timing estimate to obtain the downlink data.

[0078] Optionally, the number of groups is greater than or equal to 7.

[0079] In a fifth aspect, the present invention further provides a communication system, characterized in that it includes a transmitting end and a receiving end; the transmitting end is configured to implement the downlink data transmission method for laser fiber power supply applications described in the first aspect above, and the receiving end is configured to implement the downlink data transmission method for laser fiber power supply applications described in the third aspect above.

[0080] In a sixth aspect, the present invention further provides an electronic device, characterized in that it includes: at least one processor and a memory; the memory and the processor are connected through a bus;

[0081] The memory is used to store one or more programs;

[0082] When the one or more programs are executed by the at least one processor, the downlink data transmission method for laser fiber power supply application described in the first aspect above is implemented, or the downlink data transmission method for laser fiber power supply application described in the third aspect above is implemented.

[0083] In a seventh aspect, the present invention further provides a readable storage medium, characterized in that an execution program is stored thereon, and when the execution program is executed, the downlink data transmission method for laser fiber power supply application described in the first aspect above is implemented, or the downlink data transmission method for laser fiber power supply application described in the third aspect above is implemented.

[0084] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0085] The present invention provides a downlink data transmission method for laser fiber power supply application. The transmitting end performs differential encoding on the downlink data to be transmitted to obtain a data bit sequence; adopts a single-carrier phase modulation method to map the data bit sequence into a modulation symbol sequence; performs digital-to-analog conversion on the modulation symbol sequence to obtain an analog signal; and outputs downlink energy and downlink data through an energy fiber according to the analog signal. By differential encoding and single-carrier phase modulation, the present invention shifts the signal spectrum away from the DC frequency, which can minimize the interference of DC laser energy on signal detection, improve the signal-to-noise ratio, reduce inter-symbol interference, and ensure that the receiving end has sufficient signal-to-noise ratio to reliably detect data. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 is a block diagram of the joint transmission architecture of energy and downlink data of the laser fiber power supply system of the present invention;

[0087] Figure 2 is a schematic diagram of a bipolar pulse amplitude modulation laser signal of the present invention;

[0088] Figure 3 is a schematic flow diagram of the downlink data transmission method for laser fiber power supply application of the present invention;

[0089] Figure 4 is a schematic diagram of single-carrier QPSK phase modulation of the present invention;

[0090] Figure 5 is a block diagram of the functional units of a full-digital transmitter and receiver of the single-carrier phase modulation method for downlink data transmission of the present invention;

[0091] Figure 6 is a schematic diagram of replacing a sine wave with a square wave in the single-carrier phase modulation method of the present invention;

[0092] Figure 7 Schematic diagram of the transmitting end functional unit of the QPSK carrier phase modulation method using a square wave to replace a sine wave according to the present invention;

[0093] Figure 8 Oversampled sample index schematic diagram of the symbol positioning method according to the present invention;

[0094] Figure 9 Schematic diagram of the structure of the communication system according to the present invention;

[0095] Figure 10 Schematic diagram of the structure of the communication device according to the present invention;

[0096] Figure 11 Schematic diagram of the structure of the communication device according to the present invention;

[0097] Figure 12 Schematic diagram of the structure of the electronic device according to the present invention. Detailed implementation manners

[0098] The present invention is mainly oriented to laser optical fiber power supply (PoF) for power equipment status monitoring. PoF is a solution for powering sensing nodes installed outdoors and on the high-voltage side. Compared with traditional power supplies, laser optical fiber power supply can meet requirements such as electrical isolation, lightning / spark protection, electromagnetic interference immunity, weight reduction, and corrosion resistance. In addition to powering the sensing nodes, a data link is also required between the sensing nodes and the control nodes located on the low-voltage side. The downstream data from the control center to the sensing nodes is used to configure and control the remote sensing nodes, and the upstream data from the sensing nodes to the control center is used to upload sensing data.

[0099] Figure 1 Schematic diagram of the joint transmission architecture of energy and downstream data for a laser optical fiber power supply system. At the energy and data transmitting end on the low-voltage side, the control center sends the downstream data to the microprocessor, and then through the laser driver and high-power laser, first modulates the downstream data into an electrical signal (i.e., current) that controls the laser output, and then converts the electrical signal into a laser signal, which is coupled into the energy optical fiber. At the energy and data receiving end on the high-voltage side, the photovoltaic module converts the incident laser signal into an electrical signal. The large DC component is used for energy storage and management to power the sensing nodes, and the laser DC component is suppressed through high-pass filtering while allowing the high-pass modulated signal to pass through. The microprocessor completes signal demodulation and data monitoring. It can be understood that Figure 1 mainly presents the downstream data communication for laser optical fiber power supply applications and does not show the upstream data communication.

[0100] The complexity and power consumption of the downstream link largely depend on the modulation scheme adopted. The most commonly used downstream link data modulation scheme is PAM. Figure 2An example of 2-level PAM modulation with a rectangular pulse shape is shown. The laser signal level P1 transmits data "1", and the level P0 (P0 < P1) transmits data "0". The reduction in the average transmitted laser power depends on the so-called extinction ratio P0 / P1 and is equal to (1 + P0 / P1) / 2.

[0101] Bipolar PAM signals are commonly used as line codes for short-distance wired data communication. It is easy to modulate and demodulate, and the PSD has a Sinc squared shape centered at the baseband. Although it has no DC component, the strong DC laser energy present at the receiver after photovoltaic conversion will seriously affect the reception of the baseband PAM signal. Therefore, it is necessary to reduce the laser DC component to a sufficiently low level through a high-pass filter to ensure sufficient signal-to-noise ratio for reliable data detection. However, an achievable and economical high-pass filter has a cut-off frequency that cannot be too small and a slope that cannot be too steep. Therefore, it is inevitable to filter out the low-frequency components of the baseband signal at the same time, which on the one hand deteriorates the signal-to-noise ratio and on the other hand causes inter-symbol interference.

[0102] Based on this, the present invention provides a method for downlink data transmission for laser fiber power supply applications. The following further elaborates on the specific implementation manners of the present invention in conjunction with the accompanying drawings.

[0103] Embodiment 1:

[0104] A method for downlink data transmission for laser fiber power supply applications provided by the present invention, the process schematic diagram is as Figure 3 shown, including:

[0105] Step 301: The transmitter performs differential encoding on the downlink data to be transmitted to obtain a data bit sequence.

[0106] Step 302: The transmitter uses a single-carrier phase modulation method to map the data bit sequence into a modulation symbol sequence.

[0107] Step 303: The transmitter performs digital-to-analog conversion on the modulation symbol sequence to obtain an analog signal.

[0108] Step 304: The transmitter outputs downlink energy and downlink data through the energy fiber according to the analog signal. Correspondingly, the receiver obtains downlink energy and downlink data through the energy fiber.

[0109] In the embodiment of the present invention, the signal spectrum is shifted away from the DC frequency through differential encoding and single-carrier phase modulation, which can minimize the interference of DC laser energy on signal detection, improve the signal-to-noise ratio, reduce inter-symbol interference, and ensure sufficient signal-to-noise ratio at the receiver for reliable data detection.

[0110] The transmitting end refers to the end for transmitting energy and data, which can transmit energy and data to the receiving end through an energy optical fiber. The receiving end is the end for receiving energy and data. The transmitting end may include / integrate a control center, or be connected to an external control center, while the receiving end may include / integrate a sensing node, or be connected to an external sensing node.

[0111] The downlink data to be transmitted in the above step 301 may be binary data. The single-carrier phase modulation method in the above step 302 may be a QPSK (Quadrature Phase Shift Keying) modulation method. Figure 4 It shows a schematic diagram of QPSK modulation with Grey coding, and one QPSK symbol lasts for two carrier periods. The original QPSK modulation symbol (or modulation signal) is a sine wave. Figure 4 The initial phase of the sine wave in it is determined by the QPSK modulation symbols (00, 01, 10, 11) according to Grey coding. In the embodiment of the present invention, the differential coding plus QPSK modulation method can achieve the DQPSK (Differential Quadrature Reference Phase Shift Keying) modulation method to ensure the transmission of downlink data. Correspondingly, the modulation symbol sequence obtained in the above step 302 may be a DQPSK symbol sequence.

[0112] In one implementation, in the above step 302, the transmitting end may adopt a single-carrier phase modulation method to map the data bit sequence into a modulation symbol sequence at a set symbol rate. The set symbol rate can be expressed as f sym .

[0113] In one implementation, in the above step 303, the transmitting end may oversample the modulation symbol sequence to obtain an oversampled signal; perform up-conversion processing and digital-to-analog conversion on the oversampled signal to obtain an analog signal. When performing oversampling, the transmitting end may oversample the modulation symbol sequence at a set oversampling frequency according to the oversampling factor to obtain an oversampled signal. Among them, the oversampling factor is the ratio of the set oversampling frequency to the set symbol rate, and the set oversampling frequency is higher than the Nyquist rate. In this implementation, the modulation symbol sequence can be sampled at a frequency much higher than the Nyquist rate, and multiple samples can be collected for each modulation symbol. The set oversampling frequency can be expressed as f os , and the oversampling factor can be expressed as N1 = f os / f sym .

[0114] To simplify the modulation of the signal at the transmitter, a square wave can be used to approximate the sine wave of the QPSK carrier phase modulation for generating the laser control signal. As Figure 5 shown, each sine wave is replaced by a positive square wave in the range of 0 to 180°, and by a negative square wave in the range of 180° to 360°. Therefore, each full-cycle sine wave is replaced by two square waves with different polarities. For example, in the case of single-carrier phase modulation, after mapping the data bit sequence to the modulation symbol sequence, the transmitter can also determine the square wave sequence corresponding to the initial phase by looking up a table according to the initial phase of the modulation symbol sequence; within each full cycle of the sine wave of the modulation symbol sequence, the sine wave of the modulation symbol sequence is replaced by the square waves with alternating polarities in the square wave sequence, while keeping the initial phase of the modulation symbol sequence unchanged.

[0115] Optionally, the ratio of the carrier frequency of the modulation symbol sequence after the square wave replacement to the set symbol rate is an integer multiple of the set coefficient. For example, the ratio N4 of the carrier frequency f c of the modulation symbol sequence after the square wave replacement to the set symbol rate f sym is N4 = f c / f sym . The number of square waves with alternating polarities in the square wave sequence is related to the ratio. For example, when the number of square waves with alternating polarities in the square wave sequence is related to the ratio, when 2N4 is an integer, each QPSK symbol can be represented by a square wave sequence with 2N4 alternating polarities, and its initial phase remains unchanged, which is Figure 3 the same and is determined by the QPSK modulation symbols (00, 01, 10, 11) according to the Grey code. This processing method can retain the phase state information (0, π / 2, π, 3π / 2) of the original QPSK modulation signal, so the receiver can extract information as if using the original signal, which can simplify the processing at the receiver. For example, for downlink data using single-carrier phase modulation, QPSK is preferred, and the carrier frequency should be at least 6 times the symbol rate, so that the modulation signal spectrum is far from the baseband DC frequency, reducing the performance requirements for the high-pass filter used at the receiver to filter out the high-power DC component and reducing the distortion of the received signal.

[0116] Since the downlink data is mainly used to control and configure the operation of the sensing nodes, and the required data rate is between several kHz and dozens of kHz (kilohertz), starting from reducing costs and complexity, a fully digital structure of the transmitter and receiver architecture is preferred, and a low-cost and low-power MCU (Microcontroller Unit) is selected to implement the algorithm. Figure 6The figure shows a schematic diagram of the structure of a fully digital transmitter and receiver for a possible carrier phase modulation method for downlink data transmission. The transmitting end includes a fully digital transmitter (also known as a fully digital emitter) and a driver / laser. The fully digital transmitter can perform differential encoding, QPSK mapping, oversampling, mixing (i.e., upconversion), and DAC (Digital-to-Analog Conversion) processing on binary data to obtain an analog signal, and then control the driver / laser to output energy and data through an energy optical fiber. The receiving end includes a photovoltaic module, a high-pass filter, and a fully digital receiver (also known as a fully digital receiver). The specific implementation process of the receiving end will be described below.

[0117] The above method of replacing the sine wave with a square wave can greatly simplify the generation of the signal modulation at the transmitting end and the laser control signal. Refer to Figure 7 As shown, according to different QPSK phase modulation data, the corresponding square wave sequence is obtained by looking up a table. Through 1-bit digital-to-analog conversion, the current or voltage signal used to control the laser output can be directly generated. And Figure 6 compared, the implementation at the transmitting end is significantly simplified. For example, replacing the sine wave of carrier phase modulation with a square wave requires the carrier frequency f c and the QPSK symbol rate f sym The ratio N4 = f c / f sym is an integer multiple of the coefficient 0.5. The QPSK modulation symbol is replaced with a square wave sequence of 2N4 alternating polarities, and its initial phase remains unchanged, which is determined by the QPSK symbol (00, 01, 10, 11) according to the Grey code. The square wave sequence corresponding to each QPSK symbol is stored in the MCU. During data transmission, the corresponding square wave sequence is obtained by looking up a table according to the QPSK modulation data. Through 1-bit digital-to-analog conversion, the current or voltage signal used to control the laser output is generated.

[0118] In one implementation, during the upconversion processing and digital-to-analog conversion in step 303 above, the transmitting end can upconvert the oversampled signal to the carrier frequency to obtain a digital phase modulation signal; perform digital-to-analog conversion on the digital phase modulation signal at the digital-to-analog conversion frequency to obtain an analog signal; the digital-to-analog conversion frequency is 4n times the carrier frequency, where n is a positive integer, and the digital-to-analog conversion frequency is an integer multiple of the set oversampling frequency.

[0119] It can be seen that in the embodiments of the present invention, the transmitting end shifts the signal spectrum away from the DC frequency through carrier modulation and effectively suppresses the DC power of the laser using a simple and low-cost high-pass filter. Further, a square wave is proposed to replace the sine wave used for carrier phase modulation, which greatly simplifies the generation of the carrier modulation signal and the laser control current signal while maintaining the original phase state and data symbol mapping relationship. As the data rate increases, the effect of this impact is greater, and a complex and high-power digital channel equalizer needs to be used at the receiver, which is often unacceptable. Therefore, in the embodiments of the present invention, the key parameters of single-carrier phase modulation / demodulation (such as sampling frequency, carrier frequency, oversampling factor, and symbol rate) are tightly coupled to simplify the implementation architecture of the pure digital receiver and minimize the power consumption.

[0120] The specific implementation process of the receiving end will be described below. In step 304 above, the receiving end can perform high-pass filtering and analog-to-digital conversion on the received analog signal to obtain digital samples; perform down-conversion processing and low-pass filtering on the digital samples to obtain a complex baseband signal; extract signal samples from the complex baseband signal; perform symbol decision and differential decoding on the signal samples to obtain downlink data. In one example, referring to Figure 6 , after receiving energy and data through the energy optical fiber, the receiving end processes them using a photovoltaic module and a high-pass filter, and then the all-digital receiver sequentially performs ADC (Analog-to-Digital Conversion), digital down-conversion, low-pass filtering, sample extraction, symbol decision and symbol synchronization, and differential decoding to obtain binary data, that is, downlink data.

[0121] The process of performing down-conversion processing and low-pass filtering on the digital samples to obtain a complex baseband signal may include: performing down-conversion processing on the digital samples to obtain complex baseband samples; performing low-pass filtering on the complex baseband samples to obtain a complex baseband signal with I (In-phase) and Q (Quadrature) components.

[0122] The digital samples are the samples after analog-to-digital conversion at the receiving end. Assuming that r(l) represents the digital samples, l is the sample index, and Δt = 1 / f s is the sample interval, then the complex baseband samples obtained after down-conversion processing satisfy the following formula (1):

[0123] y(l) = r(l) *e j2πl*Δt*fc = r(l) *e j2πl*fc / fs (1)

[0124] where y(l) is the complex baseband sample, r(l) is the digital sample, l is the sample index, j is the imaginary unit, and f c is the carrier frequency, and f sis the sampling frequency. According to formula (1), down-conversion requires multiplying the samples by the sine function and the cosine function, which is complex to implement. For example, to simplify (1), it is proposed to make the sampling frequency f s and the carrier frequency f c be tightly coupled so that f s is an integer multiple of 4 of f c , that is, it is required to satisfy the following formula (2):

[0125] f s / f c = N2 = n*4, n=1, 2, 3 (2)

[0126] N2 is the ratio of f s to f c . Substituting formula (2) into formula (1), the final complex baseband samples can be obtained, which satisfy the following formula (3):

[0127] y(l) =r(l)*e jln*π / 2 (3)

[0128] where y(l) are the complex baseband samples, r(l) are the digital samples, l is the sample index, and j is the imaginary unit. Therefore, the complex sample sequence <y(l)> containing the complex baseband samples can be obtained by the periodic "multiplication" of the sequence <r(l)> with (1, j, -1, -j). Therefore, according to the coupling of the sampling frequency and the carrier frequency proposed in formula (2), the algorithm can be significantly simplified, thereby significantly reducing the power consumption at the receiving end. It can be seen that in this implementation, the analog-to-digital conversion sampling frequency f s is an integer multiple of 4 of the carrier frequency f c (N2 = f s / f c =4*n, n=1, 2,..), which simplifies the digital down-conversion algorithm to the periodic repeated multiplication of the received sample sequence and the sequence (1, j, -1, -j).

[0129] For the receiving end, after the low-pass filter processing, a decimation operation is performed on the samples to reduce the sample rate from f s to the oversampling frequency f os . If f s is not an integer multiple of f os , interpolation is required to obtain the decimated samples. In the embodiments of the present invention, in order to avoid interpolation, it is further proposed to tightly couple the ADC sampling frequency f s with the oversampling frequency f os , requiring f s to be an integer multiple of f os , that is, to satisfy the following formula (4):

[0130] N3 = f s / f os N3: Integer (4)

[0131] In this way, sample extraction can be achieved by selecting a sample at equal intervals (i.e., every N3 samples) from the complex baseband signal (such as the complex sample sequence). That is, the process of extracting signal samples from the complex baseband signal described above may include: extracting signal samples at equal intervals in the complex baseband signal; the value of the equal interval is the ratio of the analog-to-digital conversion frequency to the set oversampling frequency. Assuming that the value of the equal interval N3 is 6, i.e., N3 = 6, then 1 sample needs to be extracted at equal intervals from every 6 samples.

[0132] The signal samples satisfy the following formula (5):

[0133] x (k, α) = x (kT + α / N1 T) (5)

[0134] Where x and x(k,α) are signal samples, that is, the samples after extraction. That is to say, x is the output sample of the extraction function module at the receiving end, k is the symbol interval index, T is the symbol interval, and T = 1 / f sym , α is the oversampling sample index within the symbol interval, α = 0, 1, …, N1, 1, N1 is the oversampling factor. In this implementation manner, the analog-to-digital conversion sampling frequency f s is an integer multiple of the oversampling frequency f os , and the extraction function is achieved by selecting a sample at equal intervals (N3 = f s / f os ) from the sample sequence.

[0135] For symbol decision, accurate symbol timing information of the symbol needs to be obtained. This patent proposes a non-training data-aided symbol timing method based on the signal sample x(k,α). For example, the process of performing symbol decision and differential decoding on the signal sample to obtain the downlink data described above may include: performing a fourth-power operation on the signal sample to obtain the result of the power operation; grouping the result of the power operation according to the oversampling sample index of the signal sample within the symbol interval to obtain N1 groups; calculating the variance of each group according to different oversampling sample indices and determining the group with the smallest variance; determining the symbol timing estimate according to the oversampling sample index corresponding to the group with the smallest variance; performing symbol decision and differential decoding on the signal sample according to the symbol timing estimate to obtain the downlink data.

[0136] Let τ0 be the actual symbol timing, 0 ≤ τ0 < T, and τ be the estimate of the symbol timing. x(kT + τ) is the corresponding sample value. Under ideal channel conditions, when τ = τ0 and QPSK modulation is used, the sample x(kT + τ) corresponds to one of the 4 QPSK modulation symbols and satisfies the following formula (6):

[0137] x(kT + τ0) ∈ {A e j nπ / 4}, n = 0, 1, 2, 3, 0 ≤ τ0 < T (6)

[0138] where x(kT + τ0) is the signal sample corresponding to the actual symbol timing τ0, k is the symbol interval index, T is the symbol interval, and A is a constant coefficient. Taking the fourth power of x(kT + τ) gives the following formula (7):

[0139] u(kT + τ0) = [x(kT + τ0)] 4 = A 4 e j0 = A 4 (7)

[0140] where u(kT + τ0) is the result of the power operation. It can be seen that the result of this power operation is a positive value on the real axis of the complex plane. In the embodiments of the present invention, after the corresponding power operation, the original scattered points on the complex plane converge to a point on the real axis, and a unique symbol timing estimation can be obtained, and the ambiguity disappears.

[0141] To obtain an estimation of the symbol timing τ0 of the k-th symbol, consider the N = 2L + 1 symbol intervals before and after the k-th symbol. Refer to Figure 8 which shows the oversampled signal samples of the (k - 1)-th, k-th, and (k + 1)-th symbol intervals after decimation. α is the oversampling sample index, and N1 is the oversampling factor. It is assumed that τ0 remains unchanged within this time interval. Taking the fourth power of each sample gives the sequence shown in formula (8):

[0142] <u(l, α)> = <[x(l, α)] 4 >, l = k - L, k - L + 1, …, k - 1, k, k + 1, …, k + L (8)

[0143] The sequence <u(l, α)> shown in formula (8) is a complex number sequence, x is the output sample of the decimation function module at the receiving end, l is the symbol interval index, L is a parameter related to the symbol interval, and α is the oversampling sample index.

[0144] Then, according to formulas (9) and (10) respectively, determine the mean and variance of <u(l, α)>:

[0145] ε mean (α) = 1 / N * ∑ u(l, α) (9)

[0146] ε var (α) = 1 / N * ∑ │u(l, α) - εmean (α)│ 2 (10)

[0147] where ε mean (α) is the mean of the sequence, and ε var (α) is the variance of the sequence, l = 0, 1, ……, N - 1, and N is the number of symbols used to estimate symbol timing. For example, if N = 5, it means that 5 adjacent symbols are used to estimate symbol timing.

[0148] According to different α, a total of N1 different variance values are obtained. The present invention proposes a simplified method for symbol timing synchronization, that is, to find the oversampling index α within the symbol interval that minimizes the variance (11), denoted as α0, and α0 satisfies

[0149] ε var (α0) = Min { ε var (α)} for all α ∈ {0, 1,.., N1 - 1} and α ≠ α0 (11)

[0150] where ε var (α0) is the minimum variance of the sequence, and for all represents the value range of α.

[0151] And take the oversampling sample time corresponding to α0 as the estimation of the minimum variance of the actual symbol timing τ0, see formula (12)

[0152] τ(α0) = (α0 / N1 )T (12)

[0153] There are two reasons for the estimation error τ0 - τ(α0). One is channel interference, and the other is quantization error caused by using a finite number of samples N1 within the symbol interval. The quantization error decreases as the oversampling factor N1 increases. Considering the balance between the symbol timing quantization error on the one hand and the algorithm complexity on the other hand, an oversampling factor of N1 ≥ 7 is selected, that is, the number of groups is greater than or equal to 7.

[0154] In this implementation, it is required that the oversampling frequency f os is an integer multiple of the symbol rate f sym and perform a fourth - power operation on the oversampled samples after decimation. According to the sample index of the samples within each symbol interval (there are N1 samples in each symbol interval), divide the result of the power operation into N1 groups. Calculate the variance of each group respectively, and obtain the group with the minimum variance. The corresponding index α (α = 0, 1, …, N1 - 1) of this group is the estimation of the symbol timing that minimizes the variance. In order to reduce the symbol timing estimation error, preferably N1 ≥ 7.

[0155] Based on the symbol timing estimation τ(α0), the receiving end can use the eye diagram opening of the I and Q components for symbol decision-making and complete subsequent operations.

[0156] The following uses a specific embodiment to illustrate the embodiments of the present invention:

[0157] For the transmitting end, it includes processes such as QPSK mapping, oversampling, upconversion, and digital-to-analog conversion (DAC).

[0158] QPSK mapping: The data bit sequence after differential encoding is mapped to a QPSK symbol sequence at the symbol rate f sym ;

[0159] Oversampling: The DQPSK symbols are sampled at a rate much higher than the Nyquist rate. Multiple samples are collected for each symbol, and the oversampling factor is the ratio of the oversampling frequency f os to the symbol rate f sym , N1 = f os / f sym ;

[0160] Upconversion: The oversampled signal is upconverted to the carrier frequency;

[0161] Digital-to-analog conversion (DAC): The digital phase modulation signal after oversampling and upconversion is then converted to an analog signal at a higher sampling frequency. This analog signal is usually used to control the output of the laser.

[0162] For the receiving end, it includes processes such as analog-to-digital conversion (ADC), DDC (Digital Down Converter), low-pass filtering, decimation, symbol synchronization, and symbol decision-making.

[0163] Analog-to-digital conversion (ADC): After passing through a high-pass filter, the analog signal is converted to digital samples at the sampling frequency f s ;

[0164] Digital down conversion (DDC): The carrier phase modulation signal is shifted to the baseband;

[0165] Low-pass filter: Removes high-frequency components and leaves a complex baseband signal with I and Q components;

[0166] Decimation unit: Reduces the sampling rate of the filtered baseband signal to a more manageable level;

[0167] Symbol synchronization: Obtains the symbol timing required for symbol decision-making;

[0168] Symbol decision: Determines the QPSK symbol according to the I (in-phase) and Q (quadrature) components.

[0169] When designing for practical applications, the following parameters can be selected:

[0170]

[0171] Based on the above parameters, the following can be obtained:

[0172]

[0173] The selection of the above parameters meets the requirements of the correlation and coupling between the core parameters of the all-digital transmission and reception architecture of this patent, simplifies the generation of single-carrier phase modulation and laser control signals at the transmitter, greatly simplifies the algorithms of the core functional modules at the receiver, and makes it possible to implement the all-digital reception of the downlink data link using a low-cost and low-power MCU.

[0174] Considering that the sensing nodes in high-voltage and outdoor environments face harsh working conditions. To reduce functional failures and lower maintenance costs, it is necessary to minimize the complexity of the sensing nodes as much as possible and limit the power consumption within the smallest possible range. Therefore, if the laser fiber power supply components can be reused, especially the energy fiber and photovoltaic module on the high-voltage side, to meet the data communication requirements, the system cost, size, and complexity can be reduced. Of particular importance is to reduce the power consumption of the sensing nodes for data communication. High power consumption will inevitably lead to high heat loss in the photovoltaic module, reducing the conversion efficiency, operating reliability, and lifespan of the photovoltaic module. When using the photovoltaic module as the transmitter of the uplink data, the photovoltaic module needs to operate in the forward bias voltage mode, which does not conform to the design purpose of the photovoltaic module. Therefore, the photovoltaic module is not suitable for sharing in uplink data transmission. The embodiments of the present invention focus on the reuse of lasers, energy fibers, and photovoltaic modules in downlink data communication. Through the downlink data modulation and demodulation tailored to the characteristics of laser fiber power supply applications, on the one hand, it can minimize the interference of powerful DC laser energy on signal detection, and on the other hand, it can minimize the implementation complexity and power consumption at the receiver.

[0175] Specifically, in fiber-optic power supply applications, the energy fiber provides sufficient bandwidth resources without sharing with other applications. Restricted by system compatibility requirements and the like, it provides considerable freedom for designing the downlink data communication method. The single-carrier phase modulation proposed in the embodiments of the present invention moves the modulation signal away from the baseband DC frequency. With a low-cost high-pass filter, it effectively realizes the isolation of the data modulation signal and the high-power DC component, minimizing the impact on the received signal and laying the foundation for implementing a fully digital transmit and receive architecture based on low-power and low-cost MCUs. And the embodiments of the present invention propose to tightly couple the key parameters (such as sampling frequency, carrier frequency, oversampling ratio, and symbol rate) of single-carrier phase modulation / demodulation, greatly simplifying the implementation of single-carrier phase modulation and demodulation and reducing power consumption. Furthermore, the embodiments of the present invention further propose to use a square wave to replace the sine wave used for carrier phase modulation. While maintaining the original phase state and data symbol mapping relationship, a control current signal for the laser output can be generated through a 1-bit DAC converter, greatly simplifying the generation of single-carrier phase modulation and laser control signals at the transmitter. Specifically, in the embodiments of the present invention, the laser, the fiber, and the photovoltaic module are multiplexed as the electro-optical converter (in the transmitter part) for downlink data transmission, the transmission medium (in the fiber part) is multiplexed, and the opto-electronic converter (in the receiver part) is multiplexed. In other words, in the embodiments of the present invention, through the multiplexing of the modules in the transmitter and the receiver, using a pure digital transmitter and a digital receiver and combining the corresponding functional units, the Figure 6 complete communication function can be achieved.

[0176] Embodiment 2:

[0177] Based on the same inventive concept, the present invention also provides a communication system, the structural schematic diagram of which is as Figure 9 shown, including: a transmitter and a receiver; the transmitter is used to implement the downlink data transmission method for laser fiber power supply applications in the above embodiments, and the receiver is used to implement the downlink data transmission method for laser fiber power supply applications in the above embodiments.

[0178] Embodiment 3:

[0179] Based on the same inventive concept, the present invention also provides a communication device, which is applied to the transmitter, and the structural schematic diagram of which is as Figure 10 shown, including:

[0180] An encoding and modulation module, configured to perform differential encoding on the downlink data to be transmitted to obtain a data bit sequence; and map the data bit sequence to a modulation symbol sequence by using a single-carrier phase modulation method;

[0181] A digital-to-analog conversion module, configured to perform digital-to-analog conversion on the modulation symbol sequence to obtain an analog signal;

[0182] A driving laser is used to output downstream energy and downstream data through an energy optical fiber according to an analog signal.

[0183] In a possible implementation manner, an encoding and modulation module is specifically configured to map a data bit sequence into a modulation symbol sequence at a set symbol rate by using a single-carrier phase modulation method.

[0184] In a possible implementation manner, the digital-to-analog conversion module includes an oversampling unit and a mixing digital-to-analog conversion unit;

[0185] The oversampling unit is used to oversample the modulation symbol sequence to obtain an oversampled signal.

[0186] The mixing digital-to-analog conversion unit is used to perform up-conversion processing and digital-to-analog conversion on the oversampled signal to obtain an analog signal.

[0187] In a possible implementation manner, the oversampling unit is specifically configured to oversample the modulation symbol sequence at a set oversampling frequency according to an oversampling factor to obtain an oversampled signal; wherein, the oversampling factor is the ratio of the set oversampling frequency to the set symbol rate, and the set oversampling frequency is higher than the Nyquist rate.

[0188] In a possible implementation manner, it further includes:

[0189] A look-up table module is used to determine a square wave sequence corresponding to the initial phase by looking up a table according to the initial phase of the modulation symbol sequence; within each full cycle of the sine wave of the modulation symbol sequence, the sine wave of the modulation symbol sequence is replaced by square waves with alternating polarities in the square wave sequence, and the initial phase of the modulation symbol sequence remains unchanged.

[0190] In a possible implementation manner, the ratio of the carrier frequency of the modulation symbol sequence after square wave substitution to the set symbol rate is an integer multiple of a set coefficient, and the number of square waves with alternating polarities in the square wave sequence is related to the ratio.

[0191] In a possible implementation manner, the mixing digital-to-analog conversion unit is specifically configured to up-convert the oversampled signal to the carrier frequency to obtain a digital phase modulation signal; perform digital-to-analog conversion on the digital phase modulation signal at a digital-to-analog conversion frequency to obtain an analog signal; the digital-to-analog conversion frequency is 4n times the carrier frequency, n is a positive integer, and the digital-to-analog conversion frequency is an integer multiple of the set oversampling frequency.

[0192] Embodiment 4:

[0193] Based on the same inventive concept, the present invention further provides a communication device, which is applied to the receiving end, and the structural schematic diagram is as Figure 11 shown, and includes:

[0194] A filtering conversion module, which is used to perform high-pass filtering processing and analog-to-digital conversion on the received analog signal to obtain digital samples; the analog signal is obtained by the transmitting end performing differential coding on the downlink data to be transmitted to obtain a data bit sequence, adopting a single-carrier phase modulation method to map the data bit sequence into a modulation symbol sequence, and then performing digital-to-analog conversion on the modulation symbol sequence.

[0195] A down-conversion processing module, which is used to perform down-conversion processing and low-pass filtering on the digital samples to obtain a complex baseband signal;

[0196] A decimation module, which is used to decimate signal samples from the complex baseband signal;

[0197] A decision decoding module, which is used to perform symbol decision and differential decoding on the signal samples to obtain the downlink data.

[0198] In a possible implementation manner, the down-conversion processing module includes a down-conversion unit and a low-pass filtering unit;

[0199] The down-conversion unit is used to perform down-conversion processing on the digital samples to obtain complex baseband samples;

[0200] The low-pass filtering unit is used to perform low-pass filtering on the complex baseband samples to obtain a complex baseband signal with in-phase I and quadrature Q components.

[0201] In a possible implementation manner, the complex baseband samples satisfy the following formula:

[0202] y(l) = r(l) * e jln*π / 2

[0203] where y(l) are the complex baseband samples, r(l) are the digital samples, l is the sample index, and j is the imaginary unit.

[0204] In a possible implementation manner, the decimation module is specifically used to decimate signal samples from the complex baseband signal at equal intervals; the value of the equal interval is the ratio of the analog-to-digital conversion frequency to the set oversampling frequency.

[0205] In a possible implementation manner, the signal samples satisfy the following formula:

[0206] x(k,α) = x(kT + α / N1 T)

[0207] where x and x(k,α) are the signal samples, k is the symbol interval index, T is the symbol interval, α is the oversampling sample index within the symbol interval, α = 0, 1, …, N1 - 1, and N1 is the oversampling factor.

[0208] In a possible implementation manner, the decision decoding module is specifically configured to perform a fourth-power operation on the signal samples to obtain a power operation result; group the power operation results according to the oversampling sample indices of the signal samples within the symbol interval to obtain N1 groups; calculate the variance of each group according to different oversampling sample indices and determine the group with the minimum variance; determine the symbol timing estimation value according to the oversampling sample index corresponding to the group with the minimum variance; and perform symbol decision and differential decoding on the signal samples according to the symbol timing estimation value to obtain the downlink data.

[0209] In a possible implementation manner, the number N1 of groups is greater than or equal to 7.

[0210] Embodiment 5:

[0211] As Figure 12 shown, the present invention further provides an electronic device, which may be a computer device, a single-chip microcomputer device, a smart mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected through a bus; the memory can be used to store an execution program, and the exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory can also be used to store data, and the data can be called and / or modified when the instructions are executed.

[0212] The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of a downlink data transmission method for a laser fiber power supply application in the above embodiment.

[0213] Embodiment 6:

[0214] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device-readable storage medium (Memory). The electronic device-readable storage medium is a memory device in the electronic device and is used to store programs and data. It can be understood that the storage medium here can include both the built-in storage medium in the electronic device and, of course, the extended storage medium supported by the electronic device. The storage medium provides a storage space, and this storage space stores the operating system of the terminal. Moreover, one or more instructions suitable for being loaded and executed by the processor are stored in this storage space, and these instructions can be one or more executable programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. By the processor loading and executing one or more instructions stored in the storage medium, the steps of the downlink data transmission method for a laser fiber power supply application in the above embodiments can be implemented.

[0215] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes.

[0216] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0217] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and this instruction device implements the functions in Figure 1 one flow or multiple flows and / or blocks Figure 1The functions specified in one or more boxes.

[0218] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide for implementing the steps of the functions specified in one Figure 1 one process or more processes and / or boxes Figure 1 step of the functions specified in one or more boxes.

[0219] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent replacements to the specific implementation manners of the application. However, these changes, modifications or equivalent replacements are all within the protection scope of the claims pending for approval of the application.

Claims

1. A downlink data transmission method for laser fiber power supply applications, characterized in that Including: Differentially encoding the downlink data to be transmitted to obtain a data bit sequence; Using a single - carrier phase modulation method to map the data bit sequence into a modulation symbol sequence; Performing digital - to - analog conversion on the modulation symbol sequence to obtain an analog signal; Outputting the downlink energy and the downlink data through an energy optical fiber according to the analog signal.

2. The method according to claim 1, characterized in that, The step of using a single - carrier phase modulation method to map the data bit sequence into a modulation symbol sequence includes: Using a single - carrier phase modulation method to map the data bit sequence into a modulation symbol sequence at a set symbol rate.

3. The method according to claim 1 or 2, characterized in that The step of performing digital - to - analog conversion on the modulation symbol sequence to obtain an analog signal includes: Oversampling the modulation symbol sequence to obtain an oversampled signal; Performing up - conversion processing and digital - to - analog conversion on the oversampled signal to obtain an analog signal.

4. The method according to claim 3, wherein The step of oversampling the modulation symbol sequence to obtain an oversampled signal includes: Oversampling the modulation symbol sequence at a set oversampling frequency according to an oversampling factor to obtain an oversampled signal; Wherein, the oversampling factor is the ratio of the set oversampling frequency to the set symbol rate, and the set oversampling frequency is higher than the Nyquist rate.

5. The method according to claim 2, characterized in that After using a single - carrier phase modulation method to map the data bit sequence into a modulation symbol sequence, it further includes: Determining a square - wave sequence corresponding to the initial phase by looking up a table according to the initial phase of the modulation symbol sequence; Within each full cycle of the sine wave of the modulation symbol sequence, using square waves with alternating polarities in the square - wave sequence to replace the sine wave of the modulation symbol sequence, and keeping the initial phase of the modulation symbol sequence unchanged.

6. The method according to claim 5, wherein The ratio of the carrier frequency of the modulation symbol sequence after square - wave replacement to the set symbol rate is an integer multiple of a set coefficient, and the number of square waves with alternating polarities in the square - wave sequence is related to the ratio.

7. The method according to claim 4, wherein The step of performing up - conversion processing and digital - to - analog conversion on the oversampled signal to obtain an analog signal includes: Up - converting the oversampled signal to a carrier frequency to obtain a digital phase - modulation signal; Performing digital - to - analog conversion on the digital phase - modulation signal at a digital - to - analog conversion frequency to obtain an analog signal; The digital - to - analog conversion frequency is 4n times the carrier frequency, where n is a positive integer, and the digital - to - analog conversion frequency is an integer multiple of the set oversampling frequency.

8. A communication device, characterized in that, Including: An encoding and modulation module for differentially encoding the downlink data to be transmitted to obtain a data bit sequence; using a single - carrier phase modulation method to map the data bit sequence into a modulation symbol sequence; A digital - to - analog conversion module for performing digital - to - analog conversion on the modulation symbol sequence to obtain an analog signal; A driving laser for outputting the downlink energy and the downlink data through an energy optical fiber according to the analog signal.

9. The device according to claim 8, wherein The encoding and modulation module is specifically used for using a single - carrier phase modulation method to map the data bit sequence into a modulation symbol sequence at a set symbol rate.

10. The device according to claim 8 or 9, characterized in that, The digital - to - analog conversion module includes an oversampling unit and a mixing digital - to - analog conversion unit; The oversampling unit is used for oversampling the modulation symbol sequence to obtain an oversampled signal; The mixed-frequency digital-to-analog conversion unit is configured to perform up-conversion processing and digital-to-analog conversion on the oversampled signal to obtain an analog signal.

11. The device according to claim 10, wherein The oversampling unit is specifically configured to oversample the modulation symbol sequence at a set oversampling frequency according to an oversampling factor to obtain an oversampled signal; wherein, the oversampling factor is the ratio of the set oversampling frequency to the set symbol rate, and the set oversampling frequency is higher than the Nyquist rate.

12. The device according to claim 9, characterized in that, Further included: A look-up table module, configured to determine a square wave sequence corresponding to the initial phase by looking up a table according to the initial phase of the modulation symbol sequence; Within each full period of the sine wave of the modulation symbol sequence, the sine wave of the modulation symbol sequence is replaced by square waves with alternating polarities in the square wave sequence, and the initial phase of the modulation symbol sequence is kept unchanged.

13. The device according to claim 12, characterized in that, The ratio of the carrier frequency of the modulation symbol sequence after the square wave replacement to the set symbol rate is an integer multiple of a set coefficient, and the number of square waves with alternating polarities in the square wave sequence is related to the ratio.

14. The device according to claim 11, characterized in that, The mixed-frequency digital-to-analog conversion unit is specifically configured to up-convert the oversampled signal to a carrier frequency to obtain a digital phase modulation signal; perform digital-to-analog conversion on the digital phase modulation signal at a digital-to-analog conversion frequency to obtain an analog signal; the digital-to-analog conversion frequency is 4n times the carrier frequency, n is a positive integer, and the digital-to-analog conversion frequency is an integer multiple of the set oversampling frequency.

15. A downlink data transmission method for laser fiber power supply applications, characterized in that, Including: Performing high-pass filtering processing and analog-to-digital conversion on the received analog signal to obtain digital samples; the analog signal is obtained by the transmitting end performing differential coding on the downlink data to be transmitted to obtain a data bit sequence, adopting a single-carrier phase modulation method, mapping the data bit sequence to a modulation symbol sequence, and performing digital-to-analog conversion on the modulation symbol sequence; Performing down-conversion processing and low-pass filtering on the digital samples to obtain a complex baseband signal; Extracting signal samples from the complex baseband signal; Performing symbol decision and differential decoding on the signal samples to obtain downlink data.

16. The method according to claim 15, wherein, The performing down-conversion processing and low-pass filtering on the digital samples to obtain a complex baseband signal includes: Performing down-conversion processing on the digital samples to obtain complex baseband samples; Performing low-pass filtering on the complex baseband samples to obtain a complex baseband signal with in-phase I and quadrature Q components.

17. The method according to claim 16, wherein The complex baseband samples satisfy the following formula: y(l) = r(l) * e jln*π / 2 wherein, y(l) is the complex baseband sample, r(l) is the digital sample, l is the sample index, and j is the imaginary unit.

18. The method according to claim 15, wherein The extracting signal samples from the complex baseband signal includes: In the complex baseband signal, extracting signal samples at equal intervals; the value of the equal interval is the ratio of the analog-to-digital conversion frequency to the set oversampling frequency.

19. The method according to claim 18, wherein The signal samples satisfy the following formula: x(k,α) = x(kT + α / N1 T) wherein, x and x(k,α) are the signal samples, k is the symbol interval index, T is the symbol interval, α is the oversampling sample index within the symbol interval, α = 0, 1, …, N1 - 1, and N1 is the oversampling factor.

20. The method according to claim 19, characterized in that, The performing symbol decision and differential decoding on the signal samples to obtain downlink data includes: Perform a fourth-power operation on the signal samples to obtain a result of the power operation; Group the results of the power operation according to the oversampling sample indices of the signal samples within the symbol interval to obtain N1 groups; Calculate the variance of each group according to different oversampling sample indices and determine the group with the minimum variance; Determine the symbol timing estimation according to the oversampling sample index corresponding to the group with the minimum variance; Perform symbol decision and differential decoding on the signal samples according to the symbol timing estimation to obtain the downlink data.

21. The method according to claim 20, wherein The number N1 of the groups is greater than or equal to 7.

22. A communication device, characterized in that, Including: A filter conversion module for performing high-pass filtering processing and analog-to-digital conversion on the received analog signal to obtain digital samples; the analog signal is obtained by the transmitting end performing differential coding on the downlink data to be transmitted to obtain a data bit sequence, adopting a single-carrier phase modulation method to map the data bit sequence into a modulation symbol sequence, and then performing digital-to-analog conversion on the modulation symbol sequence; A down-conversion processing module for performing down-conversion processing and low-pass filtering on the digital samples to obtain a complex baseband signal; A decimation module for decimating signal samples from the complex baseband signal; A decision decoding module for performing symbol decision and differential decoding on the signal samples to obtain the downlink data.

23. The device according to claim 22, characterized in that, The down-conversion processing module includes a down-conversion unit and a low-pass filtering unit; The down-conversion unit is used for performing down-conversion processing on the digital samples to obtain complex baseband samples; The low-pass filtering unit is used for performing low-pass filtering on the complex baseband samples to obtain a complex baseband signal having in-phase I and quadrature Q components.

24. The device according to claim 23, wherein The complex baseband samples satisfy the following formula: y(l) = r(l) * e jln*π / 2 where y(l) is the complex baseband sample, r(l) is the digital sample, l is the sample index, and j is the imaginary unit.

25. The device according to claim 22, characterized in that, The decimation module is specifically used for decimating signal samples at equal intervals from the complex baseband signal; the value of the equal interval is the ratio of the analog-to-digital conversion frequency to the set oversampling frequency.

26. The device according to claim 25, wherein The signal samples satisfy the following formula: x(k,α) = x(kT + α / N1 T) where x and x(k,α) are signal samples, k is the symbol interval index, T is the symbol interval, α is the oversampling sample index within the symbol interval, α = 0, 1,..., N1 - 1, and N1 is the oversampling factor.

27. The device according to claim 26, wherein The decision decoding module is specifically used for performing a fourth-power operation on the signal samples to obtain a result of the power operation; grouping the results of the power operation according to the oversampling sample indices of the signal samples within the symbol interval to obtain N1 groups; calculating the variance of each group according to different oversampling sample indices and determining the group with the minimum variance; determining the symbol timing estimation according to the oversampling sample index corresponding to the group with the minimum variance; Performing symbol decision and differential decoding on the signal samples according to the symbol timing estimation to obtain the downlink data.

28. The device according to claim 27, wherein The number N1 of the groups is greater than or equal to 7.

29. A communication system, characterized in that, It includes a transmitting end and a receiving end; the transmitting end is used to implement the downlink data transmission method for laser fiber power supply applications described in any one of claims 1-7 above, and the receiving end is used to implement the downlink data transmission method for laser fiber power supply applications described in any one of claims 15-21 above.

30. An electronic device, characterized in that, It includes: At least one processor and a memory; The memory and the processor are connected by a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, the downlink data transmission method for laser fiber power supply applications described in any one of claims 1-7 above is implemented, or the downlink data transmission method for laser fiber power supply applications described in any one of claims 15-21 above is implemented.

31. A readable storage medium, characterized in that, There is an execution program stored thereon, and when the execution program is executed, the downlink data transmission method for laser fiber power supply applications described in any one of claims 1-7 above is implemented, or the downlink data transmission method for laser fiber power supply applications described in any one of claims 15-21 above is implemented.

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