A laser microwave hybrid adaptive satellite-to-ground data transmission device

Abstract

The present invention discloses a laser microwave hybrid adaptive satellite-to-ground data transmission device. In view of the fact that the conventional satellite-to-ground data transmission system adopts a fixed coding modulation mode (CCM), the link planning usually considers the longest communication distance and the worst weather conditions, and cannot make corresponding adjustments according to the changes of the wireless channel, resulting in resource waste and low data transmission reliability. By real-time detection of the OSNR or E s The / N0 estimation result generates a link switching instruction, and sends the relevant instructions to the satellite part through the uplink feedback link to realize the autonomous switching of laser and microwave links. This laser-microwave hybrid link design can provide high-speed data transmission capability and ensure the reliability of the satellite-to-ground data transmission link.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite communications, and in particular relates to a laser microwave hybrid adaptive satellite-to-ground data transmission device. Background Art

[0002] Satellite-to-ground data transmission is a wireless communication system that transmits a large amount of payload data from space back to the ground via satellite. The traditional satellite-to-ground data transmission system uses microwaves as the signal transmission medium. The advantage is that microwave signals have a strong ability to penetrate clouds and haze and are less affected by changes in the atmospheric environment.

[0003] As the scale and number of space satellite systems continue to increase, frequency resources in the microwave band are becoming increasingly scarce, limiting the development of future large-capacity, high-speed satellite-to-ground data transmission systems. Laser communication uses laser as a signal transmission medium, which has the advantages of large bandwidth, high confidentiality, and strong anti-interference. In recent years, it has gradually been applied in the field of high-speed satellite-to-ground data transmission.

[0004] However, laser signals are easily affected by weather conditions such as clouds, rain, fog, and haze, which can lead to a decrease in the system's communication quality or even link interruption. Traditional satellite-to-ground data transmission systems use fixed coding modulation (CCM), and link planning usually takes into account the longest communication distance and the worst weather conditions, and cannot make corresponding adjustments based on changes in wireless channels. However, the actual working environment of satellite-to-ground data transmission systems is often better than the worst case, and the link margin is far greater than the actual need, which not only causes a serious waste of satellite-to-ground communication resources, but also restricts the continuous improvement of data transmission capabilities. Summary of the invention

[0005] The purpose of the present invention is to provide a laser-microwave hybrid adaptive satellite-to-ground data transmission device, which has the transmission advantages of both laser and microwave, and can enable the satellite-to-ground data transmission link to maintain the advantages of large capacity and ultra-high-speed transmission while minimizing the impact of the atmospheric environment on transmission and improving the reliability of the system.

[0006] To solve the above problems, the technical solution of the present invention is:

[0007] A laser-microwave hybrid adaptive satellite-to-ground data transmission device, supporting both laser communication and microwave communication modes, comprising: a satellite-borne device and a ground-based device;

[0008] The ground device adjusts the laser link signal-to-noise ratio OSNR and the microwave link signal-to-noise ratio E s / N0 performs real-time estimation, and feeds back communication mode control information generated based on the signal-to-noise ratio estimation result to the satellite-borne device in real time through the uplink S link; the ground device generates a signal-to-noise ratio estimation result based on the OSNR and E s / N0, the following strategies are used to achieve autonomous switching of laser microwave links:

[0009] Taking laser communication as the main mode, the real-time estimated OSNR and E s / N0 is compared with the corresponding threshold:

[0010] When the estimated value of OSNR is higher than the laser link threshold and E s When the estimated value of / N0 is higher than the microwave link threshold, the satellite-to-ground system maintains the laser link unchanged;

[0011] When the estimated OSNR is lower than the laser link threshold and E s When the estimated value of / N0 is higher than the microwave link threshold, it switches to the microwave link mode;

[0012] In microwave communication mode, when the estimated value of OSNR is higher than the laser link threshold again, regardless of E s If the estimated value of / N0 is higher than the microwave link threshold, the mode is switched to the laser link mode;

[0013] When the estimated value of OSNR is lower than the laser link threshold and E s When the estimated value of / N0 is lower than the microwave link threshold, the onboard data is stored in the solid-state memory.

[0014] According to an embodiment of the present invention, the satellite-borne device includes: a baseband data processing module, a laser channel, a laser transmitting antenna, a microwave channel, a Ka-band transmitting antenna, an ACM command receiving controller, and an S-band receiving antenna;

[0015] The baseband data processing module receives the payload data or obtains the data from the solid-state memory module, and performs data multiplexing, AOS framing, scheduling, routing and forwarding on the data;

[0016] The laser channel module is connected to the baseband data processing module to receive the data processed by the baseband data processing module; the laser channel module is also connected to the ACM instruction receiving controller to receive the control instruction output by the ACM instruction receiving controller to complete the required high-speed laser signal modulation;

[0017] The laser transmitting antenna is connected to the laser channel module, and transmits the signal output by the laser channel module to the ground receiving station according to the specified direction;

[0018] The microwave channel module is connected to the baseband data processing module to receive the data routed by the baseband data processing module; the microwave channel is also connected to the ACM instruction receiving controller to receive the control instructions output by the ACM instruction receiving controller to achieve the required modulation and amplification processing of the Ka-band microwave signal;

[0019] The Ka-band transmitting antenna is connected to the microwave channel module to transmit the signal output by the microwave channel module to the ground receiving station according to the specified direction;

[0020] The S-band receiving antenna is connected to the ACM command receiving controller, receives signals and sends them to the ACM command receiving controller.

[0021] According to one embodiment of the present invention, the baseband data processing module is also used to receive the transmission mode control instruction output by the ACM instruction receiving controller to realize the autonomous switching of the system laser and microwave links and the adaptive selection of the corresponding link information rate and coding modulation method.

[0022] According to an embodiment of the present invention, the ground device includes: a laser receiving antenna, a laser receiving subsystem, a Ka-band receiving antenna, a microwave receiving subsystem, a ground data processing and storage, an ACM instruction generating transmitter, and an S-band transmitting antenna;

[0023] The laser receiving antenna receives a downlink laser signal transmitted by a satellite;

[0024] The laser receiving subsystem receives the signal output by the laser receiving antenna, realizes the detection and photoelectric conversion of the laser signal, and estimates the OSNR in real time;

[0025] The Ka-band receiving antenna receives a downlink Ka-band microwave signal transmitted by a satellite;

[0026] The microwave receiving subsystem receives the signal output by the Ka-band receiving antenna, realizes down-conversion and demodulation of the microwave signal, and estimates E in real time. s / N0;

[0027] The ground data processing and storage module receives the data output by the laser receiving subsystem and the microwave receiving subsystem, implements data frame analysis, channel decoding, and storage, and obtains the transmitted payload data;

[0028] The ACM instruction generates the signal-to-noise ratio information estimated in real time by the laser receiving subsystem and the microwave receiving subsystem received by the transmitter, and according to the adaptive transmission strategy, the link signal-to-noise ratio estimation result is compared with the preset lookup table to complete the link, information rate and coding modulation mode selection under the current channel state, and then the relevant information is packaged into a transmission mode control instruction;

[0029] The S-band transmitting antenna is connected to the ACM command generating transmitter, and transmits the signal output by the ACM command generating transmitter to the corresponding satellite;

[0030] The S-band receiving antenna is used to receive the signal radiated by the S-band transmitting antenna and send the signal to the ACM instruction receiving controller.

[0031] According to an embodiment of the present invention, the ACM instruction generating transmitter of the ground device is provided with three sets of lookup tables based on the signal-to-noise ratio estimation results, which are:

[0032] Laser link signal-to-noise ratio OSNR, microwave link signal-to-noise ratio E s / N0 threshold lookup table;

[0033] Preset OSNR classification corresponding to different information rate and coding mode combinations;

[0034] Preset E s / N0 The lookup table corresponding to different information rate and coding modulation mode combinations.

[0035] According to an embodiment of the present invention, after the onboard device switches to the laser link or microwave link, the ACM instruction generating transmitter selects the information rate and the coding modulation mode according to the following steps:

[0036] For laser links, the real-time estimated OSNR is compared with the preset OSNR bin lookup table, the information rate and coding method corresponding to the bin range containing the current OSNR estimate are selected, the control command is generated, and it is transmitted to the satellite through the S-band transmitting antenna;

[0037] For microwave links, the real-time estimated E s / N0 and preset E s / N0 bin lookup table for comparison, select the one containing the current E s The information rate and coding modulation method corresponding to the grading range of the / N0 estimated value generate control instructions and are sent to the satellite through the S-band transmitting antenna.

[0038] According to one embodiment of the present invention, the ACM instruction receiving controller of the satellite-borne device receives the ground ACM instruction through the on-board S-band receiving antenna to generate the transmission mode control instruction sent by the transmitter, and parses it into the operation instruction of the satellite-borne baseband data processing module for the information rate, LDPC coding rate, modulation mode and link routing, and controls the satellite-borne system to implement the autonomous seamless switching and adaptive data transmission of the laser and microwave links according to the operation instruction, thereby realizing the satellite-ground closed-loop control of the laser-microwave hybrid adaptive link.

[0039] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0040] 1) The laser microwave hybrid adaptive satellite-to-ground data transmission device in one embodiment of the present invention adopts a fixed coding modulation (CCM) mode in the traditional satellite-to-ground data transmission system. Link planning usually takes into account the longest communication distance and the worst weather conditions, and cannot make corresponding adjustments according to changes in the wireless channel, resulting in resource waste and low data transmission reliability. By real-time detection of the OSNR or E s The / N0 estimation result generates a link switching instruction, and sends the relevant instructions to the satellite part through the uplink feedback link to realize the autonomous switching of laser and microwave links. This laser-microwave hybrid link design can provide high-speed data transmission capability and ensure the reliability of the satellite-to-ground data transmission link.

[0041] 2) The present invention adopts a satellite-ground coordinated adaptive transmission system based on ACM technology, which can realize adaptive transmission of both laser links and microwave links. The satellite-borne part has the ability to realize multiple information rates and coding modulation combinations. By real-time detection of the OSNR or E s / N0, the ACM instruction generation transmitter completes the selection of the corresponding information rate and coding modulation method according to the preset lookup table and feeds back the relevant instructions to the satellite system to complete the adaptive transmission of the laser link or microwave link respectively. Among them, since the laser bandwidth is large enough, the modulation method of the laser link is fixed to QPSK, and the coding method can be adaptively adjusted. This adaptive transmission system can realize the adaptive adjustment of the coding modulation efficiency and information rate of the satellite-to-ground data transmission system by switching the coding modulation combination when the symbol transmission rate is fixed, which can effectively improve the utilization of channel resources.

[0042] 3) For laser links and microwave links, the present invention maintains the same ACM frame format design at the data link layer, so that the baseband data processing module can process data according to a unified process, saving computing resources. The baseband data can be flexibly switched to the laser channel or the microwave channel through the data routing submodule. At the same time, since the satellite system schedules and distributes data in frames, not only will there be no frame loss when the laser link and the microwave link switch the coding modulation mode in their respective modes, but there will also be no frame loss when autonomously switching between the laser link and the microwave link, thereby achieving seamless switching of laser and microwave data.

[0043] 4) The present invention adopts the S-band to construct the ACM feedback link. Since the S-band has less atmospheric absorption, less rain attenuation, and less free space loss, and the satellite uses an S-band omnidirectional antenna for reception, it has a wide reception range and is easy to establish a link. It is very suitable for realizing adaptive closed-loop feedback control of large satellite-to-ground systems in all-weather, all-time, and all-domain scenarios, and can ensure that the laser microwave hybrid link can achieve adaptive transmission in different climate environments and different communication distances. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the composition of a laser-microwave hybrid adaptive satellite-to-ground data transmission device in one embodiment of the present invention;

[0045] Figure 2 Schematic diagram of the laser microwave adaptive transmission process in one embodiment of the present invention;

[0046] Figure 3 Schematic diagram of the principle of a satellite-borne baseband data processing module in one embodiment of the present invention;

[0047] Figure 4 Schematic diagram of the principle of a satellite-borne laser channel module in one embodiment of the present invention;

[0048] Figure 5 is a schematic diagram of the principle of a satellite-borne microwave channel module in one embodiment of the present invention;

[0049] Figure 6 A schematic diagram of the principle of a ground ACM instruction generating transmitter in one embodiment of the present invention;

[0050] Figure 7 The figure is a schematic diagram of the principle of a satellite-borne ACM command receiving controller in one embodiment of the present invention. DETAILED DESCRIPTION

[0051] The laser microwave hybrid adaptive satellite-to-ground data transmission device proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims.

[0052] This embodiment provides a laser-microwave hybrid adaptive satellite-to-ground data transmission device with two links, laser and microwave. The ground receiving end measures the laser link signal-to-noise ratio (OSNR) and the microwave link signal-to-noise ratio (ESR). s / N0) is estimated in real time, and transmission mode control information is generated according to the preset adaptive transmission strategy of the system, and the uplink S link is used to feed back to the satellite, so as to build a satellite-to-ground closed-loop adaptive transmission architecture. The satellite can autonomously switch between the laser link and the microwave link in real time according to the changes in the atmospheric environment and the satellite-to-ground communication distance, and adaptively select the information rate and coding modulation combination (MODCOD) of the current link, so as to maximize the channel utilization rate on the basis of combining the large bandwidth transmission of the laser link and the high reliability link establishment of the microwave link.

[0053] For details, please see Figure 1The laser microwave hybrid adaptive satellite-to-ground data transmission device in this embodiment includes a satellite device and a ground device. Among them, the satellite part is composed of modules such as baseband data processing, laser channel, laser transmitting antenna, microwave channel, Ka-band transmitting antenna, ACM command receiving controller, S-band receiving antenna and optional solid-state memory; the ground part is composed of modules such as laser receiving antenna, laser receiving subsystem, Ka-band receiving antenna, microwave receiving subsystem, ground data processing and storage, ACM command generation transmitter and S-band transmitting antenna. The main functions of each module are described as follows:

[0054] The baseband data processing module can directly receive payload data or obtain data from the solid-state memory module, and then perform data multiplexing, AOS framing, scheduling, routing and forwarding in a unified data processing flow. At the same time, the baseband data processing module is also used to receive the transmission mode control instructions output by the ACM instruction receiving controller to achieve autonomous switching of the system's laser and microwave links and adaptive selection of the corresponding link information rate and coding modulation mode;

[0055] The laser channel module is connected to the baseband data processing module and the ACM command receiving controller, and can receive the data routed by the baseband data processing module and the control instructions output by the ACM command receiving controller, thereby completing the required high-speed laser signal modulation;

[0056] The laser transmitting antenna is connected to the laser channel module, and its function is to transmit the signal output by the laser channel module to the ground receiving station in the specified direction;

[0057] The microwave channel module is also connected to the baseband data processing module and the ACM command receiving controller, and can receive the data routed by the baseband data processing module and the control instructions output by the ACM command receiving controller, thereby realizing the required modulation and amplification processing of the Ka-band microwave signal;

[0058] The Ka-band transmitting antenna is connected to the microwave channel module, and its function is to transmit the signal output by the microwave channel module to the ground receiving station in the specified direction;

[0059] The laser receiving antenna is responsible for receiving the downlink laser signal transmitted by the satellite;

[0060] The laser receiving subsystem receives the signal output by the laser receiving antenna, detects the laser signal, performs photoelectric conversion and other processing, and estimates OSNR in real time.

[0061] The Ka-band receiving antenna is responsible for receiving the downlink Ka-band microwave signal transmitted by the satellite;

[0062] The microwave receiving subsystem receives the signal output by the Ka-band receiving antenna, performs microwave signal down-conversion and demodulation, and estimates E in real time. s / N0;

[0063] The function of the ground data processing and storage module is to receive the data output by the laser receiving subsystem and the microwave receiving subsystem, implement data frame analysis, channel decoding, storage and other processing, and finally obtain the transmitted payload data;

[0064] The ACM command generation transmitter is used to receive the real-time estimated signal-to-noise ratio information (OSNR or E s / N0), according to the adaptive transmission strategy, by comparing the link signal-to-noise ratio estimation result with the preset lookup table, the link, information rate and coding modulation mode selection under the current channel state are completed, and then the relevant information is packaged into a transmission mode control instruction;

[0065] The S-band transmitting antenna is connected to the ACM command generating transmitter, and its function is to transmit the signal output by the ACM command generating transmitter to the corresponding satellite;

[0066] The function of the S-band receiving antenna is to receive the signal radiated by the S-band transmitting antenna and send the signal to the ACM command receiving controller;

[0067] The ACM command receiving control module is connected to the S-band receiving antenna. Its function is to receive the signal output by the S-band receiving antenna in real time and perform down-conversion, analog-to-digital conversion (ADC), demodulation, decoding, and command parsing. In addition, the ACM command receiving controller is also connected to the baseband data processing, laser channel, and microwave channel modules respectively, and sends the parsed transmission mode control instructions to these three modules so that the three modules can work together to realize the corresponding link switching, information rate, and coding modulation mode adaptive selection functions.

[0068] Please see Figure 2 The laser microwave adaptive transmission strategy of the laser microwave hybrid adaptive satellite-to-ground data transmission device in this embodiment is as follows:

[0069] The laser link is in the default main mode. When the OSNR and E s When the estimated values ​​of / N0 are both higher than the threshold requirements, the laser link is maintained unchanged, and the OSNR estimated value is compared with the preset OSNR graded lookup table to complete the selection of information rate and coding method under the current channel conditions of the laser link; the threshold here comes from the preset laser link signal-to-noise ratio OSNR and microwave link signal-to-noise ratio E s / N0 threshold lookup table.

[0070] When the estimated OSNR value at the receiving end is lower than the laser link threshold requirement and E s When the estimated value of / N0 is higher than the threshold requirement of the microwave link, the system switches to the microwave link and s / N0 estimated value and preset E s / N0 graded lookup table is used for comparison to complete the selection of information rate and coding modulation combination under the current channel conditions of the microwave link;

[0071] In microwave link mode, when the estimated value of the receiving end OSNR reaches the threshold again, regardless of E s / N0 is higher than the threshold, the link mode is switched to laser mode; when the estimated OSNR value at the receiving end is equal to E s When the estimated values ​​of / N0 are lower than the threshold requirements of the corresponding links at the same time, the satellite-to-ground data transmission is suspended and the payload data is stored in the solid-state memory.

[0072] In addition, in order to improve the OSNR and E s / N0 performs uninterrupted real-time estimation. When the estimated OSNR value at the receiving end is lower than the threshold requirement of the laser link, the beacon transmission of the laser link needs to be turned on, and the OSNR of the receiving end continues to be detected. s When the estimated value of / N0 is lower than the threshold requirement of the microwave link, the empty frame signal transmission of the microwave link is started, and the E s / N0 for detection.

[0073] Please see Figure 3 The baseband data processing module is composed of submodules such as data caching and distribution, framing and coding processing, physical layer framing, and data routing. In this embodiment, the baseband data processing module is equipped with 4 data processing channels, each of which includes 1 framing and coding processing submodule and 1 physical layer framing submodule.

[0074] Specifically, the data cache and distribution submodule is used to cache the received payload data and distribute it to the framing coding processing submodule as needed for the next step of processing. In this embodiment, when the laser link is working, the data cache and distribution submodule converts the payload data into 2 parallel data paths and distributes them to any 2 selected data processing channels, and the data processing capacity of each channel is 10Gb / s. At this time, the entire baseband data processing module has a data processing capacity of 20Gb / s; when the microwave link is working, the data cache and distribution submodule converts the payload data into 4 parallel data paths and distributes them to 4 data processing channels, and the data processing capacity of each channel is 3Gb / s. At this time, the entire baseband data processing module has a data processing capacity of 12Gb / s.

[0075] The framing and coding processing submodule receives the payload data output by the data caching and distribution submodule, and completes data caching, data multiplexing, AOS framing, BCH coding, LDPC coding, and bit interleaving. Channel coding is performed using BCH code as the outer code and LDPC code as the inner code. The optional code rates of LDPC code include 1 / 4, 1 / 3, 2 / 5, 1 / 2, 3 / 5, 2 / 3, 3 / 4, 5 / 6, 8 / 9, and 9 / 10.

[0076] The physical layer framing submodule receives the data output by the framing coding processing submodule, and performs constellation mapping, time slot segmentation, pilot insertion, physical layer scrambling and other processing. At the same time, the physical layer framing submodule performs RM (Reed-Muller) encoding, spread spectrum m code sequence scrambling, and frame identification on the physical layer signaling to form a physical layer frame header. The binary bit data of the physical layer frame header is mapped according to the π / 2BPSK method and together with the symbols in the data area, it forms a physical frame to form a unified frame format. Among them, the modulation modes supported by the constellation mapping part include QPSK, 8PSK, 16APSK and 32APSK. Note that in laser link mode, the modulation mode is fixed to QPSK.

[0077] The data routing submodule receives the data output by the physical layer framing submodule, and sends the data to the laser channel module or the microwave channel module according to the system link selection result. Specifically, when the laser link is working, the data routing submodule sends the data output by the selected two data processing channels to the laser channel module; when the microwave link is working, the data routing submodule sends the data output by all four data processing channels to the microwave channel module.

[0078] Please see Figure 4 The laser channel module consists of two laser modulation submodules (laser modulation 1, laser modulation 2) and a wavelength division multiplexing submodule. The two laser modulation submodules receive two 10Gb / s data paths routed from the baseband data processing module (Note: Figure 4The 10Gb / s data has been converted into two data paths with a rate of 5Gb / s, namely I path and Q path), and the input electrical signal is modulated into a laser signal. Each laser modulation submodule includes an electro-optical modulator (electro-optical modulator 1 or electro-optical modulator 2), a narrow linewidth laser (narrow linewidth laser 1 or narrow linewidth laser 2) and a microprocessor (MBC1 or MBC2). Narrow linewidth laser 1 and narrow linewidth laser 2 are used to generate two laser carriers of different wavelengths. The electro-optical modulator modulates the electrical signal into a laser signal using QPSK and other methods. The microprocessor (MBC) coordinates the bias point of the electro-optical modulator to ensure that the quality of the laser signal generated at a rate of 10Gb / s is in the optimal state. The wavelength division multiplexing submodule uses a wavelength division multiplexer with a frequency interval of 50GHz to multiplex the two laser signals output by the two laser modulation submodules to form a high-speed laser signal with a rate of 20Gb / s.

[0079] Please see Figure 5 ,The microwave channel module consists of 4 high-speed modulators, 4 Ka-band linearized traveling wave tube amplifiers and 2 duplexers.

[0080] The four high-speed modulators receive four channels of 3Gb / s data routed from the baseband data processing module and complete the Ka-band signal modulation. The high-speed modulator receives data through the optical fiber interface, then performs physical frame header recognition and frame synchronization, performs π / 2BPSK modulation on the frame header, and performs shaping filtering, orthogonal modulation and other processing on the valid data area. The modulation modes that can be implemented by the high-speed modulator include QPSK, 8PSK, 16APSK and 32APSK. The generated digital signal is converted into an intermediate frequency analog signal of the S band after digital-to-analog conversion (DAC), and then mixed with the Ka-band local oscillator source after suppressing the image frequency through a bandpass filter to achieve signal up-conversion processing, and finally output after further amplification and filtering. The Ka-band local oscillator sources of the four high-speed modulators generate four carrier signals with different frequencies, so that the high-speed modulator can output four Ka-band signals with different frequencies.

[0081] Four Ka-band linearized traveling wave tube amplifiers are connected to four high-speed modulators respectively to receive four Ka-band signals output by the four high-speed modulators. The Ka-band linearized traveling wave tube amplifier performs analog pre-distortion processing on the received Ka-band signals to suppress nonlinear noise to reduce the performance degradation of high-order modulated signals after passing through nonlinear channels, and then amplifies the signal power to a suitable working range.

[0082] Duplexer 1 combines the high-power signals of different frequencies output by Ka-band linearized traveling wave tube amplifier 1 and Ka-band linearized traveling wave tube amplifier 2 to generate a 6Gb / s high-speed signal, and sends it to the left-handed polarization port of the Ka-band transmitting antenna. Duplexer 2 combines the high-power signals of different frequencies output by Ka-band linearized traveling wave tube amplifier 3 and Ka-band linearized traveling wave tube amplifier 4 to generate a 6Gb / s high-speed signal, and sends it to the right-handed polarization port of the Ka-band transmitting antenna.

[0083] Please see Figure 6 The ACM instruction generation transmitter consists of two submodules: signal processing and S-band up-conversion. The signal processing submodule receives the OSNR estimated by the ground laser receiving subsystem and the E estimated by the ground microwave receiving subsystem. s / N0, select the link and the corresponding information rate and coding modulation according to the adaptive transmission strategy. Then, the above-mentioned mode selection information is processed by instruction framing, encoding, modulation and digital-to-analog conversion and then output. Here, the encoding process uses 1 / 2LDPC code, and the modulation method uses BPSK. The S-band mixer in the S-band up-conversion submodule is connected to the DAC in the signal processing submodule, and is used to receive the signal output by the above-mentioned DAC and up-convert it to the S band. In addition, the S-band local oscillator source is connected to the S-band mixer to provide it with a carrier signal of a specific frequency in the S band. The signal output by the S-band mixer is filtered and amplified before output to obtain a transmission mode control command signal with a rate of 1Mb / s.

[0084] Please see Figure 7 The ACM command receiving controller consists of two sub-modules: S-band down-conversion and signal processing. The S-band down-conversion sub-module is connected to the S-band receiving antenna, receives the signal output at a rate of 1Mb / s, and completes the down-conversion processing through the S-band mixer after amplification and filtering, reducing the signal frequency to the intermediate frequency. The S-band local oscillator here is used to generate a specific frequency signal for use by the S-band mixer. After receiving the signal output by the S-band down-conversion sub-module, the signal processing sub-module first performs analog-to-digital conversion, demodulation and decoding, and then parses the transmission mode control command and forwards it to the baseband data processing, laser channel and microwave channel modules in real time. The three work together to control the information rate, coding modulation combination and routing of the system to achieve adaptive transmission.

[0085] The ACM command generation transmitter, S-band transmitting antenna, S-band receiving antenna and ACM command receiving controller together constitute the system's uplink feedback link, which together with the downlink that transmits payload data forms a satellite-ground coordinated adaptive data transmission system. The uplink feedback link works in the S-band and has a better than 1×10 -7The error performance can ensure the reliable and accurate transmission of transmission mode control instructions.

[0086] In summary, the laser-microwave hybrid adaptive satellite-to-ground data transmission device in this embodiment has two satellite-to-ground data transmission links, laser and microwave. The laser link, as the default main transmission link, can provide large-capacity (20Gb / s) and highly confidential communication capabilities to meet the growing demand for payload data transmission. The microwave link can improve the link availability in severe weather conditions such as clouds, rain, fog, and haze, while providing 12Gb / s communication capabilities. Based on the system's adaptive transmission strategy, by setting the ACM instruction generation transmitter and the ACM instruction receiving controller, the receiving end OSNR and E s The / N0 estimation result generates a link switching instruction, and completes the selection of the corresponding information rate and coding modulation method according to the preset lookup table, and sends the relevant instructions to the satellite part through the uplink feedback link to realize the autonomous switching of laser and microwave links. This laser-microwave hybrid link design can provide high-speed data transmission capability and ensure the reliability of the satellite-to-ground data transmission link.

[0087] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A laser-microwave hybrid adaptive satellite-to-ground data transmission device, supporting both laser communication and microwave communication modes, characterized in that: include: Spaceborne devices and ground devices; The ground device adjusts the laser link signal-to-noise ratio OSNR and the microwave link signal-to-noise ratio E s / N0 performs real-time estimation, and feeds back communication mode control information generated based on the signal-to-noise ratio estimation result to the satellite-borne device in real time through the uplink S link; The ground device estimates the OSNR and E in real time. s / N0, the following strategies are used to achieve autonomous switching of laser microwave links: Taking laser communication as the main mode, the real-time estimated OSNR and E s / N0 is compared with the corresponding threshold: When the estimated value of OSNR is higher than the laser link threshold and E s When the estimated value of / N0 is higher than the microwave link threshold, the laser-microwave hybrid adaptive satellite-to-ground data transmission device maintains the laser link unchanged; When the estimated OSNR is lower than the laser link threshold and E s When the estimated value of / N0 is higher than the microwave link threshold, it switches to the microwave link mode; In microwave communication mode, when the estimated value of OSNR is higher than the laser link threshold again, regardless of E s If the estimated value of / N0 is higher than the microwave link threshold, the mode is switched to the laser link mode; When the estimated value of OSNR is lower than the laser link threshold and E s When the estimated value of / N0 is lower than the microwave link threshold, the onboard data is stored in the solid-state memory; The ACM instruction receiving controller of the satellite-borne device receives the ground ACM instruction through the satellite S-band receiving antenna to generate the transmission mode control instruction sent by the transmitter, and parses it into the operation instruction of the satellite-borne baseband data processing module for the information rate, LDPC coding rate, modulation mode and link routing, and controls the satellite-borne device to implement the autonomous seamless switching and adaptive data transmission of the laser and microwave links according to the operation instruction, thereby realizing the satellite-ground closed-loop control of the laser-microwave hybrid adaptive link; The baseband data processing module of the satellite device performs framing encoding on the received payload data, generates physical frames according to a unified frame format, and routes the data to the laser channel module or the microwave channel module in units of frames according to the link mode of the laser-microwave hybrid adaptive satellite-to-ground data transmission device; When transmitting in a laser link, wavelength division multiplexing technology is used. A wavelength division multiplexer with a specific frequency interval is used to multiplex the n laser signals output by n laser modulation modules to generate a high-speed laser signal with a rate that is n times the rate of a single signal, thereby achieving high-speed data transmission.

2. The laser-microwave hybrid adaptive satellite-to-ground data transmission device according to claim 1, characterized in that: The satellite-borne device includes: a baseband data processing module, a laser channel module, a laser transmitting antenna, a microwave channel module, a Ka-band transmitting antenna, an ACM command receiving controller, and an S-band receiving antenna; The baseband data processing module receives the payload data or obtains the data from the solid-state memory, and performs data caching and distribution, framing coding, physical layer framing and data routing processing on the data; The laser channel module is connected to the baseband data processing module to receive the data processed by the baseband data processing module; the laser channel module is also connected to the ACM instruction receiving controller to receive the control instruction output by the ACM instruction receiving controller to complete the required high-speed laser signal modulation; The laser transmitting antenna is connected to the laser channel module, and transmits the signal output by the laser channel module to the ground receiving station according to the specified direction; The microwave channel module is connected to the baseband data processing module to receive the data routed by the baseband data processing module; the microwave channel module is also connected to the ACM instruction receiving controller to receive the control instructions output by the ACM instruction receiving controller to achieve the required modulation and amplification processing of the Ka-band microwave signal; The Ka-band transmitting antenna is connected to the microwave channel module to transmit the signal output by the microwave channel module to the ground receiving station according to the specified direction; The S-band receiving antenna is connected to the ACM command receiving controller, receives signals and sends them to the ACM command receiving controller.

3. The laser-microwave hybrid adaptive satellite-to-ground data transmission device according to claim 2, characterized in that: The baseband data processing module is also used to receive the transmission mode control instruction output by the ACM instruction receiving controller, so as to realize the autonomous switching of the laser and microwave links of the laser-microwave hybrid adaptive satellite-to-ground data transmission device and the adaptive selection of the corresponding link information rate and coding modulation mode.

4. The laser-microwave hybrid adaptive satellite-to-ground data transmission device according to claim 1, characterized in that: The ground device includes: a laser receiving antenna, a laser receiving subsystem, a Ka-band receiving antenna, a microwave receiving subsystem, a ground data processing and storage module, an ACM instruction generating transmitter, and an S-band transmitting antenna; The laser receiving antenna receives a downlink laser signal transmitted by a satellite; The laser receiving subsystem receives the signal output by the laser receiving antenna, realizes the detection and photoelectric conversion of the laser signal, and estimates the OSNR in real time; The Ka-band receiving antenna receives a downlink Ka-band microwave signal transmitted by a satellite; The microwave receiving subsystem receives the signal output by the Ka-band receiving antenna, realizes down-conversion and demodulation of the microwave signal, and estimates E in real time. s / N0; The ground data processing and storage module receives the data output by the laser receiving subsystem and the microwave receiving subsystem, implements data frame analysis, channel decoding, and storage, and obtains the transmitted payload data; The ACM instruction generates the signal-to-noise ratio information estimated in real time by the laser receiving subsystem and the microwave receiving subsystem received by the transmitter, and according to the adaptive transmission strategy, the link signal-to-noise ratio estimation result is compared with the preset lookup table to complete the link, information rate and coding modulation mode selection under the current channel state, and then the relevant information is packaged into a transmission mode control instruction; The S-band transmitting antenna is connected to the ACM command generating transmitter, and transmits the signal output by the ACM command generating transmitter to the corresponding satellite; The S-band receiving antenna is used to receive the signal radiated by the S-band transmitting antenna and send the signal to the ACM instruction receiving controller.

5. The laser-microwave hybrid adaptive satellite-to-ground data transmission device according to claim 4, characterized in that: The ACM instruction generation transmitter of the ground device has three sets of lookup tables based on the signal-to-noise ratio estimation results, which are: Laser link signal-to-noise ratio OSNR, microwave link signal-to-noise ratio E s / N0 threshold lookup table; Preset OSNR classification corresponding to different information rate and coding mode combinations; Preset E s / N0 The lookup table corresponding to different information rate and coding modulation mode combinations.

6. The laser-microwave hybrid adaptive satellite-to-ground data transmission device as claimed in claim 4, characterized in that: After the onboard device switches to the laser link or microwave link, the ACM instruction generating transmitter selects the information rate and coding modulation mode according to the following steps: For laser links, the real-time estimated OSNR is compared with the preset OSNR bin lookup table, the information rate and coding method corresponding to the bin range containing the current OSNR estimate are selected, the control command is generated, and it is transmitted to the satellite through the S-band transmitting antenna; For microwave links, the real-time estimated E s / N0 and preset E s / N0 bin lookup table for comparison, select the one containing the current E s The information rate and coding modulation method corresponding to the grading range of the / N0 estimated value generate control instructions and are sent to the satellite through the S-band transmitting antenna.

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