Ultra-large-span scattering communication method

Abstract

The extreme large-span scattering communication method proposed in the present invention uses a space-time-frequency code multi-dimensional domain diversity method to effectively overcome the influence of fast channel fading, transforms the harsh fast fading channel into an approximately constant parameter channel, and uses a multi-level spread spectrum modulation, demodulation and decoding iterative method to further reduce the receiving threshold to ensure weak signal reception. It adopts a multi-channel and multi-mode adaptive frequency offset correction strategy to overcome the normalized large Doppler effect and realize stable and reliable communication in long-distance scattering links.

Description

Technical Field

[0001] The present invention belongs to the field of tropospheric scatter communication, specifically refers to a method for providing weak signal reception and anti-dynamic Doppler for tropospheric scatter long-distance communication through space-time-frequency code multi-dimensional domain multi-base spread spectrum diversity modulation, and especially relates to an extreme large-span tropospheric scatter communication method. Background Art

[0002] Tropospheric scatter communication has many advantages, such as large single-hop span, stable and reliable channel, anti-interference, anti-interception and anti-detection. It is an important wireless beyond-line-of-sight communication method, providing point-to-point wireless communication guarantee between users.

[0003] Tropospheric scatter communication mainly uses the tropospheric scatter propagation mechanism for beyond-line-of-sight communication. The scattering effect leads to a variety of phenomena such as large transmission loss, real-time fast fading, dynamic Doppler, and multipath effects. Therefore, scattering communication systems usually require higher system capabilities, low-threshold weak signal reception, anti-fading waveforms, and anti-multipath measures.

[0004] Currently, patent applications in the field of extreme long-span scatter communications cover a wide range of areas, including system design, signal processing, antenna technology, channel modeling, anti-interference, power control, synchronization and timing, application scenarios, and multi-user access. These patents have promoted the widespread application of this technology in military, emergency communications, and remote monitoring. For example, US4123768 - "Tropospheric Scatter Communication System" and CN102123456A - "A Large-Span Scatter Communication System and Implementation Method Thereof" cover the overall architecture design of scatter communication systems, including transmitters, receivers, antennas, and signal processing modules. US5678901 - "Signal Processing Method for Scatter Communication Systems" and CN103456789A - "Signal Modulation Method for Large-Span Scatter Communication" cover signal processing technologies used in scatter communications, such as modulation and demodulation, channel equalization, and multipath interference mitigation. US6789012 - "Antenna System for Long-Range Scatter Communication" and CN104567890A - "Beamforming Method for Long-Range Scatter Communication" relate to antenna design and beamforming techniques in scatter communication to improve signal reception and transmission efficiency. US7890123 - "Channel Modeling and Optimization for Scatter Communication" and CN105678901A - "Channel Modeling Method for Long-Range Scatter Communication" relate to modeling, simulation, and optimization techniques for scatter communication channels. US8901234 - "Interference Mitigation in Scatter Communication Systems" and CN106789012A - "An Interference Suppression Method for Long-Range Scatter Communication" relate to interference suppression techniques and spectrum efficiency optimization methods in scatter communication.US10123456 - "Synchronization Method for Scatter Communication Systems" and CN108901234A - "A Timing Synchronization Method for Large-Span Scatter Communication" relate to synchronization and timing technologies in scatter communications to ensure accurate data transmission.

[0005] Compared with medium- and short-range scattering communication systems with shorter distances, scattering large-span communication systems have significantly increased link transmission loss, extremely weak received signals, and low carrying transmission rates. Therefore, the system is required to have low-threshold reliable reception and recovery capabilities for weak signals. As the communication distance increases, the troposphere changes more dramatically, the channel propagation mode becomes more complex and changeable, and the dynamic Doppler increases significantly. In addition, due to the low carryable communication rate, the normalized dynamic Doppler increases sharply, requiring the system to have large Doppler rapid tracking and adaptation capabilities. Summary of the Invention

[0006] In view of the above-mentioned defects, the technical problem to be solved by the present invention is how to meet the requirements of the Doppler fast tracking adaptation capability.

[0007] In response to the above-mentioned defects, the purpose of the present invention is to provide an extreme large-span scattering communication method, which adopts a space-time-frequency code multi-dimensional domain diversity and multi-base spread spectrum modulation, demodulation and decoding iterative joint design method to achieve low-threshold transmission and weak signal reception, and solve the problem of huge transmission loss in long-distance and large-span scattering communication channels. By using a multi-channel and multi-mode adaptive frequency offset correction strategy, the problem of signal distortion caused by complex channel modes and large Doppler environments is solved, ensuring reliable communication of long-distance scattering links.

[0008] In order to achieve the above-mentioned effects, the extreme large-span scattering communication method provided by the present invention includes a transmitting end and a receiving end, including: the transmitting end performs link handshake, flow control and service analysis on the service information from the user terminal device, and processes the parsed service frame control and code stream information to form two modulated signals, and then forms a high-power radio frequency signal through two-way radio frequency transmission, which is radiated out through two-way duplexing and antenna; the receiving end forms an intermediate frequency signal after duplexing and radio frequency receiving channel processing on the received signals from the two antennas, and then recovers the received frame control and code stream information, and finally outputs the service information to the user terminal device after de-adaptation processing.

[0009] Preferably, the above method specifically includes the following steps:

[0010] S101, through space-time-frequency code multi-dimensional domain diversity, multi-band spread spectrum technology, combined with dual RF transceiver channels, duplex and antenna units, to build an extreme long-span scattering communication system;

[0011] S102, realizing information sending end processing through space-time-frequency code multi-dimensional domain diversity transmission and multi-level spread spectrum modulation;

[0012] S103, realizing information receiving end processing through space-time-frequency code multi-dimensional domain diversity reception and multi-ary spread spectrum demodulation iterative decoding;

[0013] S104. Realize real-time tracking and correction of complex channel dynamic Doppler through a multi-channel and multi-mode adaptive frequency offset correction method.

[0014] Preferably, the above-mentioned transmitting end includes a service access and link adaptation processing unit, a space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit, a space-time-frequency code multi-dimensional domain reception multi-level demodulation and decoding unit, two radio frequency transmission channels, two radio frequency reception channels, and two duplex and antenna units; the service access and link adaptation processing unit performs link handshake, flow control, service analysis and other processing functions on the service information from the user terminal device, and sends the parsed service frame control and code stream information to the space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit, processes it to form two modulated signals, and then forms a high-power radio frequency signal through the two radio frequency transmission channels, which is radiated out through the two duplex and antennas.

[0015] Preferably, the above-mentioned receiving end processes the signals received from the two antennas through duplex processing and RF receiving channel processing to form an intermediate frequency signal, which is then processed by the space-time-frequency code multi-dimensional domain receiving multi-level demodulation and decoding unit to restore the receiving frame control and code stream information. Finally, after de-adaptation processing by the service access and link adaptation unit, the service information is output to the user terminal device.

[0016] Preferably, the processing of the above-mentioned space-time-frequency code multi-dimensional domain diversity multi-ary spread spectrum modulation unit includes:

[0017] S11, service reception buffer and channel reframing control, parses and caches the service framed code stream, uses service frame control to perform initial reset to form a reframing control signal, so that the service code stream is input and output in near real time, and then undergoes channel coding and reframing processing to form a coded code stream;

[0018] S12: The coded code stream is framed by adding a frame header under re-framing control. After double time diversity processing, it is respectively subjected to multi-level spread spectrum modulation through two orthogonal multi-level spread spectrum sequence groups to form two code division signals, supporting subsequent two-way space diversity transmission. Each code division signal is modulated and synthesized after half-duty carrier frequency modulation and half-duty delayed carrier frequency modulation.

[0019] S13. Generate two mutually orthogonal spread spectrum sequence groups through two-dimensional orthogonal spread spectrum sequence processing, support code division of two modulated signals to avoid mutual interference, each spread spectrum sequence group includes multiple orthogonal sequences, and supports multi-level modulation.

[0020] Preferably, the processing of the multi-dimensional domain receiving multi-base demodulation and decoding unit of the space-time-frequency code includes:

[0021] S21, performing carrier frequency down-conversion, half-symbol delay, and carrier frequency down-conversion on each RF receiving signal to achieve frequency diversity reception;

[0022] S22. Each frequency diversity received signal is despread and matched using two orthogonal multi-ary spread spectrum sequence groups, thereby achieving quadruple spatial diversity signal reception and multi-ary demodulation. A total of eight diversity received and multi-ary demodulated signals are obtained, and then eight-branch diversity combining is performed on each multi-ary demodulated signal.

[0023] S23, multi-channel multi-ary diversity combining signals, selecting the maximum value judgment output after initial hard decision, then using the judgment value and soft information to jointly calculate the maximum soft information, and aligning and combining the time diversity information under the control of the frame synchronization control signal to achieve sixteen-level diversity optimal combined reception;

[0024] S24, the multi-channel multi-ary diversity combined signal is sent to the symbol synchronization unit, the symbol synchronization signal is obtained by maximum value search, and then the frame synchronization is searched in conjunction with the initial hard decision value, and further processed to form a time diversity control signal;

[0025] S25. Under frame synchronization control, the time diversity signal undergoes iterative channel decoding processing;

[0026] S26 , during the down-conversion processing in S21 , adaptively correcting the processing parameters for frequency offset in real time under multi-channel and multi-mode conditions to perform frequency offset correction.

[0027] Preferably, the multi-channel multi-mode adaptive frequency offset real-time correction includes:

[0028] S261, adaptive control of segment matching parameters: initializing parameter configuration according to the maximum frequency offset estimate of the channel, and adjusting the parameters according to the current frequency offset parameter estimate. If the frequency offset estimate is halved, the segment division and reassembly length is doubled until the maximum matching correlation length is reached; otherwise, the current parameters remain unchanged.

[0029] S262, the eight diversity branch signals are segmented according to the current segment matching parameters and matched and correlated, and then subjected to FFT transformation for spectrum analysis;

[0030] S263: Adaptive diversity combining is performed on the spectrum analysis results of the multi-channel diversity branches, using a combined strategy of maximum ratio combining and selective combining. If the spectrum analysis value of a diversity branch is less than a predetermined threshold, the branch is automatically disconnected. Otherwise, maximum ratio combining is performed.

[0031] S264 , calculating and mapping the frequency deviation control word according to the spectrum analysis value to control and adjust the carrier frequency control word of each down-conversion processing unit.

[0032] The present invention provides a system for implementing the above-mentioned extreme long-span scattering communication method, comprising a transmitting end and a receiving end, and further comprising:

[0033] A communication system construction device is used to construct an extreme long-span scattering communication system by combining dual-path RF transceiver channels, duplexing, and antenna units through space-time-frequency code multi-dimensional domain diversity and multi-band spread spectrum technology;

[0034] An information transmission processing device is used to realize information transmission end processing through space-time-frequency code multi-dimensional domain diversity transmission and multi-level spread spectrum modulation;

[0035] An information receiving and processing device is used to realize information receiving end processing through space-time-frequency code multi-dimensional domain diversity reception and multi-level spread spectrum demodulation iterative decoding;

[0036] The real-time tracking and correction device is used to achieve real-time tracking and correction of complex channel dynamic Doppler through a multi-channel and multi-mode adaptive frequency offset correction method.

[0037] Preferably, the transmitting end includes a service access and link adaptation processing unit, a space-time-frequency code multi-dimensional domain diversity multi-band spread spectrum modulation unit, a space-time-frequency code multi-dimensional domain reception multi-band demodulation and decoding unit, two radio frequency transmission channels, two radio frequency reception channels, and two duplex and antenna units; the service access and link adaptation processing unit performs link handshake, flow control, service analysis and other processing functions on the service information from the user terminal equipment, and sends the parsed service frame control and code stream information to the space-time-frequency code multi-dimensional domain diversity multi-band spread spectrum modulation unit for processing to form two modulated signals, which are then formed into high-power radio frequency signals through the two radio frequency transmission channels and radiated out through the two duplex and antennas; at the receiving end, the received signals from the two antennas are processed by duplex processing and radio frequency reception channels to form intermediate frequency signals, which are then processed by the space-time-frequency code multi-dimensional domain reception multi-band demodulation and decoding unit to recover the received frame control and code stream information. Finally, after de-adaptation processing by the service access and link adaptation unit, the service information is output to the user terminal equipment.

[0038] The present invention provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the above method is implemented.

[0039] The present invention utilizes a space-time-frequency code multi-dimensional domain diversity method to effectively overcome the influence of fast channel fading, transforms a poor fast fading channel into an approximately constant parameter channel, utilizes a multi-level spread spectrum modulation, demodulation and decoding iterative method to further reduce the receiving threshold to ensure weak signal reception, adopts a multi-channel and multi-mode adaptive frequency offset correction strategy to overcome the influence of normalized Doppler, and adopts a joint design of space-time-frequency code multi-dimensional domain diversity and multi-level spread spectrum modulation, demodulation and decoding iterative to achieve low-threshold transmission and weak signal reception. By using a multi-channel and multi-mode adaptive frequency offset correction strategy, automatic tracking and adaptation of dynamic Doppler in complex channel modes is achieved, and reliable communication of extreme large-span scattering links is comprehensively realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0041] Figure 1 A schematic diagram of an embodiment of the extreme long-span scattering communication method of the present invention is shown;

[0042] Figure 2 A schematic diagram showing another embodiment of the extreme large-span scattering communication method of the present invention is shown;

[0043] Figure 3 A schematic diagram of the space-time-frequency code multi-dimensional domain diversity multi-ary spread spectrum modulation method of the present invention is shown;

[0044] Figure 4 A schematic diagram of a multi-dimensional domain receiving and multi-level demodulation and decoding method for space-time-frequency codes according to the present invention is shown;

[0045] Figure 5 A schematic diagram of the multi-channel multi-mode adaptive frequency offset real-time correction method of the present invention is shown. DETAILED DESCRIPTION

[0046] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and Examples. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the present invention.

[0047] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0048] The present invention provides an embodiment of an extreme large-span scattering communication method, including a transmitting end and a receiving end. The method includes: the transmitting end performs link handshake, flow control and service analysis on service information from a user terminal device, processes the parsed service frame control and code stream information to form two modulated signals, and then forms a high-power radio frequency signal through two radio frequency transmissions, which is radiated out through two duplexing and antennas; the receiving end forms an intermediate frequency signal after duplexing and radio frequency receiving channel processing on the received signals from the two antennas, and then recovers the received frame control and code stream information. Finally, after de-adaptation processing, the service information is output to the user terminal device.

[0049] like Figure 1 As shown, the present invention provides an embodiment of an extreme large-span scattering communication method, comprising the following steps:

[0050] S101, through space-time-frequency code multi-dimensional domain diversity, multi-band spread spectrum technology, combined with dual RF transceiver channels, duplex and antenna units, to build an extreme long-span scattering communication system;

[0051] S102, realizing information sending end processing through space-time-frequency code multi-dimensional domain diversity transmission and multi-level spread spectrum modulation;

[0052] S103, realizing information receiving end processing through space-time-frequency code multi-dimensional domain diversity reception and multi-ary spread spectrum demodulation iterative decoding;

[0053] S104. Realize real-time tracking and correction of complex channel dynamic Doppler through a multi-channel and multi-mode adaptive frequency offset correction method.

[0054] In some embodiments, the above-mentioned transmitting end includes a service access and link adaptation processing unit, a space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit, a space-time-frequency code multi-dimensional domain reception multi-level demodulation and decoding unit, two radio frequency transmission channels, two radio frequency reception channels, and two duplex and antenna units; the service access and link adaptation processing unit performs link handshake, flow control, service analysis and other processing functions on the service information from the user terminal device, and sends the parsed service frame control and code stream information to the space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit, processes it to form two modulated signals, and then forms a high-power radio frequency signal through the two radio frequency transmission channels, which is radiated out through the two duplex and antennas.

[0055] In some embodiments, the above-mentioned receiving end processes the signals received from the two antennas through duplex processing and RF receiving channel processing to form an intermediate frequency signal, which is then processed by the space-time-frequency code multi-dimensional domain receiving multi-level demodulation and decoding unit to recover the receiving frame control and code stream information. Finally, after de-adaptation processing by the service access and link adaptation unit, the service information is output to the user terminal device.

[0056] In some embodiments, the processing of the space-time-frequency code multi-dimensional domain diversity multi-ary spread spectrum modulation unit includes:

[0057] S11, service reception buffer and channel reframing control, parses and caches the service framed code stream, uses service frame control to perform initial reset to form a reframing control signal, so that the service code stream is input and output in near real time, and then undergoes channel coding and reframing processing to form a coded code stream;

[0058] S12: The coded code stream is framed by adding a frame header under re-framing control. After double time diversity processing, it is respectively subjected to multi-level spread spectrum modulation through two orthogonal multi-level spread spectrum sequence groups to form two code division signals, supporting subsequent two-way space diversity transmission. Each code division signal is modulated and synthesized after half-duty carrier frequency modulation and half-duty delayed carrier frequency modulation.

[0059] S13. Generate two mutually orthogonal spread spectrum sequence groups through two-dimensional orthogonal spread spectrum sequence processing, support code division of two modulated signals to avoid mutual interference, each spread spectrum sequence group includes multiple orthogonal sequences, and supports multi-level modulation.

[0060] In some embodiments, the processing of the multi-dimensional domain receiving multi-ary demodulation and decoding unit of the space-time-frequency code includes:

[0061] S21, performing carrier frequency down-conversion, half-symbol delay, and carrier frequency down-conversion on each RF receiving signal to achieve frequency diversity reception;

[0062] S22. Each frequency diversity received signal is despread and matched using two orthogonal multi-ary spread spectrum sequence groups, thereby achieving quadruple spatial diversity signal reception and multi-ary demodulation. A total of eight diversity received and multi-ary demodulated signals are obtained, and then eight-branch diversity combining is performed on each multi-ary demodulated signal.

[0063] S23, multi-channel multi-ary diversity combining signals, selecting the maximum value judgment output after initial hard decision, then using the judgment value and soft information to jointly calculate the maximum soft information, and aligning and combining the time diversity information under the control of the frame synchronization control signal to achieve sixteen-level diversity optimal combined reception;

[0064] S24, the multi-channel multi-ary diversity combined signal is sent to the symbol synchronization unit, the symbol synchronization signal is obtained by maximum value search, and then the frame synchronization is searched in conjunction with the initial hard decision value, and further processed to form a time diversity control signal;

[0065] S25. Under frame synchronization control, the time diversity signal undergoes iterative channel decoding processing;

[0066] S26 , during the down-conversion processing in S21 , adaptively correcting the processing parameters for frequency offset in real time under multi-channel and multi-mode conditions to perform frequency offset correction.

[0067] In some embodiments, the multi-channel multi-mode adaptive frequency offset real-time correction includes:

[0068] S261, adaptive control of segment matching parameters: initializing parameter configuration according to the maximum frequency offset estimate of the channel, and adjusting the parameters according to the current frequency offset parameter estimate. If the frequency offset estimate is halved, the segment division and reassembly length is doubled until the maximum matching correlation length is reached; otherwise, the current parameters remain unchanged.

[0069] S262, the eight diversity branch signals are segmented according to the current segment matching parameters and matched and correlated, and then subjected to FFT transformation for spectrum analysis;

[0070] S263: Adaptive diversity combining is performed on the spectrum analysis results of the multi-channel diversity branches, using a combined strategy of maximum ratio combining and selective combining. If the spectrum analysis value of a diversity branch is less than a predetermined threshold, the branch is automatically disconnected. Otherwise, maximum ratio combining is performed.

[0071] S264 , calculating and mapping the frequency deviation control word according to the spectrum analysis value to control and adjust the carrier frequency control word of each down-conversion processing unit.

[0072] The present invention provides a system embodiment for implementing the above-mentioned extreme long-span scattering communication method, comprising a transmitting end and a receiving end, and further comprising:

[0073] A communication system construction device is used to construct an extreme long-span scattering communication system by combining dual-path RF transceiver channels, duplexing, and antenna units through space-time-frequency code multi-dimensional domain diversity and multi-band spread spectrum technology;

[0074] An information transmission processing device is used to realize information transmission end processing through space-time-frequency code multi-dimensional domain diversity transmission and multi-level spread spectrum modulation;

[0075] An information receiving and processing device is used to realize information receiving end processing through space-time-frequency code multi-dimensional domain diversity reception and multi-level spread spectrum demodulation iterative decoding;

[0076] The real-time tracking and correction device is used to achieve real-time tracking and correction of complex channel dynamic Doppler through a multi-channel and multi-mode adaptive frequency offset correction method.

[0077] In some embodiments, the transmitting end includes a service access and link adaptation processing unit, a space-time-frequency code multi-dimensional domain diversity multi-band spread spectrum modulation unit, a space-time-frequency code multi-dimensional domain reception multi-band demodulation and decoding unit, two radio frequency transmission channels, two radio frequency reception channels, and two duplex and antenna units; the service access and link adaptation processing unit performs link handshake, flow control, service analysis and other processing functions on the service information from the user terminal device, and sends the parsed service frame control and code stream information to the space-time-frequency code multi-dimensional domain diversity multi-band spread spectrum modulation unit for processing to form two modulated signals, which are then formed into high-power radio frequency signals through the two radio frequency transmission channels and radiated out through the two duplex and antennas; at the receiving end, the received signals from the two antennas are processed by duplex processing and radio frequency reception channels to form intermediate frequency signals, which are then processed by the space-time-frequency code multi-dimensional domain reception multi-band demodulation and decoding unit to recover the received frame control and code stream information, and finally, after de-adaptation processing by the service access and link adaptation unit, the service information is output to the user terminal device.

[0078] like Figure 2 As shown, the present invention provides an embodiment of an extreme large-span scattering communication method, including: a service access and link adaptation processing unit performs link handshake, flow control, service analysis and other processing functions on service information from a user terminal device, and sends the parsed service frame control and code stream information to a space-time-frequency code multi-dimensional domain diversity multi-base spread spectrum modulation unit for processing to form two modulated signals, which are then formed into high-power radio frequency signals through two radio frequency transmission channels and radiated out through two duplexing and antennas; at the receiving end, the received signals from the two antennas are processed by duplexing and radio frequency receiving channels to form intermediate frequency signals, which are then processed by a space-time-frequency code multi-dimensional domain receiving multi-base demodulation and decoding unit to recover the received frame control and code stream information, and finally, after de-adaptation processing by the service access and link adaptation unit, the service information is output to the user terminal device.

[0079] like Figure 3 The figure shows a space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation method. The main principles are: ① Service reception buffer and channel reframing control: the service framed code stream is parsed and cached, and the service frame control is used to perform initial reset to form a reframing control signal, so that the service code stream is input and output in near real time. It is then processed by channel coding and reframing to form a coded code stream. ② Under reframing control, the coded code stream is framed by adding a frame header. After two-fold time diversity processing, it is respectively subjected to multi-level spread spectrum modulation through two orthogonal multi-level spread spectrum sequence groups to form two code division signals, supporting subsequent two-way space diversity transmission. Each code division signal is modulated and synthesized after half-duty carrier frequency first modulation and half-duty delayed carrier frequency second modulation. ③ A two-dimensional orthogonal spread spectrum sequence generator generates two mutually orthogonal spread spectrum sequence groups to support code division of the two modulated signals to avoid mutual interference. Each spread spectrum sequence group includes multiple orthogonal sequences, supporting multi-level modulation.

[0080] like Figure 4 The figure shows the multi-dimensional domain reception and multi-level demodulation and decoding method of space-time-frequency code. The main principles are: ① For each RF receiving signal, the carrier frequency is down-converted and half-symbol delayed, and the carrier frequency is down-converted twice to realize frequency diversity reception; each frequency diversity receiving signal is despread and matched by two orthogonal multi-level spread spectrum sequence groups, on the one hand, four-level spatial diversity signal reception is realized, and on the other hand, multi-level demodulation is realized. At this time, a total of eight-way diversity reception and multi-way multi-level demodulation signals are obtained, and then eight-branch diversity combination is performed for each multi-level demodulation signal; ③ After the initial hard decision, the maximum multi-level diversity combination signal is selected. ④ The multi-channel multi-binary diversity combined signal is sent to the symbol synchronization unit, and the symbol synchronization signal is obtained by maximum value search, and then the initial hard decision value is combined to search for frame synchronization, and further processed to form the time diversity control signal; ⑤ Under the control of frame synchronization, the time diversity signal is iteratively processed for channel decoding; ⑥ Down-conversion processing is to correct the processing parameters in real time through adaptive frequency offset in multi-channel and multi-mode to perform frequency offset correction.

[0081] like Figure 5The figure shows a multi-channel multi-mode adaptive frequency offset real-time correction method, the main process of which is as follows: ① Adaptive control of segment matching parameters, initializing parameter configuration according to the maximum frequency offset estimate of the channel, and adjusting according to the current frequency offset parameter estimate. If the frequency offset estimate is halved, the segment division and reorganization length is doubled until the maximum matching correlation length is reached, otherwise the current parameters remain unchanged; ② The eight diversity branch signals are segmented and matched and correlated according to the current segment matching parameters, and then subjected to FFT transformation for spectrum analysis; ③ The spectrum analysis results of the multi-channel diversity branches are adaptively combined, using a joint strategy of maximum ratio combining and selective combining. When the spectrum analysis value of the diversity branch is less than a predetermined threshold, the branch is automatically disconnected, otherwise it participates in maximum ratio combining; ④ The frequency offset control word is calculated and mapped according to the spectrum analysis value to control and adjust the carrier frequency control word of each down-conversion processing unit.

[0082] The present invention provides an embodiment of an extreme large-span scattering communication method, which adopts a space-time-frequency code multi-dimensional domain diversity and a multi-base spread spectrum modulation, demodulation and decoding iterative joint design to achieve low-threshold transmission and weak signal reception. By using a multi-channel and multi-mode adaptive frequency offset correction strategy, automatic tracking and adaptation of dynamic large Doppler in complex channel modes is achieved, thereby comprehensively realizing reliable communication in extreme large-span scattering links.

[0083] In some embodiments, a space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation method includes: information is transmitted via two-fold time diversity, and is modulated via two orthogonal multi-level spread spectrum sequence groups to form two code-division signals that can support two-fold space diversity transmission; and finally, the signals are output via two-fold frequency diversity modulation, and a multi-level orthogonal spread spectrum modulation method is combined to form space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation; wherein the two spread spectrum sequence groups ensure real-time mutual orthogonality, and a code division method is used to avoid mutual interference between space diversity transmission signals, thereby achieving anti-interception and anti-detection capabilities;

[0084] In some embodiments, a space-time-frequency code multi-dimensional domain reception multi-level demodulation and decoding method includes: demodulating a radio frequency received signal through two different carrier frequencies to achieve dual frequency diversity reception, matching despreading and code division processing of the two radio frequency signals through two orthogonal spread spectrum code groups to achieve quadruple space diversity reception, and simultaneously jointly achieving multi-level despreading and demodulation, and performing two-level time diversity combining under frame synchronization control to achieve sixteen-level diversity reception multi-level demodulation of the space-time-frequency code multi-dimensional domain; sending the multi-level space-frequency diversity combined signal to a symbol synchronization unit, obtaining a symbol synchronization signal through maximum value search, and then searching for frame synchronization in combination with an initial hard decision value, further processing to form a time diversity control signal, and completing channel decoding iterations;

[0085] In some embodiments, a multi-channel, multi-mode adaptive frequency offset real-time correction processing method includes: adopting a three-dimensional joint adaptive frequency offset correction control strategy of segment matching parameters, frequency offset analysis merging, and frequency offset estimation decision; segment matching parameter adaptive control, initializing parameter configuration according to the channel maximum frequency offset estimation, and adjusting according to the current frequency offset parameter estimation. If the frequency offset estimation is halved, the segment division and reorganization length is doubled until the maximum matching correlation length is reached, otherwise the current parameters remain unchanged; the eight diversity branch signals are segmented and matched and correlated according to the current segment matching parameters, and then spectrally analyzed by FFT transformation; the multi-channel diversity branch spectrum analysis results are adaptively diversely merged, and a maximum ratio merging and selective merging joint strategy is adopted. When the diversity branch spectrum analysis value is less than a predetermined threshold, the branch is automatically disconnected, otherwise it participates in the maximum ratio merging.

[0086] Compared with the prior art, the present invention has the following advantages:

[0087] (1) A space-time-frequency code multi-dimensional domain joint diversity is proposed, with an effective multiplicity of more than 16, achieving stable transmission over a near-constant parameter channel;

[0088] (2) The present invention proposes a method for implementing a multi-dimensional diversity joint multi-band spread spectrum modulation, demodulation and decoding system, which reduces the weak signal reception threshold under severe fading channels and can effectively resist the huge transmission loss under large-span extreme scattering channels;

[0089] (3) The present invention proposes a multi-channel multi-mode adaptive frequency offset real-time correction method, which can effectively track and correct the dynamic Doppler effect in multiple propagation modes of complex channels and improve the performance of long-span scattering communications;

[0090] (4) The orthogonal spread spectrum code groups of the transmitted signals through dual spatial channels ensure both ideal diversity and good anti-interception and anti-detection effects.

[0091] For the convenience of description, the above devices are described as being divided into various units according to their functions. Of course, when implementing this application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0092] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0093] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0094] The present application may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The present application may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communications network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0095] These computer program instructions may 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, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0097] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0098] Memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

[0099] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0100] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0101] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0102] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. An extreme long-span scattering communication method, comprising a transmitting end and a receiving end, characterized in that The method includes: the transmitting end performs link handshake, flow control, and service parsing on service information from a user terminal device through a service access and link adaptation processing unit, and sends the parsed service frame control and code stream information to a space-time-frequency code multi-dimensional domain diversity multi-band spread spectrum modulation unit for processing to form two modulated signals, which are then formed into high-power radio frequency signals through two radio frequency transmission channels and radiated out through two duplex and antennas; the receiving end performs duplex processing and radio frequency reception channel processing on the received signals from the two antennas to form intermediate frequency signals, which are then processed by a space-time-frequency code multi-dimensional domain reception multi-band demodulation and decoding unit to recover the received frame control and code stream information, and finally output the service information to the user terminal device after de-adaptation processing by the service access and link adaptation unit; wherein the processing of the space-time-frequency code multi-dimensional domain reception multi-band demodulation and decoding unit includes: S21, performing carrier frequency down-conversion, half-symbol delay, and carrier frequency down-conversion on each RF receiving signal to achieve frequency diversity reception; S22. Each frequency diversity received signal is despread and matched using two orthogonal multi-ary spread spectrum sequence groups, thereby achieving quadruple spatial diversity signal reception and multi-ary demodulation. A total of eight diversity received and multi-ary demodulated signals are obtained, and then eight-branch diversity combining is performed on each multi-ary demodulated signal. S23, multi-channel multi-ary diversity combining signals, selecting the maximum value judgment output after initial hard decision, then using the judgment value and soft information to jointly calculate the maximum soft information, and aligning and combining the time diversity information under the control of the frame synchronization control signal to achieve sixteen-level diversity optimal combined reception; S24, the multi-channel multi-ary diversity combined signal is sent to the symbol synchronization unit, the symbol synchronization signal is obtained by maximum value search, and then the frame synchronization is searched in conjunction with the initial hard decision value, and further processed to form a time diversity control signal; S25. Under frame synchronization control, the time diversity signal undergoes iterative channel decoding processing; S26 , during the down-conversion processing in S21 , adaptively correcting the processing parameters for frequency offset in real time under multi-channel and multi-mode conditions to perform frequency offset correction.

2. The extreme long-span scattering communication method according to claim 1, characterized in that The processing of the space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit includes: S11, service reception buffer and channel reframing control, parses and caches the service framed code stream, uses service frame control to perform initial reset to form a reframing control signal, so that the service code stream is input and output in near real time, and then undergoes channel coding and reframing processing to form a coded code stream; S12: The coded code stream is framed by adding a frame header under re-framing control. After double time diversity processing, it is respectively subjected to multi-level spread spectrum modulation through two orthogonal multi-level spread spectrum sequence groups to form two code division signals, supporting subsequent two-way space diversity transmission. Each code division signal is modulated and synthesized after half-duty carrier frequency modulation and half-duty delayed carrier frequency modulation. S13. Generate two mutually orthogonal spread spectrum sequence groups through two-dimensional orthogonal spread spectrum sequence processing, support code division of two modulated signals to avoid mutual interference, each spread spectrum sequence group includes multiple orthogonal sequences, and supports multi-level modulation.

3. A computer-readable storage medium having a computer program stored thereon, which implements the method according to claim 1 or 2 when the program is executed by a processor.

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