Extreme large-span scatter communication method

Abstract

According to the extreme large-span scatter communication method provided by the invention, the influence of fast fading of a channel is effectively overcome by utilizing a space-time-frequency code multi-dimensional domain diversity mode, a severe fast fading channel is transformed into an approximate constant-parameter channel, and a receiving threshold is further reduced to guarantee weak signal receiving by utilizing a multi-system spread spectrum modulation-demodulation decoding iteration mode; a multi-channel multi-mode self-adaptive frequency offset correction strategy is adopted, the influence of normalized large Doppler is overcome, and stable and reliable communication of a long-distance scattering link is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of tropospheric scatter communication, and specifically refers to a method for providing weak signal reception and dynamic Doppler resistance for scattering long-distance communication through space-time-frequency code multi-dimensional domain multi-level spread spectrum diversity modulation, and more particularly relates to an extreme large-span scattering 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 to carry out 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] At present, patent applications in the field of extreme long-span scattering communication cover many aspects, 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 communication, and remote monitoring. For example, US4123768 - "Tropospheric Scatter Communication System" (Tropospheric Scatter Communication System); CN102123456A - "A large-span scattering communication system and its implementation method" (Large-span scattering communication system and implementation method) involves the overall architecture design of the scattering communication system, including a transmitter, a receiver, an antenna, and a signal processing module. US5678901 - "SignalProcessing Method for Scatter Communication Systems" (Signal Processing Method for Scatter Communication Systems); CN103456789A - "A signal modulation method for large-span scattering communication" (Signal modulation method for large-span scattering communication) involves signal processing technology in scattering communication, such as modulation and demodulation, channel equalization, and anti-multipath interference. US6789012 - "Antenna System for Long-Range Scatter Communication" (Long-Range Scatter Communication Antenna System); CN104567890A - "A Beamforming Method for Long-Range Scatter Communication" (Long-Range Scatter Communication Beamforming Method) relates to antenna design and beamforming technology in scatter communication to improve signal reception and transmission efficiency. US7890123 - "Channel Modeling and Optimization for Scatter Communication" (Channel Modeling and Optimization for Scatter Communication); CN105678901A - "A Channel Modeling Method for Long-Range Scatter Communication" (Long-Range Scatter Communication Channel Modeling Method) relates to modeling, simulation and optimization technology of scatter communication channels. US8901234 - "Interference Mitigation in Scatter Communication Systems" (Interference Suppression in Scatter Communication Systems); CN106789012A - "An Anti-interference Method for Long-Range Scatter Communication" (Anti-interference Method for Long-Range Scatter Communication) relates to anti-interference technology and spectrum efficiency optimization methods in scatter communication.US10123456 - "Synchronization Method for Scatter Communication Systems" (Synchronization Method for Scatter Communication Systems); CN108901234A - "A Timing Synchronization Method for Large Span Scatter Communication" (Timing Synchronization Method for Large Span Scatter Communication) relates to synchronization and timing technology in scatter communication to ensure the accuracy of data transmission.

[0005] Compared with the short- and medium-range scattering communication systems with shorter distances, the link transmission loss of the scattering large-span communication system is significantly increased, the received signal is extremely weak, and the transmission rate is low. The system is required to have the ability to reliably receive and recover weak signals with a low threshold. As the communication distance increases, the troposphere changes more dramatically, the channel propagation mode becomes more complex and changeable, the dynamic Doppler increases significantly, and due to the low carryable communication rate, the normalized dynamic Doppler increases sharply, requiring the system to have a large Doppler rapid tracking and adaptation capability. 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 view of 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-level 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, thereby ensuring reliable communication of long-distance scattering links.

[0008] In order to achieve the above-mentioned effect, the extreme large-span scattering communication method provided by the present invention includes a transmitting end and a receiving end, including: the transmitting end service performs link handshake, flow control and service analysis on the service information from the user terminal device, and processes the service frame control and code stream information after analysis to form two-way modulated signals, and then forms a high-power radio frequency signal through two-way radio frequency transmission, which is radiated through two-way duplex and antenna; the receiving end forms an intermediate frequency signal after duplex processing and radio frequency receiving channel processing of 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 comprises the following steps: S101, through the space-time-frequency code multi-dimensional domain diversity, multi-level spread spectrum technology, combined with dual-channel RF transceiver channels, duplex and antenna units, to build an extreme long-span scattering communication system; S102, realizing information sending end processing through space-time-frequency code multi-dimensional domain diversity transmission and multi-level spread spectrum modulation; S103, realizing information receiving end processing through space-time-frequency code multi-dimensional domain diversity reception and multi-level spread spectrum demodulation iterative decoding method; S104. Realize real-time tracking and correction of complex channel dynamic Doppler through a multi-channel and multi-mode adaptive frequency offset correction method.

[0010] 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 two radio frequency transmission channels, which is radiated through two duplex and antennas.

[0011] Preferably, the above-mentioned receiving end processes the received signals 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, and finally outputs the service information to the user terminal device after de-adaptation processing by the service access and link adaptation unit.

[0012] Preferably, the processing of the above-mentioned space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit includes: S11, service receiving buffer and channel reframing control, analyze and buffer the service framing code stream, use 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 forms a coded code stream through channel coding and reframing processing; S12, the coded code stream is framed by adding a frame header under the re-framing control, and after double time diversity processing, two orthogonal multi-level spread spectrum sequence groups are used to complete multi-level spread spectrum modulation to form two code division signals, supporting subsequent two-way space diversity transmission, and each code division signal is modulated and synthesized after half-duty carrier frequency one modulation and half-duty delayed carrier frequency two modulation processing; S13. Generate two mutually orthogonal spread spectrum sequence groups through two-dimensional orthogonal spread spectrum sequence processing, support code division of two-way modulated signals to avoid mutual interference, each spread spectrum sequence group includes multiple orthogonal sequences, and supports multi-level modulation.

[0013] Preferably, the processing of the multi-dimensional domain receiving multi-level demodulation and decoding unit of the space-time-frequency code includes: S21, performing carrier frequency down-conversion and half-symbol delay and carrier frequency down-conversion processing on each RF receiving signal to achieve frequency diversity reception; S22, each frequency diversity reception signal is despread and matched through two orthogonal multi-level spread spectrum sequence groups, so as to realize quadruple spatial diversity signal reception and multi-level demodulation, thereby obtaining eight-way diversity reception and multi-way multi-level demodulation signals, and then performing eight-branch diversity combination for each multi-level demodulation signal; S23, multi-channel multi-level diversity combined signal, after initial hard decision, select the maximum value decision output, then use the decision value and soft information to jointly calculate the maximum value soft information, and align and combine 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-level 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 performs channel decoding iterative processing; S26, during the down-conversion processing in S21, adaptive frequency deviation real-time correction processing parameters are performed in multi-channel and multi-mode to perform frequency deviation correction.

[0014] Preferably, the multi-channel multi-mode adaptive frequency offset real-time correction comprises: S261, segment matching parameter adaptive control, initializing parameter configuration according to the maximum frequency offset estimation of the channel, adjusting according to the current frequency offset parameter estimation, if the frequency offset estimation is reduced by one time, the segment division and reorganization length is doubled until the maximum matching correlation length is reached, otherwise the current parameters are kept unchanged; S262, the eight diversity branch signals are segmented and matched according to the current segment matching parameters, and then the signals are subjected to FFT transformation for spectrum analysis; S263, adaptive diversity combining is performed on the spectrum analysis results of the multi-channel diversity branches, and a maximum ratio combining and selective combining strategy is adopted. When the spectrum analysis value of the diversity branch is less than a predetermined threshold, the branch is automatically disconnected, otherwise, the maximum ratio combining is performed; 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.

[0015] The present invention provides a system for implementing the above-mentioned extreme large-span scattering communication method, comprising a transmitting end and a receiving end, and further comprising: A communication system construction device is used to construct an extreme large-span scattering communication system by combining dual-path radio frequency transceiver channels, duplex and antenna units through space-time-frequency code multi-dimensional domain diversity and multi-level spread spectrum technology; 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; 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 mode; The real-time tracking and correction device is used to realize the real-time tracking and correction of the dynamic Doppler of the complex channel through a multi-channel and multi-mode adaptive frequency offset correction method.

[0016] 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 receiving multi-level demodulation and decoding unit, two radio frequency transmission channels, two radio frequency receiving 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-level spread spectrum modulation unit, processes to form two modulated signals, and then forms high-power radio frequency signals through two radio frequency transmission channels, and radiates through two duplex and antennas; at the receiving end, the received signals from the two antennas are processed by duplex processing and radio frequency receiving channel to form intermediate frequency signals, and then processed by the space-time-frequency code multi-dimensional domain receiving multi-level demodulation and decoding unit to restore the received frame control and code stream information, and finally output the service information to the user terminal equipment after de-adaptation processing by the service access and link adaptation unit.

[0017] 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.

[0018] The present invention utilizes space-time-frequency code multi-dimensional domain diversity to effectively overcome the influence of fast channel fading, transforms the bad fast fading channel into an approximately constant parameter channel, utilizes multi-level spread spectrum modulation, demodulation and decoding iteration 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 large Doppler, and adopts space-time-frequency code multi-dimensional domain diversity and multi-level spread spectrum modulation, demodulation and decoding iteration to jointly 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, and reliable communication of extreme large-span scattering links is comprehensively realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following briefly introduces the drawings required for use in the embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A schematic diagram of an embodiment of the extreme large span scattering communication method of the present invention is shown; Figure 2 A schematic diagram showing another embodiment of the extreme large span scattering communication method of the present invention is shown; Figure 3 A schematic diagram of a space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation method according to the present invention is shown; Figure 4 A schematic diagram of a multi-dimensional domain receiving multi-level demodulation and decoding method of a space-time-frequency code according to the present invention is shown; Figure 5 A schematic diagram of the multi-channel multi-mode adaptive frequency deviation real-time correction method of the present invention is shown. DETAILED DESCRIPTION

[0021] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the purpose, technical solutions and advantages of the present invention clearer, 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 only to provide a better understanding of the present invention by illustrating examples of the present invention.

[0022] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0023] The present invention provides an embodiment of an extreme large-span scattering communication method, including a transmitting end and a receiving end, and the method includes: the transmitting end performs link handshake, flow control and service analysis on the service information from the user terminal equipment, processes the service frame control and code stream information after analysis to form two-way modulation signals, and then forms a high-power radio frequency signal through two-way radio frequency transmission, which is radiated through two-way duplex and antenna; the receiving end forms an intermediate frequency signal after duplex processing and radio frequency receiving channel processing of 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 equipment after de-adaptation processing.

[0024] like Figure 1 As shown, the present invention provides an embodiment of an extreme large span scattering communication method, comprising the following steps: S101, through the space-time-frequency code multi-dimensional domain diversity, multi-level spread spectrum technology, combined with dual-channel RF transceiver channels, duplex and antenna units, to build an extreme long-span scattering communication system; S102, realizing information sending end processing through space-time-frequency code multi-dimensional domain diversity transmission and multi-level spread spectrum modulation; S103, realizing information receiving end processing through space-time-frequency code multi-dimensional domain diversity reception and multi-level spread spectrum demodulation iterative decoding method; S104. Realize real-time tracking and correction of complex channel dynamic Doppler through a multi-channel and multi-mode adaptive frequency offset correction method.

[0025] 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 two radio frequency transmission channels, which is radiated through two duplex and antennas.

[0026] In some embodiments, the above-mentioned receiving end processes the received signals 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 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 device.

[0027] In some embodiments, the processing of the above-mentioned space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit includes: S11, service receiving buffer and channel reframing control, analyze and buffer the service framing code stream, use 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 forms a coded code stream through channel coding and reframing processing; S12, the coded code stream is framed by adding a frame header under the re-framing control, and after double time diversity processing, two orthogonal multi-level spread spectrum sequence groups are used to complete multi-level spread spectrum modulation to form two code division signals, supporting subsequent two-way space diversity transmission, and each code division signal is modulated and synthesized after half-duty carrier frequency one modulation and half-duty delayed carrier frequency two modulation processing; S13. Generate two mutually orthogonal spread spectrum sequence groups through two-dimensional orthogonal spread spectrum sequence processing, support code division of two-way modulated signals to avoid mutual interference, each spread spectrum sequence group includes multiple orthogonal sequences, and supports multi-level modulation.

[0028] In some embodiments, the processing of the multi-dimensional domain receiving multi-level demodulation and decoding unit of the space-time-frequency code includes: S21, performing carrier frequency down-conversion and half-symbol delay and carrier frequency down-conversion processing on each RF receiving signal to achieve frequency diversity reception; S22, each frequency diversity reception signal is despread and matched through two orthogonal multi-level spread spectrum sequence groups, so as to realize quadruple spatial diversity signal reception and multi-level demodulation, thereby obtaining eight-way diversity reception and multi-way multi-level demodulation signals, and then performing eight-branch diversity combination for each multi-level demodulation signal; S23, multi-channel multi-level diversity combined signal, after initial hard decision, select the maximum value decision output, then use the decision value and soft information to jointly calculate the maximum value soft information, and align and combine 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-level 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 performs channel decoding iterative processing; S26, during the down-conversion processing in S21, adaptive frequency deviation real-time correction processing parameters are performed in multi-channel and multi-mode to perform frequency deviation correction.

[0029] In some embodiments, the multi-channel multi-mode adaptive frequency offset real-time correction includes: S261, segment matching parameter adaptive control, initializing parameter configuration according to the maximum frequency offset estimation of the channel, adjusting according to the current frequency offset parameter estimation, if the frequency offset estimation is reduced by one time, the segment division and reorganization length is doubled until the maximum matching correlation length is reached, otherwise the current parameters are kept unchanged; S262, the eight diversity branch signals are segmented and matched according to the current segment matching parameters, and then the signals are subjected to FFT transformation for spectrum analysis; S263, adaptive diversity combining is performed on the spectrum analysis results of the multi-channel diversity branches, and a maximum ratio combining and selective combining strategy is adopted. When the spectrum analysis value of the diversity branch is less than a predetermined threshold, the branch is automatically disconnected, otherwise, the maximum ratio combining is performed; 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.

[0030] The present invention provides a system embodiment for implementing the above-mentioned extreme large-span scattering communication method, comprising a transmitting end and a receiving end, and further comprising: A communication system construction device is used to construct an extreme large-span scattering communication system by combining dual-path radio frequency transceiver channels, duplex and antenna units through space-time-frequency code multi-dimensional domain diversity and multi-level spread spectrum technology; 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; 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 mode; The real-time tracking and correction device is used to realize the real-time tracking and correction of the dynamic Doppler of the complex channel through a multi-channel and multi-mode adaptive frequency offset correction method.

[0031] 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-level spread spectrum modulation unit, a space-time-frequency code multi-dimensional domain receiving multi-level demodulation and decoding unit, two radio frequency transmission channels, two radio frequency receiving 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 to form two modulated signals, and then forms high-power radio frequency signals through two radio frequency transmission channels, and radiates through two duplex and antennas; at the receiving end, the received signals from the two antennas are processed by duplex processing and radio frequency receiving channel to form intermediate frequency signals, and then processed by the space-time-frequency code multi-dimensional domain receiving multi-level demodulation and decoding unit to restore 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.

[0032] 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 the service information from the user terminal equipment, and sends the analyzed service frame control and code stream information to the space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit, processes to form two-way modulated signals, and then forms a high-power radio frequency signal through two radio frequency transmission channels, and radiates through two duplex and antennas; at the receiving end, the received signals from the two antennas are processed by duplex processing and radio frequency receiving channel to form an intermediate frequency signal, and then processed by the space-time-frequency code multi-dimensional domain receiving multi-level 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 equipment.

[0033] like Figure 3 The figure shows a space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation method, the main principles of which are: ① service receiving cache and channel re-framing control, parsing and caching the service frame code stream, using service frame control to perform initial reset to form a re-framing control signal, so that the service code stream is input and output in near real time, and then the coded code stream is formed through channel coding and re-framing processing; ② the coded code stream is framed by adding a frame header under the re-framing control, and after two-fold time diversity processing, multi-level spread spectrum modulation is completed through two orthogonal multi-level spread spectrum sequence groups to form two-way code division signals, supporting subsequent two-way space diversity transmission, and each code division signal is modulated and synthesized after half-duty carrier frequency one modulation and half-duty delayed carrier frequency two modulation processing; ③ a two-dimensional orthogonal spread spectrum sequence generator, generating two groups of mutually orthogonal spread spectrum sequence groups, supporting code division of two-way modulated signals to avoid mutual interference, each spread spectrum sequence group includes multiple orthogonal sequences, supporting multi-level modulation.

[0034] like Figure 4 The figure shows the multi-dimensional domain reception 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, half-symbol delayed, and the carrier frequency is down-converted to achieve frequency diversity reception; each frequency diversity reception signal is despread and matched through two orthogonal multi-level spread spectrum sequence groups, on the one hand, 4-fold space diversity signal reception is achieved, and on the other hand, multi-level demodulation is achieved. 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-level diversity combined signal is sent to the symbol synchronization unit, and the symbol synchronization signal is obtained by the maximum value search, and then the frame synchronization is searched in conjunction with the initial hard decision value, 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 The down-conversion processing is to correct the processing parameters in real time through adaptive frequency deviation in multi-channel and multi-mode to perform frequency deviation correction.

[0035] like Figure 5 The figure shows a multi-channel multi-mode adaptive frequency offset real-time correction method, the main process is: ① segment matching parameter adaptive control, the parameter configuration is initialized according to the channel maximum frequency offset estimate, and the frequency offset parameter estimate is adjusted. If the frequency offset estimate is reduced by one time, the segment division and reorganization length is doubled until the maximum matching correlation length is reached, otherwise the current parameter is kept unchanged; ② the eight diversity branch signals are segmented and matched and correlated according to the current segment matching parameters, and then the spectrum is analyzed by FFT transformation; ③ the spectrum analysis results of multi-channel diversity branches are adaptively combined, and the maximum ratio combination and selective combination joint strategy are adopted. When the spectrum analysis value of the diversity branch is less than the predetermined threshold, the branch is automatically disconnected, otherwise it participates in the maximum ratio combination; 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.

[0036] 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-level 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 of extreme large-span scattering links.

[0037] In some embodiments, the space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation method includes: information is sent through two-fold time diversity, and is modulated through two groups of orthogonal multi-level spread spectrum sequence groups to form two-way code division signals, which can support two-fold space diversity transmission, and finally output through two-way 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 groups of spread spectrum sequence groups ensure real-time mutual orthogonality, and a code division method is used to avoid mutual interference of space diversity transmission signals, and to achieve anti-interception and anti-detection capabilities; In some embodiments, the space-time-frequency code multi-dimensional domain reception multi-level demodulation and decoding method includes: a radio frequency reception signal is demodulated by two different carrier frequencies to realize double frequency diversity reception, two radio frequency signals are matched and despread by two orthogonal spread spectrum code groups, and code division processing is performed to realize quadruple space diversity reception, and multi-level despreading and demodulation are jointly realized at the same time, and two-level time diversity merging is performed under frame synchronization control to realize space-time-frequency code multi-dimensional domain sixteen-level diversity reception multi-level demodulation; the multi-level space-frequency diversity combined signal is sent to a symbol synchronization unit, a symbol synchronization signal is obtained by a maximum value search, and then a frame synchronization is searched in conjunction with an initial hard decision value, and further processed to form a time diversity control signal, and a channel decoding iteration is completed; 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 reduced by half, the segment division and reorganization length is doubled until the maximum matching correlation length is reached, otherwise the current parameters are kept unchanged; the eight diversity branch signals are segmented and matched and correlated according to the current segment matching parameters, and then spectrally analyzed through 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.

[0038] Compared with the prior art, the present invention has the following advantages: (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; (2) The present invention proposes a method for implementing a multi-dimensional diversity joint multi-level spread spectrum modulation, demodulation and decoding system, which reduces the weak signal reception threshold under a bad fading channel and can effectively resist the huge transmission loss under a large span extreme scattering channel; (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 large Doppler effect in multiple propagation modes of complex channels and improve the performance of long-span scattering communications; (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.

[0039] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0040] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. 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 disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0041] 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 flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to 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 flowchart and / or block diagram. 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.

[0042] 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 communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0043] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate 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 A function specified in one or more boxes.

[0044] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0045] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0046] The 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. The memory is an example of a computer-readable medium.

[0047] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. 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 disk read-only memory (CD-ROM), digital versatile disk (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 temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0048] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0049] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0050] The above is only 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 modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in 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 sending end performs link handshake, flow control and service analysis on the service information from the user terminal equipment, processes the service frame control and code stream information after analysis to form two-way modulated signals, and then forms a high-power radio frequency signal through two-way radio frequency transmission, which is radiated through two-way duplex and antenna; the receiving end forms an intermediate frequency signal after duplex processing and radio frequency receiving channel processing of 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 equipment after de-adaptation processing.

2. The extreme long-span scattering communication method according to claim 1, characterized in that The method specifically comprises the following steps: S101, through the space-time-frequency code multi-dimensional domain diversity, multi-level spread spectrum technology, combined with dual-channel RF transceiver channels, duplex and antenna units, to build an extreme long-span scattering communication system; S102, realizing information sending end processing through space-time-frequency code multi-dimensional domain diversity transmission and multi-level spread spectrum modulation; S103, realizing information receiving end processing through space-time-frequency code multi-dimensional domain diversity reception and multi-level spread spectrum demodulation iterative decoding method; S104. Realize real-time tracking and correction of complex channel dynamic Doppler through a multi-channel and multi-mode adaptive frequency offset correction method.

3. The extreme long-span scattering communication method according to claim 1, characterized in that: The 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, and service analysis on the service information from the user terminal device, and sends the analyzed service frame control and code stream information to the space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit, processes them to form two modulated signals, and then forms a high-power radio frequency signal through the two radio frequency transmission channels, which is radiated through the two duplex and antennas.

4. The extreme long-span scattering communication method according to claim 3, characterized in that: The receiving end processes the received signals 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 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 device.

5. The extreme long-span scattering communication method according to claim 3 or 4, characterized in that The processing of the space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit includes: S11, service receiving buffer and channel reframing control, analyze and buffer the service framing code stream, use 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 forms a coded code stream through channel coding and reframing processing; S12, the coded code stream is framed by adding a frame header under the re-framing control, and after double time diversity processing, two orthogonal multi-level spread spectrum sequence groups are used to complete multi-level spread spectrum modulation to form two code division signals, supporting subsequent two-way space diversity transmission, and each code division signal is modulated and synthesized after half-duty carrier frequency one modulation and half-duty delayed carrier frequency two modulation processing; S13. Generate two mutually orthogonal spread spectrum sequence groups through two-dimensional orthogonal spread spectrum sequence processing, support code division of two-way modulated signals to avoid mutual interference, each spread spectrum sequence group includes multiple orthogonal sequences, and supports multi-level modulation.

6. The extreme long-span scattering communication method according to claim 3 or 4, characterized in that: The processing of the space-time-frequency code multi-dimensional domain receiving multi-level demodulation and decoding unit includes: S21, performing carrier frequency down-conversion and half-symbol delay and carrier frequency down-conversion processing on each RF receiving signal to achieve frequency diversity reception; S22, each frequency diversity reception signal is despread and matched through two orthogonal multi-level spread spectrum sequence groups, so as to realize quadruple spatial diversity signal reception and multi-level demodulation, thereby obtaining eight-way diversity reception and multi-way multi-level demodulation signals, and then performing eight-branch diversity combination for each multi-level demodulation signal; S23, multi-channel multi-level diversity combined signal, after initial hard decision, select the maximum value decision output, then use the decision value and soft information to jointly calculate the maximum value soft information, and align and combine 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-level 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 performs channel decoding iterative processing; S26, during the down-conversion processing in S21, adaptive frequency deviation real-time correction processing parameters are performed in multi-channel and multi-mode to perform frequency deviation correction.

7. The extreme long-span scattering communication method according to claim 6, characterized in that: The multi-channel multi-mode adaptive frequency deviation real-time correction comprises: S261, segment matching parameter adaptive control, initializing parameter configuration according to the maximum frequency offset estimation of the channel, adjusting according to the current frequency offset parameter estimation, if the frequency offset estimation is reduced by one time, the segment division and reorganization length is doubled until the maximum matching correlation length is reached, otherwise the current parameters are kept unchanged; S262, the eight diversity branch signals are segmented and matched according to the current segment matching parameters, and then the signals are subjected to FFT transformation for spectrum analysis; S263, adaptive diversity combining is performed on the spectrum analysis results of the multi-channel diversity branches, and a maximum ratio combining and selective combining strategy is adopted. When the spectrum analysis value of the diversity branch is less than a predetermined threshold, the branch is automatically disconnected, otherwise, the maximum ratio combining is performed; 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.

8. A system for implementing the extreme long-span scattering communication method according to any one of claims 1 to 7, comprising a transmitting end and a receiving end, characterized in that Also includes: A communication system construction device is used to construct an extreme large-span scattering communication system by combining dual-path radio frequency transceiver channels, duplex and antenna units through space-time-frequency code multi-dimensional domain diversity and multi-level spread spectrum technology; 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; 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 mode; The real-time tracking and correction device is used to realize the real-time tracking and correction of the dynamic Doppler of the complex channel through a multi-channel and multi-mode adaptive frequency offset correction method.

9. The system according to claim 8, characterized in that The 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 receiving multi-level demodulation and decoding unit, two radio frequency transmission channels, two radio frequency receiving channels and two duplex and antenna units; the service access and link adaptation processing unit performs link handshake, flow control and service analysis on the service information from the user terminal equipment, and sends the analyzed service frame control and code stream information to the space-time-frequency code multi-dimensional domain diversity multi-level spread spectrum modulation unit, processes to form two-way modulated signals, and then forms high-power radio frequency signals through two radio frequency transmission channels, and radiates through two duplex and antennas; at the receiving end, the received signals from the two antennas are processed by duplex processing and radio frequency receiving channel to form intermediate frequency signals, and then processed by the space-time-frequency code multi-dimensional domain receiving multi-level demodulation and decoding unit to restore the received frame control and code stream information, and finally output the service information to the user terminal equipment after de-adaptation processing by the service access and link adaptation unit.

10. A computer-readable storage medium having a computer program stored thereon, wherein the program, when executed by a processor, implements the method according to any one of claims 1 to 7.

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