WO2022104993A1 - 天波大规模mimo通信方法、模型及系统 - Google Patents

天波大规模mimo通信方法、模型及系统 Download PDF

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WO2022104993A1
WO2022104993A1 PCT/CN2020/137876 CN2020137876W WO2022104993A1 WO 2022104993 A1 WO2022104993 A1 WO 2022104993A1 CN 2020137876 W CN2020137876 W CN 2020137876W WO 2022104993 A1 WO2022104993 A1 WO 2022104993A1
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sky
wave
massive mimo
base station
communication
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PCT/CN2020/137876
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French (fr)
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高西奇
于祥龙
卢安安
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东南大学
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/22—Scatter propagation systems, e.g. ionospheric, tropospheric or meteor scatter
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/30—Monitoring; Testing of propagation channels
    • H04B17/309—Measuring or estimating channel quality parameters
    • H04B17/345—Interference values
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/30—Monitoring; Testing of propagation channels
    • H04B17/391—Modelling the propagation channel
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/30—Monitoring; Testing of propagation channels
    • H04B17/391—Modelling the propagation channel
    • H04B17/3912—Simulation models, e.g. distribution of spectral power density or received signal strength indicator [RSSI] for a given geographic region
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0014—Three-dimensional division
    • H04L5/0023—Time-frequency-space
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0037—Inter-user or inter-terminal allocation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0058—Allocation criteria
    • H04L5/006—Quality of the received signal, e.g. BER, SNR, water filling
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2626—Arrangements specific to the transmitter only
    • H04L27/2646—Arrangements specific to the transmitter only using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • the invention belongs to the field of sky wave communication, and in particular relates to a sky wave communication method and system using a short-wave band massive MIMO (multiple input multiple output) antenna array.
  • massive MIMO multiple input multiple output
  • sky-wave communication In order to effectively improve the rate performance and reliability of the sky-wave communication system, some existing works have introduced the MIMO technology into the short-wave band sky-wave communication. However, most of them are point-to-point MIMO, and only a small increase in system rate performance can be obtained.
  • Massive MIMO communication can serve a large number of end users on the same time-frequency resource by configuring a large number of antenna units in the base station, thereby significantly improving the system spectral efficiency, power efficiency, transmission rate and reliability.
  • Massive MIMO has become one of the key technologies for fifth-generation (5G) mobile communication systems, and has been extensively studied in the sub-6G band, millimeter wave/terahertz band, and optical band.
  • the invention provides a sky-wave communication method and system for configuring a short-wave band massive MIMO antenna array in a base station.
  • the present invention discloses a sky wave massive MIMO communication method, model and system, which greatly improves the spectrum and power efficiency, transmission bandwidth and distance, speed and terminal capacity of sky wave communication.
  • a sky-wave massive MIMO communication method of the present invention includes: using a large-scale antenna array to construct a sky-wave communication base station in the short-wave band, and the sky-wave communication base station and user terminals in the coverage area perform sky-wave massive MIMO communication through ionospheric reflection.
  • Skywave communication base station determines the spacing of large-scale antenna arrays according to the highest operating frequency, and uses time division duplex TDD communication to communicate with user terminals.
  • Skywave massive MIMO signal transmission adopts orthogonal frequency division multiplexing OFDM or its power efficiency improved modulation.
  • Skywave communication base station selects the communication carrier frequency within the short-wave band according to the real-time ionospheric channel characteristics, and adaptively selects OFDM modulation parameters and signal frame structure; Users perform scheduling to form space-division user groups. Different user groups use different communication time-frequency resources to perform sky-wave massive MIMO signal transmission with the sky-wave communication base station. User terminals in the same user group use the same time-frequency resources to communicate with the sky-wave communication base station. MIMO signal transmission.
  • the large-scale antenna array of the sky-wave communication base station is a linear array composed of antennas in the short-wave band.
  • the spacing of the large-scale antenna arrays of the sky-wave communication base station is the highest operating frequency or a half-wavelength corresponding to the highest operating frequency.
  • the short-wave band range is 1.6MHz-30MHz.
  • the communication carrier frequency is determined by the frequency selection system of the sky wave communication base station. With the change of external factors such as seasons, day and night, and weather, the sky wave communication base station realizes the frequency selection function through passive monitoring and active detection; during the active detection process, the sky wave communication base station sends The dedicated channel detection signal uses the received short-wave full-band signal to implement dynamic frequency selection and interference detection. Generally, the frequency point with less interference should be selected as the current working carrier frequency.
  • the sky wave TDD communication method uses the same frequency band for uplink and downlink transmission, and the time occupied by the uplink and downlink transmission in one frequency band is adjusted as required.
  • the Sky-Wave Massive MIMO signal transmission adopts OFDM or its improved power efficiency modulation mode, specifically: Sky-Wave Massive MIMO downlink signal transmission adopts OFDM modulation mode, and Sky-Wave Massive MIMO uplink signal transmission adopts OFDM modulation or its improved power efficiency. . Including discrete Fourier transform DFT spread OFDM.
  • the user statistical channel information required for user scheduling is the statistical channel information in the OFDM subcarrier domain used by each user terminal.
  • the sky-wave massive MIMO communication time-frequency resources are OFDM modulation symbols and OFDM-modulated subcarriers.
  • the sky-wave massive MIMO signal transmission performed by the same time-frequency resource and the sky-wave communication base station is specifically as follows: each user terminal in the same user group sends and receives signals on the same time-frequency resource; The channel information of the user terminal is calculated, and the uplink receiver and downlink precoder of the user terminal are calculated to receive and transmit signals.
  • the uplink receiver and the downlink precoder are calculated based on the minimum mean square error criterion or the polynomial expansion type or the deterministic equivalent polynomial expansion type.
  • the specific sky-wave massive MIMO communication process is as follows:
  • Synchronization Skywave communication base station broadcasts downlink synchronization signal, user terminal uses the received signal to establish and maintain synchronization with Skywave communication base station;
  • Skywave communication user terminals send uplink sounding signals, and skywave communication base stations use the received sounding signals to estimate the channel state information of each user terminal;
  • Skywave communication base station uses the obtained user channel information to implement user scheduling, and schedules several groups of user groups that communicate simultaneously on the same time-frequency resource within the coverage area;
  • Uplink transmission The user terminals in the same user group send pilot signals and data signals to the SkyWave communication base station at the same time; the SkyWave communication base station uses the uplink sounding signal or pilot signal to estimate the uplink instantaneous channel information or statistical channel information.
  • the square error criterion is either based on a polynomial expansion type or based on a deterministic equivalent polynomial expansion type to calculate the uplink reception processing vector of each user terminal, and implement uplink signal reception processing;
  • Skywave communication base station uses the channel reciprocity of the TDD system to obtain the downlink channel, and calculates the downlink prediction of each user terminal in the user group based on the minimum mean square error criterion or the polynomial expansion type or the deterministic equivalent polynomial expansion type.
  • the coding vector is used to send user pilot signals and data signals in the digital precoding domain; the user terminal uses the obtained downlink pilot signals to perform downlink channel estimation, demodulate and decode data signals, and recover the user signals sent by the base station.
  • the sky-wave communication base station By adopting the beam domain statistical model of the sky-wave massive MIMO broadband communication channel according to the method of the invention, the sky-wave communication base station generates the beam domain statistical model of the sky-wave massive MIMO broadband communication channel; the sky-wave communication base station selects a set of spatial angle sampling grid points, Using the corresponding array direction vectors, the beam-domain statistical representation of the sub-carrier domain channel of sky-wave massive MIMO broadband communication OFDM transmission is formed; each array direction vector corresponds to a beam, and the number of array direction vectors or the number of beams is greater than or equal to The number of antennas in the array; the matrix formed by the array direction vector realizes the conversion between the antenna domain channel of sky-wave massive MIMO broadband communication and the beam domain channel of sky-wave massive MIMO broadband communication, which varies along different signal frequencies or subcarriers; The statistics or energy of a MIMO wideband communication beam-domain channel is the same across all signal frequencies or sub-carriers.
  • the set of spatial angle sampling grid points are uniform sampling grid points of angle cosine.
  • the array direction vector is determined by the sky wave communication base station according to the current signal frequency or subcarrier index number and the antenna spacing configuration.
  • the statistic representation of the sky-wave massive MIMO broadband communication beam domain is specifically: using the matrix formed by the array direction vector, multiplied by a random vector whose elements are independent of each other, to characterize the sky-wave massive MIMO broadband communication antenna domain channel; the random vector is: Skywave Massive MIMO Wideband Communication Beam Domain Channel Vectors.
  • the sky-wave massive MIMO communication system using the method of the present invention includes a base station and a large number of user terminals, and the sky-wave communication base station is configured with a large-scale antenna array in the short-wave band, which is used for user terminals in the same coverage area to perform large-scale antenna arrays through ionospheric reflection.
  • MIMO communication Skywave communication base station determines the spacing of large-scale antenna arrays according to the highest operating frequency, and uses TDD to communicate with user terminals.
  • Skywave massive MIMO signal transmission adopts OFDM or its improved power efficiency modulation method; Skywave communication base station uses real-time ionization to communicate with user terminals.
  • the sky wave communication base station uses the statistical channel information of each user terminal to schedule users in the coverage area to form space division users group, use different time-frequency resources and different user groups to perform sky-wave massive MIMO signal transmission, and use the same time-frequency resource to perform sky-wave massive MIMO signal transmission with user terminals in the same user group.
  • the sky wave communication base station side includes a frequency selection unit, a baseband processing unit, a radio frequency unit, and a large-scale antenna array; wherein, the baseband processing unit includes:
  • Analog-to-digital conversion A/D and digital down-conversion module used in the sky-wave massive MIMO uplink transmission process; the A/D module realizes RF sampling on the short-wave full-band, and converts broadband analog signals into digital signals; digital down-conversion module The digital signal output by the A/D module is digitally down-converted to the baseband to obtain a digital baseband signal;
  • Digital baseband processing and control module In the process of SkyWave massive MIMO uplink transmission, it is used to perform OFDM demodulation, perform joint reception processing on multi-user received signals, and restore the transmitted signals of each user terminal; during SkyWave massive MIMO downlink transmission , used to implement multi-user precoding transmission, generate the transmission signal of each user terminal, and perform OFDM modulation; the control module is used to implement space division user scheduling to form space division user groups and implement other control of the communication process;
  • Digital up-conversion and digital-to-analog conversion D/A module used in the sky-wave massive MIMO downlink transmission process; the digital up-conversion module modulates the digital baseband signal to the radio frequency through digital processing; the D/A module generates the digital up-conversion module The digital transmission signal is converted into an analog signal;
  • the frequency selection unit on the base station side of the sky wave communication performs frequency selection through passive monitoring and active detection.
  • active detection process a dedicated channel detection signal is sent, and short-wave full-band signals are used to implement dynamic frequency selection and interference detection.
  • the frequency with the least interference should be selected. point as the current working carrier frequency;
  • the large-scale antenna array of the sky-wave communication base station is an antenna array composed of short-wave band antenna units, the spacing of the antenna units is a half wavelength corresponding to the highest operating frequency, and the array form is a linear array or other convenient layout forms.
  • the user terminal side includes a baseband processing unit, a radio frequency unit, and an antenna, wherein the baseband processing unit includes:
  • A/D and digital down-conversion module used in the downlink transmission process of Skywave Massive MIMO; the A/D module converts the received analog signal into a digital signal; the digital down-conversion module digitally converts the digital signal output by the A/D module Down-converted to baseband to obtain a digital baseband signal;
  • Digital baseband processing and control module In the process of SkyWave massive MIMO downlink transmission, it is used to implement downlink channel estimation, perform OFDM demodulation, and recover the data signal sent by the base station; in the process of SkyWave massive MIMO uplink transmission, it is used to generate digital transmission signals , perform OFDM modulation;
  • Digital up-conversion and D/A module used in the sky-wave massive MIMO uplink transmission process; the D/A module converts the digital signal into an analog signal; the digital up-conversion module digitally modulates the digital baseband signal to the radio frequency.
  • the short-wave band range is generally 1.6MHz-30MHz.
  • the sky wave TDD communication method uses the same frequency band for uplink and downlink transmission, and the time occupied by the uplink and downlink transmission in one frequency band can be adjusted as required.
  • the sky-wave massive MIMO signal transmission adopts OFDM or its improved power efficiency modulation mode specifically: sky-wave massive MIMO downlink signal transmission adopts OFDM modulation mode, and sky-wave massive MIMO uplink signal transmission adopts OFDM modulation or its power efficiency improved mode. Including DFT spread OFDM.
  • the statistical channel information of each user terminal is the statistical channel information of the OFDM subcarrier domain used by each user terminal.
  • the sky-wave massive MIMO communication time-frequency resources are OFDM modulation symbols and OFDM-modulated subcarriers.
  • the sky-wave massive MIMO signal transmission performed by the same time-frequency resource and user terminals in the same user group is as follows: each user terminal in the same user group sends and receives signals on the same time-frequency resource; the sky-wave communication base station uses the space division user group. The channel information of each user terminal is calculated, and the uplink receiver and downlink precoder of the user terminal are calculated to receive and transmit signals.
  • the uplink receiver and the downlink precoder are calculated based on the minimum mean square error criterion or the polynomial expansion type or the deterministic equivalent polynomial expansion type; the uplink receiver includes a minimum mean square error receiver or a polynomial expansion. type receiver or low-complexity polynomial expansion type receiver; the downlink precoder includes a minimum mean square error precoder or a polynomial expansion type precoder or a low-complexity polynomial expansion type precoder.
  • the sky-wave massive MIMO communication method and system proposed by the present invention can greatly improve the spectrum and power efficiency, transmission bandwidth and distance, speed and terminal capacity of the sky-wave communication system.
  • Making full use of the characteristics of the sky wave channel implementing dynamic frequency selection and adaptively adjusting OFDM and its power efficiency improved parameters and signal frame structure can fully improve the system performance.
  • Make full use of the large span of the array to establish a more accurate wideband channel model in which the direction vector is related to the signal frequency.
  • An oversampling refined beam domain channel statistical model is established to make the statistical channel information more sufficient and accurate.
  • Fig. 1 is a schematic diagram of sky-wave massive MIMO communication
  • Fig. 2 is the flow chart of the sky wave massive MIMO communication method
  • Fig. 3 is the beam domain statistical model diagram of sky wave massive MIMO broadband communication channel
  • Figure 4 is a functional block diagram of the base station side of the SkyWave massive MIMO communication system
  • Figure 5 is a functional block diagram of the user terminal side of the SkyWave massive MIMO communication system
  • FIG. 6 is an uplink traversal and rate result diagram of a sky-wave massive MIMO communication system based on the transmission method of the MMSE receiver, the PE receiver, and the low-complexity PE receiver.
  • FIG. 7 is a graph showing the downlink traversal and rate results of a sky-wave massive MIMO communication system based on the MMSE precoder, PE precoder, and low-complexity PE precoder transmission method.
  • the technical solutions provided by the present invention will be described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.
  • the method of the invention is mainly applicable to the sky-wave massive MIMO (Multiple Input Multiple Output) communication system in which the base station is equipped with a massive antenna array to serve a large number of single-antenna user terminals at the same time.
  • the specific implementation process of the present invention involving the Skywave Massive MIMO communication method and system will be described in detail below with reference to specific communication system examples. It should be noted that the present invention method is not only applicable to the specific system models given in the following examples, but also applicable to other Configured system model.
  • the base station is configured with a large-scale antenna array in the short-wave band, and communicates with a large number of user terminals within its coverage through ionospheric reflection.
  • the sky-wave massive MIMO communication method disclosed in the embodiment of the present invention includes: using a large-scale antenna array to construct a sky-wave communication base station in the short-wave band, and the sky-wave communication base station and user terminals in the coverage area perform ionospheric reflection.
  • Skywave communication base station determines the spacing of large-scale antenna arrays according to the highest operating frequency, and uses TDD duplex mode to communicate with terminals.
  • Skywave massive MIMO signal transmission adopts OFDM or its improved power efficiency modulation method
  • Skywave communication base station According to the real-time ionospheric channel characteristics, the communication carrier frequency is selected in the short-wave band, and the OFDM modulation parameters and signal frame structure are adaptively selected
  • the sky wave communication base station uses the statistical channel information of each user terminal to schedule users in the coverage area to form
  • different user groups use different time-frequency resources to transmit sky-wave massive MIMO signals to the sky-wave communication base station, and user terminals in the same user group use the same time-frequency resources to transmit sky-wave massive MIMO signals to the sky-wave communication base station.
  • the beam domain statistical model of the sky-wave massive MIMO broadband communication channel disclosed in the embodiment of the present invention includes: selecting a set of spatial angle sampling grid points, and using the corresponding array direction vectors to form sky-wave massive MIMO Beam domain statistical characterization of sub-carrier domain channels for broadband communication OFDM transmission; each array direction vector corresponds to a beam, and the number of array direction vectors or beams is greater than or equal to the number of antennas in the array; the matrix formed by the array direction vectors, Realize the conversion between sky-wave massive MIMO broadband communication antenna domain channel and sky-wave massive MIMO broadband communication beam domain channel, varying along different signal frequencies or sub-carriers; the statistics or energy of sky-wave massive MIMO broadband communication beam domain channel is The signal frequency or sub-carriers are the same.
  • the base station side functional module diagram of the sky-wave massive MIMO communication system disclosed in the embodiment of the present invention includes a frequency selection unit, a baseband processing unit, a radio frequency unit, and a large-scale antenna array.
  • the baseband processing unit includes:
  • A/D and digital down-conversion module used for Skywave Massive MIMO uplink transmission process.
  • the A/D module realizes radio frequency sampling on the short-wave full-band, and converts the broadband analog signal into a digital signal;
  • the digital down-conversion module digitally down-converts the digital signal output by the A/D module to the baseband to obtain a digital baseband signal.
  • Digital baseband processing and control module In the process of SkyWave massive MIMO uplink transmission, it is used to perform OFDM demodulation, perform joint reception processing on multi-user received signals, and restore the transmitted signals of each user terminal; during SkyWave massive MIMO downlink transmission , is used to implement multi-user precoding transmission, generate the transmission signal of each user terminal, and perform OFDM modulation; the control module is used to implement space division user scheduling to form space division user groups and implement other control of the communication process.
  • Digital up-conversion and D/A module used for Skywave Massive MIMO downlink transmission process.
  • the digital up-conversion module modulates the digital baseband signal to the radio frequency through digital processing; the D/A module converts the digital transmission signal generated by the digital up-conversion module into an analog signal.
  • the frequency selection unit of the sky wave communication base station performs frequency selection through passive monitoring and active detection.
  • the active detection process sends dedicated channel detection signals, uses full-band signals to implement dynamic frequency selection and interference detection, and selects a frequency with less interference as the current working carrier frequency.
  • the large-scale antenna array of the sky-wave communication base station is an antenna array composed of short-wave band antenna units, the number of antenna units is tens or hundreds, the spacing of the antenna units is determined according to the highest operating frequency, and the array form can be a linear array or other convenient layout form.
  • the user terminal side functional module diagram of the sky-wave massive MIMO communication system disclosed in the embodiment of the present invention, as shown in Figure 5, includes a baseband processing unit, a radio frequency unit, and an antenna; specifically, the baseband processing unit includes:
  • A/D and digital down-conversion module used in the downlink transmission process of Skywave Massive MIMO; the A/D module converts the received analog signal into a digital signal; the digital down-conversion module digitally converts the digital signal output by the A/D module Down-converted to baseband to obtain a digital baseband signal;
  • Digital baseband processing and control module In the process of SkyWave massive MIMO downlink transmission, it is used to implement downlink channel estimation, perform OFDM demodulation, and recover the data signal sent by the base station; in the process of SkyWave massive MIMO uplink transmission, it is used to generate digital transmission signals , perform OFDM modulation;
  • Digital up-conversion and D/A module used in sky-wave massive MIMO uplink transmission process. Among them, the D/A module converts the digital signal into an analog signal; the digital up-conversion module modulates the digital baseband signal digitally to the radio frequency.
  • the number of antennas M is generally tens to hundreds, and it serves U user terminals equipped with a single antenna.
  • the selected system carrier frequency is f c , which needs to be determined by the frequency selection system of the sky wave communication base station, and changes with external factors such as seasons, day and night, and weather.
  • Skywave communication base stations use TDD to communicate with user terminals, use the same frequency band for uplink and downlink transmission, and intermittently use different time periods for uplink transmission and downlink transmission, and the time occupied by uplink and downlink transmission in one frequency band can be adjusted according to needs.
  • the sky-wave communication base station and user terminals in the coverage area perform sky-wave massive MIMO communication through ionospheric reflection.
  • the ionosphere can be divided into D, E, and F layers.
  • the E layer and the F layer mainly reflect the sky wave signal to meet the long-distance communication
  • the D layer mainly absorbs the energy of the sky wave signal and causes the transmission signal attenuation.
  • skywave signal transmission Similar to terrestrial cellular wireless channels, skywave signal transmission also undergoes a multipath propagation process. In particular, the transmitted signal reaches the receiving end through single or multiple reflections of the E layer and/or the F layer.
  • An analog baseband complex signal is sent for the uplink of the user terminal u.
  • the received analog baseband complex signal of the sky wave communication base station can be expressed as
  • h u (t, ⁇ ) ⁇ M ⁇ 1 is the time-varying uplink channel impulse response from the user terminal u to the sky-wave communication base station
  • z ul (t) is the noise vector
  • its M elements each obey the complex white Gaussian process and have the same power spectral density.
  • It is the analog baseband complex signal sent by the sky wave communication base station to the user terminal u. Then the analog baseband complex signal received by the user terminal u can be expressed as
  • [h u (t, ⁇ )] T is the time-varying downlink channel impulse response from the SkyWave communication base station to the user terminal u, expressed as the uplink channel impulse response transposition of .
  • the operator[] T represents the transpose operation, and the superscript T represents the transpose of a matrix or vector, is a complex white Gaussian noise process.
  • the channel delay spread can reach the order of milliseconds.
  • the movement of the ionosphere and the user terminal side will bring about the Doppler frequency shift of the channel.
  • the characteristics of the sky wave communication channel are related to the day and night, season, weather, and the location of the sky wave communication base station and the user terminal.
  • Typical ionospheric-induced Doppler spreads in the mid-latitude calm ionosphere, moderate ionosphere, and disturbed ionosphere environments are 0.1 Hz, 0.5 Hz, and 1 Hz, respectively.
  • the modeling of Doppler spread caused by user terminal movement is similar to that of terrestrial cellular communications.
  • the Doppler extension size is 1.48Hz.
  • the coherence time of sky wave communication channel is determined by the channel Doppler spread, and in typical scenarios, it is much larger than the channel delay spread.
  • OFDM modulation has been used in broadband sky-wave communications.
  • Skywave massive MIMO signal transmission adopts OFDM or its improved power efficiency modulation, specifically: OFDM modulation for downlink signal transmission, OFDM modulation for uplink signal transmission, or its improved power efficiency, including DFT spread OFDM.
  • OFDM modulation is considered for both uplink and downlink signal transmission of sky-wave massive MIMO, and the number of subcarriers is N c , the cyclic prefix (cyclic, CP) length is N g , and the system sampling interval is T s .
  • Skywave massive MIMO communication time-frequency resources are OFDM modulation symbols and OFDM modulation subcarriers.
  • N v sub-carriers are used to transmit data, the index of which is set
  • the remaining N c -N v sub-carriers are set as virtual carriers, which are used as guard bands of the sky-wave communication system, and the signals on them are all set as 0.
  • definition is the kth subcarrier of the user terminal u
  • the transmitted signal on the symbol, then the user terminal u containing the CP is in the first
  • the transmitted analog baseband complex signal over symbols can be expressed as
  • the baseband demodulated signal on the kth subcarrier of symbols can be expressed as
  • the downlink channel frequency response on the kth subcarrier of the symbols is complex Gaussian noise.
  • the antenna domain channel of sky wave massive MIMO broadband communication is established.
  • a generalized stationary uncorrelated scattering channel It is assumed that there are P u distinguishable paths between the user terminal u and the sky-wave communication base station.
  • the transmission delay ⁇ u,p,m of the p-th path between the user terminal u and the m-th antenna of the sky-wave communication base station can be expressed as
  • ⁇ u,p,m ⁇ u,p +(m-1) ⁇ u,p , (8)
  • ⁇ d/c
  • ⁇ u,p represents the transmission delay of the p-th path between the user terminal u and the first antenna of the sky-wave communication base station
  • ⁇ u,p is the downlink departure angle or the uplink arrival angle of the p-th path of the user terminal u.
  • the angular spread is caused by the scattering of the signal during reflection in the ionosphere and the ground, and the angle of multipath propagation is different.
  • the azimuth arrival/departure angle can be different from the great circle direction between the skywave communication base station and the user, and the typical azimuth angle spread is 1°, but a larger angular spread may be observed in a disturbed ionospheric environment.
  • the pitch arrival/departure angle is determined by the great circle distance and the ionospheric pattern. In long-distance sky wave transmission, the observed elevation angle spread is relatively small.
  • the time-varying channel impulse response between the user terminal u and the mth antenna of the skywave communication base station can be expressed as
  • ⁇ u,p (t) is a pure imaginary number
  • ⁇ u,p (t) represents a complex gain random process. Since both the Earth's surface and the reflected ionosphere are rough, it can be assumed that the p-th path contains Q p indistinguishable sub-paths with the same delay and arrival/departure angle. Then ⁇ u,p (t) can be expressed as
  • ⁇ u,p,q , ⁇ u,p,q , and ⁇ u,p,q represent the gain, initial phase, and Doppler frequency shift of the qth subpath, respectively.
  • ⁇ u, p, q are random variables uniformly distributed on the interval [0, 2 ⁇ ).
  • Q p tends to infinity
  • ⁇ u,p (t) obeys a complex Gaussian random process with zero mean and experiences Rayleigh fading.
  • the impulse response vector of the uplink channel from the user terminal u to the skywave communication base station is:
  • * is the convolution symbol
  • g( ⁇ , ⁇ ) [g 1 ( ⁇ , ⁇ ),...,g M ( ⁇ , ⁇ )] T , (13)
  • the frequency response vector of the uplink channel in the sky-wave massive MIMO broadband communication antenna domain can be expressed as
  • the sky wave communication base station selects a set of spatial angle sampling grid points, which are uniform sampling grid points of angle cosine ⁇ . make Indicates the number of sampled array direction vectors.
  • the set of all possible angle cosines is expressed as in And ⁇ represents the union of sets.
  • Definition ⁇ represents the intersection of sets, then can be rewritten as
  • angle cosine in can be approximated as but can be approximated as
  • array direction vector representing samples, varying along different signal frequencies or subcarriers.
  • the array direction vector It is determined by the sky wave communication base station according to the current signal frequency or subcarrier index number and the antenna spacing configuration.
  • the above channel approximation gives a channel representation based on the beam domain, since the sampled array direction vectors correspond to physical spatial beams and each array direction vector corresponds to a beam. can It is considered to be a beam-domain channel element of sky-wave massive MIMO broadband communication and varies along different signal frequencies or sub-carriers k.
  • the subscript represents the first elements
  • represents the modulo operation. It can be seen that the statistics or energy of the sky-wave massive MIMO wideband communication beam-domain channel is the same on all signal frequencies or sub-carriers. can be abbreviated Indicates statistical channel information.
  • ⁇ u,k denote the antenna domain channel correlation matrix of sky-wave massive MIMO broadband communication where the superscript H represents the conjugate transpose of the matrix or vector, which can be calculated
  • tr( ⁇ ) represents the trace of the matrix
  • F represents the Frobenius norm of the matrix.
  • the received signal vector expression of Sky-Wave communication base station on the k-th subcarrier is as follows:
  • H k [h 1,k ,...h U,k ] ⁇ M ⁇ U represents the sky-wave massive MIMO uplink channel matrix on the kth subcarrier, Its covariance matrix satisfies is the transmitted signal of user terminal u, q ul is the average transmit power of each user terminal, is a complex Gaussian noise vector.
  • the linear receiver is represented by R k ⁇ ⁇ U ⁇ M , and the mean square error of the receiver is defined as
  • the downlink received signal vector of U user terminals on the kth subcarrier can be expressed as
  • P k is the precoding matrix and satisfies the power constraint Its covariance matrix satisfies is the signal sent to user terminal u, q dl is the average transmit power of each user terminal, is a complex Gaussian noise vector.
  • the mean square error of precoding is defined as
  • the uplink receiver based on the polynomial expansion can be expressed as
  • N ⁇ U represents the order of the receiver, are the coefficients of the polynomial expansion of the upstream receiver. Further define the coefficient vector as and make can get
  • the subscripts i, j represent the elements of the i-th row and the j-th column of the matrix. Similarly, define
  • This embodiment uses the large-dimensional random matrix theory to calculate certainty is equivalent.
  • the number of antennas of the base station for day-wave massive MIMO communication tends to be infinite, it can be obtained
  • the MMSE receiver/precoder, PE receiver/precoder, and low-complexity PE receiver/precoder in this embodiment under a specific system configuration are given below. Under precoder, uplink/downlink traversal and rate results.
  • Set the number of antennas of Skywave communication base station M 256, the number of sampling beams
  • the number of user terminals U 96.
  • FIG. 6 shows the comparison of uplink traversal and rate results of the MMSE receiver, PE receiver, and low-complexity PE receiver under different total transmit powers in the present embodiment of the considered sky-wave massive MIMO communication system.
  • Figure 7 shows the comparison of downlink traversal and rate results of the MMSE precoder, PE precoder, and low-complexity PE precoder under different total transmit powers in the present embodiment of the considered sky-wave massive MIMO communication system. It can be seen from Figure 6 and Figure 7 that the system uplink and downlink traversal and rate results increase with the increase of the total transmission power. Compared with the sky-wave communication system in the traditional short-wave frequency band, the sky-wave massive MIMO communication in this embodiment can greatly improve the system and rate.

Abstract

本发明公开了天波大规模MIMO通信方法、模型及系统。利用大规模天线阵列，构建短波波段的天波通信基站，与覆盖区内的用户终端通过电离层反射进行天波大规模MIMO通信。天波通信基站依据最高工作频率确定天线阵列间距，采用TDD方式与用户终端通信，信号传输采用OFDM或其功率效率改进型调制方式。天波通信基站根据实时电离层信道特性，在短波波段范围内选定载频，并自适应选取OFDM调制参数及信号帧结构。天波通信基站利用各用户终端的信道信息进行用户调度，形成空分用户组，不同用户组使用不同时频资源、同一用户组使用同一时频资源与天波通信基站进行通信。本发明可以大幅度提升天波通信的频谱与功率效率、传输带宽与距离、以及速率与终端容量。

Description

天波大规模MIMO通信方法、模型及系统 技术领域
本发明属于天波通信领域，具体涉及一种利用短波波段大规模MIMO(多输入多输出)天线阵列的天波通信方法与系统。
背景技术
为了满足未来无线通信对全球覆盖的应用需求，卫星通信被认为是能满足这一需求的有吸引力的候选技术，并已成为学术界和工业界的研究热点。利用短波波段的天波通信可以实现数千公里的超视距通信，从而满足未来无线通信系统对于全球覆盖的需求。天波通信系统不需要昂贵的基础设施，但其仅占据非常有限的频谱资源，且传输依赖时变的多径电离层信道。天波通信系统一般具有很低的系统速率，并在和卫星通信的竞争中处于劣势。近些年来，为了有效提升天波通信系统的速率性能和可靠性，一些现有工作将MIMO技术引入短波波段天波通信中。但绝大部分为点对点MIMO，且只能获得很少的系统速率性能的提升。
大规模MIMO通信通过在基站配置大量的天线单元，可以在同一时频资源上服务大量终端用户，从而显著提升系统频谱效率、功率效率、传输速率及可靠性。大规模MIMO已经成为第五代(5G)移动通信系统的关键技术之一，且在sub-6G频段、毫米波/太赫兹频段和光波段被广泛研究。本发明给出一种在基站配置短波波段大规模MIMO天线阵列的天波通信方法与系统。
发明内容
技术问题：针对现有技术的不足，本发明公开了天波大规模MIMO通信方法及模型和系统，大幅提升天波通信的频谱与功率效率、传输带宽与距离、以及速率与终端容量。
技术方案：本发明的一种天波大规模MIMO通信方法包括：利用大规模天线阵列，构建短波波段的天波通信基站，天波通信基站与覆盖区内的用户终端通过电离层反射进行天波大规模MIMO通信；天波通信基站依据最高工作频率确定大规模天线阵列的间距，采用时分双工TDD通信方式与用户终端进行通信，天波大规模MIMO信号传输采用正交频分复用OFDM或其功率效率改进型调制方式；天波通信基站根据实时电离层信道特性，在短波波段范围内选定通信载频，并自适应选取OFDM调制参数及信号帧结构；天波通信基站利用各用户终端的统计信道信息对覆盖区域内用户进行调度，形成空分用户组，不同用户组使用不同通信时频资源与天波通信基站进行天波大规模MIMO信号传输，同一用户组内用户终端使用同一时频资源与天波通信基站进行天波大规模MIMO信号传输。
其中，所述天波通信基站大规模天线阵列为短波波段的天线组成的线型阵列。
所述天波通信基站大规模天线阵列的间距为最高工作频率或接近最高工作频率对应的半波长。
所述短波波段范围为1.6MHz-30MHz。
所述通信载频通过天波通信基站选频系统确定，随季节、昼夜、天气等外部因素变化，天波通信基站通过无源监测和主动探测实现选频功能；在主动探测过程中，天波通信基站发送专用信道探测信号，利用接收到的短波全波段信号实施动态选频和干扰侦测，一般应选取干扰较小频点作为当前工作载频。
所述天波TDD通信方式使用相同的频带进行上下行传输，在一个频带内上下行传输占用的时间根据需要进行调节。
所述天波大规模MIMO信号传输采用OFDM或其功率效率改进型调制方式，具体为：天波大规模MIMO下行信号传输采用OFDM调制方式，天波大规模MIMO上行信号传输采用OFDM调制或其功率效率改进型。包括离散傅里叶变换DFT扩展OFDM。
所述天波大规模MIMO，用户调度所需用户统计信道信息为各用户终端使用的OFDM子载波域的统计信道信息。
所述天波大规模MIMO通信时频资源为OFDM调制符号与OFDM调制的子载波。
所述同一时频资源与天波通信基站进行天波大规模MIMO信号传输具体为：同一用户组内的各用户终端，在同一时频资源上发送和接收信号；天波通信基站利用空分用户组内各用户终端的信 道信息，计算用户终端的上行接收机和下行预编码器，进行信号的接收和发送处理。
所述上行接收机和下行预编码器为基于最小化均方误差准则或者基于多项式展开型或者基于确定性等同的多项式展开型计算得到。
所述具体天波大规模MIMO通信过程如下：
a.同步：天波通信基站广播下行同步信号，用户终端利用接收信号建立并保持与天波通信基站的同步；
b.信道探测：天波通信用户终端发送上行探测信号，天波通信基站利用接收到的探测信号估计每个用户终端的信道状态信息；
c.空分成组：天波通信基站利用所获得的用户信道信息，实施用户调度，在覆盖区域内调度出若干组在同一时频资源上同时通信的用户组；
d.上行传输：同一用户组内用户终端，同时向天波通信基站发送导频信号和数据信号；天波通信基站利用上行探测信号或导频信号估计上行瞬时信道信息或统计信道信息，基于最小化均方误差准则或者基于多项式展开型或者基于确定性等同的多项式展开型计算各用户终端的上行接收处理矢量，并实施上行信号接收处理；
e.下行传输：天波通信基站利用TDD系统的信道互易性获得下行信道，基于最小化均方误差准则或者基于多项式展开型或者基于确定性等同的多项式展开型计算用户组内各用户终端下行预编码矢量，在数字预编码域上发送用户导频信号和数据信号；用户终端利用所获得的下行导频信号实施下行信道估计，进行数据信号解调、解码等操作，恢复基站发送的用户信号。
采用本发明所述方法的天波大规模MIMO宽带通信信道的波束域统计模型，天波通信基站生成天波大规模MIMO宽带通信信道的波束域统计模型；天波通信基站选定一组空间角度采样格点，利用所对应的阵列方向矢量，形成天波大规模MIMO宽带通信OFDM传输子载波域信道的波束域统计表征；每个阵列方向矢量对应一个波束，阵列方向矢量的个数或波束个数为大于或等于阵列中天线个数；阵列方向矢量构成的矩阵，实现天波大规模MIMO宽带通信天线域信道与天波大规模MIMO宽带通信波束域信道之间的转换，沿不同信号频率或子载波变化；天波大规模MIMO宽带通信波束域信道的统计信息或能量在所有信号频率或子载波上相同。
所述一组空间角度采样格点为角度余弦的均匀采样格点。
所述阵列方向矢量由天波通信基站根据当前信号频率或子载波索引号以及天线间距配置确定。
所述天波大规模MIMO宽带通信波束域统计表征具体为：利用阵列方向矢量构成的矩阵，乘以一各元素相互独立的随机矢量，表征天波大规模MIMO宽带通信天线域信道；所述随机矢量为天波大规模MIMO宽带通信波束域信道矢量。
采用本发明所述方法的天波大规模MIMO通信系统，包括基站和大量用户终端，所述天波通信基站配置短波波段大规模天线阵列，用于同覆盖区内的用户终端通过电离层反射进行大规模MIMO通信；天波通信基站依据最高工作频率确定大规模天线阵列的间距，采用TDD方式与用户终端进行通信，天波大规模MIMO信号传输采用OFDM或其功率效率改进型调制方式；天波通信基站根据实时电离层信道特性，在短波波段范围内选定通信载频，并自适应选取OFDM调制参数及信号帧结构；天波通信基站利用各用户终端的统计信道信息对覆盖区域内用户进行调度，形成空分用户组，使用不同时频资源与不同用户组进行天波大规模MIMO信号传输，使用同一时频资源与同一用户组内用户终端进行天波大规模MIMO信号传输。
其中：所述天波通信基站侧包括选频单元、基带处理单元、射频单元、大规模天线阵列；其中，基带处理单元包括：
模数转换A/D和数字下变频模块：用于天波大规模MIMO上行传输过程；其中，A/D模块实现短波全波段上的射频采样，将宽带模拟信号转换成数字信号；数字下变频模块对A/D模块输出的数字信号通过数字方式下变频到基带，得到数字基带信号；
数字基带处理与控制模块：天波大规模MIMO上行传输过程中，用于进行OFDM解调，对多用户接收信号进行联合接收处理，恢复每个用户终端的发送信号；天波大规模MIMO下行传输过程中，用于实施多用户预编码传输，生成每个用户终端的发送信号，并进行OFDM调制；控制模块用于实施空分用户调度，以形成空分用户组并实施通信过程的其它控制；
数字上变频和数模转换D/A模块：用于天波大规模MIMO下行传输过程；其中，数字上变频模块对数字基带信号通过数字处理方式调制到射频；D/A模块将数字上变频模块生成的数字发送信号转换成模拟信号；
所述天波通信基站侧的选频单元通过无源监测和主动探测进行选频，主动探测过程发送专用信道探测信号，利用短波全波段信号实施动态选频和干扰侦测，一般应选取干扰最小频点作为当前工作载频；
所述天波通信基站大规模天线阵列为短波波段天线单元构成的天线阵列，所述天线单元的间距为最高工作频率对应的半波长，阵列形态为线性阵列或其它方便布设的形态。
所述用户终端侧包含基带处理单元、射频单元、天线，其中，所述基带处理单元包括：
A/D和数字下变频模块：用于天波大规模MIMO下行传输过程；其中，A/D模块将接收模拟信号转换成数字信号；数字下变频模块对A/D模块输出的数字信号通过数字方式下变频到基带，得到数字基带信号；
数字基带处理和控制模块：天波大规模MIMO下行传输过程中，用于实施下行信道估计，进行OFDM解调，恢复基站发送的数据信号；天波大规模MIMO上行传输过程中，用于生成数字发送信号，进行OFDM调制；
数字上变频和D/A模块：用于天波大规模MIMO上行传输过程；其中，D/A模块将数字信号转换成模拟信号；数字上变频模块对数字基带信号通过数字方式调制到射频。
所述短波波段范围一般为1.6MHz-30MHz。
所述天波TDD通信方式使用相同的频带进行上下行传输，在一个频带内上下行传输占用的时间可根据需要进行调节。
所述天波大规模MIMO信号传输采用OFDM或其功率效率改进型调制方式具体为：天波大规模MIMO下行信号传输采用OFDM调制方式，天波大规模MIMO上行信号传输采用OFDM调制或者其功率效率改进型。包括DFT扩展OFDM。
所述各用户终端的统计信道信息为各用户终端使用的OFDM子载波域的统计信道信息。
所述的天波大规模MIMO通信时频资源为OFDM调制符号与OFDM调制的子载波。
所述同一时频资源与同一用户组内用户终端进行天波大规模MIMO信号传输为：同一用户组内的各用户终端，在同一时频资源上发送和接收信号；天波通信基站利用空分用户组内各用户终端的信道信息，计算用户终端的上行接收机和下行预编码器，进行信号的接收和发送处理。
所述上行接收机和下行预编码器为基于最小化均方误差准则或者基于多项式展开型或者基于确定性等同的多项式展开型计算得到；所述上行接收机包括最小均方误差接收机或者多项式展开型接收机或者低复杂度多项式展开型接收机；所述下行预编码器包括最小均方误差预编码器或者多项式展开型预编码器或者低复杂度多项式展开型预编码器。
有益效果：与现有技术相比，本发明具有如下优点
本发明提出的天波大规模MIMO通信方法与系统能够大幅提升天波通信系统的频谱与功率效率、传输带宽与距离、以及速率与终端容量。充分利用天波信道特性，实施动态选频及自适应调整OFDM及其功率效率改进型参数和信号帧结构，能够充分提升系统性能。充分利用阵列跨度大的特点，建立更为精确的方向矢量与信号频率有关的宽带信道模型。建立过采样的精细化波束域信道统计模型，使得统计信道信息更加充分和准确。
附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简要的介绍，显而易见地，下面描述中的附图仅仅表明本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他实施例的附图。
图1为天波大规模MIMO通信示意图；
图2为天波大规模MIMO通信方法流程图；
图3为天波大规模MIMO宽带通信信道的波束域统计模型图；
图4为天波大规模MIMO通信系统基站侧功能模块图；
图5为天波大规模MIMO通信系统用户终端侧功能模块图；
图6为基于MMSE接收机、PE接收机、低复杂度PE接收机传输方法的天波大规模MIMO通信系统上行遍历和速率结果图。
图7为基于MMSE预编码器、PE预编码器、低复杂度PE预编码器传输方法的天波大规模MIMO通信系统下行遍历和速率结果图。
具体实施方式
以下将结合具体实施例对本发明提供的技术方案进行详细说明，应理解下述具体实施方式仅用于说明本发明而不用于限制本发明的范围。本发明方法主要适用于基站配备大规模天线阵列以同时服务大量单天线用户终端的天波大规模MIMO(多输入多输出)通信系统。下面结合具体的通信系统实例对本发明涉及天波大规模MIMO通信方法与系统的具体实现过程作详细说明，需要说明的是本发明方法不仅适用于下面示例所举的具体系统模型，也同样适用于其它配置的系统模型。
如图1所示，本发明实施例公开的天波大规模MIMO通信示意图，基站配置短波波段的大规模天线阵列，通过电离层反射，在其覆盖范围内，与大量用户终端进行通信。
如图2所示，本发明实施例公开的天波大规模MIMO通信方法，包括：利用大规模天线阵列，构建短波波段的天波通信基站，天波通信基站与覆盖区内的用户终端通过电离层反射进行大规模MIMO通信；天波通信基站依据最高工作频率确定大规模天线阵列的间距，采用TDD双工方式与终端进行通信，天波大规模MIMO信号传输采用OFDM或其功率效率改进型调制方式；天波通信基站根据实时电离层信道特性，在短波波段范围内选定通信载频，并自适应选取OFDM调制参数及信号帧结构；天波通信基站利用各用户终端的统计信道信息对覆盖区域内用户进行调度，形成空分用户组，不同用户组使用不同时频资源与天波通信基站进行天波大规模MIMO信号传输，同一用户组内用户终端使用同一时频资源与天波通信基站进行天波大规模MIMO信号传输。
如图3所示，本发明实施例公开的天波大规模MIMO宽带通信信道的波束域统计模型，包括：选定一组空间角度采样格点，利用所对应的阵列方向矢量，形成天波大规模MIMO宽带通信OFDM传输子载波域信道的波束域统计表征；每个阵列方向矢量对应一个波束，阵列方向矢量的个数或波束个数为大于或等于阵列中天线个数；阵列方向矢量构成的矩阵，实现天波大规模MIMO宽带通信天线域信道与天波大规模MIMO宽带通信波束域信道之间的转换，沿不同信号频率或子载波变化；天波大规模MIMO宽带通信波束域信道的统计信息或能量在所有信号频率或子载波上相同。
一、系统构成
本发明实施例公开的天波大规模MIMO通信系统基站侧功能模块图，如图4所示，包括选频单元、基带处理单元、射频单元、大规模天线阵列。具体来说，所述基带处理单元包括：
A/D和数字下变频模块：用于天波大规模MIMO上行传输过程。其中，A/D模块实现短波全波段上的射频采样，将宽带模拟信号转换成数字信号；数字下变频模块对A/D模块输出的数字信号通过数字方式下变频到基带，得到数字基带信号。
数字基带处理与控制模块：天波大规模MIMO上行传输过程中，用于进行OFDM解调，对多用户接收信号进行联合接收处理，恢复每个用户终端的发送信号；天波大规模MIMO下行传输过程中，用于实施多用户预编码传输，生成每个用户终端的发送信号，并进行OFDM调制；控制模块用于实施空分用户调度，以形成空分用户组并实施通信过程的其它控制。
数字上变频和D/A模块：用于天波大规模MIMO下行传输过程。其中，数字上变频模块对数字基带信号通过数字处理方式调制到射频；D/A模块将数字上变频模块生成的数字发送信号转换成模拟信号。
所述天波通信基站选频单元通过无源监测和主动探测进行选频。特别地，主动探测过程发送专用信道探测信号，利用全频段信号实施动态选频和干扰侦测，选取干扰较小频点作为当前工作载频。
所述天波通信基站大规模天线阵列为短波波段天线单元构成的天线阵列，天线单元数为数十个或数百个，天线单元的间距依据最高工作频率确定，阵列形态可以为线性阵列或其它方便布设的形态。
本发明实施例公开的天波大规模MIMO通信系统用户终端侧功能模块图，如图5所示，包括 基带处理单元，射频单元，天线；具体来说，所述基带处理单元包括：
A/D和数字下变频模块：用于天波大规模MIMO下行传输过程；其中，A/D模块将接收模拟信号转换成数字信号；数字下变频模块对A/D模块输出的数字信号通过数字方式下变频到基带，得到数字基带信号；
数字基带处理和控制模块：天波大规模MIMO下行传输过程中，用于实施下行信道估计，进行OFDM解调，恢复基站发送的数据信号；天波大规模MIMO上行传输过程中，用于生成数字发送信号、进行OFDM调制；
数字上变频和D/A模块：用于天波大规模MIMO上行传输过程。其中，D/A模块将数字信号转换成模拟信号；数字上变频模块对数字基带信号通过数字方式调制到射频。
考虑天波通信基站配备间距为d的一维均匀线性阵列，天线数M一般为几十到几百，服务U个配备单根天线的用户终端。在短波波段(1.6-30MHz)范围内选定系统载频为f c，其需要通过天波通信基站选频系统确定，随季节、昼夜、天气等外部因素变化。定义f o为系统最高工作频率，并设置d＝λ o/2，其中λ o＝c/f o，c表示光速。天波通信基站采用TDD方式与用户终端进行通信，使用相同的频带进行上下行传输，上行传输和下行传输间歇地使用不同时段，且在一个频带内上下行传输占用的时间可根据需要进行调节。
二、信号模型
天波通信基站与覆盖区内的用户终端通过电离层反射进行天波大规模MIMO通信。电离层可以被划分为D层、E层和F层。其中，E层和F层主要进行天波信号的反射，来满足远距离通信，D层主要作为吸收天波信号能量，引起传输信号衰减。和陆地蜂窝无线信道类似，天波信号传输也经历多径传播过程。特别地，发送信号经过E层和/或F层的单次或多次反射到达接收端。
定义
Figure PCTCN2020137876-appb-000001
为用户终端u的上行发送模拟基带复信号。天波通信基站的接收模拟基带复信号可以表示为
Figure PCTCN2020137876-appb-000002
其中，h u(t,τ)∈□ M×1是从用户终端u到天波通信基站的时变上行信道冲激响应，z ul(t)是噪声矢量，其M个元素各自服从复白高斯过程且具有相同功率谱密度。类似地，定义
Figure PCTCN2020137876-appb-000003
为天波通信基站发送给用户终端u的模拟基带复信号。那么用户终端u接收到的模拟基带复信号可以表示为
Figure PCTCN2020137876-appb-000004
其中，依据天波TDD通信的上、下行信道互易性，[h u(t,τ)] T是从天波通信基站到用户终端u的时变下行信道冲激响应，表示为上行信道冲激响应的转置。运算符[] T表示转置运算，上标T表示矩阵或矢量的转置，
Figure PCTCN2020137876-appb-000005
是复白高斯噪声过程。
由于天波通信中不同传播路径的传播距离差很大，其信道时延扩展可以达到毫秒量级。同时，电离层和用户终端侧的移动会带来信道多普勒频移。天波通信信道特性随昼夜、季节、天气和天波通信基站与用户终端位置都有关。在中纬度地区平静电离层、中度电离层和扰动电离层环境下典型的电离层引发的多普勒扩展大小分别为0.1Hz、0.5Hz和1Hz。此外，用户终端移动引发的多普勒 扩展的建模和陆地蜂窝通信类似。例如，如果用户终端的移动速度为，100km/h,载频为16MHz，那么多普勒扩展大小为1.48Hz。一般来说，天波通信信道相干时间由信道多普勒扩展决定，且在典型场景下远大于信道时延扩展。通过自适应选取OFDM调制参数和信号帧结构，OFDM调制已经被用于宽带天波通信中。天波大规模MIMO信号传输采用OFDM或其功率效率改进型调制方式，具体为：下行链路信号传输采用OFDM调制方式，上行信号传输采用OFDM调制，或其功率效率改进型，包括DFT扩展OFDM。
本实施例中天波大规模MIMO上下行信号传输均考虑OFDM调制，记子载波数量为N c，循环前缀(cyclic，CP)长度为N g，系统采样间隔为T s。上述OFDM调制参数为天波通信基站根据实时电离层信道特性自适应选取。记T c＝N cT s为OFDM符号持续时间，T g＝N gT s为CP持续时间。天波大规模MIMO通信时频资源为OFDM调制符号与OFDM调制的子载波。假设N v个子载波被用来发送数据，其索引为集合
Figure PCTCN2020137876-appb-000006
其余的N c-N v个子载波被设置为虚载波，作为天波通信系统保护频带，其上的信号均被设为0。定义
Figure PCTCN2020137876-appb-000007
为用户终端u的第k个子载波第
Figure PCTCN2020137876-appb-000008
个符号上的发送信号，则包含CP的用户终端u在第
Figure PCTCN2020137876-appb-000009
个符号上的发送模拟基带复信号可以表示为
Figure PCTCN2020137876-appb-000010
其中，Δf＝1/T c表示子载波间隔。类似地，用
Figure PCTCN2020137876-appb-000011
表示天波通信基站发给用户终端u的第k个子载波第
Figure PCTCN2020137876-appb-000012
个符号上的信号。天波通信基站发给用户终端u的第
Figure PCTCN2020137876-appb-000013
个符号上包含CP的模拟基带复信号可以表示为
Figure PCTCN2020137876-appb-000014
定义h u(t,τ)的傅里叶变换为
Figure PCTCN2020137876-appb-000015
则天波通信基站第
Figure PCTCN2020137876-appb-000016
个符号第k个子载波上的基带解调信号可以表示为
Figure PCTCN2020137876-appb-000017
其中，
Figure PCTCN2020137876-appb-000018
表示第
Figure PCTCN2020137876-appb-000019
个符号第k个子载波上的上行信道频率响应，表示为
Figure PCTCN2020137876-appb-000020
且
Figure PCTCN2020137876-appb-000021
是复高斯噪声矢量,
Figure PCTCN2020137876-appb-000022
表示均值为a，方差为B的循环对称复高斯分布。
类似地，用户终端u在第
Figure PCTCN2020137876-appb-000023
个符号第k个子载波上的基带解调信号可以表示为
Figure PCTCN2020137876-appb-000024
其中，
Figure PCTCN2020137876-appb-000025
表示从天波通信基站到用户u的第
Figure PCTCN2020137876-appb-000026
个符号第k个子载波上的下行信道频率响应，
Figure PCTCN2020137876-appb-000027
是复高斯噪声。
三、信道模型
首先建立天波大规模MIMO宽带通信天线域信道。考虑广义平稳非相关散射信道。假设用户终端u和天波通信基站间存在P u条可分辨路径。用户终端u和天波通信基站第m根天线之间第p条径的传输时延τ u,p,m可以表示为
τ u,p,m＝τ u,p+(m-1)ΔτΩ u,p，        (8)
其中Δτ＝d/c，τ u,p表示用户终端u和天波通信基站第1根天线之间第p条径的传输时延，Ω u,p＝cosθ u,p表示天线阵列的角度余弦，θ u,p是用户终端u第p条径的下行离开角或上行到达角。
角度扩展是由于信号在电离层和地面反射过程中的散射，和多径传播的角度不同引发的。方位到达/离开角可以和天波通信基站与用户间的大圆方向不同，典型的方位角度扩展为1°，但在扰动电离层环境下更大的角度扩展可能会被观测到。俯仰到达/离开角由大圆距离和电离层模式来决定。在远距离天波传输中，观测到的俯仰角度扩展比较小。
上行链路中，用户终端u与天波通信基站第m根天线之间的时变信道冲激响应可以表示为
Figure PCTCN2020137876-appb-000028
其中，
Figure PCTCN2020137876-appb-000029
为纯虚数，α u,p(t)表示复数增益随机过程。由于地球表面和反射电离层都是粗糙的，可以假设第p条径包含Q p条不可分辨的子径，且具有相同的时延和到达/离开角。那么α u,p(t)可以表示为
Figure PCTCN2020137876-appb-000030
其中，β u,p,q，φ u,p,q，和υ u,p,q分别表示第q条子径的增益，初始相位，和多普勒频移。假设φ u,p,q是区间[0,2π)上均匀分布的随机变量。当Q p趋于无穷大时，α u,p(t)服从零均值的复高斯随机过程，经历瑞利衰落。
为了简洁，可以表示用户终端u到天波通信基站的上行信道冲激响应矢量为
Figure PCTCN2020137876-appb-000031
其中，*为卷积符号，
g u,p(t,τ)＝α u,p(t)δ(τ-τ u,p)，       (12)
g(Ω,τ)＝[g 1(Ω,τ),…,g M(Ω,τ)] T，      (13)
且
Figure PCTCN2020137876-appb-000032
进一步地，天波大规模MIMO宽带通信天线域上行信道频率响应矢量可以表示为
Figure PCTCN2020137876-appb-000033
其中
Figure PCTCN2020137876-appb-000034
表示第k个子载波上的阵列方向矢量。可以看出阵列方向矢量v(Ω,k)沿子载波变化。接下来，基于天线域信道模型(15)，进一步利用采样的阵列方向矢量得到统计信道模型。将此统计信道模型表述为波束域信道模型。在下面表述中，定义
Figure PCTCN2020137876-appb-000035
来简化符号表示。
天波通信基站选定一组空间角度采样格点，为角度余弦Ω的均匀采样格点。令
Figure PCTCN2020137876-appb-000036
表示采样的阵列方向矢量个数。全部可能的角度余弦组成的集合表示为
Figure PCTCN2020137876-appb-000037
其中
Figure PCTCN2020137876-appb-000038
且∪表示集合并集。
定义
Figure PCTCN2020137876-appb-000039
为用户终端u的角度余弦集合。定义∩表示集合交集，那么
Figure PCTCN2020137876-appb-000040
可以被改写为
Figure PCTCN2020137876-appb-000041
定义
Figure PCTCN2020137876-appb-000042
且集合
Figure PCTCN2020137876-appb-000043
中的角度余弦可以被近似为
Figure PCTCN2020137876-appb-000044
则
Figure PCTCN2020137876-appb-000045
可以被近似为
Figure PCTCN2020137876-appb-000046
其中，
Figure PCTCN2020137876-appb-000047
表示采样的阵列方向矢量，沿不同信号频率或子载波变化。特别地，阵列方向矢量
Figure PCTCN2020137876-appb-000048
由天波通信基站根据当前信号频率或子载波索引号以及天线间距配置确定。且
Figure PCTCN2020137876-appb-000049
上面的信道近似给出了一种基于波束域的信道表示，由于采样的阵列方向矢量对应物理上的空间波束且每个阵列方向矢量对应一个波束。可以将
Figure PCTCN2020137876-appb-000050
认为是天波大规模MIMO宽带通信波束域信道元素，且沿不同信号频率或子载波k变化。
表示
Figure PCTCN2020137876-appb-000051
为用户终端u在第k个子载波第
Figure PCTCN2020137876-appb-000052
个符号上的天波大规模MIMO宽带通信波束域信道矢量，其各元素为相互独立的随机变量。然后第k个子载波上采样的阵列方向矢量构成的矩阵可以表示为
Figure PCTCN2020137876-appb-000053
这样可以实现天波大规模MIMO宽带通信天线域信道与天波大规模MIMO宽带通信波束域信道之间的转换，表示为
Figure PCTCN2020137876-appb-000054
定义第k个子载波第
Figure PCTCN2020137876-appb-000055
个OFDM符号上的天波大规模MIMO宽带通信波束域信道统计表征为
Figure PCTCN2020137876-appb-000056
其中
Figure PCTCN2020137876-appb-000057
表示求数学期望，□表示哈达玛积，上标*表示矩阵或矢量的共轭。
Figure PCTCN2020137876-appb-000058
的第
Figure PCTCN2020137876-appb-000059
个元素可以被计算为
Figure PCTCN2020137876-appb-000060
其中，下标
Figure PCTCN2020137876-appb-000061
表示矢量的第
Figure PCTCN2020137876-appb-000062
个元素，|□|表示求模值运算。可以看出天波大规模MIMO宽带通信波束域信道的统计信息或能量在所有信号频率或子载波上相同。可以简记
Figure PCTCN2020137876-appb-000063
表示统计信道信息。
三、上行MMSE接收机和下行MMSE预编码器
不失一般性，后续仅考虑第
Figure PCTCN2020137876-appb-000064
个OFDM符号上的传输。为了简洁，在符号标记中省略下标
Figure PCTCN2020137876-appb-000065
。天波大规模MIMO上下行传输前，天波通信基站利用各用户终端使用的OFDM子载波域的统计信道信息实施用户调度。具体来讲，首先生成一个对角阵Λ u，其对角线元素构成的矢量为diag(Λ u)＝ω u，其中diag(□)表示提取矩阵的对角线元素，构成矢量。令Ξ u,k表示天波大规模MIMO宽带通信天线域信道相关矩阵
Figure PCTCN2020137876-appb-000066
其中上标H表示矩阵或矢量的共轭转置，可以计算
Figure PCTCN2020137876-appb-000067
进一步定义用户终端u和用户终端u′间信道相关矩阵的相关性为
Figure PCTCN2020137876-appb-000068
其中，tr(□)表示矩阵的迹，||□|| F表示矩阵的Frobenius范数。在天波大规模MIMO用户调度中，应选取用户终端信道相关矩阵相关性最小的用户终端形成空分用户组。
天波大规模MIMO上行传输中，天波通信基站在第k个子载波上的接收信号矢量表达式为
Figure PCTCN2020137876-appb-000069
其中，H k＝[h 1,k,…h U,k]∈□ M×U表示第k个子载波上的天波大规模MIMO上行信道矩阵，
Figure PCTCN2020137876-appb-000070
其协方差矩阵满足
Figure PCTCN2020137876-appb-000071
是用户终端u的发送信号，q ul是每个用户终端的平均发送功率，
Figure PCTCN2020137876-appb-000072
是复高斯噪声矢量。
用R k∈□ U×M表示线性接收机，定义接收机的均方误差为
Figure PCTCN2020137876-appb-000073
其中||□||表示2范数。定义
Figure PCTCN2020137876-appb-000074
最小化均方误差的上行接收机表达式为
Figure PCTCN2020137876-appb-000075
天波大规模MIMO下行传输中，U个用户终端在第k个子载波上的下行接收信号矢量可以表示为
Figure PCTCN2020137876-appb-000076
其中，P k是预编码矩阵，且满足功率约束
Figure PCTCN2020137876-appb-000077
其协方差矩阵满足
Figure PCTCN2020137876-appb-000078
是发往用户终端u的信号，q dl是每个用户终端的平均发送功率，
Figure PCTCN2020137876-appb-000079
是复高斯噪声矢量。
定义预编码的均方误差为
Figure PCTCN2020137876-appb-000080
其中ζ k是实缩放因子。最小化均方误差的下行预编码器表达式为
Figure PCTCN2020137876-appb-000081
其中ρ dl＝q dl/σ dl，
Figure PCTCN2020137876-appb-000082
取值满足功率约束
Figure PCTCN2020137876-appb-000083
五、基于多项式展开型的上行接收机和下行预编码器
由于最小均方误差准则的上行接收机和下行预编码器中的矩阵求逆操作计算复杂度较高，考虑将该矩阵求逆操作代替为近似的矩阵多项式。首先，基于多项式展开型的上行接收机可以表示为
Figure PCTCN2020137876-appb-000084
其中，N≤U表示接收机的阶数，
Figure PCTCN2020137876-appb-000085
是多项式展开上行接收机的系数。进一步定义系数矢量为
Figure PCTCN2020137876-appb-000086
且令
Figure PCTCN2020137876-appb-000087
可以得到
Figure PCTCN2020137876-appb-000088
其中，
Figure PCTCN2020137876-appb-000089
a k∈□ N×1，且有
Figure PCTCN2020137876-appb-000090
[a k] n＝μ k,n，        (35)
其中，下标i,j表示矩阵的第i行第j列的元素。类似地，定义
Figure PCTCN2020137876-appb-000091
其中，
Figure PCTCN2020137876-appb-000092
记
Figure PCTCN2020137876-appb-000093
的第n个元素为
Figure PCTCN2020137876-appb-000094
则基于多项式展开型的下行预编码器可以表示为
Figure PCTCN2020137876-appb-000095
其中，
Figure PCTCN2020137876-appb-000096
取值满足功率约束
Figure PCTCN2020137876-appb-000097
六、基于确定性等同的多项式展开型上行接收机和下行预编码器
由于系数矢量
Figure PCTCN2020137876-appb-000098
和
Figure PCTCN2020137876-appb-000099
根据瞬时信道H k来计算，则H k一旦变化，
Figure PCTCN2020137876-appb-000100
和
Figure PCTCN2020137876-appb-000101
需要被重新计算更新。频繁更新系数会带来很大的计算复杂度。考虑利用随时间缓慢变化的天波大规模MIMO宽带通信波束域信道的统计信息来计算
Figure PCTCN2020137876-appb-000102
和
Figure PCTCN2020137876-appb-000103
当天波通信基站侧天线数趋于无穷大时，下式成立：
Figure PCTCN2020137876-appb-000104
其中的期望运算
Figure PCTCN2020137876-appb-000105
往往需要进行很大数目的蒙特卡罗仿真，这也会带来很大的计算量。为进一步降低计算复杂度，考虑
Figure PCTCN2020137876-appb-000106
的确定性等同，表示为
Figure PCTCN2020137876-appb-000107
其中
Figure PCTCN2020137876-appb-000108
的计算仅仅需要依赖随时间缓慢变化的天波大规模MIMO宽带通信波束域信道的统计信息。
为了计算
Figure PCTCN2020137876-appb-000109
定义Θ∈□ M×M，η u,k(Θ)表示
Figure PCTCN2020137876-appb-000110
可以计算
Figure PCTCN2020137876-appb-000111
本实施例利用大维随机矩阵理论来计算
Figure PCTCN2020137876-appb-000112
的确定性等同。当天波大规模MIMO通信基站天线数趋于无穷多时，可以得到
Figure PCTCN2020137876-appb-000113
其中，
Figure PCTCN2020137876-appb-000114
可以表示为
Figure PCTCN2020137876-appb-000115
且
Figure PCTCN2020137876-appb-000116
可以通过下面递推关系式得到
Figure PCTCN2020137876-appb-000117
Figure PCTCN2020137876-appb-000118
其中，n∈□，初始值
Figure PCTCN2020137876-appb-000119
当天波大规模MIMO通信基站天线数非常多时，可以用
Figure PCTCN2020137876-appb-000120
来近似μ k,n。定义
Figure PCTCN2020137876-appb-000121
Figure PCTCN2020137876-appb-000122
为
Figure PCTCN2020137876-appb-000123
Figure PCTCN2020137876-appb-000124
则近似的系数矢量可表示为
Figure PCTCN2020137876-appb-000125
记
Figure PCTCN2020137876-appb-000126
的第n个元素为
Figure PCTCN2020137876-appb-000127
则基于确定性等同的多项式展开型上行接收机可以表示为
Figure PCTCN2020137876-appb-000128
类似地，定义
Figure PCTCN2020137876-appb-000129
其中，
Figure PCTCN2020137876-appb-000130
记
Figure PCTCN2020137876-appb-000131
的第n个元素为
Figure PCTCN2020137876-appb-000132
则基于确定性等同的多项式展开型下行预编码器可以表示为
Figure PCTCN2020137876-appb-000133
其中，
Figure PCTCN2020137876-appb-000134
取值满足功率约束
Figure PCTCN2020137876-appb-000135
五、实施效果
为了使本技术领域的人员更好地理解本发明方案，下面给出具体系统配置下的本实施例中MMSE接收机/预编码器，PE接收机/预编码器，低复杂度PE接收机/预编码器下，上行/下行遍历和速率结果。
考虑天波大规模MIMO-OFDM通信系统，系统参数配置如下：载频f c＝16MHz，天波通信基站天线阵列间距d＝9m，系统带宽B＝384kHz，系统采样间隔T s＝1.95μs，子载波间隔Δf＝250Hz，子载波个数N c＝2048，CP个数N g＝512。设置天波通信基站天线数M＝256，采样波束个数
Figure PCTCN2020137876-appb-000136
用户终端数U＝96。定义总发送功率为U个用户终端在系统带宽B＝384kHz上的发送功率之和，遍历和速率为所有有效子载波上的遍历和速率的平均。图6给出了在所考虑天波大规模MIMO通信系统本实施例中MMSE接收机，PE接收机，低复杂度PE接收机在不同发送总功率下的上行遍历和速率结果比较。图7给出了在所考虑天波大规模MIMO通信系统本实施例中MMSE预编码器，PE预编码器，低复杂度PE预编码器在不同发送总功率下的下行遍历和速率结果比较。从图6和图7中可以看出，系统上下行遍历和速率结果随发送总功率的增加而增大。和传统短波频段的天波通信系统相比，本实施例中天波大规模MIMO通信能够大幅度提升系统和速率。
在本申请所提供的实施例中，应该理解到，所揭露的方法，在没有超过本申请的精神和范围内，可以通过其他的方式实现。当前的实施例只是一种示范性的例子，不应该作为限制，所给出的具体内容不应该限制本申请的目的。例如，一些特征可以忽略，或不执行。
本发明方案所公开的技术手段不仅限于上述实施方式所公开的技术手段，还包括由以上技术特征任意组合所组成的技术方案。应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也视为本发明的保护范围。

Claims (26)

  1. 一种天波大规模MIMO通信方法，其特征在于，包括：利用大规模天线阵列，构建短波波段的天波通信基站，天波通信基站与覆盖区内的用户终端通过电离层反射进行天波大规模多输入多输出MIMO通信；天波通信基站依据最高工作频率确定大规模天线阵列的间距，采用时分双工TDD通信方式与用户终端进行通信，天波大规模MIMO信号传输采用正交频分复用OFDM或其功率效率改进型调制方式；天波通信基站根据实时电离层信道特性，在短波波段范围内选定通信载频，并自适应选取OFDM调制参数及信号帧结构；天波通信基站利用各用户终端的统计信道信息对覆盖区域内用户进行调度，形成空分用户组，不同用户组使用不同通信时频资源与天波通信基站进行天波大规模MIMO信号传输，同一用户组内用户终端使用同一时频资源与天波通信基站进行天波大规模MIMO信号传输。
  2. 根据权利要求1所述的天波大规模MIMO通信方法，其特征在于，所述天波通信基站大规模天线阵列为短波波段的天线组成的线型阵列。
  3. 根据权利要求2所述的天波大规模MIMO通信方法，其特征在于，所述天波通信基站大规模天线阵列的间距为最高工作频率或接近最高工作频率对应的半波长。
  4. 根据权利要求1所述的天波大规模MIMO通信方法，其特征在于，所述短波波段范围为1.6MHz-30MHz。
  5. 根据权利要求1所述的天波大规模MIMO通信方法，其特征在于，所述通信载频通过天波通信基站选频系统确定，随季节、昼夜、天气等外部因素变化，天波通信基站通过无源监测和主动探测实现选频功能；在主动探测过程中，天波通信基站发送专用信道探测信号，利用接收到的短波全波段信号实施动态选频和干扰侦测，一般应选取干扰较小频点作为当前工作载频。
  6. 根据权利要求1所述的天波大规模MIMO通信方法，其特征在于，所述天波TDD通信方式使用相同的频带进行上下行传输，在一个频带内上下行传输占用的时间根据需要进行调节。
  7. 根据权利要求1所述的天波大规模MIMO通信方法，其特征在于，所述天波大规模MIMO信号传输采用OFDM或其功率效率改进型调制方式，具体为：天波大规模MIMO下行信号传输采用OFDM调制方式，天波大规模MIMO上行信号传输采用OFDM调制或其功率效率改进型。
  8. 根据权利要求1所述的天波大规模MIMO通信方法，其特征在于，所述天波大规模MIMO，用户调度所需用户统计信道信息为各用户终端使用的OFDM子载波域的统计信道信息。
  9. 根据权利要求1所述的天波大规模MIMO通信方法，其特征在于，所述天波大规模MIMO通信时频资源为OFDM调制符号与OFDM调制的子载波。
  10. 根据权利要求1所述的天波大规模MIMO通信方法，其特征在于，所述同一时频资源与天波通信基站进行天波大规模MIMO信号传输具体为：同一用户组内的各用户终端，在同一时频资 源上发送和接收信号；天波通信基站利用空分用户组内各用户终端的信道信息，计算用户终端的上行接收机和下行预编码器，进行信号的接收和发送处理。
  11. 根据权利要求10所述的天波大规模MIMO通信方法，其特征在于，所述上行接收机和下行预编码器为基于最小化均方误差准则或者基于多项式展开型或者基于确定性等同的多项式展开型计算得到。
  12. 根据权利要求1所述的天波大规模MIMO通信方法，其特征在于，所述具体天波大规模MIMO通信过程如下：
    a.同步：天波通信基站广播下行同步信号，用户终端利用接收信号建立并保持与天波通信基站的同步；
    b.信道探测：天波通信用户终端发送上行探测信号，天波通信基站利用接收到的探测信号估计每个用户终端的信道状态信息；
    c.空分成组：天波通信基站利用所获得的用户信道信息，实施用户调度，在覆盖区域内调度出若干组在同一时频资源上同时通信的用户组；
    d.上行传输：同一用户组内用户终端，同时向天波通信基站发送导频信号和数据信号；天波通信基站利用上行探测信号或导频信号估计上行瞬时信道信息或统计信道信息，基于最小化均方误差准则或者基于多项式展开型或者基于确定性等同的多项式展开型计算各用户终端的上行接收处理矢量，并实施上行信号接收处理；
    e.下行传输：天波通信基站利用TDD系统的信道互易性获得下行信道，基于最小化均方误差准则或者基于多项式展开型或者基于确定性等同的多项式展开型计算用户组内各用户终端下行预编码矢量，在数字预编码域上发送用户导频信号和数据信号；用户终端利用所获得的下行导频信号实施下行信道估计，进行数据信号解调、解码等操作，恢复基站发送的用户信号。
  13. 一种如权利要求1所述方法的天波大规模MIMO宽带通信信道的波束域统计模型，其特征在于，天波通信基站生成天波大规模MIMO宽带通信信道的波束域统计模型；天波通信基站选定一组空间角度采样格点，利用所对应的阵列方向矢量，形成天波大规模MIMO宽带通信OFDM传输子载波域信道的波束域统计表征；每个阵列方向矢量对应一个波束，阵列方向矢量的个数或波束个数为大于或等于阵列中天线个数；阵列方向矢量构成的矩阵，实现天波大规模MIMO宽带通信天线域信道与天波大规模MIMO宽带通信波束域信道之间的转换，沿不同信号频率或子载波变化；天波大规模MIMO宽带通信波束域信道的统计信息或能量在所有信号频率或子载波上相同。
  14. 根据权利要求13所述的天波大规模MIMO宽带通信信道的波束域统计模型，其特征在于，所述一组空间角度采样格点为角度余弦的均匀采样格点。
  15. 根据权利要求13所述的天波大规模MIMO宽带通信信道的波束域统计模型，其特征在于， 所述阵列方向矢量由天波通信基站根据当前信号频率或子载波索引号以及天线间距配置确定。
  16. 根据权利要求13所述的天波大规模MIMO宽带通信信道的波束域统计模型，其特征在于，所述天波大规模MIMO宽带通信波束域统计表征具体为：利用阵列方向矢量构成的矩阵，乘以一各元素相互独立的随机矢量，表征天波大规模MIMO宽带通信天线域信道；所述随机矢量为天波大规模MIMO宽带通信波束域信道矢量。
  17. 一种如权利要求1所述方法的天波大规模MIMO通信系统，包括基站和大量用户终端，其特征在于，所述天波通信基站配置短波波段大规模天线阵列，用于同覆盖区内的用户终端通过电离层反射进行大规模MIMO通信；天波通信基站依据最高工作频率确定大规模天线阵列的间距，采用TDD方式与用户终端进行通信，天波大规模MIMO信号传输采用OFDM或其功率效率改进型调制方式；天波通信基站根据实时电离层信道特性，在短波波段范围内选定通信载频，并自适应选取OFDM调制参数及信号帧结构；天波通信基站利用各用户终端的统计信道信息对覆盖区域内用户进行调度，形成空分用户组，使用不同时频资源与不同用户组进行天波大规模MIMO信号传输，使用同一时频资源与同一用户组内用户终端进行天波大规模MIMO信号传输。
  18. 根据权利要求17所述的天波大规模MIMO通信系统，其特征在于：所述天波通信基站侧包括选频单元、基带处理单元、射频单元、大规模天线阵列；其中，基带处理单元包括：
    模数转换A/D和数字下变频模块：用于天波大规模MIMO上行传输过程；其中，A/D模块实现短波全波段上的射频采样，将宽带模拟信号转换成数字信号；数字下变频模块对A/D模块输出的数字信号通过数字方式下变频到基带，得到数字基带信号；
    数字基带处理与控制模块：天波大规模MIMO上行传输过程中，用于进行OFDM解调，对多用户接收信号进行联合接收处理，恢复每个用户终端的发送信号；天波大规模MIMO下行传输过程中，用于实施多用户预编码传输，生成每个用户终端的发送信号，并进行OFDM调制；控制模块用于实施空分用户调度，以形成空分用户组并实施通信过程的其它控制；
    数字上变频和数模转换D/A模块：用于天波大规模MIMO下行传输过程；其中，数字上变频模块对数字基带信号通过数字处理方式调制到射频；D/A模块将数字上变频模块生成的数字发送信号转换成模拟信号；
    所述天波通信基站侧的选频单元通过无源监测和主动探测进行选频，主动探测过程发送专用信道探测信号，利用短波全波段信号实施动态选频和干扰侦测，一般应选取干扰最小频点作为当前工作载频；
    所述天波通信基站大规模天线阵列为短波波段天线单元构成的天线阵列，所述天线单元的间距为最高工作频率对应的半波长，阵列形态为线性阵列或其它方便布设的形态。
  19. 根据权利要求17所述的天波大规模MIMO通信系统，其特征在于：所述用户终端侧包含 基带处理单元、射频单元、天线，其中，所述基带处理单元包括：
    A/D和数字下变频模块：用于天波大规模MIMO下行传输过程；其中，A/D模块将接收模拟信号转换成数字信号；数字下变频模块对A/D模块输出的数字信号通过数字方式下变频到基带，得到数字基带信号；
    数字基带处理和控制模块：天波大规模MIMO下行传输过程中，用于实施下行信道估计，进行OFDM解调，恢复基站发送的数据信号；天波大规模MIMO上行传输过程中，用于生成数字发送信号，进行OFDM调制；
    数字上变频和D/A模块：用于天波大规模MIMO上行传输过程；其中，D/A模块将数字信号转换成模拟信号；数字上变频模块对数字基带信号通过数字方式调制到射频。
  20. 根据权利要求17所述的天波大规模MIMO通信系统，其特征在于：所述短波波段范围一般为1.6MHz-30MHz。
  21. 根据权利要求17所述的天波大规模MIMO通信系统，其特征在于：所述天波TDD通信方式使用相同的频带进行上下行传输，在一个频带内上下行传输占用的时间可根据需要进行调节。
  22. 根据权利要求17所述的天波大规模MIMO通信系统，其特征在于：所述天波大规模MIMO信号传输采用OFDM或其功率效率改进型调制方式具体为：天波大规模MIMO下行信号传输采用OFDM调制方式，天波大规模MIMO上行信号传输采用OFDM调制或者其功率效率改进型。
  23. 根据权利要求17所述的天波大规模MIMO通信系统，其特征在于：所述各用户终端的统计信道信息为各用户终端使用的OFDM子载波域的统计信道信息。
  24. 根据权利要求17所述的天波大规模MIMO通信系统，其特征在于：所述的天波大规模MIMO通信时频资源为OFDM调制符号与OFDM调制的子载波。
  25. 根据权利要求17所述的天波大规模MIMO通信系统，其特征在于：所述同一时频资源与同一用户组内用户终端进行天波大规模MIMO信号传输为：同一用户组内的各用户终端，在同一时频资源上发送和接收信号；天波通信基站利用空分用户组内各用户终端的信道信息，计算用户终端的上行接收机和下行预编码器，进行信号的接收和发送处理。
  26. 根据权利要求25所述的天波大规模MIMO通信系统，其特征在于：所述上行接收机和下行预编码器为基于最小化均方误差准则或者基于多项式展开型或者基于确定性等同的多项式展开型计算得到；所述上行接收机包括最小均方误差接收机或者多项式展开型接收机或者低复杂度多项式展开型接收机；所述下行预编码器包括最小均方误差预编码器或者多项式展开型预编码器或者低复杂度多项式展开型预编码器。
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