阅读说明：本技术 一种多波束高通量链路建模仿真系统 (Multi-beam high-flux link modeling simulation system ) 是由 王忠华 周武旸 王楷为 李乐天 吴瑞荣 李可 龙永刚 于 2021-08-25 设计创作，主要内容包括：本发明公开了一种多波束高通量链路建模仿真系统,属于卫星通信技术领域,包括前向链路地面端及返向链路用户端、卫星端、前向链路用户端及返向链路地面端；所述前向链路地面端及返向链路用户端包括发送端数传仿真模块、Ka频段无线链路信道传输模块、Ka频段天线发送模块；所述发送端数传仿真模块用于进行对原始数据的编码、数字调制、成型滤波,空闲数据添加工作。本发明在卫星上进行星上解调译码再调制编码等处理,能够有效减少传输时延,解决大容量的信息高速交换问题,使得卫星系统可以采用大量高增益(强方向性)的窄点波束,获得较大的信号波束赋性增益,满足全覆盖和海量连接的需求,值得被推广使用。(The invention discloses a multi-beam high-flux link modeling simulation system, which belongs to the technical field of satellite communication and comprises a forward link ground end, a return link user end, a satellite end, a forward link user end and a return link ground end; the forward link ground end and the return link user end comprise a sending end data transmission simulation module, a Ka frequency band wireless link channel transmission module and a Ka frequency band antenna sending module; and the transmitting end data transmission simulation module is used for encoding, digitally modulating, forming and filtering original data and adding idle data. The satellite demodulation method and the satellite demodulation method have the advantages that the satellite demodulation, decoding, modulation and coding and other processing are carried out on the satellite, the transmission time delay can be effectively reduced, the problem of high-speed exchange of large-capacity information is solved, a satellite system can adopt a large number of high-gain (strong-directivity) narrow spot beams, a large signal beam forming gain is obtained, the requirements of full coverage and mass connection are met, and the satellite demodulation method are worthy of popularization and use.)

1. A multi-beam high-flux link modeling simulation system is characterized in that: the system comprises a forward link ground end, a return link user end, a satellite end, a forward link user end and a return link ground end;

the forward link ground end and the return link user end comprise a sending end data transmission simulation module, a Ka frequency band wireless link channel transmission module and a Ka frequency band antenna sending module; the transmitting end data transmission simulation module is used for encoding, digitally modulating, forming and filtering original data and adding idle data; the Ka frequency band antenna sending module is used for outputting the modulated, molded and filtered signals to a wireless channel, and an ideal amplifier is adopted to simulate the antenna gain; the Ka frequency band wireless link channel transmission module is used for transmitting the signal transmitted by the Ka frequency band antenna transmission module;

the satellite terminal comprises a multi-beam reflector antenna receiving module, an on-satellite baseband receiving module and an on-satellite baseband transmitting module; the multi-beam reflector antenna receiving module is used for selecting a beam channel according to an input switch combination sequence of a feed source and reflector gain after receiving a transmission signal from a channel and outputting the selected beam channel to the satellite baseband receiving module; the satellite baseband receiving module is used for receiving, filtering, down-converting, demodulating, decoding and de-framing signals; the satellite baseband transmitting module is used for signal generation, framing, coding, modulation, up-conversion, filtering processing and signal output;

the forward link user side and the return link ground side comprise a Ka frequency band antenna receiving module and a receiving end data transmission simulation module; the Ka frequency band antenna receiving module is used for receiving transmission signals from a channel, amplifying the transmission signals according to antenna gain, and amplifying and outputting weak signals through a low-noise amplifier in the receiving module; the receiving end data transmission simulation module is used for performing matched filtering, frame synchronization, down sampling, demodulation and decoding of received data and bit error rate statistics.

2. The multi-beam high-throughput link modeling simulation system of claim 1, wherein: after the S-band wireless link channel transmission module receives the transmitted signal, the satellite-ground distance d and the carrier central frequency f are utilized_cCalculating the free space propagation loss PL:

PL(dB)＝92.44+20lgd(m)+20lgf_c(GHz)

and the input attenuation value is added to the calculation of the spatial propagation loss.

3. The multi-beam high-throughput link modeling simulation system of claim 1, wherein: in the satellite baseband receiving module, after a signal is received, a root raised cosine filter is used for matched filtering, then a synchronous head and a frame synchronization module are used for eliminating idle data and completing frame synchronization, then down-sampling is carried out on the data after frame synchronization, an asynchronous data distributor is used for extracting an effective data sequence, and therefore down-conversion is carried out to a baseband, and finally digital demodulation and decoding are carried out to be output to a satellite baseband sending module.

4. The multi-beam high-throughput link modeling simulation system of claim 3, wherein: in the satellite baseband sending module, an input signal is coded and digitally modulated, a sequence generating module is used for generating a synchronous head, an asynchronous data converter is used for framing with the coded and modulated data and a guard interval sequence in the previous step, an up sampler and a root-raised cosine filter are used for forming filtering, idle data are added at the tail of a frame after forming filtering, finally carrier modulation is carried out, and the idle data are output to a satellite-ground wireless channel through an amplifier.

5. The multi-beam high-throughput link modeling simulation system of claim 4, wherein: the multi-beam high-flux link modeling simulation system further comprises a group delay and amplitude-frequency characteristic module, wherein the group delay and amplitude-frequency characteristic module comprises a group delay module and an amplitude-frequency characteristic module; the group delay module is used for calculating the order of a preset filter by utilizing the central frequency, the pass band width, the pass band attenuation, the stop band width, the stop band attenuation and the sampling frequency of an input signal, and calculating the group delay of the filter, and the amplitude-frequency characteristic module is used for inserting an amplitude-frequency characteristic analyzer at any position of a link to analyze the amplitude-frequency characteristic of the position.

6. The multi-beam high-throughput link modeling simulation system of claim 5, wherein: using a frequency translation relationship based on the parameters utilized by the group delay moduleConverting the technical index of the digital filter into the technical index of the analog filter to obtain a zero and a pole of the analog filter, and accordingly obtaining a system function of the corresponding analog filter, wherein if no repeated pole exists, the method comprises the following steps:

converting the system function from an analog domain s plane to a digital domain z plane by using a bilinear transformation method to obtain the system function of the digital filter:

after obtaining the system function of the digital filter, using z ═ e^jwConverting H (z) to H (e)^jw) And calculating group delay:

Technical Field

The invention relates to the technical field of satellite communication, in particular to a multi-beam high-flux link modeling simulation system.

Background

In recent years, with the increase of networking devices and communication data and the difficulty in effective coverage of a ground wireless network in a part of regions, satellite communication can be combined with various multiple access technologies to form a novel communication network due to the characteristics of large coverage area, wide communication frequency band, large capacity and the like, and the novel communication network can be used as effective supplement and expansion of the ground network. Therefore, the system communication capacity and the communication effectiveness of the satellite communication under different coding modulation modes of each frequency band can be verified and simulated before the satellite is transmitted.

Meanwhile, the satellite-ground link has high signal carrier frequency and large path loss, and is difficult to meet the requirement of seamless coverage, and a multi-beam high-flux satellite system can adopt a large number of narrow spot beams, so that signals can obtain larger beam forming gain, the coverage range is enlarged, more antennas are configured under the condition of given antenna size, and the requirements of mass connection, reliability and throughput are fully met. In a satellite communication system, for a specific carrier frequency, different spreading, coding, modulation modes and the like have different signal-to-noise ratio requirements to achieve the communication error rate standard. Therefore, for different spread spectrum, coding and modulation modes, multi-beam high flux is realized, and the satellite physical layer simulation is a technical problem to be solved urgently. Therefore, a multi-beam high-flux link modeling simulation system is provided.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: how to solve the problem that the physical layer of a satellite link can be simulated under different spreading, coding and modulation modes, and the system capacity of the satellite communication system and the signal-to-noise ratio required by reaching a specific bit error rate are verified through different coding and modulation modes, thereby providing a multi-beam high-flux link modeling simulation system.

The invention solves the technical problem by the following technical proposal, and the invention comprises a forward link ground end, a return link user end, a satellite end, a forward link user end and a return link ground end;

the forward link ground end and the return link user end comprise a sending end data transmission simulation module, a Ka frequency band wireless link channel transmission module and a Ka frequency band antenna sending module; the transmitting end data transmission simulation module is used for encoding, digitally modulating, forming and filtering original data and adding idle data; the Ka frequency band antenna sending module is used for outputting the modulated, molded and filtered signals to a wireless channel, and an ideal amplifier is adopted to simulate the antenna gain; the Ka frequency band wireless link channel transmission module is used for transmitting the signal transmitted by the Ka frequency band antenna transmission module;

the satellite terminal comprises a multi-beam reflector antenna receiving module, an on-satellite baseband receiving module and an on-satellite baseband transmitting module; the multi-beam reflector antenna receiving module is used for selecting a beam channel according to an input switch combination sequence of a feed source and reflector gain after receiving a transmission signal from a channel and outputting the selected beam channel to the satellite baseband receiving module; the satellite baseband receiving module is used for receiving, filtering, down-converting, demodulating, decoding and de-framing signals; the satellite baseband transmitting module is used for signal generation, framing, coding, modulation, up-conversion, filtering processing and signal output;

the forward link user side and the return link ground side comprise a Ka frequency band antenna receiving module and a receiving end data transmission simulation module; the Ka frequency band antenna receiving module is used for receiving transmission signals from a channel, amplifying the transmission signals according to antenna gain, and amplifying and outputting weak signals through a low-noise amplifier in the receiving module; the receiving end data transmission simulation module is used for performing matched filtering, frame synchronization, down sampling, demodulation and decoding of received data and bit error rate statistics.

Furthermore, after the transmission module of the S-band wireless link channel receives the transmitted signal, the satellite-ground distance d and the carrier central frequency f are utilized_cCalculating the free space propagation loss PL:

PL(dB)＝92.44+20lg d(m)+20lg f_c(GHz)

and the input attenuation value is added to the calculation of the spatial propagation loss.

Furthermore, in the satellite baseband receiving module, after receiving signals, a root raised cosine filter is used for matched filtering, then a synchronous head and a frame synchronization module are used for eliminating idle data and completing frame synchronization, then down-sampling is carried out on the data after frame synchronization, an asynchronous data distributor is used for extracting an effective data sequence, and therefore down-conversion is carried out to a baseband, and finally digital demodulation and decoding are carried out and output to a satellite baseband sending module.

Furthermore, in the satellite baseband sending module, an input signal is coded and digitally modulated, a sequence generating module is used for generating a synchronous head, an asynchronous data converter is used for framing with the coded and modulated data and a protection interval sequence in the previous step, an up sampler and a root-raised cosine filter are used for forming filtering, idle data are added at the tail of a frame after forming filtering, and finally carrier modulation is carried out, and the idle data are output to a satellite-ground wireless channel through an amplifier.

Furthermore, the multi-beam high-flux link modeling simulation system further comprises a group delay and amplitude-frequency characteristic module, wherein the group delay and amplitude-frequency characteristic module comprises a group delay module and an amplitude-frequency characteristic module; the group delay module is used for calculating the order of a preset filter by utilizing the central frequency, the pass band width, the pass band attenuation, the stop band width, the stop band attenuation and the sampling frequency of an input signal, and calculating the group delay of the filter, and the amplitude-frequency characteristic module is used for inserting an amplitude-frequency characteristic analyzer at any position of a link to analyze the amplitude-frequency characteristic of the position.

Further, a frequency translation relationship is employed based on the parameters utilized by the group delay moduleConverting the technical index of the digital filter into the technical index of the analog filter to obtain a zero and a pole of the analog filter, and accordingly obtaining a system function of the corresponding analog filter, wherein if no repeated pole exists, the method comprises the following steps:

converting the system function from an analog domain s plane to a digital domain z plane by using a bilinear transformation method to obtain the system function of the digital filter:

after obtaining the system function of the digital filter, using z ═ e^jwConverting H (z) to H (e)^jw) And calculating group delay:

compared with the prior art, the invention has the following advantages: in a general satellite simulation system, a mode of direct forwarding on the satellite is mostly adopted, and the multi-beam high-flux link modeling simulation system demodulates, decodes, modulates and encodes on the satellite planet, can effectively reduce transmission delay, solves the problem of high-speed exchange of large-capacity information, enables the satellite system to adopt a large number of high-gain (strong-directivity) narrow spot beams, obtains a large signal beam forming gain, meets the requirements of full coverage and mass connection, and is worthy of popularization and use.

Drawings

Fig. 1 is a flow chart of a transmitting end data transmission baseband simulation module in an embodiment of the present invention;

fig. 2 is a flowchart of an antenna transmission module (Ka band antenna transmission module) of a user terminal and a ground station according to an embodiment of the present invention;

fig. 3 is a flow chart of a multi-beam reflector antenna receiving module in an embodiment of the present invention;

FIG. 4 is a flow chart of an on-board baseband receiving module according to an embodiment of the present invention;

FIG. 5 is a flow chart of an on-board baseband transmission module according to an embodiment of the present invention;

fig. 6 is a flowchart of an antenna receiving module (Ka band antenna receiving module) of a user terminal and a ground station according to an embodiment of the present invention;

FIG. 7 is a flow chart of a receiving end data transmission simulation module in the embodiment of the present invention;

fig. 8 is a flow chart (return) of a multi-beam high-throughput link modeling simulation system in an embodiment of the invention.

Detailed Description

The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.

The embodiment provides a technical scheme: a multi-beam high-throughput link modeling simulation system, comprising:

forward link ground side and reverse link user side

The system comprises a sending end data transmission simulation module, a Ka frequency band wireless link channel transmission module and a Ka frequency band antenna sending module;

the transmitting end data transmission simulation module is used for encoding, digitally modulating, forming and filtering, upsampling and adding idle data to original data;

the data rate (data transmission rate) is 1Mbps-800Mbps, the coding comprises a plurality of coding modes of convolutional codes, LDPC, RS and BCH, and the digital modulation comprises modes of BPSK, QPSK, UQPSK, 8PSK and the like;

the Ka frequency band wireless link channel transmission module is used for receiving signals sent by an antenna and utilizing the satellite-ground distance d and the carrier central frequency f_cCalculating the free space propagation loss PL:

PL(dB)＝92.44+20lg d(m)+20lg f_c(GHz)

adding attenuation values input by rain attenuation, ionosphere attenuation and the like into the calculation of path loss;

the Ka frequency band antenna sending module is used for outputting the modulated, formed and filtered signals to a wireless channel, and simulating antenna gain by adopting an ideal amplifier, wherein the antenna gain is comprehensively provided according to influence factors such as omnidirectional antenna transmitting power, an antenna directional diagram and the like;

in the modeling process, not only a modulation coding mode but also parameters such as a frame length and the like are considered, wherein filters of the data transmission simulation module and the satellite module are designed according to requirements, and factors such as rain attenuation, atmospheric dispersion and the like are considered for the wireless channel module.

Satellite terminal

The system comprises a multi-beam reflector antenna receiving module, an on-satellite baseband receiving module and an on-satellite baseband transmitting module;

and the multi-beam reflector antenna receiving module is used for selecting a beam channel according to the input switch combination sequence of the feed source and the reflector gain after receiving the transmission signal from the channel and outputting the selected beam channel to the satellite baseband receiving module.

The satellite baseband receiving module mainly comprises the functions of signal receiving, filtering, down-conversion, demodulation, decoding, frame decoding and the like; the main process is as follows: firstly, a root raised cosine filter which is the same as the data transmission module is used for matched filtering, a synchronous head and a frame synchronization module are used for eliminating idle data and completing frame synchronization, then down-sampling is carried out on the data after frame synchronization, an effective data sequence is extracted by an asynchronous data distributor, so that down-conversion is carried out to a baseband, and finally digital demodulation and decoding are carried out and output to a baseband sending module on the satellite; the satellite baseband receiving module and the ground data transmission receiving module are the same in structure.

The satellite baseband sending module mainly comprises the functions of signal generation, framing, coding, modulation, up-conversion, filtering, signal output and the like. The main process is as follows: firstly, coding and digitally modulating an input signal, generating a synchronous head by using a sequence generating module, framing the synchronous head, data which is coded and modulated in the previous step and a protection interval sequence (tail complement 0) by using an asynchronous data converter, then performing forming filtering by using an up sampler and a root-raised cosine filter, adding a plurality of bits of idle data at the tail of a frame after the forming filtering, finally performing carrier modulation, and outputting the idle data to a satellite-ground wireless channel through an amplifier. The satellite baseband sending module and the ground data transmission sending module are the same in structure.

Among them, the amplifier uses a Low Noise Amplifier (LNA), and in the case of amplifying a weak signal, the noise of the amplifier itself may cause serious interference to the signal, so it is desirable to reduce the noise to improve the signal-to-noise ratio of the output;

the degree of signal-to-noise ratio degradation caused by the amplifier is typically expressed in terms of a noise factor F. The noise figure F of an ideal amplifier is 1, which has the physical meaning that the input signal-to-noise ratio is equal to the output signal-to-noise ratio. NF in the SystemVue amplifier module corresponds to a noise figure, that is, NF (dB) is 10lg F, NF 0 corresponds to F1, and NF of a good low noise amplifier can be less than 3 dB.

Where the noise figure is low, the noise temperature T is also typically used_eAs a measure of the noise performance of the amplifier:

T_e(K)＝T₀(F-1)

wherein T is₀At room temperature, 290K is usually taken.

For a multistage cascade low noise amplifier, the noise mainly depends on its front stage, and for example, the noise coefficients of N cascaded low noise amplifiers are:

wherein F₁、F₂、…、F_NAs noise coefficient, A₁、A₂、…、A_NIs the low noise amplifier gain;

the modeling process needs to consider not only frame synchronous sampling, but also a digital modulation and coding mode, wherein filters of a data transmission simulation module and an on-satellite module are designed according to requirements.

The system comprises a Ka frequency band antenna receiving module and a receiving end data transmission simulation module;

the Ka frequency band antenna receiving module is used for receiving transmission signals from a channel, amplifying the transmission signals according to antenna gain, amplifying weak signals through a low-noise amplifier in the receiving module and outputting the weak signals to the frequency conversion module;

the receiving end data transmission simulation module is used for performing matched filtering, frame synchronization, down sampling, demodulation and decoding of received data and bit error rate statistics;

the receiving end data transmission simulation module not only comprises the inverse process of the transmitting end data transmission simulation module, but also comprises the calculation of the error rate, and finally the calculation result of the error rate can be output.

Group delay and amplitude-frequency characteristic module

Obtaining a preset order of the filter through theoretical calculation by utilizing the central frequency, the passband width (passband cut-off frequency), the passband attenuation, the stopband width (stopband cut-off frequency), the stopband attenuation and the sampling frequency of an input signal so as to calculate the group delay characteristic of the filter;

according to the above input parameters, adopting frequency conversion relationConverting the technical index of the digital filter into the technical index of the analog filter to obtain a zero and a pole of the analog filter, and accordingly obtaining a system function of the corresponding analog filter, wherein if no repeated pole exists, the method comprises the following steps:

wherein s is_pkFor the kth pole, A, of an analog filter_kFor the gain corresponding to the kth pole, H(s) is the Laplace domain function of the filter.

Converting the system function from an analog domain s plane to a digital domain z plane by using a bilinear transformation method to obtain the system function of the digital filter:

after obtaining the system function of the digital filter, using z ═ e^jwConverting H (z) to H (e)^jw) And calculating group delay:

for the amplitude-frequency characteristic module, a spectrum analyzer device (which can output an amplitude-frequency characteristic graph of a corresponding node) in system mvue can be used for inserting at any position of a link, and the spectrum analyzer is used for outputting at the radio frequency end (before decoding).

The working principle is as follows:

the specific implementation of the multi-beam high-throughput link modeling simulation software (return) is shown in fig. 8 (exchange of user side and ground station in the forward direction). First, as shown in fig. 1, data is generated in the SystemVue, encoded and digitally modulated by MATLAB, and then subjected to operations such as framing, upsampling, shaping filtering, and the like, and idle data is inserted at the end of the frame, and then transmitted to the transmitting antenna module through carrier modulation. The transmitting antenna module receives the up-converted signal, gives a certain antenna gain and then transmits the signal to a wireless channel. As shown in fig. 3, the multi-beam reflector antenna receiving module receives a signal passing through a wireless channel, calculates antenna gain according to a Ka band antenna shape error simulation module and a Ka band antenna beam radiation characteristic modeling module, selects a beam channel according to an input switch combination sequence of a feed source and reflector gain, and outputs the selected beam channel to the satellite baseband receiving module. As shown in fig. 4, the satellite baseband receiving module performs signal matching filtering, frame synchronization, down-sampling, digital demodulation, decoding, and other processing, and then inputs the processed signals to the satellite baseband transmitting module. As shown in fig. 5, the baseband on satellite transmission module performs encoding, digital modulation, spreading, framing, upsampling, shaping, filtering, and other processing, and then transmits the result to the wireless channel. As shown in fig. 6, in the user side and ground station antenna receiving module (Ka band antenna receiving module), the user side or ground station receives a signal sent from the satellite, gives a certain antenna gain, and outputs the signal to the receiving end data transmission simulation module shown in fig. 7, and outputs the received data through a series of inverse operations with respect to the transmitting end data transmission simulation module, and calculates the bit error rate of the entire system (when calculating the BER, the transmitting end data and the receiving end data are input to the BER calculating module in the receiving end data transmission simulation module, and further calculates the bit error rate and the frame error rate).

To sum up, the multi-beam high-throughput link modeling simulation system of the above embodiment demodulates, decodes, modulates, encodes, and the like on the satellite, can effectively reduce transmission delay, solves the problem of high-speed exchange of large-capacity information, enables the satellite system to adopt a large number of high-gain (strong-directivity) narrow spot beams, obtains a large signal beam forming gain, meets the requirements of full coverage and mass connection, and is worthy of popularization and use.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.