CN114301515B - Terminal simulator for low-earth-orbit satellite constellation communication system and control method - Google Patents

Abstract

The invention relates to a terminal simulator and a control method for a low-orbit satellite constellation communication system, wherein the multiple access mode of the terminal simulator for communicating with a satellite comprises one or a combination of a plurality of time division multiple access, a frequency division multiple access, a code division multiple access and a space division multiple access, the terminal simulator comprises a terminal uplink and receiving parameter simulation module, a local pps signal synchronization module, a spread spectrum transmitting module and a spread spectrum receiving module, the terminal uplink and receiving parameter simulation module is used for outputting a multiple access control signal which corresponds to the set multiple access mode and is used for uplink and receiving of the terminal, the spread spectrum receiving module is used for receiving and demodulating a downlink signal sent by the satellite, and the spread spectrum transmitting module is used for receiving the multiple access control signal and outputting the uplink signal to the satellite. By combining multiple access modes, the communication capacity and the test efficiency of the satellite constellation communication system can be improved from multiple angles of time, frequency, address and space.

Description

A terminal simulator and control method for a low-orbit satellite constellation communication system

technical field

The invention relates to the technical field of satellite communication, in particular to a terminal simulator and a control method for a low-orbit satellite constellation communication system.

Background technique

According to different operating altitudes, satellites can generally be divided into three categories: high-orbit satellites, medium-orbit satellites and low-orbit satellites. Due to its close distance from the ground, the low-orbit satellite communication system has the advantages of small delay, small path loss, and low transmission power, and is widely used in various fields. The low-orbit satellite constellation can provide global coverage and rapidly improve the capabilities of satellite communication and satellite remote sensing; it has great potential in communication broadband and can improve service quality with lower signal propagation delay; apply the low-orbit constellation to current global navigation satellites The signal enhancement of the system can realize fast and accurate positioning. The satellite constellation arranges multiple satellites on several orbital planes, and forms a cellular service cell on the surface of the earth through communication links. User terminals in the service area are covered by at least one satellite and access the system in specified time slots.

As an important basis for joint commissioning and testing of satellite in-orbit operation, terminal simulation plays an important guiding role in the development of ground terminals. The terminal emulator can receive and process the downlink signal transmitted by the satellite, and transmit the uplink signal for Doppler compensation and satellite-ground distance compensation. The terminal simulator can receive and process satellite high-dynamic signals, and perform Doppler compensation and satellite-ground distance compensation; it can also generate specific signals to verify the acquisition and tracking performance of satellite receivers.

In the prior art, terminal simulators used in low-orbit satellite communication systems generally use code division multiple access to communicate with satellites. The number of users is affected by the number of pseudo-random codes. At the same time, the number of users that can be accessed by the system is relatively small. The test efficiency of the simulated satellite constellation communication system is low.

Therefore, it is necessary to provide a terminal simulator that improves the communication capacity of the low-orbit satellite communication system and increases the number of terminals that can be simulated to solve the above technical problems.

Contents of the invention

In order to solve the above technical problems, the present invention provides a terminal simulator for a low-orbit satellite constellation communication system. The invention solves the problems that the code division multiple access method is adopted in the prior art to realize communication with different user terminals, the number of accessible users is too small, and the test efficiency of the communication system is low.

Technical effect of the present invention is achieved as follows:

A terminal emulator for a low-orbit satellite constellation communication system, the terminal emulator is used to simulate a plurality of terminals to communicate with satellites, and the multiple access methods for the terminal emulator to communicate with satellites include time division multiple access and frequency division multiple access , code division multiple access, space division multiple access, or a combination of several of them, the terminal emulator includes a terminal uplink and receiving parameter simulation module, a local pps signal synchronization module, a spread spectrum transmitting module and a spread spectrum receiving module, so The terminal uplink and receiving parameter simulation module is used to output the multiple access control signal for terminal uplink and reception corresponding to the set multiple access mode to control the spread spectrum transmitting module and the spread spectrum receiving module according to the multiple access mode The spread spectrum receiving module is used to receive the multiple access control signal and the downlink signal sent by the satellite and demodulates the downlink signal sent by the satellite according to the multiple access control signal, and the spread spectrum transmit module is used to receive The multiple access control signal is used to output an uplink signal to the satellite, and the local pps signal synchronization module is used to output the local pps signal to the terminal uplink and receiving parameter simulation module. Through the new terminal emulator in this application, multiple multiple access methods such as time division multiple access, frequency division multiple access, code division multiple access, and space division multiple access can be used to realize the simulation between multiple terminals and satellites Communication, so that the communication capacity of the satellite constellation communication system can be improved from multiple perspectives of time, frequency, address and space, and the number of terminals that can be simulated by the terminal simulator has been greatly increased, thereby increasing the number of users that the satellite constellation communication system can access. Furthermore, it is possible to simulate and test a satellite constellation communication system that uses different multiple access methods for communication and has a large number of users, which improves the test efficiency of the satellite constellation communication system and solves the problem of using code division multiple access methods in the prior art. Inter-communication, the number of accessible users is too small, and the communication system testing efficiency is low.

Further, the multiple access control signal output by the terminal uplink and receiving parameter simulation module includes a time slot control signal, a carrier frequency control signal, a pseudocode frequency control signal and a pseudocode generator polynomial.

Further, the terminal uplink and receiving parameter simulation module includes a read address control module, a terminal uplink and receive parameter ROM and a terminal uplink and receive parameter parsing module, and the read address control module is used to output an address to the terminal uplink and a receiving parameter ROM, the terminal uplink and receiving parameter analysis module is used to read and analyze the multiple access parameters corresponding to the addresses in the terminal uplink and receiving parameter ROM to output corresponding multiple access control signals.

Further, the spread spectrum transmission module includes a Doppler compensation and delay control module, and the Doppler compensation and delay control module is used to compensate Doppler dynamics and satellite-ground distance delay output terminal uplink pseudo-code NCO control word and The terminal uplinks the carrier NCO control word to modulate the corresponding multiple access control signal for the terminal uplink.

Further, the spread spectrum receiving module includes a capturing module, which is used to capture the sampled downlink signal output terminal receiving carrier NCO control word, terminal receiving pseudo code NCO control word and terminal receiving pseudo code phase control signal.

Further, when multiple terminals simulated by the terminal emulator are located in the same beam coverage area and use the same carrier frequency and the same pseudo code, the terminal emulator uses time division multiple access to communicate with the satellite.

Further, when multiple terminals simulated by the terminal emulator are located in the same beam coverage area and use the same pseudocode and different carrier frequencies, the terminal emulator communicates with the satellite in a frequency division multiple access manner.

Further, when multiple terminals simulated by the terminal emulator are located in the same beam coverage area and use the same carrier frequency and different pseudocodes, the terminal emulator communicates with the satellite in a code division multiple access manner.

Further, when multiple terminals simulated by the terminal emulator are located in different beam coverage areas and use the same carrier frequency and the same pseudo code, the terminal emulator communicates with the satellite in a space division multiple access manner.

In addition, a control method for a terminal simulator for a low-orbit satellite constellation communication system is also provided, the method is implemented based on the above-mentioned terminal simulator for a low-orbit satellite constellation communication system, and the method includes:

The control terminal uplink and receiving parameter simulation module initializes the multiple access control signal corresponding to the parameter output related to the multiple access mode, and the multiple access control signal includes a multiple access control signal for terminal uplink and a multiple access control signal for terminal reception;

The terminal emulator simulates a plurality of terminals according to the multiple access control signal, and the multiple terminals respectively use different multiple access parameters to modulate and demodulate the input signal and the output signal;

The multiple terminals simulated by the terminal simulator receive the downlink signal sent by the satellite through the spread spectrum receiving module according to their corresponding multiple access parameters, and demodulate the uplink signal according to the multiple access control signal used for terminal reception;

Multiple terminals simulated by the terminal simulator use the spread spectrum transmitting module to compensate the Doppler dynamics and the satellite-to-ground distance delay for the multiple access control signals used for the terminal uplink, and output the terminal uplink pseudo code NCO control word and the terminal uplink carrier NCO control word;

Multiple terminals simulated by the terminal emulator modulate the terminal uplink pseudocode NCO control word and terminal uplink carrier NCO control word according to their corresponding multiple access parameters to output uplink signals to the satellite.

As mentioned above, the present invention has the following beneficial effects:

1) Through the new terminal emulator in this application, multiple multiple terminals and satellites can be simulated by combining multiple access methods such as time division multiple access, frequency division multiple access, code division multiple access, space division multiple access, etc. Inter-communication, so that the communication capacity of the satellite constellation communication system can be improved from multiple perspectives of time, frequency, address and space, and the number of terminals that can be simulated by the terminal simulator is greatly increased, thereby increasing the number of users that the satellite constellation communication system can access Quantity, and then can simulate and test the satellite constellation communication system that uses different multiple access methods for communication and has a large number of users, improves the test efficiency of the satellite constellation communication system, and solves the problem of using code division multiple access in the prior art. Communication between user terminals, the number of accessible users is too small, and the communication system testing efficiency is low.

2) By setting the terminal uplink and receiving parameter simulation module, the parameters related to the multiple access mode can be initialized by controlling the terminal uplink and receiving parameter simulation module to output the corresponding multiple address control signal to realize the multiple access mode of terminal uplink and terminal reception, so that According to the multiple access mode of the terminal that needs to communicate, the terminal emulator is switched to the corresponding multiple access mode, so that the terminal emulator can simulate the communication between the terminal and the satellite using different multiple access modes.

Description of drawings

In order to illustrate the technical solution of the present invention more clearly, the following will briefly introduce the drawings required for the embodiments or the description of the prior art. Apparently, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings according to these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a terminal simulator for a low-orbit satellite constellation communication system provided by an embodiment of this specification;

FIG. 2 is a schematic structural diagram of a terminal uplink and receiving parameter simulation module provided by an embodiment of this specification;

Fig. 3 is a working flow chart of the terminal uplink and receiving parameter simulation module provided by the embodiment of this specification;

Fig. 4 is a schematic diagram of the communication process when the terminal emulator provided by the embodiment of this specification adopts the mode of time division multiple access to communicate with the satellite;

Fig. 5 is a schematic diagram of the communication process when the terminal emulator provided by the embodiment of this specification adopts the mode of frequency division multiple access to communicate with the satellite;

Fig. 6 is a schematic diagram of the communication process when the terminal emulator provided by the embodiment of this specification adopts the mode of code division multiple access to communicate with the satellite;

Fig. 7 is a schematic diagram of the communication process when the terminal emulator provided by the embodiment of this specification adopts the mode of space division multiple access to communicate with the satellite;

Fig. 8 is a schematic diagram of the communication process when the terminal emulator provided by the embodiment of this specification adopts a combination of time division multiple access, frequency division multiple access, code division multiple access, and space division multiple access to communicate with the satellite;

FIG. 9 is a schematic flow diagram of the communication between the terminal emulator and the satellite provided by the embodiment of this specification.

Wherein, the reference numerals in the figure correspond to:

Terminal uplink and receiving parameter simulation module 1, read address control module 11, terminal uplink and receiving parameter ROM, terminal uplink and receiving parameter analysis module 13, spread spectrum transmitting module 3, Doppler compensation and delay control module 31, spread spectrum The receiving module 4 and the capturing module 41 .

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

It should be noted that the terms "first" and "second" in the description and claims of the present invention and the above drawings are used to distinguish similar objects, but not necessarily used to describe a specific sequence or sequence. It is to be understood that the data so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or device comprising a sequence of steps or elements is not necessarily limited to the expressly listed instead, may include other steps or elements not explicitly listed or inherent to the process, method, product or apparatus.

Example 1:

As shown in Figures 1-8, the embodiment of this specification provides a terminal simulator for a low-orbit satellite constellation communication system. The terminal simulator is used to simulate multiple terminals communicating with satellites, and the terminal simulator communicates with satellites. Multiple access methods include time division multiple access, frequency division multiple access, code division multiple access, space division multiple access, or a combination of several. The terminal simulator includes terminal uplink and receiving parameter simulation module 1, local pps signal synchronization module 2 , the spread spectrum transmitting module 3 and the spread spectrum receiving module 4, the terminal uplink and receiving parameter simulation module 1 is used to output the multiple access control signal for the terminal uplink and receiving corresponding to the set multiple access mode to control the spread spectrum transmitting module 3 and the spread spectrum receiving module 4 work according to the multiple access mode. The spread spectrum receiving module 4 is used to receive the multiple access control signal and the downlink signal sent by the satellite and demodulate the downlink signal sent by the satellite according to the multiple access control signal. The spread spectrum transmitting module 3 It is used to receive the multiple access control signal and output the uplink signal to the satellite, and the local pps signal synchronization module 2 is used to output the local pps signal to the terminal uplink and receiving parameter simulation module 1.

Specifically, the multiple access control signal includes a multiple access control signal for terminal uplink and a multiple access control signal for terminal reception, and the spread spectrum transmitting module 3 receives the multiple access control signal for terminal uplink and outputs the uplink signal to the satellite, The spread spectrum receiving module 4 receives the multiple access control signal for the terminal to receive and the downlink signal sent by the satellite, and demodulates the downlink signal from the satellite according to the multiple access control signal for the terminal to receive.

Specifically, the principles of time division multiple access, frequency division multiple access, code division multiple access, and space division multiple access are as follows:

Time division multiple access is to divide time into periodic frames on a broadband wireless carrier, and each frame is divided into several time slots (no matter the frames or time slots are non-overlapping), each time slot is a communication Channel, assigned to a user. Multiple users are allowed to use the same frequency or code address to access the communication system and communicate with satellites in different time slices (time slots).

Frequency division multiple access divides the frequency band into several channels, and at the same time, multiple users with different addresses use different carriers (channels) to realize multiple access connections. Only one user's business information can be transmitted at the same time in one frequency channel. Each user uses channels of different frequencies, so there is no mutual interference.

Code division multiple access is an address distinguished by different address codes. Each user can use the same frequency band for communication at the same time by using a different address code.

Space-division multiple access uses space division to form different channels, and the beams of the antenna on the satellite are directed to different areas on the earth's surface. Users in different areas on the ground work at the same time, even if they use the same frequency, there will be no interference between them.

It should be noted that in the prior art, terminal simulators used in low-orbit satellite communication systems generally use code division multiple access to communicate with satellites, and the number of users is affected by the number of pseudo-random codes. At the same time, the system can The number of access users is small, and the test efficiency of the simulated satellite constellation communication system is low.

Therefore, by setting up a new type of terminal emulator in this application, multiple multiple access methods such as time division multiple access, frequency division multiple access, code division multiple access, and space division multiple access can be used to realize the simulation between multiple terminals and satellites. communication, so that the communication capacity of the satellite constellation communication system can be improved from multiple perspectives of time, frequency, address and space, and the number of terminals that can be simulated by the terminal simulator is greatly increased, thereby increasing the number of users that the satellite constellation communication system can access , and then can simulate and test the satellite constellation communication system that adopts different multiple access methods for communication and has a large number of users, improves the test efficiency of the satellite constellation communication system, and solves the problem of using code division multiple access methods in the prior art to achieve communication with different users. For inter-terminal communication, the number of accessible users is too small and the test efficiency of the communication system is low.

Preferably, the multiple access control signal output by the terminal uplink and receiving parameter simulation module 1 includes a time slot control signal, a carrier frequency control signal, a pseudocode frequency control signal and a pseudocode generator polynomial.

Preferably, as shown in Figure 2, the terminal uplink and receiving parameter simulation module 1 includes a read address control module 11, a terminal uplink and receive parameter ROM 12 and a terminal uplink and receive parameter analysis module 13, and the read address control module 11 is used to Output the address to the terminal uplink and receive parameter ROM 12, the local pps signal is input to the terminal uplink and receive parameter analysis module 13, the terminal uplink and receive parameter analysis module 13 is used to read and analyze the address corresponding to the terminal uplink and receive parameter ROM 12 Multiple address parameters to output corresponding multiple address control signals.

Specifically, the read address control module 11 changes the address value of the read address control module 11 under the control of the output data of the terminal uplink and receiving parameter ROM 12, and the terminal uplink and receiving parameter ROM12 stores parameters related to the multiple access mode, Such as time slot allocation, pseudo code polynomial, pseudo code initial phase, pseudo code frequency, carrier frequency, etc., terminal uplink and receiving parameter ROM 12 outputs multiple access parameters according to the read address, terminal uplink and receiving parameter analysis module 13 After the parameters are analyzed, the time slot control signal, pseudo code polynomial and initial phase, pseudo code NCO control word, carrier NCO control word and channel selection signal are output.

Specifically, the time slot control signal includes the terminal uplink time slot control signal and the terminal receiving time slot control signal, the pseudo code polynomial and the initial phase include the terminal uplink pseudo code polynomial and the initial phase and the terminal receiving pseudo code polynomial and the initial phase, the pseudo code NCO The control word includes the terminal uplink pseudo code NCO control word and the terminal receiving pseudo code NCO control word, the carrier NCO control word includes the terminal uplink carrier NCO control word and the terminal receiving carrier NCO control word, the channel selection signal includes the terminal uplink channel selection signal and the terminal receiving Channel selection signal.

Among them, the terminal uplink time slot control signal, terminal uplink pseudocode polynomial and initial phase, terminal uplink pseudocode NCO control word, terminal uplink carrier NCO control word and terminal uplink channel selection signal are used to output to the spread spectrum transmitting module 3; The time slot control signal, the terminal receiving pseudo code polynomial and the terminal receiving initial phase, the terminal receiving pseudo code NCO control word, the terminal receiving carrier NCO control word and the terminal receiving channel selection signal are output to the spread spectrum receiving module 4 .

The working process of the terminal uplink and receiving parameter simulation module 1 is shown in Figure 3. First, the terminal uplink and receiving parameter ROM 12 is initialized through the coe file at the beginning of power-on of the low-orbit satellite constellation communication system to store multiple access parameters, and the terminal The read address addr of the uplink and receiving parameter ROM 12 is assigned an initial value of zero, and then enters the judgment and loops to judge whether addr is less than or equal to the maximum address that can be read by the terminal uplink and receiving parameter ROM 12, and if so, read the terminal uplink And receive the content pointed to by the address addr in the parameter ROM 12, that is, the multiple address parameter, and analyze the read multiple address parameter through the terminal uplink and receive parameter analysis module 13, and output the control signal, which is used for the terminal uplink and receive The time slot control signal, pseudo code polynomial and initial phase, pseudo code NCO control word, carrier NCO control word and channel selection signal, and then add one to the value of the read address addr and re-judge; if not, read The value of address addr is set to zero and judged again.

Preferably, the spread spectrum transmission module 3 includes a Doppler compensation and delay control module 31, and the Doppler compensation and delay control module 31 is used to compensate Doppler dynamics and satellite-ground distance delay output terminal uplink pseudo code NCO control word and terminal The uplink carrier NCO control word is used to modulate the corresponding multiple access control signal for the uplink of the terminal.

Specifically, the spread spectrum transmitting module 3 also includes: terminal uplink encoding module, terminal uplink pseudocode NCO, pseudocode generator, shaping filter, terminal uplink carrier NCO, sine table, cosine table, DAC and channel selection module.

Specifically, the spread spectrum transmission module 3 is used to compensate Doppler dynamics and satellite-ground distance delay through the Doppler compensation and delay control module 31, and to spread and modulate the baseband signal output by the terminal uplink encoding module, and output Uplink signal with Doppler dynamic and satellite-to-earth distance delay compensation.

Among them, the terminal uplink encoding module is used to process the original data encoding (such as RS encoding, differential encoding, convolutional encoding, etc.) to generate baseband signals; the terminal uplink pseudocode NCO is used to generate corresponding pseudocode frequency ;The pseudo code generator is used to generate the corresponding pseudo code sequence based on the pseudo code frequency according to the generated polynomial input from the outside and the initial phase, and spread spectrum modulation of the baseband signal; the shaping filter is used to eliminate inter-symbol interference and compress the transmission bandwidth; the terminal uplink carrier NCO is used to generate the corresponding carrier frequency according to the terminal uplink carrier control word; the sine table and cosine table are used to map the corresponding sine signal and cosine signal according to the terminal uplink carrier frequency, and up-convert the baseband signal after spread spectrum modulation Modulation; the DAC and channel selection module are used to select the corresponding radio frequency channel according to the terminal uplink channel selection signal, and convert the up-converted signal into an analog signal and output it through the radio frequency channel.

Preferably, the spread spectrum receiving module 4 includes a capture module 41, and the capture module 41 is used to capture the sampled downlink signal output terminal receiving carrier NCO control word, terminal receiving pseudo code NCO control word and terminal receiving pseudo code phase control signal.

Specifically, the spread spectrum receiving module 4 also includes a code loop module and a carrier loop module, the code loop module is used to output the pseudo code NCO control word received by the terminal, and the carrier loop module is used to output the terminal to receive the carrier NCO control word, so as to realize the 41. The code loop module and the carrier loop module work together to modulate the corresponding multiple access control signal for receiving by the terminal.

Specifically, the spread spectrum receiving module 4 is used to receive downlink signals sent by satellites, perform sampling, capture, and tracking, and demodulate data frames.

Specifically, the spread spectrum receiving module 4 also includes an ADC and a channel selection module, a terminal receiving carrier NCO, a sine table, a cosine table, a terminal receiving pseudocode NCO, a terminal receiving pseudocode generator, a carrier loop module, a code loop module, and a bit synchronization module.

Among them, the ADC and channel selection module are used to select the corresponding radio frequency channel according to the terminal receiving channel selection signal, and then convert the analog signal into a digital signal; the terminal receiving carrier NCO is used to generate the corresponding carrier frequency according to the terminal receiving carrier control word; the sine meter The cosine table and the cosine table are respectively used to map the corresponding sine signal and cosine signal according to the carrier frequency received by the terminal, and strip the carrier of the input signal; the pseudo code NCO received by the terminal is used to generate the corresponding pseudo code frequency according to the pseudo code control word received by the terminal; the terminal The receiving pseudo-code generator is used to generate corresponding pseudo-code sequences according to the terminal receiving pseudo-code frequency and output the leading pseudo-code sequence, real-time pseudo-code sequence and lagging pseudo-code sequence respectively according to the externally input terminal receiving generator polynomial and initial phase. It is used for tracking the pseudo code of the downlink input signal; the carrier loop module is used for carrier tracking, that is, after the carrier is captured, the carrier Doppler frequency deviation will be reduced to a smaller range, and carrier tracking is required at this time, and the output terminal Receive the carrier NOC control word, adjust the carrier frequency received by the terminal, and further reduce the frequency error to achieve correct demodulation; the code ring module is used to track the pseudo code of the input signal through the delay locked loop, and the output terminal receives the pseudo code NCO control word, and adjust the frequency of the pseudo code sequence received by the terminal, so as to realize the correct stripping of the pseudo code of the input signal, so as to realize correct demodulation; the bit synchronization module is used to realize the bit synchronization of the demodulated data, and demodulate the correct data bit .

Specifically, the local pps signal synchronization module 2 tracks the externally input pps signal through a phase-locked loop, and outputs a local pps signal synchronized with it. The externally input pps signal usually comes from the output of the GPS/BD navigation satellite timing module to synchronize the terminal simulator with the universal time UTC.

The multiple access mode of the new terminal emulator of the present application may be any one or any combination of time division multiple access, frequency division multiple access, code division multiple access and space division multiple access. The following is a detailed explanation of the communication process between the new terminal emulator of the present application and the satellite under each multiple access mode and when four multiple access modes are used at the same time:

In the first embodiment, the terminal emulator simulates that i terminals communicate with satellites by means of time division multiple access, as shown in Figure 4, when a satellite communicates with i terminals, all terminals can be in the same beam coverage area, using Same carrier frequency and same pseudocode. First, the communication period is divided into i time slots, in each time slot, the satellite only communicates with the corresponding terminal, that is, in time slot 1, the satellite communicates with terminal 1; in time slot 2, the satellite communicates with terminal 2 ; In time slot i, the satellite communicates with terminal i. Due to the influence of the Doppler frequency offset and the distance between the satellite and the ground, there will be a certain time delay between the satellite sending data and the terminal receiving data, or the terminal sending data and the satellite receiving data, so a period of time is set in each time slot, called for the valid period. During the communication process, it is only necessary to ensure that the satellite or the terminal receives the data within the valid time period. Taking the communication between the satellite and terminal 1 as an example, the satellite simulates Doppler dynamics and the distance between the satellite and the ground, and sends out data frame 1 in time slot 1. After a certain period of delay, terminal 1 receives data frame 1 in the effective period of time slot 1 , the demodulation calculates the Doppler frequency offset and the distance between the satellite and the ground, and compensates, and then sends the data frame 1 in the next time slot 1. After a certain time delay, the satellite receives the data in the effective period of time slot 1 In frame 1, the communication between the satellite and terminal 1 is completed.

In the second embodiment, the terminal emulator simulates that i terminals communicate with satellites by means of frequency division multiple access, as shown in Figure 5, the satellite communicates with j terminals at the same time, and all terminals can be covered by the same beam region and use the same pseudocode, but they use different carrier frequencies. After the satellite simulates the Doppler dynamics and the distance between the satellite and the ground, it uses different carrier frequencies to send data frames 1~j at the same time, and the terminal demodulates the corresponding data frames using their respective carrier frequencies, and calculates the Doppler frequency offset and the distance between the satellite and the ground After compensation, the data frames are sent out with their respective carrier frequencies, and the satellite then demodulates with the corresponding carrier frequency to obtain data frames 1~j, and the satellite completes the communication with each terminal.

In the third embodiment, the terminal emulator simulates that i terminals communicate with the satellite by means of code division multiple access, as shown in Figure 6, the satellite communicates with k terminals at the same time, and all terminals can be covered by the same beam area and use the same carrier frequency, but they use different pseudocodes. The satellite simulates the Doppler dynamics and the distance between the satellite and the ground, uses different pseudo codes to spread the frequency and sends out data frames 1~k at the same time, and the terminal uses their respective pseudo codes to demodulate the corresponding data frames to calculate the Doppler frequency offset and satellite data. After the ground distance is compensated, the respective pseudo codes are used to spread the spectrum and send out data frames, and the satellites demodulate with the corresponding pseudo codes to obtain data frames 1~k, and the satellites complete the communication with each terminal.

In the fourth embodiment, the terminal emulator simulates that i terminals communicate with satellites using space division multiple access, as shown in Figure 7, the satellite communicates with q terminals at the same time, and all terminals use the same carrier frequency Same as pseudocode, but in a different beam coverage area. After the satellite simulates the Doppler dynamics and the distance between the satellite and the ground, it sends data frames 1~q through different radio frequency channels at the same time, and the terminal receives the corresponding data frames in their respective beam coverage areas, and calculates the Doppler frequency offset and the distance between the satellite and the ground After compensation, the data frame is sent out, the satellite receives the data frame 1~q through the corresponding radio frequency channel, and the satellite completes the communication with each terminal.

In the fifth embodiment, the terminal emulator simulates i terminals to communicate with the satellite in a combination of time division multiple access, frequency division multiple access, code division multiple access and space division multiple access, as shown in Figure 8, the communication The system includes i time slots, j carrier frequencies, k pseudo-codes, and q beams. Terminal (i, j, k, q) means that in the i-th time slot, the Code, communicate with the satellite in the qth beam coverage area.

The embodiment of this specification provides a control method for a terminal simulator for a low-orbit satellite constellation communication system. The method is implemented based on the terminal simulator for a low-orbit satellite constellation communication system in Embodiment 1. The method includes:

The control terminal uplink and receiving parameter simulation module 1 initializes the multiple access control signal corresponding to the parameter output related to the multiple access mode, and the multiple access control signal includes a multiple access control signal for terminal uplink and a multiple access control signal for terminal reception;

The terminal simulator simulates multiple terminals according to the multiple access control signal, and multiple terminals use different multiple access parameters to modulate and demodulate the input signal and output signal;

The multiple terminals simulated by the terminal simulator receive the downlink signal sent by the satellite through the spread spectrum receiving module 4 according to their corresponding multiple access parameters, and demodulate the uplink signal according to the multiple access control signal used for terminal reception;

Multiple terminals simulated by the terminal simulator use the spread spectrum transmitting module 3 to compensate the Doppler dynamics and satellite-ground distance delay for the multiple access control signals used for the terminal uplink, and output the terminal uplink pseudo code NCO control word and the terminal uplink carrier NCO control word ;

Multiple terminals simulated by the terminal emulator modulate the terminal uplink pseudocode NCO control word and terminal uplink carrier NCO control word according to their corresponding multiple access parameters to output uplink signals to the satellite.

Specifically, the communication process between the terminal emulator and the satellite is shown in Figure 9. First, the terminal uplink and receiving parameter simulation module 1 in the terminal emulator initializes the parameters related to the multiple access mode, such as the time slot for the terminal uplink and receiving distribution, pseudo code polynomial, pseudo code initial phase, pseudo code frequency, carrier frequency, etc., and output corresponding multiple access control signals according to its parameters; then the terminal emulator simulates multiple terminals according to the multiple access control signals, which use different The input and output signals are modulated and demodulated by the multiple access parameters; each terminal simulated by the terminal simulator receives and demodulates the corresponding downlink signal from the satellite according to its own multiple access parameters; finally, each terminal simulated by the terminal simulator After performing Doppler compensation and delay control, the terminal modulates and outputs uplink signals to satellites according to its own multiple access parameters.

Although the present invention has been described in terms of preferred embodiments, the present invention is not limited to the embodiments described herein, and various changes and changes are included without departing from the scope of the present invention.

In this article, the orientation words such as front, rear, upper, and lower involved are defined by the parts in the drawings and the positions between the parts in the drawings, just for the clarity and convenience of expressing the technical solution. It should be understood that the use of the location words should not limit the scope of protection claimed in this application.

In the case of no conflict, the above-mentioned embodiments and features in the embodiments herein can be combined with each other.

The above disclosure is only a preferred embodiment of the present invention, which certainly cannot limit the scope of rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope of the present invention.

Claims (9)

1. A terminal simulator for a low earth orbit satellite constellation communication system, the terminal simulator is used for simulating a plurality of terminals to communicate with a satellite, the multiple access mode of the terminal simulator communicating with the satellite comprises two or more of time division multiple access, frequency division multiple access, code division multiple access and space division multiple access, the terminal simulator comprises a terminal uplink and receiving parameter simulation module (1), a local pps signal synchronization module (2), a spread spectrum transmitting module (3) and a spread spectrum receiving module (4), the terminal uplink and receiving parameter simulation module (1) is used for outputting a multiple access control signal corresponding to a set multiple access mode and used for terminal uplink and receiving so as to control the spread spectrum transmitting module (3) and the spread spectrum receiving module (4) to work according to the multiple access mode, the spread spectrum receiving module (4) is used for receiving the multiple access control signal and a downlink signal sent by the satellite and demodulating the downlink signal sent by the satellite according to the multiple access control signal, the spread spectrum transmitting module (3) is used for receiving the multiple access control signal and outputting the uplink signal to the satellite, the local pps signal synchronization module (2) is used for outputting the uplink signal and the local simulation parameter (1) sent by the local terminal to the local pps signal synchronization module,

the multiple access control signal output by the terminal uplink and receiving parameter simulation module (1) comprises a time slot control signal, a carrier frequency control signal, a pseudo code frequency control signal and a pseudo code generator polynomial.

2. The terminal simulator for low earth orbit satellite constellation communication system of claim 1, wherein the terminal uplink and reception parameter simulation module (1) comprises a read address control module (11), a terminal uplink and reception parameter ROM (12) and a terminal uplink and reception parameter analysis module (13), the read address control module (11) is configured to output an address to the terminal uplink and reception parameter ROM (12), and the terminal uplink and reception parameter analysis module (13) is configured to read and analyze a multiple access parameter corresponding to the address in the terminal uplink and reception parameter ROM (12) to output a corresponding multiple access control signal.

3. Terminal simulator for low earth orbit satellite constellation communication system according to claim 1, characterized in that the spread spectrum transmission module (3) comprises a doppler compensation and delay control module (31), the doppler compensation and delay control module (31) being adapted to compensate doppler dynamics and satellite to ground distance delay output terminal uplink pseudo code NCO control words and terminal uplink carrier NCO control words to modulate corresponding multiple access control signals for terminal uplink.

4. The terminal simulator for low earth orbit satellite constellation communication system of claim 1, wherein the spread spectrum receiving module (4) comprises an acquisition module (41), and the acquisition module (41) is configured to acquire the sampled downlink signal and output a terminal received carrier NCO control word, a terminal received pseudo code NCO control word and a terminal received pseudo code phase control signal.

5. The terminal simulator for a low earth orbit satellite constellation communication system of claim 1, wherein when a plurality of terminals simulated by the terminal simulator are located in the same beam coverage area and use the same carrier frequency and the same pseudo code, the terminal simulator communicates with the satellite in a time division multiple access manner.

6. The terminal simulator for low earth orbit satellite constellation communication system of claim 1, wherein when a plurality of terminals simulated by the terminal simulator are located in the same beam coverage area and use the same pseudo code and different carrier frequencies, the terminal simulator communicates with the satellite in frequency division multiple access.

7. The terminal simulator for low earth orbit satellite constellation communication system of claim 1, wherein when a plurality of terminals simulated by the terminal simulator are located in the same beam coverage area and use the same carrier frequency and different pseudo codes, the terminal simulator communicates with the satellite in code division multiple access.

8. The terminal simulator for a low earth orbit satellite constellation communication system of claim 1, wherein when a plurality of terminals simulated by the terminal simulator are located in different beam coverage areas and use the same carrier frequency and the same pseudo code, the terminal simulator communicates with a satellite in a space division multiple access manner.

9. A method for controlling a terminal simulator for a low earth orbit satellite constellation communication system, the method being implemented based on the terminal simulator for a low earth orbit satellite constellation communication system according to any one of claims 1-8, the method comprising:

the method comprises the steps that a control terminal uplink and receiving parameter simulation module (1) initializes parameters related to a multiple access mode and outputs corresponding multiple access control signals, wherein the multiple access control signals comprise multiple access control signals used for terminal uplink and multiple access control signals used for terminal receiving;

the terminal simulator simulates a plurality of terminals according to the multiple access control signals, and the plurality of terminals respectively use different multiple access parameters to modulate and demodulate input signals and output signals;

a plurality of terminals simulated by the terminal simulator receive downlink signals sent by a satellite through a spread spectrum receiving module (4) according to corresponding multiple access parameters of the terminals, and demodulate uplink signals according to multiple access control signals received by the terminals;

a plurality of terminals simulated by the terminal simulator output terminal uplink pseudo code NCO control words and terminal uplink carrier NCO control words to a multi-address control signal for terminal uplink compensation Doppler dynamic and satellite-ground distance delay through a spread spectrum transmitting module (3);

and modulating terminal uplink pseudo code NCO control words and terminal uplink carrier NCO control words by a plurality of terminals simulated by the terminal simulator according to corresponding multiple access parameters thereof, and outputting uplink signals to the satellite.

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