CN117394907B - Air-ground communication system based on Beidou satellite communication link - Google Patents

Air-ground communication system based on Beidou satellite communication link Download PDF

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CN117394907B
CN117394907B CN202311703398.0A CN202311703398A CN117394907B CN 117394907 B CN117394907 B CN 117394907B CN 202311703398 A CN202311703398 A CN 202311703398A CN 117394907 B CN117394907 B CN 117394907B
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data
satellite
communication link
acquisition
communication
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CN117394907A (en
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李志敏
李国成
李�真
陈渊博
李雪芹
郭云
王康
谷鹏举
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XI'AN XINYU AVIATION MAINTENANCE ENGINEERING CO LTD
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XI'AN XINYU AVIATION MAINTENANCE ENGINEERING CO LTD
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/18578—Satellite systems for providing broadband data service to individual earth stations
    • H04B7/18584—Arrangements for data networking, i.e. for data packet routing, for congestion control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/18578—Satellite systems for providing broadband data service to individual earth stations
    • H04B7/18586—Arrangements for data transporting, e.g. for an end to end data transport or check
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/18578—Satellite systems for providing broadband data service to individual earth stations
    • H04B7/18597—Arrangements for system physical machines management, i.e. for construction, operations control, administration, maintenance
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0852—Delays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0876—Network utilisation, e.g. volume of load or congestion level
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/16—Threshold monitoring
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/12—Shortest path evaluation
    • H04L45/121—Shortest path evaluation by minimising delays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H04L47/22—Traffic shaping
    • H04L47/225—Determination of shaping rate, e.g. using a moving window
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H04L47/27—Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/08—Testing, supervising or monitoring using real traffic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/0289—Congestion control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
    • H04W40/12—Communication route or path selection, e.g. power-based or shortest path routing based on transmission quality or channel quality
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
    • H04W40/18—Communication route or path selection, e.g. power-based or shortest path routing based on predicted events
    • 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

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  • Signal Processing (AREA)
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  • General Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
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  • Radio Relay Systems (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The invention relates to the technical field of air-ground communication, in particular to an air-ground communication system based on a Beidou satellite communication link, which comprises a monitoring center, wherein the monitoring center is in communication connection with a data acquisition module, a data processing module, a communication link selection module, a link bandwidth estimation module and a jumping window module; the data acquisition module is used for acquiring service data; the data processing module is used for processing the received business data and analyzing the priority value; the communication link selection module is used for acquiring a satellite communication link which meets the preset communication transmission requirement at the current moment; the link bandwidth estimation module is used for carrying out real-time bandwidth estimation on the communication links meeting the preset communication transmission requirements; the jumping window module allocates data transmission quota for the data transmission path, and when the data transmission quota of the data transmission path is full, the new data transmission path is reselected until all the service data transmission is completed; the data transmission efficiency in the satellite communication link is significantly improved.

Description

Air-ground communication system based on Beidou satellite communication link
Technical Field
The invention relates to the technical field of air-ground communication, in particular to an air-ground communication system based on a Beidou satellite communication link.
Background
The communication satellite is generally located in a synchronous orbit of 36000km above the equator, and the satellite communication terminal host computer moves frequently and is greatly affected by the environment and the satellite antenna. Satellite communications have several features:
a) The path attenuation of the satellite channel is larger and is easy to be influenced by environment.
b) The bandwidth is small, which is a scarce resource in satellite communications, and the satellite bandwidth used today is relatively small compared to classical ethernet.
c) Propagation delay, the factor affecting satellite communication delay is more than one, the main one being orbit type. In most cases, the unidirectional propagation delay of the low-rail system is 20-25ms, the unidirectional propagation delay of the medium-rail system is 110-130 ms, the unidirectional propagation delay of the static rail system is 250-280ms, and the system delay is also influenced by factors such as inter-satellite routing, on-satellite processing, buffering and the like.
d) The mobility of the terminal is often such that the satellite communication terminal moves because it is easily affected by the environment and the antenna direction. The possible interruption of satellite communication and a relatively high bit error rate result.
e) The communication cost is high, and the transmission and operation costs of the satellite are high, so that the information cost of satellite communication is relatively high compared with the information cost of communication means such as a wired network.
The comparison document CN116074865A is a transmission configuration method, device and storage medium of an air-ground integrated network, and the optimal value of each parameter in transmission configuration is determined by constructing a first function relation of the combination of throughput and transmission configuration parameters of the air-ground integrated network and solving the first function relation with the aim of maximizing frequency efficiency; therefore, the problem of spectrum efficiency reduction caused by cross-link interference in the air-ground integrated network is solved, and the working efficiency of the air-ground integrated network is improved.
The invention discloses a multipath end-to-end transmission system based on space-to-ground communication and an application method thereof, which are used for reallocating received user data streams according to the quality of a plurality of current channels. The user data is distributed to each channel in proportion through the algorithm for transmission, and simultaneously, the encryption is carried out by utilizing the coupling of a plurality of channels, so that the system throughput is effectively increased, the user privacy is ensured not to be revealed, and the safe transmission of the user data is realized.
In a satellite network with high error rate, smaller bandwidth and higher propagation delay, the satellite network is more prone to congestion in the face of more and more data transmission types and larger data transmission order requirements, and the problem of how to reduce higher data transmission delay while ensuring that service data of a user terminal can be transmitted under low error rate is urgent to solve.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide an air-to-ground communication system based on a Beidou satellite communication link, which comprises a monitoring center, wherein the monitoring center is in communication connection with a data acquisition module, a data processing module, a communication link selection module, a link bandwidth estimation module and a jumping window module;
the data acquisition module is in distributed communication connection with a plurality of satellite terminals through a ground base station and is used for acquiring service data sent by a plurality of edge user terminals and sending the service data to the data processing module;
the data processing module is used for analyzing the processing priority value of the received service data and sequentially transmitting the corresponding service data to the ground base station according to the processing priority value;
when the ground base station receives service data, the ground base station sends path request information to a communication link selection module, wherein the communication link selection module is used for responding to the path request information, acquiring the satellite orbit type and the satellite communication link length of Beidou satellite communication, acquiring a satellite communication link meeting the preset communication transmission requirement at the current moment according to the satellite communication link length, and sending the satellite communication link to a link bandwidth estimation module;
the link bandwidth estimation module is used for carrying out real-time bandwidth estimation on the communication links meeting the preset communication transmission requirements, selecting a data transmission path according to the real-time bandwidth and sending the data transmission path to the ground base station;
the jumping window module is connected with the ground base station and is used for distributing data transmission quota for the data transmission path, after the data transmission quota of the data transmission path is full, the path is abandoned, meanwhile, the ground base station resends the path request information to the communication link selection module, the communication link selection module selects a new data transmission path from the rest communication links, and the like until all the service data transmission is completed.
Further, the process of the data processing module for processing the priority value analysis of the received service data includes:
packaging service data sent by the same edge user terminal into data packets, and acquiring acquisition records of the corresponding edge user terminal, wherein the acquisition records comprise acquisition time, data types and data quantity;
counting the accumulated acquisition times of the corresponding edge user terminals according to the acquisition records of the corresponding edge user terminals, carrying out average value calculation on adjacent acquisition moments to obtain central moments, carrying out time difference calculation between the adjacent acquisition moments to obtain acquisition intervals, correlating the central moments obtained from the same adjacent acquisition moments with the acquisition intervals, setting weight indexes of the acquisition intervals according to the time difference between the central moments of the acquisition intervals and the current moment, generating interval coefficients according to the acquisition intervals and the corresponding weight indexes, and obtaining the acquisition frequency of the corresponding edge user terminals according to the accumulated acquisition times and the interval coefficients;
and obtaining the priority of the edge user terminal according to the data type, the data quantity and the acquisition frequency.
Further, the process of the communication link selection module responding to the path request information to obtain the satellite orbit type and the satellite communication link length of the Beidou satellite communication comprises the following steps:
acquiring a satellite orbit type requiring Beidou satellite communication according to path request information, wherein the satellite orbit type comprises a satellite-ground orbit and an inter-satellite orbit;
downloading ephemeris of a satellite constellation to a communication link selection module, wherein the ephemeris is updated at regular time according to the satellite constellation orbit period;
when the satellite orbit type for Beidou satellite communication is a satellite-ground orbit, acquiring latitude and longitude geographic coordinate information of a ground station and a satellite at the current moment from an ephemeris, constructing a geocentric coordinate system, converting the geographic coordinate into a geocentric coordinate, and calculating the communication link length between a ground base station and the satellite through a linear distance formula in a three-dimensional space under the geocentric coordinate system;
when the satellite orbit type for Beidou satellite communication is inter-satellite orbit, acquiring a satellite A in a low earth orbit layer and a satellite B in a high earth orbit layer in a communication link, and firstly acquiring the length of the communication link between the satellite A in the low earth orbit layer and a ground base station;
acquiring the longitude and latitude of the satellite A point and the longitude and latitude of the satellite B point according to the ephemeris, and acquiring the instantaneous geocentric angle between the satellite A and the satellite B according to the longitude and latitude of the satellite A point and the longitude and latitude of the satellite B point;
acquiring the orbit height of a satellite A and the orbit height of a satellite B according to the ephemeris, and acquiring the link length between the two stars according to the orbit height of the satellite A, the orbit height of the satellite B and the instantaneous geocentric angle between the satellite A and the satellite B;
the satellite orbit type is the total length of the communication link of the inter-satellite orbit is the sum of the length of the communication link of the satellite a in the low earth orbit layer and the ground base station and the length of the inter-double-satellite link.
Further, the process of selecting the satellite communication link meeting the preset communication transmission requirement by the communication link selecting module according to the communication link length includes:
calculating the propagation delay at the current moment according to the length of the communication link;
setting a propagation delay threshold value, and comparing the propagation delay of the communication link with the propagation delay threshold value;
when the propagation delay of the communication link is greater than the propagation delay threshold, rejecting the communication link;
and when the propagation delay of the communication link is smaller than or equal to a propagation delay threshold value, marking the communication link as a candidate communication link.
Further, the process of the link bandwidth estimation module for performing real-time bandwidth estimation on the communication link meeting the preset communication transmission requirement includes:
the link bandwidth estimation module sends a detection data packet with a fixed time interval to a satellite through a candidate communication link, determines the data length of the detection data packet, sends acknowledgement response data to the link bandwidth estimation module after the satellite receives the detection data packet, records the time when the link bandwidth estimation module receives the acknowledgement response data, and acquires a bandwidth sample value according to the data length of the detection data packet, the time when the acknowledgement response packet is received and the propagation delay of the candidate communication link;
and when the link bandwidth estimation module receives one piece of confirmation response data to estimate the link bandwidth to obtain one bandwidth sample value, the EWMA filter is utilized to carry out filtering processing on the bandwidth sample value to obtain a stable bandwidth estimation value at the current moment.
Further, the process of selecting the data transmission path by the link bandwidth estimation module according to the real-time bandwidth and sending the data transmission path to the ground base station includes:
and acquiring the stable bandwidth estimated value of each candidate communication link at the current moment, and selecting the first k communication links with the largest stable bandwidth estimated values as data transmission paths.
Further, the process of allocating the data transmission quota for the data transmission path by the jitter window module includes:
dividing a data packet received by a ground base station into k sub-data packets, distributing a corresponding data transmission path for each sub-data packet, setting a jumping window before the sub-data packet is transmitted, determining the initial window length of the jumping window, acquiring the number of data bytes transmitted at the current moment according to the initial window length by the sub-data packet, feeding back acknowledgement response data to a jumping window module after the satellite successfully receives the data, determining the round trip delay of the current data according to the acknowledgement response data and the transmission time of the data by the jumping window module, dynamically adjusting and increasing the number of data bytes transmitted at the next moment according to the round trip delay, and so on until the data dispatch in the sub-data packet is completed.
Further, the process of dynamically adjusting and increasing the number of data bytes of the data transmission at the next moment by the jitter window module according to the round trip delay includes:
setting a delay threshold value, and comparing the round trip delay with the delay threshold value;
if the round trip delay is greater than the delay threshold, discarding the current data transmission path by the sub-data packet, sending path request information to the ground base station, and retransmitting the path request information to the communication link selection module by the ground base station, wherein the communication link selection module selects a new data transmission path from the rest communication links;
if the round trip delay is less than or equal to the delay threshold, acquiring the delay variation amplitude of the current moment;
setting a time delay variation amplitude threshold value, and comparing the time delay variation amplitude value with the time delay variation amplitude threshold value;
when the time delay change amplitude is larger than the time delay change amplitude threshold, discarding the current data transmission path by the sub-data packet, sending path request information to the ground base station, and retransmitting the path request information to the communication link selection module by the ground base station, wherein the communication link selection module selects a new data transmission path from the rest communication links;
when the time delay change amplitude is smaller than or equal to the time delay change amplitude threshold, the initial window length at the next moment when data transmission is performed according to the time delay change amplitude is increased in an exponential form, and the like until all data in the sub-data packet are transmitted.
Compared with the prior art, the invention has the beneficial effects that:
1. the data acquisition module acquires the data type, the data quantity and the acquisition frequency of the transmitted service data of the edge user terminal according to the acquisition record of the edge user terminal, acquires the service data processing priority of the edge user terminal, and sequentially transmits the corresponding service data to the ground base station according to the size of the service data processing priority, so that the data processing is more hierarchical and well-suited;
2. when the ground base station receives service data, the ground base station sends path request information to a communication link selection module, wherein the communication link selection module is used for responding to the path request information, acquiring the satellite orbit type and the satellite communication link length of Beidou satellite communication, acquiring a satellite communication link meeting the preset communication transmission requirement at the current moment according to the satellite communication link length, and sending the satellite communication link to a link bandwidth estimation module; the link bandwidth estimation module carries out real-time bandwidth estimation on the communication link meeting the preset communication transmission requirement, and selects a data transmission path according to the real-time bandwidth and sends the data transmission path to the ground base station, so that the data transmission efficiency is effectively improved;
3. the EWMA filter is utilized to carry out filtering treatment on the bandwidth sample value to obtain a stable bandwidth estimated value at the current moment, so that the deviation rate of real-time bandwidth estimation of a communication link is effectively reduced, and the error rate of transmission of the channel link is reduced;
4. the jitter window module allocates data transmission quota for the data transmission path, dynamically adjusts and increases the number of data bytes of data transmission at the next moment according to the round trip time delay, and dynamically adjusts and increases the number of data bytes of data transmission on the basis of not affecting the data transmission speed of the path while avoiding the problem of low transmission efficiency caused by too many data packets transmitted by the same path and too long continuous transmission time, thereby further accelerating the data transmission efficiency of the satellite communication link.
Drawings
Fig. 1 is a schematic diagram of an air-ground communication system based on a beidou satellite communication link in an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application, taken in conjunction with the accompanying drawings, clearly and completely describes the technical solutions of the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.
As shown in fig. 1, the air-ground communication system based on the Beidou satellite communication link comprises a monitoring center, wherein the monitoring center is in communication connection with a data acquisition module, a data processing module, a communication link selection module, a link bandwidth estimation module and a jumping window module;
the data acquisition module is in distributed communication connection with a plurality of satellite terminals through a ground base station and is used for acquiring service data sent by a plurality of edge user terminals and sending the service data to the data processing module;
the data processing module is used for analyzing the processing priority value of the received service data and sequentially transmitting the corresponding service data to the ground base station according to the processing priority value;
when the ground base station receives service data, the ground base station sends path request information to a communication link selection module, wherein the communication link selection module is used for responding to the path request information, acquiring the satellite orbit type and the satellite communication link length of Beidou satellite communication, acquiring a satellite communication link meeting the preset communication transmission requirement at the current moment and sending the satellite communication link to a link bandwidth estimation module;
the link bandwidth estimation module is used for carrying out real-time bandwidth estimation on the communication links meeting the preset communication transmission requirements, selecting a data transmission path according to the real-time bandwidth and sending the data transmission path to the ground base station;
the jumping window module is connected with the ground base station and is used for distributing data transmission quota for the data transmission path, after the data transmission quota is used up, the path is abandoned, meanwhile, the ground base station retransmits path request information to the communication link selection module, and the communication link selection module selects a new data transmission path from the rest communication links and the like until all service data transmission is completed.
It should be further noted that, in the implementation process, the process of performing the processing priority value analysis on the received service data by the data processing module includes:
packaging service data sent by the same edge user terminal into data packets, and acquiring acquisition records of the corresponding edge user terminal, wherein the acquisition records comprise acquisition time, data types and data quantity;
counting the accumulated acquisition times YW of the corresponding edge user terminals according to the acquisition records of the corresponding edge user terminals, carrying out average calculation on adjacent acquisition moments to obtain central moments, carrying out time difference calculation on the adjacent acquisition moments to obtain acquisition intervals, and the like, marking a plurality of acquisition intervals as T1, T2, T3, & gt, T (i-1), associating the central moments obtained from the same adjacent acquisition moment with the acquisition interval T (i-1), and carrying out time difference calculation on the central moments of the acquisition intervals T (i-1) according to the central moments of the acquisition intervals T (i-1)The time difference at the previous time t is provided with a weight index beta (i-1), and the calculation formula of the weight index beta (i-1) is as follows:；
wherein a1 is a weight factor;the central moment;
and generating an interval coefficient U1 according to a plurality of acquisition intervals T1, T2, T3, & gt, T (i-1) and a corresponding weight index beta (i-1), wherein the calculation formula of the interval coefficient U1 is as follows:；
acquiring the acquisition frequency P of the corresponding edge user terminal according to the accumulated acquisition times YW and the interval coefficient U1, wherein the calculation formula of the acquisition frequency P is as follows:；
wherein a2 and a3 are weight factors;
marking the data size of a data packet sent by a current corresponding edge user terminal as K1, acquiring a service level protocol to which the data type of the current data packet of the current edge device belongs, setting the importance level of the data type based on the service level protocol, classifying different types of data according to the agreed service degree and performance requirements, and ensuring that the requirements of users are met and acquiring the importance XL of the data type of the current data packet;
according to the importance XL of the data type, the data quantity K1 and the acquisition frequency P, the priority G of the edge user terminal is obtained, and the calculation formula of the priority G is as follows:；
wherein a4, a5 and a6 are weight factors.
It should be further noted that, in the implementation process, the process of obtaining the satellite orbit type and the satellite communication link length of the Beidou satellite communication required by the communication link selection module in response to the path request information includes:
acquiring satellite orbit types needing Beidou satellite communication according to path request information, wherein the satellite orbit types comprise an LEO satellite orbit, a GEO satellite orbit and a LEO satellite and GEO satellite double-satellite orbit; LEO satellite orbit has advantages of low delay, high speed and shorter orbit period, is suitable for some applications requiring fast data transmission and high density coverage, while GEO satellite orbit can provide long-time stable communication and observation service, is suitable for applications requiring wide area coverage and stable link, and the selection of different satellite orbits depends on specific application requirements of a user side in path request information.
Firstly, downloading ephemeris of a satellite constellation to a communication link selection module, wherein the ephemeris is updated periodically according to satellite constellation orbit period, and then, when the length of an inter-satellite communication link is calculated, satellite information on different track paths is read from the ephemeris;
when the satellite orbit type for Beidou satellite communication is LEO satellite orbit or GEO satellite orbit, latitude and longitude geographic coordinate information of a ground station and a satellite is obtained, a geocentric coordinate system is constructed, the geographic coordinate is converted into geocentric coordinate, under the geocentric coordinate system, the communication link length dzp between a ground base station and the satellite is calculated through a linear distance formula in a three-dimensional space, and the calculation formula of the communication link length dzp is as follows:；
wherein (x 1, y1, z 1) and (x 2, y2, z 2) are the coordinates of the ground station and satellite, respectively, in the geocentric coordinate system;
when the satellite orbit type for Beidou satellite communication is the double-satellite orbit of LEO satellite and GEO satellite, taking LEO satellite A and GEO satellite B in different layers as examples, firstly acquiring the communication link length dzp1 of LEO satellite A and ground base station, wherein the calculation formula of the communication link length dzp1 is as follows:；
wherein (x 1, y1, z 1) and (x 3, y3, z 3) are the coordinates of the ground station and LEO satellite a, respectively, under the geocentric coordinate system;
acquiring the longitude and latitude of the satellite point below the satellite A of LEO satellite according to the ephemerisAnd the satellite point under GEO satellite B is warp and weft ∈ ->And warp and weft according to the satellite point of LEO satellite A>And the satellite under-satellite point longitude and latitude of GEO satellite BThe instantaneous geocentric angle theta between the LEO satellite A and the GEO satellite B is obtained, and the calculation formula of the instantaneous geocentric angle theta is as follows:；
acquiring the orbit height hA of the LEO satellite A and the orbit height hB of the GEO satellite B according to the ephemeris; obtaining a double-star inter-link length dzp2 based on the orbital heights hA and hB of the LEO satellite a and the GEO satellite B and the instantaneous geocentric angle θ between the LEO satellite a and the GEO satellite B; the calculation formula of the double-star inter-link length dzp is as follows:；
wherein R is the earth radius;
the calculation formula of the total length dzp of the communication link when the satellite orbit type is the double-star orbit of the LEO satellite and the GEO satellite is dzp = dzp1+ dzp2;
it should be further noted that, in the implementation process, the process of selecting, by the communication link selection module, a communication link meeting a preset communication transmission requirement according to a communication link length of the satellite includes:
the propagation delay tcd at the current moment is calculated according to the length of the communication link, and the calculation formula of the propagation delay tcd is as follows:；
wherein tcd is propagation delay; dzp is the length of the communication link at the current time; c is the speed of light;
setting a propagation delay threshold tcdM, and comparing the propagation delay tcd of the communication link with the propagation delay threshold tcdM;
when the propagation delay tcd of the communication link is larger than the propagation delay threshold tcdM, rejecting the communication link;
when the propagation delay tcd of the communication link is less than or equal to the propagation delay threshold tcdM, the communication link is marked as a candidate communication link.
It should be further noted that, in the implementation process, the process of performing real-time bandwidth estimation on the communication link meeting the preset communication transmission requirement by the link bandwidth estimation module includes:
the link bandwidth estimation module sends a detection data packet with a fixed time interval tgD to a satellite through a candidate communication link, the data length of the detection data packet is Lg, after the satellite receives the detection data packet, confirmation response data is sent to the link bandwidth estimation module, when the link bandwidth estimation module receives the confirmation response data, the time tg of receiving the confirmation response packet is recorded, a bandwidth sample value Bg is obtained according to the data length Lg of the detection data packet, the time tg of receiving the confirmation response packet and the propagation delay tcd of the candidate communication link, and the calculation formula of the bandwidth sample value Bg is as follows:；
wherein t (g-1) is the time when the link bandwidth estimation module receives the last acknowledgement response data;
the link bandwidth estimation module estimates the link bandwidth every time it receives a confirmation response data to obtain a bandwidth sample value, and in digital signal processing, the sample values have certain randomness, and the sample data may be affected by factors such as network conditions, equipment performance, measurement errors and the like, so that fluctuation and instability of sampling values are caused, and the bandwidth condition of the current communication link cannot be accurately reflected;
the EWMA filter in digital signal processing is used for filtering sampling bandwidth samples in a period of time, the EWMA filter is used for giving higher weight to the latest sampling value, the old sampling value is gradually attenuated by the EWMA filter, the weight distribution mode enables the filter to pay more attention to the latest data, the filter is more sensitive to rapidly changing signals, and at the same time, the filter also has a certain memory to reflect the change trend in a longer time range by gradually attenuating the weight of the old data, the fluctuation of the sampling value can be reduced by using the EWMA filter, and a stable bandwidth estimated value is obtainedBandwidth estimation +.>The calculation formula of (2) is as follows: />，，/>；
Wherein,is a stationary bandwidth estimate at tg; b (g-1) is a bandwidth sample value at time t (g-1); βg is a filter gain weight value, and Lg is the data length of the probe data packet sent at tg; tgD is a fixed time interval for transmitting probe packets; />Is the cut-off frequency of the filter.
It should be further noted that, in the implementation process, the process of selecting the data transmission path by the link bandwidth estimation module according to the real-time bandwidth and sending the data transmission path to the ground base station includes:
obtaining a stationary bandwidth estimate for a current time of each candidate communication linkAnd selecting the first k communication links with the largest stationary bandwidth estimation values as data transmission paths.
It should be further noted that, in the implementation process, the process of allocating the data transmission quota for the data transmission path by the jitter window module includes:
dividing a data packet received by a ground base station into k sub-data packets, distributing a corresponding data transmission path for each sub-data packet, setting a jumping window before the sub-data packet is transmitted, determining the initial window length WLi of the jumping window, acquiring the data byte number Li of data transmission at the current moment according to the initial window length WLi by the sub-data packet, feeding back acknowledgement response data to a jumping window module after the satellite successfully receives the data, determining the round trip delay Ttrans of the current data according to the acknowledgement response data and the transmission time of the data by the jumping window module, dynamically adjusting and increasing the data byte number L (i+1) of data transmission at the next moment according to the round trip delay Ttrans, and the like until the data distribution in the sub-data packet is completed.
It should be further noted that, in the implementation process, the jitter window module dynamically adjusts and increases the number of data bytes L (i+1) of the data transmission at the next time according to the round trip delay Ttrans, and so on, until the data distribution in the sub-data packet is completed, the process includes:
setting a delay threshold XTtrans, and comparing the round trip delay Ttrans with the delay threshold XTtrans;
if the round trip delay Ttrans is greater than the delay threshold value XTtrans, the sub-data packet abandons the current data transmission path, and sends the path request information to the ground base station, and the ground base station resends the path request information to the communication link selection module, wherein the communication link selection module selects a new data transmission path from the rest communication links;
if the round trip delay Ttrans is less than or equal to the delay threshold XTtrans, calculating a delay variation amplitude Fi at the current moment, wherein a calculation formula of the delay variation amplitude Fi is as follows:；
where Ttrans (i) is the round trip delay of the transmission data at the present moment; ttrans (i-1) is the round trip delay of the transmission data at the previous time;
setting a time delay variation amplitude threshold XFi, and comparing the time delay variation amplitude Fi with the time delay variation amplitude threshold XFi;
when the time delay change amplitude Fi is larger than the time delay change amplitude threshold XFi, discarding the current data transmission path by the sub-data packet, sending path request information to the ground base station, and retransmitting the path request information to a communication link selection module by the ground base station, wherein the communication link selection module selects a new data transmission path from the rest communication links;
when the delay variation amplitude Fi is smaller than or equal to the delay variation amplitude threshold XFi, the initial window length WL (i+1) at the next time when the data transmission is performed increases exponentially until all the data transmission in the sub-data packet is completed, where the calculation formula of the initial window length WL (i+1) at the next time is as follows:；
WLi is the initial window length at the current time; WL (i+1) is the initial window length at the next time.
The above embodiments are only for illustrating the technical method of the present invention and not for limiting the same, and it should be understood by those skilled in the art that the technical method of the present invention may be modified or substituted without departing from the spirit and scope of the technical method of the present invention.

Claims (5)

1. The air-ground communication system based on the Beidou satellite communication link comprises a monitoring center and is characterized in that the monitoring center is in communication connection with a data acquisition module, a data processing module, a communication link selection module, a link bandwidth estimation module and a jumping window module;
the data acquisition module is in distributed communication connection with a plurality of satellite terminals through a ground base station and is used for acquiring service data sent by a plurality of edge user terminals and sending the service data to the data processing module;
the data processing module is used for analyzing the processing priority value of the received service data and sequentially transmitting the corresponding service data to the ground base station according to the processing priority value;
the process of processing the priority value analysis of the received business data by the data processing module comprises the following steps:
packaging service data sent by the same edge user terminal into data packets, and acquiring acquisition records of the corresponding edge user terminal, wherein the acquisition records comprise acquisition time, data types and data quantity;
counting the accumulated acquisition times of the corresponding edge user terminals according to the acquisition records of the corresponding edge user terminals, carrying out average value calculation on adjacent acquisition moments to obtain central moments, carrying out time difference calculation between the adjacent acquisition moments to obtain acquisition intervals, correlating the central moments obtained from the same adjacent acquisition moments with the acquisition intervals, setting weight indexes of the acquisition intervals according to the time difference between the central moments of the acquisition intervals and the current moment, generating interval coefficients according to the acquisition intervals and the corresponding weight indexes, and obtaining the acquisition frequency of the corresponding edge user terminals according to the accumulated acquisition times and the interval coefficients;
acquiring the priority of the edge user terminal according to the data type, the data quantity and the acquisition frequency;
the process of obtaining the priority of the edge user terminal according to the data type, the data quantity and the acquisition frequency comprises the following steps:
packaging service data sent by the same edge user terminal into data packets, and acquiring acquisition records of the corresponding edge user terminal, wherein the acquisition records comprise acquisition time, data types and data quantity;
counting the accumulated acquisition times YW of the corresponding edge user terminals according to the acquisition records of the corresponding edge user terminals, carrying out average calculation on adjacent acquisition moments to obtain central moments, carrying out time difference calculation on the adjacent acquisition moments to obtain acquisition intervals, and the like, marking a plurality of acquisition intervals as T1, T2, T3, & gt, T (i-1), associating the central moments obtained from the same adjacent acquisition moments with the acquisition intervals T (i-1), and setting a weight index beta (i-1) according to the time difference between the central moment of the acquisition interval T (i-1) and the current moment T, wherein the calculation formula of the weight index beta (i-1) is as follows:；
wherein a1 is a weight factor;the central moment;
and generating an interval coefficient U1 according to a plurality of acquisition intervals T1, T2, T3, & gt, T (i-1) and a corresponding weight index beta (i-1), wherein the calculation formula of the interval coefficient U1 is as follows:；
acquiring the acquisition frequency P of the corresponding edge user terminal according to the accumulated acquisition times YW and the interval coefficient U1, wherein the calculation formula of the acquisition frequency P is as follows:；
wherein a2 and a3 are weight factors;
marking the data size of a data packet sent by a current corresponding edge user terminal as K1, acquiring a service level protocol to which the data type of the current data packet of the current edge device belongs, setting the importance level of the data type based on the service level protocol, classifying different types of data according to the agreed service degree and performance requirements, and ensuring that the requirements of users are met and acquiring the importance XL of the data type of the current data packet;
according to the importance XL of the data type, the data quantity K1 and the acquisition frequency P, the priority G of the edge user terminal is obtained, and the calculation formula of the priority G is as follows:；
wherein a4, a5 and a6 are weight factors;
in response to receiving the service data, the ground base station sends path request information to a communication link selection module, wherein the communication link selection module is used for responding to the path request information, acquiring a satellite orbit type and a satellite communication link length of Beidou satellite communication, acquiring a satellite communication link meeting preset communication transmission requirements at the current moment according to the satellite communication link length, and sending the satellite communication link to a link bandwidth estimation module;
the link bandwidth estimation module is used for carrying out real-time bandwidth estimation on the communication links meeting the preset communication transmission requirements, selecting a data transmission path according to the real-time bandwidth and sending the data transmission path to the ground base station;
the process of carrying out real-time bandwidth estimation on the communication link meeting the preset communication transmission requirement by the link bandwidth estimation module comprises the following steps:
the link bandwidth estimation module sends a detection data packet with a fixed time interval to a satellite through a candidate communication link, determines the data length of the detection data packet, sends acknowledgement response data to the link bandwidth estimation module after the satellite receives the detection data packet, records the time when the link bandwidth estimation module receives the acknowledgement response data, and acquires a bandwidth sample value according to the data length of the detection data packet, the time when the acknowledgement response packet is received and the propagation delay of the candidate communication link;
when the link bandwidth estimation module receives a confirmation response data to estimate the link bandwidth to obtain a bandwidth sample value, filtering the bandwidth sample value by using an EWMA filter to obtain a stable bandwidth estimation value at the current moment;
the jumping window module is connected with the ground base station and is used for distributing data transmission quota for the data transmission path, discarding the data transmission quota of the data transmission path after the data transmission quota is full, and simultaneously, retransmitting path request information to the communication link selection module by the ground base station, wherein the communication link selection module selects a new data transmission path from the rest communication links, and the like until all service data transmission is completed;
the process of allocating the data transmission quota for the data transmission path by the jitter window module comprises the following steps:
dividing a data packet received by a ground base station into k sub-data packets, distributing a corresponding data transmission path for each sub-data packet, setting a jumping window before the sub-data packet is transmitted, determining the initial window length of the jumping window, acquiring the number of data bytes transmitted at the current moment according to the initial window length by the sub-data packet, feeding back acknowledgement response data to a jumping window module after the satellite successfully receives the data, determining the round trip delay of the current data according to the acknowledgement response data and the transmission time of the data by the jumping window module, dynamically adjusting and increasing the number of data bytes transmitted at the next moment according to the round trip delay, and so on until the data dispatch in the sub-data packet is completed.
2. The space-to-ground communication system based on Beidou satellite communication link according to claim 1, wherein the process of obtaining the satellite orbit type and the satellite communication link length required for Beidou satellite communication by the communication link selection module in response to the path request information comprises:
acquiring a satellite orbit type requiring Beidou satellite communication according to path request information, wherein the satellite orbit type comprises a satellite-ground orbit and an inter-satellite orbit;
downloading ephemeris of a satellite constellation to a communication link selection module, wherein the ephemeris is updated at regular time according to the satellite constellation orbit period;
when the satellite orbit type for Beidou satellite communication is a satellite-ground orbit, acquiring latitude and longitude geographic coordinate information of a ground station and a satellite at the current moment from an ephemeris, constructing a geocentric coordinate system, converting the geographic coordinate into a geocentric coordinate, and calculating the communication link length between a ground base station and the satellite through a linear distance formula in a three-dimensional space under the geocentric coordinate system;
when the satellite orbit type for Beidou satellite communication is inter-satellite orbit, acquiring a satellite A in a low earth orbit layer and a satellite B in a high earth orbit layer in a communication link, and firstly acquiring the length of the communication link between the satellite A in the low earth orbit layer and a ground base station;
acquiring the longitude and latitude of the satellite A point and the longitude and latitude of the satellite B point according to the ephemeris, and acquiring the instantaneous geocentric angle between the satellite A and the satellite B according to the longitude and latitude of the satellite A point and the longitude and latitude of the satellite B point;
acquiring the orbit height of a satellite A and the orbit height of a satellite B according to the ephemeris, and acquiring the link length between the two stars according to the orbit height of the satellite A, the orbit height of the satellite B and the instantaneous geocentric angle between the satellite A and the satellite B;
the satellite orbit type is the total length of the communication link of the inter-satellite orbit, which is the sum of the communication link length of the satellite a in the low earth orbit layer and the ground base station and the double-star inter-satellite link length.
3. The space-to-ground communication system based on Beidou satellite communication link according to claim 2, wherein the process of selecting the satellite communication link meeting the preset communication transmission requirement by the communication link selection module according to the communication link length comprises the following steps:
calculating the propagation delay at the current moment according to the length of the communication link;
setting a propagation delay threshold value, and comparing the propagation delay of the communication link with the propagation delay threshold value;
when the propagation delay of the communication link is greater than the propagation delay threshold, rejecting the communication link;
and when the propagation delay of the communication link is smaller than or equal to a propagation delay threshold value, marking the communication link as a candidate communication link.
4. A space-to-ground communication system based on a Beidou satellite communication link according to claim 3, wherein the process of selecting a data transmission path by the link bandwidth estimation module according to the real-time bandwidth and transmitting the data transmission path to the ground base station comprises:
and acquiring the stable bandwidth estimated value of each candidate communication link at the current moment, and selecting the first k communication links with the largest stable bandwidth estimated values as data transmission paths.
5. The space-to-ground communication system based on Beidou satellite communication link according to claim 4, wherein the process of dynamically adjusting and increasing the number of data bytes of data transmission at the next time according to the round trip delay by the jitter window module comprises:
setting a delay threshold value, and comparing the round trip delay with the delay threshold value;
if the round trip delay is greater than the delay threshold, discarding the current data transmission path by the sub-data packet, sending path request information to the ground base station, and retransmitting the path request information to the communication link selection module by the ground base station, wherein the communication link selection module selects a new data transmission path from the rest communication links;
if the round trip delay is less than or equal to the delay threshold, acquiring the delay variation amplitude of the current moment;
setting a time delay variation amplitude threshold value, and comparing the time delay variation amplitude value with the time delay variation amplitude threshold value;
when the time delay change amplitude is larger than the time delay change amplitude threshold, discarding the current data transmission path by the sub-data packet, sending path request information to the ground base station, and retransmitting the path request information to the communication link selection module by the ground base station, wherein the communication link selection module selects a new data transmission path from the rest communication links;
when the time delay change amplitude is smaller than or equal to the time delay change amplitude threshold, the initial window length at the next moment when data transmission is performed according to the time delay change amplitude is increased in an exponential form, and the like until all data in the sub-data packet are transmitted.
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