CN112436916B - Multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking - Google Patents
Multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking Download PDFInfo
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Abstract
The invention relates to a multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking, which is used for determining the access mode of each ground terminal, so that at least one ground terminal is accessed to the satellite, and one ground terminal is accessed to the unmanned aerial vehicle, thereby completing networking; to access satellites or drones. After networking is completed, determining the uplink rate and the downlink rate of each ground terminal and the corresponding accessed satellite communication link; determining the uplink rate and the downlink rate of the ground terminal and the accessed corresponding unmanned aerial vehicle communication link under different heights in the height adjustable range of the unmanned aerial vehicle; when the same-frequency interference of any communication link is calculated, the time division duplex mode of other communication links is fixed; calculating the same-frequency interference value of the communication link in a time division duplex mode; obtaining the same-frequency interference value of all communication links in a time division duplex mode; and determining the optimal height of each unmanned aerial vehicle and the optimal time division duplex mode of each link, and eliminating the same-frequency interference to the greatest extent.
Description
Technical Field
The invention relates to a multilink interference elimination method applied to comprehensive networking of satellites and unmanned aerial vehicles, and belongs to the technical field of satellite communication and unmanned aerial vehicle communication.
Background
Definition and composition of satellite communications. The satellite communication means a wireless communication mode for performing information interaction between a user terminal and a core network through satellites, and satellites used for the communication mode include a GEO (Geosynchronous Earth Orbit) communication satellite deployed at an orbit position of about 36000 km, a MEO (Medium Earth Orbit) communication satellite deployed at an orbit position of 2000-36000 km, and a LEO (Low Earth Orbit) communication satellite deployed at an orbit position of 50-2000 km. A simple satellite communication system typically consists of a user terminal, a satellite, and a gateway station, from which the information stream passes through the satellite to the user terminal, often referred to as the forward link, and from which the information stream passes through the satellite to the gateway station as the return link. The user terminal is a mobile communication terminal or a fixed ground receiving station, the gateway station is a fixed ground receiving station and is used for connecting a core network and carrying out information interaction with the user terminal, the user terminal can establish a one-way or two-way communication link with a communication satellite, and the gateway station and the communication satellite establish a two-way communication link; the processing of information by communication satellites can be divided into two modes, transparent forwarding and on-board processing.
Composition and classification of unmanned aerial vehicle communications. In recent years, unmanned aerial vehicles represented by quadrotor unmanned aerial vehicles are widely used in various aspects of social development and entertainment life. Meanwhile, wireless communication technologies represented by the fifth generation (5th Generation,5G) mobile communication system are rapidly developed, application scenes are continuously expanded, and communication performance is continuously improved.
Performance and application scenarios of satellite communications. The uplink and downlink transmission rate provided by the conventional wide-beam GEO satellite is generally not more than 500kpbs, and the narrow-beam high-flux GEO satellite developed in recent years can provide a system capacity of 50-300Gbps, and the end-to-end delay (terminal-satellite-gateway) of the GEO satellite is about 500ms. LEO satellites can provide uplink and downlink transmission rates of 0.5-5.2Gbps, and end-to-end delays can be as low as tens of ms. Satellite communications are commonly applied in three categories of scenarios: 1) Providing mobile communication service for remote areas without coverage or insufficient coverage of a ground communication network; 2) When the mobile terminals such as airplanes, trains, automobiles, ships and the like are accessed to the traditional ground communication network, the difficult problems of no network coverage, high complexity mobility management and the like are faced, and satellite communication can provide wireless communication service for the mobile terminals; 3) Services such as multicasting, etc., such as satellite television broadcasting, emergency communication, etc., are provided for the edges or uncovered areas of conventional terrestrial communication networks.
Spatial spectrum resources are scarce. The spectrum resources used for wireless communication are important strategic resources which are not renewable, and with the rapid development of satellite communication and terrestrial cellular mobile communication for decades, the shortage of spectrum resources has become one of the important factors restricting the development of future wireless communication. The method fully utilizes limited frequency spectrum resources to perform effective interference management, and is a key point and a difficult point in the comprehensive networking of satellites and unmanned aerial vehicles.
Disclosure of Invention
The technical problems solved by the invention are as follows: the invention provides a multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking, which considers that the same frequency band is used for wireless communication links of the satellite and the unmanned aerial vehicle, and aims at solving the problem that the same-frequency interference among the multilinks causes the decrease of the throughput of a system when the satellite and the unmanned aerial vehicle are comprehensively networked. The core principle of the invention capable of reducing interference and improving throughput is that the direction and the size of the same-frequency interference can be changed by changing the height of the unmanned aerial vehicle and the transmission direction of a link, so that the interference suffered by a receiver during the integrated networking of the satellite and the unmanned aerial vehicle is minimized.
The technical scheme of the invention is as follows: a multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking comprises the following steps:
step one, acquiring the transmitting power P of all satellites, unmanned aerial vehicles and ground terminals in a comprehensive networking application scene s 、P u And P g Antenna beam main lobe width θ for satellites and unmanned aerial vehicles s And theta u Unmanned aerial vehicle height-adjustable range H umax And H umin The number and location coordinates of all satellites, drones and ground terminals.
Step two, according to the transmission power P of all satellites, unmanned aerial vehicles and ground terminals in the comprehensive networking application scene obtained in the step one s 、P u And P g Antenna beam main lobe width θ for satellites and unmanned aerial vehicles s And theta u Unmanned aerial vehicle height adjustable range H umax And H umin Number of all satellites, unmanned aerial vehicles and ground terminalsDetermining the access mode of each ground terminal according to the quantity and the position coordinates, so that at least one ground terminal is accessed to a satellite, and one ground terminal is accessed to the unmanned aerial vehicle, and networking is completed; to access satellites or drones.
Step three, after networking is completed, determining the uplink rate and the downlink rate of each ground terminal and the corresponding accessed satellite communication link according to the path loss of the link between the satellite and the ground terminal and the large-scale shadow fading of signal transmission in the link;
Determining the uplink rate and the downlink rate of the ground terminal and the accessed corresponding unmanned aerial vehicle communication link at different heights in the height adjustable range of the unmanned aerial vehicle according to the path loss of the link of the ground terminal and the accessed corresponding unmanned aerial vehicle communication and the large-scale shadow fading of signal transmission in the link;
step four, calculating the bidirectional rate sum of each ground terminal and the corresponding accessed satellite communication link and the bidirectional rate sum of each ground terminal and the corresponding accessed unmanned aerial vehicle communication link at different heights in the height adjustable range of the unmanned aerial vehicle;
step five, when the same-frequency interference of any communication link is calculated, the time division duplex mode of other communication links is fixed; according to the fourth step, calculating the bidirectional speed sum of each ground terminal and the corresponding accessed satellite communication link and the bidirectional speed sum of each ground terminal and the corresponding accessed unmanned aerial vehicle communication link in different heights within the height adjustable range of the unmanned aerial vehicle, calculating the same-frequency interference value of the communication link in a time division duplex mode, and the like, traversing the time division duplex mode combination of all other communication links to obtain the same-frequency interference value of all communication links in the time division duplex mode;
Step six, according to the calculated bidirectional rate sum of each ground terminal and the corresponding accessed satellite communication link in the step four, the bidirectional rate sum of each ground terminal and the corresponding accessed unmanned aerial vehicle communication link in different heights in the unmanned aerial vehicle height adjustable range, and the same-frequency interference value in the time division duplex mode of all the communication links obtained in the step five, determining the communication network throughput in the comprehensive networking application scene in the time division duplex mode in different heights in the unmanned aerial vehicle height adjustable range;
step seven, comparing the communication network throughput in the comprehensive networking application scene in the time division duplex mode at different heights in the height adjustable range of the unmanned aerial vehicle, and obtaining the corresponding height of each unmanned aerial vehicle and the time division duplex mode of each communication link when the network throughput is maximum; the optimal unmanned plane height and the optimal time division duplex mode of each link are obtained;
and step eight, according to the optimal heights of the unmanned aerial vehicles and the optimal time division duplex modes of the links, adjusting the current height adjustment values of the unmanned aerial vehicles in the comprehensive networking application scene to the optimal time division duplex modes of the links, namely, eliminating the same-frequency interference to the greatest extent.
Preferably, the unmanned aerial vehicle height refers to the height of the unmanned aerial vehicle from sea level.
Preferably, the ground terminal access modes comprise two types, namely an access satellite and an access unmanned aerial vehicle, wherein the access criterion is the nearest criterion, namely the ground terminal selects the satellite closest to the ground terminal or the unmanned aerial vehicle to access until the service is finished.
Preferably, the time division duplex mode includes: the upper couple is even and the lower couple is even; the odd up-and-down are uplink communication at odd time and downlink communication at even time, and are alternated in turn; the odd-even up is the odd-even up, the odd-even down is the odd time to carry out uplink communication and the even time to carry out downlink communication, alternating in sequence.
Preferably, the comprehensive networking application scene comprises: unmanned aerial vehicle, a plurality of satellites, ground terminals;
the unmanned aerial vehicle can be deployed between 100m and 1000m from the sea level, and one or more unmanned aerial vehicles can be deployed; one or more satellites, which may be LEO, MEO or GEO when there is only one satellite; when there are a plurality of satellites, there may be only LEO and MEO, or there may be only LEO and GEO; only MEO or GEO may be used; LEO, MEO and GEO are also possible.
The number of the ground terminals is more than two;
the unmanned aerial vehicle and the satellite are both provided with directional antennas to the ground; an omnidirectional antenna is arranged on the ground terminal;
The satellite and unmanned aerial vehicle comprehensive networking mode and the communication mode. The multi-link interference elimination method provided by the invention is suitable for comprehensive networking of any unmanned aerial vehicle and satellites, wherein the unmanned aerial vehicle can be deployed between 100-1000m, the satellites can be LEO, MEO and GEO, the unmanned aerial vehicle and the satellites can simultaneously provide communication services for ground users in the same frequency, the unmanned aerial vehicle and the satellites are connected with a ground core network through connecting ground gateway stations, and the ground terminal can be accessed to the unmanned aerial vehicle or the satellites. Space-to-ground links used by the drone and satellites each use a load-balanced time division duplex (Time Division Duplex, TDD) mode of operation.
Preferably, the unmanned aerial vehicle may be a fixed wing or a multi-rotor unmanned aerial vehicle, and it is required that the unmanned aerial vehicle can carry at least a wireless communication load and a sufficient energy source for communication.
Preferably, the ground core network has a function of receiving the backhaul links of the satellite and the unmanned aerial vehicle, and may also have a function of forwarding core network information to the satellite and the unmanned aerial vehicle.
Preferably, the ground terminal has a wireless communication terminal, and the terminal has a function of selecting access to the unmanned aerial vehicle or satellite. The receiving sensitivity of the wireless communication terminal needs to be matched with that of a satellite and a unmanned aerial vehicle.
Preferably, the space-to-ground link of the unmanned aerial vehicle means: a link for communication between the drone and the ground terminal;
the space-to-ground link used by the satellite means: a link for communication between the satellite and the ground terminal.
Preferably, space-to-ground links used by the unmanned aerial vehicle and the satellite both use a load-balanced time division duplex (Time Division Duplex, TDD) operating mode, specifically: and in two consecutive time slots, the first time slot carries out uplink communication, the second time slot carries out downlink communication, and all frequency bands allocated to links are used for uplink and downlink communication.
Preferably, the height-adjustable range H of the unmanned aerial vehicle umax And H umin The requirements are: minimum height H umin Taking geographical environment into consideration for collision avoidance, the highest height H umax Needs and usesThe unmanned aerial vehicle used supports maximum height direction matching.
Preferably, the bidirectional rate sum is the sum of the uplink rate and the downlink rate of the link.
Preferably, the path loss of the link refers to the amplitude fading experienced by the wireless communication signal during free space propagation.
Compared with the prior art, the invention has the advantages that:
(1) When the satellite and the unmanned aerial vehicle are comprehensively networked, the satellite link and the unmanned aerial vehicle link are simultaneously and simultaneously communicated at the same frequency, so that the spectrum utilization rate is effectively improved, and the method can be used as a satellite/unmanned aerial vehicle comprehensive networking mode under the condition that the current wireless communication spectrum resources are increasingly stressed.
(2) Aiming at the interference problem when multiple links communicate simultaneously in the same frequency, the invention provides the method for reducing the same frequency interference as much as possible by adjusting the transmission direction of the links and the height of the unmanned aerial vehicle, wherein, the source and the experienced channel of the interference can be changed by adjusting the transmission direction of the links, and the reasonable balance between the path loss and the satellite link interference can be made by adjusting the height of the unmanned aerial vehicle.
(3) The invention firstly fully acquires the parameter information of each node in the comprehensive networking, secondly calculates the optimal unmanned aerial vehicle height and link time division duplex mode based on the parameter information and faces to the maximized network throughput.
Drawings
FIG. 1 is a schematic diagram of a satellite and unmanned aerial vehicle integrated networking scenario;
FIG. 2 is a schematic diagram of a satellite and unmanned aerial vehicle integrated networking scenario;
FIG. 3 is a schematic diagram of a satellite and unmanned aerial vehicle integrated networking scenario;
FIG. 4 is a schematic diagram of a comprehensive networking scenario for satellites and unmanned aerial vehicles;
fig. 5 is a flow chart of the present invention for multilink interference cancellation.
Detailed Description
The invention is described in further detail below with reference to the drawings and the specific embodiments.
The invention relates to a multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking, which is used for determining the access mode of each ground terminal, so that at least one ground terminal is accessed to the satellite, and one ground terminal is accessed to the unmanned aerial vehicle, thereby completing networking; to access satellites or drones. After networking is completed, determining the uplink rate and the downlink rate of each ground terminal and the corresponding accessed satellite communication link; determining the uplink rate and the downlink rate of the ground terminal and the accessed corresponding unmanned aerial vehicle communication link under different heights in the height adjustable range of the unmanned aerial vehicle; when the same-frequency interference of any communication link is calculated, the time division duplex mode of other communication links is fixed; and calculating the same-frequency interference value of the communication link in the time division duplex mode. And the same-frequency interference value under the time division duplex mode of all the communication links is obtained by traversing the time division duplex mode combination of all the other communication links; and determining the optimal heights of the unmanned aerial vehicles and the optimal time division duplex modes of the links, adjusting the heights of the unmanned aerial vehicles to the optimal heights of the links, and adjusting the heights of the unmanned aerial vehicles to the optimal time division duplex modes of the links, namely, eliminating the same-frequency interference to the greatest extent.
On the one hand, the unmanned aerial vehicle carrying terminal load can be used as an aerial user to access a ground base station of a ground mobile communication system, so that high-speed return of image/video data is realized. On the other hand, the unmanned aerial vehicle can also be carried with a base station/relay load to be deployed as an air base station/air relay to provide services such as emergency communication, hot spot area enhanced coverage and the like due to the characteristics of rapid deployment and flexibility.
Satellite communication and unmanned aerial vehicle communication are comprehensively networked. The satellite and the unmanned aerial vehicle have the characteristics of wide communication coverage, flexible and changeable coverage area and the like, and the industry represented by 3GPP is used for researching a non-ground communication network formed by a 5G mobile communication system by using a satellite, an unmanned aerial vehicle and other platforms. Among these, the role of non-terrestrial networks in 5G can be broadly divided into three aspects: 1) An economical and efficient Internet network access service is provided in areas where the ground communication network cannot cover or does not cover enough; 2) The enhanced 5G communication system provides mobile communication service for mobile platforms such as airplanes, ships, high-speed rails, automobiles and the like; 3) Providing efficient multicast and broadcast services to edge users of a terrestrial network. The satellite and the unmanned aerial vehicle are comprehensively networked, so that the characteristics of heterogeneous platforms such as the satellite, the unmanned aerial vehicle and the like can be further explored, and flexible and reliable wireless communication services can be provided for users in different scenes.
The invention has the application scene of comprehensive networking scene of simultaneously existence of satellite, unmanned aerial vehicle and ground terminal, and the ground terminal uses time division duplex mode to carry out two-way communication with satellite or unmanned aerial vehicle. Under this scene, ground terminal can select and satellite or unmanned aerial vehicle to connect and carry out two-way communication, and the two-way communication link that ground terminal and satellite or unmanned aerial vehicle set up can select to work in different time division duplex modes, and unmanned aerial vehicle can select to arrange in different altitudes, so this comprehensive networking scene communication mode is nimble changeable, the combination is complicated, and the same frequency interference is different under the different circumstances and time division duplex mode and unmanned aerial vehicle deployment altitude selection have can cause serious inter-link same frequency interference.
The multi-link interference elimination method provided by the invention can effectively select the optimal link time division duplex mode and the deployment height of the unmanned aerial vehicle in flexible and changeable communication modes with complex combination, can eliminate the same-frequency interference to the greatest extent, and improves the communication performance of each link in the comprehensive networking scene.
As shown in fig. 1, the comprehensive networking scene of the satellite and the unmanned aerial vehicle is one, which is divided into a left side 1) and a right side 2), wherein 1) the unmanned aerial vehicle is in the coverage range of the satellite; 2) The two links use the same transmission direction;
FIG. 2 is a view of a second comprehensive networking scenario for satellites and unmanned aerial vehicles, divided into left 1) and right 2), wherein 1) the unmanned aerial vehicle is within the coverage of the satellite; 2) The two links use different transmission directions;
FIG. 3 is a view of a third scenario for integrated networking of satellites and drones, divided into left 1) and right 2), wherein 1) the drone is out of satellite coverage; 2) The two links use different transmission directions;
fig. 4 shows a fourth comprehensive networking scenario for satellites and unmanned aerial vehicles, which is divided into left 1) and right 2), wherein 1) the unmanned aerial vehicle is within the coverage of the satellites; 2) The two links use the same transmission direction;
as shown in fig. 5, the method for eliminating the multi-link interference applied to the comprehensive networking of satellites and unmanned aerial vehicles comprises the following steps:
step one, acquiring the transmitting power P of all satellites, unmanned aerial vehicles and ground terminals in a comprehensive networking application scene s 、P u And P g Antenna beam main lobe width θ for satellites and unmanned aerial vehicles s And theta u Unmanned aerial vehicle height-adjustable range H umax And H umin The number and location coordinates of all satellites, drones and ground terminals. The preferable scheme is as follows:
the invention can carry out comprehensive networking management and control, namely, the system can be a satellite or an unmanned aerial vehicle, namely, a management and control program is installed on the satellite or the unmanned aerial vehicle.
As shown in fig. 1, all satellites, unmanned aerial vehicles and ground terminals in the comprehensive networking scene transmit power P of all satellites, unmanned aerial vehicles and ground terminals s 、P u And P g Antenna beam main lobe width θ for satellite and unmanned aerial vehicle s And theta u Unmanned aerial vehicle height-adjustable range H umax And H umin And sending the data of the number and the position coordinates of all the satellites, the unmanned aerial vehicle and the ground terminal to the satellite or the unmanned aerial vehicle where the management and control program is located.
The data transmission implementation mode specifically comprises the following steps: all satellites, unmanned aerial vehicles and ground terminals periodically broadcast own parameter information by using preset frequency bands and power, and the satellites or unmanned aerial vehicles where the control program is located periodically receive the own parameter information of all satellites, unmanned aerial vehicles and ground terminals on the preset frequency bands.
The method realizes the acquisition of various parameter information in the comprehensive networking application scene.
Step two, according to the transmission power P of all satellites, unmanned aerial vehicles and ground terminals in the comprehensive networking application scene obtained in the step one s 、P u And P g Antenna beam main lobe width θ for satellites and unmanned aerial vehicles s And theta u Unmanned aerial vehicle height-adjustable range H umax And H umin Determining the access mode of each ground terminal by the number and the position coordinates of all satellites, unmanned aerial vehicles and ground terminals, so that at least one ground terminal is accessed to the satellites, and one ground terminal is accessed to the unmanned aerial vehicle, thereby completing networking; to access satellites or drones. The preferable scheme is as follows:
The invention is directed to a comprehensive networking scene of satellites and unmanned aerial vehicles, so that the number of unmanned aerial vehicles and satellites is at least 1 respectively, and the number of ground terminals is at least greater than or equal to the number of unmanned aerial vehicles and satellites, and the access modes of the ground terminals can be determined to be divided into the following two cases:
in the first case, the number of ground terminals is equal to the number of unmanned aerial vehicles and satellites. At the moment, all the ground terminals can be matched with the satellite or the unmanned aerial vehicle for access, and according to the coordinate positions of the satellite, the unmanned aerial vehicle and the ground terminals, the ground terminals are respectively accessed to the satellite or the unmanned aerial vehicle with the nearest distance according to the common communication distance nearest criterion.
And in the second case, the number of ground terminals is greater than the number of unmanned aerial vehicles and satellites. At this time, the number of the ground terminals connected to the satellites or the unmanned aerial vehicles is smaller than that of the existing ground terminals, the ground terminals which are equal to the number of the satellites and the unmanned aerial vehicles are randomly selected from all the existing ground terminals, and the ground terminals are connected to the satellites or the unmanned aerial vehicles which are closest to each other according to the common communication distance nearest criterion. In addition, the remaining non-accessed ground terminals wait for the round of communication to complete and then try to access again.
The specific mode of the access is as follows: the satellite or the unmanned aerial vehicle where the control program is located in the first step can broadcast the matching result determined in the first case and the second case to each access node, and the matching of the communication addresses on the communication protocol is completed, namely the access is completed.
Step three, after networking is completed, determining the uplink rate and the downlink rate of each ground terminal and the corresponding accessed satellite communication link according to the path loss of the link between the satellite and the ground terminal and the large-scale shadow fading of signal transmission in the link;
determining the uplink rate and the downlink rate of the ground terminal and the accessed corresponding unmanned aerial vehicle communication link at different heights in the height adjustable range of the unmanned aerial vehicle according to the path loss of the link of the ground terminal and the accessed corresponding unmanned aerial vehicle communication and the large-scale shadow fading of signal transmission in the link; the preferable scheme is as follows:
path loss L of satellite air-ground link s Can be expressed as:
wherein f c For the communication carrier frequency, C is the speed of light, d s N is the distance between the satellite and the ground terminal s Is the path loss attenuation factor of the satellite space-earth link.
The path loss of the unmanned aerial vehicle air-to-ground link may be expressed as
Wherein d u (H u ) For Euler distance between unmanned aerial vehicle and ground terminal and for unmanned aerial vehicle height H u Is a function of (unmanned aerial vehicle height H as previously described) u In the range of H umax And H umin Before), n u Is a path loss attenuation factor of the unmanned aerial vehicle air-ground link.
Shadow fading of the satellite air-to-ground link and the unmanned air-to-ground link may be represented as Φ, respectively s And phi is u Link noise is denoted as sigma.
The satellite space link uplink rate can be calculated by the following formula:
the satellite space-earth link downlink rate can be calculated by the following formula:
the uplink speed of the unmanned aerial vehicle air-ground link can be calculated by the following formula:
the downlink speed of the unmanned aerial vehicle air-ground link can be calculated by the following formula:
because the height of the unmanned aerial vehicle can be flexibly adjusted, the uplink and downlink speeds of the unmanned aerial vehicle air-ground link are the height H of the unmanned aerial vehicle u The uplink rate and the downlink rate of the unmanned aerial vehicle air-ground link are the uplink rate and the downlink rate of different unmanned aerial vehicle heights.
Step four, calculating the bidirectional rate sum of each ground terminal and the corresponding accessed satellite communication link and the bidirectional rate sum of each ground terminal and the corresponding accessed unmanned aerial vehicle communication link at different heights in the height adjustable range of the unmanned aerial vehicle; the preferable scheme is as follows:
satellite air-ground link bidirectional rateCan be calculated by the following formula:
unmanned aerial vehicle air-ground link bidirectional speed and speed under different heights in unmanned aerial vehicle height adjustable rangeCan be calculated by the following formula:
step five, when the same-frequency interference of any communication link is calculated, the time division duplex mode of other communication links is fixed; according to the fourth step, calculating the bidirectional speed sum of each ground terminal and the corresponding accessed satellite communication link and the bidirectional speed sum of each ground terminal and the corresponding accessed unmanned aerial vehicle communication link in different heights within the height adjustable range of the unmanned aerial vehicle, calculating the same-frequency interference value of the communication link in a time division duplex mode, and the like, traversing the time division duplex mode combination of all other communication links to obtain the same-frequency interference value of all communication links in the time division duplex mode; the preferable scheme is as follows:
Traversing the time division duplex mode combinations of all other communication links to obtain the same-frequency interference value under the time division duplex mode of all the communication links:
time division duplex mode: time division duplex is a communication scheme in which uplink and downlink are performed using the same frequency band but in different time slots. Time division duplexing can be divided into two modes, namely an odd upper couple and a low couple and an odd lower couple; the odd up-and-down are uplink communication at odd time and downlink communication at even time, and are alternated in turn; the odd-even up is the odd-even up, the odd-even down is the odd time to carry out uplink communication and the even time to carry out downlink communication, alternating in sequence.
Traversing the division duplex mode: assuming two communication links (the first is an unmanned aerial vehicle air-ground link between an unmanned aerial vehicle and a ground terminal node, and the second is a satellite air-ground link between a satellite and a ground terminal node), each communication link has (as described in the above paragraph) two time division duplex operation modes of an odd upper couple and a lower couple, so that the following four different time division duplex operation mode combination conditions exist: 1) The first link is even and odd, and the second link is even and odd; 2) The first is odd and even, the second is odd and even; 3) The first link is even and even, and the second link is even and even; 4) The first link is on the odd-even pair, and the second link is on the odd-even pair. The above description is presented with reference to figures 1, 2, 3 and 4.
And (3) co-channel interference calculation: it is assumed that both links (described in the previous examples) operate in the following modes of operation: the first link is odd and even, the second link is odd and even, the first link transmits uplink signals to the unmanned aerial vehicle for the ground terminal node at odd time, and the second link transmits uplink signals to the satellite for the ground terminal node; and the first link at even time sends downlink signals to the ground terminal node for the unmanned aerial vehicle, and the second link sends downlink signals to the ground terminal node for the satellite. At this time, because the two links operate in the same frequency band, the unmanned aerial vehicle and the satellite at odd times are respectively interfered by uplink signals from the ground terminal in the other link, and the ground terminal node at even times is respectively interfered by downlink signals from the satellite and the unmanned aerial vehicle in the other link. Based on the positions of the unmanned plane/satellite/two ground terminal nodes and the transmitting power of the three nodes, the same-frequency interference can be calculated.
The flag of the time division duplex mode of the link is denoted by r, that is, r=0 indicates that the link is even and odd, and r=1 indicates that the link is even and odd.
The satellite-air link uplink is subject to co-channel interference in the above example (and is time division duplex mode r and drone height H u A function of) can be calculated by the following formula:
co-channel interference imposed by satellite space-earth link downlinkCan be calculated by the following formula:
co-channel interference suffered by unmanned aerial vehicle air-ground link uplink(and is time division duplex mode r and drone height H u A function of) can be calculated by the following formula:
co-channel interference imposed by satellite space-earth link downlinkCan be calculated by the following formula:
the co-channel interference values of the rest links can be obtained similarly. The same-frequency interference value is equal to the height H of the unmanned plane u And also to the time division duplex mode r.
Step six, according to the calculated bidirectional rate sum of each ground terminal and the corresponding accessed satellite communication link in the step four, the bidirectional rate sum of each ground terminal and the corresponding accessed unmanned aerial vehicle communication link in different heights in the unmanned aerial vehicle height adjustable range, and the same-frequency interference value in the time division duplex mode of all the communication links obtained in the step five, determining the communication network throughput in the comprehensive networking application scene in the time division duplex mode in different heights in the unmanned aerial vehicle height adjustable range; the preferable scheme is as follows:
the preferable scheme is as follows: there are two communication links in the networking scenario: one is an unmanned aerial vehicle space-to-ground link between an unmanned aerial vehicle and a ground terminal node, and the other is a satellite space-to-ground link between a satellite and a ground terminal node. According to the traversing result of the time division duplex modes of the two links in the fifth example, four time division duplex mode combination conditions exist at the moment; in each time division duplex mode combination, the drone may be deployed at different altitudes: for example, there are two heights of 100m and 200m, so that the time division duplex mode and the unmanned plane height are combined in 8 total. The bidirectional rate sum of the two links and the co-channel interference value received can be calculated in each case, and the communication network throughput in each case of 8 cases can be further calculated. )
Based on satellite space-to-ground link bidirectional rate sumUnmanned aerial vehicle air-ground link bidirectional speed sum +.>Wei Xingkong uplink all co-channel interference +.>Co-channel interference to satellite space-earth link downlink>The uplink of the unmanned aerial vehicle air-ground link is subject to the same-frequency interference->And the co-channel interference suffered by the downlink of the unmanned aerial vehicle air-ground link +.>The communication network throughput under different unmanned aerial vehicle heights and different time division duplex modes can be calculated:
step seven, comparing the communication network throughput in the comprehensive networking application scene in the time division duplex mode at different heights in the height adjustable range of the unmanned aerial vehicle, and obtaining the corresponding height of each unmanned aerial vehicle and the time division duplex mode of each communication link when the network throughput is maximum; the optimal unmanned plane height and the optimal time division duplex mode of each link are obtained; the preferable scheme is as follows:
traversing each H according to the above formula u And r, calculating C under different combination conditions net (r,H u ) Of which the largest C is selected net (r,H u ) Value and corresponding H u And r is the optimal unmanned plane height and the optimal link time division duplex mode when the network throughput is maximum.
And step eight, according to the optimal heights of the unmanned aerial vehicles and the optimal time division duplex modes of the links, adjusting the current height adjustment values of the unmanned aerial vehicles in the comprehensive networking application scene to the optimal time division duplex modes of the links, namely, eliminating the same-frequency interference to the greatest extent. The preferable scheme is as follows:
And in the first step, the satellite or the unmanned aerial vehicle where the control program is located sends the calculated optimal unmanned aerial vehicle height and the optimal time division duplex mode to other satellites, unmanned aerial vehicles and ground terminals.
And all the satellites and the ground terminals configure the time division duplex mode in the communication protocol according to the received optimal time division duplex mode.
All unmanned aerial vehicles adjust the height of the unmanned aerial vehicle to the optimal unmanned aerial vehicle height, and all unmanned aerial vehicles configure the time division duplex mode in the communication protocol according to the received optimal time division duplex mode.
At this time, the co-channel interference can be eliminated to the greatest extent by adjusting the height of the optimal unmanned aerial vehicle and configuring the optimal time division duplex mode, and the purpose of the invention is achieved.
In order to improve the spectrum use efficiency, the invention considers that the same frequency band is used for wireless communication links of the satellite and the unmanned aerial vehicle, and aims at the problem that the same-frequency interference among multiple links causes the reduction of the throughput of the system when the satellite and the unmanned aerial vehicle are comprehensively networked. The core principle of the invention capable of reducing interference and improving throughput is that the direction and the size of the same-frequency interference can be changed by changing the height of the unmanned aerial vehicle and the transmission direction of a link, so that the interference suffered by a receiver during the integrated networking of the satellite and the unmanned aerial vehicle is minimized.
The satellite and unmanned aerial vehicle comprehensive networking mode and the communication mode. The multilink interference elimination method provided by the invention is suitable for comprehensive networking of any unmanned aerial vehicle and satellites, wherein the unmanned aerial vehicle can be deployed between 100 and 1000m, the satellites can be LEO, MEO and GEO, the unmanned aerial vehicle and the satellites both use directional antennas to the ground, and the ground terminal antenna uses omni-directional antennas. The unmanned aerial vehicle and the satellite can simultaneously provide communication service for the ground user at the same frequency, the unmanned aerial vehicle and the satellite are connected with the core network through the ground gateway station, and the ground user can access the unmanned aerial vehicle and the satellite. The space-to-ground links used by the unmanned aerial vehicle and the satellite both use a load-balanced time division duplex (Time Division Duplex, TDD) working mode, namely, in two continuous time slots, the first time slot carries out uplink communication, the second time slot carries out downlink communication, and all frequency bands allocated to the links are used for uplink and downlink communication.
The satellite and the unmanned aerial vehicle integrate the multilink interference in the networking. In order to fully utilize precious spectrum resources, the invention considers the application scene as follows: the satellite and the unmanned aerial vehicle can simultaneously provide services for ground users at the same frequency. Therefore, the ground link of the unmanned aerial vehicle and the ground link of the satellite inevitably generate mutual co-channel interference. Specifically, when the receiving end of one link is in the main lobe range of the antenna of the transmitting end of the other link, the receiving end will be interfered by the same frequency of the transmitting end of the other link, and the same frequency interference will reduce the receiving signal-to-noise ratio, so as to seriously correspond to the communication performance.
A method of multilink interference cancellation. The core of the method for eliminating the multi-link interference during the integrated networking of the satellite and the unmanned aerial vehicle provided by the invention is that 1) the transmission direction of a link is adjusted. The transmission directions of the links are adjusted to change the sources of interference, so that the sources of interference are more subjected to the ground channel instead of the air-ground channel to propagate, and the ground channel is subjected to more serious shadow fading than the air-ground channel, so that the strength of interference signals reaching a receiver can be reduced, and the signal-to-interference ratio of a receiving end is improved. 2) And adjusting the height of the unmanned aerial vehicle. The unmanned aerial vehicle can leave the coverage range of a beam main lobe of the satellite by raising the height of the unmanned aerial vehicle, so that the interference from the satellite is avoided; however, increasing the height of the unmanned aerial vehicle increases the link transmission distance and reduces the strength of the signal received by the receiving end. Therefore, there is a trade-off between the adjustment of the unmanned aerial vehicle height, and the adjustment of the height can be determined by comparing and optimizing the unmanned aerial vehicle height according to different transmission scenes and system parameters.
The invention designs a multilink interference elimination method applied to the comprehensive networking of satellites and unmanned aerial vehicles, which is suitable for the comprehensive networking scene of any unmanned aerial vehicle and any satellite. In the specific embodiment, we take a comprehensive networking scenario of a satellite and a unmanned aerial vehicle as an example to illustrate the core design of the present invention.
The invention relates to a multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking, which is suitable for setting different beam main lobe widths for any unmanned aerial vehicle and any satellite. In the specific embodiments herein, the core design of the present invention is illustrated by taking one satellite and one drone as an example to set a specific beam main lobe width (and assuming that the transmit beam main lobe width and the receive beam main lobe width are identical). The invention relates to a multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking, which is suitable for setting different unmanned aerial vehicle heights and satellite orbit heights for any unmanned aerial vehicle and any satellite. In the specific embodiment, the core design of the present invention is illustrated by taking a preferred configuration of a satellite and a drone with a specific height adjustable range and satellite orbit height as an example.
The invention relates to a multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking, the application scene is shown in figure 1, the satellite and unmanned aerial vehicle comprehensive networking scene comprises a satellite (a specific orbit height and a beam main lobe width, if specific numbers are required to be specified, the specific numbers can be set to 100km and 60 degrees), an unmanned aerial vehicle (a specific unmanned aerial vehicle height adjustable range and a beam main lobe width, if specific numbers are required to be specified, the specific numbers can be set to 0.1km-3km and 60 degrees) and ground nodes, and the ground nodes can be randomly accessed to the satellite or the unmanned aerial vehicle and are in wireless communication with the satellite or the unmanned aerial vehicle. Fig. 1-4 depict four transmission scenarios of a service ground node when a drone and a satellite are comprehensively networked, respectively.
In fig. 1, the drone is within the satellite coverage, and both links use the same transmission direction. Both satellite links and drone links consider the time division duplex communication mode of load balancing (described above), so the whole transmission period can be divided into two phases, slot one and slot two: in the first time slot, the unmanned aerial vehicle link and the satellite link are downlink links, ground users in the unmanned aerial vehicle link are subjected to same-frequency interference because the ground users are in the coverage area of the satellite beam, and the ground users in the satellite link are out of the coverage area of the unmanned aerial vehicle and are not subjected to same-frequency interference; in the second time slot, the unmanned aerial vehicle link and the satellite link are both uplink links, the satellite in the satellite link is subjected to the same-frequency interference of the ground user provided with the omnidirectional antenna, and the main lobe of the unmanned aerial vehicle receiving antenna in the unmanned aerial vehicle link does not contain the ground user in the satellite link, so that the unmanned aerial vehicle is not subjected to the same-frequency interference.
In fig. 2 the drone is within the satellite coverage, and the two links use different transmission directions. The whole transmission period can be divided into two phases of time slot one and time slot two: in the first time slot, the unmanned aerial vehicle link is a downlink link, the satellite link is an uplink link, the satellite link is not subjected to the same-frequency interference because the satellite is out of the coverage range of the transmitting beam of the unmanned aerial vehicle, and the ground user in the unmanned aerial vehicle link is in the coverage range of the omnidirectional antenna of the ground user in the satellite link and is subjected to the same-frequency interference; in the second time slot, the unmanned aerial vehicle link is an uplink link and the satellite link is a downlink link, the ground user in the satellite link is subjected to the same-frequency interference of the ground user in the unmanned aerial vehicle link, and the main lobe of the unmanned aerial vehicle receiving antenna in the unmanned aerial vehicle link does not contain the satellite in the satellite link, so that the unmanned aerial vehicle is not subjected to the same-frequency interference.
In fig. 3 the drone is outside the satellite coverage, the two links use different transmission directions. The whole transmission period can be divided into two phases of time slot one and time slot two: in the first time slot, the unmanned aerial vehicle link is a downlink link, the satellite link is an uplink link, the satellite link is not subjected to the same-frequency interference because the satellite is out of the coverage range of the transmitting beam of the unmanned aerial vehicle, and the ground user in the unmanned aerial vehicle link is in the coverage range of the omnidirectional antenna of the ground user in the satellite link and is subjected to the same-frequency interference; in the second time slot, the unmanned aerial vehicle link is an uplink link and the satellite link is a downlink link, the ground user in the satellite link is subjected to the same-frequency interference of the ground user in the unmanned aerial vehicle link, and the main lobe of the unmanned aerial vehicle receiving antenna in the unmanned aerial vehicle link does not contain the satellite in the satellite link, so that the unmanned aerial vehicle is not subjected to the same-frequency interference.
In fig. 4 the drone is outside the satellite coverage, both links use the same transmission direction. The whole transmission period can be divided into two phases of time slot one and time slot two: the unmanned aerial vehicle link and the satellite link in the time slot I are uplink links, and the ground users in the satellite link are not contained in the range of the main lobe of the unmanned aerial vehicle reception in the unmanned aerial vehicle link, so that the same-frequency interference is avoided, and the ground users in the unmanned aerial vehicle link are contained in the range of the main lobe of the satellite reception in the satellite link, so that the same-frequency interference is received; in the second time slot, the unmanned aerial vehicle link and the satellite link are downlink links, and the ground user in the satellite link is positioned outside the main lobe of the unmanned aerial vehicle transmitting beam in the unmanned aerial vehicle link, so that the same-frequency interference does not exist, and the ground user in the unmanned aerial vehicle link is positioned inside the main lobe of the transmitting antenna of the satellite link satellite and is subjected to the same-frequency interference.
Based on the above discussion of four transmission scenarios, the multilink interference cancellation method in the present invention can be preferably described as follows:
step one, acquiring transmitting powers P_s, P_u and P_g of satellites, unmanned aerial vehicles and ground users in an integrated networking application scene, antenna beam main lobe widths theta_s and theta_u of the satellites and the unmanned aerial vehicles, orbit height H_s of the satellites, unmanned aerial vehicle height H_ uav, adjustable ranges H_umax and H_umin, the number and distribution of the ground users and the like.
Step two, determining a user access mode. The ground user can access the satellite and the unmanned aerial vehicle by adopting a random access mode.
Step three, the user of each pair of services traverses the four transmission scenarios of fig. 1-4. In each transmission scenario, the sum of the bi-directional rate of each link, i.e., the uplink rate plus the downlink rate, is calculated. The invention considers the path loss and the large-scale shadow fading when calculating the uplink and downlink velocity, wherein the path loss can be calculated according to the widely applied free space fading model and the parameters of the step one, and the large-scale shadow fading is an experience parameter in the propagation environment and can be obtained from the historical measurement data.
And step four, comparing the bidirectional velocity sums under four transmission conditions to obtain the optimal unmanned plane height and link transmission direction when the bidirectional velocity sums are maximum.
And fifthly, repeating the third step and the fourth step to finish the service in the comprehensive networking scene.
The invention realizes the further scheme of improving the anti-interference efficiency: setting the pitch angle of the ground terminal in the air-ground link or the satellite air-ground link of the accessed unmanned plane and other unmanned planes as theta p (furthermore, as described in the first step of the specification, the main lobe width theta of the antenna beam of the unmanned aerial vehicle u ) Then the constraint is satisfied: θ p >θ u The anti-interference efficiency can be further improved; similarly, setting the pitch angle theta of the ground terminal in the satellite and other unmanned aerial vehicle air-ground links or the satellite air-ground links after completing access q (furthermore, as described in step one of the specification, the satellite antenna main lobe width θ s ) Then the constraint is satisfied: θ q >θ s The anti-interference efficiency can be further improved; 2) Scheme for improving anti-interference stability: establishing unmanned aerial vehicle air-ground link path loss phi u The change rate of eta u Let the satellite space-to-ground link path loss phi s The change rate of eta s Then the constraint is satisfied: η (eta) u -η s <And 1, the anti-interference stability can be effectively improved.
Setting the network throughput without using the multilink interference cancellation method of the present invention asThe network throughput after the multilink interference elimination method of the invention is +. >Through actual measurement, if->The advantages of the present invention are embodied.
When the satellite and the unmanned aerial vehicle are comprehensively networked, the satellite link and the unmanned aerial vehicle link are simultaneously communicated at the same frequency, so that the spectrum utilization rate is effectively improved, the satellite/unmanned aerial vehicle comprehensive networking mode can be used as a satellite/unmanned aerial vehicle comprehensive networking mode under the condition that the current wireless communication spectrum resources are increasingly stressed, and the invention aims at the interference problem during the multi-link simultaneous same-frequency communication.
The invention firstly fully acquires the parameter information of each node in the comprehensive networking, secondly calculates the optimal unmanned aerial vehicle height and link time division duplex mode based on the parameter information and faces to the maximized network throughput.
Claims (11)
1. A multilink interference elimination method applied to satellite and unmanned aerial vehicle comprehensive networking is characterized by comprising the following steps:
step one, acquiring the transmitting power P of all satellites, unmanned aerial vehicles and ground terminals in a comprehensive networking application scene s 、P u And P g Antenna beam main lobe width θ for satellites and unmanned aerial vehicles s And theta u Unmanned aerial vehicle height-adjustable range H umax And H umin The number and location coordinates of all satellites, unmanned aerial vehicles and ground terminals; the comprehensive networking application scene comprises the following steps: unmanned aerial vehicle, a plurality of satellites, ground terminals; the unmanned aerial vehicle is deployed between 100m and 1000m away from the sea level, and one or more unmanned aerial vehicles are arranged; one or more satellites and more ground terminals; unmanned aerial vehicle and satelliteDirectional antennas to the ground are arranged; an omnidirectional antenna is arranged on the ground terminal; the satellite is LEO, MEO and/or GEO, the unmanned aerial vehicle and the satellite can simultaneously provide communication service for ground users at the same frequency, the unmanned aerial vehicle and the satellite are both connected with a ground core network through a ground gateway station, a ground terminal can be connected with the unmanned aerial vehicle or the satellite, and space-ground links used by the unmanned aerial vehicle and the satellite both use a load-balanced time division duplex (Time Division Duplex, TDD) working mode;
Step two, according to the transmission power P of all satellites, unmanned aerial vehicles and ground terminals in the comprehensive networking application scene obtained in the step one s 、P u And P g Antenna beam main lobe width θ for satellites and unmanned aerial vehicles s And theta u Unmanned aerial vehicle height adjustable range H umax And H umin Determining the access mode of each ground terminal by the number and the position coordinates of all satellites, unmanned aerial vehicles and ground terminals, so that at least one ground terminal is accessed to the satellites, and one ground terminal is accessed to the unmanned aerial vehicle, thereby completing networking;
step three, after networking is completed, determining the uplink rate and the downlink rate of each ground terminal and the corresponding accessed satellite communication link according to the path loss of the link between the satellite and the ground terminal and the large-scale shadow fading of signal transmission in the link;
determining the uplink rate and the downlink rate of the ground terminal and the accessed corresponding unmanned aerial vehicle communication link at different heights in the height adjustable range of the unmanned aerial vehicle according to the path loss of the link of the ground terminal and the accessed corresponding unmanned aerial vehicle communication and the large-scale shadow fading of signal transmission in the link;
step four, calculating the bidirectional rate sum of each ground terminal and the corresponding accessed satellite communication link and the bidirectional rate sum of each ground terminal and the corresponding accessed unmanned aerial vehicle communication link at different heights in the height adjustable range of the unmanned aerial vehicle;
Step five, when the same-frequency interference of any communication link is calculated, the time division duplex mode of other communication links is fixed; according to the fourth step, calculating the bidirectional speed sum of each ground terminal and the corresponding accessed satellite communication link and the bidirectional speed sum of each ground terminal and the corresponding accessed unmanned aerial vehicle communication link in different heights within the height adjustable range of the unmanned aerial vehicle, calculating the same-frequency interference value of the communication link in a time division duplex mode, and the like, traversing the time division duplex mode combination of all other communication links to obtain the same-frequency interference value of all communication links in the time division duplex mode; wherein r represents a mark of a time division duplex mode of the link, namely r=0 represents that the link is odd-up and even-down, and r=1 represents that the link is odd-down and even-up; the time division duplex mode comprises an odd upper couple and a low couple and an odd lower couple; the odd up-and-down are uplink communication at odd time and downlink communication at even time, and are alternated in turn; the odd-even up is the odd-even up, the odd-even down is the odd time to carry out uplink communication and the even time to carry out downlink communication, sequentially and alternately;
step six, according to the calculated bidirectional rate sum of each ground terminal and the corresponding accessed satellite communication link in the step four, the bidirectional rate sum of each ground terminal and the corresponding accessed unmanned aerial vehicle communication link in different heights in the unmanned aerial vehicle height adjustable range, and the same-frequency interference value in the time division duplex mode of all the communication links obtained in the step five, determining the communication network throughput in the comprehensive networking application scene in the time division duplex mode in different heights in the unmanned aerial vehicle height adjustable range;
Step seven, comparing the communication network throughput in the comprehensive networking application scene in the time division duplex mode at different heights in the height adjustable range of the unmanned aerial vehicle, and obtaining the corresponding height of each unmanned aerial vehicle and the time division duplex mode of each communication link when the network throughput is maximum; the optimal unmanned plane height and the optimal time division duplex mode of each link are obtained;
and step eight, according to the optimal heights of the unmanned aerial vehicles and the optimal time division duplex modes of the links, adjusting the current height adjustment values of the unmanned aerial vehicles in the comprehensive networking application scene to the optimal time division duplex modes of the links, namely, eliminating the same-frequency interference to the greatest extent.
2. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: the unmanned aerial vehicle height refers to the height of the unmanned aerial vehicle from the sea level.
3. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: the ground terminal access modes comprise two types, namely an access satellite and an access unmanned aerial vehicle, wherein the access criterion is the nearest criterion, namely the ground terminal selects the satellite closest to the ground terminal or the unmanned aerial vehicle to access until the service is finished.
4. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: the unmanned aerial vehicle can be a fixed wing or a multi-rotor unmanned aerial vehicle, and the unmanned aerial vehicle is required to be at least capable of carrying wireless communication load and being used for enough energy for communication.
5. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: the ground core network has the function of receiving the satellite and the unmanned aerial vehicle backhaul link, and can also have the function of forwarding core network information to the satellite and the unmanned aerial vehicle.
6. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: the ground terminal is provided with a wireless communication terminal, and the terminal has the function of selecting to access the unmanned aerial vehicle and also can select to access the satellite; the receiving sensitivity of the wireless communication terminal needs to be matched with that of a satellite and a unmanned aerial vehicle.
7. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: the space-to-ground link of the unmanned aerial vehicle refers to: a link for communication between the drone and the ground terminal;
The space-to-ground link used by the satellite means: a link for communication between the satellite and the ground terminal.
8. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: space-to-ground links used by the unmanned aerial vehicle and the satellite both use a load-balanced time division duplex (Time Division Duplex, TDD) working mode, specifically: and in two consecutive time slots, the first time slot carries out uplink communication, the second time slot carries out downlink communication, and all frequency bands allocated to links are used for uplink and downlink communication.
9. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: unmanned aerial vehicle height adjustable range H umax And H umin The requirements are: minimum height H umin Taking geographical environment into consideration for collision avoidance, the highest height H umax Maximum height direction matching needs to be supported with the unmanned aerial vehicle used.
10. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: the bidirectional rate sum is the sum of the uplink rate and the downlink rate of the link.
11. The method for removing multi-link interference applied to integrated networking of satellites and unmanned aerial vehicles according to claim 1, wherein the method comprises the following steps: the path loss of a link refers to the amplitude fading experienced by a wireless communication signal during free space propagation.
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