Joint optimization for location, beam, and radio resources of aerial base station having controllable directional antenna

Abstract

Disclosed is a technology for operating an unmanned aerial vehicle support network. In an embodiment, a method, performed by an electronic device, for determining a flight path, a beam parameter, and resource allocation of an aerial base station in a system comprising a ground base station, the aerial base station, and a plurality of user devices that receive data from the ground base station via a relay of the aerial base station may comprise the steps of: setting requirements including a minimum required data transfer rate condition for each user device; and determining a flight path, a beam parameter, and resource allocation of the aerial base station for maximizing the sum of reception data transfer rates of the plurality of user devices while satisfying the set requirements.

Description

Joint optimization of location, beam, and radio resources of airborne base stations with controllable directional antennas.

[0001] The present disclosure relates to techniques for operating a drone support network, and more particularly, to techniques for optimizing flight paths, beam parameters, and resource allocation of an airborne base station.

[0002] Unmanned Aerial Vehicles (UAVs) offer numerous advantages, including flexible deployment in three-dimensional space, rapid mobility, small size, and low cost, making them widely used in various fields. Wireless networks are also one area where UAVs can enhance network performance. Based on this potential, active research is underway to integrate UAVs into wireless networks, known as "UAV-enabled networks." For example, UAVs can act as aerial base stations (ABSs), relaying data between ground base stations (GBSs) and ground users (GUs).

[0003] Generally, communication antennas come in two types: omnidirectional and directional. Directional antennas allow for adjustable beam direction and beam width, which in turn allows for adjustment of antenna gain. Therefore, if a UAV is equipped with a directional antenna, optimal control of its beam direction and beam width may be necessary.

[0004] Because the optimal beam direction and beam width can vary depending on the UAV's location, joint optimization of position, beam direction, and beam width may be necessary in UAV-supported networks with directional antennas. Furthermore, joint optimization of position, beam direction, and beam width may be necessary for efficient resource utilization in UAV-supported networks.

[0005] For example, a technique may be needed to optimize the position, beam direction, beam parameters, and resource allocation of a UAV while satisfying certain conditions (e.g., QoS conditions, etc.).

[0006] Therefore, we aim to provide a technology for efficiently operating a UAV support network (e.g., a technology for optimizing the position, beam direction, beam parameters, and resource allocation of a UAV while satisfying certain conditions).

[0007] One aspect of the present disclosure provides a method for determining a flight path, beam parameters, and resource allocation of an air base station in a system including a ground base station, an air base station, and a plurality of user devices receiving data from the ground base station through a relay of the air base station, the method comprising: setting a requirement, including a minimum required data transmission rate condition of each user device; and determining a flight path, beam parameters, and resource allocation of the air base station to maximize a sum of reception data transmission rates of the plurality of user devices while satisfying the set requirement.

[0008] In some embodiments, the resource to be allocated may include at least one of: transmission power allocated when the public base station transmits data to the plurality of user devices; bandwidth allocated when the public base station transmits data to the plurality of user devices; and a ratio of resources used by a link between the ground base station and the public base station (hereinafter, “backhaul link”) and a link between the public base station and the plurality of user devices (hereinafter, “access link”).

[0009] In some embodiments, the system operates based on a plurality of time slots, each of the plurality of time slots including a time subslot for a backhaul link and a time subslot for an access link. In some embodiments, the terrestrial base station transmits data to the air base station using a time subslot for the backhaul link included in each of the plurality of time slots, and the air base station transmits data to the plurality of user devices using a time subslot for the access link included in each of the plurality of time slots. In some embodiments, the ratio of the resources may be a ratio of the time subslot for the access link to the time slot.

[0010] In some embodiments, the beam parameter may include at least one of a transmit beam direction and a transmit beam width of the aerial base station.

[0011] In some embodiments, the flight path includes locations of airborne base stations during the relay, and the requirements may further include minimum and maximum heights that the locations may have.

[0012] In some embodiments, the requirement may further include a minimum beamwidth supported by the public base station.

[0013] In some embodiments, the determining step comprises the following mathematical expression:

[0014]

[0015] (Here, and represent the reception data transmission rate and minimum required data transmission rate of the ith user device, respectively. represents the data transmission rate of the backhaul link. Each represents the location, transmission beam direction, and transmission beam width of the above-mentioned aerial base station. and represent the bandwidth and transmission power allocated to the transmission to the ith user device, respectively. is the azimuth and elevation angle Indicates the beam direction expressed as . and represent the beam width and minimum beam width of the above airborne base station, respectively. represents the maximum bandwidth of the above system, represents the maximum transmission power of the above-mentioned public base station. and Each represents the height of the location of the above-mentioned aerial base station, and the minimum and maximum heights that can be located during the relay service period. represents the number of the above multiple user devices. The method further comprises a step of determining based on a solution of the problem expressed as (wherein the ratio of the access link subslots in the time slots composed of the backhaul link subslots and the access link subslots is represented by), and the requirement may be a constraint in the above mathematical expression.

[0016] In some embodiments, the resource to be allocated includes a transmission power allocated when the public base station transmits data to the plurality of user devices; a bandwidth allocated when the public base station transmits data to the plurality of user devices; and a ratio of resources used by a backhaul link and an access link, and the determining step may include a step of determining a flight path, power allocation, and bandwidth allocation of the public base station to maximize a sum of reception data transmission rates of the plurality of user devices while satisfying the set requirement; and a step of determining a beam parameter and a ratio of the resources based on the determined flight path, power allocation, and bandwidth allocation of the public base station.

[0017] In some embodiments, the step of determining the beam parameter and the ratio of the resources may include the step of determining the beam parameter based on the determined flight path of the aerial base station; and the step of determining the ratio of the resources based on the determined flight path, power allocation, bandwidth allocation, and beam parameter of the aerial base station.

[0018] In some embodiments, the beam parameters include a transmission beam direction and a transmission beam width of the aerial base station, and the determining step may include determining a flight path of the aerial base station; and determining the beam direction and the beam width based on the determined flight path.

[0019] In some embodiments, the step of determining the beam direction and the beam width may include the step of determining the beam direction and the beam width such that the transmission beam of the public base station covers all of the plurality of user devices simultaneously, while making the circle formed by the transmission beam the smallest.

[0020] In some embodiments, the determining step may include, in an optimization problem of determining a flight path, beam parameters, and resource allocation of the air base station to maximize a sum of reception data transmission rates of the plurality of user devices while satisfying the set requirements, obtaining an optimal target value of the optimization problem for a given flight path; determining a flight path of the air base station based on the obtained optimal target value; and determining a beam parameter and resource allocation of the air base station based on the determined flight path.

[0021] In some embodiments, the step of obtaining the optimal target value and the step of determining the flight path may be performed based on a particle swarm optimization (PSO) algorithm.

[0022] In some embodiments, the step of determining beam parameters and resource allocation of the aerial base station may include the step of determining the beam parameters based on the determined flight path of the aerial base station; and the step of determining the resource allocation based on the determined beam parameters.

[0023] In some embodiments, the resource to be allocated includes transmission power allocated when the public base station transmits data to the plurality of user devices; bandwidth allocated when the public base station transmits data to the plurality of user devices; and a ratio of resources used by a backhaul link and an access link, and the step of determining the resource allocation may include a step of determining transmission power allocation and bandwidth allocation; and a step of determining the ratio of the resources based on the determined flight path, beam parameters, transmission power allocation, and bandwidth allocation.

[0024] In some embodiments, the electronic device is the airborne base station, and the method may further include performing relaying based on the determined flight path, beam parameters, and resource allocation.

[0025] In some embodiments, the electronic device is a device physically separate from the airborne base station, and the method may further include providing information about the determined flight path, beam parameters, and resource allocation to the airborne base station.

[0026] Another aspect of the present disclosure provides an electronic device for determining a flight path, beam parameters, and resource allocation of an aerial base station in a system including a ground base station, an aerial base station, and a plurality of user devices receiving data from the ground base station via a relay of the aerial base station, the electronic device comprising: a processor; and a computer-readable storage medium comprising instructions, the instructions, in response to execution by the processor, causing the electronic device to perform at least one of the embodiments of the present disclosure.

[0027] Another aspect of the present disclosure provides an electronic device, comprising: a processor; one or more hardware-based transceivers; and a computer-readable storage medium comprising instructions, wherein the instructions, in response to execution by the processor, cause the electronic device to perform at least one of the embodiments of the present disclosure.

[0028] Another aspect of the present disclosure provides a non-transitory recording medium storing instructions readable by a processor of an electronic device, the instructions causing the processor to perform at least one of the embodiments of the present disclosure.

[0029] This Summary is provided to introduce a selection of concepts in a simplified form that are further explained in the Detailed Description below. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all of the problems mentioned in any portion of this specification. In addition to the exemplary aspects, embodiments, and features described above, additional aspects, embodiments, and features will become apparent by reference to the following Detailed Description and Drawings.

[0030] Some embodiments of the present disclosure may have the following advantages. However, this does not mean that all embodiments must include all of the advantages, and the scope of the present invention should not be construed as being limited thereby.

[0031] According to some embodiments, a UAV-supported network may be provided that has excellent system performance (e.g., the sum of the received data rates of user devices) while meeting requirements (e.g., a minimum required data rate requirement).

[0032] According to some embodiments, the location, beam direction, beam width, and resource allocation of ABSs in a UAV-supported network using directional antennas can be jointly optimized.

[0033] Figure 1 illustrates a system for describing some embodiments of a UAV support network.

[0034] Figure 2 illustrates the time slots available to the system.

[0035] Figure 3 is a conceptual diagram explaining the minimum circle problem.

[0036] Figure 4 illustrates an algorithm for determining optimal values ​​for optimal beam direction and optimal beam width based on the minimum circle problem.

[0037] Figure 5 illustrates an algorithm for obtaining an optimal solution and an optimal target value for the problem of mathematical expression 11.

[0038] Figure 6 illustrates an algorithm for finding an optimal solution by applying the PSO algorithm.

[0039] FIG. 7 is a block diagram illustrating an electronic device performing a method according to embodiments of the present disclosure.

[0040] The description of the present invention is merely an example for structural and functional explanation, and therefore, the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, since the embodiments can be modified in various ways and can take various forms, the scope of the present invention should be understood to include equivalents that can realize the technical idea. In addition, the purposes or effects presented in the present invention do not mean that a specific embodiment must include all of them or only such effects, and therefore, the scope of the present invention should not be construed as being limited thereby.

[0041] Meanwhile, the meanings of the terms described in this disclosure should be understood as follows.

[0042] Terms such as "first" and "second" are intended to distinguish one component from another, and the scope of the rights should not be limited by these terms. For example, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

[0043] When a component is said to be "connected" to another component, it should be understood that while it may be directly connected to that other component, there may also be other components intervening. Conversely, when a component is said to be "directly connected" to another component, it should be understood that there are no other intervening components. Similarly, other expressions describing relationships between components, such as "between" and "directly between," or "adjacent to" and "directly adjacent to," should be interpreted similarly.

[0044] Singular expressions should be understood to include plural expressions unless the context clearly indicates otherwise, and terms such as "comprises" or "have" should be understood to specify the presence of a feature, number, step, operation, component, part or combination thereof, but not to exclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0045] For each step, the identifiers (e.g., a, b, c, etc.) are used for convenience of explanation and do not describe the order of the steps. The steps may occur in a different order than stated unless the context clearly dictates a specific order. That is, the steps may occur in the same order as stated, may be performed substantially simultaneously, or may be performed in the opposite order.

[0046] Figure 1 illustrates a system for describing some embodiments of a UAV support network.

[0047] In some embodiments, as illustrated in FIG. 1, the system (100) may include GBS (110), ABS (120), and user equipment (UE, 130_1, 130_2, …, 130_8) of GUs.

[0048] In some embodiments, ABS (120) may be implemented as a UAV.

[0049] In some embodiments, each GU (user index i = 1, …, N, N = 9 in FIG. 1) may receive communication services through communication between its UE (130_1, 130_2, …, 130_9) and the ABS (120). For example, the ABS (120) may receive data (downlink data) transmitted from the GBS (110) through a backhaul link and then transmit the received data to the corresponding UE through a connection link. In another example, the ABS (120) may receive data (uplink data) transmitted from each UE through a connection link and then transmit the received data to the GBS (110) through a backhaul link. For convenience, the former case (relaying of downlink data) will be assumed in the following description of some embodiments.

[0050] In some embodiments, the ABS (120) can fly along a path (i.e., a flight path) to be relayed, and the beam direction ( ), and the beam width (Ω) can be adjusted.

[0051] For example, the flight path is each location (where ABS (120) flies during the relay service) ) can be expressed as a set of .

[0052] For example, the beam direction ( ) is, as illustrated in Fig. 1, the azimuth ( ) and elevation angle ( ) can be expressed as.

[0053] Figure 2 illustrates the time slots available to the system.

[0054] In some embodiments, as illustrated in FIG. 2, communication devices within the system (100) may communicate in units of time slots (T). For example, each time slot (T) represents a time ratio between the access link and the backhaul link. It can be divided into a sub-slot for a connection link and a sub-slot for a backhaul link.

[0055] In some embodiments, for transmission of access links (in case of downlink transmission, links from ABS to each UE), power (p1, p2, p3, …, p N ) and bandwidth (b1,b2,b3, …,b N ) can be assigned.

[0056] In some embodiments, in the UAV-supported network system illustrated in FIG. 1, an electronic device determines a flight path, beam parameters, and resource allocation of an ABS (e.g., the ABS illustrated in FIG. 1), and based on the determined results, the UAV can perform a relay service.

[0057] Hereinafter, for convenience, an electronic device that determines a flight path, beam parameters, and resource allocation will be referred to as an optimization device to describe several embodiments. As an example, the optimization device may be an ABS. In this case, the ABS determines the flight path, beam parameters, and resource allocation, and the UAV can perform a relay service based on the determined results. As another example, the optimization device may be a device physically separate from the ABS (e.g., the GBS illustrated in FIG. 1, or a separate device not illustrated in FIG. 1). In this case, the optimization device may provide information about the determined flight path, beam parameters, and resource allocation to the ABS, so that the UAV can perform a relay service accordingly.

[0058] In some embodiments, the optimization device may, after setting requirements, determine flight paths, beam parameters, and resource allocations of ABSs to maximize the sum of received data transmission rates of a plurality of user devices (e.g., UEs of the GUs illustrated in FIG. 1) while satisfying the set requirements.

[0059] In some embodiments, the requirements may include a minimum required data transfer rate requirement for each user device.

[0060] In some embodiments, the resource to be allocated may include at least one of: transmission power allocated when the ABS transmits data to the plurality of user devices; bandwidth allocated when the ABS transmits data to the plurality of user devices; and a ratio of resources used by the backhaul link and the access link.

[0061] In some embodiments, the ratio of the resources is the ratio of the time subslots for the access link to the time slots ( ) may be.

[0062] In some embodiments, the beam parameter is a transmit beam direction of the ABS ( ) and transmission beam width ( ) may include at least one of the following.

[0063] In some embodiments, the flight path is the positions of the ABS during the relay ( ) and the above requirements are the minimum height that the above locations can have ( ) and maximum height ( ) may be included.

[0064] In some embodiments, the requirement is the minimum beamwidth supported by the airborne base station ( ) may be included.

[0065] In some embodiments, the optimization device can determine the flight path, beam parameters, and resource allocation of the ABS by finding a solution to an optimization problem expressed by Equation 1.

[0066]

[0067] Here, i represents the index of the user device (UEs of GUs in Fig. 1) and can have a value from 1 to N (9 in the case of Fig. 1).

[0068] and represents the reception data transmission rate and minimum required data transmission rate of the i-th user device, respectively. represents the data transmission rate of the backhaul link. and can be expressed by mathematical expressions 2 and 3.

[0069] and represents the bandwidth and transmission power allocated to transmission to the i-th user device, respectively. represents the maximum bandwidth of the above system, represents the maximum transmission power of the ABS. Indicates the height of the ABS position.

[0070] In mathematical expression 1, (1b) is the transmission rate requirement described above, and (1c) to (1j) are conditions that the system must basically satisfy for the relay service, or represent the minimum or maximum value of each parameter.

[0071]

[0072]

[0073] In equations 2 and 3 and represent the achievable data transmission rate of the backhaul link and the achievable data transmission rate of the i-th UE-related link among the access links, respectively, and can be expressed by mathematical expressions 4 and 5, respectively.

[0074]

[0075]

[0076] In mathematical formula 4 and is the transmission power and bandwidth of GBS (110), which in some embodiments is a fixed value in the optimization problem (e.g., ) can be set. is a channel gain of a backhaul link and can be expressed as a function of the distance between GBS (110) and ABS (120), various constants (such as path loss constant), the transmit antenna gain of GBS (110), and the receive antenna gain of ABS (120). The transmit antenna gain of GBS (110) and the receive antenna gain of ABS (120) can be set to fixed values ​​in the optimization problem. is the noise spectral density.

[0077] In mathematical equation 5 and is the transmission power and bandwidth of ABS (110) for the link to the i-th UE, is the channel gain of the link, which can be expressed as a function of the distance between the ABS (110) and the UE, various constants (such as a path loss constant), the transmit antenna gain of the ABS (110), and the receive antenna gain of the UE. In some embodiments of the ABS (110), the transmit antenna gain can be expressed as a function of the transmit beamwidth of the ABS (120). In some embodiments, the receive antenna gain of the UE can be set to a fixed value in the optimization problem.

[0078] at last and can be expressed as decision variables of the optimization problem of mathematical expression 1.

[0079] In some embodiments, the optimization device may determine a flight path, power allocation, and bandwidth allocation of the air base station to maximize the sum of the reception data transmission rates of the plurality of user devices while satisfying the set requirement, and may determine a beam parameter and a ratio of the resources based on the determined flight path, power allocation, and bandwidth allocation of the air base station. For example, Equation 1 , and This is because it can be reconstructed as an optimization problem with only .

[0080] In some embodiments, the optimization device determines the beam parameters based on the determined flight path of the aerial base station, and determines the ratio of the resources based on the determined flight path, power allocation, bandwidth allocation, and beam parameters of the aerial base station. ) can be determined.

[0081] For example, the optimization device may have a ratio of the above resources ( ) can be obtained using mathematical formula 6.

[0082]

[0083] For example, if Equation 6 is applied to Equation 1, Equation 7 without the decision variable δ is obtained.

[0084]

[0085] In some embodiments, the optimization device can determine a flight path of the ABS and determine the beam direction and the beam width based on the determined flight path.

[0086] The optimization device can determine the optimal beam direction and width by solving the smallest circle enclosing problem based on the determined flight path. The technique presented in E. Welzl's paper, "Smallest enclosing disks (balls and ellipsoids)," in New Results and New Trends in Computer Science, 1991, pp. 359-370, can be used to solve the smallest circle problem.

[0087] Figure 3 is a conceptual diagram explaining the minimum circle problem.

[0088] In some embodiments, the optimization device can determine the beam direction and the beam width such that the transmit beam of the ABS covers all of the plurality of user devices simultaneously, while making the circle formed by the transmit beam (the dotted circle shown in FIG. 3) the smallest. That is, the optimization device can determine the beam direction and the beam width such that the circle formed by the transmit beam (the dotted circle shown in FIG. 3) is the smallest. About and To obtain , we can use the minimum circle problem, which is the problem of finding the smallest circle containing a finite set of points in a plane, as illustrated in Fig. 3.

[0089] For example, the optimization device can determine the optimal beam direction and optimal beam width using Equations 8 and 9.

[0090]

[0091]

[0092] Here, the street is calculated in spherical coordinates.

[0093] Figure 4 illustrates an algorithm for determining optimal values ​​for optimal beam direction and optimal beam width based on the minimum circle problem.

[0094] For example, the optimization device can determine the optimal beam direction and optimal beam width using Algorithm 1 illustrated in FIG. 4.

[0095] Algorithm 1 follows the structure of a recursive algorithm, as illustrated in Fig. 4.

[0096] In the base case, the smallest circle can be easily obtained when the number of given points is three or less (line 3-6 of Algorithm 1).

[0097] In a recursive step, one of the given points is randomly selected and the smallest circle of the remaining points excluding the selected point is found (lines 8-9 of Algorithm 1).

[0098] If the selected point is outside the smallest circle obtained above, a recursive step is performed to find the smallest circle that the point is above (i.e., on the line of the circle) (lines 10-13 of Algorithm 1).

[0099] By recursively performing the algorithm in this way, a circle that all given points are inside or on can be provided (line 14 of Algorithm 1).

[0100] The resulting circle is given by N points, is the smallest circle for .

[0101] In some embodiments, the obtained If the range condition is not satisfied, it can be adjusted so that it is satisfied, and then the optimal beam direction and beam width can be finally determined. For example, the obtained beam width This minimum beam width If it is smaller than, silver can be finally decided.

[0102] In the optimization problem of mathematical expression 7 and Each of the mathematical formulas 8 And mathematical formula 9 If we replace it with , the optimization problem in Equation 7 becomes It can be reconstructed into mathematical expression 10.

[0103]

[0104] Here For simplicity of explanation, I would like to express myself on behalf of .

[0105] The objective function (10a) of Equation 10 is a concave function, and constraints (1d), (1e), and (1i) are all linear inequalities and satisfy a convex set. Therefore, the optimization problem of Equation 10 is a convex optimization problem. The optimization problem of Equation 10 can be solved using a standard algorithm for convex optimization problems. In the following, the solution of the optimization problem of Equation 10 is I want to express it as .

[0106] As mentioned above, given The optimal solution to the optimization problem of mathematical expression 1 for , Ω, b, p, and ) can be obtained. That is, given The optimization problem of mathematical expression 1 can be expressed as the optimization problem of mathematical expression 11.

[0107]

[0108] Below, given The optimal target value for problem (11) and express them as , and their optimal solutions are I want to express it as .

[0109] Figure 5 illustrates an algorithm for obtaining an optimal solution and an optimal target value for the problem of mathematical expression 11.

[0110] The optimization device is expressed by mathematical expression 6. By substituting into Equation 1, Equation 7 is derived (line 1 of Algorithm 2).

[0111] The optimization device uses Algorithm 1 (e.g., Algorithm 1 illustrated in Fig. 4). Find (line 2 of Algorithm 2).

[0112] The optimization device is obtained By substituting Equation 7 into Equation 10, an optimization problem is formed (line 3 of Algorithm 2).

[0113] The optimization device solves the optimization problem of Equation 10. Find (line 4 of the algorithm)

[0114] The optimization device uses mathematical expression 6. Save.

[0115] The only task left to solve the problem in Equation 1 is The goal is to obtain the optimal solution. To achieve this, the following optimization problem must be solved.

[0116]

[0117] In some embodiments, the optimization device can apply a particle swarm optimization (PSO) algorithm to solve the problem of Equation 12. Is Since it is difficult to express the closed-form expression of , it is difficult to solve the problem of Equation 12 analytically. A detailed description of the PSO algorithm itself is given in the paper J. Kennedy and R. Eberhart, "Particle swarm optimization," in Proc. Int. Conf. Neural Netw. (ICNN'95), 1995, pp. 1942-1948. and the paper R. Poli, J. Kennedy, and T. Blackwell, "Particle swarm optimization," Swarm Intell., vol. 1, no. 1, pp. 33-57, Aug. 2007.

[0118] Figure 6 illustrates an algorithm for finding an optimal solution by applying the PSO algorithm.

[0119] In Algorithm 3 represents the position of the ith particle in the tth iteration. represents the updated difference in the position of the ith particle.

[0120] is the best position of the i-th particle until the t-th iteration, is the best position among all particles up to the tth iteration.

[0121] In some embodiments, the optimization device may obtain an optimal target value of the optimization problem for a given flight path, determine a flight path of the airborne base station based on the obtained optimal target value (up to line 21 of Algorithm 3), and then determine beam parameters and resource allocation of the airborne base station based on the determined flight path (line 22 of Algorithm 3).

[0122] In some embodiments, the optimization device may obtain the optimal target value and determine the flight path based on a particle swarm optimization (PSO) algorithm.

[0123] In some embodiments, the optimization device may determine the beam parameter based on the determined flight path of the aerial base station, and determine the resource allocation based on the determined beam parameter.

[0124] In some embodiments, the optimization device may determine a transmission power allocation and a bandwidth allocation in determining the resource allocation, and may determine a ratio of the resources based on the determined flight path, beam parameters, transmission power allocation, and bandwidth allocation.

[0125] Referring to Figure 6, through lines 1-6, the initial position of each particle is set, and the set initial position Using Algorithm 2 based on Find the best location is the set initial position is updated, is initialized randomly within the available set.

[0126] Through lines 7-8, the P numbers obtained previously The largest value among Set to .

[0127] Then, repeat lines 11-20 while increasing the iteration index t until a given termination condition is satisfied. The termination condition can be the maximum value of the iteration index, the total execution time of the algorithm, the number of iteration indices at which the optimal solution is not updated, or the execution time at which the optimal solution is not updated.

[0128] As the equation in line 13 is renewed, and renewed is used to determine the next position of each particle in line 14.

[0129] After convergence is selected as the optimal position value, and the optimal solutions are obtained using Algorithm 2 in line 22. is used to obtain .

[0130] Algorithm 3 provides an approximate optimal solution to the problem in Equation 12, which allows us to approximately solve the original problem in Equation 1.

[0131] FIG. 7 is a block diagram illustrating an electronic device that performs a method according to embodiments of the present disclosure. In FIG. 7, the electronic device (700) is described as a single physical device, but depending on the embodiment, the electronic device (700) may be implemented in a form in which multiple devices are linked together (e.g., distributed computing).

[0132] In some embodiments, the electronic device (700) may include a memory (710), a processor (720), and a communication module (730), as illustrated in FIG. 7 . In some other embodiments, the electronic device (700) may further include all or some of the input / output interface (740) and other units. For example, if the electronic device (700) performing the embodiments is an unmanned aerial vehicle, it may further include units such as a flight means.

[0133] The memory (710) is a recording medium readable by an electronic device (e.g., a computer), and may include a random access memory (RAM), a read only memory (ROM), and a permanent mass storage device such as a disk drive. Here, the ROM and the permanent mass storage device may be included as a separate permanent storage device separate from the memory (710). In addition, the memory (710) may store an operating system and at least one program code (for example, a program such as a computer program for controlling the electronic device (700) by being stored on a recording medium included in the electronic device (700) to perform a method according to embodiments of the present disclosure). These software components may be loaded from a recording medium readable by an electronic device separate from the memory (710). The recording medium readable by the separate electronic device may include a recording medium readable by an electronic device such as a floppy drive, a disk, a tape, a DVD / CD-ROM drive, a memory card, etc. In another embodiment, the software components may be loaded into the memory (710) via a communication module (730) rather than a readable recording medium on the electronic device.

[0134] The processor (720) may be configured to process instructions of a program, such as a computer program, by performing basic arithmetic, logic, and input / output operations. Instructions may be provided to the processor (720) by the memory (710) or the communication module (730). For example, the processor (720) may be configured to execute instructions received according to program code loaded into the memory (710). More specifically, the processor (720) may sequentially execute instructions according to the code of the computer program loaded into the memory (710) to perform processing related to a drone support network according to an embodiment of the present disclosure (e.g., optimization of flight paths, beam parameters, and resource allocation of an airborne base station). The communication module (730) may provide a function for communicating with other physical devices through a communication network, such as a computer network. For example, the present disclosure may be implemented in a manner in which a processor (720) of an electronic device (700) performs a part of the process of the present embodiment, and another physical device (e.g., an electronic device such as another computer, not shown) of a communication network performs the remaining process, while exchanging the processing results with the communication network through a communication module (730).

[0135] The input / output interface (740) may be a means for interfacing with an input / output device (750). For example, in the input / output device (750), the input device may include a device such as a keyboard or a mouse, and the output device may include a device such as a display or a speaker. In FIG. 7, the input / output device (750) is represented as a separate device from the electronic device (700), but depending on the embodiment, the electronic device (700) may be implemented such that the input / output device (750) is included in the electronic device (700).

[0136] The devices described above may be implemented as hardware components, software components, and / or a combination of hardware components and software components. For example, the devices and components described in the embodiments may be implemented using one or more general-purpose computers or special-purpose computers, such as a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a programmable logic unit (PLU), a microprocessor, or any other device capable of executing instructions and responding to them. The electronic device (700) may execute an operating system (OS) and one or more software applications running on the operating system. In addition, the electronic device (700) may access, store, manipulate, process, and generate data in response to the execution of software. For ease of understanding, the electronic device (700) is sometimes described as being used alone. However, those skilled in the art will appreciate that the electronic device (700) may include multiple processing elements and / or multiple types of processing elements. For example, the electronic device (700) may include multiple processors or one processor and one controller. Additionally, other processing configurations, such as parallel processors, are also possible.

[0137] The software may include a computer program, code, instructions, or a combination of one or more of these, and may configure the electronic device (700) to operate as desired or may independently or collectively command the electronic device (700). The software and / or data may be embodied in any type of machine, component, physical device, computer storage medium, or device for interpretation by the electronic device (700) or for providing instructions or data to the electronic device (700). The software may also be distributed across networked computer systems and stored or executed in a distributed manner. The software and data may be stored on one or more computer-readable recording media.

[0138] The method according to the embodiment may be implemented in the form of program commands that can be executed through various computer means and recorded on a computer-readable medium. At this time, the medium may be one that continuously stores a computer-executable program or one that temporarily stores it for execution or download. In addition, the medium may be various recording means or storage means in the form of a single or multiple hardware combinations, and is not limited to a medium directly connected to a computer system, but may also be distributed on a network. Examples of the medium may include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, and those configured to store program commands, including ROM, RAM, and flash memory. In addition, examples of other media may include recording media or storage media managed by app stores that distribute applications, sites that supply or distribute various software, servers, etc.

[0139] Although the embodiments described above have been described by way of limited examples and drawings, those skilled in the art will appreciate that various modifications and variations can be made based on the above teachings. For example, appropriate results can still be achieved even if the described techniques are performed in a different order than described, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents.

[0140] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims described below.

Claims

1. In a system including a ground base station, an air base station, and a plurality of user devices receiving data from the ground base station through a relay of the air base station, a method for an electronic device to determine a flight path, beam parameters, and resource allocation of the air base station, A step for setting requirements - including minimum required data transfer rate conditions for each user device; and A method comprising the step of determining a flight path, beam parameters, and resource allocation of the airborne base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the set requirements.

2. In paragraph 1, the resource that is the target of the resource allocation is Transmission power allocated when the above public base station transmits data to the plurality of user devices; The bandwidth allocated when the above public base station transmits data to the plurality of user devices; and The ratio of resources used by the link between the ground base station and the aerial base station (hereinafter, backhaul link) and the link between the aerial base station and the plurality of user devices (hereinafter, access link) A method comprising at least one of:

3. In paragraph 2, The above system operates based on multiple time slots, Each of the above multiple time slots includes a time subslot for a backhaul link and a time subslot for an access link, The above ground base station transmits data to the air base station using a time subslot for a backhaul link included in each of the plurality of time slots, The above-mentioned public base station transmits data to the plurality of user devices using a time subslot for an access link included in each of the plurality of time slots, A method in which the ratio of the above resources is the ratio of the time subslots for the above access link to the above time slots.

4. In the first paragraph, the beam parameter is A method comprising at least one of a transmission beam direction and a transmission beam width of the above-mentioned aerial base station.

5. In paragraph 1, The above flight path includes the locations of the airborne base stations during the above relay, The above requirements further include a minimum height and a maximum height that the above locations can have.

6. In paragraph 1, The above requirements further include a minimum beamwidth supported by the above airborne base station.

7. In paragraph 1, The above setting step and the above determining step are based on the following mathematical formula (Here, and represents the reception data transmission rate and minimum required data transmission rate of the i-th user device, respectively. represents the data transmission rate of the backhaul link. Each represents the location, transmission beam direction, and transmission beam width of the above-mentioned aerial base station. and represent the bandwidth and transmission power allocated to the transmission to the ith user device, respectively. is the azimuth and elevation angle Indicates the beam direction expressed as . and represent the beam width and minimum beam width of the above airborne base station, respectively. represents the maximum bandwidth of the above system, represents the maximum transmission power of the above-mentioned public base station. and Each represents the height of the location of the above-mentioned aerial base station, and the minimum and maximum heights that can be located during the relay service period. represents the number of the above multiple user devices. A method performed based on an optimization problem expressed as (where ) represents the ratio of access link subslots in a time slot composed of backhaul link subslots and access link subslots.

8. In paragraph 1, The resources subject to the above resource allocation are The transmission power allocated when the public base station transmits data to the plurality of user devices; the bandwidth allocated when the public base station transmits data to the plurality of user devices; and the ratio of resources used by the backhaul link and the access link, The above decision steps are A step of determining a flight path, power allocation, and bandwidth allocation of the airborne base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the above-mentioned set requirements; and A method comprising the step of determining beam parameters and a ratio of the resources based on the determined flight path, power allocation, and bandwidth allocation of the aerial base station.

9. In the 8th paragraph, the step of determining the ratio of the beam parameter and the resource A step of determining the beam parameters based on the flight path of the determined aerial base station; and A method comprising the step of determining the ratio of the resources based on the determined flight path, power allocation, bandwidth allocation, and beam parameters of the aerial base station.

10. In paragraph 1, The above beam parameters include the transmission beam direction and transmission beam width of the above aerial base station, A method wherein the determining step comprises: determining a flight path of the aerial base station; and determining the beam direction and the beam width based on the determined flight path.

11. In the 10th paragraph, the step of determining the beam direction and the beam width is A method comprising the step of determining the beam direction and the beam width so that the transmission beam of the above-mentioned public base station covers all of the plurality of user devices simultaneously, while making the circle formed by the transmission beam the smallest.

12. In paragraph 1, The above decision steps are In an optimization problem of determining a flight path, beam parameters, and resource allocation of the airborne base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the above-mentioned set requirements, a step of obtaining an optimal target value of the optimization problem for a given flight path; A step of determining a flight path of the aerial base station based on the obtained optimal target value; and A method comprising the step of determining beam parameters and resource allocation of the aerial base station based on the determined flight path.

13. In paragraph 12, A method in which the step of obtaining the above optimal target value and the step of determining the flight path are performed based on a particle swarm optimization (PSO) algorithm.

14. In the 12th paragraph, the step of determining beam parameters and resource allocation of the aerial base station is A step of determining the beam parameters based on the flight path of the determined aerial base station; and A method comprising a step of determining the resource allocation based on the determined beam parameters.

15. In paragraph 14, The resources subject to the resource allocation include transmission power allocated when the public base station transmits data to the plurality of user devices; bandwidth allocated when the public base station transmits data to the plurality of user devices; and the ratio of resources used by the backhaul link and the access link. The step of determining the above resource allocation is A step of determining transmission power allocation and bandwidth allocation; and A method comprising the step of determining the ratio of the resources based on the determined flight path, beam parameters, transmission power allocation and bandwidth allocation.

16. In paragraph 1, The above electronic device is the above air base station, The method further comprises a step of performing relaying based on the determined flight path, beam parameters, and resource allocation.

17. In paragraph 1, The above electronic device is a device physically separated from the above public base station, The method further comprises the step of providing information on the determined flight path, beam parameters, and resource allocation to the airborne base station.

18. An electronic device for determining a flight path, beam parameters, and resource allocation of an aerial base station in a system including a ground base station, an aerial base station, and a plurality of user devices receiving data from the ground base station through a relay of the aerial base station, processor; and A computer-readable storage medium comprising instructions, An electronic device, wherein the command, in response to execution by the processor, causes the electronic device to perform the method described in any one of claims 1 to 15.

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