Joint Optimization of Location, Beam, and Radio Resource for an Aerial Base Station With Controllable Directional Antennas

Abstract

A technology for operating an unmanned aerial vehicle support network is disclosed. In one embodiment, a method for an electronic device to determine a flight path, beam parameters, and resource allocation of an air base station in a system comprising a ground base station, an air base station, and a plurality of user devices receiving data from the ground base station through relay of the air base station may include: a step of setting a requirement condition—including a minimum required data transmission rate condition for each user device—and a step of determining a flight path, beam parameters, and resource allocation of the air base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the set requirement condition.

Description

Technology Field

[0001] The present disclosure relates to technology for operating an unmanned aerial vehicle support network, and more specifically, some embodiments relate to technology for optimizing flight paths, beam parameters, and resource allocation of airborne base stations. Background Technology

[0002] Unmanned aerial vehicles (UAVs) are widely used in various fields due to their many advantages, such as flexible deployment in three-dimensional space, rapid mobility, small size, and low cost. Wireless networks are also one of the fields where network performance can be improved using UAVs. Based on these possibilities, research on integrating UAVs into wireless networks is actively underway, and this is referred to as a 'UAV-enabled network'. For example, UAVs can act as Aerial Base Stations (ABS) to relay data between Ground Base Stations (GBS) and Ground Users (GU).

[0003] Generally, there are two types of communication antennas: omnidirectional antennas and directional antennas. Directional antennas can adjust the beam direction and beam width, which in turn allows for the control of antenna gain. Therefore, if a UAV is equipped with a directional antenna, it may be necessary to optimally control its beam direction and beam width.

[0004] Since the optimal beam direction and beam width can vary depending on the UAV's location, joint optimization of location, beam direction, and beam width may be necessary in UAV support networks equipped with directional antennas. Furthermore, such joint optimization may require efficient resource utilization within the UAV support network.

[0005] For example, technology may be required to optimize the position, beam direction, beam parameters, and resource allocation of a UAV while satisfying certain conditions (e.g., QoS conditions). The problem to be solved

[0006] Therefore, we aim to provide technology for efficiently operating an unmanned aerial vehicle support network (e.g., technology that optimizes the position, beam direction, beam parameters, and resource allocation of UAVs while satisfying specific conditions). means of solving the problem

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

[0008] In some embodiments, the resource subject to the resource allocation may include at least one of: transmission power allocated when the air base station transmits data to the plurality of user devices; bandwidth allocated when the air 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 air base station (hereinafter, backhaul link) and the link between the air base station and the plurality of user devices (hereinafter, connection link).

[0009] In some embodiments, the system operates based on a plurality of time slots, and each of the plurality of time slots may include a time subslot for a backhaul link and a time subslot for a connection link. In some embodiments, the ground base station transmits data to the air base station using the time subslot for a 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 the time subslot for a connection link included in each of the plurality of time slots. In some embodiments, the ratio of the resource may be the ratio occupied by the time subslot for the connection link in the time slot.

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

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

[0012] In some embodiments, the requirement may further include a minimum beam width supported by the airborne base station.

[0013] In some embodiments, the determining step is as follows:

[0014]

[0015] (Here, and represents the received data transmission rate and the 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 airborne base station. and represents the bandwidth and transmission power allocated to transmission to the i-th user device, respectively. is the azimuth and elevation angle It indicates the beam direction expressed as. and represents the beam width and minimum beam width of the above-mentioned airborne base station, respectively. B max represents the maximum bandwidth of the above system, and P max represents the maximum transmission power of the above-mentioned airborne base station. and Each represents the height among the locations of the above-mentioned airborne base stations, the minimum height and maximum height at which they can be located during the relay service period. ... indicates the number of the above multiple user devices. The method includes a step of determining based on the solution to the problem expressed as (which represents the ratio of the connection link subslot to the time slot composed of the backhaul link subslot and the connection link subslot), and the above requirement may be a constraint in the above mathematical formula.

[0016] In some embodiments, the resources subject to resource allocation include transmission power allocated when the air base station transmits data to the plurality of user devices; bandwidth allocated when the air base station transmits data to the plurality of user devices; and the ratio of resources used by the backhaul link and the access link, and the determining step may include the step of determining the flight path, power allocation, and bandwidth allocation of the air base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the set requirements; and the step of determining beam parameters and the ratio of resources based on the determined flight path, power allocation, and bandwidth allocation of the air base station.

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

[0018] In some embodiments, the beam parameters include the transmission beam direction and transmission beam width of the air base station, and the determining step may include the step of determining the flight path of the air base station; and the step of 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 air base station simultaneously covers all of the plurality of user devices, while minimizing the circle formed by the transmission beam.

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

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

[0025] In some embodiments, the electronic device is a device physically separated from the airborne base station, and the method may further include the step of providing information regarding 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 air base station in a system comprising a ground base station, an air base station, and a plurality of user devices receiving data from the ground base station through relay of the air base station, the electronic device comprising: a processor; and a computer-readable storage medium comprising instructions, wherein the instructions cause the electronic device to perform at least one of the embodiments of the present disclosure in response to execution by the processor.

[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 enable the electronic device to perform at least one of the embodiments of the present disclosure in response to execution by the processor.

[0028] Another aspect of the present disclosure is a non-transient recording medium for storing instructions readable by a processor of an electronic device, wherein the instructions provide a recording medium that enables the processor to perform at least one of the embodiments of the present disclosure.

[0029] This summary is provided to introduce, in a simplified form, selected concepts among those further described in the following detailed description. This summary is not intended to identify the core or essential features of the subject matter of the claimed invention, nor is it intended to be used to limit the scope of the subject matter of the claimed invention. Furthermore, the subject matter of the claimed invention is not limited to implementations that solve some or all of the problems mentioned in any part of this specification. In addition to the exemplary aspects, embodiments, and features described above, additional aspects, embodiments, and features will become apparent with reference to the following detailed description and drawings. Effects of the invention

[0030] Some embodiments of the present disclosure may have effects including the following advantages. However, this does not mean that all embodiments must include all of these, and therefore the scope of the present invention should not be understood as being limited by them.

[0031] According to some embodiments, a UAV-supported network with excellent system performance (e.g., sum of received data transmission rates of user devices) can be provided while satisfying requirements (e.g., minimum required data transmission rate conditions).

[0032] According to some embodiments, the location, beam direction, beam width, and resource allocation of ABS in a UAV support network using directional antennas can be jointly optimized. Brief explanation of the drawing

[0033] FIG. 1 illustrates a system for explaining some embodiments of a UAV support network. Figure 2 illustrates the time slots available to the system. Figure 3 is a conceptual diagram to explain the minimum circle problem. Figure 4 illustrates an algorithm for determining the optimal beam direction and optimal beam width based on the minimum circle problem. Figure 5 illustrates an algorithm for finding the optimal solution and optimal target value of the problem in Equation 11. Figure 6 illustrates an algorithm for finding the optimal solution by applying the PSO algorithm. FIG. 7 is a block diagram illustrating an electronic device for performing a method according to embodiments of the present disclosure. Specific details for implementing the invention

[0034] The description of the present invention is merely an example for structural or functional explanation, and therefore the scope of the present invention should not be interpreted as being limited by the examples described in the text. That is, since the examples are subject to various modifications and may take various forms, the scope of the present invention should be understood to include equivalents capable of realizing the technical concept. Furthermore, the objectives or effects presented in the present invention do not imply that a specific example must include all of them or only such effects; therefore, the scope of the present invention should not be understood as being limited by them.

[0035] Meanwhile, the meaning of the terms described in this disclosure should be understood as follows.

[0036] Terms such as "first," "second," etc., are intended to distinguish one component from another, and the scope of rights shall not be limited by these terms. For example, the first component may be named the second component, and similarly, the second component may be named the first component.

[0037] When it is stated that one component is "connected" to another component, it should be understood that it may be directly connected to that other component, or that there may be other components in between. Conversely, when it is stated that one component is "directly connected" to another component, it should be understood that there are no other components in between. Meanwhile, other expressions describing the relationships between components, such as "between" and "exactly between," or "adjacent to" and "directly adjacent to," should be interpreted in the same way.

[0038] A singular expression should be understood to include a plural expression unless the context clearly indicates otherwise, and terms such as "include" or "have" are intended to specify the existence of the implemented features, numbers, steps, actions, components, parts, or combinations thereof, and should be understood not to preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0039] In each step, 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 differently from the specified order unless a specific order is clearly indicated in the context. That is, the steps may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

[0040] FIG. 1 illustrates a system for explaining some embodiments of a UAV support network.

[0041] In some embodiments, as illustrated in FIG. 1, the system (100) may include user equipment (hereinafter UE, 130_1, 130_2, …, 130_8) of the GBS (110), ABS (120), and GUs.

[0042] In some embodiments, the ABS (120) can be implemented as a UAV.

[0043] In some embodiments, each GU (user index) i= 1, … , N (N=9 in FIG. 1) can receive communication services through communication between its UE (130_1, 130_2, …, 130_9) and ABS (120). For example, ABS (120) can receive data (downlink data) transmitted from GBS (110) via a backhaul link and then transmit the received data to the corresponding UE via a connection link. As another example, ABS (120) can receive data (uplink data) transmitted from each UE via a connection link and then transmit the received data to GBS (110) via a backhaul link. For convenience, several embodiments will be described below assuming the former case (relaying downlink data).

[0044] In some embodiments, the ABS (120) can fly along a relay service path (i.e., flight path) and beam direction ( ), beam width (Ω) can be adjusted.

[0045] For example, the flight path is each location where the ABS (120) flies during the relay service ( It can be expressed as a set of ).

[0046] For example, beam direction ( ) is, as exemplified in FIG. 1, the azimuth angle ( ) and elevation angle( It can be expressed as ).

[0047] Figure 2 illustrates the time slots available to the system.

[0048] In some embodiments, as illustrated in FIG. 2, communication devices within the system (100) may perform communication in units of time slots (T). For example, each time slot (T) is the time ratio between a connection link and a backhaul link. It can be partitioned according to and configured into a sub-slot for a connection link and a sub-slot for a backhaul link.

[0049] In some embodiments, for transmitting a connection link (in the case of downlink transmission, the link from the ABS to each UE), power ( p 1, p 2, p 3, … , p N ) and bandwidth( b 1, b 2, b 3, … , b N ) can be assigned.

[0050] In some embodiments, in the UAV support network system illustrated in FIG. 1, the electronic device determines the flight path, beam parameters, and resource allocation of the ABS (e.g., the ABS illustrated in FIG. 1), and based on the determined results, the UAV can perform relay services.

[0051] Hereinafter, for convenience, an electronic device that determines a flight path, beam parameters, and resource allocation will be referred to as an optimization device, and several embodiments will be described. For example, the optimization device may be an ABS. In this case, the ABS determines the flight path, beam parameters, and resource allocation, and based on the determined results, the UAV can perform relay services. In another example, the optimization device may be a device physically separated from the ABS (e.g., the GBS exemplified in FIG. 1, or a separate device not shown in FIG. 1). In this case, the optimization device may provide information regarding the determined flight path, beam parameters, and resource allocation to the ABS so that relay services can be performed accordingly.

[0052] In some embodiments, the optimization device may determine the flight path, beam parameters, and resource allocation of the ABS to maximize the sum of the 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.

[0053] In some embodiments, the requirement may include a minimum required data transfer rate condition for each user device.

[0054] In some embodiments, the resource subject to the resource allocation 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 the ratio of resources used by the backhaul link and the connection link.

[0055] In some embodiments, the ratio of the resource is the ratio that the time sub-slot for the connection link occupies in the time slot ( It can be.

[0056] In some embodiments, the beam parameter is the transmission beam direction of the ABS ( ) and transmit beam width ( It may include at least one of ).

[0057] In some embodiments, the flight path is the locations of the ABS during the relay ( Includes ), and the above requirement is the minimum height that the above locations can have ( ) and maximum height( It may include more ).

[0058] In some embodiments, the requirement is the minimum beam width supported by the air base station ( It may include more ).

[0059] In some embodiments, the optimization device can determine the flight path, beam parameters, and resource allocation of the ABS by finding a solution to the optimization problem expressed by Equation 1.

[0060]

[0061] Here, irepresents the index of a user device (UEs of the GUs in FIG. 1), and 1 to N It can have values ​​up to (9 in the case of Fig. 1).

[0062] and are each i It indicates the received data transmission rate and the minimum required data transmission rate of the nth user device. represents the data transmission rate of the backhaul link. and It can be expressed by mathematical formula 2 and mathematical formula 3.

[0063] and are each i It indicates the bandwidth and transmission power allocated for transmission to the th user device. represents the maximum bandwidth of the above system, and represents the maximum transmission power of ABS. represents the height among the ABS positions.

[0064] In mathematical formula 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.

[0065]

[0066]

[0067] In mathematical formulas 2 and 3 and represents the achievable data transmission rate of the backhaul link and the achievable data transmission rate of the i-th UE-related link among the connection links, respectively, and can be expressed by mathematical equations 4 and 5, respectively.

[0068]

[0069]

[0070] In mathematical formula 4 and is the transmission power and bandwidth of the GBS (110), and in some embodiments, a fixed value in the optimization problem (e.g., It can be set to ). The channel gain of the backhaul link can be expressed as a function of the distance between the GBS (110) and the ABS (120), various constants (path loss constant, etc.), the transmitting antenna gain of the GBS (110), and the receiving antenna gain of the ABS (120). The transmitting antenna gain of the GBS (110) and the receiving antenna gain of the ABS (120) can be set to fixed values ​​in the optimization problem. is the noise spectral density.

[0071] In mathematical formula 5 ,and is the transmit power and bandwidth of the ABS (110) for the link to the i-th UE, and The channel gain of the corresponding link can likewise be expressed as a function of the distance between the ABS (110) and the corresponding UE, various constants (path loss constant, etc.), the transmit antenna gain of the ABS (110), and the receive antenna gain of the corresponding 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 corresponding UE can be set to a fixed value in the optimization problem.

[0072] at last and It can be expressed as the decision variables of the optimization problem in mathematical equation 1.

[0073] In some embodiments, the optimization device determines the flight path, power allocation, and bandwidth allocation of the air base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the set requirements, and can determine beam parameters and the ratio of the resources based on the determined flight path, power allocation, and bandwidth allocation of the air base station. For example, Equation 1 is , , and This is because it can be restructured into an optimization problem with only one decision variable.

[0074] In some embodiments, the optimization device determines the beam parameters based on the determined flight path of the air base station, and the ratio of the resources ( ) can be determined.

[0075] For example, the optimization device has a ratio of the above resources ( ) can be calculated using mathematical formula 6.

[0076]

[0077] For example, if Equation 6 is applied to Equation 1, Equation 7 without the decision variable δ is obtained.

[0078]

[0079] In some embodiments, the optimization device can determine the flight path of the ABS and determine the beam direction and the beam width based on the determined flight path.

[0080] The optimization device can determine the optimal beam direction and optimal beam width by solving the smallest circle enclosing problem based on the determined flight path. As a method for solving the smallest circle problem, the technique presented in the paper by E. Welzl, "Smallest enclosing disks (balls and ellipsoids)," in New Results and New Trends in Computer Science, 1991, pp. 359-370, can be used.

[0081] Figure 3 is a conceptual diagram to explain the minimum circle problem.

[0082] In some embodiments, the optimization device may determine the beam direction and the beam width such that the transmission beam of the ABS covers all of the plurality of user devices simultaneously, while minimizing the circle formed by the transmission beam (the dotted circle shown in FIG. 3). That is, the optimization device, given About and To obtain this, the minimum circle problem, which is the problem of finding the smallest circle containing a finite set of points in a plane as exemplified in Fig. 3, can be used.

[0083] For example, the optimization device can determine the optimal beam direction and optimal beam width using mathematical formulas 8 and 9.

[0084]

[0085]

[0086] Here, the distance It is calculated in a spherical coordinate system.

[0087] Figure 4 illustrates an algorithm for determining the optimal beam direction and optimal beam width based on the minimum circle problem.

[0088] For example, the optimization device can determine the optimal beam direction and optimal beam width using Algorithm 1, which is exemplified in FIG. 4.

[0089] Algorithm 1 follows the structure of a recursive algorithm, as exemplified in Figure 4.

[0090] As a base case, the smallest circle can be easily found when the number of given points is three or less (line 3-6 of Algorithm 1).

[0091] In a recursive step, one point is randomly selected from the given points, and the smallest circle of the remaining points excluding the selected point is found (lines 8-9 of Algorithm 1).

[0092] If the selected point is outside the smallest circle found above, a recursive step is performed to find the smallest circle above (i.e., on the line of the circle) (lines 10-13 of Algorithm 1).

[0093] By performing the algorithm recursively in this way, a circle in which all given points are inside or on top can finally be provided (line 14 of Algorithm 1).

[0094] The circle obtained as a result is the given number of points, It is the smallest circle for.

[0095] In some embodiments, the obtained in this way If the range condition is not satisfied, it can be adjusted to satisfy it, and then finally determined as the optimal beam direction and beam width. For example, the obtained beam width This minimum beam width Ω min If it is smaller than, Ω min It can be finally decided as.

[0096] In the optimization problem of mathematical formula 7 and Ω, respectively, of Equation 8 and mathematical formula 9's If replaced, the optimization problem of mathematical equation 7 is given It can be reconstructed into mathematical formula 10.

[0097]

[0098] Here For the sake of simplifying the explanation, I intend to express it on behalf of.

[0099] The objective function (10a) of Equation 10 is a concave function, and the 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 standard algorithms for convex optimization problems. Below, the solution to the optimization problem of Equation 10 is I intend to express it as.

[0100] As described above, given The optimal solution to the optimization problem of mathematical formula 1 for , Ω, b, p, and ) can be obtained. That is, the given The optimization problem of Equation 1 for can be expressed as the optimization problem of Equation 11.

[0101]

[0102] In the following, given The optimal target value of the problem (11) for Expressed as, and the optimal solutions I intend to express it as.

[0103] Figure 5 illustrates an algorithm for finding the optimal solution and optimal target value of the problem in Equation 11.

[0104] The optimization device is expressed by mathematical equation 6 Substitute into Equation 1 to derive Equation 7 (Line 1 of Algorithm 2).

[0105] The optimization device uses Algorithm 1 (e.g., Algorithm 1 exemplified in FIG. 4) Calculate (Line 2 of Algorithm 2).

[0106] The optimization device is obtained Substitute into Equation 7 to construct the optimization problem of Equation 10 (Line 3 of Algorithm 2).

[0107] The optimizer solves the optimization problem of mathematical equation 10. , Calculate (line 4 of the algorithm)

[0108] The optimizer uses mathematical formula 6 Find .

[0109] The only remaining task to solve the problem in mathematical equation 1 is The goal is to obtain the optimal solution for. To achieve this, the following optimization problem must be solved.

[0110]

[0111] In some embodiments, the optimization device can obtain a solution to the problem of Equation 12 by applying a particle swarm optimization (PSO) algorithm. Is This is because it is difficult to express it in a closed form, making it difficult to solve the problem of Equation 12 analytically. A detailed description of the PSO algorithm itself is provided in the papers J. Kennedy and R. Eberhart, "Particle swarm optimization," in Proc. Int. Conf. Neural Netw. (ICNN'95), 1995, pp. 1942-1948, and R. Poli, J. Kennedy, and T. Blackwell, "Particle swarm optimization," Swarm Intell., vol. 1, no. 1, pp. 33-57, Aug. 2007.

[0112] Figure 6 illustrates an algorithm for finding the optimal solution by applying the PSO algorithm.

[0113] In Algorithm 3 represents the position of the i-th particle in the t-th iteration. represents the updated difference in the position of the i-th particle.

[0114] is the best position of the i-th particle up to the t-th iteration, and is the best position among all particles up to the t-th iteration.

[0115] In some embodiments, the optimization device may obtain the optimal target value of the optimization problem for a given flight path, determine the flight path of the air base station based on the obtained optimal target value (up to line 21 of Algorithm 3), and then determine the beam parameters and resource allocation of the air base station based on the determined flight path (line 22 of Algorithm 3).

[0116] In some embodiments, the optimization device may obtain the optimal target value based on a particle swarm optimization (PSO) algorithm and determine the flight path.

[0117] In some embodiments, the optimization device may determine the beam parameters based on the flight path of the determined air base station and determine the resource allocation based on the determined beam parameters.

[0118] In some embodiments, the optimization device may determine the transmission power allocation and the bandwidth allocation in determining the resource allocation, and determine the ratio of the resources based on the determined flight path, beam parameters, transmission power allocation and bandwidth allocation.

[0119] Referring to Fig. 6, the initial position of each particle is set through lines 1-6, and the set initial position Based on, using Algorithm 2 Find the best position is the set initial position Updated to, It is initialized randomly within the available set.

[0120] Through lines 7-8, the previously obtained P The largest value among them Set to.

[0121] Next, repeat lines 11-20 while increasing the iteration index t until a given termination condition is satisfied. The termination condition may include 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.

[0122] With the equation of line 13 is updated, and the updated Is It is used to determine the next position of each particle in line 14.

[0123] After convergence is selected as the optimal position value, and the optimal solution is obtained using Algorithm 2 on line 22 It is used to find .

[0124] Through Algorithm 3, we can obtain an approximate optimal solution to the problem of Equation 12, which allows us to approximate the original problem of Equation 1.

[0125] FIG. 7 is a block diagram illustrating an electronic device for performing a method according to embodiments of the present disclosure. Although FIG. 7 describes the electronic device (700) as a single physical device, according to the embodiment, the electronic device (700) may be implemented in a form in which a plurality of devices are interconnected (e.g., distributed computing).

[0126] 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, it may further include an input / output interface (740) and all or some of 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.

[0127] Memory (710) is a recording medium readable by an electronic device (e.g., a computer) and may include a non-perishable mass storage device such as RAM (random access memory), ROM (read only memory), and a disk drive. Here, the ROM and the non-perishable mass storage device may be included as separate permanent storage devices separated from the memory (710). Additionally, the memory (710) may store an operating system and at least one program code (e.g., a program such as a computer program for controlling the electronic device (700) by storing it in a recording medium included by the electronic device (700) to perform the method according to the 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). Such a separate recording medium readable by an electronic device may include a recording medium readable by an electronic device such as a floppy drive, disk, tape, DVD / CD-ROM drive, or memory card. In another embodiment, software components may be loaded into memory (710) via a communication module (730) rather than a recording medium readable by the electronic device.

[0128] 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 memory (710) or a communication module (730). For example, the processor (720) may be configured to execute instructions received according to program code loaded in memory (710). As a more specific example, the processor (720) may sequentially execute instructions according to the code of a computer program loaded in memory (710) to perform processing related to an unmanned aerial vehicle support network according to an embodiment of the present disclosure (e.g., optimization of flight paths, beam parameters, and resource allocation of airborne base stations). 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 embodiment of the present disclosure may be performed in such a way that the processor (720) of the electronic device (700) performs part of the process of the present embodiment, and another physical device of the communication network (e.g., an electronic device such as another computer not shown) performs the remaining process, and the processing results are exchanged through the communication network and the communication module (730).

[0129] The input / output interface (740) may be a means for interfacing with an input / output device (750). For example, the input device (750) may include a device such as a keyboard or mouse, and the output device may include a device such as a display or speaker. In FIG. 7, the input / output device (750) is depicted as a separate device from the electronic device (700), but according to the embodiment, the electronic device (700) may be implemented such that the input / output device (750) is included in the electronic device (700).

[0130] The device described above may be implemented as a hardware component, a software component, and / or a combination of a hardware component and a software component. For example, the device and components described in the embodiments may be implemented using one or more general-purpose 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 and responding to instructions. The electronic device (700) may execute an operating system (OS) and one or more software applications executed on said operating system. Additionally, the electronic device (700) may access, store, manipulate, process, and generate data in response to the execution of the software. For ease of understanding, the electronic device (700) may be described as being used as a single one, but a person of ordinary skill in the art will know that the electronic device (700) may include a plurality of processing elements and / or a plurality of 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 a parallel processor, are also possible.

[0131] 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 command the electronic device (700) independently or collectively. Software and / or data may be embodied in any type of machine, component, physical device, computer storage medium, or device to be interpreted by the electronic device (700) or to provide instructions or data to the electronic device (700). Software may be distributed over a networked computer system and stored or executed in a distributed manner. Software and data may be stored on one or more computer-readable recording media.

[0132] The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. In this case, the medium may continuously store a program executable by a computer, or temporarily store it for execution or download. Additionally, the medium may be various recording or storage means in the form of a single or several hardware combined, and is not limited to a medium directly connected to a computer system, but may also exist distributed over a network. Examples of media 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 media configured to store program instructions, including ROM, RAM, and flash memory. Additionally, other examples of media may include recording or storage media managed by app stores that distribute applications or sites and servers that supply or distribute various other software.

[0133] Although the embodiments have been described above with reference to limited examples and drawings, those skilled in the art can make various modifications and variations from the description above. For example, suitable results can be achieved even if the described techniques are performed in a different order than described, and / or the components of the described system, structure, device, circuit, etc. are combined or assembled in a form different from described, or replaced or substituted by other components or equivalents.

[0134] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims set forth below.

Claims

Claim 1 A method for an electronic device to determine a flight path, beam parameters, and resource allocation of an air base station in a system comprising a ground base station, an air base station, and a plurality of user devices receiving data from the ground base station through relay of the air base station, comprising: a step of setting a requirement—including a minimum required data transmission rate condition for each user device—and a step of determining a flight path, beam parameters, and resource allocation of the air base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the set requirement, wherein the resource subject to resource allocation includes the ratio of resources used by the link between the ground base station and the air base station (hereinafter, backhaul link) and the link between the air base station and the plurality of user devices (hereinafter, connection link). Claim 2 A method according to claim 1, wherein the resource subject to the resource allocation further comprises at least one of: transmission power allocated when the air base station transmits data to the plurality of user devices; and bandwidth allocated when the air base station transmits data to the plurality of user devices. Claim 3 In claim 1, the system operates based on a plurality of time slots, each of the plurality of time slots includes a time subslot for a backhaul link and a time subslot for a connection link, the ground base station transmits data to the air base station using the time subslot for a backhaul link included in each of the plurality of time slots, the air base station transmits data to the plurality of user devices using the time subslot for a connection link included in each of the plurality of time slots, and the ratio of the resources is the ratio that the time subslot for a connection link occupies in the time slots. Claim 4 A method according to claim 1, wherein the beam parameters include at least one of the transmission beam direction and transmission beam width of the airborne base station. Claim 5 A method according to claim 1, wherein the flight path includes the locations of airborne base stations during the relay, and the requirement further includes the minimum height and maximum height that the locations may have. Claim 6 In claim 1, the above requirement further includes a minimum beam width supported by the above air base station. Claim 7 In paragraph 1, the setting step and the determining step are as follows: (Here, and represents the received data transmission rate and the 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 airborne base station. and represents the bandwidth and transmission power allocated to transmission to the i-th user device, respectively. is the azimuth and elevation angle It indicates the beam direction expressed as. and represents the beam width and minimum beam width of the above-mentioned airborne base station, respectively. B max represents the maximum bandwidth of the above system, and P max represents the maximum transmission power of the above-mentioned airborne base station. and Each represents the height among the locations of the above-mentioned airborne base stations, the minimum height and maximum height at which they can be located during the relay service period. N ... indicates the number of the above multiple user devices. δ A method performed based on an optimization problem expressed as (representing the ratio of the connection link subslot to the time slot composed of a backhaul link subslot and a connection link subslot). Claim 8 The method of claim 1, wherein the resource subject to the resource allocation further comprises: transmission power allocated when the air base station transmits data to the plurality of user devices; and bandwidth allocated when the air base station transmits data to the plurality of user devices, and the determining step comprises: determining the flight path, power allocation, and bandwidth allocation of the air base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the set requirements; and determining beam parameters and the ratio of the resources based on the determined flight path, power allocation, and bandwidth allocation of the air base station. Claim 9 A method according to claim 8, wherein the step of determining the ratio of the beam parameters and the resources comprises: the step of determining the beam parameters based on the flight path of the determined air base station; and the step of determining the ratio of the resources based on the flight path, power allocation, bandwidth allocation, and beam parameters of the determined air base station. Claim 10 A method for an electronic device to determine a flight path, beam parameters, and resource allocation of an air base station in a system comprising a ground base station, an air base station, and a plurality of user devices receiving data from the ground base station through relay of the air base station, the method comprising: a step of setting a requirement—including a minimum required data transmission rate condition for each user device—and a step of determining a flight path, beam parameters, and resource allocation of the air base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the set requirement, wherein the beam parameters include a transmission beam direction and a transmission beam width of the air base station, and the determining step comprises a step of determining a flight path of the air base station; and a step of determining the beam direction and the beam width based on the determined flight path. Claim 11 In claim 10, the step of determining the beam direction and the beam width comprises the step of determining the beam direction and the beam width such that the transmitting beam of the air base station simultaneously covers all of the plurality of user devices, while minimizing the circle formed by the transmitting beam. Claim 12 In claim 10, the determining step comprises: obtaining an optimal target value for an optimization problem regarding a given flight path, beam parameters, and resource allocation of the air base station to maximize the sum of the received data transmission rates of the plurality of user devices while satisfying the set requirements; determining the flight path of the air base station based on the obtained optimal target value; and determining the beam parameters and resource allocation of the air base station based on the determined flight path. Claim 13 In claim 12, the step of obtaining the optimal target value and the step of determining the flight path are performed based on a particle swarm optimization (PSO) algorithm. Claim 14 In claim 12, the step of determining the beam parameters and resource allocation of the above-determined air base station comprises: the step of determining the beam parameters based on the flight path of the above-determined air base station; and the step of determining the resource allocation based on the determined beam parameters. Claim 15 In claim 14, the resources subject to the resource allocation include: transmission power allocated when the air base station transmits data to the plurality of user devices; bandwidth allocated when the air base station transmits data to the plurality of user devices; and the ratio of resources used by the backhaul link and the access link, and the step of determining the resource allocation includes: 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. Claim 16 In paragraph 10, the electronic device is the airborne base station, and the method further comprises the step of performing relay based on the determined flight path, beam parameters, and resource allocation. Claim 17 In claim 10, the electronic device is a device physically separated from the airborne base station, and the method further comprises the step of providing information regarding the determined flight path, beam parameters, and resource allocation to the airborne base station. Claim 18 An electronic device for determining a flight path, beam parameters, and resource allocation of an air base station in a system comprising a ground base station, an air base station, and a plurality of user devices receiving data from the ground base station through relay of the air base station, the electronic device comprising: a processor; and a computer-readable storage medium comprising instructions, wherein the instructions cause the electronic device to perform the method described in claim 10 in response to execution by the processor.

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