An efficient data transmission method based on a drone swarm

Abstract

The application relates to an efficient data transmission method based on a UAV group, and belongs to the technical field of mobile communication. Due to the advantages of strong mobility, flexible deployment and line-of-sight link of unmanned aerial vehicles (UAVs), the UAVs are increasingly widely applied in the field of wireless communication. The UAV relay can effectively expand the communication range, improve the system capacity and improve the reliability of the communication system. The application provides an efficient data transmission method based on a UAV group, wherein a plurality of UAVs serve as relays to assist information exchange between multiple pairs of ground users. First, a UAV relay communication network scene including a UAV, a source device and a destination device is constructed, and a data transmission model of the source device and the UAV is established in each time slot. Second, an optimization model maximizing the minimum link average throughput of the system is constructed. Finally, the optimization problem is decoupled into three sub-problems of user scheduling, UAV flight trajectory and transmission power based on the block coordinate descent method, and the three sub-problems are solved through an alternating iteration algorithm.

Description

Technical Field

[0001] This invention belongs to the field of mobile communication technology and relates to an efficient data transmission method based on unmanned aerial vehicle (UAV) swarms. Background Technology

[0002] Traditional terrestrial communication systems primarily rely on ground-based communication infrastructure, such as base stations. However, drone-based airborne communication offers lower costs and other significant advantages. First, drones are highly maneuverable, making the deployment of drone-assisted communication systems faster and more flexible, suitable for specific scenarios or emergencies. Second, compared to ground-to-ground communication links in terrestrial systems, drone-to-ground communication links are more likely to be line-of-sight links, thus providing greater communication channel capacity.

[0003] In wireless communication, relay technology is an effective way to improve throughput and reliability while extending communication range. However, due to practical constraints such as limited backhaul links, most existing relay systems are deployed in fixed locations. Compared to traditional static relays, drones, as mobile relay technology, have the ability to adaptively adjust their flight paths to obtain better channel conditions. By utilizing the degrees of freedom of drone movement, end-to-end throughput can be significantly improved, and communication coverage and channel capacity can be increased. However, current research on drone relay communication systems mostly considers only a single data link, i.e., the case from a source to a destination user. However, in some information-intensive areas, a single data link is no longer sufficient to meet the high information volume requirements. Furthermore, in scenarios involving IoT devices, real-time data collection becomes crucial, requiring data to be extracted before it loses value or is overwritten by new data. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide an efficient data transmission method based on UAV swarms, which jointly optimizes UAV trajectories, communication resource allocation, and communication scheduling to maximize the minimum average throughput of the system links.

[0005] To achieve the above objectives, the present invention provides the following technical solution: An efficient data transmission method based on UAV swarms, comprising the following steps: S101: Construct a drone relay communication network scenario that includes drones, source devices, and destination devices; S102: Set the total working time and number of communication time slots for the UAV, and establish the data transmission model of the source device and the UAV in each time slot; S103: Calculate the information transmission rate of each drone and the source device in each time slot using the data transmission model of the source device and the drone. S104: Calculate the value for each source-destination pair in...N The average information transmission rate of each time slot is used to construct an optimization problem; S105: Combines UAV trajectory, transmission power, and communication scheduling to maximize the average throughput of the minimum link in the system.

[0006] Furthermore, in S101, a model for relaying multiple source-destination pairs in a drone swarm is established. This model is composed of... M UAV and K The set of UAVs consists of several source-destination pairs. The set of source devices is The set of target devices is UAVs act as relays to support K Each ground source node communicates simultaneously with its respective ground destination node. Assuming that each source-destination pair cannot communicate directly, or that the distance between two nodes is too large and there are obstacles blocking normal communication, the UAV is equipped with a full-duplex cable that can be used for both data transmission and reception.

[0007] The source device can only upload data within a given timeframe; this data carries valid information, and information becomes invalid after the given timeframe. For example, during natural disasters, it is necessary to collect specific and important data in a timely manner to conduct a systematic evaluation of the current situation in a particular area. UAVs must be equipped with... k Deadline Previously, its information was transmitted. Assume the device's location, its corresponding data size, and the data generation time. and data transmission deadline Known.

[0008] Furthermore, in S102, the duration of one flight cycle of the UAV is set to... T Seconds, representing time T Divided into N There are 1 time slot, and the length of each time slot is 1. Seconds, that is For seconds, each UAV is approximately stationary within each time slot. Let... and They represent the first k For the three-dimensional Cartesian coordinates of the source and destination devices, where , UAV m Position used express, .

[0009] v max This represents the maximum speed of the UAV, and the maximum distance the UAV can travel in one time slot is equal to... V v max d t Define q 0,m and q f,m They represent UAV m The initial and final positions, then , .

[0010] Let the wireless channels from the source device to the UAV and from the UAV to the destination device be LoS channels. Therefore, in the time slots... n From the source device k To UAV m Channel power gain and from UAV m To the destination device k The channel power gains are expressed as follows: (1) (2) in, Indicates source device k To UAV m distance, UAV m To the destination device k The distance.

[0011] Furthermore, in S103, the transmission bandwidth of each UAV is set to be... B Different UAVs use different frequency bands. This is the self-interference cancellation coefficient. (In the time slot) n Source device k To UAV m uplink transmission rate and UAV m To the destination device k downlink transmission rate They are represented as follows: (3) (4) Furthermore, in S104, the first k For source-destination pairs N The average throughput of each time slot is defined as: (5) The optimization objective of this invention is to maximize the average throughput of the minimum source-destination device pair, i.e. Simultaneously, jointly optimize UAV trajectory Q and user scheduling. And the transmit power P of the UAV and the source device.

[0012] Furthermore, in S105, the optimization problem is decomposed into three sub-problems using the block coordinate descent method, and then solved through alternating iterative optimization.

[0013] The beneficial effects of this invention are as follows: To ensure the real-time and reliable transmission of information in information hotspots, the UAV relay system needs to deploy multiple parallel data links. In this way, multiple information sources can simultaneously transmit information to multiple destination users through multiple UAV relays. Furthermore, to address the timeliness issue of data uploads from IoT devices, by optimizing UAV trajectories and power resource allocation, the UAV swarm can transmit as much data as possible, thereby improving the system's throughput.

[0014] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0015] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 System model diagram; Figure 2 This is a flowchart of an efficient data transmission method based on drone swarms. Detailed Implementation

[0016] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0017] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0018] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0019] See Figure 1 and Figure 2 An efficient data transmission method based on UAV swarms includes the following steps: S101: Construct a drone relay communication network scenario that includes drones, source devices, and destination devices; The scene contains M UAV and K Source-destination pairs. UAVs act as relays to support... K Each ground source node communicates simultaneously with its respective ground destination node. The UAV is equipped with a full-duplex cable, which can be used for both data transmission and reception.

[0020] S102: In the UAV relay communication network scenario, establish the source device and UAV data transmission model for each time slot; T This indicates the flight duration of the UAV. For ease of trajectory optimization, the flight time is... T Discretized N There are three equal time slots. The length of each time slot is sufficiently small. d t = T / N Within each time slot, each UAV is approximately stationary. Let the wireless channels from the source device to the UAV and from the UAV to the destination device be called the LoS channels. n Time slot, from source device k To UAV m Channel power gain and from UAV m To the destination k Channel power gain They are represented as: (6) (7) in The channel gain is given at a reference distance of 1m. Indicates source devicek To UAV m distance, UAV m To the destination device k The distances are expressed as follows: (8) (9) S103: Calculate the information transmission rate of each drone and the source device in each time slot using the data transmission model of the source device and the drone. In a full-duplex network, the self-interference signal is related to the transmit power of the full-duplex node. Let... This represents the self-interference cancellation coefficient. (Source device) k To UAV m uplink transmission rate and UAV m Arrive at the destination k The downlink transmission rates are as follows: (10) (11) in In time slot n Source device k To UAV m The transmission power, In time slot n UAV m To the destination device k The transmission power, This represents noise power.

[0021] S104: Calculate the value for each source-destination pair in N Average transmission rate per time slot; No. k For source-destination pairs N Average transmission rate per time slot Defined as: (12) Among them, the full-duplex binary indicator variable Indicates in time slot n Source-destination pairs and UAVs m Matching, i.e., in time slots n source k Upload data to UAV m And UAV m Also transmit data to the destination k .

[0022] S105: Construct an optimization model that maximizes the minimum average throughput of the system links and satisfies the various constraints. (1) Minimum and maximum height constraints Due to the influence of terrain, building avoidance, and government regulations, UAVs k The height is at [ h min , h max Within the range, h min and h max Minimum and maximum permissible flight altitudes for UAVs: (13) (2) Initial and final position constraints When a UAV takes off and lands at a given location, its initial and final positions can be represented as: (14) Where, q 0,m and q f,m They represent UAV m The initial and final positions.

[0023] (3) Maximum and minimum speed constraints of UAV The speed of a UAV during flight must meet the following constraints: (15) The maximum distance a UAV can fly within a time slot. V v max d t , v max This indicates the maximum speed of the UAV.

[0024] (4) Collision avoidance constraints To ensure safety, UAVs need to maintain a certain distance from other drones during flight. The trajectory of the UAV needs to satisfy the following constraints: (16) In the formula d min This represents the minimum allowable distance between any two UAVs in any time slot.

[0025] (5) User scheduling constraints In any given time slot, a UAV matches at most one source-destination pair, and a source-destination pair matches at most one UAV, for full-duplex binary indicator variables. The following constraints apply: (17) (18) (6) Transmit power constraint Time slot n Source device k To UAV m Transmission power UAV m To the destination device k Transmission power Subject to the following average and maximum values: (19) (20) (7) Information validity constraints UAVs must be present on each device. k Relay its information within the validity period, source k To UAV m Data transmission needs Between, source devices k The following transmit power constraints apply: (twenty one) (8) Information causality constraint Source device k in front n Send one time slot to UAV m The data should be greater than or equal to UAV. m Send to destination k Given the amount of data, assuming the data processing delay of the UAV relay is one time slot, the following constraints apply: (twenty two) S106: Maximize the minimum average throughput of the system links by combining UAV trajectory, communication resources, and communication scheduling; The joint optimization model expression for UAV trajectory, communication scheduling, and transmission power is as follows. This relay system includes multiple pairs of users.

[0026] Optimization variables are M The trajectory of a UAV , M UAV and K Transmission power of individual source devices binary indicator variables The goal is to maximize the minimum source-destination ratio for average throughput. ,make The problem is transformed into The optimization problem can then be modeled as: (twenty three) This optimization problem is a 0-1 integer non-convex optimization problem.

[0027] S107: The block coordinate descent method and successive convex approximation technique are used to solve the UAV trajectory, transmission power and communication scheduling.

[0028] The core idea of ​​the Block Coordinate Descent Method (BCD) is to alternately update different variable blocks. The original optimization problem is decomposed into three subproblems, and by alternately solving these three subproblems, a local optimum of the original optimization problem can be found.

[0029] Subproblem 1: Relax the binary variable A into a continuous form, and constrain it. Can be written as Given a fixed trajectory Q and transmit power P for the UAV, the user scheduling subproblem can be expressed as: (twenty four) Problem P2 is a linear programming problem, and the optimal solution can be obtained through convex optimization techniques.

[0030] Subproblem 2: Based on the results of subproblem 1, with the transmit power P of the UAV and the source device fixed, the trajectory optimization subproblem can be expressed as: (25) Subproblem 3: Based on the results of subproblems 1 and 2, the power optimization subproblem can be expressed as: (26) Since subproblems 2 and 3 are non-convex optimization problems, the successive convex approximation (SCA) method is used to solve them.

[0031] Furthermore, a block coordinate iterative algorithm is used to solve the three sub-problems iteratively until the iteration error is less than the threshold value.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for efficient data transmission based on unmanned aerial vehicle (UAV) swarms, characterized in that: The method includes the following steps: S101: Construct a drone relay communication network scenario that includes drones, source devices, and destination devices; In S101, a model for relaying multiple source-destination pairs by a drone swarm is established. This model is composed of... M UAV and K The set of UAVs consists of several source-destination pairs. The set of source devices is The set of target devices is UAVs act as relays to support K Each ground source node communicates simultaneously with its respective ground destination node. Assuming that each source-destination pair cannot communicate directly, and that the distance between two nodes is too large and there are obstacles blocking the communication, the UAV is equipped with a full-duplex cable for both data transmission and reception. The source device can only upload data within a given period, and the data it carries is considered valid information. Data uploaded after the given period is invalid. S102: Set the total working time and number of communication time slots for the UAV, and establish the data transmission model of the source device and the UAV in each time slot; In S102, the duration of one flight cycle of the UAV is set to... T Seconds, representing time T Divided into N There are 1 time slot, and the length of each time slot is 1. Seconds, that is Seconds, within each time slot, each UAV is approximately stationary; let and They represent the first k For the three-dimensional Cartesian coordinates of the source and destination devices, where , UAV m Position used express, ; v max This represents the maximum speed of the UAV, and the maximum distance the UAV can travel in one time slot is equal to... V v max d t Define q 0,m and q f,m They represent UAV m The initial and final positions, then , ; Let the wireless channels from the source device to the UAV and from the UAV to the destination device be the LoS channels; in the time slots n From the source device k To UAV m Channel power gain and from UAV m To the destination device k The channel power gains are expressed as follows: (1) (2) in, This represents the channel gain at a reference distance of 1m. S103: Calculate the information transmission rate of each drone and the source device in each time slot using the data transmission model of the source device and the drone. In S103, the transmission bandwidth of each UAV is assumed to be... B Different UAVs use different frequency bands; This is the self-interference cancellation coefficient; in the time slot n Source device k To UAV m uplink transmission rate and UAV m To the destination device k downlink transmission rate They are represented as follows: (3) (4) in, This represents the transmit power from source device k to UAV m in time slot n; Indicates noise power; This represents the channel gain at a reference distance of 1m. This represents the transmission power of UAV m to destination device k in time slot n; S104: Calculate the value for each source-destination pair in... N The average information transmission rate of each time slot is used to construct an optimization problem; In S104, the first k For source-destination pairs N The average throughput of each time slot is defined as: (5) The optimization objective is to maximize the average throughput of the minimum source-destination device pair, i.e. Simultaneously, jointly optimize UAV trajectory Q and user scheduling. And the transmit power P of the UAV and the source device; Full-duplex binary indicator variable Indicates in time slot n Source-destination pairs and UAVs m Matching, i.e., in time slots n source k Upload data to UAV m And UAV m Also transmit data to the destination k ; Optimization variables are M The trajectory of a UAV , M UAV and K Transmission power of individual source devices binary indicator variables ; S105: Combining UAV trajectory, transmit power, and communication scheduling to maximize the system's minimum link average throughput; In S105, the optimization problem is decomposed into three sub-problems using the block coordinate descent method, and then solved by iterative optimization.

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