UAV-Based Air-to-Ground Hybrid Communication Method, Apparatus, and Communication System

Abstract

The present invention discloses a method, apparatus and communication system for air-to-ground hybrid communication based on UAVs. The method includes: for a scenario containing multiple UAVs and UEs, designing a hybrid communication architecture and establishing a channel model; in the hybrid communication architecture, each time slot is divided into an uplink and a downlink transmission phase based on TDD technology, and the transmission duration is divided according to the uplink-downlink ratio; based on FDMA technology, the total system frequency bandwidth within each time slot is divided into sub-frequency bandwidths for each UE according to a division ratio of multiple sub-bandwidths matching the number of UEs; based on the hybrid communication architecture and the channel model, calculating the uplink and downlink data transmission rates between the UAVs and UEs within each time slot as the communication rate calculation result; determining a communication decision based on the communication rate calculation result between the UAVs and UEs within each time slot, so as to realize air-to-ground communication between the UAVs and UEs. The present invention can improve the communication performance and efficiency of UAVs by configuring the uplink-downlink ratio division and the sub-bandwidth division ratio.

Description

Technical Field

[0001] The present invention belongs to the technical fields of network communication and signal processing, and particularly relates to an air-to-ground hybrid communication method, device, and communication system based on UAVs. Background Art

[0002] With the continuous exploitation of the earth's resources, the ecological balance has been seriously damaged, leading to a significant increase in sudden natural disasters. In post-disaster rescue, the collection and real-time transmission of information are the key to the rescue process. Natural disasters such as earthquakes, heavy rains, and strong winds will damage the communication network in the affected areas and hinder the timely transmission of information to the outside world. In this case, unmanned aerial vehicles (UAVs) equipped with airborne communication base station systems can integrate aerial networking and image transmission technologies to achieve vertical and horizontal interconnection of images, voices, and data. Compared with traditional emergency rescue, UAVs (Unmanned Aerial Vehicle) can get rid of the limitations of optical cables and electricity in the original infrastructure and achieve rapid deployment of emergency communication. Due to the large number of ground nodes and limited spectrum resources, it is difficult to achieve communication coverage while ensuring communication quality, which requires continuous optimization of relevant parameters through advanced algorithms.

[0003] In the prior art, Gui Jinsong et al. proposed a millimeter-wave heterogeneous cellular network with wireless self-backhaul in the patent "Gui Jinsong, Chen Can, Deng Xiaoheng. Communication method for self-backhaul millimeter-wave cellular network based on dynamic time-division duplex communication [P]. Hunan Province: CN202310462350.9, 2024-02-02.", which includes a macrocell and N small cells. In the target network, the macro base station, small base stations, and user equipment are all equipped with wireless interfaces in the millimeter-wave band and sub-6GHz band, respectively, for data transmission and control information exchange. The communication frame ratio is configured in the time-division long-term evolution scheme to meet the uplink and downlink communication requirements; the in-band transmission mode is adopted for transmission, and the access link and the backhaul link share the same spectrum resource.

[0004] However, in the above solution, only the communication frame ratio is configured to meet the uplink and downlink communication requirements, but the same spectrum resource is shared, and the spectrum resource is not optimized, which will lead to spectrum resource waste and signal interference problems. Summary of the Invention

[0005] To solve the above problems existing in the prior art, the present invention provides an air-to-ground hybrid communication method, device, and communication system based on UAVs. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides an air-to-ground hybrid communication method based on UAVs, and the method includes:

[0007] For a scenario containing multiple Unmanned Aerial Vehicles (UAVs) and User Equipment (UEs), a hybrid communication architecture is designed, and a channel model between the UAVs and UEs is established. In the hybrid communication architecture, each time slot is divided into an uplink and a downlink transmission phase based on Time Division Duplex (TDD) technology, and the transmission duration is divided according to the uplink-downlink ratio. Based on Frequency Division Multiple Access (FDMA) technology, the total system frequency bandwidth within each time slot is divided into sub-frequency bandwidths for each UE according to a division ratio matching the number of UEs.

[0008] Based on the hybrid communication architecture and the channel model, calculate the uplink data transmission rate and the downlink data transmission rate between the UAVs and UEs within each time slot, as the communication rate calculation result for the corresponding time slot.

[0009] Within each time slot, based on the communication rate calculation result between the UAVs and UEs, determine the communication decision between the UAVs and UEs to characterize whether a communication connection is established, and achieve the air-to-ground communication between the UAVs and UEs in the scenario through the communication decision.

[0010] In an embodiment of the present invention, in the scenario, J UAVs are deployed above the ground, denoted as I UEs are deployed on the ground, denoted as

[0011] For the scenario, the designed hybrid communication architecture includes:

[0012] The communication cycle of the UAVs in the scenario is divided into T equal time periods, denoted as Each time period is a time slot, represented by the duration τ, and τ is small enough. Each time slot t is divided into an uplink and a downlink transmission phase based on TDD technology. The transmission durations of the uplink transmission phase and the downlink transmission phase are divided according to the uplink-downlink ratio k, where the value of k ranges between 0 and 1. kτ represents the transmission duration of the uplink transmission phase in a time slot, and (1 - k)τ represents the transmission duration of the downlink transmission phase in the same time slot. Within each time slot t, the total system frequency bandwidth is divided into sub-frequency bandwidths for each of the I UEs according to I sub-bandwidth division ratios. Let w represent the size of the total system frequency bandwidth, and the sub-frequency bandwidths of the I UEs divided are denoted as a i is the sub-bandwidth division ratio for the i-th UE.

[0013] In an embodiment of the present invention, the channel model covers two types: line-of-sight and non-line-of-sight.

[0014] In an embodiment of the present invention, the process of establishing the channel model between the UAVs and UEs includes:

[0015] Determine the UAV in time slot t j and the UE iThe line-of-sight (LoS) connection probability and non-line-of-sight (NLoS) connection probability between them are respectively expressed as:

[0016]

[0017] where LoS and NLoS respectively represent line-of-sight and non-line-of-sight; UAV j represents the j-th UAV; UE i represents the i-th UE; represents the LoS connection probability between the UAV j and UE i in time slot t; represents the NLoS connection probability between the UAV j and UE i in time slot t; α and β are environmental constants; represents the elevation angle between the UAV j and UE i in time slot t;

[0018] Determine the average LoS path loss and average NLoS path loss between the UAV j and UE i in time slot t, which are respectively expressed as:

[0019]

[0020] where, and respectively represent the average LoS path loss and average NLoS path loss between the UAV j and UE i in time slot t; f represents the channel transmission frequency of the UAV j and UE i , with the unit of Hz; represents the distance between the UAV j and UE i in time slot t; c represents the speed of light; η LoS and η NLoS respectively represent the additional loss on the LoS path and the additional loss on the NLoS path;

[0021] According to the LoS connection probability and NLoS connection probability between the UAV j and UE i in time slot t, and the average LoS path loss and average NLoS path loss between the UAV j and UE i in time slot t, determine the average path loss between the UAV j and UE i in time slot t, which is expressed as:

[0022]

[0023] Among them, is the average path loss between the UAV j and the UE i in time slot t, which is used to characterize the channel state.

[0024] In an embodiment of the present invention, the formula for calculating the uplink data transmission rate between the UAV and the UE in each time slot is:

[0025]

[0026] The formula for calculating the downlink data transmission rate between the UAV and the UE in each time slot is:

[0027]

[0028] Among them, is the uplink data transmission rate of the UAV j and the UE i in time slot t; is the downlink data transmission rate of the UAV j and the UE i in time slot t; P ij represents the transmission power of the UE i to the UAV; represents the average path loss between the UAV j and the UE i in time slot t; P ji represents the transmission power of the UAV j and the UE i ; represents the average path loss between the UAV j and the UE i in time slot t, is equal to σ0 represents the power spectral density of additive white Gaussian noise at the receiving end.

[0029] In an embodiment of the present invention, the calculation formula for the communication decision is:

[0030]

[0031] Among them, represents the comprehensive data transmission rate between the UE i and the UAV j in time slot t, represents the uplink data transmission rate between the UE i and the UAV j ; represents the UE i and the UAVj The downlink data transmission rate; m represents the weight of the uplink rate, and n represents the weight of the downlink rate;

[0032] represents the communication decision of the UE in time slot t i of the communication decision, represents the UE i and the maximum value of the comprehensive data transmission rate of all UAVs, If represents the UE i and the UAV j establishes a communication link within the communication coverage; if represents the UE i and the UAV j does not establish a communication link and is not within the communication coverage.

[0033] In a second aspect, an embodiment of the present invention provides an air-to-ground hybrid communication device based on UAVs, and the device includes:

[0034] A hybrid communication architecture and channel model construction module, which is used to design a hybrid communication architecture for a scenario containing multiple unmanned aerial vehicles (UAVs) and user nodes (UEs), and establish a channel model between the UAVs and the UEs; wherein, in the hybrid communication architecture, each time slot is divided into an uplink and a downlink transmission stage based on the TDD technology, and the transmission duration is divided according to the uplink and downlink ratio; based on the FDMA technology, the total system frequency bandwidth within each time slot is divided into sub-frequency bandwidths of each UE according to a division ratio of multiple sub-bandwidths matching the number of UEs;

[0035] A communication rate calculation result acquisition module, which is used to calculate the uplink data transmission rate and the downlink data transmission rate between the UAVs and the UEs within each time slot based on the hybrid communication architecture and the channel model, as the communication rate calculation result of the corresponding time slot;

[0036] A communication decision calculation module, which is used to determine the communication decision between the UAVs and the UEs within each time slot based on the communication rate calculation result between the UAVs and the UEs to represent whether to establish a communication connection, and realize the air-to-ground communication between the UAVs and the UEs in the scenario through the communication decision.

[0037] In a third aspect, an embodiment of the present invention provides a communication system, including multiple unmanned aerial vehicles (UAVs) and user nodes (UEs), and the communication system realizes air-to-ground communication by using the air-to-ground hybrid communication method described in the first aspect.

[0038] The beneficial effects of the present invention:

[0039] In the solution provided by the embodiments of the present invention, a hybrid communication architecture is proposed based on TDD technology and FDMA technology. Among them, each time slot is divided into an uplink and a downlink transmission stage based on TDD technology, and the transmission duration is divided according to the uplink-downlink ratio; based on FDMA technology, the total system frequency bandwidth within each time slot is divided into sub-frequency bandwidths for each UE according to a division ratio of multiple sub-bandwidths matching the number of UEs. The present invention takes into account the parameter configurations in both the time domain and the frequency domain, which is more comprehensive than existing solutions. It can provide new ideas for optimization objectives such as the total system throughput and the number of UAV deployments in the future on the premise of achieving full coverage of ground nodes in the UAV network communication, and provides a new solution for the access of ground nodes in UAV-assisted communication. Description of the Drawings

[0040] Figure 1 It is a schematic flow chart of a UAV-based air-to-ground hybrid communication method provided by an embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of a scenario containing multiple unmanned aerial vehicles (UAVs) and user nodes (UEs) in an embodiment of the present invention;

[0042] Figure 3 It is a schematic structural diagram of a hybrid communication architecture provided by an embodiment of the present invention;

[0043] Figure 4 It is a schematic structural diagram of a UAV-based air-to-ground hybrid communication device provided by an embodiment of the present invention. Detailed Embodiments

[0044] The following further describes the present invention in detail with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0045] In order to optimize by simultaneously considering the influencing factors in the time domain and the frequency domain and achieve the purpose of optimizing communication performance, the embodiments of the present invention provide a UAV-based air-to-ground hybrid communication method and device, and further provide a communication system, which can be used in the field of social public safety, such as emergency communication, etc.

[0046] It should be noted that the execution subject of a UAV-based air-to-ground hybrid communication method provided by an embodiment of the present invention can be a UAV-based air-to-ground hybrid communication device, and the device can run in an electronic device. Among them, the electronic device can be a server of a backend control center, a cloud server, a UAV edge computing device, etc., but is not limited thereto.

[0047] In the first aspect, the embodiments of the present invention provide a UAV-based air-to-ground hybrid communication method, as Figure 1 shown, the method may include the following steps:

[0048] S1. For a scenario with multiple unmanned aerial vehicles (UAVs) and user nodes (UEs), design a hybrid communication architecture and establish a channel model between the UAVs and UEs. In the hybrid communication architecture, each time slot is divided into an uplink and a downlink transmission phase based on TDD technology, and the transmission duration is divided according to the uplink-downlink ratio. Based on FDMA technology, the total system frequency bandwidth within each time slot is divided into sub-frequency bandwidths for each UE according to a division ratio that matches the number of UEs.

[0049] Figure 2 It is a schematic diagram of a scenario with multiple UAVs and UEs. In this scenario, J UAVs are deployed above the ground, aiming to use the UAVs as aerial base stations to quickly restore communication. The J UAVs are denoted as I UEs are deployed on the ground. The UEs can be the communication devices of users in the disaster area. The I UEs are denoted as

[0050] For the designed hybrid communication architecture in this scenario, which is abbreviated as HybridComm, it is divided into two-layer framework. The upper layer uses TDD technology to achieve full-duplex communication, and the lower layer uses FDMA to achieve multi-access of multiple ground nodes. Please refer to the hybrid communication architecture Figure 3 Understand that it specifically includes:

[0051] The communication cycle of the UAVs in the scenario is divided into T equal time periods, denoted as Each time period is a time slot, represented by a duration τ, and τ is small enough.

[0052] For the implementation of the full-duplex communication function, each time slot t is divided into an uplink and a downlink transmission phase based on TDD technology. The transmission durations of the uplink and downlink transmission phases are divided according to the uplink-downlink ratio k, where the value of k ranges between 0 and 1. The specific value of k can be set as needed. It can be a fixed value determined in advance for a large amount of data, or a value that is continuously adjusted according to the communication time slot requirements. It is not limited here. kτ represents the transmission duration of the uplink transmission phase in a time slot, and (1 - k)τ represents the transmission duration of the downlink transmission phase in the same time slot.

[0053] For the implementation of the ground multi-node multi-access function, embodiments of the present invention achieve simultaneous communication of multiple users by dividing the available spectrum into multiple independent frequency channels. Each user is assigned a fixed frequency bandwidth and can continuously use it during a call, ensuring that signals between different users do not interfere with each other. FDMA supports parallel communication, allowing multiple users to transmit data simultaneously, and the same frequency can be reused in different geographical regions to improve spectrum utilization. Specifically, within each time slot t, the total system frequency bandwidth is divided into sub-frequency bandwidths of each UE according to the I sub-bandwidth division ratios; let w represent the size of the total system frequency bandwidth, and the sub-frequency bandwidths of the I UEs divided are expressed as a i is the sub-bandwidth division ratio of the i-th UE, and its value range is between 0 and 1. The sum of all sub-bandwidth division ratios is 1. Similarly, the specific values of these sub-bandwidth division ratios can also be set according to needs and are not limited here.

[0054] In embodiments of the present invention, a designed hybrid communication architecture is adopted, taking the uplink-downlink ratio and the sub-bandwidth division ratio as time-domain and frequency-domain influencing factors respectively and considering them simultaneously. Through the configuration of these two parameters, the performance and efficiency of UAV communication can be improved, providing new possibilities for the optimization of the space-ground integrated communication system.

[0055] In embodiments of the present invention, the corresponding communication system can be transmitted on the air-to-ground (A2G) channel in a relatively open area, with a limited number of buildings and vegetation. Therefore, the channel model covers two types: line-of-sight and non-line-of-sight.

[0056] In an optional implementation manner, the process of establishing a channel model between the UAV and the UE includes:

[0057] ① Determine the line-of-sight connection probability and non-line-of-sight connection probability between the UAV j and the UE i in the time slot t, which are respectively expressed as:

[0058]

[0059] where LoS and NLoS respectively represent line-of-sight and non-line-of-sight; UAV j represents the j-th UAV; UE i represents the i-th UE; represents the line-of-sight connection probability between the UAV j and the UE i in the time slot t, represents the non-line-of-sight connection probability between the UAV j and the UE i in the time slot t; α and β are environmental constants; represents the UAV in the time slot tj and the UE i the elevation angle between;

[0060] ② Determine the UAV in time slot t j and the UE i the average LoS path loss and the average NLoS path loss between, respectively expressed as:

[0061]

[0062] Wherein, and respectively represent the average LoS path loss and the average NLoS path loss between the UAV in time slot t j and the UE i ; f represents the channel transmission frequency of the UAV j and the UE i , in Hz; represents the distance between the UAV in time slot t j and the UE i ; c represents the speed of light; η LoS and η NLoS respectively represent the additional loss on the LoS path and the additional loss on the NLoS path;

[0063] ③ According to the line-of-sight connection probability and the non-line-of-sight connection probability between the UAV in time slot t j and the UE i , the average LoS path loss and the average NLoS path loss between the UAV in time slot t j and the UE i , determine the average path loss between the UAV in time slot t j and the UE i , expressed as:

[0064]

[0065] Wherein, is the average path loss between the UAV in time slot t j and the UE i , used to characterize the channel state.

[0066] S2. Based on the hybrid communication architecture and the channel model, calculate the uplink data transmission rate and the downlink data transmission rate between the UAV and the UE in each time slot, as the communication rate calculation result of the corresponding time slot;

[0067] Among them, the formula for calculating the uplink data transmission rate between the UAV and the UE in each time slot is:

[0068]

[0069] The formula for calculating the downlink data transmission rate between the UAV and the UE in each time slot is as follows:

[0070]

[0071] Among them, is the uplink data transmission rate of the UAV j and the UE i in time slot t; is the downlink data transmission rate of the UAV j and the UE i in time slot t; P ij represents the transmit power of the UE i to the UAV; represents the average path loss between the UAV j and the UE i in time slot t; P ji represents the transmit power of the UAV j and the UE i ; represents the average path loss between the UAV j and the UE i in time slot t, is equal to σ0 represents the power spectral density of the additive white Gaussian noise at the receiving end.

[0072] In each time slot, the uplink data transmission rate and the downlink data transmission rate between the UAV and the UE are used as the calculation results of the communication rate for the corresponding time slot.

[0073] S3. In each time slot, based on the calculation results of the communication rate between the UAV and the UE, determine the communication decision between the UAV and the UE to characterize whether to establish a communication connection, and implement the air-to-ground communication between the UAV and the UE in the scenario through the communication decision.

[0074] In the embodiment of the present invention, a communication link establishment rule is constructed by determining the communication decision between the UAV and the UE in each time slot.

[0075] Among them, the calculation formula of the communication decision is:

[0076]

[0077] Among them, represents the comprehensive data transmission rate of the UE i and the UAV j in time slot t, represents the uplink data transmission rate of the UE i and the UAV j in time slot t; represents the UE iWith the UAV j The downlink data transmission rate; m represents the weight of the uplink rate, and n represents the weight of the downlink rate; the value ranges of m and n are between 0 and 1, and the specific values of m and n can be adjusted according to the user's situation. For example, if the user considers the uplink more important, m>n can be configured.

[0078] Indicates the communication decision of the UE in time slot t i The communication decision, Indicates the UE i The maximum value of the comprehensive data transmission rate with all UAVs, that is If Indicates the UE i With the UAV j Establish a communication link within the communication coverage; if Indicates the UE i With the UAV j No communication link is established and it is not within the communication coverage.

[0079] Through the calculation of the above communication decision, it is possible to determine whether the UAV and the UE are connected or not in each time slot, so as to achieve air-to-ground communication.

[0080] In the solution provided by the embodiments of the present invention, a hybrid communication architecture is proposed based on TDD technology and FDMA technology. Among them, each time slot is divided into an uplink and a downlink transmission stage based on TDD technology, and the transmission duration is divided according to the uplink-downlink ratio; based on FDMA technology, the total system frequency bandwidth within each time slot is divided into sub-frequency bandwidths of each UE according to the division ratio of multiple sub-bandwidths matching the number of UEs; the present invention takes into account both time-domain and frequency-domain parameter configurations, which is more comprehensive than existing solutions, and can provide new ideas for optimization objectives such as the total system throughput and the number of UAV deployments in the future, and provide a new solution for the access of ground nodes in UAV-assisted communication.

[0081] In a second aspect, corresponding to the above method embodiments, the embodiments of the present invention also provide an air-to-ground hybrid communication device based on UAVs, as Figure 4 shown, the device includes:

[0082] Hybrid communication architecture and channel model construction module, which is used to design a hybrid communication architecture and establish a channel model between UAVs and UEs for a scenario containing multiple unmanned aerial vehicles (UAVs) and user nodes (UEs); in the hybrid communication architecture, each time slot is divided into an uplink and a downlink transmission phase based on TDD technology, and the transmission duration is divided according to the uplink-downlink ratio; based on FDMA technology, the total system frequency bandwidth within each time slot is divided into sub-frequency bandwidths for each UE according to a division ratio of multiple sub-bandwidths matching the number of UEs.

[0083] Communication rate calculation result acquisition module, which is used to calculate the uplink data transmission rate and the downlink data transmission rate between the UAV and the UE within each time slot based on the hybrid communication architecture and the channel model, as the communication rate calculation result for the corresponding time slot.

[0084] Communication decision calculation module, which is used to determine the communication decision between the UAV and the UE within each time slot based on the communication rate calculation result between the UAV and the UE to represent whether to establish a communication connection, and realize the air-to-ground communication between the UAV and the UE in the scenario through the communication decision.

[0085] For the specific processing procedures of each module of the device, please refer to the relevant content in the first aspect, and details are not described here.

[0086] In a third aspect, an embodiment of the present invention further provides a communication system, including multiple unmanned aerial vehicles (UAVs) and user nodes (UEs), and the communication system realizes air-to-ground communication by using the air-to-ground hybrid communication method described in the first aspect.

[0087] This system can be referred to Figure 2 For understanding, please refer to the relevant content in the first aspect for the specific communication method, and details are not described here.

[0088] It should be noted that in the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0089] Each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for the related parts, reference can be made to the corresponding description in the method embodiment.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are all included in the protection scope of the present invention.

Claims

1. An air-to-ground hybrid communication method, characterized in that, Including: Design a hybrid communication architecture for scenarios containing multiple unmanned aerial vehicles (UAVs) and user nodes (UEs), and establish a channel model between UAVs and UEs. Among them, the j-th UAV in the air above the ground is denoted as UAV j , The i-th UE on the ground is denoted as UE i , In the hybrid communication architecture, the communication period is divided into T equal time slots. The duration of time slot t is denoted by τ, and τ is small enough Each time slot is divided into an uplink and a downlink transmission phase based on time-division duplexing (TDD) technology. The transmission duration is divided according to the uplink-downlink ratio. Based on frequency-division multiple access (FDMA) technology, the total system frequency bandwidth within each time slot is divided into sub-frequency bandwidths for each UE according to a division ratio that matches the number of UEs Based on the hybrid communication architecture and the channel model, calculate the uplink data transmission rate and the downlink data transmission rate between the UAV and the UE in each time slot, as the communication rate calculation result for the corresponding time slot; In each time slot, based on the communication rate calculation result between the UAV and the UE, determine the communication decision between the UAV and the UE to characterize whether to establish a communication connection, and realize the air-to-ground communication between the UAV and the UE in the scenario through the communication decision; The calculation formula of the communication decision is: Among them, represents the comprehensive data transmission rate between the UE i and the UAV j in time slot t; represents the uplink data transmission rate between the UE i and the UAV j in time slot t; represents the downlink data transmission rate between the UE i and the UAV j in time slot t; m represents the weight of the uplink rate, and n represents the weight of the downlink rate; represents the maximum value among the comprehensive data transmission rates between the UE i and all UAVs in time slot t; Indicates the communication decision between the UAV j and the UE i in time slot t, indicates that the UE i establishes a communication connection with the UAV j ; indicates that the UE i does not establish a communication connection with the UAV j .

2. The air-to-ground hybrid communication method according to claim 1, wherein For the scenario, the designed hybrid communication architecture includes: Each time slot is divided into an uplink and a downlink transmission phase based on TDD technology. The transmission durations of the uplink and downlink transmission phases are divided according to the uplink-downlink ratio k, where the value of k ranges between 0 and 1; kτ represents the transmission duration of the uplink transmission phase in a time slot, and (1 - k)τ represents the transmission duration of the downlink transmission phase in the same time slot. Within each time slot, the total system frequency bandwidth is divided into sub-frequency bandwidths for each UE according to the I sub-bandwidth division ratios. Let w represent the magnitude of the total system frequency bandwidth, and the sub-frequency bandwidths of the I UEs divided are expressed as a i is the sub-bandwidth division ratio for the i-th UE.

3. The air-to-ground hybrid communication method according to claim 2, wherein The channel model covers two types: line-of-sight and non-line-of-sight.

4. The air-to-ground hybrid communication method according to claim 3, wherein The process of establishing a channel model between the UAV and the UE includes: Determine the line-of-sight connection probability and non-line-of-sight connection probability between the UAV j and the UE i in time slot t, which are respectively denoted as: where LoS and NLoS represent line-of-sight and non-line-of-sight, respectively; UAV j represents the j-th UAV; UE i represents the i-th UE; represents the probability of line-of-sight connection between the UAV j and the UE i in time slot t; represents the probability of non-line-of-sight connection between the UAV j and the UE i in time slot t; α and β are environmental constants; represents the elevation angle between the UAV j and the UE i in time slot t; Determine the UAV in time slot t j and the UE i The average LoS path loss and the average NLoS path loss between them are respectively expressed as: Among them, and respectively represent the average LoS path loss and the average NLoS path loss between the UAV j and the UE i in time slot t; f represents the channel transmission frequency of the UAV j and the UE i , with the unit of Hz; represents the distance between the UAV j and the UE i in time slot t; c represents the speed of light; η LoS and η NLoS respectively represent the additional loss on the LoS path and the additional loss on the NLoS path; According to the line-of-sight connection probability and non-line-of-sight connection probability between the UAV j and the UE i in time slot t, and the LoS average path loss and NLoS average path loss between the UAV j and the UE i in time slot t, determine the average path loss between the UAV j and the UE i in time slot t, expressed as: Among them, is the average path loss between the UAV j and the UE i in time slot t, which is used to characterize the channel state.

5. The air-to-ground hybrid communication method according to claim 4, characterized in that, The formula for calculating the uplink data transmission rate between the UAV and the UE in each time slot is: The formula for calculating the downlink data transmission rate between the UAV and the UE in each time slot is: wherein, is the uplink data transmission rate of the UAV j and the UE i in time slot t; is the downlink data transmission rate of the UAV j and the UE i in time slot t; P ij represents the transmit power of the UE i to the UAV; represents the average path loss between the UAV j and the UE i in time slot t; P ji represents the transmit power of the UAV j and the UE i ; represents the average path loss between the UAV j and the UE i in time slot t, equals σ0 represents the power spectral density of the additive white Gaussian noise at the receiving end.

6. An air-to-ground hybrid communication device, characterized in that, Including: Hybrid communication architecture and channel model construction module, which is used to design a hybrid communication architecture for a scenario containing multiple unmanned aerial vehicles (UAVs) and user equipment (UEs), and establish a channel model between UAVs and UEs; among them, the j-th UAV in the air above the ground is denoted as UAV j , the i-th UE on the ground is denoted as UE i , In the hybrid communication architecture, the communication cycle is divided into T equal time slots, the duration of time slot t is denoted by τ, and τ is small enough Each time slot is divided into an uplink and a downlink transmission phase based on TDD technology, and the transmission duration is divided according to the uplink-downlink ratio; based on FDMA technology, the total system frequency bandwidth within each time slot is divided into sub-frequency bandwidths for each UE according to a division ratio of multiple sub-bandwidths matching the number of UEs A communication rate calculation result acquisition module, configured to calculate the uplink data transmission rate and the downlink data transmission rate between the UAV and the UE in each time slot based on the hybrid communication architecture and the channel model, as the communication rate calculation result for the corresponding time slot; A communication decision calculation module, configured to determine the communication decision between the UAV and the UE in each time slot based on the communication rate calculation result between the UAV and the UE, to characterize whether to establish a communication connection, and realize the air-to-ground communication between the UAV and the UE in the scenario through the communication decision; The calculation formula of the communication decision is: Among them, represents the combined data transmission rate between the UE i and the UAV j in time slot t; represents the uplink data transmission rate between the UE i and the UAV j in time slot t; represents the downlink data transmission rate between the UE i and the UAV j in time slot t; m represents the weight of the uplink rate, and n represents the weight of the downlink rate; represents the maximum value among the combined data transmission rates between the UE i and all UAVs in time slot t, Indicates the communication decision between the UAV j and the UE i in time slot t, indicating that the UE i establishes a communication connection with the UAV j ; indicating that the UE i does not establish a communication connection with the UAV j .

7. A communication system, characterized in that, Including multiple unmanned aerial vehicles (UAVs) and user nodes (UEs), and the communication system realizes air-to-ground communication by using the air-to-ground hybrid communication method according to any one of claims 1-5.

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