UAV cluster collaborative communication method and device based on reverse second-layer blockchain

Abstract

The present invention provides a method and device for cooperative communication of a drone cluster based on a reverse two-layer blockchain, wherein the method includes: encrypting channel quality information and storing the channel quality information to complete the main chain initialization; monitoring the ground-to-air communication link, and if the ground-to-air communication link cannot complete the communication requirements between the drones in the drone cluster and the ground station and meets the activation conditions of the second-layer side chain, completing the communication between the drones by activating the second-layer side chain, and starting the heartbeat packet proof consensus mechanism when the second-layer side chain stores information; if the ground-to-air communication link can complete the communication requirements between the drones in the drone cluster and the ground station, then dormant the second-layer side chain, and communicate through the main chain, so that in the case of interference, the interference status information of the entire drone network can still be synchronized, and the interference status information feedback is effectively used to adjust channel selection and power control, thereby solving the interference avoidance problem of the entire drone network.

Description

Technical Field

[0001] This document relates to the field of blockchain-based wireless communication technology, and in particular to a method and device for cooperative communication of drone clusters based on a reverse second-layer blockchain. Background Art

[0002] Drone swarms consist of numerous nodes, and swarm control requires coordinated coordination to achieve mission objectives. When a swarm is exposed to interference, inter-drone communication becomes difficult to maintain, and centralized communication can easily create single points of failure. Leveraging the immutability and decentralization of blockchain, a trusted wireless communication network without a control center can demonstrate robust single-point-of-failure resistance against targeted external interference attacks in interference environments. Therefore, blockchain-based decentralized communication approaches hold great promise.

[0003] Patent application CN112383944A discloses a blockchain-based method for adaptive networking of drone swarms. This invention, incorporating basic blockchain technology, achieves adaptive networking of drone swarms with built-in blockchains. This, combined with an identifier-based dynamic networking mechanism for drone swarms, improves drone efficiency. Patent CN108418622B discloses a blockchain-based method for group decision-making among drones. This invention utilizes multi-drone voting to make collective decisions, increasing the authenticity of drone-collected data. Wang Haotong et al. proposed a blockchain-based anti-interference communication model for drone swarms. This model utilizes encrypted transmission and group voting to improve access control logic and enhance the ability of drone swarms to resist non-cooperative interference. However, current blockchain-based wireless communication mechanisms are difficult to deploy in drone networks in interference environments. The consensus mechanism used in Chinese patent application CN112383944A is proof-of-work (PoW), and each drone maintains a complete blockchain. This consensus mechanism consumes significant energy, which is inconsistent with the limited onboard energy resources of drone platforms. The voting decision-making methods of Chinese patent CN108418622B and Wang Hao's patent require frequent communication between drones. However, the communication quality between drones is difficult to guarantee in an interference environment. Using voting to communicate in a scenario where communication is interrupted at any time will produce uncontrollable communication delays. In the interference confrontation scenario, it is difficult to meet the urgent needs of drone networks for rapid storage and rapid use of information.

[0004] In summary, the difficulties in direct deployment stem from three main factors. First, traditional blockchain technology suffers from slow transaction verification and low communication system capacity. Second, ground-to-air communication quality is difficult to maintain in interference environments, resulting in high latency. Third, the traditional consensus process consumes significant onboard energy, making it incompatible with drone platforms. In short, traditional blockchain is unsuitable for drone networks due to low communication capacity, slow consensus processes, excessive energy consumption, and susceptibility to interruption by interference.

[0005] While blockchain technology offers technical advantages in defending against malicious nodes, traditional blockchain technology suffers from a very slow transaction verification speed, making it difficult to meet the demands of the fast-paced offensive and defensive confrontations between drone platforms and jammers. To increase transaction verification speed, the blockchain used in drone networks needs to be scaled. Blockchain scaling technologies can be categorized into three types based on their technical approaches: zero-layer, first-layer, and second-layer. Zero-layer scaling involves optimizing the underlying blockchain data transmission network. First-layer scaling involves completely changing the blockchain's main chain using newly designed blockchain technology. Second-layer scaling involves scaling without changing the main chain, primarily through state channels, sidechains, and cross-chain mechanisms to increase transaction speed. Since the quality of wireless communication links is significantly different from that of wired communication links, zero-layer scaling is difficult to apply. Furthermore, since the scenario under consideration involves intelligent jamming attacks, where jamming strategies can be constantly changing, the blockchain deployed in drone networks must also be able to flexibly expand its functionality. Compared to first-layer scaling, second-layer scaling offers greater functional expansion capabilities. Therefore, second-layer technologies hold great potential in addressing the aforementioned challenges. Summary of the Invention

[0006] This invention provides a method and device for cooperative communication in drone swarms based on a reversed two-layer blockchain. By swapping the first and second layer functions within a traditional two-layer blockchain architecture, the first-layer main chain deployed on the ground station is responsible for performance enhancement, while the side chain deployed on the drone network is responsible for the consensus mechanism. To meet the requirement of low energy consumption, a heartbeat message negotiation algorithm is designed that embeds local trust information into the heartbeat message, allowing the transmission of trust information with minimal computational load.

[0007] The present invention provides a UAV cluster collaborative communication method based on a reverse second-layer blockchain, comprising:

[0008] S1. Initialize the main chain by encrypting and storing the channel quality information;

[0009] S2. Monitor the ground-to-air communication link. If the ground-to-air communication link cannot complete the communication requirements between the drones in the drone cluster and the ground station and meets the activation conditions of the second-layer side chain, the second-layer side chain is activated to complete the communication between the drones. The heartbeat packet proof consensus mechanism is initiated when the second-layer side chain stores information.

[0010] S3. If the ground-to-air communication link can meet the communication requirements between the drones in the drone cluster and the ground station, the second-layer side chain will be dormant and communication will be carried out through the main chain.

[0011] The present invention provides a UAV cluster collaborative communication device based on a reverse second-layer blockchain, comprising:

[0012] Establishing a main chain module for completing the main chain initialization by encrypting and storing the channel quality information;

[0013] Layer 2 sidechain communication module: used to monitor the ground-to-air communication link. If the ground-to-air communication link cannot complete the communication requirements between the drones in the drone cluster and the ground station and meets the activation conditions of the layer 2 sidechain, the communication between the drones is completed by activating the layer 2 sidechain. The heartbeat packet proof consensus mechanism is initiated when the layer 2 sidechain stores information.

[0014] The main chain communication module is restored to determine whether the ground-to-air communication link can meet the communication requirements between the drones in the drone cluster and the ground station, then the second-layer side chain is dormant and communication is carried out through the main chain.

[0015] The embodiments of the present invention flexibly switch between two blockchain storage methods, the first-layer main chain storage and the second-layer side chain storage, depending on the degree of interference in ground-to-air communication. This avoids the problem of traditional solutions becoming inoperable if ground-to-air communication is interrupted. A heartbeat packet proof consensus mechanism is designed to determine accounting rights based on topological advantage, which does not require additional energy consumption. Furthermore, the consensus process is tolerant of communication interruptions. Even if communication is interrupted, the consensus process still "participates". The lack of heartbeat packet feedback indicates that the topological advantage is not present, thus saving energy consumption during the consensus process.

[0016] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate one or more embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a flowchart of a drone cluster collaborative communication method based on a reverse second-layer blockchain according to an embodiment of the present invention;

[0019] Figure 2 This is the reverse two-layer blockchain structure of an embodiment of the present invention;

[0020] Figure 3 Schematic diagram of the activation process of the layer 2 side chain according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the heartbeat packet consensus process according to an embodiment of the present invention;

[0022] Figure 5 Schematic diagram of a drone cluster collaborative communication device based on a reverse second-layer blockchain according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below in conjunction with the drawings in one or more embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this document.

[0024] Method Example

[0025] According to an embodiment of the present invention, a method for cooperative communication of drone clusters based on a reverse second-layer blockchain is provided. Figure 1 This is a flow chart of the UAV cluster collaborative communication method based on the reverse second-layer blockchain according to an embodiment of the present invention. Figure 1 As shown, the drone cluster collaborative communication method based on the reverse second-layer blockchain in an embodiment of the present invention includes:

[0026] Step S101, completing the main chain initialization by encrypting and storing the channel quality information, step S101 specifically includes:

[0027] Step 1.1: System initialization and key distribution. The first layer of the main chain deployed on the ground station GCS is initialized first. To ensure the confidentiality of the main chain data and to facilitate the implementation of the smart contract access control function, the main chain data is encrypted with asymmetric keys using the elliptic curve digital signature algorithm. The ground station is responsible for the authorization of the distributed trust center. Before the drone performs a mission, the drone pre-sets the public key of the GCS as the trust root. The identity ID is ID i UAV u i Get its public and private keys and corresponding certificates from GCS Used for encryption of channel quality information. i After the initialization is completed, the drone u i Become a legitimate node of the main chain. When the drone flies through the GCS service area, it can download and update the required latest block data from the main chain.

[0028] Step 1.2: Channel quality information storage. i The UAVs continuously communicate with their neighboring UAVs. During the communication process, the channel quality information is of great value to the neighboring UAVs to avoid interference. Therefore, the UAVs as receiving nodes have a strong motivation to send channel quality information such as SINR data back to the sender and GCS. j In the drone u i Upload channel quality information to GCS j Before, u i First send the upload request to GCS j The request includes the identity ID i , the corresponding signature and certificates After receiving the request, GCS j Will verify the drone u i The storage permission and send the response back to u i If you allow i Storage, then u i In use i Public key After encryption, the channel quality information and location information will be sent to GCS as a record j ,Right now

[0029]

[0030] in,

[0031]

[0032]

[0033]

[0034] Step 1.3: Generate main chain block. i Through GCS j The latest channel quality information report will be uploaded when the GCS service area is reached. j and drone u i After sending ACK messages to each other, GCS j The report is packaged into a temporary storage pool. j When the number of information items in the temporary storage pool reaches the capacity of a block, GCS jGenerate a new block with a timestamp and broadcast it to other GCSs for review and verification. When the identity of the sender of the ACK message is verified, the block is appended to the end of the main chain. When a GCS fails to collect enough information items within the specified time, each GCS broadcasts its own temporary storage pool to its neighboring GCSs, and the GCS with the most information items among its neighbors is responsible for packaging them into blocks. The verification task at this time includes two items: one is to verify whether the GCS responsible for packaging has contributed the most information items, and the other is to verify whether the information in its own temporary storage pool is packaged repeatedly. If the number of duplicate packaged information items does not exceed a predetermined ratio (usually 5%), the duplicate information in the block can be marked as invalid and passed for confirmation. Otherwise, the block will be invalid and wait for repackaging and verification. After verification, the block is appended to the end of the main chain.

[0035] Step S102: Monitor the ground-to-air communication link. If the ground-to-air communication link cannot complete the communication requirements between the drones in the drone cluster and the ground station and meets the activation conditions of the second-layer side chain, the second-layer side chain is activated to complete the communication between the drones. The heartbeat packet proof consensus mechanism is initiated when the second-layer side chain stores information.

[0036] When communication between a drone and the ground station (GCS) is disrupted by intelligent jamming and coordinated deception attacks, the channel quality information collected by the drone cannot be shared with the GCS. In this situation, a DAG-based Layer 2 sidechain is activated, allowing drones to share information directly without going through the GCS. The sidechain uses DAG as its data structure. This is because DAG offers advantages such as high concurrency, high efficiency, and low energy consumption, making it suitable for use in harsh communication environments. Figure 2 This is the reverse two-layer blockchain structure of the embodiment of the present invention. Figure 3 The following is a schematic diagram of the activation process of the second-layer side chain. The activation process of the second-layer side chain includes:

[0037] The second layer side chain wakes up. There are two prerequisites for the activation of the second layer side chain. The first is that the communication interruption time between the drone and the GCS exceeds the threshold time T DAG Another condition is the average reputation value of the drones requesting to activate the second layer DAG side chain. Greater than the average Rep of the entire network AVG When these two conditions are met, the second layer DAG side chain will be activated. After activating the side chain, check to ensure that the generation unit G has been created. The generation unit is Figure 3 Nodes are marked with the letter "G".

[0038] The second-layer sidechain operates as follows. When a receiving drone generates new channel quality information based on the latest SINR value, the information selects two distal tip nodes as parent units. Tip nodes are leaf nodes in the DAG data structure. When selecting tip nodes, nodes with smaller timestamp values are prioritized. After selecting these two tip nodes, the new report is broadcast to other drones in the second-layer sidechain network. Other drones verify the received broadcast message. If no anomalies are found, an ACK message is broadcast. When the reputation value of the drone sending the confirmation message exceeds half, the report is verified and officially added to the end of the second-layer sidechain, becoming a new tip node.

[0039] Among them, when the side chain needs to store information, the heartbeat packet proof consensus mechanism is started.

[0040] To overcome the difficulty in maintaining link communication quality under interference attacks, and in response to the reality of coordinated interference and deception attacks, a heartbeat packet proof consensus mechanism has been designed for Layer 2 sidechain drone networks. The key idea of this consensus mechanism is that, when link communication quality is poor, the number of heartbeat packets received or forwarded represents the topological advantage of a node. The node with the greatest topological advantage is selected as the winning node for this round, and thus obtains the right to record the transaction, thereby reducing communication costs for the entire network.

[0041] During the operation of the mechanism, each drone regularly broadcasts heartbeat packets to neighboring nodes. In order to reduce the communication burden, a lightweight heartbeat packet is designed, which is a timestamp signed by a private key. min Indicates the minimum SINR at which the receiver can successfully resolve the signal. When the SINR of the heartbeat packet received by the neighboring drone is greater than the SINR min When , it indicates that there is a communicative drone nearby. After successfully receiving the heartbeat packet, if the next round of heartbeat packet sending time has not yet arrived, the drone will re-sign the received heartbeat data packet with its own private key and then continue to broadcast it.

[0042] Each drone maintains a variable This variable represents the number of drones u in a period of time. i The total number of direct and indirect heartbeat packets received. When there is a new channel information that requires consensus, the drone broadcasts Neighbor drone confirmed value, The drone with the largest value is the winner of this round. Table 1 shows the detailed process of generating consensus.

[0043] Table 1 Heartbeat packet proof consensus process

[0044]

[0045]

[0046] The heartbeat packet consensus process diagram is as follows Figure 4 As shown. The consensus process is divided into 5 stages. In the first stage, each drone in the second-layer side chain will broadcast the received heartbeat packet. In the second stage, the drone verifies whether the heartbeat packet is sent directly or forwarded. In the third stage, the drone signs the verification result and broadcasts it. Figure 4 In the example, Drone 2 received the most heartbeat packets. After verification and review by the other drones, its status changed from potential winner to winner of the fourth phase. In the final phase, Drone 2 selected two tip nodes, established two hash pointers to verify the selected tip nodes, and appended the new record data to the DAG distributed ledger.

[0047] Step S103: If the ground-to-air communication link can meet the communication requirements between the drones in the drone cluster and the ground station, the second-layer side chain is dormant and communication is carried out through the main chain. Step S103 specifically includes:

[0048] The second-layer sidechain is dormant. When the drone in the second-layer sidechain resumes ground-to-air communication, it broadcasts a request to terminate the second-layer sidechain. When the reputation of the drone requesting sidechain termination exceeds half of the total reputation of the second-layer sidechain network, the second-layer sidechain will terminate. Historical sidechain data is sent back to the GCS, which converts it into a standard mainchain block format and appends it to the end of the mainchain.

[0049] When the communication between some drones and GCS is interrupted, only some drones will use the second-layer side chain to share information, while the remaining drones will continue to use the first-layer main chain to share information.

[0050] When the task is completed, the second-layer side chain and the first-layer main chain will be closed.

[0051] The embodiment of the present invention exchanges the functions of the first and second layers in a traditional two-layer blockchain architecture, with the first-layer main chain deployed on the ground station responsible for performance improvement, and the side chain deployed on the drone network responsible for the consensus mechanism. The design inspiration of this reverse two-layer blockchain architecture comes from the fact that in the scenario under discussion, the SINR information stored in the blockchain has distinct regional and time-sensitive characteristics. In comparison, the strong consistency in the CAP theorem is much less important for this specific research problem. The present invention relaxes the requirement of strong consistency to local consistency, giving the highest priority to availability. This design concept can greatly speed up the transaction verification.

[0052] This embodiment of the present invention can flexibly switch between the ground-based primary link and the aerial drone network's secondary side link based on the quality of ground-to-air communication, achieving optimal interference status information storage. While ensuring availability, it maximizes the use of ground-based edge computing capabilities to reduce drone network energy consumption. As long as the ground-to-air communication link can be established, mobile edge computing can be used to compensate for the drone platform's computing power deficit, effectively alleviating the platform's computational load.

[0053] Embodiments of the present invention design a low-latency consensus mechanism capable of reaching consensus within a limited timeframe in harsh communication environments. This mechanism, based on the drone network topology and channel communication quality, selects a node suitable for information aggregation as the winning node in the consensus process, completing the information storage task. This novel consensus mechanism determines the accounting node based on topological location advantages, avoiding the energy-consuming Proof-of-Work (PoW) operation and significantly reducing the energy consumption of the consensus process.

[0054] Blockchain technology uses a data structure with end-links between blocks, with each block containing multiple transactions. When communication quality is poor, the transmission of channel quality information becomes difficult. If sufficient transactions must be collected before they can be packaged into blocks, the confirmation time will be excessive, seriously affecting the timeliness of the information. The two-layer sidechain data structure of this invention replaces the blockchain with a transaction chain, allowing every two transactions to be added to the chain. This will significantly accelerate the storage and utilization of information on the distributed ledger.

[0055] By adopting the embodiments of the present invention, the following beneficial effects are achieved:

[0056] 1. The present invention can flexibly switch between two blockchain storage methods: the first-layer main chain storage and the second-layer side chain storage according to the degree of interference in ground-to-air communication, avoiding the problem that traditional solutions cannot work once the ground-to-air interruption occurs.

[0057] 2. This invention designs a heartbeat packet proof consensus mechanism for drone networks that determines bookkeeping rights based on topological advantage. This consensus mechanism does not require additional energy consumption. Furthermore, the consensus process is tolerant of communication interruptions. Even if communication is interrupted, the consensus process is still "participated" and the lack of heartbeat packet feedback indicates that the network lacks topological advantage.

[0058] Device embodiment

[0059] According to an embodiment of the present invention, a drone cluster collaborative communication device based on a reverse second-layer blockchain is provided. Figure 5 This is a schematic diagram of a UAV cluster collaborative communication device based on a reverse second-layer blockchain according to an embodiment of the present invention. Figure 5 As shown, the drone cluster collaborative communication device based on the reverse second-layer blockchain in an embodiment of the present invention includes:

[0060] The main chain establishment module 50 is used to complete the main chain initialization by encrypting and storing the channel quality information. The main key establishment module 50 is specifically used to:

[0061] Before the drone performs a mission, it sets the public key of the ground station as the root of trust. The drone obtains the public key, private key and corresponding certificate of the ground station to encrypt the channel quality information, thereby completing the initialization of the drone and making the drone a legitimate node of the main chain.

[0062] The drone sends the channel quality information and location information to the ground station. Before sending, the drone first sends an upload request to the ground station. After the upload request is approved, the drone uses the public key to encrypt the quality information and location information and sends it to the ground station.

[0063] The ACK messages sent between the drone and the ground station are packaged into a temporary storage pool. When the number of information items in the temporary storage pool reaches the capacity of a block at a specific time, the ground station generates a new block with a timestamp and adds it to the end of the main chain. If the number of information items in the temporary storage pool does not reach the capacity of a block at a specific time, the ground station broadcasts its temporary storage pool to its neighboring ground stations. Among the neighboring ground stations, the ground station with the largest number of information items is selected to generate a new block and add it to the end of the main chain.

[0064] The second-layer side chain communication module 52 is used to monitor the ground-to-air communication link. If the ground-to-air communication link cannot complete the communication requirements between the drones in the drone cluster and the ground station and meets the activation conditions of the second-layer side chain, the second-layer side chain is activated to complete the communication between the drones. The heartbeat packet proof consensus mechanism is initiated when the second-layer side chain stores information;

[0065] The activation conditions for the second-layer side chain include:

[0066] The communication interruption time between the drone and the ground station exceeds the interruption threshold time, and the average reputation value of the drone requesting to activate the second-layer side chain is greater than the average value of the entire network.

[0067] Furthermore, the specific steps of completing communication between drones via the second-layer side chain in the second-layer side chain communication module 52 include:

[0068] The information receiving drone generates new channel quality information based on the latest SINR value and selects two tip nodes as parent units in the new channel quality information. When selecting the tip node, the node with the smaller timestamp value is selected.

[0069] After selecting two terminal Tip nodes, the message information generated by the new channel quality information will be broadcast to other drones in the second-layer side chain. Other drones verify the received broadcast message information and perform verification. If the verification is successful, a confirmation message will be broadcast. When the reputation value of the drone sending the confirmation message exceeds half, the message information is verified and added to the tail of the second-layer side chain, becoming a new Tip node.

[0070] Furthermore, the heartbeat packet proof consensus mechanism initiated in the second-layer side chain communication module 52 specifically includes:

[0071] The drone broadcasts heartbeat packets to neighboring nodes at specific intervals. The heartbeat packets are timestamped and signed by the private key.

[0072] After receiving the heartbeat data packet, the drone verifies the heartbeat data packet and decides whether to send or forward the strip data packet based on the verification result;

[0073] The drone signs and verifies the verification results and broadcasts them;

[0074] The drone that receives the most heartbeat packets will be the winner;

[0075] The winner selects two tip nodes and appends the new record data to the DAG distributed ledger.

[0076] The main chain communication module 54 is used to determine if the ground-to-air communication link can meet the communication requirements between the drones in the drone cluster and the ground station, then dormant the second-layer side chain and communicate through the main chain. The main chain communication module 54 is specifically used to:

[0077] When each drone communicating using the second-layer side chain resumes communication with the ground station, the drone that resumes communication broadcasts a request to terminate the second side chain;

[0078] When the reputation value of the drone requesting the termination of the second side chain exceeds half of the total reputation value of the second side chain, the second side chain will be terminated;

[0079] The data of the second side chain is sent back to the ground station, which converts the data of the second side chain into the standard main chain data format and appends it to the end of the main chain.

[0080] When some drones that use the second-layer side chain for communication resume communication with the ground station, the drones that have not resumed communication communicate through the second-layer side chain, and the drones that resume communication communicate through the main chain.

[0081] When the drone completes the communication mission, the second-layer side chain and the main chain are closed.

[0082] By adopting the embodiments of the present invention, the following beneficial effects are achieved:

[0083] 1. The present invention can flexibly switch between two blockchain storage methods: the first-layer main chain storage and the second-layer side chain storage according to the degree of interference in ground-to-air communication, avoiding the problem that traditional solutions cannot work once the ground-to-air interruption occurs.

[0084] 2. This invention designs a heartbeat packet proof consensus mechanism for drone networks that determines bookkeeping rights based on topological advantage. This consensus mechanism does not require additional energy consumption. Furthermore, the consensus process is tolerant of communication interruptions. Even if communication is interrupted, the consensus process is still "participated" and the lack of heartbeat packet feedback indicates that the network lacks topological advantage.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A drone cluster collaborative communication method based on reverse second-layer blockchain, characterized in that: include: S1. Initializing the main chain by encrypting and storing the channel quality information; S2. Monitor the ground-to-air communication link. If the ground-to-air communication link cannot complete the communication requirements between the drones in the drone cluster and the ground station and meets the activation conditions of the second-layer side chain, activate the second-layer side chain to complete the communication between the drones. The second-layer side chain initiates the heartbeat packet proof consensus mechanism when storing information. S3. If the ground-to-air communication link can meet the communication requirements between the drones in the drone cluster and the ground station, then the second-layer side chain is dormant and communication is carried out through the main chain; The activation conditions of the second-layer side chain in step S2 specifically include: The communication interruption time between the drone and the ground station exceeds the interruption threshold time, and the average reputation value of the drones requesting activation of the second-layer side chain is greater than the average value of the entire network; The heartbeat packet proof consensus mechanism started in step S2 specifically includes: The drone broadcasts a heartbeat data packet to neighboring nodes at a specific interval. The heartbeat data packet is a timestamp signed by a private key. After receiving the heartbeat data packet, the drone verifies the heartbeat data packet and determines whether to send or forward the heartbeat data packet according to the verification result; The drone signs and verifies the verification result and broadcasts it; The drone that receives the most heartbeat data packets is selected as the winner; The winner selects two tip nodes and appends the new record data to the DAG distributed ledger.

2. The method according to claim 1, characterized in that The step S1 specifically includes: S11. Before the drone performs a mission, it sets the public key of the ground station as the root of trust. The drone obtains the public key, private key, and corresponding certificate of the ground station to encrypt the channel quality information, thereby completing the initialization of the drone and making the drone a legitimate node of the main chain. S12. The UAV sends the channel quality information and location information to the ground station. Before sending, the UAV first sends an upload request to the ground station. After the upload request is approved, the UAV encrypts the quality information and location information using the public key and sends the encrypted information to the ground station. S13. Pack the ACK messages sent between the drone and the ground station into a temporary storage pool. When the number of information items in the temporary storage pool reaches the capacity of a block at a specific time, the ground station generates a new block with a timestamp and adds it to the end of the main chain.

3. The method according to claim 1, characterized in that The specific steps of completing the communication between drones through the second-layer side chain in step S2 include: The information receiving drone generates new channel quality information based on the latest SINR value and selects two tip nodes as parent units in the new channel quality information. When selecting the tip node, the node with the smaller timestamp value is selected. After selecting two terminal Tip nodes, the message information generated by the new channel quality information will be broadcast to other drones in the second-layer side chain. Other drones verify the received broadcast message information and perform verification. If the verification is successful, a confirmation message will be broadcast. When the reputation value of the drone sending the confirmation message exceeds half, the message information passes the verification and is added to the tail of the second-layer side chain, becoming a new Tip node.

4. The method according to claim 1, wherein The step S3 specifically includes: When each drone communicating using the layer-2 side chain resumes communication with the ground station, the drone that resumes communication broadcasts a request to terminate the layer-2 side chain; When the reputation value of the drone requesting the termination of the second-layer side chain exceeds half of the total reputation value of the second-layer side chain, the second-layer side chain will be terminated; The data of the second-layer side chain is sent back to the ground station, which converts the data of the second-layer side chain into a standard main chain data format and appends it to the end of the main chain.

5. The method according to claim 4, characterized in that The step S3 further comprises: When some of the drones that communicate using the second-layer side chain resume communication with the ground station, the drones that have not resumed communication communicate through the second-layer side chain, and the drones that resumed communication communicate through the main chain.

6. The method according to claim 1, characterized in that The method further comprises: When the drone completes the communication task, the second-layer side chain and the main chain are closed.

7. The method according to claim 2, characterized in that The step S13 further comprises: If the number of information items in the temporary storage pool cannot reach the capacity of a block within a specific time, the ground station broadcasts its own temporary storage pool to its neighboring ground stations, and selects the ground station with the largest number of information items among the neighboring ground stations to generate a new block and add it to the end of the main chain.

8. A UAV cluster collaborative communication device based on a reverse second-layer blockchain based on the UAV cluster collaborative communication method based on a reverse second-layer blockchain according to any one of claims 1 to 7, characterized in that: include: Establishing a main chain module, configured to complete main chain initialization by encrypting and storing channel quality information; A second-layer sidechain communication module is used to monitor the ground-to-air communication link. If the ground-to-air communication link cannot complete the communication requirements between the drones in the drone cluster and the ground station and the activation conditions of the second-layer sidechain are met, the second-layer sidechain is activated to complete the communication between the drones. The heartbeat packet proof consensus mechanism is initiated when the second-layer sidechain stores information; The main chain communication module is restored to determine whether the ground-to-air communication link can meet the communication requirements between the drones in the drone cluster and the ground station, then dormant the second-layer side chain and communicate through the main chain.

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