Unmanned aerial vehicle swarm networked measurement and control communication system and communication method

Abstract

The invention relates to the technical field of communication, and provides an unmanned aerial vehicle swarm networked measurement and control communication system and method, and the architecture of the communication system comprises a network layer, a link layer and a physical layer. A routing protocol in the network layer uses a cross-layer pulse routing protocol, and all nodes multiplex a neighbor connection relationship in two hops of the link layer in a cross-layer manner; the link layer adopts a pre-allocation and dynamic negotiation resource management strategy based on a time division multiple access protocol and a storage scheduling strategy based on a service quality level; and the physical layer adopts an MIMO technology and an adaptive modulation and coding technology, and supports different service transmission requirements of multiple users. According to the invention, the problems of low channel utilization rate and slow response to dynamic topology change can be solved, and high-capacity information transmission, inter-aircraft cooperative information distribution and unmanned aerial vehicle networked measurement and control services are supported at the same time.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and in particular, to a networked measurement and control communication system and a communication method for a drone swarm. Background Art

[0002] The existing networked measurement and control communication systems and communication methods for drone swarms assume relatively ideal application scenarios and do not comprehensively consider aspects such as the actual combat environment, application scenarios, mobility, and scalability. For example, the invention patent "A Measurement and Control Communication Link and a Communication Method for a Drone Group Network" (patent publication number CN114697902A) is only applicable to single-hop networks and does not consider the complex actual combat environment where the movement of drone nodes can cause drastic topological changes and the need for a routing protocol to maintain the robust connection of the communication link. In the invention patent "A Multi-Node Relay Communication Method Based on Dynamic Time Slot Allocation" (patent publication number CN114125784A), the master node needs to perform dynamic time slot allocation, without considering the survivability of the network and the mobility requirements of the drone swarm networking, etc.

[0003] Drone swarms are large in number, mobile and flexible, with outstanding characteristics such as rapid deployment and excellent coordination ability, and have unique battlefield advantages. The basis for the autonomous networking and formation coordination of drone swarms is that each drone node can communicate with each other through an inter-aircraft communication link, and the prerequisite for the operator to effectively command or supervise the drone swarm is to have a robust measurement and control communication link. The existing networked measurement and control communication systems for drone swarms have problems such as slow response to topological changes and low channel utilization rate, resulting in limited scale of task nodes, which need to be solved urgently.

[0004] (1) Solve the problem of low channel utilization rate.

[0005] The existing networked measurement and control communication systems for UAV swarms usually adopt link layer designs mainly including distributed Time Division Multiple Access (TDMA) types and contention-based random access type control protocols. For example, the Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) protocol provided by IEEE 802.11. CSMA / CA adopts a contention-based resource allocation method and uses the RTS / CTS mechanism for collision avoidance. When the number of unicast traffic flows in the network is small, channel preemption can be quickly completed with a small delay. However, when the number of unicast traffic flows in the network is large, a backoff mechanism needs to be adopted for collision avoidance, which results in a long waiting time for data packets in the queue and thus increases the end-to-end delay. In addition, the CSMA / CA protocol is difficult to ensure the reliable transmission of broadcast services. The traditional TDMA protocol allocates resources to all nodes in the network by means of time slot polling. Each node knows in advance the time to access the channel and the time to occupy the channel, and can reasonably set the data packet transmission time according to the network scale, reduce the probability of data packet collision, improve the channel utilization rate, and can well support broadcast and unicast services. However, in the case of a large-scale network, the load differences of different links in the network are large, and the network nodes still follow a fixed time slot polling mechanism, lacking a certain degree of flexibility, which increases the data packet delay of high-traffic links and results in low performance.

[0006] (2) Solve the problem of slow response to dynamic topology changes

[0007] When UAV swarms operate in complex environments such as cities and mountains, factors such as obstacle occlusion, multipath effects, high-speed movement of nodes, and single-point failures will cause frequent changes in link states. When using traditional proactive link state-based routing or on-demand routing, local link state changes or interruptions of active paths will cause the routing to broadcast control messages to the entire network, with poor adaptability to mobile communication of tactical network nodes, low routing sensitivity, and inability to ensure the robustness of communication links.

[0008] (3) Solve the problems of simultaneously supporting large-capacity information transmission, inter-aircraft collaborative information distribution, and UAV networked measurement and control.

[0009] Typical services of the networked measurement and control communication system for UAV swarms include the uplink remote control service of the command node for all UAVs, the downlink telemetry service and mission payloads of UAVs to the command node; the position information, online status, target data, and collaborative information for inter-aircraft interaction; the designed networked measurement and control communication system and communication method for UAV swarms need to ensure the efficient and reliable transmission of remote control and telemetry information while supporting the effective transmission of high-traffic backhaul services and inter-aircraft interaction services. Summary of the Invention

[0010] The present invention aims to provide a networked measurement and control communication system and a communication method for a drone swarm to solve the above existing problems.

[0011] The present invention provides a networked measurement and control communication system for a drone swarm. The architecture of the communication system includes a network layer, a link layer, and a physical layer;

[0012] The routing protocol in the network layer uses a cross-layer pulse routing protocol, and all nodes cross-layer multiplex the connection relationship of two-hop neighbors in the link layer;

[0013] The link layer adopts a pre-allocation plus dynamic negotiation resource management strategy based on a time division multiple access protocol and a storage scheduling strategy based on the quality of service level;

[0014] The physical layer adopts MIMO technology and adaptive modulation and coding technology to support the transmission requirements of different services for multiple users.

[0015] In some embodiments, the cross-layer pulse routing protocol includes:

[0016] Select the ground control node as the pulse source node; the pulse source node floods pulse messages periodically in the whole network;

[0017] After receiving the pulse message, the node constructs a minimum acyclic spanning tree by updating the distance metric to the pulse source node, and connects all nodes to the pulse source node;

[0018] Each node cross-layer multiplexes the neighbor relationship within two hops reported by the link layer, and periodically updates the paths to the neighbors within two hops in the local routing table;

[0019] If the service source node receives a request to communicate with the target node, it checks whether there is a path to the target node in the local routing table. If not, the service source node unicasts a routing request packet to the pulse source node along the nodes on the minimum acyclic spanning tree;

[0020] The one-hop neighbors of the nodes on the path from the service source node to the pulse source node establish a route to the service source node that sends the routing request packet according to the routing request packet monitored by the broadcast;

[0021] When the pulse source node receives the routing request packet from the service source node, it first checks whether there is a valid path pointing to the target node in the local routing forwarding table: if so, it responds to the service source node, and unicasts a routing response message from the pulse source node to the service source node; if not, the pulse source node will place the target node address label in the paging field of the pulse message and send it out during the next pulse flooding;

[0022] When the target node receives its own address tag in the paging field of the pulse message, it unicasts a routing response message to the pulse source node;

[0023] An end-to-end shortcut is formed between the service source node and the target node. The shortcut is obtained by broadcasting a routing modification message when a one-hop neighbor listens and discovers a shorter path.

[0024] In some embodiments, the pulse message includes: the pulse source node address tag, the distance metric to the pulse source node, the current sequence number, and the list of target nodes that the pulse source node is currently paging.

[0025] In some embodiments, each node on the path from the service source node to the pulse source node needs to complete:

[0026] Create a reverse path towards the service source node in its routing forwarding table;

[0027] Update the distance metric from the service source node;

[0028] Send an updated routing request packet along the tree structure to the pulse source node.

[0029] In some embodiments, each node on the path from the target node to the pulse source node needs to complete:

[0030] Create a reverse path towards the target node in its routing forwarding table;

[0031] Update the distance metric from the target node;

[0032] Send an updated routing response packet along the tree structure to the pulse source node.

[0033] In some embodiments, the pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol includes:

[0034] The pre-allocated static time slots have been reserved in advance for each node during the frame structure design, and the remaining time slots are dynamically negotiated and occupied by each node according to the real-time traffic changes on demand;

[0035] Neighbor interaction to establish a two-hop neighbor connection relationship;

[0036] Calculate the current required number of data time slots N according to the current service load;

[0037] Calculate the number of time slots that need to be applied for or released according to the required number of data time slots N and the number of time slots that the current node already occupies;

[0038] The node sends a resource application message and a resource feedback message in the pre-allocated time slot;

[0039] The node obtains the latest occupied time slot position according to the received resource feedback message.

[0040] In some embodiments, the formula for calculating the number of data time slots N currently required is as follows:

[0041] N=totalUnicastResDemandNum+totalBroadcastResDemandNum

[0042] Among them, totalUnicastResDemandNum represents the total number of unicast traffic demand resources sent by this node to each neighboring node, and totalBroadcastResDemandNum represents the number of broadcast traffic resource demands.

[0043] In some embodiments, the calculation formula for the total number of unicast traffic demand resources sent by the current node to neighboring nodes is as follows:

[0044] totalUnicastResDemandNum=totalUnicastFlow / tbSize current

[0045] Among them, totalUnicastFlow represents the total unicast flow sent by this node to neighboring nodes, tbSize current Indicates the traffic that can be carried by a single timeslot obtained through AMC under the current link status.

[0046] In some embodiments, the storage scheduling strategy based on the quality of service level includes:

[0047] The network layer identifies the service type and labels different types of data packets with corresponding service quality levels;

[0048] The link layer identifies the service quality level label of the data packet from the upper layer, and stores the data packet in different priority queues and different destination node IDs. The node ID counts from 1, and the broadcast message is stored in the index position 0 of each queue.

[0049] According to the time slot occupancy result, if the current time slot is the pre-allocated time slot of this node, it will start from the highest priority queue and traverse step by step, send the broadcast message at index position 0, and assemble the frame according to the carrying capacity corresponding to index position 0; if the current time slot is the data time slot dynamically negotiated by this node, first check whether there is still a high-priority broadcast service that needs to be transmitted: if so, give priority to sending the broadcast message at index position 0 of the high-priority queue; if not, it will start from the highest priority queue and traverse step by step, send the unicast message to a destination node, and assemble and disassemble the frame according to the AMC result;

[0050] If the current time slot is not the transmission time slot of this node, query the locally saved time slot occupancy table for reception, and at the same time, adaptively adjust the modulation and coding level according to the current link measurement results.

[0051] In some embodiments, the adaptive modulation and coding technology adaptively selects an appropriate modulation and coding level for transmission and reception according to the current transceiver link state, including:

[0052] The receiving node obtains the received power magnitude through wireless link measurement;

[0053] Calculate the signal-to-noise ratio SNR from the received power;

[0054] The link state between the receiving node and the current sending node can be perceived through the SNR, and an appropriate MCS level is selected for transmission and reception, and the latest MCS level of the sending node received by the local node is updated;

[0055] Carry the latest MCS level during the next neighbor information interaction, so that after the sending node receives it, it uses the latest MCS level to send data to this node.

[0056] The present invention also provides a method for networked measurement and control communication of an unmanned aerial vehicle (UAV) swarm. The method is implemented based on the above-mentioned networked measurement and control communication system of the UAV swarm, and includes the following steps:

[0057] Initially select the command and control node as the pulse source node of the cross-layer pulse routing protocol;

[0058] After all nodes go online and obtain time synchronization, the command and control node periodically floods pulse messages to establish a minimum acyclic spanning tree from all UAV nodes in the network to the command and control node;

[0059] Each node exchanges control information within its pre-assigned static TDMA time slot. The link layer updates the neighbor connection relationship within two hops and periodically reports it to the network layer;

[0060] The traffic flow drives the node to find the path from this node to the destination node on demand. If there is a valid path to the destination node in the local routing table entry, forward the data packet according to the existing path; if there is no path, perform addressing according to the cross-layer pulse routing protocol and then forward;

[0061] The link layer continuously senses the size of the unicast traffic flow in the sending queue of this node, and performs dynamic time slot occupancy and release according to the pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol;

[0062] The node queries the locally saved time slot occupancy table. If the current time slot is the transmission time slot of this node, the link layer performs packet assembly and disassembly on the data packet based on the storage scheduling strategy of the quality of service level, and sends it to the physical layer to send data;

[0063] Other nodes query the locally saved time slot occupancy table for reception, and at the same time, adaptively adjust the modulation and coding level according to the current link measurement results.

[0064] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0065] 1. The present invention supports large-scale networking applications and has scalability. The present invention adopts a centerless distributed ad hoc network design with a flattened networking structure. The relationship between nodes is peer-to-peer, there is no master node, and there is no limit on the number of relay transmission hops. It supports any node to move arbitrarily within the network range, with strong mobility and anti-destruction ability. There is no need to perform subnet planning and inter-subnet interconnection coordination for network nodes like in a hierarchical and clustered network structure. The present invention has high networking flexibility and scalability. Among them, the physical layer uses MIMO technology to ensure that sufficient transmission bandwidth can be obtained for the communication of a large number of users in the network; the link layer adopts a pre-allocation and dynamic negotiation TDMA protocol to improve the resource reuse degree and the fairness of resource allocation in large-scale networking scenarios; the network layer adopts a cross-layer pulse routing protocol, with controllable signaling overhead, sensitive response to topology changes, and little impact on the increased overhead brought by the growth of the network user scale.

[0066] 2. The present invention provides support for Quality of Service (QoS) guarantee, provides differentiated service guarantee functions at multiple levels of the protocol stack, and ensures the transmission of low-latency real-time services.

[0067] 3. In the present invention, the pre-allocation plus dynamic negotiation resource management strategy based on the Time Division Multiple Access (TDMA) protocol can sense the change of resource demand in real time, conduct dynamic resource negotiation, effectively avoid conflicts, and can maintain a high success rate of time slot application and avoid occupancy conflicts under unstable links. While the pre-allocated time slots guarantee the high-priority transmission of broadcast signaling, they can also be used for the transmission of service data, further ensuring the real-time transmission of high-priority measurement and control services; the dynamically negotiated time slots flexibly guarantee the transmission of large-traffic task payload backhaul services.

[0068] 4. The present invention supports high-reliability communication applications in complex environments. The cross-layer pulse routing has the ability of fast self-formation and self-repair, and adapts to the fully dynamic UAV swarm network with topology changes. In environments such as cities and mountains, the movement of nodes causes frequent changes in the link state. The routing mechanism of the present invention does not require the whole network to announce the link state changes, and the movement of nodes will not cause a significant increase in routing overhead. One pulse flood of the pulse source can quickly repair the damaged path, and at the same time, the cross-layer multiplexes the two-hop neighbor relationship of the link layer, saving the routing overhead of inter-aircraft communication while making the selected path in the moving communication network environment have higher reliability and robustness.

[0069] 5. The present invention is applicable to the communication characteristics of various typical services in the UAV swarm networked measurement and control communication system. Generally speaking, in the application scenario of the UAV swarm networked measurement and control communication system, a large amount of data in the network will be transmitted back to the command and control node or the intelligence processing node, etc. In view of the characteristics of this "backhaul" communication mode, the present invention takes the command and control node as the pulse source, and uses the cross-layer pulse routing protocol with the active pulse flooding mechanism to generate and maintain the minimum acyclic spanning tree structure from all UAV nodes to the command and control node, which can provide zero-waiting available routes for these "backhaul" services without adding obvious network overhead. Moreover, by using the minimum acyclic spanning tree structure, it can also provide efficient distribution support for the transmission of broadcast services in the network, enabling the data from the command and control node to be broadcast and diffused throughout the network along the tree structure path, reducing unnecessary forwarding actions in the flood-style broadcast, and improving the network's carrying capacity and real-time performance for broadcast services such as remote control sent from the command and control node to the UAV swarm. In addition, the cross-layer design in the routing protocol helps to shorten the path finding time and reduce the path finding overhead for the inter-UAV communication service, provides shorter paths, and reduces the transmission delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a schematic diagram of a typical application scenario of the UAV swarm networked measurement and control communication system in an embodiment of the present invention.

[0071] Figure 2 It is an overall block diagram of the architecture of the UAV swarm networked measurement and control communication system in an embodiment of the present invention.

[0072] Figure 3 It is a simulation topology diagram of the UAV swarm networked measurement and control communication system in an embodiment of the present invention.

[0073] Figure 4 It is a comparison result diagram of the simulation results of the routing protocol overhead in an embodiment of the present invention.

[0074] Figure 5 It is a comparison result diagram of the simulation results of the transmission success rate in an embodiment of the present invention.

[0075] Figure 6 It is a simulation result diagram of the end-to-end delay for transmitting 4 QoS level services in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0076] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0077] Accordingly, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0078] Embodiment

[0079] Construct a typical application scenario of the UAV swarm networked measurement and control communication system as Figure 1 shown, which consists of 1 ground command node and 59 UAV nodes in the air, with a total of 60 nodes in the whole network. The command node is one-to-many, and the nodes in the network are connected by multi-hop. In this application scenario, a UAV swarm networked measurement and control communication system and a communication method provided by the present invention are implemented. A flat networking structure is adopted, the relationship between nodes is peer-to-peer, there is no master node, there is no limit on the number of relay transmission hops, the measurement and control communication link and the inter-aircraft communication link work on the same frequency point, and the command node is selected as the pulse source node.

[0080] As Figure 2 shown, in a UAV swarm networked measurement and control communication system provided by an embodiment of the present invention, the architecture of the communication system includes a network layer, a link layer, and a physical layer;

[0081] The routing protocol in the network layer uses a cross-layer pulse (PULSE) routing protocol, and all nodes cross-layer multiplex the connection relationship of two-hop neighbors in the link layer;

[0082] The link layer adopts a pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol (TDMA) and a storage scheduling strategy based on the quality of service (QoS) level;

[0083] The physical layer adopts MIMO technology and adaptive modulation and coding technology to support the transmission requirements of different services of multiple users.

[0084] The following details the specific implementation schemes of the network layer, the link layer, and the physical layer.

[0085] (1) Implementation scheme of the cross-layer pulse routing protocol in the network layer

[0086] The cross-layer pulse routing protocol adopted in the embodiment of the present invention has the capabilities of fast self-formation and self-repair, is sensitive to topological changes, has little impact on the increased overhead caused by the growth of the network user scale, can provide a zero-waiting available route for the "backhaul" service, and does not require an obvious increase in network overhead, and is suitable for the UAV swarm networked measurement and control communication system.

[0087] The cross-layer pulse routing protocol is a hybrid routing protocol that combines the advantages of proactive routing and on-demand routing. Its core idea is to select the command and control node as the pulse source node, and flood pulse messages periodically through the pulse source node to establish the optimal path (minimum acyclic spanning tree) from all UAV nodes in the network to the command and control node, providing efficient distribution support for the transmission of broadcast services in the network, enabling the data from the command and control node to be broadcast and diffused throughout the network along the tree-structured path, reducing unnecessary forwarding actions in flood-style broadcasts, and improving the network's carrying capacity and real-time performance for broadcast services such as remote control sent from the command and control node to the UAV swarm; in addition, other nodes are triggered by the traffic flow to find the route to the destination node on demand through the pulse source node; at the same time, considering that the air-to-air link conditions between UAV nodes are good and most nodes are two-hop reachable, a cross-layer design is used to reuse the two-hop neighbor connection relationships collected during the neighbor interaction at the link layer to periodically update the routes within two hops, reducing the route search time for inter-aircraft interaction services.

[0088] In some embodiments, the cross-layer pulse routing protocol includes the following steps:

[0089] S101, select the ground command and control node as the pulse source node; the pulse source node floods pulse messages periodically throughout the network. In some embodiments, the pulse message includes: the pulse source node address tag, the distance metric to the pulse source node, the current sequence number, and the list of target nodes (if any) that the pulse source node is currently paging.

[0090] S102, after receiving the pulse message, the node updates the distance metric to the pulse source node, and if the updated metric is lower than the previously received distance metric, modifies the next-hop address to the pulse source node in the routing table and re-broadcasts the pulse message; otherwise, discards the pulse message; once the pulse message propagates throughout the network, the network constructs a minimum acyclic spanning tree that connects all nodes to the pulse source node. Note that only the optimal path to the pulse source node is established in the routing tables of all nodes, and no path to the previous-hop node is established, aiming to generate a unidirectional, optimal path (minimum acyclic spanning tree) from any node to the pulse source node.

[0091] S103, each node cross-layer reuses the neighbor relationships within two hops reported by the link layer and periodically updates the paths to the neighbors within two hops in the local routing table.

[0092] S104, if the service source node (SRC) receives a request to communicate with the destination node (DEST), it first checks whether there is a path to the destination node in its local routing table. If not, the service source node unicasts a routing request packet to the pulse source node along the nodes on the minimum acyclic spanning tree; the routing request packet addressed to the pulse source node contains the destination node address label, the distance metric to the service source node, and the distance metric to the destination node. Among them:

[0093] Each node on the path from the service source node to the pulse source node does three things:

[0094] (1) Create a reverse path towards the service source node in its routing forwarding table;

[0095] (2) Update the distance metric from the service source node;

[0096] (3) Send the updated routing request packet along the tree structure to the pulse source node.

[0097] Each node on the path from the destination node to the pulse source node does three things:

[0098] (1) Create a reverse path towards the destination node in its routing forwarding table;

[0099] (2) Update the distance metric from the destination node;

[0100] (3) Send the updated routing response packet along the tree structure to the pulse source node.

[0101] S105, The one-hop neighbors of the nodes on the path from the service source node to the pulse source node establish a route to the service source node that sent the routing request packet according to the routing request packet monitored by broadcast.

[0102] S106, When the pulse source node receives the routing request packet from the service source node, it first checks whether there is a valid path pointing to the destination node in its local routing forwarding table. If so, it responds to the service source node and unicasts a routing response message from the pulse source node to the service source node. If not, the pulse source node will put the destination node address label in the paging field of the pulse message when the next pulse floods.

[0103] S107, When the destination node receives that its own address label is in the paging field of the pulse message, it unicasts the routing response message to the pulse source node. This will also create a reverse route towards the destination node in the node forwarding tables on the tree. At the same time, the one-hop neighbors will monitor the routing response packet and establish a route to the destination node that sent the response packet (this process is the same as step S104).

[0104] S108. An end-to-end shortcut is formed between the service source node and the target node. The shortcut is obtained by a one-hop neighbor listening and then broadcasting a routing modification message when a shorter path is found. That is, when a one-hop neighbor obtains that there is a shorter path for a data packet in the network, it broadcasts a one-hop gratuitous response - a routing modification message to its neighbors. Then, the node that receives this broadcast routing modification message can modify the routing forwarding table to reach the destination node through a shorter path.

[0105] (2) Implementation scheme of the pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol (TDMA) in the link layer

[0106] The link layer access method of the embodiment of the present invention uses the pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol (TDMA), and does not use the contention-based CSMA / CA. Because when the networking scale of the unmanned platform is large, the contention conflict is large and the backoff time is long, resulting in a high packet loss rate, which is not suitable for the node-intensive scenario, and the support for broadcast services is not good. While the pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol (TDMA) can sense the change of resource demand in real time, conduct dynamic negotiation of resources, effectively avoid conflicts, and can maintain a high success rate of time slot application under unstable links and will not cause occupancy conflicts. The pre-allocated time slots ensure the high-priority transmission of broadcast signaling, and can also be used for service data transmission, further ensuring the real-time transmission of high-priority measurement and control services. The dynamically negotiated time slots flexibly ensure the transmission of large-traffic task payload return services.

[0107] In some embodiments, the pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol (TDMA) includes the following steps:

[0108] S201. The pre-allocated static time slots have been reserved in advance for each node during the frame structure design, and the remaining time slots are dynamically negotiated and occupied by each node according to the real-time traffic changes.

[0109] S202. Neighbor interaction to establish a two-hop neighbor connection relationship.

[0110] S203. Calculate the current required number of data time slots N according to the current service load.

[0111] N = totalUnicastResDemandNum + totalBroadcastResDemandNum

[0112] Among them, totalUnicastResDemandNum represents the total number of resource numbers of the unicast traffic demands sent from this node to each neighbor node, and totalBroadcastResDemandNum represents the number of resource demands of the broadcast traffic.

[0113] Among them, the number of unicast traffic resources required by this node to send to neighboring nodes is:

[0114] totalUnicastResDemandNum=totalUnicastFlow / tbSize current

[0115] Among them, totalUnicastFlow represents the total unicast flow sent by this node to neighboring nodes, tbSize current Indicates the traffic that can be carried by a single time slot obtained through AMC under the current link status;

[0116] S204, calculating the number of time slots that need to be applied for or released based on the number of data time slots N required and the number of time slots currently occupied by the node;

[0117] S205, the node sends a resource application message and a resource feedback message in the pre-allocated time slot;

[0118] S206: The node obtains the latest occupied time slot position according to the received resource feedback message.

[0119] (3) Implementation of storage scheduling strategy based on Quality of Service (QoS) level in link layer

[0120] S301, the network layer identifies the service type and tags the different types of data packets with corresponding service quality levels;

[0121] S302, the link layer identifies the service quality level label of the data packet from the upper layer, and stores the data packet in queues with different priorities and destination node IDs, where the node ID starts counting from 1, and the broadcast message is stored at the index position 0 of each queue;

[0122] S303, according to the time slot occupancy result, if the current time slot is the pre-allocated time slot of this node, then start from the highest priority queue and traverse step by step, send the broadcast message of index position 0 (MCS), and assemble the frame according to the carrying capacity corresponding to index position 0 to ensure the reliable transmission of high-priority broadcast services; if the current time slot is the data time slot dynamically negotiated by this node, first check whether there is still a high-priority broadcast service that needs to be transmitted. If so, give priority to sending the broadcast message of index position 0 of the high-priority queue to ensure the real-time transmission of high-priority broadcast services; if not, start from the highest priority queue and traverse step by step, send to a unicast message of a destination node, assemble and disassemble the frame according to the AMC result, and ensure the efficient return of large-volume task load services;

[0123] S304, if the current time slot is not the transmission time slot of this node, query the locally saved time slot occupancy table for reception, and at the same time, adaptively adjust the modulation and coding level according to the current link measurement results.

[0124] (4) Physical layer implementation

[0125] Embodiments of the present invention can work in bands such as L, S, and C bands according to different task environments and applications, and the channel bandwidth can be customized according to requirements. The physical layer uses MIMO multi-antenna technology and is based on an orthogonal frequency division multiplexing (OFDM) multi-carrier modulation transmission scheme, supporting MIMO technologies including maximal ratio combining (MRC), space-time block coding (STBC), and spatial multiplexing. It also makes full use of the multipath propagation characteristics of wireless signals. Moreover, by receiving and processing multiple radio frequency reflected propagation signals generated in the surrounding wireless environment, MIMO technology extends the communication distance range of users in complex environments such as cities, underground, and at sea, and improves the link transmission throughput and communication reliability of the network. The application of these advanced technologies enables the network of the present invention to exhibit obvious performance advantages when working in environments such as cities, tunnels, and buildings.

[0126] The adaptive modulation and coding function (AMC) adaptively selects an appropriate modulation and coding level (MCS) for transmission and reception according to the current transceiver link state, including the following steps:

[0127] S401, the receiving node obtains the received power through wireless link measurement;

[0128] S402, calculate the signal-to-noise ratio SNR through the received power;

[0129] S403, the link state between the current sending node can be sensed through the signal-to-noise ratio SNR, select an appropriate MCS gear for transmission and reception, and update the latest MCS gear of the local node receiving the sending node;

[0130] S404, carry the latest MCS gear during the next neighbor information interaction so that after the sending node receives it, it uses the latest MCS gear to send to this node.

[0131] Based on the above constructed UAV swarm networked measurement and control communication system, a UAV swarm networked measurement and control communication method provided by an embodiment of the present invention includes the following steps:

[0132] S1, initially select the command and control node as the pulse source node of the cross-layer pulse routing protocol;

[0133] S2. After all nodes go online and obtain time synchronization, the accusing node periodically floods pulse messages to establish the optimal path (minimum acyclic spanning tree) from all UAV nodes in the network to the accusing node.

[0134] S3. Each node exchanges control information within its pre-allocated static TDMA time slot. The link layer updates the neighbor connection relationships within two hops and reports them to the network layer regularly.

[0135] S4. The traffic flow drives the node to find the path from the local node to the destination node on demand. If there is a valid path to the destination node in the local routing table, the data packet is forwarded according to the existing path; if there is no path, it is addressed according to the cross-layer pulse routing protocol and then forwarded.

[0136] S5. The link layer continuously senses the size of the unicast traffic in the local node's transmission queue and performs dynamic time slot occupancy and release according to the pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol.

[0137] S6. The node queries the locally saved time slot occupancy table. If the current time slot is the node's transmission time slot, the link layer performs packet framing and deframing on the data packet based on the storage scheduling strategy of the quality of service level and sends it to the physical layer to send the data.

[0138] S7. Other nodes query the locally saved time slot occupancy table for reception and adaptively adjust the modulation and coding level according to the current link measurement results.

[0139] The present invention is further described below through simulation experiments.

[0140] 1. Test Conditions

[0141] Operating System: Windows 10;

[0142] CPU: Above intel i7 7700;

[0143] Memory: Above 16GB;

[0144] Hard Disk: Above 512GB;

[0145] Simulation Software: OMNeT++ 6.0 Preview 10 + INET 4.3.0;

[0146] 2. Test Method

[0147] Build a simulation topology of the UAV swarm networked measurement and control communication system in the OMNET++ software as Figure 3As shown in the figure, host[0] is the ground control node, and host[1] to host

[59] are 59 drone nodes in the air. The entire network consists of 60 nodes in total. The control node has a one-to-many relationship, and the nodes in the network are interconnected through multi-hop. First, compare the routing overhead with typical ad-hoc routing protocols: the proactive Optimized Link State Routing (OLSR) and the on-demand Ad hoc On-Demand Distance Vector Routing (AODV), and analyze the performance of the cross-layer pulse routing protocol used in the present invention; then compare the transmission success rate with the typical competitive link layer access protocol IEEE802.11b, and analyze the performance of the pre-allocation plus dynamic negotiation TDMA protocol used in the present invention; finally, configure typical services of the drone swarm networked measurement and control communication system to verify the overall network performance of the present invention and the correctness of the information link design.

[0148] Model the services of the drone swarm networked measurement and control communication system based on the quality of service level. As shown in Table 1 and Table 2, QoS0 is specified as the highest priority in the present invention.

[0149] Table 1, typical service model of the drone swarm networked measurement and control communication system:

[0150]

[0151] Table 2, simulation parameter configuration table:

[0152]

[0153]

[0154] 3. Test Contents and Results

[0155] (1) Routing protocol performance verification. First, configure 1, 5, and 10 backhaul service flows for the network in sequence, that is, the sending nodes randomly select 1, 5, and 10 from the drone nodes in sequence, and the receiving node is the control node. Under the pre-allocation plus dynamic negotiation resource allocation scheme TDMA protocol and the competitive resource allocation scheme IEEE802.11b protocol, use the proactive OLSR routing and the on-demand AODV routing, and compare with the cross-layer pulse routing in the present invention to observe the change of the routing overhead of the three routing protocols as the number of backhaul service flows increases.

[0156] From Figure 4It can be seen that under the two different link - layer access schemes, the routing protocols have similar trends. Among the three routing protocols, the one with the largest routing overhead is the proactive routing OLSR, followed by the hybrid cross - layer PULSE, and the one with the smallest overhead is the on - demand routing AODV. Among them, as the number of traffic flows (the number of transceiver node pairs) increases, the routing overheads of OLSR and cross - layer PULSE do not show obvious fluctuations, while the routing overhead of AODV increases with the increase in the number of traffic flows. This is because as a proactive routing protocol, OLSR actively establishes all paths in the whole network at each node, and the routing overhead does not change with the number of backhaul traffic flows; cross - layer PULSE pre - establishes all the backhaul paths from all UAV nodes to the command and control node through periodic pulse flooding by the pulse source node, and the routing overhead changes little with the number of backhaul traffic flows; while AODV, as an on - demand routing protocol, after the number of traffic flows increases, more traffic source nodes need to initiate new path requests to address, increasing the overhead.

[0157] (2) Performance verification of link - layer access protocols. Under the scenario described in (1), observe the transmission success rate under different access protocols. Figure 5 It can be seen that when the number of "backhaul" traffic flows is 1, the transmission success rates of service packets of the two link - layer protocols combined with the three routing protocols are all close to 100%; however, as the number of "backhaul" traffic flows increases, the transmission success rates of the 802.11b protocol combined with the three routing protocols gradually decrease. This is because in the 802.11b protocol, broadcast packets are directly sent without using the RTS / CTS mechanism to ensure the channel is idle. For the proactive routing OLSR with the largest broadcast signaling overhead, the probability of broadcast collision is higher, and the routing establishment fails. Therefore, the network packet loss of 802.11b combined with OLSR is the most serious; the TDMA protocol combined with the three routing protocols can all maintain a high transmission success rate because TDMA adopts a pre - allocation plus dynamic negotiation resource management strategy, which negotiates resources for each node according to the traffic volume size, avoids conflicts, and ensures successful routing establishment. Therefore, for the UAV swarm networking with a dense number of nodes and a large number of traffic flows in the network, the transmission success rate of using the TDMA protocol at the link layer is higher.

[0158] Furthermore, by comparing the transmission success rates of the TDMA protocol combined with three routing protocols, it can be obtained that the combination of TDMA and the cross-layer PULSE routing can always achieve a relatively high transmission success rate. The reason is that the routing overhead of OLSR is large, which will occupy the transmission opportunities of services, resulting in packet loss of services and a decrease in the transmission success rate. In addition, the anti-mobility performance of AODV is poor, and the response to topological changes during node movement is slow, resulting in packet loss of services when the link is disconnected and a decrease in the transmission success rate. As a hybrid routing protocol, the cross-layer pulse routing selects the command node as the pulse source to regularly maintain the minimum acyclic spanning tree of all nodes to the pulse source, taking into account the self-repair of the path in the mobile scenario and avoiding a large amount of broadcast flooding overhead in the network. It is naturally applicable to the "backhaul" service scenario of the UAV swarm networked measurement and control communication system.

[0159] (3) Performance verification of the UAV swarm networked measurement and control communication system. Configure typical services with 4 QoS levels for the nodes in the network, and simulate and observe the transmission delay and transmission success rate results.

[0160] Table 3, UAV swarm networking service configuration:

[0161]

[0162] After the simulation is completed, the transmission success rates of services with 4 QoS levels are all 100%. The end-to-end delay results are as Figure 6 shown. According to different QoS levels, this solution preferentially guarantees the transmission of high-priority services. Therefore, the transmission delay of the highest-priority service is the shortest, and the transmission delay of the lowest-priority service is the longest.

[0163] The test results show that the present invention can effectively solve the communication requirements of the UAV swarm networked measurement and control communication system, support large-capacity information transmission, inter-aircraft collaborative information distribution, and UAV networked measurement and control. It can maintain the stable connection of a multi-hop high-dynamic large-scale flat network. While ensuring the efficient and reliable transmission of remote control and telemetry information, it supports the effective transmission of large-traffic backhaul services.

[0164] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A drone swarm networked measurement, control and communication system, characterized in that: The architecture of the communication system includes a network layer, a link layer and a physical layer; The routing protocol in the network layer uses a cross-layer pulse routing protocol, and all nodes cross-layer reuse the two-hop neighbor connection relationship of the link layer; The link layer adopts a pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol and a storage scheduling strategy based on the service quality level; The physical layer adopts MIMO technology and adaptive modulation and coding technology to support multi-user different service transmission requirements.

2. The UAV swarm networked measurement, control and communication system according to claim 1 is characterized in that: The cross-layer pulse routing protocol includes: Select the ground command node as the pulse source node; the pulse source node periodically floods the pulse message in the entire network; After receiving the pulse message, the node builds a minimum acyclic spanning tree by updating the distance metric to the pulse source node, connecting all nodes to the pulse source node; Each node reuses the neighbor relationships within two hops reported by the link layer across layers and periodically updates the paths to neighbors within two hops in the local routing table; If the service source node receives a request to communicate with the target node, it checks whether there is a path to the target node in the local routing table. If not, the service source node unicasts the routing request packet to the pulse source node along the node on the minimum loop-free spanning tree; A one-hop neighbor of a node on the path from the service source node to the pulse source node establishes a route to the service source node that sends the route request packet based on the route request packet monitored by the broadcast; When the pulse source node receives the route request packet from the service source node, it first checks whether there is a valid path to the target node in the local routing forwarding table: if so, it responds to the service source node and sends a route response message unicast from the pulse source node to the service source node; if not, the pulse source node puts the target node address label in the paging field of the pulse message and sends it out during the next pulse flooding; When the target node receives the address label of the local node in the paging field of the pulse message, it unicasts the routing response message to the pulse source node; An end-to-end shortcut is formed between the service source node and the target node. The shortcut is obtained by broadcasting a route modification message when a shorter path is found after monitoring the one-hop neighbor.

3. The UAV swarm networked measurement, control and communication system according to claim 2 is characterized in that: The pulse message includes: a pulse source node address tag, a distance metric to the pulse source node, a current sequence number, and a target node list that the pulse source node is currently paging.

4. The UAV swarm networked measurement, control and communication system according to claim 2, characterized in that: Each node on the path from the service source node to the pulse source node needs to complete: create a reverse path toward the service source node in its routing forwarding table; update the distance metric from the service source node; send the updated routing request packet to the pulse source node along the tree structure; each node on the path from the target node to the pulse source node needs to complete: create a reverse path toward the target node in its routing forwarding table; Update the distance metric from the target node; Send the updated route response packet to the pulse source node along the tree structure.

5. The UAV swarm networked measurement, control and communication system according to claim 1, characterized in that: The pre-allocation plus dynamic negotiation resource management strategy based on the time division multiple access protocol includes: The pre-allocated static time slots are reserved for each node in advance when the frame structure is designed. The remaining time slots are occupied by each node according to the real-time traffic changes through dynamic negotiation. Neighbor interaction, establishing a two-hop neighbor connection relationship; According to the current service load, calculate the number of data time slots N currently required; The number of time slots that need to be applied for or released is calculated based on the number of data time slots N required and the number of time slots currently occupied by the node; The node sends resource request messages and resource feedback messages in the pre-allocated time slots; The node obtains the latest occupied time slot position according to the received resource feedback message.

6. The UAV swarm networked measurement, control and communication system according to claim 5, characterized in that: The formula for calculating the number of data time slots N currently required is as follows: N=totalUnicastResDemandNum+totalBroadcastResDemandNum Among them, totalUnicastResDemandNum represents the total number of unicast traffic demand resources sent by this node to each neighboring node, and totalBroadcastResDemandNum represents the number of broadcast traffic resource demands.

7. The UAV swarm networked measurement, control and communication system according to claim 6, characterized in that: The calculation formula for the total number of unicast traffic resources required by the node to send to neighboring nodes is as follows: totalUnicastResDemandNum=totalUnicastFlow / tbSize current Among them, totalUnicastFlow represents the total unicast flow sent by this node to neighboring nodes, tbSize current Indicates the traffic that can be carried by a single timeslot obtained through AMC under the current link status.

8. The UAV swarm networked measurement, control and communication system according to claim 1, characterized in that: The storage scheduling strategy based on the quality of service level includes: The network layer identifies the service type and labels different types of data packets with corresponding service quality levels; The link layer identifies the service quality level label of the data packet from the upper layer, and stores the data packet in different priority queues and different destination node IDs. The node ID counts from 1, and the broadcast message is stored in the index position 0 of each queue. According to the time slot occupancy result, if the current time slot is the pre-allocated time slot of this node, it will start from the highest priority queue and traverse step by step, send the broadcast message at index position 0, and assemble the frame according to the carrying capacity corresponding to index position 0; if the current time slot is the data time slot dynamically negotiated by this node, first check whether there is still a high-priority broadcast service that needs to be transmitted: if so, give priority to sending the broadcast message at index position 0 of the high-priority queue; if not, it will start from the highest priority queue and traverse step by step, send the unicast message to a destination node, and assemble and disassemble the frame according to the AMC result; If the current time slot is not the sending time slot of this node, the local time slot occupancy table is queried for reception, and the modulation and coding level is adaptively adjusted according to the link measurement result.

9. The UAV swarm networked measurement, control and communication system according to claim 1, characterized in that: The adaptive modulation and coding technology is to adaptively select an appropriate adjustment coding level for transmission and reception according to the current transmission and reception link status, including: The receiving node obtains the receiving power through wireless link measurement; The signal-to-noise ratio (SNR) is calculated by the received power; The signal-to-noise ratio (SNR) can be used to detect the link status between the current sending node, select the appropriate MCS level for sending and receiving, and update the local node to receive the latest MCS level of the sending node; The latest MCS level is carried out during the next neighbor information exchange, so that after receiving the information, the sending node uses the latest MCS level to send it to the local node.

10. A drone swarm networked measurement, control and communication method, characterized in that: The method is implemented based on the UAV swarm networked measurement, control and communication system according to any one of claims 1 to 9, and comprises the following steps: Initially select the control node as the pulse source node of the cross-layer pulse routing protocol; After all nodes are online and time is synchronized, the command node periodically floods pulse messages to establish the minimum loop-free spanning tree from all drone nodes in the entire network to the command node; Each node exchanges control information in the static TDMA time slot pre-allocated to itself. The link layer updates the neighbor connection relationship within two hops and reports it to the network layer regularly. The service flow drives the node to find the path from the node to the destination node as needed. If there is a valid path to the destination node in the local routing table, the data packet is forwarded along the existing path. If there is no path, the packet is forwarded after addressing according to the cross-layer pulse routing protocol; The link layer senses the unicast service traffic size in the node's sending queue in real time, and dynamically occupies and releases time slots based on the pre-allocation and dynamic negotiation resource management strategy based on the time division multiple access protocol; The node queries the locally saved time slot occupancy table. If the current time slot is the sending time slot of the node, the link layer assembles and disassembles the data packet based on the storage scheduling strategy of the service quality level, and sends it to the physical layer to send the data. Other nodes query the locally stored time slot occupancy table for reception, and adaptively adjust the modulation and coding level according to the link measurement results.

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