Cluster head pushing method of satellite navigation-free unmanned aerial vehicle network based on directional communication

Abstract

The invention discloses a cluster head pushing method for a satellite-guided unmanned aerial vehicle-free network based on directional communication, and the method comprises the steps: enabling a slow node to scan an air node at a current wave position in a wave position polling manner, and transmitting a scanning frame; if the air node exists at the current wave position, the air node sends a response frame to the slow node after receiving the scanning frame, and the slow node records the response frame after receiving the response frame; the slow node continues to scan the air node at the next beam position in the beam position polling mode, and a scanning frame is sent; if the air node does not exist at the current beam position, the slow node cannot receive the response frame, continues to scan the air node at the next beam position in the beam position polling mode, and sends a scanning frame; and the low-speed nodes push cluster heads according to recording results of the low-speed nodes until all the wave positions are scanned, and cluster head information is sent to all the air nodes in the form of notification frames. According to the method, cluster head pushing of the unmanned aerial vehicle can be realized under the condition that no satellite navigation unmanned aerial vehicle exists or no satellite navigation unmanned aerial vehicle exists.

Description

Technical Field

[0001] The invention belongs to the technical field of unmanned aerial vehicle self-organizing network communication, and in particular relates to a cluster head recommendation method for a satellite-free unmanned aerial vehicle network based on directional communication. Background Art

[0002] With the continuous advancement and development of drone technology, its application scenarios are no longer limited to a single drone, but are moving towards self-organizing and collaborative self-organizing networks.

[0003] In the prior art, the positioning and control of drones are mainly carried out through base stations or satellite navigation systems. Once the drone can determine the exact coordinates of the target node and perceive its own posture, it can easily determine the position. However, in some special cases, such as when the satellite navigation signal is deliberately interfered and becomes unreliable, or in an environment without navigation signals, the drone cannot be positioned through base stations or satellite navigation systems, making the positioning of the drone unreliable.

[0004] Therefore, in an environment where drones operate in groups, providing a drone networking method that does not rely on satellite navigation systems has become a difficult problem that needs to be overcome in this field. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a cluster head recommendation method for a satellite-free UAV network based on directional communication. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a cluster head recommendation method for a satellite-free unmanned aerial vehicle network based on directional communication, comprising:

[0007] The slow node scans the air node at the current wave position in a wave position polling manner and sends a scan frame;

[0008] If there is an aerial node at the current wave position, the aerial node receives the scan frame and sends a response frame to the slow node. After the slow node receives the response frame, it records it. The slow node continues to scan the aerial node at the next wave position in a wave position polling manner and sends a scan frame.

[0009] If there is no aerial node at the current wave position, the slow node continues to scan the aerial node at the next wave position in a wave position polling manner and sends a scan frame;

[0010] Until all wave positions are scanned, the slow node elects a cluster head based on its recorded results and sends the cluster head information to all air nodes in the form of a notification frame;

[0011] The aerial node performs self-verification to determine whether it is the cluster head.

[0012] Optionally, there are n wave positions, the time slots for the slow node to send scan frames are n, the time slots for receiving response frames are n, and the time slots for sending notification frames are x, where x represents the number of air nodes;

[0013] The time slot for slow nodes to elect cluster heads is 2n+x;

[0014] Each time slot includes a data phase and a protection phase. The data phase is 1.5T and the protection phase is 1T. T = T t +T s +T r , T t =a / b, T s =c / d, T r ≈T t , T t represents the transmission delay, a represents the data length, b represents the transmission rate, T s represents the propagation delay, c represents the maximum distance between the slow node and the aerial node, d represents the electromagnetic propagation speed, T r Indicates the receiving delay.

[0015] Optionally, the scanning frame, the response frame and the notification frame all include a frame header;

[0016] The frame header includes a fixed value of the data frame header, a source node MAC address, a destination node MAC address, a frame type, a subframe type, and a data frame length.

[0017] Optionally, the scan frame, the response frame and the notification frame all include a data field;

[0018] Among them, the data field of the scanning frame includes the cluster number, time slot number, timestamp and CRC check; the data field of the response frame includes the presence or absence of the guide type, the source node longitude, the source node latitude, the source node altitude, the northeast sky speed, the northeast sky acceleration and CRC check; the data field of the notification frame includes the node allocation ID number, the cluster head node ID number, the relative longitude, the relative latitude, the relative altitude and the CRC check.

[0019] Optionally, before scanning in wave position polling mode, it also includes:

[0020] Taking the slow node as the reference point, the aerial area is divided into four areas arranged in an array, and each row and column includes two areas;

[0021] Construct a wave map for the region and define the wave polling order.

[0022] Optionally, construct a wavemap and define the wave polling order, including:

[0023] According to the size of the beam transmitted by the array antenna of the slow node, the maximum range of the coverage wave position in the area and the range of each wave position are determined, and the ranges of adjacent wave positions have overlapping areas;

[0024] Take the inscribed regular hexagon of the range of each wave position, and the regular hexagons corresponding to adjacent wave positions are tangent to each other, determine the number of layers of regular hexagons corresponding to the wave positions within the maximum range of the wave positions covered in the area, and construct a wave position map;

[0025] The regular hexagon corresponding to the central wave position is taken as the starting point of the wave position polling, and the wave position tangent to any side of the regular hexagon corresponding to the central wave position is taken as the second point of the wave position polling, and the wave position polling order is selected in a clockwise or counterclockwise manner.

[0026] Optionally, according to the size of the beam transmitted by the array antenna of the slow node, the maximum range of the coverage beam position in the area and the range of each beam position are determined, including:

[0027] According to the half-wave angle m of the wide beam emitted by the array antenna of the slow node, the radius of the maximum range of the coverage position in the area is determined to be r1, r1 = sin(m);

[0028] According to the half-wave angle n of the narrow beam emitted by the array antenna of the slow node, the radius r2 of the range of each beam position in the area is determined, r2=sin(n).

[0029] Optionally, determining the number of regular hexagonal layers corresponding to the wave position within the maximum range of the wave position covered in the area, and constructing a wave position map, including:

[0030] According to the radius r1 of the maximum range of wave positions covered in the region and the radius r2 of the range of each wave position in the region, the number of layers of regular hexagons corresponding to the wave positions within the maximum range of wave positions covered in the region is calculated, and a wave position map is constructed, whose expression is:

[0031]

[0032] Among them, s represents the number of layers, the center coordinates of the regular hexagon corresponding to the i-th wave position are expressed as (d·sinβ, d·cosβ), and the side length of the i-th virtual hexagon formed by the center line of the regular hexagon corresponding to the i-th wave position is expressed as:

[0033]

[0034] Among them, d and β satisfy the relationship:

[0035]

[0036] Among them, d represents the vertical distance from the center to the edge of the regular hexagon corresponding to the i-th wave position, and β represents the angle between the perpendicular line from the center to the edge of the regular hexagon corresponding to the i-th wave position and the y-axis.

[0037] Optionally, after receiving the response frame, the slow node records the following information:

[0038] After receiving the response frame, the slow node determines the wave position of the aerial node that sent the response frame, and records the deflection angle and pitch angle corresponding to the wave position. The expression is:

[0039]

[0040] Where θ represents the beam deflection angle, represents the wave position elevation angle, x = d·sinβ, y = d·cosβ, x and y represent the center coordinates of the regular hexagon corresponding to the wave position;

[0041] After receiving the response frame, the slow node determines and records the relative distance D between the aerial node that sent the response frame and the slow node, which is expressed as:

[0042] D=(T2-T1)×V c ;

[0043] Among them, T1 represents the time when the air node receives the scanning frame, T2 represents the time when the air node sends the response frame, and V c Represents the speed of electromagnetic propagation.

[0044] Optionally, the slow node elects a cluster head according to its recording result, and sends the cluster head information to all the aerial nodes in the form of a notification frame, including:

[0045] The slow node recommends the aerial node as the cluster head according to the deflection angle and pitch angle corresponding to the wave position of the aerial node and the relative distance between the aerial node and the slow node, according to the preset rules;

[0046] The slow node calculates the longitude and latitude of the cluster head according to its own longitude and latitude, the deflection angle and pitch angle corresponding to the wave position of the aerial node, and the relative distance between the aerial node and the slow node, and sends it to all aerial nodes in the form of a notification frame as the cluster head information.

[0047] Beneficial effects of the present invention:

[0048] The present invention provides a cluster head recommendation method for a satellite-free UAV network based on directional communication. By means of slow nodes scanning aerial nodes in a wave position polling manner and the interaction between slow nodes and aerial nodes, in an environment without satellite navigation, the UAVs can still autonomously recommend cluster heads to achieve self-organization management and communication scheduling within the group. In this way, the autonomy of the system is enhanced, so that the UAV network can continue to operate in a GPS-free environment, and is suitable for complex environments where satellite signals are limited or completely missing.

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a flow chart of a cluster head selection method for a satellite-free unmanned aerial vehicle network based on directional communication provided by an embodiment of the present invention;

[0051] Figure 2 It is a schematic diagram of a wave position polling sequence provided by an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the time slots required for a slow node to elect a cluster head according to an embodiment of the present invention;

[0053] Figure 4 is a schematic diagram of wave position projection provided by an embodiment of the present invention;

[0054] Figure 5 It is a schematic diagram of obtaining the center coordinates of a regular hexagon corresponding to the i-th wave position provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0056] See also Figure 1 and Figure 2 , Figure 1 is a flow chart of a cluster head selection method for a satellite-free unmanned aerial vehicle network based on directional communication provided by an embodiment of the present invention. Figure 2 1 is a schematic diagram of a wave position polling sequence provided by an embodiment of the present invention. The present invention provides a cluster head recommendation method for a satellite-free unmanned aerial vehicle network based on directional communication, comprising:

[0057] S101. The slow node scans the air node at the current wave position in a wave position polling manner and sends a scanning frame.

[0058] Specifically, in this embodiment, n wave positions are set, the slow node sends scan frames in n time slots, receives response frames in n time slots, sends notification frames in x time slots, and x represents the number of air nodes.

[0059] See also Figure 3 , Figure 3 This is a schematic diagram of the time slots required for the slow node to elect a cluster head provided by an embodiment of the present invention. The time slots for the slow node to elect a cluster head are 2n+x. Optionally, the number of aerial nodes is 16.

[0060] Each time slot includes a data phase and a protection phase. The data phase is 1.5T and the protection phase is 1T. T = T t +T s +T r , T t =a / b, T s =c / d, T r ≈T t , T t represents the transmission delay, a represents the data length (bit), b represents the transmission rate (bps), T s represents the propagation delay, c represents the maximum distance between the slow node and the aerial node (m), d represents the electromagnetic propagation speed (3×108m / s), T r Indicates the receiving delay; it should be noted that the data phase allows the sending of scan frames and the receiving of response frames, while the protection phase only allows the receiving of response frames.

[0061] Optionally, the slow node is a ground node or a sea surface node, and the aerial node is a drone.

[0062] In this embodiment, the scanning frame includes a frame header and a data field. The frame header of the scanning frame includes a fixed value of the data frame header (frame_head), a source node MAC address (addr_src), a destination node MAC address (addr_dst), a frame type (frame_type), a subframe type (frame_subtype) and a data frame length (frame_data_len). The data field of the scanning frame includes a cluster number (net_num), a time slot number (slot_num), a timestamp (timeStamp) and a CRC check (CRC).

[0063] S102. If the aerial node exists at the current wave position, the aerial node sends a response frame to the slow node after receiving the scan frame. The slow node receives the response frame and records it. The slow node continues to scan the aerial node at the next wave position in a wave position polling manner and sends a scan frame.

[0064] Specifically, in this embodiment, the response frame includes a frame header and a data field. The frame header of the response frame includes a fixed value of the data frame header (frame_head), a source node MAC address (addr_src), a destination node MAC address (addr_dst), a frame type (frame_type), a subframe type (frame_subtype) and a data frame length (frame_data_len). The data field of the response frame includes whether there is a guide type (type), source node longitude (longitude), source node latitude (latitude), source node altitude (altitude), northeast celestial speed (speed), northeast celestial acceleration (ac_speed) and CRC check (CRC).

[0065] S103: If there is no aerial node at the current wave position, the slow node continues to scan the aerial node at the next wave position in a wave position polling manner and sends a scanning frame.

[0066] It should be noted that when there is no aerial node at the current wave position, the slow node will not receive a response frame within a certain period of time, and will continue to scan the aerial node at the next wave position and send a scan frame.

[0067] S104, until all the wave positions are scanned, the slow node recommends a cluster head according to its recorded results, and sends the cluster head information to all air nodes in the form of a notification frame.

[0068] Specifically, in this embodiment, the notification frame includes a frame header and a data field. The notification frame header includes a data frame header fixed value (frame_head), a source node MAC address (addr_src), a destination node MAC address (addr_dst), a frame type (frame_type), a subframe type (frame_subtype) and a data frame length (frame_data_len). The notification frame data field includes a node allocation ID number (node_id), a cluster head node ID number (head_id), relative longitude (head_id), relative latitude (rela_la), relative altitude (rela_al) and CRC check (CRC).

[0069] S105: The aerial node performs self-verification to determine whether it is the cluster head.

[0070] In summary, the cluster head selection method for a satellite-free UAV network based on directional communication provided by the present invention has the following beneficial effects:

[0071] 1. Enhanced the self-organizing ability of the drone network. By scanning the air nodes in a wave position polling manner through slow nodes, drones can still autonomously elect cluster heads in an environment without satellite navigation, and realize self-organizing management and communication scheduling within the group; thus, the autonomy of the system is enhanced, so that the drone network can continue to operate in a GPS-free environment, which is suitable for complex environments where satellite signals are limited or completely missing.

[0072] 2. Reduce dependence on external navigation systems. In the absence of satellite navigation, this method relies on nodes within the network to recommend cluster heads, reducing dependence on external navigation systems and improving the survival and adaptability of the UAV system in harsh environments, especially for missions in high-interference or hostile areas.

[0073] 3. Improved network stability and robustness. Through the cluster head election method, the network can quickly respond to dynamic changes, such as node movement, failure or loss, and maintain network stability; the reasonable selection of cluster head nodes makes resource allocation more efficient and can effectively reduce communication interruptions caused by node failures or link instability in the network.

[0074] 4. Optimized communication performance. The cluster head election method based on directional networks reduces interference and conflicts within the network by utilizing directional antennas and directional links, and improves the success rate and efficiency of communication. The elected cluster head node can effectively manage the communication within the cluster, reduce resource competition and data conflicts, and thus improve the communication performance of the entire network.

[0075] 5. Save energy consumption and extend network life. The elected cluster head node takes on the management and data aggregation tasks within the cluster, reducing the communication burden of non-cluster head nodes and thus reducing their energy consumption.

[0076] 6. Strong adaptability, suitable for a variety of application scenarios. This method can be applied to a variety of complex drone cluster tasks, such as disaster relief, environmental monitoring, etc., especially suitable for environments without satellite navigation or navigation restrictions; the system can quickly adjust the network structure through cluster head recommendation to adapt to different mission requirements and scene changes.

[0077] In general, this invention improves the autonomy, stability and communication performance of drone networks, and has significant application advantages in complex environments.

[0078] In an optional embodiment of the present invention, please continue to refer to Figure 2 , before scanning in wave position polling mode, it also includes:

[0079] Taking the slow node as the reference point, the aerial area is divided into four areas arranged in an array, and each row and column includes two areas;

[0080] Construct a wave map for the region and define the wave polling order.

[0081] In this embodiment, the wave positions scanned by the slow node are analyzed and designed, the coverage mode is determined, and the parameters such as the number and pointing position of each sub-wave position corresponding to the beam transmitted by the array antenna in the slow node within a given scanning range are calculated.

[0082] The relationship between the communication distance and beam width between the slow node and the aerial node depends on factors such as the communication scheme, antenna type, and channel capacity. Generally speaking, the smaller the beam width, the longer the communication distance, but it also increases the difficulty of signal alignment. Taking various factors into consideration, each node is designed to be equipped with one omnidirectional antenna and one directional antenna, and the beam width of the directional antenna is 15 degrees.

[0083] The wave position map is constructed based on the idea of ​​joint coverage of regular hexagons. Each regular hexagon corresponds to a sub-wave position. These sub-wave positions are numbered, and the wave position deflection angle and pitch angle are calculated. Specifically:

[0084] See also Figure 4 , Figure 4 This is a schematic diagram of the wave position projection provided by an embodiment of the present invention. The array antenna is placed in the XOY plane of the unit sphere coordinate system. The center of the array coincides with the center of the unit sphere. The boundary of the wave position with the maximum range obtained by the array antenna will intersect with a single wave position, and projection is performed to obtain a projection circle, that is, the maximum range of the wave position. The sub-beam of the array antenna is projected to obtain the range of each wave position. Considering the antenna widening effect, the projection is also a circle. The inscribed regular hexagons of the small circles corresponding to each wave position are jointly covered. The central wave position is No. 1, and the wave positions above it are numbered. Each wave position is marked layer by layer counterclockwise, as shown in Figure 2. Therefore, the beam coverage problem in the three-dimensional space is converted into a two-dimensional plane using the projected small circle corresponding to the wave position to cover the projected large circle corresponding to the wide beam.

[0085] In an optional embodiment of the present invention, constructing a wave position map and defining a wave position polling order include:

[0086] According to the size of the beam transmitted by the array antenna of the slow node, the maximum range of the coverage wave position in the area and the range of each wave position are determined, and the ranges of adjacent wave positions have overlapping areas;

[0087] Take the inscribed regular hexagon of the range of each wave position, and the regular hexagons corresponding to adjacent wave positions are tangent to each other, determine the number of layers of regular hexagons corresponding to the wave positions within the maximum range of the wave positions covered in the area, and construct a wave position map;

[0088] The regular hexagon corresponding to the central wave position is taken as the starting point of the wave position polling, and the wave position tangent to any side of the regular hexagon corresponding to the central wave position is taken as the second point of the wave position polling, and the wave position polling order is selected in a clockwise or counterclockwise manner.

[0089] In an optional embodiment of the present invention, the maximum range of coverage beam positions in the area and the range of each beam position are determined according to the size of the beam transmitted by the array antenna of the slow node, including:

[0090] According to the half-wave angle m of the wide beam emitted by the array antenna of the slow node, the radius of the maximum range of the coverage position in the area is determined to be r1, r1 = sin(m);

[0091] According to the half-wave angle n of the narrow beam emitted by the array antenna of the slow node, the radius r2 of the range of each beam position in the area is determined, r2=sin(n).

[0092] In an optional embodiment of the present invention, determining the number of regular hexagonal layers corresponding to wave positions within a maximum range of wave positions covered in a region, and constructing a wave position map includes:

[0093] According to the radius r1 of the maximum range of wave positions covered in the region and the radius r2 of the range of each wave position in the region, the number of layers of regular hexagons corresponding to the wave positions within the maximum range of wave positions covered in the region is calculated, and a wave position map is constructed, whose expression is:

[0094]

[0095] Where s represents the number of layers, see Figure 5 , Figure 5 : is a schematic diagram of obtaining the center coordinates of the regular hexagon corresponding to the i-th wave position provided by an embodiment of the present invention. The center coordinates of the regular hexagon corresponding to the i-th wave position are expressed as (d·sinβ, d·cosβ). The side length of the i-th virtual hexagon formed by the center connecting line of the regular hexagon corresponding to the i-th wave position is expressed as:

[0096]

[0097] Among them, d and β satisfy the relationship:

[0098]

[0099] Wherein, d represents the vertical distance from the center to the edge of the regular hexagon corresponding to the i-th wave position, β represents the angle between the perpendicular line from the center to the edge of the regular hexagon corresponding to the i-th wave position and the y-axis, and the y-axis represents the y-axis in the geodetic coordinate system.

[0100] In an optional embodiment of the present invention, after receiving the response frame, the slow node records it, including:

[0101] After receiving the response frame, the slow node determines the wave position of the aerial node that sent the response frame, and records the deflection angle and pitch angle corresponding to the wave position. The expression is:

[0102]

[0103] Where θ represents the beam deflection angle, represents the wave position pitch angle, x=dvsinβ, y=d·cosβ, x and y represent the center coordinates of the regular hexagon corresponding to the wave position; it should be noted that the deflection angle and pitch angle of the wave position can be obtained according to the positivity of x and y.

[0104] After receiving the response frame, the slow node determines and records the relative distance D between the aerial node that sent the response frame and the slow node, which is expressed as:

[0105] D=(T2-T1)×V c ;

[0106] Among them, T1 represents the time when the air node receives the scanning frame, T2 represents the time when the air node sends the response frame, and V c Represents the speed of electromagnetic propagation.

[0107] In an optional embodiment of the present invention, the slow node elects a cluster head according to its recording result, and sends the cluster head information to all air nodes in the form of a notification frame, including:

[0108] The slow node recommends the aerial node as the cluster head according to the deflection angle and pitch angle corresponding to the wave position of the aerial node and the relative distance between the aerial node and the slow node, according to the preset rules;

[0109] The slow node calculates the longitude and latitude of the cluster head according to its own longitude and latitude, the deflection angle and pitch angle corresponding to the wave position of the aerial node, and the relative distance between the aerial node and the slow node, and sends it to all aerial nodes in the form of a notification frame as the cluster head information.

[0110] In an optional embodiment of the present invention, a simulation test is performed on the above wave position design, such as Figure 4 As shown in the figure, combined with the wave position area to be scanned and the coverage method, the coverage effect of the 1 / 4 spherical shell area is obtained. The scanning node is located at the center of the spherical shell. According to the simulation calculation, the number of wave positions scanned for 1 / 4 sphere is 61, and the entire spherical surface coverage requires 244 wave positions, and 1 / 4 sphere is one area. It can be concluded that for a ground node, 122 wave positions are required to cover the 0 to 60° area with itself as the center.

[0111] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant is intended to cover non-exclusive inclusion, so that the article or device including a series of elements includes not only those elements, but also other elements that are not explicitly listed. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the article or device including the elements. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The orientation or position relationship indicated by "up", "down", "left", "right", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0112] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0113] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A cluster head selection method for a satellite-free UAV network based on directional communication, characterized in that: include: The slow node scans the air node at the current wave position in a wave position polling manner and sends a scan frame; If the aerial node exists at the current wave position, the aerial node sends a response frame to the slow node after receiving the scanning frame, and the slow node receives the response frame and records it; the slow node continues to scan the aerial node at the next wave position in a wave position polling manner and sends a scanning frame; If the aerial node does not exist at the current wave position, the slow node continues to scan the aerial node at the next wave position in a wave position polling manner and sends a scanning frame; Until all the wave positions are scanned, the slow node elects a cluster head according to its recorded results, and sends the cluster head information to all the aerial nodes in the form of a notification frame; The aerial node performs self-verification to determine whether it is the cluster head.

2. The cluster head selection method of the satellite-free UAV network based on directional communication according to claim 1 is characterized in that: The number of the wave positions is n, the number of time slots for the slow node to send a scan frame is n, the number of time slots for receiving a response frame is n, and the number of time slots for sending a notification frame is x, where x represents the number of the aerial nodes; The time slot for the slow node to elect a cluster head is 2n+x; Each time slot includes a data phase and a protection phase, the data phase is 1.5T, the protection phase is 1T, T=T t +T s +T r , T t =a / b, T s =c / d, T r ≈T t , T t represents the transmission delay, a represents the data length, b represents the transmission rate, T s represents the propagation delay, c represents the maximum distance between the slow node and the aerial node, d represents the electromagnetic propagation speed, T r Indicates the receiving delay.

3. The cluster head selection method of the satellite-free UAV network based on directional communication according to claim 1 is characterized in that: The scanning frame, the response frame and the notification frame all include a frame header; The frame header includes a fixed value of a data frame header, a source node MAC address, a destination node MAC address, a frame type, a subframe type and a data frame length.

4. The cluster head selection method of the satellite-free UAV network based on directional communication according to claim 1 is characterized in that: The scanning frame, the response frame and the notification frame all include a data field; Among them, the data field of the scanning frame includes the cluster number, time slot number, timestamp and CRC check; the data field of the response frame includes the presence or absence of the guide type, source node longitude, source node latitude, source node altitude, northeast sky speed, northeast sky acceleration and CRC check; the data field of the notification frame includes the node allocation ID number, cluster head node ID number, relative longitude, relative latitude, relative altitude and CRC check.

5. The cluster head selection method of the satellite-free UAV network based on directional communication according to claim 1 is characterized in that: Before scanning in wave position polling mode, it also includes: Taking the slow node as a reference point, the aerial area is divided into four areas arranged in an array, and each row and each column includes two areas; For the area, a wave map is constructed and a wave polling sequence is defined.

6. The cluster head selection method of the satellite-free UAV network based on directional communication according to claim 5 is characterized in that: The construction of the wave map and the definition of the wave polling order include: Determine the maximum range of the coverage wave position in the area and the range of each wave position according to the size of the beam transmitted by the array antenna of the slow node, and the range of adjacent wave positions has an overlapping area; Take the inscribed regular hexagon of the range of each wave position, and the regular hexagons corresponding to adjacent wave positions are tangent to each other, determine the number of layers of regular hexagons corresponding to the wave positions within the maximum range of the wave positions covered in the area, and construct a wave position map; The regular hexagon corresponding to the central wave position is taken as the starting point of the wave position polling, and the wave position tangent to any side of the regular hexagon corresponding to the central wave position is taken as the second point of the wave position polling, and the wave position polling order is selected in a clockwise or counterclockwise manner.

7. The cluster head selection method of the satellite-free UAV network based on directional communication according to claim 6 is characterized in that: According to the size of the beam transmitted by the array antenna of the slow node, the maximum range of the coverage beam position in the area and the range of each beam position are determined, including: According to the half-wave angle m of the wide beam emitted by the array antenna of the slow node, the radius of the maximum range of the coverage position in the area is determined to be r1, r1=sin(m); According to the half-wave angle n of the narrow beam emitted by the array antenna of the slow node, the radius r2 of the range of each beam position in the area is determined, r2=sin(n).

8. The cluster head selection method of the satellite-free UAV network based on directional communication according to claim 7 is characterized in that: Determine the number of regular hexagonal layers corresponding to the wave position within the maximum range of the wave position covered in the area, and construct a wave position map, including: According to the radius r1 of the maximum range of wave positions covered in the region and the radius r2 of the range of each wave position in the region, the number of layers of regular hexagons corresponding to the wave positions in the maximum range of wave positions covered in the region is calculated, and a wave position map is constructed, and its expression is: Among them, s represents the number of layers, the center coordinates of the regular hexagon corresponding to the i-th wave position are expressed as (d·sinβ, d·cosβ), and the side length of the i-th virtual hexagon formed by the center line of the regular hexagon corresponding to the i-th wave position is expressed as: Among them, d and β satisfy the relationship: Among them, d represents the vertical distance from the center to the edge of the regular hexagon corresponding to the i-th wave position, and β represents the angle between the perpendicular line from the center to the edge of the regular hexagon corresponding to the i-th wave position and the y-axis.

9. The cluster head selection method of the satellite-free UAV network based on directional communication according to claim 8 is characterized in that: After receiving the response frame, the slow node records the response frame, including: After receiving the response frame, the slow node determines the wave position of the aerial node that sent the response frame, and records the deflection angle and pitch angle corresponding to the wave position, which are expressed as follows: Where θ represents the beam deflection angle, represents the wave position pitch angle, x = d·sinβ, y = d·cosβ, x and y represent the center coordinates of the regular hexagon corresponding to the wave position; After receiving the response frame, the slow node determines and records the relative distance D between the aerial node that sends the response frame and the slow node, which is expressed as: D=(T2-T1)×V c ; Among them, T1 represents the time when the air node receives the scanning frame, T2 represents the time when the air node sends the response frame, and V c Represents the speed of electromagnetic propagation.

10. The cluster head selection method of the satellite-free UAV network based on directional communication according to claim 9 is characterized in that: The slow node elects a cluster head according to its recording result, and sends the cluster head information to all the aerial nodes in the form of a notification frame, including: The slow node recommends the aerial node as the cluster head according to the deflection angle and pitch angle corresponding to the wave position where the aerial node is located, and the relative distance between the aerial node and the slow node, according to the preset rules; The slow node calculates the longitude and latitude of the cluster head based on its own longitude and latitude, the deflection angle and pitch angle corresponding to the wave position of the aerial node, and the relative distance between the aerial node and the slow node, and sends it to all the aerial nodes in the form of a notification frame as cluster head information.

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