CN116170860B - Ad hoc network method for antenna ad hoc network system - Google Patents
Ad hoc network method for antenna ad hoc network system Download PDFInfo
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Abstract
The invention relates to an ad hoc network method for an antenna ad hoc network system, which comprises the following steps: dividing unmanned aerial vehicles with known ID numbers in a gateway scene into a plurality of formations, wherein each formation represents a cluster, one unmanned aerial vehicle in each cluster is used as a central node to represent a cluster head, other unmanned aerial vehicles are used as common nodes, inter-cluster networking is carried out among the cluster heads of the plurality of clusters, and intra-cluster networking is carried out in each cluster; when a common node which cannot access the network in the network initialization process or a common node which is re-added after the network is removed or a new node which is temporarily added exist, actively transmitting a network access application to be added into the network in an active network access mode; and when the node needs to be network-removed, the node performs active network-removal or passive network-removal according to the self requirement of the node. According to the wireless ad hoc network based on the multi-beam directional antenna, azimuth angles and pitch angles are covered by using multiple antennae in the whole airspace, and the communication efficiency can be improved and the probability of capturing signals by an enemy can be reduced by using the directional antenna with high gain and narrow beam.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to an ad hoc network method for an antenna ad hoc network system.
Background
The unmanned aerial vehicle data link networking is forward developed in the directions of safety, miniaturization, high speed, networking, universalization and standardization, and the unmanned aerial vehicle bee colony dynamic self-organizing network has a very flexible network structure, strong destruction resistance and high application value in military; the self-organizing network technology is applied to real-time communication among unmanned aerial vehicles, the flexibility and the survivability of the network are ensured, and meanwhile, the real-time transmission of time sensitivity information can be realized, and real-time information sharing such as control, command, battlefield situation and the like is provided for a battle system, so that the combined battle capability of the army is enhanced.
However, the current common ad hoc network method is generally based on omni-directional antenna design, and is divided into a request frame time slot, a response frame time slot and a dynamic data frame time slot, and node time slots in the whole network are divided based on time division multiple access, so that the defects of high network control overhead, weak processing capacity and the like exist, and centralized network management and control are difficult to implement. While using an omni-directional antenna can easily be intercepted by an adversary to expose the target.
It should be noted that the information disclosed in the above background section is only for enhancing understanding of the background of the present disclosure and thus may include information that does not constitute prior art known to those of ordinary skill in the art.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides an ad hoc network method for an antenna ad hoc network system, and solves the problems of the existing ad hoc network method.
The aim of the invention is achieved by the following technical scheme: an ad hoc network method for an antenna ad hoc network system, the ad hoc network method comprising:
s1, initializing a network: dividing unmanned aerial vehicles with known ID numbers in a gateway scene into a plurality of formations, wherein each formation represents a cluster, one unmanned aerial vehicle in each cluster is used as a central node to represent a cluster head, other unmanned aerial vehicles are used as common nodes, the common nodes in the clusters can reach the cluster heads of the central node in one hop, the cluster heads of the plurality of clusters are subjected to inter-cluster networking, namely secondary network networking, and each cluster is subjected to intra-cluster networking, namely primary network networking;
s2, the node is accessed into the network: when a common node which cannot access the network in the network initialization process or a common node which is re-added after the network is removed or a new node which is temporarily added exist, actively transmitting a network access application to be added into the network in an active network access mode;
s3, the node moves back to the network: and when the node needs to be network-removed, the node performs active network-removal or passive network-removal according to the self requirement of the node.
The inter-cluster networking comprises the following contents:
a1, each formation selects one formation cluster head node for inter-cluster networking through calculation, and other nodes in the formation are common nodes in the cluster;
a2, after power-on, the cluster head performs repeated scanning directional reception on all time slots until network initialization is started after a network access message is received;
a3, according to the instruction of the ground control command center, the ground control center node starts to initiate an initialization network access flow of the secondary network, and the antenna scans all directions in each beam direction in sequence to send HELLO packets in a directional mode;
a4, after the cluster heads receive HELLO packets sent by the ground control center node, adjusting a local clock according to time information of the received HELLO packets to complete coarse synchronization, and after receiving RTT information from the second-level network one-hop cluster head node, the ground control center replies RTT information in sequence in corresponding time slots, and immediately replies RTT_REP information, and then performs fine synchronization to realize complete synchronization of the second-level network one-hop cluster head node and the ground control center node;
a5, after the ground control center discovers at least one second-level network one-hop node, executing the subsequent step, otherwise, returning to the step A1 to carry out second-level network networking again;
a6, the ground control center sequentially sends networking instructions to the first-hop cluster head nodes of the second-level network which are already connected according to the ID sequence of the network connection nodes, the cluster head nodes start neighbor discovery of the second-hop cluster head nodes, the first-hop cluster head nodes finish fine synchronization after discovering the second-hop cluster head nodes, and the first-hop cluster head nodes report discovered information of the two-hop nodes to the ground control center node in a reporting time slot; after a certain hop cluster head node discovers a two hop cluster head node and completes reporting to a ground control center node in a precise synchronization way, the next hop cluster head node begins broadcasting own HELLO (high efficiency uplink packet) packets again, begins neighbor discovery of the two hop cluster head nodes, and discards the HELLO packets according to ID (identity) numbers when the certain hop cluster head node receives the HELLO packets of other hop cluster head nodes; and the three-hop and four-hop cluster head networking is completed in the same way;
and A7, after the information of the secondary network cluster head is all collected to the ground control center, the ground control center directionally transmits the secondary network topology information to the secondary network cluster head node according to the secondary network whole network topology information.
The intra-cluster networking comprises the following contents:
b1, when control information is sent to a cluster head node by a ground control center, the cluster head node firstly broadcasts HELLO information packets, then common nodes in the cluster sequentially send RTT information to the cluster head node according to ID numbers after receiving the information packets, and the cluster head node immediately replies RTT_REP information after receiving the RTT information, so that networking of the common nodes in the cluster is completed; the cluster head nodes report the topology information in each formation to a ground control center and send the topology information to common nodes in the cluster in sequence according to the formation ID number sequence;
and B2, after the networking in the cluster is completed, all topology information of the whole network is collected to a ground control center, the ground control center broadcasts the transmitting information to nodes in the whole network hop by hop, and the nodes in the whole network upload data to the ground control center hop by hop.
The node network access specifically comprises the following contents:
the network access node flies to a designated area according to a specific geographical range which is updated in real time and is given by a ground control center, continuously transmits network access application information comprising network access node position information through omni-directional scanning of a networking/network access spreading code after reaching the designated area, and then the network access node is converted into an omni-directional scanning receiving state; when the HELLO message sent by the in-network node is received, the network access RTT message is sent to the in-network node immediately, and after the network access node receives the RTT_REP message of the in-network node, the network access node achieves time fine synchronization to complete network access, and the network is participated in normal communication in the next frame.
The network access discovery node adopts omni-directional scanning of a networking/network access spreading code to receive network access application information, when the network access application information is received, the network access node information is declared to the cluster head node in the cluster by a declaration time slot in the cluster, the cluster head node judges whether to allow the network access according to the network access node information, when the network access permission information of the cluster head node is received, the network access node sends HELLO information in a designated time slot, and after the network access RTT information of the network access node is received, the RTT_REP information is immediately replied.
The active logout specifically comprises the following contents:
active network exit of the cluster member nodes: the method comprises the steps that a cluster head node allows the cluster head node to adjust a time frame structure according to the number of new cluster members after the cluster head node performs network withdrawal, a central control time slot in the cluster is adopted, the cluster head node transmits network withdrawal confirmation information to the node, and notifies all other cluster head nodes of the network withdrawal information of the node, and the node completes active network withdrawal;
cluster head nodes actively exit the network: the method comprises the steps that in-cluster control time slots send replacement cluster head node information to replacement cluster head nodes, new cluster head node information is announced to in-cluster member nodes, in the next time frame, the cluster head nodes report the new cluster head node information to a ground control center, in-cluster control time slots, the new cluster head nodes receive in-cluster member node application information, time slot allocation is completed, and up to this point, the cluster head nodes complete active network withdrawal.
The passive network-returning specifically comprises the following contents:
passive network exit of cluster member nodes: if the cluster head node declares a time slot in a cluster of two continuous time frames and does not receive the declaration information of the node, the cluster head node considers the node to exit the network, the cluster head node adjusts the time frame structure according to the number of members in a new cluster, deletes the network exit node in a topology database in the next time slot, the new time slot table does not contain the table item of the network exit node any more, and sends the network exit information of the node to other member nodes in the cluster;
cluster head nodes passively exit the network: if other common nodes in the two time frames do not receive the cluster head node reply message, the standby cluster head node is updated to a new cluster head node in the next time frame, the replacement of the cluster head node is completed, the network-quitting node is deleted in the topology database, and the new time slot table does not contain the table item of the network-quitting node any more so as to maintain the normal operation of the network.
The coarse synchronization includes: the ground control center starts network initialization, sends HELLO packets containing time information, and adjusts a local clock according to the time information after cluster head nodes in one hop of the secondary network receive the HELLO packets, so as to complete coarse synchronization in the range of one hop.
The fine synchronization includes: each cluster head sends RTT information in a corresponding time slot and records time T1, the ground control center receives the RTT information and records arrival time T2, and sends corresponding RTT_REP information and records time T3 according to cluster head position information contained in the RTT, each cluster head receives the RTT_REP information and records time T4, a clock adjustment value delta T is obtained according to a synchronization principle formula, each cluster head adjusts a local clock, and fine synchronization within a one-hop range is completed.
The invention has the following advantages: an ad hoc network method for an antenna ad hoc network system is based on wireless ad hoc network of multi-beam directional antennas, azimuth angle and pitch angle coverage is carried out by using multiple antennas in the whole airspace, and communication efficiency can be improved and the probability of capturing signals by enemies can be reduced by using the directional antennas with high gain and narrow beams. In the time frame structure, a hierarchical structure is adopted, time division multiple access, code division multiple access and space division multiplexing are combined, so that the time slot utilization rate is improved, the throughput rate is high, the anti-interference capability and the anti-destruction capability are strong, and the method has high application value in military.
Drawings
FIG. 1 is a flow chart of network initialization networking of the present invention;
FIG. 2 is a schematic diagram of a cluster head node one-hop coarse synchronization;
FIG. 3 is a schematic diagram of cluster head node one-hop fine synchronization;
FIG. 4 is a schematic diagram of cluster head node one-hop node two-hop neighbor discovery;
FIG. 5 is a schematic diagram of synchronization of common nodes in a two-hop cluster;
FIG. 6 is a schematic diagram of progressive network delivery and reporting;
FIG. 7 is a schematic diagram of neighbor discovery;
FIG. 8 is a schematic diagram of a generic node network access;
FIG. 9 is a system synchronization diagram;
fig. 10 is a schematic diagram of the coarse synchronization and the fine synchronization.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Accordingly, the following detailed description of the embodiments of the present application, provided in connection with the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to be within the scope of the present application. The invention is further described below with reference to the accompanying drawings.
In the scene of the invention, 12 unmanned aerial vehicles and a ground control center are combined, the maximum node hop count is supported to be 4 hops, and the communication mode is single-frequency point and dynamic time division multiplexing. 12. The unmanned aerial vehicle is divided into 3 formations (clusters) which can be dynamically changed. Each cluster is internally provided with an intra-cluster center node (cluster head), namely a node participating in the secondary networking, each formation is internally provided with 3 (variable) primary intra-cluster common nodes, and the primary intra-cluster networking common nodes and the cluster heads can reach one hop. Firstly, the ID of 12 unmanned aerial vehicles is known, at the initial stage of networking, a ground control center firstly needs to know the ID number of a second-level networking node cluster head in a network, and inside a first-level network cluster, the second-level networking node cluster head also needs to know the ID number of a first-level networking node in the cluster, and relates to an ad hoc network method for an antenna ad hoc network system, which specifically comprises the following steps:
1. network initialization:
as shown in fig. 1, it includes an inter-cluster networking (secondary networking) and an intra-cluster networking (primary networking), wherein the inter-cluster networking (secondary networking) includes:
1) And each formation selects one formation cluster head node (a secondary networking node) for inter-cluster networking through calculation, and the rest nodes in the formation are common nodes in the cluster.
2) After power-on, the cluster head performs repeated scanning directional reception on all time slots until a network access message is received, and network initialization is started.
3) According to the instruction of the ground control command center, the ground control center node starts to initiate an initialization network access flow of the secondary network, and the antenna scans and transmits HELLO packets in a directional mode in each beam direction in sequence.
4) After the cluster head receives the HELLO packet sent by the ground control center node, the cluster head node considers itself as a second-level network one-hop node, and adjusts a local clock according to the time information of the received HELLO packet to complete coarse synchronization, and the RTT information is recovered to the ground control center node in turn in the corresponding time slot because each cluster head ID number is known. The ground control center can immediately reply RTT_REP information after receiving RTT information from the second-level network one-hop cluster head node, and then the second-level network one-hop cluster head node performs fine synchronization after receiving the RTT_REP information. The one-hop cluster head node of the secondary network is completely synchronous with the ground control center node.
5) The ground control center at least finds one second-level network one-hop node to continue the subsequent steps, otherwise, the second-level network networking process can only be started again.
6) 2-4, after at least one second-level network first-hop cluster head node is found, starting a second-level network second-hop networking process, and sequentially sending networking instructions to the second-level network first-hop cluster head nodes which are already networked by a ground control center according to the ID number sequence of the network-accessed nodes, wherein the cluster head nodes start second-hop cluster head node neighbor discovery, and the neighbor discovery process is basically the same as the process of the ground control center for discovering the second-level network first-hop cluster head nodes. After the first-hop cluster head sends out the two-hop cluster head nodes, the two-hop cluster head nodes finish the fine synchronization, and the first-hop cluster head node has a reporting time slot and reports the discovered two-hop node information to the ground control center node. After a certain hop cluster head node discovers a two-hop cluster head node and completes reporting to a ground control center node in a precise synchronization way, the next hop cluster head node starts broadcasting own HELLO (high efficiency uplink packet) packets again and starts neighbor discovery of the two-hop cluster head node. When one hop cluster head node receives HELLO packets of other one hop cluster head nodes, discarding the HELLO packets according to the ID number. The subsequent three-hop and four-hop cluster head networking process can be completed according to the same method.
7) And the information of the secondary network cluster heads is all collected to a ground control center. The ground control center transmits the secondary network topology information to the secondary network cluster head node in a directional manner according to the secondary network whole network topology information; the ground control center can also calculate and select the secondary network cluster head and the standby cluster head according to a certain clustering algorithm.
Further, the intra-cluster networking (primary network networking) specifically includes:
1) As shown in fig. 5, black circles in the diagram indicate cluster head nodes, and circles without filling color indicate common nodes in the clusters, after the networking is completed among the clusters, the networking in the clusters is started, and because the topology of the secondary network among the clusters is known, the networking in the clusters is sequentially performed according to the formation ID number sequence. Because the cluster head can reach the cluster head node by one hop, when the control information is sent to the cluster head node by the ground control center, the cluster head node firstly broadcasts HELLO information packets, then common nodes in the cluster sequentially send RTT information to the cluster head node according to ID numbers after receiving the information packets, and the cluster head node immediately replies RTT_REP information after receiving the RTT information, so that the networking of the common nodes in the cluster is completed. After the networking in the cluster is completed, the cluster head nodes report the topology information in the respective formation to a ground control center and issue the topology information to common nodes in the cluster in sequence according to the formation ID number.
2) As shown in fig. 6, black circles in the graph represent cluster head nodes, non-filled circles represent common nodes in the clusters, after the inter-cluster networking is completed, topology information of the whole network is all collected to a ground control center node, and the ground control center broadcasts the transmitting information to the nodes in the whole network hop by hop, and the nodes in the whole network upload data to the ground control center hop by hop.
Further, all nodes, when performing neighbor node discovery, will already include the network node ID number in the HELLO packet when the node broadcasts the HELLO packet. Therefore, when the node which is not connected with the network receives the HELLO packet, the ID number of the node which is connected with the network can be known, and the sequence of the node which is not connected with the network can be known. The nodes which are not connected to the network can reply with RTT and receive rtt_rep in the corresponding reserved time slot according to the deduced sequence. With the increasing number of nodes that have entered the network, the number of time slots required to perform the discovery process of a neighbor node per time is continually reduced.
As shown in fig. 7, if the ID number of the node in the cluster is 1-5, the ID number of the cluster head is 1, the ID number of the node which is already in the network is 2, the ID numbers of the nodes which are not in the network are 3, 4 and 5, and the information of the HELLO packet sent by the cluster head 1 contains the information of the node 2 which is already in the network, so that the nodes 3, 4 and 5 can determine the time slot sequence in RTT reply if they receive the HELLO packet. Suppose nodes 3 and 5 are neighbor discovered and node 4 is not discovered.
2. The node is connected to the network: there are three situations for nodes in the network that need to be networked: the common node which can not access the network in the network initialization process and the common node which can exit the network due to the rapid movement in the normal operation process of the network are added again to the network, and new nodes which are temporarily added after the network initialization are added again; the invention adopts an active network access mode, wherein the active network access means that a new node actively transmits a network access application message, and once the node in the network receives the network access application message, the node reports the new node discovery message to the cluster head node. After the cluster head node allows the new node to join, the node in the designated network can complete time synchronization with the network-access node in the designated time slot and join the network.
And controlling time slots among clusters in the TDMA time frame, wherein non-gateway nodes in the clusters are in an idle state. At this time, all non-gateway nodes in the cluster adopt networking/network-access spread spectrum codes to perform omni-directional scanning to receive network access application messages. Because the inter-cluster control time slot is shorter, all network access application messages cannot be received, each cluster selects one network access discovery node by the cluster head node, and when the cluster head node performs dynamic time slot allocation, the network access discovery node is in an omni-directional scanning receiving state to receive the network access application messages within a sufficient time at the tail end of the dynamic time slot of each frame.
1) And (3) network access node flow:
as shown in fig. 8, the network access node flies to a designated area according to a real-time updated specific geographical range of the formation, which is given by the ground control center, and after the network access node reaches a designated airspace, the network access application message is sent by using omni-directional scanning of the networking/network access spreading code, and the network access application message contains the position information of the network access node. Because the network access node is not synchronous with the whole network time, the network access node needs to continuously send for a period of time, and the network access application message is ensured to be received by the nodes in the network. Then, the network node goes into an omni-directional scanning receiving state. When the HELLO message sent by the in-network node is received, the network access RTT message is sent to the in-network node immediately, and after the network access node receives the RTT_REP message of the in-network node, the network access node achieves time fine synchronization to complete network access, and the network is participated in normal communication in the next frame.
2) And (3) in-network node flow:
the network access discovery node receives the network access application message by adopting omni-directional scanning of the networking/network access spreading codes. When the network access request message is received, the network access node information is declared to the cluster head node of the cluster in the intra-cluster declaration time slot, and the cluster head node judges whether to allow the network access according to the network access node information. When receiving the network access permission information of the cluster head node, the network access node sends HELLO information in a designated time slot, and immediately replies RTT_REP information after receiving the network access RTT information of the network access node.
3. The nodes are off-line: the node network-exiting can be divided into node active network-exiting and node passive network-exiting. The node actively quits the network refers to the fact that the node cannot stay in the original cluster for objective reasons, and actively applies for quitting the network. The passive network exit of the node is caused by the factors of destroyed node, fault and the like, and other nodes in the network cannot be informed to be forced to exit the network.
1) Node active network exit: the method comprises the steps of actively removing the network from the member nodes in the cluster and actively removing the network from the cluster head nodes.
Wherein, the cluster member node actively moves back to the network: and the cluster head node allows the cluster head node to withdraw from the network and adjusts the time frame structure according to the number of new cluster members after the cluster head node allows the cluster head node to withdraw from the network. And controlling a time slot in the cluster center, transmitting network-quitting confirmation information to the node by the cluster head node, informing the network-quitting information of the node to all other cluster member nodes, and completing active network-quitting by the node.
Cluster head nodes actively exit the network: cluster head nodes also act as gateways due to their importance. When the cluster head node is to be network-removed, the control time slot in the cluster sends the information of the alternative cluster head node to the alternative cluster head node, and the new cluster head node information is announced to the member nodes in the cluster. And in the next time frame inter-cluster control time slot, the cluster head node reports the new cluster head node information to the ground control center. And controlling time slots in the clusters, and receiving the application information of the members in the clusters by the new cluster head nodes to finish the functions of time slot allocation and the like. Thus, the cluster head node completes active network withdrawal.
2) Passive network withdrawal of nodes: the method comprises passive network withdrawal of the cluster member nodes and passive network withdrawal of the cluster head nodes.
Passive network exit of cluster member nodes: the cluster head node considers that the node exits the network if the cluster head node does not receive the declaration information of the node in the cluster declaration time slots of two continuous time frames. The cluster head node adjusts the time frame structure according to the number of the members in the new cluster, deletes the network-quitting node in the topology database in the next time slot, the new time slot table no longer contains the table item of the network-quitting node, and sends the network-quitting information of the node to other member nodes in the cluster.
Cluster head nodes passively exit the network: if other common nodes in the two time frames do not receive the cluster head node reply message, the standby cluster head node is updated to a new cluster head node in the next time frame, the replacement of the cluster head node is completed, the network-quitting node is deleted in the topology database, and the new time slot table does not contain the table item of the network-quitting node any more so as to maintain the normal operation of the network.
Further, the nodes synchronize: the purpose of network clock synchronization is to make the local clocks identical between the nodes that need synchronization,
each node in the network is configured with a hardware crystal oscillator that is used to control the local time of the node itself. The error exists between different crystal oscillators, and the same crystal oscillator can generate frequency offset along with the time under different physical conditions, so that the local time of the node is synchronized once only at one moment, and the local time of the node is required to be continuously synchronized at regular intervals. In this way, clock synchronization between nodes is maintained for a long time by constantly and repeatedly adjusting the local clock of the nodes to be synchronized.
The basic principle of system synchronization is: synchronization between each node and the node at the upper level in the system is realized by a periodical bidirectional message exchange mode. The synchronous information exchange is periodically carried out between the master node clock and the slave node clock, and meanwhile, the sending and receiving time of the information packet is accurately captured and the time stamp information is added. Once the slave node clock receives the synchronous information packet, the time stamp information can be extracted from the synchronous information packet, and the time difference between the slave node clock and the master node clock and the transmission delay in the network are calculated according to the time stamp information, so that the local node clock is calibrated, and the synchronization of all nodes and the standard clock node is realized.
As shown in fig. 9, clock synchronization of the node to be synchronized 1 is achieved by means of bidirectional message exchange between the node to be synchronized 1 and the time reference node 2. In the figure, T1: the time when the node 1 to be synchronized sends RTT message (the node 1 to be synchronized records); t2: the time when the RTT message is received by the time reference node 2 (time reference node 2 records); t3: the time reference node 2 replies with the rtt_rep message (time reference node 2 records); t4: the time when the rtt_rep message is received by the node 1 to be synchronized (the record of the node 1 to be synchronized); d1: the node 1 to be synchronized transmits the RTT message to the propagation delay of the time reference node 2; d2: the time reference node 2 replies the propagation delay from the RTT_REP message to the node 1 to be synchronized; Δt: clock offset values of the node 1 to be synchronized and the time reference node 2.
The specific response mechanism is as follows:
(1) And the slave node sends RTT message request synchronization to the master node and records the sending time T1. After receiving the message, the master node records the receiving time T2;
(2) The master node sends an RTT-ACK message to the slave node, and is used for initiating calculation of reverse transmission delay, recording the sending time T3 and recording the time T2 and the time T3 in the RTT-ACK message;
(3) After receiving the message from the node, the receiving time T4 is recorded. Thus, the slave node has four time stamps of T1 to T4, and thus the clock skew Δt between the master and slave nodes can be calculated.
The equation is as follows: t2=t1+d1+ +Δ T, T4 =t3+d2- Δt, since D1 is substantially equal to D2, then from the above formula, it can be solved: deltaT= ((T2-T1) - (T4-T3))/2.
As shown in fig. 10, the overall system synchronization is divided into two phases, inter-cluster synchronization and intra-cluster synchronization. The principle followed by inter-cluster synchronization and intra-cluster synchronization is as follows: the cluster heads are firstly synchronized, the cluster head synchronization is carried out according to the sequential hop-by-hop sequence, and then the common nodes in the cluster are synchronized with the cluster head nodes.
The coarse synchronization in the inter-cluster synchronization is as follows: coarse synchronization occurs during the network initialization phase and during the node network entry phase. The ground control center starts network initialization, sends HELLO packets containing time information, and adjusts a local clock according to the time information after cluster head nodes in one hop of the secondary network receive the HELLO packets, so as to complete coarse synchronization in the range of one hop. Coarse synchronization in the two-hop and above range is the same as the above principle.
The fine synchronization in the inter-cluster synchronization is as follows: fine synchronization occurs in the network initialization phase, the node network access phase and the network normal operation process phase. Each cluster head sends RTT information in a corresponding time slot and records time T1, the ground control center receives the RTT information and records arrival time T2, and sends corresponding RTT_REP information and records time T3 according to cluster head position information contained in the RTT, each cluster head receives the RTT_REP information and records time T4, a clock adjustment value delta T is obtained according to a synchronization principle formula, each cluster head adjusts a local clock, and fine synchronization within a one-hop range is completed.
Intra-cluster synchronization is the same as inter-cluster synchronization.
Further, selecting spare cluster head nodes in the cluster: after the original cluster head node leaves the network, a certain influence on the network is inevitable. In order to increase the stability of the network, a spare cluster head node is generally selected in the formation, and when the cluster head node cannot perform tasks, the spare cluster head node can timely replace the cluster head node to play a role. The selection principle of the standby formation center node is to select the node closest to the physical center of the network space as the standby cluster head node.
The foregoing is merely a preferred embodiment of the invention, and it is to be understood that the invention is not limited to the form disclosed herein but is not to be construed as excluding other embodiments, but is capable of numerous other combinations, modifications and environments and is capable of modifications within the scope of the inventive concept, either as taught or as a matter of routine skill or knowledge in the relevant art. And that modifications and variations which do not depart from the spirit and scope of the invention are intended to be within the scope of the appended claims.
Claims (7)
1. An ad hoc network method for an antenna ad hoc network system, which is characterized in that: the ad hoc network method comprises the following steps:
s1, initializing a network: dividing unmanned aerial vehicles with known ID numbers in a gateway scene into a plurality of formations, wherein each formation represents a cluster, one unmanned aerial vehicle in each cluster is used as a central node to represent a cluster head, other unmanned aerial vehicles are used as common nodes, the common nodes in the clusters can reach the cluster heads of the central node in one hop, the cluster heads of the plurality of clusters are subjected to inter-cluster networking, namely secondary network networking, and each cluster is subjected to intra-cluster networking, namely primary network networking;
s2, the node is accessed into the network: when a common node which cannot access the network in the network initialization process or a common node which is re-added after the network is removed or a new node which is temporarily added exist, actively transmitting a network access application to be added into the network in an active network access mode;
s3, the node moves back to the network: when the node needs to be network-removed, active network-removal or passive network-removal is carried out according to the self requirement of the node;
the inter-cluster networking comprises the following contents:
a1, each formation selects one formation cluster head node for inter-cluster networking through calculation, and other nodes in the formation are common nodes in the cluster;
a2, after power-on, the cluster head performs repeated scanning directional reception on all time slots until network initialization is started after a network access message is received;
a3, according to the instruction of the ground control command center, the ground control center node starts to initiate an initialization network access flow of the secondary network, and the antenna scans all directions in each beam direction in sequence to send HELLO packets in a directional mode;
a4, after the cluster heads receive HELLO packets sent by the ground control center node, adjusting a local clock according to time information of the received HELLO packets to complete coarse synchronization, and after receiving RTT information from the second-level network one-hop cluster head node, the ground control center replies RTT information in sequence in corresponding time slots, and immediately replies RTT_REP information, and then performs fine synchronization to realize complete synchronization of the second-level network one-hop cluster head node and the ground control center node;
a5, after the ground control center discovers at least one second-level network one-hop node, executing the subsequent step, otherwise, returning to the step A1 to carry out second-level network networking again;
a6, the ground control center sequentially sends networking instructions to the first-hop cluster head nodes of the second-level network which are already connected according to the ID sequence of the network connection nodes, the cluster head nodes start neighbor discovery of the second-hop cluster head nodes, the first-hop cluster head nodes finish fine synchronization after discovering the second-hop cluster head nodes, and the first-hop cluster head nodes report discovered information of the two-hop nodes to the ground control center node in a reporting time slot; after a certain hop cluster head node discovers a two hop cluster head node and completes reporting to a ground control center node in a precise synchronization way, the next hop cluster head node begins broadcasting own HELLO (high efficiency uplink packet) packets again, begins neighbor discovery of the two hop cluster head nodes, and discards the HELLO packets according to ID (identity) numbers when the certain hop cluster head node receives the HELLO packets of other hop cluster head nodes; and the three-hop and four-hop cluster head networking is completed in the same way;
a7, after the information of the secondary network cluster head is all collected to a ground control center, the ground control center directionally transmits the secondary network topology information to the secondary network cluster head node according to the secondary network whole network topology information;
the intra-cluster networking comprises the following contents:
b1, when control information is sent to a cluster head node by a ground control center, the cluster head node firstly broadcasts HELLO information packets, then common nodes in the cluster sequentially send RTT information to the cluster head node according to ID numbers after receiving the information packets, and the cluster head node immediately replies RTT_REP information after receiving the RTT information, so that networking of the common nodes in the cluster is completed; the cluster head nodes report the topology information in each formation to a ground control center and send the topology information to common nodes in the cluster in sequence according to the formation ID number sequence;
and B2, after the networking in the cluster is completed, all topology information of the whole network is collected to a ground control center, the ground control center broadcasts the transmitting information to nodes in the whole network hop by hop, and the nodes in the whole network upload data to the ground control center hop by hop.
2. An ad hoc network method for an antenna ad hoc network system according to claim 1, wherein: the node network access specifically comprises the following contents:
the network access node flies to a designated area according to a specific geographical range which is updated in real time and is given by a ground control center, continuously transmits network access application information comprising network access node position information through omni-directional scanning of a networking/network access spreading code after reaching the designated area, and then the network access node is converted into an omni-directional scanning receiving state; when the HELLO message sent by the in-network node is received, the network access RTT message is sent to the in-network node immediately, and after the network access node receives the RTT_REP message of the in-network node, the network access node achieves time fine synchronization to complete network access, and the network is participated in normal communication in the next frame.
3. An ad hoc network method for an antenna ad hoc network system according to claim 2, wherein: the network access discovery node adopts omni-directional scanning of a networking/network access spreading code to receive network access application information, when the network access application information is received, the network access node information is declared to the cluster head node in the cluster by a declaration time slot in the cluster, the cluster head node judges whether to allow the network access according to the network access node information, when the network access permission information of the cluster head node is received, the network access node sends HELLO information in a designated time slot, and after the network access RTT information of the network access node is received, the RTT_REP information is immediately replied.
4. An ad hoc network method for an antenna ad hoc network system according to claim 1, wherein: the active logout specifically comprises the following contents:
active network exit of the cluster member nodes: the method comprises the steps that a cluster head node allows the cluster head node to adjust a time frame structure according to the number of new cluster members after the cluster head node performs network withdrawal, a central control time slot in the cluster is adopted, the cluster head node transmits network withdrawal confirmation information to the node, and notifies all other cluster head nodes of the network withdrawal information of the node, and the node completes active network withdrawal;
cluster head nodes actively exit the network: the method comprises the steps that in-cluster control time slots send replacement cluster head node information to replacement cluster head nodes, new cluster head node information is announced to in-cluster member nodes, in the next time frame, the cluster head nodes report the new cluster head node information to a ground control center, in-cluster control time slots, the new cluster head nodes receive in-cluster member node application information, time slot allocation is completed, and up to this point, the cluster head nodes complete active network withdrawal.
5. An ad hoc network method for an antenna ad hoc network system according to claim 1, wherein: the passive network-returning specifically comprises the following contents:
passive network exit of cluster member nodes: if the cluster head node declares a time slot in a cluster of two continuous time frames and does not receive the declaration information of the node, the cluster head node considers the node to exit the network, the cluster head node adjusts the time frame structure according to the number of members in a new cluster, deletes the network exit node in a topology database in the next time slot, the new time slot table does not contain the table item of the network exit node any more, and sends the network exit information of the node to other member nodes in the cluster;
cluster head nodes passively exit the network: if other common nodes in the two time frames do not receive the cluster head node reply message, the standby cluster head node is updated to a new cluster head node in the next time frame, the replacement of the cluster head node is completed, the network-quitting node is deleted in the topology database, and the new time slot table does not contain the table item of the network-quitting node any more so as to maintain the normal operation of the network.
6. An ad hoc network method for an antenna ad hoc network system according to claim 1, wherein: the coarse synchronization includes: the ground control center starts network initialization, sends HELLO packets containing time information, and adjusts a local clock according to the time information after cluster head nodes in one hop of the secondary network receive the HELLO packets, so as to complete coarse synchronization in the range of one hop.
7. An ad hoc network method for an antenna ad hoc network system according to claim 1, wherein: the fine synchronization includes: each cluster head sends RTT information in a corresponding time slot and records time T1, the ground control center receives the RTT information and records arrival time T2, and sends corresponding RTT_REP information and records time T3 according to cluster head position information contained in the RTT, each cluster head receives the RTT_REP information and records time T4, a clock adjustment value delta T is obtained according to a synchronization principle formula, each cluster head adjusts a local clock, and fine synchronization within a one-hop range is completed.
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