A preamble-based multi-frequency self-organizing network fast routing discovery and networking method

Abstract

The application discloses a kind of multi-frequency self-organizing network fast routing discovery and networking method based on preamble, it is characterized in that, from gateway node, each previous node initiates multi-frequency preamble time switch mechanism process, T-Query process, Net-Config process to its subsequent node in turn, so that the secondary node accesses the network with the gateway node as the starting node.The method of the application can significantly reduce the networking and maintenance time, as the significant reduction of networking and maintenance time, using the method of the application can let industrial internet of things collect data for more time, thereby significantly improving the data acquisition frequency of industrial internet of things.

Description

Technical Field

[0001] This invention relates to the field of network layer protocols for the Industrial Internet of Things (IIoT), and more particularly to a method for fast route discovery and networking of multi-frequency self-organizing networks based on a preamble. Background Technology

[0002] The Industrial Internet of Things (IIoT) is an important branch of the Internet of Things (IoT) and is considered the foundation of smart manufacturing and Industry 4.0. IIoT operates in factory environments, aggregating and uploading data generated by sensors within the factory. However, the large number of nodes in an IIoT network, the often unfavorable communication environments, and the limited processing power of individual nodes due to cost constraints all contribute to the network's instability.

[0003] The networking process in the Industrial Internet of Things (IIoT) is essentially a multi-level self-organizing network based on centralized control. The process of numerous nodes competing to access the network typically employs the CSMA / CA mechanism (Carrier Sense Multiple Access with Collision Detection) to form a tree-like network topology. However, practical experience shows that existing mechanisms are insufficient. First, the CSMA / CA protocol uses data transmission for contention, resulting in excessively long data frames and thus lengthy network establishment and maintenance times. Second, while existing preamble-based networking mechanisms (P-MAC) offer faster networking speeds than CSMA / CA, they operate only on a single frequency. Networking on a single frequency often fails to detect all connections between nodes, and connections on a single frequency are prone to disconnection under frequency-selective channel conditions. This necessitates frequent networking and maintenance to ensure connectivity for all nodes. Due to these limitations, the network spends excessive time on networking and maintenance, leading to a lower frequency of industrial data acquisition. Therefore, designing a mechanism capable of rapid networking and maintenance across multiple communication frequencies is crucial for the successful implementation of the IIoT. Summary of the Invention

[0004] In view of the above-mentioned deficiencies of the prior art, the present invention provides a fast route discovery and networking method for multi-frequency self-organizing networks based on a preamble, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this invention provides a fast route discovery and networking method for multi-frequency self-organizing networks based on a preamble. This method starts with the gateway node (CCO), and each preamble node sequentially initiates a multi-frequency preamble time exchange mechanism process, a T-Query process, and a Net-Config process to its subsequent nodes, enabling the secondary nodes to access the network originating from the gateway node. In the specific networking process, the gateway node (CCO) initially acts as the preamble node, and the slave nodes (STAs) that can directly communicate with it are used as secondary nodes for networking. Subsequently, the CCO controls these slave nodes (STAs) to sequentially network with their respective secondary nodes until all STAs have completed networking.

[0006] A further improvement of the present invention is that the frequency division preamble time exchange mechanism (FD-PTE process) specifically includes:

[0007] The front-end node sends a NET preamble to each of the secondary nodes via multiple frequency bands;

[0008] After receiving the NET preamble, each secondary node waits randomly for several time slots and sends a REQ preamble to the primary node in the frequency band in which the NET preamble was received. Both the primary node and the secondary nodes record the time difference between the NET preamble and each REQ preamble as the preamble time difference.

[0009] In the multi-frequency preamble time exchange mechanism, all frequencies capable of establishing communication are determined based on prior knowledge (e.g., user profiles). Both the preceding and following nodes record the preamble time difference, ensuring that the uplink and downlink preamble time differences are known to both the master and receiving nodes. During the FD-PTE phase, utilizing the characteristics of time delay during signal transmission, a correction mechanism is employed to ensure that the time differences recorded by the master and following nodes are equal.

[0010] In this process, the preambles transmitted on different frequencies are different and will not collide. In this method, the gateway node CCO and each slave node STA use three types of preambles: NET preamble (representing the downlink preamble at the start of network formation), REQ preamble (representing the uplink preamble for network access request), and DAT preamble (representing the data frame).

[0011] A further improvement of the present invention is that the T-Query process has time-division multiplexing characteristics, which includes:

[0012] The front-end node transmits data frames in each frequency band, and the data frames in each frequency band include the preamble time difference of all REQ preambles in that frequency band.

[0013] After receiving a data frame from the preceding node, the secondary node iterates through all preamble time differences in the data frame. If it finds a preamble time difference in the frequency band that matches the preamble time difference stored by the secondary node, it waits for the corresponding number of time slots according to the order of the preamble time differences in the data frame before sending a MAC data frame (for example, if the second preamble time difference is the same, it waits for two time slots before sending the MAC data frame). The MAC data frame includes the MAC address of the secondary node, the current SID address, and all preamble time differences recorded by the secondary node.

[0014] The Net-Config process is used to confirm whether a node has joined the network. This process specifically includes:

[0015] The front-end node transmits data frames in each frequency band. The data frames include the MAC address of each secondary node and the corresponding new SID. In this embodiment, the new SID is specified by the gateway node CCO.

[0016] Upon receiving the data frame, each secondary node traverses the data frame to find its own MAC address. If a MAC address is found, the corresponding SID is used as its own SID, and an ACK reply is sent to the preceding node sequentially according to the position of the MAC address in the data frame. Specifically, the Net-Config process is used to notify STAs acting as slave nodes of their network entry results. The CCO or PCO sends a data frame (denoted as SDF, or SID Frame) on a certain frequency, which contains the MAC addresses of all STAs that have successfully entered the network on that frequency and their assigned SIDs. STAs receiving this data frame traverse the MAC addresses in the data frame. If their own MAC address is found, their SID is updated to the value in the data frame, and the position index of their own MAC address in the data frame is recorded. After waiting for the specified number of time slots, they reply to the CCO or PCO with a data frame (denoted as ACK, or Acknowledge Frame). The ACK data frame contains their own MAC address and the latest SID. The CCO or PCO performs the above Net-Config process sequentially on all frequencies.

[0017] In this invention, all nodes except the gateway node CCO are slave nodes STA; during network formation, when a slave node STA acts as a front-end node, it becomes a proxy node PCO; in the multi-level network formation process:

[0018] The gateway node CCO sends a PTE-S data frame to the proxy node, causing the proxy node to initiate the multi-frequency preamble time exchange mechanism process.

[0019] The proxy node sends the preamble time differences recorded during the multi-frequency preamble time exchange mechanism to the gateway node via PTE-F data frames.

[0020] The gateway node sends a Tquery-S data frame to the proxy node, causing the proxy node to start the Tquery process.

[0021] The proxy node sends the data (MAF) in the MAC data frames sent by each secondary node during the Tquery process to the gateway node through Tquery-F data frames;

[0022] The gateway node sends a Netconfig-S data frame to the proxy node, causing the proxy node to start the Net-Config process.

[0023] The proxy node sends the ACK responses sent by each secondary node during the Netconfig process to the gateway node via Netconfig-F data frames.

[0024] A further improvement of the present invention is that the Netconfig-S data frame includes the SID corresponding to the MAC data of each secondary node of the proxy node.

[0025] For multi-level networks, an existing STA (Stationary Targeting Organization) needs to act as a PCO (Programmer's Office) to discover lower-level STAs. The specific process is as follows: The CCO (Center for Controlling the Network) sends a data frame representing the start of network formation (denoted as PTE-S, or PTEStart) to the STA acting as the PCO using the previously discovered routes; after receiving the PTE-S data frame, the PCO begins the FD-PTE process, and then sends a data frame containing the number of recorded time differences (denoted as PTE-F, or PTEStart) to the CCO. The process involves the following steps: After receiving a PTE-F data frame, the CCO sends a Tquery-S data frame to the PCO to notify it to perform a T-Query process, and determines the maximum waiting time based on the number of time differences from the PCO; after receiving the Tquery-S data frame, the PCO performs the T-Query process and then sends a Tquery-F data frame to the CCO, containing the recorded MAC addresses; after receiving the Tquery-S, the CCO sends a Netconfig-S data frame to the PCO, containing the SIDs assigned to all MAC addresses; after receiving the Netconfig-S, the PCO performs the Net-Config process and then sends a Netconfig-F data frame to the CCO, containing the SIDs of the STAs that have successfully joined the network; finally, the CCO updates the routing information and begins multi-level networking with other STAs acting as PCOs. Once all STAs that have joined the network have performed networking as PCOs at least once, it is considered that all nodes in the network have joined the network.

[0026] A further improvement of this invention lies in the fact that, during the multi-frequency preamble time exchange mechanism, collision detection is achieved by detecting whether there are identical preamble time differences in each frequency band. The specific mechanism for collision detection and handling is as follows: The CCO (or PCO) records the STA to which each time difference belongs. After the FD-PTE process, all time differences recorded by the CCO (or PCO) are in an unassigned state. During the T-Query process, the MAF data frame sent by the STA contains all time differences recorded by the STA at all frequencies. The CCO (or PCO) iterates through the time differences in the MAF and checks their local assignment status. If it is unassigned, the status of the time difference is updated to belong to that STA. If it already belongs to another STA, it indicates that the two STAs have the same time difference at the current frequency, and a collision will occur. This collision detection mechanism can detect both past and future collisions. Collision handling occurs during the Net-Config phase. The CCO (or PCO) can send a dedicated data frame to the STA involved in the collision at the frequency where the collision occurred, thus clarifying that these STAs and the CCO (or PCO) can establish a connection at the frequency where the collision occurred.

[0027] The method of the present invention can significantly reduce networking and maintenance time. Due to the significant reduction in networking and maintenance time, the method of the present invention allows the Industrial Internet of Things (IIoT) to have more time for data collection, thereby significantly improving the data collection frequency of the IIoT.

[0028] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating an example of a single-layer network implemented according to the present invention.

[0030] Figure 2 This is a schematic diagram illustrating an example of a multi-layer network implemented according to the present invention.

[0031] Figure 3 This is a schematic diagram illustrating an example of collision detection and processing implemented in this invention.

[0032] Figure 4 The surface represents the change in collision detection failure probability as a function of P and M (N = 160, F = 8).

[0033] Figure 5 The surface representing the statistical frequency of collision detection failures as a function of P and M (N = 160, F = 8). Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0035] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0036] Some exemplary embodiments of the invention have been described for illustrative purposes. It should be understood that the invention may be implemented in other ways not specifically shown in the accompanying drawings.

[0037] Figure 1 The example shown is a single-layer networking process proposed in this invention, and the example of a two-level network consisting of four nodes is analyzed.

[0038] The network connectivity is shown in the figure. There are three communicable frequencies, denoted as f1, f2, and f3. CCO and STA1 can communicate on f1 and f2, STA2 on f2, CCO and STA3 on f2 and f3, and CCO and STA4 on f1, f2, and f3. First, CCO initiates FD-PTE, sequentially sending NET preambles on the three frequencies. The four STAs will then receive the NET on their respective communicable frequencies. After waiting for a certain number of time slots, each STA sends a REQ preamble to CCO on the frequency on which it received the NET. Both CCO and the STAs record the time difference between the NET and REQ. When REQs from different frequencies are sent in the same time slot, since the different frequencies do not interfere with each other, CCO can receive these preambles normally. Then, the CCO initiates a T-Query procedure. First, it sends a data frame containing all f1 preamble time differences on frequency f1. STA1 and STA4 respond to this data frame by sequentially replying to the CCO with MAC data frames containing their own MAC address, current SID, and all time differences. The CCO also performs similar T-Query procedures on f2 and f3. Finally, the CCO initiates a Net-Config procedure, sending data frames containing the MAC addresses and SIDs of STA1 and STA4, STA1, STA2, STA3, and STA4, and STA3 and STA4 respectively on frequencies f1, f2, and f3. All STAs send ACK replies on a specific frequency in a designated time slot. Because the data frames replied by the STAs during the T-Query procedure contain time differences from other frequencies, the CCO, after confirming the STA belonging to a time difference, can refrain from sending queries for that time difference in subsequent T-Query procedures on other frequencies. This further reduces the number of data frames sent, which is why the T-Query procedure is not performed on f3.

[0039] Figure 2 The following is an example of the multi-layer networking process proposed in this invention, analyzing an example of a three-level network composed of 5 nodes.

[0040] Assuming that CCO has completed a single-layer network with STA1 and STA2, STA1 can establish connections with STA3 and STA4 at f2 and f3 respectively, and STA2 can establish connections with STA4 and STA5 at f3 and f1 respectively. Since the second-level network has two nodes, the networking of the third-level network needs to be performed twice (i.e., Step 1 and Step 2).

[0041] In Step 1, the CCO sends a PTE-S data frame to instruct STA1 to begin network setup. Upon receiving the frame, STA1 performs the FD-PTE procedure and then replies in a PTE-F data frame with the number of time differences recorded on all frequency points. Next, the CCO sends a Tquery-S data frame to STA1. Upon receiving this frame, STA1 begins the T-Query procedure on each frequency, then packages the received MAF data frames from each frequency into a Tquery-F data frame and replies to the CCO. Finally, the CCO packages the assigned SID into a Netconfig-S data frame. Upon receiving this frame, STA1 begins the Net-Config procedure on each frequency and then sends the SIDs of STA3 and STA4, which have successfully joined the network, to the CCO. Thus, STA1, acting as the PCO, completes the third-level network organization.

[0042] The CCO will instruct STA2 to act as the PCO, performing a process similar to Step 1 to organize the third-level network. Due to the complexity of multi-layered networks, lower-layer STAs may have connections with multiple upper-layer STAs. If an STA receives a NET preamble again after already joining the network, it will still send a REQ preamble. This allows the CCO to obtain all connection information about the STA, enabling the CCO to communicate with it via more backup routes. Furthermore, node connectivity can be uploaded as industrial data to the upper layers of the Industrial Internet of Things (IIoT). The upper layers can utilize more powerful computing devices for long-term analysis to identify patterns in connection changes. Maintaining all possible routes facilitates this process.

[0043] Figure 3 The following is an example of the collision detection and processing process proposed in this invention, analyzing the detection and processing when two nodes collide.

[0044] Assume that STA1 and STA2 can both establish connections with the CCO on f1 and f2 respectively. During the FD-PTE process, both STA1 and STA2 send REQ preambles on f1 and f2 respectively, and their preambles on f1 collide. Since preamble detection is significantly easier than data frame detection, the CCO may still be able to detect the REQ collision on f1, but will only record one time difference (ΔT11 equals ΔT21). In the T-Query on the f1 frequency, STA1 and STA2 will send MAF data frames in the same time slot, and the data frame collision makes it impossible for the CCO to distinguish the correct information. However, during the T-Query on f2, the MAF data frames sent by STA do not collide. When the CCO analyzes the two MAF data frames, it will find that they have the same time difference on f1, thus detecting a collision between STA1 and STA2 on f1. The CCO handles the collision by starting an additional Net-Config process on f1, which does not collide, allowing the CCO to verify the connection between STA1 and STA2 on f1.

[0045] Networking Time Analysis: Comparing the FD-PMAC method proposed in this invention with existing preamble time difference (P-MAC) networking mechanisms operating on a single frequency, considering a single-layer network, assuming a total of N communication frequencies and M nodes, F... m Let m∈{1,…,M} represent the set of frequencies at which each STA can establish a connection with the CCO. If P-MAC is extended to N frequencies, the PTE time needs to be N times the original time. However, FD-PTE operates in parallel across all frequencies; therefore, FD-PTE, performing the same function on N frequencies, takes only 1 / N the time of PTE. For the T-Query process, PMAC uses a polling method, with each data packet carrying only one time difference information, requiring a total number of time slots. FD-PMAC uses time-division multiplexing, and each data packet carries information from all frequencies, requiring a total of N+M time slots. For the Net-Config process, P-MAC uses a polling method when executing these two processes, while FD-PMAC uses time-division multiplexing; therefore, FD-PMAC takes half the time of P-MAC. Let N be a typical value of 8, |F m |=3,m∈{1,..,M}, the number of preamble time slots in the PTE process is 4 times the total number of nodes. Assuming the preamble time slot length is T, which is 1 / 25 of the data frame time slot length, the single-layer networking times for FD-PMAC and P-MAC are 4M×T+M×25T+3M×25T and 32M×T+6M×25T+6M×25T respectively. FD-PMAC's time is approximately only 30% of P-MAC's. In multi-layer networking, FD-PMAC can save more time than P-MAC.

[0046] Compared with the FD-PMAC proposed in this invention and the existing CSMA / CA mechanism, the hardware resources required for parallel transmission and reception of data frames on multiple frequencies exceed the limitations of industrial IoT devices. CSMA / CA mechanisms at different frequencies can only be executed serially. Moreover, it has been proven that the execution time of P-MAC on a single frequency is only 1%-10% of that of CSMA / CA. Therefore, the time spent on networking and maintenance of FD-PMAC will be much less than that of CSMA / CA.

[0047] Due to the significant reduction in networking and maintenance time, using FD-PMAC allows the Industrial Internet of Things (IIoT) to have more time for data acquisition, thereby significantly increasing the data acquisition frequency of the IIoT.

[0048] Success Rate Analysis of Collision Detection and Handling Mechanism: The collision detection mechanism proposed in this invention utilizes the characteristics of multiple communication frequencies. A collision between two STAs occurring on one frequency cannot be detected on that frequency, but the two STAs may not collide on other frequencies. As long as the CCO successfully receives data frames from both STAs on any other frequency, it can detect the collision at that frequency. Collisions on different frequencies are independent of each other, and the condition for a collision of an STA to be undetectable is that the data frames transmitted by that STA on all frequencies will collide. Therefore, the probability of collision detection failure decreases rapidly as the number of communication frequencies increases.

[0049] Let N be the number of time slots allocated during the FD-PTE process, F be the number of communicable frequencies, and M be the number of STAs requesting to join the network. For communication quality, let P represent the probability that a STA can communicate on a single frequency. The smaller P is, the fewer communicable frequencies a single STA has, and the fewer STAs can communicate on the same frequency. The average number of communication frequencies for a STA is P×M, and the average number of STAs communicating on a single frequency is P×F. Then, for a single STA, the probability that all of its transmitted data frames collide is P. c As shown in equation (1), the time slot selection of each STA is independent of each other, so the total number of collision detection failures follows a Bernoulli probability, with an expected value equal to P. c The product of M.

[0050]

[0051] Considering common scenarios, set N to 160, F to 8, let P vary between 1 / 8 and 1, and let the number of competing STAs M vary between 4 and 40. Plot P. c Surfaces that vary with P and M, such as Figure 4 As shown. Furthermore, large-scale simulations were performed (50,000 simulations per point), and the expected value was approximated using statistical averaging. The resulting collision probability surface is shown below. Figure 5As shown. Figure 4 and Figure 5 The results show that the detection failure probability is on the order of 0.1% when there are 2 communication frequencies, and on the order of 0.01% when there are 3 communication frequencies. In the worst case, the collision probability is on the order of 1%, which indicates that the collision detection failure probability is very low when there are multiple communication frequencies.

[0052] Explanation of abbreviations and terms:

[0053] The FD-PMAC (Frequency Division Preamble based MAC) protocol is a self-organizing network protocol that uses a preamble-based contention access method on multiple communication frequencies to achieve fast route discovery and network establishment. This protocol is mainly aimed at the Industrial Internet of Things.

[0054] • CCO, PCO, and STA are types of nodes in a network. Nodes in a network are divided into gateways (CCO) and slave nodes (STA). Slave nodes become proxy nodes (PCO) when forwarding data frames from gateways and other slave nodes.

[0055] NET, REQ, and DAT are the preamble types used in the FD-PMAC protocol. The NET preamble is sent by the CCO or PCO and represents the start of a layer of networking. The REQ preamble is sent by the STA and represents a networking request. The DAT preamble serves as the start marker for a data frame.

[0056] • Frequency Division Preamble Time Exchange (FD-PTE) refers to a preamble-based contention access method on multiple frequencies, where the CCO (or PCO) and STA record the same time difference information on frequencies where they can communicate with each other.

[0057] • SID refers to the short address of a node in a network. The short address has a shorter byte length than the MAC address.

[0058] • TDF and MAF are data frames sent by CCO (or PCO) and STA during the T-Query process based on time division multiplexing. TDF (Time Difference Frame) contains all the time differences recorded by CCO (or PCO) on a certain frequency, and MAF (MAC Address Frame) contains the STA's MAC address and current SID (initialized to 1 when the STA has not joined the network).

[0059] • The T-Query process based on time division multiplexing involves the sending node (i.e., CCO or PCO) sending a TDF, and the receiving node (i.e., STA) reading the time difference in the TDF and comparing it with the local time difference. If they match, the receiving node replies with a MAF data frame. When multiple STAs reply, time division multiplexing is used.

[0060] • SDF and ACK are data frames sent by the CCO (or PCO) and STA during the Net-Config process based on time division multiplexing. The SDF (SID Frame) contains all the MAC addresses recorded by the CCO (or PCO) on a certain frequency and the SID assigned to them. The ACK contains the STA's MAC address and the latest SID, indicating that the STA has confirmed that it has joined the network.

[0061] • The time-division multiplexing-based Net-Config process involves the sending node (i.e., CCO or PCO) sending an SDF, and the receiving node (i.e., STA) reading the MAC address in the SDF and comparing it with its own MAC address. If they match, the receiving node replies with an ACK data frame. When multiple STAs reply, time-division multiplexing is used.

[0062] • PTE-S, PTE-F, Tquery-S, Tquery-F, Netconfig-S, and Netconfig-F are data frames used by the CCO and PCO in the multi-level networking process. The S (Start) suffix is ​​sent by the CCO, and the F (Feedback) suffix is ​​sent by the PCO. PTE-S controls the PCO to start the FD-PTE process. PTE-F contains the time difference recorded by the PCO at each frequency. Tquery-S controls the PCO to start the T-Query process. Tquery-F contains the MAF recorded by the PCO at each frequency. Netconfig-S contains the SID assigned by the CCO to all MAC addresses. Netconfig-F contains the ACKs of all STAs that have successfully joined the network.

[0063] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for fast route discovery and networking in a multi-frequency ad hoc network based on a preamble, characterized in that, Starting from the gateway node, each preceding node sequentially initiates the multi-frequency preamble time exchange mechanism process, the T-Query process, and the Net-Config process to its following nodes, enabling the secondary nodes to access the network starting from the gateway node. The T-Query process specifically includes: The front-end node transmits data frames in each frequency band, and the data frames in each frequency band include the preamble time difference of all REQ preambles in that frequency band. After receiving a data frame from the preceding node, if the secondary node records the same preamble time difference, it waits for the corresponding number of time slots according to the order of the preamble time difference in the data frame before replying with a MAC data frame. The MAC data frame includes the MAC address of the secondary node, the current SID address, and all the preamble time differences recorded by the secondary node. In the multi-frequency preamble time exchange mechanism, collision detection is achieved by detecting whether there is the same preamble time difference in each frequency band. The collision detection mechanism is as follows: the front-end node records the secondary node to which each time difference belongs. After the multi-frequency preamble time exchange process, all time differences recorded by the front-end node are in an unassigned state. During the T-Query process, the MAC data frame sent by the secondary node will contain all time differences recorded by the secondary node at all frequencies. The front-end node will traverse the time differences in the MAC data frame and check the local assignment status of these time differences. If it is in an unassigned state, the status of the time difference will be updated to belong to the secondary node. If it has already belonged to another secondary node, it means that the two secondary nodes have the same time difference at the current frequency, and a collision will occur. Apart from the gateway node, all other nodes are slave nodes; during network construction, when a slave node acts as a front-end node, it becomes a proxy node; in two-level or multi-level network construction: The gateway node sends a PTE-S data frame to the proxy node, causing the proxy node to initiate the multi-frequency preamble time exchange mechanism process. The proxy node sends the preamble time differences recorded during the multi-frequency preamble time exchange mechanism to the gateway node via PTE-F data frames. The gateway node sends a Tquery-S data frame to the proxy node, causing the proxy node to start the T-Query process. The proxy node sends the data in the MAC data frames sent by each secondary node during the T-Query process to the gateway node through Tquery-F data frames; The gateway node sends a Netconfig-S data frame to the proxy node, causing the proxy node to start the Net-Config process. The proxy node sends the ACK responses sent by each secondary node during the Net-Config process to the gateway node via Netconfig-F data frames; In the process of multi-level network construction, if a secondary node that has already joined the network receives the NET preamble again, the secondary node that has already joined the network will still send the REQ preamble, so that the gateway node can obtain all the connection information about the secondary node that has already joined the network, and more backup routes can communicate with the secondary node that has already joined the network.

2. The method for fast route discovery and networking of multi-frequency ad hoc networks based on preambles according to claim 1, characterized in that, The multi-frequency preamble time exchange mechanism process specifically includes: The front-end node sends NET preambles to each of the secondary nodes via multiple frequency bands; After receiving the NET preamble, each secondary node waits randomly for several time slots and sends a REQ preamble to the primary node in the frequency band in which the NET preamble was received. Both the primary node and the secondary nodes record the time difference between the NET preamble and each REQ preamble as the preamble time difference.

3. The method for fast route discovery and networking in a multi-frequency ad hoc network based on a preamble, as described in claim 1, is characterized in that... The Net-Config process specifically includes: The front-end node transmits data frames in each frequency band, and the data frames include the MAC address and corresponding SID of each secondary node. Upon receiving the data frame, each of the secondary nodes sequentially sends an ACK reply to the preceding node.

4. The method for fast route discovery and networking of multi-frequency ad hoc networks based on preambles according to claim 1, characterized in that, The Netconfig-S data frame includes the SID corresponding to the MAC data of each secondary node of the proxy node.

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