A method and apparatus for channel preemption in a wireless ad hoc network

Abstract

The application discloses a channel preemption method and device in a wireless self-organizing network, relates to the field of communication technology, and is applied to any network node in a wireless Mesh self-organizing network system and is realized based on a physical layer hardware. The method comprises the following steps: continuously detecting whether a unified preamble exists in a channel in a listening window period of a current time slot cluster; if no preamble is detected and the signal strength of the current channel is 0, then a data frame comprising a preamble, an SFD and service data in sequence is sent; if a preamble is detected, then a first priority identified by the SFD is acquired; if the second priority of the service data of the node is higher than the first priority, then the data frame is sent; if the second priority is lower than the first priority, then the current sending is abandoned, a silent listening state is entered, and the next similar time slot cluster is waited for to reinitiate sending. The application can compress the time delay of channel access and preemption decision to the order of microseconds, can significantly reduce the conflict probability in a multi-node concurrent scene, and can save system overhead.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a channel preemption method and apparatus in a wireless ad hoc network. Background Technology

[0002] With the development of the low-altitude economy and the industrial internet, wireless mesh self-organizing network technology, due to its decentralized, self-healing, and flexible networking characteristics, is widely used in scenarios such as drone swarms, emergency communications, and sensor networks. To ensure the orderly communication under multiple concurrent services, related technologies typically employ a time-division multiplexing mechanism, dividing superframes into different functional time slot clusters (such as broadcast time slot clusters, time synchronization time slot clusters, and command transmission time slot clusters). Network nodes must compete within their respective functional time slot clusters to complete data transmission.

[0003] Currently, channel access and priority scheduling in mainstream wireless mesh networks largely rely on the Media Access Control (MAC) layer protocol stack and software scheduling by the Central Processing Unit (CPU). A typical approach is as follows: after receiving an air interface signal, a network node needs to upload the complete data frame to the CPU via the radio frequency link. The protocol stack then performs preamble alignment, frame parsing, priority tag extraction, and queuing scheduling before deciding whether to transmit or avoid the signal.

[0004] However, under the above-mentioned technical path based on software deframe and protocol stack processing, the system often faces long-term technical bottlenecks such as extended channel access time, high probability of channel collision, and difficulty in further reducing system overhead when facing service transmission with high real-time requirements. Summary of the Invention

[0005] In view of this, the present invention provides a channel preemption method and apparatus in a wireless ad hoc network to solve the technical problems faced by existing solutions, such as prolonged channel access time, high probability of channel collisions, and difficulty in further reducing system overhead. The technical solution is as follows:

[0006] The first aspect of this application provides a channel preemption method in a wireless ad hoc network, applicable to any network node in a wireless mesh ad hoc network system. The method is implemented based on physical layer hardware and includes:

[0007] During the listening window of the current functional time slot cluster, continuously detect whether there is a network-wide unified preamble in the channel;

[0008] If the preamble is not detected and the current channel signal strength is 0, the channel is determined to be idle, and a data frame containing the preamble, the start-of-frame delimiter (SFD), and the target service data is sent sequentially, wherein the SFD indicates the priority of the target service data;

[0009] If the preamble is detected, it is determined that the channel has been occupied by other network nodes. The SFD immediately following the preamble is read, the priority identified by the read SFD is determined, and the first priority is obtained.

[0010] The second priority is compared with the first priority, where the second priority is the priority of the target service data of this network node;

[0011] If the second priority is higher than the first priority, then a data frame containing the preamble, SFD and target service data in sequence is sent.

[0012] If the second priority is lower than the first priority, the current transmission is abandoned, and a silent listening state is entered, waiting for the next time slot cluster of the same function to re-initiate the transmission.

[0013] In one possible implementation, the channel preemption method in the wireless ad hoc network further includes:

[0014] If, during the transmission of the data frame, it is detected that the priority identified by the SFD sent by a network node is higher than the priority identified by the SFD in the data frame, the transmission of the data frame is stopped, and a silent listening state is entered, waiting for the next time slot cluster of the same function to re-initiate the transmission.

[0015] In one possible implementation, stopping the transmission of the data frame includes:

[0016] Turn off the power amplifier to stop RF transmission, clear the transmit buffer, and record the preempted state.

[0017] In one possible implementation, the channel preemption method in the wireless ad hoc network further includes:

[0018] During the transmission of the data frame, if a conflict signal of the same priority transmitted by another network node is detected in the channel, the Received Signal Strength Indicator (RSSI) value of the conflict signal of the same priority is obtained, wherein the priority identified by the SFD contained in the conflict signal of the same priority is the same as the priority identified by the SFD in the data frame.

[0019] Based on the RSSI value and in conjunction with preset contention avoidance rules, determine whether you have the right to use the channel;

[0020] If it determines that it has the right to use the channel, it continues to complete the transmission of the data frame;

[0021] If it determines that it does not have the right to use the channel, it stops sending the data frame and enters a silent listening state, waiting for the next time slot cluster of the same function to re-initiate the transmission.

[0022] In one possible implementation, determining the priority identified by the read SFD includes:

[0023] Based on a pre-built mapping table between SFDs and priorities, the read SFDs are matched with the SFDs in the mapping table;

[0024] The priority of the SFD that matches the read SFD in the correspondence table is determined as the priority identified by the read SFD.

[0025] In one possible implementation, the correspondence table includes high priority, medium priority, and low priority, as well as SFDs corresponding to the high priority, medium priority, and low priority, with different SFDs corresponding to different priorities.

[0026] In one possible implementation, the high-priority service data includes one or more of the following service data: gateway broadcast data, time synchronization data, sensing data, and control command data;

[0027] The medium-priority service data includes: interaction data between the base station-side terminal and the network access node;

[0028] The low-priority business data includes one or more of the following: normal status reporting data and non-real-time data.

[0029] In one possible implementation, the physical layer hardware includes a radio frequency front-end and baseband hardware;

[0030] The detection of the preamble and the transmission of the data frame are performed based on the radio frequency front end;

[0031] The reading of SFDs, priority determination, priority comparison, and decision-making regarding preemptive transmission and collision avoidance are performed based on the baseband hardware.

[0032] In one possible implementation, the network node performs priority preemption only within its own functional time slot cluster, and the priority preemption performed by the node is only effective within the functional time slot cluster to which the node belongs; priority preemption between different functional time slot clusters is independent of each other and does not interfere with each other.

[0033] The second aspect of this application provides a channel preemption device in a wireless ad hoc network, which is applied to any network node in a wireless mesh ad hoc network system. The device includes a radio frequency front-end and baseband hardware.

[0034] The radio frequency front end is used to continuously detect whether there is a network-wide unified preamble in the channel during the listening window period of the current functional time slot cluster;

[0035] The baseband hardware is configured to determine that the channel is idle when the preamble is not detected by the radio frequency front-end and the current channel signal strength is 0, and to start transmitting a data frame containing the preamble, a hierarchical frame start descriptor (SFD), and target service data in sequence. The SFD indicates the priority of the target service data. When the preamble is detected by the radio frequency front-end, it is determined that the channel is occupied by other network nodes. The SFD immediately following the preamble is read, and the priority identified by the read SFD is determined to obtain a first priority. A second priority is compared with the first priority, where the second priority is the priority of the target service data of this network node. If the second priority is higher than the first priority, a data frame containing the preamble, SFD, and target service data in sequence is transmitted. If the second priority is lower than the first priority, the radio frequency front-end is controlled to abandon this transmission, and the network node enters a silent listening state to wait for the next time slot cluster of the same function to re-initiate transmission.

[0036] By employing the above technical solution, the channel preemption method in wireless ad hoc networks provided by this invention decentralizes core steps such as preamble detection, SFD reading, priority determination, and priority comparison to physical layer hardware execution. This eliminates the need to upload complete data frames to the CPU for MAC layer protocol stack parsing and queuing scheduling. Compared to the millisecond-level access latency of existing technologies that rely on software frame de-framing and CPU scheduling, this method compresses the channel access and preemption decision latency to the microsecond level, providing reliable guarantees for low-latency services. Simultaneously, this invention directly identifies and recognizes service priorities at the physical layer hardware through hierarchical SFD. When multiple network nodes generate transmission requests within the same time slot cluster, high-priority nodes can immediately preempt the channel based on hardware comparison results, while low-priority nodes actively yield within microseconds, thus significantly reducing the probability of collisions in multi-node concurrent scenarios. Furthermore, the entire decision-making chain of preamble detection, SFD reading, priority determination, and priority comparison is completed in the physical layer hardware. The entire process does not require CPU participation, protocol stack parsing, or memory read / write operations caused by frame parsing. This effectively frees up CPU processing resources, significantly reduces the number of interrupt responses and memory accesses, and avoids the power consumption overhead caused by frequent CPU wake-ups and memory operations. It comprehensively saves system overhead from multiple dimensions such as computing resources, memory access, and power consumption, which is particularly beneficial for battery-powered terminal devices. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0038] Figure 1 This is a flowchart illustrating the channel preemption method in a wireless ad hoc network provided in an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of the channel preemption device in a wireless ad hoc network provided in an embodiment of the present invention. Detailed Implementation

[0040] The embodiments of the present invention will now be described with reference to the accompanying drawings. The terminology used in the embodiments section is for illustrative purposes only and is not intended to limit the scope of the invention.

[0041] The embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided by the embodiments of the present invention are equally applicable to similar technical problems.

[0042] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the description of embodiments of the invention. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of units is not necessarily limited to those units, but may include other units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0043] To address the shortcomings of existing technologies, this invention provides a channel preemption method in wireless ad hoc networks. This method is applied to any network node in a wireless mesh ad hoc network system. It should be noted that this method is implemented based on physical layer hardware. Please refer to [link to relevant documentation]. Figure 1 The flowchart illustrates a channel preemption method in a wireless ad hoc network provided in an embodiment of this application. This method may include:

[0044] Step S101: During the listening window of the current functional time slot cluster, continuously detect whether there is a network-wide unified preamble in the channel.

[0045] The current functional time slot cluster is a specific time resource unit allocated to a node by the wireless mesh ad hoc network system for performing specific communication functions such as data transmission, time synchronization, or broadcasting. The listening window period is configured at the beginning of each functional time slot cluster and serves as a preset time interval for network nodes to assess the channel state before attempting to transmit.

[0046] The network-wide unified preamble is a fixed bit sequence shared by all nodes in a wireless mesh self-organizing network system, designed to ensure that all network nodes have consistent channel identification and synchronization capabilities. During the listening window, the network node can use physical layer hardware to continuously monitor the channel and detect the presence of the network-wide unified preamble.

[0047] In one possible implementation, the physical layer hardware may include a radio frequency front-end and baseband hardware. During the listening window, the network node can continuously monitor the channel based on the radio frequency front-end to detect whether a preamble exists in the channel.

[0048] Step S102a: If no preamble is detected and the current channel signal strength is 0, the channel is determined to be idle, and a data frame containing a preamble, a start frame delimiter (SFD), and the target service data is sent sequentially.

[0049] The target service data is the service data to be sent by this node, and the SFD in the data frame is used to identify the priority of the target service data.

[0050] If no preamble is detected within the listening window and the current channel signal strength is 0, it indicates that the current channel is idle and no other nodes are transmitting. At this time, the network node can start sending data frames based on the radio frequency front-end. The data frame contains the preamble, SFD, and communication payload in sequence. The communication payload carries the service data to be sent by the network node, i.e., the target service data mentioned above. The preamble is located at the beginning of the frame, followed by the SFD, which is used to identify the priority of the target service data.

[0051] In this embodiment, the frame structure of "preamble + SFD + communication payload" allows the receiver to identify the priority of the currently transmitted data simply by parsing the SFD after the preamble, without having to process the complete frame content, thus providing a physical layer basis for fast hardware-level priority determination.

[0052] Step S102b: If a preamble is detected, it is determined that the channel has been occupied by other nodes. The SFD immediately following the preamble is read, the priority identified by the read SFD is determined, and the first priority is obtained.

[0053] The priority identified by the SFD read is the priority of the service data sent by the currently occupying node.

[0054] If a preamble is detected within the listening window, it indicates that the channel has been occupied by another node. In this case, the local network node does not upload the complete data frame to the CPU for protocol stack parsing. Instead, it directly reads the SFD (Short Frame Decoder) immediately following the preamble using its baseband hardware. Because the SFD is located after the preamble in the frame structure, the baseband hardware can quickly locate and read the SFD.

[0055] After reading the SFD based on the baseband hardware, the priority identified by the read SFD can be further determined based on the baseband hardware. In one possible implementation, the priority identified by the read SFD can be determined based on a pre-configured correspondence table between SFDs and priorities. For example, if the read SFD is 0xB6, and its corresponding low priority is defined in the correspondence table, then the priority identified by the read SFD is determined to be low priority, i.e., the first priority is low priority. If the read SFD is 0xC7, and its corresponding medium priority is defined in the correspondence table, then the priority identified by the read SFD is determined to be medium priority, i.e., the first priority is medium priority.

[0056] Step S103: Compare the second priority with the first priority.

[0057] The second priority is the priority of the business data to be sent by this node, i.e., the target business data.

[0058] During the transmission preparation phase, this network node will determine the priority of the target service data based on its type.

[0059] After acquiring the first priority, the network node uses a hardware comparator based on its baseband hardware to compare the second priority with the first priority to determine their relative importance. For example, if a smaller priority value indicates a lower priority, the system can determine if the second priority value is greater than the first priority value. If the second priority value is greater than the first priority value, then the second priority is higher than the first priority; if the second priority value is less than the first priority value, then the second priority is lower than the first priority. This real-time hardware-level comparison enables preemption decisions to be made within microseconds, providing a basis for subsequent transmission or avoidance control.

[0060] Step S104a: If the second priority is higher than the first priority, then start sending data frames containing preamble, SFD and target service data in sequence.

[0061] When the comparison result shows that the second priority is higher than the first priority, it means that the target service data of this network node has a higher urgency or importance for transmission. This network node determines that it is eligible to preempt and immediately initiates preemptive transmission, directly transmitting the data frame containing the preamble, SFD, and target service data in sequence based on the radio frequency front-end. Due to the use of a hardware triggering mechanism, the delay from the completion of the decision to the start of transmission is extremely low, ensuring that high-priority data can quickly access the channel and achieve low-latency transmission.

[0062] Since the preamble detection, SFD reading and priority determination in steps S101 and S102, the priority comparison in step S103, and the preemptive transmission in this step are all completed in the physical layer hardware (for example, the baseband hardware directly controls the RF front-end to transmit after the decision), without the need for CPU to participate in scheduling, the response delay from detecting the preamble to starting to transmit high-priority data frames is compressed to the microsecond level, ensuring that high-priority service data can be transmitted with extremely low latency by preempting the channel.

[0063] Step S104b: If the second priority is lower than the first priority, then abandon this transmission and enter a silent listening state, waiting for the next time slot cluster of the same function to re-initiate the transmission.

[0064] When the comparison result shows that the second priority is lower than the first priority, it indicates that the service data transmitted by the node currently occupying the channel has a higher priority. To avoid interfering with the transmission of high-priority service data, this network node relinquishes its transmission opportunity and then enters a silent listening state, i.e., it continues to monitor the channel but does not actively initiate transmission until the current functional time slot cluster ends. After the current functional time slot cluster ends, this network node waits until the next similar functional time slot cluster (i.e., time slot resources with the same functional attributes) begins, and then re-executes the above process from the listening window period to attempt transmission again. This avoidance strategy ensures that high-priority service data is transmitted first.

[0065] In this embodiment, network nodes use a unified preamble to achieve consistent channel detection, and use hierarchical SFD to directly complete priority identification and comparison in the physical layer hardware. High-priority network nodes immediately preempt the channel based on the hardware decision result, while low-priority network nodes actively avoid it. The entire process does not require CPU intervention in protocol stack parsing, which significantly reduces access latency and reduces multi-node concurrent conflicts.

[0066] The channel preemption method in wireless ad hoc networks provided by this invention pushes core steps such as preamble detection, SFD reading, priority determination, and priority comparison down to the physical layer hardware for execution. It eliminates the need to upload complete data frames to the CPU for MAC layer protocol stack parsing and queuing scheduling. Compared with the millisecond-level access latency of existing technologies that rely on software frame unpacking and CPU scheduling, it can compress the latency of channel access and preemption decision to the microsecond level, providing a reliable guarantee for low-latency services. Meanwhile, by directly identifying and recognizing service priorities at the physical layer hardware through hierarchical SFD, when multiple nodes generate transmission requests within the same functional time slot cluster, high-priority nodes can immediately preempt the channel based on hardware comparison results, while low-priority nodes actively avoid it within microseconds. This significantly reduces the probability of collisions in multi-node concurrent scenarios. Furthermore, the entire decision-making chain of preamble detection, SFD reading, priority determination, and priority comparison is executed entirely based on physical layer hardware, without CPU involvement, protocol stack parsing, or memory read / write operations caused by frame parsing. Compared to existing technologies where each frame of data requires interrupting the CPU, parsing the protocol stack layer by layer, and repeatedly copying memory and scheduling queues, this invention effectively releases CPU processing resources, significantly reduces the number of interrupt responses and memory accesses, and avoids power consumption overhead caused by frequent CPU wake-ups and memory operations. It saves system overhead in terms of computing resources, memory access, and power consumption, which is particularly beneficial for battery-powered terminal devices.

[0067] As mentioned in the above embodiments, if a preamble is detected in the channel, it is determined that the channel is occupied by other network nodes. The SFD immediately following the preamble is read based on the baseband hardware, and then the priority identified by the read SFD is determined. In some embodiments of this application, the process of determining the priority identified by the read SFD is described.

[0068] In one possible implementation, the process of determining the priority identified by the SFD being read may include:

[0069] Step a1: Based on the pre-built correspondence table between SFDs and priorities, match the read SFDs with the SFDs in the correspondence table.

[0070] The pre-built mapping table between SFDs and priorities is the key configuration data of this invention. It should be noted that the mapping table between SFDs and priorities is not a software-level data structure, but a hardware mapping table. During system initialization, network planning, or node network configuration, the hardware mapping table is loaded and solidified into a readable parameter set in the physical layer hardware of the network nodes. In one optional implementation, the hardware mapping table can be stored in the form of key-value pairs in the dedicated register set of the physical layer hardware or in non-volatile memory. When stored in non-volatile memory, it is loaded into the dedicated register set after system power-on for fast access by the hardware logic.

[0071] The mapping table between SFDs and priorities logically defines a unique mapping between each valid SFD and its assigned priority. For example, as shown in Table 1, SFD=0xB5 corresponds to high priority, SFD=0xA3 corresponds to medium priority, and SFD=0x91 corresponds to low priority. This mapping table is used to implement fast indexing from SFD to priority at the hardware layer. The construction of this mapping table ensures that priority information extraction no longer depends on any protocol stack parsing or CPU computation.

[0072] Table 1. Example of the correspondence between SFD and priority

[0073]

[0074] When matching the read SFD with the corresponding SFDs in the table, the read SFD is compared with each SFD in the table. A match is considered successful if and only if the read SFD is exactly the same as any SFD in the table. The above matching process can be completed based on baseband hardware, without CPU involvement or protocol stack parsing, and can provide matching results in microseconds.

[0075] Step a2: Determine the priority of the SFD that matches the read SFD in the correspondence table as the priority identified by the read SFD.

[0076] After SFD matching is completed, the corresponding priority is extracted from the correspondence table based on the matching results. Specifically, the priority corresponding to the SFD that is the same as the read SFD is extracted from the correspondence table and used as the priority identified by the read SFD.

[0077] For example, if the read SFD (0xB5) matches SFD_H in the corresponding relationship table, and the priority corresponding to SFD_H is high priority, then the high priority corresponding to SFD_H is extracted as the priority identified by the read SFD.

[0078] By using a lookup table mapping method, the SFD detected by the physical layer can be accurately converted into a priority, thereby providing an accurate quantitative basis for subsequent priority comparison and preemption decision, ensuring the accuracy and consistency of hardware-level decision logic.

[0079] As mentioned above, this invention establishes a correspondence between SFDs and priorities through a hardware mapping table. In some preferred embodiments of this application, the correspondence table includes at least high priority, medium priority, and low priority, as well as the corresponding SFD for each priority. This three-tiered priority design effectively controls the size of the hardware mapping table while meeting the needs of most ad hoc network application scenarios, which is beneficial for further reducing the occupation of hardware logical resources and matching latency.

[0080] It is important to note that the high, medium, and low priorities mentioned above are not abstract classification labels, but rather strongly correlated with specific types of service data. This correlation allows network node hardware to accurately infer the urgency or importance of the service data transmitted in the current channel simply by reading the SFD (Service Data Facts).

[0081] In this embodiment, high-priority service data may include one or more of the following types: gateway broadcast data (such as network-wide synchronization instructions, route update announcements, emergency network configuration parameters, etc.), time synchronization data (such as time reference signals, synchronization frames, etc.), perception data (such as radar detection results, target trajectory data, etc.), and control command data (such as aircraft attitude control commands, mission switching commands, etc.). It should be noted that the above-mentioned high-priority service data are merely examples and should not be considered as limiting the scope of protection of this application. In actual deployment, they can be adaptively extended according to the real-time requirements of the services.

[0082] In this embodiment, medium-priority service data mainly includes interaction data between the base station-side terminal and the network access node, such as two-way handshake information, configuration confirmation messages, link status queries and responses, etc. Although this type of data is necessary to maintain normal network throughput, its urgency is lower than that of the aforementioned high-priority service data. Based on this, it is classified as medium priority and configured with corresponding SFDs to ensure that high-priority services are scheduled with absolute priority while effectively balancing the overall network operating efficiency and user experience.

[0083] In this embodiment, low-priority service data includes, but is not limited to, at least one of the following types: ordinary status reporting data (such as device temperature, operating voltage, current operating mode, etc., periodically reported by nodes), and non-real-time data (such as historical data backhaul, log file upload, etc.). This type of data is scheduled for transmission only when channel resources are idle and is configured to avoid resource occupation by high-priority service data to avoid delays affecting urgent services.

[0084] Through the above-mentioned high, medium and low three-level fine division, the present invention constructs a clear and hierarchical service priority system. Based on this system, service data of different priorities are distinguished at the physical layer through different SFDs, and compete for channel resources in strict accordance with the preemption process of steps S101 to S104. This realizes the fine-grained and differentiated scheduling of limited wireless channel resources among services of different importance, effectively improving the overall service quality and operating efficiency of the wireless ad hoc network system.

[0085] Those skilled in the art will understand that the above-described high, medium, and low priorities and their corresponding service data types are merely preferred examples and not limiting examples of this application. Depending on the actual network scale and service requirements, the hardware mapping table of this invention can be configured to support more or fewer priority levels (e.g., four or two levels), and the SFD length and value corresponding to each priority level can be adjusted accordingly; all of this should be considered within the scope of protection of this application.

[0086] In some embodiments of this application, the channel preemption method in the wireless ad hoc network described above may further include: when the network node preempts the channel, if it is detected during the transmission of a data frame that the priority identified by the SFD sent by another network node is higher than the priority identified by the SFD in the data frame sent by the network node, the transmission of the data frame is stopped, and a silent listening state is entered, waiting for the next time slot cluster of the same function to re-initiate the transmission.

[0087] In a wireless mesh ad hoc network system, due to factors such as signal propagation delay and distributed independent decision-making by nodes, a situation may arise where a low-priority node has already occupied an idle channel and started transmitting data before a high-priority node initiates transmission. Therefore, even if the network node has successfully preempted the channel and started transmitting data frames, the possibility of a higher-priority signal appearing later cannot be ruled out. Based on this, this embodiment introduces a real-time monitoring and dynamic backoff mechanism during the transmission process. That is, the network node continuously monitors the channel status during data frame transmission and actively terminates the current transmission to backoff when a higher-priority signal is detected, ensuring priority access for high-priority services.

[0088] Specifically, while radiating signals outward through the radio frequency front-end, this network node utilizes the transmission detection capability of the radio frequency front-end to perform real-time parallel monitoring of the channel status, thereby achieving "same-transmit, same-listen" at the hardware level. When a new SFD is detected in the channel, the SFD is read based on the baseband hardware, the priority of the SFD identifier is determined, and the priority of the SFD identifier is compared in real time with the priority of the SFD identifier in the data frame currently being transmitted by this network node through a hardware comparator.

[0089] If a comparison reveals that the newly appearing SFD identifier has a higher priority than the SFD identifier in the data frame currently being transmitted by this network node, it indicates that higher-priority service data has appeared in the channel. At this point, this network node stops transmitting data frames. Specifically, it controls the RF front-end to shut down the power amplifier to cut off RF energy output, thereby physically terminating the transmission of data frames. Simultaneously, it clears the transmission buffer to ensure that any untransmitted data residue will not affect the next transmission process, and records the preemption status.

[0090] When higher-priority service data appears in the channel, this embodiment physically cuts off the output path of the radio frequency signal through hardware control, completely stopping the interference to the channel within microseconds of the preemption decision. Specifically, the radio frequency front-end responds to the interrupt command issued by the baseband hardware, immediately disconnecting the bias voltage or enable signal of the power amplifier, forcing the transmit link into a high-impedance state or a shutdown state. Compared to simply shutting down the logic power supply or canceling the transmission command layer by layer through the software protocol stack, this physical-level hard shutdown mechanism avoids residual signals caused by software processing delays, effectively eliminating the interference of incompletely stopped radio frequency energy on high-priority data frames, thereby ensuring the instantaneity and cleanliness of the channel handover process.

[0091] The transmit buffer is used to cache the data bit stream waiting to be modulated and transmitted. When a higher priority signal is detected by the baseband hardware, the data that has not yet been transmitted in the transmit buffer is discarded by resetting the signal or clearing the write pointer. This operation not only frees up storage space for the transmission of subsequent new data frames, but also eliminates the risk that old data will be incorrectly read and transmitted in the next functional time slot cluster due to the buffer pointer not being reset.

[0092] Recording the preemption status allows the upper-layer protocol stack to identify the cause of link interruption, thus optimizing subsequent retransmission scheduling decisions. In one possible implementation, a corresponding status flag can be set in a hardware register. Setting this flag marks the interruption due to preemption, and optionally records the preemption timestamp or the priority that triggered the preemption. This status flag is automatically generated and stored by hardware logic without CPU intervention. Based on this status flag, in the scheduling cycle following the previous transmission failure, the network node can quickly identify that the interruption was caused by priority contention leading to proactive avoidance, rather than channel noise or hardware failure. It can then intelligently choose to immediately retransmit in the next time slot cluster with the same function, avoiding time-consuming exponential backoff waiting and improving the efficiency and real-time performance of service transmission in high-density concurrent scenarios.

[0093] After stopping the transmission of data frames, this network node enters a silent listening state. In this state, it no longer attempts to retransmit within the current functional time slot cluster, but waits until the next functional time slot cluster arrives before re-executing the listening and contention process.

[0094] The above strategy ensures that even after a network node successfully preempts the channel and begins transmission, it remains sensitive to higher-priority events. This avoids the blind spot problem caused by the inability to detect channel changes during transmission, as seen in traditional listen-before-send mechanisms, further guaranteeing low-latency transmission of high-priority service data. Since the entire decision-making chain of "send while listening—SFD reading—priority comparison—stop transmission" is completed based on the RF front-end and baseband hardware, without CPU involvement, the response latency from detecting a higher-priority signal to stopping transmission can be controlled within microseconds, ensuring that the channel can be quickly relinquished to truly high-priority service transmissions.

[0095] Considering that multiple network nodes with the same priority may initiate data transmission simultaneously in real-world scenarios, this application also provides a handling strategy for scenarios with conflicts of the same priority. This handling strategy may include:

[0096] Step b1: If a network node detects a conflicting signal of the same priority sent by another node in the channel during the transmission of a data frame, it acquires the Received Signal Strength Indicator (RSSI) value of the conflicting signal of the same priority.

[0097] Among them, the priority identified by the SFD in the same priority conflict signal is the same as the priority identified by the SFD in the data frame sent by this network node.

[0098] In a wireless mesh ad hoc network system, multiple nodes may simultaneously initiate the transmission of service data with the same priority (e.g., multiple drones simultaneously reporting sensing data). In this case, the SFD identifiers in their data frames have the same priority, leading to a priority conflict. Since the SFDs transmitted by each node have the same priority, the winner cannot be directly determined by the SFD priority comparison strategy in steps S101-S104. Therefore, this embodiment introduces a competition strategy based on signal strength for further adjudication.

[0099] While performing data frame transmission tasks, this network node uses the in-transmission monitoring function of the radio frequency front end to monitor the channel status in real time. When it detects the transmission signal of another node in the channel, it first reads the SFD carried by the SFD based on the baseband hardware. If the priority of the read SFD identifier is consistent with the priority of the SFD identifier in the data frame currently being transmitted by this network node, it is determined that a transmission conflict of the same priority has occurred. At this time, instead of immediately forcibly stopping the transmission, a competition mechanism based on signal strength is used to further adjudicate the conflict.

[0100] Specifically, this network node acquires the RSSI value of conflicting signals of the same priority. The RSSI value directly reflects the strength of the opposing signal reaching this network node, thus providing a quantitative basis for subsequent channel usage right determination. Acquiring the RSSI value of conflicting signals of the same priority can be done directly by reading relevant registers in the RF front-end. For example, in wireless communication standards such as IEEE 802.15.4, the RSSI value is usually automatically calculated by the physical layer chip and stored in a specific register. By reading the current value of this register in real time, the strength parameters of conflicting signals of the same priority, such as -65dBm or -72dBm, can be accurately obtained.

[0101] Step b2: Based on the RSSI value and the preset contention avoidance rules, determine whether you have the right to use the channel.

[0102] This step is the channel usage right determination stage based on RSSI values. After obtaining the RSSI values ​​of conflicting signals of the same priority, the network node determines whether it has the right to use the channel based on the RSSI values ​​and in conjunction with preset contention avoidance rules.

[0103] Specifically, this network node compares the RSSI value of a conflicting signal of the same priority with the reference strength of its own transmitted signal. If the RSSI value of the conflicting signal of the same priority is lower than the reference strength of its own transmitted signal, it determines that it has an advantage in signal strength contention and has the right to use the channel. Conversely, if the RSSI value of the conflicting signal of the same priority is higher than the reference strength of its own transmitted signal, it determines that the other party has won the channel contention, and this network node does not have the right to use the channel. The above decision process can be completed based on the hardware comparator of the baseband hardware, without the need for CPU participation or protocol stack parsing, and can output the decision result in microseconds, providing a real-time control basis for subsequent continued transmission or cessation of avoidance.

[0104] Step b3-a: If it is determined that it has the right to use the channel, then continue to complete the transmission of data frames.

[0105] When the competition decision result based on the RSSI value indicates that this network node has the advantage in the signal strength competition, this network node maintains the current transmission state.

[0106] When the decision result of step b2 indicates that this network node has the right to use the channel, it means that in the current conflict of the same priority, the signal strength of this network node is superior to other competing nodes. At this time, this network node maintains the transmission state of the radio frequency front-end, does not perform any interruption or backoff operation, and continues to complete the transmission of the current data frame.

[0107] Step b3-b: If it is determined that it does not have the right to use the channel, it stops sending data frames and enters a silent listening state, waiting for the next time slot cluster with the same function to re-initiate the transmission.

[0108] When the competition decision result based on the RSSI value indicates that this network node is at a disadvantage in the signal strength competition, this network node actively stops transmitting to avoid it.

[0109] When the decision result of step b2 indicates that this network node does not have the right to use the channel, it means that in the current conflict of the same priority, the signal strength of other competing nodes is better than that of this network node. In order to avoid channel congestion caused by continuous conflict, this network node immediately performs a backoff operation. Specifically, based on the baseband hardware control, the RF front-end shuts down the power amplifier to cut off the RF signal output (stops the transmission of the current data frame), and clears the transmission buffer. Then it enters a silent listening state. In the silent listening state, this network node no longer attempts to transmit data in the current functional time slot cluster, but continues to listen to the channel status and waits for the next time slot cluster of the same type to re-initiate transmission.

[0110] By employing the aforementioned processing strategies of immediate stop, silent listening, and delayed retransmission, this embodiment achieves staggered transmission of each node in the time domain under concurrent scenarios with the same priority without the need for complex coordination protocols, effectively resolving conflicts of the same priority.

[0111] RSSI values, as physical layer features, are directly used to determine channel usage rights, freeing the system from the latency limitations of upper-layer protocol processing. The competition avoidance strategy based on RSSI values ​​enables multiple network nodes to quickly determine the winner when they simultaneously initiate data transmission of services with the same priority. This allows for the stable resolution of concurrent conflicts with the same priority in practical applications, thereby enabling the system to maintain efficient channel utilization and orderly communication.

[0112] It should be noted that this network node only performs priority preemption within its own functional time slot cluster, and the priority preemption performed by this network node is only effective within the functional time slot cluster to which this network node belongs.

[0113] In the wireless mesh ad hoc network superframe architecture of this embodiment, the timeline is strictly divided into multiple functionally independent time periods, namely functional time slot clusters. Functional time slot clusters not only represent time segments but also define the types of services allowed to be transmitted within that time period, such as broadcast time slot clusters, time synchronization time slot clusters, data transmission time slot clusters, command transmission time slot clusters, and reply acknowledgment time slot clusters. Each time slot cluster is isolated from each other in the time domain and carries a specific network function. When a network node is in a data transmission time slot cluster, it only participates in channel contention and priority preemption within that time slot cluster. Its decision-making logic, listening behavior, and preemption actions all operate only on the channel state within that data transmission time slot cluster.

[0114] The aforementioned time slot scope limitation ensures that high-priority services can only preempt data within service flows that have the same function. Taking sensing data as an example, it can only preempt data traffic within the time slot cluster where sensing data is transmitted, and cannot cross time slot boundaries to interfere with the transmission of synchronization messages within the time synchronization time slot cluster. By locking the scope of priority preemption, it avoids the blockage or jitter of other critical basic functions (such as network-wide synchronization) caused by sudden bursts of local high-priority traffic, ensuring that each type of service can operate according to its predetermined logic within its dedicated time slot resources.

[0115] Priority preemption between different functional time slot clusters is independent and does not interfere with each other, thus forming a system-level isolation mechanism. Specifically, different functional time slot clusters use independent channel access and contention decision instances. The channel occupancy status, priority conflict results, or preemption behavior within one time slot cluster will not be passed as input conditions to the decision logic of another functional time slot cluster. Even if a network node experiences intense priority preemption within a command transmission time slot cluster, causing a transmission delay, this event will not affect the transmission timing and priority determination of that network node in subsequent broadcast time slot clusters. This dual physical and logical isolation prevents cross-functional domain crosstalk and cascading congestion, enabling the entire network to maintain orderly scheduling and controllable state even when carrying high-density, multi-type services.

[0116] To more clearly illustrate the complete workflow of the channel preemption method in a real-world multi-node concurrent scenario provided by this invention in a wireless ad hoc network, a detailed description will be provided below using a specific low-altitude sensing mesh network application example.

[0117] Assuming a low-altitude sensing mesh network, there are three full-duplex network nodes deployed in the same data exchange time slot cluster. The identity of each network node, the service data to be sent, and its priority configuration are shown in the table below:

[0118] Table 2. Identities, pending service data, priorities, and SFDs of the three network nodes.

[0119]

[0120] All network nodes use a unified 32-bit preamble 0x1A2B3C4D. The specific preemption process is as follows:

[0121] (1) Carrier sensing.

[0122] Each network node detects the presence of a preamble by continuously monitoring the channel based on the radio frequency front end within the listening window (e.g., 10 μs) at the beginning of the functional time slot cluster.

[0123] Assume that at the start of the current functional time slot cluster, all three network nodes have data to be sent, and UAV C (low priority) completes the channel state assessment first and determines that the channel is available, and initiates the transmission first. Ground terminal B (medium priority) completes the channel state assessment later, and UAV A (high priority) completes the channel state assessment last.

[0124] (2) Drone C (low priority) sends first.

[0125] UAV C begins transmitting data frames based on the radio frequency front-end, with the following timing structure: | Preamble: 0x1A2B3C4D | SFD_L: 0x91 | Communication payload: Conventional telemetry data transmission |.

[0126] The drone C is currently in the stage of transmitting preamble and SFD_L based on the radio frequency front-end.

[0127] (3) Ground terminal B detects the preamble and reads the SFD.

[0128] Ground terminal B has not yet started transmitting. Based on the preamble 0x1A2B3C4D detected by its radio frequency front-end, it confirms that the channel has been occupied. Based on the baseband hardware, it reads SFD_L immediately following the preamble and finds out from the hardware mapping table that SFD_L indicates low priority, that is, the service data transmitted by ground terminal B has a low priority.

[0129] Ground terminal B's hardware comparator, based on baseband hardware, compares the priority of its own service data to be transmitted with the low priority of the SFD_L identifier. The comparison finds that the priority of its own service data to be transmitted is higher than the low priority of the SFD_L identifier, thus determining that preemption is allowed, and then initiating transmission. The timing structure of the transmitted data frame is as follows: |Preamble: 0x1A2B3C4D|SFD_M: 0xA3|Communication payload: Target trajectory exchange data|.

[0130] (4) When UAV C encounters channel preemption, it silently avoids it.

[0131] While transmitting data via the radio frequency front-end, UAV C simultaneously listens to the channel. When it detects SFD_M (0xA3) in the channel, it looks up the priority of the SFD_M identifier in the hardware mapping table. The hardware comparator based on the baseband hardware compares the priority of its own transmitted SFD_L identifier with the priority of the SFD_M identifier. The comparison reveals that the priority of the SFD_L identifier is lower than that of the SFD_M identifier. Therefore, it stops transmitting data frames, that is, immediately shuts down the power amplifier, clears the transmission buffer, records the preemption mark, and then switches to silent listening state, waiting for the next time slot cluster with the same function to retransmit.

[0132] (5) Drone A detects the preamble and reads the SFD.

[0133] Drone A detects the preamble within the listening window based on the radio frequency front-end (at this time, ground terminal B is sending the preamble and SFD_M). Based on the baseband hardware, it reads the following SFD_M and looks up the priority in the SFD_M identifier in the hardware mapping table.

[0134] The priority of the service data to be transmitted by UAV A is high priority. The hardware comparator based on the baseband hardware compares the priority of its own service data to be transmitted with the priority of the SFD_M identifier. The comparison finds that the priority of its own service data to be transmitted is higher than the priority of the SFD_M identifier. Therefore, it is determined that preemption is allowed, and then the data frame is transmitted based on the radio frequency front end. The timing structure of the data frame is |Preamble: 0x1A2B3C4D|SFD_H: 0xB5|Communication payload: Emergency flight status reporting data|.

[0135] (6) Ground terminal B encountered channel preemption and silently avoided it.

[0136] During the transmission of a data frame, ground terminal B detects the preamble and SFD_H (0xB5). It checks the hardware mapping table and finds that the SFD_H identifier has a high priority. The hardware comparator based on the baseband hardware compares the priority of its own transmitted SFD_M identifier with the priority of the SFD_H identifier. The comparison reveals that the priority of the SFD_M identifier is lower than that of the SFD_H identifier. Therefore, it stops transmitting the data frame, that is, immediately shuts down the power amplifier, clears the transmission buffer, records the preemption flag, and then enters a silent listening state, waiting for the next time slot cluster with the same function to retransmit.

[0137] (7) UAV A monopolizes the channel to complete high-priority service data transmission.

[0138] Only Drone A remains in the channel transmitting data, and Drone A completes the transmission of the entire data frame.

[0139] The final result is that UAV A obtains the right to use the channel and completes the transmission, ground terminal B encounters channel preemption and waits to retransmit, and UAV C encounters channel preemption and waits to retransmit.

[0140] Throughout the entire process described above, the CPU does not participate in the decision-making. Priority comparison, preemption, and avoidance decisions are all completed based on the RF front-end and baseband hardware, with a total response delay of less than 1 microsecond.

[0141] As can be seen from the complete process examples of the above specific application scenarios, the channel preemption method in wireless ad hoc networks provided by this invention can achieve consistent channel state awareness based on a unified preamble in complex scenarios with multiple nodes transmitting concurrently. Based on hierarchical SFD, it can directly complete the real-time identification and comparison of priorities at the physical layer hardware level. High-priority nodes immediately preempt the channel based on the hardware decision result, and low-priority nodes actively avoid the channel within microseconds. The entire process does not require CPU participation in protocol stack parsing, effectively solving the technical problems of channel preemption relying on software frame decoding, large latency, and poor real-time performance in the prior art. It significantly improves the channel access efficiency and transmission reliability of wireless ad hoc networks in high-density and high-dynamic scenarios.

[0142] The above describes the channel preemption method in a wireless ad hoc network provided by the embodiments of the present invention. The following will describe the apparatus for implementing the above-described channel preemption method in a wireless ad hoc network.

[0143] Please see Figure 2 The diagram shows a schematic of a channel preemption device in a wireless ad hoc network provided by an embodiment of the present invention. The device is applied to any network node in a wireless mesh ad hoc network system and may include a radio frequency front-end 201 and baseband hardware 202.

[0144] The radio frequency front-end 201 is used to continuously detect whether there is a network-wide unified preamble in the channel during the listening window period of the current functional time slot cluster.

[0145] The baseband hardware 202 is used to determine that the channel is idle when the RF front-end does not detect a preamble and the current channel signal strength is 0. It then begins transmitting a data frame containing a preamble, a start-of-frame delimiter (SFD), and target service data in sequence. The SFD indicates the priority of the target service data. When the RF front-end detects a preamble, it determines that the channel is occupied by another network node. It reads the SFD immediately following the preamble, determines the priority identified by the read SFD, obtains the first priority, and compares the second priority with the first priority. The second priority is the priority of the target service data of this network node. If the second priority is higher than the first priority, a data frame containing a preamble, SFD, and target service data in sequence is transmitted. If the second priority is lower than the first priority, the RF front-end is controlled to abandon this transmission, and the network node enters a silent listening state to wait for the next time slot cluster of the same function to re-initiate transmission.

[0146] In one possible implementation, the radio frequency front end 201 is also used to perform channel monitoring during the transmission of data frames.

[0147] The baseband hardware 202 is also used to determine the priority of the new SFD identifier when the radio frequency front-end 201 detects a new SFD, and compare the priority of the new SFD identifier with the priority of the SFD identifier in the data frame currently being transmitted by the radio frequency front-end 201. If the priority of the new SFD identifier is higher than the priority of the SFD identifier in the data frame currently being transmitted by the radio frequency front-end 201, then the radio frequency front-end 201 is controlled to stop transmitting data frames, and the network node is put into a silent listening state, waiting for the next time slot cluster with the same function to re-initiate transmission.

[0148] The RF front-end 201 stops transmitting data frames by: shutting down the power amplifier to stop RF transmission, clearing the transmit buffer, and recording the preempted state.

[0149] In one possible implementation, the baseband hardware 202 is also used for:

[0150] When the radio frequency front-end 201 detects a conflict signal of the same priority sent by another network node in the channel, it acquires the Received Signal Strength Indicator (RSSI) value of the conflict signal of the same priority, wherein the priority identified by the SFD contained in the conflict signal of the same priority is the same as the priority identified by the SFD in the data frame.

[0151] Based on the RSSI value and in conjunction with preset contention avoidance rules, determine whether you have the right to use the channel;

[0152] If it determines that it has the right to use the channel, it controls the radio frequency front-end 201 to continue to complete the transmission of data frames;

[0153] If it determines that it does not have the right to use the channel, it controls the radio frequency front-end 201 to stop sending data frames and puts the network node into a silent listening state, waiting for the next time slot cluster of the same function to re-initiate the transmission.

[0154] In one possible implementation, the process by which the baseband hardware 202 determines the priority identified by the read SFD includes:

[0155] Based on a pre-built mapping table of SFDs and priorities, the read SFDs are matched with the SFDs in the mapping table;

[0156] The priority of the SFD that matches the read SFD in the correspondence table is determined as the priority identified by the read SFD.

[0157] In one possible implementation, the correspondence table contains high priority, medium priority, and low priority, as well as SFDs corresponding to high priority, medium priority, and low priority, with different SFDs corresponding to different priorities.

[0158] In one possible implementation, high-priority business data includes one or more of the following: gateway broadcast data, time synchronization data, sensing data, and control command data;

[0159] Medium-priority service data includes: interaction data between base station-side terminals and network access nodes;

[0160] Low-priority business data includes one or more of the following: normal status reporting data and non-real-time data.

[0161] In one possible implementation, the network node performs priority preemption only within its own functional time slot cluster, and the priority preemption performed by the node is only effective within the functional time slot cluster to which the node belongs; priority preemption between different functional time slot clusters is independent of each other and does not interfere with each other.

[0162] The channel preemption device in the wireless ad hoc network provided in this embodiment of the invention can compress the latency of channel access and preemption decision to the microsecond level, providing reliable protection for low-latency services, significantly reducing the probability of conflict in multi-node concurrent scenarios, and saving system overhead in terms of computing resources, memory access, power consumption, and other dimensions.

[0163] It should also be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. In addition, in the accompanying drawings of the device embodiments provided by this invention, the connection relationship between modules indicates that they have a communication connection, which can be implemented as one or more communication buses or signal lines.

[0164] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the present invention, hardware implementation is more often the preferred implementation method, and the specific hardware structure used by the present invention to implement the same function can be diverse, such as analog circuits, digital circuits, or dedicated circuits.

Claims

1. A channel preemption method in a wireless ad hoc network, characterized in that, The method, applied to any network node in a wireless mesh self-organizing network system, is implemented based on physical layer hardware and includes: During the listening window of the current functional time slot cluster, continuously detect whether there is a network-wide unified preamble in the channel; If the preamble is not detected and the current channel signal strength is 0, the channel is determined to be idle, and a data frame containing the preamble, the start-of-frame delimiter (SFD), and the target service data is sent sequentially, wherein the SFD indicates the priority of the target service data; If the preamble is detected, it is determined that the channel has been occupied by other network nodes. The SFD immediately following the preamble is read, the priority identified by the read SFD is determined, and the first priority is obtained. The second priority is compared with the first priority, where the second priority is the priority of the target service data of this network node; If the second priority is higher than the first priority, then a data frame containing the preamble, SFD and target service data in sequence is sent. If the second priority is lower than the first priority, the current transmission is abandoned, and a silent listening state is entered, waiting for the next time slot cluster of the same function to re-initiate the transmission.

2. The channel preemption method in a wireless ad hoc network according to claim 1, characterized in that, Also includes: If, during the transmission of the data frame, it is detected that the priority identified by the SFD sent by a network node is higher than the priority identified by the SFD in the data frame, the transmission of the data frame is stopped, and a silent listening state is entered, waiting for the next time slot cluster of the same function to re-initiate the transmission.

3. The channel preemption method in a wireless ad hoc network according to claim 2, characterized in that, The step of stopping the transmission of the data frame includes: Turn off the power amplifier to stop RF transmission, clear the transmit buffer, and record the preempted state.

4. The channel preemption method in a wireless ad hoc network according to claim 1, characterized in that, Also includes: During the transmission of the data frame, if a conflict signal of the same priority transmitted by another network node is detected in the channel, the Received Signal Strength Indicator (RSSI) value of the conflict signal of the same priority is obtained, wherein the priority identified by the SFD contained in the conflict signal of the same priority is the same as the priority identified by the SFD in the data frame. Based on the RSSI value and in conjunction with preset contention avoidance rules, determine whether you have the right to use the channel; If it determines that it has the right to use the channel, it continues to complete the transmission of the data frame; If it determines that it does not have the right to use the channel, it stops sending the data frame and enters a silent listening state, waiting for the next time slot cluster of the same function to re-initiate the transmission.

5. The channel preemption method in a wireless ad hoc network according to claim 1, characterized in that, The determination of the priority identified by the SFD being read includes: Based on a pre-built mapping table between SFDs and priorities, the read SFDs are matched with the SFDs in the mapping table; The priority of the SFD that matches the read SFD in the correspondence table is determined as the priority identified by the read SFD.

6. The channel preemption method in a wireless ad hoc network according to claim 1, characterized in that, The correspondence table includes high priority, medium priority and low priority, as well as SFDs corresponding to the high priority, medium priority and low priority, respectively. The SFDs corresponding to different priorities are different.

7. The channel preemption method in a wireless ad hoc network according to claim 6, characterized in that, The high-priority service data includes one or more of the following: gateway broadcast data, time synchronization data, sensing data, and control command data; The medium-priority service data includes: interaction data between the base station-side terminal and the network access node; The low-priority business data includes one or more of the following: normal status reporting data and non-real-time data.

8. The channel preemption method in a wireless ad hoc network according to claim 1, characterized in that, The physical layer hardware includes a radio frequency front-end and baseband hardware; The detection of the preamble and the transmission of the data frame are performed based on the radio frequency front end; The reading of SFDs, priority determination, priority comparison, and decision-making regarding preemptive transmission and collision avoidance are performed based on the baseband hardware.

9. The channel preemption method in a wireless ad hoc network according to claim 1, characterized in that, This network node performs priority preemption only within its own functional time slot cluster, and the priority preemption performed by this node is only effective within the functional time slot cluster to which this node belongs; priority preemption between different functional time slot clusters is independent of each other and does not interfere with each other.

10. A channel preemption device in a wireless ad hoc network, characterized in that, The device is applied to any network node in a wireless mesh self-organizing network system, and includes a radio frequency front-end and baseband hardware; The radio frequency front end is used to continuously detect whether there is a network-wide unified preamble in the channel during the listening window period of the current functional time slot cluster; The baseband hardware is configured to determine that the channel is idle when the preamble is not detected by the radio frequency front-end and the current channel signal strength is 0, and to start transmitting a data frame containing the preamble, a hierarchical frame start descriptor (SFD), and target service data in sequence. The SFD indicates the priority of the target service data. When the preamble is detected by the radio frequency front-end, it is determined that the channel is occupied by other network nodes. The SFD immediately following the preamble is read, and the priority identified by the read SFD is determined to obtain a first priority. A second priority is compared with the first priority, where the second priority is the priority of the target service data of this network node. If the second priority is higher than the first priority, a data frame containing the preamble, SFD, and target service data in sequence is transmitted. If the second priority is lower than the first priority, the radio frequency front-end is controlled to abandon this transmission, and the network node enters a silent listening state to wait for the next time slot cluster of the same function to re-initiate transmission.

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