Half-duplex protocol synchronization control method and system based on out-band digital keying features

Abstract

This application discloses a half-duplex protocol synchronization control method and system based on out-of-band digital keying features, relating to the field of digital communication and network protocols. The method includes: setting a sub-band outside the main data carrier band; generating a pseudo-random sequence containing local node identifiers, timestamps, and channel coordination information, and modulating it into an out-of-band digital keying signal, which is then combined with the main data signal to form a radio frequency signal for transmission; during node transmission, acquiring a mixed signal superimposed on the local transmission component and the external radio frequency signal via split-feed and monitoring the receiving path, and performing out-of-band filtering, demodulation, and weighted cross-correlation detection to suppress local transmission interference, identify external node sequences, obtain arrival time peaks, and parse external identifiers, timestamps, and coordination control information; calculating the time deviation based on the local receiving time, completing clock synchronization correction, and adjusting the transmission state and link time slot scheduling. This improves the synchronization sensing capability and coordination control reliability during transmission.

Description

Technical Field

[0001] This application relates to the field of digital communication and network protocol technology, and in particular to a half-duplex protocol synchronization control method and system based on out-of-band digital keying features. Background Technology

[0002] Half-duplex communication is widely used in low-power wide-area networks (LPWANs), wireless sensor networks, and various IoT terminal communication scenarios due to its relatively simple RF transceiver structure, low hardware cost, and low power consumption. In this communication mode, nodes typically transmit and receive data on the same communication resources. However, due to the limitations of the half-duplex mechanism, nodes often cannot simultaneously perform effective channel listening during transmission. Therefore, as the number of network nodes increases, the level of service concurrency rises, and bursty data streams increase, inter-node timing coordination, transmission avoidance, and collision suppression significantly impact link reliability, throughput performance, and energy efficiency.

[0003] Currently, half-duplex networks typically maintain link order using methods such as carrier sensing, random backoff, polling control, time slot allocation, or intra-frame synchronization fields. These methods are simple to implement in low-load or small-node scenarios, but in dense network environments, hidden nodes, near-simultaneous transmissions, and sudden traffic contention can easily lead to collision accumulation. Nodes frequently perform listening, waiting, backoff, or retransmission operations to reduce collision probability, increasing ineffective channel occupation and control interaction overhead, reducing payload transmission opportunities, and causing node energy consumption to increase with the degree of network contention.

[0004] To improve synchronization and conflict coordination in half-duplex networks, some solutions introduce additional control resources, external time bases, or multi-round interaction mechanisms to help nodes obtain link status, time bases, or send control information. However, these approaches typically require additional hardware modules, consume additional communication resources, or introduce more control interaction processes, leading to increased terminal structure complexity, system deployment costs, and protocol scheduling burden. For low-cost, low-power, and large-scale IoT communication scenarios, these overheads diminish the original advantages of half-duplex communication in terms of hardware simplification and low-power deployment. Summary of the Invention

[0005] This application provides a half-duplex protocol synchronization control method, system, storage medium, computer program product, and electronic device based on out-of-band digital keying features, which at least solves the problem of insufficient link coordination awareness during node transmission in existing half-duplex networks, resulting in limited synchronization control and conflict suppression effects.

[0006] In a first aspect, embodiments of this application provide a half-duplex protocol synchronization control method based on out-of-band digital keying (DOK) features, applied to a half-duplex communication node. The method includes: generating a pseudo-random sequence carrying a local node identifier, local timestamp information, and local channel coordination information; modulating the pseudo-random sequence onto an out-of-band sub-band outside the main data carrier frequency band to obtain an out-of-band DK signal; modulating the main data signal onto the main data carrier frequency band; and merging the modulated main data signal and the out-of-band DK signal into a single radio frequency (RF) signal to be transmitted; during the period when the half-duplex communication node is transmitting the single RF signal, splitting a portion of the power of the RF signal in the transmission path and feeding it to a local monitoring channel; and collecting a mixed RF signal formed by the superposition of the local transmission component formed by the split feeding and the external RF signal transmitted by the external node coupled through the monitoring and receiving path via the monitoring channel; and performing out-of-band filtering on the mixed RF signal received by the monitoring channel. The system performs demodulation processing to extract the corresponding discrete baseband sequence from the mixed radio frequency signal. Using a pre-configured set of reference sequences containing pseudo-random reference sequences corresponding to multiple nodes, weighted cross-correlation detection is performed on the discrete baseband sequence to identify the target out-of-band digital keying sequence transmitted by the external node while suppressing the local transmit component. The system obtains the peak arrival time corresponding to the target out-of-band digital keying sequence and parses the external node identifier, external timestamp information, and external channel coordination information from the target out-of-band digital keying sequence. Combining the external timestamp information, the peak arrival time, and the local reception time recorded based on the local clock reference, the time deviation of the external node relative to the local clock reference is calculated. Synchronization correction and update are performed on the local clock reference based on the time deviation, and the transmission state of the half-duplex communication node is adjusted according to the coordination control signaling parsed from the external channel coordination information to perform link time slot scheduling.

[0007] Secondly, embodiments of this application provide a half-duplex protocol synchronization control system based on out-of-band digital keying (DOK) features, deployed at a half-duplex communication node. The system includes: an out-of-band signal generation unit, used to generate a pseudo-random sequence carrying local node identifier, local timestamp information, and local channel coordination information, and modulate the pseudo-random sequence onto an out-of-band sub-band outside the main data carrier frequency band to obtain an out-of-band DSK signal; a radio frequency (RF) signal combining unit, used to modulate the main data signal onto the main data carrier frequency band and combine the modulated main data signal with the out-of-band DSK signal into a single RF signal to be transmitted; a local transmission monitoring unit, used to feed a portion of the power of the RF signal in the transmission path to a local monitoring channel while the half-duplex communication node is transmitting the single RF signal, and to collect a mixed RF signal formed by the local transmission component generated by the feed and the external RF signal transmitted by an external node coupled through the monitoring and receiving path via the monitoring channel; and an out-of-band signal receiving and processing unit, used to process the mixed RF signal received by the monitoring channel. The system includes: an external frequency band filtering and demodulation processing unit to extract the corresponding discrete baseband sequence from the mixed radio frequency signal; a target sequence identification unit to perform weighted cross-correlation detection on the discrete baseband sequence using a pre-configured reference sequence set containing pseudo-random reference sequences corresponding to multiple nodes, to identify the target out-of-band digital keying sequence sent by the external node while suppressing the local transmit component, to obtain the arrival time peak corresponding to the target out-of-band digital keying sequence, and to parse the external node identifier, external timestamp information, and external channel coordination information from the target out-of-band digital keying sequence; a time deviation calculation unit to calculate the time deviation of the external node relative to the local clock reference by combining the external timestamp information, the arrival time peak, and the local reception time recorded based on the local clock reference; and a clock synchronization and link scheduling unit to perform synchronization correction and update of the local clock reference according to the time deviation, and to adjust the transmission state of the half-duplex communication node according to the coordination control signaling parsed from the external channel coordination information, so as to perform link time slot scheduling.

[0008] Thirdly, an electronic device is provided, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the steps of the half-duplex protocol synchronization control method based on out-of-band digital keying features according to any embodiment of the present application.

[0009] Fourthly, embodiments of this application provide a storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the half-duplex protocol synchronization control method based on out-of-band digital keying features of any embodiment of this application.

[0010] Fifthly, embodiments of this application provide a computer program product, including a computer program / instructions, which, when executed by a processor, implement the steps of the half-duplex protocol synchronization control method based on out-of-band digital keying features of any embodiment of this application.

[0011] The half-duplex protocol synchronization control method and system based on out-of-band digital keying features provided in this application can achieve at least the following technical effects:

[0012] (1) A pseudo-random sequence carrying node identifiers, timestamp information, and channel coordination information is modulated onto an out-of-band sub-band outside the main data carrier frequency band and transmitted in combination with the main data signal, so that protocol synchronization information and link coordination information can be transmitted in parallel with service data. Since this coordination feature is distinguishable from the main data carrier in the frequency domain, the corresponding discrete baseband sequence can be obtained through out-of-band filtering and demodulation, thereby forming coordinated control information that is released synchronously with the transmission process without significantly occupying the main data transmission resources. Furthermore, by feeding part of the radio frequency power in the transmission path to the local monitoring channel during the transmission state, and collecting the mixed radio frequency signal formed by the superposition of the local transmission component and the radio frequency signal of the external node, the half-duplex node can still obtain out-of-band feature observation results related to the transmission behavior of the external node during its own transmission process, thereby enhancing the node's link coordination perception capability during transmission and providing real-time basis for subsequent synchronization correction and scheduling control.

[0013] (2) Weighted cross-correlation detection of discrete baseband sequences is performed using a pre-configured set of pseudo-random reference sequences. The peak value of the sequence correlation, rather than simple energy changes, is used as the basis for identifying external nodes. During the detection process, the interference of local transmission components on the target out-of-band digital keying sequence is suppressed. Since the pseudo-random sequences corresponding to different nodes have distinguishable correlation characteristics, the target sequence transmitted by external nodes can be identified in mixed radio frequency signals, and the external node identifier, external timestamp information, and external channel coordination information can be obtained by parsing. Subsequently, the time deviation is calculated by combining the external timestamp information, the peak arrival time of the target sequence, and the local reception time. This allows the local clock reference to be synchronized and corrected according to the actual observed external transmission characteristics, and the transmission state is adjusted based on the parsed coordination control signaling. This enables node identification, time synchronization, and link time slot scheduling to form a continuous closed loop, improving the targeting of transmission avoidance, time slot arrangement, and collision suppression.

[0014] This technical solution utilizes out-of-band digital keying features for parallel transmission, monitoring channels during transmission, correlation detection and identification based on pseudo-random sequences, and time-deviation-driven synchronous scheduling control. This enables half-duplex communication nodes to obtain the cooperative status and time reference of external nodes while maintaining the continuity of the main data transmission process. Consequently, the transmission timing between nodes becomes more consistent, link scheduling becomes more timely, and overhead such as ineffective waiting, blind backoff, and collision retransmissions is reduced. This improves the link reliability, effective throughput, and energy efficiency of the half-duplex network under multi-node concurrency and bursty service scenarios. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A flowchart illustrating an example of a half-duplex protocol synchronization control method based on out-of-band digital keying features according to an embodiment of this application is shown.

[0017] Figure 2 This document illustrates an example of an operation flowchart for identifying a target out-of-band digital keying sequence sent by an external node in a method according to an embodiment of this application.

[0018] Figure 3 This paper shows an example of an operation flowchart of performing a synchronization correction update on a local clock reference based on a time deviation in a method according to an embodiment of this application;

[0019] Figure 4 A schematic diagram illustrating the system operation mechanism of an example of a half-duplex protocol synchronization control method based on out-of-band digital keying features according to an embodiment of this application is shown.

[0020] Figure 5 A schematic diagram of the joint evaluation and comparison of different methods in terms of normalized throughput and end-to-end latency is shown.

[0021] Figure 6 A schematic diagram showing the comparative experimental simulation results of different methods in terms of network energy efficiency is presented as an example.

[0022] Figure 7 A schematic diagram of a three-dimensional surface verification of an example of the detection robustness and boundary exploration of an out-of-band cooperative sensing link in a strong self-interference environment is shown.

[0023] Figure 8A structural block diagram of an example of a half-duplex protocol synchronization control system based on out-of-band digital keying features according to an embodiment of this application is shown. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] It should be noted that, at the specific protocol implementation level, current technologies mainly revolve around media access avoidance, external time synchronization assistance, and high-precision time synchronization. For example, HD-CSMA / CA (Half-Duplex Carrier Sense Multiple Access with Collision Avoidance) mechanisms typically reduce the probability of simultaneous transmission by listening to the channel state before transmission and combining this with random backoff rules. This type of mechanism is relatively simple to implement in low-load scenarios, but in scenarios with dense node deployments, many hidden nodes, or strong bursts of traffic, pre-transmission listening cannot fully reflect the actual collision risk. Nodes repeatedly performing listening, waiting, backoff, and retransmission processes increases link contention overhead and weakens effective data transmission efficiency.

[0026] To address the challenge of timely control information transmission in half-duplex links, some solutions attempt to introduce independent control resources outside the main data channel. These resources assist in transmitting link status, coordinating information, or sending conflict alerts. While this approach can reduce the occupancy of control frames or synchronization fields within the main data channel to some extent, it typically requires additional frequency resources, dedicated receiving paths, or relatively independent RF front-ends, increasing the complexity of terminal hardware integration, spectrum coordination costs, and deployment and maintenance costs. For IoT terminals designed for low-cost, low-power, and large-scale deployment, the additional overhead from these control resources limits their applicability.

[0027] To address the time slot alignment requirements in low-power wide-area networks (LPWANs), some studies have proposed an external time synchronization scheme combining S-ALOHA (Slotted ALOHA) and FM-RDS (FM-Radio Data System). This scheme distributes time information to nodes via public broadcast signals, enabling nodes to align to a unified time slot boundary and thus improving collision handling in random access scenarios. The advantage of this approach is that it reduces the occupation of communication opportunities by synchronization information within the data channel. However, nodes typically need to possess corresponding broadcast signal reception, demodulation, or time synchronization processing capabilities, which increases the complexity of the terminal structure and the burden of energy management.

[0028] Furthermore, in long-distance or high-precision synchronization scenarios, some current related technologies still rely on the SX1280-TWR (SX1280 Two-Way Ranging) time synchronization approach. This approach utilizes the ranging capability of the RF chip and the round-trip delay estimation mechanism to calculate the propagation delay and the clock deviation between nodes. While this method can achieve high synchronization accuracy under specific hardware platforms and controlled link conditions, it typically relies on multiple rounds of interaction, including request, response, and timestamp exchange. When the timing information provided by a single half-duplex response is limited, multiple consecutive bidirectional ranging processes are required to obtain complete time parameters. This increases the number of air interface control interactions, prolongs the synchronization convergence process, and increases the complexity of the underlying protocol's timing scheduling.

[0029] In summary, current technologies have developed various half-duplex link coordination mechanisms, including HD-CSMA / CA, external timing assistance, and SX1280-TWR. However, different paths typically require trade-offs between conflict avoidance capabilities, synchronization accuracy, hardware complexity, spectrum usage, protocol interaction overhead, and network adaptability. In particular, in low-power, large-scale, and highly competitive IoT communication scenarios, these trade-offs further impact the effective throughput, energy efficiency, and link control stability of half-duplex networks.

[0030] It should be understood that the above description of the relevant technologies is intended only to help the public better understand the inventive spirit and motivation of this application, and is not intended to limit this application. Furthermore, the technical solutions described in the above-mentioned relevant technologies are not prior art, and may also be undisclosed technical solutions, such as those under research or in the laboratory stage.

[0031] The technical solutions in this application, including the collection, storage, use, processing, transmission, provision, and disclosure of users' personal information, comply with relevant laws and regulations and do not violate public order and good morals.

[0032] Figure 1A flowchart illustrating an example of a half-duplex protocol synchronization control method based on out-of-band digital keying features according to an embodiment of this application is shown.

[0033] Regarding the execution subject of the method in the embodiments of this application, it can be any controller or processor with computing or processing capabilities, such as the protocol synchronization controller of a half-duplex communication node, which implements the method of the embodiments of this application by running programs or instructions stored in a storage medium. In some examples, it can be integrated and configured in an electronic device or terminal through software, hardware, or a combination of software and hardware, and the type of terminal or electronic device can be diverse.

[0034] like Figure 1 As shown, in step S110, a pseudo-random sequence carrying local node identifier, local timestamp information and local channel coordination information is generated, and the pseudo-random sequence is modulated to the out-of-band sub-band outside the main data carrier frequency band to obtain an out-of-band digital keying signal.

[0035] Specifically, in half-duplex networking scenarios such as low-power wide-area networks (LPWANs), wireless sensor networks, industrial IoT, campus equipment networking, or vehicle-to-everything (V2X) communication, multiple communication nodes may periodically or burstily transmit service data on the same or adjacent communication resources. For example, sensor nodes in an industrial field may report status data, warehouse or campus mobile devices may periodically broadcast location and control status, and LWAN terminals may upload monitoring data in a low duty cycle mode. For such scenarios, out-of-band digital keying (IDK) signals can be constructed in addition to the main service data, enabling nodes to carry lightweight synchronization and link coordination information while transmitting service data.

[0036] In some embodiments, a half-duplex communication node may include a baseband control module, a protocol control module, a clock reference module, and a radio frequency modulation module. The baseband control module can generate a local node identifier, local timestamp information, and local channel coordination information based on the node state of the current communication cycle. The local node identifier distinguishes the current node from other nodes in the network; the local timestamp information characterizes the local clock reference used by the current node when generating or transmitting out-of-band digital keying signals; and the local channel coordination information can represent information related to the node's current link state, transmission intent, or coordinated control. This information can be encapsulated, delimited, or validated to form a control field that can embed a pseudo-random sequence.

[0037] When generating a pseudo-random sequence, the aforementioned control fields can be embedded into a preset or real-time generated pseudo-random sequence. This gives the pseudo-random sequence both sequence characteristics that are easy to detect and distinguish, and control meanings that can be parsed by external nodes. Thus, after detecting the sequence, external nodes can not only determine that "a certain out-of-band keying signal exists," but also further identify the sending node, obtain information related to the transmission time, and parse the link coordination state. It should be noted that the specific method of generating the pseudo-random sequence can be flexibly configured according to the communication protocol, the number of nodes, the channel environment, and hardware capabilities. This embodiment does not limit it to using a specific sequence structure.

[0038] Subsequently, the modulation and transmission unit modulates the pseudo-random sequence onto an out-of-band sub-band outside the main data carrier frequency band. This out-of-band sub-band can be located adjacent to the main data carrier frequency band or at a narrowband frequency position outside the preset guard interval, as long as it can form a distinguishable carrying region with the main data carrier frequency band in the spectrum. In this way, the out-of-band digital keying signal exists as a cooperative signal accompanying the main data transmission, used to carry node synchronization, identification, and channel cooperation information, without changing the service data carrying method within the main data carrier frequency band. In this way, the half-duplex communication node encapsulates node identity, time reference, and cooperative control status into a unified out-of-band digital keying feature.

[0039] In step S120, the main data signal is modulated onto the main data carrier frequency band, and the modulated main data signal is combined with the out-of-band digital keying signal into a whole radio frequency signal to be transmitted.

[0040] Specifically, the main data signal can be formed from upper-layer application data packets, sensor data, control status data, alarm data, or other service payloads, and modulated onto the main data carrier frequency band according to the modulation method supported by the original communication protocol of the half-duplex communication node. For example, in a low-power wide-area network node, the main data signal can correspond to periodically reported environmental monitoring data; in an industrial IoT node, the main data signal can correspond to equipment operating status, control feedback, or abnormal alarms; in roadside or mobile terminal communication scenarios, the main data signal can correspond to location, speed, control status, or other collaborative information. The above-mentioned service data is still carried by the main data carrier frequency band, maintaining the original main communication link's service transmission function.

[0041] Unlike the main data signal, the out-of-band digital keying (ODS) signal is not primarily intended to carry large volumes of service data. Instead, it exists as a low-power, low-data-rate, identifiable cooperative control component. Functionally, they are distinct: the main data signal transmits the service payload, while the ODS signal provides node identification, time synchronization, and channel coordination status. They are also spectrally distinct: the main data signal resides in the main data carrier band, while the ODS signal resides in an out-of-band sub-band outside the main data carrier band.

[0042] In practical implementation, the modulated main data signal and the out-of-band digital keying signal can be combined into a single radio frequency signal to be transmitted through digital domain synthesis, multiplexing at the digital-to-analog converter front end, RF combining network, power combining structure, or other equivalent methods. During the combining process, the main data signal can maintain its primary transmit power to meet the modulation and demodulation requirements of the service data; at the same time, the out-of-band digital keying signal can be transmitted with the main data signal at a lower power to reduce adjacent band leakage interference to the main data carrier frequency band.

[0043] For example, in an Industrial Internet of Things (IIoT) node, the main data signal can be used to transmit sensor sample values ​​or device control feedback, while the out-of-band digital keying (DOK) signal simultaneously carries the node identifier, transmission timestamp, and link coordination status. These two signals are combined and output as the overall radio frequency (RF) signal in the same physical layer transmission process. In this way, external nodes can perceive the out-of-band coordination status of the local node while it is transmitting service data, without waiting for independent control frames.

[0044] As a result, the main service data and out-of-band collaborative control information are combined into a single overall radio frequency signal and transmitted synchronously. This eliminates the need to configure a complete and independent physical transmission process for the collaborative control information, reduces the overhead of additional control frame transmission and protocol interaction, and ensures that the out-of-band collaborative information has a clear time correspondence with the current main data transmission behavior.

[0045] In step S130, while the half-duplex communication node is in the state of transmitting the overall radio frequency signal, a portion of the power of the radio frequency signal in the transmission path is fed to the local monitoring channel, and the monitoring channel collects the mixed radio frequency signal formed by the local transmission component formed by the split feeding and the external radio frequency signal sent by the external node coupled through the monitoring and receiving path.

[0046] It should be noted that when a half-duplex communication node transmits its entire radio frequency signal, its main transceiver path is usually in the transmitting state, and a conventional receiving link is difficult to use simultaneously for complete monitoring of external channels. In scenarios with dense node deployment or frequent sudden traffic, if the node can only monitor before transmission and cannot continuously sense the status of external nodes during transmission, it is easy to encounter situations where the collaborative status of external nodes cannot be obtained in a timely manner during transmission. Therefore, in this embodiment, a local monitoring channel is set up so that the node can still collect radio frequency inputs for out-of-band collaborative sensing during its own transmission.

[0047] In some embodiments, a directional coupler, a low-power splitter, a coupling sampling network, or other equivalent splitting structure can be configured in the transmit path to feed a small amount of power of the radio frequency signal in the transmit path to the local monitoring channel. The signal component formed by this split feeding is the local transmit component, which represents the coupling or leakage of the current node's own transmitted signal within the monitoring channel. Since this component originates from the local transmit path, its power is typically higher than the signal coupled into the monitoring channel from distant external nodes. Therefore, subsequent detection processes need to consider the impact of the local transmit component on the detection of out-of-band sequences.

[0048] Meanwhile, external radio frequency (RF) signals transmitted by external nodes can enter the local monitoring channel via antenna coupling, residual coupling at the RF front end, the monitoring receiving path, or other equivalent paths. These external RF signals may contain out-of-band digital keying (DKeying) signals emitted by the external nodes, as well as the external nodes' main data signals or other RF components. Because the local transmission component and the external RF signal are superimposed in the monitoring channel, the monitoring channel actually acquires a mixed RF signal. This mixed RF signal can be understood as the monitoring input formed by the combined effects of the local transmission status, the external node's transmission status, and environmental noise.

[0049] For example, in a high-concurrency industrial wireless network, while this node is transmitting device status data, another nearby node may simultaneously transmit out-of-band keying features with link coordination implications. Through its local monitoring channel, this node can acquire mixed radio frequency signals containing these external out-of-band features while its main transmission path continues to operate. Therefore, the node does not need to wait until the current transmission process is completed to learn about the status of external nodes, providing a signal basis for link coordination judgment during transmission.

[0050] Thus, the half-duplex communication node establishes a low-power bypass monitoring path during transmission. This process does not require changing the basic operating mode of the half-duplex main transmit / receive path, but rather obtains additional monitoring input for out-of-band collaborative sensing during transmission, thereby providing the necessary data source for subsequent out-of-band filtering, baseband demodulation, and external node sequence detection.

[0051] In step S140, out-of-band filtering and demodulation processing are performed on the mixed radio frequency signal received by the monitoring channel to extract the corresponding discrete baseband sequence from the mixed radio frequency signal.

[0052] It should be noted that the mixed radio frequency signals acquired by the monitoring channel may contain local transmission components, external node radio frequency signals, main data carrier frequency band components, out-of-band sub-band components, and environmental noise. Directly performing sequence matching on the mixed radio frequency signals would not only be computationally complex but also susceptible to the influence of strong signal components in the main data carrier frequency band. Therefore, out-of-band filtering is first performed to extract the signal components corresponding to the out-of-band sub-band from the mixed radio frequency signals, while suppressing signal components from the main data carrier frequency band and other irrelevant frequency bands.

[0053] In some embodiments, out-of-band filtering can be implemented using an analog bandpass filter, a programmable RF filter, a digital filter, or a combination thereof. The filter's passband can cover the out-of-band subband, and its stopband can cover the main power region of the main data carrier band, as well as other frequency bands that do not participate in out-of-band cooperative sensing. After filtering, subsequent processing focuses primarily on the frequency region carrying out-of-band digital keying features, thereby reducing the impact of strong main service data signals on out-of-band cooperative feature detection.

[0054] After out-of-band filtering, demodulation can be performed on the filtered out-of-band signal. Demodulation can include down-conversion, sampling, symbol synchronization, envelope extraction, phase decision, or other operations matched to the specific digital keying (DKeying) method. For example, when the out-of-band DKeying signal uses amplitude variation to carry sequence information, amplitude or envelope-related demodulation can be used; when phase variation carries sequence information, phase decision or differential decision-related demodulation can be used. The resulting discrete baseband sequence is used to characterize the discrete temporal changes of the out-of-band DKeying features.

[0055] For example, in low-power wide-area networks or wireless sensor networks, out-of-band keying signals emitted by external nodes may have low power and be easily masked by local transmission components. By first performing out-of-band filtering and then matching baseband demodulation, the out-of-band cooperative features originally mixed in the radio frequency signal can be extracted into a discrete baseband sequence that can be analyzed by a digital processing unit. Thus, the mixed radio frequency signal in the monitoring channel is converted into a discrete baseband sequence suitable for digital detection, transforming the out-of-band cooperative sensing problem in the radio frequency domain into a baseband sequence processing problem. This allows subsequent weighted cross-correlation detection to be performed on a clearly defined discrete sequence object, improving the feasibility of out-of-band digital keying sequence recognition by external nodes.

[0056] In step S150, a pre-configured set of reference sequences containing pseudo-random reference sequences corresponding to multiple nodes is used to perform weighted cross-correlation detection on the discrete baseband sequence. This is done to identify the target out-of-band digital keying sequence sent by the external node while suppressing the local transmit component. The arrival time peak corresponding to the target out-of-band digital keying sequence is obtained, and the external node identifier, external timestamp information, and external channel coordination information are parsed from the target out-of-band digital keying sequence.

[0057] Specifically, half-duplex communication nodes can obtain a set of reference sequences during network configuration, protocol initialization, or runtime updates. This set of reference sequences includes pseudo-random reference sequences corresponding to multiple nodes. The pseudo-random reference sequences corresponding to different nodes can have distinguishable sequence characteristics, enabling the receiving side to determine whether the discrete baseband sequence contains an out-of-band digital keying sequence emitted by a certain external node through sequence matching. During detection, the local node performs a sliding match between the discrete baseband sequence and each pseudo-random reference sequence in the set of reference sequences to identify any possible external node sequences.

[0058] Since local nodes may still be in an emission state when performing this detection, residual leakage of local emission components or local out-of-band keying components may exist in the discrete baseband sequence. If all sampling positions are processed with equal weight, the sampling portions with strong local emission residues may adversely affect the correlation detection results. Therefore, a weighted cross-correlation detection method can be adopted, adjusting the contribution of a sampling position in the correlation detection according to the degree to which it is affected by the local emission components. For sampling positions that are strongly affected by local emission components, their contribution to the correlation results can be reduced; for sampling positions that better reflect the out-of-band sequence characteristics of external nodes, their detection contribution is retained.

[0059] During the detection process, when the weighted cross-correlation result between a pseudo-random reference sequence and a discrete baseband sequence forms a correlation peak that satisfies a preset locking condition, the corresponding pseudo-random reference sequence can be identified as the matching reference sequence, and the out-of-band digital keying sequence of the external node corresponding to the matching reference sequence can be identified as the target out-of-band digital keying sequence. The position of this correlation peak on the time axis can be used to characterize the time position of the target out-of-band digital keying sequence arriving at the local node, thus the corresponding arrival time peak can be further obtained.

[0060] After identifying the target out-of-band digital keying (OUTB) sequence, the sequence can be decoded to extract the external node identifier, external timestamp information, and external channel coordination information it carries. For example, in a campus IoT network, the target OIB sequence of an external node can carry its node identifier, the local timestamp when the sequence was sent, and the link coordination status. The local node can then decode and parse the sequence to obtain the external node's identity, time reference, and scheduling-related status. Thus, the OIB sequence is not only used for physical layer detection but is also transformed into structured information that can be used for protocol layer synchronization and scheduling. Even with the presence of local transmit components, the local node can still identify the target OIB sequence sent by the external node and obtain the peak arrival time and external node coordination information. This further transforms the discrete baseband sequence obtained from out-of-band monitoring into node identity, time information, and link coordination status, providing a direct basis for subsequent time deviation calculation and transmission status adjustment.

[0061] In step S160, the time deviation of the external node relative to the local clock reference is calculated by combining the external timestamp information, the peak arrival time, and the local reception time recorded based on the local clock reference.

[0062] Specifically, the external timestamp information represents the remote time information used by the external node when generating or transmitting the target out-of-band digital keying sequence; the arrival time peak represents the corresponding time position or propagation delay information in the detection result when the target out-of-band digital keying sequence arrives at the local node; and the local reception time represents the time recorded by the local node based on the local clock reference when it detects the target out-of-band digital keying sequence. By using the above information in combination, the impact of the remote transmission time, the local reception time, and the signal propagation process on the detection time can be distinguished.

[0063] In some implementations, when weighted cross-correlation detection locks onto a target out-of-band digital keying sequence, the local node can record the local clock reference corresponding to the detection event as the local reception time. Subsequently, the node combines the external timestamp information parsed from the target out-of-band digital keying sequence with the arrival time peak obtained from the correlation peak position to calculate the time deviation of the external node relative to the local clock reference. This time deviation characterizes the relative deviation between the external node's time base and the local clock reference, rather than simply the signal detection time difference.

[0064] For example, in a scenario where multiple sensor nodes transmit data according to an agreed-upon transmission window, if the time reference of an external node is offset relative to the local node, a corresponding time difference will appear between the transmission timestamp of its out-of-band digital keying sequence and the local detection time. The local node can estimate the deviation of the external node relative to its local clock reference by combining the external timestamp, peak arrival time, and local reception time. This deviation can be used to subsequently correct the local scheduling clock, making the understanding of the transmission window boundaries more consistent among multiple nodes. Thus, nodes can obtain inter-node time deviation information using the out-of-band digital keying features accompanying master data transmission without introducing additional independent request-response synchronization interactions. This provides feedback for the synchronization correction of the local clock reference and a time basis for transmission window alignment, status judgment, and time slot scheduling in multi-node half-duplex communication.

[0065] In step S170, the local clock reference is updated with synchronization correction based on the time deviation, and the transmission state of the half-duplex communication node is adjusted according to the cooperative control signaling parsed from the external channel cooperative information in order to perform link time slot scheduling.

[0066] In some implementations, after obtaining the time deviation of the external node relative to the local clock reference, the local clock control unit, protocol control unit, baseband processing unit, or a combination thereof can perform synchronization correction updates on the local clock reference. The local clock reference may include a local logical clock, protocol timing reference, time slot counter, transmission window timer, or other time references used for link scheduling. The purpose of the synchronization correction update is to reduce the time reference deviation between the local node and the external node, enabling the local node to use a more consistent time scale in subsequent link state determination, transmission time selection, and scheduling window control.

[0067] Simultaneously, the parsed external channel coordination information can be further interpreted as coordination control signaling, which reflects the link status, transmission intention, priority status, or other scheduling-related status of external nodes. Local nodes can adjust their transmission status accordingly based on their current state, such as preparing to transmit, transmitting, waiting, or receiving / listening. For example, during the preparation phase, they can determine whether to adjust their local transmission plan based on the coordination control signaling of external nodes; when already in the transmission state, they can decide whether to maintain or change their current transmission status based on the coordination control signaling; and when there is no coordination control signaling affecting local scheduling, they can execute subsequent transmission arrangements based on the synchronized and corrected local clock reference.

[0068] In a typical industrial sensor network example, multiple half-duplex nodes may report data according to a predetermined transmission window. When a node broadcasts its link coordination status via out-of-band digital keying (DOK), other nodes can parse this coordination status before preparing to transmit and determine whether they need to adjust their transmission behavior based on the synchronized time reference. Similarly, in scenarios involving sudden alarms or high-priority services, nodes can also transmit status information affecting scheduling decisions to other nodes through out-of-band coordination information, enabling other nodes to adjust their transmission strategies in a timely manner.

[0069] Here, the results of out-of-band signal generation, monitoring and acquisition, filtering and demodulation, sequence detection and time deviation calculation are closed into the synchronization correction and link time slot scheduling process of the half-duplex communication node. This enables the half-duplex communication node to adjust its own transmission behavior such as sending, waiting, pausing or time slot selection according to the out-of-band coordination status of external nodes, thereby improving the time slot coordination, conflict avoidance capability and link transmission stability in a multi-node half-duplex network.

[0070] Regarding the implementation details of generating the out-of-band digital keying signal in step S110, in some examples of embodiments of this application, firstly, a pseudo-random spreading sequence with a preset symbol length and composed of positive and negative bipolar symbols (e.g., +1 and -1) is selected as the base spreading sequence. The base spreading sequence can be a pseudo-random sequence suitable for binary spreading processing, such as an m-sequence, a Gold sequence, or other sequences that meet the correlation detection requirements after bipolar mapping. The purpose of selecting this type of sequence is to enable the receiving side to obtain a clear correlation peak position in an environment with noise, multipath, and other node signal superposition through correlation detection, thereby providing a basis for the identification and timing of the out-of-band digital keying signal.

[0071] To ensure that the substrate spread spectrum sequence has stable correlation peak characteristics, it can be constrained to meet preset cyclic autocorrelation characteristics. These cyclic autocorrelation characteristics include: forming an autocorrelation peak corresponding to the sequence length in the zero cyclic shift state, and the residual autocorrelation response in the non-zero cyclic shift state not exceeding a preset upper limit for residual autocorrelation.

[0072] For example, suppose the substrate spreading sequence is Its code elements belong to the set of positive and negative binary values, and the sequence length is Then its cyclic autocorrelation function can be expressed as:

[0073] Equation (1)

[0074] in, And in hour, In the formula, The value of the cyclic autocorrelation function. For sequence length, For the first spread spectrum sequence in the base plate The value of each code element Circular shift The code value after each code element This is the cyclic shift amount. This represents the upper limit of the residual autocorrelation corresponding to a non-zero cyclic shift. This is the modulo operator.

[0075] The aforementioned cyclic autocorrelation constraint indicates that when the candidate sequence at the receiving side is aligned with the local reference sequence in the sense of cyclic shift, the correlation operation can generate a significant correlation peak; when there is a non-zero cyclic shift between the two, the correlation response is constrained by the upper limit of residual autocorrelation. Therefore, the impact of multipath echoes, noise disturbances, or misalignment of adjacent sequences on the identification of the main correlation peak can be reduced, allowing out-of-band digital keying signals to still possess detectable sequence characteristics under low power conditions. It should be noted that the constraint on the cyclic autocorrelation characteristics here does not require the use of the exact same sequence structure in all communication scenarios, as long as the sequence used can meet the above requirements for peak value and residual correlation response.

[0076] Then, local timestamp information is generated based on the local clock reference, and the local timestamp information is rolled-encoded through a linear feedback shift register. The local node identifier, the rolled-encoded local timestamp information, and the local channel coordination information are concatenated into the underlying control codeword.

[0077] Specifically, half-duplex communication nodes generate local timestamp information based on a local clock reference. This local timestamp information can originate from an internal hardware counter, protocol timer, synchronization clock module, or other clock unit capable of providing a local time base. To ensure continuous variation of the time field across different transmission cycles, rolling encoding of the local timestamp information can be performed using a linear feedback shift register. This rolling encoding can scramble, cyclically update, or serialize the timestamp field, making the time fields output in different transmission cycles easier to distinguish and reducing the impact of the repetition control field on sequence detection stability.

[0078] Subsequently, the base spread spectrum sequence is converted into a binary spread spectrum code, and the underlying control codeword and the binary spread spectrum code are XORed and spread, which is then mapped to a pseudo-random sequence composed of positive and negative binary symbols.

[0079] In some implementations, the local node identifier, the locally timestamp information after rolling coding, and the local channel coordination information can be concatenated into a low-level control codeword. The local node identifier can be used to identify the identity of the current transmitting node; the locally timestamp information after rolling coding can be used to identify the local time reference corresponding to the out-of-band digital keying signal; and the local channel coordination information can be used to identify information related to the current link state or coordination control. The above fields can be concatenated according to a preset field length, field order, and delimitation method to form a binary low-level control codeword suitable for physical layer spread spectrum processing.

[0080] After obtaining the underlying control codeword, the logical form corresponding to the base spread spectrum sequence can be extracted into a binary spread spectrum code (i.e., a binary code composed of 0s and 1s). This binary spread spectrum code is then used to perform an XOR spread spectrum operation on the underlying control codeword. After completing the XOR operation in the binary field, the spread binary result is remapped into a pseudo-random sequence composed of positive and negative bipolar symbols.

[0081] In one exemplary implementation, let... The first in the underlying control codeword Each binary information bit It is a binary spreading code obtained by mapping from the basis spreading sequence. The preset single-bit spreading factor, The first pseudo-random sequence in the output is the... If there are bipolar symbols, then the XOR spreading and bipolar mapping process can be represented as:

[0082] Equation (2)

[0083] In the formula, The first pseudo-random sequence in the output is the... The value of each bipolar symbol. These are the binary information bits in the underlying control codeword. For floor operation, The preset single-bit spreading factor, Binary spreading code representing periodic calls, This is an XOR operator. Through the above processing, the underlying control codeword is expanded into a bipolar symbol stream with pseudo-random sequence characteristics, enabling the control field to be carried in the out-of-band digital keying signal in spread spectrum form.

[0084] It should be noted that the above equation (2) is an exemplary spread spectrum mapping method. In actual implementation, the spread spectrum factor, code word segmentation method or binary mapping rule can also be equivalently adjusted according to the underlying control codeword length, spread spectrum gain requirements or number of nodes, which can also be used as corresponding alternative implementation methods.

[0085] Subsequently, narrow sub-bands with intervals relative to the main data carrier frequency band are selected on both sides of the center frequency of the main data carrier frequency band as out-of-band sub-bands. According to the preset symbol bit period, differential phase keying or amplitude keying is used to modulate the subcarrier signal in the out-of-band sub-bands based on the pseudo-random sequence to generate out-of-band digital keying signals.

[0086] It should be noted that after generating the pseudo-random sequence, the RF modulation unit can select narrow sub-bands on both sides of the center frequency of the main data carrier band, spaced relative to the main data carrier band, as out-of-band sub-bands. These out-of-band sub-bands can be located outside the guard band of the main data carrier band, or in adjacent narrow band positions that meet the system spectrum planning requirements. By setting the out-of-band sub-bands outside the main data carrier band, the out-of-band digital keying signal and the main data signal can form distinguishable carrying areas in the frequency domain.

[0087] Furthermore, the RF modulation unit can perform digital keying modulation on the subcarrier signal in the out-of-band subband according to a preset symbol bit period and a pseudo-random sequence. Digital keying modulation can employ differential phase keying (DPS) or amplitude keying (ASK). When using DPS, the symbol state in the pseudo-random sequence can be represented by the phase change between adjacent symbols, thereby reducing the dependence on absolute carrier phase recovery. When using ASK, the symbol state in the pseudo-random sequence can be represented by the change in the subcarrier amplitude state, thereby simplifying the amplitude or envelope detection processing at the receiver. Different modulation methods can be selected based on node power consumption, receiver complexity, channel conditions, and hardware capabilities.

[0088] Furthermore, the transmit power of the out-of-band digital keying signal is adjusted so that the proportion of the transmit power of the out-of-band digital keying signal to the total transmit power of the overall radio frequency signal to be transmitted is not greater than a preset power proportion threshold, so as to reduce the adjacent band leakage interference of the out-of-band digital keying signal to the main data carrier frequency band.

[0089] Here, to reduce adjacent-band leakage interference from the out-of-band digital keying signal to the main data carrier frequency band, the transmit power of the out-of-band digital keying signal can be limited. In an exemplary implementation, let the transmit power of the out-of-band digital keying signal be... The total transmit power of the overall radio frequency signal to be transmitted is The preset power percentage threshold is Then, constraints can be imposed:

[0090] Equation (3)

[0091] In the formula, This indicates the transmit power of the out-of-band digital keying signal. This represents the total transmit power of the entire radio frequency signal to be transmitted. This indicates a preset power percentage threshold. This power constraint allows out-of-band digital keying signals to exist as low-power accompanying signals, preventing excessive power from causing excessive adjacent-band leakage to the main data carrier frequency band.

[0092] In some embodiments, the preset power percentage threshold can be configured based on the modulation scheme of the main data carrier band, receiver adjacent channel selectivity, transmit spectrum template, frequency spacing between the out-of-band sub-band and the main data carrier band, and the system's allowable adjacent band leakage level. For example, when the main data service is sensitive to adjacent band leakage, a lower power percentage threshold can be set; when the channel environment is poor and it is necessary to improve the detectability of out-of-band digital keying signals, the power percentage threshold can be appropriately increased within the range that meets the adjacent band leakage requirements. This setting method can achieve a balance between the demodulation quality of the main data signal and the detectability of the out-of-band cooperative signal.

[0093] In this embodiment, a spread spectrum sequence with cyclic autocorrelation constraints is used on the baseband side to carry node identifiers, timestamps, and channel coordination information. This pseudo-random sequence is then modulated onto an out-of-band sub-band outside the main data carrier frequency band on the radio frequency side. This enables the out-of-band digital keying signal to possess distinguishable sequence characteristics, a clear time field, and low-power frequency domain isolation, while reducing adjacent-band leakage interference to the main data carrier frequency band. This improves the reliability of the out-of-band coordination information being identified and resolved during the main data transmission process.

[0094] Figure 2 A flowchart illustrating an example of identifying a target out-of-band digital keying sequence sent by an external node in a method according to an embodiment of this application is shown.

[0095] like Figure 2 As shown, in step S210, the extracted discrete baseband sequence is processed for symbol synchronization according to a preset symbol bit period, and mapped to a discrete sampling point stream corresponding to the symbol position of the pseudo-random reference sequence. Within the sliding observation window, the total short-time observation energy captured by the monitoring channel is measured, and the short-time leakage energy formed by the leakage of the local transmission component to the monitoring channel through the radio frequency front-end isolation is estimated.

[0096] It should be noted that, since the out-of-band digital keying sequence sent by the external node may be affected by propagation delay, multipath spread, sampling clock deviation, and local transmission leakage when it arrives at the local monitoring channel, a preset symbol bit period can be used before performing relevant detection. Symbol synchronization processing is performed on the discrete baseband sequence. This symbol synchronization processing can be achieved through phase-locked loops, early-late gate timing recovery algorithms, interpolation resampling algorithms, or other equivalent symbol timing recovery methods, so that the processed sampling points correspond as closely as possible to the symbol positions of the pseudo-random reference sequence. After synchronization processing, the discrete baseband sequence is mapped to a discrete sampling point stream. ,in, Used to indicate the first The baseband sample value corresponding to each code element position.

[0097] After symbol synchronization is completed, the local baseband processing unit can measure the total short-time observation energy captured by the monitoring channel within a sliding observation window. This total short-time observation energy reflects the energy level formed by the local transmit component, the out-of-band signal from external nodes, and environmental noise within the current observation window. Meanwhile, since the local node is in transmit mode, some radio frequency energy in the local transmit path may leak into the monitoring channel through branching, coupling, or isolation. Therefore, it is also necessary to estimate the short-time leakage energy formed by the local transmit component.

[0098] In some examples, the local transmit baseband sample is known to the local node. This sample can be combined with the isolation of the RF front-end or the leakage channel response to estimate the leakage sample of the local transmit component in the monitoring channel. Let the locally known transmit baseband sample be... The equivalent response of the leakage path is Then the local leak sample can be represented as:

[0099] Equation (4)

[0100] Furthermore, the short-term leakage energy at the corresponding sampling time can be estimated based on the energy accumulation of local leakage samples within a short observation window:

[0101] Equation (5)

[0102] Accordingly, the total energy of short-time observations can be expressed as:

[0103] Equation (6)

[0104] In the formula, To estimate the local leakage sample, For locally known baseband sampling points, The equivalent response of the leakage path. This corresponds to the short-term leakage energy at the sampling time. This represents the total energy of short-term observations at the corresponding sampling time. To focus on the sampling time The set short-term observation window, For discrete sampling time index, This is a discrete tap delay index for the leaked channel. For the sliding sampling index within the observation window, For discrete sample point streams at the sliding sample index The baseband sample value at that location. Through the above processing, energy state parameters that can be obtained on the digital baseband side to distinguish between the effects of local leakage and the contribution of external signal detection can be obtained.

[0105] In step S220, an adaptive suppression weight is dynamically determined for weighted cross-correlation detection based on the transient occupancy of short-time leakage energy relative to the total short-time observation energy. Specifically, the adaptive suppression weight decreases the contribution of the corresponding sampling location to the correlation detection result as the relative proportion of short-time leakage energy in the total short-time observation energy increases, and weight fluctuations in low-energy observation states are suppressed by a preset energy lower limit parameter.

[0106] It should be noted that when a half-duplex node is in transmit mode, some sampling points in the monitoring channel may be strongly affected by local transmit components. If all sampling points are given the same weight in cross-correlation detection, sampling points strongly affected by local leakage may interfere with the formation of correlation peaks in the out-of-band digital keying sequence of external nodes. Therefore, adaptive suppression weights can be dynamically assigned to different sampling positions based on the relative occupancy of short-time leakage energy in the total short-time observation energy.

[0107] In one exemplary implementation, for discrete delay quantities The corresponding observation window can be used to calculate the adaptive suppression weights as follows:

[0108] For example, the adaptive inhibition weights can be dynamically calculated using the following formula:

[0109] Equation (7)

[0110] In the formula, Indicates the discrete delay amount The corresponding observation window Adaptive suppression weights at each code position This represents the estimated short-term leakage energy at the corresponding sampling time. This represents the total short-time observation energy measured at the corresponding sampling time. The preset leakage suppression adjustment factor, This is the preset lower limit parameter for energy.

[0111] In equation (7) above, when the proportion of short-time leakage energy corresponding to a certain sampling location in the total short-time observation energy is relatively high, the weight... The corresponding reduction decreases the contribution of this sampling location to subsequent related detection results; when the proportion of local leakage energy is low, this sampling location can retain a higher correlation contribution. Preset energy lower limit parameter. This method is used to limit weight fluctuations caused by excessively small denominators when the total energy of short-term observations is low, thereby improving the numerical stability of the weight calculation process. In this way, the correlation detection process can adaptively suppress local emission leakage without altering the original reference sequence structure.

[0112] In step S230, the calculated adaptive suppression weights are combined to perform sliding weighted cross-correlation calculations on the discrete sampling point stream and each pseudo-random reference sequence in the reference sequence set, so as to construct sliding weighted cross-correlation functions corresponding to different pseudo-random reference sequences and different discrete delay positions.

[0113] Specifically, the local node can sequentially call candidate pseudo-random reference sequences from the reference sequence set and combine them with the discrete sampling point stream. Perform sliding matching. For the first sequence in the reference sequence set... A pseudo-random reference sequence The following sliding weighted cross-correlation function can be constructed by combining the adaptive suppression weights obtained in step S220:

[0114] Equation (8)

[0115] In the formula, The discrete delay is represented as The weighted cross-correlation function value at time, The symbol length of the preset pseudo-random reference sequence, Indicates the corresponding discrete delay amount The first discrete sampling point stream The value of each sampling point, Indicates the first In the nth pseudo-random reference sequence The value of each code element This represents the adaptive suppression weight for the corresponding observation location.

[0116] In the sliding weighted cross-correlation calculation represented by Equation (8) above, the received discrete sample point stream is weighted and matched with the candidate reference sequence at different discrete delay positions. Compared with equal-weighted cross-correlation, this calculation method introduces a weight related to the local leakage energy into each multiplicative summation term, which reduces the contribution of sampling positions that are more affected by the local emission component to the correlation function, while the sampling positions that better reflect the characteristics of the external node sequence maintain a higher contribution. As a result, the correspondence between the peak value of the correlation function and the target sequence of the external node can be improved.

[0117] In practical implementation, the sliding weighted cross-correlation calculation can be performed by a digital signal processor, a field-programmable gate array (FPGA), a baseband dedicated processing unit (DPLU), or a general-purpose processor. For networks with a large number of nodes, the calculation can be performed one by one according to the reference sequence set. Alternatively, the number of reference sequences participating in the search can be reduced based on the candidate node range, recent communication records, or network configuration results, thereby reducing the real-time computing burden.

[0118] In step S240, the maximum absolute correlation peak of the sliding weighted cross-correlation function is retrieved within the preset correlation search window. When the maximum absolute correlation peak exceeds the preset correlation locking threshold, the pseudo-random reference sequence corresponding to the maximum absolute correlation peak is determined as the matching reference sequence, and the out-of-band digital keying sequence corresponding to the matching reference sequence is determined as the target out-of-band digital keying sequence.

[0119] In some implementations, after obtaining the sliding weighted cross-correlation function Subsequently, the local node can retrieve its maximum absolute correlation peak value within a preset correlation search window. The correlation search window can be determined based on the communication distance range, allowable propagation delay, symbol bit period, node synchronization accuracy, or the maximum detection delay set by the system. Since out-of-band digital keying sequences may use bipolar symbols or phase reversal, using the absolute correlation peak value for decision-making can reduce the impact of sequence polarity reversal or phase state differences on the detection results.

[0120] When the maximum absolute correlation peak corresponding to a candidate reference sequence exceeds a preset correlation locking threshold, it can be determined that there exists an out-of-band digital keying sequence in the discrete baseband sequence that matches the candidate reference sequence. In this case, the pseudo-random reference sequence corresponding to the maximum absolute correlation peak is identified as the matching reference sequence, and the out-of-band digital keying sequence corresponding to the matching reference sequence is identified as the target out-of-band digital keying sequence. The correlation locking threshold can be configured according to the background noise level, desired false detection rate, reference sequence length, transmit power, or system detection reliability requirements.

[0121] After determining the target out-of-band digital keying sequence, the peak arrival time of the target out-of-band digital keying sequence can be obtained based on the discrete delay position corresponding to the maximum absolute correlation peak. For the node identifier, timestamp information, and channel coordination information that need to be parsed subsequently, the decoding unit can perform the corresponding delimitation and field parsing after the target sequence is locked. In this way, both the existence of the target sequence and the time position and node matching relationship related to the target sequence are determined.

[0122] This application's embodiments introduce adaptive suppression weights related to local leakage energy into the digital baseband processing and apply them to sliding cross-correlation detection. This reduces interference from sampling locations heavily affected by local leakage on correlation detection results when a half-duplex node is in transmit mode and a local transmission component exists in the monitoring channel, thereby improving the stability of out-of-band digital keying sequence recognition and the reliability of arrival time peak location for external nodes. Simultaneously, this processing retains the correlation detection framework for pseudo-random reference sequences, facilitating implementation within the digital baseband processing module.

[0123] Regarding the implementation details of obtaining the external node identifier, external timestamp information, and external channel coordination information corresponding to the target out-of-band digital keying sequence in step S150, in some examples of embodiments of this application, firstly, the sliding weighted cross-correlation function is retrieved. The location of the discrete delay corresponding to the maximum absolute correlation peak is obtained and used as the corresponding optimal discrete delay coordinate.

[0124] Here, the relevant search window can be set based on the maximum communication distance between nodes, the system's allowed propagation delay range, the symbol bit period, and the detection and processing delay range. For the first... For a pseudo-random reference sequence, when its corresponding sliding weighted cross-correlation function forms a maximum absolute correlation peak, the discrete delay corresponding to this maximum absolute correlation peak can be determined as the optimal discrete delay coordinate. .

[0125] Specifically, the optimal discrete delay coordinates It can be represented as:

[0126] Equation (9)

[0127] In the formula, To find the discrete delay coordinates corresponding to the maximum absolute value of the sliding weighted cross-correlation function, To find the operator of the independent variable that makes the function reach its maximum value, For the first A pseudo-random reference sequence with discrete delay The corresponding sliding weighted cross-correlation function value is then determined. Through the above peak retrieval, the optimal matching position on the time axis between the received discrete baseband sequence and the local reference sequence can be determined.

[0128] Then, combined with the preset symbol bit period, the optimal discrete delay coordinates are converted into the time delay of the target out-of-band digital keying sequence arriving locally, which is used as the corresponding arrival time peak.

[0129] Specifically, after determining the optimal discrete delay coordinates, a preset sign bit period can be used as a reference. The optimal discrete delay coordinates are converted into the arrival delay component corresponding to the arrival of the target out-of-band digital keying sequence at the local node, and this arrival delay component is used as the peak arrival time. Specifically, it can be expressed as:

[0130] Equation (10)

[0131] In the formula, The peak arrival time of the target out-of-band digital keying sequence. For optimal discrete delay coordinates, The preset symbol bit period is used. This mapping relationship is used to convert the discrete symbol positions where the relevant peaks are located into arrival delay information on a time scale. It should be noted that in embodiments that employ oversampling, interpolation timing recovery, or peak refinement processing, a finer-grained arrival time estimate can be obtained based on the above mapping; when this type of refinement processing is not used, the arrival time peak can be determined according to the time granularity corresponding to the preset symbol bit period.

[0132] Subsequently, the local clock reference corresponding to the transient moment when the maximum absolute correlation peak is captured is recorded as the local reception time. Symbol decision and delimitation decoding are then performed on the identified target out-of-band digital keying sequence to parse out the external node identifier, external channel coordination information, and the remote transmission timestamp as external timestamp information. When the target out-of-band digital keying sequence uses differential phase keying, differential demodulation is performed on the target out-of-band digital keying sequence before delimitation decoding.

[0133] Specifically, when capturing the maximum absolute correlation peak, the local node can record the local clock reference corresponding to the captured event as the local reception time. Local reception time can be recorded by a local hardware counter, protocol timer, baseband processing clock, or other local time reference unit. To ensure consistency in time deviation calculation, local reception time, remote transmission timestamp, and peak arrival time should use the same time unit or be converted using a unified time scale.

[0134] While recording the local reception time, symbol decision and delimitation decoding can be performed on the identified target out-of-band digital keying sequence to parse out the external node identifier, external channel coordination information, and the remote transmission timestamp as external timestamp information. Among them, the external node identifier is used to indicate the source of the target out-of-band digital keying sequence; the external channel coordination information is used to indicate the link coordination status carried by the external node; and the remote transmission timestamp... Used to represent the remote time reference on which an external node generates or sends the target out-of-band digital keying sequence.

[0135] In some implementations, when the target out-of-band digital keying sequence uses differential phase keying, the decoder can first perform differential demodulation on the phase changes between adjacent symbols, and then perform delimited decoding; when the target out-of-band digital keying sequence uses amplitude keying, the decoder can perform amplitude decision based on the symbol amplitude state or envelope state, and then perform delimited decoding. Through decision processing that matches the keying method on the transmitting side, the corresponding control fields can be recovered from the target out-of-band digital keying sequence.

[0136] Accordingly, regarding the implementation details of calculating the time deviation relative to the local clock reference in step S160, in some examples of embodiments of this application, based on the time reference correction relationship between the local reception time, the remote transmission timestamp, and the peak arrival time, the propagation delay effect of the target out-of-band digital keying sequence during its arrival from the external node is eliminated, the transient clock deviation of the external node relative to the local clock reference is obtained, and the transient clock deviation is used as the corresponding time deviation.

[0137] In some implementations, the local reception time is obtained. Remotely sent timestamp and peak arrival time Then, the time deviation of the external node relative to the local clock reference can be calculated. Specifically, the time deviation... It can be represented as:

[0138] Equation (11)

[0139] In the formula, To calculate the time deviation, For local reception time, Send timestamps to remote end The peak arrival time is the value of the peak arrival time. The formula above indicates that the relative deviation of the external node time reference relative to the local clock reference is obtained by subtracting the arrival delay component determined by the position of the relevant peak from the time difference between the local reception time and the remote transmission timestamp.

[0140] It should be noted that the peak arrival time This can be understood as the arrival delay component that needs to be considered between the transmitting-side time reference and the local receiving reference for the target out-of-band digital keying sequence. In practical systems, It can include propagation delay, symbol alignment position, and fixed delay components calibrated in the receiving and processing link. For fixed link delays that can be pre-calibrated, compensation can be made during system initialization or runtime calibration to make the above time deviation calculation results closer to the relative offset of the clock reference between nodes.

[0141] Through the embodiments of this application, a half-duplex communication node can determine the arrival time information using the relevant peak positions of the out-of-band digital keying sequence, and calculate the time deviation between nodes by combining the remote transmission timestamp carried in the target sequence and the local reception time. This allows the time deviation calculation to be completed based on the same target sequence acquisition event, reducing reliance on additional bidirectional synchronization interactions and improving the time consistency between out-of-band synchronization information parsing and time deviation estimation.

[0142] Figure 3 A flowchart illustrating an example of performing a synchronization correction update on a local clock reference based on a time deviation in a method according to an embodiment of this application is shown.

[0143] like Figure 3 As shown, in step S310, the time deviations corresponding to multiple external nodes detected within a preset time collection window are extracted, and the corresponding trust weight coefficients are determined based on the received signal quality indicators of each external node. Here, an external node is a valid external node that successfully identifies the target out-of-band digital keying sequence, and each trust weight coefficient is a positive value.

[0144] In a half-duplex multi-node network environment, a local node may detect multiple out-of-band digital keying sequences sent by external nodes within a single time collection window, and calculate the corresponding time deviations for each. The time collection window can be a single transmission window, multiple transmission windows, a superframe period, or other time range preset by the protocol. External nodes that successfully identify the target out-of-band digital keying sequence and can parse valid timestamp information within this time collection window can be considered valid external nodes, and their corresponding time deviations can be extracted.

[0145] Because the distance, propagation environment, obstruction status, and interference level between different external nodes and the local node may vary, the reliability of the time deviation for each external node is not entirely consistent. Therefore, a trust weight coefficient can be assigned to each external node based on its received signal quality indicators. Received signal quality indicators can include received signal strength, received signal-to-noise ratio, correlation peak amplitude, the ratio between the correlation peak and sidelobes, decoding confidence, or a combination of these indicators. Generally speaking, external nodes with higher received signal quality indicators, clearer correlation peaks, and less noise influence have higher reliability of their corresponding time deviations and can be assigned a larger trust weight coefficient; external nodes with lower received signal quality indicators or unstable correlation peaks can have their corresponding time deviation trust weight reduced accordingly.

[0146] In one implementation, the trust weight coefficients can be determined using a monotonic mapping function. For example, the received signal-to-noise ratio, received signal strength, or correlation peak confidence can be normalized and mapped to positive weights. To avoid zero denominators in subsequent weighted fusion, each trust weight coefficient can be limited to positive values, and only valid external nodes for which the target out-of-band digital keying sequence has been successfully identified are included in the calculation. This reduces the impact of node time deviations, which are significantly affected by strong fading, multipath interference, or transient noise, on local synchronization correction.

[0147] In step S320, based on the time deviation and trust weight coefficient corresponding to each external node, signal quality weighted fusion is performed on multiple time deviations to calculate the weighted average time difference.

[0148] Specifically, let the total number of valid external nodes detected within the time collection window be... , No. The time deviation corresponding to each effective external node is The corresponding trust weight coefficient is Then the weighted average time difference It can be represented as:

[0149] Equation (12)

[0150] In the formula, This is the weighted average time difference. For the detected first The time deviation corresponding to each external node. This represents the total number of valid external nodes detected within the time collection window. For the first Trust weight coefficients are determined by the received signal quality index of each external node.

[0151] In equation (12) above, the time deviations of multiple external nodes are normalized and weighted for fusion. Compared with directly using the time deviation of a single external node, this method can integrate the time references provided by multiple effective external nodes. Compared with a simple arithmetic average, this method allows nodes with higher received signal quality indicators to contribute more to the fusion result, while reducing the impact of nodes with poor received signal quality indicators or low detection confidence on the fusion result. As a result, the obtained weighted average time difference can more smoothly reflect the overall deviation between the local clock reference and the external node time reference within the current time collection window.

[0152] In step S330, the weighted average time difference is used as a feedback input variable, and a preset discrete-time proportional-integral controller is used to perform smooth synchronization updates on the local clock reference. Specifically, the discrete-time proportional-integral controller, based on the normal timekeeping progression of the local clock reference, introduces a proportional correction term corresponding to the current weighted average time difference in the direction of negative feedback correction, and also introduces an integral correction term corresponding to the cumulative state of the weighted average time difference over multiple historical update cycles.

[0153] Specifically, after obtaining the weighted average time difference, instead of directly resetting the local clock reference in a step manner, it can be introduced as a feedback input variable into the discrete-time proportional-integral controller. The proportional correction term generates an immediate correction based on the weighted average time difference within the current time collection window, while the integral correction term generates a continuous correction based on the cumulative state of the weighted average time difference over multiple historical update cycles. Through the cooperation of the proportional and integral correction terms, clock fluctuations caused by single detection errors can be reduced while improving correction responsiveness.

[0154] In one implementation, the state variable of the local clock reference in the next update cycle can be calculated according to the following formula:

[0155] Equation (13)

[0156] In the formula, For the updated local clock reference value, This is the local clock reference value at the current moment. This represents the update step size for the discrete-time proportional-integral controller. The gain is adjusted proportionally. Positive integral adjustment gain, The weighted average time difference calculated for the current update cycle. For the first Weighted average time difference over a historical update period The preset total number of historical windows, This serves as an index for the history window.

[0157] In the above formula (13), This indicates the normal time advance of the local clock reference without applying synchronization correction; This indicates the proportional correction term corresponding to the current deviation; This represents the integral correction term corresponding to the cumulative state of historical deviation.

[0158] It should be noted that the negative feedback correction direction is used in equation (13) to maintain consistency with the definition of time deviation. Specifically, when the weighted average time difference indicates a trend of the local clock reference being larger than the external node time reference, the correction term adjusts the local clock reference in the opposite direction; when it indicates a trend of the local clock reference being relatively smaller, the correction term adjusts in the opposite direction. The proportional adjustment gain and integral adjustment gain can be configured according to the system sampling period, the allowable synchronous convergence speed, clock stability, and network jitter. Furthermore, it should be understood that the integral adjustment gain can be calibrated according to the update step size and the time unit of the integral term, so that the integral correction term has the same time dimension as the local clock reference.

[0159] In step S340, the state variables of the local clock reference in the next update cycle are calculated based on the proportional correction term and the integral correction term. The integral correction term is used to compensate for the inherent frequency offset of the local hardware clock and suppress transient jitter.

[0160] Specifically, the discrete-time proportional-integral (PI) controller can apply a proportional correction term corresponding to the current weighted average time difference (WOT) and an integral correction term from multiple historical update cycles to the local clock reference. The proportional correction term primarily responds to the time deviation detected within the current window, while the integral correction term primarily compensates for the long-term accumulated frequency offset trend of the local hardware clock. For example, when the local node's hardware clock is consistently faster or slower than the external node's time reference due to crystal oscillator errors, the weighted average WOT over multiple consecutive update cycles will exhibit a relatively consistent cumulative trend. The integral correction term can compensate for this trend, thereby reducing the impact of long-term frequency offset on the local clock reference.

[0161] In some implementations, the local clock reference can be a logic clock counter, a protocol timeslot counter, a transmission window timer, or other local time variables used for half-duplex link synchronization control. After calculating the state variables for the next update cycle, the local clock reference can be updated to add a smooth synchronization correction to the normal timekeeping. This avoids the need for abrupt resets of the physical hardware clock and can be achieved by adjusting the logic clock offset, counter step size, or clock compensation register.

[0162] Through the embodiments of this application, when time offset information is provided by multiple external nodes, different time offsets can be weighted and fused according to the quality of the received signal, and the local clock reference can be smoothly updated through a discrete-time proportional-integral controller. This reduces the impact of measurement errors from a single external node or transient channel fluctuations on synchronization correction and compensates for the long-term frequency offset trend of the local hardware clock, thereby improving the stability and continuity of the local clock reference update process.

[0163] Regarding the implementation details of link time slot scheduling in step S170, in some examples of embodiments of this application, firstly, based on the local clock reference updated by synchronization correction, the communication time resources are divided into periodic transmission windows, and each transmission window is discretely divided into multiple micro-time slots of a certain duration, and target transmission time slots are planned for half-duplex communication nodes based on the micro-time slots.

[0164] Specifically, the local clock reference has been synchronized and updated, and therefore can serve as the time base for the local protocol layer to divide transmission windows and micro-slots. In one implementation, the continuous communication time can be divided into periods of... Multiple transmission windows are used, and each transmission window is divided into durations of [duration]. Multiple micro-time slots. The media access control layer can determine the number of micro-time slots that the node needs to occupy based on the length of the data packet to be sent, the modulation and coding scheme, the preset guard interval, and the current service status of the node, and plan the target transmission time slots within one or more transmission windows.

[0165] In one exemplary representation, the target transmission time slot can be represented as a time interval:

[0166] Equation (14)

[0167] In the formula, Indicates the target transmission time slot interval for local planning. Indicates the start time of the target transmission time slot. This indicates the end time of the target transmission time slot. The start and end times mentioned above can be determined based on the synchronized and corrected local clock reference and the micro-slot boundaries. In this way, the local node can plan its transmission behavior in units of discretized time resources, giving the transmission state adjustment a clear time object.

[0168] In the first example, when the half-duplex communication node is in the backoff listening phase of preparing to send data packets, the out-of-band digital keying sequence of the external node is continuously detected through the monitoring channel within a preset sensing time window in order to extract external channel coordination information and parse out the coordination control signaling.

[0169] Specifically, before the local node initiates the transmission of the target data packet, a sensing window can be set before the arrival of the target transmission time slot. This sensing window can be located before the target transmission time slot or, depending on the protocol configuration, cover several candidate micro-time slots. Within this sensing window, the local node detects and decodes the out-of-band sub-band through a monitoring channel to obtain the external channel coordination information carried in the external node's out-of-band digital keying sequence. After parsing, the external channel coordination information can form coordination control signaling, which can be used to characterize the external node's occupancy status, reservation status, priority status, or other states affecting link scheduling.

[0170] Through this processing, the local node can not only determine the channel state based on energy detection during the transmission preparation phase, but also further parse the cooperative control meaning explicitly carried by external nodes. Therefore, the local node can obtain external scheduling information related to the target transmission slot before initiating physical layer transmission, improving the accuracy of pre-transmission scheduling decisions.

[0171] In the second example, if the cooperative control signaling contains a time slot reservation identifier issued by an external node, and the reserved time slot pointed to by the time slot reservation identifier has a time domain overlap conflict with the target transmission time slot planned locally, then the control half-duplex communication node suspends the current transmission plan and enters a backoff waiting state.

[0172] Specifically, if the external node's collaborative control signaling contains reservation time slot information, the local node can parse out the external reservation time slot interval. Let the external reservation time slot interval be:

[0173] Equation (15)

[0174] In the formula, This indicates the time slot interval reserved by the external node. Indicates the start time of the externally reserved time slot. Indicates the end time of the externally reserved time slot. For the local target transmission time slot... The following conditions can be used to determine whether there is a time domain overlap between the two:

[0175] Equation (16)

[0176] In the formula, To find the maximum value operator, This is the minimum value operator. If the above condition is met, it indicates that there is a valid overlap between the local target transmission time slot and the external reserved time slot. If the local node continues to send according to the original plan, it may conflict with the reserved transmission behavior of the external node. In this case, the local node can be controlled to suspend the current transmission plan and enter a backoff waiting state. The backoff waiting state can include delaying transmission, reselecting a candidate time slot, or updating the backoff count according to the protocol configuration.

[0177] Through the above processing, local nodes can avoid conflicts before transmission based on the reservation information of external nodes. Compared with methods that rely solely on random backoff or energy detection, the overlap determination based on the reservation time slot interval can more directly determine whether the target transmission time slot is subject to external occupancy constraints, thereby reducing time domain conflicts caused by hidden nodes or inconsistent transmission timing.

[0178] In the third example, when a half-duplex communication node is in a state of continuously transmitting the overall radio frequency signal, if the cooperative control signaling parsed in real time through the monitoring channel contains an emergency stop instruction issued by a high-priority node, the physical layer transmission interruption logic is triggered to stop the current physical transmission process of the overall radio frequency signal and release the wireless channel resources.

[0179] Specifically, even when the local node has already initiated physical layer transmission, it can still detect out-of-band digital keying sequences sent by external nodes through the local monitoring channel and parse the cooperative control signaling within them. If the parsing result indicates that the external node has sent an emergency abort command with a higher scheduling priority, the local node can determine whether to abort the current transmission process based on the local service priority, the external node priority, and the abort conditions configured in the protocol.

[0180] In one exemplary implementation, the priority of the external node or external cooperative control signaling can be set as follows: The priority of the local current sending service is The physical layer transmit interrupt logic can be triggered when the following conditions are met:

[0181] Equation (17)

[0182] In the formula, Indicates the priority of external node or external coordination control signaling. This indicates the priority of the currently transmitted service. When an emergency abort command is detected and the priority condition is met, the node can stop the transmission of the overall radio frequency signal through the baseband control unit, radio frequency control unit, or physical layer interrupt control unit. Abort processing may include stopping the transmission of main data signals, turning off or reducing radio frequency power output, stopping the transmission of current out-of-band digital keying signals, or switching the local state machine to a waiting state.

[0183] It should be noted that the above priority determination is an exemplary implementation. In other implementations, the decision to trigger a transmission interruption can also be determined based on service type, network management policy, node role, emergency status flag, or other protocol rules, so that even if the local node is in a transmission state, it can adjust its current physical layer transmission behavior in a timely manner according to out-of-band cooperative control signaling.

[0184] In the fourth example, if no occupancy or reservation-type cooperative control signaling that overlaps with the target transmission time slot is parsed within the preset perception time window, the authorized half-duplex communication node initiates physical layer transmission operation within the target transmission time slot and carries the local channel cooperative information configured as a local transmission reservation indication in the out-of-band digital keying signal, which is then transmitted to the external node along with the overall radio frequency signal.

[0185] Specifically, when a local node does not detect any external reservation or occupancy information that overlaps with or conflicts with the target transmission time slot within the sensing time window, it can be assumed that the current local transmission plan is not restricted by the detected external cooperative control signaling. In this case, the media access control layer can issue a transmission authorization to the physical layer, enabling the physical layer to initiate overall radio frequency signal transmission within the target transmission time slot.

[0186] When initiating transmission, the local node can configure a local transmission reservation indication as part of the local channel coordination information and transmit it along with the overall radio frequency signal, carried in the out-of-band digital keying signal. The local transmission reservation indication may include time resources that the node is about to occupy or is currently occupying, transmission status, or other coordination information related to the local transmission behavior. After receiving the out-of-band digital keying signal, the external node can parse the local channel coordination information and update its own link state judgment accordingly.

[0187] In the above overlap determination, if for a certain external reservation interval:

[0188] Equation (18)

[0189] This indicates that there is no effective overlap between the local target transmission time slot and the external reserved time slot. If there is no effective overlap between the external occupancy-type or reservation-type cooperative control signaling detected within the sensing time window, local transmission authorization can be executed. It should be noted that the above judgment can be performed on one external node or on multiple external nodes separately, and local transmission is authorized only when all relevant external time slots do not conflict with the local target transmission time slot.

[0190] Through the embodiments of this application, pre-transmission conflict judgment is performed based on the synchronized micro-slot time resources, and the current transmission state is adjusted according to the external cooperative control signaling during transmission. This enables the local node to form a clear state switching logic between target transmission slot selection, transmission plan suspension, physical transmission abort and transmission authorization, reducing the probability of conflict between local transmission behavior and the reservation or occupation state of external nodes, and improving the determinism and stability of the half-duplex link slot scheduling process.

[0191] In some examples of embodiments of this application, after identifying the target out-of-band digital keying sequence sent by the external node in step S150, a closed-loop adaptive feedback control operation can be performed on the out-of-band cooperative sensing link. The closed-loop adaptive feedback control operation can include receiving signal-to-noise ratio calculation, detection success probability estimation, threshold comparison, and adjustment of out-of-band transmit power and detection parameters.

[0192] First, the received signal power of the monitoring channel corresponding to the out-of-band digital keying sequence of the target within the current observation window is measured, and the average power of the floor noise under the current environment is estimated in order to calculate the real-time received signal-to-noise ratio of the out-of-band cooperative sensing link.

[0193] Specifically, after the target out-of-band digital keying sequence is identified, its received signal power can be determined based on the out-of-band subband energy corresponding to the target sequence within the observation window. The received signal power can be obtained through energy detection, correlation peak amplitude conversion, narrowband power integration, or other equivalent methods. Simultaneously, the average floor noise power can be estimated within signal gaps where the target sequence is not detected, adjacent guard bands, or preset noise observation windows. The average floor noise power can include thermal noise, environmental noise, residual local leakage, and other background interference components not identified as the target sequence.

[0194] In one implementation, the real-time received signal-to-noise ratio (SNR) can be obtained based on the ratio between the received signal power and the average power of the floor noise. This real-time SNR can be calculated using a linear scale or a decibel scale, but in the subsequent detection probability response model, it should use the same SNR scale as the demodulation SNR threshold. In this way, the node can obtain the reception quality indicators of the current out-of-band cooperative sensing link at the physical layer.

[0195] Subsequently, the real-time received signal-to-noise ratio (SNR) is input into a preset detection probability response model to obtain an estimate of the detection success probability of the out-of-band cooperative sensing link under the current channel conditions. The detection probability response model is used to characterize the relationship between the real-time received SNR and the demodulated SNR threshold, and to make the estimated detection success probability increase as the real-time received SNR increases.

[0196] In some examples, the detection probability response model can be represented as:

[0197] Equation (19)

[0198] In the formula, This is an estimate of the probability of successful detection. Let SNR be a natural constant, and SNR be the calculated real-time received signal-to-noise ratio. These are the model fitting constants. The demodulated signal-to-noise ratio (SNR) threshold parameter is obtained based on the monitoring channel noise level, RF front-end isolation, and demodulation method. Among them, SNR and... The same signal-to-noise ratio scale is used.

[0199] In the above formula (19), This represents the margin of the current real-time received signal-to-noise ratio (SNR) relative to the demodulated SNR threshold. When the real-time received SNR is higher than the demodulated SNR threshold, the estimated probability of successful detection increases with the increase of the SNR margin; when the real-time received SNR is lower than the demodulated SNR threshold, the estimated probability of successful detection decreases accordingly. Parameter This is used to adjust the slope of the response curve, enabling the model to adapt to different channel fading conditions, demodulation methods, or hardware reception characteristics. Through this model, the physical layer signal-to-noise ratio can be converted into a detection reliability indicator that is easy to control and judge.

[0200] Next, the estimated success probability is compared with the system's preset target detection probability threshold. On the one hand, when the estimated success probability is lower than the target detection probability threshold, a weak signal enhancement control mechanism is triggered. This controls the half-duplex communication node to increase the out-of-band digital keying signal's transmit power in the overall radio frequency signal during the next transmission cycle, and / or adjusts the leakage suppression adjustment factor when calculating the adaptive suppression weight according to preset adjustment rules. This improves the detectability of subsequent cooperative signaling sent by the half-duplex communication node by external nodes and the monitoring channel's adaptability to detecting external cooperative signaling.

[0201] Specifically, when triggering weak signal enhancement modulation, the half-duplex communication node can be controlled to increase the transmit power of the out-of-band digital keying signal in the overall radio frequency signal during the next transmission cycle, thereby improving the detectability of subsequent out-of-band cooperative signaling transmitted by this node by external nodes. Simultaneously, or alternatively, the leakage suppression adjustment factor used in calculating the adaptive suppression weight can be adjusted according to a preset adjustment rule. This improves the local monitoring channel's adaptability to external collaborative signaling detection. Preset adjustment rules can be set based on the reasons for low detection probability; for example, enhancing leakage suppression when local leakage has a strong impact, or appropriately retaining more effective sampling contribution when the overall external signal is weak.

[0202] On the other hand, when the estimated probability of successful detection is higher than the preset power reduction threshold, where the power reduction threshold is higher than the target detection probability threshold, the energy-saving backoff control mechanism is triggered, and the transmission power of the out-of-band digital keying signal is reduced according to the preset attenuation ratio, so as to reduce the out-of-band cooperative transmission energy consumption of the half-duplex communication node while meeting the reliability requirements of cooperative signaling detection.

[0203] Specifically, when the estimated success probability of detection is higher than a preset power reduction threshold, it can be determined that the current out-of-band cooperative sensing link has a high detection margin. The power reduction threshold is higher than the target detection probability threshold, used to set a power fallback condition above the target detection probability threshold to avoid frequent adjustments as soon as the target threshold is reached. At this time, an energy-saving backoff control operation can be triggered, reducing the transmission power of the out-of-band digital keying signal according to a preset attenuation ratio, thereby reducing the out-of-band cooperative transmission power consumption of the half-duplex communication node while meeting the reliability requirements of cooperative signaling detection.

[0204] On the other hand, when the estimated probability of successful detection is not lower than the target detection probability threshold and not higher than the power reduction threshold, the transmit power and leakage suppression factor of the current out-of-band digital keying signal are maintained. .

[0205] Specifically, when the estimated success probability of detection is not lower than the target detection probability threshold and not higher than the power down-adjustment threshold, the current out-of-band digital keying signal transmit power and leakage suppression adjustment factor can be maintained. This interval can serve as a parameter holding interval, preventing frequent adjustments to transmit power and detection parameters when the system's detection reliability meets requirements but the power reduction condition has not yet been met. This approach reduces the impact of repeated parameter switching on link stability under critical channel conditions.

[0206] In some embodiments, the transmit power adjustment of the out-of-band digital keying signal can be subject to a preset power percentage threshold, transmit spectrum template, adjacent band leakage limitation, or node power consumption budget constraint. That is, even if the estimated success probability of detection is lower than the target detection probability threshold, the system can adjust the transmit power of the out-of-band digital keying signal within the allowable power range to avoid adverse effects on the main data carrier band or adjacent nodes due to excessive increase in out-of-band power. Correspondingly, the leakage suppression adjustment factor... The adjustment can also be subject to preset upper and lower limits to ensure the stability of the adaptive suppression weight calculation process.

[0207] Through the embodiments of this application, a half-duplex communication node can estimate the success probability of detecting a target out-of-band digital keying sequence based on the real-time received signal-to-noise ratio of the out-of-band cooperative sensing link, and adjust the transmit power and adaptive suppression parameters of the out-of-band digital keying signal based on the threshold comparison results. This improves the detectability of cooperative signaling under poor channel conditions, reduces unnecessary out-of-band transmit power consumption under good channel conditions, and reduces fluctuations caused by frequent adjustments through parameter holding intervals.

[0208] Figure 4 A schematic diagram illustrating the system operation mechanism of an example of a half-duplex protocol synchronization control method based on out-of-band digital keying features according to an embodiment of this application is shown.

[0209] like Figure 4 As shown, the system operation mechanism can be functionally divided into an input area, a core processing area, a scheduling and control area, and an output result area. The input area collects the mixed RF signal stream, the local clock reference, and the pseudo-random keying sequence, and inputs them as basic observation parameters to subsequent processing modules. The core processing area includes an out-of-band filtering and demodulation module, a weighted correlation detection module, and a clock offset estimation module. The out-of-band filtering and demodulation module removes main carrier interference from the mixed RF signal and extracts the discrete baseband sequence. The weighted correlation detection module uses an adaptive suppression algorithm to identify the target feature sequence sent by external nodes. The clock offset estimation module quantifies the time offset of external nodes relative to the local clock.

[0210] The scheduling and control area includes a half-duplex state control module and an adaptive power and link adjustment module. The half-duplex state control module executes operations such as link time slot scheduling, backoff waiting, or transmit interruption based on the state constraints output from the core processing area. The adaptive power and link adjustment module updates parameters based on deviation data and applies the adjustment parameters to the weighted correlation detection module in real time through a dynamic closed-loop feedback path to achieve dynamic optimization of detection sensitivity. Finally, the output results area presents the synchronized network clock and the cooperatively scheduled half-duplex link, demonstrating the processing results of the synchronization control method in terms of time base alignment and channel conflict suppression.

[0211] To verify the effectiveness and boundary performance of the proposed method under real physical constraints, this embodiment constructs a cross-layer discrete event simulation model based on MATLAB (responsible for physical layer signal processing) and NS-3 (responsible for MAC layer protocol scheduling). Regarding network topology and service model settings, the simulation randomly deploys half-duplex communication nodes within a 500 m × 500 m area and uses a Poisson process to trigger packet generation. The simulation test uses "normalized network load" (i.e., the ratio of total concurrent data volume to channel capacity per unit time) as the core independent variable to evaluate the differences in system horizontal performance under different network congestion levels.

[0212] In terms of physical channel and hardware parameter configuration, the simulation employs a Rayleigh fading channel superimposed with Gaussian white noise to realistically simulate multipath effects in complex environments such as urban IoT. For the local monitoring channel, the hardware isolation of the RF front-end splitter is calibrated to 30 dB; and the transmit power of the out-of-band digital keying signal is dynamically anchored to 4% of the main data carrier power, thereby incorporating a theoretical loss of approximately 0.17 dB in the equivalent isotropically radiated power (EIRP) of the main signal. Furthermore, to ensure the objectivity and rigor of the simulation, the energy consumption and latency evaluation of the proposed scheme strictly includes the additional digital signal processing (DSP) latency (approximately 2 milliseconds / packet) and the corresponding dynamic computational power consumption (approximately 12 mW) resulting from the execution of weighted cross-correlation detection and adaptive weight calculation.

[0213] To conduct a comparative evaluation of horizontal performance, this simulation sets up two benchmark schemes: the first is the traditional benchmark HD-CSMA scheme, which adopts the traditional half-duplex CSMA / CA protocol and enables random exponential backoff, lacking out-of-band cooperative sensing and collision detection capabilities; the second is the out-of-band control channel (OB-CC) scheme, which introduces dual RF front-ends based on existing technologies, and performs collision alerts and clearance control by transmitting pulses in completely independent frequency bands. In contrast, the scheme proposed in this application (i.e., the OB-DK scheme identified in the simulation verification) uses out-of-band digital keying features and a weighted cross-correlation detection algorithm to complete clock synchronization and real-time link slot scheduling control under a single RF front-end architecture.

[0214] Figure 5The diagram illustrates the simulation results of a joint evaluation comparing different methods in terms of normalized throughput and end-to-end latency. The horizontal axis represents the normalized network load, which is the ratio of the total concurrent data volume to the channel's maximum capacity per unit time, ranging from 0.1 to 1.0. The left vertical axis represents the normalized throughput with a 95% confidence interval, shown as a line graph. The right vertical axis represents the end-to-end latency, shown as a bar chart.

[0215] like Figure 5 As shown, under low network load conditions, i.e., when the normalized load is less than 0.2, the proposed out-of-band digital keying feature-based scheme, namely the OB-DK scheme, shows little difference in normalized throughput compared to the traditional half-duplex baseline scheme HD-CSMA and the out-of-band control channel scheme OB-CC. Within this load range, the end-to-end latency of the proposed scheme is slightly higher than that of the HD-CSMA scheme. This is mainly because the proposed scheme introduces out-of-band digital keying signal generation, monitoring channel processing, and weighted cross-correlation detection, thus incurring certain physical layer processing and baseband computation overhead compared to the baseline scheme that does not perform out-of-band cooperative detection.

[0216] As the normalized network load continues to increase, especially after exceeding 0.4, the throughput of the HD-CSMA scheme begins to decline significantly, while the end-to-end latency increases rapidly, indicating that it is significantly affected by hidden node conflicts and retransmission overhead in high-density contention access scenarios. The OB-CC scheme also shows a trend of decreasing throughput and increasing latency in the medium-to-high load range, suggesting that the independent control channel may still be limited by control interaction congestion under high concurrency conditions. In contrast, the OB-DK scheme of this application maintains a relatively high normalized throughput in the high load range, and the increase in end-to-end latency is relatively small.

[0217] Under extremely high load conditions where the normalized load is close to 1.0, such as Figure 5 As shown in the right-hand region, the OB-DK scheme of this application can still maintain an effective normalized throughput of approximately 0.65, which is significantly higher than the HD-CSMA and OB-CC schemes. Simultaneously, the end-to-end latency of this application's scheme is lower than the two comparative schemes, indicating that by combining out-of-band digital keying signals, local monitoring channels, and weighted cross-correlation detection, the ability to perceive the cooperative state of external nodes in high-density half-duplex networks can be improved, and the link time slot scheduling effect can be enhanced. Simulation results show that the scheme of this application has good anti-collision capability and transmission stability under high-concurrency load conditions.

[0218] Figure 6 A schematic diagram of a comparative experimental simulation showing the effect of different methods on network energy efficiency is shown. Figure 6The horizontal axis represents the number of nodes in the network, and the vertical axis uses a logarithmic scale to represent the average total energy consumption per successfully transmitted byte of payload, measured in mJ / Byte. This evaluation metric comprehensively considers the energy consumption generated by node sleep, listening, sending, collision retransmission, and underlying digital signal processing calculations.

[0219] like Figure 6 As shown in the figure, the traditional half-duplex CSMA baseline scheme, the out-of-band control channel scheme, and the synchronization control scheme based on out-of-band digital keying features proposed in this application are compared. The traditional half-duplex CSMA baseline scheme is identified as the baseline HD-CSMA, the out-of-band control channel scheme as the OB-CC scheme, and the scheme proposed in this application as the OB-DK scheme. In sparse network scenarios with 10 to 50 nodes, due to the high channel idle rate and low probability of collisions between nodes, the baseline HD-CSMA scheme exhibits relatively lower energy consumption per unit of successful transmission because it does not require maintaining a local monitoring channel or performing out-of-band cooperative detection processing. In contrast, the OB-DK scheme of this application, due to the need to maintain a monitoring channel and perform baseband processing such as weighted cross-correlation detection, exhibits a certain increase in baseband energy consumption in the low node count range.

[0220] As the number of network nodes continues to increase, the impact of inter-node contention for access and collision retransmissions on system energy consumption gradually increases. For example... Figure 6 As shown, when the number of nodes increases to a high level, the energy consumption per unit successful transmission of the benchmark HD-CSMA scheme increases rapidly, indicating that under high-density networking conditions, collision retransmission overhead significantly affects energy efficiency. The OB-CC scheme also has relatively high overall energy consumption due to the need to maintain an additional control link. In contrast, the OB-DK scheme of this application reduces the impact of invalid transmissions and full-packet collision retransmissions on energy consumption in high-density scenarios by combining out-of-band digital keying signals, local monitoring channels, and weighted cross-correlation detection. Therefore, the increase in energy consumption per unit successful transmission with the increase in the number of nodes is relatively small.

[0221] In high-density network scenarios with nearly 200 nodes, the energy consumption per successful transmission of the OB-DK scheme in this application is significantly lower than that of the benchmark HD-CSMA scheme and lower than the energy consumption level of the OB-CC scheme. This result indicates that although the proposed scheme introduces certain monitoring and baseband processing overhead in low-load or sparse node scenarios, it can improve overall energy efficiency by reducing collision retransmission overhead in network environments with a large number of nodes and a high probability of collisions, demonstrating good applicability to large-scale half-duplex networking.

[0222] Figure 7A 3D surface plot illustrates an example of detection robustness and boundary exploration for an out-of-band cooperative sensing link in a strong self-interference environment. This plot shows the joint response relationship between the self-interference cancellation ratio (SIR), the ambient signal-to-noise ratio (SNR), and the detection probability. The units for SIR and SNR are dB, and the detection probability is labeled in the plot. It is used to characterize the probability level of successful detection of out-of-band digital keying sequences in the embodiments of this application (i.e., the detection success probability estimate of this application). ).

[0223] like Figure 7 As shown, the detection probability of the out-of-band cooperative sensing link is relatively low when the environmental signal-to-noise ratio (SNR) is low; as the SNR increases, the detection probability gradually increases and tends to stabilize. Meanwhile, under a higher self-interference cancellation ratio, the influence of the local emission component on the monitoring channel is further weakened, which is beneficial to improving the detection reliability of the external out-of-band digital keying sequence. This reflects that the detection probability is simultaneously affected by both the environmental SNR and the self-interference suppression capability.

[0224] exist Figure 7 At the typical operating condition observation point shown, when the self-interference cancellation ratio is approximately 30 dB and the environmental signal-to-noise ratio of the out-of-band signal is approximately 2 dB, the detection probability can still be maintained above 85%. The corresponding location in the figure is marked as follows. The results indicate that, in the presence of local emission remnants in the monitoring channel, introducing weighted cross-correlation detection processing based on transient energy occupancy can effectively improve the detection stability of out-of-band digital keying sequences under strong self-interference conditions.

[0225] also, Figure 7 The study also revealed that the detection probability tends to decrease when the environmental signal-to-noise ratio is low or the self-interference cancellation capability is insufficient, indicating that the out-of-band cooperative sensing link is still constrained by factors such as channel noise, residual self-interference, and hardware isolation capabilities. In practical implementation, the power, sequence configuration, or detection parameters of the out-of-band digital keying signal can be adaptively adjusted based on the channel noise level, changes in detection probability, and the system's allowable out-of-band overhead to reduce the risk of false detections and missed detections under low signal-to-noise ratio or strong self-interference conditions.

[0226] according to Figure 7 The simulation results show that the proposed scheme can maintain a good out-of-band sequence detection probability under typical self-interference suppression conditions, and its detection performance exhibits a clear response relationship with changes in the environmental signal-to-noise ratio and self-interference cancellation ratio. These results verify the robustness of weighted cross-correlation detection processing in strong self-interference half-duplex communication scenarios.

[0227] Based on the joint simulation results of the physical and network layers, under high load conditions with a normalized load close to 1.0, the method provided in this application can still maintain an effective throughput of approximately 65%. Compared with the traditional HD-CSMA scheme, which is prone to significant throughput degradation under congestion, this method demonstrates better anti-collision capability in high-density networks. Regarding energy efficiency, although the system experiences a certain increase in baseline power consumption under low load scenarios due to maintaining the operation of the monitoring channel and performing out-of-band detection processing, in a large-scale network of 200 nodes, by reducing invalid transmissions and collision retransmission overhead, the energy consumption per byte of successful transmission is significantly reduced compared to the baseline HD-CSMA scheme, demonstrating energy efficiency advantages under dense networking conditions. Furthermore, under a typical self-interference cancellation ratio of 30dB, by applying a weighted cross-correlation detection algorithm, the system can still maintain a detection probability of over 85% when the signal-to-noise ratio of the out-of-band signal is as low as 2dB. At the same time, the impact of the out-of-band digital keying signal on the equivalent omnidirectional radiation power of the main signal and the power consumption of the baseband processing are both kept at a low level, indicating that the scheme has good detection robustness and engineering feasibility under complex physical constraints.

[0228] In summary, the half-duplex protocol synchronization control scheme based on out-of-band digital keying (DOK) features proposed in this application achieves node time synchronization, external out-of-band cooperative signal sensing, and link time slot scheduling control by introducing a local monitoring channel during half-duplex node transmission and combining DK features, weighted cross-correlation detection, and closed-loop adaptive feedback processing. Simulation results show that this application achieves comprehensive improvements in throughput, energy consumption per unit successful transmission, and detection reliability under strong self-interference environments with relatively low physical layer and baseband processing overhead. Furthermore, it eliminates the need for a separate and complete second RF transceiver or independent control channel, which is beneficial for balancing the hardware simplification requirements of half-duplex IoT nodes with the link cooperative control requirements under high-density networking.

[0229] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of combined actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Secondly, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application. In the above embodiments, the descriptions of each embodiment have their own emphasis; for parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0230] Figure 8A structural block diagram of an example of a half-duplex protocol synchronization control system based on out-of-band digital keying features according to an embodiment of this application is shown. This half-duplex protocol synchronization control system based on out-of-band digital keying features can be deployed on a half-duplex communication node.

[0231] like Figure 8 As shown, the half-duplex protocol synchronization control system 800 based on out-of-band digital keying features includes an out-of-band signal generation unit 810, an RF signal merging unit 820, a local transmission monitoring unit 830, an out-of-band signal receiving and processing unit 840, a target sequence identification unit 850, a time deviation calculation unit 860, and a clock synchronization and link scheduling unit 870.

[0232] The out-of-band signal generation unit 810 is used to generate a pseudo-random sequence carrying local node identifier, local timestamp information and local channel coordination information, and modulate the pseudo-random sequence onto the out-of-band sub-band outside the main data carrier frequency band to obtain an out-of-band digital keying signal.

[0233] The radio frequency signal merging unit 820 is used to modulate the main data signal onto the main data carrier frequency band and merge the modulated main data signal with the out-of-band digital keying signal into a whole radio frequency signal to be transmitted.

[0234] The local transmission monitoring unit 830 is used to feed a portion of the power of the radio frequency signal in the transmission path to the local monitoring channel while the half-duplex communication node is transmitting the overall radio frequency signal, and to collect the mixed radio frequency signal formed by the local transmission component formed by the split feeding and the external radio frequency signal transmitted by the external node coupled through the monitoring and receiving path through the monitoring channel.

[0235] The out-of-band signal receiving and processing unit 840 is used to perform out-of-band frequency band filtering and demodulation processing on the mixed radio frequency signal received by the monitoring channel, so as to extract the corresponding discrete baseband sequence from the mixed radio frequency signal.

[0236] The target sequence identification unit 850 is used to perform weighted cross-correlation detection on the discrete baseband sequence using a pre-configured reference sequence set containing pseudo-random reference sequences corresponding to multiple nodes, so as to identify the target out-of-band digital keying sequence sent by the external node while suppressing the local transmission component, obtain the arrival time peak corresponding to the target out-of-band digital keying sequence, and parse the external node identifier, external timestamp information and external channel coordination information from the target out-of-band digital keying sequence.

[0237] The time deviation calculation unit 860 is used to combine the external timestamp information, the arrival time peak, and the local reception time recorded based on the local clock reference to calculate the time deviation of the external node relative to the local clock reference.

[0238] The clock synchronization and link scheduling unit 870 is used to perform synchronization correction updates on the local clock reference according to the time deviation, and adjust the transmission state of the half-duplex communication node according to the cooperative control signaling parsed from the external channel cooperative information, so as to perform link time slot scheduling.

[0239] In some embodiments, this application provides a non-volatile computer-readable storage medium storing one or more programs including execution instructions. The execution instructions can be read and executed by an electronic device (including but not limited to a computer, server, or network device) to perform the steps of any of the above-described half-duplex protocol synchronization control methods based on out-of-band digital keying features.

[0240] In some embodiments, this application also provides a computer program product, the computer program product including a computer program stored on a non-volatile computer-readable storage medium, the computer program including program instructions, which, when executed by a computer, cause the computer to perform the steps of any of the above-described half-duplex protocol synchronization control methods based on out-of-band digital keying features.

[0241] In some embodiments, this application also provides an electronic device comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform steps of a half-duplex protocol synchronization control method based on out-of-band digital keying features.

[0242] The above-described product can perform the methods provided in the embodiments of this application, and has the corresponding functional modules and beneficial effects for performing the methods. Technical details not described in detail in this embodiment can be found in the methods provided in the embodiments of this application.

[0243] The electronic devices in this application can exist in various forms, including but not limited to: mobile communication devices, ultra-mobile personal computer devices, portable entertainment devices, or other airborne electronic devices with data interaction functions.

[0244] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. 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.

[0245] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0246] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A half-duplex protocol synchronization control method based on out-of-band digital keying features, applied to a half-duplex communication node, characterized in that, The method includes: A pseudo-random sequence carrying local node identifier, local timestamp information and local channel coordination information is generated, and the pseudo-random sequence is modulated onto an out-of-band sub-band outside the main data carrier frequency band to obtain an out-of-band digital keying signal; The main data signal is modulated onto the main data carrier frequency band, and the modulated main data signal is combined with the out-of-band digital keying signal to form a whole radio frequency signal to be transmitted. During the period when the half-duplex communication node is transmitting the overall radio frequency signal, a portion of the power of the radio frequency signal in the transmission path is fed to the local monitoring channel, and the monitoring channel collects the mixed radio frequency signal formed by the local transmission component formed by the split feeding and the external radio frequency signal sent by the external node coupled through the monitoring and receiving path. The mixed radio frequency signal received by the monitoring channel is subjected to out-of-band filtering and demodulation processing to extract the corresponding discrete baseband sequence from the mixed radio frequency signal; Using a pre-configured set of reference sequences containing pseudo-random reference sequences corresponding to multiple nodes, weighted cross-correlation detection is performed on the discrete baseband sequence to identify the target out-of-band digital keying sequence sent by the external node while suppressing the local transmit component. The arrival time peak corresponding to the target out-of-band digital keying sequence is obtained, and the external node identifier, external timestamp information, and external channel coordination information are parsed from the target out-of-band digital keying sequence. By combining the external timestamp information, the peak arrival time, and the local reception time recorded based on the local clock reference, the time deviation of the external node relative to the local clock reference is calculated. The local clock reference is synchronized and updated according to the time deviation, and the transmission state of the half-duplex communication node is adjusted according to the cooperative control signaling parsed from the external channel cooperative information, so as to perform link time slot scheduling.

2. The method according to claim 1, characterized in that, The process of generating a pseudo-random sequence carrying local node identifiers, local timestamp information, and local channel coordination information, and modulating the pseudo-random sequence onto an out-of-band sub-band outside the main data carrier frequency band to obtain an out-of-band digital keying signal, includes: A binary spreading sequence with a preset symbol length and composed of positive and negative binary symbols is selected as the base spreading sequence, and the base spreading sequence is constrained to satisfy a preset cyclic autocorrelation characteristic; wherein, the cyclic autocorrelation characteristic includes: forming an autocorrelation peak corresponding to the sequence length in the zero cyclic shift state, and the residual autocorrelation response in the non-zero cyclic shift state does not exceed a preset residual autocorrelation upper limit; Local timestamp information is generated based on the local clock reference, and the local timestamp information is rolled-encoded through a linear feedback shift register. The local node identifier, the rolled-encoded local timestamp information, and the local channel coordination information are concatenated into the underlying control codeword. The base spread spectrum sequence is converted into a binary spread spectrum code, and the underlying control codeword and the binary spread spectrum code are XORed and spread, and then mapped into a pseudo-random sequence composed of positive and negative binary code elements. Narrow sub-bands with intervals relative to the main data carrier frequency band are selected on both sides of the center frequency of the main data carrier frequency band as out-of-band sub-bands. According to the preset symbol bit period, differential phase keying or amplitude keying is used to modulate the subcarrier signal in the out-of-band sub-bands based on the pseudo-random sequence to generate out-of-band digital keying signals. The transmit power of the out-of-band digital keying signal is adjusted so that the proportion of the transmit power of the out-of-band digital keying signal to the total transmit power of the overall radio frequency signal to be transmitted is not greater than a preset power proportion threshold, so as to reduce the adjacent band leakage interference of the out-of-band digital keying signal to the main data carrier frequency band.

3. The method according to claim 1, characterized in that, The step of performing weighted cross-correlation detection on the discrete baseband sequence using a pre-configured reference sequence set containing pseudo-random reference sequences corresponding to multiple nodes, to identify the target out-of-band digital keying sequence transmitted by the external node while suppressing the local transmission component, includes: The extracted discrete baseband sequence is symbol synchronized according to a preset symbol bit period and mapped to a discrete sampling point stream corresponding to the symbol position of the pseudo-random reference sequence. Within a sliding observation window, the total short-time observation energy captured by the monitoring channel is measured, and the short-time leakage energy formed by the leakage of the local transmission component into the monitoring channel through the radio frequency front-end isolation is estimated. Based on the transient occupancy of the short-term leakage energy relative to the total short-term observation energy, an adaptive suppression weight is dynamically determined for weighted cross-correlation detection; wherein, the adaptive suppression weight decreases the contribution of the corresponding sampling position to the correlation detection result as the relative proportion of the short-term leakage energy in the total short-term observation energy increases, and the weight fluctuation under low-energy observation state is suppressed by a preset energy lower limit parameter. Based on the calculated adaptive suppression weights, the discrete sampling point stream is subjected to sliding weighted cross-correlation calculation with each pseudo-random reference sequence in the reference sequence set to construct a sliding weighted cross-correlation function corresponding to different pseudo-random reference sequences and different discrete delay positions; The maximum absolute correlation peak of the sliding weighted cross-correlation function is retrieved within a preset relevant search window. When the maximum absolute correlation peak exceeds a preset correlation locking threshold, the pseudo-random reference sequence corresponding to the maximum absolute correlation peak is determined as the matching reference sequence, and the out-of-band digital keying sequence corresponding to the matching reference sequence is determined as the target out-of-band digital keying sequence.

4. The method according to claim 3, characterized in that, The step of obtaining the peak arrival time corresponding to the target out-of-band digital keying sequence and parsing the external node identifier, external timestamp information, and external channel coordination information from the target out-of-band digital keying sequence includes: The discrete delay position corresponding to the maximum absolute correlation peak value obtained by the sliding weighted cross-correlation function is retrieved and used as the corresponding optimal discrete delay coordinate; Combining the preset symbol bit period, the optimal discrete delay coordinates are converted into the time delay of the target out-of-band digital keying sequence arriving locally, which is used as the corresponding peak arrival time. The local clock reference corresponding to the transient moment when the maximum absolute correlation peak is captured is recorded as the local reception time. Symbol decision and delimitation decoding are performed on the identified target out-of-band digital keying sequence to parse out the external node identifier, the external channel coordination information, and the remote transmission timestamp as the external timestamp information. When the target out-of-band digital keying sequence uses differential phase keying, differential demodulation is performed on the target out-of-band digital keying sequence before delimitation decoding. Accordingly, the step of calculating the time deviation of the external node relative to the local clock reference by combining the external timestamp information, the peak arrival time, and the local reception time recorded based on the local clock reference includes: Based on the time reference correction relationship between the local reception time, the remote transmission timestamp, and the arrival time peak, the propagation delay of the target out-of-band digital keying sequence during its arrival from the external node is eliminated, and the transient clock deviation of the external node relative to the local clock reference is obtained, and the transient clock deviation is used as the corresponding time deviation.

5. The method according to claim 1 or 4, characterized in that, The step of performing synchronization correction update on the local clock reference based on the time deviation includes: Extract the time deviations corresponding to the multiple external nodes detected within a preset time collection window, and determine the corresponding trust weight coefficients based on the received signal quality indicators of each external node; wherein, the external node is a valid external node that successfully identifies the target out-of-band digital keying sequence, and each trust weight coefficient is a positive value; Based on the time deviation and trust weight coefficient corresponding to each of the external nodes, signal quality weighted fusion is performed on multiple time deviations to calculate the weighted average time difference. The weighted average time difference is used as a feedback input variable, and a preset discrete-time proportional-integral controller is used to perform smooth synchronization updates on the local clock reference. The discrete-time proportional-integral controller, based on the normal time advance of the local clock reference, introduces a proportional correction term corresponding to the current weighted average time difference in the direction of negative feedback correction, and introduces an integral correction term corresponding to the cumulative state of the weighted average time difference in multiple historical update cycles. Based on the proportional correction term and the integral correction term, the state variable of the local clock reference in the next update cycle is calculated; wherein, the integral correction term is used to compensate for the inherent frequency offset of the local hardware clock and suppress transient deviation jitter.

6. The method according to claim 1, characterized in that, The adjustment of the transmission state of the half-duplex communication node based on the cooperative control signaling parsed from the external channel cooperative information for link time slot scheduling includes: Based on the local clock reference updated by synchronization correction, the communication time resources are divided into periodic transmission windows, and each transmission window is discretely divided into multiple micro-time slots of a certain duration. Based on the micro-time slots, a target transmission time slot is planned for the half-duplex communication node. When the half-duplex communication node is in the backoff listening phase of preparing to send data packets, the out-of-band digital keying sequence of the external node is continuously detected through the monitoring channel within a preset sensing time window in order to extract external channel coordination information and parse out coordination control signaling. If the cooperative control signaling includes a time slot reservation identifier issued by an external node, and the reserved time slot pointed to by the time slot reservation identifier has a time domain overlap conflict with the target transmission time slot planned locally, then the half-duplex communication node is controlled to suspend the current transmission plan and switch to a backoff waiting state. When the half-duplex communication node is in a state of continuously transmitting the overall radio frequency signal, if the cooperative control signaling parsed in real time through the monitoring channel contains an emergency stop instruction issued by a high-priority node, the physical layer transmission interruption logic is triggered to stop the current physical transmission process of the overall radio frequency signal and release the wireless channel resources. If no occupancy or reservation-type cooperative control signaling that overlaps with the target transmission time slot is parsed within the preset sensing time window, the half-duplex communication node is authorized to initiate physical layer transmission operation within the target transmission time slot, and the local channel cooperative information configured as a local transmission reservation indication is carried in the out-of-band digital keying signal and sent to the external node along with the overall radio frequency signal.

7. The method according to claim 3 or 4, characterized in that, After identifying the target out-of-band digital keying sequence sent by the external node, the method further includes performing closed-loop adaptive feedback control operations on the out-of-band cooperative sensing link, specifically including: The received signal power of the monitoring channel corresponding to the out-of-band digital keying sequence of the target within the current observation window is measured, and the average power of the floor noise under the current environment is estimated, so as to calculate the real-time received signal-to-noise ratio of the out-of-band cooperative sensing link; The real-time received signal-to-noise ratio is input into a preset detection probability response model to obtain an estimated detection success probability of the out-of-band cooperative sensing link under the current channel conditions; wherein, the detection probability response model is used to characterize the relationship between the real-time received signal-to-noise ratio and the demodulation signal-to-noise ratio threshold, and to make the estimated detection success probability increase as the real-time received signal-to-noise ratio increases; The estimated success probability of detection is compared with the target detection probability threshold preset by the system. When the estimated success probability of detection is lower than the target detection probability threshold, a weak signal enhancement and control mechanism is triggered to control the half-duplex communication node to increase the transmission power of the out-of-band digital keying signal in the overall radio frequency signal in the next transmission cycle, and / or adjust the leakage suppression adjustment factor when calculating the adaptive suppression weight according to a preset adjustment rule, so as to improve the detectability of the subsequent cooperative signaling sent by the half-duplex communication node by the external node and the detection adaptability of the monitoring channel to the external cooperative signaling; When the estimated success probability of detection is higher than the preset power reduction threshold, wherein the power reduction threshold is higher than the target detection probability threshold, an energy-saving backoff control mechanism is triggered to reduce the transmission power of the out-of-band digital keying signal according to a preset attenuation ratio, so as to reduce the out-of-band cooperative transmission power consumption of the half-duplex communication node while meeting the reliability requirements of cooperative signaling detection. When the estimated success probability of detection is not lower than the target detection probability threshold and not higher than the power down-adjustment threshold, the current transmit power and leakage suppression adjustment factor of the out-of-band digital keying signal are maintained.

8. A half-duplex protocol synchronous control system based on out-of-band digital keying features, deployed at a half-duplex communication node, characterized in that, The system includes: An out-of-band signal generation unit is used to generate a pseudo-random sequence carrying local node identifier, local timestamp information and local channel coordination information, and modulate the pseudo-random sequence onto an out-of-band sub-band outside the main data carrier frequency band to obtain an out-of-band digital keying signal; The radio frequency signal combining unit is used to modulate the main data signal onto the main data carrier frequency band and combine the modulated main data signal with the out-of-band digital keying signal into a whole radio frequency signal to be transmitted. The local transmission monitoring unit is used to feed a portion of the power of the radio frequency signal in the transmission path to the local monitoring channel during the period when the half-duplex communication node is transmitting the overall radio frequency signal, and to collect the mixed radio frequency signal formed by the local transmission component formed by the split feeding and the external radio frequency signal transmitted by the external node coupled through the monitoring and receiving path through the monitoring channel. An out-of-band signal receiving and processing unit is used to perform out-of-band frequency band filtering and demodulation processing on the mixed radio frequency signal received by the monitoring channel, so as to extract the corresponding discrete baseband sequence from the mixed radio frequency signal; The target sequence identification unit is used to perform weighted cross-correlation detection on the discrete baseband sequence using a pre-configured reference sequence set containing pseudo-random reference sequences corresponding to multiple nodes, so as to identify the target out-of-band digital keying sequence sent by the external node while suppressing the local transmission component, obtain the arrival time peak corresponding to the target out-of-band digital keying sequence, and parse the external node identifier, external timestamp information and external channel coordination information from the target out-of-band digital keying sequence; The time deviation calculation unit is used to combine the external timestamp information, the peak arrival time, and the local reception time recorded based on the local clock reference to calculate the time deviation of the external node relative to the local clock reference. The clock synchronization and link scheduling unit is used to perform synchronization correction updates on the local clock reference according to the time deviation, and adjust the transmission status of the half-duplex communication node according to the cooperative control signaling parsed from the external channel cooperative information, so as to perform link time slot scheduling.

9. An electronic device, comprising: At least one processor; as well as A memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the steps of the method as described in any one of claims 1-7.

10. A storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1-7.

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