Hidden node-oriented data transmission method and system based on exposed node feedback

Abstract

The invention belongs to the technical field of wireless networks, and discloses a hidden node-oriented data transmission method based on exposed node feedback, which has high reliability: the state of a hidden node is indirectly deduced through the exposed node feedback, and the limitation that the hidden node carries out one-way communication most of the time is broken through. And resource efficiency: based on an ACK sequence matching rate, accurately predicting whether a hidden node receives, and dynamically adjusting and reducing redundant transmission. Environment adaptability: supporting one-way communication scenes (such as military command nodes, Internet of Things sensors and satellite ground terminals) of fixed nodes, adapting to channel changes through passive updating and active detection, and enhancing system robustness. And expansibility: the cross-scene generalization ability is enhanced through the ACK sequence matching rate, and the method is suitable for various one-way communication applications.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wireless networks, and particularly relates to a data transmission method and system for hidden nodes based on exposure node feedback. BACKGROUND

[0002] In a wireless communication network, hidden nodes usually cannot return ACK or NACK feedback to the sending end due to limitations such as security policy, hardware power or deployment location, resulting in that the sending end cannot judge whether the data is successfully received in real time. The existing technology usually adopts forward error correction and blind retransmission to improve reliability, but such methods depend on fixed redundancy configuration, which causes resource waste when the channel quality is good, and may not be enough to guarantee data reliability when the channel quality deteriorates, so the overall spectrum utilization and transmission efficiency are low, and it is difficult to adapt to the rapidly changing network environment.

[0003] Part of the cooperative communication technology introduces relay or neighbor nodes to participate in feedback delivery, but such a scheme generally requires all nodes to have bidirectional communication capability to realize end-to-end ACK interaction. For hidden nodes that can only receive but cannot send feedback, this mechanism cannot be directly applied, and the modification cost is too high on low-power Internet of Things devices with limited hardware, and the deployment feasibility is poor.

[0004] Channel prediction methods try to infer the future link state by analyzing historical channel parameters and statistical characteristics to optimize the sending strategy. However, such methods assume in the design that the prediction object can participate in bidirectional measurement and feedback, and are not optimized for the characteristics of hidden nodes. At the same time, the channel estimation process does not combine the spatial position relationship and channel correlation between hidden nodes and surrounding exposed nodes, resulting in a significant decrease in prediction accuracy under multipath fading and dynamic topology.

[0005] In summary, the existing technology still lacks an effective mechanism that uses exposed node feedback information and combines spatial correlation to dynamically infer the receiving state of hidden nodes. The lack of such a mechanism not only limits the reliable access capability of hidden nodes in special scenarios such as secure communication, military deployment and emergency networks, but also hinders the improvement of transmission performance of wireless networks in low-visibility and high-interference environments. SUMMARY

[0006] In view of the problems in the prior art, the application provides a data transmission method for hidden nodes based on exposure node feedback.

[0007] The application is implemented as follows: a data transmission method for hidden nodes based on exposure node feedback comprises the following steps:

[0008] Step 1: a central control unit establishes an association relationship between a hidden node and an optimal exposed node;

[0009] Step 2, the central control unit informs the exposed node to listen to all the hidden node addresses with the association relationship;

[0010] Step 3, the exposed node receives the data packet with the target address as the hidden node, and feeds back ACK after successful reception;

[0011] Step 4, running phase, the hidden node remains silent, and only the associated exposed node feeds back the reception status;

[0012] Step 5, the central control unit dynamically adjusts the transmission strategy according to the feedback of the exposed node.

[0013] Further, the association relationship is established as follows:

[0014] Position coarse screening: according to the known position information of the hidden node and the exposed node, the Euclidean distance between the two is calculated, and the exposed node with a distance less than the preset threshold is selected as the candidate associated node;

[0015] Channel fine screening: by sending an association establishment data packet, the ACK sequence of the hidden node and the candidate exposed node is recorded, and the ACK sequence matching rate is calculated:

[0016]

[0017] Wherein, S H and S E are the ACK sequences of the hidden node and the exposed node respectively, is an indicator function (1 is generated when the two input values are the same; 0 is generated when the two input values are different), NACK is not sent, and the central control unit considers NACK when it does not receive a response within a timeout period;

[0018] The conditional probability is calculated at the same time, and the method is:

[0019]

[0020] Wherein, H represents the hidden node, and E represents the exposed node.

[0021] The exposed node with the highest matching rate (and the conditional probability > 90%) is selected as the only associated node of the hidden node

[0022] Further, one exposed node can simultaneously associate multiple hidden nodes;

[0023] One hidden node is associated with only one optimal exposed node.

[0024] Further, the association establishment data packet contains a test packet that forces to trigger NACK (causes intentional reception failure, and the receiver does not send NACK), which is implemented by the following method:

[0025] The transmitting power is reduced by 8-12 dBm; or

[0026] Injecting an interference signal with a bandwidth of 10-20% in a specific frequency band.

[0027] Further, the dynamic maintenance includes the following manners:

[0028] Periodic maintenance: recalibrate the association relationship every 24 hours or other preset time period;

[0029] Event-triggered maintenance: recalibrate the association relationship when the moving distance of the exposed node or the hidden node exceeds the preset threshold;

[0030] The dynamic adjustment of the transmission strategy includes at least one of the following manners:

[0031] Re-transmission number adjustment;

[0032] Forward error correction (FEC) adjustment;

[0033] Encoding code rate adjustment;

[0034] Transmitting power adjustment;

[0035] The hidden node provides limited feedback (the hidden node only feeds back the association establishment data packet) in the association calibration stage, and is completely silent in the running stage;

[0036] If the conditional probability of the hidden node and all exposed nodes is lower than 90%, the number of association establishment data packets is increased or the exposed and hidden nodes are moved to recalibrate the association relationship.

[0037] Another object of the present application is to provide an exposed node feedback-based hidden node-oriented data transmission system, which comprises:

[0038] An association relationship establishment module of the center control unit, configured to establish the association relationship of the hidden node and the optimal exposed node by the center control unit;

[0039] A notification module of the center control unit, configured to notify the exposed node to listen to all hidden node addresses having the association relationship by the center control unit;

[0040] Exposed node: receiving module + feedback module

[0041] In the running stage: the receiving module of the exposed node receives the data packet with the target address being the hidden node, and after successful reception, the feedback module of the exposed node feeds back ACK

[0042] In the association establishment stage: the receiving module of the exposed node receives the association establishment data packet, and after successful reception, the feedback module of the exposed node feeds back ACK

[0043] Hidden node: receiving module + feedback module

[0044] In the running phase: the receiving module of the hidden node receives the data packet with the receiving target address being the hidden node, and the feedback module does not work;

[0045] In the association establishment phase: the receiving module of the hidden node receives the data packet for association establishment, and after successful reception, the feedback module of the hidden node feeds back ACK

[0046] The adjusting module of the center control unit is used for dynamically adjusting the transmission strategy of the center control unit according to the feedback of the exposed node.

[0047] Another object of the present application is to provide a computer device comprising a memory and a processor, the memory storing a computer program, the computer program being executed by the processor to make the processor execute the steps of the data transmission method for hidden nodes based on the feedback of exposed nodes.

[0048] Another object of the present application is to provide a computer readable storage medium storing a computer program, the computer program being executed by a processor to make the processor execute the steps of the data transmission method for hidden nodes based on the feedback of exposed nodes.

[0049] Another object of the present application is to provide an information data processing terminal for implementing the data transmission system for hidden nodes based on the feedback of exposed nodes.

[0050] In combination with the above technical solutions and the technical problems solved, the technical solution to be protected by the present application has the following advantages and positive effects:

[0051] Firstly, the present application aims to solve the problem of uncertain receiving state of hidden nodes in wireless communication networks due to the inability to send feedback (such as ACK). This problem is particularly prominent in military communication, Internet of Things, satellite broadcasting and other scenarios. Traditional methods (such as FEC or blind retransmission) have the disadvantages of resource waste or low efficiency, and are difficult to adapt to dynamic network environments. The present application indirectly infers the receiving state of hidden nodes through the feedback of exposed nodes, optimizes the transmission strategy, and improves the system reliability and resource efficiency.

[0052] The present application selects the unique associated exposed node of the hidden node based on the ACK sequence matching rate, and provides an efficient, robust and highly concealed communication method, which has significant innovation compared with the prior art:

[0053] Simplified feedback mechanism: the present application only uses the ACK sequence matching rate of exposed nodes and hidden nodes:

[0054]

[0055] where S H1 , S Ei are ACK sequences of the hidden node and the exposed node, is an indicator function. This method does not require the exposed node to feedback complex channel information (such as RSSI, SNR), significantly reducing the uplink overhead, especially suitable for low-power scenarios (such as Internet of Things sensors, satellite terminals).

[0056] Robustness: By directly comparing ACK sequences, the similarity of the receiving behavior of the hidden node and the exposed node is captured, adapting to dynamic channel environments (such as electromagnetic interference in military communications, multipath fading). Compared with existing technologies that rely on RSSI / SNR segmentation, this method avoids segmentation failure caused by channel fluctuations, improving inference reliability.

[0057] Enhanced concealment: The hidden node only provides limited feedback during the association calibration stage and is completely silent during the running stage, significantly reducing the risk of exposure, which is superior to traditional RTS / CTS or HARQ mechanisms (which require frequent feedback).

[0058] Low initialization overhead: Only a small number of broadcasts (such as 20 times) are required to construct the ACK matching rate, the overhead of the association calibration stage is low, and it is suitable for fast deployment scenarios.

[0059] Wide applicability: This method is suitable for one-way communication (such as satellite broadcasting), low-power networks (such as LoRa, NB-IoT), and high-concealment scenarios (such as military communications), and has significant commercial value.

[0060] Through the above innovations, the present application realizes efficient, robust, and concealed communication in the inference of the receiving state of the hidden node, which is significantly superior to existing technologies.

[0061] Second, the technical solution of the present application is particularly suitable for three types of high-value application scenarios: In military communications, the hidden node remains silent and transfers the feedback responsibility to the exposed node, ensuring the integrity and timeliness of the command link without exposing its own position; In Internet of Things networks, a large number of low-power sensors act as hidden nodes, and their feedback is replaced by more powerful gateway nodes, which can significantly extend battery life and reduce backhaul conflicts; In satellite broadcast systems, ground terminals receive silently and are responsible for feedback by regional proxy nodes, which can significantly improve the reliability and scalability of the downlink broadcast link.

[0062] At the resource utilization level, the exposure node helps the center control unit accurately infer the receiving state of the hidden node based on the ACK information, so that the sending end only starts retransmission and increases FEC redundancy when necessary, which can reduce the bandwidth occupation and transmission power consumption by 20%-40% as a whole, effectively saving satellite transponder rental fees or ground narrowband spectrum costs. According to actual measurement or simulation, when the matching rate of the exposure node reaches 95%, the inference accuracy of the system for the successful reception of the hidden node can be maintained at more than 90%, which is significantly better than the traditional broadcast feedback mechanism.

[0063] The "zero uplink" feature of the hidden node in the running phase naturally has high concealment and anti-interference ability, which meets the compliance requirements of national defense security, emergency communication and privacy-sensitive Internet of Things applications. This feature of high reliability, low power consumption and strong concealment can lead to multiple commercial product forms such as military communication modules, satellite Internet of Things chips and secure gateway devices, and is expected to generate hundreds of millions of yuan in authorized and system integration revenue in the low earth orbit satellite service market within five years.

[0064] Traditional wireless link design is generally based on the "two-way symmetric" assumption: the MAC layer needs to continuously exchange frames between the sending end and the receiving end through RTS / CTS or HARQ to complete collision avoidance, rate negotiation and error recovery; at the link layer or physical layer, continuous channel parameters such as RSSI, SNR and CSI are relied on for real-time estimation and power closed loop. The implicit premise of this paradigm is that all nodes have stable uplink capabilities and sufficient energy consumption budget, so there is a deep-rooted technical bias for the application scenarios of "one-way silent" nodes - once the receiving end cannot return fine channel information, the system will have difficulty in ensuring reliability and resource utilization.

[0065] The present application adopts the "exposure node proxy feedback + ACK sequence inference" mechanism to completely get rid of the above-mentioned two-way symmetric dependence. The core lies in: first, only 0 / 1 ACK is used as the feedback feature input, and complex parameters such as RSSI or SNR that need to be quantized in real time are abandoned, so that the inference algorithm still has robustness in dynamic, multipath and unstable channels, while significantly reducing the calculation and uplink load; second, by pre-establishing a "hidden node - optimal exposure node" mapping table, the exposure node independently completes the uplink ACK in the running phase, and the hidden node remains completely silent, which breaks through the traditional understanding that "two-way communication is necessary" from the system architecture, and opens up a feasible and reliable transmission path for one-way receiving or ultra-low power consumption nodes.

[0066] Practice shows that under the condition of silent hidden nodes and relying only on ACK sequence of exposed nodes, the system can still maintain a receiving state inference accuracy of ≥90%, and save 20-40% in bandwidth and power consumption compared with traditional HARQ schemes. Therefore, the technical solution not only overcomes the inherent technical bias for two-way interaction, but also realizes high adaptability to dynamic channels and natural compatibility to security-sensitive scenarios with lower complexity, embodying unique and quantifiable engineering value. BRIEF DESCRIPTION OF DRAWINGS

[0067] Figure 1 is a data transmission method flow chart for hidden nodes based on exposed node feedback provided by the embodiment of the present application.

[0068] Figure 2 is a method flow chart for establishing an association relationship provided by the embodiment of the present application.

[0069] Figure 3 is a system structure block diagram for hidden nodes based on exposed node feedback provided by the embodiment of the present application. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0071] In the existing wireless communication network, hidden nodes cannot directly return receiving confirmation information to the sending end due to physical location, transmission power or security policy restrictions, resulting in the sending end being unable to accurately know whether the data transmission is successful. This feedback loss makes the sending end uncertain in link state judgment and can only rely on high-redundancy forward error correction or repeated retransmission to improve reliability, causing a decrease in spectrum utilization, an increase in latency and an increase in energy consumption. In the scenarios of industrial Internet of Things, emergency communication and military communication with multiple node dense deployment, this problem is particularly prominent, directly affecting the throughput efficiency of the network and the timeliness of task execution.

[0072] The present application introduces exposed nodes as proxy feedback entities of hidden nodes in the network, establishes an association mapping relationship between hidden nodes and optimal exposed nodes, so that hidden nodes can realize data receiving state transmission without sending additional feedback. The central control unit uses network topology information and link quality evaluation results to dynamically select exposed nodes with the best listening conditions as proxies, reducing the uncertainty of the feedback path and improving the transmission reliability of the confirmation information. This method completes the configuration of the listening target in the node association establishment stage, thereby ensuring the automation and low delay of the feedback process in the subsequent running stage.

[0073] In operation, the exposure node continuously listens to the wireless channel to capture the data packets of the target hidden node and performs correctness verification. When the data packet passes the verification, the exposure node immediately returns an ACK signal to the sender to replace the direct feedback of the hidden node. This proxy acknowledgment mechanism eliminates the limitations of the feedback link of the hidden node, enabling the sender to real-time master the reception status of the data and thus accurately control the transmission rate and retransmission strategy. Since the hidden node remains silent, it not only reduces the transmission power consumption but also reduces the channel competition and interference risk, further optimizing the overall performance of the network.

[0074] After obtaining the feedback information of the exposure node, the central control unit dynamically adjusts the transmission strategy according to parameters such as link quality fluctuation, ACK loss rate, and data packet error rate. For example, when the feedback of the exposure node indicates that the reception rate of the hidden node is decreasing, the central control unit can instruct the sender to reduce the modulation order, increase the channel coding redundancy, or switch to a channel with less interference. This closed-loop control process enables the system to have adaptive anti-interference and load adjustment capabilities, making it particularly suitable for complex and variable wireless environments.

[0075] In terms of industrial applications, this method can be deployed through software and network configuration without modifying the hardware structure of the hidden node, reducing the system transformation cost and implementation period. In scenarios such as smart factories, port logistics, and energy monitoring, hidden nodes are often located in places where high-power transmission modules are difficult to install, such as underground pipe galleries, sealed equipment warehouses, or hazardous environments. The invention enables these nodes to participate in high-reliability data interaction in low-power mode through the proxy feedback of exposure nodes, helping to extend the service life of equipment and reduce maintenance frequency.

[0076] In the field of military and emergency communication, this method can maintain the effectiveness of the data link in a harsh electromagnetic countermeasure environment. Since the hidden node does not directly transmit feedback signals, the risk of interception or positioning is reduced, and indirect feedback relying on exposure nodes ensures the confirmed delivery of task data. This design balances the concealment and reliability of communication, and is of great significance for quickly building wireless self-organizing networks in hostile or disaster environments. Through this mechanism, the network can quickly reconstruct the feedback path when facing node failure or channel condition mutation, maintaining the continuity and stability of data transmission.

[0077] As shown in Figure 1 The data transmission method for hidden nodes based on exposure node feedback provided by the embodiment of the invention includes the following steps:

[0078] S101, the central control unit establishes the association relationship between the hidden node and the optimal exposure node;

[0079] S102, the central control unit informs the exposure node to listen to all the hidden node addresses with associated relationship;

[0080] S103, the exposure node receives the data packet with the target address as the hidden node, and feeds back ACK after successful reception;

[0081] S104, in the running stage, the hidden node remains silent and only the associated exposure node feeds back the reception status;

[0082] S105, the central control unit dynamically adjusts the transmission strategy according to the feedback of the exposure node.

[0083] In the S101 association establishment stage, the central control unit first periodically broadcasts the association establishment data packet, and calculates the ACK sequence matching degree and conditional probability between each hidden node and the adjacent exposure node. The control unit selects the unique optimal exposure node for each hidden node, and internally generates a "hidden node exposure node" mapping table. If an available exposure node cannot be found for the hidden node within the preset window, it is marked as a retry or off-network state, and subsequently enters the re-association attempt.

[0084] After the mapping is completed, the S102 listening configuration stage is entered. The central control unit issues a listening instruction to each exposure node, including the required hidden node address list to be listened to, the expected system ACK time limit, etc. The exposure node starts multicast address filtering at the physical layer according to this, ensuring that only the frames related to the target hidden node are decoded, reducing the energy consumption caused by irrelevant traffic, and avoiding unnecessary interference to other cells. At the same time, the hidden node receives and stores its mapping results, but remains silent during the subsequent data service and no longer actively uploads ACK to maintain the hidden characteristic.

[0085] To the S103-S104 service transmission stage, the sender sends the business data frame carrying the target address and variable FEC redundancy to the designated hidden node according to the central control unit scheduling in each time slice. If the exposure node successfully decodes and the target address matches its associated hidden node, it returns a 1-bit positive acknowledgement to the central control unit within the specified ACK return time slot; otherwise, if the reception fails, it remains silent (no NACK), and the central control unit considers it as NACK if no ACK is received. The hidden node is always in the receiving state and does not generate uplink signaling, which fundamentally eliminates the channel occupation and location exposure risk caused by bidirectional handshake.

[0086] Finally in S105 policy closed loop, the center control unit continuously collects and statistics exposed node ACK sequence, estimates the instantaneous receiving success rate index of hidden node by using conditional probability method. When detecting link quality degradation or service QoS not up to standard, the control unit issues new physical layer configuration (such as increasing transmitting power, switching stronger FEC, reducing modulation order or shortening retransmission window) to the sending end; if finding that some exposed node is out of network due to too high energy consumption or mobile, the associated relationship can also be dynamically reconstructed. Under this closed loop mechanism, the system takes into account the concealment, reliability and resource efficiency, and realizes adaptive optimization to dynamic channel environment.

[0087] As Figure 2 shown, the method for establishing associated relationship provided by the embodiment of the application is as follows:

[0088] S201, position rough screening:

[0089] According to the known position information of the hidden node and the exposed node, the Euclidean distance between them is calculated, and the exposed node with a distance less than a preset threshold is selected as a candidate associated node;

[0090] S202, channel fine screening:

[0091] By sending associated establishment data packets, the ACK sequence of the hidden node and the candidate exposed node is recorded, and the ACK sequence matching rate is calculated:

[0092]

[0093] Wherein, S H and S E are the ACK sequences of the hidden node and the exposed node respectively, is an indication function, NACK is not sent, and the receiver considers NACK after timeout;

[0094] The calculation method of conditional probability is:

[0095]

[0096] Wherein, H represents the hidden node, and E represents the exposed node

[0097] The exposed node with the highest matching rate (and the conditional probability>0.9) is selected as the only associated node of the hidden node

[0098] The embodiment of the application provides that one exposed node can simultaneously associate multiple hidden nodes;

[0099] One hidden node is associated with only one optimal exposed node.

[0100] The associated establishment data packet provided by the embodiment of the application contains a test packet for forcibly triggering NACK, which is realized by the following way:

[0101] The transmission power is reduced by 8-12 dBm; or

[0102] An interference signal with a bandwidth of 10-20% is injected in a specific frequency band.

[0103] The conditional probability calculation method provided by the embodiment of the application is as follows:

[0104]

[0105] Wherein, H represents a hidden node, and E represents an exposed node.

[0106] The dynamic maintenance provided by the embodiment of the application includes the following modes:

[0107] Periodic maintenance: recalibrate the association relationship every 24 hours or other preset time period;

[0108] Event-triggered maintenance: recalibrate the association relationship when the moving distance of the exposed node or the hidden node exceeds the preset threshold;

[0109] The dynamic adjustment of the transmission strategy includes at least one of the following modes:

[0110] Adjustment of the number of retransmissions;

[0111] Forward error correction (FEC) adjustment;

[0112] Encoding code rate adjustment;

[0113] Transmission power adjustment;

[0114] The hidden node provides limited feedback in the association calibration stage and is completely silent in the running stage;

[0115] If the conditional probability of the ACK sequence of the hidden node and all exposed nodes is lower than 90%, the number of association establishment data packets is increased or the exposed and hidden nodes are moved to recalibrate the association relationship.

[0116] As shown in Figure 3 The data transmission system for the hidden node based on the feedback of the exposed node provided by the embodiment of the application includes:

[0117] The association relationship establishment module of the central control unit is used to establish the association relationship between the hidden node and the optimal exposed node by the central control unit;

[0118] The notification module of the central control unit is used to notify the exposed node to listen to all hidden node addresses with the association relationship by the central control unit;

[0119] The receiving module of the exposure node is used for receiving a data packet with a target address being the hidden node, and feeding back an ACK after successful reception (this is the function of the feedback module);

[0120] The feedback module of the exposure node is used for feeding back the reception status in the running phase, and the hidden node remains silent and is only fed back by the associated exposure node (but in the association establishment phase, the hidden node also feeds back the association establishment data packet)

[0121] The receiving module is always present in the hidden node, and the feedback module is also present in the hidden node (only for feeding back the association establishment data packet)

[0122] The adjustment module of the center control unit is used for dynamically adjusting the transmission strategy according to the feedback of the exposure node.

[0123] The exposure node feedback-based data transmission system for the hidden node provided by the application comprises a center control unit and a plurality of network nodes. The center control unit is provided with an association relationship establishment module, a notification module and an adjustment module. The association relationship establishment module is used for selecting an optimal exposure node for each hidden node and establishing the association thereof. The notification module is used for issuing a listening instruction to the corresponding exposure node after the association is established, so that the exposure node listens to all hidden node addresses having the association relationship. The adjustment module dynamically optimizes the transmission strategy of the hidden node, such as the silent duration, the retransmission window and the scheduling priority, according to the ACK information returned by the exposure node. The exposure node is provided with a receiving module and a feedback module. The receiving module is responsible for receiving a data packet with a target address being the associated hidden node in the running phase. The feedback module returns the reception status to the center control unit in the running phase instead of the hidden node, and also feeds back the association establishment data packet in the association relationship establishment phase. The hidden node has the receiving and feedback functions, and only feeds back the ACK in the association establishment phase, and remains silent at other times, so that the channel competition is reduced and the network throughput is improved.

[0124] Based on the above system architecture, the application further provides a computer device comprising a memory and a processor. A computer program pre-stored in the memory can complete the following steps when executed by the processor, such as the calculation of the association relationship between the hidden node and the optimal exposure node, the issuance of the listening notification, the collection and analysis of the ACK feedback, and the real-time adaptive adjustment of the transmission strategy, so as to realize the reliable data transmission for the hidden node. Synchronously, the application also discloses a computer readable storage medium, and computer program instructions stored thereon can be executed by the processor to execute the above exposure node feedback-based data transmission method for the hidden node, so as to facilitate software distribution and independent deployment.

[0125] In addition, the application also provides an information data processing terminal which can be implemented as a center control unit, an exposed node or a hidden node. The terminal is built-in with the computer program and can complete functions such as association establishment, listening notification, ACK feedback and strategy adjustment in a network environment, and can flexibly enable or disable the receiving module, the feedback module and the adjustment module according to the deployment role, so as to realize the compatibility and expansion of multiple types of communication scenes.

[0126] The application provides a one-way network hidden node data reliable transmission method based on exposed node assistance, which uses the ACK feedback of the exposed node, infers the receiving state of the hidden node through the association relationship between the hidden node and the exposed node, and dynamically adjusts the transmission strategy (such as retransmission times, FEC intensity and transmission power).

[0127] In the association establishment stage, the center control unit first broadcasts an association establishment data packet, and the sending end sends the data packet in a loop without carrying a target address according to the instruction. The exposed node and the hidden node enter a listening state at the same time: the exposed node returns an ACK to the center control unit as soon as it successfully receives the association establishment data packet; and the hidden node also feeds back an ACK when it successfully receives, to confirm the reachability of itself. The center control unit calculates the link reliability between each hidden node and the candidate exposed node according to the arrival time sequence and the channel quality parameters of the two types of ACK messages, and selects the optimal exposed node for each hidden node, to complete the generation and issuance of the association mapping table. If the ACK of the hidden node is not received within a preset time window, the hidden node is marked as off-network or a state to be retried; and if the exposed node feedback is incomplete, the center control unit triggers the re-broadcasting of the association establishment data packet until the association relationship is stable and convergent.

[0128] After entering the running stage, the sending end sends a data packet carrying a specific target address to the target hidden node in each scheduling period according to the association mapping issued, and can dynamically adjust the FEC redundancy, the transmission power and the modulation mode according to the link evaluation returned by the center control unit. The exposed node executes listening and decoding on the data packet matching the target address of the associated hidden node, and feeds back an ACK to the center control unit as soon as it successfully receives, and remains silent to avoid channel congestion if it fails. The center control unit uses the ACK of the exposed node collected continuously to statistically evaluate the actual receiving success rate of the hidden node, and uses algorithms such as Bayesian update or exponential weighted moving average to evaluate the link state in real time, and issues new modulation, power or retransmission window configurations when detecting the degradation of the index, to realize the closed-loop adaptive optimization of the data transmission strategy of the hidden node.

[0129] Association calibration stage:

[0130] Position coarse screening: the center control unit calculates the Euclidean distance between the hidden node and the exposed node according to the known position information of the hidden node and the exposed node:

[0131]

[0132] where (x h ,y h ) and (x e ,y e ) are the coordinates of the hidden node and the exposed node respectively. (Extend to 3D space, add a z)

[0133] The central control unit selects exposed nodes with distance less than a preset threshold as candidate associated nodes, forming a one-to-many correspondence between the hidden node and multiple exposed nodes.

[0134] Channel fine screening: the sending end sends association establishment packets (such as 20 times), and the exposed node and the hidden node feedback ACK if they receive successfully. (ACK message conflicts are solved by different spreading codes or different transmission times, which are not described here)

[0135] The central control unit records the ACK sequence (1 = ACK, 0 = NACK) of the hidden node and the exposed node for the exposed nodes and candidate associated nodes formed by the geographical preliminary screening, considers it as NACK if no ACK is received, and calculates the ACK sequence matching rate:

[0136]

[0137] where S H1 , S Ei are the ACK sequences of the hidden node H1 and the exposed node Ei, is an indicator function, which is 1 when the two are equal, and 0 otherwise.

[0138] Different exposed-hidden node pairs (such as E1-H1, E2-H1) produce different matching rates (such as E1-H1: 95%, E2-H1: 60%) due to differences in distance and channel environment.

[0139] The central control unit calculates the conditional probability P(S H =1|S E =1)

[0140] The central control unit selects the exposed node with the highest ACK matching rate (and the conditional probability is greater than 90%) as the only associated node of the hidden node. If there are multiple exposed nodes that meet the conditions, the one with the highest matching rate is selected.

[0141] The central control unit notifies the exposed node of the hidden node address that needs to feedback ACK / NACK, noting that there may be one exposed node that needs to listen to multiple hidden node addresses

[0142] Example: If the hidden node H1 finds two candidate exposed nodes E1 (distance 50 meters) and E2 (distance 60 meters) in the location preliminary screening stage, the sending end broadcasts 20 times of association establishment data packets, and records the ACK sequence:

[0143] H1: S H1 = [1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1] (success 14 times).

[0144] E1: S E1 = [1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1] (success 15 times).

[0145] E2: S E2 = [1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1] (success 10 times).

[0146] E1-H1 matching rate: (match 19 times, positions 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20).

[0147] E2-H1 matching rate: (match 12 times, positions 1, 3, 4, 5, 7, 8, 9, 11, 12, 14, 15, 16, 17, 19, 20).

[0148] Calculate E1-H1 conditional probability P(S H1 = 1 | S E1 = 1) ≈ 0.93 (H1 and E1 are both 1, 14 times; E1 is 1, 15 times)

[0149] Calculate E2-H1 conditional probability P(S H1 = 1 | S E2 = 1) ≈ 1 (H1 and E1 are both 1, 10 times; E2 is 1, 10 times)

[0150] Selection: E1-H1 matching rate 95% > E2-H1 matching rate 75%, and the conditional probability of both is greater than 90%, therefore, select the E1 with the highest matching rate as the association node of H1.

[0151] When sending the association establishment data packet, a data packet with a forced NACK trigger (such as a low-power or interference injection packet) is included, and when sent, it is sent at a proportion of 20%;

[0152] If the hidden node H1 and all exposed nodes Ei find that the conditional probability is lower than 90%, re-initiate the association establishment stage; or after moving the exposed and hidden nodes, re-initiate the association calibration;

[0153] Running stage:

[0154] The sending end sends a data packet containing a target address (hidden node address);

[0155] The hidden node and the exposed node with a unique association relationship need to receive the message;

[0156] The exposed node feeds back ACK after successful reception;

[0157] The central control unit deduces the hidden node reception state by using the conditional probability according to the ACK feedback of the unique associated exposed node, and considers that the hidden node receives successfully if the conditional probability is higher than a threshold;

[0158] Example: if E1 feeds back ACK, the conditional probability P (S H1 =1|S E1 =1) ≈0.93, which is higher than the threshold 90%, and it is determined that H1 receives successfully. If E1 feeds back NACK, it is considered to fail, and retransmission is triggered.

[0159] Dynamic maintenance:

[0160] The central control unit can periodically or triggered by the change of the exposed node position to re-perform the association calibration.

[0161] Transmission strategy optimization:

[0162] In retransmission, power, dynamic FEC, coding rate and modulation mode can be adjusted.

[0163] Application example

[0164] Military communication: the command node broadcasts instructions, the hidden node (silent equipment) receives, the exposed node feeds back, and the system deduces the hidden node state according to the exposed node feedback and optimizes retransmission.

[0165] Internet of Things: low-power sensors are used as hidden nodes, and gateways are used as exposed nodes, and transmission parameters are dynamically adjusted to ensure data arrival rate.

[0166] Specific application field or related product of the application.

[0167] Military communication:

[0168] Application scenario: In the military command and control system, the hidden nodes (such as unmanned reconnaissance equipment, tactical terminal) remain radio silence in the running stage due to security needs, and cannot send feedback. The present application establishes the association with the exposed nodes (such as command nodes or relay stations) through a small amount of feedback of the hidden nodes in the calibration stage, and only relies on the ACK feedback of the exposed nodes to infer the receiving state of the hidden nodes in the running stage, to ensure reliable transmission of instructions.

[0169] Related products: tactical communication equipment, unmanned aerial vehicle communication module, military one-way broadcast system.

[0170] Internet of Things (IoT):

[0171] Application scenario: In the low-power wide-area network (such as LoRa, NB-IoT), sensor nodes (such as environmental monitors, smart meters) as hidden nodes, limited by battery capacity, avoid feedback in the running stage. The present application establishes the association with the gateway or relay node (exposed node) through limited feedback of the hidden node in the calibration stage, and uses the ACK of the exposed node to infer the receiving state of the sensor in the running stage, to dynamically adjust the transmission parameters (such as FEC, power), improve the data arrival rate, and prolong the device life.

[0172] Related products: low-power sensor, IoT gateway, smart home device, smart city monitoring terminal.

[0173] Satellite communication:

[0174] Application scenario: In the satellite broadcast system, the ground terminal (such as the receiving station in remote areas) as a hidden node, it is not suitable to send feedback in the running stage to reduce cost or exposure risk. The present application establishes the association with the proxy node (such as the nearby base station) through a small amount of feedback of the ground terminal in the calibration stage, and infers the receiving success rate through the ACK of the proxy node in the running stage, to optimize the satellite signal coding and retransmission strategy.

[0175] Related products: satellite ground receiving terminal, satellite communication module, remote broadcast equipment.

[0176] Related evidence of the technical effects obtained by the embodiments of the present application.

[0177] Initialization efficiency:

[0178] Evidence: In the association calibration stage, only 20 broadcasts are needed to establish the H1-E1 matching rate and conditional probability.

[0179] Comparison: The traditional method requires a large number of channel measurements (>100 times), and the present application quickly builds the association through a small amount of broadcast and forced NACK test (interference 10-20%), and the initialization time is shortened by 50-70%.

[0180] Enhanced concealment:

[0181] Evidence: Hidden node H1 is completely silent in the running phase, providing limited feedback only in the calibration phase, with exposed node E1 proxying feedback ACK. This design avoids signal exposure of H1, with no uplink transmission in running, meeting the needs of military communication and security-sensitive scenarios.

[0182] Comparison: Traditional RTS / CTS or HARQ mechanisms require frequent feedback from nodes, with high exposure risk. This invention ensures accuracy through E1's high matching rate and conditional probability, with better concealment than existing methods.

[0183] Environmental adaptability:

[0184] Evidence: The dynamic maintenance mechanism of the patent (re-calibration every 24 hours or movement > 50 meters) further ensures the stability of the matching rate and probability.

[0185] Comparison: Traditional channel prediction (CN110890930A) relies on complex parameters (such as RSSI, SNR), and is not robust to dynamic channels. This invention uses only ACK sequences (0 / 1), simplifying modeling and being more adaptable.

[0186] It should be noted that the embodiments of the present application can be realized by hardware, software or a combination of software and hardware. The hardware part can be realized by special logic; the software part can be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or a specially designed hardware. Those skilled in the art can understand that the above-mentioned devices and methods can be realized by computer executable instructions and / or included in processor control code, such as provided on a carrier medium, such as a magnetic disk, CD or DVD-ROM, a programmable memory, such as a read-only memory (firmware), or a data carrier, such as an optical or electronic signal carrier. The devices of the present application and their modules can be realized by hardware circuits, such as very large scale integrated circuits or gate arrays, semiconductors, such as logic chips, transistors, etc., or programmable hardware devices, such as field programmable gate arrays, programmable logic devices, etc., can also be realized by software executed by various types of processors, or by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0187] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement made by those skilled in the art within the technical scope disclosed by the present application, as long as it is within the spirit and principle of the present application, should be covered within the protection scope of the present application.

Claims

1. A method for data transmission towards a concealed node based on exposure node feedback, characterized in that, The method comprises the following steps: (1) the central control unit establishes the association relationship between the hidden node and the optimal exposure node; (2) the central control unit informs the exposure node to listen to the addresses of all the hidden nodes with the association relationship; (3) the exposure node receives the data packet with the target address being the hidden node, and feeds back an ACK after successful reception; (4) in the running stage, the hidden node remains silent and only the associated exposure node feeds back the reception status; (5) the central control unit dynamically adjusts the transmission strategy according to the feedback of the exposure node.

2. The method of claim 1, wherein, The establishment of the association relationship comprises position coarse screening and channel fine screening: the position coarse screening calculates the Euclidean distance according to the known position information of the hidden node and the exposure node, and selects the exposure node with a distance less than a preset threshold as a candidate node; The channel fine screening records the ACK sequence of the hidden node and the candidate exposure node by sending an association establishment data packet, and calculates the matching rate, which is equal to the ratio of the number of times that the ACK sequences of the hidden node and the exposure node are the same to the total number of times, and selects the exposure node with the highest matching rate as the only associated node, or selects the exposure node with the shortest distance if the difference between the matching rates is less than 5%.

3. A method for establishing hidden node associations based on ACK sequence matching, characterized in that, The matching rate of the ACK sequence of the hidden node and the candidate exposure node is calculated by sending the association establishment data packet, and the optimal exposure node is selected to establish the unique association.

4. The method of claim 3, wherein, The association establishment data packet contains a test packet that forces the triggering of a NACK, which is realized by reducing the transmission power by 8 to 12 dBm or injecting an interference signal with a bandwidth of 10 to 20% in a specific frequency band.

5. A method of estimating a reception probability of a hidden node, characterized by, The reception probability of the hidden node is calculated based on the conditional probability P(H=1|E=1), which is equal to the ratio of the number of times that the hidden node and the exposure node ACK at the same time to the total number of times that the exposure node ACKs, where H represents the hidden node and E represents the exposure node.

6. The method of claim 5, wherein, When the matching rate of the ACK sequence of the hidden node and all the exposure nodes is less than 70% and the conditional probability is less than 90%, the number of association establishment data packets is increased or the node position is moved to recalibrate the association relationship.

7. A method for dynamic maintenance of a relationship of a concealed node, characterized in that, Periodic maintenance and event-triggered maintenance are included: the periodic maintenance recalibrates the association relationship every 24 hours or other preset time period; the event-triggered maintenance recalibrates the association relationship when the node moves a distance exceeding a preset threshold.

8. The method of claim 7, wherein, The hidden node provides limited feedback in the association calibration stage and is completely silent in the running stage.

9. A method for dynamically adjusting a transmission strategy based on feedback from exposed nodes, characterized in that, At least one of the number of retransmissions, the forward error correction parameter, the coding rate, or the transmission power is adjusted according to the feedback information of the exposure node to improve the data transmission reliability of the hidden node.

10. A covert node oriented data transmission system based on exposure node feedback implementing the method of any of claims 1 to 9, characterized in that, It comprises: an association relationship establishment module, a notification module, a receiving module, a feedback module, and an adjustment module, the association relationship establishment module is used to establish the association relationship between the hidden node and the optimal exposure node, the notification module is used to inform the exposure node to listen to the addresses of the associated hidden nodes, the receiving module is used for the exposure node to receive the data packet of the hidden node, the feedback module is used to feed back the reception status in the running stage instead of the hidden node, and the adjustment module is used to dynamically adjust the transmission strategy according to the feedback of the exposure node.

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