Super-multi-hop wireless ad hoc network communication method based on full-duplex relay cluster

Abstract

The invention relates to a super-multi-hop wireless ad hoc network communication method based on a full duplex relay cluster, which is applied to a linear chain communication network and comprises the following steps: initiating RTS / CTS interaction between a head end node and a tail end node to perform clustering, and determining a plurality of relay nodes as cluster head nodes according to SINR measured in the interaction process; channel reservation is carried out, whether a busy cluster head node exists or not is judged, if the busy cluster head node exists, the cluster head node closest to the busy cluster head node is used as a receiving node, full duplex handshake is carried out with the receiving node, data to be sent are sent to the receiving node, and the receiving node repeats the channel reservation and full duplex handshake process. And carrying out relay forwarding on the received to-be-sent data until a destination node, and if no busy cluster head node exists, carrying out full-duplex handshake with the destination node and sending the to-be-sent data to the destination node. According to the invention, the transmission time delay of long-distance super multi-hop and the blocking probability during sudden large flow can be greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, and particularly relates to a super multi-hop wireless ad hoc network communication method based on full-duplex relay cluster. BACKGROUND

[0002] In wireless communication, relay refers to forwarding data through intermediate nodes to expand the coverage of the network and improve the quality of communication. Relay technology is divided into two main modes: amplify-and-forward (AF) and decode-and-forward (DF).

[0003] Among them, AF relay usually adopts a half-duplex mode, which needs to separate the receiving and transmitting processes through time division duplex. Although this method avoids the interference caused by simultaneous receiving and transmitting, the delay caused by time division separation will be accumulated in the super multi-hop case, thereby greatly increasing the end-to-end delay. The time delay generated by AF relay using full-duplex system is very small, but the disadvantage is that not only the signal is amplified, but also the noise and interference signal are amplified at the same time. DF relay will decode and analyze the received signal to recover the original information, and then re-encode and forward the original information to make up for the interference and noise accumulation caused by AF relay, but at least one complete data block decoding is required, so the processing delay is obvious. At the same time, if the DF relay uses a half-duplex system, the source node will continue to send the next packet of content, which will make it difficult for the source node message queue to be released in the case of sudden large traffic, and in the case of multi-node communication, the blocking will be accumulated due to the channel reservation mechanism, thereby reducing the communication reliability.

[0004] In addition, in the engineering environment of linear super multi-hop ad hoc networks such as power private network monitoring and railway line monitoring, nodes are not densely deployed as in general ad hoc network scenarios, but are strictly distributed along the line direction, and the distance between nodes is usually 500-1000 meters, and the overall structure is highly linear and chain-like. Therefore, such networks are extremely sensitive to the availability of single nodes: the failure of any relay node or its antenna, radio frequency front end and other components may cause the link at this position to be completely broken, thereby preventing upstream data from being transmitted and continuously accumulating at the source side and along the line nodes, eventually causing large-scale congestion or even network collapse.

[0005] Existing solutions mostly focus on dynamic routing or cluster reconstruction caused by channel fading and node mobility, but lack a fast recovery mechanism for the typical linear super multi-hop scenario of "link complete interruption caused by node damage". Especially in the full-duplex link structure, once the cluster head node or key AF node fails, the original cluster structure will not be able to continue to maintain, and the traditional hop-by-hop detection method will produce a large delay accumulation, which cannot meet the requirements of the recovery speed in the super multi-hop scenario. SUMMARY

[0006] The technical problem solved by the present application is to provide a full-duplex relay cluster-based super multi-hop wireless ad hoc network communication method, which can greatly reduce the transmission delay of long-distance super multi-hop and the blocking probability in the case of burst traffic.

[0007] The technical solution adopted by the present application to solve its technical problem is to provide a full-duplex relay cluster-based super multi-hop wireless ad hoc network communication method, applied to a linear chain communication network, comprising:

[0008] Obtaining a head node and an end node, and taking the nodes therebetween as relay nodes;

[0009] Initiating RTS / CTS interaction between the head node and the end node to form clusters, and determining a plurality of relay nodes as cluster head nodes according to the SINR measured by each relay node and the end node in the interaction process;

[0010] Obtaining a source node and a destination node for data transmission;

[0011] Reserving a channel for the data transmission link, judging whether there is a busy cluster head node, if there is a busy cluster head node, taking the cluster head node closest to the busy cluster head node as a relay node, performing full-duplex handshake with the relay node and sending the data to be sent to the relay node, repeating the channel reservation and full-duplex handshake process by the relay node, and forwarding the received data to be sent until the destination node, if there is no busy cluster head node, performing full-duplex handshake with the destination node and sending the data to be sent to the destination node.

[0012] Further, the RTS / CTS interaction between the head node and the end node to form clusters, and the determination of a plurality of relay nodes as cluster head nodes according to the SINR measured by each relay node and the end node in the interaction process, comprises:

[0013] After the head node listens to the idle channel, a first RTS frame is configured to form clusters, and is sent to the end node;

[0014] The relay nodes sequentially receive and forward the first RTS frame;

[0015] If the current relay node finds that the measured SINR is greater than a set threshold, and the number of nodes in the current cluster is equal to the maximum number of nodes, the current relay node is taken as a cluster head node;

[0016] If the current relay node finds that the measured SINR is less than a set threshold, the first CTS frame is sent to the previous node to prompt that the SINR is insufficient;

[0017] After the end node receives the first RTS frame, if the measured SINR is greater than a set threshold, a second CTS frame is returned to feed back the cluster completion, otherwise a first CTS frame is sent to the upper node to prompt that the SINR is insufficient;

[0018] The first relay node receiving the first CTS frame is taken as the cluster head node.

[0019] Further, when clustering, each node keeps a fixed time length of measurement time slot to send a reference signal after sending the RTS frame or the CTS frame, so that the next node can measure the SINR; after the clustering is completed, the reference signal is no longer sent.

[0020] Further, the cluster head node re-packages the received first RTS frame and sends it to the destination node, and sends a new reference signal in the measurement time slot, and the new reference signal is orthogonal to the reference signals of other clusters.

[0021] Further, the channel reservation for the data transmission link judges whether there is a busy cluster head node, if there is a busy cluster head node, the cluster head node closest to the busy cluster head node is taken as the relay node to perform full-duplex handshake, including:

[0022] After the source node listens to the idle channel, a second RTS frame is configured to perform channel reservation, and is sent to the destination node;

[0023] After the cluster head node receives the second RTS frame, if it is busy, a third CTS frame including error information is returned, if it is idle, the second RTS frame is forwarded;

[0024] When there is a busy cluster head node between the source node and the destination node, the first cluster head node receiving the third CTS frame is taken as the relay node, the received third CTS frame is re-packaged into a fourth CTS frame including the relay node information to perform full-duplex handshake, and is sent to the source node.

[0025] Further, the data to be sent is sent to the relay node, including:

[0026] The source node determines the relay node and the window size according to the received fourth CTS frame, packages the data to be sent in the window into a plurality of data frames including the relay node, the destination node and the packet sequence number, and sequentially sends them to the relay node;

[0027] The cluster head node analyzes the received data frame and buffers the analyzed data packet, performs window synchronization verification based on the packet sequence number, if the window is synchronized, an ACK frame is returned to feed back the receiving state of the data packet in the window, and the received data frame is forwarded to the next cluster head node, otherwise a NACK frame including the current window information is returned;

[0028] After the last cluster head node receives the ACK frame, it judges whether retransmission is needed based on the received state of the data packets in the window, and if retransmission is needed, the corresponding data packets are extracted from the cache for retransmission, otherwise, a new data frame is generated after the sliding window and sent.

[0029] After the last cluster head node receives the NACK frame, a new data frame is generated and sent after adjusting the window according to the window information in the NACK frame.

[0030] Further, each cluster head node maintains a fixed-length ACK reception window, and if the current cluster head node appears ACK timeout for multiple times in succession, it is judged that there may be a link fault between the current cluster head node and the next cluster head node.

[0031] Further, after detecting the suspected fault, an RTS / CTS interaction is initiated between the two cluster head nodes where the link fault may exist to perform local clustering, and the node that does not feed back RTS in two consecutive periods is determined as a fault node, the previous node of the fault node becomes a temporary cluster head node, and the hop-by-hop link reconstruction is realized by increasing the transmission power and / or reducing the modulation order, and direct communication is established with the next effective node.

[0032] Further, the temporary cluster head node sends a fifth CTS control frame with an error code to the upstream node to stop new data writing and sending, and after the local re-clustering is completed, the CTS control frame is broadcasted to the adjacent nodes to announce the local link recovery.

[0033] Further, the cluster head node works in the DF mode, and the relay node of the non-cluster head node works in the AF mode.

[0034] Beneficial effects

[0035] Compared with the prior art, the application has the following advantages and positive effects:

[0036] The application can reduce the end-to-end delay and improve the transmission efficiency by dynamically clustering based on SINR measurement, working in the DF mode for the cluster head to process decoding, and working in the AF mode for the remaining relay to only amplify and forward with low latency.

[0037] The application sets cluster head node to maintain ACK receiving window, if finding continuous timeout, then positioning failure node quickly through local recombination cluster, and upgrading previous node as temporary cluster head, jumping to connect next effective node through increasing power / reducing modulation order, avoiding whole network reconfiguration, thereby reducing recovery delay and lowering; after confirming failure, temporary cluster head sends CTS with error code to upstream, informing node to stop new data writing and sending, preventing data accumulation causing congestion, and guaranteeing service continuity after link recovery. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is the power super multi-hop ad hoc network architecture schematic diagram of the embodiment of the application;

[0039] Figure 2 is the media control protocol frame structure schematic diagram of the embodiment of the application;

[0040] Figure 3 is the clustering flow chart of the embodiment of the application;

[0041] Figure 4 is the time slot allocation schematic diagram of the embodiment of the application;

[0042] Figure 5 is the source node clustering flow chart of the embodiment of the application;

[0043] Figure 6 is the relay node clustering flow chart of the embodiment of the application;

[0044] Figure 7 is the destination node clustering flow chart of the embodiment of the application;

[0045] Figure 8 is the handshaking flow chart of the embodiment of the application;

[0046] Figure 9 is the source node reservation handshaking flow chart of the embodiment of the application;

[0047] Figure 10 is the relay / relay / destination node reservation handshaking flow chart of the embodiment of the application;

[0048] Figure 11 is the data packet transmission and retransmission flow chart of the embodiment of the application;

[0049] Figure 12 is the sending data packet flow chart of the embodiment of the application;

[0050] Figure 13 is the receiving data packet flow chart of the embodiment of the application;

[0051] Figure 14This is a comparison chart of end-to-end latency in embodiments of the present invention;

[0052] Figure 15 This is a throughput comparison chart of embodiments of the present invention. Detailed Implementation

[0053] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0054] The embodiments of the present invention relate to a multi-hop wireless ad hoc network communication method based on full-duplex relay clusters. The purpose is to overcome the shortcomings of long-distance multi-hop wireless ad hoc network communication, such as the inability to guarantee service quality due to transmission delay and the decrease in reliability due to insufficient throughput during sudden large traffic surges. The present invention proposes to achieve full-duplex communication by using a multi-hop wireless ad hoc network form with full-duplex clusters and by implementing adaptive clustering and full-duplex handshaking through a media control protocol.

[0055] A typical application scenario for a multi-hop ad hoc network is as follows: Figure 1 As shown, the network consists of mobile terminal nodes with wireless transceiver capabilities. Each node functions as both a host and a router, achieving multi-hop transmission of data packets from the source node to the destination node through cooperative forwarding. The linear multi-hop self-organizing network adopts a chain topology, with nodes interconnected in a peer-to-peer manner. Monitoring video data is transmitted between towers in a multi-hop manner with low latency and high reliability to meet the monitoring needs of maintenance personnel.

[0056] This implementation method uses media control protocol frames to interact with data and control signals, and mainly includes an adaptive clustering scheme, a full-duplex access scheme, and a data packet retransmission scheme.

[0057] like Figure 2 As shown, the Media Control Protocol (MCP) frame includes a frame control field to distinguish between five frame types: RTS, CTS, ACK, and data frames. The frame control field differentiates between these five types. RTS and CTS also participate in the cluster initialization process, using cluster identifier settings to distinguish between normal service and cluster initialization. Furthermore, by designing a full-duplex control identifier, the handshake process from the initial half-duplex mode to full-duplex can be completed during RTS and CTS. By utilizing buffered multi-data packet continuous transmission, the full-duplex feature can be more efficiently utilized to achieve higher throughput. The payload exists only in data frame types; other frame types use a shorter frame structure.

[0058] The adaptive clustering scheme is implemented by initiating RTS / CTS interactions between the head node and the tail node. At the same time, based on the SINR measured by each relay node and the tail node during the interaction, several relay nodes are determined as cluster head nodes to achieve adaptive clustering of relay nodes.

[0059] The relay network in this embodiment can be applied to both full-duplex and half-duplex modes. However, due to potential communication conflicts, a full-duplex handshake is required before initiating full-duplex communication to enable internal nodes to operate in full-duplex mode. This paper proposes a scheme combining channel reservation and full-duplex handshake, utilizing the media control protocol frame structure mentioned above. Furthermore, to better utilize the full-duplex characteristics, and considering the special features of decentralized, multi-hop transmission in multi-hop ad hoc networks, a cache-based, high-efficiency multi-data full-duplex access scheme is proposed. This scheme first obtains the source and destination nodes for data transmission, then reserves channels for the data transmission link, and selects whether to perform full-duplex access based on the busy status of the cluster head node. Specifically, it includes:

[0060] Channel reservation is performed for the data transmission link to determine if there are busy cluster head nodes;

[0061] If a busy cluster head node exists, the cluster head node closest to the busy cluster head node will be taken as the receiving node. A full-duplex handshake will be performed with the receiving node and the data to be sent will be sent to the receiving node. The receiving node will repeat the channel reservation and full-duplex handshake process and relay the received data to be sent until it reaches the destination node.

[0062] If no busy cluster head node exists, a full-duplex handshake is performed with the destination node and the data to be sent is sent to the destination node.

[0063] During data transmission, a data packet retransmission scheme needs to be designed based on feedback from the next-hop node, specifically including:

[0064] The source node determines the receiving node and window size based on the received fourth CTS frame, packages the data to be sent in the window into several data frames including the receiving node, destination node and packet sequence number, and sends them sequentially to the receiving node.

[0065] The relay node receives the data frame from the previous node, parses the received data frame and buffers the parsed data packet, performs window synchronization verification based on the packet sequence number, and returns an ACK frame to feedback the reception status of the data packet in the window if the window is synchronized, and forwards the received data frame to the next node; otherwise, it returns a NACK frame including the current window information.

[0066] After the previous node receives the ACK frame, it determines whether retransmission is needed based on the reception status of the data packets within the window. If retransmission is needed, the corresponding data packets are retrieved from the buffer and retransmitted; otherwise, a new data frame is generated and sent after the sliding window is opened.

[0067] After receiving a NACK frame, the previous node adjusts the window based on the window information in the NACK frame, generates a new data frame, and sends it.

[0068] To address the problem of transient link interruptions caused by node or antenna failures in linear multi-hop networks, leading to packet accumulation and congestion propagation, some preferred embodiments can adopt a comprehensive mechanism based on the aforementioned adaptive clustering mechanism. This mechanism involves rapid breakpoint detection, local cluster reconstruction, and full-duplex rapid access recovery. By achieving rapid cluster structure repair and link reconstruction within a local area, this mechanism can quickly restore network connectivity and ensure service continuity without requiring a complete network-wide re-clustering.

[0069] The following description, in conjunction with specific embodiments and frame settings, further illustrates this implementation method.

[0070] Example 1:

[0071] Based on the adaptive clustering scheme of the protocol frames in Example 1, it can accommodate both half-duplex and full-duplex communication. The entire process operates in time slots as follows: Figure 3 As shown, the specific steps are described below.

[0072] Step 1: Determine the multi-hop ad hoc network topology and initialize the configuration of each node in the network.

[0073] 1) Network topology: In this embodiment, the nodes in the self-organizing network are roughly located in a straight line, and the nodes are networked in a chain structure. The distance between two nodes is set to a range of 500-1000 meters according to the engineering requirements.

[0074] 2) Node Configuration: Each node is configured with a full-duplex system with buffering capabilities, containing two transceiver antennas, one pointing towards the preceding node and the other towards the following node. To reduce self-interference, all antennas are directional. Each node is in decode-forward mode by default and can switch between amplify-forward and decode-forward modes based on received data packets. Each node is equipped with a baseband module. This module needs to obtain the device's MAC address and the mode assigned to the device in the previous clustering process during power-on. This information should be able to be read and written multiple times using FLASH memory to enable adaptive re-clustering in the event of partial node failure.

[0075] 3) During the clustering process, the time slot allocation structure of RTS / CTS frames is as follows: Figure 4As shown, after each node sends RTS / CTS, a measurement time slot needs to be maintained to send a reference signal so that subsequent nodes can measure the SINR value.

[0076] Step 2: The farthest node sends the clustering command.

[0077] like Figure 5 As shown, the farthest node listens for channel idle time before sending data. If the medium is busy at the current moment, it waits for a random backoff time, then listens for the carrier again, repeating the above process until the channel is idle. The farthest node configures an RTS frame, setting the cluster identifier in the RTS frame to 1, and all other frame control settings to 0. The source node is its own MAC address, and the destination node address is the address of the last node. The node sends the RTS to the next-hop node in the control time slot of the current frame and sends a reference signal in the measurement time slot. To avoid interference between forwarding clusters, the same reference signal is sent until the cluster head node. The other cluster uses the remaining orthogonal reference signals.

[0078] If the next node successfully receives the RTS signal without errors, it will send the RTS control signal to both ends in the same way within the specified time. The farthest node considers the transmission successful after receiving the RTS. In subsequent time slots, the node will only send signals in the measurement time slot until it receives the CTS signal and considers the clustering complete.

[0079] Step 3: Relay nodes process clustering commands

[0080] like Figure 6 As shown, when a relay node receives an RTS signal forwarded from the previous hop node and successfully decodes it, the relay node first determines whether to enter cluster mode based on the cluster identifier in the RTS signal. Once in cluster mode, the relay node first checks the cluster head node's number to see if the number of nodes in the current cluster is less than the maximum number of nodes.

[0081] During the measurement time slot, each node sends a reference signal to the next node and calculates the SINR. If the SINR is lower than the threshold, it proceeds to step A in step four. If the SINR is higher than the threshold and the number of nodes in the current cluster is equal to the maximum number of nodes, it proceeds to step B in step four; otherwise, it continues to send RTS signals to continue the framing process.

[0082] Step 4 (A): Relay Node Cluster Head Processing (A)

[0083] During the control frame time of the next time slot, a CTS command with error information is sent to the previous node to indicate insufficient SINR. After receiving the command, the previous node becomes the cluster head. It no longer needs to send reference signals and continues to send CTS commands forward in the next time slot until the previous cluster head. After repackaging the RTS frame, it sends a continuation frame to the next node.

[0084] Step 4 (B): Relay Node Cluster Head Processing (B)

[0085] Once the node is identified as the cluster head, a CTS command without error information is sent to the previous node in the next time slot to notify the cluster head that it has been formed, stop sending reference information, and send a repackaged RTS frame to the next node to continue framing.

[0086] Step 5: Destination Node Clustering

[0087] like Figure 7 As shown, after successfully receiving the RTS packet, the destination node still needs to check the SINR in the measurement time slot. If the SINR meets the requirements, it first sends a CTS command to notify the nodes within the cluster that the cluster establishment is complete and no longer needs to send reference signals. After waiting for the reserved event, it sends an ACK to notify all nodes that the clustering is complete. After receiving the cluster, the node retains its assigned AF / DF mode and exits the clustering mode, then forwards the ACK frame upwards until all nodes have been notified. Otherwise, the destination node repeats process A in step four and listens again.

[0088] Example 2:

[0089] Based on the channel reservation and full-duplex handshake method of the adaptive clustering scheme in the above embodiments, the entire handshake process is as follows: Figure 8 As shown, the specific steps are described below.

[0090] Step 1: The source node sends an RTS to initiate the service.

[0091] like Figure 9 As shown, before initiating a service, an idle source node needs to store one service data packet in a buffer and count the number of buffered data packets. Then, it configures the corresponding frame type RTS, sets the full-duplex flag to 0 in the full-duplex control / multi-frame control section (representing that it is currently in half-duplex mode), and fills in the buffered data packet sequence number and expected duration. Subsequently, the node monitors whether there is a service in progress on the channel or checks the NAV status of its own counter to determine whether it has a relay service as a DF node. If a service is in progress, it pushes the data packet into the buffer until the previous service is released before competing for access again. If no service exists, it sends RTS frames bidirectionally to reserve and handshake the channel.

[0092] Step 2: After receiving the RTS, the relay cluster head node feeds back the CTS based on the channel and service conditions.

[0093] like Figure 10As shown, after the source node initiates an RTS, the AF node receives the signal, amplifies it, and forwards it to the cluster head node. Since the source node listens to the channel before sending, it can ensure that the AF node is not in a state of amplifying and forwarding other information at this time, thus avoiding conflicts. After the RTS reaches the cluster head node, there are two possibilities: if the cluster head node is idle and can transmit services, then the cluster head node forwards the received RTS frame to the destination node in the next time slot. If the current cluster head node is busy and is conducting services, it will send a CTS frame with error information back to the source node after waiting for SIFS. If there are relay nodes between the current cluster head node and the source node, the relay node closest to the current cluster head will repackage the CTS frame with error information after receiving it and send it back to the source node. The CTS frame includes the full-duplex flag in the full-duplex control set to 1, indicating that it is acting as a full-duplex relay node to accept services, the expected duration of the accepted service data, the error information, and the MAC address of the node acting as the accepting point. After receiving a CTS frame, the node between the receiving node and the source node adjusts the full-duplex module and NAV value according to the expected duration of the service received in the frame.

[0094] After receiving the RTS frame, the destination node will repackage the CTS frame and send it back to the source node. The CTS frame includes a full-duplex flag set to 1 in the full-duplex control. After receiving the CTS frame, the node between the destination and source nodes will adjust the full-duplex module and NAV value according to the expected duration of the service undertaken in the frame.

[0095] Step 3: The source node performs services after receiving the CTS frame.

[0096] The source node receives CTS frames, which fall into three categories. The process for each category is as follows:

[0097] 1. If there is no error message in the CTS frame, it means that the channel from the current source node to the destination node has been reserved. Then, after waiting for SIFS time, data will be transmitted to the source node.

[0098] 2. If a CTS frame contains error information but also the address of the receiving node, it indicates that the channel is currently occupied, but a segment of the channel has already been reserved. In this case, data transmission to the receiving node will begin after waiting for SIFS time.

[0099] 3. If a CTS frame contains an error message but the address of the receiving node is missing, it indicates that the service is currently unavailable. The service will then be forced to abort and retry.

[0100] Example 3:

[0101] Based on the data packet transmission and retransmission of the channel reservation and full-duplex handshake method in the above embodiments, the entire process is as follows: Figure 11 As shown, the specific steps are described below.

[0102] Step 1: Send data packets continuously according to the preset window size.

[0103] After receiving a CTS frame and confirming that service can proceed, the source node waits for the SIFS time and then continuously transmits data frames to the receiving / destination node. Each data frame should contain the source node address, destination node address, and receiving node address; if no receiving node is specified, the address should be 0. Each data packet needs to be entered with a corresponding sequence number. After transmitting all data packets within the window, the node listens on the channel for ACK.

[0104] Step 2: The relay cluster head node receives and buffers the data frame, and sends back an ACK.

[0105] When a cluster head node successfully receives a data frame from its predecessor, if the data frame sequence number is within the window, it indicates that the window is currently synchronized with the predecessor's. The ACK bitmap then marks successful reception based on the current window sequence number arrangement. The window size and data packet count are synchronized during the handshake phase. If the data frame sequence number is not within the window, it indicates that the window is currently out of sync. This could be due to an error in the previous ACK frame, leading to rejection of the current data frame and the feedback of a NACK frame containing the current window status for synchronization with the predecessor. Because the window size is synchronized, the cluster head node sends an ACK to the predecessor after a predetermined time for data packet sequential transmission. Simultaneously, upon successful data packet reception, forwarding is initiated, sending successfully parsed data packets forward.

[0106] Step 3: After receiving the ACK, retransmit and adjust the window based on the bitmap.

[0107] After receiving an ACK feedback, the cluster head node or source node retransmits the missing data from the transmit buffer window according to the bitmap, assembles data frames from the buffer using a sliding window based on the bitmap, updates the NAV time in the data packets according to the retransmission status, and sends them sequentially. If a NACK frame is received, it indicates that the window synchronization failure with the subsequent node may be due to the loss of control frames such as ACK frames. In this case, the window needs to be resized according to the window and data frame reception information in the NACK frame, and the data frames within the window need to be retransmitted. This send-receive-feedback-retransmission process is repeated until all data packets have been transmitted. The node then ends the service process and enters the NAV waiting state. It can attempt to initiate the service again after the NAV ends.

[0108] Step 4: Receiving node / destination node receives data packets

[0109] In this process, the actual receiver consists of only two nodes: the receiving node and the destination node. If there is no receiving node, the destination node only needs to perform the feedback process in step two after receiving the data packet. If it is the receiving node, in addition to the feedback process in step two, it also needs to attempt to establish a channel reservation and handshake with the destination node. If the reservation is successfully established, the process differs from that of the source node, except that the data packet address needs to remain unchanged and the receiving node is retained for confirmation of the address in the ACK. This process is processed in parallel with the process of the actual receiver, where the receiving window and the transmitting window are independent but can share the same buffer. If the receiving window and the transmitting window are synchronized, the receiving node degenerates into a relay cluster head node and continues the decoding and forwarding process.

[0110] The data packet sending and receiving processes are as follows: Figure 12 and Figure 13 As shown, the source node executes the data packet sending process, the relay node executes both the data packet sending and receiving processes simultaneously, and the receiving node first buffers the received data packets before completing the handshake with subsequent nodes and then executing the data packet sending process. The source node only executes the data packet receiving process.

[0111] Example 4:

[0112] The fast recovery mechanism under network outage conditions based on the data packet transmission and retransmission methods in the above embodiments specifically includes:

[0113] 1. Window-based reception failure statistics: Each cluster head node is responsible for sending and receiving data packets after clustering and maintains a fixed-length ACK reception window. When the current node experiences multiple consecutive ACK timeouts, a failure alarm mechanism is automatically triggered, and it is determined that there may be a link failure or node failure between the current node and the next cluster head node.

[0114] 2. Fault Confirmation and Local Link Reconstruction Mechanism: Upon detecting a suspected fault, a node enters a local cluster re-reconstruction process, re-initiating RTS / CTS interaction to confirm the breakpoint location. If a node fails to send forward RTS feedback within two consecutive RTS / CTS cycles, that node is considered to have failed. The node preceding it is automatically promoted to a temporary cluster head node and achieves skip-link reconstruction by increasing transmit power and reducing modulation order, directly establishing communication with the next available node. The first available node after the failed node is also automatically marked as an auxiliary temporary cluster head to maintain backward stability of the original cluster, ensuring that communication can be restored without global reconstruction of the cluster structure.

[0115] 3. Upstream Congestion Notification and Cache Freeze Mechanism: After a link break, if the upstream node continues to send data, the node's cache will quickly fill up, causing an overflow. To prevent this, this invention sends a CTS control frame with an error code to the upstream node after the break is confirmed, notifying the upstream node to enter a cache freeze and timer pause state, stopping new data writing and transmission contention until partial cluster reassembly is completed.

[0116] 4. Local link recovery and forward and backward cluster synchronization: After the link reconstruction in step (2) is completed, the new temporary cluster head node broadcasts CTS control frames to the adjacent nodes in front and behind, announces the local link recovery and releases the buffer freeze state, and re-applies for channel occupation in the back according to the interruption event, so as to realize the rapid and stable recovery of the network.

[0117] like Figure 14 and Figure 15 As shown, simulations were performed under common bit error rates. By comparing the transmission delay and throughput of this scheme with those of the traditional CSMA / CA half-duplex mode in multi-hop networks, it is easy to see that this scheme can significantly reduce the data transmission rate of end-to-end network transmission and the transmission delay of ultra-multi-hop linear networks.

Claims

1. A multi-hop wireless ad hoc network communication method based on full-duplex relay clusters, applied to linear chain communication networks, characterized in that, include: Obtain the first and last nodes, and use the node between them as the relay node; Initiate RTS / CTS interaction between the head node and the end node to perform clustering. Based on the SINR measured by each relay node and the end node during the interaction, determine several relay nodes as cluster head nodes. Obtain the source and destination nodes for data transmission; For the data transmission link, channel reservation is performed to determine whether there is a busy cluster head node. If there is a busy cluster head node, the cluster head node closest to the busy cluster head node is selected as the receiving node. A full-duplex handshake is performed with the receiving node and the data to be sent is sent to the receiving node. The receiving node repeats the channel reservation and full-duplex handshake process and relays the received data to be sent until it reaches the destination node. If there is no busy cluster head node, a full-duplex handshake is performed with the destination node and the data to be sent is sent to the destination node.

2. The communication method according to claim 1, characterized in that, The process involves initiating RTS / CTS interactions between the head node and the tail node to form clusters. Based on the SINR measured by each relay node and tail node during the interaction, several relay nodes are determined as cluster head nodes, including: After the first node listens for an idle channel, it configures the first RTS frame to perform clustering and sends it to the last node. The relay node sequentially receives and forwards the first RTS frame; If the current relay node finds that the measured SINR is greater than the set threshold, and the number of nodes in the current cluster is equal to the maximum number of nodes, then it will become the cluster head node. If the current relay node finds that the measured SINR is less than the set threshold, it sends the first CTS frame to the next node to indicate that the SINR is insufficient. After receiving the first RTS frame, if the measured SINR is greater than the set threshold, the end node returns the second CTS frame to indicate that the clustering is complete; otherwise, it sends the first CTS frame to the upper node to indicate that the SINR is insufficient. The first relay node to receive the first CTS frame becomes the cluster head node.

3. The communication method according to claim 2, characterized in that, During clustering, after each node sends an RTS or CTS frame, it maintains a fixed-length measurement time slot to send a reference signal, enabling the next node to measure SINR; after clustering is completed, the reference signal is no longer sent.

4. The communication method according to claim 3, characterized in that, The cluster head node repackages the first RTS frame it receives and sends it to the destination node, and sends a new reference signal in the measurement time slot. The new reference signal is orthogonal to the reference signals of other clusters.

5. The communication method according to claim 1, characterized in that, The process of reserving a channel for the data transmission link, determining whether a busy cluster head node exists, and if a busy cluster head node exists, then using the cluster head node closest to that busy cluster head node as the receiving node for a full-duplex handshake, includes: After the source node listens for an idle channel, it configures a second RTS frame to reserve the channel and sends it to the destination node. After receiving the second RTS frame, if the cluster head node is busy, it returns a third CTS frame including error information; if it is idle, it forwards the second RTS frame. When there is a busy cluster head node between the destination node and the destination node, the first cluster head node to receive the third CTS frame acts as the receiving node, repackages the received third CTS frame into a fourth CTS frame including the receiving node information to perform a full-duplex handshake, and sends it to the source node.

6. The communication method according to claim 5, characterized in that, Sending the data to be sent to the receiving node includes: The source node determines the receiving node and window size based on the received fourth CTS frame, packages the data to be sent in the window into several data frames including the receiving node, destination node and packet sequence number, and sends them sequentially to the receiving node. The cluster head node parses the received data frames and buffers the parsed data packets. It performs window synchronization verification based on the packet sequence number. If the window is synchronized, it returns an ACK frame to provide feedback on the reception status of the data packets within the window and forwards the received data frames to the next cluster head node. Otherwise, it returns a NACK frame that includes the current window information. After the previous cluster head node receives the ACK frame, it determines whether retransmission is needed based on the reception status of the data packets within the window. If retransmission is needed, it retrieves the corresponding data packets from the buffer and retransmits them; otherwise, it generates a new data frame and sends it after sliding the window. After receiving a NACK frame, the previous cluster head node adjusts the window according to the window information in the NACK frame, generates a new data frame, and sends it.

7. The communication method according to claim 6, characterized in that, Each cluster head node maintains a fixed-length ACK reception window. If the current cluster head node experiences multiple consecutive ACK timeouts, it is determined that there may be a link failure between the current cluster head node and the next cluster head node.

8. The communication method according to claim 7, characterized in that, Upon detecting a suspected fault, an RTS / CTS interaction is initiated between two cluster head nodes that may have a link fault to perform local clustering. The node that has not fed back RTS within two consecutive cycles is identified as a faulty node. The node preceding the faulty node becomes a temporary cluster head node. By increasing the transmit power and / or reducing the modulation order, a skip link reconstruction is achieved, and communication is directly established with the next valid node.

9. The communication method according to claim 8, characterized in that, The temporary cluster head node sends a fifth CTS control frame with an error code to upstream nodes to stop writing and sending new data until the local cluster reassembly is completed. Then, it broadcasts CTS control frames to the adjacent nodes to announce that the local link has been restored.

10. The communication method according to claim 1, characterized in that, Cluster head nodes operate in DF mode, while relay nodes that are not cluster head nodes operate in AF mode.

Images