Method for adjusting time slot access probability of underwater acoustic sensor network based on interference relation

Abstract

The invention discloses a method for adjusting the time slot access probability of an underwater acoustic sensor network based on an interference relation. The method aims at an underwater data acquisition scene, wherein a plurality of underwater sensing nodes are shared and accessed to a central receiving node according to time slots. Under the setting of any time slot length, the central receiving node can determine the interference relation of each time slot between the underwater sensing nodes according to the propagation time delay between each sensing node and the central receiving node, and accordingly, the access probability of each underwater sensing node is adjusted in a targeted manner, so that the effectiveness of the whole underwater acoustic sensing network is maximized. The method not only can effectively reduce the problems of long idle waiting time and serious data backlog in the traditional time slot access MAC protocol, but also can remarkably improve the overall network throughput on the premise of ensuring that the underwater sensing nodes share access media fairly.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater acoustic sensor networks, and particularly relates to a method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships. Background Art

[0002] Underwater information networks play a key role in ensuring interconnection and intelligent collaboration among different individuals in the marine space. They rely on underwater wireless communication technologies. Among them, underwater acoustic networks are the basic communication guarantee for marine informatization.

[0003] The medium access control (MAC) protocol, as an important part of network technology, determines whether multiple underwater acoustic communication nodes in the network can fairly and reliably share the channel, and is an extremely important part of underwater acoustic communication networks. The main characteristic of underwater acoustic MAC is the spatio-temporal coupling characteristic. Since the propagation speed of underwater acoustic waves is five orders of magnitude slower than that of radio waves, the arrival time of data packets depends not only on the transmission time but also on the spatial position between the transmitter and the receiver. The spatio-temporal coupling characteristic makes many MAC protocols applicable to radio networks unable to be directly applied to underwater acoustic networks. For example, the performance of the slotted random access protocol (Slotted-ALOHA) is greatly reduced under the long waiting influence in underwater acoustic networks, and the collision probability is relatively large; the carrier sensing result of code division multiple access (CDMA) type protocols (CSMA) cannot reflect the real channel situation; the DAP-MAC protocol evaluates and assigns different transmission probabilities to the transmission capabilities of sensing nodes to improve the performance of underwater acoustic sensor networks, but it analyzes based on longer time slots and does not consider the data packet interference between different time slots, and the throughput improvement is limited; although the cross-network layer and physical layer MAC protocol can combine the advantages of different protocols, its design is complex. The spatio-temporal uncertainty of underwater acoustic communication networks is the main reason for data packet collisions, that is, the poor performance of the MAC protocol. Summary of the Invention

[0004] The main purpose of the present invention is to optimize the existing random access competition protocol and provide a method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships, comprising the following steps: S1. Observation water area deployment Deploy sensing nodes and 1 central node. All nodes keep the clock synchronized, and divide the time into equal-length time slots according to the clock. Each sensing node only sends data packets at the beginning of each time slot; S2. In the initialization stage, the central node initializes the channel access probability of each sensing node to And save it to the neighbor table, and broadcast and send Hello messages carrying the transmission probability at the beginning of the time slot; S3. After each sensor node receives the Hello message from the central node, it enters the initialization phase and starts with a probability to send a Dst-Data packet to the central node in the next time slot. In the initialization phase, the sensor nodes need to repeat this process; S4. After the central node receives the Dst-Data packets of all sensor nodes, it calculates the distance between each sensor node and the central node according to the node number and transmission timestamp carried in the Dst-Data packet , indicating the distance between the th sensor node and the central node, , and records the information in the neighbor table. The neighbor table stores the interference range of the th sensor node calculated from the distance information, the interference factor and the packet transmission probability to be allocated , indicating the interference factor of the th sensor node, indicating the packet transmission probability to be allocated for the th sensor node; S5. The central node broadcasts an UPDATA packet to all neighbor sensor nodes to inform each sensor node of the corresponding access probability; S6. After receiving the UPDATA packet, the sensor node stops sending Dst-Data packets to the central node, ends the initialization phase and enters the data transmission phase. At the beginning of the next time slot, the sensor node accesses the channel according to the probability allocated by the central node and sends a DATA data packet to the central node; S7. After receiving the DATA data packet, the central node returns an ACK confirmation packet to inform the sensor node that the DATA data packet has been successfully received. The central node judges whether the distance between the sensor node and itself has changed according to the transmission timestamp carried in the DATA data packet. If the position changes, the central node recalculates the interference range , the interference factor and the transmission probability , and updates the neighbor table. The updated transmission probability will be informed to each sensor node through the UPDATA packet broadcast by the central node in the next time slot.

[0006] Furthermore, in step S1, the underwater acoustic sensor network adopts a star network, and all sensor nodes are randomly deployed within the maximum reception range of the central node to ensure that data can be transmitted in one hop. Assuming that the three-dimensional coordinates of the th sensor node and the central node are respectively expressed as , , the two coordinates shall satisfy the following conditions:

[0007] where represents the th sensing node distance between the sensing node and the central node, represents the maximum transmission distance of the sensor, that is, the distance between the transmitting and receiving nodes is less than the maximum transmission distance; Data transmission is carried out in time slots, which can reduce the uncertainty of data sending and receiving time to a certain extent, and then reduce the collision of data packets at the central node. Therefore, when the sensing node data arrives in this time slot, the data packet needs to be sent at the beginning of the next time slot. The time slot length is set as follows:

[0008] where is the data packet length, is the sending rate of the underwater acoustic Modem, is the speed of sound, is the transmission delay of the data; is the ratio of the maximum communication coverage range to the speed of sound, representing the maximum propagation delay; is the protection coefficient of the maximum propagation delay, and .

[0009] Further, in the step S2, the Hello message includes the packet type, all sensing node IDs, and the channel access probability corresponding to each sensing node, and is used to wake up the sensing nodes in the initialization stage and obtain the position information of the sensing nodes.

[0010] Further, in the step S3, the Dst-Data packet header sent by the sensing node includes the packet type, the sensing node ID, and the sending timestamp. The sending timestamp is used for the central node to calculate the distance between the two. The distance between the th sensing node and the central node

[0011] where are respectively the receiving and sending times of the th sensing node data packet.

[0012] Further, in the step S4, the th sensing node determines the time slots of possible interference sources according to its distance information from the central node, which is called interference time slots. The number of interference time slots is . If the The time slot for a sensing node to send a data packet is time slot 0, and the interference time slot number is , then , where:

[0013] Each time slot corresponds to an interference interval , that is, the data packet sent in the current time slot may collide with the data packets sent by the sensing nodes within the corresponding interference interval at the time slot. The interference interval corresponding to the time slot is an annular or circular area centered on the central node. The distance from any point within the interference interval to the central node satisfies the following conditions: .

[0014] Determining the interference source can reduce the uncertainty of data packet transmission and reception to a certain extent.

[0015] Furthermore, in step S4, the sensing nodes falling within the interference interval constitute the interference set of the th sensing node at the time slot. It should be noted that the interference set does not include the node itself. The number of nodes included in the interference set is called the interference factor of the th sensing node at the time slot. The interference factor of the th sensing node within all interference time slots is .

[0016] The interference factor further clarifies the interference situation of the node and is used to evaluate the degree of interference of the node.

[0017] Furthermore, in step S4, on the premise of ensuring that underwater sensing nodes fairly share the access medium, the transmission probability of sensing nodes is adjusted with the goal of maximizing the system throughput. The sensing nodes with less interference indicate that they have a strong ability to successfully transmit data packets, and are assigned a relatively large transmission probability. According to the interference factor of the th sensing node, the transmission probability is adjusted accordingly as follows:

[0018] Further, in step S5, the sending node broadcasts the sending probability to the receiving node through an UPDATA packet. The UPDATA packet includes the packet type, all sensor node IDs, and the sending probabilities corresponding to each sensor node. , and the transmission of the UPDATA packet is set to a different transmission frequency band from that of ordinary DATA packets to avoid conflicts. The UPDATA packet is used for updating the sending probabilities of sensor nodes, enabling the sensor nodes to enter the data transmission stage.

[0019] Further, in step S6, after generating a DATA packet, the node should access the channel for packet transmission with the latest allocated sending probability. The packet sent by the node includes the sensor node ID and the sending timestamp, for the central node to calculate the distance between the two and determine whether the position has changed. The continuous update of the distance information enables the central node to update the underwater acoustic sensor network topology information in a timely manner.

[0020] Further, in step S7, the ACK packet includes the packet type and the destination sensor node ID, and the transmission of the ACK packet is set to a different transmission frequency band from that of ordinary DATA packets to avoid conflicts. Underwater sensor nodes will inevitably drift due to some reasons. The central node continuously updating the neighbor table can ensure that each sensor node updates its sending probability in a timely manner to adapt to the latest node interference information.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects: First, the present invention is carried out under short time slots, that is , different from only considering the interference of data packets within a single time slot in the case of long time slots . Although the short time slot condition will increase the data packet collision between time slots, the sensor nodes can access the channel at a higher frequency, thereby improving the network performance. Second, for the short time slot situation, the present invention gives the interference relationship and interference factors between each sensor node to evaluate the degree of interference of the node, and obtains the compatibility relationship between the central node and each sensor node. In the present invention, the MAC protocol does not require handshaking, and the optimal transmission strategy of the sender can be determined through the utility optimization framework and combined with the compatibility relationship between nodes, which can significantly improve the performance of the underwater acoustic sensor network. Moreover, this MAC protocol can continuously update the position relationship and the optimal transmission strategy between nodes during the movement of the sensor nodes, so as to ensure the adaptation to the network mobility. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 It is a schematic diagram of the working processes of a sensing node and a central node for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships disclosed by the present invention; Figure 2 It is a schematic diagram of an interference interval involved in a method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships disclosed by the present invention; Figure 3 It is a schematic diagram of four types of data packet structures involved in a method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships disclosed by the present invention; Figure 4 It is a simulation diagram of the successful transmission probability of data packets in a method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships disclosed in Embodiment 2 of the present invention; Figure 5 It is a simulation diagram of the normalized throughput in a method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships disclosed in Embodiment 2 of the present invention. Specific embodiments

[0024] In order to enable those skilled in the art of the present technology to better understand the solutions of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope protected by the present application.

[0025] Referring to "embodiment" in the present application means that the specific features, structures, or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in the present application can be combined with other embodiments.

[0026] Embodiment 1 This embodiment discloses a method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships, as Figure 1 shown, including the following steps: S1. Observation water area deployment One sensing node and one central node. All nodes maintain clock synchronization and divide time into equal-length time slots according to the clock. Each sensing node only sends data packets at the beginning of each time slot; In one embodiment, the underwater acoustic sensor network adopts a star network. All sensing nodes are randomly deployed within the maximum reception range of the central node to ensure that data can be transmitted in one hop. Assume that the three-dimensional coordinates of the th sensing node and the central node are respectively represented as , , and the two coordinates should satisfy the following conditions:

[0027] Among them represents the th sensing node and the distance between the central node. represents the maximum transmission distance of the sensor, that is, the distance between the receiving and sending nodes is less than the maximum transmission distance; When the node data arrives in this time slot, the data packet can only be sent at the beginning of the next time slot. The time slot length is set as follows:

[0028] Among them is the data packet length, is the sending rate of the underwater acoustic Modem, is the speed of sound, is the transmission delay of the data; is the ratio of the maximum communication coverage range to the speed of sound, representing the maximum propagation delay; is the protection coefficient of the maximum propagation delay, and .

[0029] S2. Initialization phase: The central node initializes the channel access probability of each sensing node to and saves it to the neighbor table, and broadcasts and sends Hello messages carrying the sending probability at the beginning of the time slot; In this embodiment, the Hello message includes the packet type, all sensing node IDs, and the channel access probability corresponding to each sensing node.

[0030] S3. After each sensing node receives the Hello message from the central node, it enters the initialization phase and sends a Dst-Data packet to the central node with a probability of at the beginning of the next time slot. The sensing node needs to repeat this process during the initialization phase; In one embodiment, the Dst-Data packet header sent by the sensing node includes the packet type, the sensing node ID, and the sending timestamp. The The distance between a sensing node and the central node The calculation formula is as follows:

[0031] Where are respectively the receiving and sending times of the data packet of the th sensing node.

[0032] S4. After the central node receives the Dst-Data packets of all sensing nodes, it calculates the distance between each sensing node and the central node according to the node number and the sending timestamp carried in the Dst-Data packet , represents the distance between the th sensing node and the central node, , and records the information in the neighbor table. The neighbor table stores the interference interval of the th sensing node calculated from the distance information , the interference factor and the allocated data packet sending probability , represents the interference factor of the th sensing node, represents the allocated data packet sending probability of the th sensing node; In this embodiment, the th sensing node determines the time slots of possible interference sources according to its distance information from the central node, which is called the interference time slots. The number of interference time slots is . If the time slot when the th sensing node sends a data packet is time slot 0 and the interference time slot number is , then , where:

[0033] Each time slot corresponds to an interference interval , that is, the data packet sent in the current time slot may collide with the data packet sent by the sensing node within the corresponding interference interval at the th time slot. The interference interval corresponding to the th time slot is an annular or circular area centered on the central node. The distance from any point within the interference interval to the central node satisfies the following conditions: .

[0034] falls within the interference interval The sensing nodes within form the th sensing node's interference set in the time slot . The interference set contains the number of nodes, which is called the th sensing node's interference factor in the time slot . The th sensing node's interference factor in all interference time slots is .

[0035] According to the th sensing node's interference factor , adjust the transmission probability correspondingly as follows:

[0036] The central node records the distances to each sensing node, each sensing node's interference set, each sensing node's interference factor, and each sensing node's transmission probability obtained from the above calculations in the neighbor table, as shown in Table 1: Table 1. Central Node Neighbor Table

[0037] S5. The central node broadcasts an UPDATA packet to all neighbor sensing nodes to inform each sensing node of the corresponding access probability; In this embodiment, the sending node broadcasts the transmission probability to the receiving node through the UPDATA packet. The UPDATA packet includes the packet type, all sensing node IDs, and the transmission probabilities corresponding to each sensing node . The UPDATA packet transmission is set to a different transmission frequency band from that of ordinary DATA data packets to avoid conflicts.

[0038] S6. After receiving the UPDATA packet, the sensing node stops sending Dst-Data packets to the central node, ends the initialization phase, and enters the data transmission phase. At the start of the next time slot, the sensing node accesses the channel according to the probability assigned by the central node and sends a DATA data packet to the central node; In this embodiment, after generating the DATA data packet, the node should access the channel with the newly assigned transmission probability for data packet transmission. The data packet sent by the node includes the sensing node ID and the transmission timestamp, for the central node to calculate the distance between the two and determine whether the position has changed.

[0039] After the central node receives the DATA data packet, it returns an ACK acknowledgment packet to inform the sensing node that the DATA data packet has been successfully received. The central node determines whether the distance between the sensing node and itself has changed according to the transmission timestamp carried in the DATA data packet. If the position changes, the central node recalculates the interference range of each sensing node , interference factor and transmission probability , and updates the neighbor table; the updated transmission probability will be informed to each sensing node through the UPDATA packet broadcast by the central node in the next time slot.

[0040] In this embodiment, the ACK packet includes the packet type and the ID of the destination sensing node, and the ACK packet transmission is set to a different transmission frequency band from that of ordinary DATA data packets to avoid conflicts.

[0041] In this embodiment, the network emulator NS-3 is used to simulate the scenario described in this example. Node data packets arrive in a Poisson distribution, with an intensity . The underwater sensing nodes are evenly distributed within the receiving range of the receiving node. Table 2 shows the normalized throughput and the packet successful transmission probability obtained after 5000s of simulation in the NS-3 emulator.

[0042] Table 2. Simulation result table of NS-3 network emulator

[0043] Embodiment 2 In Embodiment 2, the steps S1 to S7 in Embodiment 1 are parameterized and simulated on an open-source simulation platform. The number of sensing nodes is set to 2, 4, 6, 8, 10, 12, 14, 16, 20; The value is set to 0.6, 0.9, 1.2; the communication range of the node is set to ; the transmission delay of the data is set to ; the ratio of the maximum communication coverage range to the speed of sound is set to ; node data packets arrive in a Poisson distribution, with an intensity . The simulation time is 5000s. The normalized throughput and the packet successful transmission probability of the underwater acoustic sensor network are statistically calculated, and the performance of the MAC protocol in the present invention is compared with that of the S-ALOHA protocol. In the S-ALOHA protocol, if the sensing node data packet arrives in this time slot, it will access the channel with a probability of 1 in the next time slot. The simulation results of the packet successful transmission probability are as Figure 4 shown, and the simulation results of the normalized throughput are as Figure 5As shown, N-ALOHA in the simulation diagram is the experimental result of the present invention.

[0044] It can be seen from the simulation results that when the number of nodes is 2, 4, or 6, the performance of the two protocols is similar. When the number of nodes is greater than 6, after the slot access probability is adjusted, the normalized throughput and the packet successful transmission probability in the MAC protocol are significantly higher than those in the S-ALOHA protocol, indicating that the improved MAC protocol can effectively reduce the occurrence of collisions in the network by adjusting the transmission probability of the sensing nodes when the network conditions deteriorate, and seek concurrent transmission opportunities to ensure that the overall performance of the network does not change significantly. The experimental results show that the MAC protocol after the slot access probability is adjusted can effectively suppress the performance deterioration caused by network congestion.

[0045] It should be noted that for the foregoing method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, certain steps can be performed in other sequences or simultaneously.

[0046] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered that the scope described in this specification.

[0047] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationships, characterized in that It includes the following steps: S1. Deployment in the Observation Water Area Deploy [number of sensor nodes] sensor nodes and 1 central node. All nodes maintain clock synchronization and divide time into equal-length time slots according to the clock. Each sensor node only sends data packets at the beginning of each time slot; S2. In the initialization phase, the central node initializes the channel access probabilities of each sensing node to and saves them in the neighbor table, and broadcasts Hello messages carrying the transmission probability at the beginning of the time slot; S3. After each sensing node receives the Hello message from the central node, it enters the initialization phase and starts to send Dst-Data packets to the central node with a probability in the next time slot. In the initialization phase, the sensing nodes need to repeat this process; After the central node receives the Dst-Data packets from all the sensing nodes, it calculates the distances between each sensing node and the central node according to the node numbers and transmission timestamps carried in the Dst-Data packets , denotes the distance between the th sensing node and the central node. The information is recorded in the neighbor table, which stores the interference intervals, interference factors, and the allocated data packet transmission probabilities calculated based on the distance information for the th sensing node. denotes the interference factor of the th sensing node, and denotes the allocated data packet transmission probability of the S5. The central node broadcasts an UPDATA packet to all neighbor sensor nodes to inform each sensor node of the corresponding access probability; S6. After receiving the UPDATA packet, the sensor node stops sending Dst-Data packets to the central node, ends the initialization phase and enters the data transmission phase. At the start of the next time slot, the sensor node accesses the channel according to the probability assigned by the central node and sends a DATA data packet to the central node; After the central node receives the DATA data packet, it returns an ACK confirmation packet to inform the sensing node that the DATA data packet has been successfully received. The central node determines whether the distance between the sensing node and itself has changed based on the transmission timestamp carried in the DATA data packet. If the position has changed, the central node recalculates the interference intervals of each sensing node , interference factor and transmission probability , and updates the neighbor table; the updated transmission probability will be informed to each sensing node through the UPDATA packet broadcast by the central node in the next time slot.

2. The method for adjusting the time slot access probability of an underwater acoustic sensor network based on interference relationships according to claim 1, wherein In step S1, the underwater acoustic sensor network adopts a star network, and all sensor nodes are randomly deployed within the maximum reception range of the central node to ensure that data can be transmitted in one hop. Assume that the three-dimensional coordinates of the th sensor node and the central node are respectively represented as , . The two coordinates should satisfy the following conditions: Among them represents the th sensing node and the distance between the central node. represents the maximum transmission distance of the sensor, that is, the distance between the receiving and transmitting nodes is less than the maximum transmission distance; When the node data arrives in this time slot, the data packet can be sent only at the start of the next time slot. The time slot length is set as follows: wherein is the data packet length, is the transmission rate of the underwater acoustic Modem, is the speed of sound, is the transmission delay of the data; is the ratio of the maximum communication coverage range to the speed of sound, representing the maximum propagation delay; is the protection coefficient of the maximum propagation delay, and .

3. The method for adjusting the time slot access probability of an underwater acoustic sensor network based on interference relationship according to claim 1, characterized in that, In step S2, the Hello message includes the packet type, all sensor node IDs, and the channel access probability corresponding to each sensor node.

4. The method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationship according to claim 1, wherein In the step S3, the Dst-Data packet header sent by the sensing node includes a packet type, a sensing node ID, and a transmission timestamp. The distance between the th sensing node and the central node is calculated as follows: wherein are respectively the receiving and sending times of the data packet of the nth sensing node.

5. The method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationship according to claim 2, wherein In the step S4, the th sensing node determines the time slots of possible sources of interference according to the distance information between it and the central node, which are called interference time slots, and the number of interference time slots is . If the time slot for the th sensing node to send a data packet is time slot 0, and the interference time slot number is , then , where: Each time slot corresponds to an interference range , that is, the data packet sent in the current time slot may collide with the data packet sent by the sensing node in the corresponding interference range in the time slot. The interference range corresponding to the time slot is an annular or circular area centered on the central node. The distance from any point in the interference range to the central node satisfies the following conditions: 。 6. The method for adjusting the time slot access probability of an underwater acoustic sensor network based on interference relationship according to claim 1, characterized in that In the step S4, the sensing nodes falling within the interference interval constitute the interference set of the th sensing node in the th time slot. The number of nodes included in the interference set is called the interference factor of the th sensing node in the th time slot. The interference factor of the th sensing node in all interference time slots is .

7. The method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationship according to claim 1, characterized in that, In the step S4, according to the interference factor of the th sensing node, the transmission probability is adjusted correspondingly as follows: 。 8. The method for adjusting the time slot access probability of an underwater acoustic sensor network based on interference relationship according to claim 1, wherein In the step S5, the sending node broadcasts the sending probability to the receiving node through an UPDATA packet, and the UPDATA packet includes the packet type, all the sensor node IDs, and the sending probabilities corresponding to each sensor node. The transmission of the UPDATA packet is set to a different transmission frequency band from that of the ordinary DATA packet to avoid conflicts.

9. The method for adjusting the time slot access probability of an underwater acoustic sensor network based on interference relationship according to claim 1, characterized in that, In step S6, after generating the DATA data packet, the node should access the channel with the newly assigned transmission probability for data packet transmission. The data packet sent by the node includes the sensor node ID and the transmission timestamp, so that the central node can calculate the distance between the two and determine whether the position has changed.

10. The method for adjusting the slot access probability of an underwater acoustic sensor network based on interference relationship according to claim 1, characterized in that, In step S7, the ACK packet includes the packet type and the destination sensor node ID, and the ACK packet transmission is set to a different transmission frequency band from that of ordinary DATA data packets to avoid conflicts.

Images