194 results about "Underwater sensor networks" patented technology

The invention discloses one wireless sensor network communication method and system, which comprises the following steps: process center point sends broadcast in initial time and the point measures self and process center distance through the broadcast information; network point organism forms cluster structure and selecting cluster point front network gate and common point front cluster head in initial time; cluster member collects data in set time gap and sends to cluster head; the cluster head and front network gate transmit time gap data to process central point.

The invention discloses a target tracking system and a target tracking method for an underwater sensor network. The target tracking system comprises a land network and a water area network, wherein the water area network comprises multiple underwater target tracking clusters and a water surface treatment center; and the underwater target tracking clusters comprise multiple underwater sensor nodes and a cluster head node. A target state is tracked in combination with an adaptive UKF (Unscented Kalman Filter) and a PF (Particle Filter) on the basis of correcting signal acquisition time delays of the sensor nodes. The tracking error caused by different sources of signals acquired by the sensor nodes at the same moment is reduced by correcting the time delays, so that a target can be more reliably tracked; and the adaptive UFK automatically adjusts a system noise weighing coefficient according to target maneuvering situation to more properly describe a practical target motion state, so that the shortcoming of inaccuracy of target maneuvering of a target motion model is overcome, an important function with more posteriori information is provided for the particle filter, the particle degeneracy is reduced, and the tracking precision is improved.

The invention discloses a measuring method for network nodes of an underwater wireless sensor and a device. The method comprises the steps of: carrying out the interconversion of an electric signal and an ultrasonic signal by utilizing an ultrasonic transducer so as to complete underwater ultrasonic communication; calculating the relative distance between the nodes and the device by utilizing the transmission delay between node communication as well as the propagation velocity of ultrasound underwater; and collecting the underwater environmental data information from the position of the nodes by utilizing a sensor specially used in underwater detection. The device comprises a microcontroller, an FSK modulating and power amplifying module and a transducer which are connected in series; a hydrophone, a weak signal amplifier, an FSK demodulating chip and a microcontroller which are connected in series; a power management module is used for supplying power for a circuit and managing a power supply; and an external spreading interface module is used for connecting with a corresponding interface sensor and peripherals. The invention realizes the underwater sound communication function with low cost and low power consumption and the distance measuring function between the network nodes of the underwater wireless sensor.

The invention relates to an underwater sensor network media access control protocol based on a TDMA and applied in an underwater sensor network with high bit error rate, high time delay and low bandwidth. The invention is an improved underwater sensor network media access control protocol based on the TDMA on the basis of the traditional TDMA. The concrete method comprises that: different optimal protection time is set according to different propagation delay in concrete network environments in which each node is positioned, so as to avoid conflicts brought by the change of time delay; delay time is utilized to distribute propagation time for each node, so as to solve problem of conflict-free propagation of the nodes of an underwater sensor; the delay time is encapsulated into super frames, so as to notify each node about data packet transmission time; finally, lightweight synchronous communication is realized. The underwater sensor network media access control protocol lowers the requirement for accurate synchronization of each node of a TDMA mechanism to some extent, reduces conflicts and improves channel utilization rate and network throughput.

The invention discloses a method for collecting high time resolution data simulated clusters of an underwater sensor. Firstly, a network node distribution model is set up, based on which, the network is divided into a plurality of subregions according to space, and a subregion data collection time consuming model is setup, and the time necessary for all subregions to collect data is estimated; the network is more reasonably divided into a plurality of subreions, thereby achieving the balance between the division of the subregions and the collection time consumption. One executor node is distributed for each subregion after optimized combination, and the distribution position is determined so as to collect data more efficiently. When the executors reach the designation, node routes in the subregions are set up so as to construct simulated clusters. The executor nodes are used as cluster heads, in such a small-sized network, the simulated clusters collect monitoring data of other fixed nodes at a high speed, thereby realizing the collection of the high time resolution monitoring data of a wireless sensor network; after the data are collected, the simulated clusters are dismissed, and the network is switched back to the original field monitoring state.

The invention generally relates to the technical field of network communication, and particularly relates to a method for routing an underwater sensor network. The method for routing comprises the following constituent parts: (1) node grade definition; (2) node grade information acquiring and updating processes; (3) neighbor node information recording; (4) directional flooding mechanism based on grade difference; (5) adaptive routing step based on the grade difference, node density and residual energy; and (6) differential geographical routing step based on the grade difference and distance. The method has the following advantages that the best next hop adaptive routing is determined on the basis of the neighbor table information to reduce redundant paths, so that the energy efficiency is improved to a great extent; and the adaptive routing adopts immediate routing, so that the inhibition time of the conventional underwater UWSN (underwater wireless sensor network) routing to a received package is avoided, and the time delay from terminal to terminal is reduced. A great deal of simulation experiments prove that through an underwater sensor network adaptive routing protocol based on the difference, the energy consumption can be reduced to a great extent, the time delay from terminal to terminal is reduced, the node utilization equity is improved, and the whole network life time is prolonged.

The invention discloses an underwater sensor network positioning method, which integrates a three-dimensional Euclidean distance estimation method, an iterative position estimation method and a DV-Hop algorithm, and for completing the positioning of common nodes, gives selection criteria of one-hop upgrade reference nodes, two-hop upgrade reference nodes and next-hop upgrade reference nodes for forwarding positioning request information packets. The method comprises the following steps: calculating the distance between a common node and a two-hop upgrade reference node by using the three-dimensional Euclidean distance estimation method and the DV-Hop algorithm, after the coordinates of the node are calculated by using a four-edge measurement method, calculating a positioning error and a trust value according to the coordinates and the distance between the node and a reference node, comparing the magnitude relation of the trust value and a threshold value, and determining whether the node is positioned successfully and becomes an upgraded reference node; and the iterative position estimation method is used for broadcasting a beacon information packet containing the position of a common node after the common node is positioned successfully, and assisting the positioning of other common nodes. The method disclosed by the invention is applicable to the static or dynamic positioning of nodes in large-scale underwater wireless sensor networks.

The invention discloses a data collection method based on AUV position prediction in an underwater sensor network. The data collection method comprises the following steps: the AUV cruises in the network according to a pre-determined helical orbit to perform data collection and adjusts the orbit, wherein the helical orbit can be decomposed into circling motion on the horizontal direction and a uniform linear motion on the vertical direction, a node calculates whether itself is within the collection area of the AUV according to its own position and the orbit of the AUV, the node within the collection area waits for the AUV to arrive at vicinity of the node and performs with the AUV, and the node beyond the collection area forwards data to the collection area through multiple hops. The data collection method supports the AUV to cruise in the network to perform data collection, thereby reducing the energy consumption of the node, and the AUV does not need to broadcast a data packet while cruising in the network, thereby reducing the communication cost.

The invention discloses a depth adjustment method used for underwater sensor network nodes and based on a Thiessen diagram. A plurality of underwater sensors nodes are dripped on a target water area water surface in a random mode and in uniform distribution probability, and a collection node is arranged in the middle of the target water area water surface and serves as a management control center of the underwater sensor nodes in the water area. The Thiessen diagram of the underwater sensor nodes in various water depth layers is generated in a layer-by-layer mode through the collection node from a target water area water surface layer, through calculation of area of a Thiessen polygon corresponding to the underwater sensor nodes, closeness degree of the underwater sensor nodes in the horizontal direction is inspected, and the overstocked nodes in a horizontal layer are subsided to a next layer until to the bottom of the target water area. According to the facts that the nodes are arranged in a random dripped mode and an underwater coverage area is enlarged through subsiding mechanism of the nodes, the depth adjustment method used for the underwater sensor network nodes and based on the Thiessen diagram reduces arrangement cost of an underwater sensor network.

The invention relates to the technical field of network communication, in particular to an underwater sensor network media access control method. The underwater sensor network media access control method based on a state comprises a layered distribution type spread spectrum code allocation algorithm based on discrete probability, a channel access control mechanism based on a state and sending power control. According to the method, channel access is controlled on the basis of state information of receiving nodes in a neighbor table, interference caused to node transmission data in a sending state in a half duplex system is avoided, and the problems of long time delay, high energy consumption and channel idling and the like which are caused by a traditional RTS / CTS (request to send / clear to send) handshaking mechanism in an underwater sensor network are solved; near-far effect of code division multiple access (CDMA) is reduced, and energy efficiency is improved. The underwater sensor network media access control method is suitable for sparse or dense topological underwater sensor network communication, and serving as an effective and practical technical scheme, the underwater sensor network media access control method has good application prospects in underwater data collection, environmental monitoring, disaster prevention and resource monitoring and the like.

The invention provides an underwater sensor network optimized deployment method based on an important target region. The underwater sensor network optimized deployment method comprises two basic steps of construction of a water domain monitoring model and optimized deployment of an underwater sensor network: 1, constructing the important water domain monitoring model by using a main component analysis method; 2, implementing the optimized deployment of the whole network by using a weighted factor adjustment particle swarm optimization algorithm. According to the underwater sensor network optimized deployment method based on the important target region, by the construction of the important water domain monitoring model, the optimized deployment of the whole network can be realized, so that the problem about water quality monitoring of a complicated water domain can be flexibly and effectively solved.

The invention discloses a stable underwater communication node awakening signal detection method. The stable underwater communication node awakening signal detection method comprises the following steps of: S1, emitting a dual-frequency or multi-frequency awakening signal; S2, according to a set initial frequency, transform point number and frequency resolution ratio, executing CZT (chirp z transform) on a unit circle on the awakening signal; S3, searching an extreme value of a zoom spectrum of CZT, judging a signal as the awakening signal if an estimated relative frequency interval and relative amplitude relationship between frequency components are kept unchanged, or judging the signal is not the awakening signal; and S4, after the signal is determined as the awakening signal, powering on an integral communication node to enable the node to be transferred into a working state, and when the node completes working, cutting off a power supply to enable the node to be transferred into a sleeping state. According to the stable underwater communication node awakening signal detection method disclosed by the invention, due to the high frequency resolution ratio, multiple groups of frequencies can be adopted for combination to awaken a plurality of nodes of an underwater sensor network without worrying about mutual interference, so that detection false-alarm is greatly reduced and a service life of the underwater wireless sensor network is prolonged.

The invention belongs to an underwater sensor network data transmitting technology, and particularly provides a response-first-request underwater sensor network MAC (media access control) protocol (RFR-MAC) by aiming at spatial uncertainty caused by underwater sensor network underwater acoustic long propagation delay characteristics to realize time-space fairness. The method comprises the following steps of dynamically adjusting an RTS (request to send) competition stage to determine node priority transmitting data which is firstly requested to be sent in time, introducing a CTS (clear to send) delay stage to delay to send a CTS control frame, thereby avoiding conflicts of data frames, using a CTS backoff mechanism to prolong the CTS delay stage, and meanwhile, adopting a competition backoff mechanism to further improve the time-space fairness of competition channels. The experiment shows that the protocol has good time-space fairness, and meanwhile, the protocol has good throughout capacity, and lower energy consumption and time delay.

The invention discloses an opportunity data return method of an underwater sensor network. The method includes the steps: deploying multiple underwater sensor nodes in an interested sea area to monitor and collect data, deploying multiple surface buoy nodes on the surface of the corresponding sea area, collecting data observed and collected by the sensor nodes through a base station arranged on the surface of a sea or on a seashore or through ships on the sea, and analyzing and processing the data. The underwater sensor nodes (sources) broadcast the collected data to the buoy nodes on the surface of the sea after the data has undergone rateless coding. The underwater buoy nodes that have succeeded in receiving source coding packets sends coding packets which a sink does not succeeded in receiving to the sink through a wireless link. The sink returns confirmation information to the surface buoy nodes and the sources after receiving enough coding packets, and then the next around of transmission is started. The reliability of an underwater acoustic communication system can be improved in a steady and highly efficient manner, the transmission delay is minimized, and the capacity is improved.

The invention discloses a distance-based energy balance dynamic geographic routing method in an underwater sensor network, and the method comprises the steps: establishing and maintaining a neighbor node table; selecting neighbor nodes that forward a data packet according to the neighbor node table to form a data packet forwarding area; calculating a forwarding factor; and setting the time for theadjacent sensor nodes in waiting for the forwarding of the data packet according to the forwarding factor. The method performs routing selection through the coordinate position information of the nodes, effectively compensates for some defects of a topology information routing method, dynamically adjusts the size of the forwarding area, reduces excessive redundant nodes for sending data, and enables a routing protocol to have dynamic adaptability. The greater the remaining energy of a node is, the easier it is to forward data, and vice versa. Finally, energy balance can be achieved.

The invention discloses a method for positioning nodes of an underwater sensor network. The method comprise the following steps: a) establishing a space rectangular coordinate system; b) establishing a moving anchor node which moves along an isometric helical line; c) broadcasting anchor node coordinate information; d) receiving the coordinate information; e) judging whether the positions are determined; f) judging whether four pieces of coordinate information are received; g) judging whether the four anchor node coordinates are collinear; h) calculating the positions. According to the method for positioning the nodes of the underwater sensor network, a sensor node can determine the coordinate of self according to the four received collinear anchor node coordinates, so that the difficulty in deploying anchor nodes of the underwater sensor network is solved, and the network deployment cost is lowered at the same time; as position information of four non-collinear anchor nodes is adopted for positioning, the method complexity is reduced, and the method is easy to realize; according to characteristics of underwater deployment of the nodes, the search space of a particle group is limited, and the positioning method efficiency is improved.

The invention relates to a space grid region division based greedy routing method in an underwater sensor network. The method comprises three stages of (1) selecting a next region, wherein an underwater three-dimensional network monitoring region is treated as a cube and divided equally into a plurality of small cube regions, and a source node selects an optimum forwarding region according to information of the position of the source node and the position of a target node to which information is finally transmitted;; (2) selecting a node in a target region for greedy forwarding, wherein measurement criteria such as node residual energy, duty ratio sleep mechanisms and credibility are considered to select a next waking node to guarantee connectivity of the whole network; and (3) optimizing a path, wherein a tag-based optimizing strategy is introduced to eliminate path rings when path rings exist to select an optimum path. According to the greedy routing method, routing region division and credibility of nodes in the underwater sensor network are considered, so that the reliability and the extendibility of routing are increased, and the network performance is improved.

The invention discloses an underwater sensor network routing method of a plurality of mobile convergent nodes. The underwater sensor network routing method comprises a layering phase and a transmission phase, wherein in the layering phase, each convergent node forms a layered structure at the center; in the transmission phase, a source node transmits data to a target convergent node according to the nth layered structure of the convergent node s. The source node transmits the data to a next-hop forwarding node by two policies; the next-hop forwarding node transmits the data by using the same manner until a data packet is successfully sent to the convergent nodes. According to the underwater sensor network routing method, the policies are selected through the target convergent node so that the length of successively sending the data packet to a path can be effectively reduced, and furthermore, the energy consumption is reduced. The forwarding node selection policy optimizes a transmission path so that the deliverability rate of the data packet is improved.

The invention belongs to the field of multi-sensor fusion estimation, and provides a multi-target passive positioning method based on an underwater sensor network. A strategy of combining feature level and decision level information fusion is adopted. Multi-target detection based on an underwater acoustic sensor network has the problems of high energy consumption, low positioning precision, largetime delay and the like. Aiming at the defects, the algorithm provided by the invention performs multi-target azimuth estimation on a single node array, extracts the characteristics of a plurality oftarget signals, transmits the characteristics to a fusion center for processing, performs azimuth estimation on multiple targets in real time, and further obtains position information. The algorithm reduces the communication information amount between nodes while improving the accuracy of multi-target position estimation. Therefore, the method has important practical significance for solving the actual underwater multi-target passive positioning problem.

The invention relates to a method for establishing a trust model in an underwater sensor network. The method comprises steps: using a request node to perform neighbor relation determination on a target node and establishing direct trust according to data communication between the request node and the target node and the residual energy of the target node; requesting recommend trust from a common neighbor of the request node and the target node if the number of the historical communication information interaction between the request node and the target node is insufficient, and further calculating the trust value of the target node; selecting a multi-hop neighbor node to perform trust calculation if the request node and the target node are not neighbor nodes; and achieving trust assessment of the node for sensing data on the basis of node trust calculation and updating the trust value of the sensor node. The method may update the trust value of the sensor node and prevent problems of trust transmission and trust combination under the circumstance of existence of multiple recommend paths. In cooperation with sensing data trust calculation, the method achieves high precision of node trust calculation and has a wide application value.

The invention discloses an underwater moving target extended Kalman filtering tracking method based on distributed sensor energy ratios. First logarithms of energy ratios of every two sensors are introduced as observation values, thereby obtaining an observation sequence of different moments; then based on the state of motion of a target, a nonlinear observation equation is converted into an approximately linear observation equation in an error-controllable range, and a linear state-space model is built; then an extended Kalman filtering sequential iterative solution algorithm of the state-space model is derived; a linear least squares (ER-LS) positioning algorithm is utilized to position the moving target which enters an underwater sensor network range, thereby obtaining an initial value of extended Kalman filtering; and finally, an underwater target motion trail with improved performance is obtained through sequential filtering.

The invention discloses an underwater sensor network routing method based on multiple underwater autonomous vehicles. The method comprises the steps of network initialization, data transmission, network restoration and the like. In the network initialization stage, a dynamic network hierarchical structure is constructed; the underwater common sensor nodes in the underwater sensor network are layered, so that a progressive gradient is formed, and a data packet can be transmitted to a corresponding underwater autonomous vehicle according to the hierarchical relationship of the underwater commonsensor nodes in a subsequent data transmission stage. In the data transmission stage, the underwater common sensor node sorts the transmission priorities of the candidate nodes according to the composite forwarding factors of the candidate nodes, and transmission coordination of the candidate node set is carried out based on the transmission priorities of the candidate nodes, so that data packet conflicts are avoided, and the network delay is reduced; in the network restoration stage, the network restoration model is utilized to carry out periodic restoration when the initial dynamic network hierarchical structure changes, so that the transmission performance of the underwater sensor network is improved.

The invention discloses a distributive positioning method of a mobile underwater sensor network node. The method comprises the following steps: self-positioning an anchoring node on time according to a surface float equipped with a GPS device to obtain the position information of the anchoring node at the current time as the initial position information; building a prediction model of the anchoring node according to the initial position information; sequentially predicting the position at the next time based on the initial position information and the prediction model and according to the preset positioning cycle; acquiring the initial position information of a general node by referring to the initial position information of other underwater nodes; sequentially predicting the position at the next time based on the initial position information of the general node and according to the group characteristics and the preset positioning cycle. According to the method, the distributive positioning algorithm is adopted, which fully utilizes the movement model of the underwater node, and thus the positioning information of each node is obtained on the premise that the communication times of the anchoring node and the general node are reduced, and as a result, the energy consumption is decreased.

The invention discloses a high-availability data collection method based on multiple AUVs in an underwater sensor network. The method comprises the following steps: constructing an underwater sensor network model, patrolling, by a plurality of autonomous underwater vehicles AUVs, in the network according to a predefined spiral trajectory for data collection, and periodically adjusting the patrol trajectory; and calculating, by a node, whether itself is within the collection area of one or more autonomous underwater vehicles AUVs according to own location and the trajectories of the autonomousunderwater vehicles AUVs. The node within the collection area performs communication after the autonomous underwater vehicle AUV arriving at the vicinity of the node to upload data; and the node beyond the collection area forwards the data to the node within the collection area through multiple hops. When the autonomous underwater vehicle AUV is faulty, a gateway node discovering the fault broadcasts a control packet and performs fault processing. By adoption of the high-availability data collection method, the energy consumption and the communication overhead of the node are reduced, and thehigh availability of the network is guaranteed.

The invention belongs to the technical field of underwater sensor network communication and provides a media access control method based on spatial fairness in an underwater sensor network. The media access control method comprises the following steps of: setting a time label in a request message sent by each node; setting a competition counter for each node, calculating the times of the node which participates in competition, carrying out data transmission once the node participates in competition successfully, and zeroing the counter; after a receiving node receives the request message, sending a response message after delaying for a certain time called as an SD stage; and searching competition times information contained in the request message received in the SD stage by the receiving node, setting the weight value of a transmitting node to be higher and adding the transmitting node into a high-right-value queue once the competition times of certain nodes exceeds a competition threshold, or setting the weight value of the transmitting node to be lower and adding the transmitting node into a low-right-value queue. According to the media access control method disclosed by the invention, the transmission fairness can be achieved under the multi-competition condition.

The invention discloses a two-stage bidirectional prediction data acquisition method based on underwater edge equipment, and the method comprises the steps: transferring calculation from a centralizedcloud layer to a distributed edge layer, and constructing a bottom layer-edge-cloud three-layer data collection mode; historical information-based analysis and data prediction are carried out by utilizing the mobility and computing power of the underwater edge equipment, so that sound wave communication is effectively reduced on the premise of ensuring accurate data transmission, and the energy consumption of the sensor is reduced. By considering the differentiation capability of heterogeneous equipment, different prediction algorithms are adopted for two layers of nodes of an edge layer anda bottom layer, and an underwater data collection process is converted into a two-stage bidirectional data prediction process. The method can be applied to an underwater sensor network data collectionmechanism.

The invention relates to a method for detecting Sybil attack in underwater wireless sensor networks. The method includes three steps: by the aid of anchor nodes, (1) identifying suspicious nodes: identifying the suspicious nodes in the networks according to received information packets; (2) determining Sybil nodes: calculating state evaluation values of the suspicious nodes and determining the Sybil nodes by means of comparing with position information of the suspicious nodes; (3) separating the Sybil nodes: reporting the Sybil nodes to base stations which delete the Sybil nodes from the networks. The method has the advantages that hostile Sybil attack can be effectively detected, safety of the networks can be guaranteed, and hardware conditions for the nodes neither are limited strictly nor limited by specific information or specific nodes and have good expansibility.

The invention discloses an electromagnetic type underwater sensor network node carrying device, which comprises a buoyancy assembly, an underwater sensing control assembly and an anchoring assembly. The underwater sensing control assembly comprises a sealed cabin, a underwater sensor network node placed in the sealed cabin, an electromagnetic control circuit, a power circuit, a data line and an electromagnetic iron plate fixed on the lower surface of the sealed cabin, the underwater sensor network node, the power circuit and the electromagnetic control circuit are respectively fixed on the upper portion, the middle portion and the lower portion of the sealed cabin, and the data line is connected with the underwater sensor network node and the electromagnetic control circuit. The buoyancy assembly is connected with the underwater sensing control assembly and located on the top portion of the whole device, and the anchoring assembly is located on the lower portion of the device. The electromagnetic type underwater sensor network node carrying device needs no manual intervention, and is simple in updating maintenance, convenient in operation, low in cost, strong in practical applicability, good in stability, long in service life and applicable to underwater tests and marine monitoring under various situations.

The invention belongs to the technical field of underwater sensor networks and provides a media access control method based on motion prediction. Four kinds of messages of RTS, CTS, DATA and ACK are used for communication, all nodes broadcast signals randomly, according to received signal transmission time and known transmission speed, each node computes the distance between the node and an adjacent node, the obtained distance between the node and the adjacent node is broadcast, accordingly, each node records the distance values between all of the nodes, and a distance matrix D is used for representation; through the current speed and the previous motion speed of the nodes, the motion speed in the future of the nodes is subjected to linear prediction, then the distance values in the distance matrix D are updated, the maximum value in the distance matrix D is obtained, and reservation slot length is computed; and communication is carried out through a sub-slot reservation transmitting mechanism. On the basis that communication conflict between the nodes is avoided, slot resources are fully used, and channel using rate is improved.

The invention relates to an underwater sensor network architecture and an implementation method thereof. The implementation method of the underwater sensor network architecture comprises the followingsteps: when a node has data to send, the data is first delivered to the transport layer through the application layer of the protocol stack; the protocol of the transport layer performs end to end reliability transmission processing on the data; then the data is delivered down to the network layer; the protocol of the network layer encapsulates a destination address to the data and gives appropriate routing information; then the data is continued to deliver down to the MAC layer; the protocol of the MAC layer encapsulates the next hop address to the data and gives a method to send the data tothe next node; and finally, the data is delivered to the physical layer, modulated by the physical layer and sent out in the form of a sound signal. The implementation method of the underwater sensornetwork architecture provides both a pure layered architecture and a cross layer design, and the cross layer design is crucial to the sensor network, because the performance of the system is affectedby each layer, and the cross layer design can make each layer cooperate with each other, therefore, the performance of the system is improved.