19 results about "Wireless sensor network" patented technology

A method is provided for performing a clear channel assessment in a wireless network. The method involves first listening for channel energy on a wireless channel. Whatever channel energy is heard over the wireless channel is demodulated into non-synchronized in-phase and non-synchronized quadrature phase components. Each of the non-synchronized in-phase and non-synchronized quadrature phase components are squared, and then the non-synchronized in-phase component is multiplied by the non-synchronized quadrature phase component to produce an I−Q product. The sum of the squared non-synchronized in-phase component, the inverse of the squared non-synchronized quadrature component, and double the I−Q product is determined as a clear channel assessment input value. A carrier signal detection function is then performed on the clear channel assessment input value to produce a clear channel assessment output value, which is used to determine whether a signal is present in the wireless channel.

Provided a method and device for efficiently retransmitting packets of which transmissions failed in wired/wireless network including detecting continuity by detecting whether or not a sequence ID of a received packet is continuous with a start sequence ID or an end sequence ID of packets included in reception blocks which are generated in advance of the received packet; depending on the result of the detection, manipulating reception blocks to renew or delete the reception blocks or generate a new reception block by using the sequence ID of the received packet; and transmitting an EBN (Explicit Block NACK) for requesting retransmission of lost packets in units of a block when discontinuity is detected.

The invention relates to an AOA-based two-dimensional wireless sensor network semi-definite programming positioning method comprising the following steps: assuming that there is no obstruction between a reference node and a target node to be positioned in a wireless sensor network, and measuring the angle of arrival of each signal; converting the angles of arrival of the signals into distance information between the nodes; converting a problem of wireless sensor network target node positioning into a mathematical optimization problem of maximum likelihood estimate MLE and solving the problem, and providing an optimized objective function for subsequent steps; introducing redundant variables to convert the mathematical optimization problem of maximum likelihood estimate MLE into a constrained optimization problem; converting the obtained constrained optimization problem into a semi-definite programming SDP convex optimization problem using a mini-max criterion and a semi-definite relaxation SDR method, and getting an optimal solution, thus completing positioning of the target node. Through the method, the precision of target node positioning is improved.

A method provides differentiated quality of service (QoS) by providing adaptive updates to media access control (MAC) layer parameters on a distributed basis. The method includes calculating a failure probability for a transmission over the network, determining a target value for determining a contention window according to a mapped function of the failure probability, and altering the contention window according to a scaling function of the target value. The mapped function and the scaling can provide QoS differentiation. A wireless device ensures fairness in a wireless time slotted network and includes a network interface card (NIC), a network driver interface, a network monitor, a statistics engine, and an adaptive parameter engine for determining a target value for determining a contention window according to a mapped function of the one or more probabilities to enable an alteration of the contention window and provide new parameters for the MAC layer.

The invention discloses a grid based wireless sensor network fuzzy-locating method in the technical field of wireless sensor network application. The grid based wireless sensor network fuzzy-locating method includes: transmitting information to a node to be located by anchor nodes, receiving information and build an neighbor anchor node chain table through the node to be located; dividing an area where the sensor network is located into grids in assigned number; computing membership degree of the node to be located to each grid and arranging the node to be located in descending order according to the membership degree; computing average values of sequence numbers of all the grids comprising auxiliary locating points by setting peaks of the grids as the auxiliary locating points to form a sequence (QY); selecting a former first assigning item from the (QY) and setting the centroid of the auxiliary locating point of the corresponding grid as roughly evaluated coordinates of the node to be located; clustering the auxiliary locating points corresponding to the former second assigning item in the (QY) by setting the roughly evaluated coordinates as the initial clustering center and obtaining the coordinates of the node to be located. The grid based wireless sensor network fuzzy-locating method is capable of computing accurate evaluated coordinates of the node to be located, complete and excellent in locating performance.

The invention discloses a sensor network positioning method based on hop counts. In a wireless sensor network, communication distances of all nodes are the same, one node only receives information of other nodes within limited hop counts, and a non-linear equation set is constructed by utilizing the ratio of the hop counts from different anchor nodes to unknown nodes, so that the unknown nodes are positioned. By means of distributed calculating and processing, node information exchange times are decreased, information conflict and network node power consumption are reduced, positioning precision of the unknown nodes is improved, and the method has a certain application value and is capable of meeting the requirement on high-precision distributed positioning of the wireless sensor network.

A method for aggregating data in a network, particularly in a wireless sensor network, wherein the network (1) includes a plurality of sensor nodes (N_i) to measure data and at least one sink node (S) at which the data measured by the sensor nodes (N_i) are aggregated, and wherein each sensor node (N_i) encrypts its measured data with a key k and forwards the result towards the sink node (S), is characterized in that, in the context of a key distribution within the network (1), a master key K is chosen, and that the master key K is autonomously split up by the network (1) into individual keys k_i to be used by the sensor nodes (N_i) for encrypting measured data, with the sum of all individual keys k_i being equal to the master key K.

The invention discloses a rectifier circuit for piezoelectric energy collectors to solve the problem that the energy consumption of an existing circuit is high and the efficiency of a piezoelectric energy collector is low when the rectifier voltage of the piezoelectric energy collector is greater than 2.5 V. The rectifier circuit comprises a full-wave rectifier bridge (2) and an active diode circuit (4), and further comprises a bias circuit (3). The output end of the full-wave rectifier bridge (2) is connected with the input ends of the active diode circuit (4) and the bias circuit (3). The output end of the bias circuit (3) is connected with the bias voltage end of a comparator in the active diode circuit (4). The output end of the active diode circuit (4) is connected with an energy storage capacitor C3. The rectifier circuit for piezoelectric energy collectors has the advantages of being low in power consumption, high in energy conversion efficiency, and capable of ensuring the energy demand of wireless sensor network node load.

The invention relates to a three-dimensional positioning method, device and system based on a wireless sensor network and a computer readable storage medium. The method comprises the following steps of respectively computing a reference hop distance of each anchor node in the wireless sensor network; computing an average value of the reference hop distances of the anchor nodes in the wireless sensor network, and acquiring a correction hop distance of each anchor node according to the average value; and acquiring minimum hop count of an unknown node and the anchor nodes in the wireless sensor network, and determining positioning coordinates of the unknown node according to the correction hop distance and the minimum hop count. According to the three-dimensional positioning method based on the wireless sensor network, the average value of the reference hop distances of the anchor nodes is computed, the correction hop distance of each anchor node is acquired, and the positioning coordinates of the unknown node are determined, so that an accidental error between different anchor nodes can be effectively eliminated, and the accuracy of positioning the unknown node in the three-dimensional positioning is improved.

The invention discloses a wireless sensor network node positioning method based on a quantum tiger shark mechanism. The method comprises the following steps: establishing a distance estimation model based on hop distance correction; establishing a node positioning model based on hop distance correction; initializing unknown nodes to be positioned as 1, and positioning the unknown nodes to be positioned one by one; initializing a quantum tiger shark group and setting parameters; defining and calculating the distance between the quantum tiger shark and the prey, and determining the optimal quantum position of the quantum tiger shark group, wherein the quantum tiger sharks execute a prey tracking mode and a swimming mode respectively, and the quantum positions of the quantum tiger sharks are evolved by using a simulated quantum revolving door in the execution process; updating the quantum position of the quantum tiger shark and the optimal quantum position of the quantum tiger shark group; judging evolution termination, and realizing positioning; and performing positioning termination judgment, and outputting positioning results of all unknown nodes. According to the method, the estimated distance from the unknown node to the anchor nodes of the whole network is closer to the real distance, better robustness is achieved, and unknown node positioning in the wireless sensor network is achieved.

The invention provides a movable wireless charging system based on automatic cruise of an unmanned aerial vehicle. The system employs the unmanned aerial vehicle with an autonomous path planning function as a moving means of wireless charging equipment, and charges a built-in battery in an application occasion where a wireless sensor network is arranged in a large scale. The system comprises an unmanned aerial vehicle control module, an airborne positioning module, an airborne wireless charging device, an unmanned aerial vehicle start-stop wireless charging platform, a communication module, aplatform built-in control center and a cloud server. By applying the technical scheme, autonomous path planning can be realized, and the wireless charging equipment is carried to be positioned to a specified position to charge the built-in battery of a wireless sensor network node.

The invention discloses an energy consumption management method for sensor nodes in a wireless sensing network. At sensor nodes the method comprises the following steps: starting a CPU to enter into a normal operation mode at a preset time and starting sensor transition; controlling the CPU to enter into a low-power mode; after the completion of the sensor transition, controlling the CPU to enter into the normal operation mode and reading information data acquired by the sensor; starting power supply of a wireless emission unit to send an uplink data; shutting down the power supply of the wireless emission unit and controlling the CPU to enter into a sleep mode. According to the invention, the sensor nodes are arranged into the sleep mode when the nodes do not need operation, in the process of starting the sensor transition, the CPU of the sensor nodes enters into the low-power mode, power supply consumption of the sensor nodes power supply is effectively reduced, and power supply life of the sensor nodes is effectively raised finally. In the invention, adding an extra power supply or using a mass power supply is not needed, so the method in the invention is not restricted to application scenes.

A method of transmitting data over a wireless network to a plurality of receivers connected to the network, the method comprising applying a superimposed encoded multicast or broadcast so as to generate a multi-resolution multicast or broadcast signal to transmit data to the plurality of receivers in the form of an extensible multicast or broadcast. The method comprises the following steps: dividing data into one or more quality layers; converting the data in each quality layer into an independent protected layer data stream through an application protection or robustness method; using a modulation means to modulate each of the protected layer data streams, the modulation means for each of the protected layer data streams not necessarily being the same; superposing the modulation data of all layers into a single or multicast transmission block; and sending the single broadcast or multicast transmission block to a plurality of receivers connected with the wireless network, so that a non-uniform channel state is efficiently solved, and various wrong robust data between the receivers is effectively recovered.