Wireless sensor networks

Wireless sensor networks

Times progress, technology innovation, and as information access to the most important and basic technology-sensor technology, has also been a great development. The technology of sensor information acquisition has evolved from the single of the past to the integration, miniaturization and networking, which will bring about an information revolution.

Wireless sensor Network (WSN) with perceptual, computational and communication capabilities, combined with sensor technology, embedded computing technology, distributed information processing and communication technology, can monitor, perceive and collect information of various environment or monitoring objects in the network distribution area in real time, and process the information, Get detailed and accurate information that is sent to users who need this information.

Due to the great application value of WSN, it has aroused wide attention of military departments, industry and academia in many countries in the world, and has been widely used in military, industrial process control, national security, environmental monitoring and other fields.

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WSN is a wireless network composed of a set of sensor nodes in a self-organized way, which is designed to collaboratively perceive, collect, and process the information of the perceptual objects in the geographic area covered by the network and publish them to the observer. WSN Wireless sensor network node mainly consists of data acquisition unit, data Processing unit, wireless data transceiver unit and small cell cell, usually small size, with low cost, low power consumption, multifunction and so on. It uses the built-in sensor in the node to effectively detect the temperature, humidity, light intensity, pressure and other environmental parameters in the area, as well as the voltage and current of the object to be measured, and transmits the detection information to the data aggregation center through the wireless network for processing, analysis and forwarding.

WSN has obvious advantages over conventional sensors and measurement and control systems. It uses point-to-point or point-to-multipoint wireless connection, greatly reduces the cost of cable, at the sensor node is the integration of analog signal/digital signal conversion, digital signal processing and network communication functions, the node has self-test function, system performance and reliability significantly improved and significantly reduced costs. Wireless sensor networks have the following characteristics:

Limited hardware resources. WSN nodes use embedded processors and memory, which is very limited in computing power and storage capacity. Therefore, it is necessary to collaborate on distributed information processing under the condition of limited computing power.

Limited power supply capacity. In order to measure real-world specific values, each node is densely distributed within the area under test and often does not facilitate the replenishment of energy. Each node is to reserve energy for long-term use, or to draw energy from the outside (solar). When the energy of the battery itself is exhausted, it is often discarded, even causing the interruption of the network. Therefore, any WSN technology and protocol should focus on energy-saving.

Peer In wireless sensor networks, the status of all nodes is equal, without a pre-specified center, and is a peer network. Each node is coordinated by a distributed algorithm, and in the case of unmanned intervention, the node can automatically organize a measurement network. And just because there is no center, the network will not be compromised by the detachment of individual nodes. Nodes can join or leave the network at any time, the failure of any node will not affect the operation of the entire network, has a strong anti-destruction.

Self-organizing. Network layout and deployment do not rely on any pre-set network facilities, the node through the hierarchical protocol and distributed algorithms to coordinate their behavior, the node can be quickly and automatically formed a separate network.

Multi-hop routing. The WSN node has limited communication capabilities and covers a range of only dozens of to hundreds of meters, and the node can only communicate directly with its neighbors. If you want to communicate with a node that is outside of its RF coverage, you need to route through an intermediary node. Multi-hop routing in WSN is done by a normal network node.

Dynamic topology. WSN is a dynamic network where nodes can move around, and a node may exit the network because of battery energy exhaustion or other failures, or it may be added to the network due to the need for work. These will make the topology of the network change at any time, so the network should have dynamic topological organization function.

Due to technical constraints, the large-scale business of WSN is still to be seen. However, with the reduction of microprocessor volume and the improvement of performance, there are many wsn in the beginning of commercial, its application mainly focus on the following aspects:

Military aspects

The goal of the C4ISRT system is to use advanced high-tech technology to design a command, control, communication, computation, intelligence, surveillance, reconnaissance and positioning in one battlefield command system for the future Modern warfare, which is widely regarded by the military developed countries, because the sensor network is a dense, low-cost, A randomly distributed node, self-organizing and fault-tolerant, makes the entire system crash without the damage of some nodes in a malicious attack, making the sensor network ideal for use in harsh battlefield environments. An intelligent sensor network, can be more detailed and accurate detection of accurate information, such as some special terrain area of the special information (Landing operations of the enemy beach detailed geographical characteristics of information, jungle ground hardness, dry humidity), to more accurately develop combat action plan to provide intelligence basis, it through the "digital roadmap" As a transmission tool, it provides "picking" intelligence service for each combat platform and unit, which makes the intelligence reconnaissance and acquisition ability produce qualitative leap.

Industrial aspects

Modern manufacturing facilities are increasingly complex and sophisticated. The corresponding wireless sensor network nodes can be installed from the production line to the complex machine equipment, so as to keep abreast of the work health of the equipment, early detection of the problem early treatment, thereby effectively reduce the loss and reduce the incidence of accidents. Wireless sensor network can be used to monitor the large-scale wind tunnel monitoring and control environment, to the rotating mechanism, gas source system, wind tunnel operation system, and other non-infrastructure and wired sensor system installation is not convenient or unsafe application environment for all-round detection.

Aspects of Life

Smart Home

The modern living pattern makes the family life more and more closed, the security problem appears particularly important. The current safety precaution and alarm system is one of the most important ways to ensure the safety of residential and household, and it is also an important part of digital family. When encountering police, fire, gas leaks and other emergency situations, it is necessary to complete the external alarm in time by telephone. With the wireless sensor network, these problems can be well solved.

Anti-Theft fire

For fire prevention facilities We are not unfamiliar, but we are familiar with most of the traditional fire equipment, traditional fire equipment or mainly rely on human operation, in real-time can not meet the requirements, and sensor network is precisely to compensate for this defect, in the event of The special sensor can quickly detect the smoke concentration and temperature parameters of the environment, when the threshold is reached, it will control the fire fighting facilities, and inform the personnel in the area to have sufficient time to evacuate the scene.

Vehicle positioning

There are many ways to locate the main method, in order to detect the ultrasonic intensity of the sensor as an example, the realization of a wireless sensor network, according to the sensor detected by the ultrasonic strength to decide to turn on or off the parking light, so as to determine whether a vehicle into the detection area. This sensor network combines embedded technology, sensor technology, short-range wireless communication technology, and has a wide range of applications. The system does not need to change the field structure, does not need any fixed network support, can be quickly arranged, easy to adjust, and has good maintainability and extensibility. It can also be applied to environmental monitoring, health care, logistics, robot control and so on. With the improvement of people's material living standard, people will be more and more comfortable in the life, such a large number of wireless sensors will become modern people's "eyes, ears, nose", so that we better avoid disadvantages, to ensure the safety of life and property. Continuously improve the production efficiency, quality of life, while constantly promoting the progress of the era of technological upgrading.

Wireless sensor networks