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Xiaoxin has already told you that wireless sensor networks are widely used. The sensor node uses its built-in various sensors to measure the heat, infrared, sonar, radar, and seismic wave signals in the surrounding environment, including temperature, humidity, noise, light intensity, pressure, soil composition, size of moving objects, Many physical phenomena of interest such as speed and direction. The sensor nodes have good cooperation capabilities, and complete global tasks through local data exchange.
Due to the requirements of the node characteristics of the IoT sensor network , multi-hop, peer-to-peer communication methods are more suitable for wireless sensor networks than traditional single-hop, master-slave communication methods, and can also effectively avoid the long-distance wireless signal propagation process. Problems such as signal fading and interference encountered. Through the gateway, the sensor network can also be connected to the existing network infrastructure, so that the collected information can be passed back to remote end users for use. Wireless sensor networks also have the following characteristics:
4. Network dynamics:
The topology of a sensor network may change due to the following factors:
① The sensor node fails or fails due to environmental factors or power exhaustion;
② Changes in environmental conditions may cause changes in the bandwidth of wireless communication links, and may even be intermittent;
③ The three elements of the sensor network, such as sensors, sensing objects, and observers, may have mobility;
④ The addition of new nodes. This requires the sensor network system to be able to adapt to this change and have dynamic system reconfigurability.
5. Network reliability:
Sensor networks are particularly suitable for deployment in harsh environments or areas that are not reachable by humans. Sensor nodes may work in open air environments, be exposed to the sun or wind and rain, and even be damaged by unrelated personnel or animals. Sensor nodes are often deployed randomly, such as by broadcasting or launching "guns" to designated areas for deployment.
These all require that the sensor node is very sturdy, not easily damaged, and adapted to various harsh environmental conditions. Due to the limitation of the monitoring area environment and the huge number of sensor nodes, it is impossible to "care" each sensor node manually, and the network maintenance is very difficult or even impossible to maintain. The confidentiality and security of communication in sensor networks are also very important. It is necessary to prevent monitoring data from being stolen and obtain false monitoring information. Therefore, the software and hardware of the sensor network must be robust and fault-tolerant.
6. Focus on data:
Sensor networks are mission-oriented networks, and talking about sensor nodes outside the sensor network makes no sense. Nodes in a sensor network are marked with a node number. Whether the node number is required for the entire network depends on the design of the network communication protocol. Due to the random deployment of sensor orders, the relationship between the formed sensor network and the node number is completely dynamic, as shown by the fact that the node number and the node position are not necessarily related. When users use the sensor network to query events, they directly notify the network of the events of interest, rather than to a certain number of nodes. The network reports the information to the user after obtaining the information of the specified event.
This idea of using data as a query or transmission clue is closer to the habit of natural language communication. So it is usually said that a sensor network is a data-centric network. For example, in a sensor network applied to target tracking, the tracking target may appear anywhere, and users interested in the target only care about the location and time of the target, and do not care which node detects the target. In fact, in the process of target movement, different nodes must provide the location information of the target.
7. Application-Related Networks
The sensor network is used to sense the objective physical world and obtain the amount of information in the physical world. The physical quantity of the objective world is diverse and inexhaustible. Different sensor network applications care about different physical quantities, so there are various requirements for sensor application systems. Different application backgrounds have different requirements for sensor networks, and their hardware platforms, software systems, and network protocols must be very different. Therefore, the sensor network cannot have a unified communication protocol platform like the Internet.
Although there are some common problems for different sensor network applications, in developing sensor network applications, more attention is paid to the differences in sensor networks. Only by bringing the system closer to the application can the most effective target system be made. Researching sensor network technology for each specific application is a significant feature of sensor network design that is different from traditional networks.
Wireless sensor networks can be used in fine agriculture to monitor pests in crops, soil pH and fertilization. You can also track the migration of migratory birds and insects, study the impact of environmental changes on crops, and monitor the composition of the ocean, atmosphere, and soil.
July 8, 2016
Chengdu Xinxin Electronic Technology Co., Ltd. Editorial Department
Editor: Little Devil in Gourd