1.What is the Internet of Things

internet of Things (internet of Things, referred to as IOT), the Internet of things simply refers to a variety of physical devices, intelligent terminals, sensors, etc., connected through the network, the LAN can also communicate with each other between the wider area wide area network, to achieve information exchange and communication technology, to achieve information sharing and intelligent management.

1.1.What is the use of iot

Internet of Things for home, campus, and even enterprises, its application field is very wide, including industrial automation, smart city, agricultural Internet of things, medical health and other fields, the use of the Internet of things can bring a lot of convenience and benefits for our life and work.

2.The three-layer structure of the Internet of Things

感知层(Perceptual layer)

The bottom layer, located in the first of the three layers of the iot structure, is responsible for identifying external objects, collecting information, and passing information to other layers of the iot system

1. Data collection: temperature, humidity, light, sound, position, human body, noise, pressure.
2. Equipment control: Through the content data transmitted by the sensor, the interactive actions of each actuator can be controlled according to the upper control instructions, so as to achieve intelligence and automation.
3. For us humans, it is the use of our five senses and skin to perceive the external world through sight, taste, smell, hearing and touch. The perception layer is the facial features and skin of the Internet of Things, which are used to identify external objects and collect information. It can collect external data through sensors, and then transmit data through short-range transmission technologies such as RFID, bar codes, buses, Bluetooth, and infrared.

网络层(Network layer)

The transport layer, also known as the network layer, is located at the second layer of the three-layer structure, and its function is to securely transmit data from the upper and lower layers through the communication network

1. The transmission layer of the Internet of Things is mainly responsible for transmitting and processing the information obtained by the perception layer, which is divided into two categories: wired transmission and wireless transmission.
2. The network layer, as a link connecting the perception layer and the application layer, is composed of various private networks, the Internet, wired and wireless communication networks, etc., equivalent to the human nervous system, responsible for transmitting the information obtained by the perception layer to the application layer safely and reliably, and then processing the information according to different application requirements.

中心网关(Central gateway)

The central gateway is located in the middle of the three-layer structure and the two-layer structure of the Internet of Things, and its function uses the analyzed and processed perceptual data to provide users with a wealth of specific services Under normal circumstances, each device is unable to directly communicate with other devices point-to-point, then a device is needed for transit, this device is (central gateway). The central gateway provides secure and reliable connectivity and communication capabilities, connects massive devices downward, and supports device data collection to the cloud. The cloud API is provided upward, and commands are sent to the device by invoking the cloud API to achieve remote control and remote interaction.

应用层（Application layer）

Located in the top layer of the three-layer structure, similar to the human brain, the instruction is sent to the nerve, transmitted to the perception layer of the Internet of Things, and the interactive use of the device to achieve intelligence

1. The main function is to use the data collected from the underlying perception layer and the network layer to realize various applications and services. Based on these data for analysis, decision-making and control, so as to achieve a variety of intelligent, automated functions.
2. The application layer and the perception layer are closely related, one is to obtain data, the other is to use data, and there is a causal relationship between them. On the one hand, the application layer can calculate and process the data collected by the perception layer.