Internet Of Things
The Internet of Things (IoT) describes a network of smart devices that are connected to the internet. IoT can be applied in home and office automation, agriculture, manufacturing, transportation and smart cities. Designing an IoT network includes selecting devices, choosing a protocol for exchanging information and selecting a network technology for physical transport of data.
| Sensor | Plug | Actuator |
|---|---|---|
 |  |  |
Devices
Devices are the objects at the edge of the IoT network. The may perform some basic calculations or cache data. Examples are sensors to collect data, automatic switches to turn on lights and devices or actuators that open and close windows.
| Device | Usage | Example |
|---|---|---|
| Sensors | Conversion of a physical parameter such as temperature, pressure or accelleration into an analog or digital value. | DHT11, BMP280 |
| Microcontrollers | Reading, converting, caching and transferring sensor data and controlling devices. | ESP32, Arduino |
| Gateways | Central device for connecting wireless sensors to the internet | Zwave gateway |
| Actuators | Generation of motion, sound or light. | LED, Alarm, Servo, Motor |
Protocol
The protocol is the language for communicating between devices. Data can be transferred by pulling data, pushing data or subscribing to channels where data is broadcasted.
| Protocol | Usage | Example |
|---|---|---|
| SSH | Executing remote commands on a computer platform | Read CPU load, excute commands. |
| HTTP | Create, read, update and delete objects via a REST web service | Read sensor values from a platform with connected devices. |
| MQTT | Exchange information via publish and subscribe. | Sensor broadcasting temperature. |
| WebSockets | Publish and subscribe for exchaning data between web browsers and servers. | Chat apps, dashboards. |
Network
The network is the physical layer for transporting information. This can be over wired connection or via radio signals. Selecting the most appropriate networking technology depends on the density and frequency of data exchange and available power.
| Transport | Usage | Example |
|---|---|---|
| Lan | Wired local network | Building or office network. |
| Wifi | Transfer of high volume data for sensors with power supply up to 50 meter. | Web cam, Power switch. |
| Bluetooth | Transfer data from devices with batteries up to 50 meter | Heartbeat monitor, Home appliance. |
| Zwave | Wireless mesh of connected sensors for longer distance data transfer | Power switches, presence detection. |
| Lora | Long range low power and low energy data transfer up to 30 km | Humidity sensors in agriculture. |
| 3G/4G/5G | High density data exchange using paid subscription | Smartphones, vehicle tracking. |