In wireless communication, signals are transmitted through air without using any cable, wires or other electrical conductors. Wireless communication technologies include infrared (IR), mobile phone, radio frequency (RF), Wi-Fi, Bluetooth, Li-Fi, ZigBee, Z-Wave, laser, ultrasonic, etc. These find many applications in diverse fields. Home automation is one of them. Typically, a wireless home automation system comprises devices as shown in Figure.
Some wireless communication devices used in home automation are:
Infrared
Here, information is shared between devices or systems through IR radiation. In the electromagnetic spectrum, IR radiation lies between microwaves and visible light. It is used in many consumer electronics including security system, TV remote control and short-range communications.
Mobile phone
It can be used to turn on/off various electrical appliancesin homes. So, it works as a remote for home automation system. Most control signals from the mobile phone are sent either using Bluetooth or GSM (Global System for Mobile communication) mode in India. In GSM mode, it is possible to control home appliances from very far off as cellular networks have a wide range of coverage.
Wi-Fi
Appliances can be controlled using a personal computer through Wi-Fi. Most Wi-Fi devices use 2.4GHz frequency and implement frequency division multiplexing technology.
Bluetooth
Bluetooth devices are easily accessible for wireless control as these exist in many electronic products including mobile phones. Bluetooth provides a range of about 10 metres at the speed of 1Mbps.
Radio frequency
You can control home appliances using a pair of RF modules (transmitter and receiver). For example, most common RF devices used by hobbyists are 433MHz RF modules. ZigBee is a more powerful and longer-range RF device.
ZigBee
It is a low-power, wireless mesh network that operates in the following radio bands: 868MHz, 915MHz, and 2.4GHz.
Z-Wave
It is a relatively new wireless home automation protocol. It uses extremely less power and runs on a mesh network. The device communicates in a sub-gigahertz frequency range, around 900MHz.
Li-Fi
Light Fidelity or Li-Fi uses the visible region of the electromagnetic spectrum for communication. It can be easily used in places where Bluetooth, IR and Wi-Fi are banned, because it uses light instead of radio waves.
