Wireless networks, commonly known as Wi-Fi, are increasingly popular for home networks. Several members of the household can share an Internet subscription, each using their own computer in different parts of the house without having to run cables all over the building. Everyone know that "wireless" does not use wires, but what does it use?
Data Packets
- In cabled networks, data travels around the network in a structure called a packet. The packet body contains a segment of data and network software puts headers on the front of the packet. The headers contain administration data. This includes the source and destination address for the packet, and also identifiers for the two applications communicating over the network. Wireless networks use exactly the same structure of a data packet. The only difference between wired and wireless networks is the network medium.
Radio Waves
- Wireless networks transmit data by radio waves. These are generated by a conductor on the wireless network card integrated into the computers and routers of the network. Radio waves are a magnetic disturbance that radiate out from an antenna attached to the conductor like the ripples in a pond hit with a stone. Like the ripples in disturbed water, the radio waves extend out in a circle becoming weaker with distance. The waves form a circle around the antenna, creating a signal footprint. A receiver within that footprint can pick up the signals if it tuned to the right frequency.
Frequency
- Frequency is an issue of timing. It is the number of radio waves per second. Imagine hearing a regular drum beat. That beat gets faster and faster, until it sounds like one continuous noise. It isn't, it is simply that the human ear is not tuned to a frequency beyond a certain point. The receiver has to operate at the same frequency as the transmitter so that it can detect the difference between a series of waves. Wi-Fi systems use frequencies of either 2.4 GigaHertz or 5 GigaHertz. Dual-band equipment uses both.
Modulation
- Wireless network adapters convert binary data (zeros and ones) into a square wave. The adapter generates a constant standard wave at the transmission frequency. This is called the carrier wave. The data wave is merged with the carrier wave in a process called modulation. The receiving antenna demodulates the wave by subtracting the carrier wave. The remaining wave is then converted back into binary data.
