GCSE Link: 5.02 - Wired and Wireless Networks
A wireless network transfers information using radio waves or other wireless signals instead of physical cables.
Wi-Fi is one of the most common wireless network technologies, allowing computers to join wireless local area networks (WLANs).
A wireless access point is a component of a network which allows devices to connect to a local area network.
The wireless access point will broadcast the network's Service Set Identifier (SSID), its unique network name, so that devices know the network exists. When a device attempts to join the network, the wireless access point asks for a password (using the Wi-Fi Protected Access, or WPA, protocol), and only allows devices which have the correct password. Then, it encrypts all communication on the network, making sure that outsiders can't steal the data.
A wireless network adapter converts data into radio signals, allowing a computer to communicate with a wireless access point.
They are built into almost all modern computers, but can also be external devices which plug into a USB port.
Wi-Fi can operate in two different frequency bands: 2.4GHz (the older standard) and 5GHz (more
modern). The 2.4GHz band has slower transfer speeds than 5GHz, but has a longer range.
Most modern routers support both bands for backwards-compatibility.
Both bands are susceptible to interference, since a lot of consumer electronic devices output
radio signals at those frequencies. We can calculate the signal-to-noise ratio (SNR) using
the formula SNR (dB) = 10 × log10(signal / noise).
Calculate the SNR if the signal power is 100mW and the noise power is 1mW.
SNR = 10 × log10(100 / 1) = 10 × 2 = 20 dB