Wireless Networking Protocols
FREQUENCIES
Wireless networking replaces network cable with radio waves on specific frequencies. Just as a car radio has separate AM and FM bands on different frequencies, Wi-Fi uses two different frequency bands: 2.4GHz and 5GHz. Wi-Fi frequencies are among the many radio frequencies (RF) that are regulated by various organizations around the world. Different types of devices are assigned different RF bands to help avoid interference.
2.4GHz
The 2.4GHz frequency is the more common of the two frequencies used by Wi-Fi. It is supported by almost all of the Wi-Fi
standards discussed later in this chapter. It has a longer range than 5GHz. However, the 2.4GHz frequency also is used by some forms of Bluetooth wireless networking, older wireless phones, and other sources of radio frequency interference (RFI), which can distort wireless signals.
5GHz
The 5GHz frequency is it runs at a higher frequency, 5GHz networks transmit and receive data much more quickly than 2.4GHz networks. However, their range is much shorter.
CHANNELS
Wi-Fi’s two frequency bands are sliced into a number of channels to enable different wireless local area networks (WLANs) to coexist nearby.
2.4GHz channels supported worldwide are 1–11; only channels 1, 6, and 11 do not overlap with other channels. 5GHz channels supported in the US/Canada are 36, 40, 44, 48,149, 153, 157, and 161.
