The physical layers describes how data must be transformed in order for them to be transmitted as individual bits over the physical medium. In this process the following steps are performed in a wireless LAN device:
- Modulation of digital data into analog carrier signals
- Modulation of the carrier signal into a radio signal in the selected frequency band, which for a wireless LAN is either 2.4 or 5 GHz.
The second modulation step in IEEE 802.11n occurs in the same way as in conventional wireless LAN standards and is therefore not covered here. However, there are a number of changes in the way digital data are modulated into analog signals in 802.11n.