air interface (mobile communications) (AI)
The air interface( AI), also known as the radio interface, is standardized and specifies the transmission-relevant parameters of a mobile communications system.
In principle, an air interface is comparable to an interface on the physical level, with the difference that the air interface ensures adaptation to the medium air and transmission by means of electromagnetic waves. The information is modulated onto a carrier frequency, which is radiated by antennas. In terms of reception, the carrier frequency is received by a receiving antenna and the information is demodulated from the carrier frequency.
The transmission-relevant parameters of the air interface are the frequency bands for the uplink and the downlink, the modulation method, the transmission method, the multiplexing method whether frequency division multiplex or time division multiplex, and the access to the frequency-discrete radio channels.