Legacies
1G -> AMPS
Had only voice services.
2G -> GSM/CDMA
Had both voice and data services
GSM -> used Time Division multiplexing
CDMA -> used Code Division multiplexing
3G -> WCDMA/TDSCDMA/EVOD
Higher data rates
4G -> LTE
5G -> NR
Radio Resource Protocol(RRC) is used to configure and control the radio resource between UE and eNB
Signaling Radio Bearers(SRBs) are used for the transmission of RRC and NAS Message between eNodeB and UEs