CDMA

Same frequency is used by every user and simultaneous transmission occurs

Every narrowband signal is multiplied by wideband spreading signal, usually known as codeword

Every user has a separate pseudo-codeword, i.e., orthogonal to others

Only the desired codeword is detected by the receivers and others appear as noise

It is mandatory for the receivers to know about the transmitter’s codeword

FDMA

When the channel is not in use, it sits simply idle

Bandwidth of Channel is relatively narrow (30 KHz), known as narrowband system

Little or no equalization is needed for spreading symbol time

Analog links are suitable for FDMA

Framing or synchronization bits are not needed for continuous transmission

Tight filtering is needed to minimize interference

Combined with FDD for duplexing