cdma is a wide thing to expain....but still i will try to give in a nutshell....
wat u do in cdma is u give a fixed id to ur user..say some code word of 32 bits . all the data that u want to transfer of the user want to transfer to him will be coded into this by usin spread spectrum....
CDMA stands for Code Division Multiple Access. It is one of multiple access in communications besides others such as FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access). Among others, CDMA is used in 3G communications.
CDMA stands for CODE DIVISION MULTIPLEXING.in its each use same freqenny and time divsion but each subscriber get differnt codes to transmit.it use PN CODES.