GSM mostly uses frequency division multiple access in which each user has a separate carrier freq about 200kHz apart.... CDMA uses same frequency for all communication efficiently conserving bandwidth..... in CDMA the message is encoded using a psuedo random sequence which can be decoded only by the user for which it was encoded for and for users it would be useless....... CDMA is faster than GSM and more secure....
GSM used both TDMA and FDMA in 2G itself.... they r bringing even more in 3G.... how do you say CDMA is spread spectrum.... isnt CDMA coded FDMA??.... isn't spread spectrum supposed to vary its frequency and time slots....