Reusing the same frequency in every cell eliminates the need for frequency planning in a CDMA system; however, planning of the different pseudo-random sequences must be done to ensure that the received signal from one cell does not correlate with the signal from a nearby cell. Data to be transmitted is multiplied with a high data rate bit sequence and then modulated onto an RF carrier to produce a signal with a much wider bandwidth than data alone.
A code called spreading code is used to perform this action.
In case of this, old link is to be broken when the new one is firmly established. The frequencies used in different cells must be planned carefully to ensure signals from different cells do not interfere with each other. But it is not that simple.
This means that we get a gain of this. CDMA has become successful in every aspect, and it has enabled improvements need to be gained over the previous technologies used in 2G systems. In other words, unlike synchronous CDMA, the signals of other users will appear as noise to the signal of interest and interfere slightly with the desired signal in proportion to number of users.
Individual conversations are encoded with the help of pseudo-random digital sequence. If dot product is zero, then the two vectors are said to be in orthogonal.
A receiver cannot demodulate this transmission without knowledge of the pseudo-random sequence used to encode the data.
The difference between GSM and CDMA can be considered in terms of technology they use, the security factors, and the data transfer speeds, and so on.