Why is CDMA needed?

CDMA optimizes the use of available bandwidth as it transmits over the entire frequency range and does not limit the user’s frequency range . It is used as the access method in many mobile phone standards.

CDMA in cellular systems offers attractive features such as the potential for high spectrum efficiency, soft capacity, soft handover and macro-diversity . This has been claimed and demonstrated in various system design studies, analyses and trials.

CDMA is a spread spectrum technique. Each data bit is spread by a code sequence . This means, energy per bit is also increased.

radio frame structure of WCDMA is shown in Figure 1 [15]. Frame structure has an overall length of 10 ms , comprising 15 time-slots. …

The Voice Activity Factor of 0.4 is considered = -4dB . CDMA has 100% frequency reuse. Use of same frequency in surrounding cells causes some additional interference.