Better system capacity (supporting high no. of users) is one of the advantages of CDMA mobile system.

The main advantage of WCDMA  is the much higher data rate than GSM. Therefore, one gets more data services including high speed internet communications.

This is attributed to the wideband communication channels for wcdma compared to narrow band communication channels for GSM.

The following link gives a comparison between the different mobile generations.

http://www.rfcafe.com/references/electrical/wireless-data-rates.htm

It is spread spectrum so data rate is high and the biggest advantage is user capacity which is depends upon pseudo code design.  

Thank you all

Basic math is roughly 10X capacity/throughput/number of simultaneous users for CDMA vs GSM (ie TDMA); hence all 4G systems leveraging off of CDMA as starting point; and hence Qualcomm's annoyingly high patent royalty rates....so lucrative that China is currently investigating as an illegal monopoly when of course (temporary) monopolies is basis of patent systems worldwide. 

Now, the next question is 'what is 5G going to be based on' if not CDMA....the Koreans claim they already have the answer, time will tell if they are correct or jumping the gun in the wrong direction as they did with mobile streaming...

CDMA mobiles are more advantageous to GSM mobiles because CDMA technology is comparatively immune to fading effects (fall back compatability), network is capable to handle more users in the same spectrum  & higher data rates.

The answer in short is the idea of sharing. In cdma all users share the same channel (the same frequencies) all the time giving rise to capacity gain over past systems.

In analog FDMA (Frequency Division Multiple Access) the available frequencies are divided among users, hence one call will have a solitary use of the whole channel for the whole duration of the call added to that the necessary guard bands (unused frequencies between channels for complete isolation between neighbouring channels). This is a big waste of the spectrum resource.

GSM, the second generation 2G mobile, came as digital system which allows the simultaneous use of any one channel (a band of frequencies) between a number of users by subdividing channel use in time. This is TDMA (Time Division Multiple Access), This meant practically that the channel is reused and the efficiency of using the spectrum is manyfolds increased. The use of digital technology enabled this while voice quality was even improved.This complex scheme is called TDMA/FDM , which means that the whole spectrum available to a mobile provider is divided into frequency channels (200KHz) and each one of them is used by N (typically 8) calls by division in time slots). Hence the channel in GSM is the continuous use of one time slot in one frequency band (frequency channel) Even with this rise in capacity, we still have wastes, we still need guard bands between channels (in frequency) and unused inter-slots to guard against ISI (inter-symbol Interference) between users occupying neighbouring time slots (of the same band/frequency channel).

In CDMA, all users use all of the frequencies all the time with no waste in guard bands in either the time or the frequency. This gives rise to the capacity increase of WCDMA (The wideband CDMA) over GSM. Users are separated using coding (cryptological codes) and unwanted users are suppressed at the receiver to noise floor levels leaving the target signal (the intended signal with the right code) to be detected and demodulated.

The  Capacity of GSM and analog 1 is a hard capacity; i.e. number of simultaneous calls are fixed for a given cluster of cells and channels allocated to these cells.  However, the capacity in CDMA depends on the interference level in the cell which is dictated by number of active users in the cell (and in neighbouring cells) and their activity levels  (voice calls have about 50% activity while data users can have lower activity percentage). This is called soft capacity in which no maximum is available and the real maximum is flexible (if you are going to sacrifice a little bit the quality of communication).

In fact, one more factor for extra more capacity gain of CDMA (and was one of the big incentives for WCDMA 3G) is the gain resulting from the users' silence periods (the activity factor). Silence periods are wasted in GSM (and of course in analog FDMA) because the channel is closed to its user (all frequencies in the band or the dedicated time slot). However, in CDMA, silence periods contribute to less interference to others (especially with the use of special controllers to completely stop emission whenever silence periods are detected at the transmitters) giving rise to capacity gains.

Hope this clarifies the main advantage of capacity compared to GSM. Other advantages include simpler receiver without the need for complex time equalizers and the robustness against fading in the frequency domain (of the wideband CDMA). Thanks. @AlDmour.

Reverse power control in CDMA will help to maintain desired BER across the cell. Number of handovers are less in CDMA due to large cell size and 64 users per carrier.

But generally GSM phones provide better services compared to CDMA.

Hello,

2G of mobile cellular networks are based on TDMA/FDMA or CDMA multiple access techniques. Both of them are approximately hte same for 2G. But CDMA or WCDMA is accepted for 3G and beyond.