Generally speaking, CDMA and gsm are two different signals used to provide wireless data services.
1.CDMA2000/CDMA and GSM are communication standards of communication operators, and multimode is a network that supports multiple standards at the same time. Among them, CDMA2000 is 3G of China Telecom, CDMA is 2G of China Unicom and GSM is 2G of China Mobile. In other words, this mobile phone supports both telecom 3G, Unicom 2G and mobile 2G.
2.CDMA 2000 (Code Division Multiple Access 2000) system is mainly proposed by Qualcomm North America Company, and its construction cost is relatively low. Its main supporters include Japan, South Korea and North America. Multi-carrier (ds) mode is adopted, and the carrier bandwidth is1.25mhz..
3.cdma2000*** is divided into two stages: the first stage will provide the data transmission rate of 144kbit/s per second, and when the data rate accelerates to 2mbit/s per second, it will be the second stage. By then, supporting wcdma-like mobile multimedia services will be the ultimate goal for cdma to develop 3g.
4.4. In principle, there is no essential difference between 4.4.cdma2000 and wcdma, both of which are derived from cdma(is-95) system technology. However, cdma2000 is fully compatible with cdma(is-95) system, which brings obvious benefits to the continuity of technology: the maturity and reliability are relatively guaranteed, and it also makes cdma2000 the smoothest choice for the transition from the second generation to the third generation mobile communication. However, compared with the direct spread spectrum mode of wcdma, the multi-load transmission mode of cdma2000 wastes a lot of frequency resources, and its frequency band also conflicts with the frequency band specified by imt-2000.