CDMA

CDMA (Code Division Multiple Access) is translated as "Code Division Multiple Access Packet Data Transmission Technology" and is called the 2.5th generation mobile communication technology . The market currently using this technology is mainly in the United States, Japan, South Korea and so on. CDMA mobile phones are characterized by clear speech, low call drop, low transmission power, and strong confidentiality. The transmission power is only 1/60 of that of GSM mobile phones, and is called a "green mobile phone." More importantly, CDMA based on broadband technology makes video applications in mobile communications possible.

The principle of CDMA technology is based on spread spectrum technology, which is to be transmitted with certain signal bandwidth information data, modulated with a high-speed pseudo-random code with a bandwidth much larger than the signal bandwidth, so that the bandwidth of the original data signal is extended and then modulated by the carrier and Send it out. The receiving end uses the same pseudo-random code and correlates with the received bandwidth signal, and replaces the broadband signal with the narrowband signal of the original information data, namely despreading, to realize information communication.

The advantages of CDMA include:

The voice coding technology provided in CDMA can reduce the noise of the surrounding environment during the user's conversation and make the call more clear. CDMA uses spread-spectrum communication technology, which can reduce the interference between mobile phones and can increase the user's capacity. Moreover, the relatively low power of mobile phones can not only increase the use of time, but more importantly, it can reduce electromagnetic radiation and reduce harm to people to a certain extent. The bandwidth of CDMA can be greatly expanded and images can also be transmitted. In terms of security performance, CDMA has a good authentication system, but because of its transmission characteristics, it greatly enhances the ability to prevent people from being intercepted.