Hand mechanism

At present, the hand mechanisms mainly include GSM, CDMA and 3G. Since the advent of mobile phones, they have gone through the first generation of analog-type mobile phones (1G), second-generation GSM, TDMA and Other digital mobile phones (2G) and 2.5th generation mobile communication technologies. CDMA and 3G mobile communication technology 3G.

Comparison of GSM, CDMA and 3G:

The GSM digital mobile communication system was designed by a standardization committee composed of major European telecommunication operators and manufacturers. It was developed based on the cellular system. Including GSM900MHz, GSM1800MHz and GSM1900MHz and other frequency bands. The GSM system has several important features: good anti-theft copying ability, large network capacity, abundant number resources, clear calls, strong stability, no interference, sensitive information, less dead calls, and low power consumption.

CDMA is Code Division Multiple Access (Code Division Multiple Access), a new and mature wireless communication technology developed on the branch of digital technology, spread spectrum communication technology. It can meet the high requirements of the market for mobile communication capacity and quality, and has the characteristics of high spectrum utilization, good voice quality, strong confidentiality, low call drop rate, small electromagnetic radiation, large capacity, and wide coverage, which can significantly reduce investment and Reduce operating costs.

3G is the third generation of mobile communication technology and is the general term for next-generation mobile communication systems. The 3G system is dedicated to providing users with better voice, text, and data services. Compared with the existing technology, the main advantage of 3G technology is that it can greatly increase system capacity, improve communication quality and data transmission rate. In addition, seamless roaming between different networks can be used to connect the wireless communication system to the Internet and provide more advanced services to mobile terminal users.

CDMA mobile phones Compared with GSM mobile phones, CDMA mobile phones have the following advantages: CDMA mobile phones use advanced switching technology: soft handover technology (that is, the handover is interrupted before continuing), making CDMA mobile phone calls comparable to fixed phones; In CDMA networks, the investment of operators is relatively reduced, which leaves room for the reduction of CDMA mobile phone tariffs; due to the adoption of a modulation and multiple access communication method based on top-frequency communication, its capacity is 10 times higher than that of analog technologies. Exceeds GSM network by about 4 times; CDMA based on broadband technology makes video application in mobile communication possible, thus make the mobile phone move towards broadband multimedia application from narrow service such as can only call and send short message.