CDMA mobile phone and GPRS mobile phone

It's impossible ~ the network is simply different ~ it's not temporary ~

GSM digital network: GSM (Global System for Mobile Communications) network is a global mobile communication system, also known as "GSM", and many companies participated in the formulation of standards. GSM digital mobile communication system is designed by standardization committee composed of major European telecom operators and manufacturers, and it is developed on the basis of cellular system. Since the end of 1994, China has established GSM cellular mobile communication networks in more than ten provinces and cities, and the development momentum has impressed the whole world. Up to now, GSM digital network has covered more than 30 provinces (autonomous regions and municipalities), more than 300 regions and more than 2,000 counties and cities, and can roam with more than 40 countries.

GSM adopts digital modulation technology, and one of its key technologies is time division multiple access (each user selects a carrier frequency in a certain time slot and can only receive information at a specific time). GSM system has several important features: good anti-theft and copying ability, large network capacity, rich number resources, clear call, strong stability, sensitive information, few dead calls and low power consumption of mobile phones. Therefore, its voice is clear and easy to keep secret, and it can provide many data transmission services. The number of users supported by GSM network is 1.8-2 times that of analog network.

Because of the rapid development of GSM, after its 900MHZ band was full, it opened up the GSMl800 band, and the mobile phone worked at 900MHZ and 1.8 GHz band, and GSM 1900MHz band.

GPRS:GPRS is the English abbreviation of General Packet Radio Service, and Chinese is General Packet Radio Service. It is a wireless packet switching technology based on GSM system, which provides end-to-end and wide-area wireless IP connection. Compared with the original GSM dial-up circuit-switched data transmission mode, GPRS is a packet switching technology, which has the advantages of "real-time online", "quantity charging", "fast login", "high-speed transmission" and "free switching". Generally speaking, GPRS is a high-speed data processing technology, and the method is to transmit data to users in the form of "packets". Although GPRS is a transitional technology from the existing GSM network to the third generation mobile communication, it has obvious advantages in many aspects.

Because of the use of "grouping" technology, users surf the Internet relatively stably, avoiding unnecessary short-term troubles. In addition, the method of accessing the Internet using GPRS is different from WAP. Using WAP to surf the Internet is like surfing the Internet at home. After surfing the Internet, you can't use the telephone line at the same time, but GPRS is superior. You can download data and talk at the same time. Technically speaking, voice transmission (that is, call) continues to use GSM, while data transmission can use GPRS. In this way, the application of mobile phones will be promoted to a higher level. Moreover, the development of GPRS technology is also very "economical", because it can only be developed according to the existing GSM network. GPRS is widely used, including sending and receiving e-mails through mobile phones and surfing the Internet.

TDMA:TDMA is the abbreviation of Time Division Multiple Access, which is a technology to provide wireless digital services by time division multiple access, and it represents a digital signal transmission technology of mobile phone system. TDMA divides a radio frequency into multiple time slots, and then assigns these time slots to multiple groups of calls. In this way, a radio frequency can support multiple data channels at the same time. At present, this technology has become the basis of today's D-AMPS and GSM systems.

Compared with analog mobile phone voice, GSM digital machine

The voice of GSM digital mobile phone can only be transmitted on the wireless channel after being digitized. It is not as easy to be disturbed as an analog mobile phone, so the voice is clear and the interference is small. However, due to the transmission of digital voice, there are also shortcomings of voice distortion. The speech distortion of analog mobile phone is better than that of GSM digital mobile phone. Now, the relevant departments are studying and developing more advanced speech digital coding technology to reduce the speech distortion of GSM mobile phones.

CDMA digital network: CDMA is the abbreviation of code division multiple access, which is a brand-new and mature wireless communication technology developed on the spread spectrum communication technology, a branch of digital technology. It can meet the market's high demand for mobile communication capacity and quality, and has the characteristics of high spectrum utilization, good voice quality, strong confidentiality, low dropped call rate, small electromagnetic radiation, large capacity, wide coverage and so on, which can greatly reduce investment and operating costs.

Operators in this industry are trying to increase the number of users in their systems, reduce the cost of each user, create greater profits and actively strengthen market penetration. Code division multiple access technology is one of the digital communication technologies to solve this problem.

Its advantages are:

Effective band utilization and greater network capacity.

Simplify network planning

Improve the call quality

Enhance confidentiality

Improve coverage characteristics

Extend the user's talk time

Soft volume and "soft" switching

It's faster to surf the internet.

At present, China's "China Great Wall Mobile Communication Network" with CDMA technology has been opened in Beijing, Shanghai, Guangzhou and Xi 'an.

CDMA is the latest development of digital network technology, and the United States is the birthplace and the most widely used. CDMA mobile phone has clear voice, close to wired phone, good signal coverage and is not easy to drop.

Compared with GSM mobile phone, CDMA mobile phone has the following advantages: CDMA mobile phone adopts advanced switching technology: soft switch technology (that is, switching is to connect first and then interrupt), which makes CDMA mobile phone call comparable to fixed phone; Using CDMA network, the investment of operators is relatively reduced, which reserves space for the downward adjustment of CDMA mobile phone charges; Because of the modulation multiple access communication mode based on spread spectrum communication, its capacity is 10 times higher than that of analog technology and about 4 times higher than that of GSM network. CDMA based on broadband technology makes the application of video in mobile communication possible, and makes mobile phones move from narrow services such as calling and texting to broadband multimedia applications.

GSM/KOOC-0/X: The so-called GSM/KOOC-0/X refers to dual-mode mobile phones that support two standard networks, mainly GSM/PHS and GSM/CDMA, which greatly improve the Internet access speed compared with GSM/GPRS, among which the GSM/PHS mobile phone is only Sanyo's PDG-G/KOOC-0/000 (that is, J/KOOC-0 sold by Taiwan Province Public Telecom).