3G technical standard
In May 2000, the International Telecommunication Union (ITU) determined three mainstream wireless interface standards: W-CDMA, CDMA2000 and TDS—CDMA, and wrote them into the 3G technical guidance document "International Mobile Communication Plan 2000" (IMT—2000 for short).
W—CDMA
That is wideband code division multiple access, also known as CDMADirectSpread, which means wideband code division multiple access. Its supporters are mainly European manufacturers with GSM system, and Japanese companies are also involved to some extent, including Ericsson, Alcatel, * * *, Lucent and Nortel in Europe and America, as well as NTT, Fujitsu and Sharp in Japan. This system can be built on the existing GSM network, which can be easily transitioned by system providers. In Asia, where GSM system is quite popular, the acceptance of this new technology is expected to be quite high. Therefore, W-CDMA has inherent market advantages.
CDMA2000
CDMA2000, also known as CDMAMulti—Carrier, was proposed by Qualcomm North America Company, and Motorola, Lucent and later Korea participated in it. Now Korea is the leader of this standard. The system originated from the narrow-band CDMAOne digital standard, and can be directly upgraded from the original CDMAOne structure to 3G, with low construction cost. But at present, CDMA is only used in Japan, South Korea and North America, so there are not as many supporters of CDMA2000 as W-CDMA. However, the research and development technology of CDMA2000 is the fastest among the current standards, and many 3G mobile phones have already taken the lead.
TD—SCDMA
This standard is a 3G standard independently formulated by Chinese mainland. On June 29th, 1999, China Institute of Telecommunications Science and Technology (Datang Telecom) proposed to ITU. The standard integrates international leading technologies such as smart wireless, synchronous CDMA and software radio, and has unique advantages in spectrum utilization, business support flexibility, frequency flexibility and cost. In addition, due to the huge market in China, the standard has attracted the attention of major telecom equipment manufacturers, and more than half of the equipment manufacturers in the world have announced that they can support the TD-SCDMA standard.
What is 2.5G?
At present, the 2.5G mobile communication technology that has been put into commercial use is a fusion technology from 2G to 3G. Because 3G is a huge project, involving many and complicated layers, it is impossible to connect from the current 2G to 3G at once, so there is a 2.5G between 2G and 3G. Technologies such as HSCSD, WAP, EDGE, Bluetooth and EPOC are all 2.5G technologies.
HSCSD (high speed circuit switched data service)
This is an upgraded version of GSM network. HSCSD (High Speed Circuit Switched Data) can be transmitted at the same time through multiple time-divisions, not just a single time-division, so it can greatly increase the transmission speed by two to three times. At present, both M 1 in Singapore and Singapore Telecom use HSCSD system, and the transmission speed can reach 57.6kbps.
Wireless application communication protocol
WAP (WirelessApplication Protocol) is the first stage product of the combination of mobile communication and Internet. This technology allows users to surf the Internet using wireless devices such as mobile phones and navigate between websites through small screens. These websites must also be written in WML (Wireless Markup Language), which is equivalent to HTML (Hypertext Markup Language) on the Internet.
Bluetooth (Bluetooth)
Bluetooth is a short-range wireless communication technology. Electronic devices can be connected to each other through Bluetooth, and traditional wires are useless here. Through the wireless receiver on the chip, electronic products equipped with Bluetooth technology can communicate with each other within ten meters, and the transmission speed can reach 1 megabyte per second. In the past, the transmission technology in infrared data association required the distance of electronic equipment in sight. Now, with Bluetooth technology, such troubles can be eliminated.
When will 3G come?
Japanese mobile communication giant NTTDoCoMo has launched the world's first 3G service on June 10, which is based on WCDMA standard.
At present, Asia has become the fastest growing region of 3G, followed by Europe, and the United States is far behind in technical preparation due to lack of enthusiasm. In addition to Japan and South Korea, Thailand and Hong Kong also issued 3G licenses. Taiwan Province Province will soon issue 3G licenses, and the mainland is expected to issue 3G licenses before the end of the year. It is expected that the market will issue two or three cards.
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Now "3G communication" is about to become the mantra in people's mouths, so do you know what 3G communication is? The so-called 3G, in fact, is the third generation, which means the third generation digital communication in Chinese. 1995, the first generation of digital mobile phones, can only make voice calls; The second generation digital mobile phones from 1996 to 1997 have added the function of receiving data, such as accepting emails or web pages; The main difference between the third generation and the first two generations is that the speed of transmitting sound and data has increased. It can handle various media forms, such as images, music and video streams, and provide various information services, including web browsing, teleconference and e-commerce. Compared with the first generation analog mobile phones (1G) and the second generation GSM, TDMA and other digital mobile phones (2G).
There are many names for 3G communication. ITU defines it as "IMT-2000" (International Mobile Phone 2000), and European telecom giants call it "UMTS" universal mobile telecommunications system. According to the standard, when the mobile terminal moves at the speed of the vehicle, its data transmission rate is 144kbps, when it is stationary or walking outdoors, it is 384kbps, and it is 2Mbps indoors. However, these requirements do not mean that the available rate of users can reach 2Mbps, because the indoor rate will also depend on the detailed frequency planning in the building and the close cooperation between organizations and operators.
The International Telecommunication Union (ITU) has determined three mainstream wireless interface standards for 3G communication, namely W-CDMA (Wideband Code Division Multiple Access), CDMA2000 (Multicarrier Wavelength Division Multiplexing Spread Spectrum Modulation) and TDS-CDMA (time division-synchronous code division multiple access). Among them, the W-CDMA standard mainly originated from the early third-generation wireless research activities in Europe and Japan. The system is used in the existing GSM network and can be easily converted by system providers. The standard mainly supports Cui Tingfu's studio. Please post it when you are free. There are European, Japanese and Korean ones. At the end of last year, at&; T Mobile Services Branch also announced that it has chosen WCDMA as its third generation service platform. CDMA2000 system is mainly proposed by Qualcomm North America Company. Its construction cost is relatively low, which mainly supports Cui Tingfu's studio. Please post it when you are free. Participants include Japan, South Korea and North America. TD-SCDMA standard was first put forward by China, and cooperated with the international community on the basis of RTT. TD-SCDMA standard is completed and becomes a member of CDMA TDD standard. This is a pioneering work in the field of mobile communication in China, and also China's contribution to the development of the third generation mobile communication. In the competition with the 3G standards proposed by Europe and America respectively, TD-SCDMA proposed by China has officially become one of the global 3G standards, which indicates that China has entered a leading position in the field of mobile communication.
3G mobile phone is the product of the integration of communication industry and computer industry. Compared with the previous mobile phone, the difference is too great, so more and more people begin to call this new mobile communication product "personal communication terminal". Even the most layman in the communication industry can easily judge whether a mobile phone is the "third generation" from its appearance: the third generation mobile phones have a large color display screen, which is often touch-sensitive. 3G mobile phone can not only complete high-quality daily communication, but also carry out multimedia communication. Users can write and draw directly on the touch screen of 3G mobile phone and send it to another mobile phone, which may take less than one second. Of course, you can also send this information to the computer or download some information from the computer; Users can use 3G mobile phones to surf the Internet directly, check emails or browse the web. There will be many models of 3G mobile phones with their own cameras, which will enable users to use their mobile phones for computer conferences and even make digital cameras redundant.
3G communication is a mobile communication service introduced in the mobile communication market after the first generation of analog technology, and it has been introduced into the agenda in the vigorous development of the second generation digital mobile communication market. With the rise of Internet data services and the improvement of fixed access rate (HDSL, ADSL, VDSL), 3G mobile communication system has also seen the dawn of the market, and attracted more and more attention from telecom operators, communication equipment manufacturers and ordinary users.
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