Basic information
As a new technology, CDMA and CDMA2000 are rapidly sweeping the world and have occupied 20% of the wireless market. By the end of 20 12, the number of CDMA2000 users worldwide had exceeded 256 million, and 156 operators in 70 countries had commercialized 3G CDMA services. Dozens of OEMs around the world, including Ankexin Communication Technology Co., Ltd. authorized by Qualcomm, have launched EVDO mobile intelligent terminals. In 2002, the sales of Qualcomm chips in the United States reached a record high. From 65438 to 0994, Qualcomm has provided more than 7.5 billion chips to many global manufacturers, including China. 3G was born under this background.
Generally speaking, 3G refers to a new generation of mobile communication system that combines wireless communication with multimedia communication such as the Internet. In the future, 3G will be combined with community websites, and the combination of WAP and WEB is the trend. For example, popular Weibo websites like David and Sina Weibo have added this application. [ 1-2]
The main difference between 3G and 2G is the speed of voice and data transmission. It can better realize global wireless roaming, handle images, music, video streams and other media forms, and provide various information services including web browsing, teleconference, e-commerce and so on. At the same time, we should also consider the good compatibility with the existing second-generation system. In order to provide this service, the wireless network must be able to support different data transmission speeds, that is, at least 2Mbps (megabits per second), 384kbps (kilobits per second) and 144kbps in indoor, outdoor and driving environments, respectively (this value will change according to the network environment).
The first generation of analog mobile phones (1995) can only make voice calls.
From 1996 to 1997, the second-generation GSM, CDMA and other digital mobile phones (2G) have added the function of receiving data, such as receiving emails or web pages.
3G is the third generation communication network. At present, China supports three wireless interface standards determined by ITU, namely CDMA2000 of China Telecom, WCDMA of China Unicom and TD-SCDMA of China Mobile. GSM equipment adopts time division multiple access, CDMA adopts code division spread spectrum technology, and advanced power and voice activation can provide at least three times the capacity of GSM network. The industry regards CDMA technology as the mainstream technology of 3G, and ITU has determined three wireless interface standards, namely CDMA2000 in the United States. China Unicom's CDMA was sold to China Telecom, and China Telecom upgraded CDMA to 3G network, with the main feature of providing mobile broadband multimedia services.
In fact, 3G was not born in 2009. As early as 2002, 3G was produced abroad, and China also developed China's 3G in 2003, but it was officially listed in 2009. The theoretical peak speed of the downlink can reach 3.6Mbit/s (2.8Mbit/s), and the peak speed of the uplink can also reach 384 kbit/s, so it is impossible to download a movie at 2G per second, as the Internet said. Of course, it is impossible to download a movie instantly.
538 WCDMA operators have opened WCDMA networks in 246 countries and regions, and the commercial market share of 3G is over 80%. WCDMA backward compatible GSM network has covered 184 countries around the world, and the number of WCDMA users exceeds 600 million.