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The author:(作者)qq
published in(发表于) 2015/6/6 7:32:52
Why most mobile phones do not support China Telecom？ ，

Colleagues have been complaints recently Telecom, I asked him why, he said: "telecommunications signal is too weak, and my patience can only complain, but look at this card with me for many years, was reluctant to change a number's sake, I change the card a long time ago! "But there are a lot of friends asking" this phone does not support Telecom card? "This shows that the telecommunication users struggled, leave open. Puzzling small part is to check out why many manufacturers most models do not support Telecom card.

Three carriers, China Mobile, China Unicom, China Telecom. Use GSM technology for mobile and China Unicom, said in detail, our country has three main 3G standard, CDMA2000 and TD-SCDMA,WCDMA, respectively, these three 3G criteria respectively, by China Mobile, China Unicom and telecom operations. WCDMA network, 3G network of China Unicom, Waugh; TDSCDMA has a network, China Mobile's G3;CDMA IS95,CDMA 1x,CDMA 2000 is the network of China Telecom, CDMA 2000 is 3G, we call him sky wing. That is mobile and China Unicom was accepted, only its own network of telecommunications, Telecom Mobile phones are generally only used with Telecom card.

Cell phones since the development has gone through 4 generations, 1G (first generation) that the first generation of mobile communications technology, represented by the now obsolete analog mobile network. Mobile was the main representative, although now in the movies are cool, in fact, first-generation analog mobile network it is easy to listen.

2G (second generation) that the second generation of mobile communications technology, represented by the GSM, digital voice transmission technologies at the core. 2.5G is based on the transition between the 2G and 3G types. Than 2G on the speed, bandwidth has increased. Existing GSM network can be easily achieved with easy access to high-speed data packet.

LBS is the third generation of mobile communications technology, is a general name for next generation mobile communication systems. There are three main 3G standard of our country, namely TD-SCDMA,WCDMA and CDMA2000, the three 3G criteria respectively, by China Mobile, China Unicom and telecom operations.

4G mobile network structure can be divided into three layers: the physical network layer, application environments in the middle layer, network layer. The fourth generation mobile communication system based on orthogonal frequency division multiplexing (OFDM) technology core. Characteristics of OFDM technology is highly scalable network structure, has good noise immunity and anti-multi-channel interference, you can provide a higher quality than wireless data technology (high speed, bears) service and better price-performance ratio, 4G wireless network can provide better solutions. That is 4g is the most efficient, best communications guarantee, cost-effective cell phone era. Above for cell phone history, as we understand the fundamentals of mobile.

China has three major operators, though most families are using China Telecom Internet, but China Telecom in mobile deployments and far less investment than China Mobile and China Unicom, mobile telecommunications base stations mostly technology and equipment in China Unicom, especially 4G, clear understandable for telecommunications users give money to telecommunications, Telecom took part to China Unicom. This is the strategic cooperation, but should be noted that Unicom Telecom 4G ≠ 4G. Business monopolies and other reasons, China Unicom and China Telecom are using FDD-LTE format, but Unicom mobile phone does not support Telecom card, Telecom Mobile phones do not support China Unicom 4G (Netcom), business call "double 4G" means supporting Unicom 4G and mobile 4G, Telecom 4G Telecom Mobile and Netcom-only support.

Is a high throughput manufacture of telecommunications equipment, Qualcomm in EV-do networks (Telecom CDMA network) is an absolute monopoly, Telecom 4% patent charge for the high pass (now do not know how much), mobile phone manufacturers only Qualcomm chips down again to join the telecommunications system, monopoly and message into chip provider Qualcomm have explicitly abandoned in CDMA-4G of research and development. While CDMA networks in the world's countries less in international roaming can only replace the GSM card. So now that most cell phones will not be the first time a CDMA version.

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