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Friday, December 5, 2008

technology about 3G mobile

:: 3G Defined
3G (Third Generation) is a generic name for a set of mobile technologies set to be launched by the end of 2001 which use a host of high-tech infrastructure networks, handsets, base stations, switches and other equipment to allow mobiles to offer high-speed Internet access, data, video and CD-quality music services.

Data speeds in 3G networks should be show speeds of to up to 2 Megabits per second, an increase on current technology.

:: 2G/2.5G Defined
GSM for example is a 2G technology. It uses TDMA technology, proving data speeds of 9.6kbps/14.4kbps. The packet radio upgrade to GSM, called GPRS, can have speeds of up to 114kbps. GPRS an interim technology towards 3G, and hence is known as 2.5G. GSM might go the same way as the older first generation (1G) NMT and AMPS networks in 8-15 years because of the use of newer and better UMTS technology (More on GSM) ; (More on GPRS)

The new 3G services are almost all flavours of technolgies based on the generic name, CDMA (Code Division Multiple Access). CDMA is a digital wireless technology that allows multiple users to share radio frequencies at the same time without interfering with each other. A telephone or data call is assigned a unique code that distinguishes it from others and and since the signals hop among different frequencies.

Current 2G services using the original CDMA "IS-95" technology are know as cdmaOne. 3G services will use new high-speed versions of CDMA called W-CDMA, or its competing technology, cdma2000. (More on CDMA)

In all, these technologies fall under the ITUs generic name of IMT-2000 (International Mobile Telecommunications 2000). But when the ITU tried to unify and standardise 3G technologies, no consensus was reached. There were thus five terrestrial standards developed as part of the IMT-2000 program. Instead, depending on where in the world 3G will be implemented, the 3G standard will be based on CDMA variants cdma2000 or W-CDMA.

CDMA 3G Variants (in the IMT-2000 Family)
The primary CDMA variants that will be used in IMT-2000 3G networks are W-CDMA (Wideband CDMA) and cdma2000, which are similar but not the same, so that W-CDMA handsets will not work with cdma2000 handsets and visa versa.

W-CDMA (Wideband CDMA)
W-CDMA is the competitor to cdma2000 and one of two 3G standards that makes use of a wider spectrum than CDMA and therefore can transmit and receive information for faster and more efficiently. Co-developed by NTT DoCoMo, it is being backed by most European mobile operators and is expected to compete with cdma2000 to be the de facto 3G standard

In Europe, 3G W-CDMA networks are known as UMTS (Universal Mobile Telephony System) another name for w-CDMA/3G services. Governments in the region held UMTS auctions for 3G licences netting $108 billion in 2000.


Japanese giant NTT DoCoMo Inc brand name for 3G services is FOMA (Freedom of Mobile Multimedia Access). Based on the W-CDMA format, FOMA services for a limited number of users is to begin at the end of May, with full commercial services due in October 2001.

cdma2000 (See more on cdma2000)
Then there is cdma2000, the other 3G standard. It is the upgarde to cdmaOne. It can use of a wider spectrum than CDMA and therefore can transmit and receive information faster and more efficiently, making fast Internet data, video, and CD-quality music transmission possible. There are however new cdma2000 variants called cdma2000 1X, 1X-EV-DV, 1X EV-DO, and cdma2000 3X. They deliver 3G services while occupying a very small amount of current spectrum (1.25 MHz per carrier) as opposed to UMTS which requires completely NEW spectrum (hence the auctions).

That is why cddma2000 is considered slightly more technologically advanced than the competing W-CDMA standard. CDMA2000 is not constrained to only the IMT band; it is defined to operate in existing cellular and PCS spectrum as well as IMT spectrum, thereby maximizing flexibility for operators. Cdma2000 is expected to be compatible with with CDMA and GSM/TDMA networks so that GSM networks can "overlay" a cdma2000 network over their GSM networks.more [more...]

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