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What Is The Difference Between TDMA, FDMA, CDMA, and WCDMA?

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ghazal gi Profile
ghazal gi answered
Well these are all the technologies which are used for the mobile or wireless communication. And all of them came one after another. All of these are the good technology of their time.First about the Time Division Multiple Access, this is the acronym of TDMA. In this technology whole the frequency band is assigned vertically in the form of fixed number of slots to individual users for a specific time. Disadvantage of time and bandwidth. And also the data stolen problem.    Then the Frequency division multiple access, which is the acronym of FDMA came. In this the given bandwidth is dived into fixed number of frequencies horizontally. And in this also the one frequency is assigned to individual users; it will remain idle, if that user is not sending any data. In this also there is bandwidth and time wastage. Here also data stolen problem  Then after that a new technology came i.e. Code Division Multiple Access that is the acronym of CDMA. This is the 3G technology. In this bandwidth is not divided into any thing. Data can be send to any frequency at any time by any user; there is not any fixed number of users. And the data steel problem is also solved. This technology is in use now a day.  The new updating of the CDMA is WCDMA. In this all the good qualities of the TDMA, FDMA, and CDMA is used.
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Anonymous answered
FDMA,as the name implies operates by dividing thebandwidth of the wireless channel equally among a number of users wanting to access the channel.ie frequency division multiple access. It was the first technology used.
TDMA was the next to come, it was the opening of digital world.It had an attractive feature that it does accommodate the transmission of source channel encoded digital data alongside digitized speech in straightforward manner.With TDMA channel bandwidths are wider than FDMA and fading is no longer frequency flat,but rather frequency selective.IT is time division multiple access.GSM was from this global system for mobile,it has frame structure with 8 time slots.
CDMA refers to a multiple-access technique in which the individual terminals use spread spectrum technique and occupy all the spectrum whenever they transmit,it is the interference attenuation property of the spread-spectrum that allows multiple users to occupy the same spectrum at the same time.It is the coded division multiple access it uses the coding. The 3g is from this, WCDMA is wide band cdma, that is it uses both fdma and tdma techniques very effectively to bring about a big change in mainly the packet radio systems.

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