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Where are the TDMA/FDMA techniques used?

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venkat3271

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Hello friends,
can somebody post where TDM, FDM are used.also where TDMA/FDMA are used.
I know what these terms are.I am just asking where these techniques are used in real time world applications.?
 

fm_com_28

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gsm tdma fdma

TDMA/FDMA is used in 2G of mobile communication in the European Standard. GSM is one of these technologies.
 

kengloong

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tdma fdma

As I understand, both of the technologies is used in Cellular Communications Systems.

For FDMA, it's used in first generation cellular com. systems. (e.g. NMT, ETACS, AMPS, etc...)
(Frequency Division Multiple Access) The technology used in the analog cellular telephone network that divides the spectrum into 30 kHz channels.

For TDMA, it's a second generation mobile. (e.g. GSM, PCS, etc...)
(Time Division Multiple Access) A satellite and cellular phone technology that interleaves multiple digital signals onto a single high-speed channel. For cellular, TDMA triples the capacity of the original analog method (FDMA). It divides each channel into three subchannels providing service to three users instead of one. The GSM cellular system is also based on TDMA, but GSM defines the entire network, not just the air interface.


Cellular Generation
1G - Analog
Introduced in the late 1970s and early 1980s, the first cellular systems were analog. They were used for data just like land-based telephone lines are used for dial-up with analog modems. A handful of cellphone models could be adapted to laptop modems and transfer data at less than 15 Kbps while traveling. (e.g. AMPS, TACS and NMT.)

2G - 2.5G - Digital
The second generation refers to digital voice cellphone systems deployed in the 1990s, which were based on GSM, TDMA or CDMA. Several so-called 2.5G (or 2G+) technologies added data services for Internet access and e-mail with typical downstream speeds ranging from 64 to 200 Kbps for the user. These include GPRS, EDGE and IS-95B. (e.g. GPRS, EDGE and IS-95.)

3G - High Speed
Launched after the turn of the century, the third generation offers faster access to the Internet and other data services with typical downstream speeds ranging from 400 Kbps up to 1 Mbps for the user. Defined by the ITU under the IMT-2000 framework, 3G is implemented regionally in Europe (UMTS), North America (CDMA2000) and Japan (NTT DoCoMo). EV-DO, WCDMA and HSDPA are examples of 3G data services. 3G also embraces worldwide roaming for global travelers. (e.g. GAN, EV-DO, WCDMA, HSDPA, CDMA2000, UMTS and 3GPP.)

4G - Higher Speed for Movies and TV
In the 2008-2010 time frame, 4G cellphones are expected to support TV in realtime as well as video downloads at high speed. It is also expected to embrace automatic roaming to non-cellular systems such as Wi-Fi, satellite and other wireless networks, whichever is most appropriate. NTT DoCoMo's 4G service is based on WCDMA; however, carriers in the U.S. and Europe are expected to deploy other air interfaces. (e.g. NTT DoCoMo and WCDMA.)
 

ismailbtk

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tdma, fdma, cdma

TDMA is used in GSM i-e 2.5G
 

raghuram_msc

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tdma and fdma

Hi all,

Rather as an "appendix" to the detailed post of kengloong I may add....

These technologies come into picture for one main reason that the frequency allocated to any service provider is quite limited, where as he/she has to serve ever increasing number of customers, remaining within that very BW.

Basically there are two "channels" involved in mobile technology, namely, Data and Voice channels.

All the said technologies refer to optimising these two for best performance...!

Sai
 

suru

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fdma and tdma

TDM IS USED IN TELEPHONE COMMUNICATION WHEREAS FDM IS USED IN TV CHANNELS.
 

hamed_sotoudi

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gsm tdma/fdma

Hi
both of this techniques are used in netwrks which theris collision. that is there is only on medium for sending data which is share among more than 2 devices. for example when 2 mobile set wants to comunicate the only interface is the air so if both of them work with the sam frequency and send data at the same time there data collide. so u can use TDMA or FDMA for the first for one period of tme on of them send and another period of time the second. or u can use more than 1 frequency that is every of this devices use a deffirent frequency which is the FDMA.
 

suru

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fdma vs tdma

tdma-USED IN TELEPHONE/MOBILE SERIVE WHREAS FDMA IS USED IN TV CHANNELS TRANSMISSION.
 

kengloong

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fdma cellular phone

suru said:
tdma-USED IN TELEPHONE/MOBILE SERIVE WHREAS FDMA IS USED IN TV CHANNELS TRANSMISSION.
Not necessary, FDMA also been used in mobile communications, e.g ETACS, AMPS, NMT450, etc... For me, its just a method of multiplex the signal/ channel.
 

raghuram_msc

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frequency division multiple access

Hi
both of this techniques are used in netwrks which theris collision. that is there is only on medium for sending data which is share among more than 2 devices. for example when 2 mobile set wants to comunicate the only interface is the air so if both of them work with the sam frequency and send data at the same time there data collide. so u can use TDMA or FDMA for the first for one period of tme on of them send and another period of time the second. or u can use more than 1 frequency that is every of this devices use a deffirent frequency which is the FDMA.
Friend this generally cannot happen..!!! The reason is all wireless communications & mobile in purticular use very robust encrption technologies. Even though two signals (say) originating from any cellphone whatsoever and having precisely the same frequency can never "colide" with another and at the same time never be picked-up by any cell phone other than the one intended to receive.

Sai
 

springf2000

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how gsm uses both fdma and tdma techniques

GSM IS TDM/FDM used
 

pngzhi

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tdma vs fdma

In the GSM system the TDM/FDM combination is used.
 

avi_e-

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tdma fdma amps

Hi Friend,

1)TDM - Time Division Multiplexing

2)FDM - Frequency Division Multiplexing
--------------------------------------------------------------------------------------------
1)TDMA - Time Division Multiple Access

2)FDMA - Frequency Division Multiple Access

3)CDMA - Code division Multiple Access

Note in this the first two are entirely different from the second three.

The first two are used to modify the signal in such a way that you want.

The second three are the mobile phone reception technologies.

In this you will be aware of CDMA technology.

Refer www.wikipedia.com & www.howstuffworks.com for further assistance.



Regards,
Avinash.S.
 

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