The differences between CDMA, FDMA and TDMA

hi guys i read abt cdma fdma tdma.i didnt understand their differences.i would like to know which is superioir and why....
any body can help me plz...........

Re: hi cdma fdma tdma

FDMA is basically Analog technology and the oldst one. TDMA is digital and being used in GSM. CDMA is newest of all, whre all users are allocated a distinct code.

Added after 2 minutes:

For easy and basic understanding I will recommend " Data Comm and Networking" by Behrouz Forouzan

hi cdma fdma tdma

Hi

In TDMA any user can access each time slot.Many booke say that CDMA is better.

Re: hi cdma fdma tdma

First, what is "MA" means:
MA=Multiple Access, which means that many users share the same medium. There are many techniques to share the medium between them;

FDMA=Freq division multiple access:
where each user has its own freq band that is allocated for him all the time.

TDMA=Time division multiple access:
where all the users share the same frequency band but part of the time, i.e. no more than one user can occupy the freq band at the same time.

CDMA=Code division multiple access:
where each user is different than the others by its own code that identify him from all the other users. Hence, all the frequency band is for all users all the time.

If it hepls you, press "Helped me"

KAMAL

Re: hi cdma fdma tdma

Hi
You can also refer to the link :



tronix

hi cdma fdma tdma

Anyone has info or documents on SDMA ( Space Division Multiple Access).

Regards
M

Re: hi cdma fdma tdma

hi
One Doubt on this topic.

How to differentiate Multiplexing and Multiple Access Exactly?

Since even for both we saying (e.g FDM/FDMA frequency is dividing between users)How that parameter frequency exactly differentiating MA and Multiple Access?

Thanks in Advance
PraveenGoud

Re: hi cdma fdma tdma

hi to all
1)FDMA: frequency division multiple access and in this technique the total bandwidth is divided between users,i.e. all users send the data on the same time but different frequencies. FDM is the same but the only difference is in FDM we have one transmitter and more than one receiver (like the radio broadcast) but in FDMA we have more than one transmitter trying to access one receiver (like the mobiles trying to access base station).
2)TDMA: time division multiple access and in this technique time is divided between users,i.e. all users send the data on the same bandwidth (the same frequency) but in different time slots. the same concept with TDM.
BOTH FDMA and TDMA are used in GSM
3)CDMA: code division multiple access and in this technique each user is assigned to a certain code that enable the user to extract the information,i.e. all the users send the data at the same time and the same frequency. this technique has a lot of advantages than FDMA and TDMA like Jamming immunity,security, privacy and the number of users that share the same communication channel is greater than FDMA ana TDMA.
CDMA is used in 3G

hope every thing is clear now

bye[/u]

Re: hi cdma fdma tdma

CDMA is the best technology for mobile telecommunication, it gives you higher bandwidth,
but the modulation and and demodulation is more compicated.
BR

Re: hi cdma fdma tdma

CDMA is better than TDMA.

Re: hi cdma fdma tdma

> CDMA is used in 3G???

FALSE.

For 3G, the standard is WCDMA, CDMA2000, TDSCDMA...
CDMA is used in 2G.


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Re: hi cdma fdma tdma

Hi P,

Multiplexing and Multiple Access.

Multiple Access refers to media access technology... i.e. how users are assigned slots or channels on the Medium (wireless channel)
While Multiplexing refers to what you do with your data. i.e. how ur analogue or digital signal are combined into a signal to be transmitted over the medium.

Simply put, Mr A,B C and D intends to use a particular frequncy channel.
I need to use 'multiple access' techniques to allow them use the channel. Say i am the controller, i decide whether to use TDMA, CDMA, or FDMA(this is not digital. its only for voice transmission) to divide the channel between them.
That sorted;
Each of A, B,C and D now decides what to do with their slots. Each may decide to use OFDM or FDM to 'multiplex' its signals over the allocated channel slot assigned to them.
I hope you find this useful.

Someone pls correct me if this is wrong.

Re: hi cdma fdma tdma

hi spikefeet

MA(multiple access) means many users share the same medium.

FDMA (Frequency Division Multiple Access) :
here the same freq. band is subdivided into many bands.
each user is assigned to a particular freq band. each user are distinct.
The main problem is thereis chance for freq interference.

TDMA(Time Division Multiple Access):
Here same freq is used for all the users. But their alloted time is different.
Main disadvantage is more delay

CDMA(Code Division Multiple Access):
It is the most useful and good access technique.
Here each user is assigned to a particular code and is more secure.

this is the basic and u go through book for more.....