Application of CDMA in comparison to GSM

[leoren_tm]

pls discuss GSM versus CDMA aplication..
ty to all

 

[aandavan]

Re: CDMA versus GSM..

hi,
CDMA communication mainly based on a secret code. And also this sort of communication provides full security and reliability because this technique uses the entire bandwidth.

 

[leoren_tm]

Re: CDMA versus GSM..

thx for that.. but i need a brief discusion on its advantages and disadvantages ..
therefore comparing both....

 

[truebs]

Re: CDMA versus GSM..

CDMA is more effective in in terms of Power/ Bandwidth management. Whereas GSM is most commonly used now a days.
As far as i understand CDMA is a better
check out :-
www.mouthshut.com/product-reviews/GSM_Mobile_Technology_Vs_CDMA_Mobile_Technology-925040507.html

 

[leoren_tm]

Re: CDMA versus GSM..

how did you say its better??
pls discuss

 

[spikeyang]

CDMA versus GSM..

For the same frequency bandwidth, CDMA can contain more users than GSM.

 

[leoren_tm]

Re: CDMA versus GSM..

For the same frequency bandwidth, CDMA can contain more users than GSM.

it that true???
i read something that says, cdma would lesser its trasmission quility to occupy the calls....:?::?::?:

 

[louisnells]

Re: CDMA versus GSM..

I think thats not correct, CDMA has a better quality than GSM. Atleast GSM is one generattion lower than that of CDMA. CDMA uses a bandwidth shared by multiple users, but the sharing scheme is not ordinary multiplexing. In CDMA sharing of bandwidth is done by multiplexing by a code. Also when we compare the number of users using a single bandwidth CDMA has a better utilization in the sense of quality of service.

In CDMA the polarized data is multiplied by a code word of specific bit width (which is a noise like signal). Once this is done the output will be a very high bandwidth noise like signal (just like the code word). On the decoder we multiply this signal by the same code word again and gets the data back. Each user uses a unique code word of same bit width, and even if the signals from the all encoders reach a single decoder, only the signal from particular encoder which uses the same code word as the decoder will be decoded correctly, because all other signals from the other encoders and the channel noise will be multiplied by the code word they become a very low noise signal. So the output at the decoder contains the data and the noise, and we can remove this noise easily. This is how we multiplex the bandwidth with the code word.

For the same frequency bandwidth, CDMA can contain more users than GSM.

it that true???
i read something that says, cdma would lesser its trasmission quility to occupy the calls....:?::?::?:

 

[leoren_tm]

Re: CDMA versus GSM..

yha...but it didnt answer my question thou....
CDMA has a good quality, but this would be a tradeoff for a capacity.....
this means if CDMA would have a greater subscriber, it would lesser its quality....
need a explanation on it....
ty

 

[louisnells]

Re: CDMA versus GSM..

Wrong again. In CDMA the whole bandwidth is always used by each user. ie: All encoders transmits to the same bandwidth. Its because on multiplication with the code word the base band input data is converted in to a wideband signal spread over the bandwidth.

Because all encoders share some bandwidth there won't be any degradation in quality with the increase of users. But there is always a maximum count of users. Maximum number of users depends on the code word length (one of the parameters ...), which in turn influences the bandwidth used too. Also each user can use the whole bandwidth for communication.

yha...but it didnt answer my question thou....
CDMA has a good quality, but this would be a tradeoff for a capacity.....
this means if CDMA would have a greater subscriber, it would lesser its quality....
need a explanation on it....
ty

 

[tronix]

Re: CDMA versus GSM..

CDMA vs GSM
Let say we have four couples and they all have to propose to each other and also that proposal can be made inside a particular room only.

What GSM will do:
Let first couple go in - give them a moment or two - take them out and let the next couple go in - allow them some time and so on in a circular fashion till the task is complete.

What CDMA will do:
Let all the 4 couples go in at the same time and let all of them propose simultaneously but now each will be having a decoder which will decode only one of the proposals that is meant for him/her.So its like one will get all the signals but will be able to decode only what is meant for him.

Regards
tronix

 

[konarkk]

Re: CDMA versus GSM..

No need of freq reuse , secure mean of transmission

 

[leoren_tm]

Re: CDMA versus GSM..

CDMA vs GSM
Let say we have four couples and they all have to propose to each other and also that proposal can be made inside a particular room only.

What GSM will do:
Let first couple go in - give them a moment or two - take them out and let the next couple go in - allow them some time and so on in a circular fashion till the task is complete.

What CDMA will do:
Let all the 4 couples go in at the same time and let all of them propose simultaneously but now each will be having a decoder which will decode only one of the proposals that is meant for him/her.So its like one will get all the signals but will be able to decode only what is meant for him.

Regards
tronix

:idea::idea::idea::idea::idea:
very good explanation....thank you very much....
and...???..the GSM advantage??

Added after 1 minutes:

No need of freq reuse , secure mean of transmission

what is frequency reuse??
is that make it better??

 

[FSio]

Re: CDMA versus GSM..

Apparently CDMA is better than GSM for Power/BW.

So, Why most companies (operators) prefer buy GSM equipments instead of CDMA?

 

[louisnells]

Re: CDMA versus GSM..

Reasons:
1) GSM already has a very wide service network
2) Many of the CDMA service thariffs are costlier than their GSM counter-parts

Apparently CDMA is better than GSM for Power/BW.

So, Why most companies (operators) prefer buy GSM equipments instead of CDMA?

 

[leoren_tm]

Re: CDMA versus GSM..

yha....coz GSM came first...
but CDMA will take the market sOON

 

[FSio]

Re: CDMA versus GSM..

thanks louisnells.

I would like to add 2 more reasons:

3) The equipments are cheapper than CDMA. It is a strategic commercial issue, non technical.

4) You missed the MOST important advantage : the SIM CARD. CDMA technology doesn't have it. The SimCARD is a big advantage in the "services' world".


Moreover,
While CDMA tech has to pay a fee to Qualcomm for license(*), it will continue being a technology so expensive, as much for provider as for customers.

Rgs

 

[leoren_tm]

Re: CDMA versus GSM..

yha...SIM card..
but CDMA uses 10times less power than GSM..
CDMA has a 10times less in radiation,
some of news says, skin irratation due to the station of GSM
and also, GSM has less security compare to CDMA!!!!

 

[inifinitrix]

CDMA versus GSM..

what do you mean by 'less security'??

 

[leoren_tm]

Re: CDMA versus GSM..

hmmm... what i mean is that, CDMA was conceptualize by the army, it uses spreadspectrum....
try reading about spreadspectrum..