CDMA Networks vs GSM/GPRS Networks

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Ultimate Geek

#5972 22-May-2004 09:32

i used to have a TX95c , low battery life. was another program.

its MMS client was very slow.

also only MMS to 027

the 6220 has video on GSM and no video on CDMA> :)

within a year , i think they wil be equal :)

freitasm

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#5974 22-May-2004 10:39

Now, don't take me wrong, but... 3GSM (WCDMA) or not, I'd like to see the coverage being enhanced. Current GPRS coverage will not be good enough for the spots where 3GSM is not available.

Also, GPRS performance is something that must be worked on. I gave up working on my laptop while in Auckland last week, except where I could connect to Reach Wireless (wi-fi). And Wellington is not better either.

rck

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#5978 22-May-2004 15:50

I have found the TX95 MMS to be the quickest out of any MMS phone I have tested for sending to email or other phones. Particularly voda phones - I can be waiting hours to recieve MMS picks through email. With the TX95 i can access it through email as soon as the phone tells me it is accepted.
You may be referring to the fact that it does not send the MMS as a background function like the nokia's.

sbiddle

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#5979 22-May-2004 16:10

I think you have to look at it a bit like the VHS vs Beta war - CDMA is no doubt the best for data since it has an IP layer built in and not hacked on top but like it or not GSM/GPRS/WCDMA have become the defacto global cellular standard, not CDMA. The Americans even seem to agree with that when they got American companies to deploy a GSM network in Iraq! Had it not been for the actions of the South Korean govt would CDMA have even moved outside North America?

Jama

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#6011 24-May-2004 08:31

sbiddle

You need to think about why the Americans really deployed GSM instead of CDMA in Iraq. CDMA has never been hacked, it is a secure communications network and it is virtually impossible to intercept mobile to mobile CDMA calls. Deploying CDMA in Iraq would have given terrorists their own private communications network. With GSM the Americans can monitor and listen into any conversation they desire.

skyplonk

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#6012 24-May-2004 09:25

"I think you have to look at it a bit like the VHS vs Beta war"

Not really, every 3rd Gen standard is based on CDMA. W-CDMA, EV-DO, EV-DV etc... Every network that has 3G plans are going to go down the CDMA road, in one way or another.

rck

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#6014 24-May-2004 10:04

Johnr, I can only go with what I have personally experienced. Admittedly one was a the Alcatel 735, another was a new samsung. Both phones I had to wait a couple of hours till I was able to recieve the photos in my email whereas with my TX95 I got it through straight away. If thats not a standard thing with the GPRS network then thats good, if you've experienced different then thats even better. I'm only going with what I have personally experienced.

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Jama

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#6016 24-May-2004 10:14

Johnr

You are again very, very incorrect. CDMA can not be intercepted by the carrier - even with a court order. CDMA to landline can be intercepted by bugging the landline, but not CDMA to CDMA.

Another lesson - CDMA 101 - Security

Spread spectrum is the technique of spreading call information over a much greater bandwidth than the minimum required to transmit the original signal. The nature of spread spectrum transmission makes the original signal very hard to detect, and as such it was originally used for military applications, as it is difficult to jam or interfere with the signal.
CDMA technology is based on a 1.25MHz piece of spectrum, which can have many users assigned to it at the same time (users are not always assigned the same channel). All calls are in the same frequency, but are encrypted with unique ‘PN’ codes. The data of an encrypted call is modulated and distributed across the entire 1.25 MHz frequency range, intermingled with the signals of all other users in the same cell. This provides ‘frequency diversity’, which reduces interference and fading.
A CDMA call starts with a standard rate of 9600 bits per second (9.6 kilobits per second). This is then spread to a transmitted rate of about 1.23 Megabits per second. Digital codes are applied to the data bits associated with each user in a cell and transmitted along with the signals of each user in that cell. When the signal is received, the codes are removed form the desired signal, separating the users and returning the call to a rate of 9600 bps.
Increased privacy is inherent in spread spectrum technology. As CDMA uses spread spectrum technique, phone calls are more secure from the casual eavesdropper since, unlike an analogue conversation, a simple radio receiver will not be able to pick up individual conversations

An integral part of spread spectrum technology and multiple users is 'pseudonoise' or 'psuedorandom' (PN) codes. A PN code is a psuedo-random binary sequence (that is, it is made up of zeros and ones), and can be up to 2

42 -1 bits long. CDMA combines PN codes with the digitised voice or data signal to encrypt each signal differently. The PN encryption is calculated by a secure algorithm, which results in a random and unique signal for each call generated.
Only the phone receiving the call has the ability to unscramble the signal, as only the intended phone is told (by messages at call setup) the correct PN code to use. All other calls are picked up, but as they are unable to be read, they are effectively filtered out as background noise.
Each mobile phone receives the sum of all randomised signals from the cell site; but each phone is only able to unscramble one component; the one using its own assigned PN code. (In essence, when the '0's and '1's which make up a signal are combined with the PN code of each phone, all undesired signals add up to zero, and the desired signal is the only one which forms a pattern which may be converted into speech.)
There are three types of PN code:
Short PN Codes (32,768 bits long)
Long PN Codes (more than 4.4 trillion bits long)
Walsh Codes (only 64 bits long)
PN codes are used in combination, and a unique PN code is generated for each call by combining all three types of code. PN codes are used differently on forward and reverse links.

It takes 42 days for Telecom to recycle through the Long PN Codes. By the time you worked out what PN Code was used for a specific voice call the call would be well and truly finished.

Next Question?

ajones

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Wannabe Geek

#6070 27-May-2004 13:06

Damn, shot down in FLAMES!

"I have some meetings coming up with some folk from vodafone Europe that have rolled out 3G there which I am really looking forward too." What exactly do you do at Vodafone?

alasta

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#6073 27-May-2004 14:01

I've been watching this thread with interest and it's good to see plenty of well educated opinions coming out.

Based on what I've seen here, it seems as though the conclusion is that CDMA is the superior standard from a technical point of view. My question is this: who cares? The average consumer is much more interested in the practical aspects rather than the technical aspects of a particular network. Handset availability, roaming and choice of providers are all key aspects for consumers when they make their decision.

At the end of the day, people are more likely to choose a provider and accept their technology rather than choose a technology and accept a provider.

JaBZ

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Ultimate Geek

#6074 27-May-2004 14:13

alasta obviously I care, which is why i created the topic.

My opinions and ideas expressed in posts are solely my own and do not reflect the views of my employer in any way..

skyplonk

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#6075 27-May-2004 14:31

And I think people do care, once they know.
Not everyone. But people do.

skyplonk

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#6077 27-May-2004 14:45

What do you do for Vodafone John? You must of missed the question when it was asked in this thread before.

If it is a waste of time john, why do you read it? Nobody makes you post here.

freitasm

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#6078 27-May-2004 14:48

What's the problem? Some people do think it's important, and the thread is not a waste of time. If it's not interesting to someone, please don't add noise to the discussion.

alasta

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#6083 27-May-2004 17:32

Many people here disagree venomously with Johnr, and probably with good reason, but I don't really think it's appropriate for anyone to be asking him (or anyone else here for that matter) questions about the nature of his employment. As far as I'm aware, he is not acting as a representative or spokesperson for Vodafone on this forum, and I note that he has already stuck his neck out in the thread about Vodafone text messaging rumours.

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