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View Full Version : a threat to 3G video calling


Russ
17-10-2003, 19:48
http://www.3g.co.uk/PR/Oct2003/5887.htm

Seeing as 3G's main selling point is video calling, this might not be such good news.

Jerrek
17-10-2003, 20:52
*frown* The G* technologies are old, outdated, and there is no upgrade path. It is a dead end to a technology that was good for the 1990s. 3G is just a technology that tries to add to the dying GSM and GPRS system.

I doubt we will see a strong 3G presence here... CDMA is taking over and CDMA2K is all of 3G but vastly better.

Nidge
19-10-2003, 08:01
3G IMHO is pants. I was looking for a new mobile phone provider the other week and I went on to the 3G website, all they are bothered about is getting you to sign up for the video of football and video conferencing. Have they missed something because 4 million people have access to SKY or cable TV so, why do we want to pay extra when we already pay for it????

Russ
19-10-2003, 10:56
Don't forget the incredible tarrifs. For £35 per month you get 750 cross network/landline minutes.

Downloading videoclips while you're on the move is cool, once you get in to the habit of being able to watch highlights of last nights' match while sitting at your desk it somehow becomes a habit :D

Nidge
19-10-2003, 19:55
Don't forget the incredible tarrifs. For £35 per month you get 750 cross network/landline minutes.

Downloading videoclips while you're on the move is cool, once you get in to the habit of being able to watch highlights of last nights' match while sitting at your desk it somehow becomes a habit :D

Now let me guess Russ Man U was it?????????? :nono: :nono: :nono:

Dooby
20-10-2003, 10:29
*frown* The G* technologies are old, outdated, and there is no upgrade path. It is a dead end to a technology that was good for the 1990s. 3G is just a technology that tries to add to the dying GSM and GPRS system.

I doubt we will see a strong 3G presence here... CDMA is taking over and CDMA2K is all of 3G but vastly better.

3G has nothing to do with GSM or GPRS it is a seperate network which uses UMTS which is. I believe, W-CDMA

In fact CDMA2K is the one that is built on CDMA, as the requirement in the US was to be backwardly compatible, whereas UMTS is a new system ( i.e. it is not compatible with GSM )

oh, and 3G is a wide term that covers several things I believe, it is not a single technology.

this is quite interesting http://www.umtsworld.com/umts/faq.htm

Chris
20-10-2003, 10:48
3G has nothing to do with GSM or GPRS it is a seperate network which uses UMTS which is. I believe, W-CDMA

In fact CDMA2K is the one that is built on CDMA, as the requirement in the US was to be backwardly compatible, whereas UMTS is a new system ( i.e. it is not compatible with GSM )

oh, and 3G is a wide term that covers several things I believe, it is not a single technology.

this is quite interesting http://www.umtsworld.com/umts/faq.htm (http://www.umtsworld.com/umts/faq.htm%20[/QUOTE):spin:

What's this? I go away for a weekend and when I get back the forum's translated itself into Greek ... anyone want to offer a translation of some of the acronyms floating around this thread? (except 3G, I know that one). ;)

Dooby
20-10-2003, 13:17
UMTS = Universal Mobile Telephone System.
CDMA = Code Division Multiple Access
W-CDMA = Wideband CDMA

Chris
20-10-2003, 13:24
UMTS = Universal Mobile Telephone System.
CDMA = Code Division Multiple Access
W-CDMA = Wideband CDMA
I seeeee .... I shouda known better than to ask ... ;)

What does it all mean?

Dooby
20-10-2003, 15:02
I seeeee .... I shouda known better than to ask ... ;)

What does it all mean?

um...thats a more difficult question... its to do with the way you can send multiple calls over the network I think. GSM uses a time based division, so each call gets a kind of 'time slot' to transmit in, where as CDMA is 'code' division... but I am not sure exactly how that works...

*edit* ok just asked teh guy sat next to me ( he used to work for motorolla ) and it goes something like this...

the 'code' is a kind of key... all the different calls are transmitted on top of each other, but the signal is 'processed' to include the key as part of the signal.

when you want to listen to just the one call, you decode the 'common' signal using the code for that call and you get the signal you want enhanced, with all the other signals coming out a bit like noise...


its kind of like having an encrypted file but you are encrypting lots of information into the file with different keys, and depending which key you use you get a different file out.

Dooby
20-10-2003, 15:05
http://thorin.adnc.com/~jd/Qualcomm/party.html
GSM is basically TDMA ( Time Division Multiple Access ) in this example i think

Chris
20-10-2003, 15:16
I think I'm beginning to understand ... so what are the issues here? Which is best? And, to try to stay on topic, is video-phone via a TV set likely to pose a commercial threat to these mobile systems or do they have any particular advantages?

Dooby
20-10-2003, 15:25
i think it is generally accepted that the cdma based technologies are better ( what we know of as '3G' is WCDMA )
as to whether this TV thing will 'kill' the mobile video phone market, well I suppose that is a bit like saying that these new fangled land lines you have in your house will destroy the mobile phone market. the 'in the home' option may be cheaper to use, but they are in your home, not out on a walk with you, or at the bus stop, or on the train etc etc..

I am no great believer that the whole video phone thing will take off, but it has some uses.
as for picture messaging, well, ok as a fad but I am not sure it has the same appeal as text messages ( sorry txt msgs :rolleyes: ) as one of the advantage of them is they are inobtrusive to both parties.
tbh, the LAST thing I want is to have my mum phone me AND for her to be able to see what I am doing :o

Chris
20-10-2003, 17:26
the LAST thing I want is to have my mum phone me AND for her to be able to see what I am doing :o
lol ... that could be awkward! Actually in 12 or 15 years' time I'm looking forward to keeping track of my son, who will be a teen by then, using a vid phone and being able to check that he is where he says he is.

As to video calling from home, I think it sounds like a great idea but I look at the problems ntl has setting up and running the services it's already launched and I think ... naah, it'll never work.

Besides, full-screen video conferences at our office currently use up 6 ISDN lines simultaneously in order to deliver high-ish quality video and audio. How is this meant to work in a domestic context?

Dooby
20-10-2003, 17:55
Besides, full-screen video conferences at our office currently use up 6 ISDN lines simultaneously in order to deliver high-ish quality video and audio. How is this meant to work in a domestic context?
yeah, we have a similar system here, uses a leased line to the US and the image quality isnt great... I find it hard to believe that you can get the image quality shown on that picture via an analogue phone line, unless maybe the frame rate is 1 frame per minute or something LOL.

Jerrek
20-10-2003, 21:07
The first cell phone system, other than regular frequency modulated waves, was TDMA. TDMA stands for Time Division Multiple Access. With TDMA, multiple phones used the same frequency. Phones would digitize the voice and transmit it in the allocated timeslice. TDMA timeslices are 30 KHz in bandwidth.

GSM is based on TDMA, but instead is only 25 KHz. GSM was quite a bit of an improvement over TDMA.

Along came CDMA, or Code Division Multiple Access. CDMA was invented and developed by Qualcomm and is a very, very nifty piece of technology. With CDMA, phones on the same frequency band do not take turns because they don't need to.

(Note: CDMA, TDMA, and GSM all refer to the RF (radio frequency) layer of cellular communications)

CDMA was so revolutionary when it was first discussed that a company deeply involved with GSM (based on TDMA), Ericson, went through the three stages of Not Invented Here Syndrome.

1) It is impossible!
2) It isn't practical.
3) Actually, we thought of it first.

After two years of lawsuits against Qualcomm and losing every single lawsuit, Ericson finally bought rights to use CDMA. Qualcomm won.


So, what do uses what?


Basically, Europe uses GSM because the European governments, at that time, thought GSM was so good and they passed legislation making it illegal to implement any other system. The advantage was clear: a unified system for Europe.

In the United States and Canada, the FCC decided not to take sides and let the free market decide which one will win out. This resulted in chaos for a few years because both CDMA and two implementations of TDMA (GSM and IS-136) was implemented accross the country.

After some company mergers, it ended up that:

- AT&T uses IS-136. IS-136 (based on TDMA too) is dead and has absolutely no upgrade path.

- Cingular uses GSM.

- Sprint and Verizon (Bell) uses CDMA.


So what is the significance of that? Well, people wanted to start using their phones for more than just voice. In comes data transmissions.

In GSM, a timeslot is 25 KHz going both directions. Of course, when I'm listening to you speaking, all the phone is catching is my breathing which is basically the lower end of the spectrum. A lot of KHz is wasted.

In CDMA, the amount of bandwith that a phone uses changes 50 times per second. So when I'm breathing, I only use 1/8 of the bandwith that I use when I'm talking. This is VERY useful for voice, but ESSENTIAL for data because data tends to be very bursty, and CDMA was designed to do this. Using the existing infrastructure, data transmission became relatively easy. 9600 and 14400 kbps was easy to achieve using 8K and 13K codecs. When higher rates were needed, augment the phones with a new codec and using the same infrastructure and frequency allocation, 56k could be reached.

When GSM tried to do this, that is, send data at a rate faster than the existing voice channel supported, they ended up having to allocate an entirely new carrier just for that job which handled NOTHING except data, and they had to deploy a NEW infrastructure to do that. Welcome to GPRS. GPRS is expensive to deploy and expensive to use because it is VERY inefficient.

So you can see the difference here. CDMA use the same carrier and bandwidth is allocated 50 times per second automatically. You can implement high speed data without having to install new transmittors and antennas.


So what does this mean?


Well, people wanted even greater data rates. It was clear that GSM was not going to do that. The CDMA interface was very much superior to GSM and TDMA.

So, Qualcomm was once again innovating. They designed the new 3G system with new capabilities and they made it backwards compatible. The result is CDMA 2000, or CDMA2K. No new spectrum is required because it is backwards compatible.

That wasn't the case for GSM. CDMA and TDMA is not compatible at all. It is like Apple and PC. The architecture is just different. The new system, called WCDMA, will not be compatible with existing TDMA (GSM) handsets. It is just technically impossible to make it compatible. Worse yet: you can't phase the existing specrum over. When WCDMA appears, existing GSM users will have to install it, issue new handsets to all customers, and then one day throw a switch. Alternatively, they can license a new spectrum just for WCDMA while continuing to run GSM.

(Note: Of course you can build a WCDMA handset so that they can use TDMA (GSM). It just makes the phone wickedly expensive.)


DoCoMo was the first company that deployed WDCMA in Japan. They had to recall and replace thousands of handsets at its own expensive because of fatal technical problems. In fact, they did this TWICE. Oh and, their name is mud in Japan now, and will probably never recover.


CDMA2K, on the other hand, is real and it works. Sprint and Verizon and Bell are already using it, and it works pretty damn well as demonstrated by KDDI in Japan (DoCoMo's rival). Lots of Japanese have handsets with little cameras in them and use it to send each other pictures.


European service providers are in trouble though. They had to spend substantial amounts of resources on a license for a new spectrum (for WDCMA) that they can't really use. Even worse is that the license specify that they can ONLY use it for WDCMA. Others are asking if they can have permission to deploy CDMA2K instead, but the bureaucrats in the EU aren't having any of that. For now.


Now someone is bound to point out how GSM is more widely deployed than any other system. True, but be sure to point out that the bribes that went along with it. (Think: If you choose GSM over CDMA, we'll build a factory here." (*cough* Brazil))


So, what is happening now?

Well, European telephone companies are not doing so well. A few years ago Germany had to bail out MobilCom with 400 million euros. They had to lay off 40% of their staff. Lets not even talk about France Telecom.

Morale of the story? Don't let the government interfere in such matters. Europeans had a nice system in the 1990s because of one standard, but it ended up being the wrong standard and now **** is happening.

So right now, enjoy WDCMA and the costs involved. It is years behind schedule. In the meantime, I'll enjoy CDMA2K which works.


(I don't mean to bash Europeans in this post, but sometimes their government do stupid, stupid, stupid things.)

Chris
20-10-2003, 23:57
(I don't mean to bash Europeans in this post, but sometimes their government do stupid, stupid, stupid things.)

Particularly European 'government'. Don't worry, a lot of us 'Europeans' would entirely agree with you. Europe aint nothing but trouble.