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3G for Dummies |
Hlcn Twst
Joined: Jul 27, 2006
Posts: > 500
From: Purgatory, Utah, USA
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I'm obviously a dummy, as even Wikipedia's explanation of 3G is incomprehensible to me 
I know what it is in principle - the new generation of mobile internet after EDGE (2.5G).
What I don't understand are the different frequencies, protocols, etc. in use around the world. AFAIK, Cingular (USA) is expanding its existing 850/1900 MHz network to run HSDPA. T-Mobile (USA) bought up 1700 and 2000 MHz spectrum for its 3G, whatever protocol they choose to implement. This much I have gleaned from this article. Looking at the mobile phones sold outside the USA, it appears to me that the rest of the world uses 2100 MHz WCDMA. Do I have this correct so far?
What are HSDPA, WCDMA, etc.? What is UMTS? And what would a true "world" 3G phone need other than being quad-band (for voice) + EDGE? (The HTC Hermes is I believe truly world-capable, as it has 3 different 3G implementations built-in.)
Thanks in advance 
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I am the love child of Dionysus and Athena 
[ This Message was edited by: Hlcn Twst on 2007-05-02 17:52 ] | |
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JK
Joined: Feb 24, 2005
Posts: > 500
From: S. Africa - JOZI
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On 2007-05-02 15:43:00, Hlcn Twst wrote:
I'm obviously a dummy, as even Wikipedia's explanation of 3G is incomprehensible to me
I know what it is in principle - the new generation of mobile internet after EDGE (2.5G).
What I don't understand are the different frequencies, protocols, etc. in use around the world. AFAIK, Cingular (USA) is expanding its existing 850/1900 MHz network to run HSDPA. T-Mobile (USA) bought up 1700 and 2100 MHz spectrum for its 3G, whatever protocol they choose to implement. This much I have gleaned from this article. Looking at the mobile phones sold outside the USA, it appears to me that the rest of the world uses 2100 MHz WCDMA. Do I have this correct so far?
What are HSDPA, WCDMA, etc.? What is UMTS? And what would a true "world" 3G phone need other than being quad-band (for voice) + EDGE? (The HTC Hermes is I believe truly world-capable, as it has 3 different 3G implementations built-in.)
Thanks in advance
Ok you get different types of data carriers, 1st being GPRS which can send data in small slow sizes, like pictures etc MMS.
Then came EDGE which a faster data carrier, twice as fast as GPRS! Almost fast enough to view live streams.
Then come 3G which is very fast 384KBS it enables live video streaming, video calls fast internet downloads.
Then comes HSPDA which is around 6 times + faster than 3G, meaning if you wanted to download a 2MB file it could theoretically download it in 1 second!!!
WCDMA is old technology ie it bills internet usage by the minute whereas 3G/HSDPA bills only the data downloaded.
Hope u understand.
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Hlcn Twst
Joined: Jul 27, 2006
Posts: > 500
From: Purgatory, Utah, USA
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WCDMA is old technology ie it bills internet usage by the minute whereas 3G/HSDPA bills only the data downloaded.
Wow, so Cingular is actually ahead of somebody? The end is nigh!
Around the world, who uses what? Outside the US, is it WCDMA or something else?
Here in the US, anyone know what T-Mobile will use? (I may be switching from Cingular.)
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JK
Joined: Feb 24, 2005
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From: S. Africa - JOZI
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On 2007-05-02 16:24:28, Hlcn Twst wrote:
WCDMA is old technology ie it bills internet usage by the minute whereas 3G/HSDPA bills only the data downloaded.
Wow, so Cingular is actually ahead of somebody? The end is nigh!
Around the world, who uses what? Outside the US, is it WCDMA or something else?
Here in the US, anyone know what T-Mobile will use? (I may be switching from Cingular.)
We have HSDPA which is 1.8 MBs, we heading into the 3,6MBs very soon and then 7,2MBs!!
We had 3G around 2.5 years ago.
The US is behind but they catching up fast, there biggest mistake was not using GSM!!
As for T-mobile im not sure what they will use. Probably the 3G/HSDPA route.
WCDMA is what we call CSD ie Circuit Switched Data... Like I said Old technology now.
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Hlcn Twst
Joined: Jul 27, 2006
Posts: > 500
From: Purgatory, Utah, USA
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The US is behind but they catching up fast, there biggest mistake was not using GSM!!
Our biggest problems have been spectrum allocation and cost. The world decided to make GSM run on 900 and 1800, two frequencies the US had long since allocated to other uses. (IIRC 900 was for cordless phones and baby monitors, and 1800 is a restricted government frequency.) This limited the handsets available to us, thus artificially retarding our advancement in GSM.
Ditto for 3G - 2100 MHz is also a restricted frequency here. I could say this was a deliberate conspiracy against the US 
As for cost: It's neither cheap nor easy to set up towers across a nation as large and, in most places, sparsely populated as the US!
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BobaFett
Joined: Jan 06, 2004
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From: Kamino (wish it would be Lund)
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click here "technology"
http://www.gsmworld.com/index.shtml
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aatuif
Joined: Sep 04, 2006
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From: KASHMIR
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In india, we still linger on with gprs, with very few pockets having edge connectivity... No 3G yet...
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carkitter
Joined: Apr 29, 2005
Posts: > 500
From: Auckland, NZ
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Here in New Zealand we have only two network operators:
Telecom NZ (CDMA/CDMA2000 1xEV-DO) and Vodafone NZ (GSM/GPRS/UMTS/HSDPA)
Most of the 3G vodafone mobiles here are 384kbps.
The Vodem that plugs into my laptop supplies me with 3G at (supposedly) 3.6Mbps and there are PCMCIA cards (3.2Mbps) and 3G Wifi routers (384 kbps) available.
Some useful info here
Its rumoured that Telecom NZ may drop CDMA and finally build the GSM network they should've built long ago.
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dayz
Joined: Oct 03, 2006
Posts: 144
From: Philippines
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philippines do now offer 3g but the speed is like GPRS
i pity our network T_T |
aatuif
Joined: Sep 04, 2006
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From: KASHMIR
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Quote:
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On 2007-05-05 09:11:53, dayz wrote:
philippines do now offer 3g but the speed is like GPRS
i pity our network T_T
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how can 3g speed be like gprs... it can't stoop that low... maybe it isn't 3g after all...
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BobaFett
Joined: Jan 06, 2004
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From: Kamino (wish it would be Lund)
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it can be that slow, if the operator built a crap system or if the system is given, but isnt that far developed, as the amount of the users. at more connections ( more uers in the same time as the system it allowes ) it gets slow. it happens to easto from time to time as well, shown " too many connections"
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mikeb
Joined: Nov 12, 2002
Posts: 98
From: Sweden
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Hi,
to try and answer your oringal question.
First we have GSM, which origanlly was on the 900MHz frequency band. The GSM specification was enhanced with GPRS (packet data) for speeds up to 115 kbps (theoritical, 30 to 40 in reality). After GPRS, the GSM specification was further enhanced with EDGE, to support up about 200 kbps (about 100 to 150 in reality).
In radio specifications it is normal to specify the "peak data rate" i.e. the maximum possible bit rate (in GSM that is governed by the modulation scheme used and the number of timeslots allocated). It is rare to achieve these peak rates outside of lab conditions, because radio is a shared media and must be shared by all users in the cell (for voice and data). In live networks it is rare you can get the max possible resource allocation (because other people would also like to send data or make a call). In addition to that, interference and other problems means you rarely get the highest modulation scheme (the higher the modulation scheme, the higher the bit rate, but as you move away from the base station you get weaker signals and more interference, so you need more robust modulation schemes, i.e. lower modulation and lower bit rates).
As the 900 Mhz band was being filled to capacity, 1800 MHz was specified for GSM to allow for expansion (i.e. more capacity = more users).
Hence GSM is in the 900 and 1800MHz frequency bands worldwide, except the USA.
In the US, 900 & 1800 MHz is not available. Hence for the US market (but also for a few other countries), 1900MHz was specified for GSM.
Hence today the majority of GSM phones are tri-band, 900, 1800 & 1900 MHz to be able to work worldwide.
In recent years in the US, the 850MHz band became available for GSM and there are 850MHz GSM phones out there, typically tri-band 850, 1800 & 1900MHz or quad-band 850, 900, 1800 & 1900MHz.
When it came to 3G, the orginal specification for WCDMA (often referred to as Release 99 or R99 to indicate what year it was specified) it was decided that up to 2Mbps should be supported and a new technology needed a new spectrum allocation. Worldwide 2100MHz was identified as the spectrum band for WCDMA. The specification for WCDMA R99 does support up to 2Mbps, but in reality (mainly because of complexity & cost) most WCDMA networks & phones only support a max of 384 kbps.
Like GSM, it is rare you will achieve 384kbps outside a lab and speeds between 200 and 300 kbps are more common.
Also, to avoid having to rollout WCDMA nationwide on day 1, it was specified how to hand over from WCDMA to GSM (and vice versa). This meant you could start a voice call (or packet data session) on WCDMA and if you moved outside coverage handover to GSM. Hence most 3G phones typically support WCDMA on 2100MHz and GSM on tri-band 900, 1800 & 1900MHz.
Once again, 2100MHz was not available in the US, so for the US the 850 and 1900MHz frequency bands were specified for WCDMA as well.
It is only this year we are seeing the first quad-band 850, 900, 1800 & 1900MHz GSM + tri-band 850, 1900 & 2100MHz WCDMA terminals becoming available.
The next evolution step after WCDMA R99 (which covers voice & data) was to enhance the data speeds. So it was decided in release 5 (they changed the release numbering scheme as well, to make sure you were confused) to enhance the downlink packet speeds, to support a peak data rate of 14Mbps. This is called HSDPA (High Speed Downlink Packet Data Access).
However to achieve 14Mbps you need a terminal (mobile) that supports up to 20 codes (in WCDMA you use codes, instead of timeslots). However this is both complex and costly. So the first generation of terminals only supported 2 codes (which is 1.8Mps). Then there were terminals that could support 5 codes (3.8Mbps) and finally there are a few terminals on the market capable of 10 codes (7.6Mbps). It is unlikely (but not impossible) we will see terminals (mobiles) capable of supporting the full 14Mbps any time soon.
In release 5, you are still limited to 384kbits on the uplink. So in release 6 (which we will see deployed in the market this year) they enhanced the uplink, called HUSPA (High Speed Uplink Packet Data Access) to support up to 5.6Mbps (although again, for complexity and cost reasons most first gen mobile terminals will only support 1.6Mbps on the uplink).
More commonly, HSDPA + HSUPA are referred to as simply HSPA (High Speed Packet Access).
In the future (release 7 and release 8 ) we will see the specfication for HSPA enchanced with MIMO to support 28 Mbps and later also higher modulation schemes as well, to boost peak data rates to 42Mbps.
Finally, to finish, you asked what is UMTS ? Well UMTS is the Universal Mobile Telephony System. It is the requirement specification for a 3G mobile telephony network. It comes from ITU (International Telecommunication Union).
You see GSM, WCDMA, HSPA all these lovely acroymns only refer to the radio interface. For a true mobile telephony system you need to specify the entire network inter-working (how to authenticate end users, how to sign on to the network, how to do roaming, how to do hand overs, charging etc.).
So 3GPP (an organisation that makes the specifications) covers the entire network architecture. 3GPP makes the specficiations for how it all works (according to the ITU requirements) and this is then sent to ITU to get it accepted internationally (which is why your mobile phone works when on holiday in Spain) .
I hope this helps and is not too confusing,
/Mike B.
[ This Message was edited by: mikeb on 2007-05-06 18:46 ] |
aatuif
Joined: Sep 04, 2006
Posts: > 500
From: KASHMIR
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Helped, in my case...
thanks...
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occupied
Joined: Feb 24, 2007
Posts: 99
From: Middle of Nowhere
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Haha america is obviously left behind china. China is about to implement 4G, and you're talking about 3G here 
and wikiPOOdia isn't a reliable resource...
Actually in some countries, wcdma/umts billing systems are provided in both time-based and data-based so users have an option which one to use.
And mike, good posting pal | |
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Posted: 2007-05-02 15:43
