WCDMA v. HDSPA v. UMTS
 

I know a WCDMA 2100 phone is needed to work in Japan. I read on a couple web sites that HDSPA is an advanced version of WCDMA and is backwards compatible with WCDMA.

My question is: Is a HDSPA 2100 phone usable in Japan?

Am I correct in stating that all WCDMA phones are UMTS but not all UMTS phones are WCDMA?

Thanks for any light someone can shed on this.

...mike

1- yes, because hsdpa on umts as like as edge on gsm network

2- no, wcdma is the core technology of the umts, so is pratically the same to say wcdma phone or umts phone
(read http://www.gsmworld.com/technology/3g/faq.shtml )

WCDMA is an interface between the phone and the network.

The first generation of WCDMA phones used UMTS.

The second generation uses HSPA, which permits faster data transfer. It is backwards compatible with UMTS.

All WCDMA networks to my knowledge support UMTS. Only some support UMTS.

If you get a device that supports UMTS but not HSPA, you will be able to use 3G WCDMA networks but those that support HSPA will only work for you at UMTS speeds. If you use an HSPA phone on a UMTS network that doesn't support HSPA, again your phone will work but you will not get the maximum speed your phone can handle.

If you need HSPA where it's available, get an HSPA phone. If you don't, a UMTS phone will suffice. For voice, the difference is nil. It's only a data issue.

Is there any difference in the SIM between UMTS and HSPA? I've seen people selling HSDPA SIMS but wondered if this was just marketing and they're the same as UMTS. By analogy that no special SIM is needed for EDGE.

Can't really answer your question, however I'm aware of one SIM card that works in HSDPA/HSUPA devices but doesn't in UMTS devices.

Speed :)

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[via HSUPA, qualcosa si muove] <!--post-->

WCDMA is the designation of a multiplex technology describing the way data is radio-transmitted.

WCDMA is used in several mobile communication standards, which are namely FOMA, UMTS-FDD/HSPA and UMTS-TDD.

FOMA is an early 3G-standard, which was only used in Japan and was very similar to UMTS-FDD. After UMTS-FDD was standardized NTTDoCoMo, who were the only operator of a FOMA-network, switched their whole network to UMTS-FDD. So FOMA is dead today.

WCDMA is often used synonymously for UMTS-FDD, but actuallty UMTS-FDD is just one standard using WCDMA. However since UMTS-FDD is the major 3G-standard worldwide, it is often refered to as "UMTS" or "WCDMA".

UMTS-TDD, which is incompatible to UMTS-FDD has been deployed in very few places and isn't marketed as "UMTS" anywhere, afaik.

So all in all when you read "WCDMA" or "UMTS" people mean "UMTS-FDD".

HSDPA is an enhancement of UMTS-FDD providing [B]download[B] bandwidth of up to 14.4 MBit/s instead of only 384 KBit/s.
HSUPA is another enhancement of UMTS-FDD providing [B]upload[B] bandwidth of up to 5.76 MBit/s instead of only 384 KBit/s.
If a device supports HSDPA and HSUPA it is called "HSPA", which is kind of needless, since all HSUPA-devices support HSDPA. So talking about "HSUPA" implies HSDPA-support.

HSPA has been subject to improvements raising download bandwidth to more than 14 MBit/s, which is then called HSPA+. Australian operators even plan to provide 42 MBit/s by the end of 2010.

HSDPA/HSUPA/HSPA is basicly still UMTS-FDD with the ability to reach higher speed by improved modulation. So both are fully compatible. So a HSPA-device will work on a UMTS-only-nework and a UMTS-only-device will work on a HSPA-enabled network, however in both cases speed will be limited to 384 KBit/s.

Besides this question of standard you should bear in mind, that many frequency bands are used for UMTS and only very few devices support more than one frequency band.
Whereas Europe, Oceania and Asia mostly operate UMTS at 900 and 2100 MHz, American UMTS-networks work at 850, 1700 and 1900 MHz. Afaik there is still no device available supporting all these five UMTS-bands, so it's impossible to have a worldwide compatible UMTS-device, whereas that's possible for GSM by buying a quadband-phone.
For a complete list of UMTS-bands see: UMTS frequency bands - Wikipedia, the free encyclopedia

Forgot to mention, that HSDPA is also called 3.5G and HSUPA/HSPA 3.75G.

UMTS-TDD is used in only 20 networks worldwide: UMTS TDD Alliance :: Deployments

@AndreA
Why have you set up such a short timelimit for alterations? I think one whole hour would be better.

No, there are no special HSPA-SIM cards. There is only a difference between plain GSM-SIMs and UMTS-SIMs (so-called "USIMs"). Wether a subscriber may use HSPA on a UMTS-network or not depends on what's defined in the HLR.
The main difference of GSM-SIMs and USIMs is the authentification-methods, since these differ between GSM and UMTS. However you can still configure UMTS-networks to accept GSM-autentification. Therefore in Germany you can access the T-Mobile and Vodafone networks even with ancient GSM-SIMs, whereas eplus and O2 insist on UMTS-authentifiation, so their customers need a USIM to register on the UMTS-networks. Since this is a question of network configuration a eplus/O2 subscriber with GSM-SIM can theoretically still access foreign UMTS-networks while roaming, as far as GSM-autentication is accepted.
Besides this relevant difference USIMs usually have higher memory capacity.

That's true. Anyway I'm loving my upload speed :D