[Touch Diamond, MDA Compact IV General] landshark:
Can anyone explain exactly what it will take for HSDPA in the US?

Hi -

Similar to the original poster, I have been watching with anticipation the development of the Diamond and the XDA cookers' work on unlocking its capabilites. I too am confused, with many conflicting posts about the ability to do HSPDA in the US. Can anyone explain exactly what it will take? Based on my understanding:

1.) Ability to transmit and recieve on the radio frequency used by the telco / phone company for UMTS service (Universal Mobile Telecommunications System). For AT&T, I thought this frequency was 850 mhz. Based on peoples' reports and some testing done, it seems like the Diamond can be unlocked through a ROM flash to broadcast and recieve on 850 mhz. So far, so good.

2.) Ability to use the UMTS service

My reading of Wikipedia seems to say that UMTS is a "technology" -

This is different from a "standard" like GSM,which is an integrated system of hardware (radio transmitters and towers), an "air interface" (a set of protocols to handle packet transfers, analogous to TCP/IP on the Internet, only using radio waves rather than wires), an "infrastructure" (base station sub-system and GPRS (packet) subsystem - towers and the computers and routers that connect them) and connection software (validating users, tracking usage, billing, transmission control codecs, etc.). UMTS is a collection of transmission control codecs and user identification codecs operating within a GSM network. So, UMTS is a phrase that describes improvements to the old, 2G GSM protocols. But it is still GSM.

AT&T in the US is using WCDMA as the "air interface" over which it is running its UMTS service. It is using the 850 mhz frequency. One key difference between GSM and UMTS is that UMTS uses a "Universal Subscriber Identification Modue" (USIM) rather than a plain old Subscriber Identificaton modue (SIM). If AT&T's UMTS service requires a USIM, then having only a SIM will prevent you from accessing the UMTS service - you will only be able to access the data service offered by the GSM, which is EDGE in the US, not WCDMA (i.e., only 2G). This is regardless of hardware. If this is the case, then it's a bummer.

HOWEVER....the UMTS service CAN use SIM cards as well, so AT&T may have theirs configured to use SIM cards as well. I currently have the HTC Trinity with what I think is a SIM card - I was forced to "upgrade" the SIM card when Cingular "integrated" with AT&T, so my card is branded Cingular, but has the snazzy 3G fireball on it. So maybe it's actually a USIM? My Trinity does have the "H" icon show up, and I can get 300kbps or so tethering to my laptop (but not above that - grrrr...) so maybe I'm getting UMTS service on that device? If so, then the SIM vs USIM should not be an issue if I got a Diamond.

3.) Ability to use the HSPDA protocol

As far as I can tell, HSPDA is pure protocol - just like TCP/IP. It achieves faster speeds by using fast packet scheduling and something called adaptive modualtion and coding. It is part of the UMTS standards, so it's actually part fo the overall UMTS system, but not everyone uses it. If your phone and your carrier can use this protocol, you can get HSPDA.

Based on the above, it seems reasonable that the Diamond is capable of transmitting at HSPDA speeds in the US on AT&T's network. Has anyone been able to actually do this? If not, could those much more informed than me explain the obstacle? Is it a setting on AT&T's side? A setting on the Diamond? Is the radio hardware for UMTS somehow different? Does the Diamond lack WCDMA capability due to lack of software?

I understand that some people have tried selecting the band on their ROM-flashed phone to get 3G on AT&T with no success, but that doesn't mean it can't be done. I'm trying to understand the eaxt nature of the obstacle.

Thanks!!!

Mike