General discussion

3G Frequency

Does anyone have an explanation on why the 3G implemented in the US is different from the one that is implemented from Asia?

From what I know:

US: There is Uplink and Downlink and both are on different Frequency
Ex - AT&T 850MHz uplink and 1900MHz downlink
Ex - T-Mobile 1700MHz uplink 2100MHz downlink

Asia: Both Uplink and Downlink is on the same frequency
Ex - Singtel 2100MHz

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It's all about...

...what parts of the electromagnetic spectrum have been allocated for various purposes in different areas. For example, Military or Emergency services may be using a particular frequency in India but not in North America, etc.

Arguably the U.S. frequency band situation for cellular is the most annoying of all. Here's a table which may help a little-


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Uplink Downlink

That wasn't really what I was expecting. I think I might have not explained myself that clearly.

I understand that the spectrum is used by many companies other than the cell phone companies.

My question is why did they implement different spectrum for Uplnk and Downlink instead of a single spectrum for it as what is being done in Asia.(I might be mistaken here)

Why didn't AT&T and T-Mobile use 1900MHz and 2100MHz respectively for uplink and downlink? Why did they split the downlink and uplink to 2 different spectrums?

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Although I am not 100% certain, perhaps if not enough bandwidth was available around 1900 for the full monty, that's likely why they had to split it w/ 850 in north america. Also, keep in mind that technically, if I understand the situation correctly w/ 2100, the uplink is 1920-1980MHz while downlink is 2110-2170 for band I UMTS service. They just call it 2100. Look at the band I specs again on the UMTS chart.

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