Category: UMTS

UMTS is operated on the 2.1 GHz band (or UMTS operating band I) pretty much everywhere around the globe. The U.S., however, is a special case. There, the band is already occupied for other uses. Thus, operators are using the 1900 MHz band both for 2G and 3G wireless (UMTS operating band II) and in addition the 850 MHz band (operating band V), again both for 2G and 3G. It looks like T-Mobile ran a bit out of luck when it came to 3G as they had to resort to a frequency band which is not used by anyone else so far.

During FCC frequency auctions last year, T-Mobile received frequencies in the what seems to be the new 1700/2100 MHz band (UMTS operating band IV). Here’s a report from Unstrung that describes this detail. The 1700 MHz part is used for the uplink while the 2100 MHz part of the spectrum is used for the downlink (network to mobile). I guess this is a bit confusing because speculations have been going on if T-Mobile will be compatible with UMTS devices sold in the rest of the world in the areas where they deploy 2100 MHz. Well no, they are not because the 2100 MHz part is just the downlink part of their spectrum. The uplink is on 1700 MHz and not on 1920-1980 MHz as for UMTS operating band I devices.

Here’s the table of UMTS operating bands from the standards (3GPP TS 25.101). Take a look on line 4. The frequency ranges match with those in the Unstrung report about the auction I linked to above.

Therefore be careful! Some people are saying that T-Mobile U.S. uses 2100 MHz but it is slightly off the European band. Well, that’s not accurate. The 2100 MHz portion is inside the frequency range used in the rest of the world. The uplink however, is totally off mark.

I am not sure if T-Mobile U.S. will be happy with these frequencies both long and short term. Not even the latest and greatest data cards supporting multiple UMTS bands like the Globtrotter from Option supports band IV today. Also, I wonder if the band will be used in other regions of the world in the future. If not, T-Mobile might have a big problem with 3G handset vendors as the market for band IV devices will be quite small. Also, the use of yet another frequency range for 3G in the U.S. will fracture the market even more.

While being at the 3GSM congress last week, I used the opportunity to visit my publisher and to pick up a couple of good books which will keep me entertained in the weeks to come. One of these books is "HSDPA/HSUPA for UMTS" by Harri Holma and Antti Toskala.

If you ‘only‘ want to get a good overview of HSDPA (and UMTS), you might want to take a look at my book first. If, however, you want to get the nitty gritty details, read the standards (like I did before writing my book, but not really recommendable as you’ll die of boredom or confusion unless you are a die hard like me) or Harri’s and Antti’s book. In chapter 7 on HSDPA bit rates, capacity and coverage, they feature an interesting mathematical formula on how to calculate the CAPEX (capital expenditure) cost per giga byte transmitted over HSDPA depending on the price per base station (or price per TRX to be exact).

They concluded that at a price per base station (Node-B) with six transceivers of around €100.000 (which includes the partial price of the RNC and core network serving this base station) the CAPEX cost would be around two to four Euros per GB of data traffic. An interesting number! Be careful, however, as the OPEX (operational expenditure) part of the cost is still missing. Also, the formula does not take partly loaded networks into account. They also give the price per GB of data traffic for other network / base station prices as well.

So what’s the cost of a UMTS base station these days? I did some research on this on the Internet but came up almost empty handed. Seems to be quite a well kept secret. The only reference I could find on UMTS and GSM base station prices is in an article on Unstrung from 2004. Here, Brett Simpson of Arete Research LLC is quoted giving a price for a UMTS base station in 2004 of $24.000. It seems rather low to me. Anyone got other sources?

For more on network capacity and cost take a look at my "The 1 kb/s 3G surfer" blog entry.

3G has been around for a couple of years but I guess even at the congress, networks have only been lightly loaded in the past as most people were still using 2G phones.

This year, things are a lot different. Except for ‘proud’ Berry owners, most other people these days carry a 3G phone and are using it heavily to make calls. I’ve also seen people skipping the Wifi coverage, which is a bit slow at times from what I have heard, and instead use their 3G PC card to access the Internet.

One of the toughest 3G environments in the world must be hall  8 this week with all major mobile phone manufacturers being present and showing their latest and greatest phones using the four public 3G networks. There must be hundreds of phones in this hall using the networks simultaneously and still they manage to show their online demos with good performance.

Every now and then I go online as well to get my eMails and to post my blog entries with my mobile phone. The network feels a bit slower in the halls than elsewhere but still I get my work done.

I think this speaks for a number of things. Firstly, all operators on site must have made sure their networks have enough capacity. It also shows UMTS is able to perform well in such demanding environments. And lastly, I think that 3G network use for both voice and data this year at the conference is most likely is higher than the use of the GSM networks.

The public does not seem too far behind. Yesterday, T-Mobile announced a revenue of 1 billion (dollars?) from data services excluding SMS in their group last year. Agreed, this is only a tiny fraction of their overall revenue, but data use has increased 8 times over the previous year and the amount of data transfered is doubling every quarter. Looks like competitive and attractive prices for mobile data finally get the mobile Internet train rolling.