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The 700mhz Spectrum Auction In Perspective
YIAAL writes "Writing in Popular Mechanics, Robert X. Cringely looks at the upcoming auction of the 700mbz spectrum, which is currently used for soon-to-be-defunct analog TV. 'Why are all these companies so excited? Because the 60 MHz of spectrum that's about to be auctioned is the last prime real estate for mobile communications that will be available in the U.S. for decades to come ... Some pundits (that would be me) think Google will bid to win its spectrum block, then will trade that block to Sprint/Nextel for some of that company's 2.5-GHz WiMAX licenses that are far better suited for data.' Plus, the prospect of offering unlicensed data service in the 'white space' between existing broadcast channels."
The article is just plain wrong when it states that the 2.5GHz band is superior for data, it is not. Throughput is primarily dependent on bandwidth, so 20MHz at in the 700MHz spectrum will effectively carry the same amount of data as 20MHz in the 2500MHz spectrum.
As someone who professionally designs cellular networks I can tell you that for data services 20MHz at 2.5GHz is much better than the same 20MHz at 700MHz. The data rate is determined not only by the channel bandwidth but also by the amount of interference that is generated by neighboring base stations. This interference depends on the RF propagation characteristics. At 2.5GHz the RF signals die off much faster with the distance than at 700MHz. As a result your interference levels will be lower at 2.5GHz. The downside is, of course, that cell coverage area of each individual base station will get smaller and you have to deploy them at substantially higher density. Rule of thumb: for voice you are coverage limited and you want your 700MHz (or 850MHz, ATT, Verizon) and big cells. For data you want small cells and high frequency band (2 or 2.5GHz).
Just my two cents from the tranches.