Just what is 4G speed and how are U.S. carriers offering it?

Find out exactly what the catch-all term for 4G will mean for you over the next few years.

Last week, I talked about the advantages of MiFi solutions over mobile devices with built-in 3G capabilities and highlighted Sprint's Overdrive MiFi device, which the company markets as a 4G device. One of the comments on that post correctly pointed out that the ITU (or International Telecommunications Union – a multination industry group that defines many wireless standards) recently released its definition for the term 4G and that Sprint's WiMax-based device didn't meet that definition.

The truth is that up until last month, there was no definition of what 4G is whatsoever, despite the term appearing in technology news, product specifications, service descriptions by carriers, and plenty of marketing and advertising in both online and offline media.

The term has been in use for the past couple of years and largely served as a marketing phrase that slowly developed into a handful of technologies that carriers and device manufacturers began to adopt in the U.S. and elsewhere. The ITU did formally issue its description of 4G in October. By that definition, however, no technology currently deployed anywhere in world qualifies as 4G.

The definition does specify two major technologies in development (called LTE-Advanced and WiMax 2), both advancements on what carriers currently describe as 4G. Both are still in early demo stages, barely out beyond proof of concept products that won't be available till the end of 2011 (more likely sometime in 2012) in any real form. And that doesn't even factor in how long it will take carriers to ramp up networks for either technology (considering North American carriers have barely begun roll outs of what the ITU would refuse to call 4G).

Adding to the confusion are other trade groups, some of which (like the WiMax forum) are associated with specific technologies, are certifying the existing "4G" technologies as being 4G. In addition, carriers have pretty much been unwilling to give up the 4G label for products and services that they still see as being a generation beyond the current 3G devices and networks.

So, U.S. carriers may not meet the ITU specs for 4G, but practical purposes their advanced technologies might as well be considered 4G in this country – particularly as the technologies they use do offer significantly faster data connections than what is typically thought of as 3G and it's unlikely we'll see any notable adoptions of the ITU's 4G-defined technologies in the next two to four years (if not longer).

What are those technologies? Here's a quick rundown:

WiMax – currently deployed in several cities by Sprint (with plans to support 80 cities by year's end), Clearwire, and Comcast (the cable provider makes it available for data-only devices like notebooks). Sprint's WiMax typically offers speeds of 3 - 6 Mbps (as opposed to 3G's typical 600 Kbps to 1.4 Mbps) and is predominantly seen in just two smartphones on Sprint (the HTC Evo and Samsung Epic) with additional devices expected next year.

LTE – Being deployed by Verizon (expected availability by the end of this year), MetroPCS, and AT&T (available next year), but not yet available, LTE is a competing standard with similar to greater bandwidth than WiMax (Verizon will allegedly support up 5 - 12 Mbps). It has an advantage over 3G technologies as it can be deployed alongside both GSM networks (like AT&T and T-Mobile, which are more common globally) and CDMA (like Verizon and Sprint – though Sprint has settled on WiMax).

HSPA+ - Technically, this is an advanced version of the HSPA 3G wireless protocol (used by GSM phones for data service), but it does offer higher performance (up to 7 mbps) than most 3G networks and devices. It is currently deployed in the U.S. by T-Mobile (AT&T is also deploying alongside of and before LTE), who is billing as 4G service because of its speed advantages with supported devices, some of which are already available including the T-Mobile Rocket 2 modem as well as the G2 and myTouch 4G smartphones.

Ryan Faas writes about personal technology for ITworld. Learn more about Faas' published works and training and consulting services at www.ryanfass.com. Follow him on Twitter @ryanfaas.

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