The International Telecommunications Union had initially defined "4G" technologies as International Mobile Communications (IMT)-Advanced standards that hit peak theoretical data rates of 100Mbps or higher. Needless to say, none of the current wireless data technologies commercially available anywhere in the world come close to those data rates, and actual IMT-Advanced standards aren't expected to be completed until 2012 at the earliest.
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But this doesn't matter much anymore from a marketing point of view, since the ITU threw up its hands late last year and said carriers could use the term 4G to describe any IMT-Advanced forerunner technologies such as LTE, WiMAX and HSPA+. The ITU's reasoning was that such "evolved 3G technologies" provide "a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed." In other words, unless you operate an old-school EDGE network, you can probably get away with calling your network 4G.
So since the term "4G" is used by all major U.S. wireless carriers, and given the fact that it will be a hot topic of conversation at next week's big CTIA Wireless industry event in Orlando, it's a good time to revisit just what kinds of "4G" services carriers are offering and what you can expect from them in terms of data speeds.
-- Verizon became the first major U.S. carrier to adopt LTE (Long Term Evolution) last year and this week is rolling out its first LTE smartphone, the HTC ThunderBolt. LTE is essentially a bridge from 3G technologies such as HSPA and EV-DO Rev. A to the 4G IMT-Advanced technologies that the ITU has in mind. The company made its initial LTE launch covering roughly one-third of the U.S. population. The carrier plans to have its entire current 3G footprint upgraded to LTE by the end of 2013.
As far as speeds go, initial tests of the LTE network showed data downloads frequently topping 10Mbps in most major markets, although these tests were run when the network just started and didn't have much congestion to deal with. A test released this week by PC World showed that Verizon's LTE laptop air cards provided average download speeds of 6.5Mbps and average upload speeds of 5Mbps.
-- AT&T and T-Mobile both use HSPA+, an advanced version of the GSM-based 3G HSPA standard that delivers significantly higher speeds than its predecessor. Whereas older HSPA networks would typically deliver mobile download speeds of under 1Mbps, tests have generally delivered download speeds in the 2Mbps to 4Mbps range. So although HSPA+ may not represent as big a leap forward for mobile data as LTE, it is still a vast improvement over older 3G networks such as EV-DO and HSPA.
The two carriers decided to upgrade their 3G footprints with HSPA+ technology before they take the plunge into LTE over the next two years. AT&T, which said in January that it would be launching more than 20 "4G" devices this year, is planning a limited rollout of commercial LTE services this summer. T-Mobile is expected to start offering LTE services sometime in 2012.
-- Sprint and its partners at Clearwire are the only major players in the wireless industry to have adopted WiMAX as their technology of choice. Their current coverage extends to all major markets and covers more than 120 million points of presence. On average, WiMAX services deliver download speeds of between 3Mbps and 6Mbps, although PC World found in their tests that the network was not available on a consistent basis and also that the speeds of Sprint's 3G EV-DO Rev. A network had actually decreased over the past year.
Sprint has toyed with the idea of adopting LTE to supplement its WiMAX services, as both it and Clearwire would together have enough spectrum to support both technologies if they so desired. The companies will also likely roll out the 802.16m ("WiMAX 2") standard at some point, although that might not occur until 2013 since device certification for the standard is slated to start this year and it will take some time for carriers to commercially deploy the new technology over their existing networks.
Conclusion: Buying "4G services" from a carrier really doesn't tell you anything about its coverage or overall quality. Verizon's LTE network currently offers the fastest data rates of all the networks, although it isn't yet available throughout the entire country and its 3G backup network is significantly slower. T-Mobile and AT&T are currently getting good mileage with their HSPA+ networks and they should remain competitive with Verizon as they start rolling out LTE over the next two years. Sprint's WiMAX network also gets good speeds, although there remains a good deal of uncertainty about the future of its partners at Clearwire.
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