What you really need to know about 4G LTE

The road to faster mobile broadband is paved with false marketing promises, but some are becoming real

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You might think that once all the carriers have adopted LTE, you'll be able to buy a smartphone, tablet, or mobile hotspot and use it with the carrier of your choice.

Think again. LTE devices will be as tied to carriers as CDMA devices are to Sprint or Verizon and as GSM devices are to AT&T or T-Mobile. This is not necessarily a technical issue with LTE, just as it is not with GSM, as evidenced by the many countries that forbid such tie-ins -- which explains why you can move an unlocked phone across carriers in many countries.

In the United States, a major reason for the lock-in is the fact that carriers have licensed different bands of the 4G radio spectrum, as they have with the 3G spectrum. Thus, the 3G radios in an AT&T device access different radiofrequency bands than those in a T-Mobile device, though both companies use the same GSM technology. That's why an unlocked AT&T iPhone accessing a T-Mobile network must use 2.5G frequencies. The same is true across the major CDMA carriers: Sprint, Verizon, and Metro PCS. Verizon has said that this radiofrequency divide will continue into LTE, and LTE devices designed for competitors won't work on its LTE network and vice versa.

There is of course a straightforward solution to the radiofrequency divide: the use of radios that access all 3G and LTE spectrum bands. That's what a "world" phone's radio does. Such radios cost a litle more, but the real reason they are not standard is that the U.S. carriers don't want their customers to be able to easily change providers, as they can in other parts of the world. Mobile device makers -- even Apple, though to a lesser extent -- design their device models specifically for each carrier to honor such customer lock-in requirements.

There you have it: the truth about 4G in general and LTE in particular. 4G is coming, but slowly and in a way that perpetuates today's carrier lock-in strategies. I wouldn't make 4G compatibility a litmus test for choosing a new smartphone, tablet, or mobile hotspot, but if a device you happen to like for the carrier you prefer is available in a 4G model, give it serious consideration. After all, the 3G parts also work.

This article, "What you really need to know about 4G LTE," was originally published at InfoWorld.com. Read more of Galen Gruman's Mobile Edge blog and follow the latest developments in mobile technology at InfoWorld.com. Follow Galen's mobile musings on Twitter at MobileGalen. For the latest business technology news, follow InfoWorld.com on Twitter.

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