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

As the hype around 4G cellular networks begins to really heat up -- AT&T, Sprint, T-Mobile, Verizon Wireless, and even cheapo carrier Metro PCS are flogging its faster speed and greater bandwidth in their ads -- it's time to be clear on what 4G really does for you and if it's worth factoring into your smartphone and tablet plans. The short answer: not yet.

4G means fourth-generation; today's devices and cellular networks use a mix of third-generation (3G) and late second-generation (2.5G) technologies. Even after a decade of 3G availability, we all know how often that 3G symbol on our iPhones or Androids goes away, replaced with an icon indicating a slower, 2.5G network such as EDGE or GPRS. Certainly, 3G isn't where it needs to be yet, and now you're being sold 4G.

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First, let's sort out what 4G really means
Per the definition of the standards body International Telecommunications Union, a 4G network is supposed to deliver at least 100Mbps throughput from a fast-moving vehicle such as a car or train or 1Gbps from a stationary position. It's also supposed to abandon the spread spectrum technology used in 3G networks for frequency-division technologies such as OFDMA that basically packetize network traffic much as the Ethernet protocol does for LANs. That way, individual channels aren't hogged up by individual connections as happens today.

There are no 4G networks on the market today that do these things. The two standards that meet these requirements are LTE-Advanced and WirelessMAN-Advanced, neither of which is anywhere near real-world deployment.

But there are three technologies that get the 4G label in the carriers' marketing, and for the next three to five years at least, they'll be what 4G means in a practical sense. They are LTE, WiMax, and HSPA+ with backbone assist. After the ITU said none of these networks qualified as 4G last year, its carrier members quickly twisted arms and got the ITU to claim that "precursor" technologies leading to these standards could use the 4G label. That means LTE and WiMax.

HSPA+ doesn't count because it is simply a faster version of the HSPA 3G technology long used by AT&T and T-Mobile. Both carriers claim that combined with a faster backbone network in some locations, HSPA+ speeds can equal those of LTE. That may or may not be true at any specific location, but it doesn't matter. As carriers move to first "precursor" 4G technologies and then true 4G, 3G technologies are nearly at the end of their capabilities. Today's faux 4G from AT&T and T-Mobile will not fool anyone in a few years.

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