While 4G promises carriers more efficient spectrum use, greater capacity and the benefits of an all-IP network, the benefit for users is data rates that are much faster than 3G. Verizon Wireless and AT&T say LTE subscribers - on a fully loaded network - can expect average downlink speeds of 5M to12Mbps and 2M to 5Mbps on the uplink. By comparison, Verizon's EVDO Rev A 3G network supports average downlink speeds of 600K to 1.4Mbps and 500K to 800Kbps up.
But actual performance can vary widely, as the RootMetrics data also shows. That's because LTE networks are still being built and tuned, and the number of LTE subscribers is still small compared to 3G.
Who has 4G?
Much of the confusion about 4G is due to the fact that multiple radio technologies are labeled 4G by the carriers. Verizon says it has the largest 4G LTE network, while AT&T claims it has the largest 4G network. What's going on?
"The term '4G' has fallen into the hands of the marketing departments," says Roger Entner, founder of telecom consulting firm Recon Analytics. "Everything a carrier now sells you is sold as 4G....They give you '4G LTE' and the 'regular' 4G. That's the hint. LTE is generally the faster."
Technically one can argue that no carrier today offers a true 4G service. That's because the ITU outlined what it considers "next generation" cellular in its IMT-Advanced specification, which is being embodied in two detailed technology specifications, LTE-Advanced and WirelessMAN-Advanced, sometimes called WiMax 2. LTE-Advanced, for example, will deliver up to 1Gbps for a slow-moving mobile user and up to 100Mbps for one zipping along in a car or train, far above existing LTE speeds. (See LTE-Advanced mobile standard gets go-ahead from industry)
Yet neither of these has yet been implemented (though T-Mobile USA says it will begin deploying LTE-Advanced in 2013, its first LTE offering). But with carriers claiming they offer 4G, in December 2010 the ITU issued a release saying "it is recognized that this term ['4G'], while undefined, may also be applied to the forerunners of these [LTE-Advanced and WiMAX 2] technologies, [to] LTE and WiMax, and to other evolved 3G technologies providing a substantial level of improvement in performance and capabilities with respect to the initial third generation systems." [See ITU softens on the definition of 4G mobile]