How Fast Are 4G Phones, Really?

NEW YORK (TheStreet) -- With the 2011 Consumer Electronics Show in Las Vegas right around the corner, tech's focus has turned to new gear.

In particular, tech watchers await the next generation of smartphones -- and for 2011, that means ones that will run on brand-new 4G networks.

AT&T(T), Sprint(S), T-Mobile(DT), MetroPCS(PCS) and Verizon(VZ) have already started touting their 4G networks and wares.

But just how fast is 4G, really? It's not an easy thing to pin down.

There really isn't an official definition that says how fast 4G wireless networks should be. The International Telecommunication Union, the group that sets standards for Europe and the rest of the world, said in November that 4G is defined only as a network capable of download speeds of 100 megabits per second (Mbps).

But earlier this month, the organization backtracked and said 4G should include the current WiMAX, LTE and HSPA deployed by the top U.S. carriers.

Current High-Speed Networks -- 3G and 4G

In terms of sheer speed -- disregarding things like network congestion that slows them down -- these are the current high-speed 3G and 4G standards currently available in the U.S.

EV-DO (Evolution-Data Optimized). 3G. Works on CDMA and TDMA networks. In its latest form, called Rev. A, it's supposedly capable of data speeds approaching 3.1 Mbps. Carriers that use it: Sprint, Verizon.

UMTS (Universal Mobile Telecommunication System) and HSDPA (High-Speed Download Packet Access). 3G. Supports GSM-based networks all over the world. On paper, UMTS/HSDPA systems supposedly support speeds up to 14.4-Mbps. Carriers that use it: AT&T, T-Mobile.

HSPA+: T-Mobile calls it 4G; the carrier said it has rolled it out to 100 cities across the U.S. On paper, this network supposedly provides as much as 42-Mbps down-links.

WiMAX: 4G. Most mature 4G network in the U.S. Mobile WiMAX is said to offer peak data rates of 128 Mbps down-link and 56 Mbps up-link. The next version of WiMAX aims to run at 1 Gbps (that's 1,000 Mbps) for stationary reception and 100 Mbps for mobile users. Available in 71 cities across the country. Carrier: Sprint Nextel.

Sprint 4G phones that run on WiMax: HTC EVO and Samsung Epic.

LTE (Long Term Evolution): 4G. Officially, LTE offers speeds of up to 100 Mbps in the down-link mode and 50 Mbps for up-links under the best conditions. (Stay tuned -- TheStreet will soon be posting tests of LTE smartphones). Carriers: MetroPCS (in nine markets), Verizon (in about 40 cities), AT&T.

Currently, MetroPCS sells one 4G handset -- the Samsung Craft -- and Verizon sells modems that operate on its LTE data network.