Different technologies enable the high speed data services offered by cell phone providers in USA today. Verizon uses LTE. Sprint employs WiMax. And AT&T and T-Mobile use HSPA+.
Today, T-Mobile seems to be in the lead in the race to offer 4G service. The company's HSPA+ 21 megabit per second service is available in more than 100 metropolitan networks, potentially serving 200 million people. Check your T-Mobile 4G coverage here
http://t-mobile-coverage.t-mobile.com/hspa-mobile-broadband#check-your-4g-coverage-data
Now T-Mobile has switched on HSPA+ 42 mbps service in 55 cities. You'll need a $99 USB modem sold by T-Mobile to take advantage of the higher speeds.
http://www.engadget.com/2011/05/24/t-mobile-flips-on-42mbps-hspa-across-55-markets-to-launch-rock/
Verizon is in second place in the race to deploy 4G. Its 4G service is available now in 40 markets that serve 110 million people. Verizon plans to add an additional 100 markets by the end of 2011.
http://news.vzw.com/news/2011/03/pr2011-03-21a.html
Check Verizon's LTE coverage here
http://network4g.verizonwireless.com/#/coverage
Sprint claims WiMax 4G coverage for 40 million people. The coverage map is here
http://coverage.sprint.com/IMPACT.jsp?ECID=vanity:coverage
AT&T is working to update its data network to 21 mbps HSPA+. The carrier hopes to provide HSPA+ 21 to 2/3 of its customers by the end of 2011.
http://www.pcmag.com/article2/0,2817,2384959,00.asp
Check 4G data coverage on the map here
http://www.att.com/network/#fbid=iiDlcu4ll2k
That's the story on 4G availability. But what about performance?
It's hard to predict exactly what sort of download speed you'll receive from a 4G device. The quality of your connection and the number of other people using the service at your location will affect the speed on a moment-by-moment basis. Also important is the type of equipment you're using. Using the same 4G technology, a USB modem attached directly to a computer generally returns the fastest results A mobile hotspot is next fastest. And a smartphone generally is the slowest.
A couple of magazines and blogs have reported test results that compare 4G service in different cities. Verizon LTE comes out on top, with real world test results producing download speeds between 8 and 10 megabits per second. Uploads average about 5 mbps. Services from other carriers are half as fast as Verizon, or slower.
A couple of test results:
http://www.popularmechanics.com/technology/gadgets/reviews/should-you-make-the-jump-to-4g
http://www.msnbc.msn.com/id/41485079/ns/technology_and_science-wireless/t/putting-g-speed-test/
http://www.pcworld.com/article/221931/4g_wireless_speed_tests_which_is_really_the_fastest.html
Generally, you'll need a new phone or data device to take advantage of the latest 4G services provided by the cell phone carriers. The list of phones that support 4G data is expanding daily.
Unfortunately, most existing phones can't be upgraded as new 4G service appears. If you have an older phone, a mobile hotspot may be the answer. The hotspot connects to your phone via WiFi, and to the carrier's data service via 4G.