"PC World" (http://www.pcworld.com) will report the full results of its 3G wireless testing carried out this winter in an issue to hit newsstands in early March. The feature article was published today at the magazine’s web site.

The most dramatic improvements in speed and reliability since the last round of testing in spring 2009 belong to AT&T. AT&T, which earned "PC World’s" lowest score last spring for download speeds and reliability, pumped out download speeds that were 67% faster than any other national wireless carrier in the latest testing.

“AT&T’s network has undergone a drastic makeover in the last eight months, and it's reflected in our test results. In the 13 cities in which we tested, we found AT&T's average download speeds increased by more than 80%,” says "PC World" Senior Editor Mark Sullivan.

AT&T's download speeds tripled in New York City in the publication's latest tests, compared to the results of an identical study conducted by "PC World" last spring. In San Francisco, AT&T download speeds were 40% faster. The carrier’s network has been the target of sharp criticism from iPhone users in both cities.

The AT&T network’s reliability improved drastically as well: Last spring, "PC World" testers got a usable broadband connection with AT&T only 68% of the time. In the latest tests, testers connected to AT&T successfully in 94% of their attempts.

Verizon Wireless, which performed best all-around in last spring’s 3G network testing, and Sprint, a close second, both continue to perform well, according to the recent study. The tests found that Sprint’s network delivered download speeds nearly identical to those measured eight months ago in the 13 test cities, while Verizon’s download speeds decreased by 8% on average.

Like AT&T, Sprint and Verizon face an increase in broadband-hungry smartphones relying on their networks. Both companies are working to upgrade their networks to meet the demand, but Verizon may be having more difficulty keeping up, Sullivan says in the report. Nevertheless, both networks’ reliability (the likelihood that a user can connect to the Internet at a reasonable speed) increased in the most recent tests compared to results from last spring.

"PC World" included T-Mobile in its tests for the first time this winter. Its download speeds were competitive with those of Sprint and Verizon in the tests in most major cities.

Throughout December and January, the publlication’s testing partner, Novarum, tested the download speeds, upload speeds and network dependability of AT&T, Sprint, T-Mobile and Verizon 3G networks from 20 locations in each of 13 U.S. cities. Using laptops running Ixia ixChariot testing software and smartphones running the Internet-based Extreme Labs mobile broadband performance test, Novarum performed more than 10,000 tests in total.