T-Mobile’s 4G network speed doubling this year to 42 Mbps

T-Mobile has grand plans to double its 4G network’s speeds from 21 megabits per second to 42 Mbps in 2011, the carrier announced today at the Consumer Electronics Show in Las Vegas.

The announcement makes it clear that T-Mobile is betting its network on HSPA+ technology, instead of competing 4G technologies like LTE and WiMax used by other US carriers.

The company expects HSPA+ to dominate LTE over the next few years, reaching as many as 2.5 billion people by 2015. Eventually, an advanced version of HSPA+ could reach speeds of a whopping 672Mbps.

T-Mobile said it has already activated the faster 4G service in Las Vegas, and offered up some details on how it compares to other 4G networks. In testing around the city, T-Mobile found that its 4G network was about on-par with Verizon’s LTE network with speeds around 8.5Mbps. Sprint’s WiMax network, on the other hand, lagged behind with speeds around 3Mbps.

A brief demonstration of the improved HSPA+ network in the conference room showed average speeds of around 28.6Mbps (I assume being stationary helped the test to achieve such high speeds). T-Mobile also showed off a fast-paced online racing game, which seemed just as smooth as playing an online game with home broadband.

The company touts its HSPA+ 4G network as the largest in the country, covering over 200 million people. At the moment, T-Mobile says its 4G network is 40 percent larger than Verizon’s recently launched 4G LTE network, and 40 percent bigger than Sprint’s, which has had a two-year head start on its competitors.

T-Mobile also briefly showed its new G-Slate tablet by LG, but sadly it was nothing more than a photo opportunity. We expect to hear more details on that soon.