The U.S. doesn't have full 3G coverage yet, but the nation's major carriers are already looking ahead to deploying 4G, as they continue their 3G rollout.  Sprint was the first major carrier to start to deploy a true 4G network (WiMAX).  Now T-Mobile has announced that its 3G upgrade of its current network is complete and it is beginning its own effort to deploy 4G (via HSPA+, then LTE).

T-Mobile uses High Speed Downlink Packet Access (HSDPA) to offer downlink speeds of up to 7.2 Mbps (peak speeds) on its 3G data network.  Previously the telecomm had only offered slower 3.6 Mbps downlink rates.  T-Mobile also has announced that this high-speed-upgraded network now covers 200 million Americans.

Next up, T-Mobile is focusing on deploying Evolved High Speed Packet Access (HSPA+) across its network.  A trial deployment is already underway in Philadelphia.

HSPA+ will bring downlink speeds of up to 56 Mbps and uplink speeds of up to 22 Mbps.  Actual improvements, though will vary based on how close you are to a T-Mobile tower with HSPA+ capabilities (that's the nature of the technology, not a T-Mobile-specific shortcoming).  The closer you are, the bigger the boost you get.  Customers far from a tower may not notice a significant speed increase. 

T-Mobile plans on completing its HSPA+ network upgrade by the end of this year, and will be the first major carrier in the U.S. to do so (granted Sprint already is rolling out the WiMAX, arguably a more advanced standard).  Of the GSM carriers (AT&T, T-Mobile) in the U.S., though, T-Mobile will be the top dog in terms of data transfer, as it upgrades to HSPA+ -- an important bridge technology to WiMAX competitor Long Term Evolution (LTE).

T-Mobile had more good news to report today -- for the first quarter of the 2010 it will be the exclusive carrier of the new Nexus One -- a collaborative effort by Google and HTC that sports Android 2.1 and is arguably the most attractive Android handset, in terms of features, on the market.