If you too were wondering what this 4G network is, Wired wrote an interesting piece on the subject covering the essentials—yet mainly focused on U.S evolution of the network.
The principal enhancement brought by this new network is speed.
Now, the first phone that use this tech, the HTC EVO 4G, launched yesterday (June 4th) in the U.S. Remember the 4G only works with one carrier: Sprint.
