Japanese carrier NTT DoCoMo, long known for pushing the mobile data envelope, reports that it attained 250Mbps speed in outdoor tests in February..

NTT DoCoMo already leads the world with mobile data rates available at 3.6Mbps to subscribers, expected to double next month through new enhancements.

In order to qualify as a true 3G, data rates must meet at least 2Mbps while stationary and 384Kbps when mobile. However, 4G rates are significantly higher, with current specifications calling for data rates of about 1Gbps.

Super 3G is only one of a number of solutions being developed by mobile operators working together through the 3rd Generation Partnership Project (3GPP). Called Long Term Evolution, the industry group is working hard to ensure a smooth transition to 4G.

Faster data rates open up many new possibilities for mobile communications, including improved data transfers and videoconferencing. Current systems can already support such technologies, but only in rudimentary form.

Even beyond 3G, the company is already looking to 4G services. NTT DoCoMo recently succeeded in transferring data at about 5Gbps to a receiver moving at about 10 kilometers per hour (6mph).

The company plans to release additional details of the test at next week's CTIA show in Las Vegas.