NTT DoCoMo has embarked on a month-long test of a Super 3G (third-generation) cellular system that aims to deliver 300Mbit/s downloads.

The indoor experiment will test data-transmission speeds. The first trials will involve the use of a single antenna on both the transmitter and receiver, and later use of up to four MIMO (multiple-input multiple-output) antennas. The tests will also look at the speed with which communications can be handed over from one base station to another.

Super 3G, which is also known by the acronym LTE (long-term evolution), uses the same radio spectrum band as current 3G services, but that's one of the few similarities. Super 3G allows for a number of different bandwidth channels and uses different modulation systems to transmit the data. It is envisaged to eventually allow data links at 80M bit/s to the network and 300M bit/s from the network.

NTT DoCoMo, Japan's largest cellular carrier, has been working on Super 3G for some time and anticipates introducing the technology in Japan sometime around 2009, as a stepping stone between current so-called 3.5G technology and future 4G (fourth-generation) systems.

The company has also been aggressively pursuing 4G system development. In late December the carrier came close to hitting a 5 Gbit/s data transmission speed from an experimental 4G system to a receiver moving at 10 kilometers per hour.