NTT DoCoMo has successfully tested 1Gbit/s transmission speeds using 4G mobile technology outside, the company announced yesterday.

In experiments conducted in May, the technology worked at up to 400 metres, according to a DoCoMo spokeswoman.

The company had previously demonstrated 1Gbit/s transmission with an earlier version of the same technology last August, but only in a lab. The company's current 3G network offers download and upload speeds up to 384Kbit/s, and DoCoMo won't build a 4G network until around 2010.

Before then, the company will also be increasing the speed of its 3G network. From April, it will introduce HSDPA (High Speed Downlink Packet Access), boosting the system to 14Mbit/s, although the faster network will only be available in major cities initially, the company said.

By the end of 2007, DoCoMo will also have decided the technical specifications for an even faster technology called Super 3G, Nakajima said. This will offer up to 100Mbit/s downlink and 50Mbit/s uplink speeds. That network should be operational between 2008 and 2010, the company said.