Tokyo 250Mbps mobile supernetwork speeds into life

Did you see it? There it goes again....

Japan's largest operator has built a mobile network offering massive download speeds of 250Mbps.

NTTDoCoMo's network near Tokyo is only a test, but the operator expects to complete development of the technology next year. Commercial networks could follow soon after. It's pushing technical standards to the limit in magicking out the 250Mbps speed, although it claims speeds could in theory reach 300Mbps. Upstream data can be transmitted on the network at up to 75Mbps.

The network is based on long-term evolution (LTE), an enhancement of 3G and HSDPA which is using four multiple-input multiple-output (MIMO) antennae. It's a lot faster than current networks - HSDPA offers just 14Mbps downstream while 3G provides a mere 384Kbps. Both those figures are theoretical speeds - actual experiences have been far slower.

3G is available across the majority of the UK, but HSDPA is still much more limited.

As well as providing extra bandwidth, LTE has other benefits. It should provide less delay than 3G and it's more spectrally efficient, meaning it'll save operators like NTT a yen or two. It also works over both 2G and 3G frequencies.

Before it's released commercially, a range of issues have to be tested, including the ability of users to roam between base stations without losing the call.

NTT plans to give more details of its network to the Americans at a trade show on 1 April. It has dubbed LTE as both "Super 3G" and 3.9G - which looks set to cause confusion, as HSDPA has also been called Super 3G. ®

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