Japan's NTT DoCoMo began testing of a new cellular data network that should ensure Tokyo remains one of the fastest places on the planet to send and receive data via cell phone. The new network is scheduled to go into operation in December this year and should initially deliver upload speeds of up to 25Mbps (bits per second) and downloads of 75Mbps. The speeds are respectively 5 and 10 times faster than NTT DoCoMo's current fastest service.

The new network is based on a technology called LTE (Long-Term Evolution), an IP-based system seen as a replacement for 3G-based HSPA (High Speed Packet Access). Its introduction will not only mean faster data transfers but could also reduce the per-byte cost of data communications.

NTT DoCoMo began building the LTE network in December last year and the tests that began on Tuesday will verify the network for speed, latency, stability of inter-cell handover and other factors important to a commercial service.

The December launch will be for a data communications service and DoCoMo plans to begin selling its first LTE-compatible handsets in 2011. Initial service will be restricted to Tokyo but 50 percent of populated areas are expected to be covered by 2014.

The network is being built with an investment of between ¥300 billion and ¥400 billion ($3.3 billion to $4.4 billion) during the first five years of the roll out, and comes with an eye on the future. Eventually NTT DoCoMo expects to offer even faster speeds via the new network. Future upgrades will push download speeds as fast as 300Mbps and upload speeds to 75Mbps.