Japanese mobile operator NTT Docomo has launched its LTE mobile service. At launch, the service covers the major urban centres of Tokyo, Nagoya and Osaka, with plans to reach 70 percent of the Japanese population by March 2015. Users leaving the LTE service area are handed over to Docomo's Foma 3G networks, which serves all communities nationwide. Docomo is starting with LTE data service only for PC users and plans to introduce LTE-compatible handsets including voice service over the Foma network by March 2012. In most outdoor areas, transmission speeds are up to 37.5Mbps for the downlink and 12.5Mbps for the uplink, but in heavily used indoor areas, customers can access up to 75Mbps for the downlink, approximately ten times faster than Docomo's current 3G service with HSPA. LTE also averages about three times more data in the downlink and two to three times more in the uplink and transmission latency is just one-fourth that of HSPA. Docomo's LTE network is based on 3GPP Release 8 and operates in the frequency-division duplex (FDD) mode, which uses separate frequencies for both downlink and uplink transmissions in the 2GHz band. Over the next few years, Docomo will implement a plan to expand its LTE service. As of the end of March 2011, more than USD 400 million will have been invested on a network covering about 1,000 base stations and serving about seven percent of the population. By March 2013, Docomo plans to have spent in excess of USD 3.6 billion on a network encompassing some 15,000 base stations and serving 40 percent of the population. It is expected that a quarter of the company's subscribers or 15 million people will have migrated to LTE by March 2015.
