So far, how have customers benefitted from DOCOMO’s LTE mobile service?
The big attraction for most users is Xi’s high speed. In most areas, both outdoors and indoors, the network offers a max. 75 Mbps downlink, about 10 times faster than DOCOMO’s current 3G service supported with HSPA (7.2 Mbps downlink) and max. 25 Mbps uplink. The result? A video download requiring one minute with HSPA 3G now takes just six seconds!
LTE also offers the advantages of large volume and low latency for near-instantaneous data retrieval even in highly populated areas, enabling DOCOMO Xi customers to enjoy sophisticated cloud-based services. For online gaming, cloud resources provide the necessary data storage and processing capacity for rich, high-resolution, data-intensive content. The result is a dynamic experience that actually rivals full-blown home game consoles. Another mobile cloud service that will benefit from LTE’s superior performance is real-time auto-interpretation, which is currently on trial in Japan. DOCOMO hopes to commercialize this smart-pipe service after fiscal 2012.

LTE’s high speed, high volume and low latency enables operators such as DOCOMO to offer networks that can respond to the growing use of data-heavy smartphones and tablets. DOCOMO expects its data communication volume to increase 12-fold by March 2016. LTE, however, offers triple the bandwidth efficiency, meaning three times more customers using the same bandwidth compared to the current mainstream service, HSPA 3G. The big leap in efficiency will play a vital role in accommodating the traffic explosion by ensuring the efficient delivery and operation of high-speed data communication services.
DOCOMO’s LTE service area reached 24 percent of Japan’s population by the end of December 2011. By March 2015, the plan is to reach 98 percent of the population and raise the subscriber base to 30 million. By a year later, DOCOMO’s total capital investment in LTE will amount to 880 billion yen (11.4 billion USD).

Although LTE is expanding worldwide, the varying frequencies allocated to these networks present a challenge. (See chart below). Obviously, devices built for a certain frequency don’t work on a network using a different frequency, even though they both use the same technical standard.
As one solution, DOCOMO is encouraging overseas operators that already use 2.1 GHz for current 3G services to allot the same frequency to their next-generation LTE services. As a second solution, DOCOMO — in a unique move by a mobile operator — flexed its R&D muscle to develop a compact multi-band power amplifier that enables devices to accommodate various bandwidths. A prototype developed in May 2011 handles six frequencies between 1.5 GHz and 2.5 GHz and is smaller than conventional sets of multiple single-band power amplifiers used for the same function. Hopefully, it will not be too long before LTE customers enjoy roaming overseas with versatile multi-band devices and on the compatible networks of cooperating operators.