NTT DOCOMO is preparing to push its LTE service to 150 Mbps maximum downlink rates, roughly double today's top performance. The 150 Mbps service is currently being verified in Kawasaki, Kanagawa Prefecture.
NTT DOCOMO expects to launch 150 Mbps commercial service this October, starting in parts of Tokyo, Osaka and Nagoya.
DOCOMO, in addition to steadily improving the quality of its LTE network for increased reliability, continues to upgrade LTE coverage and data transmission speeds, most recently by expanding 112.5 Mbps downlink service to more than 130 cities as of this month.
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In June, NTT DOCOMO plans to increase its number of LTE base stations from 24,400 (March 31, 2013) to 50,000 by March 31, 2014.
As part of this effort, NTT DOCOMO introduced a new compact LTE base station with simultaneous 3G capability, measuring less than 1/10th the size and less than 1/5th the weight of conventional LTE base stations. The first units entered commercial operation in DOCOMO's Xi LTE and FOMA 3G networks in Japan this month.
The compact all-weather base station, which is mainly designed for area expansion in low-traffic areas such as mountainous locations, can be installed in places where conventional LTE base stations cannot be deployed due to excess size or cost.
The new base station, equivalent to the master station of a remote-type base station, can handle up to two secondary stations. Furthermore, thanks to the new base station's 3G W-CDMA capability, simultaneous LTE and 3G service areas can be tailored efficiently to traffic and installation conditions by using secondary stations and multiple frequency bands. Electricity consumption is less than 1/4th that of conventional LTE base stations, realizing more eco-friendly operation.
In February, NEC confirmed that NTT Docomo has selected it to develop LTE-Advanced base stations for its new C-RAN architecture.
NTT Docomo is proposing a new Advanced C-RAN architecture that uses small "add-on" cells for localized coverage that act in concert with macro cells in HetNet fashion. Deep integration is achieved using carrier aggregation technology, one of the main LTE-Advanced technologies standardized by 3GPP.
Under the Advanced C-RAN architecture, high-capacity base stations utilizing advanced C-RAN architecture will serve as master base stations both for multiple macro cells covering broad areas and for add-on cells in smaller, high-traffic areas. The base stations will accommodate up to 48 macro and add-on cells at launch and even more later. Carrier aggregation will be supported for cells served by the same base station, enabling the flexible deployment of add-on cells. In addition, maximum downlink throughput will be extendible to 3Gbps, as specified by 3GPP standards.
Carrier aggregation is expected to yield 3 Gbps maximum throughput by aggregating multiple carriers of up to 100 MHz of carrier bandwidth.
