ASIA
Japan : NTT DoCoMo, Inc. announced today that it achieved 2.5Gbps packet
transmission in the downlink while moving at 20km/h. The fourth-generation
(4G) radio access field experiment took place in Yokosuka, Kanagawa
Prefecture on December 14, 2005.
DoCoMo achieved a maximum
1Gbps speed in a similar field experiment on May 9, 2005. This time,
by increasing the number of MIMO*1 transmission antennas from four
to six and by using 64-QAM*2, data volume per transmission was increased
from four bits to six bits. As a result, DoCoMo achieved a maximum
speed of 2.5Gbps, which is faster than the International Telecommunication
Union Radiocommunication Sector (ITU-R)'s proposed standard.
Frequency spectrum efficiency*3,
which is expressed as information bits per second per Hertz, was also
increased from 10 bits per second per Hertz during the last experiment
to 25 bits. This figure is the maximum frequency spectrum efficiency
for 4G as defined by WINNER*4.
Building on the success
of the field trials, DoCoMo will continue its research and development
in order to actively contribute to the global standardization of 4G.
Notes
MIMO: Multiple-Input Multiple-Output. Data transmission scheme to
increase the achievable data rate, in which different data streams
are spatially multiplexed using multiple transmitter and receiver
antennas on the same frequency.
QAM: Quadrature Amplitude Modulation. Modulation scheme which conveys
data by changing the amplitude and phase. For example, 64QAM transmits
one of 64 signal points and conveys six bits per one symbol.
Spectral efficiency: Defined by the ratio between the transmission
data rate and the channel bandwidth. The spectral efficiency of this
experiment is 2.5Gbps/100MHz=25bps/Hz.
WINNER: Wireless world INitiative NEw Radio. WINNER is a EU research
project started in January 2004. This project aims to develop a ubiquitous
radio system concept based on global requirements for mobile communication
systems beyond 3G.