NTT DoCoMo performs 4G trials0
The Japanese mobile network operator NTT DoCoMo, Inc, has not launched any 3G upgrades such as HSPDA yet, but is already working on 4G network. It even announced the achievement of 2.5Gbps download speed, while moving at 20km/h in tests on the 4G network speeds. The new DoCoMo's network is based on modified proposed standards. To achieve this high data rate, which is faster than the International Telecommunication Union (ITU) proposed standard, NTT DoCoMo, Inc uses 6 simultaneous transmissions with 6 antennas and an advanced encoding algorithm. They also managed to increase the frequency spectrum efficiency from 10 bits per second per Hertz during their last experiment, when 1Gbps speed was achieved, to 25 bits.
Source: NTT DoCoMo