NTT DoCoMo released details of a fourth-generation (4G) radio access network field trial in which it achieved a maximum packet transmission rate of approximately 5 Gbps in the downlink using 100MHz frequency bandwidth. The 5 Gbps downlink was established to a mobile station moving at 10 km/h. The field experiment took place in Yokosuka, Kanagawa Prefecture on December 25, 2006.
The result doubled the previous maximum speed of 2.5Gbps, which NTT DoCoMo achieved a year earlier, by increasing the number of MIMO transmitting and receiving antennas from six to 12 each, and by using proprietary received signal processing technology.
As compared with the December 2005 test, the frequency spectrum efficiency, or the ratio of data transmission rate to channel bandwidth, was also doubled from 25bps/Hz to 50bps/Hz (5Gbps/100MHz).
http://www.nttdocomo.com/pr/2007/001319.html
