NTT DoCoMo says it managed to transmit data at 2.5Gbps to a moving vehicle in recent tests of a new wireless data technology.
The tests involved using MIMO (multiple-input multiple-output) and are part of the Japanese carrier's research into so-called fourth generation (4G) wireless technology. MIMO involves sending data using multiple antennas -- six transmission antennas in the case of the DoCoMo trial -- to increase the total throughput.
The tests involved a vehicle traveling at 20 kilometers per hour (12mph) and took place at the company's research and development center in Yokosuka, Japan, on Dec. 14 last year but were not reported until Thursday.
Last year the carrier reported it had achieved 1Gbps transmission throughput so the latest figures are a significant improvement on that result. In addition to increasing the number of antennas from four to six, the data volume per transmission was also increased from four bits to six bits, said NTT DoCoMo.
As a result the frequency spectrum efficiency, which measures how much data can be transmitted in a single Hertz of bandwidth, increased from 10 bits per second per Hertz last time to 25 bits per second per Hertz this time.