In its latest self-described 4G trial, NTT DoCoMo has delivered 5 Gbps of downlink data to a terminal on the move. The trial, on Christmas Day last year, doubled the data throughput achieved 12 months previously in a similar trial.
The experiment used a whopping 100-MHz channel, however. Today's 2G or 3G carriers typically operate in 10-MHz or 15-MHz paired frequencies.
DoCoMo said it had achieved the faster bandwidth by doubling the number of MIMO transmit and receive antennas to 12, and by using proprietary received signal processing technology.
Spectrum efficiency had also doubled, from 25 bps/Hz to 50 bps/Hz (5 Gbps/100MHz), DoCoMo said.
Company executives will present more details of the experiment at 3GSM this week.