In Yokosuka at the end of December 2006, Japanese NTT DoCoMo's 4G technology trials yielded a result of 5Gbps transmission downlink packets to a mobile station moving at 10 kilometers per hour. Utilizing VSF-Spread OFDM (Variable Spreading Factor - Spread Orthogonal Frequency Division Multiplexing) air interface and twelve antennas, NTT DoCoMo doubled not only the previous maximum speed of 2.5Gbps to 5Gbps but also the efficiency of bandwidth usage to 50bps/Hz (5Gbps/100MHz).