NTT DoCoMo has demonstrated a downlink transmission rate of 250 Mbps 
over a high-speed wireless network in an outdoor test of an experimental Super 3G system for mobile communications. The “Super 3G” system trial has been underway using an actual wireless environment near its R&D labs in Yokosuka, just south of Tokyo, since February. The test involves four Multiple-Input Multiple-Output (MIMO) antennas for base-station transmission and mobile-station reception in the 20MHz bandwidth, the maximum under new Super 3G standards.
DoCoMo said it is continuing to test connection handover from one base station to another, and the functionality of applications in indoor and outdoor environments.
Super 3G, which features low-latency data transmission and high spectrum efficiency, is an evolution beyond the High-Speed Downlink Packet Access (HSDPA) and High-Speed Uplink Packet Access (HSUPA) protocols of W-CDMA, an original technology for 3G packet transmissions. Super 3G, also known as Long Term Evolution (LTE), is being standardized by the 3rd Generation Partnership Project (3GPP) and core specifications have been approved already.
- In September 2007, NTT DoCoMo announced a milestone of the way to “Super 3G” wireless, also known as Long Term Evolution (LTE) in the 3rd Generation Partnership Project (3GPP) — the company has developed and successfully tested a trial large-scale-integration (LSI) chip incorporating advanced power-saving signal-processing technologies that enable the chip to work at a sufficiently low power consumption and to be made small enough to fit into forthcoming Super 3G handsets and beyond.
DoCoMo reports that its LSI achieved a transmission rate of 200Mbps with high precision over a high-speed wireless network, while power consumption did not exceed 0.1W thanks to its proprietary signal-processing technology.
The company said its LSI demodulates and separates MIMO (multiple-input multiple-output)-multiplexed OFDM (orthogonal frequency division multiplexing) signals transmitted in the 20MHz bandwidth from four antennas. Signal processing is based on MLD (maximum likelihood detection) technology that DoCoMo has originally developed for 4G wireless access. Redundant circuits have been eliminated in the experimental chip, which was made with 65 nanometer processing.
DoCoMo plans to continue to develop Super 3G and 4G technologies in combination with its LSI technology, as well as cooperate in the establishment of related international standards.