4G Experimental Blast off In Japan

NTT DoCoMo, Inc. announced today that it has succeeded with the 100Mbps-downlink and 20Mbps-uplink transmission experiment under an indoor environment using an experimental system for fourth-generation (4G) mobile communications.

Since April, 1998, DoCoMo has been conducting research on 4G mobile communications. In the course of this research, DoCoMo has conducted indoor trials on an experimental system that incorporates base station and mobile station equipment to evaluate key technologies in 4G packet wireless access and demonstrate its benefit by employing the implemented experimental system.

4G mobile communications system offering high-speed transmission of large-capacity data with wide coverage requires a bandwidth of approximately 100 MHz. When using a channel with such a broad bandwidth, transmission quality required can be impaired by a large number of multipaths, that is, the occurrence of secondary signals reflected off buildings, mountains and other surrounding objects.

DoCoMo's experimental 4G mobile communications system employs variable spreading factor (VSF) and orthogonal frequency code division multiplexing (OFCDM) technologies which is developed by DoCoMo to mitigate the impact of severe multipath interference, and to allow flexible and fast packet transmission in compliance with area and other communications conditions, thereby achieving a broad-bandwidth, large-capacity wireless system.

The International Telecommunication Union Radiocommunication Sector (ITU-R) is now developing vision framework for systems beyond IMT-2000, in which the 4G mobile communication is expected to be a key forming part. In Japan, the Ministry of Public Management, Home Affairs, Posts and Telecommunications (MPHPT) is taking the initiative to develop key 4G technologies by 2005 for commercial deployment scheduled around 2010.

In line with these movements, DoCoMo will continue to focus its research and development efforts, encompassing field trials, on wireless access technologies and applications that will contribute to the global standardization of 4G mobile communications.