News
Issue #2002 - 39 (October 2002)
(Updated Oct. 15, 2002)

TECHNOLOGY

DoCoMo Keeps Moving Forward -Tests 4G System In Lab 

Japan's DoCoMo announced last week that it has succeeded with a 100Mbps-downlink and 20Mbps-uplink transmission experiment under an indoor environment using an experimental system for 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.

DoCoMo has been conducting 4G research since 1998, including a joint development agreement with Hewlett Packard. The Japanese government has called for the finalization of a 4G technology standard by 2005 and implementation by 2010. The International Telecommunication Union RadioCommunication Sector (ITU-R) is also working on a successor to IMT-2000. 

Source: Cellular News 

MobileInfo Comments and Advisory:  Even though DoCoMo is under pressure to produce better financial results with its 3G effort, it is moving full steam ahead with 4G. True to Japanese tradition, it is going for the long haul.  This is purely experimental. Of course, we do not know whether DoCoMo is trying to prove whether it should be a network infrastructure provider or a service provider. Technology for 4G is still out in the air. Of course, it is through such trials that we will find out which horse to bet on. Do not rush to the race course - the race has not really begun and a few horses are just running around.  

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