Just as it blazed the third-generation trail, NTT DoCoMo is hedging its bet on fourth-generation wireless technology with a field trial in Yokosuka, Kanagawa prefecture, the center of its research and development. This is not the first time the carrier has unveiled its next-generation plans.
“DoCoMo has been conducting research on 4G mobile communications technology since 1998,” said the company. “In indoor experiments announced last October, DoCoMo’s 4G system demonstrated maximum information bit rates of 100 Mbps (Megabits per second) for the downlink and 20 Mbps for the uplink.”
While DoCoMo performs the trials, standards are still under deliberations by the International Telecommunication Union’s Radiocommunications sector, the same path that preceding technologies followed.
“It is risky, but this may be DoCoMo’s way to take a step forward and be a leader again,” said Michael Gillin, president of Invisible Planet, adding that the company’s FOMA service has not met with the success it intended. Rival carrier KDDI Corp. has garnered more market share with its 3G services.
The operator said the field trial will employ Variable Spreading Factor Orthogonal Frequency and Code Division Multiplexing, as well as Variable Spreading Factor Code Division Multiple Access technologies.
The Japanese carrier identified four high-speed transmission technologies it plans to examine in the trials, including:
c Effective packet transmission methods
c Adaptive modulation and channel coding scheme
c Adaptive retransmission control, and
c Adaptive beam forming based on predicted direction of arrival.
Experts have indicated that industry would have to go through the evolutionary path of 3.5-generation before arriving at 4G. In its journey to 3G, DoCoMo did not travel through 2.5-generation before rolling out its FOMA 3G services.
According to industry experts, 4G will have up to six times the present capacity and 10 times the data rate of current technology, implying that it will offer not only higher bit rates, but higher spectral efficiency, optimized Internet Protocol traffic and smaller cells with radio-frequency bandwidth of 20 megahertz and higher.
Major infrastructure vendors like Nokia Corp., Siemens AG and Motorola Inc. have been working on the technology.
