9/6/2002 - Fujitsu Limited and Fujitsu Laboratories Ltd. announced that they have developed and successfully implemented highly efficient transmitting power amplification technology that also compensates for signal distortion in IMT-2000 (*1) third-generation wireless communications systems. Fujitsu has incorporated this technology in an LSI and used the chip to develop the world's most compact, energy-efficient transmitter amplifier for IMT-2000 base station systems.
Details of the new technology will be presented at a conference of the Institute of Electronics, Information, and Communication Engineers on September 13 at Miyazaki University in Japan.
Faster Internet connectivity and data transmission speeds are increasingly important requirements for mobile communications. Third-generation systems using code division multiple access (CDMA) technology (*2) have been developed to meet these requirements for greater flexibility and speed. One implementation of CDMA, called W-CDMA, was adopted by NTT DoCoMo, Inc. for its "FOMA" service, which became commercially available in October 2001.
Transmitter amplifiers for IMT-2000 systems, which use CDMA technology, must provide good linearity and low distortion in amplifying broadband signals with high dynamic range, as well as high power efficiency (*3) to keep energy consumption low. Generally, these two requirements have been mutually exclusive, so there has been growing need for distortion compensation technology that could amplify signals while minimizing distortion and power consumption.
Today, transmitter amplifiers for wireless base stations use an analog feedforward technology to compensate for distortion. However, since this technology's power efficiency is already approaching its theoretical limit, there has been a need to develop a new approach to distortion compensation technology.
About Fujitsu's New Technology
Fujitsu's new distortion compensation technology is based on the digital pre-distortion (DPD) method, which adds compensatory characteristics to the signal before distortion occurs. Fujitsu has incorporated this technology into a distortion-compensation LSI, and, using this chip, has developed a high-efficiency transmitter amplifier.
In tests, the new amplifier satisfied all IMT-2000 system wireless specification requirements, and achieved roughly double the power efficiency of conventional feedforward amplifiers, thus achieving significant improvements of efficiency and compactness in a transmitter amplifier.
Some of the key features of the new technology are as follows:
International Mobile Telecommunications 2000 is the ITU globally coordinated definition of 3G covering key issues such as frequency spectrum use and technical standards.
*2. CDMA technology
Short for code division multiple access, this is a communications access technology that multiplexes and separates multiple users communicating at the same time by using spreading codes. Because multiple users are communicating at the same time on the same frequency, it has the advantage of making good use of available frequencies.
*3. Power efficiency
The ratio of the energy in the radio signal put out by a transmitter amplifier to the power consumed by it. The higher the ratio, the less power used to amplify signals.
*4 Evolium SAS
A joint venture between Fujitsu and Alcatel.
FOMA is a registered trademark of NTT DoCoMo, Inc.
About Fujitsu (www.fujitsu.com)
Fujitsu is a leading provider of customer-focused IT and communications solutions for the global marketplace. Pace-setting technologies, high-reliability/performance computing and telecommunications platforms, and a worldwide corps of systems and services experts make Fujitsu uniquely positioned to unleash the infinite possibilities of the broadband Internet to help its customers succeed. Headquartered in Tokyo, Fujitsu Limited (TSE:6702) reported consolidated revenues of 5 trillion yen (about US$38 billion) for the fiscal year ended March 31, 2002.
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