Research and development on cognitive and software radio technologies - Devices and hardware platform -

Currently, a number of wireless access systems have been available to users. Especially, several new systems can be used on not only 800-6000MHz band that is suitable for cellular communications and broadband wireless access systems but also the lower frequency band such as VHF and UHF bands. This means that most frequency bands adequate for mobile communication systems are fully occupied after around ten years and new solutions are needed. One of solutions is to use "Cognitive Radio/Dynamic Spectrum Access" technology [1] that is a radio or system that senses, and is aware of, its operational environment and can dynamically and autonomously adjust its radio operating parameters accordingly by collaborating wireless and wired networks [2]. This technology is expected as a key technology to obtain a new available spectrum on the conventional frequency band. To realize the technology, National Institute of Information and Communications Technology (NICT) established a project supported by Ministry of Internal Affairs and Communications (MIC) to research and develop enabling technologies for the cognitive radio/dynamic spectrum access equipments in 2005. As a representative result of the project, a software defined cognitive radio (SDCR) equipment that consists of a hardware platform (HWP) and a software platform (SWP) has been developed [2]-[4]. Especially HWP is very important to realize SDCR equipment and the HWP must be programmed by software and needs to include multiband and tunable devices such as bandpass filter, amplifier, and mixer in order to reduce the size of radio equipment. This paper describes two research and development results on a SDCR equipment. One is to develop multiband/tunable devices such as bandpass filter, amplifier, and broadband direct upand down-conversion mixer over 400MHz-6GHz band for software defined radio. Another is to develop hardware platforms, especially radio frequency unit (RFU) for software defined radio.