Past Research

これまでの研究
Past Research

Utilization of Unused Frequency Bands

Rapid increase of mobile data traffic by smart phones necessitates more effective utilization of frequency resources, which can be attained by the technology of "Wideband Non-Contiguous OFDM (WNC-OFDM)". WNC-OFDM thoroughly gathers unused resources dispersed in frequency domain by placing radio signals of OFDM onto the fragmented frequency bands that are not used by other wireless systems at certain places and times.

nco_en_201405


This research was performed under research contract of “Research and Development on Wideband Non-Contiguous OFDM”, for the Ministry of Internal Affairs and Communications, Japan.

Effective and Precise Estimation of Unused Frequency Bands

Utilization status of frequency bands changes over time and from place to place. We can obtain exact status of frequency bands by putting a huge number of sensors to all locations with enormous costs. To reduce costs, we are studying "Local White Space Estimation utilising Heterogeneous Types of Sensors". Unused frequency bands are precisely estimated with a few types of sensors and radio propagation estimation.

microws_en_201405


This research was performed under research contract of “Research and Development on Technology to Accelerate Effective Utilization of Local White Space using Radio Environment Big Data”, for Strategic Information and Communications R&D Promotion Programme of the Ministry of Internal Affairs and Communications, Japan.

Wake-Up of Wireless Communication Devices on Demand

Most of wireless LAN access points in home and office consume electric power always because they are set to always-on. If they can sleep when they are not used, power consumption will be reduced. We are studying "Wake-up receivers" which can turn on wireless communication devices on demand.

rod-san_en_201405


This research was performed for Strategic Information and Communications R&D Promotion Programme of the Ministry of Internal Affairs and Communications, Japan.

Cooperative Relative Positioning Method for Cars

For preventing traffic accidents, it is very important to grasp relative position between cars. However, popularly used GPS has a non-correlated error of absolute position in urban areas because of effect of large buildings and reflection signals from them. We are studying "Cooperative Relative Positioning Method for Cars" technology. It can obtain relative position between cars in urban areas by only using highly correlated GPS signals that are shared between cars.

copos_en_201405


This research was performed for Strategic Information and Communications R&D Promotion Programme of the Ministry of Internal Affairs and Communications, Japan.