Non Line-of-Sight Transmission in 60 GHz OFDM Systems： Hybrid Beamforming and Full-Duplex Relaying

• Main Authors: Liu, Yen-Ting, 劉彥廷
• Other Authors: Wu, Wen-Wrong
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/m938wb

碩士 === 國立交通大學 === 電信工程研究所 === 101 === IEEE 802.15.3c system offers data rates of multiple Gbit/s for applications such as high speed internet access or high quality video streaming. However, it is operated in unlicensed 60GHz band, the propagation loss is high and signal penetration is low. Thus, 60GHz transceivers require high transmission power, and can only be properly operated in LOS environments. This thesis aims to develop LOS/NLOS transmission technologies for 60GHz systems. To solve the problem, we use a hybrid planar antenna array conducting beamforming. First, based on the codebook in IEEE 802.15.3c, we propose a new beam matching method which can find the best transmit and receive beamforming pair quickly. The method is also extended such that it is able to find the beamforming pair shortly after the environment changes from LOS to NLOS. Then, we propose another method, using full-duplex relays, to solve the NLOS problem. In a full-duplex relay, transmitted signal will interfere its received signal, a phenomenon called echo. We then design an echo canceller to suppress echo signal without affecting the original antenna pattern. It is shown that the echo is effectively canceled.