| Summary: | 碩士 === 國立交通大學 === 電子研究所 === 100 === In the thesis, we discuss the beamforming techniques in order to realize high speed, and reliable transmission for millimeter-wave 60GHz wireless personal area networks (60GHz WPANs). Based on the beam codebook in IEEE 802.15.3c, we proposed some techniques and their analyses for enhancing the beamforming performance. Firstly, the original codebooks in 802.15.3c are generated with 90 degree phase resolution in order to simplify the RF circuit design. We modified codebooks by raising phase resolution finitely and analyzed the performance of them. We discovered that using modified codebooks with fewer antennas could provide better performance than originals with more antennas. Secondly, codebooks are designed for the fixed antenna spacing. Therefore, it maybe has gain loss in different frequency band which could be approximate 3 dB loss when the beam is closed to the horizontal. We proposed a compensation method which only needs the information of the frequency of transmitted bands. After compensation, the performance of modified codebooks in different bands would be approximate to originals in the ideal band. In addition, we proposed a new beam searching process. Comparing to existing searching processes, our method needs the least number of training sequence to find the best beam pairs. Finally, we propose two beamforming schemes based on using codebooks to estimate direction of signals. In these methods, we only need to know SNR of different beam pairs and it would adjust the beam to the desired direction. By simulation results in OFDM and 60 GHz systems, the proposed schemes, which use symbol-wise beamforming with the lowest complexity, could provide similar performance to the hybrid beamforming, which has more complexity, and even have better performance under some conditions.
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