Novel Synchronization Design for Downlink OFDMA CoMP System

• Main Authors: Yi-Hsin Lin, 林怡欣
• Other Authors: Juinn-Horng Deng
• Format: Others
• Language: en_US
• Online Access: http://ndltd.ncl.edu.tw/handle/40607337531706631177

碩士 === 元智大學 === 通訊工程學系 === 101 === Orthogonal Frequency Division Multiplexing (OFDM) is a popular technique in modern wireless communications. There are many systems adopting the OFDM technique, such as IEEE 802.11 a/g/n, IEEE 802.16, Digital Video Broadcasting, etc. Since the subcarriers in an OFDM system are mutually orthogonal in the frequency domain, so it is quite sensitive to synchronization errors. In addition, inducing inter-carrier interference to the transmitted signals, oscillation frequency offset will also have harmful effects on clock synchronization. Therefore, aiming to these two common synchronization error problems, i.e., sampling and carrier frequency offsets, a joint time and frequency domain cross correlation method is proposed in this thesis. In order to reduce the computational complexity of matrix inversion, the sub-matrix least square channel estimation skill is proposed. And focusing on the performance impact from noise and carrier/sampling frequency offset interferences, a prefix and postfix preamble design and sliding window average interferences scheme are proposed to a novel preamble insertion method to enhance the original estimator. Next, the proposed parameter estimation method is extended to the downlink OFDMA coordinated multipoint transmission/reception (CoMP) system. Moreover, a new time-offset preamble design is used for different base station OFDMA downlink. Finally, the performance of the proposed method under serious CFO and SFO scenarios with equal gain static multipath channel environment is evaluated and confirmed that it provides the accuracy parameters estimation and achieves better BER performance than the conventional systems.