| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 99 === This thesis presents a joint time and frequency synchronization algorithm for 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) orthogonal frequency division multiplexing access (OFDMA) downlink systems. The proposed method is an initial synchronization in order to acquire the OFDM symbol timing and carrier frequency offset (CFO). The proposed method contains two parts: 1) A joint estimation of fractional CFO and OFDM symbol timing, and 2) the detection of integer CFO. In the first part, the joint timing and channel order estimation using cyclic prefix (CP) is presented. Theoretical derivation proves that, in absence of noise, the maximum peak of the cost-function appears at the correct timing and channel order. The accuracy of fractional CFO estimation might be improved by jointly utilizing the estimated timing and channel order. Second, the detection of integer CFO using the special property of Zadoff-Chu (ZC) sequences is presented before the fast Fourier transform (FFT) operation. The studies of ZC sequences are also introduced in the thesis. Comparing with the previously presented algorithms, simulation results show the improvements in mean squared error and the detection error rate performances of the proposed methods.
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