馮世邁Phoong, See-May臺灣大學:電信工程學研究所黃毓炫Huang, Yu-XuanYu-XuanHuang2010-07-012018-07-052010-07-012018-07-052009U0001-2207200911242700http://ntur.lib.ntu.edu.tw//handle/246246/188293正交分頻多工系統已成功應用在許多通訊系統，但是此系統很容易受到傳送器和接收器參數的非同步影響而破壞其正交性，降低成效。此篇論文主要討論如何估測兩個參數的非同步:載波頻率位移和取樣頻率位移與通道響應估測。Orthogonal frequency division multiplexing (OFDM) systems have been widely used and standardized for broadband wireless and wired communication systems. Due to cost, package size and power consumption, direct-conversion radio frequency (RF) receivers are popularly adopted to demodulate OFDM signals recently. For siliconmplementation, The devices can suffer from various mismatches between transmitters and receivers. Unfortunately, OFDM systems areery sensitive to these distortions or synchronization errors such as Carrier frequency offset (CFO) and sampling frequency offset (SFO). These synchronization errors at the receiver lead to intolerable inter-carrier interference (ICI). Hence we must get anccurate estimation of the CFO and SFO and compensate them properly at the receiver.n this thesis, the effects of CFO and SFO on OFDM systems are first studied. We discussed that joint influence of SFO and CFO in frequency domain. Then several estimation methods of these parameters are proposed. Firstly we propose a time domain method based on Taylor expansion for joint estimation of CFO, SFO and channel response by using a repeated training sequences. Secondly wentroduce a frequency-domain method that can jointly estimate these parameters by using pilots (instead of training sequences). A low cost iterative algorithm is proposed to solve the joint estimation of SFO and CFO in the frequency domain. Simulation results show thathe performance of the proposed methods is good.1 Introduction-1 SFO and CFO for OFDM System-52.1 Introduction to OFDM System-62.2 SFO and CFO-13 2.2.1 Sampling Frequency Offset Model in OFDM Systems-14 2.2.2 Carrier Frequency Offset Model in OFDM Systems-14 2.3 Effect of SFO and CFO-15 2.3.1 SFO Effect-15 2.3.2 CFO Effect-18 2.3.3 Effect of CFO and SFO on The BER Performance in OFDM Systems-21 2.3.4 Effect of Joint CFO and SFO on BER Performance in OFDM Systems-252.4 Compensation of SFO and CFO-29 Joint Estimation of SFO, CFO and Channel Response for OFDM Systems Using Training Sequences-313.1 Joint Estimation of SFO and Channel Response Using Training Sequences-32 3.1.1 Gault''s Algorithm in The Frequency Domain-32 3.1.2 Liu''s Algorithm in The Frequency Domain-37 3.1.3 An Estimation Method in The Time Domain-37 3.1.4 Simulation Results and Comparison-423.2 Joint Estimation of CFO and Channel Response Using Training Sequences-52 3.2.1 Correlation-52 3.2.2 Simulation Results and Comparison-533.3 Joint Estimation of SFO, CFO and Channel Response Using Training Sequences -57 3.3.1 Taylor Expansion Based Estimation Method-58 3.3.2 Correlation Based Estimation Method-63 3.3.3 Simulation Results and Comparison-66 Joint Estimation of SFO and CFO for OFDM Systems Using Pilots-814.1 Joint Estimation of SFO and CFO Using Pilots-82 4.1.1 Liu''s Algorithm-82 4.1.2 Correlation Based Estimation Method-854.2 Simulation Results and Comparison-88 Conclusion-93ibliography-952362969 bytesapplication/pdfen-US正交分頻多工系統載波頻率位移取樣頻率位移通道響應OFDM SystemCarrier Frequency OffsetSampling Frequency OffsetChannel Responsethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/188293/1/ntu-98-R96942035-1.pdf