馮世邁臺灣大學:電機工程學研究所姜智浩Chiang, Chih-HaoChih-HaoChiang2010-07-012018-07-062010-07-012018-07-062009U0001-2407200917314700http://ntur.lib.ntu.edu.tw//handle/246246/188164Orthogonal frequency division multiplexing (OFDM) is an effective method to provide high bandwidth efficiency and to mitigate inter-symbol interference (ISI) in handling time dispersion of multi-path fading channels. However, one limitation of OFDM systems is that they are highly sensitive to the phase noise (PHN) caused by local oscillators (LO) which results in inter-carrier iterference (ICI). In this thesis, the basic concept of phase noise is studied including free-running oscillator and PLL synthesizer as the two popular PHN models. In our proposed method, we approximate phase noise by Fourier series. Based on the model, we propose a method to jointly estimate phase noise and channel response in time domain using pilots. The pilot is inserted in each OFDM block in order to estimate phase noise current waveform which is always changing as a random process (RP). Moreover, the proposed method is applied to Digital Video Broadcasting - Terrestrial (DVB-T) system as a broadcasting standard. It is shown by simulation results that our proposed method performs well for any channels as long as their order is not longer than cyclic prefix (CP).1 Introduction 1 PHNEffectonOFDMSystems 5.1 Introduction to OFDMSystems . . . . . . . . . . . . . . . . . . . . . 6.2 Phase Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3 PHNModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3.1 Free-running Oscillator . . . . . . . . . . . . . . . . . . . . . . 12.3.2 PLL Synthesizer . . . . . . . . . . . . . . . . . . . . . . . . . 14.4 Effects of PHN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.4.1 Effects on the Received Base-band Signal . . . . . . . . . . . . 17.4.2 Effects on the BER Performance in OFDMSystems . . . . . . 21.5 Compensation of PHN . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Review of PHN Compensation Method on OFDM Systems 27.1 Introduction to Time Domain Estimation Method Based on Interpolation 28.2 ICIRMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2.1 Introduction to ICI Reduction Scheme . . . . . . . . . . . . . 32.2.2 ICIR PHN Estimation . . . . . . . . . . . . . . . . . . . . . . 33.2.3 ICIR PHN Compensation . . . . . . . . . . . . . . . . . . . . 35 Proposed Joint Estimation Method of PHN and Channel Responsen OFDM Systems 39.1 Phase NoiseWaveformApproximation based on Fourier Series . . . . 40.1.1 Approximation Using Fourier Series in Different Order . . . . 40.1.2 Using Flipping Method to Improve Approximation Accuracy . 43.2 Time Domain Estimation based on Fourier Series Approximation . . 50.3 Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Joint Estimation of PHN and Channel Response on DVB-T System 65.1 Introduction to DVB-T System . . . . . . . . . . . . . . . . . . . . . 66.1.1 Frame Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 66.1.2 System Parameter . . . . . . . . . . . . . . . . . . . . . . . . 67.1.3 DVB-T Pilot . . . . . . . . . . . . . . . . . . . . . . . . . . . 69.2 Estimation of PHN on DVB-T . . . . . . . . . . . . . . . . . . . . . . 72 Conclusion 85ibliography 871366216 bytesapplication/pdfen-US相位雜訊通道響應phase noiseOFDMDVB-TPHNchannel responsethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/188164/1/ntu-98-R96942098-1.pdf