Blind Identification And Parameter Estimation Techniques For OFDM Signal

The accurate and high-speed transmission of information Continue to promotethe advancement of communication technology.As the new generation ofmodulated transmission technology, increasing attention has been paid on OFDM.The continued improvement of cooperative communication technology madenon-cooperative reception of OFDM signal become a research focus.A complete technical project about non-cooperative reception of OFDM signalworked on Gaussian channel is provided in the thesis.The project can achieve theblind recognition and blind demodulation of the common OFDM signal,includingblind recognition of OFDM,estimation of OFDM signal system parameters,estimation of OFDM synchronization parameters, blind demodulation of OFDMsignal. After the depth theoretical study of parameters estimation in thisproject,new algorithms are proposed in the thesis.The main work of this paper canbe summarized as the following:1．Blind recognition of OFDM.The paper firstly focuses on the researchmeaning of non-cooperative reception of OFDM signal,then a new blindidentification algorithm using the OFDM signal Gauss characteristics and cycleprefix characteristics is summarized in this paper.which is based on the detailedanalysis of the type of modulation and signal structure of OFDM signal.2．Estimation of OFDM system parameters.Some parameters,including theeffective length of symbol,the length of cycle prefix of symbol,the number of validsubcarrier and the total number of subcarriers,are estimated in this part.A kurtosismethod using the correlation of CP data and kurtosis factor is proposed to estimatesymbol timing position and the length of the CP in this paper,which not only canrealize blind parameter estimation with high accuracy,but also the performance ofblind parameter estimation keep the same in burst communication.A newbandwidth estimation method is used to estimate the number of valid subcarrierbased on the relation between the bandwidth and the number of the validsubcarrier.The improved bandwidth estimation performance promotes the effect of the valid carrier number estimation.3．Estimation of OFDM synchronization parameters.Timing synchronizationand carrier frequency synchronization are completed in this part.The OFDM signalmodel and the array signal model are compared firstly,Then several estimationalgorithm of frequency deviation are analyzed and compared.The kurtosis methodis used to accomplish the timing synchronization.4．Blind demodulation of OFDM signal.The performance of blind receivingsystem of OFDM is carried out at the end of this paper.After that,the performace ofeach part of the system is also tested and summarized.