Study Of Intelligent Receiver Technology For OFDM In Multi-system Communication

Intelligent receiver technology for OFDM(Orthogonal Frequency Division Multiplexing) is well studied in this paper. First, a model of intelligent receiver for OFDM based on Software Defined Radio(SDR) is proposed, which could automatically identify OFDM and estimate the parameters. Then, the baud rate estimation, OFDM identification and OFDM parameter estimation are studied, which are all related to the intelligent receiver for OFDM. For the baud rate estimation, since related studies show that no existing algorithm is suitable for both OFDM and single-carrier signal, we propose a new algorithm based on FFT and Haar wavelet decomposition in this paper, which can deal with baud rate estimation no mater the signal is OFDM or single-carrier. For the identification of OFDM signal, we propose an algorithm based on feature extraction from multilevel wavelet decomposition, which overcomes the shortcomings of the algorithm based on cumulant that it can’t identify OFDM with high-level square-QAM. After that, we introduce an algorithm for OFDM parameter estimation based on ML, which could estimate the FFT length, CP length and the beginning position of OFDM symbol. At last, we give a strategy combined the cumulant and clustering for OFDM sub-carrier modulation identification, which can identify the modulation type of OFDM sub-carriers with BPSK, QPSK, square-16 QAM and square-64 QAM.