Signal Detection Techniques Of OFDM Signal And Single Carrier Signal Based On Wavelet Transform

The use of OFDM technology already had almost 40 years of history. That the first OFDM technologies reality applies in wireless military high frequency communication chain circuit. After developing for many years, this technology's turn to get broad application in broadcasting and video frequency field. People pay more and more attention on OFDM since it's advantages such as frequency spectrum utilization ratio heigher, cost low and so on.OFDM is one of the multi-carrier modulations, it divides the channel into some quadrature sub-channels, and then the high speed data stream is transformed to parallel low speed sub-data streams, these sub-data streams are modulated to the sub-channels to transmit. OFDM has high utilization ratio of spectrum, low cost and can inheritance the study after CDMA. Thus it is very necessary to study the methods of identifying the modulation types of OFDM system, if or not correctly identify the modulation types is related to the correct or incorrect demodulation and information receiving.In this paper, the fundament and the system architecture of Orthogonal Frequency Division Multiplexing(OFDM) were discussed firstly. Secondly the basic theroy of wavelet transform. Wavelet transformation has the favorable property of time-frequency localization, Suitable for the analysis of steady signal and the non-steady signal. In this paper, wavelet transformation is used to analyze the four signals FSK, PSK, QAM and OFDM.