Research On Blind Identification Algorithm Of OFDM Signal

The technology of communication signal modulation identification plays an important role in the field of electronic war and defined radio management etc., and increasing attention has been paid on it in the field of non-cooperative communications in the recent years.With the development of wireless communication, the OFDM technology is widely used in many communication systems because of its high spectrum efficiency and strong ability of against multipath fading. But the blind recognition of OFDM signals is not mature, so it is of great significance to study it.This paper first introduces the basic principles of OFDM technology and the model of OFDM system identification, analyzes the advantages and disadvantages of OFDM technology. Then it focus on the OFDM signal modulation recognition and OFDM parameters estimation under the Gauss channel. OFDM modulation recognition is divided into two parts, one is the recognition of OFDM and single-carrier signal, this part uses a combined recognition method of Higher-order Statistics and power spectrum; the second is recognition of OFDM signal in multicarrier signals, this part uses the variance coefficient of the multicarrier signal’s spectral envelope and the cyclic prefix to the recognize OFDM signal. The estimation of the OFDM system parameters is divided into three aspects, one is using the cyclic prefix to estimate the effective length of the OFDM symbol; the second is based on the estimation of bandwidth and over sampling methods to estimate the number of sub carrier of OFDM signal; the third takes advantages of the periodic feature of OFDM signal’s brought by cyclic auto-correlation to estimate the total length of OFDM symbol.