OFDM Signal Identification and Transmission Parameter Estimation for Cognitive Radio Applications

Methods for identification of orthogonal frequency division multiplexing (OFDM) signals and estimation of fundamental OFDM parameters are developed in this paper. Detected transmissions are classified as single-carrier or multi-carrier. In the case of multi-carrier transmission, OFDM symbol duration and cyclic prefix (CP) length are estimated blindly using characteristics of OFDM transmission. For estimation of symbol duration and CP length, cyclostationarity of OFDM signaling is explored by using a maximum likelihood (ML) estimator. The proposed algorithms can be used in cognitive radio for identifying various OFDM-based transmissions and for electronic surveillance to detect illegal or enemy signals.