Nowadays OFDM (Orthogonal Frequency Division Multiplexing) techniques are adopted by many existing or progressing wireless communication standards. OFDM’s sensing and spectrum shaping capabilities together with its flexibility and adaptivity make it the best transmission technology for CR system. Spectrum sensing helps to detect the spectrum holes (unutilized bands of the spectrum) providing high spectral resolution capability. Thus, a robust spectrum sensing algorithm for OFDM modulated signals is highly decide to implement CR when the primary signal uses OFDM modulation. Motivated by this demand, a Time-Domain Symbol Cross-correlation based spectrum sensing algorithm (TDSC method) is presented in this paper. The algorithm makes use of the property that the mean of the TDSC of two OFDM symbols is not zero if they have embedded the same frequency-domain pilot tones. We propose a new decision statistic for the signal detection based on the special feature –Cyclic Prefix embedded in OFDM signal. Further, in this paper we used to control the Transmit Power for cognitive radio. Different spectrum sensing techniques for OFDM based cognitive radio are discussed in this paper.Keywords: Cognative Radio, OFDM, Spectrum Sensing, Energy Detection, Matched Filter, Cyclostationary Feature Detection
