Side Lobe Suppression of OFDM Based Cognitive Radio by Using Genetic Algorithm

The spectrum allocation policies of the Federal Communications Commission (FCC) [1] only allow spectrum access to primary users, it has been proven by various spectrum measurement campaigns that, the current spectrum usage across time and frequency is inefficient. Therefore, in order for the secondary users to access the unused portions of the licensed spectrum, the concept of “spectrum pooling” has been proposed. Efficient pooling of the radio-frequency spectrum is achieved by employing a cognitive radio (CR). A CR could be a multi-band, spectrally agile radio that employs versatile communication techniques. An outstanding candidate for CR which provides us several reasons to use is orthogonal frequency division multiplexing (OFDM) which is a combination of modulation and multiplexing.. The large side lobes resulting from the utilization of OFDM leads to high out-of-band (OOB) radiation that causes interference to the neighbor used frequency spectrum. We are proposing this adaptive optimum suppression technique for side lobe power reduction of CR signals based on a previously proposed method AST, employing a genetic algorithm (GA) approach for optimization purpose. Also we have draw BER vs. SNR after simulation. Index Terms – Cognitive Radio, OFDM, Out Of Band Radiation, Side lobe Suppression.