A Nature-Inspired Hybrid Technique for Interference Reduction in Cognitive Radio Networks

Orthogonal frequency division multiplexing, a multicarrier method, is so far the best potential candidate for the physical layer of cognitive radio system. It has the ability to efficiently utilize the spectrum holes, contiguous or non-contiguous, and accordingly make an effective use of the natural resources. On the other hand, one of the major drawbacks is its high side-lobes that result in excessive out-of-band radiation. This out-of-band radiation causes significant interference to the nearby users, including the licensed or un-licensed. Existing techniques found in the literature for the reduction of out-of-band radiation have been compared with our proposed technique. In this paper, a hybrid technique is developed to reduce the out-of-band radiation by a cancelation carrier method using nature-inspired algorithm, known as cuckoo search algorithm. It has been widely used in different fields of engineering, for solving the problem related to optimization, especially global optimization. The generalized side-lobe canceller, which is the simplest version of linearly constraint minimum variance, coverts the constraint minimization problem into an unconstraint one. Simulation results depicted that with the proposed technique, significant improvement in interference reduction is achieved.