Improved algorithms for interference suppression in non-contiguous orthogonal frequency division multiplexing-based cognitive radio systems

Abstract

Non-contiguous orthogonal frequency division multiplexing is considered as an auspicious scheme for the cognitive radio (CR) systems. It has the abilities such as spectral efficiency, multiple path delay spread and robustness against channel fading. However, due to its high sidelobes, it distorts the signals of the neighboring users including cognitive radio users (CRUs) as well as licensed users. In this paper, we proposed two novel metaheuristic algorithms, i.e., Cuckoo search algorithm and Firefly algorithm, to estimate the amplitudes of cancelation carriers which are used for the suppression of sidelobes. The effectiveness of the proposed algorithms is shown in single as well as the multiple CRUs environment. Simulations results in terms of power spectral density show that with the help of proposed algorithms significant reduction in sidelobes is achieved as compared with the existing methods.