Adaptation of Cognitive Radio Network

the cognitive radio network came to solve the spectrum scarcity problem, through arrival of the unauthorized users to the unlicensed spectrum to take advantage of the unused spectrum and avoiding interference with authorized users, the objective of this paper are adaptation of CRN by book the empty spectrum for primary users and secondary users thus use the best spectrum, and use four goals in order to access the optimal system: the minimize ber, the maximize throughput, the minimize transmission power, the minimize interference, each goal represent function, and thus we get to the optimization system. after the execution of the simulator the result were obtain in terms of chart which show: the unused spectrum used by the secondary user, thus we solved problem of spectrum scarcity. And the function of maximize through put increase exponentially with decrease the BER, and the function of minimize ber increase exponentially with decrease the BER thus subcarrier N increase exponentially with increase the function of minimize ber, and subcarriers N increase exponentially with increase the function of minimize power and the function of minimize interferences.