PU Adjacent Subcarriers Power Allocation for Controlling Interference of OFDM-CR Systems

Abstract Interference is the primary limiting factor of Cognitive Radio (CR) systems. This paper proposes a new power allocation idea for orthogonal frequency division multiplexing (OFDM)-based CR systems to control the interference to the licensed primary users (PUs) caused for allowing cognitive users (CUs) to use a licensed band temporarily. The idea is redistribute the power among a minimum number of PU adjacent subcarriers’. This idea has been implemented to modify two existing power loading schemes, and developed an evolutionary Genetic Algorithm (GA)-based power distribution method for maximizing CR system capacity of (i) a single PU, and (ii) multiple PUs CR paradigm under the constraint of total power budget, individual sub-channel power budget and, PU interference tolerance limit. Simulation results authenticated that the CU capacity improvement significantly depends on channel gain quality (good’ or bad’) of the PU adjacent subcarriers.