Abstract

In order to optimize power allocation, Orthogonal frequency division multiplexing (OFDM) based cognitive radio (CR) network allows flexible spectrum and adaptive capability. Decreased capacity due to subcarrier cancelation and out of band reduction can be compensated while employing multiple inputs and multiple outputs (MIMO) along with OFDM based CR. MIMO allows better beam forming and directivity due to multiple transmit and receive antenna. Here we have implemented water filling mechanism with channel state information (CSI) for optimal power allocation under hybrid spectrum sharing scenario such as overlay, underlay and interweave. Main objective is to maximize overall capacity of cognitive radio network in downlink while considering interference constraint imposed by primary user and maximum transmit power constraint at secondary user. Simulation results demonstrate waterfilling approach for hybrid scenario in MIMO-OFDM based CRN.