This paper investigated the problem of resource allocation in an orthogonal frequency division multiplexing( OFDM) cooperative cognitive radio networks( CRN). The goal was to maximize the overall throughput with constraints on the individual power of each node and the communication rate,while the interference induced to the primary users( PUs) was kept satisfying a predefined threshold. It presented the joint subcarrier pairing,power allocation and relay selection optimal algorithms for different relay tran...