In opportunistic spectrum access and cognitive radio, the device is assumed to be operating over a very wide range of Radio Frequencies (RF). This implies that severe implementation imperfections can take place in the RF modules of the devices. One such imperfection is oscillator phase noise. In this paper, the authors study the impact and DSPbased mitigation of oscillator phase noise in OFDM-based cognitive radio link. The paper proposes an iterative receiverside DSP algorithm for joint transmitter and receiver phase noise mitigation. In the algorithm, the received signal is first detected, and the detection results combined with channel state estimate are used to form an estimate of the time-varying phase noise process.