Effects of primary users´ position uncertainty on down-link transmission in location based OFDMA cognitive radio networks

Channel state information(CSI) was applied in resource allocation to decide the interference relationship among primary and secondary users in OFDMA based cognitive radio networks. The CSI among the secondary users are easy to collect by exchanging transmitting and received signal power. However, it is not reasonable to require the CSI between secondary users and primary users since primary users should not send feedbacks to secondary users. Location information has also been used to describe the interference relationship. In this method, primary users´ position can be collected by received signal strength based localization approach. Therefore, localization error always exists in localization methods and has not been considered in resource allocation problems. In this paper, we formulate the primary user´s position uncertainty as a perturbation. A robust optimization algorithm is proposed for this perturbed problem. Simulation results show the performance of the proposed algorithm.