Interference Avoidance Based on Forward Modification and Multi-step-ahead Prediction for Cognitive Radio

The main objective of spectrum sensing is to provide more spectrum access opportunities to cognitive radio users without interfering with the operations of the primary network. Hence, recent research has been focused on the interference avoidance problem. To coexist with the primary user (PU) in the same frequency band, the secondary user (SU) has to adopt strict interference control rules to avoid interference towards primary users. A scheme based on forward modification and multi-step-ahead prediction (FMFAP) for cognitive radio is proposed to modify the sensing result and predict the interference time ratio (ITR) satisfying the strict interference constraint of primary networks in order to control the ITR so that it does not exceed a predefined threshold. Theoretical analysis and simulations show that within acceptable predicting step number CR systems can modify the sensing result to detect the exact state of PU for control data transmission and achieve precise ITR control which could greatly reduce the probabilities of collisions between second users and primary users through the proposed interference avoidance scheme.