An interference avoidance scheme for orthogonally multiplexed cognitive radio systems

An interference avoidance scheme is proposed for orthogonally multiplexed cognitive radio (CR) systems. The CR systems are based on filter bank modulation (FBM) with special filter bank structures, i.e., some of the filter bank tree leafs are virtual or not modulated by the transmitted data. This kind of structure is capable of creating holes in the transmitted signal spectrum which can be used to avoid interference. By changing the tree structure of the filter banks such as the tree depth, the number of the virtual leafs, and the location of the virtual leafs, the number and the location of the spectral holes are also variable. In the simulation tests, primary users are modeled as partial band interference (PBI) located in individual spectral bands. It is shown that the proposed scheme is capable of avoiding various kind of PBI.