Novel scheme for interference avoidance in cognitive radio based cellular networks

The cognitive radio (CR) technology is believed to improve the spectrum efficiency. However, the interference problem has become a critical issue due to the coexistence of primary systems and CR systems. In this paper, the interferences in CR based cellular networks are discussed. Interference scenarios are analyzed, considering different interference sources. Meanwhile, an improved model named ‘Cognitive Interference Ring’ is introduced to describe the interference range of each secondary user (SU). Depending on the above analysis, graph coloring based dynamic power allocation (GCDPA) scheme is proposed for interference avoidance. Simulation results demonstrate that in CR based cellular networks, the interferences to primary users (PUs) can be effectively mitigated with the proposed GCDPA scheme, and the system throughput and power efficiency are both improved.