8. An Enhanced Cooperative Spectrum Sensing Scheme Based on New Rule of Combining Evidences in Cognitive Radio

Cognitive radio (CR) is a technology that enables the solution of the spectrum scarcity problem in wireless communication and is based on the concept of opportunistic spectrum access. Spectrum sensing is an essential functionality that enables CRs to detect spectral holes and opportunistically use under-utilized frequency bands without harmfully interfering to licensed users (LU). Spectrum sensing is highly affected by fading and shadowing. To overcome this, cooperative spectrum sensing was introduced. The decision of cooperative users can be combined using centralized or decentralized method. In this paper, we propose a new rule of combining evidences of users when they are highly conflicting, because in this situation the conventional Dempster-Shafer (D-S) combination rule produces illogical results. With our proposed system, we show that the reliability of the system increases as compared to the conventional D-S theory of combination rule. The simulation results show that our proposed system outperform the conventional D-S theory of combination.