Pwam: Penalty-based Weight Adjustment Mechanism for Cooperative Spectrum Sensing in Centralized Cognitive Radio Networks

Current static spectrum assignment policy leads to the shortage of the spectrum for launching newer telecom cooperation or enhancing the existing ones. To address this issue of inefficient spectrum utilization, a new term Dynamic Spectrum Access has emerged. Cognitive Radio is the most decisive technology for the successful deployment of Dynamic Spectrum Access. Spectrum sensing plays a vital role for cognitive radio to avoid interference with primary users by identifying unused portion of the spectrum. In practice, sensing is severely degraded by multipath fading and shadowing effects. To mitigate these impacts cooperative spectrum sensing is the most familiar technique. Cooperative spectrum sensing exploits spatial diversity by sharing sensing information among cognitive radios at the cost of additional bandwidth consumption and reporting time. This paper presents a fast convergent and adaptively adjusted weighted cooperative spectrum sensing scheme for centralized cooperative spectrum sensing scheme. In our method, the weight factor values are updated according to the cognitive users’ performance history. Then, the weight factor is adjusted using a penalty mechanism based on current local decision made by secondary user. The final result is then computed by fusion of weighted soft decisions made by each cooperating secondary user. Simulation results show significant decrease in probability of error.