Implementation of PFD based spectrum sensing method in applications of Cognitive Radio

摘要

Rapid, accurate and efficient SS is of vital elements in CR technology. Emerging broadband wireless applications have demanded extraordinary increase in radio spectrum resources. As a result, we had been going through a critical spectrum shortage problem. However, numerous recent measurements reveal very low spectrum utilization in most beneficial frequency bands. Cognitive radio generation is a promising generation that can essentially enhance the spectrum usage of licensed frequency bands through secondary spectrum access. Spectrum scarcity is a big and vital problem in wireless communication system nowadays. Defining and designing new applications, developing users and their needs, especially the fixed spectrum allocation policy / strategies have made the problems more serious. The spectrum sensing problem has gained new dimensions with cognitive radio and opportunistic or dynamic spectrum access ideas. To overcome this we investigated a method of frequency sensing which is based on frequency comparison using a phase frequency detector (PFD). In this method output of PFD is used to sense the spectrum without any information of incoming or received signal, channel parameters or noise.