Interference effect evaluation of cognitive radio by using statistical method

Cognitive Radio (CR) has become one of the most popular communication skills around the world. One advantage of CR is efficient utilization of the radio spectrum. A cognitive radio would be designed to dynamically adapt its transmissions to find and utilize frequencies while minimizing interference. Therefore, care must be taken to protect legacy (primary) users, while secondary users are using the frequency bands which have been allocated for primary users. So research of secondary transmitters interference effect on privacy receivers is an important issue in the development of Cognitive Radio. This paper presents an efficient method to evaluate interference effect on primary receiver. The statistical measuring method has been proved to be an effective method to study the characteristics of electromagnetic interference and it is an open issue to study the interference effect on digital communication systems by using these statistical characteristics. This paper studies the relation between the secondary interference´s amplitude probability distribution (APD) and bit error probability (BEP) of primary digital communication systems. At last we report the measuring APD results of WLAN devices in use and the relationship between these results and BEP of Bluetooth systems.