Abstract
Since multimedia service is recently popularized, the demand for mobile traffic is increasing. As a method to meet such demand, femtocell network is proposed. However, as femtocell network is used by sharing frequency with macrocell network, severe interference is caused by macrocell base station and neighboring femtocell base station. Thus, dynamic channel allocation technique is proposed inside & outside country as a method to mitigate interference. The advanced study on the spectrum sensing scheme is essential to more effectively use such technique. Thus, this paper introduces cooperative spectrum sensing scheme which is studied inside & outside country and describes its result and direction of the future study.