earticle

영어

Enormous growth of wireless applications makes the spectrum scarcity problem worse day by day. Moreover, traditional fixed spectrum assignment policy causes serious spectrum underutilization problem. However, Cognitive Radio that enables opportunity based spectrum access for unlicensed users has recently been recognized as a heartening solution for spectrum scarcity and underutilization problem. Medium access control protocol is the key enabler or coordinator for this opportunity based channel access. However, recent studies show that in distributed cognitive radio networks MAC protocol suffers from severe performance degradation due to common control channel selection (CCC) problem, the multichannel hidden terminal problem (MHTP). In this paper, we propose a MAC protocol that eliminates CCC selection problem. Here, unlicensed users use dedicated band owned by them as a common control channel. Every unlicensed user equipped with two transceivers. One is control radio that helps SU’s to get updated control information and other is data radio. This clearly cuts down the number of collisions with other secondary and primary users in data transmission phase. To obtain the accurate sensing result, we propose cooperative sensing for idle channel detection. In this paper, we develop an analytical model to analyze important performance metrics. Simulation results show the effectiveness of our system.