CROSS LAYER BASED THROUGHPUT OPTIMIZATION IN COGNITIVE RADIO NETWORKS WITH EFFECTIVE CHANNEL SENSING SCHEMES

Cognitive Radio technology is a novel and effective approach to improve utilization of the precious radio spectrum. Spectrum sensing is one of the essential mechanisms for cognitive radio (CR) and various sensing techniques are used by the secondary users to scan the licensed spectrum band of the primary radio (PR) users to determine the spectrum holes. These can be intelligently used by the secondary users also referred to as CR users, for their own transmission without causing interference to the PR users. In this paper, a MAC protocol with two spectrum sensing schemes, namely Fusion based Arbitrary sensing scheme and Intelligence based sensing scheme are analyzed including the effects of interference. Rayleigh channel model for PR-PR interference and CR-PR interference is considered. An expression for the aggregate throughput of the cognitive radio network is derived for the two channel sensing schemes. The effects of interference on throughput are studied both by analysis and by simulation. It is found that interference affects the sensing efficiency which in turn affects the throughput of the cognitive radio users. Rate Adaptation techniques are further employed to enhance the cognitive radio network throughput.