Outage probability based unified framework for always transmit solution in cognitive radio systems

Cognitive radio is a promising technology that uses radio spectrum opportunely and efficiently. In this paper, we propose a unified framework for enhancing the cognitive sources data transmission to provide “Always Transmit” solution using mixed strategies in cognitive radio context. Indeed, we propose to combine underlay and interweave approaches depending on the activity of primary system and taking into account secondary user QoS. We analyze the outage probability of cognitive transmission under joint transmission power constraint and interference power constraint over Rayleigh fading channels. This framework accounts for all the parameters that affect the performance and provides fundamental insights that may be of value to the transmission scenario, such as the spectrum sensing duration, spectrum hole detection, primary system bandwidth occupancy, transmission and interference power constraints.