Achievable Transmission Throughput Of Cognitive Radio Network Base On Outage Constraints

ABSTRACT:Cognitive radio network (CRN) can mitigate the impending spectrum scarcity problem by utilizing their capability of accessing licensed spectrum bands opportunistically. Underlay cognitive spectrum sharing networks, typically composed of primary and secondary networks, improve the network spectrum efficiency and capacity. Based on studying on fundamental and related spectrum sensing, accessing and sharing technology of CRN, this paper will make a theoretical research on the achievable transmission throughput with outage constraints.First, the problem of analyzing the overall achievable transmission throughput in additive white gaussian noise (AWGN) channel was investigated. In Underlay spectrum sharing model, the outage probability from both the primary and secondary systems with considering of the corresponding detection threshold at the receiver was derived by using stochastic geometry. The effect of adjusting system parameters such as spatial density, transmission power ratio, outage probability constraints and detection threshold on the overall throughput in cognitive radio networks were also analyzed. The numerical results obtained by MATLAB were provided to illustrate the analysis.The results showed the optimal strategy of choosing spatial density of secondary users and power ratio to maximize the overall throughput.Then, to protect primary user communications from SU interference, modeled the interwave of Underlay and Overlay spectrum sharing schemes, introduce protection region in the space domain and derive the optimal guard distance that maximizes the spatio spectrum opportunities available to SUs based on interference temperature limit. The outage peobability and the transmission throughput of both the primary and secondary systems in Rayleigh fading channel were also obtained. The simulation results show that the proposed interwave spectrum sharing schemes and distributed channel access schemes reduce the outage probability of both the primary and secondary systems effectivly, and also can improve the network maximum throughput by adjusting cognitive system parameters.