Capacity Analysis On Aggregate Interference Of Cognitive Radio Networks Based On Stochastic Geometry

Cognitive radio technology has been considered as the best solution to improve the spectrum efficiency since it was proposed. Interference is an important aspect in the study of cognitive radio technology. This paper focuses on the transmission capacity with aggregate interference which employs a stochastic geometry model in cognitive radio networks.Firstly, this paper introduces a cooperative transmission scheme in an overlaid wireless network where a primary (PR) users network and a secondary (SR) users network coexist together. In this scheme, the PR users employ DAF scheme, whereas the CR users transmit directly. The outage probability and capacity of the PR users are analyzed with the consideration of aggregate interference compared with the traditional non-cooperative transmission scheme. Simulation results show that the use of cooperative transmission achieves much lower outage probability and a larger capacity than the direct transmission. Furthermore, such performance gain can be manipulated to increase the transmission capacity of the SR network without deteriorating the performance of the PR network. In addition,numerical results demonstrate that AF cooperation scheme is better than DAF in terms of outage probability and system implementation in the non-fading channel.Meanwhile, this paper studies the relationship between the transmission capacities of the coexisting wireless network and the outage probability of the PR users in Rayleigh fading channel with outage constraints. During the analysis, interference to the PR user which is generated both by the SR users and the PR user itself are considered. Numerical results show that if the PR network permits a small increase of its outage probability, the total transmission capacity of the coexisting network will be boosted significantly. Different from the previous approach for single network, this paper obtains asymptotic tradeoff of the transmission capacities for these two networks. Compared to the non-fading channel, this study which is based on the Rayleigh fading channel is more close to the actual channel environment and has a better practical sense.In summary, this paper has a certain theoretical significance and reference value for the study of aggregate interference, spectrum efficiency and transmission capacity.