Interference Analysis And Outage Probability Optimization For Wireless Cognitive Relay Networks

How to reduce the interference of coexisting systems, improve the spectral efficiency; andensure cooperation among the nodes, reduce outage probability, achieve full diversity gain are keyissues to cognitive relay network research. In this paper, the method of stochastic geometry is usedto model and analyze the aggregate interference generated by cognitive users, the analysis focuseson how power distribution affects aggregate interference model; in the self-interference existing twoway relay system, inequality analysis is the approach for outage probability lower bound anddiversity gain of the system is obtained under the existence of multiple relays.First, in order to achieve the primary user network and cognitive user network coexistence, theaggregate interference generated by cognitive user must to be taken into account seriously. With theaggregate interference model established by stochastic geometry theory, this paper considers thesingle-threshold protocol and multi-threshold protocol situations, analyses the impact of differentpower distribution and compares with the lognormal model. Analysis and simulation results showthat the optimization power distribution can reduce the aggregate interference, the impact ofdifferent power distribution on aggregate interference model is different, lognormal distribution is agood approximation model to aggregate interference.Secondly, in order to ensure the reliability of two way relay system, this paper analyses outageprobability of system. Under the amplify-and-forward (AF) mode, the SNR is optimized by the aidof the relationship between the signal-to-noise ratios of the source nodes and reconcile inequality, anew system outage probability lower bound and the diversity gain in the case of multiple relays areobtained. Simulation results show that outage probability obtained by Monte Carlo simulationapproaches to a new outage probability lower bound; in the case of multi-relay selection, the systembased on maximum minimum mutual information criterion still obtains the full diversity gain andoptimizes the lower bound of outage probability.