| Cognitive radio is increasingly widely used as an effective way to solve the problem of shortage of available spectrum resources and low spectrum utilization.In order to improve the spectrum sensing performance and the data transmission rate,this thesis applies relay collaboration technology,multi-antenna technology,single relay selection technology and full-duplex technology to different cognitive wireless networks,the specific research content is divided into two parts as follows:(1)The outage probability is studied in suggested multi-relay multi-antenna decode-and-forward(DF)cognitive networks system.Specifically,firstly,the optimal relay is selected by using the max-min relay selection scheme.Then,the outage probability of the primary user and the secondary user is analyzed,and the corresponding expressions are given.According to the simulation results,with the increase of the number of antennas of the primary user and cognitive users,the outage probability of the corresponding user decreases;after the relay selection,the outage probability of the cognitive user is lower than that of the absence of relay selection.(2)The optimal power allocation strategies are derived in proposed multi-relay multi-antenna decode-and-forward(DF)cognitive networks system with full-duplex(FD)operation.Different from traditional cognitive system and the ordinary multi-relay system,in order to improve the spectrum efficiency of the whole system,the multi-antenna relay with full-duplex operation is regarded as a cognitive user in this paper.In order to maximize the data transmission rate of the system,the optimal power allocation among multiple antennas is presented in this thesis.Finally,the power optimization strategy is verified by numerical simulation.The simulation results show that the data rate of the proposed system model works in the hybrid spectrum sharing mode is higher than that of single antenna,half duplex,overlay and underlay mode. |
PDF Full Text Request