Research On Power Allocation Of Non-Orthogonal Multiple Access In Cognitive Radio Network

With the development of mobile communication,a large number of mobile terminals are put into use,wireless spectrum resources are getting increasingly nervous.However,spectrum resources are the core resources for promoting industrial development in the field of mobile communicationsand.At the same time,spectrum resources are the basis of the wireless communication.Both non-orthogonal multiple access technology and cognitive radio technology can improve spectral efficiency and user's transmission rate effectively in the system.Aiming at the problem of low user's transmission rate in the edge region in the traditional NOMA-based cognitive radio network,a non-orthogonal multiple access based relay cooperative transmission system is proposed.Based on the limited power of the cognitive base station,the solution targets the "secondary-user's throughput" and deploys the amplify-and-forward relay to use non-orthogonal multiple access to broadcast user information.The characteristics adaptively adjust the power allocation factor.The relay can adjust the power allocation factor based on characteristics between channels adaptively.Simulation experiments show that,the proposed scheme can maximize the user's throughput in the system under the premise of ensuring the communication quality of edge users.Aiming at the problem that the edge user has low communication quality,a decode-and-forward relay can be deployed in the system.So,the signal is transmitted to the user stably.First,the cumulative distribution function of the signal-to-noise ratio of the user is calculated,then obtain the outage probability of the user.Simulation experiments show that some key parameters in the system,such as the transmit power of the cognitive base station,the distance between the cognitive base station and the relay and the power allocation factor,have a significant impact on the user's outage probability.