Resource Allocation For Cognitive Cooperative NOMA Networks

With the rise of the short video,online shopping,and other apps,people's demand for mobile data traffic is increasing,which brings challenges such as high data rate and spectral efficiency,large-scale connection,and low latency to the existing communication network.Right now,spectrum resources are very limited.However,cooperative non-orthogonal Multiple Access(NOMA)and cognitive radio can be combined to improve spectral efficiency.But,the organic combination of cognitive radio,NOMA,and cooperative communication is an open question.This paper focuses on resource allocation for cognitive cooperative NOMA networks.In this thesis,a new cooperative NOMA(C-NOMA)strategy is proposed for the single-carrier two-user cognitive Cooperative NOMA network,in which the Secondary User(SU)with good channel condition is used as receiver and relay between transmitter and weak User,so as to improve the receiving reliability of weak user with poor channel condition.This C-NOMA way is applied to the multi-carrier multi-user cognitive cooperative NOMA network.Since many SUs are randomly distributed,the performance of more weak users can be guaranteed.Resources are also allocated jointly between the primary and secondary networks.The proposed C-NOMA is applied to both networks.This ensures the performance of weak users in each network.It is worth noting that SU has the flexibility to change the transmission mode,as it can be a relay receiver to help weak users in two networks or just a receiver in a secondary network.In this system,Orthogonal Frequency Division Multiplexing Access(OFDMA)technology is applied to make SU use spectrum discontinuously and improve spectrum utilization.In addition,this paper studies the resource allocation of multi-carrier and multi-user cognitive C-NOMA network,and constructs an optimization function for spectrum efficiency.It is divided into two subproblems due to non-convex,namely user selection,and power allocation.The corresponding optimization scheme is as follows: users choose to adopt matching algorithms;Power distribution uses the standard difference of convex(DC)algorithm.Besides,the system performance is analyzed under the condition of perfect channel state information(CSI)and imperfect CSI.In addition,the tradeoff between energy and spectral efficiency is simulated.Through the simulation analysis,we can see that the proposed transmission way can improve spectral efficiency,fairness,and increase the number of effective access users.