Research On Power Allocation Scheme Of NOMA System

With the rapid development of the mobile Internet,5G have spawned a variety of new services to meet different needs,but the problem of scarce spectrum resources has become more and more concerned.In order to improve spectrum resource utilization and system efficiency,NOMA technology emerges as the times require and becomes one of the candidate technologies for access technology of next-generation communication systems.The technology mainly introduces a power domain,so that users can multiplex on the same time-frequency resources,increase the number of users that the system can access,differentiate users by power difference between users,improve spectrum efficiency,and ensure fairness among users.In the non-orthogonal multiple access technology system,user scheduling and power allocation will directly affect system performance,which is one of the hot research directions of NOMA.The main work of this thesis includes:1.A NOMA user pairing scheme based on channel gain difference is proposed.The scheme first establishes the priority assigned by the user on the subcarrier and gives a new user pairing scheme to reduce the scheduled sample space.In terms of power allocation,iterative water injection power allocation algorithm and FTPA algorithm are used to perform sub-carrier power allocation and sub-carrier internal power allocation.The simulation results show that the proposed system performance is significantly better than the traditional resource allocation scheme,and the complexity of the scheduling process is reduced.2.A NOMA multi-user scheduling scheme based on weighted proportional fair scheduling is proposed.The scheme considers long-term fairness and short-term fairness,introduces a weighting factor,and uses the weighted PF metric to select the best user combination in each scheduling time slot.The simulation results show that compared with the traditional PF scheduling algorithm,the proposed algorithm improves the system throughput and ensures the fairness of users.3.A NOMA dynamic resource allocation scheme based on deletion criteria is proposed.The scheme firstly gives the optimal power allocation algorithm for users under the fixed subcarrier allocation matrix to achieve the optimization goal of maximizing the total transmission rate of the system under the condition of limited transmit power.Furthermore,a deletion criterion based on rate contribution ratio is proposed.The criterion is used to iteratively update the subcarrier allocation matrix and the corresponding power allocation matrix to complete the allocation of NOMA dynamic resources.The simulation results show that compared with the traditional resource allocation algorithm,the new algorithm improves the total transmission rate of the system and reduces the computational complexity.