Research On Resource Allocation Scheme In NOMA Downlink

With the continuous expansion of the global mobile Internet population and the increasing use time per capita,the wireless communication technology in the new era needs to have higher spectral efficiency(SE),meet larger-scale user / device connection,provide faster data transmission rate,etc.The traditional orthogonal multiple access(OMA)technology has gradually failed to meet the needs of users.Different from orthogonal multiple access technology,non orthogonal multiple access(NOMA)can allocate resources non orthogonally,so as to expand the connection scale and improve the spectrum utilization.Therefore,NOMA is considered as the key technology in the fifth generation mobile communication system.This paper mainly studies the downlink resource allocation algorithm of NOMA system in order to improve the total throughput of the system.The main research work and results are as follows:1.A dynamic clustering algorithm for downlink users in NOMA system based on adaptive genetic algorithm is proposedA user clustering scheme based on dynamic clusters is proposed,so that the number of NOMA clusters and the number of users in the cluster are adaptively changed with the simulated environment.This scenario will be closer to the actual situation.In addition,this paper applies genetic algorithm to optimize user dynamic clustering in NOMA network.In order to improve the problems of slow convergence speed and easy to fall into local optimum of standard genetic algorithm,this paper proposes an improved genetic algorithm with adaptive adjustment parameters.Specifically,the suboptimal cooperation heuristic method is used to generate the initial population,and the system throughput is used as the fitness function value to participate in the subsequent selection,crossover and mutation operations.The roulette selection method is used,and the change of the fitness function value is used to timely The size of the crossover and mutation probability is adjusted so that the algorithm can converge to the global optimum better and faster.The simulation results show that the proposed algorithm can effectively reduce the complexity of the solution and obtain suboptimal system performance.2.A low-complexity base station-oriented sub-optimal sub-channel allocation algorithm is proposedThis paper mainly studies the sub-channel allocation problem in multi-cell multi-carrier non-orthogonal multiple access networks,and the goal is to maximize the total system throughput of the downlink of multi-cell multi-carrier NOMA systems.First,the optimization problem is decoupled into two sub-problems: the sub-channel assignment problem and the power assignment problem;then,the proportional power assignment algorithm is used to simplify the optimization problem into a single base station-oriented sub-channel assignment problem.In order to solve the above problems,this paper proposes a sub-optimal sub-channel allocation algorithm for multi-cell multi-carrier NOMA systems.Specifically,a definition of weighted interference distance is given first;then a sub-channel allocation scheme filtering algorithm is proposed based on the definition.It is used to narrow the optimization range for solving the optimization problem and shorten the problem solving time;finally,the sub-optimal sub-channel allocation scheme is traversed from the filtered sub-channel allocation scheme.The simulation results show that the algorithm proposed in this paper can effectively reduce the complexity of the solution and obtain sub-optimal system performance,and its advantages are more obvious in complex scenarios.