Research On Resource Allocation Of NOMA Based On MMTC

Massive Machine Type of Communication(mMTC),as one of the three main scenarios of the upcoming fifth-generation wireless mobile communication(5G)and the typical scenario of the Internet of Things,will provide massive connections for largescale devices.While the Internet of Everything brings opportunities,new requirements are placed on spectrum utilization,transmission delay and data throughput.In order to cope with these challenges,Non-orthogonal multiple access(NOMA)can improve spectrum efficiency and reduce signaling overhead by utilizing the new dimensional power domain,which is more advantageous in supporting massive connections.Resource management has also become a hot research issue in the field of wireless communications.This paper takes mMTC in the Industrial Internet of Things as the background and NOMA as the technical support.It studies the system throughput,fairness and power consumption from the perspectives of user scheduling,power control,time slot allocation and grouping strategy.The main work and contributions of this paper are as follows:Aiming at the characteristics of uplink communication with low transmission rate of large-scale sensor nodes in industrial IoT scenarios,a joint non-orthogonal-time division multiple access communication mode is proposed.The system allows multiple sensor nodes to transmit data in the same time-frequency resource block,and divides the available time into time slots with different lengths and assigns them to different sensors for different modes of transmission.At the same time,optimization problems of joint user scheduling,time allocation and power control were developed to maximize the system's sum ?utility.In addition,the equivalent D.C.equation is used to solve the original non-convex optimization problem,and the joint non-orthogonal-time division multiple access D.C.programming is proposed to obtain the optimal solution in a finite number of iterations.The simulation results show that the proposed joint nonorthogonal-time division multiple access communication mode is superior to traditional orthogonal multiple access in spectrum utilization and fairness.Aiming at the performance and complexity requirements of the deployment when supporting multi-sensor nodes for simultaneous NOMA communication,a grouping strategy based on interference aware is proposed.In the system,sensor nodes in the same group transmit data through NOMA while orthogonal resource allocation is performed among different groups.Considering the quality of service constraints of the sensor nodes,an optimization problem that minimizes system power consumption is established.Starting from the principle of continuous interference cancellation,the interference power consumption function is determined for the sensor node,and the interference graph is constructed based on the interference perception to describe the influence of the sensor node replacement group on the system performance.In addition,a suboptimal low complexity algorithm for fast search of negative loops is proposed to reduce system power consumption.The simulation results show that the proposed algorithm can effectively reduce the system transmit power and support the diverse service quality requirements of different devices.