The Research On Energy Efficiency And Spectrum Efficiency Optimization Of NB-IoT

Narrow band of Internet of Things(NB-IoT)technology is widely used in scenarios such as smart city,smart agriculture and smart transportation because of its advantages of large connectivity,low power consumption,wide coverage and low cost.However,with the increasing number of access devices and the influence of factors such as NB-IoT distance and device deployment requirements,it is easy to cause network signal fading and serious energy consumption,thus making the quality of service of NB-IoT edge users not well satisfied.In addition,with the increasing number of access devices,the allocation of spectrum resources also puts forward higher demands.With the advent of the 5th Generation(5G)era,Nonorthogonal Multiple Access(NOMA)technology and Simultaneous Wireless Information and Power The application of energy harvesting technology represented by Non-orthogonal Multiple Access(NOMA)and Simultaneous Wireless Information and Power Transfer(SWIPT)can realize the requirement of common transmission of multiple types of services and reduce network energy consumption.In order to meet the requirements of 5G network objectives and user quality of service,this paper focuses on NB-IoT energy efficiency and spectrum efficiency optimization issues,and proposes SWIPT-NOMA-based NB-IoT energy efficiency analysis and NOMA-based NB-IoT spectrum efficiency optimization research,the main research contents are as follows:(1)For the NB-IoT downlink relay SWIPT-NOMA network model,idle users are used as relays to assist long-distance users to realize data transmission,and at the same time,SWIPT technology is introduced in the relay devices,and since the assistance of relays also increases the power consumption,then power control is needed for such users to ensure that the network maintains a high Energy Efficiency(EE).In order to achieve efficient data transmission while improving EE,this paper proposes a rational allocation algorithm of spectrum resources based on SWIPT-NOMA.A nonlinear fractional programming problem with the objective of maximizing the energy efficiency of end users is established.Due to the nonconvexity of the objective function and the coupling between parameters,this paper uses fractional programming and sequential convex approximation theory to solve the problem.First,the maximum energy efficiency is determined by the dichotomous method,and then the optimal transmit power of the base station is solved by the sequential convex approximation,and the optimal configuration parameters of the system are determined according to the objective function.The above algorithm is iterated several times until convergence to obtain the optimal solution.The simulation results in MATLAB platform show that the proposed algorithm can improve the energy efficiency of the system and is better than the Orthogonal Multiple Access(OMA)technique in terms of energy efficiency.(2)For the NB-IoT downlink relay NOMA network model,the NOMA-based resource allocation strategy is designed to optimize the spectrum efficiency of NB-IoT devices with the objective of NB-IoT device spectrum efficiency,consider the minimum demand of data rate of NB-IoT devices,take into account the relationship between balanced energy efficiency and spectrum efficiency,and establish the resource allocation problem model with joint power allocation and parameter configuration,through Dinkelbach’s iterative algorithm for power control,the golden partitioning algorithm to optimize the power partitioning factor,the transmit power and power allocation factor optimization into a univariate optimization problem,and then the iterative algorithm is used to solve the maximum value of spectral efficiency under the objective function constraint.Finally,the improvement of spectrum resource utilization between the algorithm proposed in this paper and NB-IoT in practical applications is compared by simulation experiments,and the algorithm has lower complexity and is close to the optimal solution of power allocation,which is significantly better than Orthogonal Multiple Access in terms of spectrum efficiency and further improves network performance.