Research On Resource Allocation Optimization For Energy Efficiency And Secrecy Rate In Downlink Systems

This paper focuses on the resource allocation optimization problem for energy effi-ciency and secrecy rate in the downlink system.In order to solve the above problems,the paper proposes the robust beamforming design for secure multiuser MISO interference channel and energy-efficiency joint power and bandwidth allocation for NOMA system to solve it.Firstly,this paper studies the problem of secure beamforming design for multi-user multiple-input single-output interference channels.The interference channel has K pairs oflegitimate transmitters and receivers and an eavesdropper,and also has incomplete chan-nel state information.This problem is primarily concerned with beamforming design is-sues in order to maximize the minimum worst case secrecy rate subject to the transmit power constraints with norm bounded channel uncertainty.Obviously,the problem is non-convex and difficult to solve.Therefore,we propose an effective method.By explot-ing the conservative approximation and the sequential convex approximation methods,the above non-convex problems are reformulated as a series of tractable convex optimization problems with linear matrix inequalities and second-order cone constraints.The approx-imate convex problem is solved iteratively,and finally the approximate optimal solution of the original problem is obtained.The simulation and comparison are carried out on the algorithm.The simulation results demonstrate the effectiveness of the proposed robust al-gorithm.This paper also considers the energy-efficiencyjoint power and bandwidth allocation for NOMA system.The problem is a downlink based on non-orthogonal multiple access(NOMA)system in which a base station(BS)simultaneously communicates with multiple users,each user share the subchannels5,non-orthogonal multiple access technology is im-plemented on each subchannels and FDMA is carried out between different subchannels.The frequency division multiple access technique is adopted.In this problem power and bandwidth allocation are jointly optimized to maximize system energy efficiency(EE)at the transmit power constraints at the BS and minimum rate constraints for individual users.Since the objective function is a fractional form and a non-convex constraint,the optimiza-tion problem is non-convex.In order to solve the original non-convex problem,we first convert it into an equivalent DC(differential of two convex functions)program by intro-ducing slack variables,and then an iterative algorithm based on the constrained concave-convex procedure is proposed to solve it.Our numerical results demonstrate that the pro-posed algorithm has better EE performances compared to the NOMA scheme with equal-bandwidth allocation and conventional orthogonal multiple access scheme.